Fertilité et aneuploïdies spermatiques après traitement par radiothérapie et/ou chimiothérapie pour cancer du testicule ou lymphome

Improvements in cancer therapy have considerably modified patient survival rates over recent years. However, the side effects of these treatments especially the effects on fertility, must be taken into account. Anticancer therapy can transiently inhibit spermatogenesis. Factors such as pretreatment semen parameters and the type of chemotherapy or radiotherapy may influence recovery of spermatogenesis, but it is still impossible to predict the probability of and time to recovery for each patient. Sperm banking remains the only way to prevent the effects of cancer treatment on male fertility. Another possible effect of chemotherapy or radiotherapy is genetic damage to germ cells. For instance, chromosomal abnormalities in viable sperm produced by these patients after recovery of spermatogenesis may result in fetal death or congenital abnormalities in their offspring. It has been fairly well documented that, during the first three months after treatment, DNA breaks and abnormal chromosomal segregation induced by chemotherapy/radiotherapy lead to structural and numerical chromosomal abnormalities in spermatozoa, respectively. However, the long-term effects on genetic sperm content have not been clearly established. The results of published studies are contradictory and are based on limited numbers of patients (maximum of 6). We present the preliminary results of a retrospective study concerning patients treated for testicular cancer or lymphoma between 1995 and 2000. Fluorescence in situ hybridization (FISH) analysis of chromosomes X, Y and 18 was performed on sperm collected one to five years after treatment and compared to the data obtained for non-affected fertile men. For four out of 13 patients, we found a significantly increased frequency of aneuploidy rates (mainly XY disomy and diploidy), and these results did not appear to be correlated with sperm count, sperm morphology or post-treatment duration. In conclusion, increased sperm aneuploidy rates appear to only concern a small number of patients, to varying degrees and without any predictive factors. According to published data and our preliminary results, we recommend waiting at least two years before starting ART (Assisted Reproduction Therapy) for patients treated for testicular cancer or lymphoma. Moreover, FISH analysis could be helpful to choose between ART with post-treatment sperm or cryopreserved sperm.     

Sex‐dependent Associations of Leptin With Metabolic Syndrome–related Variables: The Stanislas Study

Serum leptin has been reported to be associated in a sex‐dependent manner with C‐reactive protein (CRP), independently of adiposity. We tested the hypothesis that leptin is associated, independently of anthropometry indexes and in a sex‐dependent way, with other inflammatory markers and variables related to metabolic syndrome (MS). In 384 healthy middle‐aged adults (192 men and 192 women) total fat mass (FM), waist circumference (WC), serum leptin and 15 MS‐related parameters (systolic and diastolic blood pressure, triglycerides, cholesterol, high density lipoprotein (HDL)‐cholesterol, apo AI and B, fasting glucose, uric acid, CRP, orosomucoid and haptoglobin levels and aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT) and γ‐glutamyl transferase (GGT) activities) were measured. After adjustment for age, alcohol and cigarette consumption, WC, and total FM, leptin concentration was significantly associated with serum triglycerides, total cholesterol, apo B, uric acid and haptoglobin concentrations and liver enzyme activity only in men, and with apo AI, HDL‐cholesterol (only borderline) and CRP only in women. Sex interaction terms were significant for total cholesterol, apo B, HDL cholesterol, uric acid, ALAT and GGT, and borderline significant for triglycerides, apo AI and ASAT. In this healthy population, leptin is significantly associated with various MS factors, independently of WC and total FM, depending on gender. Our study provides further evidence of sex‐related differences mediated by leptin in inflammatory mechanisms and other MS‐related metabolic pathways.     

Immuno-cytochemical localization of indole-3-acetic acid during induction of somatic embryogenesis in cultured sunflower embryos

Immature zygotic embryos of sunflower (Helianthus annuus L.) produce somatic embryos when cultured on medium supplemented with a cytokinin as the sole source of exogenous growth regulators. The timing of the induction phase and subsequent morphogenic events have been well characterized in previous work. We address here the question of the role of endogenous indole-3-acetic acid (IAA), since auxins are known to have a crucial role in the induction of somatic embryogenesis in many other culture and regeneration systems. The fact that in the sunflower system no exogenous auxin is required for the induction of somatic embryos makes this system very suitable for the study of the internal dynamics of IAA. We used an immuno-cytochemical approach to visualize IAA distribution within the explants before, during and after the induction phase. IAA accumulated transiently throughout cultured embryos during the induction phase. The detected signal was not uniform but certain tissues, such as the root cap and the root meristem, accumulated IAA in a more pronounced manner. IAA accumulation was not restricted to the reactive zone but the kinetics of endogenous variations strikingly mimic the pulse of IAA that is usually provoked by exogenous IAA application. The direct evidence presented here indicates that an endogenous auxin pulse is indeed among the first signals leading to the induction of somatic embryogenesis.     

Male meiotic segregation of gonosomes analysed by two colour FISH in human interphase spermatozoa

Human meiotic segregation of X and Y chromosomes was simultaneously analysed by dual fluorescence in situ hybridization (FISH) on 10638 interphase spermatozoa from the same donor. A modified method for sperm decondensation ensured access of both X and Y probes to the sperm chromatin and a 99% hybridization efficiency. Expected sex ratios were obtained (49.30% haploidy X and 49.22% haploidy Y). The frequencies of meiotic II non-disjunctions for X and Y chromosomes (0.05%) were similar to those observed in sperm karyotypes after heterospecific fertilization of hamster eggs. In contrast, the frequency of XY bearing cells was significantly higher (0.42%). However, XY cells detected by FISH could either be diploid somatic cells, diploid germinal cells or hyperhaploid XY spermatozoa, the latter resulting from meiotic I non-disjunctions.     

Somatic embryogenesis and organogenesis induced on the immature zygotic embryo of sunflower (Helianthus annum L.) cultivated in vitro: role of the sugar

Summary Immature zygotic embryos of sunflower constitute an experimental system where the change of a single key factor (sucrose concentration) conditions the in vitro morphogenesis to either organogenesis (87 mM sucrose) or somatic embryogenesis (350 mM sucrose). Experiments with a variety of culture media differing in the sugar type and concentration, as well as osmotic pressure, indicate that a minimal threshold level of both, sugar supply and osmotic pressure, are required for somatic embryogenesis, but not organogenesis, to occur. The nature of the sugar used, though, was less important.Abbreviations IZE immature zygotic embryo     

Agrobacterium-mediated transformation of sunflower (Helianthus annuus L.) shoot apices: transformation patterns

Apical segments of embryonic axes of sunflower (Helianthus annuus L.) embryos were submitted to co-culture experiments with a disarmed strain of Agrobacterium tumefaciens, harbouring a plasmid coding for the marker enzyme -glucuronidase. The expression patterns of this marker were analysed at different developmental stages of the regenerated shoots. The results are consistent with the hypothesis that transformed shoots originate from transformation events that have occurred within the existing meristems. Two of the resulting chimaeric plants have been analysed in detail, and some representative gene integration patterns are presented.