A virion-associated protein kinase induces apoptosis

Apoptosis and inhibition of host gene expression are often associated with virus infections. Many viral polypeptides modulate apoptosis by direct interaction with highly conserved apoptotic pathways. Some viruses induce apoptosis during late stages of the infection cycle, while others inhibit apoptosis to facilitate replication or maintain persistent infection. In previous work, we showed that Chilo iridescent virus (CIV) or CIV virion protein extract induces apoptosis in spruce budworm and cotton boll weevil cell cultures. Here, we characterize the product of a CIV gene (iridovirus serine/threonine kinase; istk) with signature sequences for S/T kinase and ATP binding. ISTK appears to belong to the superfamily, vaccinia-related kinases (VRKs). The istk gene was expressed in Pichia pastoris vectors. Purified ISTK (48 kDa) exhibited S/T kinase activity. Treatment with ISTK induced apoptosis in budworm cells. A 35-kDa cleavage product of ISTK retaining key signature sequences was identified during purification. Pichia-expressed 35-kDa polypeptide, designated iridoptin, induced apoptosis and inhibition of host protein synthesis in budworm and boll weevil cells. A mutation in the ATP-binding site eliminated both kinase and apoptosis activity of iridoptin, suggesting that kinase activity is essential for induction of apoptosis. Analysis with custom antibody confirmed that ISTK is a structural component of CIV particles. This is the first demonstration of a viral kinase inducing apoptosis in any virus-host system and the first identification of a factor inducing apoptosis or host protein shutoff for the family Iridoviridae.     

Comic woman,victim woman: Pushing gender and genre boundaries in popular Hindi Cinema

“Women's film” in Hollywood is associated both with the genre of melodrama, the “weepie”, and with female spectatorship. In the Indian context of popular Hindi cinema, first, genre analysis itself is a questionable line of inquiry since several genres, the melodrama, musical, gangster, or mystery, combine in a single film, known locally as the masala (spicy) film; and second, films are scarcely divided by a gendered viewership. Yet I identify “women's films” as a distinct category in Hindi cinema, emerging around the ‘70s. These women's films typically center on female protagonists, dramatize their victimization and vindication; by the ‘80s under a range of influences these films mutated into rape‐revenge narratives.

However, another strain emerged within the ‘70s’ “women's film,” which drew on cinema's rich visual iconographic tradition of the sight gag, promulgating the comedic/tomboy heroine figure. It favored laughing and mocking patriarchal structures rather than surrendering to them in tears. Focusing on Ramesh Sippy's Sita aur Gita [1972] emblematic of this trend I explore theoretical concerns about associating genres with gender. In keeping with recent poststructuralist theories about gender and media ‘consumption I show how the film destabilized clear‐cut gender identification and stood for a promising trend that was sadly undercut. Thus, while genre might still be a useful analytical tool for Hindi cinema, defining women's film as female‐centered narratives is a viable category as long as we appreciate the instability in gendered viewer identification.     

Molecular and biochemical characterization of urease and survival of Yersinia enterocolitica biovar 1A in acidic pH in vitro

Background  

Yersinia enterocolitica, an important food- and water-borne enteric pathogen is represented by six biovars viz. 1A, 1B, 2, 3, 4 and 5. Despite the lack of recognized virulence determinants, some biovar 1A strains have been reported to produce disease symptoms resembling that produced by known pathogenic biovars (1B, 2-5). It is therefore imperative to identify determinants that might contribute to the pathogeniCity of Y. enterocolitica biovar 1A strains. Y. enterocolitica invariably produces urease and the role of this enzyme in the virulence of biovar 1B and biovar 4 strains has been reported recently. The objective of this work was to study genetic organization of the urease (ure) gene complex of Y. enterocolitica biovar 1A, biochemical characterization of the urease, and the survival of these strains under acidic conditions in vitro.     

Emerging water-borne pathogens

Emerging water-borne pathogens constitute a major health hazard in both developed and developing nations. A new dimension to the global epidemiology of cholera-an ancient scourge-was provided by the emergence of Vibrio cholerae O139. Also, water-borne enterohaemorrhagic Escherichia coli ( E. coli O157:H7), although regarded as a problem of the industrialized west, has recently caused outbreaks in Africa. Outbreaks of chlorine-resistant Cryptosporidium have motivated water authorities to reassess the adequacy of current water-quality regulations. Of late, a host of other organisms, such as hepatitis viruses (including hepatitis E virus), Campylobacter jejuni, microsporidia, cyclospora, Yersinia enterocolitica, calciviruses and environmental bacteria like Mycobacterium spp, aeromonads, Legionella pneumophila and multidrug-resistant Pseudomonas aeruginosa have been associated with water-borne illnesses. This review critically examines the potential of these as emerging water-borne pathogens. It also examines the possible reasons, such as an increase in the number of immunocompromised individuals, urbanization and horizontal gene transfer, that may underlie their emergence. Further, measures required to face the challenge posed by these pathogens are also discussed.     

Distribution of virulence-associated genes in Yersinia enterocolitica biovar 1A correlates with clonal groups and not the source of isolation

Yersinia enterocolitica, an important food- and water-borne enteric pathogen, is represented by six biovars viz. 1A, 1B and 2-5. Some biovar 1A strains, despite lacking virulence plasmid (pYV) and chromosomal virulence genes, have been reported to cause symptoms similar to that produced by isolates belonging to known pathogenic biovars. Virulence-associated genes viz. ail, virF, inv, myfA, ystA, ystB, ystC, tccC, hreP, fepA, fepD, fes, ymoA and sat were studied in 81 clinical and nonclinical strains of Y. enterocolitica biovar 1A by PCR amplification. All strains lacked ail, virF, ystA and ystC genes. The distribution of other genes with respect to clonal groups revealed that four genes viz. ystB, hreP, myfA and sat were associated exclusively with strains belonging to clonal group A. The clonal groups A and B were differentiated previously based on rep (REP-/ERIC) - PCR genomic fingerprinting. The distribution of virulence-associated genes, however, did not differ significantly between clinical and nonclinical strains. In strains of Y. enterocolitica biovar 1A, clonal groups seem to reflect virulence potential better than the source (clinical vs. nonclinical) of isolation.     

Characteristics of β-lactamases and their genes (<Emphasis Type="Italic">blaA</Emphasis> and <Emphasis Type="Italic">blaB</Emphasis>) in <Emphasis Type="Italic">Yersinia intermedia</Emphasis> and <Emphasis Type="Italic">Y. frederiksenii</Emphasis>

Background  

The presence of β-lactamases in Y. enterocolitica has been reported to vary with serovars, biovars and geographical origin of the isolates. An understanding of the β-lactamases in other related species is important for an overall perception of antibiotic resistance in yersiniae. The objective of this work was to study the characteristics of β-lactamases and their genes in strains of Y. intermedia and Y. frederiksenii, isolated from clinical and non-clinical sources in India.     

In vitro antibiotic susceptibilities of Yersinia enterocolitica biotype 1A

Antibiotic susceptibilities of 80 strains of Yersinia enterocolitica biotype 1A isolated from human, swine and various aquatic sources to 20 β-lactam and 26 non-β-lactam antibiotics were studied. Most isolates were resistant to penicillins, first-generation cephalosporins, macrolides and lincosamides, while sensitive to aminoglycosides and quinolones. In comparison to earlier studies, the majority of the strains were either intermediately sensitive or resistant to piperacillin. Relatively decreased susceptibility or resistance to third-generation cephalosporins was also observed in several Y. enterocolitica isolates. This revised version was published online in August 2006 with corrections to the Cover Date.     

MutS HOMOLOG1 is a nucleoid protein that alters mitochondrial and plastid properties and plant response to high light

Mitochondrial-plastid interdependence within the plant cell is presumed to be essential, but measurable demonstration of this intimate interaction is difficult. At the level of cellular metabolism, several biosynthetic pathways involve both mitochondrial- and plastid-localized steps. However, at an environmental response level, it is not clear how the two organelles intersect in programmed cellular responses. Here, we provide evidence, using genetic perturbation of the MutS Homolog1 (MSH1) nuclear gene in five plant species, that MSH1 functions within the mitochondrion and plastid to influence organellar genome behavior and plant growth patterns. The mitochondrial form of the protein participates in DNA recombination surveillance, with disruption of the gene resulting in enhanced mitochondrial genome recombination at numerous repeated sequences. The plastid-localized form of the protein interacts with the plastid genome and influences genome stability and plastid development, with its disruption leading to variegation of the plant. These developmental changes include altered patterns of nuclear gene expression. Consistency of plastid and mitochondrial response across both monocot and dicot species indicate that the dual-functioning nature of MSH1 is well conserved. Variegated tissues show changes in redox status together with enhanced plant survival and reproduction under photooxidative light conditions, evidence that the plastid changes triggered in this study comprise an adaptive response to naturally occurring light stress.