The S15 self-incompatibility haplotype in Brassica oleracea includes three S gene family members expressed in stigmas.
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Self-incompatibility in Brassica is controlled by a single, highly polymorphic locus that extends over several hundred kilobases and includes several expressed genes. Two stigma proteins, the S locus receptor kinase (SRK) and the S locus glycoprotein (SLG), are encoded by genes located at the S locus and are thought to be involved in the recognition of self-pollen by the stigma. We report here that two different SLG genes, SLGA and SLGB, are located at the S locus in the class II, pollen-recessive S15 haplotype. Both genes are interrupted by a single intron; however, SLGA encodes both soluble and membrane-anchored forms of SLG, whereas SLGB encodes only soluble SLG proteins. Thus, including SRK, the S locus in the S15 haplotype contains at least three members of the S gene family. The protein products of these three genes have been characterized, and each SLG glycoform was assigned to an SLG gene. Evidence is presented that the S2 and S5 haplotypes carry only one or the other of the SLG genes, indicating either that they are redundant or that they are not required for the self-incompatibility response. (+info)
Current status of reproductive behaviour in Africa.
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The current annual population growth rate of 3.2% in Africa will double the population by the year 2025. The majority of this population is below 15 years of age, and Africa concurrently also has the highest incidence of infertility in the world. Sexual behaviour, which has been poorly studied in Africa, has a direct impact on reproductive health [including fertility, infertility and sexually transmitted diseases (STDs)]. The multiple cultures and religions which characterize the African continent also affect reproductive health. Factors that have a significant effect on reproductive health in Africa include greater prevalence of extramarital/commercial sexual activity, polygamy, lower prevalence of contraceptives, reliance on traditional practices, high incidence of STDs and teenage pregnancies. High risk reproductive behaviours are predominantly displayed by adolescents, and the prevalence of STDs, including HIV (human immunodeficiency virus), is very high in this group. Pregnancy-related complications are the major cause of health-related problems in 15-19 year old girls. Maternal mortality rates in most countries remain high. Literacy rates affect these behaviours. It is apparent that changing the sexual behaviour of adolescents is one way of reversing the adverse trends, such as STD transmission, unwanted pregnancy and poor general reproductive health. (+info)
Leptin in human reproduction.
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The recent discovery of the obese (ob) gene has provided new insight into the mechanism which controls body fat mass. Leptin, a product of the ob gene, serves as the link between fat and the brain. This protein, by acting at the level of the hypothalamus, decreases food intake and increases energy expenditure. Animals that lack leptin (ob/ob mice) develop profound obesity and become infertile. Treatment of these animals with leptin reduces food intake and restores normal fertility. Although leptin is important for the control of fat stores in certain species, the role of this substance in the development of human obesity remains obscure. However, it has been speculated that, in humans, obesity is related to leptin resistance. The relationship between fat and reproduction has been recognized for >20 years. This article discusses the relationship between leptin and human reproduction. In particular, recent knowledge about the possible role of leptin in various conditions such as puberty, polycystic ovary syndrome and pregnancy is reviewed. Also, the article discusses the possible role of leptin in ovarian function and the relationship of this protein with gonadal steroids. It is expected that future research will clarify the physiological importance of leptin in human reproductive function. (+info)
Interspecies transfer of female mitochondrial DNA is coupled with role-reversals and departure from neutrality in the mussel Mytilus trossulus.
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Mussels of the genus Mytilus have distinct and highly diverged male and female mitochondrial DNA (mtDNA) genomes with separate routes of inheritance. Previous studies of European populations of Mytilus trossulus demonstrated that 33% of males are heteroplasmic for a second mtDNA genome of increased length and that hybridization with Mytilus edulis does not block mtDNA introgression, in contrast to reports for American populations. Here, we demonstrate that the female mtDNA type of M. edulis has replaced the resident female mtDNA type of European M. trossulus. This is supported by COIII sequence data indicating that the female mtDNA of European M. trossulus is very similar to that of M. edulis and that in phylogenetic trees, the mtDNAs of these two species cluster together but separately from American M. trossulus sequences, the latter not being disturbed by introgressive hybridization. We also provide evidence that the mtDNA genome of increased length found in heteroplasmic males of European M. trossulus derives from a recent partition of an introgressed M. edulis female type into the male route of transmission. Neutrality tests reveal that European populations of M. trossulus display an excess of replacement polymorphism within the female mtDNA type with respect to conspecific American populations, as well as a significant excess of rare variants, of a similar magnitude to those previously reported for the invading European M. edulis mtDNA. Results are consistent with a nearly neutral model of molecular evolution and suggest that selection acting on European M. trossulus mtDNA is largely independent of the nuclear genetic background. (+info)
Influence of prepartum body condition score change on reproduction in multiparous beef cows calving in moderate body condition.
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Multiparous, spring-calving beef cows (n = 250) were used to determine whether large changes in body energy reserves during mid- to late gestation influenced subsequent reproductive performance of cows calving in moderate body condition. In three states, cows were blocked by BW and body condition score (BCS; 1 = emaciated to 9 = obese) then allotted to receive either a high or low plane of nutrition from late summer to early winter over a 3-yr period. This generated an array of BCS by the beginning of the last trimester of pregnancy when cows were grouped by BCS as follows: Group 1, BCS < or = 4; Group 2, BCS of 5 or 6; and Group 3, BCS > or = 7. Each group was managed so that individual cows would calve with a BCS of 5 to 6. At the time of group assignment, mean BW and BCS differed (P < .01) among groups and were 480 kg and 3.6, 541 kg and 5.5, and 594 kg and 7.1 for Groups 1 to 3, respectively. Within 28 d before calving, BW and BCS were similar (P > .20) among groups averaging 555 kg and 5.1. Prepartum BCS changes averaged 1.4, -.4, and -2.0 units for Groups 1 to 3, respectively (P < .01). Cows were managed as a single group after calving in each state. Location effect was significant for the prepartum and postpartum BW and BCS changes but not for postpartum reproductive performance. Significant location x BCS group interactions were found for the 90-d prepartum BW, BCS at calving, and prepartum changes in BW, but were caused by differences in magnitude among locations. The percentage of cows with luteal activity at the start of a subsequent breeding season was not affected (P > .20) by either location or BCS group, and averaged 66%. Mean pregnancy rates at 20, 40, and 60 d of a subsequent breeding season were 55, 76, and 89% for Group 1; 51, 67, and 82% for Group 2; and 64, 79, and 89% for Group 3 (P > .30). Mean days to conception were 89, 87, and 85 for Groups 1 to 3, respectively (P = .70). Neither calf birth weight (x = 38.6 kg) nor adjusted 205-d weight (x = 223.6 kg) were affected by prepartum BW and BCS changes. We conclude that reproductive performance of cows calving in moderate body condition is not influenced by large changes in body energy reserves during the last trimester of pregnancy. (+info)
Cytogenetic evidence for a species complex within Anopheles pseudopunctipennis theobald (Diptera: Culicidae).
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Anopheles pseudopunctipennis was collected from Acapulco, Mexico and Sallee River, Grenada, West Indies and used in cross-mating experiments. Larvae from the cross, Mexico female X Grenada male, died in the third instar. However, adult progeny were obtained from the reciprocal cross Grenada female x Mexico male. These hybrid males had testes with apparently normal appearance but some without viable sperm. Polytene chromosomes obtained from hybrid females exhibited extensive asynapsis of the X chromosomes. Previously undescribed fixed inversion differences between the two populations were noted on the X chromosome. It is concluded that the two populations belong to different species. The Grenada population is designated An. pseudopunctipennis species C, since it is the third taxon recognized in this species complex. (+info)
The centrosomin protein is required for centrosome assembly and function during cleavage in Drosophila.
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Centrosomin is a 150 kDa centrosomal protein of Drosophila melanogaster. To study the function of Centrosomin in the centrosome, we have recovered mutations that are viable but male and female sterile (cnnmfs). We have shown that these alleles (1, 2, 3, 7, 8 and hk21) induce a maternal effect on early embryogenesis and result in the accumulation of low or undetectable levels of Centrosomin in the centrosomes of cleavage stage embryos. Hemizygous cnn females produce embryos that show dramatic defects in chromosome segregation and spindle organization during the syncytial cleavage divisions. In these embryos the syncytial divisions proceed as far as the twelfth cycle, and embryos fail to cellularize. Aberrant divisions and nuclear fusions occur in the early cycles of the nuclear divisions, and become more prominent at later stages. Giant nuclei are seen in late stage embryos. The spindles that form in mutant embryos exhibit multiple anomalies. There is a high occurrence of apparently linked spindles that share poles, indicating that Centrosomin is required for the proper spacing and separation of mitotic spindles within the syncytium. Spindle poles in the mutants contain little or no detectable amounts of the centrosomal proteins CP60, CP190 and (gamma)-tubulin and late stage embryos often do not have astral microtubules at their spindle poles. Spindle morphology and centrosomal composition suggest that the primary cause of these division defects in mutant embryos is centrosomal malfunction. These results suggest that Centrosomin is required for the assembly and function of centrosomes during the syncytial cleavage divisions. (+info)
Involving men in reproductive health: the Young Men's Clinic.
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OBJECTIVES: This report describes the population of young men who use the Young Men's Clinic in New York City, presents a profile of their reproductive behaviors, and describes the clinic's model of service delivery. METHODS: Data were gathered through a routine clinic visit form administered by clinic staff. RESULTS: The clinic sees approximately 1200 predominately Dominican young men each year for a wide range of clinical and mental health services. Two thirds of clients had ever been sexually active, three quarters had ever used birth control, and 69% had used birth control at their last sexual encounter. CONCLUSIONS: The Young Men's Clinic may serve as a model for health care delivery to adolescent and young adult males. (+info)