环境污染对林木群体遗传的影响

大气污染引起林木种群遗传性改变的综述主要集中在:1)选择过程的研究方法;2)选择结果的适当试验与贡献的描述;3)自然选择的结果:遗传多样性的损失;4)种源试验结果的比较;5)保存遗传多重性(genetic multiplicity)的结果;6)关于森林面积减少机制的假说讨论。本文总结了有关云杉属、松属、杨属和桦属的试验结果及结论,并提出了有待进一步研究的内容。

Genetic diversity analysis with ISSR PCR on green algae Chlorella vulgaris and Chlorella pyrenoidosa

In the present study, genetic polymorphism and diversity in unicellular clones of Chlorella vulgaris Beijerinck and Chlorella pyrenoidosa Chick were studied with Inter Simple Sequence Repeats PCR （ISSR PCR）. Samples including four clones of C. vulgaris and three clones of C. pyrenoidosa were purified by single-clone-choice method. For four C. vulgaris unicellular clones, the total number of the bands scored for 18 primers was 298; and the number of the polymorphic bands was 118, of which 39.6% were polymorphic. The size of PCR products ranged from 200 to 2 500 bp. The total number of bands scored for 18 primers, the number of polymorphic bands and the percentage of three C. pyrenoidosa unicellular clones was 194.83 and 30.8%, respectively. POPGENE analysis show that the average Nei genetic diversity （h^＊） and Shannon index of diversity （I^＊） in the four C. vulgaris unicellular clones was 0.2181 and 0.3208, respectively, which is slightly higher than those of the three C. pyrenoidosa unicellular clones （0.190 3 and 0.274 8）, which agreed with the percentage of polymorphic bands in the mixed samples of the two species. The results suggest that ISSR is a useful method to Chlorella for intra-species genetic analysis.

Correlation and path analysis of morphological and weight traits in marine gastropod Glossaulax reiniana

Using correlation and path analysis, the genetic correlation between weight traits and morphological traits was determined in the marine gastropod Glossaulax reiniana. A total of 100 G. reiniana individuals from a wild population were used. Shell width （X1）, shell height （X2）, umbo-callus height （X3）, body width （X4）, operculum length （X5）, operculum width （X6）, body weight （Y1） and soft-tissue weight （Y2） were measured, and the correlation coefficient matrix calculated. Morphological traits were used as independent variables and weight traits as dependent variables for path coefficient analysis. Path coefficients, correlation indices and determination coefficients were also determined. Results indicate that the correlation coefficients associated with each morphological and weight trait were all highly significant （P〈0.01）. After deleting redundant independent variables, the following optimum multiple regression equations were obtained using stepwise multiple regression analysis： Y1=-29.317＋0.362X2＋0.349X4＋ 1.190）（5 for body weight; and Y2=-17.292＋0.166X1＋0.171X2＋0.703X5, for soft-tissue weight. Operculum height had the highest positive direct correlation with both body weight and soft-tissue weight, which was in accordance with the test results obtained from determinate coefficient analysis. The indication of high genetic correlations between weight traits and morphological traits will provide valuable information for G. reiniana breeding programs.

Solving Hitchcock’s transportation problem by a genetic algorithm

Genetic algorithms (GAs) employ the evolutionary process of Darwin’s nature selection theory to find the solutions of optimization problems. In this paper, an implementation of genetic algorithm is put forward to solve a classical transportation problem, namely the Hitchcock’s Transportation Problem (HTP), and the GA is improved to search for all optimal solutions and identify them automatically. The algorithm is coded with C++ and validated by numerical examples. The computational results show that the algorithm is efficient for solving the Hitchcock’s transportation problem.

Advance of Study on SSR Molecular Marker in Citrus and Its Close Relatives

Simple sequences repeat （SSR） molecular maker, as a new type of DNA molecular marker, the second generation based on the polymerase chain reaction （PCR）, is valuable and of great potential as genetic markers for its characteristics of abundant quantity, high polymorphic, reproducibility, specific site amplification, high occurring frequency, and co-dominant inheritance etc. This paper outlined its principles and characteristics, and introduced its application to variety identification, phylogenetic relationship analysis, genetic diversity analysis, DNA fingerprinting and linkage map constructing etc. in recent years in Citrus and its close relatives.

Development of 107 SSR markers from whole genome shotgun sequences of Chinese bayberry(Myrica rubra) and their application in seedling identification

Chinese bayberry （Myrica rubra Sieb. et Zucc.） is one of the important subtropical fruit crops native to the South of China and Asian countries. In this study, 107 novel simple sequence repeat （SSR） molecular markers, a powerful tool for genetic diversity studies, cultivar identification, and linkage map construction, were developed and characterized from whole genome shotgun sequences. M13 tailing for forward primers was applied as a simple method in different situations. In total, 828 alleles across 45 accessions were detected, with an average of 8 alleles per locus. The number of effective alleles ranged from 1.22 to 10.41 with an average of 4.08. The polymorphic information content （PIC） varied from 0.13 to 0.89, with an average of 0.63. Moreover, these markers could also be amplified in their related species Myrica cerifera （syn. More/la cerifera） and Myrica adenophora. Seventy-eight SSR markers can be used to produce a genetic map of a cross between ＇Biqi＇ and ＇Dongkui＇. A neighbor-joining （N J） tree was con- structed to assess the genetic relationships among accessions, and the elite accessions ＇Y2010-70＇, ＇Y2012-140＇, and ＇Y2012-145＇, were characterized as potential new genotypes for cultivation.

Progress in understanding epigenetic remodeling during induced pluripotency

Over 50 years of efforts, cellular reprogram- ruing opens a new door for disease modeling and regen- erative medicine. Although induction of pluripotency by transcription factors has become common, only a small portion of basic mechanisms of epigenetic modifications during this process have been revealed. To clearly under- stand reprogramming and devise ways to promote full transition towards pluripotency, we must gain insight from comprehensive characterizations of cells at distinct repro- gramming stages, which involves gene expression profil- ing, chromatin state maps of key activating and repressive marks, and DNA modifications. Here, we review recent advances in epigenetic reprogramming to pluripotency with a focus on the principal molecular regulators and attach importance to the combination of high-throughput sequencing and systematic biology approaches in uncov- ering underlying molecular mechanisms of this unique platform in future researches.

Rapid generation of genetic diversity by multiplex CRISPR/Cas9 genome editing in rice

The clustered regularly interspaced short palindromic repeats(CRISPR)-associated endonuclease 9(CRISPR/Cas9) system has emerged as a promising technology for specific genome editing in many species. Here we constructed one vector targeting eight agronomic genes in rice using the CRISPR/Cas9 multiplex genome editing system. By subsequent genetic transformation and DNA sequencing, we found that the eight target genes have high mutation efficiencies in the T_0 generation. Both heterozygous and homozygous mutations of all editing genes were obtained in T_0 plants. In addition, homozygous sextuple, septuple, and octuple mutants were identified. As the abundant genotypes in T_0 transgenic plants, various phenotypes related to the editing genes were observed. The findings demonstrate the potential of the CRISPR/Cas9 system for rapid introduction of genetic diversity during crop breeding.