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H C Joshi

Publications and source records attributed to H C Joshi.

At least 19 recordsLinked to original sources
PubMed2005

Impact of post-methanation distillery effluent irrigation on groundwater quality.

Molasses-based distilleries generate large quantities of effluent, which is used for irrigation in many countries including India. The effluent is rich in organic and inorganic ions, which may leach down and pollute the groundwater. An on-farm experiment was conducted to assess the impact of long-term irrigation with post-methanation distillery effluent (PMDE) on nitrate, sulphate, chloride, sodium, potassium, and magnesium contents in the groundwater of two sites in northwest India. Electrical conductivity (EC), pH, total dissolved solids (TDS), sodium adsorption ratio (SAR) and colour were also determined to assess the chemical load in the groundwater. Nitrate content in the groundwater samples ranged from 16.95 mg L(-1) in the unamended fields to 59.81 mg L(-1) in the PMDE-amended fields during the 2-year study (2001-2002). Concentrations of TDS in water samples from tubewell of the amended field was higher by 40.4% over the tubewell water of the unamended field. Colour of the water samples of the amended fields was also darker than that of the unamended fields. The study indicated that the organic and inorganic ions added through the effluent could pose a serious threat to the groundwater quality if applied without proper monitoring.

Agriculture↗
PubMed2003

Fluorescence characteristics of protonated form of 6-hydroxyquinoline in Nafion film.

Fluorescence characteristics of 6-hydroxyquinoline (6-HQ) have been studied at room temperature in Nafion(R) film by steady state and nano-second time-resolved fluorescence spectroscopy. The fluorescence spectrum exhibits single emission band corresponding to the protonated form of 6-HQ in this matrix. However, the decay fits with two or three exponential functions depending on the emission wavelength monitored. At blue edge of the emission, the decay fits to three-exponential function, whereas at longer wavelengths, the decay fits to bi-exponential function. Two tentative mechanisms have been proposed to explain the experimental data, viz. a closely lying charge transfer state (CT) or an excited state proton transfer (ESPT) process. The photophysical parameters appear to be sensitive to the change in microstructure due to swelling of the membrane by the solvents.

Fluorocarbon Polymers↗
PubMed2003

Soil properties and crop productivity as influenced by flyash incorporation in soil.

Field experiments were carried out during 1996-97 at Gulawathi, Muthiani and Salarpur Villages, IARI Farm, New Delhi and NCPP Campus, Dadri to evaluate changes in soil characteristics and growth of wheat (Triticum aestivum L.), mustard (Brassica juncea L.), lentil (Lence esculenta Moench.), rice (Oryza sativa L.) and maize (Zea mays L.) by varying amounts of flyash addition (up to 50t ha(-1)) in soils at sowing/transplanting time of crops. Flyash addition in areas adjoining NCPP Thermal Power Plant, Dadri, Ghaziabad, U.P. ranged from 5-12 t ha(-1)] yr(-1) in 1995-96. Shoot and root growth and yield of test crops at different locations after flyash incorporation resulted in beneficial effects of flyash addition in most cases. The silt dominant texture of flyash improved loamy sand to sandy loam textures of the surface soils at the farmers' fields. The increased growth in yield of crops with flyash incorporation was possibly due to modifications in soil moisture retention and transmission characteristics, bulk density, physico-chemical characters such as pH and EC and organic carbon content. The response of flyash addition in the soil on soil health and crop productivity needs to be evaluated on long-term sustainable aspects.

Agriculture↗
PubMed2002

Effect of potassium salts and distillery effluent on carbon mineralization in soil.

Distillery effluent, a rich source of potassium, is used for irrigation at many places in the world. A laboratory experiment was conducted to study the influence of potassium salts present in post-methanation distillery effluent (PME) along with two other salts, KCl and K2SO4, on mineralization of carbon in soil. PME oxidized with H2O2, raw PME, KCl and K2SO4 solutions containing K equivalent to 10%, 20%, 40% and 100% of K present in PME were added to the soil separately, maintaining four replications for each treatment and control. Addition of salts up to a certain concentration stimulated C mineralization but a decline was noticed at higher concentrations. All the levels of salts caused higher CO2 evolution than the control suggesting that the presence of K salts enhanced the microbial activity resulting in increased CO2 evolution. The influence of K2SO4 was significantly higher than KCl in stimulating C mineralization in soil. Oxidized effluent had a higher stimulating effect than inorganic salts, showing the influence of other salts accompanying K in the PME. Raw PME, which contained excess organic C, increased CO2 evolution even at the highest salt level (100% PME) signifying the effect of added C on alleviating the salt stress on microbial activity.

Carbon↗
PubMed2002

Steady state and time-resolved spectroscopic studies of 7-hydroxyquinoline in various polymeric matrices.

The photophysical behavior of 7-hydroxyquinoline (7HQ) is studied in four polymer matrices, viz. polymethyl methacrylate (PMMA), cellulose acetate (CA), polyvinyl alcohol (PVA) and Nafion-117, at ambient temperature using both steady state and time-domain measurements. The study reveals both ground as well as excited state tautomerization in the case of PVA. In PMMA and CA, the intermolecular hydrogen bond to the host polymer results in proton transfer. Edge excitation red shift (EERS) and excitation and emission wavelength dependent decays are observed for normal emission in PMMA and CA matrices. These results are attributed to the trapping of a normal molecule in different geometries. In Nafion, the results show the presence of 7HQ cationic species trapped in the polymer.

Cellulose↗
PubMed2001

Sustained activation of p34(cdc2) is required for noscapine-induced apoptosis.

Mitotic arrest and subsequent apoptosis has been observed in many types of cells treated with anti-microtubule agents. However, the molecular mechanisms underlying the two events as well as their relationship are not well understood; on the contrary, there has been increasing evidence indicating that anti-microtubule agents might induce apoptosis via signaling pathways independent of mitosis. In this study, we found that apoptosis induced by noscapine, an anti-microtubule drug previously shown to cause both mitotic arrest and apoptotic cell death, was blocked by inhibiting p34(cdc2) activity with olomoucine in FM3A murine mammary carcinoma cells or by reducing the level and activity of p34(cdc2) in a mutant cell line FT210 derived from FM3A. Furthermore, transfection of the mutant FT210 cells with wild-type p34(cdc2) restored their ability to undergo mitotic arrest and then apoptosis in response to noscapine. Thus, we conclude that sustained activation of the p34(cdc2) kinase during mitotic arrest is required for subsequent apoptosis induced by noscapine, establishing a link between the two events.

Animals↗
PubMed2001

Conditional mutations in gamma-tubulin reveal its involvement in chromosome segregation and cytokinesis.

gamma-Tubulin is a conserved essential protein required for assembly and function of the mitotic spindle in humans and yeast. For example, human gamma-tubulin can replace the gamma-tubulin gene in Schizosaccharomyces pombe. To understand the structural/functional domains of gamma-tubulin, we performed a systematic alanine-scanning mutagenesis of human gamma-tubulin (TUBG1) and studied phenotypes of each mutant allele in S. pombe. Our screen, both in the presence and absence of the endogenous S. pombe gamma-tubulin, resulted in 11 lethal mutations and 12 cold-sensitive mutations. Based on structural mapping onto a homology model of human gamma-tubulin generated by free energy minimization, all deleterious mutations are found in residues predicted to be located on the surface, some in positions to interact with alpha- and/or beta-tubulins in the microtubule lattice. As expected, one class of tubg1 mutations has either an abnormal assembly or loss of the mitotic spindle. Surprisingly, a subset of mutants with abnormal spindles does not arrest in M phase but proceeds through anaphase followed by abnormal cytokinesis. These studies reveal that in addition to its previously appreciated role in spindle microtubule nucleation, gamma-tubulin is involved in the coordination of postmetaphase events, anaphase, and cytokinesis.

Amino Acid Sequence↗
PubMed2001

Kendrin/pericentrin-B, a centrosome protein with homology to pericentrin that complexes with PCM-1.

The centrosome is responsible for nucleating microtubules and performing other cellular roles. To define the organization of the centrosome more completely, a human anti-centrosome serum was used to screen a human cDNA library, and a cDNA encoding a >350 kDa centrosome protein was identified. Sequence analyses revealed that this novel centrosome protein contains two coiled-coil domains bounded by non-coiled regions. The N-terminal region of the protein, named pericentrin-B, shares 61% identity (75% similarity) with pericentrin, suggesting an evolutionary relationship between these proteins. Antibodies against pericentrin-B stain centrosomes at all stages of the cell cycle, and pericentrin-B remains associated with centrosomes following microtubule depolymerization. Immunodepletion of neither pericentrin-B nor PCM-1 from cellular extracts inhibited the ability of salt-stripped centrosomes to recover microtubule nucleation potential, demonstrating that neither protein plays a key role in microtubule nucleation processes. Moreover, the binding of both PCM-1 and pericentrin-B with salt-stripped centrosomes required intact microtubules, demonstrating that the association of PCM-1 and pericentrin-B with centrosomes is a late event in the centrosome maturation process. Finally, pericentrin-B and PCM-1 coimmunoprecipitate, suggesting that PCM-1 and pericentrin-B form a functional complex in cells. This observation may help to explain the generation of anti-centrosome autoantibodies in certain autoimmune patients and may be important for centrosome function.

Amino Acid Sequence↗
PubMed2000

Noscapine inhibits tumor growth with little toxicity to normal tissues or inhibition of immune responses.

Noscapine, a phthalideisoquinoline alkaloid derived from opium, has been used as an oral anti-tussive agent and has shown very few toxic effects in animals or humans. Recently, we reported that noscapine binds stoichiometrically to tubulin and promotes microtubule polymerization. Noscapine causes growth arrest of tumor cells in mitosis and induces apoptosis of tumor cells in vitro. Previous experiments also showed that noscapine has potent antitumor activity in mice when administered parenterally or by gastric lavage. Here, we report that the anti-mitotic effect was specific to noscapine since closely related compounds did not inhibit the growth of a lymphoma cell line. In addition, noscapine was shown to be effective in reducing the growth of the lymphoma and increasing the survival of tumor-bearing mice when administered in the drinking water. It is noteworthy that, noscapine showed little or no toxicity to kidney, liver, heart, bone marrow, spleen or small intestine at tumor-suppressive doses. Furthermore, oral noscapine did not inhibit primary immune responses, which are critically dependent upon proliferation of lymphoid cells. Thus, our results indicate that noscapine has the potential to be an effective chemotherapeutic agent for the treatment of human cancer.

Alkaloids↗
PubMed2000

Noscapine and analogues as potential chemotherapeutic agents.

Noscapine, an antitussive drug, has been previously shown to inhibit the growth of cultured tumor cells and tumors implanted in nude mice. Like some other antitumor agents, noscapine targets a cellular protein, tubulin, that is responsible for the assembly of important scaffolding polymers, microtubules. As a result, noscapine causes the aberrant assembly of the cellular machinery necessary for cell division, the mitotic spindle. This is followed by apoptotic cell death. Current evidence suggests that the antitumor activity of noscapine might lie in its initiation of apoptotic pathways. Compared with other microtubule drugs, noscapine has low toxicity and wide efficacy in animal models. For clinical use, noscapine affords simple means of administration including oral, rectal, parenteral or by simple inhalation of suitable aerosols. Thus, noscapine and its analogues are potential cost-effective chemotherapeutic agents for the treatment of human cancers.

Journal Article↗
PubMed1998

Centrosome reduction during mouse spermiogenesis.

The sperm does not contribute the centrosome during murine fertilization. To determine the manner in which a functional centrosome is reduced, we have studied centrosome degeneration during spermiogenesis of mice. The round spermatids display normal centrosomes consisting of a pair of centrioles along with gamma-tubulin containing foci. However, they do not seem to organize microtubules. Elongating spermatids display gamma-tubulin spots in the neck region, while microtubules are organized from the perinuclear ring as the manchette. Electron microscopic studies using immunogold labeling revealed that gamma-tubulin is mainly localized in the centriolar adjunct from which an aster of microtubules emanates. Microtubules repolymerized randomly in the cytoplasm after nocodazole treatment and reversal. gamma-Tubulin dissociates from the neck region and is discarded in the residual bodies during spermiation. The distal centriole degenerates during testicular stage of spermiogenesis, while the proximal centriole is lost during epididymal stage. Loss of centrosomal protein and centrioles in mouse sperm further confirm the maternal inheritance of centrosome during murine fertilization.

Animals↗
PubMed1998

Opium alkaloid noscapine is an antitumor agent that arrests metaphase and induces apoptosis in dividing cells.

An alkaloid from opium, noscapine, is used as an antitussive drug and has low toxicity in humans and mice. We show that noscapine binds stoichiometrically to tubulin, alters its conformation, affects microtubule assembly, and arrests mammalian cells in mitosis. Furthermore, noscapine causes apoptosis in many cell types and has potent antitumor activity against solid murine lymphoid tumors (even when the drug was administered orally) and against human breast and bladder tumors implanted in nude mice. Because noscapine is water-soluble and absorbed after oral administration, its chemotherapeutic potential in human cancer merits thorough evaluation.

Animals↗
PubMed1998

Microtubule dynamics in living cells.

Most people think of a skeleton as a solid and static framework upon which complex structures are elaborated. From what we have learned in the past decade about the cytoskeleton, it seems certain that the 'skeleton' part of the term is a bit misleading. It is clear now that the polymers that constitute the cytoskeleton, actin filaments, microtubules, and intermediate filaments, are all in fact ever-changing dynamic infrastructures of cells. Recently, advances have been made in the study of the cellular dynamics of one of the prominent components of the cytoskeleton, the microtubules. Observations in the past year have revealed some fundamental in vivo behaviors of these polymers, during interphase, during mitosis, and during the elaboration of postmitotic axonal microtubule arrays. These observations are important for the understanding of cytoplasmic organization in many types of cells.

Animals↗
PubMed1996

Distribution of gamma-tubulin differs in primary and secondary oocytes of Ephestia kuehniella (Pyralidae, Lepidoptera).

In a previous study, barrel-shaped spindles were found in metaphase I oocytes of Ephestia kuehniella (Pyralidae, Lepidoptera). Aster microtubules (MTs) were missing (Wolf, 1993: Cell Motil Cytoskeleton 24:200-204). This points to an acentriolar organization of the spindle apparatus. The present study was aimed at the question of whether gamma-tubulin, a newly detected member of the tubulin superfamily that has often been identified in microtubule-organizing centers, plays a role in the nucleation of MTs in meiotic spindles of the moth. To this end, the distribution of gamma-tubulin was examined in oocytes of E. kuehniella using an antibody against gamma-tubulin in combination with indirect immunofluorescence. The antibody evenly decorated spindle MTs in metaphase I oocytes of the moth. Enhanced staining of the spindle poles was not detectable. In subsequent stages of meiosis, gamma-tubulin was gradually lost from spindle MTs and was then found at the surface of the so-called elimination chromatin. Female meiosis in Lepidoptera is achiasmatic. The elimination chromatin, i.e., modified and persisting synaptonemal complexes, is believed to keep homologous chromosomes linked until the onset of anaphase I. In meiosis I of female Lepidoptera, the elimination chromatin persists at the spindle equator between the segregating chromatin masses. It is plausible to assume that gamma-tubulin is involved in spindle organization in the absence of canonical centrosomes. In MTs of metaphase II spindles of E. kuehniella, gamma-tubulin was no longer detectable with our immunological approach. This points to a far-reaching change in spindle organization during transition from meiosis I to meiosis II.

Animals↗
PubMed1996

Microtubule organization and distribution of gamma-tubulin in male meiosis of lepidoptera.

Meiotic spindles in males of higher Lepidotera are unusual in that the bulk of the spindle microtubules (MTs) ends about halfway between the equatorial plate and the centrosomes in metaphase. It appears worthwhile to determine how the MTs are nucleated, while their pole proximal ends are distant from the centrosomes. To this end, spermatocytes of Phragmatobia fuliginosa (Arctiidae), collected in the field, were double-labeled with antibodies to beta- and gamma-tubulin. The former antibody reveals the entire microtubular cytoskeleton, and the latter is directed against a newly-discovered tublin isoform that is prevalent in microtubule-organizing centers (MTOCs). The immunocytochemical work was supplemented by a fine structural analysis of MTOCs and spindles. Gamma-tubulin was clearly detected at the spindle poles, and prominent microtubular asters originated from these sites. Additionally, MT arrays at both sides of the equatorial plate in metaphase spermatocytes contained gamma-tubulin. The staining persisted in late anaphase, when kinetochore MTs are depolymerized. This indicates that at least nonkinetochore MTs contain gamma-tubulin. The analysis of ultrathin sections through spindles revealed large amounts of pericentriolar material at the spindles poles, in prometaphase through anaphase. The spindle MTs appeared as regular, straight elements in longitudinal sections. We assume that gamma-tubulin is located at the pole proximal ends of the MTs and/or is associated with the spindle MTs throughout their lengths. In order to distinguish between these possibilities, testes of Ephestia kuehniella (Pyralidae), a laboratory species, were cold-treated prior to double-labeling with antibodies to beta- and gamma-tubulin. The treatment was expected to depolymerize MTs. Astral MTs, which were nucleated end-on by gamma-tubulin-containing material, indeed depolymerized. In contrast, the gamma-tubulin-containing spindle MTs persisted. It is, therefore, conceivable that gamma-tubulin is associated with MTs throughout their lengths in male meiosis of Lepidoptera species. It is plausible that this association stabilizes the MTs against cold-induced disassembly.

Animals↗
PubMed1996

gamma-Tubulin and microtubule organization in plants.

In animal cells, microtubule assembly is usually initiated at one specialized structure, the centrosome. By contrast, in plant cells, microtubule assembly begins at a variety of locations within the cell. A member of the tubulin gene family, gamma-tubulin, is localized to the centrosome in animal cells and is important in the assembly of microtubules in vivo. Recent reports have identified gamma-tubulin genes in plants and have described the complex intracellular distribution of the encoded polypeptides. Here, Harish Joshi and Barry Palevitz comment upon how this information may help elucidate the organizing principles of the complex arrays of microtubules in plant cells.

Journal Article↗
PubMed1996

Tubulin transport in neurons.

A question of broad importance in cellular neurobiology has been, how is microtubule cytoskeleton of the axon organized? It is of particular interest because of the history of conflicting results concerning the form in which tubulin is transported in the axon. While many studies indicate a stationary nature of axonal microtubules, a recent series of experiments reports that microtubules are recruited into axons of neurons grown in the presence of a microtubule-inhibitor, vinblastine (Baas, P.W., and F.J. Ahmad. 1993.J. Cell Biol. 120:1427-1437: Ahmad F.J., and P.W. Baas. 1995. J. Cell Sci, 108:2761-2769; Sharp, D.J., W. Yu, and P.W. Baas. 1995. J. Cell Biol, 130:93-103; Yu, W., and P.W. Baas. 1995. J. Neurosci. 15:6827-6833.). Since vinblastine stabilizes bulk microtubule-dynamics in vitro, it was concluded that preformed microtubules moved into newly grown axons. By visualizing the polymerization of injected fluorescent tubulin, we show that substantial microtubule polymerization occurs in neurons grown at reported vinblastine concentrations. Vinblastine inhibits, in a concentration-dependent manner, both neurite outgrowth and microtubule assembly. More importantly, the neuron growth conditions of low vinblastine concentration allowed us to visualize the footprints of the tubulin wave as it polymerized and depolymerized during its slow axonal transport. In contrast, depolymerization resistant fluorescent microtubules did not move when injected in neurons. We show that tubulin subunits, not microtubules, are the primary form of tubulin transport in neurons.

Animals↗