CALLING SONG DISPLACEMENT IN A ZONE OF OVERLAP AND HYBRIDIZATION

The ground crickets Allonemobius fasciatus and A. socius meet in a mosaic zone of overlap and hybridization stretching from the East Coast to at least Illinois. To test whether male calling song differences were enhanced in sympatry, we analyzed the songs of crickets from inside and outside the zone of overlap along two transects. No evidence of calling song displacement was found in A. socius males from populations within the zone of overlap. On the other hand, A. fasciatus displayed calling song displacement in three populations. Our results are consistent with the hypothesis that the selective pressure exerted by the challenge from a related species is frequency dependent. While not a conclusive demonstration, the observed shifts in calling song are strongly suggestive of reproductive character displacement.     

Negative incorporation,the next generation and involvement in transnational organizations

ABSTRACT

Can the negative aspects of incorporation – discrimination, marginalization, and frustration with life in a country of settlement – help us to understand next generation transnationalism? This question is applied to a small, non-representative sample of next generation individuals involved in Mexican and Salvadoran transnational political and philanthropic organizations operating in California and Washington, DC. The findings suggest that negative incorporation had some explanatory potential for the transnational mobilization of some respondents. However, the study also suggests the multiple trajectories and contexts that give rise to next generation transnationalism. Involvement in cross-border organizations appears not only to be a refuge for those who perceive the country of settlement negatively or a means through which individuals can respond to negative experiences; it can also be pursued by individuals that positively identify with the country of settlement and perceive its values favourably, indicating the need for a more synthetic understanding of this phenomenon.     

鳄蜥对熟悉和陌生个体气味的辨别

个体辨别对于减少同种争斗以及配偶选择具有重要意义。我们用棉棒粘取鳄蜥(Shinisaurus crocodilurus)尿液作为气味源,以香水作为对照,测定鳄蜥对熟悉个体气味、陌生个体气味以及香水的舔舌次数和舔舌潜伏期,来探讨鳄蜥通过化学信息辨别熟悉和陌生个体的能力。结果显示,不论是雌性还是雄性,对不同个体尿液的舔舌次数均显著高于对香水的,舔舌潜伏期显著短于香水的;尽管雄性对陌生同性个体气味与熟悉同性个体气味的舔舌次数无显著差异,但对前者的舔舌潜伏期显著短于后者;雄性对陌生雌性气味的舔舌次数显著多于熟悉雌性气味的,对前者的舔舌潜伏期显著短于后者;雌性对陌生雄性气味的舔舌潜伏期显著短于对熟悉雄性气味的;雄鳄蜥对陌生雌性气味的舔舌次数显著多于雌鳄蜥对陌生雄性的。结果表明,鳄蜥能辨别同种个体的化学信息,并能通过化学信息来辨别熟悉和陌生个体,推测鳄蜥的这种辨别能力对其领域分配以及繁殖交配有重要作用。     

SWIMMING SPEEDS OF SINGING AND NON-SINGING HUMPBACK WHALES DURING MIGRATION

Limited data exist on swimming speeds of humpback whales ( Megaptera novaeangliae ) and none on swimming speeds of singing whales during migration. We tracked humpback whales visually and acoustically during migration from the breeding grounds past our study site on the east coast of Australia (latitude 26°28'S). The mean swimming speed for whales while singing was 2.5 km/h, significantly less than for non-singing whales with a mean of 4.0 km/h but significantly greater than the mean of 1.6 km/h observed for singing whales on the Hawaiian breeding grounds. Between song sessions, there was no significant difference in speeds between whales that had been singing and other whales. Migration speeds were less for whales while singing but increased during the season. Although humpback whales can swim rapidly while singing (maximum observed 15.6 km/h), they generally do not do so, even during migration. Slower migration by singers would delay their return to the polar feeding areas and may be costly, but may be a strategy to provide access to more females.     

Elevated yolk androgen levels and the expression of multiple sexually selected male characters

Maternal hormones in bird eggs modulate not only offspring development, but recently it has also been shown that these effects can persist into adult life. A number of long-lasting effects concern traits of which the expression or development is modulated by androgens. This suggests that the nature of yolk hormone-mediated maternal effects may be organizational. Maternal androgens may therefore play an important role in sexual selection, since the expression of sexually selected male characters is often androgen-dependent.We experimentally manipulated the yolk androgen concentrations of European Starling (Sturnus vulgaris) eggs. Subsequently we followed 49 unrelated males from hatching until year of first reproduction. We investigated the expression of multiple sexually selected male characters (song, beak color and throat feather characteristics), taking into account whether a trait is androgen-dependent.Elevated levels of yolk androgens affected the length of the embryonic period, but did not modify the expression of either androgen-dependent or androgen-independent sexually selected male characters including song phenotype at adulthood. Thus the most important function of yolk androgens in starlings and possibly other bird species may relate to the early developmental period. The outcome of our study together with the results of our meta-analysis indicates that the effects of yolk androgens on sexually selected male characters may be comparatively small. Our results suggest that this may relate to the numerous other environmental and/or genetic factors influencing the expression of sexually selected male characters.     

VPMCD: variable interaction modeling approach for class discrimination in biological systems

Data classification algorithms applied for class prediction in computational biology literature are data specific and have shown varying degrees of performance. Different classes cannot be distinguished solely based on interclass distances or decision boundaries. We propose that inter-relations among the features be exploited for separating observations into specific classes. A new variable predictive model based class discrimination (VPMCD) method is described here. Three well established and proven data sets of varying statistical and biological significance are utilized as benchmark. The performance of the new method is compared with advanced classification algorithms. The new method performs better during different tests and shows higher stability and robustness. The VPMCD is observed to be a potentially strong classification approach and can be effectively extended to other data mining applications involving biological systems.     

Glutamate taste: Discrimination between the tastes of glutamate agonists and monosodium glutamate in rats

Taste aversion studies have demonstrated that rats conditioned to avoid monosodium glutamate (MSG) with amiloride added to reduce the intensity of the sodium component of MSG taste, generalize this aversion to aspartic acid and to L-AP4, but not to ionotropic glutamate receptor agonists. That is, MSG, L-AP4 and aspartate have similar tastes to rats. However, conditioned taste aversion methods are unable to show to what extent the tastes of two substances are different. If two substances activate the same afferent processes (e.g. taste receptors), they are likely to produce the same tastes, but if they activate different afferent processes, the subject may detect differences between the tastes of the substances. In this study, rats were tested to determine if they could discriminate between the tastes of these agonists and MSG. We also established the detection thresholds for NMDA, aspartic acid and L-AP4, with and without amiloride (a sodium channel antagonist). Taste threshold values were 1-4 mM for NMDA and aspartic acid and 0.5-2.5 microM for L-AP4. None were affected by 30 micro M amiloride. Rats could readily distinguish between the tastes of MSG and NMDA but they had difficulty discriminating between the tastes of aspartic acid and MSG. Rats could also easily distinguish between 10-100 mM MSG and 0.01-5 mM L-AP4. However, in two separate experiments error rates increased significantly when L-AP4 concentrations were between 10-100 mM, indicating that the tastes of L-AP4 and MSG were similar at these concentrations.     

NMDA受体在海马CA_3区习得性LTP保持中的作用

在大鼠明暗分辨学习的建立和巩固过程中,通过与记录电极一起慢性埋植于海马CA_3区的注药管微量注射NMDA受体的特异性拮抗剂2-amino-5-phosphonovaleric acid(APV),观察对海马CA_3区突触效应及与之相关的习得性行为的影响。结果如下:(1)在动物经训练PS峰幅值刚增大至最高水平后,即在习得性LTP刚好形成后,每实验单元先于CA_3区注射AFV 1μl(2mmol/L),然后在药物有效作用时间内再进行训练,则PS峰值不能随训练而保持在最高水平,相反经8个实验单元,PS峰值降至实验前水平;相应地动物的正确反应率不能随训练而巩固,反而下降至10％以下。(2)在动物习得性LTP已形成并经一单元训练PS保持在最高水平后,于每实验单元训练前注射APV 1μl(2mmol/L),PS峰值同样不会随训练而保持在最高水平,经14个实验单元注药和训练,PS峰值逐渐降至实验前水平,相应地动物行为的正确反应率也降至10％以下,习得性行为消退,不过其消退速度比前一情况的动物为慢,说明习得性LTP发展情况不同,APV的作用效率有差别。结果表明:NMDA受体在习得性LTP的巩固中起着重要作用。     

Survival time and resistance to desiccation of diapause and non-diapause eggs of temperate Aedes (Stegomyia) mosquitoes

Time-related changes in the patterns of host discrimination may have a complex form depending on whether or not hosts are marked following first parasitisation, the persistence of chemicals in these marks, and changes in the host as a result of being parasitised. Here we present an experimental design capable of detecting temporal patterns in host discrimination of solitary parasitoids. This method is tested against experimental data from Aphidius ervi attacking the aphid, Acyrthosiphon kondoi. The results demonstrate that there are statistically significant changes in the patterns of egg distribution in aphid hosts held for intervals between 1 and 48 h between parasitisation. These changes appear to be attributable to increasing oviposition restraint by the superparasitising female as the time interval between attacks is increased. The form of this relationship is not significantly different to a sigmoid function and the rate of change of restraint was greatest between 6–8 h after the first oviposition.     

In silico analysis of expression pattern of a Wnt/β-catenin responsive gene ANLN in gastric cancer

Actin-binding protein anillin (ANLN) is primarily involved in the cytokinesis and known to be dysregulated in many cancers including gastric cancer (GC). However, the regulation and clinical significance of ANLN in GC are far less clear. In the present study, we aimed to investigate the clinical significance and possible regulators of ANLN in GC. We have identified the Wnt/β-catenin associated regulation of ANLN by analyzing the in vitro perturbed β-catenin mRNA expression profiles. Investigating the gastric tumors from publicly available genome-wide mRNA expression profiles, we have identified the over expression of ANLN in gastric tumors. Association between ANLN expression and clinical characteristics of GC showed elevated expression in intestinal type GC. Performing a single sample prediction method across GC mRNA expression profiles, we have identified the over expression of ANLN in proliferative type gastric tumors compared to the invasive and metabolic type gastric tumors. In silico pathway prediction analysis revealed the association between Wnt/β-catenin signaling and ANLN expression in gastric tumors. Our results highlight that expression of a Wnt/β-catenin responsive gene ANLN in GC is a molecular predictor of intestinal and proliferative type gastric tumors.