We studied the hibernation behavior of the water frog Rana lessonae and its hybridogenetic associate R. esculenta in their natural habitat during three successive winters. Animals caught in pitfall traps at a fenced pond were individually
marked with PIT tags and some (n=36) were additionally equipped with radio transmitters. Of the animals caught, 85% left the fenced pond for hibernation.
More R. esculenta remained inside the fenced area compared to R. lessonae. R. lessonae emigrated earlier in autumn and came back later in spring than R. esculenta, but the distance to their hibernation sites did not differ. Both species left the fenced pond earlier in the year when ambient
temperatures were lower. All radio-tracked animals hibernated in woodland, 3–7 cm below the surface in soil, under moss, fallen
leaves or small branches. Soil temperatures at the actual hibernation sites were significantly higher than at randomly chosen
control sites. A surprising finding was that most frogs changed their hibernation sites during winter, and often more than
once. Movements were more frequent in the warmer first half of the winter than in the cooler second half, but some animals
were active even on days with mean temperatures below 1°C. These results show that both species do not spend the whole winter
torpid in one particular hibernation site but move around, especially at higher temperatures. Most of the animals lost weight
during the winter, and the weight loss was greater in females than in males and higher in warm than in cold winters. To what
extent weight loss and survival is influenced by the chosen hibernation sites and the amount of movement during winter, and
whether this contributes to the differences in species and sex ratios found in mixed populations, needs more investigation.
Received: 4 August 1999 / Accepted: 15 November 1999 相似文献
(1) The analysis of catecholamines revealed alterations in norepinephrine levels in the blood serum and the central nervous system of the Egyptian cobra during the different phases of the hibernation cycle. This may reflect an increased central demand for norepinephrine as a mediator for adaptive changes to cold.
(2) The low and variable concentration of dopamine suggests retarded synthesis during all the phases studied.
(3) Serotonin may be depleted or associated with increased activity of serotonergic neurons during cold acclimation. This increases the rate of turnover of serotonin to 5-hydroxy indole acetic acid.
(4) Cricannual measurements of cortisol and adrenocorticotrophic hormones revealed marked suppression that would clarify the direct effect of hibernation on higher centers. The decreased levels during prehibernation and hibernation were restored in normothermic animals when the pituitary–adrenal axis resumed its activity.
(5) The decline in thyroid hormone concentrations has its behavioural and physiological responses that lead to seasonal adjustments in the hibernating cobras.
The predation pressure of the greater horseshoe bat, Rhinolophus ferrumequinum, on the diapausing population of the noctuid moth, Goniocraspidum preyeri, was examined at an abandoned mine in central Japan. These bats did not prey on the moths in summer. The number of moths preyed on was largest in March. More than 60% of the diapausing moths were eaten by only three or four bats, which accounted for over 90% of all the moth deaths. This moth was an important source of food at the end of the hibernating period when the bat had already used most of its stored subcutaneous fat. The predation on G. preyeri may have raised the overwintering success rate of R. ferrumequinum. 相似文献
The initiation of innate immunology system could play an important role in the aspect of protection for sperms long‐term storage when the sperms got into oviduct of turtles and come into contact with epithelium. The exploration of TLR2/4 distribution and expression in oviduct during hibernation could help make the storage mechanism understandable. The objective of this study was to examine the gene and protein expression profiles in Chinese soft‐shelled turtle during hibernation from November to April in the next year. The protein distribution of TLR2/4 was investigated in the magnum, isthmus, uterus, and vagina of the turtle oviduct using immunohistochemistry, and the gene expression of TLR2/4 was analyzed using quantitative real‐time PCR (qRT‐PCR). The results showed positive TLR2 protein expression primarily in the epithelium of the oviduct. TLR4 immunoreactivity was widely observed in almost every part of the oviduct, particularly in the epithelium and secretory gland membrane. Analysis of protein, mRNA expression revealed the decreased expression of TLR2/4 in the magnum compared with the isthmus, uterus, and vagina during hibernation. The protein and mRNA expression of TLR2 in the magnum, isthmus, uterus, and vagina was decreased in April compared with that in November. TLR4 protein and mRNA expression in the magnum, isthmus, uterus and vagina was decreased in November compared with that in April. These results indicated that TLR2/4 expression might protect the sperm from microbial infections. In contrast to the function of TLR2, which protects sperm during the early stages of hibernation, TLR4 might play a role in later stages of storage. The present study is the first to report the functions of TLR2/4 in reptiles. 相似文献
AIM: To investigate the influence of ischemia/reperfusion on arctic ground squirrel(AGS) neuronal progenitor cells(NPCs), we subjected these cultured cells to oxygen and glucose deprivation.METHODS: AGS NPCs were expanded and differentiated into NPCs and as an ischemia vulnerable control, commercially available human NPCs(hNPCs) were seeded from thawed NPCs. NPCs, identified by expression of TUJ1 were seen at 14-21 d in vitro(DIV). Cultures were exposed to control conditions, hypoxia, oxygen and glucose deprivation or glucose deprivation alone or following return to normal conditions to model reperfusion. Cell viability and death were assessed from loss of ATP as well as from measures of alamarB lue~ and lactate dehydrogenase in the media and from counts of TUJ1 positive cells using immunocytochemistry. Dividing cells were identified by expression of Ki67 and phenotyped by double labeling with GFAP, MAP2 ab or TUJ1. RESULTS: We report that when cultured in NeuraLife~(TM), AGS cells remain viable out to 21 DIV, continue to express TUJ1 and begin to express MAP2 ab. Viability of hN PCs assessed by fluorescence alamarB lue(arbitrary units) depends on both glucose and oxygen availability [viability of hNPCs after 24 h oxygen glucose deprivation(OGD) with return of oxygen and glucose decreased from 48151 ± 4551 in control cultures to 43481 ± 2413 after OGD, P 0.05]. By contrast, when AGS NPCs are exposed to the same OGD with reperfusion at 14 DIV, cell viability assessed by alamar Blue increased from 165305 ± 11719 in control cultures to 196054 ± 13977 after OGD. Likewise AGS NPCs recovered ATP(92766 ± 6089 in control and 92907 ± 4290 after modeled reperfusion; arbitrary luminescence units), and doubled in the ratio of TUJ1 expressing neurons to total dividing cells(0.11 ± 0.04 in control cultures vs 0.22 ± 0.2 after modeled reperfusion, P 0.05). Maintaining AGS NPCs for a longer time in culture lowered resistance to injury, however, did not impair proliferation of NPCs relative to other cell lineages after oxygen deprivation followed by re-oxygenation.CONCLUSION: Ischemic-like insults decrease viability and increase cell death in cultures of human NPCs. Similar conditions have less affect on cell death and promote proliferation in AGS NPCs. 相似文献