Bacterial Diversity in the Metal-Rich Terrestrial Deep Subsurface Sediments of Krishna Godavari Basin,India

Abstract

Krishna Godavari (KG) basin, located in the eastern continental margin of India, is a geological region well known for the abundance of economically important minerals. However, less is known about the microbial ecology of its subsurface sediments. The present study is the first report on the comprehensive culture-independent census of bacterial communities of deep subsurface of KG basin and their relationship with the geochemical environment. Elemental and mineralogical characterization of the sediments highlighted the presence of carbon and nitrogen deprived conditions along with the abundance of metalliferous minerals, especially rich in valuable elements like zirconium, vanadium, cesium, and rare earth elements. Diversity analysis based on Illumina MiSeq high-throughput sequencing platform revealed the predominance of Firmicutes (44.24%), Proteobacteria (34.17%), Bacteroidetes (15.18%), and Actinobacteria (3.81%) in the deep subsurface of this basin. ‘Abundant’ and ‘rare’ sub-communities analysis indicated that a large number of phyla like Acidobacteria, Armatimonadetes, Chloroflexi, and Deinococcus-Thermus were exclusively present as a rare community. Statistical analyses demonstrated that geochemical parameters, especially depth, pH, and metal content, showed significant influence on the microbial community structure. The present study should help future investigations for microbial mediated sustainable utilization of mineral-rich sediments of the region.     

An improved protocol for electroporation in members of the genus Gordonia

Gordonia are high GC gram-positive bacteria that have not yet been exploited well for biotechnological purposes because of the limited genetic tools. Described here is an improved protocol for electroporation, which is useful for several Gordonia species. The maximum transformation efficiency obtained was 2.8 × 10⁴/μg (Gordonia rubropertinctus, Gordonia sp), and 1.7 × 10³/μg (Gordonia amarae).     

Functional Access to Neuron Subclasses in Rodent and Primate Forebrain

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Re-expression of proteins involved in cytokinesis during cardiac hypertrophy

Cardiomyocytes stop dividing after birth and postnatal heart growth is only achieved by increase in cell volume. In some species, cardiomyocytes undergo an additional incomplete mitosis in the first postnatal week, where karyokinesis takes place in the absence of cytokinesis, leading to binucleation. Proteins that regulate the formation of the actomyosin ring are known to be important for cytokinesis. Here we demonstrate for the first time that small GTPases like RhoA along with their downstream effectors like ROCK I, ROCK II and Citron Kinase show a developmental stage specific expression in heart, with high levels being expressed in cardiomyocytes only at stages when cytokinesis still occurs (i.e. embryonic and perinatal). This suggests that downregulation of many regulatory and cytoskeletal components involved in the formation of the actomyosin ring may be responsible for the uncoupling of cytokinesis from karyokinesis in rodent cardiomyocytes after birth. Interestingly, when the myocardium tries to adapt to the increased workload during pathological hypertrophy a re-expression of proteins involved in DNA synthesis and cytokinesis can be detected. Nevertheless, the adult cardiomyocytes do not appear to divide despite this upregulation of the cytokinetic machinery. The inability to undergo complete division could be due to the presence of stable, highly ordered and functional sarcomeres in the adult myocardium or could be because of the inefficiency of degradation pathways, which facilitate the division of differentiated embryonic cardiomyocytes by disintegrating myofibrils.     

Melanocyte–keratinocyte interaction induces calcium signalling and melanin transfer to keratinocytes

Physical contact between melanocytes and keratinocytes is a prerequisite for melanosome transfer to occur, but cellular signals induced during or after contact are not fully understood. Herein, it is shown that interactions between melanocyte and keratinocyte plasma membranes induced a transient intracellular calcium signal in keratinocytes that was required for pigment transfer. This intracellular calcium signal occurred due to release of calcium from intracellular stores. Pigment transfer observed in melanocyte–keratinocyte co‐cultures was inhibited when intracellular calcium in keratinocytes was chelated. We propose that a ‘ligand‐receptor’ type interaction exists between melanocytes and keratinocytes that triggers intracellular calcium signalling in keratinocytes and mediates melanin transfer.     

In vitro culture in combination with aeroponics is an efficient means of mass propagation of Sarcostemma acidum: a rare medicinal plant of Indian arid zone

In Vitro Cellular & Developmental Biology - Plant - In vitro culture in combination with aeroponics is observed to be an efficient means for mass propagation of Sarcostemma acidum in the...     

Efficacy of human beta-casein fragment (54-59) and its synthetic analogue compound 89/215 against Leishmania donovani in hamsters

The characteristic feature of visceral leishmaniasis (VL) is the profound impairment of immune system of the infected host, which contributes significantly to the partial success of antileishmanial chemotherapy. Since in VL, cure is the combinatorial effect of drug and immune status of the host, the rationale approach towards antileishmanial chemotherapy would be to potentiate the immune functioning of the host to extract desired results. Towards this direction several rationally designed analogues of human beta-casein fragment (54-59) were evaluated for their ability to stimulate the non-specific resistance in hamsters against Leishmania donovani infection. By virtue of being derived from the food protein casein derivatives may be devoid of unwanted side effects associated with the substances of microbial origin, e.g. muramyl dipeptide (MDP). Out of this one peptide Val-Glu-Gly-Ile-Pro-Tyr (compound 89/215) had been reported to have such activity. In this communication, the prophylactic and therapeutic efficacy of the peptide along with its natural sequence has been evaluated in detail against experimental VL in hamsters. Their use as an adjunct to chemotherapy was also explored. Human beta-casein fragment, compound 89/215 and MDP were tested in vivo at various dose levels wherein compound 89/215 showed superiority over MDP at 3 mg/kg x 2 given intraperitoneally (i.p.). Compound 89/215 sensitized peritoneal macrophages acquired considerable resistance and only 24% of the cells were found infected in comparison to control peritoneal macrophages where 76.4% of the cells were found infected. Similarly, the efficacy of sodium antimony gluconate (SAG) in hamsters pretreated with compound 89/215 enhanced significantly (P < 0.001). This peptide also exhibited considerably good therapeutic efficacy when evaluated either alone or in combination with SAG in established infection of L. donovani.     

Liquid-ordered microdomains in lipid rafts and plasma membrane of U-87 MG cells: a time-resolved fluorescence study

Lipid rafts, the functional microdomains in the cell membrane, are believed to exist as liquid-ordered (Lo) phase domains along with the liquid-disordered (Ld) phase of the bulk of the cell membranes. We have examined the lipid order in model and natural membranes by time-resolved fluorescence of trimethylammonium-1,6-diphenylhexatriene incorporated into the membranes. The lipid phases were discerned by the limiting anisotropy, rotational diffusion rate and distribution of the fluorescence lifetime. In dipalmitoylphosphatidylcholine (DPPC)-cholesterol mixtures the gel phase exhibited higher anisotropy and a two-fold slower rotational diffusion rate of the probe as compared to the Ld phase. On the other hand, the Lo phase exhibited higher limiting anisotropy but a rotational diffusion rate comparable to the Ld phase. The Ld and Lo phases elicited unimodal distribution of lifetimes with distinct mean values and their co-existence in phospholipid-cholesterol mixtures was reflected as a biphasic change in the width of the lifetime distribution. Global analysis of the lifetimes yielded a best fit with two lifetimes which were identical to those observed in single Lo or Ld phases, but their fractional contribution varied with cholesterol concentration. Attributing the shorter and longer lifetime components to the Ld and Lo phases, respectively, the extent of the Lo/Ld phase domains in the membranes was estimated by their fractional contribution to the fluorescence decay. In ternary mixtures of egg PC-gangliosides-cholesterol, the gangliosides induced heterogeneity in the membrane but the Ld phase prevailed. The Lo phase properties were observed only in the presence of cholesterol. Results obtained in the plasma membrane and detergent-resistant membrane fractions (DRMs) isolated from U-87 MG cells revealed that DRMs mainly possess the Lo phase; however, a substantially large proportion of plasma membrane also exists in the Lo phase. Our data show that, besides cholesterol, the membrane proteins play a significant role in the organization of lipid rafts and, furthermore, a considerable amount of heterogeneity is present among the lipid rafts.