Frequency of holoprosencephaly in the International Clearinghouse Birth Defects Surveillance Systems: searching for population variations

BACKGROUND: Holoprosencephaly (HPE) is a developmental field defect of the brain that results in incomplete separation of the cerebral hemispheres that includes less severe phenotypes, such as arhinencephaly and single median maxillary central incisor. Information on the epidemiology of HPE is limited, both because few population‐based studies have been reported, and because small studies must observe a greater number of years in order to accumulate sufficient numbers of births for a reliable estimate. METHODS: We collected data from 2000 through 2004 from 24 of the 46 Birth Defects Registry Members of the International Clearinghouse for Birth Defects Surveillance and Research. This study is based on more than 7 million births in various areas from North and South America, Europe, and Australia. RESULTS: A total of 963 HPE cases were registered, yielding an overall prevalence of 1.31 per 10,000 births. Because the estimate was heterogeneous, possible causes of variations among populations were analyzed: random variation, under‐reporting and over‐reporting bias, variation in proportion of termination of pregnancies among all registered cases and real differences among populations. CONCLUSIONS: The data do not suggest large differences in total prevalence of HPE among the studied populations that would be useful to generate etiological hypotheses. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.     

QTL alleles on chromosome 7 from fatty Meishan pigs reduce fat deposition

~~QTL alleles on chromosome 7 from fatty Meishan pigs reduce fat deposition@岳根华$Department of Animal Breeding and Biotechnology,University of Hohenheim!Garbenstr.17,70593 Stutt-gart,GermanyCurrent address:Institute of Molecular Agrobiology,national University of Singapore @Petra Beeckmann$Department of Animal Breeding and Biotechnology,University of Hohenheim!Garbenstr.17,70593 Stutt-gart,Germany @Gerhard Moser$Department of Animal Breeding and Biotechnology,University…     

Crystal structure of the endosomal SNARE complex reveals common structural principles of all SNAREs.

SNARE proteins are crucial for intracellular membrane fusion in all eukaryotes. These proteins assemble into tight complexes that connect membranes and may induce fusion. The crystal structure of the neuronal core complex is represented by an unusually long bundle of four alpha-helices connected by 16 layers of mostly hydrophobic amino acids. Here we report the 1.9 A resolution crystal structure of an endosomal SNARE core complex containing four SNAREs: syntaxin 7, syntaxin 8, vti1b and endobrevin/VAMP-8. Despite limited sequence homology, the helix alignment and the layer structure of the endosomal complex are remarkably similar to those of the neuronal complex. However, subtle variations are evident that characterize different SNARE subfamilies. We conclude that the structure of the SNARE core complex is an evolutionarily conserved hallmark of all SNARE complexes and is intimately associated with the general role of SNAREs in membrane fusion.     

The kinetics of electron entry in cytochromec oxidase

Summary The kinetics of electron entry in beef heart cytochromec oxidase have been studied by stopped-flow spectroscopy following chemical modification of the Cu_A site with mercurials. In this derivative Cu_A is no longer reducible by cytochrome c while cytochromea may accept electrons from the latter with rates comparable to the native enzyme. The results indicate that Cu_A is not the exclusive electron entry site in cytochromec oxidase.     

The integral membrane nucleoporin pom121 functionally links nuclear pore complex assembly and nuclear envelope formation

The metazoan nuclear envelope (NE) breaks down and reforms at each mitosis. Nuclear pore complexes (NPCs), which allow nucleocytoplasmic transport during interphase, assemble into the reforming NE at the end of mitosis. Using in vitro NE assembly assays, we show that one of the two transmembrane nucleoporins, pom121, is essential for NE formation, whereas the second, gp210, is dispensable. Depletion of either pom121-containing membrane vesicles or the protein alone does not affect vesicle binding to chromatin but prevents their fusion to form a closed NE. When the Nup107-160 complex, which is essential for integration of NPCs into the NE, is also depleted, pom121 becomes dispensable for NE formation, suggesting a close functional link between NPC and NE formation and the existence of a checkpoint that monitors NPC assembly state.     

HDLs induce raft domain vanishing in heterogeneous giant vesicles

Cholesterol efflux from the plasma membrane to HDLs is essential for cell cholesterol homeostasis. Recently, cholesterol-enriched ordered membrane domains, i.e. lipid rafts have been proposed to play an important role in this process. Here we introduce a new method to investigate the role of HDL interactions with the raft lipid phase and to directly visualize the effects of HDL-induced cholesterol efflux on rafts in model membranes. Addition of HDLs to giant lipid vesicles containing raft-type domains promoted decrease in size and disappearance of such domains as visualized by fluorescence microscopy. This was interpreted as resulting from cholesterol efflux from the vesicles to the HDLs. The raft vanishing rate was directly related to the HDL concentration. Evidence for a direct interaction of HDLs with the membrane was obtained by observing mutual adhesion of vesicles. It is suggested that the present method can be used to study the selective role of the bilayer lipid phase (raft and non-raft) in cholesterol efflux and membrane-HDL interaction and their underlying mechanisms. Such mechanisms may contribute to cholesterol efflux in vivo.