Temperature‐correlated shifts in the timing of egg‐laying in House Finches Haemorhous mexicanus

Although temperature‐correlated shifts in the timing of egg‐laying have been documented in numerous bird species, the vast majority of species examined to date have been those that breed in Europe and have an animal‐based diet during breeding. However, given that the timing of breeding can be driven, either in the proximate or in the ultimate sense, by seasonal fluctuations in food availability, the relationship between temperature and laying may differ with diet. Here, we report on patterns of reproductive timing in House Finches Haemorhous mexicanus, a North American species that breeds on a primarily seed‐based diet. Analysing nest records from House Finches in California spanning more than a century, we found that egg‐laying occurred significantly earlier in warmer springs. We also found that although the timing of egg‐laying does not show long‐term changes in most of California, in the hottest region of the state (the southeast desert basin) it has advanced significantly.     

Synthesis and structure-activity relationships of retro bis-aminopyrrolidine urea (rAPU) derived small-molecule antagonists of the melanin-concentrating hormone receptor-1 (MCH-R1). Part 1

The design, synthesis, and SAR of a series of retro bis-aminopyrrolidine ureas are described. Compounds from this series exhibited potent binding affinity and functional activity at MCH-R1, and good oral bioavailability in rat.     

中国西南虎跳峡地区云南松林土壤侵蚀控制潜能(英文)

 作为中国西南长江上游众多峡谷、深谷的典型代表,虎跳峡地区的土壤侵蚀是一个严重的环境问题。为了解决侵蚀问题,大面积的适宜荒山已经植树造林。云南松是运用最广的造林树种之一。本研究试图以虎跳峡地区1993年的情况为例,探讨云南松林土壤侵蚀控制的水文效应及其潜能。研究发现,云南松密林能够截留31.1％的降雨量。林下的土壤溅蚀量(4.9kg·m-2)比裸地上的(6.1kg·m-2)降低了19.7％。松林内的土壤流失总量与裸地的57.9g·m-2比较,降低到32.9g·m-2,表明松林减少了43.19％的土壤流失。实验指出,降雨强度对这里的土壤流失,以及云南松林的侵蚀控制作用有明显的影响。另一方面,研究也发现松林能够产生较大直径的叶滴,引起林下的叶滴溅蚀;而且,松林并不能明显地减少地表径流。然而,从综合作用来看,云南松密林具有土壤侵蚀控制的净效应。与茂密的草丛相比,松林侵蚀控制的效果相对较低。     

Bergmann's rule is maintained during a rapid range expansion in a damselfly

Climate‐induced range shifts result in the movement of a sample of genotypes from source populations to new regions. The phenotypic consequences of those shifts depend upon the sample characteristics of the dispersive genotypes, which may act to either constrain or promote phenotypic divergence, and the degree to which plasticity influences the genotype–environment interaction. We sampled populations of the damselfly Erythromma viridulum from northern Europe to quantify the phenotypic (latitude–body size relationship based on seven morphological traits) and genetic (variation at microsatellite loci) patterns that occur during a range expansion itself. We find a weak spatial genetic structure that is indicative of high gene flow during a rapid range expansion. Despite the potentially homogenizing effect of high gene flow, however, there is extensive phenotypic variation among samples along the invasion route that manifests as a strong, positive correlation between latitude and body size consistent with Bergmann's rule. This positive correlation cannot be explained by variation in the length of larval development (voltinism). While the adaptive significance of latitudinal variation in body size remains obscure, geographical patterns in body size in odonates are apparently underpinned by phenotypic plasticity and this permits a response to one or more environmental correlates of latitude during a range expansion.     

Intracellular signaling specificity in response to uniaxial vs. multiaxial stretch: implications for mechanotransduction

Several lines of evidence suggest that muscle cells can distinguish between specific mechanical stimuli. To test this concept, we subjected C₂C₁₂ myotubes to cyclic uniaxial or multiaxial stretch. Both types of stretch induced an increase in extracellular signal-regulated kinase (ERK) and protein kinase B (PKB/Akt) phosphorylation, but only multiaxial stretch induced ribosomal S6 kinase (p70^S6k) phosphorylation. Further results demonstrated that the signaling events specific to multiaxial stretch (p70^S6k phosphorylation) were elicited by forces delivered through the elastic culture membrane and were not due to greater surface area deformations or localized regions of large tensile strain. Experiments performed using medium that was conditioned by multiaxial stretched myotubes indicated that a release of paracrine factors was not sufficient for the induction of signaling to p70^S6k. Furthermore, incubation with gadolinium(III) chloride (500 µM), genistein (250 µM), PD-98059 (250 µM), bisindolylmaleimide I (20 µM), or LY-294002 (100 µM ) did not block the multiaxial stretch-induced signaling to p70^S6k. However, disrupting the actin cytoskeleton with cytochalasin D did block the multiaxial signaling to p70^S6k, with no effect on signaling to PKB/Akt. These results demonstrate that specific types of mechanical stretch activate distinct signaling pathways, and we propose that this occurs through direct mechanosensory-mechanotransduction mechanisms and not through previously defined growth factor/receptor binding pathways. growth; hypertrophy; muscle; strain; tension     

The effect of proflavine on HeLa cells

1. The effect of proflavine on the metabolism of RNA, DNA and protein of HeLa cells was studied. 2. The synthesis of RNA, DNA and protein was progressively inhibited by concentrations of proflavine up to 43mum. 3. There was no simple relationship between the degrees of inhibition of synthesis of RNA, DNA and protein by increasing concentrations of proflavine: the synthesis of RNA was most readily inhibited, and the synthesis of protein was relatively insensitive. 4. A concentration of 22mum-proflavine inhibited synthesis of RNA and DNA and caused a progressive loss of RNA from both nucleus and cytoplasm without any accompanying loss of DNA or dry weight from the cells. 5. The rapidly labelled RNA in the nucleus was preferentially degraded and was not transferred in a stable form to the cytoplasm.     

Comparison of Clark's presence-absence test and the membrane filter method for coliform detection in potable water samples

A total of 2,601 water samples from six different water systems were tested for coliform bacteria by Clark's presence-absence (P-A) test and by the membrane filter (MF) method. There was no significant difference in the fraction of samples positive for coliform bacteria for any of the systems tested. It was concluded that the two tests are equivalent for monitoring purposes. However, 152 samples were positive for coliform bacteria by the MF method but negative by the P-A test, and 132 samples were positive by the P-A test but negative by the MF method. Many of these differences for individual samples can be explained by random dispersion of bacteria in subsamples when the coliform density is low. However, 15 samples had MF counts greater than 3 and gave negative P-A results. The only apparent explanation for most of these results is that coliform bacteria were present in the P-A test bottles but did not produce acid and gas. Two other studies have reported more samples positive by Clark's P-A test than by the MF method.     

The influence of natural variation at the <Emphasis Type="Italic">foraging</Emphasis> gene on thermotolerance in adult <Emphasis Type="Italic">Drosophila</Emphasis> in a narrow temperature range

Poikilothermic organisms such as insects have mechanisms to protect neural function under high temperature stress. Natural variation at the foraging (for) locus of the fruit fly, Drosophila melanogaster, encoding a cGMP-dependent protein kinase (PKG), influences neural thermotolerance in Drosophila larvae. The current study re-examines thermotolerance of adult flies to account for inconsistencies in the documented role of for during hyperthermia. We found that adult for ^R (rover) flies with high PKG activity were incapacitated faster under hyperthermic conditions of 39°C compared to their lower PKG activity counterparts for ^s and for ^s2 (sitters), but not at higher temperatures. This indicates that lowered PKG activity promotes tolerance to heat stress, and that the for gene influences thermotolerance for a narrow range of temperatures in adult flies.