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1.
Lanthanum belongs to the group of elements known as “lanthanons,” which also includes cerium, europium, promethium, and thulium. It is the most electropositive element of the rare earth group, is uniformly trivalent, and is similar in its chemical properties to the alkaline earth elements. The effects of this element and its compounds on cellular systems are of considerable interest because of their increasing use in industry and as a substitute or antagonist for calcium in a variety of cellular reactions. Lanthanum is also being employed extensively in studying anatomical barriers, membrane structure, and subcellular transport systems, particularly the calcium pathway. 相似文献
2.
Archana Pundle Asmita Prabhune Hephzibah SivaRaman 《Applied microbiology and biotechnology》1988,29(5):426-429
Summary A procedure which does not involve the use of an immiscible organic solvent phase is described for the entrapment of yeast cells in porous beads of polyacrylamide gel. The cells are rapidly dispersed at 4° C in an aqueous solution containing sodium alginate and acrylamide-N,Nmethylene-bis-acrylamide monomer, and the suspension is immediately dropped into a solution of calcium formate to give calcium alginate coated beads. Polyacrylamide gel forms within the bead. The calcium alginate is subsequently leached out of the composite bead with either sodium citrate or potassium phosphate buffer solution. Cells of Saccharomyces uvarum ATCC 26 602 entrapped in such polyacrylamide beads ferment cane molasses in batch mode at higher specific ethanol productivity than a free cell suspension. Their volumetric productivity in continuous fermentation is higher than that of Ca2+-alginate immobilized cells.NCL Communication No. 4383 相似文献
3.
The effects of cobaltous chloride in inducing chromosomal aberrations were observed on laboratory bred mice in vivo after single oral administration of different fractions (1/10, 1/20, 1/40) of the lethal toxic dose of the salt. Bone marrow cells were flushed out and processed for chromosome studies following colchicine, hypotonic, giemsa, air drying procedure. The parameters screened were chromosomal aberrations, with and without gaps and break per cell. Slides were screened after the expiry of 6, 12, 18, and 24 h. Statistical analysis indicated the clastogenic effects of the salt. The degree of chromosome damage was directly related to the concentration, and also to the period after administration. The different stages of the cell cycle were affected. 相似文献
4.
5.
The ability to withstand thermal stress in a laboratory population of the blowflyLucilia cuprina (measured as per cent adult survival following varying periods of exposure to elevated temperature up to a maximum of 48°C)
was in the order pupa > larva > adult. Pre-exposure to a mild heat shock (37°C) induced tolerance to temperatures which were
otherwise lethal. An analysis of heat shock-induced protein synthesis during development at similar elevated temperatures
presented patterns corresponding to the above observations on thermotolerance. The induced level of synthesis of major heat
shock proteins (viz., 79, 69, 28, 20 and 19 kDa) were greater in larval tissues than in most of the adult tissues except gonads.
The response varied between young (2 days) and old (30 days) adults in a tissue-specific manner. In general, heat shock protein
69 kDa was most abundant in all the tissues studied. Control as well as heat shocked Malpighian tubules of adults uniquely
showed two major [35S]methionine labelled bands corresponding to approximately 62 and 64 kDa. Immunoblots showed the 62 kDa protein to cross react
with an antibody againstHelioihis HSP60. Although the synthesis of the 62 kDa polypeptide was prominent only in Malpighian tubules of adult blowflies, nearly
equal levels of this HSP60 family polypeptide were present in all tissues (control as well heat shocked) except the larval
salivary glands. 相似文献
6.
Archana Sachdev Monica Sharma R. P. Johari S. L. Mehta 《Journal of plant biochemistry and biotechnology.》1995,4(1):33-36
The strain BYT-1, capable of utilizing ODAP/DAP as a sole source of nitrogen and carbon was identified as Psuedomonas stutzeri by various microbial and biochemical tests. Transformation experiments showed that the ODAP utilizing property Is encoded by the plasmid. Restriction of plasmid DNA with Pstl, followed by cloning of fragments and screening of ODAP containing medium, led to the isolation of a clone with insert size of ?3.3 kb, which encoded ODAP metabolizing property. The growth and ODAP/DAP utilization by this clone (TB) was almost similar to that of the wild type strain. 相似文献
7.
Soft, nodular and hard types of calli were initiated on mature zygotic embryo explants of two tetraploid clones of Costus speciosus, of which, only the hard calli were amenable to morphogenetic responses. The two clones differed in their growth regulator requirements both for the initiation of calli and for shoot regeneration. De novo formation of both shoot bud meristems and somatic embryoids were observed. Latter were encased partially or fUlly by coleoptilar sheath. Embryoids could be isolated as discrete units. On maturity, a stock like appendage developed from the base and finally embryoids got detached from the subtending tissue. Both shoot-bud meristems and somatic embryoids developed into complete plantlets, the former upon sequential transfer of calli on Schenk and Hildebrandt’s (SH) basal medium containing lower levels of growth hormones, while the latter only on basal medium. These culture regenerants were subsequently transferred to the field. The morphogenetic behaviour of these two tetraploid clones reflects their marked genotypic difference inspite of their same ploidy status. 相似文献
8.
Manganese in cell metabolism of higher plants 总被引:1,自引:0,他引:1
Manganese, a group VII element of the periodic table, plays an important role in biological systems and exists in a variety of oxidation states. The normal level of Mn in air surrounding major industrial sites is 0.03 μg/m3, in drinking water 0.05 mg/liter and in soil between 560 and 850 ppm. Manganese is an essential trace element for higher plant systems. It is absorbed mainly as divalent Mn2+, which competes effectively with Mg2+ and strongly depresses its rate of uptake. The accumulation of Mn particularly takes place in peripheral cells of the leaf petiole, petiolule and palisade and spongy parenchyma cells. Mn is involved in photosynthesis and activation of different enzyme systems. Mn deficiency may be expressed as inhibition of cell elongation and yield decrease. Mn toxicity is one of the important growth limiting factors in acid soils. Plant tops are affected to a greater extent than root systems. The toxicity symptoms are, in general, similar to the deficiency symptoms. Toxic effects of Mn on plant growth have been attributed to several physiological and biochemical pathways, although the detailed mechanism is still not very clear. Higher O2 uptake and loss of control in Mn activated enzyme systems have been associated with Mn toxicity. Mn interferes with the uptake, transport and use of several essential elements including Ca, Fe, Cu, Al, Si, Mg, K, P and N. Excess of Mn reduces the uptake of certain elements and increases that of others. pH plays an important role in Mn uptake. Acidic pH causes a lack of substantial amount of nitrate as an alternative electron acceptor and leads to a high amount of Mn in leaves. High microbial activity, water logging and poorly structured soils cause severe Mn toxicity even in neutral soils. The molecular mechanism of Mn-tolerance is not yet clear. The level of tolerance is different in different species and seems to be controlled by more than one gene. Further information is required on the factors affecting the distribution, accumulation and membrane permeability of the metal in different plant parts and different species. Understanding of the genetic basis of Mn-tolerance is necessary to improve adaptation of crops against acid soils, water logging and other adverse soil conditions. 相似文献
9.
Asish K. Sen Amal K. Mukherjee Bhakti Guhathakurta Archana Dutta Dipti Sasmal 《Carbohydrate research》1979
On hydrolysis, the purified lipopolysaccharide (LPS) isolated from Vibrio cholera, Inaba 569 B, yielded glucose, mannose, a heptose behaving like d-glycero-l-manno-heptose and one behaving like d-glycero-l-gluco-heptose, 2-amino-2-deoxy-glucose, and glucuronic acid in the molar ratios of ~9:4:5:1:2:5. Studies on the LPS, the polysaccharide (PS), and carboxyl-reduced LPS showed that the PS has a branched structure, with (1→2)-linked mannopyranosyl and a heptopyranosyl, and (1→4)-linked glucopyranosyluronic and 2-amino-2-deoxyglucopyranosyl residues in the interior part of the molecule, and glucopyranosyl and heptopyranosyl residues as nonreducing end-groups. 相似文献
10.
Effects of various concentrations of streptomycin sulphate either alone or in combination with different cations and hormones on mungbean (Phaseolus aureus L.) seedling growth were studied. The relative inhibition of root growth was stronger than that of hypocotyl growth. Root growth inhibition was completely overcome by calcium, while other cations were ineffective. Inhibition of hypocotyl elongation could not be prevented by cations. IAA and GA3 were capable of relieving streptomycin inhibition but kinetin was ineffective. In the coleoptiles of streptomycin-treated rice (Oryza sativa L.) seedlings, there were accumulation of nucleic acids and decline in protein content resulting in increased RNA/protein and DNA/protein ratios. High nucleic acid content induced by streptomycin could be correlated with reduced activity of the nucleases. 相似文献