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Biomedical subjects

M Krauskopf

Publications and source records attributed to M Krauskopf.

At least 37 records · Page 2Linked to original sources
PubMed1990

[Overview of research in Chile by several epistemolometric indicators].

Scientific productivity in Chile was studied examining a data bank constructed with the publications indexed by the Institute for Scientific Information during 1987 and 1988. The bank excludes meeting abstracts and contains the full title of the published paper, the list of authors, addresses, field, and the nature of collaboration between two or more institutions. The articles were classified in different fields and tabulated according to the institution from which they originated. Although biology remains to be the more productive subject (26.5%) followed by medical sciences (23.9%) and chemistry (12.3%), articles in mathematics and physics continued their increase as in previous years. Using the scientometric indicators published by Braun et al., the impact of the research originated in Chile in biology, physics and mathematics was compared to that attained in Argentina, Brazil, Mexico and Venezuela. The role of the chilean National Research Fund and the output of the financed research projects were also analyzed. The successful results obtained during the first years in which the National Research Fund has been involved in the support of the scientific activity in Chile, confirms the need to strengthen its budget, according to the goals stated in the National Plan for Science and Technology for Development.

Chile↗
PubMed1988

Interaction of cibacron blue and anilinonaphthalenesulphonate with lipoproteins provides a new means for simple isolation of these plasma proteins.

The selective interaction of serum proteins with immobilized Cibacron Blue and the binding properties of the dye anilinonaphthalenesulphonate has been used to separate albumin and lipoproteins by affinity chromatography. The novel binding of anilinonaphthalenesulphonate to lipoproteins from the sera of lamprey, fish and mammals provides a simple procedure for the isolation of these plasma proteins, and permit preparation of specific antisera, tools particularly relevant for evolutionary and clinical studies.

Anilino Naphthalenesulfonates↗
PubMed1987

[Science and the university. Both need more attention].

Scientific output in Chile was studied examining the publications indexed by the Institute for Scientific Information during 1985 and 1986. Meeting abstracts were not considered. The articles were classified in different areas and tabulated according to the institution from which they originated. As in previous years, more than 80% of the papers were published by universities. The most productive subjects in these institutions were biology (33.2%), medical sciences (23.4%), and chemistry (16.9%). Outside universities the following fields were the most productive: medical sciences, astronomy, social sciences, biology and physics. To compare the overall output of chilean universities, in addition to their scientific publications, the number of degrees granted at the undergraduate and graduate levels was also evaluated. The proportion of governmental funds that each university received was used to standardize the indicators. Significant differences were observed which revealed that the chilean higher educational system is very heterogeneous. The indicators presented herein objective the overall output of each of the 24 chilean institutions of higher education funded by the government and provide the necessary insight to compare their contribution, and to respond to their urgent needs.

Bibliometrics↗
PubMed1984

Co-ordinate control of gene expression. Muscle-specific 7 S RNA contains sequences homologous to 3'-untranslated regions of myosin genes and repetitive DNA.

We have cloned and sequenced a complementary DNA copy (pSS48) of a novel muscle-specific, low molecular weight RNA, 7 S RNA, isolated from embryonic chick cardiac muscle cells. The hybridization pattern of plasmid pSS48 DNA to chick genomic DNA suggests that 7 S RNA is derived from the repetitive chick DNA with a repetition frequency of about 300 copies per haploid genome. Under low stringency, pSS48 DNA also hybridizes with high specificity to the single copy gene for chick myosin light chain (MLC) and to myosin heavy chain (MHC), and possibly to other co-ordinately expressed genes for chick muscle proteins. The sequence analysis of recombinant plasmids pSS48, pML10 and pMHC8, for 7 S RNA, MLC mRNA and MHC RNA, respectively, indicated that short nucleotide stretches homologous to 7 S RNA reside in the 3' untranslated regions of the respective genes. The 7 S RNA sequence appears to be highly specific for the chick muscle tissue, since RNA and DNA from several sources did not hybridize to pSS48 DNA. Furthermore, the 7 S RNA-like sequence(s) appears in chick blastodermal cells preferentially earlier than the onset of transcription of genes for major muscle proteins. These results, taken together, suggest a possible function for 7 S RNA in expression of muscle-specific genes during chick development.

Animals↗
PubMed1984

Fish liver protein synthesis during cold acclimatization: seasonal changes of the ultrastructure of the carp hepatocyte.

A cell-free system, active in protein synthesis, was constructed using ribosomes and supernatant factors isolated from the livers of winter-acclimatized carps. Upon seasonal adaptation, the hepatocytes of these fishes exhibited distinctive morphological features that were not sex dependent. The cytoarchitecture of the liver cell from summer carps is consistent with the cellular arrangements found when the rate of gene expression is high. During winter, several morphological features reveal that macromolecular synthetic activity may be clearly diminished.

Acclimatization↗
PubMed1984

Effects of insulin on the fine structure of hepatocytes from winter-acclimatized carps: studies on protein synthesis.

Male and female winter-acclimatized carps were injected with insulin. This treatment resulted in a sharp decrease in the liver glycogen content. Although an increase in the ribosomal RNA level was also observed, a cell-free system obtained from the hormone-treated fish exhibited less amino acid incorporation activity as compared to the control fish. However, polysomes from insulin-treated fish exhibited a higher amino acid incorporating activity when a soluble fraction of untreated winter carps was used. Insulin induced a profound change in the cytoarchitecture of the winter carp hepatocyte. The cytoplasm and nuclei showed all the features of the summer carp liver cell. The nucleolar components were totally intermingled suggesting a high rate of gene expression as in the case of the summer-acclimatized fish.

Acclimatization↗
PubMed1984

Cloning, physical mapping and genome organization of mitochondrial DNA from Cyprinus carpio oocytes.

The mitochondrial genome from Cyprinus carpio oocytes is a 10.5 megadalton, circular DNA molecule. The carp mitochondrial DNA was cloned in pBR325. Three recombinant plasmids accounted for the entire genome. Mapping of this DNA using 11 different restriction endonucleases is reported here. Both the large and small rRNA genes were then localized using Southern blot analysis. The subunit I of the cytochrome oxidase, the cytochrome b, the tRNAGlu and the URF 4 genes were localized by nucleotide sequence analysis and homology studies with human mtDNA. Our results suggest that a similar gene order has been maintained in the mitochondrial genomes of Chordata and support the hypothesis of a common ancestor for all vertebrate organelle genomes. This study constitutes the first report on the genome organization of a fish mtDNA and provides information for further investigation in connection with sequence determination, replication, and gene expression in carp mitochondria.

Animals↗
PubMed1983

Molecular cloning and sequencing of pheU, a gene for Escherichia coli tRNAPhe.

A recombinant plasmid (designated pID2) carrying the E. coli gene for tRNAPhe has been isolated from a plasmid bank constructed by the ligation of a total EcoRI digest of E. coli K12 DNA into the EcoRI site of pACYC184 DNA. The plasmid was selected by virtue of its ability to complement a temperature-sensitive lesion in the gene (PheS) for the alpha-subunit of phenylalanyl-tRNA synthetase. Crude tRNA isolated from such transformants exhibited elevated levels of phenylalanine acceptor activity. The tRNAPhe gene has been localized within the first 300 base pairs of a 3.6 kb SalI fragment of pID2. The sequence of the gene and its flanking regions is presented.

Base Sequence↗
PubMed1983

The nucleotide sequence of myosin light chain (L-2A) mRNA from embryonic chicken cardiac muscle tissue.

The nucleotide sequence of a cDNA clone (pML10) for chicken cardiac myosin light chain is described. The cDNA insert contains 613 nucleotides representing the entire coding sequence, with the exception of nine NH2-terminal amino acids, and the full 3'-non-coding region of 146 nucleotides. The missing 5' terminus of the mRNA, not represented in the clone pML10, was obtained by extension of the cDNA using a 43 nucleotide long internal EcoR1 fragment as a primer. The non-coding region contains several direct and inverted repeated sequences and the polyadenylation signal sequence AATAAA. The coding portion exhibits non-random usage of synonymous codons with a strong bias for codons ending in G and C.

Amino Acid Sequence↗
PubMed1983

Characterization of the 42-S nucleoprotein particles of Cyprinus carpio oocytes.

Previtellogenic oocytes of the fish Cyprinus carpio contain 42S nucleoprotein particles that are composed of two proteins of molecular weights 48,500 and 39,300 (molar ratio 2:1), tRNA and 5S RNA (molar ratio 3:1). The tRNA population embodied in the 42S particle contains all amino acid acceptor species but their distribution differs from that found in tRNA from mature oocytes.

Amino Acids↗
PubMed1983

[Scientific activity in Chile. Publications registered during the period 1980-1982].

Scientific activity in Chile from 1980 to 1982 was studied examining the publications registered by the Institute for Scientific Information. Abstracts were not considered. The list of publications which were produced in chilian laboratories was taken from the ASCA service. After classifying the areas to which each article belonged and also the university where the work was performed, the information was processed using a computer system. Almost 80% of the papers were published by universities. The more productive fields in the universities were biology (45,2%), medical sciences (25,9%) and chemistry (13,4%). Detailed data is presented for the biological sciences. The prevailing lack of support and encouragement for scientific research in Chile is discussed.

Chile↗
PubMed1982

Behavior of RNA and protein synthesis during the acclimatization of the carp. Studies with isolated hepatocytes.

1. Carp hepatocytes were isolated by dissociating the liver tissue with collagenase. The procedure yields viable cells with highly preserved ultrastructural and metabolic features. The isolated cells were able to self-aggregated and form tissue. 2. RNA and protein synthesis activity was significantly higher in the carp hepatocytes from summer acclimatized fish compared to the activity present in the cold adapted animals. 3. RNA synthesis assayed in carp hepatocytes suspensions obtained from summer and winter acclimatized fish exhibited a behaviour consistent with an inverse compensation to the cold acclimatization state, being apparently repressed, whereas protein synthesis did not show a compensatory activity.

Acclimatization↗