Comparison of 16S rRNA gene sequences of genus Methanobrevibacter

BACKGROUND: The phylogeny of the genus Methanobrevibacter was established almost 25 years ago on the basis of the similarities of the 16S rRNA oligonucleotide catalogs. Since then, many 16S rRNA gene sequences of newly isolated strains or clones representing the genus Methanobrevibacter have been deposited. We tried to reorganize the 16S rRNA gene sequences of this genus and revise the taxonomic affiliation of the isolates and clones representing the genus Methanobrevibacter. RESULTS: The phylogenetic analysis of the genus based on 786 bp aligned region from fifty-four representative sequences of the 120 available sequences for the genus revealed seven multi-member groups namely, Ruminantium, Smithii, Woesei, Curvatus, Arboriphilicus, Filiformis, and the Termite gut symbionts along with three separate lineages represented by Mbr. wolinii, Mbr. acididurans, and termite gut flagellate symbiont LHD12. The cophenetic correlation coefficient, a test for the ultrametric properties of the 16S rRNA gene sequences used for the tree was found to be 0.913 indicating the high degree of goodness of fit of the tree topology. A significant relationship was found between the 16S rRNA sequence similarity (S) and the extent of DNA hybridization (D) for the genus with the correlation coefficient (r) for logD and logS, and for [ln(-lnD) and ln(-lnS)] being 0.73 and 0.796 respectively. Our analysis revealed that for this genus, when S = 0.984, D would be <70% at least 99% of the times, and with 70% D as the species "cutoff", any 16S rRNA gene sequence showing <98% sequence similarity can be considered as a separate species. In addition, we deduced group specific signature positions that have remained conserved in evolution of the genus. CONCLUSIONS: A very significant relationship between D and S was found to exist for the genus Methanobrevibacter, implying that it is possible to predict D from S with a known precision for the genus. We propose to include the termite gut flagellate symbiont LHD12, the methanogenic endosymbionts of the ciliate Nyctotherus ovalis, and rat feces isolate RT reported earlier, as separate species of the genus Methanobrevibacter

Short Communication Residence time distribution in the extra capillary space of hollow fiber bioreactors

The residence time distribution (RTD) in the extracapillary space (ECS) of hollow fiber bioreactors (HFBRs) has been studied using a high molecular weight protein, bovine serum albumin, as a tracer. The RTD measurements have been carried out at different conditions of flow in the ECS and the intracapillary space (ICS). The RTD results obtained give an indication of the flow patterns existing in the ECS. The implications of these studies on cell cultivation as well as product recovery from HFBRs have been discussed

Lactobacillus plantarum (VR1) isolated from an Ayurvedic medicine (Kutajarista) ameliorates in vitro cellular damage caused by Aeromonas veronii

<p>Abstract</p> <p>Background</p> <p><it>Lactobacillus plantarum </it>is considered as a safe and effective probiotic microorganism. Among various sources of isolation, traditionally fermented foods are considered to be rich in <it>Lactobacillus </it>spp., which can be exploited for their probiotic attribute. Antibacterial property of <it>L. plantarum </it>has been demonstrated against various enteric pathogens in both <it>in vitro </it>and <it>in vivo </it>systems. This study was aimed at characterizing <it>L. plantarum </it>isolated from Kutajarista, an ayurvedic fermented biomedicine, and assessing its antagonistic property against a common enteropathogen <it>Aeromonas veronii</it>.</p> <p>Results</p> <p>We report the isolation of <it>L. plantarum </it>(VR1) from Kutajarista, and efficacy of its cell free supernatant (CFS) in amelioration of cytotoxicity caused by <it>Aeromonas veronii</it>. On the part of probiotic attributes, VR1 was tolerant to pH 2, 0.3% bile salts and simulated gastric juice. Additionally, VR1 also exhibited adhesive property to human intestinal HT-29 cell line. Furthermore, CFS of VR1 was antibacterial to enteric pathogens like <it>Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli</it>, <it>Aeromonas veronii </it>and clinical isolates of <it>P. aeruginosa </it>and <it>E. coli</it>. Detailed study regarding the effect of VR1 CFS on <it>A. veronii </it>cytotoxicity showed a significant decrease in vacuole formation and detrimental cellular changes in Vero cells. On the other hand, <it>A. veronii </it>CFS caused disruption of tight junction proteins ZO-1 and actin in MDCK cell line, which was prevented by pre-incubation with CFS of VR1.</p> <p>Conclusions</p> <p>This is the first study to report isolation of <it>L. plantarum </it>(VR1) from Kutajarista and characterisation for its probiotic attributes. Our study demonstrates the antagonistic property of VR1 to <it>A. veronii </it>and effect of VR1 CFS in reduction of cellular damage caused by <it>A. veronii </it>in both Vero and MDCK cell lines.</p

Generation, annotation, and analysis of ESTs from midgut tissue of adult female Anopheles stephensi mosquitoes

<p>Abstract</p> <p>Background</p> <p>Malaria is a tropical disease caused by protozoan parasite, <it>Plasmodium</it>, which is transmitted to humans by various species of female anopheline mosquitoes. <it>Anopheles stephensi </it>is one such major malaria vector in urban parts of the Indian subcontinent. Unlike <it>Anopheles gambiae</it>, an African malaria vector, transcriptome of <it>A. stephensi </it>midgut tissue is less explored. We have therefore carried out generation, annotation, and analysis of expressed sequence tags from sugar-fed and <it>Plasmodium yoelii </it>infected blood-fed (post 24 h) adult female <it>A. stephensi </it>midgut tissue.</p> <p>Results</p> <p>We obtained 7061 and 8306 ESTs from the sugar-fed and <it>P. yoelii </it>infected mosquito midgut tissue libraries, respectively. ESTs from the combined dataset formed 1319 contigs and 2627 singlets, totaling to 3946 unique transcripts. Putative functions were assigned to 1615 (40.9%) transcripts using BLASTX against UniProtKB database. Amongst unannotated transcripts, we identified 1513 putative novel transcripts and 818 potential untranslated regions (UTRs). Statistical comparison of annotated and unannotated ESTs from the two libraries identified 119 differentially regulated genes. Out of 3946 unique transcripts, only 1387 transcripts were mapped on the <it>A. gambiae </it>genome. These also included 189 novel transcripts, which were mapped to the unannotated regions of the genome. The EST data is available as ESTDB at <url>http://mycompdb.bioinfo-portal.cdac.in/cgi-bin/est/index.cgi</url>.</p> <p>Conclusion</p> <p>3946 unique transcripts were successfully identified from the adult female <it>A. stephensi </it>midgut tissue. These data can be used for microarray development for better understanding of vector-parasite relationship and to study differences or similarities with other malaria vectors. Mapping of putative novel transcripts from <it>A. stephensi </it>on the <it>A. gambiae </it>genome proved fruitful in identification and annotation of several genes. Failure of some novel transcripts to map on the <it>A. gambiae </it>genome indicates existence of substantial genomic dissimilarities between these two potent malaria vectors.</p

Analysis of Mitochondrial DNA Sequences in Childhood Encephalomyopathies Reveals New Disease-Associated Variants

BACKGROUND: Mitochondrial encephalomyopathies are a heterogeneous group of clinical disorders generally caused due to mutations in either mitochondrial DNA (mtDNA) or nuclear genes encoding oxidative phosphorylation (OXPHOS). We analyzed the mtDNA sequences from a group of 23 pediatric patients with clinical and morphological features of mitochondrial encephalopathies and tried to establish a relationship of identified variants with the disease. METHODOLOGY/PRINCIPLE FINDINGS: Complete mitochondrial genomes were amplified by PCR and sequenced by automated DNA sequencing. Sequencing data was analyzed by SeqScape software and also confirmed by BLASTn program. Nucleotide sequences were compared with the revised Cambridge reference sequence (CRS) and sequences present in mitochondrial databases. The data obtained shows that a number of known and novel mtDNA variants were associated with the disease. Most of the non-synonymous variants were heteroplasmic (A4136G, A9194G and T11916A) suggesting their possibility of being pathogenic in nature. Some of the missense variants although homoplasmic were showing changes in highly conserved amino acids (T3394C, T3866C, and G9804A) and were previously identified with diseased conditions. Similarly, two other variants found in tRNA genes (G5783A and C8309T) could alter the secondary structure of Cys-tRNA and Lys-tRNA. Most of the variants occurred in single cases; however, a few occurred in more than one case (e.g. G5783A and A10149T). CONCLUSIONS AND SIGNIFICANCE: The mtDNA variants identified in this study could be the possible cause of mitochondrial encephalomyopathies with childhood onset in the patient group. Our study further strengthens the pathogenic score of known variants previously reported as provisionally pathogenic in mitochondrial diseases. The novel variants found in the present study can be potential candidates for further investigations to establish the relationship between their incidence and role in expressing the disease phenotype. This study will be useful in genetic diagnosis and counseling of mitochondrial diseases in India as well as worldwide

Detection of conjugation related type four secretion machinery in Aeromonas culicicola

BACKGROUND: Aeromonas sp. can now be considered relatively common enteropathogens due to the increase of diseases in humans. Aeromonas culicicola is a gram negative rod-shaped bacterium isolated for the first time from the mosquito mid-gut, but subsequently detected in other insects and waters also. Our previous study discovered that A. culicicola harbors three plasmids, which we designated as pAc3249A, pAc3249B and pAc3249C. We investigated and report here the existence and genetic organization of a Conjugal Type IV Secretion System (TFSS) in pAc3249A. METHODOLOGY/PRINCIPLE FINDING: The complete operon is 11,061 bp in length and has G+C content of 47.20% code for 12 ORFs. The gene order and orientation were similar to those found in other bacteria with some differences. We have designated this system as AcTra for Aeromonas culicicola transfer system. BLAST results of ORFs and phylogenetic analysis showed significant similarity towards the respective proteins of the IncI2 plasmid R721 of E. coli. Other bioinformatics studies have been performed to predict conserved motifs/domains, signal peptides, transmembrane helices, etc. of the ORFs. CONCLUSIONS/SIGNIFICANCE: BLAST results of ORFs and phylogenetic analysis showed significant similarity towards the respective proteins of the IncI2 plasmid R721 of E. coli

Reduction of vanadate by a microsomal redox system

The reduction of vanadate catalyzed by rat liver microsomes is demonstrated. This reaction is SOD-insensitive. It is specific for NADH and polyvanadate and is not obtained with metavanadate and NADPH

NADH-dependent polyvanadate reduction by microsomes

NADH-dependent redn. of polyvanadate was obsd. by using rat liver microsomes as the enzyme source. The reduced vanadate obtained was blue in color, with a broad absorption max. in the red region at .apprx.650 nm. Microsomes and phosphate anions were essential for polyvanadate redn. The rate and the extent of formation of the blue-colored compd. depended on the amt. of vanadate present. Cytochrome b5 was involved in this superoxide dismutase-insensitive reaction. The rate of disappearance of the blue-colored compd. was dependent on the concn. of NADH and was sensitive to SOD. Catalase and $Mn^{2+}$, which inhibit the O consumption accompanying NADH oxidn., increased both the rate and extent of the blue-colored compd. formed. Vanadate apparently acts an electron acceptor

luxRI homologs are universally present in the genus Aeromonas

BACKGROUND: Aeromonas spp. have been regarded as "emerging pathogens". Aeromonads possess multifactorial virulence and the production of many of these virulence determinants is associated with high cell density, a phenomenon that might be regulated by quorum sensing. However, only two species of the genus are reported to possess the luxRI quorum sensing gene homologs. The purpose of this study was to investigate if the luxRI homologs are universally present in the Aeromonas strains collected from various culture collections, clinical laboratories and field studies. RESULTS: Of all the 73 Aeromonas strains used in the study, seventy-one strains elicited acyl-homoserine lactone-mediated response in multiple biosensor strains. However, dot blot hybridization revealed that the luxRI homologs are present in all the strains. PCR amplification and sequencing revealed that the luxRI homologs shared a very high percentage sequence similarity. No evidence for lateral gene transfer of the luxRI homologs between aeromonads and other genera was noted. CONCLUSION: We propose that the luxRI quorum sensing gene homologs are universally present in the genus Aeromonas independently from their origin. This study is the first genus-wide report of the taxonomic distribution of the luxRI homologs

Noradrenaline treatment of rats stimulates H2O2H_2O_2 generation in liver mitochondria.

Treatment of rats with noradrenaline stimulated $H_20_2$ generation in liver mitochondria using succinate, choline or glycerol 1-phosphate as substrate. The dehydrogenase activity with either succinate or choline as substrate showed no change, whereas that with glycerol 1-phosphate increased. 2. The effect was obtained with noradrenaline, but not with dihydroxyphenylserine. 3. Phenoxybenzamine and yohimbine, but not propranolol, prevented the response to noradrenaline treatment. 4. Phenylephrine could stimulate $H_20_2$ generation, whereas isoprenaline had only a marginal effect. 5. Theophylline treatment slightly decreased the generation of $H_20_2$ in liver mitochondria, but treatment with pargyline, Ro4-1284 and dibutyryl cyclic AMP had little effect. 6. These studies showed that noradrenaline might possibly be acting through the $\alpha_2$-adrenergic system