Genetic analysis of murine strains C57BL/6J and C3H/HeJ to confirm the map position ofAth-1, a gene determining atherosclerosis susceptibility

Previous results suggested that strains C57BL/6J and C3H/HeJ differed in a single gene for atherosclerosis susceptibility, calledAth-1. Based on data from recombinant inbred strainsAth-1 was tentatively assigned to chromosome 1 linked toAlp-2. In this report, a cross between C57BL/6 and C3H/HeJ was carried out in order to test whether the tentative map position was correct. Parental strains and F₁ and F₂ progeny were examined. Susceptible alleles ofAth-1, found in C57BL/6, are associated with relatively low levels of high-density lipoprotein (HDL)-cholesterol in animals fed an atherogenic diet; resistant alleles ofAth-1 are associated with relatively high levels of HDL-cholesterol. F₁ progeny have HDL levels that are intermediate between these of the two parental strains. Among the F₂ progeny,Alp-2 andAth-1 cosegregated, providing confirmatory evidence thatAth-1 is linked toAlp-2 on chromosome 1. Three mice recombinant forAlp-2 andAth-1 were found among the 60 chromosomes tested, giving an estimated map distance between these two genes of 5.0±2.8 (SE) cM. The phenotypic characteristics ofAth-1 resemble a genetic trait in humans, hyperalphalipoproteinemia, which is characterized by elevated levels of HDL-cholesterol, reduced risk of heart disease, and increased longevity.This work was supported by Grant HL-32087 from the Heart, Lung, and Blood Institute, National Institutes of Health, Grant 1858 from the Council for Tobacco Research, Grant 86-1387 from the American Heart Association with funds contributed in part by the Alameda, Orange, and Santa Barbara County Chapters, and Grants 85-N132A and 85-N136A from the California Affiliate of the American Heart Association.     

Low codon bias and high rates of synonymous substitution in Drosophila hydei and D. melanogaster histone genes

We have evaluated codon usage bias in Drosophila histone genes and have obtained the nucleotide sequence of a 5,161-bp D. hydei histone gene repeat unit. This repeat contains genes for all five histone proteins (H1, H2a, H2b, H3, and H4) and differs from the previously reported one by a second EcoRI site. These D. hydei repeats have been aligned to each other and to the 5.0-kb (i.e., long) and 4.8-kb (i.e., short) histone repeat types from D. melanogaster. In each species, base composition at synonymous sites is similar to the average genomic composition and approaches that in the small intergenic spacers of the histone gene repeats. Accumulation of synonymous changes at synonymous sites after the species diverged is quite high. Both of these features are consistent with the relatively low codon usage bias observed in these genes when compared with other Drosophila genes. Thus, the generalization that abundantly expressed genes in Drosophila have high codon bias and low rates of silent substitution does not hold for the histone genes.      

Functional Loss of Semaphorin 3C and/or Semaphorin 3D and Their Epistatic Interaction with Ret Are Critical to Hirschsprung Disease Liability

Innervation of the gut is segmentally lost in Hirschsprung disease (HSCR), a consequence of cell-autonomous and non-autonomous defects in enteric neuronal cell differentiation, proliferation, migration, or survival. Rare, high-penetrance coding variants and common, low-penetrance non-coding variants in 13 genes are known to underlie HSCR risk, with the most frequent variants in the ret proto-oncogene (RET). We used a genome-wide association (220 trios) and replication (429 trios) study to reveal a second non-coding variant distal to RET and a non-coding allele on chromosome 7 within the class 3 Semaphorin gene cluster. Analysis in Ret wild-type and Ret-null mice demonstrates specific expression of Sema3a, Sema3c, and Sema3d in the enteric nervous system (ENS). In zebrafish embryos, sema3 knockdowns show reduction of migratory ENS precursors with complete ablation under conjoint ret loss of function. Seven candidate receptors of Sema3 proteins are also expressed within the mouse ENS and their expression is also lost in the ENS of Ret-null embryos. Sequencing of SEMA3A, SEMA3C, and SEMA3D in 254 HSCR-affected subjects followed by in silico protein structure modeling and functional analyses identified five disease-associated alleles with loss-of-function defects in semaphorin dimerization and binding to their cognate neuropilin and plexin receptors. Thus, semaphorin 3C/3D signaling is an evolutionarily conserved regulator of ENS development whose dys-regulation is a cause of enteric aganglionosis.     

Suicidal process,suicidal communication and psychosocial situation of young suicide attempters in a rural Vietnamese community

The study aimed to explore the suicidal process, suicidal communication and psychosocial situation of young suicide attempters in a rural community in Hanoi, Vietnam. Semi-structured interviews were conducted, in a community setting, with 19 suicide attempters aged 15-24 who had been consecutively hospitalized in an intensive care unit. In 12 of 19 cases, the first pressing, distinct and constant suicidal thoughts appeared less than one day before the suicide attempt in question. However, distress and mild, fleeting suicidal thoughts had been present up to six months before the suicide attempt in 16 cases. Five respondents had a suicide plan one to three days before attempting suicide. Altogether, 13 engaged in some form of suicidal communication before their attempt. This communication was, however, difficult for outsiders to interpret. Twelve of the respondents were victims of regular physical abuse and 16 had suffered psychological violence for at least one year before attempting suicide. Eighteen of the respondents used pesticides or raticides in their suicide attempts. None sought advice or consultation in the community despite long-standing psychosocial problems. The strategy of reducing the availability of suicide means (e.g., pesticides or raticides) in Asian countries should be complemented with a long-term suicide-preventive strategy that targets school dropouts and domestic violence, and promotes coping abilities and communication about psychological and social problems as well as recognition of signs of distress and suicidal communication.     

Xenopus TACC3/maskin is not required for microtubule stability but is required for anchoring microtubules at the centrosome

Members of the transforming acidic coiled coil (TACC) protein family are emerging as important mitotic spindle assembly proteins in a variety of organisms. The molecular details of how TACC proteins function are unknown, but TACC proteins have been proposed to recruit microtubule-stabilizing proteins of the tumor overexpressed gene (TOG) family to the centrosome and to facilitate their loading onto newly emerging microtubules. Using Xenopus egg extracts and in vitro assays, we show that the Xenopus TACC protein maskin is required for centrosome function beyond recruiting the Xenopus TOG protein XMAP215. The conserved C-terminal TACC domain of maskin is both necessary and sufficient to restore centrosome function in maskin-depleted extracts, and we provide evidence that the N terminus of maskin inhibits the function of the TACC domain. Time-lapse video microscopy reveals that microtubule dynamics in Xenopus egg extracts are unaffected by maskin depletion. Our results provide direct experimental evidence of a role for maskin in centrosome function and suggest that maskin is required for microtubule anchoring at the centrosome.     

Proof-of-concept human laboratory study for protracted abstinence in alcohol dependence: effects of gabapentin

There is a need for safe medications that can effectively support recovery by treating symptoms of protracted abstinence that may precipitate relapse in alcoholics, e.g. craving and disturbances in sleep and mood. This proof-of-concept study reports on the effectiveness of gabapentin 1200 mg for attenuating these symptoms in a non-treatment-seeking sample of cue-reactive, alcohol-dependent individuals. Subjects were 33 paid volunteers with current Diagnostic and Statistical Manual of Mental Disorders-IV alcohol dependence and a strength of craving rating 1 SD or greater for alcohol than water cues. Subjects were randomly assigned to gabapentin or placebo for 1 week and then participated in a within-subjects trial where each was exposed to standardized sets of pleasant, neutral and unpleasant visual stimuli followed by alcohol or water cues. Gabapentin was associated with significantly greater reductions than placebo on several measures of subjective craving for alcohol as well as for affectively evoked craving. Gabapentin was also associated with significant improvement on several measures of sleep quality. Side effects were minimal, and gabapentin effects were not found to resemble any major classes of abused drugs. Results suggest that gabapentin may be effective for treating the protracted abstinence phase in alcohol dependence and that a randomized clinical trial would be an appropriate next step. The study also suggests the value of cue-reactivity studies as proof-of-concept screens for potential antirelapse drugs.