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1.
A. D. Lachmann 《Physiological Entomology》1998,23(4):360-368
Abstract .Males and females of the dung fly species Coproica vagans Haliday 1833 (Diptera: Sphaeroceridae) mate soon after emergence from the puparium. At this time females still have immature ovaries. Therefore, mating precedes vitellogenesis in this species. Data presented here show that mating enhances oogenesis in C. vagans females. Mated females mature their first egg batch sooner and oviposit four days earlier than virgin conspecifics. Mating-related enhancement of oogenesis could be explained either through nutritional benefits to females or male chemical or stimulatory manipulation of the females. Oogenesis was divided into six arbitrary stages, with vitellogenesis beginning in stage 4. Ovarian development beyond stage 4 is rapid compared with pre-vitellogenetic development. Virgin females pause oogenesis in stage 4. The genital opening of mated females is blocked by a mating plug that persists until oviposition begins. The plug seems to ensure the paternity of the last male to mate by preventing females from remating. The operational sex ratio in C. vagans populations is presumed to be strongly male-biased. 相似文献
2.
Luc Giasson Charles A. Specht Craig Milgrim Charles P. Novotny Robert C. Ullrich 《Molecular & general genetics : MGG》1989,218(1):72-77
Summary An A mating-type allele (A4) was isolated by walking the chromosome from the closely linked PAB1 gene. A cosmid clone containing the A1 allele isolated from the walk was used as a probe to recover the A1 allele from another cosmid library. Cosmids encoding mating-type activity were identified by transforming Schizophyllum cells and screening for activation of A-regulated development. Putative mating-type transformants were confirmed in mating tests and genetic analyses of progeny. The identity of the specific alleles isolated was demonstrated by showing that their effectiveness in transforming for mating type is limited to recipient strains possessing an A allele different from the one encoded by the cloned sequences. Transforming DNA is active in trans, suggesting that A encodes a diffusible product. Restriction mapping shows that A1 and A4 are coded in the same physical region of the genome, but within a subregion that contains extensive sequence divergence. In addition, Southern analyses show that there is only one copy of A1 or A4 per haploid genome, and that they do not cross-hybridize to one another or to any of the other A alleles. A1 and A4 were subcloned as 2.8 and 1.2 kb fragments, respectively, retaining in transformation all the mating-type activity demonstrated of the original cosmids. 相似文献
3.
Regular systems of inbreeding are defined as those with discrete, nonoverlapping generations and with the same number of individuals and mating pattern in every generation. Given the number of individuals in a generation, there are many possible regular mating systems. A notion of when two such mating systems are equivalent is introduced, and several necessary conditions are given for such an equivalence. The use of these conditions is illustrated for N = 2, 3, 4 and 5 individuals, and a complete enumeration has been found for these cases: the numbers of inequivalent mating systems are 1, 5, 57 and 858, respectively. The maximal eigenvalue of the matrix q that specifies the recursion relations satisfied by the probabilities of identity have also been found for these cases. For N = 3 and 4 (and 2 trivially), circular mating gives the slowest rate of approach to genetic uniformity of those systems that do evolve to uniformity, but for N = 5 there are two other mating systems that have a slower rate of convergence, and for N = 6 partial results show that there are many such examples.Deceased 相似文献
4.
Effect of exogenous fatty acids on zygote formation in Saccharomyces cerevisiae was studied. Arachidonic and oleic acids considerably stimulated zygote formation, but other fatty acids tested, linoleic, linolenic, stearic and palmitic acids, did not. Pretreatment experiments with arachidonic acid showed that the stimulation of zygote formation by the fatty acid required the presence of mating pheromone.Abbreviations YPD
yeast-peptone-dextrose medium
- A530
absorbance at 530 nm 相似文献
5.
Summary Few quantitative studies have examined the ecological consequences of similarities and/or differences in mating behaviour of parapatric species. Reproductive interference occurs between several parapatric species of Australian reptile tick, due to similarities in their mating behaviour (Andrews et al. 1982a). Attempts to determine whether reproductive interference serves to maintain parapatry between Amblyomma limbatum and Aponomma hydrosauri have been hindered because of difficulties in providing conditions conducive to conspecific mating in Amb. limbatum. The present study examined whether off-host and/or onhost temperature influenced the subsequent mating behaviour (i.e. the proportion of females that mate and the time when mating occurs) of these two species. Irrespective of the temperature experienced by ticks prior to host attachment, specific on-host temperatures were needed to induce mating in Amb. limbatum (i.e. host cloacal temperatures >32° C prior to the time of peak mating activity). Significantly more Amb. limbatum females were mated and the time taken by females to mate decreased with increasing on-host temperatures. mating in Ap. hydrosauri occurred over a wider range of on-host temperatures and the time when mating occurred did not alter at different on-host temperatures. In addition, significantly more Ap. hydrosauri males moved and each male made more moves on hosts than did Amb. limbatum males. It is suggested that Ap. hydrosauri may in consequence have a competitive mating advantage over Amb. limbatum at a boundary. Similarities in mating behaviour, on the other hand, increase the probability of reproductive interference, hence reduce the reproductive fitness of colonizing females of both species. We propose that similarities and differences in mating behaviour could play a critical role in the maintenance of parapatric boundaries. 相似文献
6.
Uwe Wolfrum 《Cell and tissue research》1991,266(2):399-403
Summary Sexual stimulation of males has been reported to affect hypothalamic oxytocinergic systems. In the present study we used radioimmunoassays of micro-dissected forebrain regions and immunocytochemical analysis of Vibratome sections to study the oxytocin systems of naive males, males killed after one mating, and males mated daily with different receptive females for 3 weeks. In males that had mated once, less oxytocin-immunoreactive neurons were observed in the paraventricular (PVN), supraoptic (SON) and periventricular (NPE) nuclei than in naive males. However, after repeated matings, the number of immunoreactive neurons and their staining intensity was increased in these regions. Furthermore, additional oxytocinergic neurons could be found in the lateral subcommissural nucleus, the zona incerta and the ansa lenticularis of repeatedly mated males. Oxytocin-immunoreactive neurons were only occasionally seen in these areas in unmated males or in animals that had been killed after initial mating. Radio-immunoassays of microdissected PVN, SON, NPE and the lateral hypothalamus confirmed the reduction in oxytocin-immunoreactive levels after a first mating by a male and the increase after repeated matings. It is likely that oxytocin secretion into peripheral and portal circulation is stimulated by the endocrine conditions associated with initial mating. These immediate effects may be followed by the activation of synthesis in oxytocin neurons in several sites of the basal forebrain. 相似文献
7.
Patrick A. Garratt 《Environmental Biology of Fishes》1991,31(4):345-353
Synopsis The santerCheimerius nufar is widespread in tropical and subtropical waters of the western Indian Ocean and forms an important component of linefish catches along the east coast of southern Africa. Observations of spawning behaviour in captivity have revealed that spawning occurs during spring over a period of four months. Mating takes place at sunrise and may continue for up to 105 min (mean duration = 60 min). During spawning males become dark with prominent white markings. They become very aggressive and set up territories. Females remain a uniform silvery-pink. Mating occurs between males and females of similar sizes, culminating in egg and sperm release near the surface. Individual fish spawned up to 14 times during a morning. Streaking occurred throughout the season, with a second male joining a spawning pair and releasing gametes simultaneously. Slinger,Chrysoblephus puniceus, a dominant fish on offshore reefs in the same region, interfered with spawning throughout the season and were observed to eat eggs when they were released. The spawning strategy ofC. nufar is similar to protogynous species in several respects, indicating that this functional gonochorist may not conform to current theoretical predictions. 相似文献
8.
The agglutinability-masking factors (AMFs) of a and mating types of Issatchenkia scutulata var. scutulata were prepared from culture fluids. AMFs masked the agglutinability of opposite mating-type cells sex-specifically, just like agglutination substances responsible for sexual cell agglutination. a AMF adsorbed to cells was eluted by incubating the cells at 60°C for 10 min. AMF was prepared directly from culture fluids of cells by DEAE-cellulose ion exchange chromatography. The active part of the AMFs is thought to be a peptidyl moiety because of the sensitivity to subtilisin. The pretreatment of cells with AMF of the opposite mating-type was shown to promote zygote formation. AMF slightly inhibited growth in a cells but not in cells, while a AMF did not show any growth-inhibitory effect on either a or x cells. 相似文献
9.
H. S. Balyan A. K. Verma 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,71(1):111-118
Summary The relative efficiences of the biparental mating systems and selfing series in connection with phenotypic and geno-phenotypic selection procedures were evaluated for yield improvement in a cross HP1102 X CPAN 1681 of wheat. Two selection cycles having a 4 per cent selection intensity for grain yield were carried out following both selection procedures under the two mating systems. Following these selection procedures, a greater improvement for grain yield could be achieved with the biparental mating system than with the selfing series. During the first selection cycle, the geno-phenotypic selection procedure had an edge over phenotypic selection procedure. The realized response due to the second cycle of selection and the predicted response for the third selection cycle indicated that the phenotypic selection procedure is more efficient than the geno-phenotypic selection procedure. It is suggested that selection following intermating in early segregating generations is able to overcome several inherent limitations of the simple pedigree method as it is possible to increase genetic variation and to concentrate favourable genes and gene combinations for grain yield. An increase in grain yield was, in general, accompanied by an increase in plant height, peduncle length, 100 grain weight, tiller number and biological yield. Therefore, it is suggested that an index comprised of grain yield, plant height, tiller number, grain weight and biological yield could be used for selecting high yielding genotypes of suitable height. 相似文献
10.
Simon C. Nemtzov 《Environmental Biology of Fishes》1985,14(2-3):199-211
Synopsis The Red Sea razorfish, Xyrichtys pentadactylus, a territorial haremic labrid with dominance hierarchies within the harems. Theory predicts that primary males (fish developing initially as males) should be rare or nonexistent in haremic territorial species because the larger secondary males (males which have undergone sex and/or color change) limit access to females. Histological examination of gonads of 95 specimens showed that all males are derived from females by sex change (i.e. they are secondary males). During five months of field studies 100% of more than 200 observed matings were pair spawnings — the usual mating practice for monandric (having one type of male) species. Sex change in females was induced by male removal in nature. Isolation of four groups of females in aquaria showed that the largest female in the social group changes sex in the absence of a male, demonstrating that sex change is socially-controlled in this species. 相似文献