Processing of viral envelope glycoprotein by the endomannosidase pathway: evaluation of host cell specificity

Endo-alpha-D-mannosidase is an enzyme involved in N-linked oligosaccharide processing which through its capacity to cleave the internal linkage between the glucose-substituted mannose and the remainder of the polymannose carbohydrate unit can provide an alternate pathway for achieving deglucosylation and thereby make possible the continued formation of complex oligosaccharides during a glucosidase blockade. In view of the important role which has been attributed to glucose on nascent glycoproteins as a regulator of a number of biological events, we chose to further define the in vivo action of endomannosidase by focusing on the well characterized VSV envelope glycoprotein (G protein) which can be formed by the large array of cell lines susceptible to infection by this pathogen. Through an assessment of the extent to which the G protein was converted to an endo-beta-N- acetylglucosaminidase (endo H)-resistant form during a castanospermine imposed glucosidase blockade, we found that utilization of the endomannosidase-mediated deglucosylation route was clearly host cell specific, ranging from greater than 90% in HepG2 and PtK1 cells to complete absence in CHO, MDCK, and MDBK cells, with intermediate values in BHK, BW5147.3, LLC-PK1, BRL, and NRK cell lines. In some of the latter group the electrophoretic pattern after endo H treatment suggested that only one of the two N-linked oligosaccharides of the G protein was processed by endomannosidase. In the presence of the specific endomannosidase inhibitor, Glcalpha1-->3(1- deoxy)mannojirimycin, the conversion of the G protein into an endo H- resistant form was completely arrested. While the lack of G protein processing by CHO cells was consistent with the absence of in vitro measured endomannosidase activity in this cell line, the failure of MDBK and MDCK cells to convert the G protein into an endo H-resistant form was surprising since these cell lines have substantial levels of the enzyme. Similarly, we observed that influenza virus hemagglutinin was not processed in castanospermine-treated MDCK cells. Our findings suggest that studies which rely on glucosidase inhibition to explore the function of glucose in controlling such critical biological phenomena as intracellular movement or quality control should be carried out in cell lines in which the glycoprotein under study is not a substrate for endomannosidase action.      

Influence of language and ancestry on genetic structure of contiguous populations: A microsatellite based study on populations of Orissa

Background

Although cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, the severity of disease is highly variable indicating the influence of modifier genes. The intestines of Cftr deficient mice (CF mice: Cftr ^tm1Unc ) are prone to obstruction by excessive mucus accumulation and are used as a model of meconium ileus and distal intestinal obstruction syndrome. This phenotype is strongly dependent on the genetic background of the mice. On the C57Bl/6 background, the majority of CF mice cannot survive on solid mouse chow, have inflammation of the small intestine, and are about 30% smaller than wild type littermates. In this work potential modifier loci of the CF intestinal phenotype were identified.

Results

CF mice on a mixed genetic background (95% C57Bl/6 and 5% 129Sv) were compared to CF mice congenic on the C57Bl/6 background for several parameters of the intestinal CF phenotype. CF mice on the mixed background exhibit significantly greater survival when fed dry mouse chow, have reduced intestinal inflammation as measured by quantitative RT-PCR for marker genes, have near normal body weight gain, and have reduced mucus accumulation in the intestinal crypts. There was an indication of a gender effect for body weight gain: males did not show a significant improvement at 4 weeks of age, but were of normal weight at 8 weeks, while females showed improvement at both 4 and 8 weeks. By a preliminary genome-wide PCR allele scanning, three regions were found to be potentially associated with the milder phenotype. One on chr.1, defined by marker D1Mit36, one on chr. 9 defined by marker D9Mit90, and one on chr. 10, defined by marker D10Mit14.

Conclusion

Potential modifier regions were found that have a positive impact on the inflammatory phenotype of the CF mouse small intestine and animal survival. Identification of polymorphisms in specific genes in these regions should provide important new information about genetic modifiers of the CF intestinal phenotype.     

Phylogeny of the M superhaplogroup inferred from complete mitochondrial genome sequence of Indian specific lineages

Background  

Phylogenetic analysis of human complete mitochondrial DNA sequences has largely contributed to resolving phylogenies and antiquity of different lineages belonging to the majorhaplogroups L, N and M (East-Asian lineages). In the absence of whole mtDNA sequence information of M lineages reported in India that exhibits highest diversity within the sub-continent, the present study was undertaken to provide a detailed analysis of this haplogroup to precisely characterize the lineages and unravel their intricate phylogeny.     

Peripartum Cardiomyopathy Presenting With Ventricular Tachycardia: A Rare Presentation

A 25-year-old previously asymptomatic pregnant woman at 36 weeks'' gestation was noticed to have repetitive monomorphic ventricular tachycardia. A dilated left ventricle with moderately reduced systolic function was found on echocardiographic examination. This is a very rare presentation of peripartum cardiomyopathy (PPCMP) presenting with repetitive monomorphic ventricular tachycardia.     

A sawdust-derived soil conditioner promotes plant growth and improves water-holding capacity of different types of soils

Sawdust, a bulky waste generated by wood processing industries, has very few profitable and ecofriendly uses and poses a problem of proper disposal. Treatment with the fungusVolvariella volvaceae and a dilute solution of urea converted sawdust from a phytoinhibitory material to a phytostimulatory soil conditioner. In different types of soils, the soil conditioner increased the moisture retention and facilitated the cohesive interaction of particles. Analyses of the major biopolymers of sawdust after fungal treatment indicated that levels of cellulose, hemicellulose and lignin decreased; however, these changes did not account for the plant growth stimulatory property attained by this material.     

Transcriptional activation of the human immunodeficiency virus long terminal repeat sequences by cis-platin

We constructed a recombinant plasmid, pBHIV1 carrying the long terminal repeat (LTR) of the human immunodeficiency virus 1 (HIV-1), linked to the chloramphenicol acetyl transferase (CAT) gene plasmid. Plasmid pBHIV1 also contains the aminoglycoside phosphotransferase gene as a selectable marker. We introduced pBHIV1 in rat 208F fibroblasts and obtained stable geneticin resistant RFBHIV1-1 transfectant cells. A further control used was plasmid p202A, which carries the mutant T24 H-ras1 promoter linked to the promotorless cat gene. Plasmid p202A also carries the aph gene as a selectable marker and was transfected into 208F cells to obtain stable transfectant RF202A-1 cells. Both RFBHIV1-1 and RF202A-1 cells expressed CAT activity from the HIV LTR and T24 H-ras1 promoters. The response to cis-platin, a platin derivative and hexadecyl-phosphocholine was studied on the HIV LTR and H-ras1 regulated CAT activity in RFBHIV1-1 and RF202A-1 cells. It was found that at 5 x 10(-5) M concentrations cis-platin stimulates by 22-fold the expression of CAT from the HIV LTR, whereas only a 4-fold stimulation was observed on the T24 H-ras1 promoter. Our results suggest caution against therapy including this compound at cytotoxic concentrations in the treatment of AIDS patients.     

Plant 2-arylobenzofurans demonstrate a selective estrogen receptor modulator profile

We have isolated from the plant Onobrychis ebenoides three novel arylobenzofurans with binding affinity for the estrogen receptor. In this study, we evaluated these arylobenzofurans, namely ebenfuran I, ebenfuran II and ebenfuran III for their potential selective estrogen receptor modulator (SERM)-like properties. We examined their ability, (1) to induce the insulin growth factor binding protein-3 (IGFBP-3) in MCF-7 breast cancer cells, (2) to stimulate differentiation and mineralization of osteoblastic cell culture by histochemical staining for alkaline phosphatase, Alizarin Red-S staining and calcium levels in the supernatants and (3) to inhibit cell proliferation of cervical adenocarcinoma (Hela) cells by use of the MTT assay. An estrogen receptor mediated effect was investigated by carrying out chloramphenicol acetyl transferase (CAT) assay on transient MCF-7 transfectants. Estradiol and the "pure" antiestrogen ICI 182780 were included to serve as control samples of the estrogenic and antiestrogenic effect respectively. Our data reveal that ebenfuran II is a highly potent SERM, exhibiting antiestrogenic activity in breast cancer cells via the estrogen receptor, estrogenic effect on osteoblasts and no stimulatory effect on cervix adenocarcinoma cells. In conclusion, our study is the first to demonstrate that plant derived arylobenzofurans show a SERM profile and may be considered for the prevention and treatment of diseases such as breast cancer, cervical cancer and osteoporosis.     

Tracking the genetic imprints of lost Jewish tribes among the gene pool of Kuki-Chin-Mizo population of India

Background  

The Kuki-Chin-Mizo population comprising traditionally endogamous tribal groups residing in the state of Mizoram, India claim their descent from the ten lost tribes of Israel that were exiled by the Assyrians. To ascertain their oral history, we analysed DNA markers comprising 15 autosomal microsatellite markers, 5 biallelic and 20 microsatellite markers on Y-chromosome and the maternally inherited mitochondrial DNA sequence variations on 414 individuals belonging to 5 tribal communities from Mizoram (Hmar, Kuki, Mara, Lai and Lusei). The genetic profiles obtained were compared either with populations sharing Jewish ancestry or with local populations along the probable route of migration of the Jewish ancestry claimant Mizoram tribes.     

Articles selected by Faculty of 1000: plant comparative mitochondrial genomics; open source proteomics database; identifying disease-associated enzymes; predicting microRNA targets; genome annotation using polymorphisms

Background

Phylogenetic analysis of human complete mitochondrial DNA sequences has largely contributed to resolving phylogenies and antiquity of different lineages belonging to the majorhaplogroups L, N and M (East-Asian lineages). In the absence of whole mtDNA sequence information of M lineages reported in India that exhibits highest diversity within the sub-continent, the present study was undertaken to provide a detailed analysis of this haplogroup to precisely characterize the lineages and unravel their intricate phylogeny.

Results

The phylogenetic tree constructed from sequencing information of twenty four whole mtDNA genome revealed novel substitutions in the previously defined M2a and M6 lineages. The most striking feature of this phylogenetic tree is the formulation of a new lineage M30, distinguished by the presence of 12007 transition, and comprises of the recently defined M18 and a potential new sub-lineage possessing substitution at 16223 and 16300. M30 further branches into M30a sub-lineage, defined by 15431 and 195A substitution. The age of M30 lineage was estimated at 33,042 YBP, indicating a more recent expansion time than M2 (49,686 YBP). Contradictory to earlier reports, the M5 lineage does not always include a 12477 substitution, and is more appropriately defined by a transversion at 10986A. The phylogenetic tree also identifies a potential new lineage M* with HVSI sequence 16223,16325. No new substitutions were found in M25 and the M3 mt DNA genome could only be tentatively rooted by 16126 mutation. M4 and M*(16251, 16267) lineages could not be resolved distinctly.

Conclusions

This study describes seven new basal mutations and fourteen lineages that substantially contribute to the present understanding of superhaplogroup M. The phylogenetic tree supported by median-joining network helps in distinctly identifying the genetic relation between different M lineages that could not be achieved solely by control region sequence information. Although high control region diversity has been reported in the different M lineages distributed in India, complete sequencing of M* and defined lineages suggests that these mt DNA genomes emerged from a limited number of branches arising from the M trunk.