Biochemical and immunological approaches to the study of gap junctional communication

Summary Studies on gap junctions isolated from rat liver by a procedure that avoids exogenous proteolysis (Hertzberg, E. L.; Gilula, N. B.; J. Biol. Chem. 254: 2138–2147; 1979) are described. The original isolation procedure was modified to increase the yield and has been extended to the preparation of gap junctions from mouse and bovine liver. Peptide map studies showed that the 27,000-dalton polypeptides present in liver gap junction preparations from all three sources are homologous and are not derived from other polypeptides of higher molecular weight that are observed in cruder preparations. Similar studies with lens fiber junctions demonstrated no homology between liver and lens junction polypeptides. Antibodies to the lens junction polypeptide did not cross-react with the liver gap junction polypeptide, further supporting this conclusion. Presented in the symposium on Molecular and Morphological Aspects of Cell-Cell Communication at the 31st Annual Meeting of the Tissue Culture Association, St. Louis, Missouri, June 1–5, 1980. This symposium was supported in part by Contract 263-MD-025754 from the National Cancer Institute and the Fogarty International Center. Research in the laboratory was supported by grants to Dr. Gilula from the National Institute of Health (HL 16507 and GM 24753).     

Phenylalanine hydroxylase gene haplotypes in Polynesians: evolutionary origins and absence of alleles associated with severe phenylketonuria.

A total of 630 haplotypes for the phenylalanine hydroxylase (PAH) gene locus were established in five groups of Polynesians comprising Samoans, Tongans, Cook Islanders, Maori, and Niueans. Considerable genetic continuity was demonstrated between these widely dispersed populations, since three common haplotypes (4, 1, and 7) constituted over 95% of alleles. A control group of individuals from Southeast Asia shared the same major haplotypes, 4, 1, and 7, with Polynesians. These data provide further support for the theories of genetic homogeneity and of Asian affinities of the Polynesian precursor populations. The absence of severe phenylketonuria (PKU) in both Polynesians and Southeast Asians is consistent with the lack of PAH haplotypes 2 and 3, on which the severe PKU mutants have arisen among Caucasians.     

Limited genetic diversity in polynesians reflected in the highly polymorphic 3'HVR alpha-globin gene marker.

Polynesians from five distinct island groups were studied with DNA probe alpha 3'HVR, a highly polymorphic VNTR (variable number of tandem repeats) minisatellite region associated with the alpha-globin gene cluster. Results showed a paucity of genetic heterozygosity together with clustering of alpha 3'HVR alleles with alpha-globin DNA haplotypes and alpha-globin gene rearrangements. This restricted diversity is consistent with population bottlenecks in the colonization of Polynesia.     

Albert Damon's contributions to engineering anthropology

The work by physical anthropologists in general, and by Albert Damon in particular, for U. S. flying personnel during World War II led to anthropological improvements in the combat effectiveness, safety and comfort of aircrewmen important in the outcome of that conflict. The efforts of those men created the foundations of a new profession, Engineering Anthropology, which has become an essential part of an even broader movement, Human Factors Engineering (or Ergonomics in Europe) in modern technology.     

Patterns of abundance and demography: Collembola in a habitat patch gradient

The demography and abundance of Collembola in relation to a gradient of increasingly isolated tussocks of Carex ursina were investigated near Ny-Alesund, Svalbard The study area was divided into three zones according to tussock density Ten tussocks were sampled in each zone In addition, samples were taken between tussocks, which consisted of ground covered with a layer of cyanobacteria A total of ten Collembola species were found, five of which were chosen for further studies The Carex tussocks were the preferred habitat for the majority of these species Only one species, Hypogastrura viatica, was found regularly between tussocks, although at low density The gradient in tussock distribution was probably an important factor in determining the distribution, abundance and the underlying demographic processes of most species This was indicated by an increase in demographic heterogeneity with patch isolation The different species were affected differently, however Whereas one species appeared to be unaffected by the gradient (H viatica), two species (H longispina) and (Folsomia sexoculata) were somewhat surprisingly found to have their highest density where tussocks were furthest apart Factors other than the spatial configuration of the habitat are probably important in determining the distribution of these two species, indicated by a positive correlation at tussock level between them In accordance with general hypotheses on the effect of patchiness on population dynamics the remaining two species, F quadrioculata and Onvchiurus groenlandicus, occurred in very low numbers or not at all, respectively, in the zone where tussocks were furthest apart Their response is probably dependent on their ability to successfully colonise isolated tussocks We predict that different species specific demographic strategies, and in particular dispersal rates may account for the observed patterns     

Non-typeable pneumococci circulating in Portugal are of cps type NCC2 and have genomic features typical of encapsulated isolates

Background

Pneumococcus is a major human pathogen and the polysaccharide capsule is considered its main virulence factor. Nevertheless, strains lacking a capsule, named non-typeable pneumococcus (NT), are maintained in nature and frequently colonise the human nasopharynx. Interest in these strains, not targeted by any of the currently available pneumococcal vaccines, has been rising as they seem to play an important role in the evolution of the species. Currently, there is a paucity of data regarding this group of pneumococci. Also, questions have been raised on whether they are true pneumococci. We aimed to obtain insights in the genetic content of NT and the mechanisms leading to non-typeability and to genetic diversity.

Results

A collection of 52 NT isolates representative of the lineages circulating in Portugal between 1997 and 2007, as determined by pulsed-field gel electrophoresis and multilocus sequence typing, was analysed. The capsular region was sequenced and comparative genomic hybridisation (CGH) using a microarray covering the genome of 10 pneumococcal strains was carried out. The presence of mobile elements was investigated as source of intraclonal variation. NT circulating in Portugal were found to have similar capsular regions, of cps type NCC2, i.e., having aliB-like ORF1 and aliB-like ORF2 genes. The core genome of NT was essentially similar to that of encapsulated strains. Also, competence genes and most virulence genes were present. The few virulence genes absent in all NT were the capsular genes, type-I and type-II pili, choline-binding protein A (cbpA/pspC), and pneumococcal surface protein A (pspA). Intraclonal variation could not be entirely explained by the presence of prophages and other mobile elements.

Conclusions

NT circulating in Portugal are a homogeneous group belonging to cps type NCC2. Our observations support the theory that they are bona-fide pneumococcal isolates that do not express the capsule but are otherwise essentially similar to encapsulated pneumococci. Thus we propose that NT should be routinely identified and reported in surveillance studies.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-863) contains supplementary material, which is available to authorized users.     

Experimental stress in inflammatory rheumatic diseases: a review of psychophysiological stress responses

Introduction  

Stressful events are thought to contribute to the aetiology, maintenance and exacerbation of rheumatic diseases. Given the growing interest in acute stress responses and disease, this review investigates the impact of real-life experimental psychosocial, cognitive, exercise and sensory stressors on autonomic, neuroendocrine and immune function in patients with inflammatory rheumatic diseases.     

Identification of Mendelian inconsistencies between SNP and pedigree information of sibs

Background

Using SNP genotypes to apply genomic selection in breeding programs is becoming common practice. Tools to edit and check the quality of genotype data are required. Checking for Mendelian inconsistencies makes it possible to identify animals for which pedigree information and genotype information are not in agreement.

Methods

Straightforward tests to detect Mendelian inconsistencies exist that count the number of opposing homozygous marker (e.g. SNP) genotypes between parent and offspring (PAR-OFF). Here, we develop two tests to identify Mendelian inconsistencies between sibs. The first test counts SNP with opposing homozygous genotypes between sib pairs (SIBCOUNT). The second test compares pedigree and SNP-based relationships (SIBREL). All tests iteratively remove animals based on decreasing numbers of inconsistent parents and offspring or sibs. The PAR-OFF test, followed by either SIB test, was applied to a dataset comprising 2,078 genotyped cows and 211 genotyped sires. Theoretical expectations for distributions of test statistics of all three tests were calculated and compared to empirically derived values. Type I and II error rates were calculated after applying the tests to the edited data, while Mendelian inconsistencies were introduced by permuting pedigree against genotype data for various proportions of animals.

Results

Both SIB tests identified animal pairs for which pedigree and genomic relationships could be considered as inconsistent by visual inspection of a scatter plot of pairwise pedigree and SNP-based relationships. After removal of 235 animals with the PAR-OFF test, SIBCOUNT (SIBREL) identified 18 (22) additional inconsistent animals.Seventeen animals were identified by both methods. The numbers of incorrectly deleted animals (Type I error), were equally low for both methods, while the numbers of incorrectly non-deleted animals (Type II error), were considerably higher for SIBREL compared to SIBCOUNT.

Conclusions

Tests to remove Mendelian inconsistencies between sibs should be preceded by a test for parent-offspring inconsistencies. This parent-offspring test should not only consider parent-offspring pairs based on pedigree data, but also those based on SNP information. Both SIB tests could identify pairs of sibs with Mendelian inconsistencies. Based on type I and II error rates, counting opposing homozygotes between sibs (SIBCOUNT) appears slightly more precise than comparing genomic and pedigree relationships (SIBREL) to detect Mendelian inconsistencies between sibs.