Modulation of Ah receptor and CYP1A1 expression by alpha-naphthoflavone in rainbow trout hepatocytes

The objective of this study was to evaluate whether alpha-naphthoflavone (ANF) modulates aryl hydrocarbon receptor (AhR) signaling in rainbow trout (Oncorhynchus mykiss). AhR and cytochrome P450 1A1 (CYP1A1) protein and mRNA content were used as indictors of AhR signaling. Primary culture of rainbow trout hepatocytes were exposed to different concentrations of ANF (10(-9)-10(-5) M), while beta-naphthoflavone (BNF 10(-10)-10(-6) M) and a combination of ANF and BNF were used to elucidate the impact of ANF on AhR signaling. ANF increased AhR and CYP1A1 protein expression in a concentration-related manner; the maximal induction was about 50% that of BNF. Despite the differences in protein content between ANF and BNF stimulation, the maximal AhR and CYP1A1 mRNA abundance seen with the high concentrations of ANF and BNF were similar. ANF significantly decreased ( approximately 50%) BNF-induced AhR protein expression (only at 10(-9) M), but not CYP1A1 protein and gene expression. In addition, ANF at a sub-maximal concentration (10(-7) M) did not affect BNF-induced AhR protein content, but increased the sensitivity of hepatocytes to BNF-mediated CYP1A1 protein expression. Taken together, the mode of action of ANF appears similar to BNF, including modulation of AhR expression and activation of AhR-mediated signaling in rainbow trout hepatocytes. Overall, ANF is not only a partial AhR agonist, but may also modify BNF-mediated AhR signaling in trout hepatocytes.     

X-ray analysis of Mycobacterium smegmatis Dps and a comparative study involving other Dps and Dps-like molecules

The structure of the DNA binding protein from starved cells from Mycobacterium smegmatis has been determined in three crystal forms and has been compared with those of similar proteins from other sources. The dodecameric molecule can be described as a distorted icosahedron. The interfaces among subunits are such that the dodecameric molecule appears to have been made up of stable trimers. The situation is similar in the proteins from Escherichia coli and Agrobacterium tumefaciens, which are closer to the M.smegmatis protein in sequence and structure than those from other sources, which appear to form a dimer first. Trimerisation is aided in the three proteins by the additional N-terminal stretches that they possess. The M.smegmatis protein has an additional C-terminal stretch compared to other related proteins. The stretch, known to be involved in DNA binding, is situated on the surface of the molecule. A comparison of the available structures permits a delineation of the rigid and flexible regions in the molecule. The subunit interfaces around the molecular dyads, where the ferroxidation centres are located, are relatively rigid. Regions in the vicinity of the acidic holes centred around molecular 3-fold axes, are relatively flexible. So are the DNA binding regions. The crystal structures of the protein from M.smegmatis confirm that DNA molecules can occupy spaces within the crystal without disturbing the arrangement of the protein molecules. However, contrary to earlier suggestions, the spaces do not need to be between layers of protein molecules. The cubic form provides an arrangement in which grooves, which could hold DNA molecules, criss-cross the crystal.     

Phenotypic and molecular typing of Vibrio harveyi isolates and their pathogenicity to tiger shrimp larvae

AIMS: The objective of the present study was to identify the biotype(s) and molecular type(s) of Vibrio harveyi associated with pathogenicity in tiger shrimp (Penaeus monodon) larvae. METHODS AND RESULTS: Five luminescent and four nonluminescent V. harveyi isolates were subjected to phenotyping and random amplified polymorphic DNA (RAPD) fingerprinting, and pathogenicity testing to P. monodon mysis. Four isolates induced 34-41% mortality of P. monodon mysis when challenged at the rate of 10(6) CFU ml(-1) within 60 h. Sucrose-fermenting biotypes of V. harveyi appeared to be associated with pathogenicity to larval shrimp. Higher temperature and salinity appeared to play a role on the onset of vibriosis and mortality in the challenged larval shrimp. Pathogenic isolates of V. harveyi could be demarcated as revealed by their clustering in the dendrogram constructed based on the RAPD fingerprints. CONCLUSIONS: Nonluminescent V. harveyi also appear to be important aetiological agents of vibriosis of shrimp larvae. Sucrose-fermenting biotypes are likely to be pathogenic. High temperature may trigger onset of vibriosis. SIGNIFICANCE AND IMPACT OF THE STUDY: Biotyping of V. harveyi isolates and looking for traits, such as ability to ferment sucrose may be helpful in identifying the pathogenic forms, and such approach requires to be investigated further with larger number of isolates.     

Neuroprotective Effect of Natural Products Against Alzheimer’s Disease

Nature has gifted mankind with a plethora of flora-bearing fruits, vegetables and nuts. The diverse array of bioactive nutrients present in these natural products plays a pivotal role in prevention and cure of various neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease and other neuronal dysfunctions. Accumulated evidence suggests that naturally occurring phyto-compounds, such as polyphenolic antioxidants found in fruits, vegetables, herbs and nuts, may potentially hinder neurodegeneration, and improve memory and cognitive function. Nuts such as walnut have also demonstrated neuroprotective effect against AD. The molecular mechanisms behind the curative effects rely mainly on the action of phytonutrients on distinct signalling pathways associated with protein folding and neuroinflammation. The neuroprotective effects of various naturally occurring compounds in AD is evaluating in this review.     

First report of Perkinsus beihaiensis in Crassostrea madrasensis from the Indian subcontinent

Protozoan parasites of the genus Perkinsus are considered important pathogens responsible for mass mortalities in many wild and farmed bivalve populations. The present study was initiated to screen populations of the Indian edible oyster Crassostrea madrasensis, a promising candidate for aquaculture along the Indian coasts, for the presence of Perkinsus spp. The study reports the presence of P. beihaiensis for the first time in C. madrasensis populations from the Indian subcontinent and south Asia. Samples collected from the east and west coasts of India were subjected to Ray's fluid thioglycollate medium (RFTM) culture and histology which indicated the presence of Perkinsus spp. PCR screening of the tissues using specific primers amplified the product specific to the genus Perkinsus. The taxonomic affinities of the parasites were determined by sequencing both internal transcribed spacer (ITS) and actin genes followed by basic local alignment search tool (BLAST) analysis. Analysis based on the ITS sequences showed 98 to 100% identity to Perkinsus spp. (P. beihaiensis and Brazilian Perkinsus sp.). The pairwise genetic distance values and phylogenetic analysis confirmed that 2 of the present samples belonged to the P. beihaiensis clade while the other 4 showed close affinities with the Brazilian Perkinsus sp. clade. The genetic divergence data, close affinity with the Brazilian Perkinsus sp., and co-existence with P. beihaiensis in the same host species in the same habitat show that the remaining 4 samples exhibit some degree of variation from P. beihaiensis. As expected, the sequencing of actin genes did not show any divergence among the samples studied. They probably could be intraspecific variants of P. beihaiensis having a separate lineage in the process of evolution.     

Aquaculture related invasion of the exotic <Emphasis Type="Italic">Artemia franciscana</Emphasis> and displacement of the autochthonous <Emphasis Type="Italic">Artemia</Emphasis> populations from the hypersaline habitats of India

Autochthonous parthenogentic Artemia populations have been reported from Indian hypersaline habitats since 1950s. Exotic Artemia franciscana was imported and introduced into India as live food for aquaculture since the early eighties. To assess the present status of the Artemia populations and the possibility of invasion by the introduced A. franciscana in Indian Salinas, an extensive study was conducted using conventional and molecular approaches. Morphological and biometric observations, crossbreeding experiments and molecular and phylogenetic analysis using Internally Transcribed Spacer-1 sequence revealed the extensive presence of alien, sexual A. franciscana populations in various hypersaline areas. Individual culture experiments and crossbreeding studies further confirmed the absence of autochthonous parthenogentic Artemia populations. Lack of regional endemism in populations of distant origins was evident, indicating that the invaded populations have naturalized and are in the process of evolution. This forms the first report of invasion by A. franciscana in hypersaline habitats of Indian subcontinent and further studies are required to assess the biological implications of this invasion.     

Glomerella truncata: another Glomerella species with an atypical mating system

In the genus Glomerella all species studied to date do not fit the usual mating system of heterothallic ascomycetes. This study investigated the mating system of G. truncata (anamorph Colletotrichum truncatum), a pathogen responsible for lentil anthracnose. Twenty-two field isolates from the Canadian prairies were crossed in all possible combinations, including selfings. All isolates also were screened for the presence of the MAT1-1 and MAT1-2 idiomorphs by targeting small conserved areas of the MAT genes (the alpha domain and the high mobility group HMG box) with degenerate primers, and a pair of G. truncata-specific HMG primers (CT21HMG) were designed. The results of the classical mating study suggested that G. truncata is heterothallic. Isolates fell into two incompatibility groups, which is consistent with a bipolar mating system but different from what has been described in other Glomerella species. Molecular screening showed that the HMG box used as a marker for the MAT1-2 idiomorph was present in both partners of fertile crosses in G. truncata, unlike in the typical ascomycete system, but as previously described for two other Glomerella species. G. truncata therefore appears to share unusual mating system characteristics with the other Glomerella species studied to date.     

Wolbachia heat shock protein 60 induces pro-inflammatory cytokines and apoptosis in monocytes in vitro

Recombinant Wolbachia heat shock protein 60 (rWmhsp60) induces gene expression of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α in human monocytic cell line THP-1. In addition, it inhibits the phagocytic activity and does not alter the nitric oxide production by differentiated THP-1 macrophages, which corroborates with no significant change in inducible nitric oxide synthase gene expression in rWmhsp60 treated THP-1 monocytes. Further, 24 h stimulation of peripheral blood mononuclear cells from normal individuals by rWmhsp60 reveals that monocytes enter the late apoptotic stage, while lymphocytes do not show apoptosis. Thus these findings suggest that rWmhsp60 may contribute to inflammation mediated monocyte dysfunction in filarial pathogenesis.