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I Dasgupta

Publications and source records attributed to I Dasgupta.

28 records · Page 2Linked to original sources
PubMed1994

Splicing in a plant pararetrovirus.

Analysis of expression in rice cells of plasmids in which an ATG-less chloramphenicol acetyl transferase ORF was placed in frame with the coding sequence of the pararetrovirus rice tungro bacilliform virus (RTBV) ORF IV, and which contained much of the upstream full-length transcript sequence of RTBV, gave evidence to suggest that a splicing event occurred. Reverse transcription/PCR of RNA from transfected protoplasts and from RTBV-infected plants yielded a product which confirmed that the 5' end of ORF IV was spliced in frame to a short ORF (sORF) in the RTBV leader sequence removing an intron of about 6.3 kb. Most of the translation is initiated at the ATG codon in the sORF with only about 10% at the ORF IV ATG codon. The efficiency of splicing appears to be inversely related to the length of the intron. The finding of splicing in a pararetrovirus blurs the differences between them and retroviruses but is in accord with the hypothesis that retroelements acquire genes and sequences which adapt them to specific niches.

Base Sequence↗
PubMed1991

An analysis of the sequence of an infectious clone of rice tungro bacilliform virus, a plant pararetrovirus.

The nucleotide sequence of an infectious clone of rice tungro bacilliform virus (RTBV) DNA has been determined. The circular genome has 8002 bp and one strand contains four open reading frames (ORFs). One ORF is potentially capable of encoding a protein of 24 kD (P24) and has no initiation (ATG) codon. The other three ORFs potentially encode proteins of 12 kD, 194 kD and 46 kD (P12, P194, P46) respectively. The functions of P24, P12 and P46 are unknown. Comparative analyses with retroviruses and Commelina yellow mottle virus suggest that the 194 kD putative product is a polyprotein that is proteolytically cleaved to yield the virion coat protein, a protease and replicase (reverse transcriptase and RNase H) characteristic of retroelements. The DNA sequence reveals other features which strongly support our belief that RTBV is a pararetrovirus. These include sequences at the mapped positions of two discontinuities in the virion DNA which are complementary to tRNA metinit and purine-rich, and may be the priming sites for minus- and plus-strand DNA synthesis respectively. As the positions of likely transcriptional signals suggest, a full-length viral transcript is observed by northern analysis. The predicted folding of the 645 bp 5'-region of this RNA resembles that of caulimoviruses. Comparisons with other reverse transcribing elements are discussed.

Amino Acid Sequence↗
PubMed1991

Rice tungro disease is caused by an RNA and a DNA virus.

We present evidence that rice tungro spherical virus (RTSV) has a genome of polyadenylated single-stranded RNA of about 10 kb whereas rice tungro bacilliform virus (RTBV) contains double-stranded circular DNA. RTBV DNA has been mapped and shown to have two discontinuities, one in each strand, at specific sites; it thus resembles that of the caulimoviruses. Gel electrophoresis of RTSV preparations revealed two protein bands (Mr 35K and 26K). RTBV yielded two major protein bands of 37K and 33K together with several minor species of higher and lower Mr which react with antiviral serum.

Capsid↗
PubMed1991

Rice tungro bacilliform virus DNA independently infects rice after Agrobacterium-mediated transfer.

In nature, rice tungro disease is caused by an RNA and a DNA virus complex, but we have obtained an independently infectious clone of rice tungro bacilliform virus (RTBV) DNA. Infectivity could be demonstrated only when a more than unit-length copy was cloned in the Agrobacterium binary vector Bin 19 and agroinoculated into rice plants. Rice plants thus agroinfected with cloned RTBV DNA showed typical symptoms of tungro disease, presence of viral DNA and bacilliform particles, and could be used as a source of virus to infect healthy plants by the green leafhopper (Nephotettix virescens). The importance of this infectious clone in understanding the molecular biology of RTBV and the rice tungro disease is discussed.

DNA, Viral↗
PubMed1988

Growth in height, weight and skinfold thickness of Bengali boys of Calcutta, India.

This is the first comprehensive growth study of male children of Bengali parentage. The cross-sectional survey was undertaken in an urban high school situated in the north of the Metropolitan City of Calcutta during 1982 and 1983. The sample consisted of 815 healthy Bengali boys aged 7-16 years. In this paper, data on height, weight, and skinfold thicknesses are presented including patterns of change in these physical traits with increasing age. Mean values of height or weight of the boys--not representative for all school-going boys of Calcutta--are distinctly above the national standards given by the Indian Council of Medical Research. They are, however, shorter and lighter than the well-off boys of India but have a similar magnitude of subcutaneous fat on arm. Peak annual incremental growth in height and weight occurs in Bengali boys at 12-13 years and 14-15 years, respectively. This is about one year earlier than in the well-off Indian, British, or American boys.

Adolescent↗
PubMed1984

Treatment of primary undifferentiated sarcoma of the liver with surgery and chemotherapy.

Primary undifferentiated sarcoma of the liver is a rare tumor with survival reliant on total excision of the tumor. The authors report such a tumor, initially nonresectable, in a 7-year-old girl whose tumor was successfully excised following treatment with cisplatin and Adriamycin (doxorubicin). The light and electron microscopic details of this patient's tumor are presented.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1983

Relationship between body weight and the incidence of positive axillary nodes at mastectomy for breast cancer.

The question, whether obesity is associated with an increased incidence of positive axillary nodes at mastectomy for breast cancer, was studied in two quite different hospital populations; one from a large urban teaching hospital (Montefiore) and one from a medium-sized Air Force medical center (Malcolm Grow). In the Montefiore population, the answer was "yes"; 67% of the node-positive patients, but only 31% of the node-negative patients were obese (20% or more above ideal weight) (p less than 0.05). In the Malcolm Grow population, the answer was "no"; 20% of the node-positive and 20% of the node-negative patients were obese. The different answers, we believe, are due to the biological differences between the populations; the Montefiore population was shorter (by an average of 1.7 inches), heavier (by an average of 20 lbs), and more obese. The incidence of obesity was about three times as high in the Montefiore population (52% versus 20%; p less than 0.02) and it contained a statistically distinct subpopulation of obese patients, while the few obese patients in the Malcolm Grow population constituted merely the upper tail of a unimodal log-normal distribution of weight in that population. We propose that it is possible to demonstrate a relationship of obesity to node-positivity in the Montefiore population but not in the Malcolm Grow population because obesity was highly prevalent in the former and almost nonexistent in the latter. It seems self-evident that it is not possible to demonstrate an effect of obesity in a population if that population manifests no significant obesity, statistically speaking, but disregarding this principle, we believe, may account for the controversy in the literature about whether obesity is a risk factor in breast cancer.

Adult↗