Experimental Addition of Green Plants to the Nest Increases Testosterone Levels in Female Spotless Starlings

Multiple male traits and displays may act in signalling sexually selected processes during courtship. Spotless starling males (Sturnus unicolor) carry green plants into their nests before egg laying, and recent studies have shown that this behaviour is related to female breeding decisions and the production of male‐biased broods. Although the functional implications of this effect on females are not yet clear, data suggest that it could be mediated by female circulating hormones. Additionally, females may show higher androgen levels as a consequence of the increased female–female competition generated by the increase in male attractiveness. We tested this hypothesis using the same manipulation of green nesting material that has been previously shown to result in an increase of male attractiveness in male spotless starlings. We found that females in experimental nests increased their circulating testosterone levels during the laying period. In addition, there was an increase of social interferences in the experimental nests because of the addition of green plants. We hypothesise that testosterone may allow females to maintain their mating status when competing with other females for the preferred males. Addition of green plants also increased the variance in the levels of circulating testosterone, suggesting plasticity between females in their response to the manipulation. We propose that there is a functional link between high testosterone levels, male‐biased sex ratios and female resource‐holding potential in intra‐sexual competition in this species.     

Effects of galactose on direct and indirect pathway estimates of hepatic glycogen synthesis

Hepatic glycogen is formed by direct and indirect pathways whose activities reflect altered nutrition or disease. Direct/indirect pathway measurements often involve test meals where ～10% of carbohydrate is galactose, but its effects on direct/indirect pathway estimates are unknown. Therefore, direct/indirect pathway contributions in 24-h fasted rats given 2 g/kg 100% glucose (GLU, n=6) or 90% glucose–10% galactose (GLU+GAL, n=6) were measured by [U-¹³C]glucose dilution and by position-5/position-2 glycogen enrichment (H5/H2) from 2H₂O. For GLU+GAL, galactose glycogenesis was independently measured with [1-¹³C]galactose. Glycogenesis was equivalent in both groups but for GLU+GAL, 23±4% of glycogen was derived from galactose. [U-¹³C]glucose reported a 30±3% direct pathway contribution to glycogenesis for GLU but only 20±3% for GLU+GAL (p=0.012 vs. GLU). H5/H2 yielded identical direct pathway estimates (32±3% GLU, 29±6% GLU+GAL). Thus, galactose glycogenesis was undetected by H5/H2 while [U-¹³C]glucose reported a reduced direct/indirect pathway ratio. With [1-¹³C]galactose also present, correct glycogenic source contributions were obtained.     

CD44-independent activation of the Met signaling pathway by HGF and InlB

Listeria monocytogenes is a facultative intracellular Gram-positive bacterium responsible for listeriosis. It is able to invade, survive and replicate in phagocytic and non-phagocytic cells. The L. monocytogenes surface protein InlB interacts with c-Met, the hepatocyte growth factor (HGF) receptor, inducing bacterial internalization in numerous non-phagocytic cells. As InlB and HGF are known to trigger similar signaling pathways upon c-Met activation, we investigated the role of CD44, and more specifically its isoform CD44v6, in bacterial internalization in non-phagocytic cells. Indeed, CD44, the hyaluronic acid transmembrane receptor, and more specifically its isoform CD44v6 have been reported as necessary for the activation of c-Met upon the interaction with either the endogenous ligand HGF or the L. monocytogenes surface protein InlB. Our results demonstrate that, in the cell lines that we used, CD44 receptors play no role in the activation of c-Met, neither during L. monocytogenes entry, nor upon HGF activation. Furthermore, none of the CD44 isoforms was recruited at the L. monocytogenes entry site, and depletion by siRNA of total CD44 or of CD44v6 isoform did not reduce bacterial infections. Conversely, the overexpression of CD44 or CD44v6 had no significant effect on L. monocytogenes internalization. Together our results reveal that the activation of c-Met can be largely CD44-independent.     

Antimalarial Exposure Delays Plasmodium falciparum Intra-Erythrocytic Cycle and Drives Drug Transporter Genes Expression

Background

Multi-drug resistant Plasmodium falciparum is a major obstacle to malaria control and is emerging as a complex phenomenon. Mechanisms of drug evasion based on the intracellular extrusion of the drug and/or modification of target proteins have been described. However, cellular mechanisms related with metabolic activity have also been seen in eukaryotic systems, e.g. cancer cells. Recent observations suggest that such mechanism may occur in P. falciparum.

Methodology/Principal Findings

We therefore investigated the effect of mefloquine exposure on the cell cycle of three P. falciparum clones (3D7, FCB, W2) with different drug susceptibilities, while investigating in parallel the expression of four genes coding for confirmed and putative drug transporters (pfcrt, pfmdr1, pfmrp1 and pfmrp2). Mefloquine induced a previously not described dose and clone dependent delay in the intra-erythrocytic cycle of the parasite. Drug impact on cell cycle progression and gene expression was then merged using a non-linear regression model to determine specific drug driven expression. This revealed a mild, but significant, mefloquine driven gene induction up to 1.5 fold.

Conclusions/Significance

Both cell cycle delay and induced gene expression represent potentially important mechanisms for parasites to escape the effect of the antimalarial drug.     

Infanticide by male house sparrows: gaining time or manipulating females?

The killing of genetically unrelated young by males has been viewed as a strategy that forces victimized females to advance the onset of their next fertile period, thus infanticidal males gain a time advantage that may be crucial to maximize reproductive success. Among females that may raise several broods in a year, a failure occurring relatively earlier in the time-course of the previous breeding attempt may result in an increased investment in the next breeding attempt. This female strategy may be exploited by males in their own interest, and may strongly select for male infanticidal behaviour. I demonstrate that, in the house sparrow, females mated with infanticidal males re-laid earlier, initiated more breeding attempts and fledged more offspring than females mated with non-infanticidal males. These results suggest that both the time saving and the manipulation of female investment are independent mechanisms conferring advantages that may have selected for male infanticide in the studied population.     

Population growth rate of the depredating Podisus nigrispinus (Heteroptera: Pentatomidae) and of the Tuta absoluta (Leptoptera: gelechiidae) in wintering place

The fertility life table of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) preying either on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) caterpillars or on alternative prey Tenebrio molitor L. (Coleoptera: Tenebrionidae) under greenhouse conditions (30 +/- 5 degrees C, 61 +/- 23% RH) were studied. The life table was also determined for the pest T. absoluta under the same conditions. The net reproductive rate (Ro) and the intrinsic rate of natural increase (rm) were higher 14.13 and 46.32 times for predators fed on T. molitor prey, however, the generation time (T) was similar between prey. The pest T. absoluta showed Ro and rm higher 2.15 and 32.10 times than those achieved for predators fed on this pest. However, females fed on a suitable prey T. molitor showed higher Ro and rm than those yielded for the pest. The survival curves were similar for P. nigrispinus females fed on both prey and classified as being type II by Weibull analysis. The results suggest that P. nigrispinus is able to maintain its population preying only on T. absoluta caterpillars; however, the life table parameters determined individually for both showed that the pest produces more generations per year and faster population natural growth than the predator.     

角质形成细胞生长因子(KGF)在喉粘膜良性、癌前及恶性病变中的mRNA水平分析

利用原位杂交的方法检测KGFmRNA在正常喉粘膜上皮（N）、慢性非特异性炎症（IF）、不典型增生（DYS）及鳞癌（SCC）中的转录水平,探讨KGF在喉粘膜良性及恶性病变中的分布和可能的作用。结果表明,KGFmRNA不仅在间质中的成纤维细胞中表达,少量的炎细胞及血管内皮细胞中亦表达,而且从N、IF、DYS到SCC、KGFmRNA转录水平逐渐增强;上皮细胞及肿瘤性上皮细胞不表达KGFmRNA,KGFmRNA在分化差的SCC周围间质中表达较分化好的SCC周围间质增多。结论：KGF在上皮与间充质细胞的交互作用中发挥着重要的作用,对维持喉粘膜正常结构、代谢及喉癌的发生发展具有重要意义。