Hyperhomocysteinemia, caused by a lack of cystathionine β synthase (CBS), leads to elevated plasma concentrations of homocysteine. This is a common risk factor for atherosclerosis, stroke, and possibly neurodegenerative diseases. However, the mechanisms that link hyperhomocysteinemia due to CBS deficiency to these diseases are still unknown. Early biochemical studies describe developmental and adult patterns of transsulfuration and CBS expression in a variety of species. However, there is incomplete knowledge about the regional and cellular expression pattern of CBS, notably in the brain. To complete the previous data, we used in situ hybridization and Northern blotting to characterize the spatial and temporal patterns of Cbs gene expression during mouse development. In the early stages of development, the Cbs gene was expressed only in the liver and in the skeletal, cardiac, and nervous systems. The expression declined in the nervous system in the late embryonic stages, whereas it increased in the brain after birth, peaking during cerebellar development. In the adult brain, expression was strongest in the Purkinje cell layer and in the hippocampus. Immunohistochemical analyses showed that the CBS protein was localized in most areas of the brain but predominantly in the cell bodies and neuronal processes of Purkinje cells and Ammon's horn neurons.

BACKGROUND An embryo's ability to grow and implant can be improved by selection of a normal spermatozoon with a vacuole-free head. However, large vacuoles in spermatozoa have yet to be fully characterized. The present study aimed to determine whether these vacuoles are of nuclear, membrane and/or acrosomal origin. METHODS We studied 15 infertile patients with differing sperm profiles. For each sperm sample, we used high-magnification (×10 000) contrast microscopy to select and assess 30 normal ‘top’ spermatozoa and 30 spermatozoa with a large sperm-head vacuole (≥ 25% of the head's cross-sectional area). We subsequently analysed the spermatozoa's degree of chromatin condensation (aniline blue staining), DNA fragmentation (terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labelling assay) and chromosome content (fluorescence in situ hybridization X,Y,18). Atomic force microscopy enabled us to map the plasma sperm membrane in detail. Three-dimensional deconvolution microscopy enabled us to reconstruct images of the nucleus and acrosome in ‘top’ and ‘vacuolated’ spermatozoa. RESULTS We studied a total of 450 ‘top’ spermatozoa and 450 vacuolated spermatozoa. The rate of non-condensed chromatin was higher for ‘vacuolated’ spermatozoa than for ‘top’ spermatozoa (36.2 ± 1.9 versus 7.6 ± 1.3%, respectively; P < 0.0001). ‘Top’ and ‘vacuolated’ spermatozoa did not differ significantly in terms of DNA fragmentation (0.7 ± 0.4 versus 1.3 ± 0.4% respectively; P = 0.25) or aneuploidy (1.1 ± 0.5 versus 2.2 ± 0.7% respectively; P = 0.21). The majority of aneuploid spermatozoa (9 out of 15) lacked chromatin condensation. In all vacuolated spermatozoa, the acrosome was intact, the plasma membrane was sunken but intact and the large vacuole was identified as an abnormal, ‘thumbprint’-like nuclear concavity covered by acrosomal and plasmic membranes. CONCLUSIONS The large vacuole appears to be a nuclear ‘thumbprint’ linked to failure of chromatin condensation.

Infertility concerns a minimum of 70 million couples worldwide. An important proportion of cases is believed to have a genetic component, yet few causal genes have been identified so far. In a previous study, we demonstrated that a homozygous mutation (c.144delC) in the Aurora Kinase C (AURKC) gene led to the production of large-headed polyploid multi-flagellar spermatozoa, a primary infertility phenotype mainly observed in North Africans. We now want to estimate the prevalence of the defect, to improve our understanding of AURKC physiopathology in spermatogenesis and assess its implication in oogenesis. A carrier frequency of 1/50 was established from individuals from the Maghrebian general population, comparable to that of Y-microdeletions, thus far the only known recurrent genetic event altering spermatogenesis. A total of 62 patients were genotyped, all who had a typical phenotype with close to 100% large-headed spermatozoa were homozygously mutated (n = 32), whereas no AURKC mutations were detected in the others. Two homozygous females were identified; both were fertile indicating that AURKC is not indispensible in oogenesis. Previous FISH results had showed a great chromosomal heterogeneity in these patient's spermatozoa. We demonstrate here by flow cytometry that all spermatozoa have in fact a homogeneous 4C DNA content and are thus all blocked before the first meiotic division. Our data thus indicate that a functional AURKC protein is necessary for male meiotic cytokinesis while its absence does not impair oogenesis.

It is well established that obesity is associated with dysregulation of the ratio between the two major adipokines leptin and adiponectin. Furthermore, it was recently reported that maternal obesity has a significant impact on placental development. Leptin and adiponectin are present at the fetal-maternal interface and are involved in the development of a functional placenta. However, less is known about leptin and adiponectin’s involvement in the placental alterations described in obese women. Hence, the objective of the present study was to characterize the placental expression and DNA methylation of these two adipokine systems (ligands and receptors) in obese women. Biopsies were collected from the fetal and maternal sides of third-trimester placenta in obese and non-obese (control) women. In both groups, leptin levels were higher on the fetal side than the maternal side, suggesting that this cytokine has a pivotal role in fetal growth. Secondly, maternal obesity (in the absence of gestational diabetes) was associated with (i) elevated DNA methylation of the leptin promoter on fetal side only, (ii) hypomethylation of the adiponectin promoter on the maternal side only, (iii) significantly low levels of leptin receptor protein (albeit in the absence of differences in mRNA levels and promoter DNA methylation), (iv) significantly low levels of adiponectin receptor 1 mRNA expression on the maternal side only, and (v) elevated DNA methylation of the adiponectin receptor 2 promoter on the maternal side only. Our present results showed that maternal obesity is associated with the downregulation of both leptin/adiponectin systems in term placenta, and thus a loss of the beneficial effects of these two adipokines on placental development. Maternal obesity was also associated with epigenetic changes in leptin and adiponectin systems; this highlighted the molecular mechanisms involved in the placenta’s adaptation to a harmful maternal environment.