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水稻低温敏不育系培矮64s“冷灌繁种”适用技术研究 总被引：1，自引：0，他引：1
通过对低温敏不育系水稻培矮６４ｓ育性敏感期间冷水灌溉处理后的农田微气象要素和自交结实率的平行观测，分析研究了供试不育系的适宜灌水时段、灌水深度以及灌溉用水量等的“冷灌繁种”适用技术。 相似文献
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两性个体的有效鉴别是曼氏无针乌贼高效繁育及养殖模式(如单性养殖)建立的基础。为研究曼氏无针乌贼主要形态指标及雌雄形态差异,测量了160只F1代曼氏无针乌贼的19项可测量性状及13项标准化性状。采用聚类分析、主成分分析和判别分析方法研究了曼氏无针乌贼同生群两性间的形态差异。结果表明:两性间可测量性状和标准化性状各有10项有显著性差异(P0.05);对标准化性状经过主成分分析和R-聚类分析均显示曼氏无针乌贼的两性的差异主要集中在辅助交配器官特征,头部特征,捕食器官和肥瘦特征以及体型特征等4个方面。在此基础上,通过逐步判别法从标准化性状中筛选出3项,即左3腕长/胴长、左4腕长/胴长及左触腕长/胴长,建立了雌雄的判别方程:雄性:F1=223.42X3+165.85X4+7.951X5–108.06;雌性:F2=151.48X3+92.71X4+19.19X5–60.38。所建立的判别方程,对样本群体的综合判别率达到95.00%。利用F2代亲体测量数据对判别函数进行识别验证,综合判别率达到85.34%。在判别方程中的3个标准化性状中,左3腕长/胴长和左4腕长/胴长在两性亲体间均存在显著的差异(P0.05),表明曼氏无针乌贼的雄性在性选择的作用下,交配器官存在显著差异。 相似文献
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The effects of degraded porphyran (P1) and natural porphyran (P) on the lifespan and vitality of Drosophila melanogaster are studied. The porphyrans, added daily to the food medium at 0.2% and 1% concentrations, can significantly increase the lifespan in average of 55.79 and 58.23 d in 0.2% P1 diet females and 1% P1 diet males, extending by 12.29% and 8.60% over the corresponding controls, respectively. The effects of porphyrans on D. melanogaster in heat-stress condition were also examined, and found a remarkable increase in survival time. The results which are consistently associated with the use of porphyrans are related to their free radical scavenger action. Considerable increase in vitality demonstrated that vitalities of middle-aged fly (assessed by measuring their mating capacity) was observed after porphyrans addition. Therefore, porphyrans are effective in reducing the rate of aging, and P1 in low molecular weight is better than natural P. 相似文献
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为了探讨禾本科赖草属植物大赖草的交配系统,对其的花设计、花展示、花粉活力、柱头可授期及交配方式进行了研究。结果表明:①单花的3个花丝不同步伸长,其中两个生长速度相对较快先弯曲,然后花药纵裂散出花粉,第三个花丝随后弯曲,花药纵裂散出花粉,3个花药的不同步散粉延长了单花的“花粉寿命”。②花药被送出内外稃完成散粉后,羽状柱头伸到内外稃外接受外来花粉,避免了单花内的雌雄干扰。③大赖草花序上小花阶段性批量开放（确保了同一时刻开放的小花是同步的）,还可降低同株异花花粉对柱头的干扰。④大赖草属自花授粉不亲和型,同时同株异花授粉也不亲和,大赖草已进化出了特殊的花设计、花展示和短的花粉寿命等特征来促进异花授粉。这些特征是大赖草在适应极端的沙漠环境的过程中进化出的一种生殖对策。 相似文献
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The fitness of parasitic organisms is strongly driven by their ability to infect potential hosts. Although transmission to a host organism is a key component to the parasitic lifestyle, surviving and reproducing within a host poses additional challenges. Cymothoa excisa is a parasitic isopod that infects Atlantic croaker, Micropogonias undulatus, along the Texas coast and has evolved mechanisms to successfully survive and reproduce within its host. Cymothoa excisa is known to exhibit sex‐change strategies but limited information exists on morphological changes, reproductive output and the timing at which sex change becomes optimal. This study collected Atlantic croaker during a 22‐month survey period and identified parasite prevalence and intensity in the host fish population. Infection rates were constant throughout the year at 19.88% and intensity increased through the season up to a maximum of four parasites. Following collection, isopod morphological parameters were quantified for each life stage (including female, transitional, male and juvenile), identifying shape and size transitions through ontogeny and sex change. Transitional C. excisa isopods only occurred when only one isopod was present in a fish, suggesting that isopods change sex from male to female if they are the first to recruit to an uninfected host. As isopods transition to females they have a large increase in size, legs, and pleotelson (which influence fecundity and anchoring ability), whereas the gonopod, eyes and uropod show a reduction (which are no longer needed for swimming and finding hosts). Data suggest that C. excisa sex change is related to the timing of infection and brood size increases with female size and host size. Therefore, it would be advantageous to be the first isopod to infect a host, as it could change into a female and increase reproductive potential. We discuss hypotheses that could explain the mating behavior of parasitic isopods. 相似文献
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AbstractThe honey-bees mating programming (HBMP) algorithm is introduced as a novel tool for predicting suspended sediment concentration for the Mad River catchment near Arcata, USA. The paper also applies gene expression programming (GEP) as a comparison and shows that these two approaches can the produce transparent, nonlinear relationships between the independent and dependent variables. Some modifications have been made to the HBMP algorithm to improve its capability and efficiency. The results achieved from this method and GEP are compared with two different sediment rating curves based on regression techniques. The findings show that the results from both the HBMP and GEP methods are promising and outperform the results obtained from the sediment rating curves.
Editor D. Koutsoyiannis; Associate editor L. See 相似文献
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浅析建设高产高效矿井的地质保障 总被引：1，自引：0，他引：1
按矿井建设、生产进展阶段和各阶段需要查明的地质异常体的规模和精度,将高产高效矿井地质保障系统划分为4个子系统,即建井采区设计精细勘探子系统、采区(盘区)内勘探子系统、综采工作面内探查子系统和巷道掘进前方与侧帮探查子系统以及完成各子系统探测任务相应的配套技术方法组合;认为将高产高效矿井综采工作面采前勘探以行业法规或规程加以规范是必要的。 相似文献
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A2 × 2 factorial cross between two populations of Pacific abalone Haliotis discus hannai Ino, collected separately from Dalian （D） in China and Miyagi （M） in Japan, was conducted to compare performances in fertilization rate, hatching rate, metamorphosis rate and growth at days 20, 43, 160 and 330 between purebreds （DD and MM） and crossbreds （DM and MD） and investigate the magnitude of heterobeltiosis （better parent） and heterosis （mid-parent）. Heterobeltiosis and heterosis for all the traits analyzed were evidently different between crossbreds DM and MD. Heterobeltiosis in the crossbred DM varied among traits, with values of 2.5% for the fertilization rate, 2.2% for the hatching rate, - 1.9% for the metamorphosis rate and 7.4% for the growth at the day 330. The crossbred DM displayed positive heterotic values for fertilization rate （5.4%）, hatching rate （7.4%）, metamorphosis rate （7.6%） and growth （ 12.0% ） at the day 330. However, both heterobeltiosis and heterosis for all the traits in the crossbred MD were negative except those for the growth at days 20 and 43. The results indicate the importance of selecting superior hybrid varieties if the exploitation of hybrid vigor is considered in the Pacific abalone breeding program. 相似文献
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《African Journal of Marine Science》2013,35(2):145-153
This study investigated multiple mating in three species of intertidal klipfishes (family Clinidae): super klipfish Clinus superciliosus, bluntnose klipfish Clinus cottoides, and nosestripe klipfish Muraenoclinus dorsalis. These species display the rare reproductive mode of female vivipary with superfetation, a phenomenon where offspring at various stages of development are found within the female. Three or four microsatellite loci were used to genotype 25–30 adults of each species, as well as embryos of 131 C. superciliosus from six broods, 103 C. cottoides from six broods, and 63 M. dorsalis from five broods. The presence of multiple mating by females was assessed by maximum-likelihood sibship reconstruction implemented in the program COLONY, and the non-random distribution of reproductive success among individuals (reproductive skew) within broods was tested using the binomial skew index. Multiple mating by females was pervasive and observed in 83%, 100% and 80% of the broods of C. superciliosus, C. cottoides and M. dorsalis, respectively. The mean number of sires per brood was 4.3, 3.0 and 3.2, and, correspondingly, 5/5, 5/6 and 1/4 of multiply-sired broods showed significant reproductive skew in C. superciliosus, C. cottoides and M. dorsalis, respectively. The presence of pronounced reproductive skew may indicate post-copulatory processes taking place that bias paternity. We compared our results on multiple mating within the klipfish family, and with four other fish families that have vivipary with superfetation, and found the klipfish patterns were among those of live-bearing vertebrate groups with the highest average numbers of sires per brood. 相似文献