Symmetry perception in an insect

Symmetrical visual patterns have a salient status in human perception, as evinced by their prevalent occurrence in art, and also in animal perception, where they may be an indicator of phenotypic and genotypic quality. Symmetry perception has been demonstrated in humans, birds, dolphins and apes. Here we show that bees trained to discriminate bilaterally symmetrical from non-symmetrical patterns learn the task and transfer it appropriately to novel stimuli, thus demonstrating a capacity to detect and generalize symmetry or asymmetry. We conclude that bees, and possibly flower-visiting insects in general, can acquire a generalized preference towards symmetrical or, alternatively, asymmetrical patterns depending on experience, and that symmetry detection is preformed or can be learned as perceptual category by insects, because it can be extracted as an independent visual pattern feature. Bees show a predisposition for learning and generalized symmetry because, if trained to it, they choose it more frequently, come closer to and hover longer in front of the novel symmetrical stimuli than the bees trained for asymmetry do for the novel asymmetrical stimuli. Thus, even organisms with comparatively small nervous systems can generalize about symmetry, and favour symmetrical over asymmetrical patterns.     

DDT: The degradation of ring-labeled14C-DDT to14CO2 in the rat

Summary Ring fission ofp, p-DDT was studied in the rat following a single oral dose of 0.74 mg/kg (1.04 Ci) of uniformly ring-labeled¹⁴C-DDT. Expired air was passed through a solution of ethanolamine-ethylene glycol monomethyl ether (12) to trap¹⁴CO₂. A total of 1.6% of the radioactivity administered was recovered in the expired air collected continually for 10 days, indicating that while degradation of the phenyl moiety is not a major route pfp, p-DDT metabolism in the rat, it is equal to the urinary excretion. Nevertheless, these results represent the most radical change accomplished in vivo of a residual insecticide yet reported in mammals.Acknowledgment. We acknowledge the secretarial work of Ms.Elaine Smolko. This study was supported by NIH fellowship No. 1 F22 ES01723-01 and No. HL16264.     

毛细压力对薄液膜蒸发的影响

介绍了一个考虑毛细压力对液膜在垂直平板上蒸发影响的模型．导出了此过程的控制方程组并用可变步长的Ｒｕｎｇｅ－Ｋｕｔｔａ方法进行数值积分．数值结果与Ｎｕｓｓｅｌｔ膜冷凝理论的分析解进行比较，当液膜变得足够薄时，结果与Ｎｕｓｓｅｌｔ膜理论产生显著偏差．这可能是由于Ｎｕｓｓｅｌｔ膜理论没有考虑毛细压力对液膜形状的影响     

Estimating the proportion of variation in susceptibility to schizophrenia captured by common SNPs

Schizophrenia is a complex disorder caused by both genetic and environmental factors. Using 9,087 affected individuals, 12,171 controls and 915,354 imputed SNPs from the Schizophrenia Psychiatric Genome-Wide Association Study (GWAS) Consortium (PGC-SCZ), we estimate that 23% (s.e. = 1%) of variation in liability to schizophrenia is captured by SNPs. We show that a substantial proportion of this variation must be the result of common causal variants, that the variance explained by each chromosome is linearly related to its length (r = 0.89, P = 2.6 × 10(-8)), that the genetic basis of schizophrenia is the same in males and females, and that a disproportionate proportion of variation is attributable to a set of 2,725 genes expressed in the central nervous system (CNS; P = 7.6 × 10(-8)). These results are consistent with a polygenic genetic architecture and imply more individual SNP associations will be detected for this disease as sample size increases.     

Systematic documentation and analysis of human genetic variation in hemoglobinopathies using the microattribution approach

We developed a series of interrelated locus-specific databases to store all published and unpublished genetic variation related to hemoglobinopathies and thalassemia and implemented microattribution to encourage submission of unpublished observations of genetic variation to these public repositories. A total of 1,941 unique genetic variants in 37 genes, encoding globins and other erythroid proteins, are currently documented in these databases, with reciprocal attribution of microcitations to data contributors. Our project provides the first example of implementing microattribution to incentivise submission of all known genetic variation in a defined system. It has demonstrably increased the reporting of human variants, leading to a comprehensive online resource for systematically describing human genetic variation in the globin genes and other genes contributing to hemoglobinopathies and thalassemias. The principles established here will serve as a model for other systems and for the analysis of other common and/or complex human genetic diseases.     

Coral mucus functions as an energy carrier and particle trap in the reef ecosystem

Zooxanthellae, endosymbiotic algae of reef-building corals, substantially contribute to the high gross primary production of coral reefs, but corals exude up to half of the carbon assimilated by their zooxanthellae as mucus. Here we show that released coral mucus efficiently traps organic matter from the water column and rapidly carries energy and nutrients to the reef lagoon sediment, which acts as a biocatalytic mineralizing filter. In the Great Barrier Reef, the dominant genus of hard corals, Acropora, exudes up to 4.8 litres of mucus per square metre of reef area per day. Between 56% and 80% of this mucus dissolves in the reef water, which is filtered through the lagoon sands. Here, coral mucus is degraded at a turnover rate of at least 7% per hour. Detached undissolved mucus traps suspended particles, increasing its initial organic carbon and nitrogen content by three orders of magnitude within 2 h. Tidal currents concentrate these mucus aggregates into the lagoon, where they rapidly settle. Coral mucus provides light energy harvested by the zooxanthellae and trapped particles to the heterotrophic reef community, thereby establishing a recycling loop that supports benthic life, while reducing loss of energy and nutrients from the reef ecosystem.