Genetic uniqueness of the Waorani tribe from the Ecuadorian Amazon

South America and especially the Amazon basin is known to be home to some of the most isolated human groups in the world. Here, we report on a study of mitochondrial DNA (mtDNA) in the Waorani from Ecuador, probably the most warlike human population known to date. Seeking to look in more depth at the characterization of the genetic diversity of this Native American tribe, molecular markers from the X and Y chromosomes were also analyzed. Only three different mtDNA haplotypes were detected among the Waorani sample. One of them, assigned to Native American haplogroup A2, accounted for more than 94% of the total diversity of the maternal gene pool. Our results for sex chromosome molecular markers failed to find close genetic kinship between individuals, further emphasizing the low genetic diversity of the mtDNA. Bearing in mind the results obtained for both the analysis of the mtDNA control region and complete mitochondrial genomes, we suggest the existence of a 'Waorani-specific' mtDNA lineage. According to current knowledge on the phylogeny of haplogroup A2, we propose that this lineage could be designated as subhaplogroup A2s. Its wide predominance among the Waorani people might have been conditioned by severe genetic drift episodes resulting from founding events, long-term isolation and a traditionally small population size most likely associated with the striking ethnography of this Amazonian community. In all, the Waorani constitute a fine example of how genetic imprint may mirror ethnopsychology and sociocultural features in human populations.     

大豆分离蛋白替代鱼粉对虹鳟生长性能及氮磷排泄的影响(英文)

以体重为(4.86±0.02)g的虹鳟稚鱼为实验对象,在室内循环水养殖系统中进行为期90d的生长实验。用1000 U/kg植酸酶预处理大豆分离蛋白,然后以预处理的大豆分离蛋白(Soy protein isolate,SPI)分别替代0、20%、40%、60%、80%和100%的鱼粉蛋白,配制成6种等氮(粗蛋白为44.97%)、等能(粗脂肪为13.42%)的饲料,以评估饲料中鱼粉替代量对虹鳟生长、体组成、消化率及氮磷排泄的影响。90d的养殖实验结果表明,大豆分离蛋白替代鱼粉对虹鳟生长性能和饲料利用率产生显著的影响(P<0.05)。当大豆蛋白替代水平由0增加到40%时,虹鳟的特定生长率(SGR)显著提高,随着饲料中SPI替代水平由40%增加到100%时,虹鳟的SGR显著降低(P<0.05),在S0、S20和S60试验组之间差异不显著(P>0.05)。增重率(WGR)和蛋白质效率(PER)分别在处理组之间的差异关系与特定生长率(SGR)在各组之间的变化趋势相类似;当大豆蛋白分别替代40%时,其饲料系数(FCR)显著低于其他替代组(P<0.05),当替代量超过40%后,随着替代水平的增加,FCR显著增加(P<0.05)。随着替代水平由0升高到100%,磷排泄显著降低,与之相反的是,磷沉积率显著升高。随着替代水平由0升高至40%,氮排泄逐渐降低,当替代水平由40%升高至100%,氮排泄逐渐升高,随着替代水平升高至40%,氮沉积率升高。试验证明,大豆分离蛋白替代量达到40%时,虹鳟的生长及饲料转化率达到最佳,而高比例的SPI对虹鳟的生长性能和饲料效率产生负面影响。     

The activity of antimicrobial peptide S-thanatin is independent on multidrug-resistant spectrum of bacteria

In this study, the activity of S-thanatin (an analog of antimicrobial peptide derived from thanatin) against different bacterial pathogens frequently which can cause therapeutic problems was tested. The result showed minimal inhibitory concentrations (MICs) of S-thanatin against all isolates of the Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Klebsiella ornithinolytica and Klebsiella oxytoca were in the range of 4-16 μg/ml, no matter which antibiotic the bacterial was resistant or susceptible, while almost all MICs to Gram-positive bacterial were >128 μg/ml except Enterococcus faecium. S-thanatin was more effective toward Gram-negative strains, especially for Enterobacter and Klebsiella. The MICs of S-thanatin were no significantly different in the same species regardless of antibiotic sensitive or -resistant isolates to single or multiple antibiotic (P > 0.05). Likewise, no notable difference could be observed between E. coli, K. pneumoniae, E. cloacae, E. aerogenes, K. ornithinolytica which were sensitive to S-thanatin (P > 0.05). It was implied that the antimicrobial activity of S-thanatin was independent on multi-drug resistance spectrum of bacteria.     

The decoupling between genetic structure and metabolic phenotypes in Escherichia coli leads to continuous phenotypic diversity

To assess the extent of intra-species diversity and the links between phylogeny, lifestyle (habitat and pathogenicity) and phenotype, we assayed the growth yield on 95 carbon sources of 168 Escherichia strains. We also correlated the growth capacities of 14 E. coli strains with the presence/absence of enzyme-coding genes. Globally, we found that the genetic distance, based on multilocus sequence typing data, was a weak indicator of the metabolic phenotypic distance. Besides, lifestyle and phylogroup had almost no impact on the growth yield of non-Shigella E. coli strains. In these strains, the presence/absence of the metabolic pathways, which was linked to the phylogeny, explained most of the growth capacities. However, few discrepancies blurred the link between metabolic phenotypic distance and metabolic pathway distance. This study shows that a prokaryotic species structured into well-defined genetic and lifestyle groups can yet exhibit continuous phenotypic diversity, possibly caused by gene regulatory effects.     

Biology,Epidemiology and Management of the Pathogenic Fungus Macrophomina phaseolina (Tassi) Goid with Special Reference to Charcoal Rot of Soybean (Glycine max (L.) Merrill)

The fungus Macrophomina phaseolina is a causative agent of diseases in more than 500 plant species. The fungus is primarily soil‐inhabiting but is also seed‐borne in many crops including soybean. It survives in the soil mainly as microsclerotia that germinate repeatedly during the crop‐growing season. Low C : N ratio in the soil and high bulk density as well as high soil moisture content adversely affect the survival of sclerotia. The disease can be managed to some extent by cultural practices, organic amendments, seed treatment and genetic host resistance. The scattered literature on these aspects is reviewed in this paper.     

Temperature influences the expression of resistance of soybean (Glycine max) to the soybean aphid (Aphis glycines)

Resistance of plants to arthropods may be lost at low or high temperatures. I tested whether the relative resistance of five genotypes of soybean, Glycine max (L.) Merr., to three isolates of the soybean aphid, Aphis glycines Matsumura, was influenced by three temperatures, 14, 21 and 28°C, in no‐choice tests in the laboratory. The interaction between temperature and the genotype of soybean influenced the population sizes of two isolates of A. glycines. Two genotypes of soybean, LD05‐16611 and PI 567597C, which usually are resistant to isolate 1 and 3, became susceptible: LD05‐16611 at the low temperature and PI 567597C at the high temperature. The genotypes PI 200538 and PI 567541B usually are susceptible to isolate 3 but were resistant at 21 and 28°C. I can only speculate as to the reason why temperature influences resistance of some genotypes of soybean to A. glycines: A. glycines may be directly influenced by temperature or indirectly influenced by changes in the host plant. Nevertheless, my results suggest that temperature may be one factor that influences the expression of resistance of soybean to A. glycines, so genotypes of soybean should be screened for resistance to the aphid at multiple temperatures.     

Genome-based phylogeny of dsDNA viruses by a novel alignment-free method

Sequence alignment is not directly applicable to whole genome phylogeny since several events such as rearrangements make full length alignments impossible. Here, a novel alignment-free method derived from the standpoint of information theory is proposed and used to construct the whole-genome phylogeny for a population of viruses from 13 viral families comprising 218 dsDNA viruses. The method is based on information correlation (IC) and partial information correlation (PIC). We observe that (i) the IC-PIC tree segregates the population into clades, the membership of each is remarkably consistent with biologist's systematics only with little exceptions; (ii) the IC-PIC tree reveals potential evolutionary relationships among some viral families; and (iii) the IC-PIC tree predicts the taxonomic positions of certain “unclassified” viruses. Our approach provides a new way for recovering the phylogeny of viruses, and has practical applications in developing alignment-free methods for sequence classification.     

一株阿尔泰虫草内生菌的分离及抑菌活性

目的:从采自阿尔泰山脉的虫[ Ophiocordyceps gracilis( Grev.)G.H Sung,J.M.Sung,Hywel- Jones&Spatafora]体内分离出1株出现频率较高的真菌(命名为SFY00C3)进行了研究.方法:经形态学和ITS序列分析鉴定,对SFY00C3菌株及其发酵液采用滤纸片法,同时对6种供试菌株不同程度进行了抑制作用的研究.结果:SFY00C3菌株为青霉属(Penicillium)真菌变灰青霉(Penicillium canescens);对大肠杆菌和金黄色葡萄球菌的抑制作用较强,抑菌圈均大于10 mm.结论:虫草内生菌变灰青霉的抑菌活性成分值得进一步研究,为研究新的天然产物抑菌药物提供思路.     

Nitrogen fixation in tomato (Lycopersicon esculentum Mill ‘Pusa Ruby’)

Nitrogen fixation (acetylene reduction) was found in intact tomato (Lycopersicon esculentum Mill ‘Pusa Ruby’) plants in the field, in pots and also in aseptic cultures. The unsterilized as well as sterilized rhizoplane and phylloplane of the plant when assayed separately also responded to the test. From root bits of tomato sterilized upto 20 minutes with 0.1% mercuric chloride, growth of the bacterium from the interior of the root into the medium was observed thereby indicating their presence within the endorhizosphere. Phase contrast and electron microscopic studies of the root system of tomato revealed the presence of bacterial colonies in the epidermis, cortex and vascular bundles. Bacterial numbers in the endosphere, of root and leaf were 30×10⁴ and 12×10⁴, respectively, per gram fresh weight of tissue. The bacteria were predominantly rod-shaped 1.4–4.8×0.9–1.95 μm in 24-h-old cultures, pleomorphic, polar or bipolary flagellated having β-hydroxy butyrate granules. The bacterium has been identified as a new species of Azospirillum.     

Demonstration of formaldehyde dehydrogenase activity in formaldehyde-resistant Enterobacteriaceae

Clinical isolates of different Enterobacteriaceae strains and genetically modified variants which were resistant to the disinfectant formaldehyde were investigated. In cell-free extracts of all formaldehyde-resistant strains a glutathione-dependent formaldehyde dehydrogenase activity was demonstrated. In contrast cell extracts from formaldehyde sensitive strains did not show any formaldehyde dehydrogenase activity. The enzymatic degradation of formaldehyde seems to play an important role in formaldehyde resistance.