Structural rearrangements in the membrane penetration protein of a non-enveloped virus

Non-enveloped virus particles (those that lack a lipid-bilayer membrane) must breach the membrane of a target host cell to gain access to its cytoplasm. So far, the molecular mechanism of this membrane penetration step has resisted structural analysis. The spike protein VP4 is a principal component in the entry apparatus of rotavirus, a non-enveloped virus that causes gastroenteritis and kills 440,000 children each year. Trypsin cleavage of VP4 primes the virus for entry by triggering a rearrangement that rigidifies the VP4 spikes. We have determined the crystal structure, at 3.2 A resolution, of the main part of VP4 that projects from the virion. The crystal structure reveals a coiled-coil stabilized trimer. Comparison of this structure with the two-fold clustered VP4 spikes in a approximately 12 A resolution image reconstruction from electron cryomicroscopy of trypsin-primed virions shows that VP4 also undergoes a second rearrangement, in which the oligomer reorganizes and each subunit folds back on itself, translocating a potential membrane-interaction peptide from one end of the spike to the other. This rearrangement resembles the conformational transitions of membrane fusion proteins of enveloped viruses.     

Comparative analyses of multi-species sequences from targeted genomic regions

The systematic comparison of genomic sequences from different organisms represents a central focus of contemporary genome analysis. Comparative analyses of vertebrate sequences can identify coding and conserved non-coding regions, including regulatory elements, and provide insight into the forces that have rendered modern-day genomes. As a complement to whole-genome sequencing efforts, we are sequencing and comparing targeted genomic regions in multiple, evolutionarily diverse vertebrates. Here we report the generation and analysis of over 12 megabases (Mb) of sequence from 12 species, all derived from the genomic region orthologous to a segment of about 1.8 Mb on human chromosome 7 containing ten genes, including the gene mutated in cystic fibrosis. These sequences show conservation reflecting both functional constraints and the neutral mutational events that shaped this genomic region. In particular, we identify substantial numbers of conserved non-coding segments beyond those previously identified experimentally, most of which are not detectable by pair-wise sequence comparisons alone. Analysis of transposable element insertions highlights the variation in genome dynamics among these species and confirms the placement of rodents as a sister group to the primates.     

Hemicastration-induced changes in the electrophoretic pattern of some enzymes in the brain of the skink,Mabuya carinata

Summary Hemicastration in the skink induces change in the electrophoretic pattern of some enzymes like LDH, MDH, acid phosphatase and esterases.The authors wish to thank Prof. N.B. Krishnamurthy for his encouragment, UGC, New Delhi for their financial help to DTP and SM, and CSIR, New Delhi for MR.     

Allelopathy in spring wheat mixtures

Summary In a study with binary mixtures of 3 spring wheat cultivars harmful effects due to allelopathy were observed on root number, root growth and fresh weight of the seedlings.We thank Director, I.A.R.I. for facilities and encouragement.     

Effect of sodium butyrate in combination with prostaglandin E1 and inhibitors of cyclic nucleotide phosphodiesterase on human amelanotic melanoma cells in culture

Summary Sodium butyrate and cyclic AMP-stimulating agents (prostaglandin E₁, papaverine, theophylline, and RO20-1724) caused reductions in the cell number (primarily due to reduction in cell division) when added individually to human melanoma cells in culture. However, the combination of sodium butyrate with one of the cyclic AMP-stimulating agents produced a marked reduction in cell number (primarily due to cell death).Supported in part by BRSG grant RR-05357 awarded by Biomedical Research Support Grant Program, Division of Research Resources, National Institutes of Health. We thank Marianne Gaschler for her technical help.