Novel microsatellite markers for the saltmarsh sharp-tailed sparrow, Ammodramus caudacutus (Aves: Passeriformes)

We have developed eight high-quality microsatellite DNA loci for the saltmarsh sharp-tailed sparrow and one additional locus with evidence of null alleles. In a sample of 250-350 individuals, the average number of alleles per locus was 14.7 and average observed heterozygosity was 0.80. These loci were tested in three additional species of emberizid sparrows, indicating that more than half of the loci could be useful in other sparrows.     

引起石榴枯萎病和甘薯黑斑病的甘薯长喙壳菌菌株生物学特性的比较研究

采用菌丝生长速率法对引起石榴枯萎病和甘薯黑斑病的甘薯长喙壳菌的形态特征,及其在不同培养基、光照、温度、pH值等基本培养条件下菌丝的生长速率等生物学特性的差异进行了比较研究。结果表明,在不同处理培养条件下,石榴枯萎病菌生长速度均快于甘薯黑斑病菌,其菌落形态存在较大差异。二者在甘薯葡萄糖培养基(SPDA)上生长速率最快。在黑暗条件下的生长速率比12h光暗交替、光照处理显著增大。二者最适生长温度皆为25℃,石榴枯萎病菌菌丝生长温度范围为10-36℃,而甘薯黑斑病菌的菌丝生长温度范围为10-33℃。二者菌丝在pH4-12范围内均能生长,最适pH值为6。石榴枯萎病菌菌丝的致死温度为50℃处理10min或52℃处理5min,甘薯黑斑病菌菌丝的致死温度为48℃处理10min或50℃处理5min。二者在完全培养液中产孢量最大,菌丝生长速率随培养基中葡萄糖浓度的减小而增大。     

四川石榴枯萎病的病原菌

2009年在四川省攀西地区的石榴上发现一种毁灭性的新病害,且有逐年加重危害的趋势,已对石榴生产造成了巨大威胁。通过对发病植株的症状观察,病原菌的分离培养和显微形态特征观察,rDNA-ITS序列分析,及致病性测定,最后确定该病害是由甘薯长喙壳Ceratocystis fimbriata 侵染引起的。该病害在印度和中国云南蒙自石榴产区曾有发生报道,但在四川省石榴产区为首次报道。     

落叶松八齿小蠹体内外和坑道内真菌类群

采集落叶松八齿小蠹成虫、幼虫、蛹,以及母坑道、子坑道、蛹室的韧皮组织和蓝变组织。采用马丁氏培养基和PDA综合培养基对各虫态体表、体内、坑道内真菌进行分离培养,统计真菌检出率。对获得的真菌菌株通过形态学和分子生物学相结合的方法进行鉴定。在落叶松八齿小蠹虫体内外和坑道内共分离出真菌31种,其中接合菌3种,子囊菌8种,担子菌1种,半知菌19种。自各虫态体表共分离出真菌23种,体内共分离出真菌8种,31种真菌在坑道内均有检出。其中,Ceratocystis fujiensis为中国新记录种,Ophiostoma     

A simple PCR procedure for discovering microsatellites from small insert libraries

Microsatellite discovery from genomic libraries is tedious because of the low number of clones that contain inserts and costly because of screening methodologies. A new procedure for screening clones for microsatellite DNA is described herein. Instead of colony hybridization, a polymerase chain reaction (PCR) with two vector standard primers and one synthesized repeat primer was used to directly screen colonies. PCR of colonies that produced a strong smear in gels contained the desired motif, whereas a single strong band indicated the lack of the desired motif. This simple screening method is a cost‐effective way to identify microsatellite‐containing colonies.     

黑龙江省长白落叶松八齿小蠹虫体及坑道的真菌类群

采集落叶松八齿小蠹成虫、幼虫、蛹,以及母坑道、子坑道、蛹室的韧皮组织和蓝变组织。采用马丁氏培养基和PDA综合培养基对各虫态体表、体内、坑道内真菌进行分离培养,统计真菌检出率。对获得的真菌菌株通过形态学和分子生物学相结合的方法进行鉴定。在落叶松八齿小蠹虫体内外和坑道内共分离出真菌24种,其中子囊菌7种,担子菌2种,无性型真菌15种。从各虫态体表共分离出真菌21种,从体内共分离出真菌6种,24种真菌在坑道内均有检出。其中,Ceratocystis fujiensis为检出率较高的蓝变真菌。     

Microsatellite markers for Sachalin fir (Abies sachalinensis Masters)

We developed eight polymorphic microsatellite markers from the Sachalin fir (Abies sachalinensis Masters). The number of alleles per locus ranged from eight to 31, with an average of 21.4. The observed and expected heterozygosities ranged from 0.656 to 0.937 and from 0.710 to 0.945, respectively. These markers will be available for population genetic studies and parentage analysis.     

Development of microsatellite markers for noninvasive DNA samples of the eastern green lizard Lacerta viridis

We report the isolation and characterization of microsatellite markers for the eastern green lizard (Lacerta viridis) usable for noninvasive samples. Ten polymorphic loci were obtained by screening 3000 recombinant clones and tested on 39 noninvasive DNA samples of individuals from different locations of the Danube area, Germany. Allelic richness ranged from three to nine alleles, the observed heterozygosity from 0.33 to 0.80, and the expected heterozygosity from 0.36 to 0.85. Our 10 loci, along with another 12 loci previously described, deliver effective analytical tools to analyse the genetic variability and to assess the social structure of eastern green lizard populations.     

Development of highly conserved primers for 12 new polymorphic microsatellite loci for the genus Rorippa Scop. (Brassicaceae), yellow‐cress

We isolated 12 highly conserved polymorphic microsatellite loci for the yellow‐cress species Rorippa amphibia and Rorippa sylvestris. We used a partial genomic library enriched for several repeat motifs. Obtained sequences containing repetitive elements were blasted and aligned with the Arabidopsis thaliana sequence. We evaluated the cross‐species compatibility of primers designed from sequences either aligning strongly or weakly with A. thaliana. The former proved much more efficient in obtaining primers that worked in both species. The developed conserved primers for microsatellite loci provide excellent markers for studying segregation, gene flow and hybridization in the genus Rorippa.     

Hypermutability of genes in Homo sapiens due to the hosting of long mono-SSR

Simple sequence repeats (SSRs) are very common short repeatsin eukaryotic genomes. "Long" SSRs are considered "hypermutable"sequences because they exhibit a high rate of expansion andcontraction. Because they are potentially deleterious, longSSRs tend to be uncommon in coding sequences. However, severalgenes contain long SSRs in their exonic sequences. Here, weidentify 1,291 human genes that host a mononucleotide SSR longenough to be prone to expansion or contraction, being calledhypermutable hereafter. On the basis of Gene Ontology annotations,we show that only a restricted number of functions are overrepresentedamong those hypermutable genes including cell cycle and maintenanceof DNA integrity. Using a probabilistic model, we show thatgenes involved in these functions are expected to host longSSRs because they tend to be long and/or are biased in nucleotidecomposition. Finally, we show that for almost all functionswe observe fewer hypermutable sequences than expected undera neutral model. There are however interesting exceptions, forexample, genes involved in protein and RNA transport, as wellas meiosis and mismatch repair functions that have as many hypermutablegenes as expected under neutrality. Conversely, there are functions(e.g., collagen-related genes) where hypermutable genes aremore often avoided than in other functions. Our results showthat, even though several functions harbor unusually long SSRin their exons, long SSRs are deleterious sequences in almostall functions and are removed by purifying selection. The strengthof this purifying selection however greatly varies from functionto function. We discuss possible explanations for this intriguingresult.