Rapid elevations in both steroid hormones and vocal signaling during playback challenge: a field experiment in Gulf toadfish

It is well known that plasma androgens are rapidly released in response to aggressive or sexual stimuli in a broad array of vertebrates. However, experimental work on behavioral functions of rapid androgen elevation is rare. A combination of field-based behavioral experiments and lab-based neuroendocrinological approaches is beginning to show how steroid hormones rapidly regulate the expression of vocal communication signals in Gulf toadfish (Opsanus beta). Male toadfish emit multiharmonic "boatwhistles" and shorter-duration, broadband "grunts" during intraspecific communication. Neurophysiology experiments demonstrate that androgens and glucocorticoids rapidly modify vocal motor patterning in male toadfish. In this study, we simulated territorial intrusions (vocal "challenges") with acoustic playbacks to toadfish in the field, and observed simultaneous, rapid (within 5-20 min) changes in vocalizations and steroid hormones. Both plasma androgens and vocal activity increased following the presentation of pure tones that mimic the duration of natural boatwhistles (275 ms), while they remained unchanged following playbacks of tone stimuli that mimic the duration of grunts (75 ms) or the upper-range of boatwhistles (475 ms). Circulating glucocorticoids were elevated in calling vs. non-calling males but were unaffected by playback stimuli, suggesting a role in the energetics of vocalization. These results strongly suggest that one function of rapid androgen elevation in response to social challenge is to mediate similarly rapid changes in territorial vocal signaling. Given the conserved organization of neuroendocrine and vocal motor systems, rapid steroid action on vocalization mechanisms may be true of other vocal vertebrates as well, including birds and mammals.     

种子超干贮藏技术应用面临的问题和研究方向

种子超干贮藏技术对种质资源保存具有很大的应用前景,但鉴于目前的研究进展,其应用还存在诸多技术上的问题。本文对种子超干贮藏技术在种子库中应用所面临的挑战以及需要开展的研究内容进行了如下几个方面的讨论：种子贮藏安全含水量下限的多样性决定了超干技术应用的复杂性;超干贮藏含水量安全下限的确定尚未有可靠的方法;超干贮藏的种子吸胀前需要恰当的预处理以避免吸胀损伤;超干处理前外源抗氧剂预处理可能改善超干贮藏效果;无氧条件可能对超干贮藏具有增效作用;糖类物质以及两性物质对种子在超干处理及超干贮藏过程中的保护作用。     

当前疫苗工业综述

本文系统化的综述了当前一个热门的研发领域-疫苗工业,并详细分析了其背景和潜在的市场,以及中国疫苗工业在发展中可能遇到的机遇和挑战。此外,还对中国疫苗工业存在的某些问题提出了解决方法。只有加强中国生物技术公司在高端疫苗领域的技术水平才能在根本上与国外制药业巨头竞争一席之地,向广大民众提供更好的药物。     

Development of seawater adaptation in pink salmon,Oncorhynchus gorbuscha,during downstream migration: relationships to temperature and residual yolk

Synopsis Seawater adaptability of wild pink salmon, Oncorhynchus gorbuscha, alevins was investigated using 96 h LC50 test, muscle sodium level and weight loss tests. Five temperature (2, 6, 9, 13 and 16°C) and two yolk groups were analysed during the beginning, the middle and the end of downstream migration. Both temperature and amount of residual yolk affected seawater adaptability. The computation of muscle sodium levels and weight loss after a short term (3–12 h) seawater challenge test may be a convenient method to estimate the seawater adaptability of fish too small to allow analysis of blood sodium concentration.     

Social correlates of testosterone and ornamentation in male mandrills

We investigated relationships between fecal androgen concentrations, facial coloration and behaviour in semi-free-ranging male mandrills. We found that fecal androgen levels were significantly positively related to dominance rank, independent of rank stability and the mating period, suggesting that male mandrills live in a permanently aggressive context in which they must actively maintain their dominance status. Facial red coloration was also significantly related to both fecal androgen levels and rank, with high ranking males having both higher androgen levels and redder faces, although dominant males did not always have the highest androgen levels or the reddest faces. Predictive relationships between androgen levels, coloration and rank were short-term. Androgen concentrations and facial redness both increased in the presence of receptive females, as did the former during periods of rank instability. We conclude that male facial redness is likely to represent an honest signal (to other males) of current androgen status, competitive ability and willingness to engage in fights and that females may also use this to assess male condition. Further, our findings provide support for the “challenge hypothesis” as originally proposed for birds by Wingfield.     

Juvenile hormone and the ontogeny of cockroach aggression

Our previous study [Kou et al., 2008. Juvenile hormone levels are increased in winners of cockroach fights. Horm. Behav. 52, 252–260] showed that the basic principle of the challenge hypothesis (hormone levels can respond to social stimuli to modulate aggression in vertebrates] could be applied to juvenile hormone (JH) levels and aggression in the lobster cockroach Nauphoeta cinerea. In that study, 80- to 85-day-old socially naïve males were used, as fighting is much more easily initiated in these older animals than in younger males, and JH III levels in the dominant were found to be significantly increased after an encounter compared to before the encounter and were significantly higher than those in the subordinates. In N. cinerea, newly emerged males usually show no aggressiveness towards each other and aggression is only initiated after several days of close contact. To investigate the development of aggression from an early age, in the present study, newly emerged males were paired to investigate the relationship between JH levels and aggression. The results showed that injection of JH III significantly increased the probability of the young males being fight winners. In each age group in which aggression was initiated, the dominants had significantly higher JH levels than either the subordinates or the same aged non-fighters. JH injection of subordinates on the day of rank establishment had no effect on the probability of rank switch. These results indicate that, (i) in newly emerged male pairs, JH plays a decisive role in rank establishment and the fact that dominant status is significantly associated with a higher JH titer and subordinate status with a lower JH titer is consistent with the basic principle of the challenge hypothesis, and (ii) after rank establishment, the lack of effect of JH treatment on rank change is consistent with the idea of “social inertia” in vertebrates.     

Context-specific territorial behavior in urban birds: no evidence for involvement of testosterone or corticosterone

Testosterone produced by the gonads is a primary mediator of seasonal patterns of territoriality and may directly facilitate territorial behavior during an encounter with a potential intruder. Costs and benefits associated with territoriality can vary as a function of habitat, for example through differences in resource distribution between areas occupied by different individuals. We investigated behaviors in response to simulated territorial intrusions (hereafter territorial behaviors) in urban (Phoenix, Arizona) and nearby desert populations of two Sonoran Desert birds (Curve-billed Thrasher and Abert's Towhee). We also examined the degree to which these behaviors are mediated by testosterone (T) and the adrenal steroid, corticosterone (CORT), which can interact with T in territorial contexts. In both species, urban birds displayed more territorial behaviors than their desert conspecifics, but this difference was not associated with variation in either plasma total or in plasma free (i.e., unbound to binding globulins) T or CORT. In addition, neither plasma T nor plasma CORT changed as a function of duration of the simulated territorial intrusion. Urban Abert's Towhees displayed more territorial behaviors in areas where their population densities were high than in areas of low population densities. Urban Curve-billed Thrashers displayed more territorial behaviors in areas with a high proportion of desert-type vegetation, particularly in areas that differed in vegetation composition from nearby randomly sampled areas, than in areas with a high proportion of exotic or non-desert type vegetation. Associations between territorial behavior and habitat characteristics were not related to plasma T or CORT. Understanding the hormonal processes underlying these associations between behavior and habitat may provide insight into how free-ranging animals assess territorial quality and alter their defensive behavior accordingly.     

Strong density-dependent competition and acquired immunity constrain parasite establishment: implications for parasite aggregation

The vast majority of parasites exhibit an aggregated frequency distribution within their host population, such that most hosts have few or no parasites while only a minority of hosts are heavily infected. One exception to this rule is the trophically transmitted parasite Pterygodermatites peromysci of the white-footed mouse (Peromyscus leucopus), which is randomly distributed within its host population. Here, we ask: what are the factors generating the random distribution of parasites in this system when the majority of macroparasites exhibit non-random patterns? We hypothesise that tight density-dependent processes constrain parasite establishment and survival, preventing the build-up of parasites within individual hosts, and preclude aggregation within the host population. We first conducted primary infections in a laboratory experiment using white-footed mice to test for density-dependent parasite establishment and survival of adult worms. Secondary or challenge infection experiments were then conducted to investigate underlying mechanisms, including intra-specific competition and host-mediated restrictions (i.e. acquired immunity). The results of our experimental infections show a dose-dependent constraint on within-host-parasite establishment, such that the proportion of mice infected rose initially with exposure, and then dropped off at the highest dose. Additional evidence of density-dependent competition comes from the decrease in worm length with increasing levels of exposure. In the challenge infection experiment, previous exposure to parasites resulted in a lower prevalence and intensity of infection compared with primary infection of naïve mice; the magnitude of this effect was also density-dependent. Host immune response (IgG levels) increased with the level of exposure, but decreased with the number of worms established. Our results suggest that strong intra-specific competition and acquired host immunity operate in a density-dependent manner to constrain parasite establishment, driving down aggregation and ultimately accounting for the observed random distribution of parasites.     

VP8* antigen produced in tobacco transplastomic plants confers protection against bovine rotavirus infection in a suckling mouse model

Group A rotavirus is a major leading cause of diarrhea in mammalian species worldwide. In Argentina, bovine rotavirus (BRV) is the main cause of neonatal diarrhea in calves. VP4, one of the outermost capsid proteins, is involved in various virus functions. Rotavirus infectivity requires proteolytic cleavage of VP4, giving an N-terminal non-glycosilated sialic acid-recognizing domain (VP8*), and a C-terminal fragment (VP5*) that remains associated with the virion. VP8* subunit is the major determinant of the viral infectivity and one of the neutralizing antigens.In this work, the C486 BRV VP8* protein was produced in tobacco chloroplasts. Transplastomic plants were obtained and characterized by Southern blot, northern blot and western blot. VP8* was highly stable in the transplastomic leaves, and formed insoluble aggregates that were partially solubilized by sonication. The recombinant protein yield was 600 μg/g of fresh tissue (FT). Both the soluble and insoluble fractions of the VP8* plant extracts were able to induce a strong immune response in female mice as measured by ELISA and virus neutralization test. Most important, suckling mice born to immunized dams were protected against oral challenge with virulent rotavirus. Results presented here contribute to demonstrate the feasibility of using antigens expressed in transplastomic plants for the development of subunit vaccines.     

Challenge of weed risk assessment (WRA) for ecological restoration in China: The case of Rhus typhina L. and the new officially released weed risk assessment system

China has conducted many ecological restoration projects to alleviate environmental degradation, with numerous alien species having good adaptability widely used for fast effect. However, unsuitable plant selection may bring negative impacts and even cause biological invasion. Weed risk assessment (WRA) is therefore indispensable, yet it is often contentious especially concerning those species that has been widely utilized before weedy attributes were noted. In this paper, we take Rhus typhina L. as an example to illustrate how scientific researches and social factors can influence the evaluation of alien species and cause challenge to WRA. The evaluation of this species is not only a pure scientific issue but also influenced by many factors such as the introduction history, current utilization status in afforestation, and divergent underlying values varying through persons and sectors. These factors determined the kind of data to be assessed, which lead to different evaluations, therefore, causing challenge to its WRA. We further examined newly officially released WRA system in China from the invasion biology viewpoint, arguing that it had some major flaws in design and validation and need much improvement. Considering the human dimension and biological characters together, we suggest that the “black list” and “green list” approaches with rigorous expert assessment should be adopted simultaneously in alien species management in China.