Whale Sharks,Rhincodon typus,Aggregate around Offshore Platforms in Qatari Waters of the Arabian Gulf to Feed on Fish Spawn

Whale sharks, Rhincodon typus, are known to aggregate to feed in a small number of locations in tropical and subtropical waters. Here we document a newly discovered major aggregation site for whale sharks within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. Whale sharks were observed between April and September, with peak numbers observed between May and August. Density estimates of up to 100 sharks within an area of 1 km² were recorded. Sharks ranged between four and eight metres’ estimated total length (mean 6.92±1.53 m). Most animals observed were actively feeding on surface zooplankton, consisting primarily of mackerel tuna, Euthynnus affinis, eggs.     

Bromo-deaza-SAH: A potent and selective DOT1L inhibitor

Chemical inhibition of proteins involved in chromatin-mediated signaling is an emerging strategy to control chromatin compaction with the aim to reprogram expression networks to alter disease states. Protein methyltransferases constitute one of the protein families that participate in epigenetic control of gene expression, and represent a novel therapeutic target class. Recruitment of the protein lysine methyltransferase DOT1L at aberrant loci is a frequent mechanism driving acute lymphoid and myeloid leukemias, particularly in infants, and pharmacological inhibition of DOT1L extends survival in a mouse model of mixed lineage leukemia. A better understanding of the structural chemistry of DOT1L inhibition would accelerate the development of improved compounds. Here, we report that the addition of a single halogen atom at a critical position in the cofactor product S-adenosylhomocysteine (SAH, an inhibitor of SAM-dependent methyltransferases) results in an 8-fold increase in potency against DOT1L, and reduced activities against other protein and non-protein methyltransferases. We solved the crystal structure of DOT1L in complex with Bromo-deaza-SAH and rationalized the observed effects. This discovery reveals a simple strategy to engineer selectivity and potency towards DOT1L into the adenosine scaffold of the cofactor shared by all methyltransferases, and can be exploited towards the development of clinical candidates against mixed lineage leukemia.     

DAZL 260A > G and MTHFR 677C > T variants in sperm DNA of infertile Indian men

DAZL (deleted in azoospermia-like) 260A > G and MTHFR (methylene tetrahydrofolate reductase) 677C > T are two important autosomal variants associated with impaired spermatogenesis. In this study, we investigated DAZL 260A > G and MTHFR 677C > T variants in sperm DNA and their frequency in oligozoospermic infertile men of Indian origin. The study on sperm DNA was performed, since it is more prone to oxidative stress-induced damage and mutation. One hundred oligozoopsermic infertile men having normal chromosomal complement with intact Y chromosome and 100 age- and ethnically-matched fertile controls were investigated for these variants in their sperm genome. Spermatozoa were separated by gradient centrifugation and DNA was isolated and analyzed for the single nucleotide polymorphisms (SNPs) by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). The results showed no significant differences in the frequency of DAZL AG (P = 0.58) and MTHFR CT (P = 0.44) between oligozoospermic infertile men and controls. However, 8% (8/100) oligozoospermic infertile men harbored both the variants and showed significantly (P < 0.0001) lower sperm count (3.28 +/- 1.1 vs 12.50 +/- 4.09) compared to infertile men with either of the single variant. None of the fertile controls showed the presence of the both variants. In conclusion, the combined effect of both DAZL 260A > G and MTHFR 677C > T variants may have role in compromised sperm count. However, further studies are required to find the pathological role of these combined variants in male infertility.     

Tissue culture of the alternate hosts of wheat,rye and oat rusts and their response to in vitro inoculation with the rust pathogens

Alternate host plants of cereal rust fungi are necessary for studying the rust sexual cycle and pathogenicity. These plants are usually difficult to propagate through cloning, while seed-propagated plants may have variable responses to the pathogen. To overcome these obstacles, tissue culture, under controlled and aseptic conditions, was utilized for clonal propagation and in vitro inoculation of the following species: Rhamnus palaestinus Boiss., the alternate host of oat (Avena spp.) crown rust (Puccinia coronata Corda); Thalictrum speciosissimum L., the alternate host of brown leaf rust of wheat (Puccinia recondita f. sp. tritici Eriks. & Henn.); and Lycopsis arvensis L., the alternate host of rye (Secala spp.) leaf rust (Puccinia recondita f. sp. recondita Rob. & Desm.). Shoot culture procedures for initial establishment and proliferation were developed for all three alternate host species. Shoot cultures were multiplied at rates ranging from 0.3 to 1.7 shoots/week. Successful infection following inoculation with teliospores of the corresponding rust fungi was obtained for R. palaestinus and T. speciosissimum but not for L. arvensis. The hardening and acclimatization efficiency of rooted T. speciosissimum and L. arvensis was of 80–90%. The propagation efficiency for R. palaestinus was not successful because of the low rate and poor quality of its rooting. It is concluded that the in vitro system might be used as an alternative method for inoculation and multiplication of alternate hosts of cereal rusts, although more experimentation is needed to define accurately the appropriate conditions for the proper infection response. This revised version was published online in June 2006 with corrections to the Cover Date.     

The F gene of rodent brain-adapted mumps virus is a major determinant of neurovirulence

Prior to the introduction of live-attenuated vaccines, mumps virus (MuV) was the leading cause of virus-induced meningitis. Although vaccination has been effective at controlling the disease, the use of insufficiently attenuated strains has been associated with high rates of aseptic meningitis in vaccinees. The molecular basis of MuV attenuation is poorly understood, and no reliable molecular markers of virulence have been identified. In this study, reverse genetics has been used to identify molecular determinants of MuV neuropathogenesis. Recombinant viruses, containing the envelope-associated genes from the Kilham (MuV(KH)) rodent brain-adapted strain of MuV, were generated in the Jeryl Lynn 5 (MuV(JL5)) vaccine strain background. The syncytium phenotypes of the recombinant viruses on Vero cells differed depending on the source of the fusion (F) and hemagglutinin-neuraminidase (HN) glycoproteins, with heterologous combinations showing either an increase or a decrease in the level of cell fusion compared to that of the homologous parental combinations. This was confirmed by transiently cotransfecting eukaryotic F and HN glycoprotein expression constructs. A Lewis rat model that discriminates between neurovirulent and nonneurovirulent MuV strains based on the extent of hydrocephalus induced in the rat brain after intracerebral inoculation was used to assess the phenotype of the recombinant viruses. Expression of the matrix (M), small hydrophobic (SH), or HN gene in isolation did not confer a neurovirulent phenotype. Expression of the F gene of the neurovirulent strain alone was sufficient to induce significant levels of hydrocephalus. Coexpression of the homologous HN gene led to a marginal increase in the level of hydrocephalus.     

Development of a challenge-protective vaccine concept by modification of the viral RNA-dependent RNA polymerase of canine distemper virus

We demonstrate that insertion of the open reading frame of enhanced green fluorescent protein (EGFP) into the coding sequence for the second hinge region of the viral L (large) protein (RNA-dependent RNA polymerase) attenuates a wild-type canine distemper virus. Moreover, we show that single intranasal immunization with this recombinant virus provides significant protection against challenge with the virulent parental virus. Protection against wild-type challenge was gained either after recovery of cellular immunity postimmunization or after development of neutralizing antibodies. Insertion of EGFP seems to result in overattenuation of the virus, while our previous experiments demonstrated that the insertion of an epitope tag into a similar position did not affect L protein function. Thus, a desirable level of attenuation could be reached by manipulating the length of the insert (in the second hinge region of the L protein), providing additional tools for optimization of controlled attenuation. This strategy for controlled attenuation may be useful for a “quick response” in vaccine development against well-known and “new” viral infections and could be combined efficiently with other strategies of vaccine development and delivery systems.     

Isolation of polymer-degrading bacteria and characterization of the hindgut bacterial community from the detritus-feeding larvae of Tipula abdominalis (Diptera: Tipulidae)

The Tipula abdominalis larval hindgut microbial community presumably facilitates digestion of the lignocellulosic diet. The microbial community was investigated through characterization of bacterial isolates and analysis of 16S rRNA gene clone libraries. This initial study revealed novel bacteria and provides a framework for future studies of this symbiosis.     

Cationic penetrating antioxidants switch off Mn cluster of photosystem II in situ

Photosynthesis Research - Photosystem I (PSI) generates the most negative redox potential found in nature, and the performance of solar energy conversion into alternative energy sources in...