紫芝不亲和性因子分析

为开展紫芝的杂交育种,对6个紫芝菌株的不亲和性因子进行分析。通过原生质体单核化,6个紫芝获得9个不同亲本型的单核化菌株,共测得7个不同的A因子和7个不同的B因子,A、B因子的多态性各占单核体的77.8%,表明紫芝有较丰富的交配型因子,为紫芝的杂交育种奠定基础。     

Morphological variation inLolium (Poaceae) as a measure of species relationships

Analysis of morphological and phenological data for determining the genetic variation within sevenLolium species led to the recognition of two groups within this genus. One group, containing the two inbreeding speciesL. temulentum andL. persicum, was clearly distinct from all other species. Strong morphological and phenological intergradation was found between both species. The cross-breeding species,L. perenne, L. rigidum, andL. multiflorum, formed another group. Little differentiation was found between these species, though they were distinct. Two inbreeding species,L. loliaceum andL. remotum, were clearly distinct from each other and the two groups.L. loliaceum had an isolated position and was most related toL. rigidum. L. remotum had an intermediate position between the cross-breeding and inbreeding species, and was almost equally distant from all three cross-breeding species.Genetic variation inLolium spp. I.     

Further experiments on the cross-breeding of two races of the mothAcidalia virgularia

Ohne Zusammenfassung

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Further experiments on the cross-breeding of two races of the mothAcidalia virgularia

     

Ethnic marriage assortativeness and intensity of metisation of Karachays

On the basis of 11280 marriage records of four regions of Karachay-Cherkessia (Karachaevsky, Malokarachaevsky, Ust-Dzhegutinsky, Prikubansky, 193.2 thousand people in total) for 1990–2000, the intensity of Karachay cross-breeding was determined, amounting to 11.7%. Comparison of the intensity of Karachay cross-breeding with that for some other ethnoses is carried out. The ethnic assortativness H is approximately one. The population is characterized a preference for monoethnic marriages. The endogamy index in the studied regions varies from 0.29 to 0.53; after the exclusion from the analysis of repatriates, it increases to 0.34–0.63. The values of local inbreeding in an interval are 0.0001–0.0004, and no differences in terms of isolation by distance are revealed among the regions (0.001). The average square migration is 40–60 km.

     

A suspected synonymy in genus Dendrocerus (Hymenoptera: Ceraphronoidea) confirmed by experimental breeding

Abstract

Breeding and cross-breeding confirm the synonymy Dendrocerus aphidum (Rondani, 1877) = Dendrocerus breadalbimensis (Kieffer, 1907).     

The Bira of the savanna and the Bira of the rain forest. A comparative study of two populations of the Democratic Republic of the Congo

In this investigation we have studied multifactor, hereditary, physical characteristics of two Congolese populations, the Bira of the savanna and the Bira of the rain forest, originated from the same population and at present diversified morphologically. The hypothesis of adaptation of these populations to different environments in which they have lived for nearly three centuries would appear to be the most appropriate explanation of the differences observed. Convergence of physical characteristics points to a cross-breeding of the Bira with pygmies in the forest and Tutsi in the savanna, although both investigation of single factor characteristics (blood groups, sicklemia) and social habits appears to contradict the cross-breeding hypothesis. In addition, the founder effect and genetic drift may have been important factors at the time of migration of these populations.The importance of adaptation and natural selection have very likely increased from generation at the expense of the role of genetic drift and of the founder effect. These two factors were shortlived but primordial for the first generations that followed the scission and migration.     

优良面包酵母菌株的杂交育种

本文对实验室保存的面包酵母进行筛选,以不加糖面团发酵力最高的菌株BY-14和高糖面团发酵力最高的菌株BY-6作为两杂交亲本.二倍体菌株经过单倍体制备、分离和筛选后,利用群体杂交方法,获得了一株兼备两亲本优良性能的面包酵母菌株,其不加糖面团发酵力达到菌株BY-14水平,且高糖面团发酵力比菌株BY-6提高了25%.     

Observation of Flowering Process of Grape (<i>Vitis vinifera</i> L.)—Insight into the Starting of Pollination of Flower Hiding in Calyptras (Cap)

It is generally agreed that many Vitis vinifera L. cultivars are self-fertile, where self-pollination often occurs before capfall in a process called cleistogamy. Therefore, it is difficult to identify the right time to remove stamens before self-pollination during the cross-breeding of grape. For this paper, we observed the process of grape flowering and measured the pollen viability and stigma receptivity of grape flowers of ‘Shine Muscat’ in order to identify the starting time of self-pollination before capfall and to provide useful information for improving the efficiency of cross-breeding. The results demonstrate that the anther is not cracked during the visible clusters and separated clusters stages. Meanwhile, in the separated floral buds, flowering begins, and full bloom stages, the pollen viability is 60.7%, 73.2% and 80.3%, respectively; however, at the berry set stage, pollen viability drops to zero. The top of the mature stigma is composed of a layer of nearly cylindrical papillary cells, and the stigma receptivity for pollen changes with the development of flowers: in particular, no reaction was observed in the visible clusters stage; weak positive reaction at the separated clusters stage; strong positive reaction at the separated floral buds, flowering begins, and full bloom stages; and no reaction at the berry set stage. In the separated floral buds stage, pollen tubes were seen germinating in the style. In the flowering begins stage, more pollen tubes were observed at the entry of the ovary. During the full bloom stage, most pollen tubes elongated into the ovary base and some entered the pearl hole. At the berry set stage, newborn endosperm nucleus could be seen in the ovule. From the above, we can conclude that the initiation time of closed fertilization for ‘Shine Muscat’ grape can be judged as the separated floral buds stage, and it is best to discard the stamen before the separated floral buds stage when conducting cross-breeding.     

Admixture and Local Breed Marginalization Threaten Algerian Sheep Diversity

Due to its geo-climatic conditions, Algeria represents a biodiversity hotspot, with sheep breeds well adapted to a patchwork of extremely heterogeneous harsh habitats. The importance of this peculiar genetic reservoir increases as climate change drives the demand for new adaptations. However, the expansion of a single breed (Ouled-Djellal) which occurred in the last decades has generated a critical situation for the other breeds; some of them are being subjected to uncontrolled cross-breeding with the favored breed and/or to marginalization (effective size contraction). This study investigated genetic diversity within and among six of the nine Algerian breeds, by use of 30 microsatellite markers. Our results showed that, in spite of the census contraction experienced by most of the considered breeds, genetic diversity is still substantial (average gene diversity ranging 0.68 to 0.76) and inbreeding was not identified as a problem. However, two breeds (Rembi and Taâdmit) appeared to have lost most of their genetic originality because of intensive cross-breeding with Ouled-Djellal. Based on the above evidence, we suggest Hamra, Sidaoun, and D’man as breeds deserving the highest priority for conservation in Algeria.     

Biomphalaria tenagophila: dynamics of populations of resistant and susceptible strains to Schistosoma mansoni, with or without pressure of the parasite

Resistant (Taim, RS) and susceptible albino (Joinville, SC) Biomphalaria tenagophila populations were kept together, at different proportions, throughout a 18-month-period. Some of the snail groups were submitted to Schistosoma mansoni infection. The targets of this study were (a) to analyze the populational dynamics among resistant and susceptible individuals to S. mansoni; (b) to study the resistance phenotype in descendants of cross-breeding; (c) to observe whether the parasite could exert any kind of selection in those snail populations. Throughout the experiment it could be observed that the susceptible B. tenagophila strain (Joinville) underwent a selective pressure of the parasite that was negative, since the individuals showed a high mortality rate. Although B. tenagophila (Taim) population presented a higher mortality rate without pressure of the parasite, this event was compensated by a reproductive capacity. B. tenagophila Taim was more fecund than B. tenagophila Joinville and was able to transmit the resistance character to their descendants. F1 generation obtained by cross-breeding between resistant and susceptible lineages was completely resistant to S. mansoni infection, irrespective of the Taim proportion. Moreover, less than 5% of F2 progeny were susceptible to S. mansoni infection.     

优良面包酵母菌株的杂交育种

本文对实验室保存的面包酵母进行筛选, 以不加糖面团发酵力最高的菌株BY-14和高糖面团发酵力最高的菌株BY-6作为两杂交亲本。二倍体菌株经过单倍体制备、分离和筛选后, 利用群体杂交方法, 获得了一株兼备两亲本优良性能的面包酵母菌株, 其不加糖面团发酵力达到菌株BY-14水平, 且高糖面团发酵力比菌株BY-6提高了25％。     

青花菜雄性不育系选育研究初报

以具有细胞质雄性不育基因的青花菜不育材料CMS94008为不育源,通过杂交和连续回交的方法选育出不育性稳定、经济性状良好的一批青花菜胞质雄性不育系,并以CMS92100、CMS93-2、CMS9905、CMS95234等不育材料及其转育父本为代表,对不育系的主要特征及农艺性状进行系统的观察鉴定。     

应用性遗传模式选育香菇优良菌株——中香68杂交菌株选育报告

根据香菇四极性异宗配合的性遗传特性,通过亲本的选择,采用孢子单核体的对称杂交育种手段,实现基因重组,从中选育出广温型优良菌株中香68,介绍了中香68菌丝生长和子实体特征及其新菌株的鉴别方法。同时讨论了香菇单孢杂交育种的种质资源和育种工艺。     

Evidence for the reproductive isolation of Dermacentor marginatus and Dermacentor reticulatus (Acari: Ixodidae) ticks based on cross-breeding, morphology and molecular studies

The species status of Dermacentor marginatus and Dermacentor reticulatus was evaluated by scanning electron microscope (SEM) examination of adult ticks, cross-breeding experiments and molecular biological analysis of eggs derived from transspecific pairings. The SEM investigations including the morphometric quantification of phenotypic features resulted in an unequivocal differentiation of adult D. marginatus and D. reticulatus ticks. The cross-breeding experiments demonstrated that irrespective of whether female ticks of both species were applied with con- or transspecific male ticks or without males to sheep, they engorged and laid eggs. The larvae, however, developed only in eggs which originated from conspecific matings. A nested polymerase chain reaction (PCR) of the second internal transcribed spacer (ITS2) using the DNA of eggs from transspecific pairings and sequencing of the PCR products revealed two different genotypes. The genotypes of eggs originating from D. marginatus and D. reticulatus females of these pairings differed. However, the eggs deposited by D. marginatus always possessed the same two genotypes as did the eggs produced by D. reticulatus. These results argue for a strict reproductive isolation of D. marginatus and D. reticulatus and, therefore, for a separate species status.     

Effect of outbreeding on weight and growth rate of captive infant rhesus macaques

The introduction of unrelated conspecifics into captive groups of primate species is desirable to inhibit inbreeding. However, for many species, such groups increasingly represent highly inbred isolate populations that are analogous to regionally isolated populations of the same species among whom the effects of outcrossing on fitness are unknown. A study of potentially adverse effects of cross-breeding between regionally isolated populations of rhesus macaques was conducted to assess the maximum advantage or disadvantage to be expected for cross-breeding such populations of other cercopithecoid primates. For this purpose, the infant weights and rates of growth of hybrid Chinese/Indian rhesus macaques were compared to those of their nonhybrid Indian peers and to those of consanguineously inbred Indian rhesus macaques from several other captive breeding groups. Neither adverse nor advantageous effects of such hybridization were detected, suggesting that outcrossing between isolates of other cercopithecoid primates with a similar social structure and mating pattern should not affect the fitness of resulting offspring. Since levels of inbreeding are roughly inversely proportional to levels of genetic diversity within populations, such outcrossing should be intensified by zoos and other captive breeding centers to ensure the continued survival of captive species, especially those that are endangered or otherwise irreplaceable.     

Detection of microcythemia in a school population in Milan: survey of microcythemic subjects 8 years after the diagnosis was made

In the Milan School population the screening for microcythemy is performed from 1963. It was conducted an investigation among the subjects who were recognized microcythemics eight years ago and who now are eighteen years old. Almost all of them are conscious about their situation and about half of them has a scrupulous notion about a cross-breeding with a high risk. Are also offered the results of the research on the personal behaviour in front of the direct prevention of the mediterranean anemia by prenatal diagnosis.     

Reproductive isolation in snails of the genus Albinaria (Gastropoda: Glausiliidae)

Parapatric, morphologically characterized forms of the Mediterranean snail genus Albinaria have traditionally been regarded as biological species. Recently, this view has been challenged on the basis of small interspecific genetic distances and cross-breeding experiments. In order to test whether traditionally recognized species are reproductively isolated lineages, two cases of syntopy were analysed by means of isozyme electrophoresis. The data suggest that complete reproductive isolation is present. In one of the two cases, ecological differentiation on a small spatial scale was observed.     

福建栽培大豆品种RAPD标记多样性分析

利用RAPD分子标记技术对福建18份栽培大豆品种遗传多样性进行研究.结果表明,12个引物共扩增出91条带,其中多态条带65条,多态性程度为71.43%.D=0.62时,聚类分析结果可以将供试材料分为3个大类群,即菜用大豆品种、杂交育成品种和地方品种、有半野生血缘的品种各聚成1类,揭示了福建省栽培大豆品种间的亲缘关系,同时还反映出品种间关系与地理起源有一定的相关.     

Genetic improvement of the biological control nematode Heterorhabditis bacteriophora (Rhabditidomorpha: Heterorhabditidae): heterosis effect enhances desiccation but not heat tolerance

The entomopathogenic nematode Heterorhabditis bacteriophora is commercially used in biological control of soil dwelling insect pests. It reproduces by autogamy (hermaphrodites) enabling the production of inbred lines, but also by amphimixis (through mating of male and female) which allows cross-breeding. When H. bacteriophora is produced in liquid culture, copulation of male and female is prevented and reproduction is solely by self-fertilisation of hermaphrodites. When reared in insects, crosses are possible resulting in heterozygous offspring. Heat and desiccation tolerance of these nematodes have been successfully improved by selective breeding. Trait deterioration was prevented by producing homozygous inbreds through consecutive reproduction in liquid culture, the method also used for commercial mass production. In this study, we investigated possible heterosis effects in desiccation and heat tolerance after cross-breeding of homozygous inbred lines of H. bacteriophora. Increased desiccation tolerance of the heterozygous progeny in comparison to homozygous inbred lines was recorded indicating that heterosis is a possible means for further improvement of this trait. In contrast, the heat tolerance of the heterozygous offspring was lower than that of the homozygous population. The results provide evidence for the tremendous potential of classical genetics to improve beneficial traits of a biological control agent and carry domestication of H. bacteriophora a significant step forward.     

The genetics of bird migration: stimulus, timing, and direction

The extent to which genetic factors are directly involved in the control of bird migration and the mode of inheritance involved has been studied systematically over the past 15 years in the Blackcap Sylvia atricapilla by cross-breeding and selective breeding. Results have also been obtained from a few experimental and field studies on Robins Eritfiacus rubecula, Blackbirds Turdus merula and Song Sparrows Melospiza melodia. Cross-breeding of migrants with nonmigrants has resulted in the partial transmission of migratory activity into the F, generation indicating that the urge to migrate is inherited and is based on a multilocus system with a threshold for expression. Migratoriness and sedentariness in obligate partial migrants is probably inherited in a similar way, suggesting that the decision to migrate also has a strong genetic basis. Both traits can be selected to phenotypic uniformity within 3–6 generations indicating an extremely high evolutionary potential. Orientation behaviour can also be transmitted to the offspring of a nonmigratory population by cross-breeding. Cross-breeding individuals with different migratory directions produced offspring with phenotypically intermediate directional preferences, suggesting that the migratory direction is also a predominantly heritable character. In the current development of novel migratory habits in those Central European Blackcaps that now winter in the British Isles, the inheritance of the novel migratory direction may be crucial. Genetic variation in migratory events seems to be sufficient to allow for many microevolutionary processes.