Freshwater fish biodiversity in the River Ganga (India): changing pattern, threats and conservation perspectives

The river Ganges is the largest river in India and the fifth longest in the world. Although, many studies on fish ecology and systematic have been conducted largely to improve fisheries but fish diversity and their distribution pattern from conservation point of view have never been adequately addressed in the Ganges. In this connection, current distribution and abundance of freshwater fishes of river Ganges was studied and assessed from April 2007 to March 2009. We documented and described 143 freshwater fish species in the all stretches of the river which is higher than what was reported earlier. Some species were observed with shift in their distribution ranges. First time, a total of 10 exotic fishes, including Pterygoplichthys anisitsi, which has never been reported from India found in the Ganges. Alterations of the hydrological pattern due to various types of hydro projects was seems to be the largest threat to fishes of Ganges. Indiscriminate and illegal fishing, pollution, water abstraction, siltation and invasion of exotic species are also threatening the fish diversity in the Ganges and as many as 29 species are listed under threatened category. The study advocates a need to identify critical fish habitats in the Ganga basin to declare them as conservation reserves to mitigate the loss of fish diversity from this mighty large river.     

POT1b protects telomeres from end-to-end chromosomal fusions and aberrant homologous recombination

POT1 (protection of telomere 1) is a highly conserved single-stranded telomeric binding protein that is essential for telomere end protection. Here, we report the cloning and characterization of a second member of the mouse POT family. POT1b binds telomeric DNA via conserved DNA binding oligonucleotide/oligosaccharide (OB) folds. Compared to POT1a, POT1b OB-folds possess less sequence specificity for telomeres. In contrast to POT1a, truncated POT1b possessing only the OB-folds can efficiently localize to telomeres in vivo. Overexpression of a mutant Pot1b allele that cannot bind telomeric DNA initiated a DNA damage response at telomeres that led to p53-dependent senescence. Furthermore, a reduction of the 3' G-rich overhang, increased chromosomal fusions and elevated homologous recombination (HR) were observed at telomeres. shRNA mediated depletion of endogenous Pot1b in Pot1a deficient cells resulted in increased chromosomal aberrations. Our results indicate that POT1b plays important protective functions at telomeres and that proper maintenance of chromosomal stability requires both POT proteins.     

Anti-apoptotic activity of caffeic acid, ellagic acid and ferulic acid in normal human peripheral blood mononuclear cells: a Bcl-2 independent mechanism

Polyphenols have been shown to induce apoptosis in a variety of tumor cells including leukemia both in vitro and in vivo. However, their action on normal human peripheral blood mononuclear cells (PBMCs) during oxidative stress remains to be explored. In this study, we have evaluated the anti-apoptotic and radical scavenging activities of dietary phenolics, namely caffeic acid (CA), ellagic acid (EA) and ferulic acid (FA). H2O2-induced apoptosis in normal human PBMCs was assayed by phosphotidylserine externalization, nucleosomal damage and DNA fragmentation. Incubation of PBMCs with 5 mM H2O2 led to increased Annexin-V binding to externalized phosphatidyl serine (PS), an event of pre-apoptotic stage of the cell. Peripheral blood mononuclear cells pretreated with phenolics could resist H2O2-induced apoptotic damage. Caffeic acid (60 and 120 microM) and EA (100 and 200 microM) caused no change in externalization of PS, whereas FA (100 and 200 microM) increased externalization of PS in PBMCs treated with H2O2. The effects of phenolics were abolished to a large extent by culturing the PBMCs for 24 h after washing the phenolics from the medium. Inhibitory activities of these phenolics on lipid peroxidation were in the order of EA相似文献   

Synthesis and antibacterial activity of substituted 1,2,3,4-tetrahydropyrazino [1,2-a] indoles

A series of substituted 1,2,3,4-tetrahydropyrazino [1,2-a] indole derivatives have been synthesized and tested against the Gram positive and Gram negative strains of bacteria namely Staphylococcus aureus (MTCCB 737), Salmonella typhi (MTCCB 733), Pseudomonas aeruginosa (MTCCB 741), Streptomyces thermonitrificans (MTCCB 1824) and Escherichia coli (MTCCB 1652). All synthesized compounds showed mild to moderate activity. However, compounds 4d-f were found to have potent activity against pathogenic bacteria used in the study. Their MIC ranged from 3.75 to 60 microg/disc. In vitro toxicity tests demonstrated that toxicity of 4d-f was not significantly different than that of gentamycin. However, at higher concentration (1000-4000 microg/ml) difference was highly significant.     

Insight into Poliovirus Genome Replication and Encapsidation Obtained from Studies of 3B-3C Cleavage Site Mutants

A poliovirus (PV) mutant (termed GG), which is incapable of producing 3AB, VPg, and 3CD proteins due to a defective cleavage site between the 3B and 3C proteins, replicated, producing 3BC-linked RNA rather than the VPg-linked RNA produced by the wild type (WT). GG PV RNA is quasi-infectious. The yield of infectious GG PV relative to replicated RNA is reduced by almost 5 logs relative to that of WT PV. Proteolytic activity required for polyprotein processing is normal for the GG mutant. 3BC-linked RNA can be encapsidated as efficiently as VPg-linked RNA. However, a step after genome replication but preceding virus assembly that is dependent on 3CD and/or 3AB proteins limits production of infectious GG PV. This step may involve release of replicated genomes from replication complexes. A pseudorevertant (termed EG) partially restored cleavage at the 3B-3C cleavage site. The reduced rate of formation of 3AB and 3CD caused corresponding reductions in the observed rate of genome replication and infectious virus production by EG PV without impacting the final yield of replicated RNA or infectious virus relative to that of WT PV. Using EG PV, we showed that genome replication and encapsidation were distinct steps in the multiplication cycle. Ectopic expression of 3CD protein reversed the genome replication phenotype without alleviating the infectious-virus production phenotype. This is the first report of a trans-complementable function for 3CD for any picornavirus. This observation supports an interaction between 3CD protein and viral and/or host factors that is critical for genome replication, perhaps formation of replication complexes.Poliovirus (PV) is the most extensively studied member of the picornavirus family and serves as a paradigm not only for picornaviruses but also for many of the nonretroviral positive strand RNA viruses (74). A schematic of the ∼7,500-nucleotide PV genome is shown in Fig. ​Fig.1A.1A. The 5′ end is linked covalently to a 22-amino-acid peptide termed VPg (virion protein genome linked) that is encoded by the 3B region of the genome. VPg and 3B are therefore used interchangeably. The 3′ end of the genome is terminated by a poly(rA) tail. Upon release of the genome into the host cell cytoplasm, genome translation is initiated by using the internal ribosome entry site. An ∼3,000-amino-acid polyprotein is produced. Complete cleavage of the polyprotein by virus-encoded proteases yields 10 proteins. The polyprotein can be divided further into three smaller polyproteins: P1, P2, and P3. P1 contains capsid proteins: VP0, VP3, and VP1. VP0 undergoes autocatalytic cleavage after genome encapsidation to produce VP4 and VP2 proteins. P2 performs host interaction functions required for robust virus multiplication, for example, shutoff of host cell translation and induction of vesicles employed for genome replication, the so-called replication complexes (RCs). P3 contains proteins that function most directly in genome replication, including the RNA-dependent RNA polymerase. Translation induces RCs, leading to genome replication. Early during infection, replicated genomes are employed as templates for translation, leading to an exponential amplification of RCs and replicated RNA. Ultimately, production of viral proteins ceases and replicated genomes are packaged. The use of RCs provides a barrier to genetic complementation; all proteins must be provided in cis, that is, produced from the RNA that they replicate.Open in a separate windowFIG. 1.PV genome organization and P3 processing pathway. (A) Schematic of the PV genome. The 5′ end of the genome is covalently linked to a peptide (VPg) encoded by the 3B region of the genome. The 3′ end contains a poly(rA) tail. Three cis-acting replication elements are known. oriL is located in 5′ NTR. oriR is located in the 3′ NTR. oriI is located in 2C-coding sequence for PV; the position of this element is virus dependent. oriI is the template for VPg uridylylation. Translation initiation employs an internal ribosome entry site (IRES). The single open reading frame encodes a polyprotein. P1 produces virion structural proteins as indicated. P2 produces proteins thought to participate in virus-host interactions required for genome replication. P3 produces proteins thought to participate directly in genome replication. Polyprotein processing is mediated by protease activity residing in 2A, 3C, and/or 3CD proteins. (B) Processing of the P3 precursor occurs by two independent pathways (60). There are major (I) and minor (II) pathways. In pathway I, processing between 3B and 3C yields 3AB and 3CD. In pathway II, processing between 3A and 3B yields 3A and 3BCD. 3BCD processing yields 3BC and 3D; 3BC processing yields 3B and 3C. Pathway II is proposed to function in genome replication and is not perturbed in the GG mutant.In addition to P3 proteins, genome replication requires three cis-acting replication elements (CREs): a cloverleaf structure located in the 5′ nontranslated region (NTR), termed oriL (left) (1, 5); a stem-loop structure located in 2C-coding sequence, termed oriI (internal) (30, 61); and a pseudoknot structure located in the 3′ NTR, termed oriR (right) (1, 40). The first step of genome replication is diuridylylation of VPg or a VPg-containing protein primer (62, 74). This reaction is templated by oriI but also requires oriL in a cell-free reaction and is catalyzed by the viral RNA-dependent RNA polymerase 3Dpol (4, 5, 11, 30, 61). In addition to the four terminal P3 cleavage products (3A, 3B, 3C, and 3D proteins) and the uncleaved P3 polyprotein, several “intermediates” are observed in infected cells (3AB, 3CD, and 3BCD proteins) (Fig. ​(Fig.1B)1B) (43, 57, 73). The major P3 cleavage pathway (I) produces 3AB and 3CD proteins; the minor P3 cleavage pathway (II) produces 3A and 3BCD proteins (Fig. ​(Fig.1B)1B) (60). In some cases, the intermediates have unique activities, specificities, and/or functions relative to their corresponding terminal cleavage products.Over the past 8 years much has been learned about oriI-templated VPg uridylylation in vitro for a variety of picornaviruses (28, 49, 53, 77, 92). However, it is still unclear whether or not VPg, 3BC(D), or 3AB is used in vivo to initiate genome replication. The VPg peptide can be uridylylated in vitro (62); however, VPg-pUpU does not chase efficiently into full-length RNA (81). 3BC(D) is uridylylated more efficiently than VPg in vitro, leading to the possibility that this precursor could be used in vivo (60). To date, 3AB has been uridylylated in vitro only in the presence of Mn²⁺ (66). In order to begin to probe the origin of VPg that is linked to picornaviral RNA, we created a PV mutant in which the cleavage site between 3B and 3C was changed from Gln-Gly to Gly-Gly (60). We refer to this mutant as GG. The GG mutation should be lethal for genome replication if use of the processed VPg peptide is absolutely required for genome replication. For the GG mutant, products of the major P3 cleavage pathway were no longer 3AB and 3CD but were now 3ABC and 3D instead. The kinetics of genome replication were reduced for the GG mutant relative to those for the wild type (WT). Surprisingly, the yield of replicated GG RNA was within an order of magnitude of that observed for WT RNA. Replicated GG RNA was then linked covalently to 3BC instead of VPg, as observed for WT PV. In spite of the substantial yield of replicated RNA, infectious virus was not recovered.We have performed a molecular characterization of the GG mutant. GG PV RNA is quasi-infectious. The low yield of virus recovery relative to replicated RNA reflects a block at a step in the PV multiplication cycle positioned after genome replication but prior to virus assembly. The existence of this step in the PV life cycle was suggested previously by Baltimore (8). Surprisingly, none of the defects associated with GG PV could be attributed to the absence of 3CD protease activity, suggesting that precursors larger than 3CD may be the primary proteases employed in vivo. All of the observed defects in GG PV multiplication were ameliorated in a pseudorevertant in which the 3B-3C cleavage site was changed from Gly-Gly to Glu-Gly. This mutant is referred to as EG. Molecular characterization of EG PV revealed for the first time a trans-complementable function for 3CD in genome replication. This observation supports a role for 3CD at a step preceding genome replication within RCs, perhaps RC formation. Our studies of EG PV confirmed the existence of a step between genome replication and virus assembly that requires 3CD and/or 3AB, thus providing compelling evidence for genome replication and genome encapsidation as distinct steps in the multiplication cycle. This study highlights the utility of polyprotein cleavage site mutants for evaluation of the viral multiplication cycle.