Kinetic constanis of asialoorosomucoid endocytosis comparison between hepatocytes from normal and streptozotocin-diabetic rats

The initial velocity of asialoorosomucoid internalization is determined for normal and diabetic rat hepatocytes. The analysis of results according to Woolf-Hofstee's method, showed no modification of the endocytosis constant. In contrast, the maximum velocity of asialoorosomucoid internalization is decreased by threefold in diabetic rat hepatocytes as compared to normal rat hepatocytes. No modification of internalization constant is observed between the two groups of rats. This suggests that the decrease of asialoorosomucoid total uptake, previously reported for diabetic rat hepatocytes is directly related to a decrease of total surface receptor number.     

Effect of phosphate and ionophores on (14C)-NEM incorporation in mitochondrial membranes and relationships with phosphate carrier system.

Phosphate transport in mitochondria was investigated with respect to its inhibition by NEM. The reactivity of the Pi carrier SH groups was influenced by phosphate or ionophores during preincubation before the addition of NEM. Furthermore in order to obtain some mitochondrial protein fractions where the typical effects of phosphate and ionophores on [14C]-NEM fixations were observed, mitochondria were submitted to hypotonic treatment and sonication. The following results were obtained: 1. -- Phosphate and grisorixin (a new ionophore of the nigericin group) decreased the inhibition of phosphate transport by NEM. The same effect was observed for [14C]-NEM incorporation. 2. -- Valinomycin increased [14C]-NEM incorporation. The valinomycin effect was abolished by phosphate. ClCCP alone affected [14C]-NEM incorporation slightly. Valinomycin plus ClCCP decreased NEM inhibition of phosphate transport and [14C]-NEM incorporation like grisorixin. 3. -- The variability of SH group reactivity can be interpreted by a control of SH group accessibility by transmembrane delta pH as previously suggested. 4. -- Typical effects of phosphate or ionophores were observed in whole pig heart and rat liver mitochondria. These effects were enhanced in the same supernatant protein fraction resulting from sonication in pig heart mitochondria : phosphate decreased [14C]-NEM incorporation by 1,50 nmoles/mg protein, grisorixin by 0.95 nmoles, whereas valinomycin increased it by 0.75 nmoles. For rat liver mitochondria the phosphate effect and the valinomycin increased it by 0.75 nmoles. For rat liver mitochondria the phosphate effect valinomycin effect on [14C]-NEM incorporation were observed in the subparticular fraction obtained after sonification.     

Identification of Small Exonic CNV from Whole-Exome Sequence Data and Application to Autism Spectrum Disorder

Copy number variation (CNV) is an important determinant of human diversity and plays important roles in susceptibility to disease. Most studies of CNV carried out to date have made use of chromosome microarray and have had a lower size limit for detection of about 30 kilobases (kb). With the emergence of whole-exome sequencing studies, we asked whether such data could be used to reliably call rare exonic CNV in the size range of 1–30 kilobases (kb), making use of the eXome Hidden Markov Model (XHMM) program. By using both transmission information and validation by molecular methods, we confirmed that small CNV encompassing as few as three exons can be reliably called from whole-exome data. We applied this approach to an autism case-control sample (n = 811, mean per-target read depth = 161) and observed a significant increase in the burden of rare (MAF ≤1%) 1–30 kb CNV, 1–30 kb deletions, and 1–10 kb deletions in ASD. CNV in the 1–30 kb range frequently hit just a single gene, and we were therefore able to carry out enrichment and pathway analyses, where we observed enrichment for disruption of genes in cytoskeletal and autophagy pathways in ASD. In summary, our results showed that XHMM provided an effective means to assess small exonic CNV from whole-exome data, indicated that rare 1–30 kb exonic deletions could contribute to risk in up to 7% of individuals with ASD, and implicated a candidate pathway in developmental delay syndromes.