显性核不育小麦孤雌生殖诱导方法的研究

在大田和隔离区条件下，以太谷核不育小麦和”矮败”小麦为材料，用５００ｍｇＬ－１ＣＰＸ＋１００ｍｇＬ－１ＫＴ＋２％ＤＭＳＯ诱导不育株孤雌生殖。试验结果表明，不同施药方法的诱导效果存在差异，注射妤于喷施。剪颖后用药剂处理和药剂处理后套袋均能提高诱导效果。药剂处理时间以晚上７时后效果最佳。太谷核不育小麦和“矮败”小麦的最佳用药处理次数各异。     

诱导矮败小麦孤雌生殖的效果研究

试验用二甲基亚砜、对氯苯氧乙酸、激动素、赤霉素、聚乙二醇、矮壮素、肌醇、烟酸 8种单一药剂 ,各种组合处理药剂及二次处理药剂 (赤霉素、肌醇、2 ,4 D和植物血清凝集素 )诱导矮败小麦孤雌生殖 ,共处理了750 0穗。结果表明 :单一药剂以 0 0 1 5mL/mL二甲基亚砜和 1 0 0mg·kg- 1 赤霉素诱导效果最好 ,两年诱导结实率分别为 0 1 67% ,0 1 94%和 0 1 1 1 % ,0 1 39%。筛选出最佳组合药剂为 50 0mg·kg- 1 对氯苯氧乙酸 1 0 0mg·kg- 1 激动素 0 0 1 5mL/mL二甲基亚砜 ,两年诱导结实率分别为 0 2 78%和 0 333 %。大多数组合药剂的诱导效果优于单一药剂的诱导效果。二次处理的每种药剂有一最适浓度     

小鼠孤雌生殖的胚胎干细胞的初步研究

比较去透明带孤雌桑葚胚和留透明带孤雌囊胚、体内受精胚胎、体外受精胚胎在饲养层上囊胚的扩张率、岵壁生长率．结果表明去透明带孤雌桑葚胚比留透明带孤雌囊胚的扩张率显著（p〈0．05）提高,而贴壁率则极其显著地（p〈0．01）提高,此外前者还发生增殖．但孤雌胚胎的囊胚扩张率、贴壁率和增殖率均极其显著地（p〈0．01）低于体内受精胚胎和体外受精组;体内受精胚胎的体外发育最佳．说明去透明带孤雌桑葚胚比留透明带孤雌囊胚更利于在饲养层上贴壁生长,为建立孤雌生殖的胚胎干细胞系提供了基础．     

Male production induced by antibiotic treatment inEncarsia formosa (Hymenoptera: Aphelinidae), an asexual species

The production of large numbers of males in the thelytokous speciesEncarsia formosa was induced by feeding antibiotics to their mothers. The males induced by antibiotic treatment produce sperm and sometimes mate with females, but insemination does not occur.     

Asexual reproduction: Genetics and evolutionary aspects

Reproduction is essential to all organisms if they are to contribute to the next generation. There are various means and ways of achieving this goal. This review focuses on the role of asexual reproduction for eukaryotic organisms and how its integration in a life cycle can influence their population genetics and evolution. An important question for evolutionary biologists as to why some organisms reproduce sexually, as opposed to asexually, is addressed. We also discuss the economic and medical importance of asexual organisms. Received 4 December 2006; received after revision 25 January 2007; accepted 20 February 2007     

Evolutionary and ecological consequences of interspecific hybridization in cladocerans

The evolutionary process of interspecific hybridization in cladocerans is reviewed based on ecological and population genetic data. The evolutionary consequences of hybridization, biogeographic patterns and fitness comparisons are analyzed within the conceptual framework of theories on hybridization. Among species of theD. longispina complex no interpopulational transition zones (hybrid zones) have been detected, but rather patchy distributions of hybrids and parentals have been found. Hybrids occur across broad geographic ranges and can be more abundant than parental species. Due to asexual reproduction (ameiotic parthenogenesis), hybrid breakdown can be avoided, and hybrids can even (temporarily) combine advantageous traits of both parental species. Evolutionary consequences may arise from repeated backcrossing, which in some cases results in introgression and patterns of reticulate evolution.Those forms which possess in some considerable degree the character of species, but which are so closely similar to some other forms, or are so closely linked to them by intermediate gradations, that naturalists do not like to rank them as distinct species, are in several respects the most important to us (Charles Robert Darwin 1859)     

Parthenogenetic Darevskia lizards mate frequently if they have the chance: a quantitative analysis of copulation marks in a sympatric zone

Several Caucasian rock lizards of the genus Darevskia of hybrid origin are known to reproduce parthenogenetically. Local communities can be composed exclusively of parthenogens, though syntopy with bisexual members of the genus may occur. In some localities, reproduction between bisexual and parthenogenetic Darevskia has been previously reported based on lizard intermediate morphology and karyology (3n, 4n). However, the frequency of such heterospecific matings remains unknown. We indirectly quantified the reproductive interactions through the inspection of copulation marks in females in a mixed Darevskia community from Kuchak (Armenia) composed of two hybrid parthenogens (D. armeniaca and D. unisexualis), one bisexual species (D. valentini) and their putative backcrosses. A total of 139 adults were randomly collected and photographed. Females were later measured (SVL), inspected for inguinal marks and ranked from 0 (no scars) to 3 (≥ 3 scars). The lizard species and ploidy determination was ensured by a parallel microsatellite analysis. Sex-ratio in the community was extremely biased due to the high abundance of parthenogenetic females. All female types displayed copulation marks with frequencies varying from 80% in D. valentini to 64% in D. armeniaca. Remarkably, 7 out of 11 (64%) backcross females also showed marks. In the most abundant D. armeniaca, the prevalence and intensity of copulation marks increased with body size, just as predicted for polygynous female lacertids. These results indicate that copulation between parthenogenetic and bisexual species in Darevskia mixed communities is common and driven by sexual selection, thus reinforcing previous suggestions of reproductive interaction in syntopy. Evolutionary implications of these findings are discussed.     

Patterns in plant parthenogenesis

Summary Plant taxa that reproduce asexually display some distinct geographical and ecological patterns. A literature review reveals that such taxa 1) tend to have larger ranges, 2) tend to range into higher latitudes, and 3) tend to range to higher elevations than do their sexual relatives. Asexual taxa have a greater tendency than sexual taxa do to colonize once-glaciated areas. These trends have previously been identified as characteristic of parthenogenetic animals as well. While many authors have interpreted these trends as providing support for the biotic uncertainty hypothesis for the maintenance of sex, these trends are consistent with several other interpretations as well. Furthermore, all of these interpretations have ignored the positive correlation that exists between ploidy level and breeding system: asexual plant and animal taxa are generally polyploid, while their sexual relatives are generally diploid. Evidence is presented for plants, and by extension for animals as well, that high ploidy levels alone could (independent of breeding system) endow individuals with the ability to tolerate these extreme environments. For this reason, it appears premature to interpret observed distribution patterns as evidence to support hypotheses about what forces maintain sexual reproduction. Only experimental tests, using sexuals and asexuals of comparable ploidy levels, can permit us to discriminate among the alternatives.     

Differential gene expression profiling in the developed ovaries between the parthenogenetic and bisexual female rice water weevils,Lissorhoptrus oryzophilus Kuschel （Coleoptera： Curculionidae）

The rice water weevil, Lissorhoptrus oryzophilus Kuschel （Coleoptera： Curculionidae）, reproduces by sex in the Southeastern United States, but reproduces by parthenogenesis in California and other invaded regions in Asia and Europe. The objective of this study was to create a parthenogenetic gene expression profile of the rice water weevil in order to gain a better insight into the molecular mechanisms of parthenogenesis in the weevil. Suppression subtractive hybridization （SSH） technique was employed for profiling differential gene expression in the developed ovary between the parthenogenetic and bisexual female rice water weevils. A total of 70 contigs were obtained, and the BLASTX search identified putatively 28 genes with differential functions. According to the cytological process of parthenogenesis, the tubulin alpha-1 chain and signal transduction genes etc. were selected for real time quantitative RT-PCR analyses, and their possible functions related to the molecular mechanism of parthenogenesis were discussed. The tubulin alpha-1 chain and some signal transduction genes may be related to the molecular mechanisms of parthenogenesis of the rice water weevil.