Mutant yolk proteins lead to female sterility in Drosophila.

Specific mutations in the yolk protein genes, yp1 and yp2, of Drosophila melanogaster cause the yolk proteins (YPs) they encode to precipitate, ultimately resulting in female sterility. YPs of the yp1 mutant fs(1)1163 are secreted normally but then precipitate as globules and occasionally as crystalline fibers in the subbasement membrane space of the fat body (Butterworth et al., 1991, J. Cell Biol. 112, 727-737). The present ultrastructural and immunological studies of the fat body of the yp2 mutant fs(1)K313 show that YP also precipitates as globules in the same tissue compartment. The globules are also incapable of passing into the hemolymph but they are morphologically distinct from those of fs(1)1163. Similar analyses were performed on developing oocytes in wild type and both mutant strains. YP-containing aggregates, ultrastructurally similar to those in the fat body of each respective mutant, were found in the space between the plasmalemma and the vitelline membrane and embedded within the membrane itself. The evidence suggests that the precipitates interfere with the correct assembly of the eggshell membranes, leading to the sterile phenotype. Immunogold studies demonstrate that newly synthesized YPs in the normal and mutant strains share secretory vesicles with putative, vitelline membrane proteins and that the translocation of follicle cell YP is not through the membrane along the interfollicular spaces but directly through the plasmalemma facing the oocyte. Further the YP precipitates in the mutants permit visualization of the polarity of exocytosis of YP from the follicle cells.     

Seroprevalence of Toxoplasma gondii infection in female sterility patients in China

Toxoplasmosis is an important parasitic disease worldwide and is related to certain psychiatric disorders and sterility. In the present study, serum samples from 882 female sterility patients and 107 pregnant-puerperant women were assayed for anti- T. gondii IgG antibodies using ELISA. The overall T. gondii seroprevalence was 14.8%. In the female sterility patients, 15.9% (140/882) were seropositive and, in the pregnant-puerperant women, 5.6% (6/107) were positive for anti- T. gondii IgG antibodies. There was a significant difference between the 2 groups ( P < 0.05). The samples were further divided into 5 groups based on age, but no significant difference was found among the 5 groups (P > 0.05). Results of the present study argue for more attention to prevention of T. gondii infection in the female population and, in particular, women of childbearing age.     

Megagametophyte development and female sterility in Maytenus obtusifolia Mart. (Celastraceae)

Protoplasma - Reproduction in flowering plants is closely related to the megagametophyte, since the megagametophyte is involved in pollen tube reception and contains the two female...     

QTLs for hybrid fertility and their association with female and male sterility in rice

Hybrid sterility is one of the major barriers to the application of wide crosses in plant breeding and is commonly encountered in crosses between indica and japonica rice varieties. Ten mapping populations comprised of two reciprocal F2 and eight BC₁F₁ populations generated from the cross between Ilpumbyeo (japonica) and Dasanbyeo (indica) were used to identify QTLs and to interpret the gametophytic factors involved in hybrid fertility or sterility between two subspecies. Frame maps were constructed using a total of 107 and 144 STS markers covering 12 rice chromosomes in two reciprocal F2 and eight BC₁F₁ populations, respectively. A total of 15 main-effect QTLs and 17 significant digenic-epistatic interactions controlling spikelet fertility (SF) were resolved in the entire genome map of F₂ and BC₁F₁ populations. Among detected QTLs responsible for hybrid fertility, four QTLs, qSF5.1 and qSF5.2 on chromosome 5, qSF6.2 on chromosome 6, and qSF12.2 on chromosome 12, were identified as major QTLs since they were located at corresponding positions in at least three mapping populations. Loci qSF5.1, qSF6.1 and qSF6.2 were responsible for both female and male sterility, whereas qSF3.1, qSF7 and qSF12.2 affected the spikelet fertility only through embryosac factors, and qSF9.1 did through pollen factors. Five new QTLs identified in this study will be helpful for understanding the hybrid sterility and for breeding programs via inter-subspecific hybridization.     

泌乳素及其受体的研究进展

泌乳素(PRL)又名催乳素,是由腺垂体及一些垂体外器官如乳腺、胸腺、脾脏等合成的一种多肽类激素,以内分泌、自分泌、旁分泌的形式发挥作用,其广泛参与机体生长发育、物质代谢、性腺功能调节、应激反应、免疫调节等。泌乳素通过与其受体(PRL receptor,PRLR)在靶细胞的细胞膜表面结合,激活下游的信号转导通路,发挥其生物学作用。由于泌乳素在人体内复杂的生物学效应,泌乳素及其受体又与乳腺癌、泌乳素瘤等多种疾病的发生发展及其预后密切相关。本文就泌乳素发挥效应时对其受体的激活、受体激活后的信号转导机制以及泌乳素同相关疾病的联系进行了综述,相信泌乳素及其受体的研究将为这些疾病的治疗提供重要的方向。     

Prolactin influences autoimmune disease activity in the female B/W mouse

Prolactin, an anterior pituitary hormone, stimulates humoral and cell-mediated immunity. This study investigated effects of manipulating prolactin levels in the autoimmune B/W mouse model of SLE. A group of B/W females was treated with daily injections of the prolactin-suppressing drug, bromocriptine. These mice had delayed elevation of anti-DNA antibodies and serum IgG; longevity was increased compared to control mice. Functioning syngeneic pituitary glands, implanted under the renal capsule, produced prolonged hyperprolactinemia in a separate group of female B/W mice. Hyperprolactinemic animals were characterized by premature albuminuria, elevated circulating gp70IC and IgG, and accelerated mortality. Analyses of thymic and splenic lymphocytes revealed no differences in lymphocyte subpopulations in mice with altered prolactin levels. This is the first report to substantiate an immunomodulatory role for prolactin in B/W mice. Further evaluation of this model may identify specific means of intervening clinically with immunosuppressive hormone-modulating therapy in SLE.     

A mutant dec-1 transgene induces dominant female sterility in Drosophila melanogaster

The Drosophila dec-1 gene produces three proproteins required for female fertility and eggshell assembly. The three proproteins are distinguished by their C termini. Fc106, the most abundant proprotein, is cleaved within the vitelline membrane to three mature derivatives in a developmentally regulated manner. To define sequences within fc106 that are critical for its function, we created wild-type and mutant versions of an fc106 cDNA transgene. The functional consequences of the mutations were assessed in dec-14, a female-sterile splicing mutant that does not produce the fc106 isoform. The fertility of dec-14 females was restored by the introduction of either a wild-type transgene or a transgene bearing a C-terminal deletion that included fc106-specific sequences. Surprisingly, the removal of internal coding sequences created an aberrant DEC-1 proprotein that induced female sterility when introduced into wild-type flies. Dominant female sterility was not associated with larger deletions that included the fc106 N terminus, suggesting that abnormal juxtaposition of N- and C-terminal sequences in the aberrant proprotein interfered with endogenous DEC-1 proteins. Changes in the fractionation behavior of the endogenous fc106 C-terminal derivative, s60, and morphological changes in the endochorion in response to expression of the aberrant proprotein support this interpretation.     

Impaired cumulus mucification and female sterility in tumor necrosis factor-induced protein-6 deficient mice

Mucification of the cumulus layer around the oocyte is an obligatory process for female fertility. Tumor necrosis factor-induced protein-6 (TNFIP6 or TSG6) has been shown to be specifically expressed during this process. We have generated TNFIP6-deficient mice and tested the ability of their cumulus cells to undergo mucification. Cumulus cell-oocyte complexes fail to expand in TNFIP6-deficient female mice because of the inability of the cumulus cells to assemble their hyaluronan-rich extracellular matrix. The impaired cumulus matrix formation is due to the lack of covalent complexes between hyaluronan and the heavy chains of the inter-alpha-trypsin inhibitor family. As a consequence, TNFIP6-deficient females are sterile. Cultured TNFIP6-deficient cumulus cell-oocyte complexes also fail to expand when stimulated with dibutyryl cyclic AMP or epidermal growth factor. Recombinant TNFIP6 is able to catalyze the covalent transfer of heavy chains to hyaluronan in a cell-free system, restore the expansion of Tnfip6-null cumulus cell-oocyte complexes in vitro, and rescue the fertility in Tnfip6-null females. These results provide clear evidence that TNFIP6 is a key catalyst in the formation of the cumulus extracellular matrix and indispensable for female fertility.     

Programmed cell death induces male sterility in Actinidia deliciosa female flowers.

The importance of programmed cell death (PCD) during the life cycle of plants is well established, although the underlying molecular mechanisms are still poorly defined. An emerging system for the study of PCD during development in plants is that of sex organ abortion. In this work we investigate the degeneration of microspores in the anthers of Actinidia deliciosa female flowers. The kiwifruit, A. deliciosa, is a dioecious species native to China. Pollen development in female flowers is equivalent to pollen development in the male flowers, until the microspores are released from the tetrads. At this time the first differences appear, and include the condensation and shrinkage of the cytoplasm, blebbing of the plasma membrane and of the nuclear envelope, and condensation of chromatin. However, at the time these events are occurring, all other cellular organelles, including mitochondria, have their structures well preserved. Fragmentation of DNA was detected in situ by the TUNEL procedure, which involves the end labeling of the DNA fragments by terminal deoxynucleotidyl transferase with UTP conjugated to a detectable marker. This assay confirmed the morphological characterization of PCD in this system.     

Influence of fetal position on neonatal androgen-induced sterility and sexual behavior in female rats

Two aspects of reproductive function were examined in relation to female fetus' contiguity to intrauterine male littermates. Following injection of 3.5 μg testosterone propionate (TP) on Day 3, females that had been positioned in utero between two males became sterile earlier in life than those located in utero between two females. Anogenital distances on Days 1 and 3 prior to neonatal treatment with TP were greater in females located in utero between two males than in females residing between two females in utero, suggesting that females developing between two males may have been exposed prenatally to a masculinizing substance, presumably an androgen. No reliable contribution of litter composition was apparent with respect to differentiation of female sexual behavior. Results indicate that littermate hormonal influence is present or effective and can be detected in a neonatally androgenized preparation.     

Prolactin directly stimulates transcellular active calcium transport in the duodenum of female rats

Prolactin has been postulated to be a novel calcium-regulating hormone during pregnancy and lactation. It stimulates both passive and active duodenal calcium transport in several experimental models. Our study was performed on sexually mature female Wistar rats (200-250 g) to study the direct action of prolactin on calcium transport in the duodenum using the Ussing chamber technique. To evaluate the effect of prolactin on total calcium transport in the duodenum, we intraperitoneally injected rats with 0.4, 0.6, and 0.8 mg/kg prolactin. The total calcium transport was divided into voltage-dependent, solvent drag-induced, and transcellular active fluxes by applying short-circuit current and by mucosal glucose replacement with mannitol. The effect of prolactin on each flux was studied separately. Finally, to evaluate the direct action of prolactin on duodenal transcellular active flux, we directly exposed duodenal segments to prolactin that had been added to the serosal solution with or without calcium transport inhibitors. We found that 0.6 and 0.8 mg/kg prolactin ip significantly increased the total mucosa-to-serosa calcium flux from the control value (nmol x hr(-1) x cm(-2)) of 34.53+/-6.81 to 68.07+/-13.53 (P < 0.05) and 84.43+/-19.72 (P < 0.01), respectively. Prolactin also enhanced the solvent drag-induced calcium flux and transcellular active calcium flux, but not the voltage-dependent calcium flux. The duodenal segments directly exposed to 200, 400, and 800 ng/mL prolactin showed a significant increase in the transcellular active calcium absorption in a dose-dependent manner, i.e., from the control value (nmol x hr(-1) x cm(-2)) of 2.94+/-0.47 to 5.45+/-0.97 (P < 0.01), 8.09+/-0.52 (P < 0.001), and 18.42+/-2.92 (P < 0.001), respectively. Its direct action was inhibited by mucosal exposure to 50 microM lanthanum chloride, a calcium transporter protein competitor, and serosal exposure to 0.1 mM trifluoperazine, a Ca2+-ATPase inhibitor. These studies demonstrate that the duodenum is a target organ of prolactin, which enhances transcellular active calcium transport.     

Correlated response in male and female sterility to selection for pupa weight in Tribolium castaneum

Summary The correlated responses in male and female sterility to 50 generations of individual selection for pupa weight in Tribolium were analyzed. Two replicate lines (S-lines) were selected for heavier pupa weight and stabilizing selection for pupa weight was practiced in two replicate control lines (C-lines). There was close agreement between replicates in both sets of lines for direct and correlated responses. The rate of inbreeding has been constant for all lines (approximately 0.5% per generation).Regression of generation means for pupa weight on generation of selection indicated a significant linear regression in the direct response for both lines. The linear increases of 46 and 55 g. per generation in the S-lines accounted for 98% of the variation among generations and the linear decreases of 5 and 10 g. per generation in the C-lines accounted for 70–90% of the variation in the generation means.Maximum likelihood estimators were used to calculate the frequency of male and female sterility for each generation and line. Average sterility in the base population ranged from about 4 to 12% for both sexes. Polynomial regressions of percent sterility on generation of selection showed that quadratic and higher order regressions were occasionally significant but accounted for a relatively small fraction of the total variation. In the two S-line replicates, linear regression coefficients of percent sterility on generation number were 0.16±.09 and 0.20±.07 for males and 0.72±.08 and 0.54±.08 for females, suggesting a larger correlated response in female than in male sterility. In the C-lines, linear regression coefficients were 0.02±.08 and –.12±.05 for males in the two replicates and –.05±.05 and –.05±.05 for females. Estimates of realized genetic correlations between pupa weight and sterility in the S-lines ranged from 0.04 to 0.14 for males and from 0.14 to 0.37 for females when the heritability of sterility was allowed to take on values from 0.05 to 0.25.Supported by NSF Grants G-1238 and GB-5987, NIH Grant GM-16074 and NIH Fellowship 1 FO2 GM4 5130-01.