Journal of Experimental Zoology最新文献_第6页

Plasticity and constraints in development and evolution. 发展和演变中的可塑性和约束。

Journal of Experimental Zoology Pub Date : 2000-04-15

J Hodin

引用次数: 0

Fundamental cryobiology of rat immature and mature oocytes: hydraulic conductivity in the presence of Me(2)SO, Me(2)SO permeability, and their activation energies. 大鼠未成熟和成熟卵母细胞的基本低温生物学:Me(2)SO存在下的水力传导性、Me(2)SO渗透率及其活化能。

Journal of Experimental Zoology Pub Date : 2000-04-01

Y Agca, J Liu, E S Critser, J K Critser

{"title":"Fundamental cryobiology of rat immature and mature oocytes: hydraulic conductivity in the presence of Me(2)SO, Me(2)SO permeability, and their activation energies.","authors":"Y Agca, J Liu, E S Critser, J K Critser","doi":"","DOIUrl":"","url":null,"abstract":"The hydraulic conductivity in the presence of dimethyl sulfoxide Me(2)SO (L(p)(Me(2)SO)), Me(2)SO (P(Me(2)SO)) permeability and reflection coefficient (sigma) of immature (germinal vesicle; GV) and mature (metaphase II; MII) rat oocytes were determined at various temperatures. A temperature controlled micropipette perfusion technique was used to conduct experiments at five different temperatures (30, 20, 10, 4, and -3 degrees C). Kedem and Katchalsky membrane transport theory was used to describe the cell volume kinetics. The cell volumetric changes of oocytes were calculated from the measurement of two oocyte diameters, assuming a spherical shape. The activation energies (E(a)) of L(p)(Me(2)SO) and P(Me(2)SO) were calculated using the Arrhenius equation. Activation energies of L(p)(Me(2)SO) for GV and MII oocytes were 34.30 Kcal/mol and 16.29 Kcal/mol, respectively; while the corresponding E(a)s of P(Me(2)SO) were 19.87 Kcal/mol and 21.85 Kcal/mol, respectively. These permeability parameters were then used to calculate cell water loss in rat oocytes during cooling at subzero temperatures. Based on these values, the predicted optimal cooling rate required to maintain extra- and intracellular water in near equilibrium for rat GV stage oocytes was found to be between 0.05 degrees C/min and 0. 025; while for rat MII oocytes, the corresponding cooling rate was 1 degrees C/min. These data suggest that standard cooling rates used for mouse oocytes (e.g., 0.5-1 degrees C/min) can also be employed to cryopreserve rat MII oocytes. However, the corresponding cooling rate required to avoid damage must be significantly slower for the GV stage rat oocyte. J. Exp. Zool. 286:523-533, 2000.","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 5","pages":"523-33"},"PeriodicalIF":0.0,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21537928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of temperature on the deformity and sex differentiation of tilapia, Oreochromis mossambicus. 温度对罗非鱼畸形和性别分化的影响。

Journal of Experimental Zoology Pub Date : 2000-04-01

L H Wang, C L Tsai

引用次数: 0

Lack of physiological plasticity in the early chicken embryo exposed to acute hypoxia. 暴露于急性缺氧的早期鸡胚缺乏生理可塑性。

Journal of Experimental Zoology Pub Date : 2000-04-01

J Altimiras, L Phu

{"title":"Lack of physiological plasticity in the early chicken embryo exposed to acute hypoxia.","authors":"J Altimiras, L Phu","doi":"","DOIUrl":"","url":null,"abstract":"By exposing chicken embryos to hypoxia (10%) acutely (2, 4, and 6 hr) during early development (2, 3, and 4 days) we tested the hypothesis that hypoxia has an impact on embryonic growth and impairs cardiac development at the time cardiac morphogenesis is taking place. After the hypoxic perturbation, the embryos were allowed to develop until day 9, when embryo mass, heart mass, and rate of oxygen consumption were recorded. Four-day-old embryos exposed to 6 hr of hypoxia showed an increased mortality (38.9% versus 18% for controls), indicating the immediate effect of hypoxia on survivability. While only 8% of the controls displayed morphological abnormalities, 3- and 4-day-old embryos exposed for 6 hr showed more frequent developmental abnormalities (25% and 30% respectively). No significant differences in embryo or heart mass were found except in 4-day-old embryos exposed for 2 hr. Mass-specific oxygen consumption was not different between controls and embryos exposed to hypoxia at 2 or 3 days of development, but it was increased in 4-day-old embryos exposed for 4 hr (P < 0.05). These results suggest that an acute hypoxic episode does not have an impact when occurring very early in development (days 2 or 3). However, when the hypoxic episode occurs on day 4, survivability is largely decreased. Considering the lack of permanent effects on the surviving embryos, we suggest that the early embryo resorts to a simple strategy of death or survival, and the individual capacity for survival must be based on interindividual differences rather than the existence of compensatory mechanisms. J. Exp. Zool. 286:450-456, 2000.","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 5","pages":"450-6"},"PeriodicalIF":0.0,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21537432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Corticotropin-releasing factor accelerates metamorphosis in Bufo arenarum: effect on pituitary ACTH and TSH cells. 促肾上腺皮质激素释放因子加速大鲵变态:对垂体ACTH和TSH细胞的影响。

Journal of Experimental Zoology Pub Date : 2000-04-01

L A Miranda, J M Affanni, D A Paz

{"title":"Corticotropin-releasing factor accelerates metamorphosis in Bufo arenarum: effect on pituitary ACTH and TSH cells.","authors":"L A Miranda, J M Affanni, D A Paz","doi":"","DOIUrl":"","url":null,"abstract":"The actions of several neuropeptides as hypothalamic mediators in the regulation of Bufo arenarum metamorphosis were investigated. Prometamorphic larvae were injected with 1.5 microg thyrotropin-releasing hormone (TRH), 2 microg ovine corticotropin-releasing factor (oCRF), 2 microg mammalian gonadotropin-releasing hormone (mGnRH), 2 microg human growth hormone-releasing hormone (hGHRH), or Holtfreter solution (control group). Larvae received two injections with the same dose: one at the beginning of the experiment and the other 7 days later. Several morphologic parameters (total length, tail length, wet weight, hind limb length, and metamorphic stages) were measured as indicators of growth and metamorphic development. These measurements were taken in 20 larvae per treatment or control group at the beginning of the experiment, at day 7 and at day 14 when the experiment ended. We observed that only the administration of exogenous CRF stimulated resorption of the tail and accelerated the rate of metamorphosis. In the pituitary of CRF-treated larvae we observed that thyrotropin (TSH) and adrenocorticotropic hormone (ACTH) producing cells showed a weaker immunoreactivity, a decrease in cell number and a reduction of volume density when compared with normal larvae. In conclusion, the results obtained indicate a possible role for CRF in Bufo arenarum metamorphosis. CRF may regulate interrenal and thyroid activity by acting directly upon TSH and ACTH cells. On the other hand, TRH, GnRH and GHRH were inactive in stimulating growth or metamorphosis of Bufo arenarum. J. Exp. Zool. 286:473-480, 2000.","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 5","pages":"473-80"},"PeriodicalIF":0.0,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21537434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Visual and nutritional food cues fine-tune timing of reproduction in a neotropical rainforest bird. 新热带雨林鸟类的视觉和营养食物提示微调繁殖时间。

Journal of Experimental Zoology Pub Date : 2000-04-01

M Hau, M Wikelski, J C Wingfield

{"title":"Visual and nutritional food cues fine-tune timing of reproduction in a neotropical rainforest bird.","authors":"M Hau, M Wikelski, J C Wingfield","doi":"","DOIUrl":"","url":null,"abstract":"Food may act as a proximate factor in the regulation of avian seasonal breeding. Food cues could provide particularly important seasonal information to birds living in variable tropical environments, but this has not yet been tested. Spotted antbirds (Hylophylax n. naevioides) inhabiting a humid forest in central Panama (9 degrees N) likely use changes in the tropical photoperiod to time reproduction on a long-term, seasonal basis. We predicted that these insectivorous birds also adjust reproduction to short-term cues such as food availability because the onset of the rainy season and the resulting increase in insect abundance varies considerably between years. To test this prediction, prior to their breeding season (when they had half-maximal gonads), we either exposed captive male spotted antbirds to an ad libitum standard diet only or added live crickets to this diet. Males that received live crickets significantly increased gonad sizes within 3 weeks over controls on the standard diet. Moreover, in six additional experiments cricket availability always increased song rate, usually within a few days. The stimulatory effect of live crickets on song activity may function independent of nutritional aspects: Freshly killed crickets, providing similar nutritional content as live crickets, did not stimulate the birds' song activity. However, song activity increased to intermediate levels when live crickets were shown under a clear plastic wrap, i.e., when birds could see but not eat crickets. We hypothesize that the opportunity to see and handle live insects stimulates song and reproductive activity in these birds. Our data indicate for the first time that a tropical rainforest bird can use food cues to evaluate the suitability of local environmental conditions for breeding. J. Exp. Zool. 286:494-504, 2000.","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 5","pages":"494-504"},"PeriodicalIF":0.0,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21537437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Regulation of opioid peptides on the release of arginine vasotocin in the hen. 阿片肽对母鸡精氨酸缩宫素释放的调控作用。

Journal of Experimental Zoology Pub Date : 2000-04-01

T Sasaki, K Shimada, N Saito

引用次数: 0

Triggering of cryoprotectant synthesis in the woolly bear caterpillar (Pyrrharctia isabella Lepidoptera: Arctiidae). 棉熊毛虫(Pyrrharctia isabella鳞翅目:绵蛾科)低温保护剂合成的触发。

Journal of Experimental Zoology Pub Date : 2000-03-01

J R Layne, D K Kuharsky

{"title":"Triggering of cryoprotectant synthesis in the woolly bear caterpillar (Pyrrharctia isabella Lepidoptera: Arctiidae).","authors":"J R Layne, D K Kuharsky","doi":"","DOIUrl":"","url":null,"abstract":"Isabella tiger moths (Pyrrharctia isabella) overwinter as caterpillars (i.e., woolly bears) that can survive freezing at moderate subzero temperatures. We observed an increase in hemolymph osmolality for field-collected woolly bears during October (325 +/- 47 to 445 +/- 27 mOsmol/liter) and tested the influence of temperature and moisture levels on cryoprotectant production. Laboratory acclimation was done at 5 degrees C in moist conditions and at 25 degrees C acclimation in both dry and moist conditions. Body water contents were diminished by dehydration at 25 degrees C for 4 days (57 +/- 4%). Caterpillars collected in early October did not alter their hemolymph osmolality during cold acclimation, but caterpillars increased by 45% (to 647 +/- 90 mOsmol/liter) after 4 days at 5 degrees C following their collection in late October. Hemolymph composition was markedly changed in caterpillars experiencing dehydration at 25 degrees C (1042 +/- 200 mOsmol/liter; 507 +/- 225 mmol glycerol/liter), whereas caterpillars showed no change in their hemolymph composition when kept moist at 25 degrees C. Our experiments reveal that both dehydration and cold acclimation rapidly induce cryoprotectant synthesis in P. isabella caterpillars. J. Exp. Zool. 286:367-371, 2000.","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 4","pages":"367-71"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21537620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Contrasting stress response of male arctic ground squirrels and red squirrels. 雄性北极地松鼠和红松鼠应激反应的对比。

Journal of Experimental Zoology Pub Date : 2000-03-01

R Boonstra, C J McColl

{"title":"Contrasting stress response of male arctic ground squirrels and red squirrels.","authors":"R Boonstra, C J McColl","doi":"","DOIUrl":"","url":null,"abstract":"A hormonal-challenge protocol was used to compare the stress response of males of Arctic ground squirrels and red squirrels during the breeding season (May). These squirrels live in the same boreal forest of the Yukon, but have very different life histories and utilize the forest in markedly different ways. Red squirrels had levels of total cortisol, maximum corticosteroid-binding capacity, and free cortisol that were 5, 7, and 2 times, respectively, those of Arctic ground squirrels. Red squirrels were resistant to suppression by an artificial glucocorticoid, dexamethasone (DEX); Arctic ground squirrels were not. Cortisol levels in red squirrels responded slowly but continuously to the ACTH injection; Arctic ground squirrels responded rapidly and then stabilized. Testosterone levels in red squirrels were extremely sensitive to the challenge, being suppressed by both DEX and ACTH; levels in Arctic ground squirrels were resistant to the challenge, being modestly suppressed by DEX and stimulated by ACTH. Energy mobilization, as measured by glucose and free fatty acid responses, was not affected. Red squirrels had four times the levels of white blood cells and higher proportions of lymphocytes and lower proportions of eosinophils than Arctic ground squirrels, indicating that the latter were in worse condition immunologically. Our evidence suggests that the functions associated with the hypothalamic-pituitary-adrenal axis are compromised in breeding male Arctic ground squirrels, but not in red squirrels. We propose that in male red squirrels this axis has evolved in the context of a stable social system based on long-lived animals with individual territories which are needed to deal with unpredictable winter food supplies. In contrast, Arctic ground squirrels escape the rigors of winter by hibernation and this hormonal axis has evolved in short-lived males in the context of intense intra-sexual competition in a social system based on female kin groups and regular male dispersal to avoid inbreeding. J. Exp. Zool. 286:390-404, 2000.","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 4","pages":"390-404"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21538104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Novel aspects of the activities and subcellular distribution of enzymes of ketone body metabolism in the liver and kidney of the goldfish, Carassius auratus. 鲫鱼肝脏和肾脏酮体代谢酶活性和亚细胞分布的新方面。

Journal of Experimental Zoology Pub Date : 2000-03-01

P J Leblanc, J S Ballantyne

{"title":"Novel aspects of the activities and subcellular distribution of enzymes of ketone body metabolism in the liver and kidney of the goldfish, Carassius auratus.","authors":"P J Leblanc, J S Ballantyne","doi":"","DOIUrl":"","url":null,"abstract":"The metabolic organization of ketone body metabolism of liver and kidney of the goldfish Carassius auratus was assessed by measuring maximal activities, subcellular distribution, and stereoisomer preference of ketone body enzymes. These determinations indicate that the organization of ketone body metabolism in liver and kidney of goldfish differs from that of mammals in some respects. All the enzymes of ketone body metabolism were present in liver and kidney of goldfish, with the exception of hydroxymethylglutaryl-CoA (HMG-CoA) synthetase, which was not detected in liver. Two forms of beta-hydroxybutyrate dehydrogenase (betaHBDH) with different stereospecificity for beta-hydroxybutyrate (D- and L-beta-hydroxybutyrate) were detectable in liver and kidney. All of the ketone body enzymes measured in liver were mainly in the mitochondrial fraction, with the exception of D- and L-betaHBDH, which were cytosolic. In kidney, HMG-CoA synthase, together with HMG-CoA lyase and acetoacetyl CoA thiolase (AcoAT), were found mainly in the mitochondrial fraction. L-betaHBDH was mainly cytosolic in kidney, but by contrast with liver, D-betaHBDH was mainly found in the mitochondria, and SKT was distributed in both the mitochondrial and cytosolic compartments. J. Exp. Zool. 286:434-439, 2000.","PeriodicalId":15686,"journal":{"name":"Journal of Experimental Zoology","volume":"286 4","pages":"434-9"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21538108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0