Letteratura scientifica selezionata sul tema "Secretion stress"
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Articoli di riviste sul tema "Secretion stress":
1
Seo, Jin, Anja Brencic e Andrew J. Darwin. "Analysis of Secretin-Induced Stress in Pseudomonas aeruginosa Suggests Prevention Rather than Response and Identifies a Novel Protein Involved in Secretin Function". Journal of Bacteriology 191, n. 3 (21 novembre 2008): 898–908. http://dx.doi.org/10.1128/jb.01443-08.
Abstract (sommario):
ABSTRACT Secretins are bacterial outer membrane proteins that are important for protein export. However, they can also mislocalize and cause stress to the bacterial cell, which is dealt with by the well-conserved phage shock protein (Psp) system in a highly specific manner. Nevertheless, some bacteria have secretins but no Psp system. A notable example is Pseudomonas aeruginosa, a prolific protein secretor with the potential to produce seven different secretins. We were interested in investigating how P. aeruginosa might deal with the potential for secretin-induced stress without a Psp system. Microarray analysis revealed the absence of any transcriptional response to XcpQ secretin overproduction. However, transposon insertions in either rpoN, truB, PA4068, PA4069, or PA0943 rendered P. aeruginosa hypersensitive to XcpQ production. The PA0943 gene was studied further and found to encode a soluble periplasmic protein important for XcpQ localization to the outer membrane. Consistent with this, a PA0943 null mutation reduced the levels of type 2 secretion-dependent proteins in the culture supernatant. Therefore, this work has identified a novel protein required for normal secretin function in P. aeruginosa. Taken together, all of our data suggest that P. aeruginosa lacks a functional equivalent of the Psp stress response system. Rather, null mutations in genes such as PA0943 may cause increased secretin-induced stress to which P. aeruginosa cannot respond. Providing the PA0943 mutant with the ability to respond, in the form of critical Psp proteins from another species, alleviated its secretin sensitivity.
2
Delbende, C., C. Delarue, H. Lefebvre, D. Tranchand Bunel, A. Szafarczyk, E. Mocaër, A. Kamoun, S. Jégou e H. Vaudry. "Glucocorticoids, Transmitters and Stress". British Journal of Psychiatry 160, S15 (febbraio 1992): 24–35. http://dx.doi.org/10.1192/s0007125000296657.
Abstract (sommario):
Many kinds of stress stimulate the neuroendocrine systems controlling catecholamine and glucocorticoid secretion. Stress-induced stimulation of CRF-containing neurons appears to be mediated by serotonergic, noradrenergic, and possibly other neuronal pathways. Stress can alter various neurobiological and endocrine functions, two essential components of the neuroendocrine responses being release of adrenalin from chromaffin cells of the adrenal medulla and secretion of glucocorticoids from adrenocortical cells. Activation of adrenal steroid secretion is mainly by a reflex activation of hypothalamic neurons, which stimulate ACTH secretion from the anterior pituitary. While the neuropeptide CRF plays a major role in the neuroendocrine response to stress, the neuronal signals which are responsible for the regulation of CRF neurons have not been completely elucidated. A number of other regulatory substances may also participate, alone or with CRF, in the control of ACTH secretion by pituitary corticotrophs, and there is increasing evidence that classical neurotransmitters or neuropeptides may act directly on adrenocortical cells to modulate corticosteroid secretion. We review the neuronal, neuroendocrine, and humoral pathways which participate in the regulation of stress-induced corticosteroid secretion, and present preliminary data on the effect of the tricyclic antidepressant, tianeptine in the response of the HPA axis to stress.
3
Cramer, Robert A. "Secretion stress and fungal pathogenesis". Virulence 2, n. 1 (gennaio 2011): 1–3. http://dx.doi.org/10.4161/viru.2.1.13902.
4
Aguiar, Tatiana Q., Orquídea Ribeiro, Mikko Arvas, Marilyn G. Wiebe, Merja Penttilä e Lucília Domingues. "Investigation of protein secretion and secretion stress in Ashbya gossypii". BMC Genomics 15, n. 1 (2014): 1137. http://dx.doi.org/10.1186/1471-2164-15-1137.
5
Žarković, Miloš, Elka Stefanova, Jasmina Ćirić, Zorana Penezić, Vladimir Kostić, Mirjana Šumarac-Dumanović, Djuro Macut, Miomira S. Ivović e Predrag V. Gligorović. "Prolonged psychological stress suppresses cortisol secretion". Clinical Endocrinology 59, n. 6 (20 novembre 2003): 811–16. http://dx.doi.org/10.1046/j.1365-2265.2003.01925.x.
6
Holtmann, Gerald, Reinholde Kriebel e Manfred V. Singer. "Mental stress and gastric acid secretion". Digestive Diseases and Sciences 35, n. 8 (agosto 1990): 998–1007. http://dx.doi.org/10.1007/bf01537249.
7
Giuliani, Fabrizio, Adam Grieve e Catherine Rabouille. "Unconventional secretion: a stress on GRASP". Current Opinion in Cell Biology 23, n. 4 (agosto 2011): 498–504. http://dx.doi.org/10.1016/j.ceb.2011.04.005.
8
Freeman, H., K. Shimomura, R. D. Cox e F. M. Ashcroft. "Nicotinamide nucleotide transhydrogenase: a link between insulin secretion, glucose metabolism and oxidative stress". Biochemical Society Transactions 34, n. 5 (1 ottobre 2006): 806–10. http://dx.doi.org/10.1042/bst0340806.
Abstract (sommario):
This paper reviews recent studies on the role of Nnt (nicotinamide nucleotide transhydrogenase) in insulin secretion and detoxification of ROS (reactive oxygen species). Glucose-stimulated insulin release from pancreatic β-cells is mediated by increased metabolism. This elevates intracellular [ATP], thereby closing KATP channels (ATP-sensitive potassium channels) and producing membrane depolarization, activation of voltage-gated Ca2+ channels, Ca2+ influx and, consequently, insulin secretion. The C57BL/6J mouse displays glucose intolerance and reduced insulin secretion, which results from a naturally occurring deletion in the Nnt gene. Transgenic expression of the wild-type Nnt gene in C57BL/6J mice rescues the phenotype. Knockdown of Nnt in the insulin-secreting cell line MIN6 with small interfering RNA dramatically reduced Ca2+ influx and insulin secretion. Similarly, mice carrying ENU (N-ethyl-N-nitrosourea)-induced loss-of-function mutations in Nnt were glucose intolerant and secreted less insulin during a glucose tolerance test. Islets isolated from these mice showed impaired insulin secretion in response to glucose, but not to the KATP channel blocker tolbutamide. This is explained by the fact that glucose failed to elevate ATP in Nnt mutant islets. Nnt is a nuclear-encoded mitochondrial protein involved in detoxification of ROS. β-Cells isolated from Nnt mutant mice showed increased ROS production on glucose stimulation. We hypothesize that Nnt mutations enhance glucose-dependent ROS production and thereby impair β-cell mitochondrial metabolism, possibly via activation of uncoupling proteins. This reduces ATP production and lowers KATP channel activity. Consequently, glucose-dependent electrical activity and insulin secretion are impaired.
9
Zhang, Irina X., Jianhua Ren, Suryakiran Vadrevu, Malini Raghavan e Leslie S. Satin. "ER stress increases store-operated Ca2+ entry (SOCE) and augments basal insulin secretion in pancreatic beta cells". Journal of Biological Chemistry 295, n. 17 (16 marzo 2020): 5685–700. http://dx.doi.org/10.1074/jbc.ra120.012721.
Abstract (sommario):
Type 2 diabetes mellitus (T2DM) is characterized by impaired glucose-stimulated insulin secretion and increased peripheral insulin resistance. Unremitting endoplasmic reticulum (ER) stress can lead to beta-cell apoptosis and has been linked to type 2 diabetes. Although many studies have attempted to link ER stress and T2DM, the specific effects of ER stress on beta-cell function remain incompletely understood. To determine the interrelationship between ER stress and beta-cell function, here we treated insulin-secreting INS-1(832/13) cells or isolated mouse islets with the ER stress–inducer tunicamycin (TM). TM induced ER stress as expected, as evidenced by activation of the unfolded protein response. Beta cells treated with TM also exhibited concomitant alterations in their electrical activity and cytosolic free Ca2+ oscillations. As ER stress is known to reduce ER Ca2+ levels, we tested the hypothesis that the observed increase in Ca2+ oscillations occurred because of reduced ER Ca2+ levels and, in turn, increased store-operated Ca2+ entry. TM-induced cytosolic Ca2+ and membrane electrical oscillations were acutely inhibited by YM58483, which blocks store-operated Ca2+ channels. Significantly, TM-treated cells secreted increased insulin under conditions normally associated with only minimal release, e.g. 5 mm glucose, and YM58483 blocked this secretion. Taken together, these results support a critical role for ER Ca2+ depletion–activated Ca2+ current in mediating Ca2+-induced insulin secretion in response to ER stress.
10
Turakulov, Ya Kh, R. B. Burikhanov, P. P. Patkhitdinov e A. I. Myslitsksya. "Immobilization stress effect on thyroid hormone secretion". Problems of Endocrinology 39, n. 5 (14 ottobre 1993): 47–48. http://dx.doi.org/10.14341/probl11990.
Abstract (sommario):
Analysis of blood flowing from the rat thyroid has shown that an acute immobilization stress enhanced thyroid hormone secretion with an increase of the T3/T4-100 index. The most marked response to stress was observed after repeated 2 min immobilization with a 3 min interval: Such increase of secretion was arrested by injection of prasosin, an -adrenoblocker. Propylthiouracil injected an hour before the experiment reduced T4 thyroid conversion index. These results permit a conclusion that short-term repeated immobilization enhanced thyroid hormone secretion via -adrenergic system stimulation, this being paralleled by increased production of hormonally more active T3.
Tesi sul tema "Secretion stress":
1
Smart, Darren. "Stressors & LH secretion in the ewe". Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333607.
2
Parker, Victoria Joanne. "Hypothalamic mechanisms mediating inhibition of prolactin secretion following stress in early pregnant mice". Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6485.
Abstract (sommario):
In early pregnancy prolonged exposure to stress is known to have profound adverse effects on reproduction and is associated with suppressed progesterone secretion and consequent disturbance of the pregnancy-protective cytokine milieu, thus threatening early pregnancy maintenance. Maternal neuroendocrine responses to stress in early pregnancy are poorly understood. Therefore, we designed experiments to (1) study the hypothalamo-pituitary-adrenal (HPA) axis responses to stress in early pregnant mice, to discover whether and how responses change and (2) to determine the effect of stress in early gestation on pregnancy hormones, with a particular focus on the secretion and regulation of prolactin. To establish the effects of stress in early pregnancy (day 5.5) two different ethologically relevant stressors were used: lipopolysaccharide (LPS) or 24h fast stress, to mimic situations that may potentially arise during pregnancy in women: infection or hunger. HPA axis secretory responses to immune stress in early-mid pregnancy were robust and comparable to that in virgins. Vasopressin rather than the usual CRH neurone responses play a key role in maintaining this. However, the mode of action of glucocorticoids in mediating pregnancy complications is not yet established. Prolactin, and its hypothalamic control mechanisms, is a key candidate to mediate brain-to-body responses to stress. Prolactin has important roles in progesterone secretion, pregnancy establishment and immune regulation. We hypothesised that stress would negatively affect prolactin and its neuroendocrine control systems. Prolactin is mainly under the inhibitory control of dopamine, released predominantly from the tuberoinfundibular dopamine (TIDA) neurones. Prolactin also negatively feeds back on itself via prolactin receptors on the TIDA neurones and janus kinase (JAK)2/signal transducer and activator of transcription (STAT)5 signalling. Both immune and fasting stressors strongly inhibited basal prolactin secretion in early pregnancy, accompanied by a mild increase in activation of TIDA as shown by elevated Fos expression, compared to virgins. In addition, pregnancy attenuated LPS-induced recruitment of parvocellular paraventricular nucleus neurones and increased activation of brainstem noradrenergic nuclei which could potentially contribute to altered control of the dopamine-prolactin system. Following either immune or fast stress in early pregnancy ovine prolactin was able to drive enhanced expression of phosphorylated (p)STAT5. However, stress alone did not alter pSTAT5 implying it is not exclusively responsible for the stress-reduced prolactin observed in early pregnancy and another stress-induced stimulus must be activating TIDA neurones in these mice. LPS did not alter dopamine activity the median eminence (DOPAC: dopamine ratio) suggesting dopamine does not underlie stress-reduced prolactin secretion and other mechanisms must be considered. Direct effects of LPS, or its associated cytokines, on pituitary lactotrophs to inhibit prolactin secretion is a possible candidate. To investigate the effect of proinflammatory cytokines on the prolactin system in early pregnancy, d5.5 mice were administered TNF-alpha (a) or interleukin (IL)-6. Both cytokines increased TIDA activation, however, only TNF-a decreased plasma prolactin and progesterone, suggesting additional TNF-alpha action at the pituitary. As prolactin is anxiolytic we further proposed that stress would have a more profound effect on elevated plus maze performance in pregnant mice. However, early pregnant mice were generally more anxious vs. virgins regardless of LPS treatment. Taken together data show that stress in early pregnancy reduces prolactin and progesterone secretion, contributing to pregnancy complications/failure, but the neuroendocrine stress-related mechanism behind this suppression is yet to be determined.
3
Kim, Beob Gyun. "INFLUENCES OF CHROMIUM (III) PICOLINATE ON PIGS UNDER THERMAL, IMMUNE OR DIETARY STRESS, AND ON ADRENAL STEROID SECRETION". UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_diss/560.
Abstract (sommario):
The objectives were to investigate the effects of chromium (III) picolinate (CrPic; up to 2,000 ppb of Cr) on growing pigs subjected to a variety of stressors including thermal, immune, or dietary stress and to examine the effects of CrPic on steroidogenesis from adrenocortical cells. In the thermal stress study, high ambient temperature caused reduced weight gain and feed consumption (P andlt; 0.01), and low ambient temperature caused increased feed intake and feed:gain (P andlt; 0.01). However, these effects were not moderated by CrPic, and respiratory rate, plasma cortisol, or plasma glucose were unaffected by CrPic. In the immune stress study, pigs challenged with lipopolysaccharide (LPS) lost 951 g during 12 hours post injection, while the phosphate buffer saline (PBS) injected group gained 170 g (P andlt; 0.001). The LPS group showed higher rectal temperature (P andlt; 0.05), higher respiratory rate (P andlt; 0.05), greater plasma cortisol (P andlt; 0.001), and lower plasma glucose (P andlt; 0.05) than the PBS group. These effects were not ameliorated by CrPic. In the dietary stress study, pigs fed the high-fat diet (HFD) gained weight faster (P andlt; 0.05), consumed less feed (P andlt; 0.001), and had lower feed:gain (P andlt; 0.001). Plasma insulin concentration on d 14 decreased with CrPic (P andlt; 0.05) in a linear manner (P = 0.05). Consumption of the HFD resulted in increases of slaughter weight, perirenal fat, and back fat measurements (P andlt; 0.01). The CrPic resulted in linear reductions of carcass weight, last rib fat, last lumbar fat and average backfat (P andlt; 0.10). The effects of CrPic on carcass fat measurements were more significant in barrows than gilts. In the adrenocortical cell study, forskolin stimulated cortisol and DHEAs secretion from H295R cells. CrPic inhibited aspects of steroidogenesis in agonist-stimulated adrenocortical cells. Overall, dietary CrPic was unable to moderate the stress related effects due to high ambient temperature, low ambient temperature, or an endotoxin challenge. However, CrPic attenuated effects of HFD, mainly on body fat accretion of pigs, especially in barrows, and CrPic inhibited steroidogenesis in stimulated adrenocorticoid cells.
4
Kosti, Ourania. "Intra-adrenal mechanisms in the control of steroid secretion and the response to stress". Thesis, Queen Mary, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411344.
5
Weber, Barbara. "Stress response and virulence in Vibrio anguillarum". Doctoral thesis, Umeå : Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet), Umeå universitet, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-33269.
6
Marin, Marie-France. "Immediate and delayed effects of stress on a reactivitated declarative long-term memory trace". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116034.
Abstract (sommario):
In 1968, a study demonstrated that consolidated memories can be affected again if they are reactivated. Given the importance of the stress hormones glucocorticoids (GCs) on memory consolidation, the goal of the current study was to assess whether GCs had the capacity to affect a reactivated long-term memory and whether neutral and emotional memories were affected differently. At the first session, participants encoded a movie containing neutral and emotional scenes. Two days later, they recalled the story. Half of them were then exposed to a psychosocial stressor. Memory performance was assessed again right after the stressor and five days later. The stressed group recalled less neutral material five days after the stressor compared to controls. Immediately after the stressor, the stressed group recalled more emotional material than controls. Moreover, this enhanced memory trace was maintained across time. This highlights the importance of minimizing exposure to stressful contexts when reactivating emotional memories.
7
Pilgrim, Kamala. "Mechanisms underlying cortisol reactivity to stress in low and high socioeconomic status individuals : role of naturally-occurring attentional biases". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116040.
Abstract (sommario):
This Master's dissertation explored whether a rapid orienting of attention toward or away from social stress information during a restful state, relates to the magnitude of glucocorticoids (GC) released in response to a stressor, the Trier Social Stress Test (TSST). It also assessed whether childhood rearing in a low socioeconomic status (SES) context mediates this relationship. Subjects rested for 45 minutes during which time they completed a modified version of Posner's attention paradigm, comprising social stress words. Immediately following, participants were exposed to the stressor. Results indicated that a rapid attentional engagement toward social stress words associated with pronounced GC responses to the TSST. Fast engagers displayed lower self-esteem and did not differ in terms of their past SES. These findings demonstrate that attentional biases for social stress information at rest combine with diminished self-esteem to predict the magnitude of GC released during psychological stress irrespective of early SES conditions.
8
Valiquette, Luc François. "Association between self-reported childhood maltreatment and cortisol profiles in psychotic patients". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112314.
Abstract (sommario):
Childhood maltreatment is extremely common in patients diagnosed with psychotic disorders. Moreover, it has been linked with impaired functioning of the Hypothalamic-Pituitary-Adrenal axis. Furthermore, abnormality of the HPA has been found in psychotic patients. Presence of childhood maltreatment could then explain why the HPA axis is dysfunctional in these subjects. Our objective was to clarify the role of childhood trauma in the cortisol profiles of psychotic patients. Thirty-one patients underwent assessments of childhood maltreatment. Diurnal cortisol and cortisol after a controlled psychosocial stress were also collected. Our results show that childhood trauma is associated with lower cortisol levels during the morning and during 24 hours. In men diagnosed with psychosis, childhood trauma is also associated with a higher cortisol response during psychosocial stress. This suggests an alteration of the HPA axis in psychotic patients, resulting from early trauma. Moreover, our results suggest that looking at specific types of childhood abuse may also be important.
9
Alharake, Jawad. "Study of genetic factors involved in enzyme secretion in hyperproductive strains of Trichoderma reesei". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASB061.
Abstract (sommario):
Les combustibles fossiles sont un contributeur majeur au réchauffement climatique, et leur nature non renouvelable est un obstacle à la construction de sociétés durables. Dans ce contexte, les biocarburants de seconde génération se présentent comme une alternative attractive et plus respectueuse de l'environnement. Le processus de production de biocarburants de deuxième génération comprend plusieurs étapes incluant le prétraitement physico-chimique de la biomasse lignocellulosique (non comestible), l'hydrolyse enzymatique de la cellulose en glucose et par la fermentation de sucres simples en biocarburants, comme le bioéthanol. Un des problèmes principaux pour une large application est cependant le coût relativement élevé des enzymes hydrolytiques, les cellulases, utilisées pour déconstruire la biomasse lignocellulosique prétraitée en sucres fermentescibles.Le champignon filamenteux Trichoderma reesei est le choix privilégié pour la production industrielle de cellulases car il possède des capacités d'hyperproduction et d'hypersécrétion. Les souches industrielles de T. reesei peuvent sécréter jusqu'à 100 g/L de cellulases dans des fermenteurs industriels contrôlés. En particulier, la souche mutante Rut-C30 est une souche hyperproductrice de référence, mais notre compréhension incomplète de son système de sécrétion performant complique l'amélioration de sa capacité d'hypersécrétion par génie génétique. C'est pourquoi, ce travail visait à éclaircir les voies de régulation contrôlant la sécrétion et les réponses au stress de sécrétion pour identifier des goulots d'étranglement et pour développer de nouvelles souches dotées d'une capacité de sécrétion supérieure dans le futur.Dans ce but, des données transcriptomiques étaient générées à partir de cultures de T. reesei Rut-C30 dans différentes conditions de stress de sécrétion et ont permis d'identifier de composants potentiels de régulation de la sécrétion qui pouvaient être ciblés pour invalidation. Pour compléter cette approche, un datamining de données transcriptomiques obtenues avec d'autres champignons filamenteux cultivés dans des conditions de stress de sécrétion a révélé d'autres gènes cibles potentiellement impliqués dans la régulation de la voie de sécrétion. Finalement, neuf gènes ont été invalidés dans la souche Rut-C30 et les mutants obtenus ont été caractérisés phénotypiquement. Tous ont montré une croissance ralentie et un comportement de sécrétion altéré. Un séquençage de l'ARN a été réalisé sur les mutants ∆res2, ∆rpn4 and ∆snd1 et comparé à celui de Rut-C30 dans les mêmes conditions de culture. Aucun des trois facteurs de transcription n'impacte la transcription des gènes impliqués dans la sécrétion ou dans la réponse au stress de sécrétion dans nos conditions. En revanche, des gènes codant pour des enzymes du métabolisme des lipides sont différentiellement exprimés dans les trois mutants ce qui pourrait affecter la sécrétion indirectement. Les résultats délivrent des premiers indices pour atténuer les goulots d'étranglement de la sécrétion dans T. reesei Rut-C30 et ouvrent la voie vers le développement de souches possédant une capacité de sécrétion amélioréeFossil fuels are a major contributor to global warming, and their non-renewable nature is an impediment for building sustainable societies. In this context, second generation biofuels represent an attractive and more environmentally friendly alternative. The process of second-generation biofuel production consists of several steps including a physicochemical pretreatment of lignocellulosic (non-edible) biomass, the enzymatic hydrolysis of cellulose into glucose and the fermentation of simple sugars into biofuels, such as bioethanol. One of the main bottlenecks for a large implementation of this process is, however, the relatively high cost of hydrolytic enzymes, namely cellulases, used to deconstruct the pretreated lignocellulosic biomass into fermentable sugars.The filamentous fungus Trichoderma reesei is the preferred choice for industrial production of cellulases since it has hyperproduction and hypersecretion capacities. Industrial strains of T. reesei can secrete up to 100 g/L of cellulases in controlled industrial fermenters. In particular, the mutant strain Rut- C30 is a reference hyperproducer strain, but our incomplete understanding of its enhanced secretion system complicates further improvement of its hypersecretion capacity by genetic engineering. Therefore, this work aimed at unravelling the regulatory pathways controlling secretion and the secretion stress response in order to identify bottlenecks and to develop new strains with enhanced secretion capacity in the future.To this end, transcriptomic data were generated from cultivations of T. reesei Rut-C30 in different secretion stress conditions which allowed to identify potential components of secretion regulation that were targeted for deletion. As a complementary approach, mining of transcriptomic data obtained with other filamentous fungi in secretion stress conditions revealed further target genes potentially involved in the regulation of the secretion pathway. Finally, nine genes were deleted in the Rut-C30 strain, and the resulting strains phenotypically characterized. All of them displayed reduced growth and showed altered protein secretion behavior. RNA sequencing was performed on ∆res2, ∆rpn4 and ∆snd1 mutant strains and compared to that of Rut-C30 in the same culture conditions. Neither of the three transcription factors impacts transcription of genes involved in secretion or the secretion stress response in our conditions. However, in all three mutants, genes encoding enzymes of lipid metabolism are differentially expressed which could affect secretion in an indirect way. The results represent first clues to alleviate bottlenecks in secretion in T. reesei Rut-C30 and pave the way to develop strains with still improved secretion capacity
10
Solà, Tapias Núria. "The involvement of the three main inflammatory bowel disease pathways and the secretion of trypsin proteolytic activity on intestinal epithelial cells". Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30049/document.
Abstract (sommario):
Les maladies inflammatoires chroniques de l'intestin (MICI) se caractérisent par une inflammation sévère de l'intestin grêle et du côlon et comprennent la maladie de Crohn (MC) et la rectocolite hémorragique (RCH). Les MICI sont des maladies complexes faisant intervenir des facteurs génétiques : certains senseurs bactériens, l'autophagie et le stress du réticulum endoplasmique. Un défaut de barrière de l'épithélium digestif est également fortement impliqué dans la physiopathologie du processus inflammatoire. La fonction barrière de l'épithélium digestif est assurée par plusieurs types cellulaires, synthétisant entre autres, des peptides antimicrobiens (PAM) et des mucines. Dans les MICI, une augmentation de la perméabilité intestinale et une perte de muco-sécrétion ont été décrites. Les protéases jouent un rôle fondamental dans la digestion du bol alimentaire mais également dans le maintien de l'homéostasie intestinale en activant ou dégradant divers motifs moléculaires, ou in induisant des signaux spécifiques aux cellules par l'activation de quatre récepteurs : les PARs (Protease-Activated Receptor). Dans les MICI, un excès d'activité protéolytique de type trypsine est observé. L'origine de cette activité est théoriquement attribuée aux cellules immunitaires, à une surproduction pancréatique ou au microbiote, mais les cellules épithéliales intestinales semblent également être une source majeure de protéases. L'objectif de mon projet de thèse visait à étudier l'impact des principales voies impliquées dans les MICI sur l'homéostasie des protéases épithéliales et le rôle de celles-ci dans la déstabilisation de la fonction de barrière. Nos résultats ont confirmé un excès de protéases à sérine dans les cellules épithéliales de patients atteint de MC ou de RCH. In vitro, sur des monocouches de cellules Caco-2, l'induction de l'autophagie diminuait la libération apicale de protéase de type trypsine, alors que le senseur bactériens NOD2 n'avait aucun effet. A l'inverse, une stimulation du Stress du réticulum endoplasmique (SRE) par la Thapsigargin, induisait une libération accrue de protéases actives de type trypsine au pôle apical des cellules. [...]Crohn's disease (CD) and Ulcerative colitis (UC) are two forms of Inflammatory Bowel Disease (IBD), a chronic inflammatory pathology affecting the digestive tract. Patients suffer from relapsing flares, diarrhea, abdominal pain and bleeding. Although the molecular mechanisms of IBD are poorly understood, recent data suggest that IBD occurs in genetically predisposed individuals developing an abnormal immune response to intestinal microbes after, being exposed to specific environmental triggers. Genetic studies have reported more than 170 polymorphisms susceptible to be involved in IBD pathogenesis. The strongest associations have highlighted three main pathways altered in IBD including bacterial sensing (NOD2, CD), autophagy (ATG16L1 and IRGM, CD) and endoplasmic reticulum stress (ER-Stress) (XBP1, UC). The role of intestinal barrier function is also strongly implicated in IBD pathogenesis, and is modulated by factors present in the lumen derived from microbiota, food or at a molecular level, by factors such as proteases. In IBD pathophysiology, the inflammatory process is characterized by impaired intestinal biology including disruption of tight junctions and leaky gut, decreased amount of Paneth and Goblet cells, and translocation of luminal antigens triggering inflammation. Previous studies have demonstrated an increased level of active serine proteases in the stools and tissues of IBD patients, supposing that proteases originate from infiltrated immune cells, pancreatic secretion or microbiota. However, our team has reported that intestinal epithelial cells are a major source of serine proteases, in particular trypsin-like enzymes, are released by a stressed epithelium in pathogenic context such as irritable bowel syndrome. In this project, we aimed at better understanding whether the three main pathways involved in IBD (Nod2, autophagy, ER-stress) could be linked to an epithelial release of trypsin and reciprocally, if epithelial trypsin is able to induce or modulate these three IBD pathways. We confirmed that trypsin-like activity was significantly higher in biopsies from UC and CD patients compared to healthy controls. In Caco-2 monolayers cultured in transwells, secreted trypsin-like proteolytic activity remained stable upon NOD2 stimulation but decreased under autophagy induction. Thapsigargin (Tg) stimulation a well-known ER-stress inducer, enhanced the apical release of trypsin-like activity in Caco2 cells. [...]
Libri sul tema "Secretion stress":
1
E, Hernandez Daniel, Glavin Gary B, New York Academy of Sciences., University of Southern California. School of Medicine. Postgraduate Division. e International Conference: Biology of Stress Ulcers (1988 : Lake Arrowhead, Calif.), a cura di. Neurobiology of stress ulcers. New York, N.Y: New York Academy of Sciences, 1990.
2
Isasi, José Luis Cano. El secreto del tren eléctrico. [Lima]: CIPUR, 1989.
3
Escamilla, David. Los secretos de las calles de Barcelona. Teià (Barcelona): Ma Non Troppo, 2010.
4
Desberg, Stephen. El Escorpión 2: El secreto del papa. Barcelona: Norma, 2003.
5
Barreto, Mascarenhas. Cristóvão Colombo, agente secreto de el-Rei D. João II. Porto [Portugal]: Ediões ASA, 1992.
6
Herman, James P. Limbic Pathways to Stress Control. A cura di Israel Liberzon e Kerry J. Ressler. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780190215422.003.0008.
Abstract (sommario):
Appropriate control of the HPA (hypothalamo-pituitary-adrenocortical axis) is required for adaptation to physiological and environmental challenges. Inadequate control is linked to numerous stress-related pathologies, including PTSD, highlighting its importance in linking physiological stress responses with behavioral coping strategies. This chapter highlights neurocircuit mechanisms underlying HPA axis adaptation and pathology. Control of the HPA stress response is mediated by the coordinated activity of numerous limbic brain regions, including the prefrontal cortex, hippocampus, and amygdala. In general, hippocampal output inhibits anticipatory HPA axis responses, whereas amygdala subnuclei participate in stress activation. The prefrontal cortex plays an important role in inhibition of context-dependent stress responses. These regions converge on subcortical structures that relay information to paraventricular nucleus corticotropin-releasing hormone neurons, controlling the magnitude and duration of HPA axis stress responses. The output of these neural networks determines the net effect on glucocorticoid secretion, both within the normal adaptive range and in pathological circumstances.
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Neuroendocrinology of gastrointestinal ulceration. New York: Plenum Press, 1995.
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Young, Allan H., e Mario F. Juruena. Hypothalamic–pituitary–adrenal axis. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198789284.003.0006.
Abstract (sommario):
Increased adrenocortical secretion of hormones, primarily cortisol in depression, is one of the most consistent findings in neuropsychiatry. The maintenance of the internal homeostatic state of an individual is facilitated by the ability to circulate glucocorticoids to exert negative feedback on the secretion of hypothalamic–pituitary–adrenal (HPA) hormones through binding to mineralocorticoid and glucocorticoid receptors, thus limiting the vulnerability to diseases related to psychological stress in genetically predisposed individuals. The HPA axis response to stress can be thought of as a crucial part of the organism’s response to stress: acute responses are generally adaptive, but excessive or prolonged responses can lead to deleterious effects. A spectrum of conditions may be associated with increased and prolonged activation of the HPA axis, including depression, poorly controlled diabetes mellitus, and metabolic syndrome. HPA axis dysregulation and hypercortisolaemia may further contribute to a hyperglycaemic or poorly controlled diabetic state.
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Marini, John J., e Paolo Formenti. Pathophysiology and prevention of sputum retention. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0119.
Abstract (sommario):
Retention of airway mucus is one of the major problem that confronts post-operative and critically-ill patients, as well as the caregivers that address it. Retained secretions increase the work of breathing and promote hypoxaemia, atelectasis, and pneumonia. The airway-intubated patient is at particular risk of retaining mucus, as the presence of the tube interrupts normal flow of airway secretions toward the larynx by the mucociliary escalator and coughing effectiveness is degraded by a glottis that is stented open and cannot close effectively. Clearance of mucus is aided by using sufficient gas stream and total body hydration to reduce sputum viscosity and lubricate secretion plugs. Airway suctioning, a routine, but inherently traumatic experience for the patient, may clear the central airway, but leave peripheral airways unrelieved of their secretion burden. Prone positioning appears to confer an advantage regarding secretion drainage and clearance. Physiotherapy techniques may be useful in re-establishing and maintaining airway patency.
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Szabo, Sandor, Gary B. Glavin e Yvette Taché. Neuroendocrinology of Gastrointestinal Ulceration. Springer London, Limited, 2012.
Capitoli di libri sul tema "Secretion stress":
1
Dias, Marcos Vinicios Salles, Vilma Regina Martins e Glaucia Noeli Maroso Hajj. "Stress-Inducible Protein 1 (STI1): Extracellular Vesicle Analysis and Quantification". In Unconventional Protein Secretion, 161–74. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-3804-9_11.
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Genazzani, A. R., F. Petraglia, S. Angioni, G. Comitini, S. Bettelli, B. Preti, F. Amato, N. Tesorio e M. C. Galassi. "Opioid Control of Gonadotropin Secretion". In Endorphins in Reproduction and Stress, 3–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75797-6_1.
3
Redei, Eva, e Christopher J. Evans. "Dual Control of Corticotropin Secretion: Isolation of Corticotropin-Inhibiting Factor". In Neuropeptides and Stress, 61–72. New York, NY: Springer New York, 1989. http://dx.doi.org/10.1007/978-1-4612-3514-9_6.
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Szalay, K. SZ. "Effects of β-Endorphin on Adrenocortical Steroid Secretion". In Endorphins in Reproduction and Stress, 118–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75797-6_13.
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Reichlin, Seymour. "Prolactin and Growth Hormone Secretion in Stress". In Advances in Experimental Medicine and Biology, 353–76. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4899-2064-5_28.
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Plotsky, Paul M. "Hypophysiotropic Regulation of Stress-Induced ACTH Secretion". In Advances in Experimental Medicine and Biology, 65–81. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4899-2064-5_6.
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Ammon, H. P. T. "Islet redox state, calcium uptake and insulin secretion: Effects of old age and oxidative stress". In Oxidative Stress and Aging, 259–76. Basel: Birkhäuser Basel, 1995. http://dx.doi.org/10.1007/978-3-0348-7337-6_25.
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Pfeiffer, D. G., e A. Pfeiffer. "Differential Role of μ- and κ-Opiate Receptors in Anterior Pituitary Hormone Secretion". In Endorphins in Reproduction and Stress, 30–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75797-6_4.
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Hightower, Lawrence E., e Emily J. Noonan. "Discovery of the Cellular Secretion of Cell Stress Proteins". In Heat Shock Proteins, 1–11. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-4740-1_1.
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Van Loon, Glen R., Judith A. Kiritsy-Roy, Laura V. Brown e Frances A. Bobbitt. "Nicotinic Regulation of Sympathoadrenal Catecholamine Secretion: Cross-Tolerance to Stress". In Tobacco Smoking and Nicotine, 263–76. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-1911-5_16.
Atti di convegni sul tema "Secretion stress":
1
Sylar, E., Y. Zhang, A. Vetticaden, A. D. Rice e T. Wang. "Endotoxin and Mechanical Stress Activate the Biosynthesis and Secretion of Placental Growth Factor". In American Thoracic Society 2019 International Conference, May 17-22, 2019 - Dallas, TX. American Thoracic Society, 2019. http://dx.doi.org/10.1164/ajrccm-conference.2019.199.1_meetingabstracts.a1978.
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Qi, Pei-shi, Wen-bin Wang e Zheng Qi. "Effect of Shear Stress on Biofilm Morphological Characteristics and the Secretion of Extracellular Polymeric Substances". In 2008 2nd International Conference on Bioinformatics and Biomedical Engineering (ICBBE '08). IEEE, 2008. http://dx.doi.org/10.1109/icbbe.2008.363.
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Natalini, J., KM Hallow e SN Ghadiali. "Effect of Fluid Shear Stress and Microbubble Flows on Surfactant Secretion from Alveolar Epithelial Cells." In American Thoracic Society 2009 International Conference, May 15-20, 2009 • San Diego, California. American Thoracic Society, 2009. http://dx.doi.org/10.1164/ajrccm-conference.2009.179.1_meetingabstracts.a1235.
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Morise, M., Y. Ito, T. Ohashi, T. Matsuno, Y. Hibino, M. Kondo, K. Imaizumi, H. Kume e Y. Hasegawa. "Unique Effects of Oxidative Stress on cAMP-Mediated Anion Secretion in Human Airway Epithelial Cells." In American Thoracic Society 2009 International Conference, May 15-20, 2009 • San Diego, California. American Thoracic Society, 2009. http://dx.doi.org/10.1164/ajrccm-conference.2009.179.1_meetingabstracts.a4940.
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Laustiola, K., R. Lassila, P. Koskinen e V. Manninen. "GEMFIBROZIL HAS ANTI-PLATELET EFFECTS IN PATIENTS WITH HYPERCHOLESTEROLAEMIA DURING PHYSICAL STRESS". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643462.
Abstract (sommario):
Earlier studies indicate an increased platelet reactivity in patients with hypercholesterolaemia. Physical and mental stress have also been reported to cause increased reactivity. The present study was undertaken to evaluate the effect of gemfibrozil (G) a new lipid lowering drug on platelet reactivity during physical stress. Ten otherwise healthy male subjects with serum cholesterol levels above 7 mmol/l were involved in a double-blind study. It consisted of two treatment periods of 8 weeks during which the patients were given either G (600 mg b.i.d.) or placebo (PI) and an 8 weeks wash-out period before the cross-over. At the end of the treatment periods an exercise test was carried out and platelet reactivity tested. Adrenaline, ADP and collagen were used to induce aggregation and 5-HT and T×B2 release measured. Plasma beta-TG and fibrinogen were also determined.The treshold concentration of adrenaline necessary to evoke secondary aggregation was increased in 8/10 patients during exercise after G treatment and in 2/10 after PI. When the lowest ADP concentration to cause secondary aggregation (2-4 uM) was used there was a significant decrease in the 5-HT (− 44%) and T×B2 (− 48%) secretion and a significant decrease in the area under the aggregation curve (− 28%). A decrease in 5-HT secretion was also seen after G treatment when a fixed ADP concentration of 10 uM was used. During collagen stimulation no changes were seen between the two groups. Beta-TG remained unchanged irrespective of treatment and fibrinogen showed a modest increase during exercise in both treatment groups. These results indicate a new anti-platelet effect of gemfibrozil which might be of importance in prevention of acute thrombotic events in hypercho1estero1aemic patients.
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Zhang, Ji, e Morton H. Friedman. "The Adaptive Response of Endothelial Transcription to Increased Shear Stress In Vitro". In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19318.
Abstract (sommario):
Previous studies have shown a substantial effect of shear stress on endothelial phenotype and functions such as production of nitric oxide, secretion of growth factors, inflammatory responses, production of reactive oxygen species, permeability to macromolecules and cytoskeletal remodeling [1–3]. However, the dynamics of the endothelial adaptive response to changes in shear stress are largely unknown. The response of vascular endothelial cells to alterations in shear stress is an essential component of normal endothelial physiology, since local shear stress can be altered in vivo by the global hemodynamic changes that are caused by daily activities such as exercise, sleep, smoking and stress. The duration of these changes ranges from minutes to hours. When adapting to the altered shear stress, endothelial cells undergo a series of structural remodeling and morphological changes, and a transient alteration of endothelial phenotype will be induced. An understanding of the transient regulation of endothelial phenotype will not only improve our knowledge of normal endothelial physiology but also yield insights into mechanisms underlying atherogenesis.
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Karacsonyi, C., N. Shanmugam e E. Kagan. "Vesicant-Induced Airway Epithelial Cytokine Secretion Is Mediated Via Epidermal Growth Factor Receptor (EGFR) Signaling and Oxidant Stress." In American Thoracic Society 2009 International Conference, May 15-20, 2009 • San Diego, California. American Thoracic Society, 2009. http://dx.doi.org/10.1164/ajrccm-conference.2009.179.1_meetingabstracts.a2818.
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Nomura, Shusaku, Tota Mizuno, Akio Nozawa, Hirotoshi Asano e Hideto Ide. "The difference in stress induced secretion of an immune substance by the schedule of an intermittent mental workload". In 2008 IEEE International Conference on Systems, Man and Cybernetics (SMC). IEEE, 2008. http://dx.doi.org/10.1109/icsmc.2008.4811264.
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Pirogov, Aleksey, Irina Andrievskaya, Anna Prikhodko, Viktor Kolosov e Yuliy Perelman. "PHOSPHATASE ACTIVITY AND POSSIBILITIES OF LYSOSOMAL SECRETION OF AIRWAY NEUTROPHILS IN PATIENTS WITH BRONCHIAL ASTHMA IN COLD-INDUCED STRESS". In XIV International Scientific Conference "System Analysis in Medicine". Far Eastern Scientific Center of Physiology and Pathology of Respiration, 2020. http://dx.doi.org/10.12737/conferencearticle_5fe01d9c3830b9.60748217.
Abstract (sommario):
An approach to the study of cellular inflammation using methods of cytochemical analysis of sputum in patients with bronchial asthma with different types of airway reactions to bronchoprovocation with cold air is presented. Endotyping of patients contributes to a better understanding of the pathophysiological mechanisms and the choice of treatment tactics for the disease.
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Salinas, M., D. Schmidt, R. Lange, M. Libera e S. Ramaswamy. "Computational Prediction of Fluid Induced Stress States in Dynamically Conditioned Engineered Heart Valve Tissues". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80787.
Abstract (sommario):
There is extensive documented evidence that mechanical conditioning plays a significant role in the development of tissue grown in-vitro for heart valve scaffolds [1–3]. Modern custom made bioreactors have been used to study the mechanobiology of engineered heart valve tissues [1]. Specifically fluid-induced shears stress patterns may play a critical role in up-regulating extracellular matrix secretion by progenitor cell sources such as bone marrow derived stem cells (BMSCs) [2] and increasing the possibility of cell differentiation towards a heart valve phenotype. We hypothesize that specific biomimetic fluid induced shear stress environments, particularly oscillatory shear stress (OSS), have significant effects on BMSCs phenotype and formation rates. As a first step here, we attempt to quantify and delineate the entire 3-D flow field by developing a CFD model to predict the fluid induced shear stress environments on engineered heart valves tissue under quasi-static steady flow and dynamic steady flow conditions.
Rapporti di organizzazioni sul tema "Secretion stress":
1
El Halawani, Mohamed, e Israel Rozenboim. Temperature Stress and Turkey Reproduction. United States Department of Agriculture, maggio 2002. http://dx.doi.org/10.32747/2002.7570546.bard.
Abstract (sommario):
High temperature stress is of major concern to turkey producers in Israel and the United States. The decline in the rate of egg production at high environmental temperature is well recognized, but the neuroendocrinological basis is not understood. Our objectives were: 1) to characterize the hypothalamo-hypophyseal axis involvement in the mechanism(s) underlying the detrimental effect of heat stress on reproduction, and 2) to establish procedures that alleviate the damaging effect of heat stress on reproduction. Heat stress (40oC, Israel; 32oC, U.S.) caused significant reduction in egg production, which was restored by VIP immunoneutralization. The decline in egg production did not appear to be entirely related to the expression of incubation behavior due to the rise in circulating PRL in stressed birds. Heat stress was found to increase circulating PRL in ovariectomized turkeys independent of the reproductive stage. Active immunization against VIP was shown for the first time to up-regulate LHb and FSHb subunit mRNA contents. These findings taken together with the results that the heat stress-induced decline in egg production may not be dependent upon the reproductive stage, lead to the suggestion that the detrimental effect of heat stress on reproductive performance may be in part mediated by VIP acting directly on the GnRH/gonadotropin system. Inhibin (INH) immunoneutralization has been shown to enhance FSH secretion and induces ovulation in mammals. It is hypothesized that immunization of heat-stressed turkeys against INH will increase levels of circulating FSH and the number of preovulating follicles which leads to improved reproductive performance. We have cloned and expressed turkey INH-a and INH-bA. Active immunization of turkey hens with rtINH-a increased pituitary FSH-b subunit mRNA and the number of non-graded preovulatory yellow follicles, but no significant increase in egg production was observed.
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Elbaum, Michael, e Peter J. Christie. Type IV Secretion System of Agrobacterium tumefaciens: Components and Structures. United States Department of Agriculture, marzo 2013. http://dx.doi.org/10.32747/2013.7699848.bard.
Abstract (sommario):
Objectives: The overall goal of the project was to build an ultrastructural model of the Agrobacterium tumefaciens type IV secretion system (T4SS) based on electron microscopy, genetics, and immunolocalization of its components. There were four original aims: Aim 1: Define the contributions of contact-dependent and -independent plant signals to formation of novel morphological changes at the A. tumefaciens polar membrane. Aim 2: Genetic basis for morphological changes at the A. tumefaciens polar membrane. Aim 3: Immuno-localization of VirB proteins Aim 4: Structural definition of the substrate translocation route. There were no major revisions to the aims, and the work focused on the above questions. Background: Agrobacterium presents a unique example of inter-kingdom gene transfer. The process involves cell to cell transfer of both protein and DNA substrates via a contact-dependent mechanism akin to bacterial conjugation. Transfer is mediated by a T4SS. Intensive study of the Agrobacterium T4SS has made it an archetypal model for the genetics and biochemistry. The channel is assembled from eleven protein components encoded on the B operon in the virulence region of the tumor-inducing plasmid, plus an additional coupling protein, VirD4. During the course of our project two structural studies were published presenting X-ray crystallography and three-dimensional reconstruction from electron microscopy of a core complex of the channel assembled in vitro from homologous proteins of E. coli, representing VirB7, VirB9, and VirB10. Another study was published claiming that the secretion channels in Agrobacterium appear on helical arrays around the membrane perimeter and along the entire length of the bacterium. Helical arrangements in bacterial membranes have since fallen from favor however, and that finding was partially retracted in a second publication. Overall, the localization of the T4SS within the bacterial membranes remains enigmatic in the literature, and we believe that our results from this project make a significant advance. Summary of achievements : We found that polar inflations and other membrane disturbances relate to the activation conditions rather than to virulence protein expression. Activation requires low pH and nutrient-poor medium. These stress conditions are also reflected in DNA condensation to varying degrees. Nonetheless, they must be considered in modeling the T4SS as they represent the relevant conditions for its expression and activity. We identified the T4SS core component VirB7 at native expression levels using state of the art super-resolution light microscopy. This marker of the secretion system was found almost exclusively at the cell poles, and typically one pole. Immuno-electron microscopy identified the protein at the inner membrane, rather than at bridges across the inner and outer membranes. This suggests a rare or transient assembly of the secretion-competent channel, or alternatively a two-step secretion involving an intermediate step in the periplasmic space. We followed the expression of the major secreted effector, VirE2. This is a single-stranded DNA binding protein that forms a capsid around the transferred oligonucleotide, adapting the bacterial conjugation to the eukaryotic host. We found that over-expressed VirE2 forms filamentous complexes in the bacterial cytoplasm that could be observed both by conventional fluorescence microscopy and by correlative electron cryo-tomography. Using a non-retentive mutant we observed secretion of VirE2 from bacterial poles. We labeled the secreted substrates in vivo in order detect their secretion and appearance in the plant cells. However the low transfer efficiency and significant background signal have so far hampered this approach.
3
Christopher, David A., e Avihai Danon. Plant Adaptation to Light Stress: Genetic Regulatory Mechanisms. United States Department of Agriculture, maggio 2004. http://dx.doi.org/10.32747/2004.7586534.bard.
Abstract (sommario):
Original Objectives: 1. Purify and biochemically characterize RB60 orthologs in higher plant chloroplasts; 2. Clone the gene(s) encoding plant RB60 orthologs and determine their structure and expression; 3. Manipulate the expression of RB60; 4. Assay the effects of altered RB60 expression on thylakoid biogenesis and photosynthetic function in plants exposed to different light conditions. In addition, we also examined the gene structure and expression of RB60 orthologs in the non-vascular plant, Physcomitrella patens and cloned the poly(A)-binding protein orthologue (43 kDa RB47-like protein). This protein is believed to a partner that interacts with RB60 to bind to the psbA5' UTR. Thus, to obtain a comprehensive view of RB60 function requires analysis of its biochemical partners such as RB43. Background & Achievements: High levels of sunlight reduce photosynthesis in plants by damaging the photo system II reaction center (PSII) subunits, such as D1 (encoded by the chloroplast tpsbAgene). When the rate of D1 synthesis is less than the rate of photo damage, photo inhibition occurs and plant growth is decreased. Plants use light-activated translation and enhanced psbAmRNA stability to maintain D1 synthesis and replace the photo damaged 01. Despite the importance to photosynthetic capacity, these mechanisms are poorly understood in plants. One intriguing model derived from the algal chloroplast system, Chlamydomonas, implicates the role of three proteins (RB60, RB47, RB38) that bind to the psbAmRNA 5' untranslated leader (5' UTR) in the light to activate translation or enhance mRNA stability. RB60 is the key enzyme, protein D1sulfide isomerase (Pill), that regulates the psbA-RN :Binding proteins (RB's) by way of light-mediated redox potentials generated by the photosystems. However, proteins with these functions have not been described from higher plants. We provided compelling evidence for the existence of RB60, RB47 and RB38 orthologs in the vascular plant, Arabidopsis. Using gel mobility shift, Rnase protection and UV-crosslinking assays, we have shown that a dithiol redox mechanism which resembles a Pill (RB60) activity regulates the interaction of 43- and 30-kDa proteins with a thermolabile stem-loop in the 5' UTR of the psbAmRNA from Arabidopsis. We discovered, in Arabidopsis, the PD1 gene family consists of II members that differ in polypeptide length from 361 to 566 amino acids, presence of signal peptides, KDEL motifs, and the number and positions of thioredoxin domains. PD1's catalyze the reversible formation an disomerization of disulfide bonds necessary for the proper folding, assembly, activity, and secretion of numerous enzymes and structural proteins. PD1's have also evolved novel cellular redox functions, as single enzymes and as subunits of protein complexes in organelles. We provide evidence that at least one Pill is localized to the chloroplast. We have used PDI-specific polyclonal and monoclonal antisera to characterize the PD1 (55 kDa) in the chloroplast that is unevenly distributed between the stroma and pellet (containing membranes, DNA, polysomes, starch), being three-fold more abundant in the pellet phase. PD1-55 levels increase with light intensity and it assembles into a high molecular weight complex of ~230 kDa as determined on native blue gels. In vitro translation of all 11 different Pill's followed by microsomal membrane processing reactions were used to differentiate among PD1's localized in the endoplasmic reticulum or other organelles. These results will provide.1e insights into redox regulatory mechanisms involved in adaptation of the photosynthetic apparatus to light stress. Elucidating the genetic mechanisms and factors regulating chloroplast photosynthetic genes is important for developing strategies to improve photosynthetic efficiency, crop productivity and adaptation to high light environments.
4
Sela, Shlomo, e Michael McClelland. Investigation of a new mechanism of desiccation-stress tolerance in Salmonella. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7598155.bard.
Abstract (sommario):
Low-moisture foods (LMF) are increasingly involved in foodborne illness. While bacteria cannot grow in LMF due to the low water content, pathogens such as Salmonella can still survive in dry foods and pose health risks to consumer. We recently found that Salmonella secretes a proteinaceous compound during desiccation, which we identified as OsmY, an osmotic stress response protein of 177 amino acids. To elucidate the role of OsmY in conferring tolerance against desiccation and other stresses in Salmonella entericaserovarTyphimurium (STm), our specific objectives were: (1) Characterize the involvement of OsmY in desiccation tolerance; (2) Perform structure-function analysis of OsmY; (3) Study OsmY expression under various growth- and environmental conditions of relevance to agriculture; (4) Examine the involvement of OsmY in response to other stresses of relevance to agriculture; and (5) Elucidate regulatory pathways involved in controlling osmY expression. We demonstrated that an osmY-mutant strain is impaired in both desiccation tolerance (DT) and in long-term persistence during cold storage (LTP). Genetic complementation and addition of a recombinantOsmY (rOsmY) restored the mutant survival back to that of the wild type (wt). To analyze the function of specific domains we have generated a recombinantOsmY (rOsmY) protein. A dose-response DT study showed that rOsmY has the highest protection at a concentration of 0.5 nM. This effect was protein- specific as a comparable amount of bovine serum albumin, an unrelated protein, had a three-time lower protection level. Further characterization of OsmY revealed that the protein has a surfactant activity and is involved in swarming motility. OsmY was shown to facilitate biofilm formation during dehydration but not during bacterial growth under optimal growth conditions. This finding suggests that expression and secretion of OsmY under stress conditions was potentially associated with facilitating biofilm production. OsmY contains two conserved BON domains. To better understand the role of the BON sites in OsmY-mediated dehydration tolerance, we have generated two additional rOsmY constructs, lacking either BON1 or BON2 sites. BON1-minus (but not BON2) protein has decreased dehydration tolerance compared to intact rOsmY, suggesting that BON1 is required for maximal OsmY-mediated activity. Addition of BON1-peptide at concentration below 0.4 µM did not affect STm survival. Interestingly, a toxic effect of BON1 peptide was observed in concentration as low as 0.4 µM. Higher concentrations resulted in complete abrogation of the rOsmY effect, supporting the notion that BON-mediated interaction is essential for rOsmY activity. We performed extensive analysis of RNA expression of STm undergoing desiccation after exponential and stationary growth, identifying all categories of genes that are differentially expressed during this process. We also performed massively in-parallel screening of all genes in which mutation caused changes in fitness during drying, identifying over 400 such genes, which are now undergoing confirmation. As expected OsmY is one of these genes. In conclusion, this is the first study to identify that OsmY protein secreted during dehydration contributes to desiccation tolerance in Salmonella by facilitating dehydration- mediated biofilm formation. Expression of OsmY also enhances swarming motility, apparently through its surfactant activity. The BON1 domain is required for full OsmY activity, demonstrating a potential intervention to reduce pathogen survival in food processing. Expression and fitness screens have begun to elucidate the processes of desiccation, with the potential to uncover additional specific targets for efforts to mitigate pathogen survival in desiccation.
5
Wolfenson, David, William W. Thatcher e James E. Kinder. Regulation of LH Secretion in the Periovulatory Period as a Strategy to Enhance Ovarian Function and Fertility in Dairy and Beef Cows. United States Department of Agriculture, dicembre 2003. http://dx.doi.org/10.32747/2003.7586458.bard.
Abstract (sommario):
The general research objective was to increase herd pregnancy rates by enhancing corpus luteum (CL) function and optimizing follicle development, in order to increase conception rate and embryo survival. The specific objectives were: to determine the effect of the duration of the preovulatory LH surge on CL function; to determine the function of LH during the postovulatory period on CL development; to optimize CL differentiation and follicle development by means of a biodegradable GnRH implant; to test whether optimization of CL development and follicle dynamics in timed- insemination protocols would improve fertility in high-yielding dairy cows. Low fertility in cattle results in losses of hundreds of millions of dollars in the USA and Israel. Two major causes of low fertility are formation of a functionally impaired CL, and subsequent enhanced ovarian follicle development. A functionally impaired CL may result from suboptimal LH secretion. The two major causes of low fertility in dairy cattle in US and Israel are negative energy status and summer heat stress; in both situations, low fertility is associated with reductions in LH secretion and impaired development of the ovulatory follicle and of the CL. In Florida, the use of 450-mg deslorelin (GnRH analogue) implants to induce ovulation, under the Ovsynch protocol resulted in a higher pregnancy rates than use of 750-mg implants, and pregnancy losses tended to decrease compared to controls, due probably to decrease in follicular development and estradiol secretion at the time of conceptus signaling to maintain the CL. An alternative strategy to enhance progesterone concentrations involved induction of an accessory CL by injection of hCG on day 5 after the cows were inseminated. Treatment with hCG resulted in 86% of the cows having two CLs, compared with 23% of the control cows. Conception rates were higher among the hCG-treated cows than among the controls. Another approach was to replace the second injection of GnRH analogue, in a timed-insemination protocol, with estradiol cypionate (ECP) injected 24 h after the injection of PGF₂ₐ Pregnancy rates were comparable with those obtained under the regular Ovsynch (timed- AI) program. Use of ECP induced estrus, and cows inseminated at detected estrus are indeed more fertile than those not in estrus at the time of insemination. Collectively, the BARD-supported programs at the University of Florida have improved timed insemination programs. In Ohio, the importance of the frequency of LH episodes during the early stages of the estrous cycle of cattle, when the corpus luteum is developing, was studied in an in vivo experiment in which cows were subjected to various episodic exposures to exogenous bovine LH. Results indicate that the frequent LH episodes immediately following the time of ovulation are important in development of the corpus luteum, from the points of view of both size and functionality. In another study, rates of cell proliferation and numbers of endothelial cells were examined in vitro in CLs collected from cows that received post-ovulation pulsatile LH treatment at various frequencies. The results indicate that the corpora lutea growth that results from luteal cell proliferation is enhanced by the episodes of LH release that occur immediately after the time of ovulation in cattle. The results also show that luteal endothelial cell numbers did not differ among cows treated with different LH doses. In Israel. a longer duration of the preovulatory LH surge stimulated the steroidogenic capacity of granulosa-derived luteal cells, and might, thereby, contribute to a higher progesterone output from the bovine corpus luteum. In an in vivo study, a subgroup of high-yielding dairy cows with extended estrus to ovulation interval was identified. Associated with this extended interval were: low plasma progesterone and estradiol concentrations and a low preovulatory LH surge prior to ovulation, as well as low post- ovulation progesterone concentration. In experiments based on the above results, we found that injection of GnRH at the onset of estrus increased the LHpeak, prevented late ovulation, decreased the variability between cows and elicited high and uniform progesterone levels after ovulation. GnRH at estrus onset increased conception rates, especially in the summer, and among primiparous cows and those with low body condition. Another study compared ovarian functions in multiparous lactating cows with those in nulliparous non-lactating heifers. The results revealed differences in ovarian follicular dynamics, and in plasma concentrations of steroids and gonadotropins that may account for the differences in fertility between heifers and cows.
6
Dahl, Geoffrey E., Sameer Mabjeesh, Thomas B. McFadden e Avi Shamay. Environmental manipulation during the dry period of ruminants: strategies to enhance subsequent lactation. United States Department of Agriculture, febbraio 2006. http://dx.doi.org/10.32747/2006.7586544.bard.
Abstract (sommario):
The project resulted from earlier observations that environmental factors, especially photoperiod and temperature, had profound effects on milk yield in dairy cattle during lactation. More recently we had determined that photoperiod manipulation during the dry period altered milk yield in the next lactation, and this was associated with shifts in circulating concentrations of prolactin; specifically exposure to short days during the dry period decreases prolactin but increases milk yield. Because prolactin is also affected by temperature, with heat stress causing an increase in prolactin similar to that of long day exposure, we focused our efforts on determining prolactin signaling provides a common pathway for generation of environmental effects on mammary growth, development and subsequent function during the dry period of dairy ruminants. Over the project period we made significant progress toward testing our hypotheses that (I): In cows, there is a discrete duration of time during the dry period in which exposure to short days will result in optimal enhancement of mammary development and milk yield in the following lactation, and that this effect is mediated through demonstrable changes in mammary gland development, prolactin signaling, and mammary gene expression; and (II): Modulation of photoperiod and temperature during the dry period will affect milk yield in goats in the subsequent lactation via shifts in nutrient and endocrine partitioning, and mammary gene expression, during the dry period and into lactation. Cows exposed to short days for only the final 21 days of the dry period did not produce more milk that those on long day or natural photoperiod when dry. However, cows on short days for the entire 60 days dry did produce more milk than the other 3 groups. This indicates that there is a duration effect of short day exposure on subsequent milk yield. Results of the second study in cows indicate that mammary growth increases differentially during the dry period under long vs. short days, and that short days drive more extensive growth which is associated with altered prolactin signaling via decreases in an suppressors of cytokine signaling that represent an inhibitory pathway to mammary growth. Evidence from the studies in Israel confirms that goats respond to short days during the dry period in a similar manner to cows. In addition, heat stress effects on during the dry period can be limited by exposure to short days. Here again, shifts in prolactin signaling, along with changes in IGF-I secretion, are associated with the observed changes in mammary function in goats. These results have a number of biological and practical implications. For dairy producers, it is clear that we can recommend that cows and goats should be on reduced light exposure during the dry period, and further, cows and goats should be cooled to avoid heat stress during that time. Environmental influences on mammary growth are apparent during the dry period, and those effects have persistent impact in the subsequent lactation. Prolactin signaling is a consistent mechanism whereby extended light exposure and heat stress may depress mammary growth and development during the dry period. Thus, the prolactin signaling system offers an opportunity for further manipulation to improve production efficiency in dairy ruminants.
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Elmann, Anat, Orly Lazarov, Joel Kashman e Rivka Ofir. therapeutic potential of a desert plant and its active compounds for Alzheimer's Disease. United States Department of Agriculture, marzo 2015. http://dx.doi.org/10.32747/2015.7597913.bard.
Abstract (sommario):
We chose to focus our investigations on the effect of the active forms, TTF and AcA, rather than the whole (crude) extract. 1. To establish cultivation program designed to develop lead cultivar/s (which will be selected from the different Af accessions) with the highest yield of the active compounds TTF and/or achillolide A (AcA). These cultivar/s will be the source for the purification of large amounts of the active compounds when needed in the future for functional foods/drug development. This task was completed. 2. To determine the effect of the Af extract, TTF and AcA on neuronal vulnerability to oxidative stress in cultured neurons expressing FAD-linked mutants.Compounds were tested in N2a neuroblastoma cell line. In addition, we have tested the effects of TTF and AcA on signaling events promoted by H₂O₂ in astrocytes and by β-amyloid in neuronal N2a cells. 3. To determine the effect of the Af extract, TTF and AcA on neuropathology (amyloidosis and tau phosphorylation) in cultured neurons expressing FAD-linked mutants. 4. To determine the effect of A¦ extract, AcA and TTF on FAD-linked neuropathology (amyloidosis, tau phosphorylation and inflammation) in transgenic mice. 5. To examine whether A¦ extract, TTF and AcA can reverse behavioral deficits in APPswe/PS1DE9 mice, and affect learning and memory and cognitive performance in these FAD-linked transgenic mice. Background to the topic.Neuroinflammation, oxidative stress, glutamate toxicity and amyloid beta (Ab) toxicity are involved in the pathogenesis of Alzheimer's diseases. We have previously purified from Achilleafragrantissimatwo active compounds: a protective flavonoid named 3,5,4’-trihydroxy-6,7,3’-trimethoxyflavone (TTF, Fl-72/2) and an anti-inflammatory sesquiterpenelactone named achillolide A (AcA). Major conclusions, solutions, achievements. In this study we could show that TTF and AcA protected cultured astrocytes from H₂O₂ –induced cell death via interference with cell signaling events. TTF inhibited SAPK/JNK, ERK1/2, MEK1 and CREBphosphorylation, while AcA inhibited only ERK1/2 and MEK1 phosphorylation. In addition to its protective activities, TTF had also anti-inflammatory activities, and inhibited the LPS-elicited secretion of the proinflammatorycytokinesInterleukin 6 (IL-6) and IL-1b from cultured microglial cells. Moreover, TTF and AcA protected neuronal cells from glutamate and Abcytotoxicity by reducing the glutamate and amyloid beta induced levels of intracellular reactive oxygen species (ROS) and via interference with cell signaling events induced by Ab. These compounds also reduced amyloid precursor protein net processing in vitro and in vivo in a mouse model for Alzheimer’s disease and improvedperformance in the novel object recognition learning and memory task. Conclusion: TTF and AcA are potential candidates to be developed as drugs or food additives to prevent, postpone or ameliorate Alzheimer’s disease. Implications, both scientific and agricultural.The synthesis ofAcA and TTF is very complicated. Thus, the plant itself will be the source for the isolation of these compounds or their precursors for synthesis. Therefore, Achilleafragrantissima could be developed into a new crop with industrial potential for the Arava-Negev area in Israel, and will generate more working places in this region.
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Lichter, Amnon, Gopi K. Podila e Maria R. Davis. Identification of Genetic Determinants that Facilitate Development of B. cinerea at Low Temperature and its Postharvest Pathogenicity. United States Department of Agriculture, marzo 2011. http://dx.doi.org/10.32747/2011.7592641.bard.
Abstract (sommario):
Botrytis cinerea is the postharvest pathogen of many agricultural produce with table grapes, strawberries and tomatoes as major targets. The high efficiency with which B. cinerea causes disease on these produce during storage is attributed in part due to its exceptional ability to develop at very low temperature. Our major goal was to understand the genetic determinants which enable it to develop at low temperature. The specific research objectives were: 1. Identify expression pattern of genes in a coldenriched cDNA library. 2. Identify B. cinerea orthologs of cold-induced genes 3. Profile protein expression and secretion at low temperature on strawberry and grape supplemented media. 4. Test novel methods for the functional analysis of coldresponsive genes. Objective 1 was modified during the research because a microarray platform became available and it allowed us to probe the whole set of candidate genes according to the sequence of 2 strains of the fungus, BO5.10 and T4. The results of this experiment allowed us to validate some of our earlier observations which referred to genes which were the product of a SSH suppression-subtraction library. Before the microarray became available during 2008 we also analyzed the expression of 15 orthologs of cold-induced genes and some of these results were also validated by the microarray experiment. One of our goals was also to perform functional analysis of cold-induced genes. This goal was hampered for 3 years because current methodology for transformation with ‘protoplasts’ failed to deliver knockouts of bacteriordopsin-like (bR) gene which was our primary target for functional analysis. Consequently, we developed 2 alternative transformation platforms, one which involves an air-gun based technique and another which involves DNA injection into sclerotia. Both techniques show great promise and have been validated using different constructs. This contribution is likely to serve the scientific community in the near future. Using these technologies we generated gene knockout constructs of 2 genes and have tested there effect on survival of the fungus at low temperature. With reference to the bR genes our results show that it has a significant effect on mycelial growth of the B. cinerea and the mutants have retarded development at extreme conditions of ionic stress, osmotic stress and low temperature. Another gene of unknown function, HP1 is still under analysis. An ortholog of the yeast cold-induced gene, CCH1 which encodes a calcium tunnel and was shown to be cold-induced in B. cinerea was recently cloned and used to complement yeast mutants and rescue them from cold-sensitivity. One of the significant findings of the microarray study involves a T2 ribonuclease which was validated to be cold-induced by qPCR analysis. This and other genes will serve for future studies. In the frame of the study we also screened a population of 631 natural B. cinerea isolates for development at low temperature and have identified several strains with much higher and lower capacity to develop at low temperature. These strains are likely to be used in the future as candidates for further functional analysis. The major conclusions from the above research point to specific targets of cold-induced genes which are likely to play a role in cold tolerance. One of the most significant observations from the microarray study is that low temperature does not induce ‘general stress response in B. cinerea, which is in agreement to its exceptional capacity to develop at low temperature. Due to the tragic murder of the Co-PI Maria R. Davis and GopiPodila on Feb. 2010 it is impossible to deliver their contribution to the research. The information of the PI is that they failed to deliver objective 4 and none of the information which relates to objective 3 has been delivered to the PI before the murder or in a visit to U. Alabama during June, 2010. Therefore, this report is based solely on the IS data.
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Ron, Eliora, e Eugene Eugene Nester. Global functional genomics of plant cell transformation by agrobacterium. United States Department of Agriculture, marzo 2009. http://dx.doi.org/10.32747/2009.7695860.bard.
Abstract (sommario):
The aim of this study was to carry out a global functional genomics analysis of plant cell transformation by Agrobacterium in order to define and characterize the physiology of Agrobacterium in the acidic environment of a wounded plant. We planed to study the proteome and transcriptome of Agrobacterium in response to a change in pH, from 7.2 to 5.5 and identify genes and circuits directly involved in this change. Bacteria-plant interactions involve a large number of global regulatory systems, which are essential for protection against new stressful conditions. The interaction of bacteria with their hosts has been previously studied by genetic-physiological methods. We wanted to make use of the new capabilities to study these interactions on a global scale, using transcription analysis (transcriptomics, microarrays) and proteomics (2D gel electrophoresis and mass spectrometry). The results provided extensive data on the functional genomics under conditions that partially mimic plant infection and – in addition - revealed some surprising and significant data. Thus, we identified the genes whose expression is modulated when Agrobacterium is grown under the acidic conditions found in the rhizosphere (pH 5.5), an essential environmental factor in Agrobacterium – plant interactions essential for induction of the virulence program by plant signal molecules. Among the 45 genes whose expression was significantly elevated, of special interest is the two-component chromosomally encoded system, ChvG/I which is involved in regulating acid inducible genes. A second exciting system under acid and ChvG/Icontrol is a secretion system for proteins, T6SS, encoded by 14 genes which appears to be important for Rhizobium leguminosarum nodule formation and nitrogen fixation and for virulence of Agrobacterium. The proteome analysis revealed that gamma aminobutyric acid (GABA), a metabolite secreted by wounded plants, induces the synthesis of an Agrobacterium lactonase which degrades the quorum sensing signal, N-acyl homoserine lactone (AHL), resulting in attenuation of virulence. In addition, through a transcriptomic analysis of Agrobacterium growing at the pH of the rhizosphere (pH=5.5), we demonstrated that salicylic acid (SA) a well-studied plant signal molecule important in plant defense, attenuates Agrobacterium virulence in two distinct ways - by down regulating the synthesis of the virulence (vir) genes required for the processing and transfer of the T-DNA and by inducing the same lactonase, which in turn degrades the AHL. Thus, GABA and SA with different molecular structures, induce the expression of these same genes. The identification of genes whose expression is modulated by conditions that mimic plant infection, as well as the identification of regulatory molecules that help control the early stages of infection, advance our understanding of this complex bacterial-plant interaction and has immediate potential applications to modify it. We expect that the data generated by our research will be used to develop novel strategies for the control of crown gall disease. Moreover, these results will also provide the basis for future biotechnological approaches that will use genetic manipulations to improve bacterial-plant interactions, leading to more efficient DNA transfer to recalcitrant plants and robust symbiosis. These advances will, in turn, contribute to plant protection by introducing genes for resistance against other bacteria, pests and environmental stress.