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Biomedical subjects

M Wu

Publications and source records attributed to M Wu.

At least 559 records · Page 31Linked to original sources
PubMed1987

Protein-DNA interaction within one cloned chloroplast DNA replication origin of Chlamydomonas.

A partially purified algal protein mixture which supports in vitro DNA replication consists of soluble proteins and proteins extracted from thylakoid membrane. The membrane extract is essential for the specific initiation of replication at a displacement loop (D-loop) site previously mapped by electron microscopy. D-loop site and its flanking sequences have been cloned and sequenced. In this study, fragment-retention assays using various subclones of the sequenced region indicate that some proteins in the membrane extract bind strongly and specifically with a 494 bp restriction fragment which partially overlaps the D-loop site. Protein gel analyses of the protein-DNA complex identify three DNA-binding polypeptides with apparent molecular weights of 18, 24 and 26 kDA, respectively. Treatment with chloramphenicol, an inhibitor of chloroplast protein synthesis, for 1 h has no obvious effect on the contents of the 24 or 26 kDa polypeptides but significantly reduces the content of the 18 kDa polypeptide in the membrane extract.

Animals↗
PubMed1987

Localization of a r-protein gene within the chloroplast DNA replication origin of Chlamydomonas.

In our previous study of chloroplast (Cp) DNA replication in Chlamydomonas reinhardtii, one D-loop site with its flanking regions was cloned and sequenced. The D-loop site mapped by electron microscopy (EM) overlaps with an open reading frame (ORF) potentially coding for a polypeptide of 136 amino acids. In this report, the corresponding D-loop isolated from another species of Chlamydomonas was sequenced. An ORF was also detected. Sequence comparison indicated that most conserved sequences between these two cloned origins are located within the ORF. Amino acid sequences of these two ORFs are highly conserved. The corresponding sequence for this ORF in the tobacco Cp genome was located by a Southern blotting analysis. Since the complete sequence data of Cp DNAs from a liverwort and from tobacco have been determined in 2 Japanese laboratories recently, it has been possible for us to show that this ORF encodes a protein homologous to the Cp ribosomal protein (r-protein) L16, by sequence comparison.

Amino Acid Sequence↗
PubMed1987

[G-banded chromosome analysis of bone marrow and peripheral blood cells from small cell lung cancer (SCLC) patients].

Detailed G-banded chromosome analysis was carried out on the bone marrow and/or PHA-stimulated peripheral blood cells from 17 SCLC patients (14 males and 3 females), who were diagnosed cytologically or pathologically or both. Twelve of them had no prior treatment and 16 had a heavy smoking history. High chromosome aberration rates were found in the bone marrow (31% for average structural aberration rate and 63% for numerical aberration rate) and peripheral blood cells (37% for average structural aberration rate and 49% for numerical aberration rate). The smoking index, as a whole, was positively correlated to the structural chromosome aberration rate, indicating that smoking is one of the most important environmental factors in causing chromosome aberrations. But some patients gave a high aberration rate dis-proportional to their smoking index, suggesting that genetically determined susceptibility to smoking or even other factors also play an important role. The structural chromosome aberrations in the bone marrow and peripheral blood cells were mainly clustered on chromosome 3 and chromosomes 1, 9 and 11, respectively. The aberration types were manifold and complicated. No consistent or specific aberration as del 3p14-23 for SCLC was found in this study.

Bone Marrow↗
PubMed1986

Gene mapping on human metaphase chromosomes by in situ hybridization with 3H, 35S, and 32P labeled probes and transmission electron microscopy.

A method based on in situ hybridization, autoradiography and transmission electron microscopy for mapping genes on human metaphase chromosomes is presented. Successful mapping of the tandemly repeated rDNA genes and of two nucleic acid probes, N-myc and probe 3 (Kanda et al. 1983), that are amplified in a homogeneously staining region (HSR) of the neuroblastoma cell line, IMR-32 is described. By using sufficiently thin AgBr emulsions, it is possible to obtain observable grains and good resolution with probes radiolabeled with 3H, 35S, or 32P, but the former gives the best results. We observe that neither of the two probes, N-myc and probe 3, has a uniform spatial distribution along the HSR and that the distributions of the two probes differ from each other. These observations support previous studies which indicated that the formation of an HSR is a more complex process than uniform amplification of a single DNA segment to form an n-fold set of perfect tandem repeats. The present study shows that the electron microscopic method is useful for extending the results of light microscopic studies for problems where higher resolution mapping is needed.

Cell Line↗
PubMed1986

Prokaryotic promoters in the chloroplast DNA replication origin of Chlamydomonas reinhardtii.

In Chlamydomonas reinhardtii, one displacement loop region which initiates the replication of chloroplast DNA was located on a 1.05 kb restriction fragment. This fragment was cloned and sequenced. In this report, the galK expression plasmid, pKO1 was used to screen for the presence of any prokaryotic promoter within the cloned fragment. The insertion of 2 AluI fragments yielded galK+ colonies. Sequence analyses of these AluI inserts revealed prokaryotic promoter consensus regions. Cloning into pKOTWI and subsequent DNA sequencing were used to determine the promoter-active orientation of each insert. Two back-to-back prokaryotic promoters were mapped on a 79 bp AluI fragment located within the displacement loop region.

Chlamydomonas↗
PubMed1986

Nutrition education at the point of purchase: the foods for health project evaluated.

Foods for Health, a nutrition education and research program sponsored by the National Heart, Lung, and Blood Institute and Giant Food, Inc., was designed to demonstrate the feasibility of cardiovascular nutrition education at the point of purchase, specifically, in the supermarket. To evaluate the program's effectiveness, measures of consumer awareness, knowledge, and food purchases were determined before, during, and after the campaign. The program was conducted in the Washington, D.C., area, with Baltimore, Maryland, area stores serving as controls. At the conclusion of the campaign, Washington shoppers showed a significant increase in knowledge scores, while these scores decreased in the Baltimore area. The gain in correct knowledge scores for Washington shoppers compared with Baltimore shoppers was 9% for food fat and cholesterol content and 11% for the relationship between dietary fat and blood cholesterols levels. The food sales data indicate no apparent differences attributable to the intervention. Issues that might account for the lack of a significant change in food purchases, such as cost and the markets' individual sales promotion campaigns, are discussed, and recommendations for the design of future projects are made.

Community Participation↗
PubMed1986

Subpallidal projections to the mesencephalic locomotor region investigated with a combination of behavioral and electrophysiological recording techniques.

Locomotor activity was increased as a function of current intensity in a series of rats with chronic stimulating electrodes in the tegmental pedunculopontine nucleus. Single pulse stimulation of these same mesencephalic locomotor region (MLR) sites antidromically activated more than one-quarter of the neurons sampled in the subpallidal area. In a second series of rats locomotor activity was increased by chronic stimulation of the zona incerta as well as by chronic stimulation of MLR. Approximately one-quarter of subpallidal neurons sampled were antidromically activated by single pulse stimulation of zona incerta and/or MLR. Thirty-one of the subpallidal neurons were antidromically activated by stimulation of both zona incerta and MLR and, according to the results of the reciprocal collision test, about half this number had branching projections to the zona incerta and MLR. These observations provide additional evidence that subpallidal-MLR neurons are associated with locomotion.

Animals↗
PubMed1986

Structure and function of a chloroplast DNA replication origin of Chlamydomonas reinhardtii.

Chloroplast DNA replication in Chlamydomonas reinhardtii is initiated by the formation of a displacement loop (D-loop) at a specific site. One D-loop site with its flanking sequence was cloned in recombinant plasmids SC3-1 and R-13. The sequence of the chloroplast DNA insert in SC3-1, which includes the 0.42-kilobase (kb) D-loop region, as well as 0.2 kb to the 5' end and 0.43 kb to the 3' end of the D-loop region, was determined. The sequence is A+T-rich and contains four large stem-loop stuctures. An open reading frame potentially coding for a polypeptide of 136 amino acids was detected in the D-loop region. One stem-loop structure and two back-to-back prokaryotic-type promoters were mapped within the open reading frame. The 5.5-kb EcoRI fragment cloned in R-13 contains the 1.05-kb SC3-1 insert and its flanking regions. A yeast autonomously replicating (ARS) sequence and an ARC sequence, which promotes autonomous replication in Chlamydomonas, have been mapped within the flanking regions [Vallet, J.-M. & Rochaix, J.-D. (1985) Curr. Genet. 9, 321-324]. Both R-13 and SC3-1 were active as templates in a crude algal preparation that supports DNA synthesis. In this in vitro system, chloroplast DNA synthesis initiated near the D-loop site.

Journal Article↗
PubMed1986

An intervening sequence in an unusual histone H1 gene of Tetrahymena thermophila.

An intervening sequence of 254 base pairs interrupts the coding region of the single gene for macronuclear histone H1 of the ciliated protozoan, Tetrahymena thermophila. The intervening sequence has splice junctions similar to those found in RNA polymerase II genes of other organisms. No obvious similarities are observed between this intron and the self-splicing intervening sequence of the Tetrahymena ribosomal gene. The derived amino acid sequence describes a small extremely basic H1 protein missing most of the central hydrophobic domain that is conserved in all other H1 proteins. Macronuclei divide amitotically, without chromosome condensation, suggesting the conserved globular domain of H1 plays a role in higher-order chromatin structure.

Amino Acid Sequence↗
PubMed1986

The studies of malignant transformation of human epithelial cells induced by diethyl-nitrosamine (NDEA) in vitro.

This is the first report on the diethylnitrosamine-induced malignant transformation of human epithelial cells derived from fetal kidney. The transformed cells have prolonged life span and aneuploid karyotypes. They also form anchorage independent colonies in soft agar. With additional one or two NDEA treatments, these cells could elicit poorly differentiated carcinomas in immunosuppressed new-born rats. This experiment indicates that the human fetal kidney cells seem to be a good material for studying the mechanisms of carcinogenesis of human epithelial cell.

Animals↗
PubMed1986

Malignant transformation of human fetal lung fibroblasts induced by nitrosamine compounds in vitro.

This report, for the first time, demonstrates that diethyl-nitrosamine (NDEA) and a new nitrosamine compound-N-1-methylacetonyl-N-3-methylbutyl-nitrosamine (MAMBNA), which are suspicious carcinogens of esophageal cancer (EC) in Linxian, Henan Province, are able to cause the malignant transformation (altered morphology, extended life span, anchorage independent growth, invasiveness, tumorigenicity, etc.) of normal diploid fibroblasts derived from human fetal lung. Besides, the preselection for clonogenic cells, which seem to be more readily to be transformed, in soft agar before carcinogen treatment, could be considered as one of the useful ways in establishment of a model system of malignant transformation of human fibroblasts in vitro.

Cell Transformation, Neoplastic↗