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Biomedical subjects

R Roychoudhury

Publications and source records attributed to R Roychoudhury.

At least 19 recordsLinked to original sources
PubMed1997

Studies on 'zinc deficiency syndrome' in black bengal goats (Capra hircus) fed with fodder (Andropogon gayanus) grown on soil treated with an excess of calcium and phosphorus fertilizer.

Overliming and excessive application of superphosphate caused a zinc deficiency in the soil and so reduced the uptake of zinc by fodder plants. Bucks reared on such fodder had significantly (p < 0.01) less zinc in their hair compared with controls and suffered from 'conditioned zinc deficiency syndrome' with a significant (p < 0.01) loss of body weight, stunted growth, alopecia, lethargy, abnormal (kyphotic) gait, anorexia, digestive and respiratory problems. Oral supplementation with zinc sulphate very rapidly improved these conditions to near normality. Histological examination of samples of skin and testis from the zinc-deficient bucks revealed formation of excessive keratin, retention of nuclei in the stratum corneum and reduction in the width of the stratum granulosum in the skin, while samples of testis indicated degenerative changes, including atrophy of the seminiferous tubules, hyperplasia of the germinal epithelium and thickening of the walls of blood vessels.

Alopecia↗
PubMed1983

Construction of a broad-host-range kanamycin-resistant plasmid vector.

A new 10.2-kb plasmid, pIRL2, was constructed by using a 2140-bp DNA fragment carrying the Kmr gene and BamHI cohesive ends. These BamHI cohesive ends were used to trap the replicating DNA fragment from a partial Sau3A digest of the plasmid R300B. The plasmid contains unique EcoRI, SstI, HindIII, SmaI, SalI, and XhoI sites. These sites can be used as cloning sites without the loss of Kmr. A unique BglII site can be used as a cloning site by insertional inactivation of the Kmr structural gene, coding for neomycin phosphotransferase type II. The new plasmid carries the Sur and Smr genes of R300B. The direction of transcription from the neo promoter is clockwise, the same as that from the sul promoter. The plasmid retains the broad-host-range function of R300B, and thus it may be used for gene cloning in Rhizobium and Agrobacterium for genetic engineering of plant cells.

Cloning, Molecular↗
PubMed1983

Isolation of a new plasmid pIRL19: its use in construction of small vectors and detection of specific sequence in a foreign DNA.

A new plasmid, pIRL19, was constructed by ligating a 1875-bp HaeII fragment carrying the ampicillin-resistance (Apr) gene to a 370-bp HaeII fragment containing the replication origin of the plasmid pBR322. The plasmid essentially contains only the basic replicator and the Apr gene. This basic replicator provides a valuable initial building block for in vitro construction of other very small vectors with antibiotic-resistance determinants. To illustrate this potential, we have transferred the chloramphenicol-resistance (Cmr) gene and a part of the Apr gene from the plasmid pBR329 into pIRL19 such that the new plasmid pIRL20 acquired the Cmr gene and maintained the integrity of its Apr structural gene.

Base Sequence↗
PubMed1981

Expression in Escherichia coli of biologically active enzyme by a DNA sequence coding for the human plasminogen activator urokinase.

We have isolated clones of Escherichia coli strain K-12 that contain a hybrid pBR322 plasmid having a 4.2-kilobase insert of a DNA transcript of the mRNA of human plasminogen activator, urokinase. The bacterially produced enzyme has properties similar to those of urokinase from human fetal kidney cells. Both enzymes occur in discrete forms ranging from 32,000 to 150,000 daltons in size. They react with antibody to purified urokinase from human kidney cells, bind to a benzamidine-Sepharose column, and induce plasminogen-dependent lysis of a fibrin clot.

Base Sequence↗
PubMed1979

Influence of nucleotide sequence adjacent to duplex DNA termini on 3' terminal labeling by terminal transferase.

We have analyzed the effect of base-pairing at the exposed ends of Hinc II fragments of SV40 DNA on the efficiency of ribonucleotide incorporation catalyzed by terminal transferase. Wide variations in the labeling efficiency of individual DNA fragments have been observed. To elucidate the nature of this variation at the molecular level, we have correlated this effect with nucleotide sequence adjacent to the cleavage site. We found that a G:C base pair right at the exposed end drastically reduces the incorporation of ribonucleotides. Furthermore, the higher the number of G:C base pairs adjacent to the exposed end, the greater the reduction in labeling efficiency. From these results, we conclude that the labeling efficiency is determined by the degree of 'terminal breathing' of the DNA molecule at the exposed end of the duplex.

Base Sequence↗