Gene survival in the Asian wild horse (Equus przewalskii): I. Dependence of gene survival in the calgary breeding group pedigree

The joint probability distribution of the number of distinct (not identical by descent) genes from each founder of the Equus przewalskii population that survive in the five horses of the Calgary Zoological Gardens breeding group has been calculated. The dependence structure of this distribution is investigated, and informative marginal distributions are given, among them the distributions of the genetic contributions of each founder to the Calgary horses and the distribution of wild-type genes in these horses. The dependence pattern is found to be complex; there is no substitute for exact calculation of the full joint probability distribution of numbers of surviving genes. Probabilities of gene survival give a more complete summary of the genetic structure of a set of individuals than is provided by more routine measures such as heterozygosity or founder contributions. The feasibility of computing these probabilities for small groups of current individuals descended from few founders via long and complex pedigrees, provides a new approach to assessing such groups, and could be used also in selecting animals to form the founder stock of propagules for future reintroduction programs.     

Molecular cloning,nucleotide sequence and expression of a cDNA encoding an intracellular protein tyrosine phosphatase,PTPase-2, from mouse testis and T-cells

The PTP-2 cDNA encoding an intracellular protein tyrosine phosphatase (PTPase-2) was isolated and sequenced from mouse testis and T-cell cDNA libraries. This PTP-2 cDNA was found to be homologous to human PTP-TC and rat PTP-S, and contained 1,551 nucleotides, including 1,146 nucleotides encoding 382 amino acids as well as 5 (61 nucleotides) and 3 (344 nucleotides) non-coding regions. Northern blot analysis indicated that PTP-2 mRNA of 1.9 Kb was most abundant in testis and kidney, although it was also present in spleen, muscle, liver, heart and brain.Abbreviations PTPase Protein Tyrosine Phosphatase (EC3.1.3.48) - PTKase Protein Tyrosine Kinase (EC2.7.1.112)     

DNA extraction for 16S rRNA gene analysis to determine genetic diversity in deep sediment communities

A protocol was devised which permitted the extraction of DNA from deep marine sediments up to 503 m below the sea floor. These sediments have been laid down over the last 3 million years. 16S rRNA gene sequences were amplified from the DNA by the polymerase chain reaction. The details of the successful extraction and polymerase chain reaction methodology varied between samples from different depths. This emphasizes the attention to detail required to allow the diversity of bacteria in these deep sediments to be studied.     

Structure and expression of a gene from Arabidopsis thaliana encoding a protein related to SNF1 protein kinase

The AKin10 gene from Arabidopsis thaliana encoding a putative Ser/Thr protein kinase (PK) has been isolated and characterized. The AKin10-encoding gene is located on a genomic 5.4-kb BamHI fragment and contains ten introns, one being located in the 5' untranslated region. The deduced amino acid sequence of AKin10 is 65% identical over the catalytic domain to the yeast PK (SNF1). SNF1 is essential for the derepression of many glucose-repressible genes, including Suc2 which encodes invertase. Southern blot hybridization experiments suggested the presence of one copy of the gene per haploid genome of A. thaliana. Northern hybridization experiments indicated that this gene is expressed in roots, shoots and leaves. AKin10 may play an important role in a signal transduction cascade regulating gene expression and carbohydrate metabolism in higher plants.     

Gene variation and gene flow inOrchis morio (Orchidaceae) from Italy

Data are presented on genetic variation at 27 enzyme loci of the Green-Winged orchid,Orchis morio, in 18 population samples from Italy. The existence in Italy of two subspecies, i.e. subspp.morio andpicta, is not supported by allozyme data. No genetic heterogeneity was found betweenmorio-like andpicta-like samples and specimens. Moreover, morphological transition between the two forms was observed in different Italian populations. The parameters of genetic variability estimated forO. morio populations are consistent with those found among monocotyledon plants, and among those outcrossing, animal-pollinated and with wind-dispersed seeds. Genetic diversity of ItalianO. morio is mostly within populations. Correspondingly, low values of interpopulational genetic distance were found. This appears to be due to high levels of gene flow, which were estimated with different methods. The lack ofO. longicornu from Italian samples, as well as of any hybrid withO. morio (F₁, backcrossed or recombinant individuals) is demonstrated on the basis of genetic data. It is concluded that recurrent reports ofO. longicornu from Italy are due to confusion withO. morio or with otherOrchis species.     

马铃薯Y病毒外壳蛋白基因的克隆及序列分析

本文报道应用聚合酶链式反应(PCR)技术,在体外扩增马铃薯 Y 病毒外壳蛋白基因及其克隆和序列分析的结果。病毒 RNA 从马铃薯 Y 病毒感染的烟草叶片中提取,用合成的PCR 3引物及 AMV 逆转录酶合成了单链的 cDNA。利用 PCR 技术,经30个循玎的扩增。得到了一特异的0.8kb 片段。克隆后对此片段进行了限制性内切酶物理图谱分析,并测定了其全序列。实验结果证明,我们克隆到的是完整的马铃薯 Y 病毒的外壳蛋白基因。与国外报道的马铃薯 Y 病毒 N 株相比,其核苷酸序列及推测的氨基酸序列的同源率分别为97.8%和97%。将该基因导入马铃薯以期获得抗 Y 病毒马铃薯的工作正在进行。本文还对 PCR 技术用于扩增植物 RNA 病毒的方法以及用基因工程方法培育抗病毒作物新品种的可行性等进行了讨论。     

Extraction and partial characterization of non-histone nuclear proteins of Schistosoma mansoni.

A pool of nuclear proteins from adult worms of Schistosoma mansoni was analyzed for amino acid composition and found to be compatible with high mobility group (HMG) proteins. One of the schistosome HMG proteins was identified as HMG 2 by one-dimensional and two-dimensional PAGE. Stage-specific differences in the HMG-like protein composition were encountered when adult worms were compared to schistosomula, the larval form. Immobilization of the adult male and female nuclear proteins onto nitrocellulose, followed by hybridization against 32P-F-10, a schistosome sex specific gene encoding a major egg shell protein, revealed distinct banding patterns. On the other hand, a synthetic oligonucleotide, derived from the 3' untranslated end of the F-10 gene and possibly containing one regulatory element of the gene, bound mainly to male low MW proteins.     

Geminiviruses: Genome structure and gene function

The plant pathogenic single‐strand DNA‐containing geminiviruses have been the recent focus of intense investigation, owing both to their agronomic importance and to their potential as vectors for the expression of foreign genes in plants. Molecular genetic studies have provided detailed information on the genomic organization of many of these viruses. A greater genetic complexity has been demonstrated among the members of this viral family than had previously been suspected, as well as an apparently rapid rate of evolution of genetic diversity. We now recognize fundamental differences in the genome structure and organization of the whitefly‐ and leafhopper‐transmitted viruses, as well as among those geminiviruses infecting dicotyledonous or monocotyledonous hosts. This knowledge has provided new insights into the evolution of these viruses. The viral genes involved in replication and in systemic movement in the plant have been defined, and viral origins for single‐strand (ss) and double‐strand (ds) DNA replication have been mapped to small nucleotide regions. With the structural features of the viral genomes now well defined, current efforts are focused on elucidating the molecular aspects of viral gene regulation and interactions with host‐cell components that lead to the production of disease. Recent progress in determining the mechanism of replication and systemic movement and the contributions of these to symptom and disease development are discussed in the context of the potential for genetically engineering disease‐resistant plants.