Ovarian Arrest Research Articles

The Roles of transformer-2 (tra-2) in the Sex Determination and Fertility of Riptortus pedestris, a Hemimetabolous Agricultural Pest.

In most holometabolous insects, transformer-2 (tra-2) is an auxiliary gene required for sex determination, exerting a crucial role in regulating sexual differentiation; however, the study of tra-2 in hemimetabolous insects remains very sparse and limited to just a few species. In this study, we investigated the sequence and expression profile of the tra-2 gene in the bean bug, Riptortus pedestris, an agricultural pest belonging to the Heteroptera order. Three non-sex-specific splicing isoforms of Rptra-2 were found, Rptra-2293, Rptra-2284, and Rptra-2299, which shared most exons and exhibited similar expression throughout all stages of development, with particularly elevated levels in the embryo, ovary, and testis. RNAi knockdown experiments revealed that the suppression of Rptra-2 in nymphs led to abnormal females, characterized the formation of male-specific external genital, and also caused longer nymph duration. Knockdown of the expression of the Rptra-2 gene in newly emergent virgin females would cause ovarian arrest, and injecting the 8th-day virgin females with dsRptra-2 also caused a noticeable decline in the offspring numbers. Conversely, in dsRptra-2-treated males, the testes maintained normal morphology but experienced impaired reproductive capacity, attributed to diminished sperm viability. These findings highlight the crucial role of Rptra-2 in the sex determination and fertility of R. pedestris, providing valuable insights into the sex determination mechanisms of hemimetabolous insects.

Comparison of overwintering survival and fertility of Zaprionus indianus (Diptera: Drosophilidae) flies from native and invaded ranges.

Zaprionus indianus is a fly species native to the Afrotropical biogeographic region that invaded the South American continent 20 years ago. Its southernmost record is 34°S in areas with temperate climates with cold winters. To better understand its invasion biology, we investigated physiological responses to winter-like abiotic conditions that may be relevant in Z. indianus geographic expansion. We characterized Z. indianus females reproductive traits (ovarian maturation and fertility) and survival in response to cold treatments with summer-like and winter-like photoperiods. We also compared these traits between native (Yokadouma, Africa) and invasive (Yuto, South America) range wild-derived flies. We showed that Z. indianus females have the ability to arrest ovarian maturation and maintain fertility following recovery from cold stress. The critical temperature for ovarian maturation of this species was estimated at c. 13°C, an intermediate value between those of tropical and temperate drosophilid species. Wild-derived females from Yuto responded to winter-like photoperiod by slowing down ovarian maturation at low but permissive temperatures of 14°C and 16°C and also delayed the start of oviposition after cold treatment. Yuto flies also survived better and recovered 20% faster from chill coma than flies from Yokadouma. These results are consistent with a scenario of local adaptations or phenotypic plasticity in the invaded range, and suggest that photoperiod could act as modulator of ovarian arrest. Conversely, the fact that native range flies showed higher fertility after cold recovery than females from invaded range is not indicative of local adaptation. All in all, our findings report a set of physiological responses that would enable Z. indianus expansion to temperate and cold areas, but also results that are compatible with a limitation to the invasion process.

Tight interplay in early pregnancy between follistatin and anti-mullerian hormone in women with polycystic ovarian syndrome (PCOS).

Follistatin levels increase during the course of pregnancy and may play a role in ovarian arrest, reflected by the simultaneous decrease of anti-mullerian-hormone (AMH) levels. The aim of the study was to investigate AMH and follistatin levels during the hormonal window at the beginning ofpregnancy. Since both parameters are described as deregulated in polycystic ovarian syndrome (PCOS), subgroup analysis of PCOS patients may additionally elucidate their interplay and effects on ovarian activity. Serum samples were retrospectively analyzed using the AMH Gen II ELISA and the Human Follistatin Quantikine ELISA Kit. Samples were collected longitudinally from 57 patients (32 with PCOS and 25 controls) before conception and during the first trimester. In 18 patients, measurements from the early and the late first trimester were available. Potential associations of AMH and follistatin levels with PCOS-related parameters were compared between the subgroups as well as longitudinally before and in the first trimester of pregnancy. For statistical analysis, the Spearman's correlation, Wilcoxon test, t test, Friedman test and multiple linear regression analysis was performed. In contrast to AMH, follistatin levels differed not between controls and PCOS patients before and in pregnancy. In both subgroups, AMH levels significantly decreased and follistatin levels significantly increased in longitudinally performed measurements before conceiving and in the first trimester of pregnancy. Follistatin levels are not suited as a biomarker for PCOS, but could be involved in suppressing ovarian activity, as reflected by AMH levels at the beginning of pregnancy.

Follistatin during pregnancy and its potential role as an ovarian suppressing agent

ObjectiveOvarian quiescence is a common condition during pregnancy. In vitro, follistatin, an antagonist of follicle-stimulating hormone, blocks follicular development at early stages, and its serum levels increase during pregnancy. A possible surrogate biomarker of ovarian arrest during pregnancy is a decrease in anti-mullerian hormone (AMH) levels followed by an increase in these levels on the second day after labor. The purpose of this study was to determine whether follistatin could act as an ovarian-suppressing agent during pregnancy. Follistatin levels and AMH levels were determined at various stages of pregnancy and postpartum. Study designThe follistatin and AMH levels of 69 patients were retrospectively determined with the AMH Gen II ELISA and with the Human Follistatin Quantikine ELISA Kit. For 49 patients, samples were available from various trimesters for cross-sectional analysis; for the other 20, samples were available longitudinally from day one before labor and then daily on days 1 through 4 after labor. Statistical significance was determined with linear regression, the Friedman rank sum test and the Wilcoxon–Nemenyi–McDonald–Thompson post hoc test. ResultsThe behavior of follistatin levels was exactly opposite that of AMH levels: Follistatin levels increased significantly during pregnancy and on the first day after parturition but declined afterwards, whereas AMH levels decreased significantly during pregnancy and increased after labor. ConclusionFollistatin can induce ovarian arrest during pregnancy.

The Insulin-Like Proteins dILPs-2/5 Determine Diapause Inducibility in Drosophila.

Diapause is an actively induced dormancy that has evolved in Metazoa to resist environmental stresses. In temperate regions, many diapausing insects overwinter at low temperatures by blocking embryonic, larval or adult development. Despite its Afro-tropical origin, Drosophila melanogaster migrated to temperate regions of Asia and Europe where females overwinter as adults by arresting gonadal development (reproductive diapause) at temperatures <13°C. Recent work in D. melanogaster has implicated the developmental hormones dILPs-2 and/or dILP3, and dILP5, homologues of vertebrate insulin/insulin-like growth factors (IGFs), in reproductive arrest. However, polymorphisms in timeless (tim) and couch potato (cpo) dramatically affect diapause inducibility and these dILP experiments could not exclude this common genetic variation contributing to the diapause phenotype. Here, we apply an extensive genetic dissection of the insulin signaling pathway which allows us to see both enhancements and reductions in egg development that are independent of tim and cpo variations. We show that a number of manipulations dramatically enhance diapause to ~100%. These include ablating, or reducing the excitability of the insulin-producing cells (IPCs) that express dILPs-2,3,5 employing the dilp2,3,5-/- triple mutant, desensitizing insulin signaling using a chico mutation, or inhibiting dILP2 and 5 in the hemolymph by over-expressing Imaginal Morphogenesis Protein-Late 2 (Imp-L2). In addition, triple mutant dilp2,3,5-/- females maintain high levels of diapause even when temperatures are raised in adulthood to 19°C. However at 22°C, these females all show egg development revealing that the effects are conditional on temperature and not a general female sterility. In contrast, over-expression of dilps-2/5 or enhancing IPC excitability, led to levels of ovarian arrest that approached zero, underscoring dILPs-2 and 5 as key antagonists of diapause.

Factors terminating ovarian arrest in long-winged females of a flightless bug, Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae)

The aim of the present study was to determine the factors that are involved in termination of a non-diapause type of ovarian arrest in the adult macropterous females of a flightless bug, Pyrrhocoris apterus (L.), reared under a long-day (18L : 6D) photoperiod. Application of an active analogue of juvenile hormone, methoprene, to adult macropterous females kept under the above conditions induced precocious termination of ovarian arrest and shortened the length of the pre-oviposition period. The results indicate that a temporary ovarian arrest in spontaneously fasting long-day macropterous females results from a deficiency of juvenile hormone. The length of the pre-oviposition period was shortened and ovarian arrest terminated also by de-alation, high temperature and by a prolonged period of starvation. Mating of long-day macropterous females with reproductively active males had no effect on the length of the pre-oviposition period. There was a relationship between the length of the starvation period and the post-feeding pre-oviposition period. The longer the starvation period, the shorter the period from when food was supplied to first oviposition. The results indicate that depletion of the fat body reserves resulting from prolonged fasting, followed by resumption of food intake are pre-requisites for full activation of the corpus allatum and egg development, and play a role in completion and termination of non-diapause ovarian arrest in long-day macropterous females. This phenomenon was never observed in short-day brachypterous females in reproductive diapause.

Overlapping Distribution of Two Groups of the Butterfly Eurema hecabe Differing in the Expression of Seasonal Morphs on Okinawa-jima Island

In Japan, Eurema hecabe (L.) has two geographically separated groups (subtropical and temperate) differing not only in the color pattern expression of the wings associated with ovarian arrest, but also in the fringe color of the wings and host-plant utilization. In a field survey (Kato, 1999), it was found that individuals with different fringe color of the forewing (brown or yellow type) inhabit Okinawa-jima Island located in north of the subtropical region, and that fringe-color is linked with seasonal morph expression. In the present study, rearing experiments were done to investigate whether these sympatric individuals are different forms within one species or belong to different species. The results show that each population of brown- and yellow-types maintained its own seasonal morph response to photoperiod and temperature through three generations. Host-plant utilization by the larvae and the fringe-color also differed between them and was maintained. These findings strongly suggest that E. hecabe of Okinawa-jima Island is divided into two distinct populations, and that one belongs to the temperate and the other to the subtropical group.

Allatostatin-like peptide in the brain-retrocerebral complex of the earwig Labidura riparia: cyclic variations related to the reproductive cycle

Summary A polyclonal antibody raised against allatostatin-3 of Blattella germanica (BLAST-3) has been used to immunolocalize allatostatin-like peptides in the brain-retrocerebral complex of Labidura riparia adult females. Strongly stained immunoreactive cells are observed in the pars intercerebralis (14 cells) and mainly in the pars lateralis (32 cells). Fibres leading to the corpus allatum are also stained. In the deutocerebrum, one cell is immunostained at the root of each antennal nerve. In the tritocerebmm two cells in each brain hemisphere are weakly immunostained. During the reproductive cycle, these cells and their axons show immunoreactivity at previtellogenic, ovulation and ovarian arrest periods. During vitellogenesis, immunoreactivity is restricted to only four perikarya in the pars intercerebralis. When young vitellogenic females are injected with 20-hydroxyecdysone (20E), which inhibits vitellogenesis, full immunoreactivity reappears, suggesting sensibility of these cells to 20E as is expected for a negative feed-back loop (Sayah et al., 1995). These results show that BLAST-3-like material is produced periodically in Labidura in correlation with low levels of juvenile hormone and the absence of vitellogenesis. This study contributes to provide information on the degree of homology of allatostatins across various insects.

Sequential danazol/leuprolide acetate therapy for ovarian suppression in an in vitro fertilization patient unresponsive to leuprolide acetate

We report a case of pituitary-ovarian suppression obtained with sequential danazol/leuprolide acetate administration in a patient undergoing in vitro fertilization and unresponsive to leuprolide acetate alone and sequential oral contraceptive-leuprolide acetate therapy. Leuprolide acetate (1 mg daily subcutaneously) was administered after 5 weeks of danazol treatment (800 mg daily) while the latter was maintained for 1 additional week. Ovarian activity was assessed by transvaginal ultrasonography and serum estradiol determination. After 5 weeks of danazol therapy, ovarian arrest was obtained despite the fact that gonadotropin serum levels did not change relative to basal values. Leuprolide acetate injection for 14 days was associated with a decrease in serum concentrations of follicle-stimulating hormone and luteinizing hormone and a further decrease of the estradiol level. We conclude that sequential danazol/leuprolide acetate therapy is a useful alternative for obtaining ovarian arrest in patients unresponsive to leuprolide acetate alone.

The comparison of two gonadotropin-releasing hormone agonists in an in vitro fertilization program

To compare two gonadotropin-releasing hormone agonists (GnRH-a), buserelin acetate and leuprolide acetate [LA], used in combination with gonadotropins in ovarian stimulation for in vitro fertilization (IVF). Randomized prospective study. Assisted Reproduction Unit of the Hospital Clínic i Provincial in Barcelona. Thirty-five pairs of IVF patients who were matched on age, indication, and number of attempts. These women were randomized to receive either buserelin acetate plus gonadotropins (group B) or LA plus gonadotropins (group L). Luteolysis, ovarian response, and IVF outcome. The mean time for total ovarian arrest and the total dose of gonadotropins and estradiol levels on the day of human chorionic gonadotropin administration were similar in the two groups of patients. The number of follicles punctured, the number of oocytes retrieved, and the percentage of mature oocytes in group L were significantly higher. The number of embryos suitable for replacement and cryopreservation was higher in group L compared with group B approaching statistical significance. Our results warrant further studies to compare different GnRH-a as therapeutic tools in IVF.

Ovarian response and outcome of in-vitro fertilization in patients treated with gonadotrophin-releasing hormone analogues in different phases of the menstrual cycle

Gonadotrophin-releasing hormone analogues (GnRH-a) are currently used in combination with gonadotrophins in ovarian stimulation for in-vitro fertilization (IVF). The present study evaluates follicular recruitment and outcome of IVF in patients treated with GnRH-a, starting in different phases of the menstrual cycle. Ovarian quiescence was achieved by s.c. injection of a GnRH-a (600 micrograms/day). Three groups of patients were randomly established. Patients in group 1 (n = 14) started GnRH-a treatment 4-7 days after ovulation. Women in group 2 (n = 15) started GnRH-a 8-10 days after ovulation. Patients in group 3 (n = 15) began the analogue 1-3 days after the onset of menses. Multiple follicular development was achieved by a combination of pure follicle-stimulating hormone and human menopausal gonadotrophin. Oocyte collection was performed 35 h after administration of human chorionic gonadotrophin. Luteolysis was successfully induced in 15% of cases in group 1 and 40% in group 2. Ovarian arrest was achieved in a significantly (P less than 0.01) shorter period of time in group 3 in comparison to groups 1 and 2. There was no difference between groups in the dose of gonadotrophins necessary to reach an optimal response. Patients in group 1 showed a significant decrease (P less than 0.05) in the number and size of follicles developed in comparison to groups 2 and 3. Fertilization and cleavage rates were similar in all three groups. The pregnancy rate was 40% in group 3, while it decreased to 14.3 and 13.3% in groups 1 and 2, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Life History Variability in the Water Boatman, Trichocorixa reticulata (Hemiptera: Corixidae), in San Francisco Bay Salt Marsh Ponds

Age structure, ovarian development, and oviposition rates of Trichocorixa reticulata Guerin-Meneville in Petaluma Marsh, San Francisco Bay, Calif., were examined over 2 years in six saline ponds that ranged in hydrological stability from temporary to permanent. In permanent and semi-permanent ponds, the population completes a spring and summer generation. After a late summer ovarian arrest, about half the summer generation adults reproduce and give rise to an autumn generation, while the remaining half overwinter as reproductively immature adults. Synchronous oviposition by these two cohorts during the spring produces a generation with a single well-defined peak, whereas asynchronous oviposition produces a generation with two staggered peaks. Because temporary ponds completely dry up many times during the dry season, neither a spring nor a summer generation can be completed. Variable recruitment of nymphs on inundating tides and of adults by flight into the temporary ponds produced erratic age structure patterns. Although the age structure patterns for T. reticulata in Petaluma Marsh vary among ponds, they appear in general to share characteristics of those reported for tropical corixids (i.e., year-round reproduction) and those reported for temperate corixids (i.e., overwintering spent only in the adult stage).