鄂托克前旗近50年降水变化特征分析

本文利用鄂托克前旗1967-2018年气象观测站近50年的气象资料,对鄂托克前旗降水特征进行分析。结果表明：整体来说，鄂托克前旗的年降水量变化呈现微弱降低趋势，每10a大约减少1.2mm；28a时间尺度决定的主周期控制着该地区的年降水变化特征，通过周期和突变分析，预计未来三年左右降水高于多年平均值，随后的14年左右时间内降水量呈现减少趋势，逐渐低于多年平均降水量。     

Evolutionary characteristics of morbilliviruses during serial passages in vitro: Gradual attenuation of virus virulence

The genus Morbillivirus is classified into the family Paramyxoviridae, and is composed of 6 members, namely measles virus (MV), rinderpest virus (RPV), peste-des-petits-ruminants virus (PPRV), canine distemper virus (CDV), phocine distemper virus (PDV) and cetacean morbillivirus (CeMV). The MV, RPV, PPRV and CDV have been successfully attenuated through their serial passages in vitro for the production of live vaccines. It has been demonstrated that the morbilliviral virulence in animals was progressively attenuated with their consecutive passages in vitro. However, only a few reports were involved in explanation of an attenuation-related mechanism on them until many years after the establishment of a quasispecies theory. RNA virus quasispecies arise from rapid evolution of viruses with high mutation rate during genomic replication, and play an important role in gradual loss of viral virulence by serial passages. Here, we overviewed the development of live-attenuated vaccine strains against morbilliviruses by consecutive passages in vitro, and further discussed a related mechanism concerning the relationship between virulence attenuation and viral evolution.     

How to maintain improved cultivars

Improved cultivars loose their identity and healthiness unless maintained properly. Contaminating and degrading forces, such as outcrossing, volunteer plants, mixing, natural selection, mutation and seed-borne diseases, are at the root of this. Maintenance selection can prevent this deterioration. How it is carried out depends on the reproduction system of the crop. Crops are therefore classified into four categories; typical cross-pollinating crops, self-pollinating crops with a substantial amount of outcrossing, typical self-pollinating crops with little outcrossing, and the vegetatively reproduced crops. Generally some of the “breeder seed” is used to plant a small plot with spaced plants. A fair number of healthy plants of the cultivar type is selected and the seed is harvested per plant. The progenies of the selected plants are grown in small plots. Non-uniform or deviating plots and plots with a seed-borne disease are removed. The seed of the progenies that are healthy, uniform and similar (and so of the cultivar type) are harvested per progeny to be tested next season on larger plots. The same selection is applied and only the seed of the progenies that are healthy, uniform and similar are harvested together to produce the “breeder seed”. The details of this maintenance selection vary with the reproduction system, the multiplication rate of the crop and the possibilities available to the breeder. Seven crops, potato, common bean, barley, wheat, faba bean, quinoa and maize are discussed here as they represent the different reproduction systems and multiplication rates, while being important Andean food crops.     

Mutation Techniques for Gene Discovery and Crop Improvement

One of the most important breakthroughs in the history of genetics ）was the discovery that mutations can be artificially induced in organisms （van Harten, 1998）. Artificially induced mutations, by physical and chemical mutagens, have greatly advanced the understanding of genetics of higher organisms. Starting in the late 1960＇s, the International Atomic Energy Agency （IAEA） and the Food and Agriculture Organization （FAO） of the United Nations sponsored extensive research on mutation induction and their application to breeding of food and indnstrial crops that resulted in the introduction of new varieties of rice, wheat, barley, apples, citrus, sugar cane, banana, and others （more than 2 500 officially released new varieties are to be found in the FAO/IAEA Mutant Varieties Database） （hitp：//www-mvd.iaea.org/MVD/default.htm）. However, the usefulness of mutation techniques has been underappreciated in research communities, particularly during the last decade, when more and more researchers and breeders were rushing into molecular marker techniques and transgenic plants. In this paper, after a brief review of the past accomplishments of mutation induction and its application, we discuss the uniqueness of induced mutations in gene discovery and how to integrate induced mutants into functional genomics programs;     

TILLING and Ecotilling the Plant Kingdom

The modem crop scientist has a large amount of available nucleotide sequence information to identify genes of potential agronomic importance. Using reverse genetic approaches, specific genes can be disrupted, and hypotheses regarding gene function directly tested in vivo. Although a number of reverse genetic methods have been introduced, many are limited in application because they are organism-specific, expensive, transgenic, or only transiently disrupt gene function. However, traditional mutagenesis using chemical mutagens has been widely used as a forward genetics strategy to create many new crop plant varieties at relatively low cost. Mutagens such as ethyl methanesulphonate （EMS） cause stable point mutations and thus produce an allelic series of truncation and missense changes that can provide a range of phenotypes （Greene et al., 2003）. TILLING （targeting induced local lesions IN genomes） is a high-throughput reverse genetic strategy that combines traditional mutagenesis and SNP discovery methods （Colbert et al., 2001; McCallum et al., 2000）. To identify mutations, target regions of-l.5 kb are amplified with fluorescently labeled gene specific primers. Heteroduplexes are then formed between wild-type and mutant strands, mismatches are cleaved by incubation with a single-strand specific nuclease,     

Evaluation of genetic architecture and mutation drift equilibrium of Marathwada buffalo population in Central India

In the present study, microsatellite data on 24 loci were generated and utilized to evaluate the genetic architecture and mutation drift equilibrium of Marathwada buffaloes, a Central Indian population maintained under low input system. Sufficient allelic diversity was observed with a total of 109 alleles across different loci. The genetic diversity analysis of Marathwada buffaloes displayed moderate level of within breed variability in terms of mean number of alleles per locus (4.48) and heterozygosity values (Ho = 0.532, He = 0.624). The studied Indian buffalo population showed considerable heterozygote deficiency (F_IS = 0.138) and deviation from HWE at many investigated loci. Three quantitative tests viz. sign test, standardized difference test and Wilcoxon sign rank test and a qualitative test for mode shift distortion of allelic frequencies were employed to evaluate mutation drift equilibrium under three different models of microsatellite evolution. The population was found to deviate significantly under IAM and TPM, while it was reverse under SMM. The qualitative test for mode shift supported the results under SMM indicating the absence of genetic bottleneck in the recent past in Marathwada buffaloes.     

粤西籍人群Fv Leiden基因突变的初步调查

了解ＦｖＬｅｉｄｅｎ基因突变在广东籍正常人群中发生的情况。方法：用两种引物多聚酶链反应方法检测１３０例广东雷州籍正常人和３例静脉血栓患者ＦｖＬｅｉｄｅｎ基因突变情况，结果所有的样本均未检出ＦｖＬｅｉｄｅｎ突变。结论粤西籍正常人中尚未发现ＦｖＬｅｉｄｅｎ突变。     

猕猴桃辐射诱变效应的初步研究

用60Co-γ射线处理"和平红阳"和"和平一号"2个猕猴桃品种幼芽,并在猕猴桃成株上进行高位嫁接,对其辐射效应进行初步研究.结果表明:嫁接萌芽率变化的一般趋势是随着辐射剂量的加大而降低;随辐射强度的增加,使萌发芽的死亡率加大,导致最终成活枝的比例降低.参试品种的半致死剂量在50～75 Gy之间.辐射在引起猕猴桃幼芽生理损伤的同时,亦会诱发性状变异.2个品种的茎长、叶柄长、叶片宽等性状50 Gy处理和CK间的差异均达到显著水平,2 a试验取得一致的结果.而茎直径和叶片长度,不同品种及不同年份的表现不同.辐射处理会提高性状的变异系数,增加性状的变异度,为选择提供更丰富的变异材料.表明辐射诱变在猕猴桃品种改良中有重要的研究应用价值.     

菊花辐射诱变育种研究进展

综述了辐射诱变的方法及变异机理,探讨了当今菊花产业中辐射诱变的发展方向,提出了以辐射诱变、组培和分子标记相结合的复合育种的思路。