Nucleic Acid Hybridization Studies within the Genus Cucurbita

The DNAs of Cucurbita species were examined by several methods. All Cucurbita DNAs have a similar CsCl isopycnic banding pattern consisting of a major band at 1.695 g/cc and a well separated satellite band at 1.707 g/cc. Compared to other plant and animal genera, Cucurbita species have a large genomic proportion of rDNA; this value ranging from 1.4% to 3.1%. The genomic proportion of rDNA was found not to be useful as a characteristic indicating degree of relatedness of the various Cucurbita species. However, Cucurbita DNAs can be distinguished by the extent to which their repetitive sequences cross-hybridize to each other and an assessment of species relationships can be made on this basis.     

Interspecific Hybridization in the Genus Dioscorea

Interspecific hybridization between Dioscorea alata (2n = 60).D. deltoidea (2n = 20), D. floribunda (2n = 36), D. composita(2n = 36), and D. friedrichsthallii (2n = 36) has revealed levelsof crossability consisting of successful crossing and normalgermination of hybrid seeds, successful crossing but poor germinationof hybrid seeds, crosses not successful due to a pre-fertilizationovular breakdown, and crosses not successful due to post-fertilizationovular breakdown. In general the three Central American species with basic chromosomenumber as 9, namely D. floribunda, D. composita, and D. friedrichsthalliiare cross compatible. In crosses involving D. floribunda withD. composita and D. floribunda with D. friedrichsthallii viablehybrids were obtained. The cross between D. friedrichsthalliiand D. composita is also successful but germination of the hybridseeds is greatly reduced. The cross of D. composita female withthe male D. friedrichsthallii was an exception to the generalcompatibility between these three species. In this cross thefertilized embryo aborted after attaining four-celled stage. The crosses between the two Old World species with basic chromosomenumber as 10, namely D. alata and D. deltoidea with each otherand with the above named three Central American species werenot successful. D. alata had pollen grains which rarely germinated.When D. alata was used as the female parent, the pollen tubesof other species grew down the style but no fertilization tookplace. The reciprocal crosses of D. deltoidea with the CentralAmerican species gave differential results. When D. deltoideawas used as the female parent no fertilization took place. However,when D. deltoidea was used as the male parent the fertilizedembryo aborted after attaining globular stage.     

甜瓜属植物种间杂交研究进展

在甜瓜属野生种Cucumis hystrix Chakr. 和栽培黄瓜之间的种间杂交取得成功的基础上,简要回顾了甜瓜属植物种质资源和系统学的研究情况,然后从甜瓜属植物种间杂交的概况、种间杂交的障碍及其解决途径等三个方面,回顾和讨论了甜瓜属植物的种间杂交的研究进展,并对进一步通过种间杂交研究利用甜瓜属野生植物资源的前景进行了展望。     

甜瓜属植物种间杂交研究进展

在甜瓜属野生种Cucumis hystrix Chakr.和栽培黄瓜之间的种间杂交取得成功的基础上,简要回顾了甜瓜属植物种质资源和系统学的研究情况,然后从甜瓜属植物种间杂交的概况、种间杂交的障碍及其解决途径等三个方面,回顾和讨论了甜瓜属植物的种间杂交的研究进展,并对进一步通过种间杂交研究利用甜瓜属野生植物资源的前景进行了展望.     

Correction to: Phenotypic,Genetic, and Cytogenetic Evidence of Hybridization between Species of Trans-Andean Tamarins (Genus Saguinus)

International Journal of Primatology - This article is intended for inclusion in the Special Issue on Primate Hybridization and Hybrid Zones. It was however published in a separate issue, Volume 39...     

Molecular Relationships Between Saccharomyces cerevisiae Strains Involved in Winemaking from Mendoza, Argentina

Three molecular typing techniques were applied to assess the molecular relationships of Saccharomyces cerevisiae strains isolated from winery equipment, grapes, and spontaneous fermentation in a cellar located in “Zona Alta del Río Mendoza” (Argentina). In addition, commercial Saccharomyces strains widely used in this region were also included. Interdelta PCR typing, mtDNA restriction analysis, and microsatellite (SSR) genotyping were applied. Dendrograms were constructed based on similarity among different patterns of bands. The combination of the three techniques discriminated 34 strains among the 35 isolates. The results of this study show the complex relationships found at molecular level among the isolates that share the same ecological environment, i.e., the winemaking process. With a few exceptions, the yeast isolates were generally clustered in different ways, depending on the typing technique employed. Three clusters were conserved independently of the molecular method applied. These groups of yeasts always clustered together and had high degree of similarity. Furthermore, the dendrograms mostly showed clusters combining strains from winery and fermentation simultaneously. Most of the commercial strains included in this study were clustered separately from the other isolates analyzed, and just a few of them grouped with the strains mainly isolated from spontaneous fermentation. Only one commercial strain was clustered repetitively with a noncommercial strain isolated from spontaneous fermentation in the three dendrograms. On the other hand, this study has demonstrated the importance of selecting an appropriate molecular method according to the main objectives of the research.     

酿酒酵母属的分类学研究进展

由于酵母菌的巨大经济价值,国内外对这类微生物从基础到应用各方面的研究一直都非常活跃,而其中最基础的学科,酵母菌分类学,亦经历了巨大变化。了解当前最具有经济重要性的酿酒酵母菌的属种概念及其分类方法,无疑对更好地掌握和利用这类酵母菌具有重要意义。１酿酒酵母属的建立及其早期分类学研究 酿酒酵母属（Ｓａｃｃｈａｒｏｍｙｃｅｓ　Ｍｅｙｅｎ　ｅｘ　Ｒｅｅｓｓ）的分类学研究历史可追溯到一个半世纪以前,Ｍｅｙｅｎ于１８３８年首次提出了Ｓａｃｃｈａｒｏｍｙｃｅｓ这一属名,并将啤酒酵母命名为Ｓａｃｃｈａｒｏｍｙｃｅ…     

Phenotypic and Genotypic Analysis of Newly Obtained Interspecific Hybrids in the Campanula Genus

Interspecific hybridisation creates new phenotypes within several ornamental plant species including the Campanula genus. We have employed phenotypic and genotypic methods to analyse and evaluate interspecific hybridisation among cultivars of four Campanula species, i.e. C. cochleariifolia, C. isophylla, C. medium and C. formanekiana. Hybrids were analysed using amplified fragment length polymorphism (AFLP), flow cytometry and biometrical measurements. Results of correlation matrices demonstrated heterogeneous phenotypes for the parental species, which confirmed our basic premise for new phenotypes of interspecific hybrids. AFLP assays confirmed the hybridity and identified self-pollinated plants. Limitation of flow cytometry analysis detection was observed while detecting the hybridity status of two closely related parents, e.g. C. cochleariiafolia × C. isophylla. Phenotypic characteristics such as shoot habitus and flower colour were strongly influenced by one of the parental species in most crosses. Rooting analysis revealed that inferior rooting quality occurred more often in interspecific hybrids than in the parental species. Only interspecific hybrid lines of C. formanekiana ‘White’ × C. medium ‘Pink’ showed a high rooting level. Phenotype analyses demonstrated a separation from the interspecific hybrid lines of C. formanekiana ‘White’ × C. medium ‘Pink’ to the other clustered hybrids of C. formanekiana and C. medium. In our study we demonstrated that the use of correlation matrices is a suitable tool for identifying suitable cross material. This study presents a comprehensive overview for analysing newly obtained interspecific hybrids. The chosen methods can be used as guidance for analyses for further interspecific hybrids in Campanula, as well as in other ornamental species.     

Diploid Hybridization in a Heterothallic Haploid Yeast, Saccharomyces rouxii

By crossing of a heterothallic haploid yeast, Saccharomyces rouxii, we have succeeded in obtaining diploid hybrids. This paper shows one possible method of breeding heterothallic haploid yeasts for industrial application. S. rouxii is highly salt-tolerant and plays an important role in shoyu and miso fermentation. Therefore, genetic improvements of the properties are of commercial importance. Since newly isolated S. rouxii could neither conjugate nor sporulate on sporulation media commonly used, a suitable medium for conjugation and sporulation of S. rouxii was firstly investigated. A 5% NaCl Shoyu-koji extract agar was found to be most efficient. Next, we tried to get diploid strains by mass culture of two mating types on the conjugation medium, but several phenomena made this difficult: (i) zygotes quickly sporulated before budding; (ii) several zygotes showed terminal budding, but the buds could not grow into diploid cells, suggesting they would be heterocaryon; and (iii) a few zygotes lost their viability. After trying to isolate and cultivate a large number of zygotes in various combinations of crossing by micromanipulation, we fortunately recognized that large cells arose from some combinations. The analysis of ploidy suggested that the large cells would be diploid. Also, they showed sporulation of typical Saccharomyces, i.e., two to four spores in an unconjugated ascus. The diploid strains thus obtained were highly salt-tolerant and stable in liquid medium. Therefore, the procedure presented here would be effective for breeding salt-tolerant S. rouxii.     

Phenotypic Novelty in EvoDevo: The Distinction Between Continuous and Discontinuous Variation and Its Importance in Evolutionary Theory

The introduction of novel phenotypic structures is one of the most significant aspects of organismal evolution. Yet the concept of evolutionary novelty is used with drastically different connotations in various fields of research, and debate exists about whether novelties represent features that are distinct from standard forms of phenotypic variation. This article contrasts four separate uses for novelty in genetics, population genetics, morphology, and behavioral science, before establishing how novelties are used in evolutionary developmental biology (EvoDevo). In particular, it is detailed how an EvoDevo-specific research approach to novelty produces insight distinct from other fields, gives the concept explanatory power with predictive capacities, and brings new consequences to evolutionary theory. This includes the outlining of research strategies that draw attention to productive areas of inquiry, such as threshold dynamics in development. It is argued that an EvoDevo-based approach to novelty is inherently mechanistic, treats the phenotype as an agent with generative potential, and prompts a distinction between continuous and discontinuous variation in evolutionary theory.     

Phenotypic and Genotypic Characteristics of Members of the Genus Streptobacillus

The genus Streptobacillus (S.) remained monotypic for almost 90 years until two new species were recently described. The type species, S. moniliformis, is one of the two etiological agents of rat bite fever, an under-diagnosed, worldwide occurring zoonosis. In a polyphasic approach field isolates and reference strains of S. moniliformis, S. hongkongensis, S. felis as well as divergent isolates were characterized by comparison of molecular data (n = 29) and from the majority also by their physiological as well as proteomic properties (n = 22). Based on growth-independent physiological profiling using VITEK2-compact, API ZYM and the Micronaut system fastidious growth-related difficulties could be overcome and streptobacilli could definitively be typed despite generally few differences. While differing in their isolation sites and dates, S. moniliformis isolates were found to possess almost identical spectra in matrix-assisted laser desorption ionization—time of flight mass spectrometry and Fourier transform infrared spectroscopy. Spectroscopic methods facilitated differentiation of S. moniliformis, S. hongkongensis and S. felis as well as one divergent isolate. Sequencing of 16S rRNA gene as well as functional genes groEL, recA and gyrB revealed only little intraspecific variability, but generally proved suitable for interspecies discrimination between all three taxa and two groups of divergent isolates.     

Hybridization Promotes Evolvability in African Cichlids: Connections Between Transgressive Segregation and Phenotypic Integration

Hybridization is a potential source of novel variation through (1) transgressive segregation, and (2) changes in the patterns and strength of phenotypic integration. We investigated the capacity of hybridization to generate novel phenotypic variation in African cichlids by examining a large F2 population generated by hybridizing two Lake Malawi cichlid species with differently shaped heads. Our morphometric analysis focused on the lateral and ventral views of the head. While the lateral view exhibited marked transgressive segregation, the ventral view showed a limited ability for transgression, indicating a difference in the genetic architecture and selective history between alternate views of the head. Moreover, hybrids showed a marked reduction in integration, with a lower degree of integration observed in transgressive individuals. In all, these data offer novel insights into how hybridization can promote evolvability, and provide a possible explanation for how broad phenotypic diversity may be achieved in rapidly evolving groups.     

植物染色体原位杂交技术及其在稻属研究中的应用

本文介绍了植物染色体原位杂交技术,以及该技术在稻属特定DNA序列定位、基因组间关系、外源染色体鉴定等研究中的应用.     

tRNA Nuclear Export in Saccharomyces cerevisiae: In Situ Hybridization Analysis

To understand the factors specifically affecting tRNA nuclear export, we adapted in situ hybridization procedures to locate endogenous levels of individual tRNA families in wild-type and mutant yeast cells. Our studies of tRNAs encoded by genes lacking introns show that nucleoporin Nup116p affects both poly(A) RNA and tRNA export, whereas Nup159p affects only poly(A) RNA export. Los1p is similar to exportin-t, which facilitates vertebrate tRNA export. A los1 deletion mutation affects tRNA but not poly(A) RNA export. The data support the notion that Los1p and exportin-t are functional homologues. Because LOS1 is nonessential, tRNA export in vertebrate and yeast cells likely involves factors in addition to exportin-t. Mutation of RNA1, which encodes RanGAP, causes nuclear accumulation of tRNAs and poly(A) RNA. Many yeast mutants, including those with the rna1-1 mutation, affect both pre-tRNA splicing and RNA export. Our studies of the location of intron-containing pre-tRNAs in the rna1-1 mutant rule out the possibility that this results from tRNA export occurring before splicing. Our results also argue against inappropriate subnuclear compartmentalization causing defects in pre-tRNA splicing. Rather, the data support “feedback” of nucleus/cytosol exchange to the pre-tRNA splicing machinery.     

Hybridization of cells of the same mating type in Saccharomyces yeasts

The problem of mating-type switches in heterothallic yeast cells was investigated. 93% of non-mating hybrids were obtained in a X a crosses. The hybrids obtained in alpha X alpha crosses expressed alpha-mating type predominantly. Hybrids with no major rearrangements or loss of chromosome III were detected among these hybrids. In the selective system for cytoduction in a X a crosses the significant part of all cytoductants were alpha-maters, i.e. those originated through a----alpha switches. In alpha X alpha crosses alpha cytoductants were predominantly obtained either spontaneously or after UV-irradiation, though the frequency of cytoductants after UV-irradiation exceeded the control value several times. So, we developed the method for selection of mating-type "switchers" (a in equilibrium alpha), avoiding the diploid stage, and demonstrated the possibility of hybridization among the alpha-cells without hereditary changes at the MAT locus.