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M Krauskopf

Publications and source records attributed to M Krauskopf.

At least 19 recordsLinked to original sources
PubMed2003

An increased expression of nucleolin is associated with a physiological nucleolar segregation.

Nucleolar segregation is the most striking cellular phenotypic feature of cold-acclimatized carp and depicts the cyclical reprogramming that the physiology of the fish undergoes between summer and winter, where a clear differential expression of some nucleolar related genes occurs. We characterized carp nucleolin, a nucleolar protein involved in multiple steps of ribosome biogenesis, and evaluated its expression upon fish acclimatization. We show that the carp cDNA deduced amino acid sequence exhibits the same tripartite structural organization found in other species. Nevertheless, we observed that nucleolin mRNA expression was strongly induced in the cold-adapted carp as was the nuclear protein content, assessed by immunocytochemistry in liver sections. The physiological up-regulation of nucleolin in the cold-acclimatized carp, where rRNA transcription and processing are depressed concomitantly with the nucleolus segregation, is consistent with the notion that nucleolin plays a fundamental role in repressing rRNA synthesis.

Acclimatization↗
PubMed2001

In situ hybridization of somatolactin transcripts in the pituitary glands from acclimatized carp (Cyprinus carpio).

We isolated and cloned a carp somatolactin SL DNA fragment, of which 78% of the nucleotides were identical to the corresponding salmon SL sequence. The results obtained upon Northern blot hybridization of carp pituitary RNA allowed the identification of two transcripts as described for other fish. When the content of SL transcripts in pituitary sections from summer- and winter-acclimatized carp was quantified by in situ hybridization assays, we found no significant differences between the two seasons. In salmonids, plasma SL reaches higher levels in summer than in winter in synchrony with the water temperature cycle; in the eurythermal carp, however, the complex adaptive responses imposed by seasonal environmental changes do not seem to include the regulation of the somatolactin detected with the probe used at the transcriptional level in pituitary glands.

Acclimatization↗
PubMed2000

Environmental acclimatization of the carp modulates the transcription of beta-actin.

A cascade of mechanisms involving changes in gene expression are substantial to shape the adaptive responses that a eurythermal fish requires upon environmental changes in its habitat. We have previously shown that the cyclical reprogramming of rRNA transcription is a remarkable feature in carp under seasonal acclimatization. Using in situ hybridization and competitive RT-PCR we found significant differences in beta-actin transcripts, generally accepted to be coded by a typical housekeeping gene, in tissues from summer- and winter-acclimatized carp. The physiological differential beta-actin transcription herein reported places us on the alert for the reference genes estimated to be constitutive to quantitatively assess gene transcripts.

Actins↗
PubMed1999

Transcription factor pit-1 expression is modulated upon seasonal acclimatization of eurythermal ectotherms: identification of two pit-1 genes in the carp.

A second Pit-1 gene in carp (Cyprinus carpio), including the complete structural gene and 1.1 kb of promoter region, was identified and completely sequenced. The exon-intron structure was determined, and reverse transcription-polymerase chain reaction (RT-PCR) experiments suggest that only one Pit-1 splice variant is present in carp pituitary. The effect of seasonal acclimatization on the extent of Pit-1 gene expression was studied in summer- and winter-acclimatized carp. Quantitative RT-PCR analysis revealed a clear increase of Pit-1 mRNA in the pituitaries from summer-acclimatized carp compared with the winter-adapted fish. In situ hybridization of pituitary gland sections with riboprobes representing the complete 5'-transactivating region of carp Pit-1 depicted a significantly higher Pit-1 mRNA level in the rostral pars distalis of the summer-acclimatized fish where prolactin is expressed in a manner that resembles the seasonal increase observed in the proximal pars distalis and the pars intermedia. The cell- and temporal-specific transcription of Pit-1 supports its role in the molecular mechanisms that underly the acclimatization process undergone by eurythermal fish as a result of the physical effects of seasonal changes on their habitat.

Amino Acid Sequence↗
PubMed1999

APH-1, a POU homeobox gene expressed in the salt gland of the crustacean Artemia franciscana.

We characterized the first POU-homeoprotein in a crustacean (designated APH-1 for Artemia POU-Homeoprotein, EMBL Y15070). The amino acid sequence of the APH-1 POU-domain is identical, except for two residues, to that of the two class III POU proteins Cf1-a (Drosophila) and POU-M1 (Bombyx mori). Southern blot analysis suggests that crustaceans have only one class III POU gene. RT-PCR and whole-mount in situ hybridization show that APH-1 mRNA is present in larvae specifically in the salt gland, an organ which is involved in osmoregulation, and disappears in the adult.

Amino Acid Sequence↗
PubMed1998

Effect of seasonal acclimatization on the expression of the carp transcription factor Pit-1.

We isolated a clone comprising four exons of the carp Pit-1 gene. Using synthetic oligonucleotide probes derived from the carp Pit-1 sequence Pit-1 expression was assessed by in situ hybridization in pituitary sections from summer- and winter-acclimatized carp. Semiquantitative analyses of the hybridization signals revealed a significant higher Pit-1 expression in the proximal pars distalis (PPD) and pars intermedia (PI) of the pituitary glands from summer-acclimatized carp, compared to the winter-acclimatized fish. In both adaptive states, relative to the PPD and PI, only a basal Pit-1 expression was detected in the rostral pars distalis. Thus, during seasonal acclimatization of an eurythermal fish, Pit-1 seems to be involved in the mechanisms that underlie the compensatory response.

Acclimatization↗
PubMed1997

[A scientometric radiography of Revista Médica de Chile].

In the context of a festschrift to commemorate the 125th anniversary of the Revista Médica de Chile, "radiography" of the journal has been depicted using several scientometric indicators. Among the mainstream journals in the category of Medicine, General & Internal and taking into account the wide editorial coverage and the language of the publication that fulfills the need for the required social appropriation of science that the country requires, the Revista Médica de Chile portrays healthy and quite relevant. Among the articles published between 1981 and 1995, some concerning public health have reached, particularly, an impact which surpasses their mean expected citation rate.

Bibliometrics↗
PubMed1996

Identification of a Renibacterium salmoninarum DNA fragment associated with bacterial internalization into CHSE-cultured cells.

We report here the isolation of a Renibacterium salmoninarum DNA sequence capable of transforming a non-invasive Escherichia coli strain into a microorganism able to enter the fish cell line, CHSE-214. Immunofluorescence and electron microscopy techniques were used to assess the acquired invasive phenotype by HB101 E. coli cells, upon transformation with pPMV-189. This plasmid carries a 2282-bp R. salmoninarum DNA segment. The invasive phenotype is conserved upon deletion of approximately 1000 bp at the 3' end of the insert. The remaining segment contains an ORF region encoding a putative protein of about 30 kDa.

Amino Acid Sequence↗
PubMed1994

A PCR-based assay for the identification of the fish pathogen Renibacterium salmoninarum.

By means of a one-step one-tube extraction from less than 1 mg of tissue it is possible to identify, via the polymerase chain reaction, Renibacterium salmoninarum in salmon with bacterial kidney disease. A 149-bp DNA sequence unique to R. salmoninarum was specifically amplified and its nature confirmed by Southern hybridization using a non-isotopically labelled probe. The sensitivity of the approach allowed the detection of 22 R. salmoninarum cells. The procedure was successfully applied in the identification of the causative agent of bacterial kidney disease in kidney tissue from infected fishes.

Animals↗
PubMed1994

Prolactin gene expression and changes of prolactin pituitary level during the seasonal acclimatization of the carp.

The effect of seasonal acclimatization on the extent of prolactin (PRL) gene expression and on the content of this was studied in summer- and winter-carp (Cyprinus carpio) hormone pituitary glands. PRL content in the rostral pars distalis (RPD) was evaluated by immunocytochemistry using antibodies against a cross-linked synthetic peptide comprising the sequence of 15 amino acids which conform to the primary structure of carp PRL. To assess the level of PRL gene transcription, a 24-mer synthetic oligonucleotide probe whose sequence included nucleotides 2041-2064 located in exon V of the carp PRL gene, was used. Employing in situ hybridization assays, a high expression of PRL mRNA was observed in the RPD of summer-acclimatized carp. A negligible level of transcription was observed in tissue sections of pituitary glands from winter-acclimatized carp. Concurrently, immunodetection of the PRL-producing cells in the RPD revealed that the pituitary hormone level was significantly higher in the warm season-adapted carp.

Acclimatization↗
PubMed1993

Oral administration of insulin in winter-acclimatized carp (Cyprinus carpio) induces hepatic ultrastructural changes.

1. The intestinal absorption of insulin in carps was assessed examining the transepithelial passage of ingested gold-labeled hormone by electron microscopy. Insulin transfer occurred mainly through the intercellular spaces between the enterocytes. 2. When reaching the lamina propria, the gold-labeled hormone gathered predominantly around the granules of the granular cells, and therefore can enter the circulatory system via the blood capillaries which are found in close contact with these cells. 3. Winter-acclimatized carp were also capable of internalizing the hormone when fed with insulin. 4. Furthermore, the absorbed hormone revealed full activity in regard to the observed changes in the ultrastructure of the liver cells of the treated cold-adapted fish. 5. The fish ingesting the hormone underwent the same type of hepatic ultrastructure reprogramming observed when winter-acclimatized carps are injected intraperitoneally with insulin, i.e. conversion to a phenotype corresponding to hepatocytes from summer-adapted carp. 6. The oral absorption of insulin by winter-acclimatized fish and its effect in reversing the cold-adaptive state might be useful for the fish culturing industry.

Acclimatization↗
PubMed1993

Reprogramming of nucleolar gene expression during the acclimatization of the carp.

During seasonal acclimatization of eurythermal fish, the nucleolus of the hepatocyte undergoes ultrastructural reprogramming. In winter acclimatized carp, the nucleolar components are segregated, a condition that suggests a decreased transcription of rRNA. The same nucleolar reorganization was observed when pituitary cells from winter- and summer-acclimatized carp were examined. In situ analyses of nucleolar RNA revealed a marked lowering of RNA content in the segregated nucleoli. Accordingly, in vitro synthesis of RNA was shown to be significantly lower in pituitary tissue from cold-acclimatized fish where precursor accumulated. Conversely, in pituitary tissue from summer-adapted fish the rate and extent of synthesis and of rRNA processing was notably higher. The involvement of pre-rRNA processing events during seasonal acclimatization was corroborated by the strong differences of U3 RNA content detected by in situ hybridization in pituitary cells from summer- and winter-fish. When RNA polymerase I activity from both acclimatized states were assayed, no differences were detected. Thus, it appears that in fish RNA polymerase I itself does not play an important role in the control of nucleolar gene expression and the nucleolar gene expression reprogramming that the seasonal rearrangement represents might involve, among the many nucleolar-specific proteins, transcription factors.

Acclimatization↗
PubMed1993

[Medical research in Chile: quantitative indicators].

Diverse indicators were used to examine medical research in Chile. According to participation in Fondecyt projects, it was concluded that 420 persons were involved in medical sciences research and that 41.9% of them had no postgraduate title. During the eighties, there was a clear aging of the community dedicated to medical research. The scientific productivity was assessed through the inventory of publications in indexed journals. During the eighties, the number of articles in Clinical Medicine and Biomedical Sciences increased two-fold. The University of Chile published the greatest number of articles, followed by the Catholic University and, with a remarkable lower amount, other Universities. The impact of the published articles in Clinical Medicine and Biomedical Sciences was calculated from the citations that they generated from 1986 to 1988. Likewise, the articles registered in 1985 with the higher citation indexes were identified.

Adult↗
PubMed1992

Effect of seasonal acclimatization on estrogen-induced vitellogenesis and on the hepatic estrogen receptors in the male carp.

The levels of circulating vitellogenin in the plasma of male carp after induction by estradiol-17 beta was examined in summer- and winter-acclimatized fish. During the warm season male fish exhibited a clear vitellogenic response, whereas the fish adapted to the cold season did not. The evaluation of the hepatic estrogen receptors revealed that although steroid-binding affinity is not affected by seasonal acclimatization, the concentration of estrogen receptors certainly is. This was evidenced in estrogen treated fish. Summer-acclimatized carp featured a concentration of hepatic estrogen receptors 2.5 fold higher than the cold season adapted fish. The results suggest that the failure of estrogen to induce vitellogenesis in cold adapted carp may be due; at least in part, to a deficient up-regulation of hepatic estrogen receptors in the corresponding acclimatized state.

Acclimatization↗
PubMed1991

Molecular cloning of Renibacterium salmoninarum DNA fragments.

A Renibacterium salmoninarum enriched recombinant DNA library was constructed to isolate DNA fragments which could be used as probes to detect gene sequences specific for the causative agent of bacterial kidney disease in salmonid fish. One fragment of 149 base pairs was isolated and its specificity and sequence determined. This probe may prove useful in the design of diagnostic tests for the disease in asymptomatic fish and ova.

Actinomycetales↗
PubMed1991

Thromboembolism and bleeding tendency in congenital factor XII deficiency--a study on 74 subjects from 14 Swiss families.

In order to assess the clinical implications of hereditary F XII deficiency, all available members of Swiss families with F XII deficiency were investigated. Based on the F XII:C values and the family pedigree, the 74 subjects, aged 8-82 years, were classified as homozygotes/double heterozygotes for F XII deficiency (n = 18), as obligatory (n = 20) or possibly (n = 25) heterozygotes, respectively, and as normals (n = 11). None of the 18 subjects with F XII:C less than 0.01 U/ml and only one possibly heterozygous woman had an abnormal bleeding tendency, confirming the notion that Hageman trait generally does not result in a hemorrhagic diathesis. Two of the 18 subjects with severe F XII deficiency had suffered from venous thromboembolic disease at age less than 40 years. One heterozygous woman had a leg ulcer probably due to venous thrombosis. Thus, whereas homozygous F XII deficiency may be associated with an increased risk for venous thromboembolic disease, partial F XII deficiency is not, by itself, a strong risk factor for thrombosis. Whereas 17 of the 18 subjects with F XII:C less than 0.01 U/ml had no detectable F XII:Ag, one cross reacting material-positive F XII deficient subject (F XII:Ag = 0.11 U/ml) was identified. The dysfunctional F XII, present in this subject's plasma and tentatively called F XII Bern, is the fourth abnormal F XII molecule identified so far.

Adolescent↗
PubMed1990

[Use of a specific DNA probe to confirm sickle cell anemia in a caucasian woman].

A specific DNA probe containing part of the structural B-globulin gene was used to confirm the diagnosis of sickle cell anemia in a caucasian woman. The patient's genomic DNA was digested with the restriction endonuclease Dde I, fractioned by agarose electrophoresis and Southern blotting. Molecular hybridization was performed with the DNA probe prepared by chemical labelling with photobiotin. The beta 8/beta 8 genotype rendered only 1 fragment of length 376 bp. Upon digestion with Dde I, the DNA of an individual with the normal genotype containing the enzyme recognition sequence at the site of sickle cell mutation, resulted in 2 fragments of 201 and 175 bp. The pedigree of the patient's caucasian family was studied by Hb electrophoresis. Four out of 7 brothers carried the sickle cell trait.

Adult↗