Interactions in male baboons: the importance of both males’ testosterone

To date, research on testosterone and behavior has focused on individuals, even when studying social behaviors that necessarily involve multiple participants. Here, we explore male responses to other males of different dominance ranks and testosterone levels in a population of wild baboons. In chacma baboons (Papio hamadryas ursinus) of the Okavango Delta, a male’s testosterone is related to his rank trajectory and, therefore, the threat he poses to other males. To examine the effects of testosterone and rank on male–male interactions, we used playback experiments to measure how a target male responded to the simulated approach of another male, scoring responses by whether or not the subject moved away from the speaker in the first minute. High testosterone subjects did not move away from the speaker more often than low testosterone subjects, but high testosterone callers elicited a move more often than low testosterone callers. When the combined testosterone of the subject and caller was high, moves were most common. The rank relationship between subject and caller did not predict moves, but the effect of combined testosterone on moving was most pronounced in adjacently ranked males. Adjacently ranked, high testosterone males are the most likely to be competing for each others’ rank, and our experiments on these dyads elicited the most moves. Both behavioral and experimental observations indicate that testosterone may be more important than the rank relationship in predicting the outcome of male–male interactions. Furthermore, combined information on the testosterone of both males was the best predictor of results, highlighting the utility of dyadic analyses when relating testosterone to behavior.     

Mate guarding and territorial aggression vary with breeding synchrony in golden whistlers (<Emphasis Type="Italic">Pachycephala pectoralis</Emphasis>)

Male paternity assurance behaviour during the female fertile period has been widely documented amongst birds. In contrast, how sex-specific behavioural strategies vary with local breeding synchrony levels remains largely unknown. This is important because, in many species, intra-population patterns of extra-pair fertilisation rates, and hence cuckoldry risk, are known to vary with the number of simultaneously fertile females. Each sex may therefore differ in how they behave towards male conspecifics during different degrees of breeding synchrony. Here I provide evidence of such sex-specific differences in the golden whistler (Pachycephala pectoralis), a species in which within-pair paternity assurance is negatively associated with breeding synchrony. Via simulated territorial intrusions using decoy males, I show that males, but not females, increase levels of aggression to male intruders during periods of low synchrony, possibly because cuckoldry risk is greatest during this period. In addition, males appear to invest more effort into mate guarding after, but not before, territorial intrusions during this period. These inter-sexual differences may reflect conflicts in interest between the sexes, with females consistently showing interest in males during the fertile period regardless of synchrony levels and males investing more resources into expelling intruders when the risk of paternity loss is greatest. This study thus provides evidence that males may be able to detect variation in breeding synchrony and cuckoldry risk and adjust their paternity assurance behaviour accordingly.     

The effects of bisphenol A on sex hormone levels of F0 female rats and F1 male rats during weaning period

The effects of bisphenol A (BPA) were examined on sex hormones of F1 generation male rats during weaning period. Female rats were exposed to BPA from day 0 after pregnancy to the weaning period at doses of 50, 100, or 200 mg kg^?1. The sex hormone levels of F1 generation male rats were determined. This study shows that F0 generation female rats fed with 200 mg kg^?1 BPA had a significantly higher serum prolactin (PRL) levels at the end of weaning. Significantly higher levels of serum estradiol (E₂) were also found in female rats fed 100 or 200 mg kg^?1 BPA. Serum levels of E₂ in F1 male generation rats were higher in treatment groups compared to control groups while serum testosterone (T) levels were lower. Follicle stimulating hormone (FSH) in F1 generation rats fed 200 mg kg^?1 was markedly decreased. The relative testicular weights were significantly less in 100 and 200 mg kg^?1 BPA groups. BPA was found to alter the sex hormone levels in F1 male rats during weaning period and thus disrupted endocrine functions.     

植物化学杀雄研究进展

介绍了化学杀雄剂诱导植物雄性不育的变化,回顾了化学杀雄杂种优势利用研究的进展,阐述了化学杀雄杂种优势利用的特点,以及化学杀雄剂的设计思路和常用的化学杀雄剂。     

壬基酚聚氧乙烯醚对成年雄性斑马鱼HPG轴相关基因表达的影响

本研究以模式动物斑马鱼（Danio rerio）为受试生物,采用半静态水体暴露的方式研究了不同浓度壬基酚聚氧乙烯醚（NPEO）对斑马鱼雄性成鱼下丘脑-垂体-性腺轴（HPG轴）的影响.结果显示,考察浓度范围内的NPEO暴露可以显著上调斑马鱼脑中GnRH2、GnRHR1、GnRHR2、GnRHR4、FSHβ和LHβ基因,以及性腺中LHR基因的相对表达量.GnRHR和LHR基因表达量对较低浓度NPEO暴露较为敏感,其中GnRHR4和LHR基因表达量在低至0.001mg/L的NPEO暴露下即出现显著上调.0.1和10mg/L NPEO暴露可以显著抑制斑马鱼精巢中CYP17基因的表达量,而10mg/L NPEO暴露则可以显著诱导CYP19a基因的表达量.GnRH相关调控基因表达量的上调,表明NPEO暴露可以诱导下丘脑分泌GnRH,进而刺激垂体分泌GtH.NPEO暴露诱导CYP19a基因的表达,促进了内源雌激素的合成.同时,NPEO通过抑制CYP17表达,可能抑制睾酮（T）的合成,干扰斑马鱼精巢中原有的性激素平衡.斑马鱼精巢内雌激素水平升高负反馈给垂体,刺激垂体分泌促性腺激素.由此表明,考察浓度范围内（0.001~10mg/L）的NPEO的暴露可以影响雄性斑马鱼成鱼HPG轴的反馈调节.     

Immune function, dominance and mating success in drumming male wolf spiders Hygrolycosa rubrofasciata

In this study, we provide a piece of experimental evidence that immune function is related to dominance and mating success in wild caught male wolf spiders, Hygrolycosa rubrofasciata. In the mating season, H. rubrofasciata males are actively searching for receptive females, and while searching males often engage in agonistic behavior (i.e., agonistic drumming signals, chases, and fights) with each other. The present results demonstrate that dominant males had higher lytic activities in their hemolymph than subordinates. Lytic activity estimates the concentration of antimicrobial peptides with lysozyme-like activity in hemolymph, which have been shown to play an important role in defense against bacteria, viruses, and fungi. Dominants also had higher courtship drumming rates than subordinates. Moreover, winners in mating competition had higher lytic activities than losers, but this was measured nonindependently of dominance status. Among males with mating failure, there was a moderate negative correlation between encapsulation rate and courtship drumming rate, suggesting that low quality males might not be able to bear the immunological costs of courtship behavior. These results suggest that females might gain immunological benefits by preferring vigorous males.     

<Emphasis Type="Italic">Drosophila melanogaster</Emphasis> virgins are more likely to mate with strangers than familiar flies

Recent evidence shows that females of many species can discriminate against males and/or male phenotypes they have mated with previously. However, these studies have not tested whether actual mating is necessary to induce the avoidance behaviour. A preference for strangers may have evolved because it avoids multiple matings with similar genotypes. Alternatively, there may be selection against mating with familiar individuals directly. By choosing its first mate among unfamiliar individuals (which are less likely close relatives than are those encountered early in life), a virgin might disentangle some of the potential benefits of avoiding genetic incompatibility and inbreeding in the offspring from the costs of remating. In this study, we test whether Drosophila melanogaster flies bias their mate choice towards strangers according to previous, non-copulatory, experience. Based on 173 trials over 12 weeks, virgin females presented with two virgin males were 59% more likely to mate with a novel male than the one which she had been housed with for 8 h the day before. Hence we present the first report showing that a dipteran can distinguish between previously encountered and not previously encountered conspecifics.     

二噁英暴露对成年男性血清类固醇激素的影响

为了解二噁英（PCDD/DFs）对成年男性类固醇激素水平的影响,采用高分辨气相色谱法/高分辨质谱联用法（HRGC/HRMS）及液相色谱-质谱联用法（LC-MS/MS）分析二噁英污染地区成年男性（n=50）及非污染地区成年男性（n=48）血清中9种类固醇激素水平和17种二噁英同类物浓度.结果显示成年男性血清中双氢睾酮、睾酮、雌二醇的水平与部分二噁英同类物浓度存在显著性相关.污染地区成年男性双氢睾酮、睾酮、雌二醇的水平与年龄呈显著性正相关.以上结果表明二噁英暴露导致成年男性类固醇激素中的性激素变化异常.     

镉对河南华溪蟹副性腺组织的氧化性损伤作用

为了探明慢性镉胁迫对河南华溪蟹(Sinopotamon henanense)副性腺的生殖毒性作用,实验设置了2个镉浓度组(0.725和1.45 mg·L-1)、1个对照组、3个处理时间(7、14和28 d),研究了镉在副性腺组织的积累,以及镉对副性腺组织细胞结构、抗氧化酶,如超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPx)活性及脂质过氧化水平(MDA含量)、蛋白质羰基化(PCO含量)和DNA-蛋白质交联(DPC)的影响.结果显示,镉处理后在河南华溪蟹副性腺组织中的积累显著或极显著高于对照组,且随着时间的延长和镉浓度的增加,副性腺组织镉的积累逐渐增高;副性腺组织细胞结构发生了不同程度的改变,主要表现为上皮细胞与基膜分离甚至破裂导致细胞核丢失.镉浓度0.725和1.45 mg·L-1条件下处理28 d,基膜结构发生明显改变,上皮细胞和基膜之间出现较大空腔,上皮细胞细胞核变形.SOD和GPx活性先升后降,而CAT的活性则随着镉浓度的增加逐渐升高;PCO含量和DPC均随着时间的延长和浓度的增加而显著升高;MDA含量也呈明显的升高趋势,但在28 d有所下降.表明慢性镉胁迫对河南华溪蟹副性腺产生了明显的氧化损伤,可能会影响副性腺正常的生理功能.