Partial Characterization of Small Plasmids fromCorynebacterium renale

A naphthalene-degrading strain of corynebacteria, Corynebacterium renale, harbors multiple small plasmids designated pCR1, pCR2, pCR3, and pCR4 with sizes of 1.4, 3.2, 4.4, and 5.7 kb, respectively. Plasmid pCR1 of 1.4 kb is the smallest plasmid reported in this group of bacteria and is present in high copy number. Attempts to clone whole pCR1 in Escherichia coli were unsuccessful but two of its fragments (750 and 650 bp) could be separately cloned in it. The 4.4-kb plasmid, pCR3, bears considerable restriction pattern similarity to a 4.4-kb plasmid belonging to the pBL1 group of cryptic plasmid of corynebacteria but has no sequence homology, suggesting that pCR3 represents a new member of the 4.4-kb group of corynebacterial plasmids.     

Under what circumstances is the human XY bivalent tangled? A note on chromosomally-derived sterility

A microspread, early-mid diplotene nucleus of a man with a normal karyotype and presumably normal meiosis is compared with a similar, earlier described nucleus of a man with meiotic arrest, heterozygous for a (14;21) Robertsonian translocation (Rosenmann et al., 1985). The axes of the XY bivalent of normal diplotene have an extremely tangled configuration, whereas those of the meiotically-arrested cell are straight, recalling the shape of the XY which is normally found in early pachytene. The morphological reversal from the complex configuration to a simpler shape may be associated with reactivation of the sex chromosome(s). Such a reactivation may be responsible for the sterility of the carrier of the Robertsonian translocation which thus may be considered as chromosomally-derived. The diplotene cells shown here have autosomal bivalents with continuous axes and various degrees of focal separation as is typical for diplotene in general. The observations on axis continuity, bivalent segmental dilatations, and XY tanglement in diplotene are compared with findings by others in human ultrathin sectioned material.     

NADPH production from NADP+ with a glucose dehydrogenase system involving whole cells and immobilized cells of Gluconobacter suboxydans

Summary A convenient and efficient method of NADPH production from NADP⁺ has been established using a glucose dehydrogenase system involving whole cells and immobilized cells of Gluconobacter suboxydans IFO 3172. Using airdried cells of the bacterium, the optimum conditions for NADPH production were examined, including the cell and glucose concentrations, NADP⁺ concentration, pH, buffer and reaction temperature. Under suitable conditions, the conversion ratio and the amount of NADPH accumulated reached about 100% and 73 mg/ml of the reaction mixture, respectively, after 1-h reaction. Intact cells of the bacterium also showed high NADPH production even in the reaction mixture without a surfactant. The addition of Triton X-100 to the reaction mixture and freeze-thawing treatment of intact cells enhanced the production. The NADPH production method was further improved by using cells of the bacterium immobilized by entrapment in a -carrageenan gel lattice. The immobilized cells had almost the same enzymatic properties as the air-dried cells. The conditions for the continuous production of NADPH with an immobilized cell column were also investigated. NADPH was produced in a good yield (about 95%) with this continuous process.     

Blockade of voltage-dependent 42K efflux from rat brain synaptosome by minaprine and tetrahydroaminoacridine

The effect of minaprine (3-(2-morpholinoethylamino)-4-methyl-6-phenylpyridazine) on the K+ channels was studied by means of 42K efflux from rat brain synaptosomes, comparing the effects of 4-aminopyridine and 9-amino-1,2,3,4-tetrahydroacridine (THA). 42K efflux from rat brain synaptosomes was classified into five components: a resting component (R), a rapidly inactivating, voltage-dependent component (T), a slowly inactivating, voltage-dependent component (S) and a voltage-dependent, Ca(2+)-dependent component which is divided into a fast phase (CT) and a slower phase (CS). 4-Aminopyridine selectively inhibited 42K efflux of component T. THA blocked both S and T components. The inhibitory effect of THA on the 42K efflux of component S was quite pronounced compared with that of component T. Minaprine inhibited the 42K efflux of components S and T but the inhibitory effect on component S was observed with a lower dose of minaprine than that needed for the effect on component T. Minaprine had no effect on the Ca(2+)-dependent component while THA blocked component CT. 42K efflux of the resting component was not changed by minaprine, THA or 4-aminopyridine. These results suggest that minaprine blocks Ca2+ independent voltage-dependent K+ channel is involved in the pharmacological actions of minaprine.     

Domains for G-protein coupling in angiotensin II receptor type I: studies by site-directed mutagenesis.

To delineate domains essential for G-protein coupling in angiotensin II type 1 receptor (AT1), we mutated the receptor cDNA in the putative cytosolic regions and determined consequent changes in the effect of GTP analogs on angiotensin II (Ang II) binding and in inositol trisphosphate production in response to Ang II. Polar residues in targeted areas were replaced by small neutral residues. Mutations in the second cytosolic loop, carboxy terminal region of the third cytosolic loop or deletional mutation in the carboxyl terminal tail simultaneously abolished both the GTP-induced shift to the low affinity form and Ang II-induced stimulation of inositol trisphosphate production. These results suggest that polar residues in the second cytosolic loop, the carboxy terminal region of the third cytosolic loop, and the carboxy terminal cytosolic tail are important for G-protein coupling of AT1 receptor.     

Identification of amino acid residues of rat angiotensin II receptor for ligand binding by site directed mutagenesis.

To determine the specific mechanism of ligand binding to angiotensin (Ang II) receptor AT1, mutagenized rat receptor cDNAs were expressed transiently in COS-7 cells and the effect of the mutations on the binding to peptidic and non-peptidic ligands was analyzed by Scatchard plots. Mutation of Lys199 to Gln in the intramembrane domain strongly reduced the affinity to both [125I] Ang II and [125I]-1Sar, 8Ile-Ang II whereas mutation of two other Lys had little effect, indicating involvement of Lys199 in binding ligands. Replacement of each of four Cys in the extracellular domain markedly reduced binding affinity, indicating the importance of two putative disulfide bridges in the formation of active receptor conformation. Substitution of Asp for Asn in N-glycosylation had no effect on ligand binding or expression of the receptor. These studies indicate mutated receptors are expressed in the plasma membrane and are amenable for further detailed studies.     

Rat angiotensin II receptor: cDNA sequence and regulation of the gene expression

The nucleotide and amino acid sequences for rat type I angiotensin II receptor were deduced through molecular cloning and sequence analysis of its complementary DNAs. The rat angiotensin II receptor consists of 359 amino acid residues and has a sequence similar to G protein-coupled receptors. The expression of this receptor gene was detected in the adrenal, liver and kidney by Northern blotting. Sodium deprivation positively modulated the expression of the receptor gene in the adrenal. No detectable change was observed in the expression levels of this receptor gene between spontaneously hypertensive rats and Wistar-Kyoto rats in the tissues examined including the adrenal, brain, kidney and liver. Interestingly the expression of this receptor gene was developmentally regulated.     

Some structural features of the d-glucan from the seed of Mirabilis jalapa

The cotyledon of the seed of Mirabilis jalapa was found to contain a d-glucan. Methylation, periodate oxidation, and graded and enzymic hydrolysis studies were conducted to elucidate its structure. For every 38 d-glucosyl residues therein, 34 are (1→4)- and 3 are (1→3)-linked; the d-glucosyl unit at the branch point is linked through O-1, O-2, and O-4. In some places in the chain, there are at least three (1→3)-linked d-glucosyl residues in a sequence. Both α- and β-d-glucosidic linkages are present in the polysaccharide, the former preponderating. The d-glucan gave with iodine a faint blue color that had λ_max 420 nm.     

Antixenosis,tolerance and genetic analysis of some rice landraces for resistance to Nilaparvata lugens (Stål.)

Twenty-six rice landraces from West Bengal, India were evaluated for antixenosis and tolerance against brown planthopper (BPH) biotype 4 at the Bidhan Chandra Krishi Viswavidyalaya (BCKV), West Bengal. High levels of resistance were observed in six landraces, namely Badshabhog, Gamra, Haldichuri, Janglijata, Kalabhat and Khara. These phenotypically resistant rice landraces including Ptb33 exhibited lowest feeding rate, fecundity, nymphal and adult preference, survival, plant dry weight loss per mg of BPH dry weight produced (PDWL), and higher functional plant loss index (FPLI), more days to wilt and unhatched eggs compared with the susceptible check Swarna. All the landraces were classified into four major clusters at 10 unit distance by the scale of similarity during genetic diversity analysis through 21 gene-linked SSR markers of BPH resistance. Some phenotypically resistant landraces were gathered under the major cluster I indicating their analogous genetic history, while some were grouped with susceptible landraces exhibiting their genetic variation. The resistant landraces can be used as potential donors in the breeding programme for the development of rice varieties with resistance to BPH.     

Morphological and molecular divergence of Indian hill trout,Barilius bendelisis (Hamilton, 1822) stocks from different Rivers in Indo‐Burma biodiversity hotspot: Does river altitude and Dam play a role?

The present study explains the intraspecific variation in Indian Hill trout (Barilius bendelisis) on the basis of image based truss network system and D‐loop region of mtDNA. A total of 210 samples were collected from three different rivers (Teesta, Kameng and Myntudu River) of North East India in Indo‐Burma Biodiversity Hotspot. By using the software applications (tpsDig version 2.1 and PAST), a total of 25 morphometric measurements were generated from 10 landmarks. The Analysis of Variance (ANOVA), Factor Analysis (FA) and Discriminate Function Analysis (DFA) showed, out of the total variations, factor 1 explained 46.74% while factor 2 and factor 3 explained 27.14% and 11.92%, respectively. Using these variables 83.33% of the cross‐validated specimens were classified into distinct groups. Analysis of Molecular Variance (AMOVA) and pairwise Fst value for D‐loop region of mtDNA also showed high to medium level of genetic variation among the stocks and within the stocks. We conclude that the observed discrete stocks might be the result of changing environmental conditions in different rivers of the hotspot as the rivers are present at different altitudinal labels. It is also believed that the variation might be due to the construction of barrages across the river which hinder the mixing among the stocks.