Comparison of glycerophosphate acyltransferases from Euglena chloroplasts and microsomes

The acylation of sn-glycerol 3-phosphate is a common reaction in the pathways leading to the biosynthesis of glycerol-derived phospholipids, galactolipids, and sulfolipids. Enzymes catalyzing this reaction have been solubilized from Euglena chloroplasts, microsomes, and mitochondria (B. A. Boehler and M. L. Ernst-Fonberg (1976) Arch. Biochem. Biophys. 175, 229-235; L. V. Grobovsky, S. Hershenson, and M. L. Ernst-Fonberg (1979) FEBS Lett. 102, 261-264). Some characteristics of the reactions catalyzed by the acyl-CoA:sn-glycerol-3-phosphate O-acyltransferases (EC 2.3.1.15) solubilized from chloroplasts and microsomes of Euglena have been compared. Although the two enzymes have some common features, including stimulation by bovine serum albumin and phosphatidyl choline and sensitivity to sulfhydryl-binding reagents, they differ in their stabilities and responses to salt and glycerol. They exhibit different acyl-CoA substrate dependency curves. The proportions of monoacyl sn-glycerol-3-phosphate acyltransferase activity differ in the two solubilized enzyme preparations, and different products are produced by each of the glycerophosphate acyltransferases solubilized from chloroplasts and microsomes, respectively. Neither glycerophosphate acyltransferase will use palmitoyl- or myristoyl-acyl carrier protein (ACP) as a substrate whereas both use the corresponding CoA esters. Neither is inhibited by ACP, but the enzyme from microsomes is inhibited by CoA.     

Enhancement of aryl hydrocarbon hydroxylase activity in cultured rodent cells by X-irradiation.

X-irradiation (500 rads) was found to enhance the aryl hydrocarbon hydroxylase (AHH) activity of three cell lines. Radiation followed by induction with benz (a) anthracene (5–15 μg/ml) produced a synergistic effect on AHH. These effects were highly significant and were observed most dramatically with a hamster tumor cell line, A(T_l)Cl-3,a nd to a lesser extent in secondary hamsters embryo cells and mouse $\text{C}\text{3}\text{H}\text{/10}\text{T}\text{1}\text{2}$ CL8 cells.     

Adenylate cyclase activity in normal and leukemic human leukocytes as determined by a radioimmunoassay for cyclic AMP

Adenylate cyclase in human leukocytes is a labile enzyme easily damaged during rupture. Homogenization in a glass homogenizer in the presence of 0.25 M sucrose preceded by swelling in the slightly hypotonic media retained the cyclase activity. Other conditions such as sonication or homogenization in the absence of sucrose resulted in a variable loss of activity. The cyclase activity was determined by a radioimmunoassay which, with some modifications, proved more sensitive than the labelled ATP assay method. Adenylate cyclase from lymphocytes of patients with chronic lymphatic leukemia exhibited an altered response to prostaglandins E₁, E₂ and F_2α when compared with cyclase from normal human lymphocytes.     

Molecular systematics of the Philippine forest skinks (Squamata: Scincidae: Sphenomorphus): testing morphological hypotheses of interspecific relationships

Skinks of the genus Sphenomorphus are the most diverse clade of squamates in the Philippine Archipelago. Morphological examination of these species has defined six phenotypic groups that are commonly used in characterizations of taxonomic hypotheses. We used a molecular phylogeny based on four mitochondrial and two nuclear genes to assess the group's biogeographical history in the archipelago and examine the phylogenetic validity of the currently recognized Philippine species groups. We re‐examined traditional characters used to define species groups and used multivariate statistics to quantitatively evaluate group structure in morphometric space. Clustering analyses of phenotypic similarity indicate that some (but not all) members of previously defined species groups are phenotypically most similar to other members of the same group. However, when species group membership was mapped on our partitioned Bayesian phylogenetic hypothesis, only one species group corresponds to a clade; all other species group arrangements are strongly rejected by our phylogeny. Our results demonstrate that (1) previously recognized species group relationships were misled by phenotypic convergence; (2) Sphenomorphus is widely paraphyletic; and (3) multiple lineages have independently invaded the Philippines. Based on this new perspective on the phylogenetic relationships of Philippine Sphenomorphus, we revise the archipelago's diverse assemblage of species at the generic level, and resurrect and/or expand four previously recognized genera, and describe two new genera to accommodate the diversity of Philippine skinks of the Sphenomorphus group. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 1217–1243.     

Allotetraploid origin and divergence in Eleusine (Chloridoideae, Poaceae): evidence from low-copy nuclear gene phylogenies and a plastid gene chronogram

Background and Aims Eleusine

(Poaceae) is a small genus of the subfamily Chloridoideae exhibiting considerable morphological and ecological diversity in East Africa and the Americas. The interspecific phylogenetic relationships of Eleusine are investigated in order to identify its allotetraploid origin, and a chronogram is estimated to infer temporal relationships between palaeoenvironment changes and divergence of Eleusine in East Africa.

Methods

Two low-copy nuclear (LCN) markers, Pepc4 and EF-1α, were analysed using parsimony, likelihood and Bayesian approaches. A chronogram of Eleusine was inferred from a combined data set of six plastid DNA markers (ndhA intron, ndhF, rps16-trnK, rps16 intron, rps3, and rpl32-trnL) using the Bayesian dating method.

Key Results

The monophyly of Eleusine is strongly supported by sequence data from two LCN markers. In the cpDNA phylogeny, three tetraploid species (E. africana, E. coracana and E. kigeziensis) share a common ancestor with the E. indica–E. tristachya clade, which is considered a source of maternal parents for allotetraploids. Two homoeologous loci are isolated from three tetraploid species in the Pepc4 phylogeny, and the maternal parents receive further support. The A-type EF-1α sequences possess three characters, i.e. a large number of variations of intron 2; clade E-A distantly diverged from clade E-B and other diploid species; and seven deletions in intron 2, implying a possible derivation through a gene duplication event. The crown age of Eleusine and the allotetraploid lineage are 3·89 million years ago (mya) and 1·40 mya, respectively.

Conclusions

The molecular data support independent allotetraploid origins for E. kigeziensis and the E. africana–E. coracana clade. Both events may have involved diploids E. indica and E. tristachya as the maternal parents, but the paternal parents remain unidentified. The habitat-specific hypothesis is proposed to explain the divergence of Eleusine and its allotetraploid lineage.     

Design and coverage of high throughput genotyping arrays optimized for individuals of East Asian, African American, and Latino race/ethnicity using imputation and a novel hybrid SNP selection algorithm

Four custom Axiom genotyping arrays were designed for a genome-wide association (GWA) study of 100,000 participants from the Kaiser Permanente Research Program on Genes, Environment and Health. The array optimized for individuals of European race/ethnicity was previously described. Here we detail the development of three additional microarrays optimized for individuals of East Asian, African American, and Latino race/ethnicity. For these arrays, we decreased redundancy of high-performing SNPs to increase SNP capacity. The East Asian array was designed using greedy pairwise SNP selection. However, removing SNPs from the target set based on imputation coverage is more efficient than pairwise tagging. Therefore, we developed a novel hybrid SNP selection method for the African American and Latino arrays utilizing rounds of greedy pairwise SNP selection, followed by removal from the target set of SNPs covered by imputation. The arrays provide excellent genome-wide coverage and are valuable additions for large-scale GWA studies.     

Comparative phylogeography reveals a shared impact of pleistocene environmental change in shaping genetic diversity within nine Anopheles mosquito species across the Indo-Burma biodiversity hotspot

South-East Asia is one of the world's richest regions in terms of biodiversity. An understanding of the distribution of diversity and the factors shaping it is lacking, yet essential for identifying conservation priorities for the region's highly threatened biodiversity. Here, we take a large-scale comparative approach, combining data from nine forest-associated Anopheles mosquito species and using statistical phylogeographical methods to disentangle the effects of environmental history, species-specific ecology and random coalescent effects. Spatially explicit modelling of Pleistocene demographic history supports a common influence of environmental events in shaping the genetic diversity of all species examined, despite differences in species' mtDNA gene trees. Populations were periodically restricted to allopatric northeastern and northwestern refugia, most likely due to Pleistocene forest fragmentation. Subsequent southwards post-glacial recolonization is supported by a north-south gradient of decreasing genetic diversity. Repeated allopatric fragmentation and recolonization have led to the formation of deeply divergent geographical lineages within four species and a suture zone where these intraspecific lineages meet along the Thai-Myanmar border. A common environmental influence for this divergence was further indicated by strong support for simultaneous divergence within the same four species, dating to approximately 900 thousand years ago (kya). Differences in the geographical structuring of genetic diversity between species are probably the result of varying species' biology. The findings have important implications for conservation planning; if the refugial regions and suture zone identified here are shared by other forest taxa, the unique and high levels of genetic diversity they house will make these areas conservation priorities.     

广东省动物(昆虫)生态学三十年

本文论述了近30年来广东省昆虫生态学的发展状况及不同分支学科的研究进展,主要包括30年来的代表性事件、昆虫种群生态学、昆虫群落生态学、昆虫行为生态学、昆虫生理生态学、昆虫化学生态学和昆虫分子生态学的研究。     

华东地区归化植物的组成特征、引入时间及时空分布

归化是入侵的前期阶段, 对归化植物的深入研究是科学管理外来物种的基本前提, 有助于预防外来植物造成入侵危害, 区域性归化植物的研究对地方外来植物的管理与防治对策的制定具有重要的指导意义。本文基于文献报道、标本信息和分类学考证, 特别是于2014-2019年对华东地区(安徽省、福建省、江苏省、江西省、山东省、上海市和浙江省)归化植物的全面调查, 统计分析了华东地区归化植物的物种组成和分布格局, 并对其首次引入(或发现)地、引入时间和引入途径进行综合分析。结果表明, 华东地区有归化植物62科181属299种, 总体上呈现种类丰富、以草本植物为主、原产于美洲的种类多、引入途径集中等特征。在空间尺度上, 福建省的物种多样性明显高于其他省市, 且仅分布于该省的种类也最多(达57种, 占总种数的19.1%), 其他省市之间则差别不大。对外交流程度和原产地与归化地之间的气候相似性可能是影响归化植物多样性和空间分布格局的主要因素。在时间尺度上, 1850年之后, 华东地区的归化植物呈现出指数增长的趋势, 增长速率达1.5种/年, 且当前正处于快速增长阶段; 21世纪以来, 80%以上的归化植物来自于无意引入的物种, 这提示我们需要对此特别关注。华东地区作为对外交流的重要区域, 面临着外来植物输入以及归化并造成入侵的双重压力, 因此需对该地区的热点地区如口岸、港口等地加强出入境监管, 同时构建一套行之有效的外来植物风险评估体系, 这是开展外来物种风险管理的基础, 也是预防外来物种入侵的有效手段之一。