Dissertations / Theses on the topic 'Leeches'
To see the other types of publications on this topic, follow the link: Leeches.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Leeches.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Martin, A. J. "Lake-dwelling leeches : coexistance and population regulation." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317192.
Full text
2
Seaby, Richard M. H. "Coexistence of lake-dwelling triclads and leeches." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317274.
Full text
3
Procter, R. M. "The feeding ecology of three species of lake-dwelling leeches." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380088.
Full text
4
Reese, David R. "Neuropilar synaptogenesis between identified central neurons in vivo." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0007/MQ44256.pdf.
Full text
5
Merz, David C. (David Christian). "Synapse formation between identified leech neurons." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28848.
Full textAbstract:
The formation of patterns of functionally appropriate chemical synapses is one of the key aspects of nervous system development. I have investigated the cellular interactions that culminate in the formation of an inhibitory synapse between the R and P neurons of the leech. These neurons may be isolated and maintained in culture, where they reform synaptic connections under easily manipulable conditions. An early event in the formation of this synapse is the loss from sites of contact in the postsynaptic P cell of an excitatory response to the transmitter serotonin. The loss of this response was triggered specifically by contact with the presynaptic R neuron, and not by contact with other leech neurons, including other serotonergic neurons. Furthermore, contact with the R neurons of the reproductive ganglia, which do not innervate P cells, was also ineffective in causing the loss of response. This highly specific cellular interaction was prevented by treatment of the R cell surface with the proteolytic enzyme trypsin or with the lectin wheat germ agglutinin (WGA), suggesting involvement of an R cell surface glycoprotein. WGA blocked not only the loss of the excitatory response, but also prevented the formation of the R-P synapse. An antibody library against the R cell generated using a novel phage-display system produced antibodies which bound to subsets of leech neurons, including the R neurons, but none of these was specific for the R cells. I conclude that an early event in the formation of the R-P synapse is the recognition by the P cell of its correct synaptic partner through an R cell-specific surface molecule.
6
Munro, Roger Cameron. "Anti - haemostatic properties of the Hirudinea." Thesis, Open University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317381.
Full text
7
Jacob, Cristina. "Use of the bioconcentration capability of leeches to evaluate chlorophenol pollution." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26298.
Full textAbstract:
The objective of this research was to investigate the use of leeches as in situ monitors of the biological availability of chlorophenols and degree of contamination in the North Arm of the Fraser River Estuary, British Columbia, where chlorophenols are used as wood preservatives by several forest industry operations. The objective was accomplished by : 1) an integrated series of grab and continous samples to determine the spatial and temporal variability in chlorophenol contamination, 2) in situ and laboratory experiments to compare leech bioconcentration to water levels of pollutants and to determine environmental factors( temperature, pH, leech size) that regulate and affect bioassay interpretation.
Grab samples were not representative of the average level of pollution in the river. High concentrations such as the one reported for Mitchell Island on October 4 (11 ppb TTCP and 2.25 ppb PCP) could give a false impression of the pollution level in the river. Also, plumes of high concentration of chlorophenols could be missed easily if the sampling time does not coincide with the pollutant discharge.
High frequency( every 2 hours) automatic water sampling showed a high variability in chlorophenol contamination( 0.278 ppb to 3.678 ppb TTCP for the March 31- April 6 field experiment) which demonstrated . the sporadic nature of chlorophenol discharges. Changes in the river flow also affected the level andthe pattern of chlorophenol variation. A method capable of integrating concentration versus time seemed to be the only way to elucidate the irregular pattern of pollutant levels.
Leeches were exposed to the contaminants by submersion in cages at various locations along the North Arm. On the basis of the levels of chlorophenols found in the leech, estimation of the average chlorophenol concentration in the water were made. Concentrations as high as 3.2 9 ug/g TTCP and 1.11 ug/g PCP were found in leeches exposed in the Mitchell Island area( TTCP and PCP were the only chlorophenols found in the area of study at any time during our sampling program carried out between August 1984 and September 1985). An average concentration higher than 2 ppb TTCP and 2 ppb PCP was estimated in the water for the duration of the leech exposure( 7 days) at that location using bioconcentration levels determined in the laboratory.
Laboratory experiments showed that lower pH increased
bioconcentration of chlorophenols. Higher bioconcentration
factors were achieved at higher temperatures and regression equations( R= 0.96 to 0.99) were calculated for the five chlorophenols used in the experiments( 2,4-DCP; 2,4,5-TCP; 2,4,6-TCP; 2,3,4,6-TTCP and PCP). Temperature affected the time needed to achieve steady state which was 4 days at 4 C, 5 days at 12 C and 7+ days at 22 C. Four out of the five chlorophenols tested( 2,4-DCP exhibited different bioconcentration characteristics) were bioconcentrated to the same level by leeches, regardless of their Po/w values. This contradicted the linear, relationships established by various researchers between the bioconcentration factor and Po/w of various compounds including chlorinated phenols in other organisms.
Recommendations for setting up a method to use leeches in a
biomonitoring program of the chlorophenol pollution in the Fraser
River Estuary are proposed from the results of this research. The
cost of the analyses using a biomonitoring program could be an order of magnitude lower than an adequate water sampling program to assess the chlorophenol pollution level.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
8
Hayes, Polly May. "Gnathiids, leeches and blood protozoans of marine fishes : morphological, pathological, developmental and molecular approaches." Thesis, Kingston University, 2007. http://eprints.kingston.ac.uk/20385/.
Full textAbstract:
Haematophagous, metazoan ectoparasites and protozoan blood parasites of intertidal fishes from Wales and South Africa formed the main focus of this study. The ectoparasites examined were largely juvenile isopods of the genus Gnathia, and specimens ofthe leech, Zeylanico~della arugamensis. These taxonomically distinct ectoparasites were suspected vectors of the blood protozoans, and the latter were mostly apicomple{(ans of the genus Haemogregarina and euglenozoans ofthe genus Trypanosoma. Knowledge of digestive tract anatomy in juvenile gnathiids is essential for assessing their role as potential vectors and this system was examined using histological, microscopical and computer-based techniques. Features that had been unreported, or insufficiently recorded, previously' included several structures within the dorsal afid ventral stomach chambers, a typhlosolelike formation in the anterior hindgut, haemozoin-like deposits in the digestive caeca of Gnathia africana and Gnathia pantherina, and an extensive gut flora. Connections between the stomach, anterior hindgut and digestive caeca were identified, salivary gland ducts were followed towards the mouthparts, and the digestive cycles of Gnathia maxillaris and G. africana juveniles were examined over a period of 30 days. The pathology associated with the attachment sites of G. africana and Gnathia sp A to teleosts, and with G. pantherina to an elasmobranch, was found to be considerable in the case of G. pantherina, while Gnathia sp A prompted the death ofits host unde: experimental conditions. Oocyst stages, presumed to be those ofHaemogregarina bigemina, were ,' . located in sections through the digestive caeca of G. africana, confirming the vector status ofthe isopod. Development stages of a new species, Haemogregarina curvata, were observed in the leech, Z. arugamensis, and within peripheral blood smears from several fishes. The life cycle oftrypanosomes found in Z. arugamensis and in fishes was also established, although interpreting the morphometries ofthese flagellates was challenging and speciation proved difficult. Identical molecular sequences oftrypanosomes were derived from separate leech samples and these were close to published sequences for marine fish trypanosomes. Thus, both gnathiids and leeches were likely vectors ofthe fish blood protozoans. Finally, probable dual transmission of a haemogregarine and trypanosomes by a leech was illustrated, a rare event, reported infrequently in the literature.
9
Nelson, Sandahl Hygeia. "Effects on motor neuron development of altering peripheral targets in embryonic leeches (Hirudo verbana)." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1473082.
Full textAbstract:
Thesis (M.S.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed Feb. 1, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 31-32).
10
Ching, Shim. "Synaptogenesis between identified neurons." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55449.
Full textAbstract:
Serotonergic Retzius (R) neurons of the leech Hirudo medicinalis in culture reform inhibitory synapses with pressure sensitive (P) neurons while selectively reducing an extrasynaptic, depolarizing response to serotonin (5-HT) in the P neuron. We have examined if the selection of 5-HT responses is restricted to sites of contact between processes and growth cones of these cells. As measured by intracellular recording at the soma, focal application of 5-HT depolarized uncontacted P cell bodies, neurites and growth cones but not processes contacted by R cells. In patch clamp recordings of the depolarizing channels, application of 5-HT modulated channel activity in uncontacted but not in contacted growth cones. The selection of transmitter responses during synaptogenesis is therefore localized to discrete sites of contact specifically between synaptic partners.Prior experiments have shown that tyrosine kinases play a crucial part in the selection of responses to 5-HT that occurs in the P cell (Catarsi and Drapeau, 1993). To further examine the mechanism responsible for this change in transmitter responses, we have utilized a monoclonal antibody against phosphotyrosine to determine if tyrosine phosphorylation could be detected in P and R cell pairs placed in contact. Our results revealed bright, punctate cytoplasmic staining in P cells paired with R cells.
Embryonic leeches were used to examine how R to P synaptogenesis proceeds in vivo. By filling the R and P neurons with different fluorescent dyes (Lucifer Yellow and Rhodamine-Dextran), confocal microscopy established that putative contact between neuropilar processes were made as early as 11 days of development. Spontaneous, chloride-dependent synaptic potentials in embryonic P cells similar to those seen in adult P cells were observed as early as day 10 of development.
11
Bonilla, Victoria. "The Succubus and the Suckers: the Soul-Siphoning Leeches in the Stories of Modernist Text." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1851.
Full textAbstract:
This paper explores the various relationships found in John Steinbeck's "Of Mice and Men," Tennessee Williams's "A Streetcar Named Desire," Franz Kafka's "The Metamorphosis," and F. Scott Fitzgerald's "Tender is the Night." The exploration of each demonstrates the common theme of parasitic relations and the toll this dynamic takes on the persons involved.
12
Iwama, Rafael Eiji. "Sanguessugas parasitas da ordem Rhyncobdellida (Clitellata: Hirudinida) do território brasileiro." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-03042018-094107/.
Full textAbstract:
Sanguessugas são importantes componentes da comunidade de macroinvertebrados bentônicos, podendo ser parasitas ou predadoras. Apesar das propriedades terapêuticas relacionadas à secreção salivar destes animais serem conhecidas por milênios, pouca atenção taxonômica foi dada ao grupo, principalmente em regiões como América do Sul, África e Ásia. O objetivo deste trabalho foi de inventariar a hirudofauna parasita da ordem Rhyncobdellida do território brasileiro e aplicar novas técnicas de estudo taxonômico, que não são recorrentes para o grupo. Além das observações da morfologia interna e externa através de dissecções e esteomicroscópio, foi realizado o estudo do tegumento através de microscopia eletrônica de varredura e microtomografia computadorizada para o estudo anatômico. Foram encontradas 7 espécies válidas e 7 espécies novas para a ciência. As ocorrências dos gêneros Oligobdella e Placobdella são discutidas em detalhe e é sugerida a criação de dois novos gêneros, para acomodar as espécies parasitas de Glossiphoniidae bianuladas e trianuladas da América do Sul. O gênero Austrobdella é registrado pela primeira vez para o Atlântico Sul, na costa do Rio de JaneiroLeeches are important components of the macroinvertebrates community and they have parasitic or predatory behavior. Although the therapeutic properties related to the salivary secretion are known for thousands of years, little attention was given to taxonomic studies, especially in South America, Africa and Asia. The present study aims to explore the diversity of parasitic rhyncobdelid leeches in Brazil and apply new technologies to the taxonomic study of this group. Besides the classic observation on the internal and external morphology using dissection and a stereomicroscope, Scanning Electron Microscopy and Microcomputed tomography were used to access the fine structure of the tegument and the internal morphology, respectively. seven known species and 7 species new to science were found. The occurrences of Oligobdella and Placobdella are discussed and the description of two new genera is suggested, to accommodate biannulate and triannulate parasitic glossiphonid species from South America. The genus Austrobdella is reported for the first time to the Southern Atlantic, from the coast of Rio de Janeiro
13
Williams, Julianne I. "Monograph of the North American freshwater fish leeches (Oligochaeta: Hirudinida ; Piscicolidae) and molecular phylogeny of the family Piscicolidae." W&M ScholarWorks, 2007. https://scholarworks.wm.edu/etd/1539616905.
Full textAbstract:
The phylogeny of the Piscicolidae was analyzed from combined sequence data of 18S rDNA, cytochrome c oxidase subunit I (CO-I), nicotinamide adenine dinucleotide dehydrogenase subunit I (ND-I), and morphological data using parsimony. A worldwide distribution of Pisciolidae was represented for the first time in a phylogenetic analysis. While the family Piscicolidae was supported as a monophyletic group, the traditional subfamilies based on morphology were not supported. The Platybdellinae was polyphyletic and formed four distinct clades, and Bathybdella sawyeri did not group with any other platybdellids. The Piscicolinae was also polyphyletic, also forming four distinct clades. The pontobdellid genus Stibarobdella was shown to be the basal taxon within the Pisciolidae; however, the Pontobdellinae was found to be paraphyletic if Oxytonostoma was included. The genera Aestabdella, Austrobdella, and Malmiana were found to be paraphyletic; the genera Calliobdella, Cystobranchus, and Platybdella were found to be polyphyletic. The species Myzobdella lugubris was not found to be monophyletic. It is proposed that Oxytonostoma be removed from the Pontobdellinae, that Aestabdella be synonymized with Pterobdella, that Calliobdella vivida, Cystobranchus mammillatus, Cystobranchus meyeri, Cystobranchus salmositicus, and Cystobranchus virginicus be reassigned to Gonimosobdella, and that Piscicolaria be synonymized with Myzobdella. The synonymy of Malmiana and Heptacyclus is confirmed, with Heptacyclus having priority. Piscicola milneri is confirmed to be a separate species from Piscicola geometra. Eleven species of freshwater leeches from North America are redescribed. The description of Gonirnosobdella mammillata is emended to correctly describe the conducting tissue and atrium. The reassignment of Piscicola sahnositica to Cystobranchus and now Gonirnosobdella is confirmed on the basis of the conducting tissue arrangement and absence of mycetomes. The description of Gonirnosobdella virginica is emended to include information on pigmentation, conducting tissue, accessory gland cells, coelomic system, and mycetomes. The reproductive and coelomic systems of Gonimosobdella meyeri, Myzobdella reducta, Piscicola milneri, and Piscicola punctata are reported for the first time.
14
Browne, Carol. "Impacts of urbanisation and metal pollution on freshwater turtles." Thesis, The University of Sydney, 2005. http://hdl.handle.net/2123/4009.
Full textAbstract:
Over 85% of Australia’s population live in urban areas and many turtle populations occur on Australia’s east coast where urban development is particularly concentrated. In the state of NSW, over half of the freshwater coastal wetlands have been highly modified or completely destroyed, and urban freshwater creeks often have only a narrow strip of weedy bushland left along their banks. Even though habitat degradation may result in declines in density and distribution of turtle populations, there are few data on Australian freshwater turtles in urban areas. In addition to extreme habitat alteration, urban waterways are innundated with anthropogenic contaminants from sources including wet weather surface runoff and industrial and sewage discharges. Pollutants can impact all systems of the body with potentially severe effects on reproduction and survival that can result in deterioration of animal populations. Turtles are particularly susceptible to anthropogenic contaminants due to their intimate contact with the aquatic environment, an often high trophic level, their ability to accumulate toxins, and their longevity. For almost all contaminants, the degree of accumulation in and effect on reptile species is unknown. Sublethal effects in field situations are particularly poorly studied and have never been documented in pleurodiran turtles. As a pioneering work in Australian reptile ecotoxicology, this thesis takes a broad approach, but focuses primarily on immunotoxicity and reproductive toxicity – two areas that greatly impact the size and continuance of animal populations. The aim of the thesis is to provide baseline data on haematology, cellular immunology and tissue metal concentrations for freshwater turtles in Sydney – data which were lacking for all Australian turtle species prior to this study. After initial assessment of the distribution and density of freshwater turtles in Sydney, the study examines the potential for Sydney’s turtles as sentinel species for measuring the effects of pollution on haematology, cellular immunity, and parasite loads; and considers the relationships between urban metal pollution and reproductive variables. The relative suitability of non-lethally sampled tissues (blood, carapace, egg) for use in biomonitoring is also assessed. Three species of Australian freshwater turtles were found in the Sydney region, with Chelodina longicollis occurring naturally in the area, and populations of Emydura macquarii and Elseya latisternum likely to have originated from translocated individuals. The North American turtle Trachemys scripta elegans was not encountered during this study despite concerns that it was establishing in the Sydney area. Chelodina longicollis populations were widespread, although poor recruitmment was indicated by low capture rates and comparatively low percentage of juveniles at some sites. Not so widespread, Emydura macquarii was present in much larger numbers than C. longicollis and with a high juvenile component in some areas of southeastern Sydney. I provide information on erythrocyte and leucocyte parameters in C. longicollis over a range of sites, pollution conditions, and seasons. In C. longicollis, numbers of lymphocytes, heterophils and eosinophils varied over sites, but not due to pollution from sewage treatment plant outfalls. There was significant temporal variation in erythrocyte, lymphocyte, eosinophil, heterophil, and basophil number, the heterophil:lymphocyte ratio, and haematocrit, but not consistently among sites. Future studies should ensure simultaneous sampling across sites for comparative purposes. Similarly, turtle populations downstream of sewage treatment plant outfalls showed no consistent difference in number, body condition, blood haemogregarine load, or leech (haemogregarine vector) load from upstream populations. Leech (Helobdella papillornata, with some Placobdella sp.) load and haemogregarine numbers increase dramatically once C. longicollis reach a carapace of 110 mm. The number of leeches on turtles varied across season, year, and site. Turtles with large numbers of leeches had reduced haematocrit, but the presence of leeches had no other correlations with haematological parameters. Haemogregarine numbers did not change across season or year, and were not correlated with haematological variables. The hypothesis that pollutants lead to an increase in normal blood protozoa due to reduced immunity thus was not supported. The concentration of metals in C. longicollis and E. macquarii carapace and in lagoon sediments varied significantly over four urban and four national park sites, but not based on this split. Pollution in periurban areas, such as illegal dumping of toxic wastes and atmospheric deposition of pollutants, means that each site must be classified separately as to degree of metal pollution. There was little or no affect of species, size, sex, or gravidity on metal concentrations in the carapace of adult turtles. Emydura macquarii had higher concentrations of blood Fe than C. longicollis from a different site, but this is possibly due to an increase in haemoglobin resulting from the site’s low aquatic oxygen concentration rather than any increased environmental exposure. Chelid turtles in Sydney do not show much promise as a biomonitoring tool. Carapace analysis is largely discounted as a potential tool for metal biomonitoring due to poor correlations between potentially toxic metals in non-lethally samplable tissues (carapace, claw) and internal organs (liver, kidney) or bone (femur). However, carapace metal concentrations still potentially reflect long-term metal presence or different dietary exposures as evidenced by the significant variation in concentrations over sites. A rare correlation was found for concentrations of aquatic Pb and carapace Pb, and a correlation was also found for concentrations of blood Pb and carapace Pb in E. macquarii. Thus any potential for tissue biomonitoring seems to lie with this highly ecotoxicologically relevant metal. Although two other ecotoxicologically relevent metals, Cu and Se, were significantly higher in egg contents of C. longicollis compared to E. macquarii, these elements are also essential and a lack of baseline values means it is not known if this simply reflects natural taxonomic variation. Ni, a metal of toxicological concern in sea turtles, was not present in egg contents, and only variably present in eggshell. The absence of Pb from eggs, despite its presence in many maternal tissues, suggests that selective metal uptake into eggs may be protective of toxic elements, rather than eggs serving as a maternal method of toxic metal elimination as has been previously suggested. The paucity of toxic metal detection in eggs renders them unlikely tissues for biomonitoring. The maternal tissue or tissues or environmental source from which egg metals originate remains obscure, although a significant negative effect of maternal carapace concentrations of Ca and Mg on eggshell thickness in E. macquarii indicates that there may be mobilisation of Ca and Mg from the carapace for eggshell formation. The only metal whose eggshell concentration correlated with eggshell thickness was Mg, indicating that ecotoxic metals previously associated with eggshell thinning are not problematic in the Sydney chelids. As with North American turtles living at polluted sites, none of the chelid hatchlings were found to have any overt abnormalities. Hatching success was poor and hatching mass low for eggs of both C. longicollis and E. macquarii, although results from natural nests are required to determine whether or not this was an outcome of hormonally-induced oviposition and artificial incubation. It is difficult to interpret metal concentrations found in the soft tissues, calcified tissues, and eggs of chelonians due to the paucity of comparative data, and much more research is required on tissue metal concentrations before patterns will emerge. This especially applies to pleurodires for which no previous information is available. From comparisons with the limited data available for other freshwater turtles, marine turtles, and other aquatic reptiles, it does not appear that Sydney’s turtle populations have unusually high metal concentrations in tissues. Exclusion of toxic metals such as Pb from the egg may also be protective to the developing embryo. An ability to live in polluted habitats, while limiting the accumulation of toxic contaminants, may be one key to their persistence in urban waterways from which other freshwater fauna have disappeared. Reproductive impacts such as low embryo survival and small hatchling weights require more rigorous examination, but may have less effect on these animals which have such naturally high egg and hatchling mortality. Although it was generally hard to demonstrate biochemical, physiological or population impacts of contaminants, C. longicollis from a site with severe sewage pollution did display unusual alterations in a number of haematological variables, body condition, and carapace bone structure. Despite this, the population was large and had a comparatively high ratio of juveniles. Additionally, the adverse haematological alterations appeared reversible. Thus, successful populations in Sydney probably are more dependent on basic ecological needs being met, than on low levels of environmental contaminants. The ongoing persistence of chelid populations in Sydney is likely to be dependent to some extent on their opportunistic diets, which generally make animals less vulnerable to habitat modification and the reduction in prey item diversity following pollution (Mason 1996, Allanson & Georges 1999), with a further benefit possibly bestowed at some sites on E. macquarii by its omnivory.
15
Browne, Carol. "Impacts of urbanisation and metal pollution on freshwater turtles." University of Sydney, 2005. http://hdl.handle.net/2123/4009.
Full textAbstract:
Doctor of Philosophy (PhD)Over 85% of Australia’s population live in urban areas and many turtle populations occur on Australia’s east coast where urban development is particularly concentrated. In the state of NSW, over half of the freshwater coastal wetlands have been highly modified or completely destroyed, and urban freshwater creeks often have only a narrow strip of weedy bushland left along their banks. Even though habitat degradation may result in declines in density and distribution of turtle populations, there are few data on Australian freshwater turtles in urban areas. In addition to extreme habitat alteration, urban waterways are innundated with anthropogenic contaminants from sources including wet weather surface runoff and industrial and sewage discharges. Pollutants can impact all systems of the body with potentially severe effects on reproduction and survival that can result in deterioration of animal populations. Turtles are particularly susceptible to anthropogenic contaminants due to their intimate contact with the aquatic environment, an often high trophic level, their ability to accumulate toxins, and their longevity. For almost all contaminants, the degree of accumulation in and effect on reptile species is unknown. Sublethal effects in field situations are particularly poorly studied and have never been documented in pleurodiran turtles. As a pioneering work in Australian reptile ecotoxicology, this thesis takes a broad approach, but focuses primarily on immunotoxicity and reproductive toxicity – two areas that greatly impact the size and continuance of animal populations. The aim of the thesis is to provide baseline data on haematology, cellular immunology and tissue metal concentrations for freshwater turtles in Sydney – data which were lacking for all Australian turtle species prior to this study. After initial assessment of the distribution and density of freshwater turtles in Sydney, the study examines the potential for Sydney’s turtles as sentinel species for measuring the effects of pollution on haematology, cellular immunity, and parasite loads; and considers the relationships between urban metal pollution and reproductive variables. The relative suitability of non-lethally sampled tissues (blood, carapace, egg) for use in biomonitoring is also assessed. Three species of Australian freshwater turtles were found in the Sydney region, with Chelodina longicollis occurring naturally in the area, and populations of Emydura macquarii and Elseya latisternum likely to have originated from translocated individuals. The North American turtle Trachemys scripta elegans was not encountered during this study despite concerns that it was establishing in the Sydney area. Chelodina longicollis populations were widespread, although poor recruitmment was indicated by low capture rates and comparatively low percentage of juveniles at some sites. Not so widespread, Emydura macquarii was present in much larger numbers than C. longicollis and with a high juvenile component in some areas of southeastern Sydney. I provide information on erythrocyte and leucocyte parameters in C. longicollis over a range of sites, pollution conditions, and seasons. In C. longicollis, numbers of lymphocytes, heterophils and eosinophils varied over sites, but not due to pollution from sewage treatment plant outfalls. There was significant temporal variation in erythrocyte, lymphocyte, eosinophil, heterophil, and basophil number, the heterophil:lymphocyte ratio, and haematocrit, but not consistently among sites. Future studies should ensure simultaneous sampling across sites for comparative purposes. Similarly, turtle populations downstream of sewage treatment plant outfalls showed no consistent difference in number, body condition, blood haemogregarine load, or leech (haemogregarine vector) load from upstream populations. Leech (Helobdella papillornata, with some Placobdella sp.) load and haemogregarine numbers increase dramatically once C. longicollis reach a carapace of 110 mm. The number of leeches on turtles varied across season, year, and site. Turtles with large numbers of leeches had reduced haematocrit, but the presence of leeches had no other correlations with haematological parameters. Haemogregarine numbers did not change across season or year, and were not correlated with haematological variables. The hypothesis that pollutants lead to an increase in normal blood protozoa due to reduced immunity thus was not supported. The concentration of metals in C. longicollis and E. macquarii carapace and in lagoon sediments varied significantly over four urban and four national park sites, but not based on this split. Pollution in periurban areas, such as illegal dumping of toxic wastes and atmospheric deposition of pollutants, means that each site must be classified separately as to degree of metal pollution. There was little or no affect of species, size, sex, or gravidity on metal concentrations in the carapace of adult turtles. Emydura macquarii had higher concentrations of blood Fe than C. longicollis from a different site, but this is possibly due to an increase in haemoglobin resulting from the site’s low aquatic oxygen concentration rather than any increased environmental exposure. Chelid turtles in Sydney do not show much promise as a biomonitoring tool. Carapace analysis is largely discounted as a potential tool for metal biomonitoring due to poor correlations between potentially toxic metals in non-lethally samplable tissues (carapace, claw) and internal organs (liver, kidney) or bone (femur). However, carapace metal concentrations still potentially reflect long-term metal presence or different dietary exposures as evidenced by the significant variation in concentrations over sites. A rare correlation was found for concentrations of aquatic Pb and carapace Pb, and a correlation was also found for concentrations of blood Pb and carapace Pb in E. macquarii. Thus any potential for tissue biomonitoring seems to lie with this highly ecotoxicologically relevant metal. Although two other ecotoxicologically relevent metals, Cu and Se, were significantly higher in egg contents of C. longicollis compared to E. macquarii, these elements are also essential and a lack of baseline values means it is not known if this simply reflects natural taxonomic variation. Ni, a metal of toxicological concern in sea turtles, was not present in egg contents, and only variably present in eggshell. The absence of Pb from eggs, despite its presence in many maternal tissues, suggests that selective metal uptake into eggs may be protective of toxic elements, rather than eggs serving as a maternal method of toxic metal elimination as has been previously suggested. The paucity of toxic metal detection in eggs renders them unlikely tissues for biomonitoring. The maternal tissue or tissues or environmental source from which egg metals originate remains obscure, although a significant negative effect of maternal carapace concentrations of Ca and Mg on eggshell thickness in E. macquarii indicates that there may be mobilisation of Ca and Mg from the carapace for eggshell formation. The only metal whose eggshell concentration correlated with eggshell thickness was Mg, indicating that ecotoxic metals previously associated with eggshell thinning are not problematic in the Sydney chelids. As with North American turtles living at polluted sites, none of the chelid hatchlings were found to have any overt abnormalities. Hatching success was poor and hatching mass low for eggs of both C. longicollis and E. macquarii, although results from natural nests are required to determine whether or not this was an outcome of hormonally-induced oviposition and artificial incubation. It is difficult to interpret metal concentrations found in the soft tissues, calcified tissues, and eggs of chelonians due to the paucity of comparative data, and much more research is required on tissue metal concentrations before patterns will emerge. This especially applies to pleurodires for which no previous information is available. From comparisons with the limited data available for other freshwater turtles, marine turtles, and other aquatic reptiles, it does not appear that Sydney’s turtle populations have unusually high metal concentrations in tissues. Exclusion of toxic metals such as Pb from the egg may also be protective to the developing embryo. An ability to live in polluted habitats, while limiting the accumulation of toxic contaminants, may be one key to their persistence in urban waterways from which other freshwater fauna have disappeared. Reproductive impacts such as low embryo survival and small hatchling weights require more rigorous examination, but may have less effect on these animals which have such naturally high egg and hatchling mortality. Although it was generally hard to demonstrate biochemical, physiological or population impacts of contaminants, C. longicollis from a site with severe sewage pollution did display unusual alterations in a number of haematological variables, body condition, and carapace bone structure. Despite this, the population was large and had a comparatively high ratio of juveniles. Additionally, the adverse haematological alterations appeared reversible. Thus, successful populations in Sydney probably are more dependent on basic ecological needs being met, than on low levels of environmental contaminants. The ongoing persistence of chelid populations in Sydney is likely to be dependent to some extent on their opportunistic diets, which generally make animals less vulnerable to habitat modification and the reduction in prey item diversity following pollution (Mason 1996, Allanson & Georges 1999), with a further benefit possibly bestowed at some sites on E. macquarii by its omnivory.
16
Huguet, i. Blanco Gemma. "Mecanismes cel·lulars en la curació de ferides a Hirudo medicinalis." Doctoral thesis, Universitat de Girona, 1994. http://www.tdx.cat/TDX-0723108-131052.
Full textAbstract:
S'estudia la histologia normal de la paret corporal d'Hirudo medicinalis i els canvis morfogenètics que es donen durant el procés de cicatrització de ferides per incisió, cauterització i nitrat de plata.El procés de curació de ferides a Hirudo medicinalis consta d'una fase de formació d'un tap cel·lular, el pseudoblastema, d'un procés de reepitelització i de la formació d'un teixit cicatricial, com en els altres hirudinis estudiats (Myers, 1935; LeGore i Sparks, 1971; Cornec, 1984). Hem observat també el fenomen de la contracció de la ferida que permet l'acostament dels marges de la ferida.
Formació i evolució del pseudoblastema
El pseudoblastema, a diferència d'altres espècies estudiades, està format per un sol tipus cel·lular: les cèl·lules vasocentrals, provinents del teixit vasofibrós, una especialització del teixit connectiu. Aquestes cèl·lules estan capacitades per realitzar les diferents funcions que en espècies rincobdèl·lides realitzen diferents tipus cel·lulars. En concret: taponament de la ferida a través de la formació del pseudoblastema, fagocitosi dels teixits necrosats i regeneració, almenys d'una part, de la matriu connectiva cicatricial. També són responsables de la contracció de la ferida.
Les cèl·lules vasocentrals en el seu estadi de repòs es troben en el teixit vasofibrós formant agrupacions coherents, però sense mostrar unions intercel·lulars especialitzades visibles en ME. La coherència del grup queda assegurada per les interdigitacions entre les cèl·lules vasocentrals i probablement per unions tipus adherens o especialitzades. Les unions amb la matriu són de tipus adherens. Aquestes cèl·lules vasocentrals presenten feixos de filaments d'actina força conspicus.
En produir-se una ferida les cèl·lules vasocentrals s'activen, desconnecten les unions intercel·lulars i amb la matriu i migren cap a la zona afectada, on s'acumulen. El pseudoblastema actua com un tap cel·lular que funciona de forma eficient per tancar la ferida en un plaç de temps relativament curt. El pseudoblastema forma un teixit coherent amb unions intercel·lulars tipus adherens, caracteritzades per material electrodens en la cara intracitoplasmàtica, feixos de filaments d'actina que hi convergeixen i espais intercel·lulars petits, de 17-20 mm, atravessats per petites fibril·les.
Un cop finalitzat el procés de reepitelització, es produeix una contracció de la ferida. Es produeix per la retracció del pseudoblastema cap a l'interior de l'animal. El pseudoblastema disminueix la seva amplària i arrossega els teixits contigus provocant un tancament. La força motriu que provoca la retracció i l'arrossegament dels teixits vindria donada per la presència dels filaments d'actina a les cèl·lules del pseudoblastema, els quals durant aquesta fase es tornen mes conspicus. La presència d'unions intercel·lulars especialitzades característiques de la fase de contracció, està relacionada amb la transmissió de la força de tensió. Aquestes unions connecten els feixos de filaments d'actina de les cèl·lules amb la matriu o d'una cèl·lula a altre a través d'espais intercel·lulars força amples en els que s'observa material electrodens.
Reepitelització
L'epitelització s'inicia quan el pseudoblastema està consolidat i segueix el mateix patró que la reepitelització de ferides en epitelis monoestratificats de vertebrats (Stem i DePalma, 1983, és a dir, per migració de tota la capa per sobre del substrat, segons l'anomenat model de lliscament.
Les glàndules unicel·lulars mucoses del tegument degeneren abans de produir-se la migració epitelial i posteriorment, un cop consolidat l'epiteli a sobre de la ferida, es diferencien a partir de les cèl·lules epitelials.
Durant l'epitelització es produeixen canvis importants en el citosquelet i les unions basals de les cèl·lules epitelials. En canvi, el complex d'unió lateral es manté durant tot el procés. En iniciar-se la migració els tonofilaments es desconnecten dels hemidesmosomes cuticulars i dèrmics i es reagrupen al voltant del nucli, a la vegada que els hemidesmosomes dèrmics es desconnecten de la làmina basal. Un cop acabada la migració, les cèl·lules epitelials estableixen unions basals amb les cèl·lules del pseudoblastema. Aquestes unions no són hemidesmosomes sinó que presenten el mateix aspecte que les unions intercel·lulars del pseudoblastema. Els hemidesmosomes no es tornen a formar fins que les cèl·lules epitelials han restablert la membrana basal.
La regeneració de la membrana basal no s'inicia fins que no s'ha començat a regenerar matriu connectiva a la zona cicatricial.
Regeneració de la cicatriu
Al mateix temps que es dona el fenomen de contracció, s'observa regeneració de la matriu connectiva entre les cèl·lules del pseudoblastema. Aquestes cèl·lules són responsables almenys del recobriment fibrós que presenten en aquest estadi, durant el qual mostren sàculs del reticle endoplasmàtic rugós molt dilatats, característics de cèl·lules que secreten constituents de la matriu. A més, s'observa infiltració de matriu connectiva i processos citoplasmàtics dels fibròcits en els marges del pseudoblastema.
En la matriu del teixit connectiu normal s'observen fibres que estan constituïdes per un còrtex de fibril·les col·làgenes organitzades al voltant dels processos citoplasmàtics dels fibròcits. Les fibres del teixit connectiu peridigestiu, d'uns 1,2-1,9 mm de diàmetre, presenten el còrtex prim, amb les fibril·les organitzades paral·lelament a l'eix de la fibra. En canvi, les fibres de la dermis i teixit connectiu intramuscular, d'uns 2,5-7,1 mm de diàmetre, tenen el còrtex gruixut, amb fibril·les que s'organitzen paral·lelament en la zona proximal a la medul·la i de forma desorganitzada en la part més distal.
Als 8 mesos la cicatriu encara és detectable. La matriu cicatricial presenta fibres connectives del tipus prim i força material fibril·lar desorganitzat disposat laxament. S'observa colonització per part de fibròcits, cromatòfors, petites fibres musculars i nervis.
This thesis in a study of the morphogenetic events that occurs during wound healing of Hirudo medicinalis and of the normal histology of the body wall.
The wound healing process of Hirudo medicinalis involves the formation of a cellular plug, the reepithelialization and the regeneration of a scar tissue, as in the others hirudineans previously studied (Myers, 1935; LeGore and Sparks, 1971; Cornec 1964). We also report the wound contraction process that allows the wound clousure.
After a wound is inflicted cells of the connective tissue migrate to form a cellular plug, the pseudoblastema. The pseudoblastema of Hirudo medicinalis formed only by one type of cell: the vasocentral cells. In the resting state those cells are associated with vasofibrous cells forming the vasofibrous tissue.
Once the pseudoblastema has been formed, then reepithelialization begins. The epithelium of the wound edges advances as a unified sheet like the monolayered epithelia of Vertebrata (Stenn and DePalma, 1988). Unicellular mucous glands of the integument degenerate until epithelial migration. Later, once the epithelium has been consolidated over the wound, some epithelial cells differentiate into mucous glands.
After the wound has been reepithelializated, wound contraction occurs by the retraction of the pseudoblastema.
In the later stages, infiltration of fibrocite citoplasmic projections can be observed. The pseudoblastema disintegrates and an extracellular matrix remains in its place. This matrix is colonized by fibrocites, capillary vessels, nerves and little muscular fibers. The body wall muscular fibers sectioned or splitted don't regenerate. The extracellular matrix of the scar zone can be distinguished from the normal one for long periods (8 months at least).
An important fact of the work is the role of the vasocentral cells. Those cells are responsible for the formation of the pseudoblastema and for the phagocitosis of the remnants of injures tissue. They are also responsible for the wound contraction, presenting acting filaments alinied with the stress direction and specialized intercellular junctions that transmit tension force. Finally, they contribute to the scar matrix regeneration by the synthesis of a fibrous cell coat.
17
Vongsombath, Chanda. "Botanical Repellents and Pesticides Traditionally Used Against Haematophagous Invertebrates in Lao PDR." Doctoral thesis, Uppsala universitet, Systematisk biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-149991.
Full textAbstract:
Haematophagous parasites and disease vectors such as leeches, ticks, mites, lice, bed bugs, mosquitoes, and myiasis-causing fly larvae are common health problems in Lao Peoples Democratic Republic (Lao PDR). A main aim of my field work in Lao PDR in 2006-2010 was to document traditional knowledge among different ethnic groups about plants that people use to repel or to kill blood-feeding invertebrates. We carried out structured interviews in 66 villages comprising 17 ethnic groups, covering a range of ethnic group, throughout Lao PDR and recorded a total of 92 plant species - in 123 different plant-ectoparasite combinations - that are used as traditional repellents and/or as “pesticides” to kill "pest" invertebrates. Traditional use was confirmed in the scientific literature for 74 of these plant species, and for an additional 13 species based on literature on closely related species. We concluded that repellents and pesticides from many plant species are commonly used in the Lao countryside. We also investigated traditionally used Lao plants for their activity to repel or to kill certain disease vectors and parasites. Target organisms were mosquitoes (Diptera, Culicidae), fly larvae (Diptera, Cyclorrhapha) in fermented fish production, and terrestrial blood-sucking leeches (Hirudinea, Haemadipsidae). The potential mosquito repellent activities of essential oils of Croton roxburghii (Euphorbiaceae), Hyptis suaveolens (Lamiaceae), and Litsea cubeba (Lauraceae) were evaluated in the field near Vientiane. Oils at concentrations of 1.7-6.7 µg/cm2 were significantly repellent to Aedes, Armigeres and Culex attracted to human baits. The activities against fly larvae, infesting fermenting fish, of three plant species, Tadehagi triquetrum (Fabaceae), Uraria crinita (Fabaceae) and Bambusa multiplex (Poaceae) were investigated: When fresh material of the plants was added on top of fermenting fish infested with fly larvae significant proportions of the larvae were repelled or killed. The total protective effect, i.e., repellent and killing effect combined, of T. triquetrum, U. crinita, and B. multiplex was 60-83 %, 77-90 %, and 60-93 %, respectively. Field evaluation of the potential leech repellent activities of water extracts of Sapindus rarak (Sapindaceae), Catunaregam spathulifolia (Rubiaceae) and Vernonia elaeagnifolia, (Asteraceae) impregnated on stockings and worn by persons in two leech-infested biotopes revealed leech repellent activities of 82.6%, 62.6% and 63.0%, respectively. The corresponding repellencies of deltamethrin and diethyl-3-methyl-benzamide (DEET) were 73.1% and 88.4%, respectively. Identification of the active components in certain of the plants with the ultimate aim to develop more optimal, less costly repellents, insecticides, acaricides, and anti-leech compounds as alternatives to synthetic repellents and pesticides against blood-feeding insects, ticks, mites, and leeches is in progress.
18
Molina, Julia Pereira 1985. "Caracterização da infecção por tripanossomatídeos (Protozoa: Kinetoplastida) presentes em três espécies de cascudo (Pisces: Loricariidae) do Rio Mogi-Guaçu, SP." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315169.
Full textAbstract:
Orientador: Marlene Tiduko UetaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-17T04:30:52Z (GMT). No. of bitstreams: 1 Molina_JuliaPereira_M.pdf: 1442066 bytes, checksum: e8ad2a162950fbe267341b74c08ad0f7 (MD5) Previous issue date: 2010
Resumo: Os tripanossomas já foram reportados em diversas espécies de peixes de água salgada e doce, sendo a maioria das espécies descritas com base nas características morfológicas. Tripanossomas parasitos de peixes são heteroxenos e são transmitidos por hirudíneos. Este trabalho tem como objetivos caracterizar a prevalência e densidade da infecção por Trypanosoma sp. presentes no sangue de três espécies de cascudos do rio Mogi Guaçu, Cachoeira de Emas, município de Pirassununga, SP e caracterizar morfologicamente e por técnicas moleculares os exemplares de Trypanosoma encontrados no sangue dos cascudos. Entre fevereiro de 2008 e fevereiro de 2009 foram coletados 256 exemplares de cascudos sendo 60 Hypostomus albopunctatus, 100 Hypostomus regani e 96 Hypostomus strigaticeps. O sangue foi coletado por punção cardíaca e alíquotas de 8?l foram retiradas para confecção de esfregaço em camada delgada, que foram fixados em metanol e corados por Giemsa, para a determinação da positividade e densidade dos tripanossomas. Após a biometria e coleta do sangue os peixes foram marcados e metade foi acondicionada em um tanque de criação do CEPTA/ ICMBIO para verificação da manutenção da infecção e o restante foi devolvido ao rio. A prevalência geral de tripanossomas foi de 47,6 % e densidade média geral de 0,75 parasitas/ µl de sangue. A prevalência ao longo do ano apresentou diferenças significativas apenas para Hypostomus regani (p=0,0054) e Hypostomus strigaticeps (p=0,0007). A densidade média de parasitas não apresentou diferenças significativas entre as três espécies de peixes analisados, assim como a variação mensal da densidade por espécie de peixes. Hirudíneos do gênero Placobdella sp. foram coletados da superfície do corpo e da boca de H regani e H. strigaticeps para extração do DNA, os oligonucleotídeos utilizados (S-1842 e S-1843) amplificaram um fragmento de 1000pb do gene 18S rRNA dos tripanossomas isolados de hirudíneos coletados em H regani e H. strigaticeps. Dos 19 peixes recapturados após dois meses apenas três se mantiveram positivos. Foram medidos 255 tripanossomas sendo 66 de H. albopunctatus, 64 de H. regani e 95 de H. strigaticeps e os valores foram comparados com os de outras espécies de tripanossomas encontradas em peixes do gênero Hypostomus. Os parasitas encontrados nas três espécies de peixes apresentaram características morfológicas semelhantes. Foi estabelecida a frequência de ocorrência de acordo com a variação do comprimento do corpo para evidência de pleomorfismo. Os dados morfológicos mostram que Trypanosoma sp.1 e Trypanosoma sp.2 podem ser considerados de espécies diferentes; as análises evidenciaram a presença de pleomorfismo nos tripanossomas encontrados nas três espécies de peixes.
Abstract: Trypanosomes have been reported in several species of fish that inhabit salt and fresh waters. The majority of these protozoan species are described based on morphologic features. The parasites are heteroxenic and are transmitted by leeches. This work aims to characterize the prevalence and density of infection by Trypanosoma sp. present in the blood of three species of armored catfish collected from Mogi Guaçu river (Cachoeira das Emas, Pirassununga city, SP) and characterize morphologically and by molecular techniques the trypanosomes found in the blood of catfish. Between february 2008 and february 2009, 256 specimens of armored catfish were collected, being 60 Hypostomus albopunctatus, 100 Hypostomus regain, and 96 Hypostomus strigaticeps. The blood was collected by cardiac puncture and a sample of 8µl was removed to realize blood smears on microscope slides. The slides were fixed in methanol and stained with giemsa for posterior analysis on light microscopy for determination of positive presence and density of trypanosomas. After biometric analysis and blood collection fish were marked half of the fish marked were maintened in a tank of CEPTA/ ICMBIO for future verification of the infeccion maintence and the other half were retorned to the river. It was found a prevalence of 47,6% and the average density of 0,75 parasitas/µl of blood. The prevalence during the year presented significative differences only for Hypostomus regani (p=0,0054) e Hypostomus strigaticeps (p=0,0007). The average density of parasites showed no significant differences among the three fish species analyzed and the monthly variation of density per species of fish. Also, leeches of the genus Placobdella sp. were collected from the surface of the body and mouth of armored catfish for DNA extraction. The primers used (S-1842 and S- 1843) amplified a 1000bp fragment of the 18S rRNA gene of trypanosomes isolated from leeches collected in H regani and H. strigaticeps. Of the 19 fish recaptured after two months only three remained positive. Therein, 255 trypanosomes were measured being 66 H. albopunctatus, 64 H. regani and 95 H. strigaticeps and values were compared with those of other parasite species found in different species of fish. The parasites found in the three species of fish presented similar morphological characteristics. The frequency of occurrence was established according to the variation in body length as evidence of pleomorphism. Nevertheless morphological data show that Trypanosoma sp.1 and Trypanosoma p.2 can be considered distinct species, the analysis revealed the presence of pleomorphism in trypanosomes found in the three species of fish.
Mestrado
Parasitologia
Mestre em Parasitologia
19
Mohammed, Sirajuddin. "PERFORMANCE EVOLUTION OF PEER TO PEER NETWORKS." Thesis, Högskolan Dalarna, Datateknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-3959.
Full textAbstract:
This thesis work concerns about the Performance evolution of peer to peer networks, where we used different distribution technique’s of peer distribution like Weibull, Lognormal and Pareto distribution process. Then we used a network simulator to evaluate the performance of these three distribution techniques.During the last decade the Internet has expanded into a world-wide network connecting millions of hosts and users and providing services for everyone. Many emerging applications are bandwidth-intensive in their nature; the size of downloaded files including music and videos can be huge, from ten megabits to many gigabits. The efficient use of network resources is thus crucial for the survivability of the Internet. Traffic engineering (TE) covers a range of mechanisms for optimizing operational networks from the traffic perspective. The time scale in traffic engineering varies from the short-term network control to network planning over a longer time period.Here in this thesis work we considered the peer distribution technique in-order to minimise the peer arrival and service process with three different techniques, where we calculated the congestion parameters like blocking time for each peer before entering into the service process, waiting time for a peers while the other peer has been served in the service block and the delay time for each peer. Then calculated the average of each process and graphs have been plotted using Matlab to analyse the results
20
Baxter, Euan W. "Homeobox containing genes in the leech." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/19982.
Full textAbstract:
Leech embryos have been used in developmental studies for over 100 years and continue to be used because of a number of unique and useful features. There is a large amount of detailed information on the highly stereotyped cellular events that take place during leech development, and recent work has shown that it is possible to study some of the genes in leech that have been shown to exert developmental effects in other species. This thesis presents that sequence of two fragments of homeobox genes which were generated from leech Helobdella robusta by polymerase chain reaction. These genes have been named Lox 7 and Lox 8. Some preliminary in situ hybridization data suggests that the Lox 7 gene is expressed in the germinal plate of stage 9 embryos. A genomic library was constructed from Helobdella robusta DNA and screened with the Lox 7 and Lox 8 fragments. A control screening was carried out with Lox 2. These experiments proved that the Lox 7 and Lox 8 genes were not represented in the library. Positives were obtained from the control screening of the Helobdella robusta genomic library and were investigated further. Evidence is presented that some of these clones do not contain the gene used to make the probe (Lox2), but may contain other homeobox genes. Positive clones were gained from the screening of a Helobdella robusta cDNA library with the leech engrailed gene. The clones show that the mRNA from the engrailed gene is alternatively spliced.
21
Andjelic, Sofija. "Calcium dynamics and compartmentalization in leech neurons." Doctoral thesis, SISSA, 2005. http://hdl.handle.net/20.500.11767/4078.
Full textAbstract:
The aim of this project was to study how and where action potentials arise and propagate in the arborizations of identified neurons in the central nervous system of the leech. A major aim was to assess whether the entry of calcium is localized to distinct regions of the cells and to determine whether there are significant differences in calcium channel distribution between different types of neurons. A combination of electrophysiological techniques, optical recording and image analysis was used to approach these problems. I developed an experimental set-up for optical recordings of calcium transients by a fast CCD-camera. By use of calcium sensitive dyes I analysed in detail optical responses to electrical stimulation of neurons and the density of calcium channels, spatially and temporarily, in different neural cell types, including mechanosensory neurons and motoneurons. Fluorescence changes (∆F/F) of the membrane impermeable calcium indicator Oregon Green were measured. The dye was pressure injected into the soma of neurons under investigation. ∆F/F caused by a single action potential (AP) in mechanosensory neurons had approximately the same amplitude and time course in the soma and in distal processes. By contrast, in other neurons such as the Anterior Pagoda neuron, the Annulus Erector motoneuron, the L motoneuron and other motoneurons, APs evoked by passing depolarizing current in the soma produced much larger fluorescence changes in distal processes than in the soma. When APs were evoked by stimulating one distal axon through the root, ∆F/F was large in all distal processes, but very small in the soma. These results confirm and extend previous electrophysiological data which demonstrate that the soma of a motoneuron in the leech, as in many other invertebrates, does not generate action potentials (Stuart, 1970; Muller and Nicholls, 2 1974; Goodman and Heitler, 1979). Impulses recorded in the soma are normally only a few millivolts in amplitude. The AP of a motoneuron propagates to muscles of the body wall along segmental nerves that emerge from ganglia. The site of impulse initiation has been found to be at a distance from the soma but within the ganglion (Melinek and Muller, 1996; Gu et al. 1991). Our experiments with fluorescent transients are in accord with the concept that they result from calcium entry through voltage sensitive channels. Thus at sites where APs are found to be large, the calcium signals are large (as in peripheral axons), while at sites where spikes are small, (as in motoneuronal cell bodies) signals were weak, or non existent.
22
Spelling, S. M. "Studies on the predators and parasites of three species of lake-dwelling leech." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356281.
Full textAbstract:
In the present study, the incidence and effects of predation and parasitism on three species of lake-dwelling leech, viz. Erpobdella octoculata, Glossinhonia complanata and Helobdella stagnalis Were investigated. A literature survey was carried out, and produced a wide range of studies which reported leeches in the diet of predators. The majority of such records were for fish from lakes and rivers, but a few records from waterfowl were also reported. Simple laboratory experiments demonstrated that a wide range of invertebrate and vertebrate predators may feed on both adult and young leeches. Field collections of these predators were taken and examined, using visual and serological techniques to establish what had been eaten. Positive evidence for predation in the field was provided by this work, but the incidence and intensity of predation was found to be very low. Field experiments, using predator exclusion methods in the stony littoral of a eutrophic lake, were carried out but failed to show any marked changes in leech mortality or population dynamics. The parasites of leeches collected from fifteen lakes in England and North Wales were surveyed and five species recorded. These parasites were the microsporidians, Nosema herpobdellae and Nosema glossiphoniae, and the trematodes, Apatemon gracilis, Cotylurus cornutus and Cyathocotyle opaca. Only A. gracilis and C. cornutus were previously reported from British leeches. The microsporidian species were re-described, using electron microscopy. Detailed studies on the incidence of the parasites were carried out in leeches from a eutrophic lake, and a limited amount of evidence for parasite-induced host mortality and a reduction in the fecundity of infected leeches was presented.The findings of the present work are discussed in relation to previous studies on leech populations, and to other mechanisms that may serve to control and regulate these populations. It is concluded that, whilst causing some mortality, predation and parasitism play a minor role in the control and regulation of the leech populations in the stony littoral of eutrophic lakes. it is suggested that the availability of food, particularly to young leeches, may be a more important factor, and certainly one that deserves future attention.
23
Cacciatore, Timothy William. "Optical, behavioral, and computational analyses of leech locomotion /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9943951.
Full text
24
Spalding, Adrian. "The ecology of the Sandhill Rustic moth Luperina nickerlii leechi in Cornwall." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25935.
Full text
25
Pennington, A. J. "Glycogenolysis and gluconeogenesis in the segmental ganglia of the leech Haemopis sanguisuga (A)." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384113.
Full text
26
Malek, Julie Anne. "Voltage-gated sodium channels and nerve regeneration in the leech." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410686.
Full text
27
Verrall, Jason. "Studies on the regeneration of the leech central nervous system." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270723.
Full text
28
Thomson, Eric E. "How the leech and its nervous system discriminate touch location /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3144324.
Full text
29
Liu, Chan-Yueh. "Marcher (Bùxíng步行), une danse ? : L'acte de marcher dans la pratique chorégraphique : l'exemple du travail de la taiwanaise Lin Leechen, inspirée par la culture chinoise." Thesis, Paris 8, 2014. http://www.theses.fr/2014PA080030.
Full textAbstract:
Cette thèse est d’une approche ethnographique de la notion de l’acte de marcher et son application dans la danse, avec en particulier les pratiques créatives de la chorégraphe taiwanaise Lin Leechen林麗珍, issues de la pensée et de la culture chinoises. L’objectif principal est, d’une part, de saisir les caractéristiques de ce mouvement dans la danse et comment cette action de locomotion a inspiré les chorégraphes ; d’autre part, de connaître ses interprétations et ses valeurs dans le travail de Lin Leechen, ce qui se présente comme un exemple de cette problématique. La procédure utilisée est l’analyse de l’application de l’acte de marcher dans quatre formes de spectacles, dans des créations chorégraphiques contemporaines et dans les conceptions personneless des chorégraphes de notre époque. Pour atteindre l’objectif fixé, nous nous penchons d’abord sur les liens de ce geste avec l’ être humain, son corps et ses usages dans la vie quotidienne, puis sur la pratique de ce mouvement dansant et son interprétation dans des créations chorégraphiques et dans des entretiens de chorégraphes. Nous analysons enfin des entraînements à la marche de Lin Leechen et ses principes phrases chorégraphiques utilisant la marche dans sa trilogie de création : Jiào醮 (Miroirs de vie), Huā shénjì花神祭 (Hymne aux fleurs qui passent). Quān觀 (Chants de la destinée)This thesis is the result of ethnographic research into the act of walking, its application in dance and practical implementation in the creations of Taiwanese choreographer Leechen Lin, which draw on Chinese philosophy and culture. The main objective is to understand how the movement is used in dance and how it inspires choreographers. It also explains how it is interpreted and its value in the work of Leechen Lin, presented as an illustration. The approach is to analyse the act of walking in four types of representation in contemporary choreography and from the personal perspective of contemporary choreographers. It first explores how human beings relate to walking in terms of their body and use in everyday life, and then how the movement is integrated into dance and interpreted in choreographers' creations and perspectives. Finally, it analyses Leechin Lin's coaching of walking and choreographic phrases in her trilogy
30
Miller, Chandra Nikole. "IMPLEMENTATION OF MEDICINAL LEECH PREPARATION TO INVESTIGATE THE CONNECTION BETWEEN THE MOTOR NEURON AND MUSCLE FIBER VIA SHARP ELECTRODE ELECTROPHYSIOLOGY." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/645.
Full textAbstract:
There are forty registered organophosphates in the United States and they range from pesticides and insecticides to nerve agents or neurotoxins such as sarin. Organophosphates (OP’s) have been used in chemical warfare for years and tend to lead to death due to an attack on the nervous system. Chemical assays and mass microscopy have been used to assess the concentration of OP’s in the environment, but both methods require the body to metabolize the OP first, which can be detrimental to the victim. It is crucial to come up with a method to investigate and detect these neurotoxins without causing harm first.
There have been several studies presented in the literature that use medicinal leeches and sharp electrode electrophysiology to study the function of the motor end plate. Kuffler, Potter and Stuart have all conducted studies using the medicinal leeches to do so. They mapped out the cells within the leech ganglion as well as created an atlas of the entire leech anatomy, and demonstrated the electrical connection between the motor neuron and longitudinal muscle fibers. Using the knowledge they have provided, a medicinal leech and sharp electrode electrophysiology can be used to investigate the effects of organophosphates on the nervous system. Before this can be achieved a dissection preparation must be implemented that can be utilized in electrophysiological experiments and that demonstrates the electrical connection between the motor neuron and muscle fibers.
This thesis outlines the implementation of the medicinal leech dissection preparation described above. The preparation removes one ganglion from the leech, leaving the roots attached to the portion of the muscle wall it innervates. To demonstrate the preparations validity, sharp electrode electrophysiology is performed using a current clamp and discontinuous single electrode voltage clamp (dSEVC). A current pulse stimulates the motor neuron and a voltage recording is obtained from the ganglion as well a current recording from the muscle wall. The electrical connection is therefore demonstrated. This dissection preparation and electrophysiology experiment are written up in a procedural manner so that another individual could repeat the experiment. The next logical step would be to use these procedures to perform OP nerve agent experiments to investigate the effect of OP’s on the neuromuscular junction.
31
Lehmkuhl, Andrew M. II. "Characterizing the mechanoreception of water waves in the leech Hirudo verbana." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1468509670.
Full text
32
Desjeux, Isabelle. "An investigation into the regulation of segment number in the leech." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/21196.
Full textAbstract:
The control of the number of segments is a problem posed in all segmented phyla: how can there be generation of a constant number of body parts? Here I have studied the leech embryo as an example of an animal where the number of segments is regulated. The leech develops in a stereotypical manner and gives rise, during the cleavage stage, to 5 pairs of teloblasts. These cells divide in a stem-cell manner, producing blast cells, the founders of the segmental body plan. The blast cells are produced one after the other, and stay ordered in such a way that the most anterior blast cells are the oldest and the most posterior the youngest. As they move anteriorly, the bandlets or columns of blast cells from the different lineages converge to form the germinal band. This results in an anteroposterior gradient of development. In most teloblast lineages, one blast cell populates one segment equivalent. However, more blast cells are born than there are segments. I have been used lineage tracing to study the fate of the cells that are eliminated in the process of segment regulation in the leech. In combination, I have been looking for genes that could be involved in such a process of number counting and boundary formation. My results confirm the presence of two types of blast cells, the segmental cells (that go on to form the segmental body) and the supernumerary cells (that die). They suggest (against what was previously thought), that blast cells do not need to be in contact with neighbours of the other lineages (i.e. the germinal band) to divide, but their presence in the germinal band is required for further divisions, and therefore making of segments. my results also show that the pair-rule gene hairy might not be implicated in setting up the boundary between segmental and supernumerary cells, but that the pair-rule gene patched might be indirectly implicated by being part of a signalling pathway between the segmented tissue and overlaying provisional epithelium.
33
Lewis, John E. "From touch localization to directed behavior : neural computation in the leech /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9805797.
Full text
34
Zhao, Bailey. "Cloning and expression of protein tyrosine kinases in the medicinal leech." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1464872.
Full textAbstract:
Thesis (M.S.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed July 7, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 50-53).
35
Briggman, Kevin L. "Optical imaging of neuronal population dynamics in the leech central nervous system." Diss., Connected to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3187817.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2005.Title from first page of PDF file (viewed March 6, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 74-79).
36
Garcia, Paul Anthony. "Modeling the Intersegmental Coordination of Heart Motor Neurons in the Medicinal Leech." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5064.
Full textAbstract:
We constructed a model of the coordination of segmental heart motor neurons driving blood circulation in leeches. The heart motor neuron models were conductance-based; conductances of voltage-gated and synaptic currents were adjusted to match the firing pattern of heart motor neurons from the living system. Each motor neuron receives a specific pattern of inhibitory input from rhythmic premotor heart interneurons and translates this spatiotemporal pattern into the fictive heartbeat motor pattern. The temporal pattern of synaptic input to the model was derived from extracellularly recorded spikes of the premotor heart interneurons. We focused on determining the components necessary to produce side-to-side asymmetry in the motor pattern: motor neurons on one side fire nearly in synchrony (synchronous coordination), while on the other they fire in a rear-to-front progression (peristaltic coordination). The model reproduces the general trends in phasing and was used to investigate the effective contribution of several synaptic and cellular properties of the motor neurons. The spatial and temporal pattern of premotor synaptic input, the electrical coupling between the segmental motor neurons, intra-burst, short-term synaptic plasticity of the synaptic inputs, and the axonal conduction delays all were integrated with the intrinsic membrane properties to influence intersegmental phasing.
37
Westcott, Fay Mostyn. "The effects of low-level chronic cadmium exposure on a freshwater leech." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq24710.pdf.
Full text
38
Gaudry, Quentin. "Mechanisms of behavioral choice in the nervous system of the medicinal leech." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3307002.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed June 25, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
39
Taylor, Andrew Wilfrid. "The social dimensions of Christian spirituality in the thought of Kenneth Leech /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65999.
Full text
40
Dean, J. A. "Pharmacology and physiology of identified neurones in the leech central nervous system." Thesis, University of Portsmouth, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373419.
Full text
41
Ries, David Christopher. "The effects of alpha-conotoxin Im1 on the intact, swimming medicinal leech." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p1459285.
Full textAbstract:
Thesis (M.S.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed November 5, 2008). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 41-42).
42
Todd, Krista L. "Formation of appropriate synapses in the nervous system of the medicinal leech." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3369589.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed September 15, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 120-134).
43
Arisi, Ivan. "Distributed processing underlying whole-body shortening in the leech central nervous system." Doctoral thesis, SISSA, 2000. http://hdl.handle.net/20.500.11767/4741.
Full text
44
Richardson, Philip Jonathan. "Sporadic geometries and their universal representation groups." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313684.
Full text
45
Slučkaitė, Asta. "Medicininės dėlės (Hirudo verbana) jauniklių elgesio tyrimai." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2011~D_20140627_171729-47680.
Full textAbstract:
Šio darbo tikslas buvo įvertinti medicininės dėlės (Hirudo verbana) jauniklių elgesį sudarant sankaupas, nustatyti sankaupų pokyčius laiko bėgyje bei veikiant terminiam ir šviesos dirgikliui. Vykdant uždavinį, ištirti jauniklių elgesį nuo jų išsiritimo iš kokonų momento iki pirmojo maitinimosi, buvo stebima, kad tik išsiritus jaunikliams iš kokonų, dar neperkėlus į vandenį, būdingos ryškios sankaupos 100% grupių. Perkėlus jauniklius į vandenį, labai trumpam dėl mechaninio poveikio, sankaupos iširsta, tačiau jau po 31,25±0.752 min. Išaiškinta, kad tiek mažo, tiek didelio tankio grupėms būdinga tendencija pirmąją savaitę sudaryti labai ryškias sankaupas, o su laiku jos pradeda irti. Lyginant šias grupes nustatyta, kad po 1 paros nuo išsiritimo negautas patikimas skirtumas tarp šių grupių, tačiau jau po 3 parų gautas patikimas skirtumas. Taip pat stebėti grupių sankaupų ryškumo skirtumai prieš maitinimąsi ir po. Gauta, kad statistiniai skirtumai yra labai patikimi nesvarbu kokio tankumo grupėse. Tyrimai parodė, kad sankaupų ryškumas grupėse, susidedančiose iš viename kokone buvusių jauniklių, nuo grupių, sudarytų iš įvairių kokonų jauniklių statistiškai nepatikimas. 640-670 lx apšvietimas stipriai paveikė dėles ir jos sudarė labai ryškias sankaupas. Rezultatai tarp eksperimentinių ir kontrolinių grupių yra labai patikimi. Tai dar kartą patvirtina neigiamą poveikį dėlėms, kurios pademonstravo ryškią apsauginę reakciją. Tiriant terminį poveikį jaunikliams, nustatyta vidutinė... [toliau žr. visą tekstą]The aim of the study is to evaluate behaviour of medicinal juvenile leeches (Hirudo verbana) by composing aggregation, establishing changes in aggregation during effect of time also applying thermic and light stimulus. During investigation of juvenile leeches behaviour from leaving the cocoon to first feeding, first aim was to observe juvenile leeches which has just left the cocoon bearing in mind that leeches cannot be moved into water. Characteristics of this observation were 100% groups’ aggregation. Moving juvenile into the water for a short period of time due to mechanical effect, aggregations separate fast after 31,25±0.752 min. Observation concludes, that both large and small density groups have a tendency to show intense aggregations and with time aggregations starts to separate. Comparing these groups it was determined that after 1 day since hatching, significant effect was not achieved between these groups, but after 3 days significant effect have been achieved. In addition, group aggregation difference was observed before and after feeding. Achievement was that statistical difference was accurate disputing density groups. Experiments showed that aggregation intensity in groups were composed out of juvenile leeches that were in the cocoon and groups that were composed out of different cocoons were statistically unreliable. 640-670lx illumination strongly affected leeches and they composed intense aggregations. Results showed that results between experimental and... [to full text]
46
Liu, Chan-Yueh. "Marcher (Bùxíng步行), une danse ? : L'acte de marcher dans la pratique chorégraphique : l'exemple du travail de la taiwanaise Lin Leechen, inspirée par la culture chinoise." Electronic Thesis or Diss., Paris 8, 2014. http://www.theses.fr/2014PA080030.
Full textAbstract:
Cette thèse est d’une approche ethnographique de la notion de l’acte de marcher et son application dans la danse, avec en particulier les pratiques créatives de la chorégraphe taiwanaise Lin Leechen林麗珍, issues de la pensée et de la culture chinoises. L’objectif principal est, d’une part, de saisir les caractéristiques de ce mouvement dans la danse et comment cette action de locomotion a inspiré les chorégraphes ; d’autre part, de connaître ses interprétations et ses valeurs dans le travail de Lin Leechen, ce qui se présente comme un exemple de cette problématique. La procédure utilisée est l’analyse de l’application de l’acte de marcher dans quatre formes de spectacles, dans des créations chorégraphiques contemporaines et dans les conceptions personneless des chorégraphes de notre époque. Pour atteindre l’objectif fixé, nous nous penchons d’abord sur les liens de ce geste avec l’ être humain, son corps et ses usages dans la vie quotidienne, puis sur la pratique de ce mouvement dansant et son interprétation dans des créations chorégraphiques et dans des entretiens de chorégraphes. Nous analysons enfin des entraînements à la marche de Lin Leechen et ses principes phrases chorégraphiques utilisant la marche dans sa trilogie de création : Jiào醮 (Miroirs de vie), Huā shénjì花神祭 (Hymne aux fleurs qui passent). Quān觀 (Chants de la destinée)This thesis is the result of ethnographic research into the act of walking, its application in dance and practical implementation in the creations of Taiwanese choreographer Leechen Lin, which draw on Chinese philosophy and culture. The main objective is to understand how the movement is used in dance and how it inspires choreographers. It also explains how it is interpreted and its value in the work of Leechen Lin, presented as an illustration. The approach is to analyse the act of walking in four types of representation in contemporary choreography and from the personal perspective of contemporary choreographers. It first explores how human beings relate to walking in terms of their body and use in everyday life, and then how the movement is integrated into dance and interpreted in choreographers' creations and perspectives. Finally, it analyses Leechin Lin's coaching of walking and choreographic phrases in her trilogy
47
Dykes, Iain Mackenzie. "A molecular study of regeneration in the CNS of the leech, Hirudo medicinalis." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249092.
Full text
48
Lipitz, Jeffrey Brian. "Cannabinoid Control of Microglial Migration." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/127.
Full textAbstract:
In both vertebrates and invertebrates, including leeches, microglia are rapidly activated by central nervous system (CNS) damage and migrate to the lesions. Adenosine triphosphate (ATP), nitric oxide (NO) and endocannabinoids have been implicated in controlling activation and migration, but details of the mechanisms are uncertain. This dissertation tests the hypothesis that endocannabinoids coordinate and influence the microglial response to nerve cord crushing. Chapter 1 reports that application of endocannabinoids to nerve cords at concentrations as low as 100 nM for arachidonylethanolamide (anandamide, or AEA) reduced the number of migrating microglia, but not when cords were pretreated with 10 µM of the CB2 cannabinoid receptor (CB2R) antagonist SR144528. In addition, immunoblots confirmed the expression of CB1-like and CB2-like receptors and immunohistochemistry showed that they were concentrated at lesions, where microglia accumulated. Benzoyl ATP (BzATP) also reduced microglia accumulation, an effect blocked by pretreatment of nerve cords with SR144528, whereas the G-protein coupled P2YR agonists uridine triphosphate (UTP) and methylthio-ATP (MeSATP) at 100 µM did not reduce accumulation. This result suggested that P2X7R activation elicited production and release of a CB2R agonist that influenced microglia movement. Chapter 2 reports that extracellular ATP levels were highest in the CNS within the first 30 min of injury and remained above unharmed controls for at least 2 hours. Application of 10 units (U) of the ATPase apyrase to nerve cords reduced accumulation of microglia at lesions, another indication that microglia require extracellular ATP to accumulate. Chapter 3 reports that AEA stopped ATP-induced movement of microglia, and that this effect was blocked by pretreatment of nerve cords with the CB1R antagonist SR141716A (10µM), the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L NAME, 2 mM) or the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-teramethylimidazoline-oxyl-3-oxide (carboxy-PTIO or cPTIO, 1 mM). Thus the migration of microglia to lesions is regulated not only by ATP acting on P2YR and by NO acting on soluble guanylate cyclase (sGC), but also potentially by ATP binding to P2X7-like receptors to increase the production of cannabinoids. Cannabinoids, binding to the CB1R and CB2R cause production of NO, which suppresses microglia movement.
49
Wilkinson, Tonia Jane. "An analysis of the molecular basis of neuronal regeneration in the leech, Hirudo medicinalis." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324196.
Full text
50
Caulfield, Jason Patrick. "Preparation for nerve membrane potential readings of a leech, laboratory setup and dissection process." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/130.
Full textAbstract:
A well documented laboratory setup, leech preparation process, and bio-potential data recording process are needed. Repeatability and quality data recordings are essential and thus dictate the requirements of the laboratory setup and processes listed above. Advances in technology have both helped and hindered this development. While very precise equipment is required to record the low voltage bio-potentials, noisy electronic equipment and wires surrounding the work area provide high levels of interference. Proper laboratory setup and data recording processes, however, limit the unwanted interference. Quality data can only be recorded from a properly handled and prepared leech subject. Proper setup and procedures result in quality recordings which lend a clean signal for furthering the understanding of nerve functionality. The electrophysiology lab at California Polytechnic State University in San Luis Obispo is an example of a proven lab setup for high quality signal capture.