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PubMed2004

Surfactant protein D is present in the human female reproductive tract and inhibits Chlamydia trachomatis infection.

Surfactant protein D (SP-D) is a lung collectin involved in innate host defence mechanisms in the lung. SP-D is also expressed at other mucosal sites throughout the human body. In the present study, we show that SP-D mRNA and protein are expressed in the human female reproductive tract. SP-D protein was localized in the apical portion of the reproductive epithelial cells. We also demonstrate that endometrial and endocervical cell lines and primary endocervical cells in culture produce SP-D mRNA and protein. Chlamydia trachomatis is an intracellular pathogen that infects the female reproductive tract, primarily the cervix, and is responsible for the most prevalent infectious disease in the USA. Untreated chlamydial infections of the female reproductive tract often result in sterility of the infected woman. Since SP-D protein is produced in cervical glands, we examined the effect of SP-D on chlamydial infection of cervical epithelial cells in vitro. We found that SP-D protein inhibits the infection of HeLa cells (an endocervical epithelial cell line) by C. trachomatis in a dose-dependent manner. We further demonstrate that the SP-D lectin-binding domain is involved in inhibiting infection of HeLa cells by Chlamydia. In conclusion, we detected SP-D in the female reproductive tract and determined that one of the functions of the SP-D protein may be to protect cervical epithelial cells from infection by C. trachomatis.

Animals↗

PubMed1988

Evaluation of serum-associated embryotoxicity/mutagenicity in females with reproductive dysfunctions using preimplantation mouse embryos in vitro.

Reproductive failures may be caused by chromosomal anomalies, complex interactions of maternal/fetal genotype and environmental factors. Some of them have also been attributed to undefined maternal serum factor(s). We have developed an assay to evaluate maternal-serum associated embryotoxicity/mutagenicity using the preimplantation mouse embryo. It is based on in vitro culture of 8-cell mouse embryos for 48 h in the presence of 10% sera from females with reproductive dysfunction along with suitable controls. The human sera were obtained from three groups of females: (i) with normal reproductive histories (negative controls), (ii) undergoing cancer chemotherapy (positive controls), and (iii) with a history of failing to achieve or maintain pregnancy (test group). The preimplantation mouse embryos were cultured in the three types of human sera and female rat serum (as an internal control for each experiment) and evaluated for toxicity (embryo survival) and mutagenicity (as measured by SCE). Embryos cultured in serum from women with normal reproductive histories and female rats had survival rates of 70.8 +/- 4.3 and 78.9 +/- 0.9%, respectively. The SCE frequencies for these two sera types were similar: 15.7 +/- 0.2 SCEs/cell (rat) and 16.3 +/- 0.3 SCEs/cell (human). Mouse embryos cultured in medium supplemented with serum from females undergoing chemotherapy had significantly (P less than 0.01) reduced survival (33.7 +/- 5.2%) and significantly (P less than 0.01) increased SCEs/cell (26.5 +/- 0.6). The effect of sera from women with histories of reproductive failures on preimplantation mouse embryos was variable and individual specific. Approximately 40% of the test group female sera yielded survival and SCEs/cell comparable to the sera from patients undergoing chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Spontaneous↗

PubMed1996

Analysis of health insurance cover for reproductive immunology.

The objective of this study was to document the current state of health insurance cover for reproductive immunology in the USA. A survey of couples who had given birth to a child within the last 2 years while they were being treated with lymphocyte immunotherapy at the Reproductive Medicine Clinic of the Finch University of Health Sciences/The Chicago Medical School (FUHS/CMS), North Chicago, IL, USA, produced 61 completed questionnaires from couples in 16 states, representing a response rate of 55%. The Reproductive Medicine Clinic at the FUHS/CMS is a major centre that treats couples with reproductive immunological problems. These couples had experienced repeated pregnancy losses that were diagnosed as immunological in nature. This prospective study documents the insurance reimbursement of couples receiving lymphocyte immunotherapy who subsequently became parents. The findings indicate that 80% of couples had insurance claims initially denied for reproductive immunotherapy-related services. The most common reason given for a denied claim was that the treatment was experimental. Couples took further action and almost all received cover. Cover for immunotherapy-related services averaged 65% of the cost. The percentage of expenses covered by the insurance was quite variable. The survey indicates that insurance cover is provided if patients are willing to take action.

Abortion, Spontaneous↗

PubMed2002

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) disrupts early morphogenetic events that form the lower reproductive tract in female rat fetuses.

In female rats, in uteroexposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during critical periods of organogenesis causes a permanent thread of tissue, consisting of a core of mesenchyme surrounded by keratinized epithelia, across the vaginal opening. The objective of the current study was to determine the earliest time after exposure to TCDD during fetal development that morphological changes in the development of the lower reproductive tract could be detected. In addition, the spatio-temporal expression of several growth factors within the developing reproductive tract was investigated to provide insight into the mechanism of action involved in TCDD-induced vaginal thread formation. Pregnant rats received a single oral dose of 1.0 microg TCDD/kg on gestation day (GD) 15. Dams were sacrificed on GD 17, 18, 19, and 21 and individual reproductive tracts were isolated from female fetuses. As early as GD 18, TCDD produced distinct abnormalities in the female reproductive tract. The width of mesenchyme separating the Mullerian ducts was significantly greater in TCDD-exposed female GD 18 and 19 fetuses and the zone of unfused Mullerian ducts was substantially increased on GD 19 and 21. TCDD induced alterations within the developing reproductive tract in the subcellular and temporal expression of transforming growth factor-beta3 (TGF-beta3) and epidermal growth factor receptor (EGFR). DNA array analysis suggested effects on several genes expressed on GD 18 and 19.

Abnormalities, Drug-Induced↗

PubMed2002

Endothelial cell proliferation in male reproductive organs of adult rat is high and regulated by testicular factors.

Endothelial cells in the intact adult are, apart from those in the female reproductive organs, believed to be quiescent. Systematic examination of endothelial cell proliferation in male reproductive organs has not been performed and was therefore the aim of the present study. Intact adult rats were either pulse labeled or long-term labeled with bromodeoxyuridine to label proliferating cells. The roles of Leydig cells and testosterone were examined after castration or treatment with the Leydig cell toxin ethane dimethane sulfonate (EDS) and testosterone substitution. After perfusion fixation, all blood vessels remained open and were easily identified. In all male reproductive organs studied, particularly in the testis and epididymis, endothelial cell proliferation was considerably higher than in other tissues such as the liver, brain, and muscle. Proliferating endothelial cells were observed in all types of blood vessels in male reproductive organs, but other characteristics of new blood vessel formation were not seen. High endothelial cell proliferation may reflect a continuous high turnover of endothelial cells rather than classical angiogenesis. In the epididymis, the ventral and dorsolateral prostate lobes, and the seminal vesicles, endothelial cell proliferation decreased after testosterone withdrawal and increased following testosterone treatment. In the testis, endothelial cell proliferation was decreased after Leydig cell depletion but remained low after testosterone substitution. High, hormonally regulated endothelial cell proliferation is not unique to the female but is also seen in the male reproductive organs.

Androgens↗

PubMed2005

Expression of the reproductive female-specific vitellogenin gene in endocrinologically induced male and intersex Cherax quadricarinatus crayfish.

In oviparous females, the synthesis of the yolk precursor vitellogenin is an important step in ovarian maturation and oocyte development. In decapod Crustacea, including the red-claw crayfish (Cherax quadricarinatus), this reproductive process is regulated by inhibitory neurohormones secreted by the endocrine X-organ-sinus gland (XO-SG) complex. In males, the C. quadricarinatus vitellogenin gene (CqVg), although present, is not expressed under normal conditions. We show here that endocrine manipulation by removal of the XO-SG complex from male animals induced CqVg transcription. The CqVg gene was expressed differentially during the molt cycle in these induced males: no expression was seen in the intermolt stages, but expression was occasionally detected in the premolt stages and always detected in the early postmolt stages. Relative quantitation with a real-time reverse transcriptase-polymerase chain reaction showed that expression of CqVg in induced early postmolt males was an order of magnitude lower than that in reproductive females, a finding that was consistent with RNA in situ hybridization results. The SDS-PAGE of high-density lipoproteins from the hemolymph of endocrinologically induced early postmolt males did not show the typical vitellogenin-related polypeptide profile found in reproductive females. On the other hand, removal of the XO-SG complex from intersex individuals, which are chromosomally female but functionally male and possess an arrested female reproductive system, induced the expression, translation, and release of CqVg products into the hemolymph, as was the case for vitellogenic females. The expression of CqVg in endocrinologically manipulated molting males and intersex animals provides an inducible model for the investigation and understanding of the endocrine regulation of CqVg expression and translation in Crustacea as well as the relationship between the endocrine axes regulating molt and reproduction.

Animals↗

PubMed1982

Effect of photoperiod on the growth of reproductive organs and on pineal N-acetyltransferase rhythm in male rats treated neonatally with testosterone propionate.

Neonatal administration of testosterone propionate (TP) sensitized male Wistar rats to photoperiodic regulation of reproduction. Testicular, seminal vesicle and prostate weights in 105-day-old TP-treated rats housed under natural photoperiodic conditions were lower during autumn and winter than during spring and summer. The reproductive organ weights in 75-day-old TP-treated rats kept under artificial lighting regimens were smaller under photoperiods shorter than 10 h per day than under photoperiods of 10 h per day or longer. In TP-treated males, pinealectomy prevented the decrease in reproductive organ weights induced by short days. The pineal involvement in the photoperiodic regulation of reproduction might be mediated by the rhythm in melatonin. Under a 8L:16D regimen, when reproductive organ weights were decreased, the period of high night N-acetyltransferase activity, which determines the period of the increased melatonin production, lasted about 1 h longer than under 12L:12D.

Acetyltransferases↗

PubMed1999

Cellular localization of estrogen receptor beta messenger ribonucleic acid in cynomolgus monkey reproductive organs.

There is now evidence that the recently identified estrogen receptor (ER) beta is more widely distributed in the body than is ER-alpha. In order to gain more information about the role of ER-beta in reproduction, we have investigated by in situ hybridization the localization of mRNA expression of this ER subtype in adult monkey reproductive organs. In the pituitary gland of animals of both sexes, in both the anterior and intermediate lobes, a large number of cells were positive. No specific signal was observed in the posterior lobe. In the ovary, granulosa cells in primary and growing follicles highly expressed ER-beta mRNA. The theca interna cells were also strongly labeled. In some corpora lutea, the luteal cells were strongly labeled, while in other ones, the signal was weak. A hybridization signal was also detected in the ovarian surface epithelium. In the uterus, ER-beta mRNA was found in high concentration in glandular epithelial cells and stromal cells of the endometrium, while weaker labeling was consistently observed in smooth muscle cells. In the mammary gland, labeling was detected in the epithelial cells of acini and interlobular ducts as well as stromal cells. In the testis, specific labeling was detected in the seminiferous epithelium whereas the interstitial Leydig cells were unlabeled. Although it was not possible to clearly identify all the positive cell types, it appears that Sertoli cells as well as the vast majority of germinal cells express ER-beta mRNA. In the prostate, the secretory epithelial cells exhibited a specific autoradiographic reaction while the stromal cells did not show mRNA expression. The epithelial cells of the prostatic urethra showed a strong labeling. No hybridization signal was detected in the seminal vesicles. It then appears quite clear that ER-beta is expressed in a cell-specific manner in all the monkey reproductive organs studied. In the female, the wide distribution of these receptors in the ovary and uterus suggests that ER-beta may play an important role in the mediation of the known effects of estrogen in reproduction functions. In the male testis and prostate, ER-beta has been found in cells that contain very little or no ER-alpha. The role of circulating or locally produced estrogens in the male reproductive system remains to be clarified.

Animals↗

PubMed2000

Inhibition of reproductive maturation and somatic growth of Fischer 344 rats by photoperiods shorter than L14:D10 and by gradually decreasing photoperiod.

Photoperiod is the major regulator of reproduction in temperate-zone mammals. Laboratory rats are generally considered to be nonphotoresponsive, but young male Fischer 344 (F344) rats have a uniquely robust response to short photoperiods of 8 h of light. Rats transferred at weaning from a photoperiod of 16 h to photoperiods of < 14 h of light slowed in both reproductive development and somatic growth rate. Those in photoperiods < 13 h of light underwent the strongest responses. The critical photoperiod of F344 rats can be defined as 13.5 h of light, but photoperiods of </= 12.5 h are required to fully suppress reproduction and somatic growth. This demonstrates that the 12-h photoperiod that is standard in some laboratory colonies would have significant effects on reproductive maturation and growth rate of this common rat strain. Young F344 rats in decreasing photoperiods that mimic natural change experienced delayed reproductive development and decreased growth rate to a greater extent and for a longer duration than those transferred at birth to a short photoperiod. The effects of gradual changes in photoperiod persisted for at least 12 wk after weaning. This indicates that young male F344 rats possess responses to photoperiod that would result in functional photoperiodism in a wild mammal.

Animals↗

PubMed2004

HIV and reproduction.

PURPOSE OF REVIEW: Three quarters of individuals infected with HIV are in their reproductive years and can expect an almost normal life expectancy under antiretroviral treatment. Many of them want to have a child and reproductive counselling and care can offer a sharp reduction in both sexual and vertical transmission rates. RECENT FINDINGS: Most couples with HIV are formed by an infected man and an uninfected woman; in this setting, semen washing coupled with reproductive technology can be applied to eliminate the risk of sexual transmission of the virus. Semen washing is a processing method which reduces both HIV RNA and DNA to undetectable amounts. In couples in which only the woman is infected, self-insemination might be indicated. When both partners are carrying HIV, semen washing can be used in couples with different viral strains. HIV can be vertically transmitted and the risk of infection for the infant can be decreased to approximately 1% by reducing maternal viral load, elective caesarean section and avoidance of breastfeeding. In pregnancy the efficacy of antiretroviral treatment should be balanced against the possibility of embryonic or fetal toxicity. Caesarean section, performed electively, has proven its protective efficacy, without significant maternal morbidity. Its role should now be reassessed in mothers with undetectable viral load. Breastfeeding, discouraged to avoid postnatal transmission, might be possible in the future, with antiretroviral therapy capable of suppressing viral excretion in maternal milk. SUMMARY: Semen washing, reproductive technology, antiretroviral therapy and obstetrical care can work in sequence to allow safe reproduction in couples infected with HIV.

Female↗

PubMed1999

Consent documents, reproductive issues, and the inclusion of women in clinical trials.

PURPOSE: To describe language used in consent documents at one academic medical center to inform women participating in studies of potential reproductive and fetal risks. METHOD: The authors reviewed consent document language describing reproductive and fetal risks in 114 approved protocols. Protocols were identified as being of high, low, or unknown risk based upon FDA drug-risk and radiation-risk categories. RESULTS: Although most consent documents advised women against participating for one or more pregnancy-related reasons, specific information about reproductive or fetal risks was included in fewer consent documents: 8 (73%) of the high-risk studies, 12 (40%) of the low-to-moderate-risk studies, and 29 (40%) of the unknown-risk studies. CONCLUSIONS: Investigators often omit fetal risk information from consent documents. Full disclosure of reproductive and fetal risks in consent documents and discussions can be taught and modeled during the research training period. The authors present a template with language that can be used in consent documents and recommend ongoing discussion of reproductive and fetal risks with women subjects throughout the study period.

Abnormalities, Drug-Induced↗

PubMed2005

Natural killer cells and reproductive failure.

PURPOSE OF REVIEW: The purpose of this review is to provide an update of what is known about the role of natural killer cells in reproduction. RECENT FINDINGS: In humans, natural killer cells are present in abundance in the uterus and appear to play an important role in early pregnancy. Women with reproductive failure have been shown to have higher levels of natural killer cell numbers and activity in peripheral blood. The evidence relating to uterine natural killer cells, however, is contradictory. While earlier studies suggested an increase of uterine natural killer cells in women with recurrent pregnancy loss, more recent investigations have not confirmed this trend. Uterine natural killer cell number or activity appear to be higher in spontaneous abortions with normal chromosomes compared with chromosomally abnormal pregnancies. Furthermore, a rise of the cytotoxic CD56(dim)CD16+ natural killer cell subset is seen in the follicular fluid of patients with idiopathic infertility and it is postulated that this increase may decrease fertilization rates in this group. SUMMARY: Natural killer cell number and activity appear to be altered in women with reproductive failure although it is unclear if the difference is a cause or effect of reproductive failure. Whether natural killer cells are increased or decreased depends on whether peripheral blood, endometrium or first-trimester decidua is analyzed. Until more is known about the role of natural killer cells in normal pregnancy, there does not appear to be any benefit in offering natural killer cell testing to women with reproductive failure outside of research protocols.

Abortion, Habitual↗

PubMedDate not supplied

Sequential classification of endocrine stages during reproductive aging in women: the FREEDOM study.

OBJECTIVE: Reproductive aging involves complex endocrine changes affecting women's fertility, health, and well-being; however, understanding of the specific changes involved is limited by the lack of detailed quantitative studies. We undertook a thorough study with the aim of characterizing the different endocrine stages involved in female reproductive aging. DESIGN: FREEDOM is a cohort study designed to determine the endocrine changes during reproductive aging in women. Here, we ascertained the different endocrine patterns in a representative population and developed a staging system. In this study, 112 women aged 30 to 58 years collected daily urine samples over a 6- to 18-month period and recorded their menstrual periods. A total of 36,786 samples were analyzed for follicle-stimulating hormone (FSH), luteinizing hormone, estrone 3-glucuronide, and pregnanediol 3-glucuronide. RESULTS: A classification of five sequential endocrine stages of reproductive aging was developed: stage 1, regular menstrual cycles with mean initial (day 1-5) FSH less than 5 IU/L; stage 2, regular cycles with FSH greater than 5 IU/L; stage 3, menstrual irregularity (with the appearance of "delayed-response cycles"); stage 4, acyclical ovarian activity with no evidence of ovulation and luteinization; and stage 5, ovarian quiescence and persistently raised gonadotropins. Distinct hormonal characteristics during the follicular and luteal phase were noted at each stage. CONCLUSION: This classification provides a detailed insight into the endocrinology of reproductive aging in women that could be useful for both clinical guidance and personal health care.

Adult↗

PubMed1975

Reproductive Growth and Dry Matter Production of Glycine max (L.) Merr. in Response to Oxygen Concentration.

Reproductive as well as vegetative parameters of mature soybean (Glycine max [L.] Merr. cv. Wye) plants grown in chambers in which the aerial portion was exposed to altered pO(2) during all or part of the growth cycle were measured. Oxygen concentration was found to be a key factor controlling all phases of reproductive development. Exposure to 5% O(2) from early seedling stage to senescence increased leaf, stem, and root dry weights and reduced seed yields when compared to 21% O(2); exposure to low O(2) during the vegetative growth stage from early seedling to mid-flowering arrested pod but not seed development; exposure from mid-flowering to mid-pod filling almost completely arrested seed but not pod development; exposure from mid-pod filling to senescence arrested seed development at the mid-filling stage.Exposures to 5% O(2) initiated at mid-flowering for 1, 2, 3, 5, 10, and 15 days had no effect on seed development when the exposure was up to 3 days and produced almost total arrest when the exposure was 10 or more days, suggesting reversibility. The requirement for O(2) in seed development is independent of CO(2) concentration with similar results produced by subambient O(2) combined with ambient CO(2), elevated CO(2) up to 2000 mul/l or depressed levels of CO(2) with the CO(2)/O(2) ratio as in air. An elevated O(2) atmosphere containing 40% O(2) and ambient or elevated CO(2) inhibited total growth but did not affect the balance of vegetative to reproductive growth.We conclude that an unknown reaction or process requiring at least atmospheric concentrations of O(2) but independent of CO(2) in contrast to photorespiration is necessary for optimization of all phases of reproductive growth and the effect is reversible for exposures of up to 3 days but not for exposures of 10 days or more. We propose that this O(2) phenomenon may be the result of a unique physical process or chemical reaction associated with translocation and accumulation of assimilates in reproductive structures.

Journal Article↗

PubMed1982

Sources, Fluxes, and Sinks of Nitrogen during Early Reproductive Growth of Maize (Zea mays L.).

A study was designed to (a) identify sources and sinks of N in the maize (Zea mays L.) shoot, by estimating net N fluxes for each of seven parts of the shoot, (b) determine effects of N entering the plant upon fluxes of N absorbed before reproductive growth, and (c) determine the effects of the opaque-2 gene on N fluxes in the maize shoot during early reproductive growth. Plants of a maize hybrid (Pioneer 3369A) and its opaque-2 counterpart (Pioneer L3369) were grown in a greenhouse using nutrient solution/sand culture, with NO(3) (-) as the N source during the vegetative growth phase. Beginning at the time of pollination, the same nutrient regime was continued, except that some plants received no N, and others received 3.75 millimolar (15)N as NO(3) (-)-N.Stalk and leaves were found to be primary N sources for the grain, while shank, husk, and cob acted first as N sinks, then as N sources during reproductive growth. Net fluxes of N for each plant part were estimated by calculating the first derivatives of regression equations used to fit data for N contents of each plant part as functions of time. All parts of the shoot were sinks for exogenous N (absorbed after pollination). Thirty-six days after pollination, the grain contained 60% endogenous N (absorbed before pollination) when 3.75 millimolar NO(3) (-)-N was supplied after pollination. Rates of total N influx to the grain were identical whether or not N was supplied in the nutrient solution during reproductive growth. At 36 days after pollination, less N had accumulated in the grain of the opaque-2 genotype, but otherwise there were no differences in N contents or dry weights of the shoots due to the opaque-2 gene. Absence of N from the rooting medium significantly affected N fluxes throughout the shoot during reproductive growth, but there were no detectable effects of the opaque-2 gene on N fluxes in parts of the plant other than the grain.

Journal Article↗

PubMed1991

Carbon Transfer and Partitioning between Vegetative and Reproductive Organs in Pisum sativum L.

Assimilate partitioning was studied in the common pea (Pisum sativum L.) by feeding (14)CO(2) to whole plants and measuring radioactivity in different organs 48 hours after labeling. Two experimental protocols were used. For the first, one reproductive node was darkened with an aluminum foil, to prevent photosynthesis during labeling. The aim was to study assimilate translocation among nodes. The second was carried out to assess any priority among sinks. Whole plants were shaded, during labeling, to reduce carbon assimilation. Various developmental stages between the onset of flowering and the final stage in seed abortion of the last pod were chosen for labeling. When all photosynthetic structures at the first reproductive node were darkened at any stage of development after the formation of the first flower, the first pod was supplied with assimilates from other nodes. In contrast, later developed pods, when photosynthetic structures at their node were darkened, received assimilates from other nodes only when they were beyond their final stage in seed abortion. Reducing illumination to 30% did not change distribution of assimilated carbon between vegetative and reproductive structures, nor among pods. It appears that the relative proportion of (14)C allocated to any one pod, compared to other pods, depends on the dry weight of that pod as a proportion of the total reproductive dry weight. When the plant was growing actively, following the start of the reproductive phase until a few days before the end of flowering, the top of the plant (i.e., all the organs above the last opened flower) had a higher sink strength and a higher relative specific activity than pods, suggesting that it was a more competitive sink for assimilates. The pattern of assimilate distribution described here provides an explanation for pod and seed abortion.

Journal Article↗

PubMed2001

A molecular phylogenetic analysis of reproductive trait evolution in the soft coral genus Alcyonium.

The soft coral genus Alcyonium is among the most reproductively diverse invertebrate taxa known: The genus includes species that vary both in mode of reproduction (including broadcast spawners, internal brooders, and external brooders) and sexual expression (gonochores, hermaphrodites, and a unisexual parthenogen). Such diversity offers a unique opportunity to examine associations between reproductive and morphological traits in a phylogenetic context. We used an approximately 900-bp sequence of the nuclear ribosomal gene complex spanning the internal transcribed spacer (ITS) regions to construct a molecular phylogeny for 14 European and North American species of Alcyonium onto which we mapped the known distribution of reproductive and morphological traits. The phylogeny suggests that hermaphroditism or parthenogenesis has evolved independently at least twice in this genus, and always in internally brooding species. Broadcast spawning and external brooding only occur in species with large colony size, whereas all species with small colony size brood their larvae internally. Internal brooding and small size appear to be ancestral in this genus; if this is the case, an association between broadcast spawning and large colony size has evolved independently in at least two clades. This tendency of small adults to brood their larvae while large adults broadcast spawn them into the plankton has been observed in a variety of solitary invertebrate taxa, but to date has not been documented in any other colonial invertebrates. Moreoever, it has been suggested that organisms with a colonial growth form should not experience the allometric constraints on brood space that have been proposed to explain the association between adult size and mode of reproduction in solitary organisms. Unlike many other colonial groups, however, module (polyp) size is strongly correlated with colony size in Alcyonium, and constraints on brooding may be imposed by module, rather than colony, allometry. The very close genetic relationship (< 1% sequence divergence) and shared polymorphisms among A. digitatum (a large, gonochoric broadcast spawner), A. siderium, and A. sp. A (intermediate-sized and small hermaphroditic, internal brooders) suggest that evolutionary transitions between broadcast spawning and brooding and between gonochorism and hermaphroditism can occur easily and rapidly in this group.

Adaptation, Physiological↗

PubMed2001

Cryptic reproductive isolation in the Drosophila simulans species complex.

Forms of reproductive isolation that act after copulation but before fertilization are potentially important components of speciation, but are studied only infrequently. We examined postmating, prezygotic reproductive isolation in three hybridizations within the Drosophila simulans species complex. We allowed females to mate only once, observed and timed all copulations, dissected a subset of the females to track the storage and retention of sperm, examined the number and hatchability of eggs laid after insemination, counted all progeny produced, and measured the longevity of mated females. Each of the three hybridizations is characterized by a different set of cryptic barriers to heterospecific fertilization. When D. simulans females mate with D. sechellia males, few heterospecific sperm are transferred, even during long copulations. In contrast, copulations of D. simulans females with D. mauritiana males are often too short to allow sperm transfer. Those that are long enough to allow insemination, however, involve the transfer of many sperm, but only a fraction of these heterospecific sperm are stored by females, who also lay fewer eggs than do D. simulans females mated with conspecific males. Finally, when D. mauritiana females mate with D. simulans males, sperm are transferred and stored in abundance, but are lost rapidly from the reproductive tract and are therefore used inefficiently. These results add considerably to the list of reproductive isolating mechanisms in this well-studied clade and possibly to the list of evolutionary processes that could contribute to their reproductive isolation.

Animals↗