Telomeric repeat [TTAGGG]n sequences of human chromosomes are conserved in chimpanzee (Pan troglodytes)

Summary Using a series of genetic parameters, attempts have been made for more than two decades to establish the close kinship of human (Homo sapiens) with chimpanzee (Pan troglodytes). Molecular and cytogenetic data presently suggest that the two species are closely related. The recent isolation of a human telomeric probe (P5097-B.5) has prompted us to cross hybridize it to chimpanzee chromosomes in order to explore convergence and/or divergence of the telomeric repeat sequences (TTAGGG)_n. On hybridization, the human probe bound to both ends (telomeres) of chimpanzee chromosomes, suggesting a concerted evolution of tandemly repeated short simple sequences (TTAGGG)_n. Even the terminal heterochromatin of chimpanzee chromosomes was found to be endowed with telomeric repeats, suggesting that evolution of heterochromatin and capping with tandemly repeated short sequences are highly complex phenomena.     

Purification and structural characterization of insulin from a caecilian, Typhlonectes natans (Amphibia: Gymnophiona)

Despite the important position of amphibia in phylogeny, efforts at the structural characterization of amphibian neurohormonal peptides have largely been confined to the Anurans (frogs and toads). Insulin was purified from an extract of the pancreas of the caecilian, Typhlonectes natans. The primary structure of the peptide was established as:

A-chain: Gly-Ile-Val-Glu-Lys⁵-Cys-Cys-Leu-Ser-Thr¹⁰-Cys-Ser-Leu-Tyr-Glu¹⁵-Leu-Glu-Ser-Tyr-Cys²⁰-Asn

B-chain: Ile-Ala-Asn-Gln-His⁵-Leu-Cys-Gly-Ser-His¹⁰-Leu-Val-Glu-Ala-Leu¹⁵-Tyr-Leu-Val-Cys-Ala²⁰-Asp-Arg-Gly-Phe- Phe²⁵-Tyr-Thr-Pro-Lys-Ser³⁰

This amino acid sequence contains several unusual substitutions (Gln → Lys at A5, His → Leu at A8, Gln → Glu at A15, and Gly → Ala at B20) that are not present in other amphibian insulins. The structure of insulin appears to be less well conserved among the different orders of amphibia, compared with reptiles and birds.     

The genomic sequence for Prader-Willi/Angelman syndromes' loci of human is apparently conserved in the great apes

Chromosomal changes through pericentric inversions play an important role in the origin of species. Certain pericentric inversions are too minute to be detected cytogenetically, thus hindering the complete reconstruction of hominoid phylogeny. The advent of the fluorescence in situ hybridization (FISH) technique has facilitated the identification of many chromosomal segments, even at the single gene level. Therefore the cosmid probe for Prader-Willi (PWS)/Angelman syndrome to the loci on human chromosome 15 [ql 1-12] is being used as a marker to highlight the complementary sequence in higher primates. We hybridized metaphase chromosomes of chimpanzee (PTR), gorilla (GGO), and orangutan (PPY) with this probe (Oncor) to characterize the chromosomal segments because the nature of these pericentric inversions remains relatively unknown. Our observations suggest that a pericentric inversion has occurred in chimpanzee chromosome (PTR 16) which corresponds to human chromosome 15 at PTR 16 band pl 112, while in gorilla (GGO 15) and orangutan (PPY 16) the bands q11-12 complemented to human chromosome 15 band q11-12. This approach has proven to be a better avenue to characterize the pericentric inversions which have apparently occurred during human evolution. Genetic divergence in the speciation process which occurs through chromosomal rearrangement needs to be reevaluated and further explored using newer techniques.Correspondence to: R.S. Verma     

Tobacco Smoking and Its Association with Illicit Drug Use among Young Men Aged 15-24 Years Living in Urban Slums of Bangladesh

Background

Tobacco smoking (TS) and illicit drug use (IDU) are of public health concerns especially in developing countries, including Bangladesh. This paper aims to (i) identify the determinants of TS and IDU, and (ii) examine the association of TS with IDU among young slum dwellers in Bangladesh.

Methodology/Principal Findings

Data on a total of 1,576 young slum dwellers aged 15–24 years were extracted for analysis from the 2006 Urban Health Survey (UHS), which covered a nationally representative sample of 13,819 adult men aged 15–59 years from slums, non-slums and district municipalities of six administrative regions in Bangladesh. Methods used include frequency run, Chi-square test of association and multivariable logistic regression. The overall prevalence of TS in the target group was 42.3%, of which 41.4% smoked cigarettes and 3.1% smoked bidis. The regression model for TS showed that age, marital status, education, duration of living in slums, and those with sexually transmitted infections were significantly (p<0.001 to p<0.05) associated with TS. The overall prevalence of IDU was 9.1%, dominated by those who had drug injections (3.2%), and smoked ganja (2.8%) and tari (1.6%). In the regression model for IDU, the significant (p<0.01 to p<0.10) predictors were education, duration of living in slums, and whether infected by sexually transmitted diseases. The multivariable logistic regression (controlling for other variables) revealed significantly (p<0.001) higher likelihood of IDU (OR = 9.59, 95% CI = 5.81–15.82) among users of any form of TS. The likelihood of IDU increased significantly (p<0.001) with increased use of cigarettes.

Conclusions/Significance

Certain groups of youth are more vulnerable to TS and IDU. Therefore, tobacco and drug control efforts should target these groups to reduce the consequences of risky lifestyles through information, education and communication (IEC) programs.     

Distinct and Atypical Intrinsic and Extrinsic Cell Death Pathways between Photoreceptor Cell Types upon Specific Ablation of Ranbp2 in Cone Photoreceptors

Non-autonomous cell-death is a cardinal feature of the disintegration of neural networks in neurodegenerative diseases, but the molecular bases of this process are poorly understood. The neural retina comprises a mosaic of rod and cone photoreceptors. Cone and rod photoreceptors degenerate upon rod-specific expression of heterogeneous mutations in functionally distinct genes, whereas cone-specific mutations are thought to cause only cone demise. Here we show that conditional ablation in cone photoreceptors of Ran-binding protein-2 (Ranbp2), a cell context-dependent pleiotropic protein linked to neuroprotection, familial necrotic encephalopathies, acute transverse myelitis and tumor-suppression, promotes early electrophysiological deficits, subcellular erosive destruction and non-apoptotic death of cones, whereas rod photoreceptors undergo cone-dependent non-autonomous apoptosis. Cone-specific Ranbp2 ablation causes the temporal activation of a cone-intrinsic molecular cascade highlighted by the early activation of metalloproteinase 11/stromelysin-3 and up-regulation of Crx and CoREST, followed by the down-modulation of cone-specific phototransduction genes, transient up-regulation of regulatory/survival genes and activation of caspase-7 without apoptosis. Conversely, PARP1⁺-apoptotic rods develop upon sequential activation of caspase-9 and caspase-3 and loss of membrane permeability. Rod photoreceptor demise ceases upon cone degeneration. These findings reveal novel roles of Ranbp2 in the modulation of intrinsic and extrinsic cell death mechanisms and pathways. They also unveil a novel spatiotemporal paradigm of progression of neurodegeneration upon cell-specific genetic damage whereby a cone to rod non-autonomous death pathway with intrinsically distinct cell-type death manifestations is triggered by cell-specific loss of Ranbp2. Finally, this study casts new light onto cell-death mechanisms that may be shared by human dystrophies with distinct retinal spatial signatures as well as with other etiologically distinct neurodegenerative disorders.     

Molecular diagnosis of apple virus and viroid pathogens from India

Apple is known to be susceptible to various virus and viroid pathogens. Symptomatic apple cultivars and rootstocks were collected and analyzed by ELISA and then through RT-PCR. The study reports the presence of Apple mosaic virus (ApMV), Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV), Apple chlorotic leaf spot virus (ACLSV), the major apple viruses and Prunus necrotic ringspot virus (PNRSV), a minor apple virus, at the molecular level in India. Apple scar skin viroid (ASSVd) infection was also confirmed at the molecular level. Sporadic incidences of Tomato ringspot virus and Arabis mosaic virus infections were also detected by ELISA in nursery plants.     

The use of biocides to control sulphate‐reducing bacteria in biofilms on mild steel surfaces

Three different types of biocides, viz. formaldehyde (FM), glutaraldehyde (GA) and isothiozolone (ITZ) were used to control planktonic and sessile populations of two marine isolates of sulphate‐reducing bacteria (SRB). The influence of these biocides on the initial attachment of cells to mild steel surfaces, on subsequent biofilm formation and on the activity of hydrogenase enzymes within developed biofilms was evaluated. In the presence of biocides the rate and degree of colonization of mild steel by SRB depended on incubation time, bacterial isolate and the type of biocide used. Although SRB differed in their susceptibility to biocides, for all isolates the biofilm population was more resistant to the treatment than the planktonic population. GA showed highest efficiency in controlling planktonic and sessile SRB compared with the other two biocides. The activity of the enzyme hydrogenase measured in SRB biofilms varied between isolates and with the biocide treatment. No correlation was found between the number of sessile cells and hydrogenase activity.