C. elegans Agrin Is Expressed in Pharynx, IL1 Neurons and Distal Tip Cells and Does Not Genetically Interact with Genes Involved in Synaptogenesis or Muscle Function

Agrin is a basement membrane protein crucial for development and maintenance of the neuromuscular junction in vertebrates. The C. elegans genome harbors a putative agrin gene agr-1. We have cloned the corresponding cDNA to determine the primary structure of the protein and expressed its recombinant fragments to raise specific antibodies. The domain organization of AGR-1 is very similar to the vertebrate orthologues. C. elegans agrin contains a signal sequence for secretion, seven follistatin domains, three EGF-like repeats and two laminin G domains. AGR-1 loss of function mutants did not exhibit any overt phenotypes and did not acquire resistance to the acetylcholine receptor agonist levamisole. Furthermore, crossing them with various mutants for components of the dystrophin-glycoprotein complex with impaired muscle function did not lead to an aggravation of the phenotypes. Promoter-GFP translational fusion as well as immunostaining of worms revealed expression of agrin in buccal epithelium and the protein deposition in the basal lamina of the pharynx. Furthermore, dorsal and ventral IL1 head neurons and distal tip cells of the gonad arms are sources of agrin production, but no expression was detectable in body muscles or in the motoneurons innervating them. Recombinant worm AGR-1 fragment is able to cluster vertebrate dystroglycan in cultured cells, implying a conservation of this interaction, but since neither of these proteins is expressed in muscle of C. elegans, this interaction may be required in different tissues. The connections between muscle cells and the basement membrane, as well as neuromuscular junctions, are structurally distinct between vertebrates and nematodes

Palatal development of preterm and low birthweight infants compared to term infants – What do we know? Part 1: The palate of the term newborn

BACKGROUND: The evidence on prematurity as 'a priori' a risk for palatal disturbances that increase the need for orthodontic or orthognathic treatment is still weak. Further well-designed clinical studies are needed. The objective of this review is to provide a fundamental analysis of methodologies, confounding factors, and outcomes of studies on palatal development. One focus of this review is the analysis of studies on the palate of the term newborn, since knowing what is 'normal' is a precondition of being able to assess abnormalities. METHODS: A search profile based on Cochrane search strategies applied to 10 medical databases was used to identify existing studies. Articles, mainly those published before 1960, were identified from hand searches in textbooks, encyclopedias, reference lists and bibliographies. Sources in English, German, and French of more than a century were included. Data for term infants were recalculated if particular information about weight, length, or maturity was given. The extracted values, especially those from non-English paper sources, were provided unfiltered for comparison. RESULTS: The search strategy yielded 182 articles, of which 155 articles remained for final analysis. Morphology of the term newborn's palate was of great interest in the first half of the last century. Two general methodologies were used to assess palatal morphology: visual and metrical descriptions. Most of the studies on term infants suffer from lack of reliability tests. The groove system was recognized as the distinctive feature of the infant palate. The shape of the palate of the term infant may vary considerably, both visually and metrically. Gender, race, mode of delivery, and nasal deformities were identified as causes contributing to altered palatal morphology. Until today, anatomical features of the newborn's palate are subject to a non-uniform nomenclature. CONCLUSION: Today's knowledge of a newborn's 'normal' palatal morphology is based on non-standardized and limited methodologies for measuring a three-dimensional shape. This shortcoming increases bias and is the reason for contradictory research results, especially if pathologic conditions like syndromes or prematurity are involved. Adequate measurement techniques are needed and the 'normal palatal morphology' should be defined prior to new clinical studies on palatal development

Topological Analysis of Small Leucine-Rich Repeat Proteoglycan Nyctalopin

Nyctalopin is a small leucine rich repeat proteoglycan (SLRP) whose function is critical for normal vision. The absence of nyctalopin results in the complete form of congenital stationary night blindness. Normally, glutamate released by photoreceptors binds to the metabotropic glutamate receptor type 6 (GRM6), which through a G-protein cascade closes the non-specific cation channel, TRPM1, on the dendritic tips of depolarizing bipolar cells (DBCs) in the retina. Nyctalopin has been shown to interact with TRPM1 and expression of TRPM1 on the dendritic tips of the DBCs is dependent on nyctalopin expression. In the current study, we used yeast two hybrid and biochemical approaches to investigate whether murine nyctalopin was membrane bound, and if so by what mechanism, and also whether the functional form was as a homodimer. Our results show that murine nyctalopin is anchored to the plasma membrane by a single transmembrane domain, such that the LRR domain is located in the extracellular space

Insertion and abstraction pathways in the reaction O(1D2) + H2-->OH+H.

Rigorous quantum dynamical calculations have been performed on the ground 1 1A' and first excited 1 1A" electronic states of the title reaction, employing the most accurate potential energy surfaces available. Product rovibrational quantum state populations and rotational angular momentum alignment parameters are reported, and are compared with new experimental, and quasiclassical trajectory calculated results. The quantum calculations agree quantitatively with experiment, and reveal unequivocally that the 1 1A" excited state participates in the reaction

Relative androgen deficiency in relation to obesity and metabolic status in older men

The definitive version is available at www.blackwell-synergy.comBackground: Although androgen deficiency in men has been linked with obesity and the metabolic syndrome, whether it predisposes to, or is a consequence of, type 2 diabetes mellitus (T2DM) is still unclear. Objective: To determine the relationship between plasma androgen levels, obesity, metabolic status and T2DM in men of 70 years or older. Design and methods: A sample of 195 men from the Australian Longitudinal Study of Ageing with a mean age of 76.2 ± 0.3 years were followed up for 8 years. Total testosterone (TT), fasting plasma glucose (FPG), urate, serum creatinine, total cholesterol (TC), HDL cholesterol (HDL-C), LDL cholesterol (LDL-C), triglycerides (TG), blood pressure (BP), body mass index (BMI), waist circumference (WC) and diabetic status were assessed at baseline. Self-reported diabetic status was obtained after 8 years. Metabolic syndrome was diagnosed based on the Third National Cholesterol Education Program Adult Treatment Panel clinical criteria. Results: TT levels were lower in diabetic men compared with non-diabetic men (12.1 ± 0.7 vs. 14.2 ± 0.4 nmol/l, p = 0.026). TT levels in healthy, non-diabetic men over 80 years of age were lower (11.9 ± 0.8 vs. 15.0 ± 0.5 nmol/l, p = 0.002) than TT levels in those aged 70–79 years, inversely related to BMI (r = −0.26, p = 0.001), WC (r = −0.30, p < 0.001) and TG (r = −0.22, p = 0.005) and positively related to LDL-C (r = 0.25, p = 0.002). Men with the metabolic syndrome had significantly lower levels of TT and HDL-C, and higher values of BP, FPG, TG, BMI and WC, compared with those without. However, no significant difference in plasma TT levels was noted between men with incident T2Dm and healthy men. Stepwise linear regression analysis revealed that only LDL-C and WC related significantly to the variance of TT. Multiple logistic regression revealed FPG to be the only independent predictor of incident diabetes (odds ratio = 60.2, p = 0.003). Conclusions: Testosterone levels continue to decline even in healthy men over the age of 80 years. Although TT levels were inversely related to visceral obesity and several components of the metabolic syndrome, our data do not support a predictive or causative role for decreasing TT levels in the development of incident T2Dm. Androgen deficiency is consequent upon, rather than a cause of, poor metabolic status.R. Y. T. Chen, G. A. Wittert, and G. R. Andrew

Translocation of a long amino-terminal domain through ER membrane by following signal-anchor sequence

Type I signal-anchor sequences mediate translocation of the N-terminal domain (N-domain) across the endoplasmic reticulum (ER) membrane. To examine the translocation in detail, dihydrofolate reductase (DHFR) was fused to the N-terminus of synaptotagmin II as a long N-domain. Translocation was arrested by the DHFR ligand methotrexate, which stabilizes the folding of the DHFR domain, and resumed after depletion of methotrexate. The targeting of the ribosome–nascent chain complex to the ER requires GTP, whereas N-domain translocation does not require any nucleotide triphosphates. Significant translocation was observed even in the absence of a lumenal hsp70 (BiP). When the nascent polypeptide was released from the ribosomes after the membrane targeting, the N-domain translocation was suppressed and the nascent chain was released from the translocon. Ribosomes have a crucial role in maintaining the translocation-intermediate state. The translocation of the DHFR domain was greatly impaired when it was separated from the signal-anchor sequence. Unfolding and translocation of the DHFR domain must be driven by the stroke of the signal-anchor sequence into translocon