Segui questo link per vedere altri tipi di pubblicazioni sul tema: Marsupials Nutrition.
Articoli di riviste sul tema "Marsupials Nutrition"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 articoli di riviste per l'attività di ricerca sul tema "Marsupials Nutrition".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi gli articoli di riviste di molte aree scientifiche e compila una bibliografia corretta.
1
J. Foley, William. "Marsupial Nutrition". Pacific Conservation Biology 5, n. 3 (1999): 240. http://dx.doi.org/10.1071/pc99240a.
Testo completoAbstract (sommario):
In the early 1980s advances in marsupial biology could no longer be encapsulated in a single volume such as Hugh Tyndale-Biscoe's "Life of Marsupials" and Cambridge University Press commissioned a series of monographs covering a range of different topics in marsupial biology. As it was, only three of that series were realized and among them was the ptedecessor to this book "Digestive Physiology and Nutrition of Marsupials" published in 1982. "Marsupial Nutrition" is a considerably expanded and comprehensive review of studies of nutrition and digestive physiology of Australasian and South American marsupials. In Australia, many ecologists view the limited nutrient status of our soils and vegetation as a fundamental limit to animal populations. This book explains firstly how Australian marsupials have responded to those limitations and secondly asks whether these responses are common amongst marsupials living in New Guinea and South America.
2
Hetz, Jennifer A., Brandon R. Menzies, Geoffrey Shaw e Marilyn B. Renfree. "The tammar wallaby: a non-traditional animal model to study growth axis maturation". Reproduction, Fertility and Development 31, n. 7 (2019): 1276. http://dx.doi.org/10.1071/rd18271.
Testo completoAbstract (sommario):
Maturation of the growth hormone (GH)/insulin-like growth factor 1 (IGF1) axis is a critical developmental event that becomes functional over the peripartum period in precocial eutherian mammals such as sheep. In mice and marsupials that give birth to altricial young, the GH/IGF1 axis matures well after birth, suggesting that functional maturation is associated with developmental stage, not parturition. Recent foster-forward studies in one marsupial, the tammar wallaby (Macropus eugenii), have corroborated this hypothesis. ‘Fostering’ tammar young not only markedly accelerates their development and growth rates, but also affects the timing of maturation of the growth axis compared with normal growing young, providing a novel non-traditional animal model for nutritional manipulation. This review discusses how nutrition affects the maturation of the growth axis in marsupials compared with traditional eutherian animal models.
3
HUME, I. D. "Nutrition of marsupials in captivity". International Zoo Yearbook 39, n. 1 (gennaio 2005): 117–32. http://dx.doi.org/10.1111/j.1748-1090.2005.tb00011.x.
Testo completo
4
Stannard, Hayley J., Robert D. Miller e Julie M. Old. "Marsupial and monotreme milk—a review of its nutrient and immune properties". PeerJ 8 (23 giugno 2020): e9335. http://dx.doi.org/10.7717/peerj.9335.
Testo completoAbstract (sommario):
All mammals are characterized by the ability of females to produce milk. Marsupial (metatherian) and monotreme (prototherian) young are born in a highly altricial state and rely on their mother’s milk for the first part of their life. Here we review the role and importance of milk in marsupial and monotreme development. Milk is the primary source of sustenance for young marsupials and monotremes and its composition varies at different stages of development. We applied nutritional geometry techniques to a limited number of species with values available to analyze changes in macronutrient composition of milk at different stages. Macronutrient energy composition of marsupial milk varies between species and changes concentration during the course of lactation. As well as nourishment, marsupial and monotreme milk supplies growth and immune factors. Neonates are unable to mount a specific immune response shortly after birth and therefore rely on immunoglobulins, immunological cells and other immunologically important molecules transferred through milk. Milk is also essential to the development of the maternal-young bond and is achieved through feedback systems and odor preferences in eutherian mammals. However, we have much to learn about the role of milk in marsupial and monotreme mother-young bonding. Further research is warranted in gaining a better understanding of the role of milk as a source of nutrition, developmental factors and immunity, in a broader range of marsupial species, and monotremes.
5
Irlbeck, NA, e ID Hume. "The role of Acacia in the diets of Australian marsupials ? A review." Australian Mammalogy 25, n. 2 (2003): 121. http://dx.doi.org/10.1071/am03121.
Testo completoAbstract (sommario):
Many of the 600 species of Acacia found in Australia form part of the diet of several groups of marsupials. Acacia foliage is generally high in tannins but is consumed by several folivorous possums and by some macropods (kangaroos and wallabies), but the macropods eat it mainly as dry leaf litter during times of food shortage (in dry seasons and drought). Acacia gum is an important diet component of two omnivorous possums (Petaurus breviceps, Gymnobelidius leadbeateri) and, to a lesser extent, two rat-kangaroos (Bettongia sp.). Acacia seeds are consumed by marsupials to a limited extent, but are an important seasonal component of the diet of the mountain brushtail possum (Trichosurus cunninghami), and possibly the tammar wallaby (Macropus eugenii) on Kangaroo Island. Likewise, Acacia arils (lipid-rich appendages to the seeds of some species) are an important seasonal component of the diet of the mahogany glider (Petaurus gracilis). Acacia pollen and nectar are consumed by several omnivorous possums (e.g., Petaurus norfolcensis) as well as by at least one species of rock-wallaby (Petrogale sp.), but the quantitative contributions made by these floral products to the protein and energy budgets of the consumers have been difficult to determine. Thus several parts of the Acacia plant are food resources for one or more groups of marsupials, but the contribution of the genus to marsupial nutrition is often overlooked.
6
Pharo, Elizabeth A. "Marsupial milk: a fluid source of nutrition and immune factors for the developing pouch young". Reproduction, Fertility and Development 31, n. 7 (2019): 1252. http://dx.doi.org/10.1071/rd18197.
Testo completoAbstract (sommario):
Marsupials have a very different reproductive strategy to eutherians. An Australian marsupial, the tammar wallaby (Macropus eugenii) has a very short pregnancy of about 26.5 days, with a comparatively long lactation of 300–350 days. The tammar mother gives birth to an altricial, approximately 400 mg young that spends the first 200 days postpartum (p.p.) in its mother’s pouch, permanently (0–100 days p.p.; Phase 2A) and then intermittently (100–200 days p.p.; Phase 2B) attached to the teat. The beginning of Phase 3 marks the first exit from the pouch (akin to the birth of a precocious eutherian neonate) and the supplementation of milk with herbage. The marsupial mother progressively alters milk composition (proteins, fats and carbohydrates) and individual milk constituents throughout the lactation cycle to provide nutrients and immunological factors that are appropriate for the considerable physiological development and growth of her pouch young. This review explores the changes in tammar milk components that occur during the lactation cycle in conjunction with the development of the young.
7
O’Hara, Patricia J., Peter J. Murray e Athol V. Klieve. "A review of the nutrition of Australian peramelid marsupials". Australian Mammalogy 34, n. 2 (2012): 133. http://dx.doi.org/10.1071/am11008.
Testo completoAbstract (sommario):
European settlement has had a dramatic impact on the distribution and abundance of peramelid (bandicoot and bilby) marsupials. Predation and competition from introduced species and altered habitat have been implicated in their decline or extinction. Bandicoots and bilbies inhabit a broad range of habitats in Australia. Research on the distribution, morphology, gastrointestinal histology, lactation, metabolism and nutritional physiology of extant peramelid species has increased in the last few decades. This paper provides a review that encompasses recent nutritional-based research. Peramelid research is mostly limited to only three species – Isoodon macrourus, Perameles nasuta and Macrotis lagotis – which prevents effective comparisons between species. Peramelids are broadly classified as omnivores and possess relatively uncomplicated gastrointestinal tracts. The caecum is the region of greatest diversity among species. The relatively large caecum of Chaeropus ecaudatus supports the theory that this species may have been the only herbivorous peramelid. The caecum of M. lagotis is less pronounced than other species and is continuous with the proximal colon. M. lagotis also has a longer total colon length, which aids water conservation to ensure survival in an arid environment. Temperate-zone species such as I. macrourus, I. obesulus and P. nasuta are more similar to each other with respect to gastrointestinal morphology than either C. ecaudatus or M. lagotis. Additional research on the morphometrics of the gastrointestinal tracts of P. gunnii, P. bougainville, P. eremiana, M. leucura and I. auratus would enable further comparisons to determine whether differences are a result of geographic distribution, habitat preference or variation between genera and/or individual species. Currently, histological information of the gastrointestinal tract is limited to the small intestine of P. nasuta and I. macrourus. The histology of the small intestine of the weaned juvenile I. macrourus more closely resembles that of P. nasuta pouch young than P. nasuta adults. The younger bandicoots possessed villi whereas in the adult P. nasuta and I. macrourus villi were arranged in a zig-zag formation. The reason for the zig-zag formation of the villi and the function it may serve remains unclear. Detailed nutritional research on captive M. lagotis, I. macrourus and P. nasuta indicate that the two temperate-zone species – I. macrourus and P. nasuta – are more similar to each other than to the arid-dwelling M. lagotis. Detailed nutritional studies are required on all species, both free-living and captive. Experimental diets do not always accurately reflect a natural diet, which means that results from captive studies may not reflect the situation for free-living animals. The hindgut of peramelids is the main region for retention of digesta, and presumably where microbial digestion occurs. However, no studies have been undertaken to examine the microflora of the gastrointestinal tract of bandicoots or the bilby. As captive husbandry is an important tool in conservation management, it should also improve their successful maintenance in captivity by the provision of diets that better meet their nutritional requirements.
8
Stringer, J. M., G. Shaw, A. Pask e M. B. Renfree. "137. GENOMIC IMPRINTING IN THE MARSUPIAL MAMMARY GLAND". Reproduction, Fertility and Development 22, n. 9 (2010): 55. http://dx.doi.org/10.1071/srb10abs137.
Testo completoAbstract (sommario):
Genomic imprinting is an epigenetic mechanism that differentially regulates the expression of certain genes, resulting in expression from only one parental allele. In mammals, genomic imprinting occurs in the placenta of both eutherians and marsupials, and plays an important role in regulating nutrition and growth of the developing fetus. The mammary gland also provides a critical source of nutrition for the neonate in all mammals, but there are few imprinting studies of this organ. Marsupials deliver tiny, altricial young that complete development during an extended lactation. INS (insulin) is paternally expressed in the eutherian and marsupial yolk sac and curiously is the only gene that is solely imprinted in this organ (1, 2). Insulin regulates carbohydrate metabolism, protein synthesis and cell growth. Insulin, (plus cortisol and prolactin) is required for the onset of lactation and the synthesis of milk (3). We characterised INS expression and examined its imprint status in the mammary gland of the tammar wallaby. INS mRNA is expressed in the mammary gland of the tammar from birth and throughout of lactation with highest expression at the initiation of lactation (Phase 1-2a) and around Phase 3 of lactation. Direct sequencing of 7 individuals at various stages of lactation confirmed that INS is imprinted in the mammary gland. Surprisingly, INS may also be imprinted in several other organs in the adult and juvenile wallaby. Preliminary bisulfite sequencing suggests there is a differentially methylated region located upstream of INS which may help to regulate INS expression. This is the first study to identify INS imprinting outside the yolk sac. As INS is critical for lactation, this is also the first indication that genomic imprinting may regulate lactation, suggesting that imprinting in the mammary gland may be as critical for post-natal survival as placental imprinting is for pre-natal development. (1) Deltour LX, et al. (1995). Tissue- and developmental stage-specific imprinting of the mouse proinsulin gene, Ins2. Dev Biol 168(2): 686–688.(2) Ager EI, et al. (2007). Insulin is imprinted in the placenta of the marsupial, Macropus eugenii. Dev Biol 309: 317–328.(3) Bolander FF, et al. (1981). Insulin is essential for accumulation of casein mRNA in mouse mammary epithelial cells. Proc Natl Acad Sci USA 78(9): 5682–5684.
9
Adamski, Frances M., e Jerome Demmer. "Two Stages of Increased IgA Transfer During Lactation in the Marsupial, Trichosurus vulpecula (Brushtail Possum)". Journal of Immunology 162, n. 10 (15 maggio 1999): 6009–15. http://dx.doi.org/10.4049/jimmunol.162.10.6009.
Testo completoAbstract (sommario):
Abstract The polymeric Ig receptor (pIgR) and J chain molecules are involved in the transfer of IgA across the mammary gland epithelia into milk. The J chain binds two IgA molecules to form dimeric IgA, and the pIgR transports this complex through epithelial cells. We report here the cloning of the first marsupial homologues for the pIgR and J chain from the brushtail possum. Marsupial young are born after a short gestation and are less developed than eutherian newborn. The pouch young is completely dependent on milk as its sole source of nutrition during early lactation and this phase can be considered to be equivalent to an external gestation. Two periods of increased expression of pIgR, J chain, and IgA heavy chain mRNAs were observed in the mammary gland during lactation. The first occurs for a brief period after birth of the pouch young and is likely to reflect IgA transfer via the colostrum. The second period of increased expression, which is unique to marsupials, occurs after the early lactation period and just before young exit the pouch. We propose that this represents a second colostral-like phase at the end of the external gestation.
10
Stringer, J. M., G. Shaw, A. Pask e M. B. Renfree. "164. THE IMPRINT STATUS AND EXPRESSION OF INS IN THE TAMMAR WALLABY, MACROPUS EUGENII". Reproduction, Fertility and Development 21, n. 9 (2009): 82. http://dx.doi.org/10.1071/srb09abs164.
Testo completoAbstract (sommario):
Genomic imprinting is an epigenetic mechanism that differentially regulates the expression of certain genes, resulting in expression from only one parental allele. It is presumed to have first evolved after the divergence of therian mammals from the monotremes. One imprinted gene, INS is maternally imprinted (paternally expressed) in the eutherian and marsupial yolk sac1,2. INS encodes the precursor to the hormone insulin, which regulates carbohydrate metabolism and has a role in cell growth and, by regulating amino acid and fatty acid transporters, protein synthesis. In rats, mice and several other mammals insulin, in addition to cortisol and prolactin, is an absolute requirement for the onset of lactation and the synthesis of milk3. As imprinting plays an important role in regulating nutrition and growth the role of imprinted genes in the placenta has been the focus for imprinting research. Since the mammary gland provides a critical source of nutrition for the neonate in all mammals it is possible that genomic imprinting may have developed and been maintained in this organ. Given that marsupials deliver tiny, altricial young, it is in the relatively long and complex lactation phase where the mother has most control of the young's growth. Therefore, there may be greater selection for genomic imprinting in the marsupial mammary gland than in the eutherian mammary gland. This study examined the expression and the imprint status of INS in the mammary gland and neonatal tissues of the tammar wallaby, Macropus eugenii. INS expression was detected using PCR and direct sequencing provides evidence of INS imprinting in the mammary gland. This is the first study to identify imprinting in the mammary gland of a marsupial and the first to identify INS imprinting outside of the yolk sac.
11
Renfree, Marilyn B., Shunsuke Suzuki e Tomoko Kaneko-Ishino. "The origin and evolution of genomic imprinting and viviparity in mammals". Philosophical Transactions of the Royal Society B: Biological Sciences 368, n. 1609 (5 gennaio 2013): 20120151. http://dx.doi.org/10.1098/rstb.2012.0151.
Testo completoAbstract (sommario):
Genomic imprinting is widespread in eutherian mammals. Marsupial mammals also have genomic imprinting, but in fewer loci. It has long been thought that genomic imprinting is somehow related to placentation and/or viviparity in mammals, although neither is restricted to mammals. Most imprinted genes are expressed in the placenta. There is no evidence for genomic imprinting in the egg-laying monotreme mammals, despite their short-lived placenta that transfers nutrients from mother to embryo. Post natal genomic imprinting also occurs, especially in the brain. However, little attention has been paid to the primary source of nutrition in the neonate in all mammals, the mammary gland. Differentially methylated regions (DMRs) play an important role as imprinting control centres in each imprinted region which usually comprises both paternally and maternally expressed genes ( PEG s and MEG s). The DMR is established in the male or female germline (the gDMR). Comprehensive comparative genome studies demonstrated that two imprinted regions, PEG10 and IGF2-H19 , are conserved in both marsupials and eutherians and that PEG10 and H19 DMRs emerged in the therian ancestor at least 160 Ma, indicating the ancestral origin of genomic imprinting during therian mammal evolution. Importantly, these regions are known to be deeply involved in placental and embryonic growth. It appears that most maternal gDMRs are always associated with imprinting in eutherian mammals, but emerged at differing times during mammalian evolution. Thus, genomic imprinting could evolve from a defence mechanism against transposable elements that depended on DNA methylation established in germ cells.
12
Weisbecker, Vera, Simon Blomberg, Anne W. Goldizen, Meredeth Brown e Diana Fisher. "The Evolution of Relative Brain Size in Marsupials Is Energetically Constrained but Not Driven by Behavioral Complexity". Brain, Behavior and Evolution 85, n. 2 (2015): 125–35. http://dx.doi.org/10.1159/000377666.
Testo completoAbstract (sommario):
Evolutionary increases in mammalian brain size relative to body size are energetically costly but are also thought to confer selective advantages by permitting the evolution of cognitively complex behaviors. However, many suggested associations between brain size and specific behaviors - particularly related to social complexity - are possibly confounded by the reproductive diversity of placental mammals, whose brain size evolution is the most frequently studied. Based on a phylogenetic generalized least squares analysis of a data set on the reproductively homogenous clade of marsupials, we provide the first quantitative comparison of two hypotheses based on energetic constraints (maternal investment and seasonality) with two hypotheses that posit behavioral selection on relative brain size (social complexity and environmental interactions). We show that the two behavioral hypotheses have far less support than the constraint hypotheses. The only unambiguous associates of brain size are the constraint variables of litter size and seasonality. We also found no association between brain size and specific behavioral complexity categories within kangaroos, dasyurids, and possums. The largest-brained marsupials after phylogenetic correction are from low-seasonality New Guinea, supporting the notion that low seasonality represents greater nutrition safety for brain maintenance. Alternatively, low seasonality might improve the maternal support of offspring brain growth. The lack of behavioral brain size associates, found here and elsewhere, supports the general ‘cognitive buffer hypothesis' as the best explanatory framework of mammalian brain size evolution. However, it is possible that brain size alone simply does not provide sufficient resolution on the question of how brain morphology and cognitive capacities coevolve.
13
Scopin, A. E., A. P. Saveljev, N. A. Suntsova, S. Gnophanxay, A. N. Tikhonov e A. V. Abramov. "Digestive system of the Laotian rock rat Laonastes aenigmamus (Rodentia: Diatomyidae) from the evolutionary viewpoint". Proceedings of the Zoological Institute RAS 315, n. 1 (30 marzo 2011): 3–18. http://dx.doi.org/10.31610/trudyzin/2011.315.1.3.
Testo completoAbstract (sommario):
A preliminary study of the gastrointestinal tract of Laonastes aenigmamus Jenkins et al., 2005 has been carried out. We have revealed that Laonastes is the smallest folivorous mammal with the enlarged forestomach, which is similar to that of certain herbivorous marsupials. The stomach of this rodent contains 70% of the digesta and performs the main role in storing and digesting of plant foods. Laonastes is a unique rodent having such the digestive system, and its herbivory is confirmed by the enlarged ampulla duodeni, small dimensions of the hindstomach (pars pylorica), the absence of vesica fellea, the presence of colon spiral loops, the well-developed lymphoid tissue of stomach, and the gut mass making up to 25–27% of the entire body mass. Such the gastrointestinal tract might have evolved as a result of a general digestive strategy of the foregut mammals that inhabited tropical forests in the Miocene. This strategy involved an adaptation to the nutrition on leaves of tropical dycots which apparently contributed to the convergent evolution of the digestive system in different folivorous mammals.
14
Snipes, RL, H. Snipes e FN Carrick. "Morphometric data on the intestines of five Australian marsupials (Marsupialia)." Australian Mammalogy 25, n. 2 (2003): 193. http://dx.doi.org/10.1071/am03193.
Testo completoAbstract (sommario):
THE nutritional biology of marsupials has been a subject of numerous studies, culminating in valuable compilations covering a wide range of aspects (Osman Hill and Rewell 1954; Walton and Richardson 1989; Hume 1982, 1999; Kerle 2001). Despite this thorough coverage, there remains a scarcity of morphometric data on the intestines of monotremes and marsupials. In an attempt to approach this need, an effort was initiated to provide morphometric data on monotremes (Snipes et al. 2002) and marsupials (Snipes et al. 1993, 2003).
15
Old, Julie M., e Hayley J. Stannard. "Corrigendum to: Conservation of quolls (Dasyurus spp.) in captivity – a review". Australian Mammalogy 43, n. 3 (2021): 378. http://dx.doi.org/10.1071/am20033_co.
Testo completoAbstract (sommario):
Quolls are carnivorous marsupials in the family Dasyuridae with characteristic white spots. They are distributed throughout Australia and New Guinea, but uncommonly seen due to their mostly nocturnal solitary nature, and large home ranges. All Australian quolls are listed as ‘near threatened' or ‘endangered' at state, national and international levels, largely due to human-induced threats. Threats include introduced predators, habitat loss through clearing and modifications including changed fire regimes, disease, human persecution, vehicle collisions and accidental or targeted poisoning by humans and cane toads (Rhinella marina). Conservation efforts that have focussed on reducing introduced predators, and minimising the impact of cane toads, have aided some translocations, hence species recovery in some local areas of Australia has occurred. Where species conservation has required captive breeding for translocation, successful captive management has been crucial. We summarise research conducted in captivity on aspects of birth and development, health and disease, and blood and nutrition parameters of quolls, and suggest future directions for research. Further research on captive and wild quoll populations will benefit future translocations, reintroductions and conservation through increased knowledge, improved maintenance and husbandry of captive colonies, and monitoring of wild populations.
16
van Tets, I. G. "Can Flower-Feeding Marsupials Meet Their Nitrogen Requirements on Pollen in The Field?" Australian Mammalogy 20, n. 3 (1998): 383. http://dx.doi.org/10.1071/am98383.
Testo completoAbstract (sommario):
Two arboreal marsupials, the eastern pygmy possum (Cercartetus nanus) and the sugar glider (Petaurus breviceps) have exceptionally low maintenance nitrogen requirements on pollen diets. This study compares their nitrogen requirements with the density of Banksia pollen that is available in the Barren Grounds Nature Reserve, New South Wales, a site where both species are known to forage on Banksia inflorescences. The pollen density was sufficiently high that both species were capable of meeting their maintenance nitrogen requirements on pollen whenever Banksia spp. were in flower. C. nanus required a smaller proportion of its home range than P. breviceps to do so and pollen was likely to be of much greater nutritional significance to both species in winter than in summer. This corresponds closely with the results of field studies comparing the diets of these mammals at different times of the year. Pollen is an important source of nitrogen for flower-feeding marsupials but its importance will vary between species depending on the marsupial's requirements, its body size and on the quantity of pollen that is available.
17
Johnson-Delaney, Cathy A. "Captive Marsupial Nutrition". Veterinary Clinics of North America: Exotic Animal Practice 17, n. 3 (settembre 2014): 415–47. http://dx.doi.org/10.1016/j.cvex.2014.05.006.
Testo completo
18
Munn, Adam J., Peter Banks e Ian D. Hume. "Digestive plasticity of the small intestine and the fermentative hindgut in a marsupial herbivore, the tammar wallaby (Macropus eugenii)". Australian Journal of Zoology 54, n. 4 (2006): 287. http://dx.doi.org/10.1071/zo06004.
Testo completoAbstract (sommario):
We investigated the effects of a ground, pelleted diet versus natural forage on the gross morphology of the gastrointestinal tract of a medium-sized (5–7 kg body mass) macropodid marsupial, the tammar wallaby (Macropus eugenii). The empty wet mass (g) of the small intestine of tammar wallabies maintained on a pelleted diet for 6 weeks was 22% greater than that of animals maintained on natural forage, once body mass was taken into account by ANCOVA. Similarly, the body-mass-adjusted length of the tammar wallaby caecum and proximal colon combined was 25% longer in animals maintained on the pelleted diet compared with those maintained on forage. Our data suggest that food particle size may be directly involved in controlling the size of the post-gastric alimentary tract in tammar wallabies, and thus in their diet choice and nutritional ecology. Notably, this is the first study that links phenotypic plasticity of the gut directly to diet in a marsupial and we conclude that the tammar wallaby is an excellent model for exploring the causes and consequences of digestive plasticity in macropodid marsupials.
19
Hayward, John S., e Paul A. Lisson. "Evolution of brown fat: its absence in marsupials and monotremes". Canadian Journal of Zoology 70, n. 1 (1 gennaio 1992): 171–79. http://dx.doi.org/10.1139/z92-025.
Testo completoAbstract (sommario):
Species from all extant families of marsupials and monotremes were examined to clarify whether these mammalian subclasses possess brown adipose tissue. To optimize the chance of finding this tissue, special emphasis was given to sampling species adapted to colder regions, species with small adult body size, and individuals at a stage of development equivalent to the newborn stage of placentals (late pouch life in the case of marsupials). Evidence based on gross morphology and light, electron, and fluorescence microscopy failed to show the presence of brown adipose tissue in any marsupial or monotreme. All adipose tissue was typical white fat, including special instances where multilocularity of lipid droplets occurred in association with white adipocyte development or with fat mobilization resulting from nutritional or cold stress. These results, combined with lack of positive identification of brown adipose tissue in birds or other vertebrates, indicate that brown adipose tissue is unique to eutherian (placental) mammals and probably evolved early in the radiation of this subclass. This uniqueness presents the opportunity to suggest a more satisfactory name for the subclass: Thermolipia (from the Greek for "warm fat") or, commonly, thermolipials.
20
Hume, I. D. "Nutrition of marsupial herbivores". Proceedings of the Nutrition Society 48, n. 1 (gennaio 1989): 69–79. http://dx.doi.org/10.1079/pns19890011.
Testo completo
21
Dearing, Denise. "Marsupial Nutrition. Ian D. Hume". Quarterly Review of Biology 75, n. 2 (giugno 2000): 196. http://dx.doi.org/10.1086/393435.
Testo completo
22
O'Hara, Patricia J., Athol V. Klieve, Peter J. Murray, Anita J. Maguire, Diane Ouwerkerk e Karen Harper. "Effect of time and diet change on the bacterial community structure throughout the gastrointestinal tract and in faeces of the northern brown bandicoot, Isoodon macrourus". Australian Journal of Zoology 64, n. 1 (2016): 48. http://dx.doi.org/10.1071/zo15078.
Testo completoAbstract (sommario):
A significant gap, in not only peramelid nutritional physiology but marsupial nutrition as a whole, is the lack of information relating to microorganisms of the gastrointestinal tract. This research is a preliminary investigation that will provide a baseline for comparisons among peramelids. The high degree of 16S rRNA gene clones identified in this research that are closely related to culturable bacteria suggests that additional research will enable a more complete description of the gastrointestinal bacteria of I. macrourus. Most identifiable clones belonged to Clostridium and Ruminococcus. This research has confirmed that the hindgut of I. macrourus, the caecum, proximal colon and distal colon, are the main sites for microbial activity.
23
McArthur, C. "Book review: Marsupial Nutrition by Ian D. Hume". Australian Mammalogy 21, n. 2 (1999): 275. http://dx.doi.org/10.1071/am99275.
Testo completo
24
Stannard, Hayley J., Bronwyn M. McAllan e Julie M. Old. "Dietary composition and nutritional outcomes in two marsupials,Sminthopsis macrouraandS. crassicaudata". Journal of Mammalogy 95, n. 3 (26 giugno 2014): 503–15. http://dx.doi.org/10.1644/13-mamm-a-071.
Testo completo
25
Stannard, Hayley J., e Julie M. Old. "Description of the gastrointestinal tract and associated organs of the kultarr (Antechinomys laniger)". Australian Mammalogy 35, n. 1 (2013): 39. http://dx.doi.org/10.1071/am12003.
Testo completoAbstract (sommario):
This paper provides a macro- and microscopic description of the digestive tract of the kultarr (Antechinomys laniger), a small dasyurid marsupial. The digestive tract was simple, with no external differentiation between the small and large intestine, and lacked a caecum. Mean gross length of the kultarr digestive tract was 165.2 ± 32.1 mm. Microscopically, the tissues had cell types similar to those of other mammals. The new information will aid future post-mortem investigations of captive kultarrs and future studies of nutrition.
26
Kanowski, John, M. S. Hopkins, Helene Marsh e J. W. Winter. "Ecological correlates of folivore abundance in north Queensland rainforests". Wildlife Research 28, n. 1 (2001): 1. http://dx.doi.org/10.1071/wr99098.
Testo completoAbstract (sommario):
The ecological factors controlling the distribution and abundance of the folivorous marsupials endemic to the rainforests of northern Australia are not understood. In this study, we surveyed folivore abundance at 40 sites stratified by altitude and geology in rainforests of the Atherton Tableland, north Queensland. All five species of folivore that inhabit the study area were more abundant in highland (800–1200 m) than in upland (400–800 m) forests. Allowing for the effects of altitude, four species of folivore were more abundant in forests on nutrient-rich basalts than in forests on nutrient-poor acid igneous or metamorphic rocks. The abundance of two folivore species also varied inversely with rainfall. Altitudinal variation in folivore abundance in the study area has been attributed to habitat destruction, Aboriginal hunting, the distribution of host plants and climate; however, none of these hypotheses has been tested. Variation in folivore abundance with geology is plausibly explained as a response to the nutritional quality of foliage. Foliage quality may also explain the inverse relationship between two of the folivores and rainfall. The results of this study show that only a relatively small proportion of north Queensland rainforests support abundant populations of the endemic folivorous marsupials.
27
McArthur, C., e G. D. Sanson. "Nutritional Effects and Costs of a Tannin in Two Marsupial Arboreal Folivores". Functional Ecology 7, n. 6 (dicembre 1993): 697. http://dx.doi.org/10.2307/2390191.
Testo completo
28
Clements, Fiona, Perdita Hope, Chris Daniels, Ian Chapman e Gary Wittert. "Thermogenesis in the marsupial Sminthopsis crassicaudata: effect of catecholamines and diet". Australian Journal of Zoology 46, n. 4 (1998): 381. http://dx.doi.org/10.1071/zo98022.
Testo completoAbstract (sommario):
The fat-tailed dunnart (Sminthopsis crassicaudata) is a small carnivorous marsupial with detectable brown adipose tissue. In order to determine whether catecholamines and food intake increase thermogenesis in this species, we measured the response of oxygen consumption (Vo2) to (i) intraperitoneal noradrenaline (0.25–4.0 mg kg-1), and (ii) food intake. The effect of nutritional status and macronutrient composition of the diet on the Vo2 response to food intake was determined by feeding both non-deprived and 24-h-food-deprived animals with either laboratory diet (1.01 Kcal g-1 (4.2 KJ g-1), 20% fat) or live mealworms (Tenebrio molitor larvae) (2.99 Kcal g-1 (12.5 KJ g-1), 30% fat). Intraperitoneal injection of noradrenaline at doses of 0.25 and 0.5 mg kg-1 increased Vo2 by 14% and 31% respectively at 30 min (P ≤ 0.05), whereas noradrenaline at 2 and 4 mg kg-1 decreased Vo2 by 10% and 31% respectively (P ≤ 0.05). Following food intake, Vo2 increased in both non-deprived (P < 0.05) and 24-h-food-deprived (P < 0.05) animals. While the magnitude of the increase in Vo2 was similar in animals fed with either laboratory diet or mealworms, both diets increased Vo2 more in non-deprived than in 24-h-food-deprived animals (P < 0.05). These results suggest that in S. crassicaudata (i) catecholamines increase thermogenesis and (ii) the magnitude of diet-induced thermogenesis is dependent on both the nutritional status of the animal and the macronutrient composition of the diet.
29
Cork, S. J. "Meeting the energy requirements for lactation in a macropodid marsupial: current nutrition versus stored body reserves". Journal of Zoology 225, n. 4 (dicembre 1991): 567–76. http://dx.doi.org/10.1111/j.1469-7998.1991.tb04325.x.
Testo completo
30
Johnson, C. N. "Nutritional Ecology of a Mycophagous Marsupial in Relation to Production of Hypogeous Fungi". Ecology 75, n. 7 (ottobre 1994): 2015–21. http://dx.doi.org/10.2307/1941606.
Testo completo
31
Hetz, Jennifer A., Brandon R. Menzies, Geoffrey Shaw, Aneta Stefanidis, Michael A. Cowley e Marilyn B. Renfree. "Effects of nutritional manipulation on body composition in the developing marsupial, Macropus eugenii". Molecular and Cellular Endocrinology 428 (giugno 2016): 148–60. http://dx.doi.org/10.1016/j.mce.2016.03.030.
Testo completo
32
Hill, Nichola J., Elizabeth M. Deane e Michelle L. Power. "Prevalence and Genetic Characterization of Cryptosporidium Isolates from Common Brushtail Possums (Trichosurus vulpecula) Adapted to Urban Settings". Applied and Environmental Microbiology 74, n. 17 (18 luglio 2008): 5549–55. http://dx.doi.org/10.1128/aem.00809-08.
Testo completoAbstract (sommario):
ABSTRACT The common brushtail possum (Trichosurus vulpecula) is one of the most abundant native marsupials in urban Australia, having successfully adapted to utilize anthropogenic resources. The habituation of possums to food and shelter available in human settlements has facilitated interaction with people, pets, and zoo animals, increasing the potential for transmission of zoonotic Cryptosporidium pathogens. This study sought to examine the identity and prevalence of Cryptosporidium species occurring in possums adapted to urban settings compared to possums inhabiting remote woodlands far from urban areas and to characterize the health of the host in response to oocyst shedding. Findings indicated that both populations were shedding oocysts of the same genotype (brushtail possum 1 [BTP1]) that were genetically and morphologically distinct from zoonotic species and genotypes and most closely related to Cryptosporidium species from marsupials. The urban population was shedding an additional five Cryptosporidium isolates that were genetically distinct from BTP1 and formed a sister clade with Cryptosporidium parvum and Cryptosporidium hominis. Possums that were shedding oocysts showed no evidence of pathogenic changes, including elevated levels of white blood cells, diminished body condition (body mass divided by skeletal body length), or reduced nutritional state, suggesting a stable host-parasite relationship typical of Cryptosporidium species that are adapted to the host. Overall, Cryptosporidium occurred with a higher prevalence in possums from urban habitat (11.3%) than in possums from woodland habitat (5.6%); however, the host-specific nature of the genotypes may limit spillover infection in the urban setting. This study determined that the coexistence of possums with sympatric populations of humans, pets, and zoo animals in the urban Australian environment is unlikely to present a threat to public health safety.
33
Claridge, AW, e SJ Cork. "Nutritional-Value of Hypogeal Fungal Sporocarps for the Long-Nosed Potoroo (Potorous-Tridactylus), a Forest-Dwelling Mycophagous Marsupial". Australian Journal of Zoology 42, n. 6 (1994): 701. http://dx.doi.org/10.1071/zo9940701.
Testo completoAbstract (sommario):
Although mycophagy (fungus-feeding) is widespread among small ground-dwelling mammals, there has been little evaluation of the nutritional benefits of this feeding habit. In Australia, some members of the Potoroidae (or rat-kangaroo family) consume large amounts of hypogeal fungi throughout the year. Hypogeal fungi appear to be of marginal nutritional quality for small mammals with simple stomachs but potoroos have an enlarged forestomach in which microbial fermentation takes place, and this may allow more effective utilisation of protected nitrogenous components and structural carbohydrates of fungi. In a feeding experiment, we evaluated the nutritional value of sporocarps of the hypogeal fungi Mesophellia glauca (Mg) and Rhizopogon luteolus (R1), for the long-nosed potoroo (Potorous tridacytlus). Although the concentration of nitrogen was high in both fungi, much of that nitrogen was in non-protein form or associated with cell walls and may be either of low nutritional value or protected from digestive enzymes. The concentration of cell-wall constituents (fibre) was high in both fungi, suggesting low availability of digestible energy. Despite these features, the digestibilities of dry matter (Mg 86%, Rl 80%), ingested nitrogen (Mg 72%, Rl 72%) and energy (kJ kg-1) (Mg 93%, Rl 76%) of both fungi were high. Consequently, P. tridactylus maintained positive nitrogen balance and high intakes of digestible and metabolisable energy. We conclude that the sporocarps of hypogeal fungi represent a nutritionally valuable food for rat-kangaroos and suggest that lack of a foregut-fermentation strategy in other similar-sized ground-dwelling mammals in the forests of south-eastern Australia explains why they use the hypogeal fungal resource to a lesser extent than do rat-kangaroos.
34
Wallis, I. R., e W. J. Foley. "Validation of near-infrared reflectance spectroscopy to estimate the potential intake of Eucalyptus foliage by folivorous marsupials". Australian Journal of Zoology 51, n. 1 (2003): 95. http://dx.doi.org/10.1071/zo02027.
Testo completoAbstract (sommario):
We validated an existing model of food intake by captive common ringtail possums (Pseudocheirus peregrinus), a folivorous marsupial, by feeding foliage from 18 individual Eucalyptus polyanthemos trees and measuring dry matter intake. Near-infrared reflectance (NIR) spectra of a sample of each foliage were recorded and compared against a previously derived model relating food intake in common ringtails and NIR spectra. We found excellent agreement between the predicted and measured food intake, with the standard error of prediction being 3.6 g kg(body mass)–0.75 day–1. NIR spectroscopy is a suitable tool for modelling complex attributes such as potential feeding rates of mammals. This makes it theoretically possible to remotely sense critical nutritional determinants of animal habitat on a landscape scale.
35
Cripps, Jemma K., Michelle E. Wilson, Mark A. Elgar e Graeme Coulson. "Experimental manipulation of fertility reveals potential lactation costs in a free-ranging marsupial". Biology Letters 7, n. 6 (6 luglio 2011): 859–62. http://dx.doi.org/10.1098/rsbl.2011.0526.
Testo completoAbstract (sommario):
Lactation is the most energetically expensive component of reproduction in mammals. Theory predicts that reproducing females will adjust their behaviour to compensate for increased nutritional demands. However, experimental tests are required, since comparisons of the behaviour of naturally reproducing and non-reproducing females cannot distinguish between true costs of reproduction, individual differences or seasonal variation. We experimentally manipulated reproduction in free-ranging, eastern grey kangaroos ( Macropus giganteus ), using a fertility control agent. Our novel field experiment revealed that females altered their behaviour in direct response to the energetic demands of reproduction: reproducing females increased bite rates, and thus food intake, when the energetic demands of lactation were highest. Reproducing females did not reduce the time spent on vigilance for predators, but increased their forage intake on faecal-contaminated pasture, thereby increasing the risk of infection by gastrointestinal parasites—a largely unrecognized potential cost of reproduction.
36
McArthur, C., e G. D. Sanson. "Nutritional Effects and Costs of a Tannin in a Grazing and a Browsing Macropodid Marsupial Herbivore". Functional Ecology 7, n. 6 (dicembre 1993): 690. http://dx.doi.org/10.2307/2390190.
Testo completo
37
Morrison, Mark, Chris S McSweeney e A.-D. G Wright. "The vertebrate animal gut in context ? microbiomes, metagenomes and methane". Microbiology Australia 28, n. 3 (2007): 107. http://dx.doi.org/10.1071/ma07107.
Testo completoAbstract (sommario):
The microbial world colonises the gastrointestinal tracts of vertebrates soon after birth or hatching. These animal-microbe relationships have been described as competitive, cooperative or combinatorial, and all provide a variety of functional and metabolic capabilities that are relevant to host animal nutrition, health and well-being. The evolutionary adaptations of Australia?s marsupial herbivores have been relatively well characterised and favour both the cooperative and combinatorial animal-microbe models. Kangaroos and wallabies possess the cooperative model: the foregut functions as an obligate combustion chamber for a microbiome specialised in the release of nutrients from plant biomass, and which precedes a region of acid and pepsinogen secretions by the host. The common ringtail possum and wombats are examples of Australian herbivores with specialised caecal and colonic obligate combustion chambers, respectively. As such, these animals typify the combination model of animal-microbe association: the stomach and its associated digestive processes precede the obligate combustion chamber and its resident microbiome that coordinates the enzymatic hydrolysis and fermentation of plant biomass.
38
Rose, R. W., e K. Flowers. "Milk composition and growth in wild and captive Tasmanian pademelons, Thylogale billardierii (Marsupialia)". Australian Journal of Zoology 53, n. 4 (2005): 241. http://dx.doi.org/10.1071/zo05009.
Testo completoAbstract (sommario):
Changes in milk composition (total solids, carbohydrate, protein, lipid and calculated gross energy content) during lactation in three groups of wild (recently culled) and one captive group (fed ad libitum) of Tasmanian pademelon (Thylogale billardierii) were related to growth rates and body condition. The habitats of the three wild groups differed. Total milk solids were generally greater in the captive group but this difference disappeared in late lactation. Milk carbohydrates showed a general increase to mid-lactation in all groups, decreasing subsequently, but were always greater in the captive group. The captive group’s milk protein was always greater than those of wild Groups 1 and 2 but differed from wild Group 3 only in mid-lactation. Milk lipid concentrations started low in all groups; thereafter, the captive group had higher concentrations of lipid in mid-lactation but there were considerable differences between the groups in late lactation with Group 2 having the highest concentrations. Other than in the captive group there was little difference in energy content between early and mid-lactation. Growth rates of young differed between all wild groups, with the captive population exhibiting more rapid growth than all others. Thus, differences in milk composition resulting from different planes of nutrition can lead to differences in growth rates of marsupial young.
39
Gibson, Lesley A., Ian D. Hume e Peter D. McRae. "Ecophysiology and nutritional niche of the bilby (Macrotis lagotis), an omnivorous marsupial from inland Australia: a review". Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 133, n. 3 (novembre 2002): 843–47. http://dx.doi.org/10.1016/s1095-6433(02)00204-0.
Testo completo
40
Menzies, B. R., T. P. Fletcher, G. Shaw, A. J. Pask e M. B. Renfree. "P2-140 Development of the growth axis in the tammar: a marsupial model for studying nutritional manipulation in mammals". Early Human Development 83 (settembre 2007): S168—S169. http://dx.doi.org/10.1016/s0378-3782(07)70473-5.
Testo completo
41
Neethling, Jeannine, Magdalena Muller, Marieta van der Rijst e Louwrens C. Hoffman. "Sensory quality and fatty acid content of springbok (Antidorcas marsupialis) meat: influence of farm location and sex". Journal of the Science of Food and Agriculture 98, n. 7 (15 novembre 2017): 2548–56. http://dx.doi.org/10.1002/jsfa.8743.
Testo completo
42
Gibson, LA, e ID Hume. "Aspects of the ecophysiology and the dietary strategy of the greater bilby Macrotis lagotis: a review." Australian Mammalogy 26, n. 2 (2004): 179. http://dx.doi.org/10.1071/am04179.
Testo completoAbstract (sommario):
Since European settlement, the distribution of the greater bilby (Macrotis lagotis), an omnivorous peramelid marsupial, has contracted into the driest and least fertile parts of its former range. A review of the dietary, metabolic and digestive strategies used by M. lagotis provides the basis for an explanation of its ability to persist in the arid regions where it is now restricted. M. lagotis utilises an opportunistic feeding strategy, selecting dietary items in accordance with their abundance. Termites, ants and seeds, that form a concentrated food source, are prevalent in their diet. In captivity, M. lagotis exhibits a flexible digestive strategy that enables them to use diets of varying nutritional value. However, the absence of a colonic separation mechanism in the hindgut suggests that they are limited to relatively low-fibre diets, and this is reflected in their diet in the field. The low water and maintenance nitrogen requirements of M. lagotis are consistent with arid habitation, but the field metabolic rate is higher than expected for an arid-zone mammal, which suggests that water rather than energy conservation is a priority for this species.
43
Ebbers, M. J. H., I. R. Wallis, S. Dury, R. Floyd e W. J. Foley. "Spectrometric prediction of secondary metabolites and nitrogen in fresh Eucalyptus foliage: towards remote sensing of the nutritional quality of foliage for leaf-eating marsupials". Australian Journal of Botany 50, n. 6 (2002): 761. http://dx.doi.org/10.1071/bt02025.
Testo completoAbstract (sommario):
Near-infrared reflectance spectroscopy provides an excellent means of assessing the chemical composition of Eucalyptus foliage but the standard methods of drying and grinding the samples limit the speed at which spectra can be collected and thus are unsuitable for measurements in the field. We investigated whether reliable spectra could be collected from whole fresh and dry leaves of E. melliodora and E. globulus and whether we could predict the concentration of total nitrogen, the volatile terpene, 1,8 cineole and the phenolic antifeedant compound, sideroxylonal A, from these spectra. Water absorbance peaks did not obscure the absorption spectrum of 1,8 cineole and so cineole concentration was readily predicted from spectra of whole, fresh E. melliodora leaves. Similarly, both total nitrogen and sideroxylonal A could be predicted from spectra of fresh leaf in E. melliodora even though water absorption obscured some spectral features. The predictions of cineole and total nitrogen concentration in E. globulus were not as good as those in E. melliodora, possibly due to interference from waxes on the leaf surface of E. globulus juvenile foliage. Overall, these results suggest that certain important ecological attributes of Eucalyptus foliage can be predicted from spectra of whole fresh leaves. Thus, it is feasible to investigate the collection of spectra by portable or airborne spectrophotometry.
44
McLeod, B. J., E. G. Thompson, J. L. Crawford e G. H. Shackell. "Successful Group Housing of Wild-Caught Brushtail Possums (Trichosurus Vulpecula)". Animal Welfare 6, n. 1 (febbraio 1997): 67–76. http://dx.doi.org/10.1017/s0962728600019400.
Testo completoAbstract (sommario):
AbstractThe common brushtail possum (Trichosurus vulpecula), introduced from Australia about 150 years ago, has become a major pest threatening the native biota of New Zealand. It is also an important disease vector, acting as a wildlife reservoir of infection. Conventional methods of control have had little effect on reducing the national population, so there is a quest to find more effective and humane methods. This has led to an upsurge in research aimed at increasing our knowledge of the biology of this marsupial, with an attendant increase in requirements for access to colony-housed animals.Possums kept for research purposes have often been housed in individual cages, and several colonies have experienced high mortality rates. After capture, possums have shown inappetence, weight loss and a predisposition to infection, suggesting that this species is susceptible to post-capture stress. For our reproductive studies, research animals are only useful if maintained under conditions that ensure behavioural and physiological processes remain normal. We have adopted an ‘animal husbandry’ approach for our possum colony, where social interaction and the ability to exhibit instinctive behaviour patterns are considered as important as adequate nutrition and housing.In this colony, group-housed possums show no signs of post-capture stress, and mortality rate has been less than one per cent (of > 600 animals housed to date). Virtually all possums gain weight over the first month of captivity. Procedures for monitoring, handling and the collection of data from these animals, are carried out with little apparent stress to either animals or staff.
45
Rosenfeld, Cheryl S. "Sex-Specific Placental Responses in Fetal Development". Endocrinology 156, n. 10 (4 agosto 2015): 3422–34. http://dx.doi.org/10.1210/en.2015-1227.
Testo completoAbstract (sommario):
The placenta is an ephemeral but critical organ for the survival of all eutherian mammals and marsupials. It is the primary messenger system between the mother and fetus, where communicational signals, nutrients, waste, gases, and extrinsic factors are exchanged. Although the placenta may buffer the fetus from various environmental insults, placental dysfunction might also contribute to detrimental developmental origins of adult health and disease effects. The placenta of one sex over the other might possess greater ability to respond and buffer against environmental insults. Given the potential role of the placenta in effecting the lifetime health of the offspring, it is not surprising that there has been a resurging interest in this organ, including the Human Placental Project launched by the National Institutes of Child Health and Human Development. In this review, we will compare embryological development of the laboratory mouse and human chorioallantoic placentae. Next, evidence that various species, including humans, exhibit normal sex-dependent structural and functional placental differences will be examined followed by how in utero environmental changes (nutritional state, stress, and exposure to environmental chemicals) might interact with fetal sex to affect this organ. Recent data also suggest that paternal state impacts placental function in a sex-dependent manner. The research to date linking placental maladaptive responses and later developmental origins of adult health and disease effects will be explored. Finally, we will focus on how sex chromosomes and epimutations may contribute to sex-dependent differences in placental function, the unanswered questions, and future directions that warrant further consideration.
46
Collin, H. Barry, e Shaun P. Collin. "The corneal surface of aquatic vertebrates: microstructures with optical and nutritional function?" Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 355, n. 1401 (29 settembre 2000): 1171–76. http://dx.doi.org/10.1098/rstb.2000.0661.
Testo completoAbstract (sommario):
The anterior surface of the mammalian cornea plays an important role in maintaining a smooth optical interface and consequently a sharp retinal image. The smooth surface is produced by a tear film, which adheres to a variety of microprojections, which increase the cell surface area, improve the absorbance of oxygen and nutrients and aid in the movement of metabolic products across the outer cell membrane. However, little is known of the structural adaptations and tear film support provided in other vertebrates from different environments. Using field emission scanning electron microscopy, this study examines the density and surface structure of corneal epithelial cells in representative species of the classes Cephalaspidomorphi, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves and Mammalia, including some Marsupialia. Variations in cell density and the structure and occurrence of microholes, microridges, microplicae and microvilli are described with respect to the demands placed upon the cornea in different aquatic environments such as marine and freshwater. A progressive decrease in epithelial cell density occurs from marine (e.g. 29348 cells mm −2 in the Dover sole Microstomius pacificus ) to estuarine or freshwater (e.g. 5999 cells mm −2 in the black bream Acanthopagrus butcheri ) to terrestrial (e.g. 2126 cells mm −2 in the Australian koala Phascolarctos cinereus ) vertebrates, indicating the reduction in osmotic stress across the corneal surface. The microholes found in the Southern Hemisphere lampreys, namely the pouched lamprey ( Geotria australis ) and the shorthead lamprey ( Mordacia mordax ) represent openings for the release of mucus, which may protect the cornea from abrasion during their burrowing phase. Characteristic of marine teleosts, fingerprint–like patterns of corneal microridges are a ubiquitous feature, covering many types of sensory epithelia (including the olfactory epithelium and the oral mucosa). Like microplicae and microvilli, microridges stabilize the tear film to maintain a smooth optical surface and increase the surface area of the epithelium, assisting in diffusion and active transport. The clear interspecific differences in corneal surface structure suggest an adaptive plasticity in the composition and stabilization of the corneal tear film in various aquatic environments.
47
Hendry, KA, KJ Simpson, KR Nicholas e CJ Wilde. "Autocrine inhibition of milk secretion in the lactating tammar wallaby (Macropus eugenii)". Journal of Molecular Endocrinology 21, n. 2 (1 ottobre 1998): 169–77. http://dx.doi.org/10.1677/jme.0.0210169.
Testo completoAbstract (sommario):
The lactating tammar wallaby progressively alters the rate of secretion and composition of its milk to provide appropriate nutrition for the developing offspring, whose needs are signalled by changes in the pattern and efficiency of its sucking. Tammars are also capable of asynchronous concurrent lactation, when the mother provides a dilute milk for a newborn young permanently attached to the teat (phase 2A of lactation), and a concentrated milk from an adjacent mammary gland for a young-at-heel (phase 3). The relationship between suckling behaviour and milk secretion, and the ability of adjacent glands to function independently, suggests that milk secretion is controlled locally, within each mammary gland, by a mechanism sensitive to frequency and completeness of milk removal. To determine if tammar milk contains a factor able to control milk secretion, milk fractions have been screened in tissue and cell culture bioassays. A 6-30 kDa fraction of phase 3 whey was found to inhibit milk constituent synthesis and secretion in vitro, and inhibitory activity was associated with two discrete fractions obtained by anion exchange chromatography, which contained protein bands migrating anomalously at 66 kDa and 63 kDa in SDS-PAGE. These bands were recognised in Western blotting by antiserum raised against a bovine autocrine inhibitor of milk secretion. By the same criteria, milk secreted in phase 2B of tammar lactation, when milk secretion is low and suckling intermittent but less vigorous than phase 3, also contained a feedback inhibitor of milk secretion. The results indicate that, as in dairy animals, marsupial milk secretion is under local control through feedback inhibition by a milk protein, and raise the possibility that autocrine feedback may influence the transition from phases of low milk secretion (phase 2A, 2B) to a high rate in the final third phase of lactation.
48
Pineda-Munoz, Silvia, Alistair R. Evans e John Alroy. "The relationship between diet and body mass in terrestrial mammals". Paleobiology 42, n. 4 (18 marzo 2016): 659–69. http://dx.doi.org/10.1017/pab.2016.6.
Testo completoAbstract (sommario):
AbstractDiet and body mass are highly important factors in mammalian ecology, and they have also proven to be powerful paleoecological indicators. Our previous research has proposed a new classification scheme for mammals with more dietary divisions that emphasizes the primary resource in a given diet. We analyzed a database summarizing the dietary preferences of 139 species of marsupial and placental terrestrial mammals (including 14 orders) and their average body masses in order to explore whether this new classification better highlights ecomorphological differences between species. Additionally, the dietary diversity of every species in the data set was quantified by applying the inverse Simpson index to stomach content percentages. We observed a decrease in maximum dietary diversity with increasing body mass. Having lower requirements for energy and nutrients per unit of body weight or ecological advantages such as larger home ranges allows larger mammals to feed on less nutritive feeding resources (i.e., structural plant material). Our results also suggest that body-size ranges are different across dietary specializations. Smaller mammals (<1 kg) are mainly insectivores, granivores, or mixed feeders, while bigger animals (>30 kg) are usually either carnivores or herbivores that feed specifically on grasses and leaves. The medium-size range (1–30 kg) is mostly composed of frugivorous species that inhabit tropical and subtropical rain forests. Thus, the near absence of medium-sized mammals in open environments such as savannas can be linked to the decreasing density of fruit trees needed to support a pure frugivorous diet year-round. In other words, seasonality of precipitation prevents species from specializing on a totally frugivorous diet. Our results suggest that this new classification scheme correlates well with body mass, one of the most studied morphological variables in paleoecology and ecomorphology. Therefore, the classification should serve as a useful basis for future paleoclimatological studies.
49
Wittmann, Karl J., e Pierre Chevaldonné. "First report of the order Mysida (Crustacea) in Antarctic marine ice caves, with description of a new species of Pseudomma and investigations on the taxonomy, morphology and life habits of Mysidetes species". ZooKeys 1079 (31 dicembre 2021): 145–227. http://dx.doi.org/10.3897/zookeys.1079.76412.
Testo completoAbstract (sommario):
SCUBA diving explorations of three islands off Dumont d’Urville Station at the coast of Adélie Land, East Antarctica, enabled the observation of marine ice caves. Sampling in this unusual habitat yielded a total of three species of Mysidae, altogether previously poorly known or unknown to science. Pseudomma kryotroglodytumsp. nov. is described, based on the structure of the antennal scale, telson and on cornea-like lateral portions set off against the main body of eyeplates. Mysidetes illigi is re-established at species level after almost a century in synonymy. Re-descriptions are provided for M. illigi and M. hanseni, based on types and ice cave materials. Keys to the Southern Ocean species of Pseudomma and to the world-wide species of Mysidetes are given. Phylogenetic trees are provided for the genera Pseudomma and Mysidetes. 18S rDNA sequences of P. kryotroglodytum differ from GenBank sequences of other Pseudomma species. First sequence data are given for species of the genus Mysidetes: 18S differs between the two examined species and COI is quite diverse between and within species. We found previously unknown, probably sensorial structures in these ice cave species: in P. kryotroglodytum, the basal segment of the antennula shows a pit-like depression with striated pad on the bottom and a median cyst, connected with the bottom of the eyeplate cleft. M. illigi shows a female homologue of the appendix masculina bearing a field of modified setae. Subsequent investigations demonstrated these structures also in species from other habitats. The feeding apparatus and stomach contents of the three ice cave species point to brushing of small particles (detritus, microalgae) from available surfaces, such as sediment, rock and the ice surface. Differences in the feeding apparatus are very subtle between the two Mysidetes species. The high content of fat bodies in M. hanseni could help it to survive periods of starvation. The large storage volume of the foregut in P. kryotroglodytum points to the collection of food with low nutritional quality and could help to balance strongly fluctuating food availability. Summer specimens of M. hanseni showed a bimodal frequency of developmental stages in the marsupium and bimodal size-frequency distribution of free-living stages. The females with younger brood (embryos) were, on average, larger and carried more marsupial young than those with older brood (nauplioid larvae). All examined incubating and spent females showed (almost) empty foreguts and empty ovarian tubes, suggesting possible semelparity and death following the release of young. The absence of juveniles and immature females from summer samples suggests that growth and accumulation of fat and yolk occur outside ice caves, while such caves could be used by fattened adults as shelter for brooding. A provisional interpretation proposes a biannual life cycle for M. hanseni, superimposed with shifted breeding schedules, the latter characterised by early breeding and late breeding females, probably in response to harsh physical and trophic conditions along the continental coast of Antarctica.
50
Fehrenkamp, B. D., e R. D. Miller. "Opossum Mammary Maturation as It Relates to Immune Cell Infiltration and Nutritional Gene Transcription". Integrative Organismal Biology 2, n. 1 (30 dicembre 2019). http://dx.doi.org/10.1093/iob/obz036.
Testo completoAbstract (sommario):
Synopsis The mammary gland has evolved to accommodate the developmental needs of offspring in species-specific ways. This is particularly true for marsupials. Marsupial milk content changes dramatically throughout lactation in ways appearing timed with neonatal ontogeny and behavior. Here we investigate morphological restructuring within the mammaries throughout lactation in the gray short-tailed opossum, Monodelphis domestica. Substantial remodeling of the mammaries occurs throughout the first half of active lactation. It is not until the latter half of lactation that opossum mammaries appear histologically similar to active eutherian mammaries. Noteworthy was the presence of eosinophils in early developing mammary tissue, which correlated with elevated abundance of transcripts encoding the chemokine IL-16. The presence and abundance of whey protein transcripts within the opossum mammaries were also quantified. Whey acidic protein (WAP) transcript abundance peaked in the latter half of lactation and remained elevated through weaning. Minimal transcripts for the marsupial-specific Early and Late Lactation Proteins (ELP/LLP) were detected during active lactation. Elevated abundance of LLP transcripts was only detected prior to parturition. Overall, the results support the role of eosinophils in mammary restructuring appearing early in mammalian evolution, and describe key similarities and differences in nutritional protein transcript abundance among marsupial species.