Numbers of sporophytic self-incompatibility alleles in populations of wild radish

Summary To estimate the numbers of sporophytic S-alleles in two adjacent populations of wild radish, we performed 701 reciprocal crosses among 50 individuals. Each cross was replicated five times in each direction. Sixteen plants were fully intercompatible, indicating the presence of at least 32 S-alleles in the two populations. A minimum of 22 S-alleles occur in a single population. The frequency of incompatibility was significantly higher for within-population crosses (14.5%) than for between-population crosses (7.8%). This suggests that the two populations differ in the composition and frequency of alleles at the S-locus.     

Patterns of paternal care in primates

An interspecific comparison was carried out to understand better the relationships among paternal care, paternal certainty, and reproductive burden in primates. Although monogamy is generally rare among mammals, a number of primate species are monogamous. Extensive paternal care is a related issue but is one that is not necessarily associated with monogamy or with paternal certainty. For example, despite paternal certainty, primate mothers in monogamous species with body weights over 2 kg still remain the primary infant caretakers, while males in the communally breeding tamarins carry infants more frequently than mothers do, even in the absence of paternal certainty. Several different tactics are used by small-bodied primates to cope with the energetic burden of raising proportionately large infants in an arboreal environment: (1) infant carrying by subadult and/or related nulliparous females (Saimiri, Lemur monogoz); (2) infant carrying by fathers and offspring (Aotus, Callicebus, Saguinus, Cebuella, Leontopithecus); (3) parking infants while family members forage (Tarsius, Galago, Microcebus, Cheirogaleus, Varecia); or (4) some combination of the above (Callithrix, Hapalemur, Loris). Lactation length and infant growth patterns appear to influence which of these tactics is employed by a given species. Moreover, although most small-bodied, mated, monogamous female primates spend no more than 9 months annually in gestation and lactation,Aotus andCallicebus mated females are either pregnant or lactating on a year-round basis. It is this heavy female reproductive burden that may be an important factor in selection for extensive paternal care in these monogamous cebids.     

无环鸟苷抗乙型肝炎病毒复制长短程疗法随访观察

慢性乙型肝炎病毒感染s5例,随机分无环鸟苷长程组22例,短程组11例和对照组22例。经一年随访观察,无环鸟苷治疗组见血清HBeAg、DNA-P和HBV-DNA有规律性阴转,短程组于12个月又有部分指标阳转,长程组阴转较多,其血清HBeAg、DNA-P和HBV-DNA阴转率与短程和对照组比较有显著性差异。一年结果四项病毒复制指标全部阴转例数与对照组有显著性差异,结果表明,无环鸟苷长疗程是有较好疗效。     

ALLOZYME DIVERSITY AND GENETIC IDENTITY IN SCHIEDEA AND ALSINIDENDRON (CARYOPHYLLACEAE: ALSINOIDEAE) IN THE HAWAIIAN ISLANDS

Genetic diversity of allozymes, genetic identity based on allozyme variability, and phylogenetic relationships were studied with respect to breeding system diversity, population size, and island age in 20 of the 29 species of Schiedea and Alsinidendron (Caryophyllaceae: Alsinoideae), a monophyletic lineage endemic to the Hawaiian Islands. Average levels of genetic variability in Schiedea and Alsinidendron were comparable to or higher than those found in other Hawaiian lineages for which equivalent data are available [Bidens, Tetramolopium, and the silversword alliance (Asteraceae: Madiinae)] and similar to average values for species of dicots. Allozyme variability was strongly dependent on breeding system, which varies widely in the Hawaiian Alsinoideae. Species with autogamous breeding systems showed very low variability, measured as the number of alleles per locus, percent polymorphic loci, and mean heterozygosity per locus. Outcrossing hermaphroditic and dimorphic species (those with gynodioecious, subdioecious, and dioecious breeding systems) showed significantly higher genetic variability. Small population size was associated with lower values for all measures of genetic variability. Nearly half of the species occurring in small populations are also autogamous; thus, both factors may have influenced levels of genetic variability in these species. Founder effect was apparent in one species (Schiedea adamantis), which occurs in a single large population, has a gynodioecious breeding system but a very low genetic variability. Island age appeared to have little effect on genetic variability. Slightly lower values of genetic variability for species occurring on Kaua'i and O'ahu result primarily from the occurrence of autogamous Alsinidendron species on those islands. Values for Nei's genetic identity for different species pairs were 0.201–0.942, a far greater range than in Bidens, the silversword alliance, and Tetramolopium. Using UPGMA clustering, there was only moderate support for relationships detected through cladistic analysis. Nei's unbiased genetic identity (I) was greatest among species with outcrossing breeding systems, which for the most part clustered together. Nei's genetic identities for self-fertilizing species were low, indicating that these species are less similar to one another and to outcrossing species, regardless of their affinities based on cladistic analysis. Parsimony analysis of allele frequency data supported two clades also found in phylogenetic analyses using morphological and molecular data. Clades recognized in parsimony analysis of allele frequencies were those lineages containing selfing species, indicating that conditions favoring fixation of alleles occurred in ancestral species. In contrast, maintenance of high genetic diversity in outcrossing species interferes with recognition of phylogenetic relationships using allozyme variability.     

POLLEN-TUBE COMPETITION AND MALE FITNESS IN HIBISCUS MOSCHEUTOS

The stigmas of animal-pollinated flowers often capture more pollen than is needed to fertilize all available ovules, and mixed-donor pollen loads are probably common. When this is the case, variation in average pollen-tube growth rates can potentially affect the number of seeds sired by a given plant. Despite considerable interest in effects of postpollination processes on male fitness, little is known about the extent of variation in pollen performance among plants from natural populations. To examine this question in Hibiscus moscheutos (rose mallow), we conducted mixed-donor hand-pollination experiments with 39 pollen donors bearing distinctive isozyme markers. Pairs of competing donors were compared on sets of 11 to 15 recipient plants per pair. These donors often differed in the proportions of seeds they sired, with the maximum deviation from an expected ratio of 50:50 being 68:32. Furthermore, three intensively studied plants exhibited consistent trends in relative pollen performance when each was tested against (1) the same three competitors, and (2) groups of 14 competitors chosen at random from the study population. In a separate experiment, we investigated the effects of salinity stress and high soil nutrients on pollen performance. These environmental factors had anticipated effects on leaf production, flower production, and petal length, but style length and (most importantly) the number of seeds sired relative to a standard pollen donor were not affected. In summary, this study provides the strongest evidence to date that pollen-tube competitive ability varies among coexisting plants and may be an important component of male fitness in plants.     

Genetic research as the valid base of strategies for breeding rust resistant wheats

It is known that few wheat cultivars maintain their resistance to rust diseases for a long period of time, particularly when crop populations become genetically more uniform. A number of genetically diverse, so far unexploited, sources of rust resistance in the natural as well as mutagenized population of wheat cultivars were identified. Several of these genes were placed in agronomically superior well-adapted backgrounds so that they could be used as pre-breeding stocks for introducing genetic diversity for resistance in a crop population. Some of these stocks when employed as parents in several cross combinations in a breeding programme have generated a number of promising cultivars with diversity for resistance.Many presently grown wheats in India, near-isogenic lines each with Lr14b, Lr14ab, Lr30 and certain international cultivars were identified as possessing diverse sources of adult plant resistance (APR) to leaf rust. Prolonged leaf rust resistance in some of the Indian cultivars was attributed to the likely presence of Lr34 either alone or in combination with other APR components. Tests of allelism carried out in certain cultivars that continue to show adequate levels of field resistance confirm the presence of Lr34, which explains the role that this gene has played in imparting durability for resistance to leaf rust. Also, Lr34 in combination with other APR components increases the levels of resistance, which suggests that combination of certain APR components should be another important strategy for breeding cultivars conferring durable and adequate levels of resistance. A new adult plant leaf rust resistance source that seems to be associated with durability in Arjun has been postulated. Likewise, cultivars possessing Sr2 in combination with certain other specific genes have maintained resistance to stem rust.Further, non-specific resistances that were transferred across widely different genotypes into two of the popular Indian wheats provided easily usable materials to the national breeding programmes for imparting durable resistance to stripe rust.     

The bacterial phleomycin resistance geneble as a dominant selectable marker inChlamydomonas

A chimeric gene composed of the coding sequence of theble gene fromStreptoalloteichus hindustanus fused to the 5 and 3 untranslated regions of theChlamydomonas reinhardtii nuclear geneRBCS2 has been constructed. Introduction of this chimeric gene into the nuclear genome ofC. reinhardtii by co-transformation with theARG7 marker yields Arg⁺ transformants of which approximately 80% possess theble gene. Of these co-transformants, approximately 3% display a phleomycin-resistant (Pm^R) phenotype. Western blot analysis using antibodies against theble gene product confirms the presence of the protein in the Pm^R transformants and genetic analysis demonstrates the co-segregation of theble gene with the phenotype in progeny arising from the mating of a Pm^R transformant to wild-type strains. Direct selection of Pm^R transformants was achieved by allowing an 18-h period for recovery and growth of transformed cells prior to selection. This work represents the first demonstration of stable expression and inheritance of a foreign gene in the nuclear genome ofC. reinhardtii and provides a useful dominant marker for nuclear transformation.     

Reproductive success and clonal genetic structure of the rareArnica montana (Compositae) in The Netherlands

In a medium-sized population ofArnica montana, a threatened species in The Netherlands, the breeding system, reproductive success and genetic clonal structure were studied. Pollination experiments suggested thatA. montana is largely self-incompatible. Inbreeding depression was observed for seedling weight but not for fruit weight and germination rate. Although genetic variation is rather low in this population, the data suggest an outcrossing mating system. Analysis of the genotype of all mapped rosettes in a plot of 100 m² indicated that dense clusters often consist of identical genotypes, suggesting a clonal structure. Open clusters frequently contained several different genotypes. This may be caused by limited fruit dispersal, since seedlings were found mainly within or in the near surroundings of the clusters.     

Use of diethyl squarate for the coupling of oligosaccharide amines to carrier proteins and characterization of the resulting neoglycoproteins by MALDI-TOF mass spectrometry

The 8-methoxycarbonyloctyl glycosides of GlcNAc, Gal1-4Glc, Fuc1-2Fuc1-3GalNac and Fuc1-2Gal1-3[Fuc1-4]GlcNac were converted to primary amines by reaction with neat ethylenediamine and then coupled to bovine serum albumin (BSA) using diethyl squarate as the connector. The average degree of incorporation of the sugar onto the protein, as well as the molecular weight distribution, could be conveniently determined using matrix assisted laser desorption ionization/time of flight (MALDI-TOF) mass spectrometry thus avoiding cumbersome structure-dependent colour-tests or analysis of cleaved ligand. The present coupling method has the advantages of proceeding under very mild conditions, yielding controlled incorporation values and can reliably be used for the coupling of very small amounts (mg) of oligosaccharide.This paper is dedicated to Sen-itiroh Hakomori on the occasion of his 65th birthday     

Use of chicken microsatellite markers in turkey: a pessimistic view

Eighty-eight chicken microsatellite markers, previously developed in our laboratory, were tested for their ability to amplify polymorphic fragments using turkey genomic DNA. Amplification products were obtained for 61 chicken microsatellite markers (69.1%) whereas 27 (30.9%) did not give rise to any products, even when different polymerase chain reaction conditions were employed. From the 61 markers that gave a product, only eight showed a length polymorphism while 37 were monomorphic on the three divergent commercial turkey lines used. The remaining 16 markers yielded many unspecific bands and no specific amplification product could be obtained. Five polymorphic and eleven monomorphic products contained a detectable microsatellite repeat. Furthermore, of the markers that detected a polymorphism in turkey, the observed heterozygosity (15–50%) and allelic variation (only 2 in most cases) was very low. Therefore, on the basis of our results, we think that chicken microsatellite markers are not very useful for mapping purposes in turkey.