Colony fission affects kinship in a social insect

Establishment of new groups is an important step in the life history of a social species. Fissioning is a common mode not only in group proliferation, for instance, as a regular part of the life cycle in the honey bee, but also when multiple females reproduce in the same group, as in multiple-queen ant societies. We studied the genetic consequences of fissioning in the ant Proformica longiseta, based on DNA microsatellites. In P. longiseta, new nests arise by fissioning from the old ones when they grow large, and the daughter nests consist of workers and queens or queen pupae but never both. Our results show that fissioning is not entirely random with respect to kinship. Workers tend to segregate along kin lines, but only when the initial relatedness in the parental nests is low. Workers in a daughter nest also tend to be associated with closely related adult queens, whereas such an association is not detected between workers and queen pupae. Most queens and workers are carried to the daughter nest by a specialized group of transporting workers, suggesting active kin discrimination by them. Fissioning pattern in P. longiseta is different from that found in other social insects with regular fission (e.g., the honey bee, swarm-founding wasps), where no fissioning along kin lines has been found. It does, however, resemble fissioning in another group of social animals: primates.     

硫化镉量子点与常规硫化镉对小鼠遗传毒性的比较研究

为比较硫化镉量子点(CdS quantum dots,CdSQDs)与常规硫化镉(CdS)对小鼠的遗传毒性作用,将30只昆明种健康雄性小鼠随机分为对照组、CdSQDs组和常规CdS组,通过经口灌胃法进行染毒,其中CdSQDs组和常规CdS组染毒剂量为100mg·kg-1,对照组为等体积的生理盐水.染毒35d后将小鼠处死,通过单细胞凝胶电泳观察外周血淋巴细胞DNA损伤情况,取小鼠一侧附睾观察精子畸形率,并取双侧肾脏做组织病理学检验.结果表明,与对照组小鼠比较,CdSQDs组和常规CdS组小鼠DNA损伤和精子畸形率均显著升高(p<0.05);CdSQDs组小鼠DNA损伤程度及精子畸形率均显著低于常规CdS组(p<0.05);组织病理切片观察显示,两种材料均可引起小鼠肾脏病变,但CdSQDs组小鼠病变程度明显轻于常规CdS组.以上结果提示,CdSQDs和常规CdS均会对小鼠产生一定程度的遗传毒性作用,但CdSQDs毒性低于相同剂量的常规CdS.     

Use of carrion fly iDNA metabarcoding to monitor invasive and native mammals

Severely fragmented habitats increase the risk of extirpation of native mammal populations through isolation, increased edge effects, and predation. Therefore, monitoring the movement of mammal populations through anthropogenically altered landscapes can inform conservation. We used metabarcoding of invertebrate-derived DNA (iDNA) from carrion flies (Calliphoridae and Sarcophagidae) to track mammal populations in the wheat belt of southwestern Australia, where widespread clearing for agriculture has removed most of the native perennial vegetation and replaced it with an agricultural system. We investigated whether the localization of the iDNA signal reflected the predicted distribution of 4 native species—echidna (Tachyglossus aculeatus), numbat (Myrmecobius fasciatus), woylie (Bettongia penicillata), and chuditch (Dasyurus geoffroii)—and 2 non-native, invasive mammal species—fox (Vulpes vulpes) and feral cat (Felis catus). We collected bulk iDNA samples (n = 150 samples from 3428 carrion flies) at 3 time points from 3 conservation reserves and 35 road edges between them. We detected 14 of the 40 mammal species known from the region, including our target species. Most detections of target taxa were in conservation reserves. There were a few detections from road edges. We detected foxes and feral cats throughout the study area, including all conservation reserves. There was a significant difference between the diversity (F_3, 98 = 5.91, p < 0.001) and composition (F_3, 43 = 1.72, p < 0.01) of taxa detections on road edges and conservation reserves. Conservation reserves hosted more native biodiversity than road edges. Our results suggest that the signals from iDNA reflect the known distribution of target mammals in this region. The development of iDNA methods shows promise for future noninvasive monitoring of mammals. With further development, iDNA metabarcoding could inform decision-making related to conservation of endangered taxa, invasive species management, and impacts of habitat fragmentation.     

The European land leech: biology and DNA-based taxonomy of a rare species that is threatened by climate warming

The European land leech Xerobdella lecomtei was discovered in 1868 and is one of the rarest animals on Earth. During the 1960s, several individuals of these approx. 40 mm long, cold-adapted terrestrial annelids that inhabit the moist soils of birch forests around Graz, Austria, were investigated. Only one original research paper has been published on the biology of this species. Between 2001 and 2005, we re-investigated the morphology of preserved specimens and searched for living individuals in their natural habitat that appeared to be intact. We found only one juvenile individual (length approx. 10 mm), indicating that this local leech population became largely extinct over the past four decades. The feeding behaviour of our ‘lonesome George of the annelids’ was studied and is described here in detail. After its death, the Xerobdella individual was used for chemical extraction and molecular studies (deoxyribonucleic acid [DNA] barcoding, based on one gene, the mitochondrial cytochrome c oxidase subunit I). In addition, novel DNA barcodes for a land leech from Madagascar and a recently discovered species from Europe were obtained. Our phylogenetic tree shows that X. lecomtei is not a member of the tropical land leeches (family Haemadipsidae), as previously thought, but represents a separate line of descent (family Xerobdellidae). The decline of the local leech population around Graz correlates with a rise in average summer temperatures of +3°C between 1961 and 2004. This warming led to a drastic reduction in the moisture content of the soil where X. lecomtei lives. We suggest that human-induced climate change without apparent habitat destruction can lead to the extinction of populations of cold-adapted species that have a low colonization ability.     

环境污染条件下生物体内DNA损伤的生物标记物研究进展

在正常条件下生物体内的基因组是稳定的;但在环境污染条件下,其DNA容易遭受伤害,主要损伤形式为:碱基改变、脱碱基位点、碱基错配、插入或缺失片段、嘧啶联合、DNA加合物、DNA链断裂、甲基化损伤、DNA链内和链间交联等. 这些受损的DNA对生物细胞产生遗传毒性或细胞毒性. 利用生物标记物进行DNA损伤的检测和定量分析是可行的方法. 本文重点介绍了一些典型的DNA损伤(如DNA加合物、断裂、DNA序列改变等)的生物标记物及其检测方法;认为这些生物标记物在环境污染物的早期诊断和评价方面具有广阔的应用前景. 参32     

In vitro methylation of DNA by the fumigant methyl bromide

Abstract

Investigations have shown that the physical state of the DNA strongly influences the pattern of methylation observed when DNA or a substance containing DNA is treated with the fumigant methyl bromide. 1‐Methyl‐adenine and 7‐methylguanine were identified, after hydrolysis, as the major methylated bases of DNA which had been treated in the solid state. 3‐Methylcytosine, 3‐methyladenine and 7‐methyladenine were found as minor products. The overall methylation pattern was similar to that observed earlier for DNA of maize and wheat which had been fumigated. In contrast, when buffer solutions of DNA were treated with methyl bromide, the N‐7 position of guanine was the major site and the N‐3 position of adenine was the second most important site of methylation. This result corresponds to that previously observed in similar studies with buffer solutions of DNA and other methylating agents.     

A_2型高粱细胞质雄性不育系与其保持系的胞质DNA和核DNA差异

以高粱细胞质雄性不育系A2 V4 (A)及其保持系V4 (B)的总DNA为模板 ,对 184个随机引物进行筛选 ,找到6个其RAPD扩增产物在A/B间存在稳定差异的引物 .将该 6个引物同时扩增A/B的总DNA、线粒体DNA(mtDNA)及叶绿体DNA(cpDNA) .以总DNA为模板时得到 12个扩增片段 ,以mtDNA为模板时得到 4个 ,以cpDNA为模板时得到 11个 .结果分析表明 ,在这些扩增片段中 ,有 7个仅仅出现在以胞质DNA为模板的扩增中 ,有 5个在以总DNA和胞质DNA为模板时同时出现 ,即认为这 12个片段来自胞质DNA .另有 7个片段 ,在以胞质DNA为模板时未出现 ,而是仅仅出现在以总DNA为模板的扩增中 ,认为是来自核DNA .来自核DNA的 7个扩增片段中 ,有 5个来自保持系 ,有 2个来自不育系 ,这表明 ,不育系与保持系在核DNA上存在差异 .对A/B核DNA在CMS中的重要性及研究对策进行了讨论 .图 2表 4参 19     

萘降解质粒pND6的分离和鉴定

从工业废水中分离的假单胞菌 (Pseudomonassp .)ND6菌株 ,能以萘为唯一碳源生长 ,使无机盐培养基(MM)中 2g/L的萘在 48h内降解 98% .该菌株含有一个 115kb的大质粒pND6 .DNA杂交实验表明 ,pND6质粒含有与恶臭假单胞菌 (P .putida)G7菌株的NAH7质粒同源的萘降解基因 .图 3表 1参 14     

Plant diversity reduces the effect of multiple heavy metal pollution on soil enzyme activities and microbial community structure

It is unclear whether certain plant species and plant diversity could reduce the impacts of multiple heavy metal pollution on soil microbial structure and soil enzyme activities. Random amplified polymorphic DNA (RAPD) was used to analyze the genetic diversity and microbial similarity in planted and unplanted soil under combined cadmium (Cd) and lead (Pb) pollution. A metal hyperaccumulator, Brassica juncea, and a common plant, Festuca arundinacea Schreb, were used in this research. The results showed that microorganism quantity in planted soil significantly increased, compared with that in unplanted soil with Cd and Pb pollution. The order of microbial community sensitivity in response to Cd and Pb stress was as follows: actinomycetes>bacteria>fungi. Respiration, phosphatase, urease and dehydrogenase activity were significantly inhibited due to Cd and Pb stress. Compared with unplanted soil, planted soils have frequently been reported to have higher rates of microbial activity due to the presence of additional surfaces for microbial colonization and organic compounds released by the plant roots. Two coexisting plants could increase microbe population and the activity of phosphatases, dehydrogenases and, in particular, ureases. Soil enzyme activity was higher in B. juncea phytoremediated soil than in F. arundinacea planted soil in this study. Heavy metal pollution decreased the richness of the soil microbial community, but plant diversity increased DNA sequence diversity and maintained DNA sequence diversity at high levels. The genetic polymorphism under heavy metal stress was higher in B. juncea phytoremediated soil than in F. arundinacea planted soil.     

Genetic mating system and timing of extra-pair fertilizations in the Kentish plover

It is still unclear why females in many bird species pursue extra-pair copulations. Current hypotheses focus mainly on indirect benefits such as obtaining particular good genes for their offspring or maximizing genetic compatibility between themselves and the father of their offspring. Supporting the latter, a recent study of shorebirds suggests that extra-pair matings may function to avoid the negative effects of genetic similarity between mates. Here, we further investigate genetic parentage in the Kentish plover, Charadrius alexandrinus, a shorebird with a highly variable social mating system. DNA fingerprinting revealed that most pairs were genetically monogamous: 7.9% of the broods (7/89) contained extra-pair young, comprising 3.9% of all chicks (9/229). These cases represented, however, three alternative reproductive behaviors: extra-pair paternity, quasi-parasitism (extra-pair maternity) and intraspecific brood parasitism. This is the first study showing the occurrence of all three behaviors in one shorebird species. We also found that extra-pair fertilizations (extra-pair paternity and quasi-parasitism) were more frequent later in the breeding season. There was no consistent relationship between genetic similarity of mates and laying date; the pattern, as well as the degree of genetic similarity, differed among breeding sites within the study population.Communicated by M. Webster