Characterization of estrous cycles and pregnancy in Somali wild asses (Equus africanus somaliensis) through fecal hormone analyses

Although reproduction in the domestic horse has been well described, less is known about reproduction in wild equids. This study describes endocrine patterns associated with estrous cycles and pregnancy for Somali wild asses (Equus africanus somaliensis), an endangered African equid. Fecal samples were collected three times per week for more than 2 years from five female Somali wild asses at the Saint Louis Zoo; progestagen and estrogen metabolites were quantified using commercially available immunoassays. Progestagen analysis indicated that cycle lengths were 27.2 ± 1.2 days and females cycled throughout the year. Progestagen levels during early pregnancy were low and not sustained above baseline until approximately 40 weeks prior to partition. Concentrations increased markedly around 16 weeks prior to delivery and peaked 2–3 weeks before birth. Fecal estrogen levels also increased significantly starting 40–45 weeks before parturition and reached their maximal value approximately 20 weeks prior to birth. Neither foal heat nor lactational suppression of estrus was observed, and females cycled within 45 days after delivery. These data are the first to describe the reproductive physiology of Somali wild asses. As the species faces increasing threats in the wild, this information may support conservation efforts by assisting with ex situ breeding programs.     

Degradative covalent reactions important to protein stability

Commonly observed chemical modifications that occur in proteins during their in vitro purification, storage, and handling are discussed. Covalent modifications described include deamidation and isoaspartate formation, cleavage of peptide bonds at aspartic acid residues, cystine destruction and thioldisulfide interchange, oxidation of cysteine and methionine residues, and the glycation and carbamylation of amino groups.     

The role of adrenal corticosteroids in induction of micronuclei by morphine.

It has previously been shown that morphine can increase the frequency of micronucleated splenocytes when administered to mice, but not when cells are exposed to the opiate in vitro. Morphine treatment is also known to increase circulating levels of glucocorticosteroids, which have been reported to produce genetic damage in vivo and in vitro. In order to determine whether adrenal hormones might mediate the genotoxic effects of morphine, adrenalectomized and sham-operated mice were treated with morphine sulfate. In sham-operated animals administration of morphine produced a dose-related increase in the frequency of micronucleated cells, whereas adrenalectomy abolished the effect. When plasma from morphine-treated mice was used to supplement growth medium of untreated splenocytes, the frequency of micronucleated cells increased, an effect partially blocked by the steroid antagonist RU 486. The N-methylmorphine, which does not stimulate the release of corticosterone from adrenal glands, induced micronuclei formation in splenocytes, and administration of metyrapone, an inhibitor of corticosterone biosynthesis, blocked the morphine-induced increase in corticosterone secretion, but had no effect on the frequency of micronuclei formation. These results indicate that basal levels of glucocorticosteroids are required for induction of micronuclei by morphine in murine splenocytes, but activation of the hypothalamo-pituitary-adrenal (HPA) axis by morphine does not contribute to the observed response.     

Circular dichroic studies on Cu(II) interactions with a protamine,scylliorhinine Z3

The interaction of Cu(II) with the protamine scylliorhinine Z₃ was studied by means of CD measurements. At a 1:1 molar ratio, three complexes are formed. (1) In the pH range 5–6.5, the results suggest the formation of a five-membered chelate ring through the coordination of two nitrogen atoms, the N-terminal and the contiguous peptide nitrogen. (2) At pH ≥ 6.4, there is involvement of the lateral NH₂ group of Arg; at pH 6.5–8, the formation of a 3N cupric complex is strongly suggested. (3) At pH ≥ 8, results indicate the formation of a 4N complex as a major species in Cu(II)-Z₃ solution. The transformation from a 2N to a 3N complex, and from a 3N to a 4N complex was followed with the help of the σ(αNH₂) → Cu(II) charge-transfer dichroic band transitions. At Cu(II):Z₃ molar ratios ≥ 2 and at pH > 8, a new dichroic band appears, indicating the involvement of the tyrosine residue side chain in metal-ion complexation.     

Human growth hormone responses to repeated bouts of sprint exercise with different recovery periods between bouts.

This study examined the growth hormone (GH) response to repeated bouts of sprint cycling. Eight healthy men completed three trials consisting of two 30-s sprints on a cycle ergometer separated by either 60 min (Trial A) or 240 min (Trial B) of recovery and a single 30-s sprint carried out the day after Trial B (Trial C). Trials A and B were separated by at least 7 days. Blood samples were obtained at rest and during recovery from each sprint. In Trial A, GH was elevated immediately before sprint 2, and there was no further increase in GH following the second sprint [area under the curve: 460 (SD 348) vs. 226 min.mug(-1).l(-1) (SD 182), P = 0.05]. Free insulin-like growth factor I tended to be lower immediately before sprint 2 than sprint 1 (P = 0.06). Serum free fatty acids were not different immediately before each of the sprints. In Trial B, there was a trend for a smaller GH response to the second sprint [GH area under the curve: 512 (SD 396) vs. 242 min.mug(-1).l(-1) (SD 190), P = 0.09]. Free insulin-like growth factor I tended to be lower (P = 0.06), and serum free fatty acids were higher (P = 0.01) immediately before sprint 2 than sprint 1. There was no difference in the GH response to sprinting on consecutive days (Trials B and C). In conclusion, repeated bouts of sprint cycling on the same day result in an attenuation or even ablation of the exercise-induced increase in GH, depending on the recovery interval between sprints.     

Hold your breath beetle—Mites!

Respiratory gas exchange in insects occurs via a branching tracheal system. The entrances to the air‐filled tracheae are the spiracles, which are gate‐like structures in the exoskeleton. The open or closed state of spiracles defines the three possible gas exchange patterns of insects. In resting insects, spiracles may open and close over time in a repeatable fashion that results in a discontinuous gas exchange (DGE) pattern characterized by periods of zero organism‐to‐environment gas exchange. Several adaptive hypotheses have been proposed to explain why insects engage in DGE, but none have attracted overwhelming support. We provide support for a previously untested hypothesis that posits that DGE minimizes the risk of infestation of the tracheal system by mites and other agents. Here, we analyze the respiratory patterns of 15 species of ground beetle (Carabidae), of which more than 40% of individuals harbored external mites. Compared with mite‐free individuals, infested one's engaged significantly more often in DGE. Mite‐free individuals predominantly employed a cyclic or continuous gas exchange pattern, which did not include complete spiracle closure. Complete spiracle closure may prevent parasites from invading, clogging, or transferring pathogens to the tracheal system or from foraging on tissue not protected by thick chitinous layers.