Narayan Chandra Talukdar

Gut bacterial diversity of the tribes of India and comparison with the worldwide data

The gut bacteria exert phenotypic traits to the host but the factors which determine the gut bacterial profile (GBP) is poorly understood. This study aimed to understand the effect of ethnicity and geography on GBP of Mongoloid and Proto-Australoid tribes of India. Fecal bacterial diversity was studied in fifteen tribal populations representing four geographic regions (Assam, Telangana, Manipur and Sikkim) by DGGE followed by NGS analysis on Illumina MiSeq platform. Geography and diet had significant effect on GBP of the Indian tribes which was dominated by Prevotella. The effects were more prominent with lower taxonomic levels, indicating probable functional redundancy of the core GBP. A comparison with the worldwide data revealed that GBP of the Indian population was similar to the Mongolian population (Mongolia). The bacterial genera Faecalibacterium, Eubacterium, Clostridium, Blautia, Ruminococcus and Roseburia were found to be core genera in the representative populations of the world.

Erratum: Secretome weaponries of Cochliobolus lunatus interacting with potato leaf at different temperature regimes reveal a CL[xxxx]LHM - motif.

BackgroundPlant and animal pathogenic fungus Cochliobolus lunatus cause great economic damages worldwide every year. C. lunatus displays an increased temperature dependent-virulence to a wide range of hosts. Nonetheless, this phenomenon is poorly understood due to lack of insights on the coordinated secretome weaponries produced by C. lunatus under heat-stress conditions on putative hosts. To understand the mechanism better, we dissected the secretome of C. lunatus interacting with potato (Solanum tuberosum L.) leaf at different temperature regimes.ResultsC. lunatus produced melanized colonizing hyphae in and on potato leaf, finely modulated the ambient pH as a function of temperature and secreted diverse set of proteins. Using two dimensional gel electrophoresis (2-D) and mass spectrometry (MS) technology, we observed discrete secretomes at 20°C, 28°C and 38°C. A total of 21 differentially expressed peptide spots and 10 unique peptide spots (that did not align on the gels) matched with 28 unique protein models predicted from C. lunatus m118 v.2 genome peptides. Furthermore, C. lunatus secreted peptides via classical and non-classical pathways related to virulence, proteolysis, nucleic acid metabolism, carbohydrate metabolism, heat stress, signal trafficking and some with unidentified catalytic domains.ConclusionsWe have identified a set of 5 soluble candidate effectors of unknown function from C. lunatus secretome weaponries against potato crop at different temperature regimes. Our findings demonstrate that C. lunatus has a repertoire of signature secretome which mediates thermo-pathogenicity and share a leucine rich “CL[xxxx]LHM”-motif. Considering the rapidly evolving temperature dependent-virulence and host diversity of C. lunatus, this data will be useful for designing new protection strategies.

Scanning electron microscopy of pollen structure throws light on resolving Bambusa–Dendrocalamus complex: bamboo flowering evidence

Since the introduction of the new genus Sinocalamus in 1940 which is now dissociated into Bambusa and Dendrocalamus, molecular markers have long been unable to discern members of the Bambusa–Dendrocalamus complex. Rapid concerted evolution governed by high level of transition/transversion at the noncoding DNA regions has limited the ability of internal transcribed spacer (rDNA) and trnL-F intergenic spacer to resolve Bambusa and Dendrocalamus in phylogenetic analysis. Based on scanning electron microscopy (SEM) analysis of Bambusa vulgaris and Dendrocalamus manipureanus pollen development, we provided the evidence that there exists genus specificity in the development and structure of woody bamboo pollen which can serve as a benchmark for allocated new species into the genus Bambusa and Dendrocalamus substantiating molecular data.

HPLC analysis of harringtonine and homoharringtonine in the needles of Cephalotaxus griffithii alkaloid fraction and cytotoxic activity on chronic myelogenous leukaemia K562 cell

Harringtonine (HT) and homoharringtonine (HHT) are Cephalotaxus alkaloids with considerable antileukaemic activity. The objectives of this research were to (1) determine the content of HT and HHT present in Cephalotaxus griffithii needles alkaloid fraction (CGAF) and (2) compare the antiproliferative activity of CGAF, with that of HT and HHT on chronic myelogenous leukaemia K562 cell. The concentration of HT and HHT was found to be 122.14 and 16.79 mg/g of CGAF, respectively. Treatment of K562 cells with CGAF, HT and HHT decreased the viable cells in a dose- and time-dependent manner. Interestingly, the maximum cell death was found in CGAF, with IC50 value which was 3- to 4.6-fold lower than those of HT and HHT. Our results indicate that HT content in the needles of C. griffithii is higher than HHT, and alkaloids other than HT and HHT in CGAF are predominantly responsible for K562 cell death.

Isolation, screening, characterization, and selection of superior rhizobacterial strains as bioinoculants for seedling emergence and growth promotion of Mandarin orange (Citrus reticulata Blanco)

Mandarin orange (MO) is an important fruit crop of tropical and subtropical regions of the world. A total of 217 morphologically distinct rhizobacteria from MO orchards in 3 states of northeastern India were isolated and analyzed for 4 plant-growth-promoting (PGP) attributes: nitrogen fixation, production of indole acetic acid like substances, solubilization of phosphate, and ability to antagonize pathogenic fungi. Isolates were ranked based on in-vitro-assayed PGP attributes, and 10 superior isolates were selected to test their effect on seedling emergence and seedling growth in a completely randomized pot experiment. These 10 isolates increased seedling emergence over a noninoculated control within 45 days after sowing. Five isolates, namely RCE1, RCE2, RCE3, RCE5, and RCE7, significantly increased shoot length, shoot dry biomass, and root dry biomass of 120-day-old seedlings over the noninoculated control. The beneficial effects of 4 selected strains, namely Enterobacter hormaechei RCE-1, Enterobacter asburiae RCE-2, Enterobacter ludwigii RCE-5, and Klebsiella pneumoniae RCE-7, on growth of the seedlings were visible up to 1 year after their transfer to 8 kg capacity pots. These strains were superior both in terms of in-vitro-assayed PGP attributes and of their beneficial effect in low phosphorus soil and, thus, may be promising bioinoculants for promoting early emergence and growth of MO seedlings.

Essential oil of Cephalotaxus griffithii needle inhibits proliferation and migration of human cervical cancer cells: involvement of mitochondria-initiated and death receptor-mediated apoptosis pathways.

This study was conducted to determine the effect of Cephalotaxus griffithii needle essential oil (CGNO) on proliferation and migration of human cervical cancer (HCC) cells. CGNO treatment decreased the viability of all the tested HCC (HeLa, ME-180 and SiHa) cells. Morphological and DNA fragmentation analysis of CGNO-treated HeLa cells indicated the involvement of apoptosis in inducing HCC cell death. CGNO increased mitochondrial membrane depolarisation and upregulated the expression of caspase-9, caspase-8, caspase-3 and cleaved-PARP. The activity of caspase-8 and caspase-9 was also significantly increased. Wound healing and transwell migration assay demonstrated that CGNO significantly inhibited the migration of HeLa cells to close a scratched wound and also inhibited their migration through filter towards a chemotactic stimulus. Taken together, these results indicated that CGNO inhibited the proliferation and migration of HCC cells. Of note, CGNO induced HeLa cell death through mitochondria-initiated and death receptor-mediated apoptosis pathway.

Host-Range Dynamics of Cochliobolus lunatus: From a Biocontrol Agent to a Severe Environmental Threat

We undertook an investigation to advance understanding of the host-range dynamics and biocontrol implications of Cochliobolus lunatus in the past decade. Potato (Solanum tuberosum L) farms were routinely surveyed for brown-to-black leaf spot disease caused by C. lunatus. A biphasic gene data set was assembled and databases were mined for reported hosts of C. lunatus in the last decade. The placement of five virulent strains of C. lunatus causing foliar necrosis of potato was studied with microscopic and phylogenetic tools. Analysis of morphology showed intraspecific variations in stromatic tissues among the virulent strains causing foliar necrosis of potato. A maximum likelihood inference based on GPDH locus separated C. lunatus strains into subclusters and revealed the emergence of unclustered strains. The evolving nutritional requirement of C. lunatus in the last decade is exhibited by the invasion of vertebrates, invertebrates, dicots, and monocots. Our results contribute towards a better understanding of the host-range dynamics of C. lunatus and provide useful implications on the threat posed to the environment when C. lunatus is used as a mycoherbicide.

Antioxidant, antibacterial, cytotoxic, and apoptotic activity of stem bark extracts of Cephalotaxus griffithii Hook. f

BackgroundCephalotaxus spp. are known to possess various therapeutic potentials. Cephalotaxus griffithii, however, has not been evaluated for its biological potential. The reason may be the remoteness and inaccessibility of the habitat where it is distributed. The main aim of this study was to: (1) evaluate multiple biological potentials of stem bark of C. griffithii, and (2) identify solvent extract of stem bark of C. griffithii to find the one with the highest specific biological activity.MethodsDried powder of stem bark of C. griffithii was exhaustively extracted serially by soaking in petroleum ether, acetone and methanol to fractionate the chemical constituents into individual fractions or extracts. The extracts were tested for total phenolic and flavonoid content, antioxidant (DPPH radical scavenging, superoxide radical scavenging, and reducing power models), antibacterial (disc diffusion assay on six bacterial strains), cytotoxic (MTT assay on HeLa cells), and apoptotic activity (fluorescence microscopy, DNA fragmentation assay, and flow cytometry on HeLa cells).ResultsAmong the three extracts of stem bark of C. griffithii, the acetone extract contained the highest amount of total phenolics and flavonoids and showed maximum antioxidant, antibacterial, cytotoxic (IC50 of 35.5 ± 0.6 μg/ml; P < 0.05), and apoptotic (46.3 ± 3.6% sub-G0/G1 population; P < 0.05) activity, followed by the methanol and petroleum ether extracts. However, there was no significant difference observed in IC50 values (DPPH scavenging assay) of the acetone and methanol extracts and the positive control (ascorbic acid). In contrast, superoxide radical scavenging assay-based antioxidant activity (IC50) of the acetone and methanol extracts was significantly lower than the positive control (P < 0.05). Correlation analysis suggested that phenolic and flavonoid content present in stem bark of C. griffithii extracts was responsible for the high antioxidant, cytotoxic, and apoptotic activity (P < 0.05).ConclusionsStem bark of C. griffithii has multiple biological effects. These results call for further chemical characterization of acetone extract of stem bark of C. griffithii for specific bioactivity.

Curcumin Resource Database

Curcumin is one of the most intensively studied diarylheptanoid, Curcuma longa being its principal producer. This apart, a class of promising curcumin analogs has been generated in laboratories, aptly named as Curcuminoids which are showing huge potential in the fields of medicine, food technology, etc. The lack of a universal source of data on curcumin as well as curcuminoids has been felt by the curcumin research community for long. Hence, in an attempt to address this stumbling block, we have developed Curcumin Resource Database (CRDB) that aims to perform as a gateway-cum-repository to access all relevant data and related information on curcumin and its analogs. Currently, this database encompasses 1186 curcumin analogs, 195 molecular targets, 9075 peer reviewed publications, 489 patents and 176 varieties of C. longa obtained by extensive data mining and careful curation from numerous sources. Each data entry is identified by a unique CRDB ID (identifier). Furnished with a user-friendly web interface and in-built search engine, CRDB provides well-curated and cross-referenced information that are hyperlinked with external sources. CRDB is expected to be highly useful to the researchers working on structure as well as ligand-based molecular design of curcumin analogs. Database URL: http://www.crdb.in

Cephalotaxus griffithii Hook.f. needle extract induces cell cycle arrest, apoptosis and suppression of hTERT and hTR expression on human breast cancer cells

BackgroundCephalotaxus spp. are known to possess anticancer potential. In this present work, for the first time the effects of C. griffithii needle (CGN) extracts on human cancer cells were examined.MethodsThe CGN was successively extracted with petroleum ether (PE), acetone and methanol. The extracts were tested for its effect on proliferation of cancer cells (MTT assay on HeLa, ZR751 and HepG2). Extract that showed the maximum growth inhibitory effect was subjected for mechanism of action study. These included apoptosis (morphological and DNA fragmentation assay), cell cycle (flow cytometry), caspase expression (Western blot) and activity (assay kit), p53 (western blot and TP53 siRNA interference) and telomerase expression (reverse transcriptase PCR) analysis.ResultsAmong the extracts, PE extract induced maximum cytotoxicity, with highest death occurred in ZR751 cells. Since, PE extract induced cell death was highest among the CGN extracts, with maximum cancer cell death occurred in ZR751 cells; we carried out mechanism study of PE extract induced ZR751 cell death. It was observed that PE extract induced ZR751 cell death was associated with cell cycle arrest and apoptosis by activating both intrinsic and extrinsic apoptotic pathways. Knock down study revealed that p53 is essential for loss of ZR751 cell viability induced by PE extract. Further, PE extract down-regulated hTERT, hTR, and c-Myc expression. Thin layer chromatography analysis indicated the presence of unique phytochemicals in PE extract.ConclusionBased on the observations, we concluded that PE extract of C. griffithii needle contains important phyto-components with multiple cellular targets for control of breast cancer and is worthy of future studies.