Plasma levels of luteinizing hormone and steroid hormones in free-living winter groups of willow tits (Parus montanus)

Plasma levels of LH, DHT, testosterone, and corticosterone were measured for all members in free-living winter flocks of willow tits, Parus montanus. Hormonal data were related to (1) flock size and (2) age/sex differences. The winter flock defends a large winter territory and shows a well-established social hierarchy in which adults consistently dominate first-year birds. One winter group normally consists of four individuals, two adults and two juveniles. In flocks containing four or five members juvenile willow tits had significantly higher corticosterone values than adults. In small-sized groups, containing three members, all individuals had high plasma levels of corticosterone. No other effects of flock size was found. When data were treated on an age/sex basis, i.e., flock size was not considered, juvenile females were found to have significantly higher plasma levels of testosterone than adult birds, and also significantly higher levels of DHT than juvenile males and adult females. Also, juvenile willow tits had significantly higher plasma levels of corticosterone than adult birds.     

Manipulating the appearance of a badge of status causes changes in true badge expression

Signals of dominance and fighting ability (i.e. status signals) are found in a wide range of taxa and are used to settle disputes between competitive rivals. Most previous research has considered status-signal phenotype as an attribute of the individual; however, it is more likely that signal expression is an emergent property that also incorporates aspects of the social environment. Furthermore, because an individual''s signal phenotype is likely to influence its social interactions, the relationships between status signals, social environment and individual quality are probably much more complex than previously appreciated. Here, we explore the dynamic relationship between social interactions and signal expression in a previously undescribed status signal, the frontal shield of the pukeko (Porphyrio porphyrio melanotus: Aves). We demonstrate that frontal shield size is a strong predictor of dominance status within social groups, even after controlling for potentially confounding variables. Then, we evaluate the relationship between social interactions and signal expression by testing whether manipulating apparent shield size influences (i) dominance interactions and (ii) future signal expression. By showing that decreasing apparent shield size causes both an increase in the amount of aggression received and a decrease in an individual''s true shield size, we provide the first evidence of dynamic feedback between signal expression and social interactions. Our study provides important insight into the role of receiver-dependent (i.e. social) costs in maintaining signal honesty and demonstrates a unique approach to studying status signalling applicable to future studies on dynamic morphological signals.     

Ovulation and implantation in montane voles (Microtus montanus) as a function of varying amounts of copulatory stimulation

Estrous female voles (Microtus montanus) received (a) no copulation, (b) one ejaculatory series, (c) two ejaculatory series, or (d) more than two series. Copulation was shown to be essential for ovulation, and increasing amounts of copulatory stimulation were demonstrated to increase the probability of ovulation. Only 25% of females receiving one ejaculatory series ovulated, whereas 100% of those receiving more than two series ovulated. Thus, multiple ejaculations play an important role in successful reproduction in this species.     

Plasma cortisol measurements in precocious male and nonprecocious male juvenile steelhead trout (Salmo gairdneri)

Summary The mean biweekly plasma cortisol levels of juvenile nonmigratory precocious male steelhead trout,Salmo gairdneri, maintained from June through November in our laboratory under natural photoperiodic conditions ranged from 2.4–27.2 g/dl. Greatest mean cortisol occurred during the month of greatest gonadal mass, suggesting a direct interrenal-testicular relationship in this population of trout. The monthly mean plasma cortisol level of nonprecocious juvenile steelhead males captured prior to their downstream migration to the ocean from an Idaho hatchery and maintained in the laboratory simultaneously with the precocious males was low. For some months plasma cortisol was less than 0.1 g/dl. In June, however, plasma cortisol in nonprecocious males was 11.0 g/dl.     

Transition of nonharem male to harem male status in the short-nosed fruit bat Cynopterus sphinx

The short-nosed fruit bat Cynopterus sphinx is known to exhibit resource defence polygyny as its primary mating strategy. Tent construction by harem males to recruit females represents a heavy investment of time and effort, which is not done by nonharem males. The previously unobserved mode of harem formation by the solitary males was studied using mark-recapture and radio-telemetry. In our observation, the solitary males roosting near to harems started recruiting females by occupying the tent abandoned by the harems. This result suggests that the transition of nonharem male to harem male status possibly by a previously unobserved mode and the female recruitment is associated with resource (roost). It implies that the solitary males are actively involving in female recruitment and also presumably mating.     

Pasteurella multocida toxin as a tool for studying Gq signal transduction

Pasteurella multocida toxin (PMT) stimulates and subsequently uncouples phospholipase C (PLC) signal transduction through its selective action on the G_q subunit. This review summarizes what is currently known about the molecular action of PMT on G_q and the resulting cellular effects. Examples are presented illustrating the use of PMT as a powerful tool for dissecting the molecular mechanisms involving pertussis toxin (PT)-insensitive heterotrimeric G proteins.     

树麻雀表型的环境适应进化

树麻雀(Passer montanus)分布范围广、海拔梯度大,也是人类活动的伴随物种。对中国837个样本的10个形态特征与温度、日照、海拔和风速等4个主要环境因子进行相关分析,结果显示:树麻雀的体重、嘴裂、翅长、尾长、跗跖长、脑骨宽、眼间距与日照因子显著相关(P0.05),体重、体长、翅长、尾长、跗跖长与海拔因子显著相关(P0.05),体重、嘴峰、翅长、脑骨长与温度因子显著相关(P0.05),表明树麻雀的形态指标易随环境因子的变化而变化。通过控制经度和海拔两个变量,对形态指标与纬度的偏相关分析表明,体重、翅长、脑骨长和脑骨宽与纬度呈显著正相关(P0.05),体表突出部分嘴峰、嘴裂与纬度呈显著负相关(P0.05),即随着纬度的升高,树麻雀身体逐渐变大,符合贝格曼规律;体表突出部分嘴峰和嘴裂随纬度升高变短,符合阿伦规律。飞行能力与海拔因子呈极显著正相关(n=92,r=0.217,P=0.038),表明树麻雀在高海拔地区具有更强的飞行能力,这也许是它成为广布种的重要原因。     

The ovicidal effects of a juvenile hormone and a juvenile hormone analogue on the fleshfly, Sarcophaga bullata

Egg fertility was reduced in adult females of Sarcophaga bullata treated topically with a juvenile hormone (Cecropia JH-1) or a juvenile hormone analogue, ZR-515 (isopropyl-11-methoxy-3,7,11-trimethyl-dodeca-2,4-dienoate), the effect was most noticeable when the flies were treated on the day of ovulation. Depending on the time of treatment, JH and JHA affected different stages of development. Treatment on the day before ovulation produced a high percentage of embryonic arrest; when the flies were treated on the day of ovulation a major proportion of fully developed embryos failed to hatch. Treatment at the early stages of embryogenesis caused mortality of larvae before molting to third instar. There was no delayed mortality after the third instar.

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Résumé Les effets ovicides d'une hormone juvénile (Cecropia JH-1) et d'un analogue d'hormone juvénile (ZR-515) ont été examinés par application locale sur des femelles adultes de Sarcophaga bullata à différents stades du dévelopement des ufs.Le traitement des mouches le jour de l'ovulation est très efficace et empèche les embryons totalement développés d'éclore et de donner des larves de premier stade.L'application de ces produits un jour avant l'ovulation provoque l'arrêt de l'embryogenèse; quand les mouches sont traitées un jour après l'ovulation, la mortalité est plus tardive et une proportion importante de larves meurt avant la mue donnant le troisième stade.

     

Juvenile hormone involvement in Drosophila melanogaster male reproduction as suggested by the Methoprene-tolerant mutant phenotype

Juvenile hormone (JH) involvement in male reproduction is poorly understood. In Drosophila melanogaster adults, JH deficiency has been shown to result in lowered protein synthesis in male accessory glands. To probe additional roles, we have examined males homozygous for a null allele of Methoprene-tolerant (Met). This gene is involved in the action of JH, possibly at the JH receptor level, and Met²⁷ null mutants reflect a diminution of JH action. Met²⁷ males were found to have reduced protein accumulation in male accessory glands and to court and mate wild-type females much less avidly than do either Met⁺ or Met²⁷; Met⁺ transgenic males. Exposure of Met²⁷ males to methoprene partially rescued the courtship deficiency. However, sperm transfer as reflected by fertility of Met²⁷ fathers was found to be similar to that of Met⁺. Taken together with previous work examining the JH-deficient mutant apterous, these results corroborate JH involvement in protein synthesis in the male accessory glands and suggest a role for JH in promoting male mating behavior in these flies.     

Effects of nutritional factors on juvenile development in male European ground squirrels (Spermophilus citellus)

In European ground squirrels (Spermophilus citellus) as in other obligate hibernators, physiological processes underlie strict time constraints. Especially for the juveniles growth and prehibernatory fattening are temporally very limited. The aim of this study was to determine the effects of specific nutritional factors on development in juvenile males. Male ground squirrels were investigated for a 7-week period starting at natal emergence. Individuals were assigned to 1 of 3 experimental groups and were provided with a diet either high in proteins or polyunsaturated fatty acids (PUFAs). The third group was used as a control and was fed with a standard rat diet. Food quality affected growth in that males of the high-protein group had significantly larger head lengths in week 4, 5, and 6 after natal emergence than those of the other 2 groups. However, body mass did not differ significantly between the groups. All juvenile males showed an increase in plasma testosterone levels from week 1–2 to week 3–4 post-emergence, thereafter testosterone secretion remained stable until week 5–6. The daily testosterone increase after the first 2 weeks was significantly higher in the PUFA group compared to the other 2 groups. The results underline the importance of diet composition for growth rates and the timing of gonadal activation during early development in this species.     

Dissemination of entomopathogenic fungi using Busseola fusca male as vector

The stem borer, Busseola fusca (Fuller), is an important pest of maize Zea mays L. and sorghum Sorghum bicolor (L.) in eastern and southern Africa. To control this pest, biological control methods including the use of entomopathogenic fungi are being considered. The pathogenicity of one isolate of Metarhizium anisopliae (Metsch.) Sorok. and one isolate of Beauveria bassiana Bals. (Vuill.) were first tested on different developmental stages of B. fusca including eggs, neonate, 2nd and 3rd-instar larvae. Both fungal isolates were pathogenic to all the stages tested. However, differences in mortality were observed among larvae that hatched from treated egg masses. Experiments were conducted thereafter to test whether B. fusca males could serve as a vector for fungal conidia to contaminate B. fusca females and subsequently eggs and larvae. Results demonstrated that B. fusca males successfully transferred inoculum to females during copulation, which in turn transmitted it to the eggs they laid on maize plants, resulting in the decrease of leaf damages.     

The bacterial phleomycin resistance geneble as a dominant selectable marker inChlamydomonas

A chimeric gene composed of the coding sequence of theble gene fromStreptoalloteichus hindustanus fused to the 5 and 3 untranslated regions of theChlamydomonas reinhardtii nuclear geneRBCS2 has been constructed. Introduction of this chimeric gene into the nuclear genome ofC. reinhardtii by co-transformation with theARG7 marker yields Arg⁺ transformants of which approximately 80% possess theble gene. Of these co-transformants, approximately 3% display a phleomycin-resistant (Pm^R) phenotype. Western blot analysis using antibodies against theble gene product confirms the presence of the protein in the Pm^R transformants and genetic analysis demonstrates the co-segregation of theble gene with the phenotype in progeny arising from the mating of a Pm^R transformant to wild-type strains. Direct selection of Pm^R transformants was achieved by allowing an 18-h period for recovery and growth of transformed cells prior to selection. This work represents the first demonstration of stable expression and inheritance of a foreign gene in the nuclear genome ofC. reinhardtii and provides a useful dominant marker for nuclear transformation.     

Light as a signal influencing the phosphorylation status of plant proteins

The phosphorylation-status of a number of plant enzymes has been shown to be altered in response to light. Phosphoenolpyruvate carboxylase is phosphorylated (more active) in C₄ plants in the light but CAM phosphoenolpyruvate carboxylase is phosphorylated (more active) in the dark. C₄ plant pyruvate, Pi dikinase is dephosphorylated (activated) in the light and sucrose phosphate synthase is less phosphorylated (more active) in the light. The mitochondrial pyruvate dehydrogenase is inactivated (phosphorylated) in the light. The reversal of these events occurs in the dark or when photosynthesis is inhibited. Phytochrome and blue light receptors also alter the phosphorylation-status of proteins. The evidence is rapidly increasing in support of signal transduction networks in plants that involve light reception.     

The controversial effects of dehydrated powder of Gracilaria birdiae as a food supplement to juvenile male rats

Journal of Applied Phycology - The present study aimed to characterize in vitro antioxidant properties of red algae (Gracilaria birdiae) powder and to investigate its potential protective and...     

The structure of a juvenile hormone-binding lipophorin from the hemolymph of Diploptera punctata

The high molecular weight, high affinity juvenile hormone binding protein from the hemolymph of Diploptera punctata was identified as a lipophorin by gradient KBr ultracentrifugation and SDS gradient PAGE. This juvenile hormone binding lipophorin (JHBL) was composed of two subunits, apolipoprotein I (230 kDa mol. wt) and apolipoprotein II (80 kDa mol. wt). The density of the native protein was 1.15 g/ml. Photoaffinity labeling using the JH analog [³H]EFDA demonstrated that the JH binding site resides on apolipoprotein I. The amino acid composition of both native lipophorin and its two subunits was determined and the N-terminal sequence of the 80 kDa apolipoprotein described for 19 of the first 21 amino acids. This sequence did not have similarity to any known protein. The N-terminus of the 230 kDa apolipoprotein was blocked. The specificity of a monoclonal antibody to purified native JHBL was also demonstrated. We show that the monoclonal antibody was specific to the 230 kDa subunit and did not recognize the 80 kDa apolipoprotein.     

Homosexual male pairing in Schistosoma mansoni

Basch P. F. and Gupta B. C. 1988. Homosexual male pairing in Schistosoma mansoni.International Journal for Parasitology18: 1115–1117. To see whether male worms within the gynecophoral canal of another male worm would become feminized (i.e. express vestigial female-associated genes), we established homosexual pairs by twice exposing mice to male cercariae with a 4 or 6-week interval, and perfusing 3–5 weeks later. From 13 to 34% of these worms were found in pairs, compared with 0 to 7% in singly exposed controls. ‘Inner’ males in homosexual pairs showed no histological evidence of female reproductive structures, but were stunted, had poorly developed testes, and the high nuclear density characteristic of mature females. More vitelline follicles occurred in unpaired unisexual males than in homosexually paired males, fewest in bisexually paired males. Uptake of tyrosine, an indicator of vitelline development, occurred in the same relative order. The gynecophoral microenvironment often led to stunting, probably through starvation induced by the relative inaccessibility of host blood to homosexually clasped males.