Interspecific crosses in Avena L. species]

Problems of crosses between various oat species are considered with regard to establishing their taxonomic positions and genomic compositions of individual species. The evolution of the genus and approaches to the search for the diploid and tetraploid ancestor of the hexaploid species are considered. Use of wild oat species in breeding is demonstrated. The results of studies of the gene pool of wild oat species are presented. These studies were performed at the Vavilov All-Russian Plant Breeding Institute with the purpose of solving problems of phylogeny and practical breeding.     

Light-oriented locomotion in certain myxobacter species

Summary Euglena gracilis, strain Z, was grown in synchronous culture. Carbon source used was either dl-lactic acid (L) or a mixture of l-glutamic and dl-malic acids (GM). Synchronisation was obtained by transfering the cells in the exponential growth phase, at regular intervals—each 3 days—to a fresh medium.Respiration (measured during a whole cell cycle, 12 h) was 20±6 l/H/10⁶ cells on (GM) and 46±7 l/H/10⁶ cells on (L) medium. At the same time as the increased rate of oxygen uptake on lactate medium, we observed the appearance of a giant chondriome in the cells. On glutamate—malate containing medium the size of mitochondria was normal.

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Les micrographies électroniques ont été réalisées par Mr. C. Mattei, Technicien CNRS.     

Enhancing fitness in offspring of crosses between two triatomine species

Chagas disease is one of the main vector‐borne diseases in Latin America, including Mexico. Understanding the biological parameters of the triatomine species is a crucial first step in estimating the epidemiologic importance of each group. The aim of this study was to compare the biological fitness of Meccus pallidipennis (Stål), M. bassolsae (Alejandre, Nogueda, Cortez, Jurberg, Galvão, Carcavallo) (Hemiptera: Reduviidae: Triatominae) and their laboratory hybrids, by estimating six biological parameters in order to increase the knowledge of the potential role of triatomine hybrids in the transmission of Trypanosoma cruzi to reservoir hosts. Biological parameters related to lifespan, number of blood meals to molt, mortality for each instar, percentage of females at the end of the cycle, number of eggs laid, and hatching of eggs in four cohorts of 100 specimens of M. pallidipennis, M. bassolsae, and their laboratory hybrids were evaluated and compared. In four of the six studied parameters (accumulative mortality, the percentage of females, mean number of laid eggs, and egg hatching), the hybrid cohorts had better fitness results than the parental cohorts. The increase in hybrid fitness found in our study could lead to an increase in the epidemiologic risks caused by transmission of T. cruzi to humans.     

Cytotaxonomy and phylogeny in certain species ofTaxodiaceae

Various species ofTaxodiaceae were selected for chromosome studies to indicate cytotaxonomic and phylogenetic relationships. Point dispersal patterns of diagrammatic presentations of the species' karyotypes, rather than marker chromosomes, were found to be the most significant cytotaxonomic characteristic in indicating phylogenetic relationships. Karyotypic evolution inTaxodiaceae appears to occur by unequal reciprocal translocations followed by pericentric and paracentric inversions. Cytotaxonomic relationships among species generally correspond to the phylogenetic relationships withinTaxodiaceae indicated by classical taxonomic classification. Presence and types of marker chromosomes may have the potential to indicate relationships between different coniferous families.     

Comparative genetics of hybrid incompatibility: sterility in two Solanum species crosses

The genetic basis of hybrid sterility can provide insight into the genetic and evolutionary origins of species barriers. We examine the genetics of hybrid incompatibility between two diploid plant species in the plant clade Solanum sect. Lycopersicon. Using a set of near-isogenic lines (NILs) representing the wild species Solanum pennellii (formerly Lycopersicon pennellii) in the genetic background of the cultivated tomato S. lycopersicum (formerly L. esculentum), we found that hybrid pollen and seed infertility are each based on a modest number of loci, male (pollen) and other (seed) incompatibility factors are roughly comparable in number, and seed-infertility QTL act additively or recessively. These findings are remarkably consistent with our previous analysis in a different species pair, S. lycopersicum x S. habrochaites. Data from both studies contrast strongly with data from Drosophila. Finally, QTL for pollen and seed sterility from the two Solanum studies were chromosomally colocalized, indicating a shared evolutionary history for these QTL, a nonrandom genomic distribution of loci causing sterility, and/or a proclivity of certain genes to be involved in hybrid sterility. We show that comparative mapping data can delimit the probable timing of evolution of detected QTL and discern which sterility loci likely evolved earliest among species.     

Gametogenesis and plasmogamy in certain species of Microspora

Gametogenesis and plasmogamy of gametes is documented in light and electron microscopy of Hazardia milleri, Culicospora magna, and an undescribed microsporidium in Aedes aegypti, using three mosquito hosts in experimental infection studies. Events taking place during gametogenesis and plasmogamy were similar in all three species studied. However, merogonial and sporogonial sequences differed among the three species. Gametes of C. magna and a Microsporidium sp. in A. aegypti were structurally different from those of H. milleri in that they contain an unusual nipple-like structure on one end. The function of this structure was not ascertained. C. magna was successfully transmitted to healthy Culex restuans larvae exposed to spores in well water, but infections were higher when larvae were exposed to spores in filtered field water taken from breeding sites. The presented evidence of the production and union of gametes is the first documentation of gametogenesis and plasmogamy in species of microsporidia. The realization of sexual cycles in some species raises important questions concerning the present classification of the Microspora.     

In situ analysis of centromeric satellite DNA segregating inMus species crosses

In situ hybridization of biotin-labeled mouse major satellite DNA clone pMR196 was applied toMus domesticus andMus spretus chromosomes (Chr). The same karyotypes were counterstained with distamycin A-DAPI to identify AT-rich heterochromatin. Chromosomes from the laboratory mouse, C57BL/6Ros (BL/6;M. domesticus) were uniformly labeled at the centromere except for the Y, while chromosomes from the divergentMus speciesM. spretus showed little or no hybridization. Differences betweenMus species in copy number of the major satellite DNA sequence were used to identify chromosomes ofM. domesticus andM. spretus in their F₁ hybrids and to discriminatedomesticus andspretus centromeres in backross progeny. The distribution pattern of heterochromatic regions demonstrated by distamycin A-DAPI counterstaining was comparable with that of in situ hybridization with pMR196, suggesting that A-T rich heterochromatin inM. domesticus is mainly constructed by the pMR196-related sequence. The in situ technique was used to examine segregation ofdomesticus centromeres in backcross progeny obtained by mating F₁ hybrid females withM. domesticus orM. spretus males. The segregation of centromeres did not deviate from the expected among the backcross progeny from C57BL/6Ros males, whereas chromosomes withM. domesticus centromeres were prone to appear in the progeny from backcross matings byM. spretus males.     

Anthocyanins: structural characteristics that result in unique metabolic patterns and biological activities

Interest in anthocyanins has increased immensely during the past decade. From these studies, it is clear that anthocyanins have unique properties: Anthocyanins are absorbed intact and absorption can be saturated; acylation of anthocyanins lowers their apparent absorption; anthocyanidin diglycosides in the form of sambubioside or rutinoside impart increased stability to the anthocyanin molecule; and the quantities excreted in urine are less than 0.1% of intake. However, 60-90% of the anthocyanins may disappear from the gastrointestinal tract within 4 h after a meal. What happens to the bulk of the anthocyanins that disappear is not clear. Degradation accounts for a part of this disappearance, but differs for the various aglycones and may be modified further by the nature of the aglycone glycosylation, which further complicates our understanding of this process. Anthocyanins may play an important role in health promotion in terms of obesity prevention, cardiovascular health, anti-inflammatory and anti-cancer effects.     

Anthocyanins: Structural characteristics that result in unique metabolic patterns and biological activities

Interest in anthocyanins has increased immensely during the past decade. From these studies, it is clear that anthocyanins have unique properties: Anthocyanins are absorbed intact and absorption can be saturated; acylation of anthocyanins lowers their apparent absorption; anthocyanidin diglycosides in the form of sambubioside or rutinoside impart increased stability to the anthocyanin molecule; and the quantities excreted in urine are less than 0.1% of intake. However, 60–90% of the anthocyanins may disappear from the gastrointestinal tract within 4 h after a meal. What happens to the bulk of the anthocyanins that disappear is not clear. Degradation accounts for a part of this disappearance, but differs for the various aglycones and may be modified further by the nature of the aglycone glycosylation, which further complicates our understanding of this process. Anthocyanins may play an important role in health promotion in terms of obesity prevention, cardiovascular health, anti-inflammatory and anti-cancer effects.     

山羊草(Aegilops)物种作母本与小麦远缘杂交的评价

研究了山羊草不同物种作母本,在不借助胚培等特殊措施的情况下与不含隐性可杂交基因的小麦推广品种杂交、回交及杂种自交情况,结果表明(1)山羊草物种作母本,小麦推广品种作父本进行杂交是一种很有效的方式;山羊草物种作母本容易与小麦进行杂交,但回交和自交较困难;回交与自交相比时,回交容易些;(2)同一物种的不同基因型材料在与小麦杂交、回交及杂种自交时存在大量变异;(3)杂交结实率与以后的回交或自交并不相关,但是杂种的回交和自交之间相关;(4)山羊草物种与小麦杂交、回交及其杂种自交的结实率与其染色体组构成并无明显相关.     

A Bayesian method for simultaneously detecting Mendelian and imprinted quantitative trait loci in experimental crosses of outbred species

Genomic imprinting is interpreted as a phenomenon, in which some genes inherited from one parent are not completely expressed due to modification of the genome caused during gametogenesis. Subsequently, the expression level of an allele at the imprinted gene is changed dependent on the parental origin, which is referred to as the parent-of-origin effect. In livestock, some QTL for reproductive performance and meat productivity have been reported to be imprinted. So far, methods detecting imprinted QTL have been proposed on the basis of interval mapping, where only a single QTL was tested at a time. In this study, we developed a Bayesian method for simultaneously mapping multiple QTL, allowing the inference about expression modes of QTL in an outbred F2 family. The inference about whether a QTL is Mendelian or imprinted was made using Markov chain Monte Carlo estimation by comparing the goodness-of-fits between models, assuming the presence and the absence of parent-of-origin effect at a QTL. We showed by the analyses of simulated data sets that the Bayesian method can effectively detect both Mendelian QTL and imprinted QTL.     

Embryo rescue response and genetic analyses in interspecific crosses of oilseed Brassica species

Embryo rescue technique is widely utilized to save developing embryo from abortion in interspecific hybridization of plants. In Brassica species, success of an embryo rescue depends on the age of embryo, developmental stage of embryo, and media composition. In this study, ten crosses were conducted between diploid oilseed species B. rapa × tetraploid B. napus and B. rapa × tetraploid B. juncea along with their reciprocal crosses. The immature embryos from parents and crosses were cultured at 14 d after pollination in MS and ½ MS medium without any growth regulators for direct embryogenesis. Embryos were found at different stages of development during isolation, from globular to cotyledonary, indicating that rate of embryo development depends on genotype. Embryos isolated at the cotyledonary stage showed the highest regeneration percentage (av. 83.29%) and required the lowest time to regenerate (5.8 d) compared with another type of embryo, torpedo stage, cultured. Embryo rescued in ½ MS media accounted for 10–51%, 4.0–61%, 6.0–21%, and 5.0–43% greater shoot length, root length, number of leaves, and days to flowering, respectively, in different cross combinations compared with full-strength MS media. The results indicated that the rate of regeneration from embryo is higher in ½ MS media compared with full-strength MS media. Percent regeneration from the cultured embryos differed significantly in different cross combinations. Days required for regeneration from embryos, length of siliqua, and the number of ovules per siliqua accounted for high heterosis and broad sense heritability. The findings of this experiment would be useful in developing cost-effective embryo rescue protocol and desired interspecific hybrids through embryo rescue in Brassica species.