The Association of the Vanin-1 N131S Variant with Blood Pressure Is Mediated by Endoplasmic Reticulum-Associated Degradation and Loss of Function

High blood pressure (BP) is the most common cardiovascular risk factor worldwide and a major contributor to heart disease and stroke. We previously discovered a BP-associated missense SNP (single nucleotide polymorphism)–rs2272996–in the gene encoding vanin-1, a glycosylphosphatidylinositol (GPI)-anchored membrane pantetheinase. In the present study, we first replicated the association of rs2272996 and BP traits with a total sample size of nearly 30,000 individuals from the Continental Origins and Genetic Epidemiology Network (COGENT) of African Americans (P = 0.01). This association was further validated using patient plasma samples; we observed that the N131S mutation is associated with significantly lower plasma vanin-1 protein levels. We observed that the N131S vanin-1 is subjected to rapid endoplasmic reticulum-associated degradation (ERAD) as the underlying mechanism for its reduction. Using HEK293 cells stably expressing vanin-1 variants, we showed that N131S vanin-1 was degraded significantly faster than wild type (WT) vanin-1. Consequently, there were only minimal quantities of variant vanin-1 present on the plasma membrane and greatly reduced pantetheinase activity. Application of MG-132, a proteasome inhibitor, resulted in accumulation of ubiquitinated variant protein. A further experiment demonstrated that atenolol and diltiazem, two current drugs for treating hypertension, reduce the vanin-1 protein level. Our study provides strong biological evidence for the association of the identified SNP with BP and suggests that vanin-1 misfolding and degradation are the underlying molecular mechanism.     

Haplotype-based quantitative trait mapping using a clustering algorithm

Background  

With the availability of large-scale, high-density single-nucleotide polymorphism (SNP) markers, substantial effort has been made in identifying disease-causing genes using linkage disequilibrium (LD) mapping by haplotype analysis of unrelated individuals. In addition to complex diseases, many continuously distributed quantitative traits are of primary clinical and health significance. However the development of association mapping methods using unrelated individuals for quantitative traits has received relatively less attention.     

A framework for structural equation models in general pedigrees

Background/Aims: Structural Equation Modeling (SEM) is an analysis approach that accounts for both the causal relationships between variables and the errors associated with the measurement of these variables. In this paper, a framework for implementing structural equation models (SEMs) in family data is proposed. Methods: This framework includes both a latent measurement model and a structural model with covariates. It allows for a wide variety of models, including latent growth curve models. Environmental, polygenic and other genetic variance components can be included in the SEM. Kronecker notation makes it easy to separate the SEM process from a familial correlation model. A limited information method of model fitting is discussed. We show how missing data and ascertainment may be handled. We give several examples of how the framework may be used. Results: A simulation study shows that our method is computationally feasible, and has good statistical properties. Conclusion: Our framework may be used to build and compare causal models using family data without any genetic marker data. It also allows for a nearly endless array of genetic association and/or linkage tests. A preliminary Matlab program is available, and we are currently implementing a more complete and user-friendly R package.     

A rickettsiales-like infection in the Pacific razor clam, Siliqua patula

An intracellular procaryotic rickettsiales-like organism was discovered in the digestive absorptive epithelium of the Pacific razor clam, Siliqua patula, from the Pacific Coast of Washington State. Of 80 animals examined, 30% contained the organisms, and all positive animals were between 1.5 mm and 3.0 cm shell length. The organisms appeared as basophilic inclusions averaging 5.0 μm in diameter. Ultrastructurally, the inclusions were membrane-bound vacuoles containing procaryotic forms which averaged 0.8 μm by up to 1.8 μm in length. These organisms had a double layer of trilaminar membrane which appeared to form blebs and outer membrane vesicles. The organisms were pleomorphic by both histological and electron microscopical examination. The host response to infection appeared to consist only of the rounding and detachment of the infected cells. Specific immunofluorescent tests for Rickettsia rickettsia, R. prowazekii, Coxiella burnetti, Chlamydia psittaci, and Legionella pneumophila were all negative when tested on impression smears of infected clam digestive gland.     

Natural Attachment Duration of Adult Female Ticks Ixodes Uriae (Acari: Ixodidae) on Free-Living Adult Black-Legged Kittiwakes Rissa Tridactyla

An investigation into the attachment duration of the tick Ixodes uriae on free-living adult black-legged kittiwakes Rissa tridactyla was carried out at a colony in southeast Scotland. Adult kittiwakes (n = 14) were caught and searched for ticks. Newly attached ticks (n = 31) were marked as was the bird before its release. These birds were recaptured at intervals of two to seven days and the presence or absence of the tick was recorded. The median attachment duration was estimated as 7.7 days (SE = 0.38) and estimated times for 5% and 95% of ticks to become detached were 5.22 days (SE = 0.67) and 9.51 days (SE = 0.58) respectively. Information on tick attachment duration is essential for the development of accurate models of tick population dynamics and patterns of disease transmission.     

Alternate pathogenesis of systemic neoplasia in the bivalve mollusc Mytilus.

The proliferative disease systemic neoplasia, also termed hemic neoplasia or disseminated sarcoma, was studied in four Puget Sound, Washington populations of the bay mussel (Mytilus sp.). Using flow cytometric measurement of DAPI-stained cells withdrawn from the hemolymph, DNA content frequency histograms were generated for 73 individuals affected by the disease. The cells manifesting systemic neoplasia were found to exist as either of two separate types, characterized by G0G1 phase nuclear DNA contents of either approximately 4.9 x haploid (pentaploid form) or approximately 3.8 x haploid (tetraploid form). The two disease forms were found to coexist in all four mussel populations sampled, with overall relative prevalences of 66% pentaploid form, 29% tetraploid form, and 5% exhibiting both disease forms simultaneously. These findings represent the first unequivocal demonstration of multiple cell types in a bivalve neoplasia. The two forms appear to represent separate pathogenetic processes rather than sequential stages of a single pathogenesis. Two cell cycling parameters associated with proliferative activity were employed to compare the alternate forms: (i) the percentage of cells assigned to the DNA Synthesis (S) phase of the neoplastic cell cycle, and (ii) the proportion of neoplastic cell mitotic figures in hemocytological preparations. Mean values for both parameters were significantly higher for mussels with the tetraploid form of the disease, suggesting a higher rate of proliferation relative to the pentaploid form. Qualitatively, cells of the tetraploid form contained slightly lower nuclear and cytoplasmic volumes compared to those of the pentaploid form. An observed wide variation in neoplastic cell nuclear size within either disease form may reflect the distribution of cells in the G0G1, S, and G2M phases of the cell cycle. Potential etiologic relationships between the two forms are discussed.     

PGM1 null allele detected in a Caucasian mother-son pair

The presence of a PGM1 null allele in a mother and her son was deduced from their inconsistent phenotypes. Quantitation studies were done to confirm the half-normal enzyme activity. Phenotype analysis of 29 additional genetic markers gave no indication of non-parentage, making non-maternity a very unlikely explanation for the discrepancy.