Validation of a cortisol enzyme immunoassay and characterization of salivary cortisol circadian rhythm in chimpanzees (Pan troglodytes)

Monitoring concentrations of stress hormones is an important tool for behavioral research and conservation for animals both in the wild and captivity. Glucocorticoids can be measured in mammals as an indicator of stress by analyzing blood, feces, urine, hair, feathers, or saliva. The advantages of using saliva for measuring cortisol concentrations are three-fold: it is minimally invasive, multiple samples can be collected from the same individual in a short timeframe, and cortisol has a relatively short response time in saliva as compared with other materials. The purpose of this study was to: (1) conduct an adrenocorticotropic hormone (ACTH) challenge as a physiological validation for an enzyme immunoassay to measure salivary cortisol in chimpanzees and (2) characterize the circadian rhythm of salivary cortisol in chimpanzees. We determined that salivary cortisol concentrations peaked 45 min following the ACTH challenge, which is similar to humans. Also, salivary cortisol concentrations peaked early in the morning and decreased throughout the day. We recommend that saliva collection may be the most effective method of measuring stress reactivity and has the potential to complement behavioral, cognitive, physiological, and welfare studies.     

Ontogeny of endocrine cells in the respiratory system of Syrian golden hamsters

The ontogeny of protein gene product 9.5 (PGP 9.5), serotonin (5–HT), calcitonin gene-related peptide (CGRP), and calcitonin (CT) immunoreactivity was evaluated in small-granule endocrine cells of hamster laryngotracheal epithelium from fetal day 11 to adulthood. Two centrifugal (proximal-to-distal) patterns of differentiation occur. The first pattern begins during fetal life. Endocrine cells, single and clustered in groups (presumptive- or protoneuroepithelial bodies, pNEBs), initially co-localize immunostaining for PGP 9.5, 5–HT, and CGRP in the larynx and proximal 2/3 of the trachea on day 12 and spread to the caudal trachea on day 13. 5–HT disappears fleetingly during the 24 h preceding birth; otherwise immunoreactivity for all three substances persists into adulthood. The clusters of endocrine cells survive beyond birth but are so diluted by expansion of the nonendocrine epithelium as to become inconspicuous. Since innervation was not actually observed, these clusters may persist as pNEBs, without developing connections to afferent or efferent nerve fibers. The second pattern concerns single small-granule cells stainable for CGRP but not for 5–HT. These cells first appear in the larynx and cartilaginous part of the cranial trachea on postnatal day 3, and in the middle and caudal trachea, on day 5. The cells increase in number on day 7. In adults, they predominate among endocrine cells of the cartilaginous region. A subset of these cells begins to co-express CT proximally on postnatal day 10, reaching the caudal end of the trachea by 3 weeks. A few elements of the older 5–HT-positive population may also become immunoreactive for CT in juvenile hamsters.     

Human Intestinal Allografts Contain Functional Hematopoietic Stem and Progenitor Cells that Are Maintained by a Circulating Pool

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Anemochory of diapausing stages of microinvertebrates in North American drylands

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Climate change,extinction, and Sky Island biogeography in a montane lizard

Around the world, many species are confined to “Sky Islands,” with different populations in isolated patches of montane habitat. How does this pattern arise? One scenario is that montane species were widespread in lowlands when climates were cooler, and were isolated by local extinction caused by warming conditions. This scenario implies that many montane species may be highly susceptible to anthropogenic warming. Here, we test this scenario in a montane lizard (Sceloporus jarrovii) from the Madrean Sky Islands of southeastern Arizona. We combined data from field surveys, climate, population genomics, and physiology. Overall, our results support the hypothesis that this species' current distribution is explained by local extinction caused by past climate change. However, our results for this species differ from simple expectations in several ways: (a) their absence at lower elevations is related to warm winter temperatures, not hot summer temperatures; (b) they appear to exclude a low‐elevation congener from higher elevations, not the converse; (c) they are apparently absent from many climatically suitable but low mountain ranges, seemingly “pushed off the top” by climates even warmer than those today; (d) despite the potential for dispersal among ranges during recent glacial periods (~18,000 years ago), populations in different ranges diverged ~4.5–0.5 million years ago and remained largely distinct; and (e) body temperatures are inversely related to climatic temperatures among sites. These results may have implications for many other Sky Island systems. More broadly, we suggest that Sky Island species may be relevant for predicting responses to future warming.     

Cellular and gene expression responses involved in the rapid growth inhibition of human cancer cells by RNA interference-mediated depletion of telomerase RNA

Inhibition of the up-regulated telomerase activity in cancer cells has previously been shown to slow cell growth but only after prior telomere shortening. Previously, we have reported that, unexpectedly, a hairpin short interfering RNA specifically targeting human telomerase RNA rapidly inhibits the growth of human cancer cells independently of p53 or telomere length and without bulk telomere shortening (Li, S., Rosenberg, J. E., Donjacour, A. A., Botchkina, I. L., Hom, Y. K., Cunha, G. R., and Blackburn, E. H. (2004) Cancer Res. 64, 4833-4840). Here we have demonstrated that such telomerase RNA knockdown in cancer cells does not cause telomere uncapping but rather induces changes in the global gene expression profile indicative of a novel response pathway, which includes suppression of specific genes implicated in angiogenesis and metastasis, and is distinct from the expression profile changes induced by telomere-uncapping mutant template telomerase RNAs. These cellular responses to depleting telomerase in human cancer cells together suggest that cancer cells are "telomerase-addicted" and uncover functions of telomerase in tumor growth and progression in addition to telomere maintenance.     

No sex difference in yolk steroid concentrations of avian eggs at laying

Yolk steroids of maternal origin have been proposed to influence genetic sex determination in birds, based on sex differences in yolk steroid concentrations of peafowl eggs incubated for 10 days. More recent reports dispute this proposal, as yolk steroids in eggs incubated for 3 days do not show such sex differences. To date, research examining this phenomenon has only analysed incubated eggs, although sex in avian species is determined before incubation begins. This may be a serious methodological flaw because incubation probably affects yolk steroid concentrations. Therefore, we investigated sex differences in yolk steroid concentrations of unincubated avian eggs. We withdrew yolk for steroid analysis from fresh, unincubated Japanese quail (Coturnix japonica) eggs by biopsy, and then incubated those eggs for 10 days, after which we harvested the embryonic material for genetic sexing and the incubated yolk for further steroid analysis. We found no sex differences in fresh Japanese quail eggs; however, sex differences were apparent in yolk steroids by day 10 of incubation, when female eggs had significantly more oestrogen in relation to androgen than male eggs. Concentrations of all yolk androgens decreased dramatically between laying and day 10 of incubation, whereas oestradiol (E2) concentrations increased marginally. Thus, yolk concentrations of androgens and E2 do not appear critical for avian sex determination.