Neotropical Africanized honey bees have African mitochondrial DNA

Non-indigenous African honey bees have invaded most of South and Central America in just over 30 years. The genetic composition of this population and the means by which it rapidly colonizes new territory remain controversial. In particular, it has been unclear whether this 'Africanized' population has resulted from interbreeding between African and domestic European bees, or is an essentially pure African population. Also, it has not been known whether this population expanded primarily by female or by male migration. Restriction site mapping of 62 mitochondrial DNAs of African bees from Brazil, Venezuela and Mexico reveals that 97% were of African (Apis mellifera scutellata) type. Although neotropical European apiary populations are rapidly Africanized by mating with neotropical African males, there is little reciprocal gene flow to the neotropical African population through European females. These are the first genetic data to indicate that the neotropical African population could be expanding its range by female migration.     

蜜蜂生物节律研究进展

 生物节律主要指有机体生命活动的内在节律性。蜜蜂生物节律受到其社会性的影响,从而参与许多复杂行为的调控。与果蝇相比,蜜蜂的生物节律与哺乳动物更相似。工蜂和蜂王的生物节律表现出高度的可塑性。例如,工蜂的昼夜节律受其劳动分工形式的调控,并通过与幼蜂的直接接触来调节,哺育蜂昼夜照料幼虫,在行为或时钟基因表达方面没有昼夜节律变化。从蜜蜂的社会性、蜜蜂生物节律产生的分子机制、神经基础、研究方法、可塑性、蜜蜂的睡眠等方面综述了蜜蜂生物节律的研究进展。     

Genetic evidence against panmixia in the European eel

The panmixia hypothesis--that all European eel (Anguilla anguilla) migrate to the Sargasso Sea for reproduction and comprise a single, randomly mating population--is widely accepted. If true, then this peculiar life history strategy would directly impact the population genetics of this species, and eels from European and north African rivers should belong to the same breeding population through the random dispersal of larvae. To date, the panmixia hypothesis has remained unchallenged: genetic studies realized on eel's mitochondrial DNA failed to detect any genetic structure; and a similar lack of structure was found using allozymes, with the exception of clinal variation imposed by selection. Here we have used highly polymorphic genetic markers that provide better resolution to investigate genetic structure in European eel. Analysis of seven microsatellite loci among 13 samples from the north Atlantic, the Baltic Sea and the Mediterranean Sea basins reveals that there is global genetic differentiation. Moreover, pairwise Cavalli-Sforza and Edwards chord distances correlate significantly with coastal geographical distance. This pattern of genetic structure implies non-random mating and restricted gene flow among eels from different sampled locations, which therefore refute the hypothesis of panmixia. Consequently, the reproductive biology of European eel must be reconsidered.     

Deletions of muscle mitochondrial DNA in patients with mitochondrial myopathies

In vitro studies of muscle mitochondrial metabolism in patients with mitochondrial myopathy have identified a variety of functional defects of the mitochondrial respiratory chain, predominantly affecting complex I (NADH-CoQ reductase) or complex III (ubiquinol-cytochrome c reductase) in adult cases. These two enzymes consist of approximately 36 subunits, eight of which are encoded by mitochondrial DNA (mtDNA). The increased incidence of maternal, as opposed to paternal, transmission in familial mitochondrial myopathy suggests that these disorders may be caused by mutations of mtDNA. Multiple restriction endonuclease analysis of leukocyte mtDNA from patients with the disease, and their relatives, showed no differences in cleavage patterns between affected and unaffected individuals in any single maternal line. When muscle mtDNA was studied, nine of 25 patients were found to have two populations of muscle mtDNA, one of which had deletions of up to 7 kilobases in length. These observations demonstrate that mtDNA heteroplasmy can occur in man and that human disease may be associated with defects of the mitochondrial genome.     

Mitochondrial DNA analysis of ancient Sampula population in Xinjiang

The archaeological site of Sampula cemetery was located about 14 km to the southwest of the Luo County in Xinjiang Khotan, China, belonging to the ancient Yutian kingdom. ¹⁴C analysis showed that this cemetery was used from 217 B.C. to 283 A.D. Ancient DNA was analyzed by 364 bp of the mitochondrial DNA hypervariable region I (mtDNA HVR-I), and by six restriction fragment length polymorphism (RFLP) sites of mtDNA coding region. We successfully extracted and sequenced intact stretches of maternally inherited mtDNA from 13 out of 16 ancient Sampula samples. The analysis of mtDNA haplogroup distribution showed that the ancient Sampula was a complex population with both European and Asian characteristics. Median joining network of U3 sub-haplogroup and multi-dimensional scaling analysis all showed that the ancient Sampula had maternal relationship with Ossetian and Iranian.     

Mitochondrial DNA analysis of ancient Sampula population in Xinjiang

The archaeological site of Sampula cemetery was located about 14 km to the southwest of the Luo County in Xinjiang Khotan,China,belonging to the ancient Yutian kingdom.~14C analysis showed that this cemetery was used from 217 B.C.to 283 A.D. Ancient DNA was analyzed by 364 bp of the mitochondrial DNA hypervariable region I (mtDNA HVR-I),and by six restriction fragment length polymorphism (RFLP) sites of mtDNA coding region.We successfully extracted and sequenced intact stretches of maternally inher- ited mtDNA from 13 out of 16 ancient Sampula samples.The analysis of mtDNA haplogroup distribution showed that the ancient Sampula was a complex population with both European and Asian characteristics.Median joining network of U3 sub-haplogroup and multi-dimen- sional scaling analysis all showed that the ancient Sampula had maternal relationship with Ossetian and Iranian.     

基于二次插值的人工蜂群算法

人工蜂群算法是一种基于蜜蜂采蜜行为的一种优化算法.针对标准人工蜂群算法的收敛速度慢、搜索能力差、精度低的缺点。提出了一种基于二次插值的人工蜂群算法(QIABC)。保持全局搜索和局部搜索的平衡.数值实验说明了改进的人工蜂群算法在函数评价次数、收敛速度、精度和鲁棒性方面具有较大的优势,从而表明改进方法的有效性。     

Antiquity of clonal salamander lineages revealed by mitochondrial DNA.

The existence of clonally reproducing vertebrates has often served as a foil in attempts to explain the near-ubiquity of sexual reproduction in eukaryotes, but the absence of recombination, with its attendant limitation of new genotypes to those produced through mutations, restricts the adaptive ability of clonal organisms. It has been argued, therefore, that clonal vertebrate taxa have short lifespans. Variation in mitochondrial DNA (mtDNA) within clonal populations is interpreted instead as reflecting multiple, although limited, independent hybridization events. On the basis of an analysis of an average of 373 nucleotide pairs, we report here that the mtDNA of clonal, hybrid, gynogenetic mole salamanders (Ambystoma, Ambystomatidae) differs by 5% or more from mtDNA of their closest possible sexual relatives (A. jeffersonianum, A. laterale and A. texanum). Assuming usual rates of mtDNA divergence, these lineages have persisted for about 5 million years, far longer than estimated for other clonal vertebrate populations. The low mtDNA variability in the clonal lineages suggests that they have undergone population reductions during the Pleistocene.     

Nucleotide sequence evidence for rapid genotypic shifts in the bovine mitochondrial DNA D-loop

Mitochondrial DNA (mtDNA) is unusual in its rapid rate of evolution and high level of intraspecies sequence variation. The latter is thought to be related to the strict maternal inheritance of mtDNA, which effectively isolates within a species mitochondrial gene pools that accumulate mutations and vary independently. A fundamental and as yet unexplained aspect of this process is how, in the face of somatic and germ-line mtDNA ploidy of 10(3) to 10(5) (refs 4, 5), individual variant mtDNA molecules resulting from mutational events can come to dominate the large intracellular mtDNA population so rapidly. To help answer this question, we have determined here the nucleotide sequence of all or part of the D-loop region in 14 maternally related Holstein cows. Four different D-loop sequences can be distinguished in the mtDNA of these animals. One explanation is that multiple mitochondrial genotypes existed in the maternal germ line and that expansion or segregation of one of these genotypes during oogenesis or early development led to the rapid genotypic shifts observed.     

Independent transfer of mitochondrial plasmids in Neurospora crassa

In the ascomycete fungus Neurospora, the distribution of homologous mitochondrial plasmid DNAs in different species and among mitochondrial types of N. crassa suggests that these molecules have moved between lineages of clonally propagated mtDNA. Here we report direct evidence for independent inheritance of mitochondrial plasmids by sexual reproduction which may help explain the distribution of these molecules among mitochondrial lineages.     

Mitochondrial genome variation and the origin of modern humans

The analysis of mitochondrial DNA (mtDNA) has been a potent tool in our understanding of human evolution, owing to characteristics such as high copy number, apparent lack of recombination, high substitution rate and maternal mode of inheritance. However, almost all studies of human evolution based on mtDNA sequencing have been confined to the control region, which constitutes less than 7% of the mitochondrial genome. These studies are complicated by the extreme variation in substitution rate between sites, and the consequence of parallel mutations causing difficulties in the estimation of genetic distance and making phylogenetic inferences questionable. Most comprehensive studies of the human mitochondrial molecule have been carried out through restriction-fragment length polymorphism analysis, providing data that are ill suited to estimations of mutation rate and therefore the timing of evolutionary events. Here, to improve the information obtained from the mitochondrial molecule for studies of human evolution, we describe the global mtDNA diversity in humans based on analyses of the complete mtDNA sequence of 53 humans of diverse origins. Our mtDNA data, in comparison with those of a parallel study of the Xq13.3 region in the same individuals, provide a concurrent view on human evolution with respect to the age of modern humans.     

Paternal inheritance of mitochondrial DNA in mice.

For nearly 20 years it has been assumed on the basis of low-resolution experiments that mitochondrial (mt)DNA, in contrast to the genes in the nucleus, has an exclusively maternal mode of inheritance in animals. Using the polymerase chain reaction, paternally inherited mtDNA molecules have now been detected in mice at a frequency of 10(-4), relative to the maternal contributions. These mice were hybrids between two inbred strains (C57BL/6J and Mus spretus) whose mtDNAs can be distinguished easily. This new mode of inheritance provides a mechanism for generating heteroplasmy and may explain mitochondrial disorders exhibiting biparental transmission.     

Direct evidence for extensive paternal mitochondrial DNA inheritance in the marine mussel Mytilus.

Inheritance of mitochondrial DNA in animals was thought to be strictly maternal. Recently, evidence for incidental paternal mtDNA leakage was obtained in hybrid crosses of Drosophila and mice. In mice, the frequency of paternal mtDNA contributions was estimated at 10(-4), compared with maternal contributions. The common occurrence in the marine mussel Mytilus of heteroplasmic individuals with two or more types of highly diverged mtDNA molecules was interpreted as strong evidence for biparental mtDNA inheritance by some, but not by others. We report here results from pair-matings involving two species of mussels, Mytilus edulis and Mytilus trossulus. Extensive contribution of paternal mtDNA, amounting to several orders of magnitude higher than that inferred for Drosophila or mice, was observed in both intra- and interspecific crosses.     

Neanderthals in central Asia and Siberia

Morphological traits typical of Neanderthals began to appear in European hominids at least 400,000 years ago and about 150,000 years ago in western Asia. After their initial appearance, such traits increased in frequency and the extent to which they are expressed until they disappeared shortly after 30,000 years ago. However, because most fossil hominid remains are fragmentary, it can be difficult or impossible to determine unambiguously whether a fossil is of Neanderthal origin. This limits the ability to determine when and where Neanderthals lived. To determine how far to the east Neanderthals ranged, we determined mitochondrial DNA (mtDNA) sequences from hominid remains found in Uzbekistan and in the Altai region of southern Siberia. Here we show that the DNA sequences from these fossils fall within the European Neanderthal mtDNA variation. Thus, the geographic range of Neanderthals is likely to have extended at least 2,000 km further to the east than commonly assumed.     

The recent disciplinal progresses of agricultural entomology in China

In this paper, four recent advances and achievements of China in agricultural insect research, namely, on the genome of silkworm （Bombyx mori Linnaeus）, on the geographical differentiation and regional migration of cotton bollworm （Helicoverpa armigera （Hübner））, on the standardized monitoring techniques for safety of honey bee （Apis mellifera Linnaeus） products, and on the virus transmission property of small brown planthopper （Laodelphax striatellus （Fallén）） as well as the interactions between vector and rice stripe virus （RSV）, were reported. All of these researches are very important for controlling agricultural insect pests and the diseases they transmit, accelerating the molecular biological research of silkworm, and promoting the international trade of honey bee products. Most of these achievements mentioned above have got the national, provincial, ministerial or municipal awards on science and technology.     

Conservation and rearrangement of mitochondrial structural gene sequences

Mitochondria contain the simplest DNA molecules that are present in eukaryotes. Mitochondrial DNA (mtDNA) is easily purified, and is an important model system for studying eukaryote gene structure and basic molecular processes. The protein sequences of mitochondrial gene products have been shown to be conserved from yeast to man, and there are definite similarities at the DNA sequence level. In contrast, the overall organization of the mitochondrial genome is drastically different in these organisms. To understand this, we need to extend work on mtDNA to a wider range of species. We have chosen to study the mtDNA of Aspergillus nidulans because a particularly comprehensive analysis of this system can be achieved using genetics as well as biochemistry, and like most eukaryotes it is an obligate aerobe, whereas Saccharomyces cerevisiae is not. We have investigated whether defined pieces of particular yeast mitochondrial genes show enough homology to Aspergillus mtDNA fragments to enable the corresponding Aspergillus genes to be located on the physical map. The results reported here show that this is the case for all five genes tested, and present the first data on the physical organization of the structural genes in the mitochondrial genome of A. nidulans.     

An autosomal dominant disorder with multiple deletions of mitochondrial DNA starting at the D-loop region

Deletions of muscle mitochondrial DNA (mtDNA) have recently been found in patients with mitochondrial myopathy. However, as most of the described cases were sporadic, and individual deletions involved different portions of mtDNA, the mechanism(s) producing the molecular lesions, as well as their mode of transmission, remain unclear. By studying families with mtDNA heteroplasmy, valuable information can be obtained about the role of inheritable factors in the pathogenesis of these disorders. We have studied four members of a family with autosomal dominant mitochondrial myopathy. Multiple deletions, involving the same portion of muscle mtDNA, were identified in all patients. Sequence analysis of the mutant mtDNAs, performed after DNA amplification by the polymerase-chain reaction showed that all the deletions start within a 12-nucleotide stretch at the 5' end of the D-loop region, a site of active communication between the nucleus and the mtDNA. The data indicate that a mutation of a nuclear-coded protein can destroy the integrity of the mitochondrial genome in a specific, heritable way.     

西藏马线粒体DNA D-loop区的遗传多样性

对西藏拉萨和泽当两个地区23匹西藏马的线粒体DNA控制区(mtDNA D-loop)部分片段进行序列分析, 检测出16个单倍型, 包括32个核苷酸多态性位点(其中转换位点31个, 缺失位点1个), 占所分析位点总数的9.27%. 单倍型多样性(h)和核苷酸多样性(π)分别为0.93±0.04和2.51%±0.16%, 表明西藏马的遗传多样性较丰富. 基于23匹西藏马序列以及现代欧亚马群的mtDNA序列, 进行了系统发育分析和多维尺度分析. 结果表明, 西藏马在母系遗传关系上与近东、 中亚以及欧洲家马有较近的亲缘关系, 与东亚的蒙古马以及韩国马亲缘关系较远.     

Complex social behaviour derived from maternal reproductive traits

A fundamental goal of sociobiology is to explain how complex social behaviour evolves, especially in social insects, the exemplars of social living. Although still the subject of much controversy, recent theoretical explanations have focused on the evolutionary origins of worker behaviour (assistance from daughters that remain in the nest and help their mother to reproduce) through expression of maternal care behaviour towards siblings. A key prediction of this evolutionary model is that traits involved in maternal care have been co-opted through heterochronous expression of maternal genes to result in sib-care, the hallmark of highly evolved social life in insects. A coupling of maternal behaviour to reproductive status evolved in solitary insects, and was a ready substrate for the evolution of worker-containing societies. Here we show that division of foraging labour among worker honey bees (Apis mellifera) is linked to the reproductive status of facultatively sterile females. We thereby identify the evolutionary origin of a widely expressed social-insect behavioural syndrome, and provide a direct demonstration of how variation in maternal reproductive traits gives rise to complex social behaviour in non-reproductive helpers.     

Genetic evidence for female host-specific races of the common cuckoo

The common cuckoo Cuculus canorus is divided into host-specific races (gentes). Females of each race lay a distinctive egg type that tends to match the host's eggs, for instance, brown and spotted for meadow pipit hosts or plain blue for redstart hosts. The puzzle is how these gentes remain distinct. Here, we provide genetic evidence that gentes are restricted to female lineages, with cross mating by males maintaining the common cuckoo genetically as one species. We show that there is differentiation between gentes in maternally inherited mitochondrial DNA, but not in microsatellite loci of nuclear DNA. This supports recent behavioural evidence that female, but not male, common cuckoos specialize on a particular host, and is consistent with the possibility that genes affecting cuckoo egg type are located on the female-specific W sex chromosome. Our results also support the ideas that common cuckoos often switched hosts during evolution, and that some gentes may have multiple, independent origins, due to colonization by separate ancestral lineages.