阿维菌素高产菌的诱变育种研究

[目的]选育B1a组分较高的阿维菌素高产菌株。[方法]通过紫外线-氯化锂(LiCl)和紫外线-亚硝基胍(NTG)对阿维链霉菌N-5-6进行了复合诱变处理。[结果]以1.00 mol/L的LiCl和60s的紫外线照射时间以及以45 s的UV照射时间和0.8 mg/ml的NTG浓度分别对出发菌株进行复合诱变处理,通过筛选得到13株总效价比出发菌株提高了20%以上的突变株,经HPLC检测,其中7株B1a组分含量较高,均在45%以上。菌株H02180的B1a含量达到了51.35%,比出发菌株N-5-6的B1a含量提高了65.1%;菌株H02108的B1a含量达到了51.26%,比出发菌株N-5-6的含量提高了64.8%。[结论]采用紫外线和氯化锂、紫外线和亚硝基胍这2种复合诱变方法对于阿维链霉菌的高产菌株的选育是有效的。     

家蚕基因库突变系统的研究

 经过十几年的研究 ,整理了包括最早于 2 0世纪 4 0年代 ,尤其是 80年代后期以来收集、引进、创造的家蚕各种突变基因、染色体变异系统及特色遗传材料 10 0 0余份 ,通过对其进行形态、生理、生化性状的鉴定和遗传分析 ,构建和完善的保存系统有 6 0 0余个家蚕基因的资源库 ,保存的家蚕突变基因种类覆盖国际现存家蚕突变基因的 90 %以上。其中珍稀突变基因达 10 0多个 ,首次发现的突变基因 6 0余个。通过对突变系统进行杂交分析 ,连锁检索和三点测验定位 ,构建了完善的家蚕连锁检索标记体系 ,含全部 2 8个连锁群的标志基因有 2 30个 ;构建了各连锁群的基因定位系统 (隐性基因合成系 ) ;发现了基因互补突变卵色和第三型母性遗传卵色 ,发现了白色卵突变基因上位作用的普遍性。育成了以形态突变基因为标记的、相互独立的近等基因系 2 8个。开发了高饲料效率、性别标记、天然有色茧丝、抗病性、广食性、可控制单性别孵化等一系列有重大应用前景的有用突变基因育种新素材。建立了较为完善的家蚕基因资源持续保存的方法和管理技术体系。     

不同羽色鸽种MC1R基因的扩增与序列分析

黑素皮质素受体1(Melanocortin-1 Receptor,MC1R)是一种7跨膜结构G蛋白耦联受体,在鸟类羽色形成中起着重要作用。为探讨MC1R对太湖鸽特殊羽色形成的影响,本实验利用PCR和直接测序法对太湖鸽、乌鸽和白卡奴鸽MC1R基因编码区进行扩增,并对不同鸽种MC1R基因序列进行差异性分析。结果表明:鸽MC1R基因编码区全长942 bp,共编码313个氨基酸,存在7个跨膜结构;白卡奴鸽与乌鸽的MC1R基因编码区核酸序列基本一致,黑羽和棕羽太湖鸽的MC1R基因序列没有差异,而太湖鸽与其他2个鸽种分别于279bp(A>G)和520bp(G>A)处存在碱基差异,其中G520A造成了氨基酸(Ser174Gly)的改变,推测该位点突变与太湖鸽特殊羽色形成有关。     

Quantitative variation as a tool for detecting human-induced impacts on genetic diversity

We propose quantitative genetic variation as a useful tool complementary to molecular variation in order to detect changes in biodiversity caused by different human-induced activities. We simulated a metapopulation setting under a number of realistic scenarios caused by anthropogenic activities (population isolation, reduced carrying capacity or reproductive rates, shifts in the local optima, and enhanced environmental variation or mutational rates). The effects on diversity of these scenarios were assessed for neutral variation estimated from molecular markers and for an additive quantitative trait that represents a typical morphological characteristic subject to stabilising selection promoting local adaptation to environmental conditions. The results show that monitoring quantitative genetic variation can be more informative than neutral variation to detect some human-induced environmental or genetic impacts on diversity, both at intra and interpopulation levels. We also compared the precision of diversity estimates obtained from molecular markers and quantitative traits. Under low migration rates and typical selection intensities for the quantitative trait, the precision of estimates can be substantially larger for a quantitative trait than for a single molecular marker. Thus, about 10-20 (2-4) independent markers are necessary for the precision of estimates of heterozygosity (population differentiation) from molecular markers to reach that of genetic variances (differentiation) from quantitative traits.     

Comparison of symbiotic effectiveness of Rhizobium sp. with positive hydrogen-uptake activity compared with negative mutants in relation to nitrogen fixation in mungbean (Vigna radiata L.)

H₂ uptake activity was well distributed in Rhizobium sp. strains isolated from nodules of mung-bean (Vigna radiata L.). Two effective strains, RMP1 und RMP2, exhibiting significantly higher H₂ uptake activity were subjected to mutagenesis with nitrosoguanidine. The respective mutation frequencies were 0.18 and 0.19%. Three Hup^- mutants each of RMP1 und RMP2 were compared with the wild-type parent strains under pot culture experiments to evaluate the significance of the H₂ uptake system in biological N₂ fixation. Nodulation capabilities, plant growth characteristics, and the chlorophyll content of the leaves were significantly reduced in the plants treated with Hup^- mutants. Nitrogenase activity in Hup^- nodules was reduced by 8–41%. Similarly, N accumulation was also reduced singificantly.     

西安地区温度时空变化特征

对西安市各区县观测站1970 ～2013年的地面温度资料进行统计分析,从西安各区县的气温年变化、季变化、月变化以及突变检验等方面分析西安地区温度时空变化特征.结果表明,西安地区是增温明显的.1994年为全市年平均气温突变年,2000年全市年平均气温突变增高达最大值,趋势越来越明显,近44年存在显著的24年长周期变化震荡.     

贵州乌蒙烟区烤烟生育期气候因子变化特点分析

利用贵州乌蒙烟区1961~2000年的气温、日照时数、降雨量等主要气候因子数据,分析了烤烟生育期气候指标的变化特点,结果表明:乌蒙烟区光照充足、降雨丰富、气温相对偏低,但气温年际间相对稳定,光照和降雨量在不同年份间存在较大波动。线性趋势分析表明:旺长期(6月)气温呈现较显著的上升趋势,成熟初期(7月)气温显著下降;烤烟生育期每月日照时数呈减少趋势,其中成熟初期(7月)的日照时数减少趋势显著;降雨量在5月、6月呈减少趋势,7月、8月呈增加趋势,生育期每月降雨量的线性变化趋势未达到显著水平。突变检验表明:40年来该烟区烤烟生育期气温在1998年发生了明显突变,日照时数在1985年发生了明显突变,降雨量未发生明显突变。     

半滑舌鳎体色白化相关突变位点的鉴定

本研究对体色相关通路基因的9个错义突变位点进行了测序调查,在体色黑化、体色白化、和体色正常的半滑舌鳎小样本群体中,发现其中3个突变位点与体色白化存在显著性相关,进一步通过扩大样本验证,显示B型内皮素受体第160位的C/T位点(ertB-160-C/T)与体色白化呈极显著性相关（P<0.01）,酪氨酸酶第473的G/A位点（tyr-473-G/A）和花生四烯酸5-脂氧合酶的第1178位的C/T位点（alox5-1178-C/T）与体色白化呈显著性相关（P<0.05）。此外,这三个突变位点分别位于蛋白Periplasmic_Binding_Protein_type1、Tyosinase C-terminal和Lipoxygenase结构域。qRT-PCR检测表明,ertB在白化半滑舌鳎中有眼侧不同颜色区域的皮肤表达没有显著差异（p>0.05）,而在无眼侧皮肤中的表达明显高于有眼侧皮肤（p<0.01）。在白化半滑舌鳎中tyr在有眼侧色素部分和非色素部分的表达水平均显著高于无眼侧（p<0.01）。此外,白化半滑舌鳎中无眼侧alox5的表达水平均显著高于有眼侧（p<0.05）,有眼侧白化区alox5的表达水平明显高于有眼侧白色皮肤（p<0.01）,首次鉴定出与半滑舌鳎养殖群体体色白化相关的突变位点,为今后半滑舌鳎的体色选育提供了分子基础。     

1960—2013年甘肃省气温、降水变化特征分析

为了研究近54年来甘肃省气候变化特征,根据甘肃境内28个气象站1960—2013年温度、降水数据,利用气候趋势分析、气候突变分析及Morlet小波分析等,分析甘肃省近54年来气温、降水变化特征。结果表明:(1)近54年来甘肃省的年均温总体呈上升趋势,年均降水量的总体上呈微弱增加趋势。(2)甘肃省中部地区处于暖湿化过程,而南部地区处于暖干化过程,北部地区仍然处于干旱化。(3)年均温在1994年前后出现明显的突变点,年均降水量正反序列曲线均未超过95%置信度线,但正反序列曲线在置信度区间内存在1个交叉点,出现在1993—1994年之间,有可能在1993—1994年发生突变;(4)Morlet小波分析显示,甘肃省年均温存在8年左右的显著变化周期,年均降水量的周期性较差。     

Conservation consequences of Chernobyl and other nuclear accidents

The explosion at the Chernobyl nuclear power plant on 26 April 1986 released vast amounts of radioactive material over an area of 200,000 km² in eastern and central Europe, affecting all living organisms. The biological impacts including the conservation consequences of this event are still poorly known even 25 years after the disaster. Here we assess the effects of this environmental disaster for conservation by focusing on two connected questions addressing the short-term ecological and the long-term evolutionary consequences: First, we pose the question of whether rare species are more impacted by radiation than common species? Second, what are the conservation consequences of elevated mutation rates due to the mutagenic effects of radionuclides from Chernobyl? Furthermore, we assess the extent to which ecological and evolutionary aspects interact. We censused breeding birds across 731 census points in Ukraine and Belarus during 3 years to assess the relationship between abundance of different species and radiation. Most bird species avoided contaminated sites and individuals were concentrated in relatively uncontaminated sites. While common species were recorded at a wide range of radiation levels, rare species were restricted to the least contaminated sites and to sites with a high biodiversity. Thus, rare species were disproportionately impacted by the accident. Mutation rates of plants and animals have increased by up to a factor 20 due to release of radionuclides from Chernobyl. Given that each slightly deleterious mutation is expected to result in a selective genetic death, and that an average fruitfly under normal conditions may carry as many as 80 mutations, the number of mutations in animals and plants around Chernobyl and hence the number of selective deaths is bound to be much higher. There is empirical evidence for highly elevated mortality rates and dramatically increased rates of reproductive failure in contaminated areas, consistent with the expected high frequency of selective deaths due to mutations. The average slightly deleterious mutation is present for 33–167 generations in Drosophila, so if these estimates are qualitatively similar in other organisms, we can expect that mutants will disperse outside contaminated areas resulting in the spread of mutations well beyond the reach of contamination with radionuclides. Therefore, it should be possible to document the gradual spread of mutations from Chernobyl. We consider that the Chernobyl disaster and other nuclear releases may have significant consequences for population size and population viability of many species due to the large number of selective deaths. These effects remain to be investigated. Finally, comparative analyses of birds revealed that species with high mitochondrial DNA substitution rates had short dispersal distances, suggesting that mutations will spread relatively short distances when they are common, but will spread longer distances in species when they are rare.