Whole-arm reciprocal translocation (WART) between Robertsonian chromosomes: finding of a Robertsonian heterozygous mouse with karyotype derived through WARTs

The karyotype of a mouse trapped in a hybrid zone between a Robertsonian (Rb) population (2n=22) and a population with the standard karyotype (2n=40-all-telocentrics) shows two Rb chromosomes with new arm compositions. We suggest that whole-arm reciprocal translocations between Rb chromosomes gave rise to the new chromosome constitution and that such events can greatly help in understanding house mouse karyotype diversification and chromosomal speciation.     

高效液相色谱-电感耦合等离子体质谱法测定海鱼中无机砷

目的建立测定海鱼中无机砷含量的高效液相色谱-电感耦合等离子体质谱法。方法海鱼样品经稀硝酸超声热水浴提取后,AS7阴离子交换色谱柱分离,3.5 mmol/L(NH4)2CO3+1%甲醇与100 mmol/L(NH4)2CO3+1%甲醇流动相梯度洗脱,电感耦合等离子体质谱仪测定,以保留时间定性,外标法定量。结果在1~100μg/L的线性范围,6种砷形态化合物的回归方程均呈良好的线性关系,相关系数均优于0.9996,检出限为0.05~0.25μg/L,定量限为0.17~0.84μg/L,3个浓度加标回收率为88.5%~106.4%,相对标准偏差为2.5%~4.9%。结论本方法满足海鱼中无机砷含量的测定要求,提取快速,稳定,操作简单,检出限低,方法的重现性好,灵敏度高。     

A test of the chromosomal theory of ecotypic speciation in Anopheles gambiae

The role of chromosomal inversions in speciation has long been of interest to evolutionists. Recent quantitative modeling has stimulated reconsideration of previous conceptual models for chromosomal speciation. Anopheles gambiae, the most important vector of human malaria, carries abundant chromosomal inversion polymorphism nonrandomly associated with ecotypes that mate assortatively. Here, we consider the potential role of paracentric inversions in promoting speciation in A. gambiae via "ecotypification," a term that refers to differentiation arising from local adaptation. In particular, we focus on the Bamako form, an ecotype characterized by low inversion polymorphism and fixation of an inversion, 2Rj, that is very rare or absent in all other forms of A. gambiae. The Bamako form has a restricted distribution by the upper Niger River and its tributaries that is associated with a distinctive type of larval habitat, laterite rock pools, hypothesized to be its optimal breeding site. We first present computer simulations to investigate whether the population dynamics of A. gambiae are consistent with chromosomal speciation by ecotypification. The models are parameterized using field observations on the various forms of A. gambiae that exist in Mali, West Africa. We then report on the distribution of larvae of this species collected from rock pools and more characteristic breeding sites nearby. Both the simulations and field observations support the thesis that speciation by ecotypification is occurring, or has occurred, prompting consideration of Bamako as an independent species.     

Selenium Cycling Across Soil-Plant-Atmosphere Interfaces: A Critical Review

Selenium (Se) is an essential element for humans and animals, which occurs ubiquitously in the environment. It is present in trace amounts in both organic and inorganic forms in marine and freshwater systems, soils, biomass and in the atmosphere. Low Se levels in certain terrestrial environments have resulted in Se deficiency in humans, while elevated Se levels in waters and soils can be toxic and result in the death of aquatic wildlife and other animals. Human dietary Se intake is largely governed by Se concentrations in plants, which are controlled by root uptake of Se as a function of soil Se concentrations, speciation and bioavailability. In addition, plants and microorganisms can biomethylate Se, which can result in a loss of Se to the atmosphere. The mobilization of Se across soil-plant-atmosphere interfaces is thus of crucial importance for human Se status. This review gives an overview of current knowledge on Se cycling with a specific focus on soil-plant-atmosphere interfaces. Sources, speciation and mobility of Se in soils and plants will be discussed as well as Se hyperaccumulation by plants, biofortification and biomethylation. Future research on Se cycling in the environment is essential to minimize the adverse health effects associated with unsafe environmental Se levels.     

Genetic and Neural Bases for Species-Specific Behavior in Drosophila Species

Abstract

Behavioral changes in evolution have attracted the attention of many evolutionary biologists. Closely related species, or even individuals from different populations within a species, often exhibit remarkably different behaviors. Such behavioral diversification has been implicated as a cause of speciation in some cases, yet the mechanisms that produce and maintain these changes remain largely unknown. Drosophila melanogaster, an outstanding model organism with which to explore the causal link among the gene, neural circuitry, and behavior, provides an excellent entry point for a comparative approach to the origin of behavioral diversification with a single-gene and single-cell resolution. Here we survey studies that attempted to reveal the mechanistic bases for behavioral changes potentially associated with speciation, and we discuss the successfully identified candidate genes or neurons involved in such events. Although evolutionary developmental biology (evo-devo), a field devoted to the developmental and molecular basis of phenotypic diversity, has mostly been focused on morphological traits, the extension of this evo-devo approach to behavioral diversity will provide a comprehensive understanding of the genome-environment interactions underlying adaptive evolution.     

The interplay between chemical speciation and physiology determines the bioaccumulation and toxicity of Cu(II) and Cd(II) to Caenorhabditis elegans

Using the well‐documented model organism Caenorhabditis elegans, a combined analysis of metal speciation in the exposure medium and body burdens of metals (Zn, Cu and Cd) was performed, and factors that are predictive of toxicological endpoints in single metal and mixed metal exposures were identified. Cu, and to a lesser extent Cd, is found to associate with Escherichia coli in the exposure medium (the food source for C. elegans) as evidenced by the observed decrease in both their dissolved and free metal ion concentrations. Together with a critical analysis of literature data, our results suggest that free metal ion concentrations and thus aqueous uptake routes are the best predictor of internal concentrations under all conditions considered, and of metal toxicity in single metal exposures. Additional factors are involved in determining the toxicity of metal mixtures. In general, the eventual adverse effects of metals on biota are expected to be a consequence of the interplay between chemical speciation in the exposure medium, timescale of exposure, exposure route as well as the nature and timescale of the biotic handling pathways.     

The XY gene hypothesis of psychosis: Origins and current status

Sex differences in psychosis and their interaction with laterality (systematic departures from 50:50 left‐right symmetry across the antero‐posterior neural axis) are reviewed in the context of the X‐Y gene hypothesis. Aspects of laterality (handedness/cerebral asymmetry/the torque) predict (1) verbal and non‐verbal ability in childhood and across adult life and (2) anatomical, physiological, and linguistic variation relating to psychosis. Neuropsychological and MRI evidence from individuals with sex chromosome aneuploidies indicates that laterality is associated with an X‐Y homologous gene pair. Within each mammalian species the complement of such X‐Y gene pairs reflects their potential to account for taxon‐specific sexual dimorphisms. As a consequence of the mechanism of meiotic suppression of unpaired chromosomes <MSUC> such X‐Y gene pairs generate epigenetic variation around a species defining motif that is carried to the zygote with potential to initiate embryonic gene expression in XX or XY format. The Protocadherin11XY (PCDH11XY) gene pair in Xq21.3/Yp11.2 in probable coordination with a gene or genes within PAR2 (the second pseudo‐autosomal region) is the prime candidate in relation to cerebral asymmetry and psychosis in Homo sapiens. The lately‐described pattern of sequence variation associated with psychosis on the autosomes may reflect a component of the human genome's adjustment to selective pressures generated by the sexually dimorphic mate recognition system. © 2013 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics Published by John Wiley and Sons, Ltd.     

冬虫夏草中砷及其安全性评价研究进展

传统名贵中药冬虫夏草Cordyceps sinensis中砷超标及其安全性问题近年来备受关注,针对冬虫夏草中砷的研究逐渐增加并不断深入。在文献查阅的基础上,从冬虫夏草砷及砷形态的分析方法,砷的含量、分布、存在形态,安全性评价,以及野生和人工仿生繁育冬虫夏草中砷含量等方面进行归纳总结,并对冬虫夏草中砷的认知及研究进行展望,以期为冬虫夏草安全性评价的深入研究提供参考。