The Drosophila ovarian tumor gene is required for the organization of actin filaments during multiple stages in oogenesis

The ovarian tumor gene is required during both early and late stages of oogenesis. Mutations produce a range of phenotypes, including agametic ovarioles, tumorous egg chambers, and late stage oogenic arrest. We demonstrate that each of these phenotypes is associated with specific aberrations in actin distribution. In the earliest case, ovarian tumor mutations cause actin filaments to accumulate ectopically in the fusome. This correlates with abnormal fusome morphology and arrested germ cell development in the germaria. Similarly, ovarian tumor function is required for the localization of actin that is essential for the maturation of ring canals. This defect gives rise to tumorous egg chambers in which germ cell numbers and morphology are profoundly aberrant. We also confirm that ovarian tumor is required for the formation of the nurse cell cytoplasmic actin array that is essential for the nonspecific transport of cytoplasmic contents to the oocyte during late oogenesis. Our data suggest that at this stage ovarian tumor controls the site where actin filaments initiate. Taken together, these studies suggest that the diverse ovarian tumor mutant phenotypes derive from the mislocalization of actin filaments, indicating a role for this gene in organizing the female germline cytoskeleton, and that the misregulation of actin can have profound effects on germ cell division and differentiation.

[Oocyte donation: ethical aspects related to the donor]

This paper analyses the reasons that brings couples to apprehend very differently the oocyte and sperm donation and highlights the difficulty of donor recruitment in those programs. The various types of donors (occasional, relational, IVF patient and professional) are described with their motivations, resistances, advantages and disadvantages. The contradictory consequences between free or paid donation, the particular risks of eggs donation (in comparison to sperm donation) for the donor as for the recipient are also highlighted. The problem of anonymity is also analysed in ethical terms but also in terms of technical efficacy: it is shown that anonymity, by authorizing sharing oocytes between recipients increases treatment efficacy by avoiding wasting this rare and precious resource of oocytes offered as a donation.

Oocyte shortage for donation may be overcome in a programme with anonymous permutation of related donors

Difficulty in recruiting donors plays a crucial role in oocyte donation programmes. We report here an original strategy to overcome this problem, consisting of sharing out anonymous oocytes between recipients, which has markedly improved treatment efficiency by avoiding freezing or destruction of supernumerary embryos. Each patient received part of the supply of oocytes from several donors in four successive cycles, while each donor underwent oocyte retrieval only once. This strategy led to one pregnancy per treated donor, increased treatment efficacy by 300%, and reduced dramatically the oocyte shortage at our centre. The system avoids wastage of the rare and precious donated oocytes, increases the chance of pregnancy for each related recipient and even permits the inclusion of some recipients without related donors.

[Update on ovarian hyperstimulation syndrome]

The ovarian hyperstimulation syndrome (OHSS) is the most important complication of the pharmacological ovulation induction. Exclusively postovulatory, it is clinically characterized by a massive ovarian enlargement associated with an acute third-space fluid shift responsible for the development of ascites, and sometimes pleural and/or pericardial effusion. While mild OHSS has no consequence, severe forms can be life-threatening because of associated hemodynamic troubles. The main risk factors are the polycystic ovarian syndrome and an explosive ovarian response to the stimulation characterized by high serum oestradiol levels and an increased number of follicles. Ultrasound and endocrine monitoring make prevention measures possible, mainly by either abandoning the stimulation cycle or, during in vitro fertilization, cryopreserving the embryos for subsequent replacement in another cycle. Treatment consists in correcting circulatory and electrolyte imbalance. Paracentesis is more and more systematically proposed in the severe forms.

Developmental analysis of the ovarian tumor gene during Drosophila oogenesis

Severe alleles of the ovarian tumor (otu) and ovo genes result in female sterility in Drosophila melanogaster, producing adult ovaries that completely lack egg chambers. We examined the developmental stage in which the agametic phenotype first becomes apparent. Germ cell development in embryos was studied using a strategy that allowed simultaneous labeling of pole cells with the determination of embryonic genotype. We found that ovo- or otu- XX embryonic germ cells were indistinguishable in number and morphology from those present in wild-type siblings. The effects of the mutations were not consistently manifested in the female germline until pupariation, and there was no evidence that either gene was required for germ cell viability at earlier stages of development. The requirement for otu function in the pupal and adult ovary is supported by temperature-shift experiments using a heat-inducible otu gene construct. We demonstrate that otu activity limited to prepupal stages was not sufficient to support oogenesis, while induction during the pupal and adult periods caused suppression of the otu mutant phenotype.

The ovarian hyperstimulation syndrome in in-vitro fertilization: a Belgian multicentric study. II. Multiple discriminant analysis for risk prediction

The considerable overlap of distributions of values for different parameters between control and ovarian hyperstimulation syndrome (OHSS) populations makes any single variable inefficient for risk prediction. Combinations of variables were studied in a discriminant function in order to increase predictivity and decrease the false negative rate. Such analyses were performed on two groups of in-vitro fertilization (IVF) patients: all OHSS cases (n = 128) (group A) and only severe OHSS cases (n = 92) (group B). Progressive introduction and automated stepwise selection of variables were applied to both groups. The best prediction (78.5%) was obtained in group A under post-oocyte retrieval conditions using log oestradiol, slope of log oestradiol increment, human menopausal gonadotrophin (HMG) dosage, number of oocytes retrieved and ratio of luteinizing hormone/follicle stimulating hormone (LH/FSH), in the formula. The corresponding false negative rate was 18.1%. However, effective prevention of OHSS implies the ability to withhold human chorionic gonadotrophin injection. Therefore a formula for pre-oocyte retrieval conditions was established yielding a prediction rate of 76.1% with a false negative rate of 18.1%. To be validated, such formulae have to be applied to another population of IVF cases used as a 'testing-set'.

Abnormal sperm-mucus penetration test predicts low in vitro fertilization ability of apparently normal semen

OBJECTIVE

To investigate whether Kremer's sperm-mucus penetration test may predict sperm fertilizing ability in IVF.

DESIGN

Kremer's test was prospectively performed on semen samples used for 66 consecutive IVF trials and compared with the fertilization rates and fertilization failure rates observed.

RESULTS

Fertilization rates were significantly reduced in cases of abnormal Kremer's test (42% versus 51%; n = 745 oocytes with a statistically insignificant increase in fertilization failure rates (21% versus 10%; n = 66 trials). For abnormal semen, fertilization rates (39% versus 39%; n = 208 oocytes) and fertilization failure rates (20% versus 28%; n = 17 trials) were similar regardless of Kremer's test result. For normal semen, an abnormal Kremer's test implied a significant decrease in fertilization rates (44% versus 54%; n = 537 oocytes) with a statistically insignificant increase in fertilization failure rates (21% versus 6%; n = 49 trials).

CONCLUSIONS

Abnormal Kremer's test results identify patients with a decreased in vitro fertilizing ability despite apparently normal semen samples and a group with very low fertilizing failure risk in case of normal semen samples and normal Kremer's test. Kremer's test does not add any predictive value to sperm analysis in the case of abnormal semen samples. These observations point out the importance of the male factor in fertilization failure even in the case of normal semen analysis.

Genetic and molecular characterization of P element-induced mutations reveals that the Drosophila ovarian tumor gene has maternal activity and a variable null phenotype

The mutations in the ovarian tumor (otu) gene arrest oogenesis at several stages in development. A series of deletion mutations in the otu region were characterized, each of which causes the absence or reduction of the otu transcript. These alleles range from the most severe class, which results in ovaries lacking egg cysts, to relatively mild mutations that allow the development of late stage oocytes. Heteroallelic combinations of these mutations demonstrate that the phenotypic complexity of otu mutant ovaries is due to a dosage dependent requirement for otu activity. Reciprocal cross and developmental Northern blot studies suggest a maternal requirement for otu in the development of the female germline. In addition we demonstrate that the otu zygotic null phenotype is variable, ranging from the absence of cysts in the most extreme cases, to the presence of tumorous egg chambers.

Comparative auto-controlled study between swim-up and Percoll preparation of fresh semen samples for in-vitro fertilization

This study compared swim-up and Percoll preparation of fresh semen samples for in-vitro fertilization. Sixty trials of in-vitro fertilization (IVF), 38 with normal semen and 22 with abnormal semen, comprising 734 oocytes were included in the study. Each semen sample was prepared by both a swim-up technique and a simplified discontinuous (50%, 70%, 90%) Percoll gradient. The oocytes for each trial were distributed at random between the two sperm preparations and incubated with the same number of motile spermatozoa. Percoll gradient preparation produced a significantly higher final concentration of spermatozoa than swim-up preparation (mean +/- SEM: 6.6 +/- 1.5 x 10(6)/ml versus 1.9 +/- 0.2 x 10(6)/ml; P less than 0.01) but a significantly lower sperm motility (69 +/- 2% versus 94 +/- 1%; P less than 0.001) and a lower number of normal forms (55 +/- 2% versus 64 +/- 2%; P less than 0.01). The ability of the Percoll gradient method to extract motile spermatozoa was higher than that of the swim-up technique (20 +/- 15.6% versus 0.8 +/- 13.6%). Nevertheless, the rates of fertilization (61%), fertilization failure (18%) and polyspermia (9%), embryo quality evaluated by mean embryo scores (3.8 +/- 0.3) and the mean number of spare embryos frozen per trial (1.4 +/- 0.3) were strictly identical in both groups. The 24 pregnancies (including three from frozen--thawed embryos) obtained in these 60 trials (40% per oocyte retrieval) could not be separated according to the sperm preparation method, as embryos from both groups were replaced together.(ABSTRACT TRUNCATED AT 250 WORDS)