Publications (20)22.59 Total impact
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Article: Effect of Temperature and Photoperiod on Prolactin Transcription in Cyprinus carpio
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ABSTRACT: We studied the effect of temperature and photoperiod on prolactin (PRL) gene expression in the pituitaries of summer-aclimatized carp (C. carpio). To assess the level of PRL gene transcription, we used a 24mer synthetic oligonucleotide probe derived from the known carp PRL gene sequence. Employing in situ hybridization assays, we observed high expression of PRL mRNA in the rostral pars distalis of summer-acclimatized carp in contrast to the almost negligible PRL transcription which occurs in the winter-acclimatized fish. When experimental combinations of long and short photoperiods with 10°C and 20°C environmental temperatures were studied, only a short photoperiod (8L-16D) in summer-acclimatized carp acclimated to a winter temperature (10°C) markedly depressed PRL gene expression. Our observations indicate that photoperiod constitutes a particularly relevant modulator in the neuroendocrine cascade that activates PRL transcription in the carp.ZOOLOGICAL SCIENCE 01/2009; · 0.95 Impact Factor -
Article: [A scientometric view of Revista Médica de Chile].
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ABSTRACT: During the last decade Revista Médica de Chile increased its visibility, measured on citations and impact factor. To perform a scientometric analysis to assess the performance of Revista Médica de Chile. Thomson's-ISI Web of Science and Journal Citation Reports QCR) were consulted for performance indicators of Revista Médica de Chile and Latin American journals whose subject is General and Internal Medicine. We also report the h-index of the journal, which infers quality linked to the quantity of the output. According to the h-index, Revista Médica de Chile ranks 4 among the 36 journals indexed and published by Argentina, Brazil, Chile and México. The top ten articles published by Revista Médica de Chile and the institutions with the higher contribution to the journal, were identified using citations. In the Latin American region, Brazil relevantly increased its scientific output. However, Argentina, Chile and México maintain a plateau during the last decade. Revista Médica de Chile increased notoriously its performance. Its contribution to the Chilean scientific community dedicated to Medicine appears to be of central value.Revista medica de Chile 09/2008; 136(8):1065-72. · 0.33 Impact Factor -
Article: Gene structure and seasonal expression of carp fish prolactin short receptor isoforms.
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ABSTRACT: The complex adaptive mechanisms that eurythermal fish have evolved in response to the seasonal changes of the environment include the transduction of the physical parameter variations into neuroendocrine signals. Studies in carp (Cyprinus carpio) have indicated that prolactin (PRL) and growth hormone (GH) expression is associated with acclimatization, suggesting that the pituitary gland is a relevant physiological node in this adaptive process. Also, the distinctive pattern of expression that carp prolactin receptor (PRLr) protein depicts upon seasonal acclimatization supports the hypothesis that PRL and its receptor clearly are involved in the new homeostatic stage that the eurythermal fish needs to survive during the cyclical changes of its habitat. Here, we characterize the first prolactin receptor gene in a teleost and show that its expression is not associated with alternative promoters, unlike in humans and rodents. Using the regulatory region to direct the transcription of green fluorescent protein (GFP) in zebrafish embryos, we mapped the appearance of this hormone receptor during fish development. This is the first report identifying a fish prolactin receptor gene expressing transcript isoforms encoding for short forms of the protein (45 kDa). These have been found in osmoregulatory tissues of the carp and are regulated in connection with the seasonal acclimatization of the fish.Journal of Cellular Biochemistry 04/2007; 100(4):970-80. · 2.87 Impact Factor -
Article: Low awareness of the link between science and innovation affects public policies in developing countries: The Chilean case.
Scientometrics. 01/2007; 72:93-103. -
Article: Ultrastructural changes of the carp (Cyprinus carpio) hepatocyte nucleolus during seasonal acclimatization.
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ABSTRACT: The eurythermal fish carp (Cyprinus carpio) adjusts to the seasonal changes in the temperature and photoperiod of its habitat through diverse cellular and molecular mechanisms. We have observed that ribosomal biogenesis is modulated during the acclimatization process and correlates with profound phenotypic changes, reflecting a seasonal-dependent ultrastructural appearance of the nucleolar components. Previous studies using classical techniques showed that in winter-adapted carp the nucleolus appears to be segregated. In the present work, we have reassessed the nucleolar ultrastructural organization of the carp in summer- and winter-adapted fish by using more specific cytochemical and immunocytological techniques. The acetylation method provided evidence that the nucleolar organization is different between winter- and summer-adapted carp. In winter-adapted fish the fibrillar component appears as a unique mass surrounded by several granular caps, whereas in summer-adapted carp the fibrillar component forms few cordons surrounded by granular masses. The nucleolar structure and distribution of the condensed chromatin observed varies upon seasonal acclimatization. In winter the nucleolar chromatin is densely packed in masses that surround the nucleolus, whereas during summer it displays a rather looser organization formed by filaments that not only surround the nucleolus, but also go through the nucleolar body. Using the TdT (terminal deoxynucleotidyl transferase)-immunogold labelling technique, we detected condensed and decondensed nucleolar chromatin, and found some labelling of fibrillar components in both seasons. When liver tissue from summer-adapted carp was treated with AMD (actinomycin D), we observed that the rearrangement of the nucleolar components and condensed chromatin were similar to that found in winter-adapted fish, with differences in the distribution of the perinucleolar chromatin. The acetylation and TdT-immunogold labelling experiments indicated that the rearrangement of the nucleolar components of winter-adapted carp is very similar to the AMD-treated summer-adapted carp nucleolus, with the latter representing the repression of the ribosomal biogenesis that occurs during the cold season. Nevertheless, the distribution of the condensed perinucleolar chromatin in winter-adapted carp compared with AMD-treated cells suggests that the transcription of rRNA genes in winter-adapted fish is less strongly inhibited and does not lead to the classical segregation of the nucleolus of that described after AMD treatment. In addition, we have confirmed that carp hepatocyte nucleoli comprise only two main structural compartments: a fibrillar component and a granular component. Fibrillar centres were not observed.Biology of the Cell 09/2006; 98(8):457-63. · 3.60 Impact Factor -
Article: Seasonal environmental changes regulate the expression of the histone variant macroH2A in an eurythermal fish.
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ABSTRACT: Adaptation to cold and warm conditions requires dramatic change in gene expression. The acclimatization process of the common carp Cyprinus carpio L. in its natural habitat has been used to study how organisms respond to natural environmental changes. At the cellular level, adaptation to cold condition is accompanied by a dramatic alteration in nucleolar structure and a down regulation of the expression of ribosomal genes. We show that the enrichment of condensed chromatin in winter adapted cells is not correlated with an increase of the heterochromatin marker trimethyl and monomethyl K20H4. However, the expression of the tri methyl K4 H3 and of the variant histone macroH2A is significantly increased during the winter season together with a hypermethylation of CpG residues. Taking into account the properties of macroH2A toward chromatin structure and dynamics and its role in gene repression our data suggest that the increased expression of macroH2A and the hypermethylation of DNA which occurs upon winter-acclimatization plays a major role for the reorganization of chromatin structure and the regulation of gene expression during the physiological adaptation to a colder environment.FEBS Letters 11/2005; 579(25):5553-8. · 3.54 Impact Factor -
Article: Seasonal environmental changes modulate the prolactin receptor expression in an eurythermal fish.
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ABSTRACT: Eurythermal fish have evolved compensatory responses to the cyclical seasonal changes of the environment. The complex adaptive mechanisms include the transduction of the physical parameters variations into molecular signals. Studies in carp have indicated that prolactin and growth hormone expression is associated with acclimatization, suggesting that the pituitary gland is a relevant physiological node in the generation of the homeostatic rearrangement that occurs in this adaptive process. Here, we report the cloning and characterization of a full-length carp prolactin receptor cDNA, which codes for the long form of the protein resembling that found in mammalian prolactin receptors. We identified up to three receptor transcript isoforms in different tissues of the teleost and assessed cell- and temporal-specific transcription and protein expression in carp undergoing seasonal acclimatization. The distinctive pattern of expression that carp prolactin receptor (cPRLr) depicts upon seasonal acclimatization supports the hypothesis that prolactin and its receptor are clearly involved in the new homeostatic stage that the eurythermal fish needs to survive during the cyclical changes of its habitat.Journal of Cellular Biochemistry 06/2004; 92(1):42-52. · 2.87 Impact Factor -
Article: [The lack of a suitable recognition of the existing capacities affects the scientific development in Chile].
Biological research 02/2003; 36(2):139-40. · 1.03 Impact Factor -
Article: Genomic organization of the rDNA cistron of the teleost fish Cyprinus carpio.
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ABSTRACT: The seasonal adaptation of the teleost Cyprinus carpio to the cyclical changes of its habitat demands physiological compensatory responses. The process involves profound nucleolar adjustments and remarkable changes in rRNA synthesis, which affects ribosomal biosynthesis. In this context, we have demonstrated that the synthesis of several proteins involved in ribosomal biogenesis as protein kinase CK2, ribosomal protein L41 and nucleolin, as well as U3 snoRNP, are differentially regulated in summer-acclimatized carp compared to the cold-season adapted fish. To understand the mechanisms involved in the seasonal regulation of rRNA gene transcription, we have been studying the carp rDNA cistron structure. Because the cis-elements that regulate the expression of the tandem organized ribosomal genes are located in the non-transcribed intergenic spacer (IGS), we analyzed the primary structure of the carp rDNA gene IGS. The gene organization is similar to that described from other vertebrate species, including numerous repetitive sequences, the transcription start site, and some potential cis-elements such as ribosomal enhancers, proximal terminator and transcriptional terminators. Ribosomal DNA is a remarkable case of gene duplication and has been used as a model to test the concerted evolution theory. We performed sequence comparison analyses of 18S rRNA coding sequences from carp with different species, data with which an unrooted phylogram was constructed.Biological research 02/2003; 36(2):241-51. · 1.03 Impact Factor -
Article: Gene structure of the carp fish ribosomal protein L41: seasonally regulated expression.
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ABSTRACT: The seasonal acclimatization of the carp fish demands physiological compensatory responses. The process involves profound nucleolar adjustments and remarkable changes in rRNA synthesis, which affect ribosomal biogenesis. We have documented that protein kinase CK2, whose activity is related to ribosomal protein L41 and the regulation of rRNA synthesis, was expressed in notably higher amounts in summer-acclimatized carp compared to the cold-season adapted fish. Thus, we approached the study of the functional genomics of carp L41 protein. We report the first cloning of a fish L41 gene encoding the highly conserved 25 amino acids, including approximately 1700 bp regulatory upstream region and the 3(') polyadenylation signal, plus the isolation and characterization of two different L41 cDNAs. We found a clear differential expression of L41, which follows the same pattern as protein kinase CK2beta that transcribes at higher levels in the summer-acclimatized carp than it does in the winter-adapted fish.Biochemical and Biophysical Research Communications 08/2002; 295(3):582-6. · 2.48 Impact Factor -
Article: [A epistemometric view of some biological disciplines in Chile].
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ABSTRACT: During the last decade the articles published by Chilean Research Centers grew 1,73 which compares to the 2.34 fold increase of mainstream research articles registered as a whole in Latin America. However, the relative impact of the Chilean publications surpassed that of Latin America. In Biological Sciences, traditionally the strongest research area within Chile, Latin America also shows a steeper slope of growth. Qualitatively, biological disciplines in Chile are comparable to those published in Latin America although in Chile there are specialties as Physiology that surpass the average world's impact. The scientometric data is consistent with the fall in individual grants that the Chilean Research Fund (FONDECYT) has been allocating during the last decade.Biological research 02/2002; 35(1):95-9. · 1.03 Impact Factor -
Article: Environmental acclimatization of the carp modulates the transcription of β‐actin
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ABSTRACT: 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 β-actin transcripts, generally accepted to be coded by a typical housekeeping gene, in tissues from summer- and winter-acclimatized carp. The physiological differential β-actin transcription herein reported places us on the alert for the reference genes estimated to be constitutive to quantitatively assess gene transcripts. J. Cell. Biochem. 80:223–228, 2000. © 2000 Wiley-Liss, Inc.Journal of Cellular Biochemistry 01/2001; 80(2):223 - 228. · 2.87 Impact Factor -
Article: Oral administration of insulin in winter-acclimatized carp (Cyprinus carpio) induces hepatic ultrastructural changes
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ABSTRACT: 1.1. 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.2.2. 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.3.3. Winter-acclimatized carp were also capable of internalizing the hormone when fed with insulin.4.4. 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.5.5. 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.6.6. 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.Comparative Biochemistry and Physiology Part A: Physiology. 01/1994; -
Article: Cloning, physical mapping and genome organization of mitochondrial DNA from Cyprinus carpio oocytes
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ABSTRACT: 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.MGG - Molecular and General Genetics 07/1984; 196(1):43-52. -
Article: Carp apolipoprotein a-i intestinal absorption and transfer into the systemic circulation during the acclimatization of the carp (Cyprinus carpio)
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ABSTRACT: 1.1. Synthesis of apo A-I in the mucosa of the proximal intestine of the carp could not be measured despite the use of different experimental approaches. Nevertheless, the content of apo A-I in the intestinal tissue was identified by immunocytochemistry.2.2. Transepithelial apo A-I transfer from the intestinal lumen into the lamina propria was visualized in tissue sections. Summer-acclimatized fish exhibited a strong intemalization of the apolipoprotein whilst winter-acclimatized carp did not. However, the latter resembled the summer-Actapted fish on insulin treatment.3.3. The absorbed apo A-I concentrated in the granular cells of the lamina propria, surrounding the granules, and was released into the systemic circulation probably through blood capillaries.4.4. The transfer of undegraded apo A-I into the circulatory system was confirmed by using biotin-labeled carp HDL-apolipoproteins as a probe.5.5. The absorptive process responded to thermal Actaptation. During cold-acclimation the transfer process was negligible with respect to the warm-Actapted state.6.6. Apo A-I bile content was confirmed. It was suggested that at least part of the HDL used for the transport of lipids proceeds from the bile.Comparative Biochemistry and Physiology Part A: Physiology. -
Article: Differences in the tRNA population between summer and winter acclimatized carp
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ABSTRACT: 1.1. Transfer RNA isolated from the livers of winter and summer acclimatized male carps was fractionated by two-dimensional polyacrylamide electrophoresis.2.2. Significant changes in the distribution of the tRNA isoacceptor species were observed.3.3. The adjustment of the tRNA population to the needs of the protein synthetic machinery during the acclimatization process correlates with the cyclic carp liver cell ultrastructural changes previously observed, and provides a new approach to gain knowledge about the mechanisms involved in the compensatory response to thermal adaptation.Comparative Biochemistry and Physiology Part B: Comparative Biochemistry. -
Article: In vivo levels of aminoacyl-tRNA species during acclimatization of the carp Cyprinus carpio
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ABSTRACT: 1.1. The behaviour of the tRNA population during the acclimatization process was studied, examining the intracellular levels of aminoacylated-tRNAs in livers from summer and winter adapted carps (Cyprinus carpio).2.2. The in vivo content of Val-tRNA, Ala-tRNA and Met-tRNA decreased significantly during the summer season, in which Val was 80%, Ala 47% and Met 54% with respect to the values attained in winter.3.3. The half-life for the nonenzymic deacylation showed significant variations for the two populations of aminoacyl-tRNA obtained from summer and winter acclimatized fish.Comparative Biochemistry and Physiology Part B: Comparative Biochemistry. 67(1):167-170. -
Article: Prolactin gene expression and changes of prolactin pituitary level during the seasonal acclimatization of the carp
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ABSTRACT: 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.Comparative Biochemistry and Physiology Part B: Comparative Biochemistry. -
Article: Seasonal Acclimatization of the Carp Involves Differential Expression of 5.8S Ribosomal RNA in Pituitary Cells
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ABSTRACT: In the carp, nucleolar reorganization is one of the most remarkable features of the cellular adjustment that occurs upon seasonal acclimatization. To assess if the level of cellular expression of a specific rRNA is maintained between both seasonal adaptive states, we isolated a carp 5.8S rRNA gene. Sequence analyses showed its high conservation during evolution. The level of expression of 5.8S rRNA was determined by in situ hybridization assays in pituitary sections from summer- and winter-acclimatized carp. The quantification of the positive hybridization signals demonstrated a statistically significant difference between the acclimatization states. Transcription of 5.8S rRNA was considerably higher in summer- than in winter-acclimatized carp. These results indicate that the level of rRNA expression in eurythermal fish is not comparable between seasons and suggest that rRNA genes may be not constitutive. Thus, rRNA transcription should be used with caution as a reference to quantitate transcripts that are modulated as part of the acclimatization process in eurythermal fish.Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. -
Article: Characterization of the major plasma apoliproteins of the high density lipoprotein in the carp (Cyprinus carpio)
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ABSTRACT: 1.1. Carp plasma DHL was isolated by a single chromatographic procedure using Affi-Gel Blue. Neither LDL nor VLDL were detected.2.2. Thus, HDL which comprises almost 40% of the total carp plasma proteins, also constitutes the major lipoprotein fraction in this fish, yielding two apolipoproteins: apo A-I and apo A-II with molecular weight of 29,500 and 12,000, respectively. These are present in a one to one molar ratio.3.3. Carp apo A-I and apo A-II lack cysteine and tryptophan. Although some similarities in the amino acid composition exist with respect to the same apoproteins from other organisms, antisera raised against carp apo-I cross-reacted only, and very slightly, with its rainbow trout counterpart.4.4. No reaction was detected with lamprey and the nothotenidae robalo fish.5.5. Four plasmatic apo A-I isoforms were identified. No differences were observed in carps acclimatized to winter and summer.Comparative Biochemistry and Physiology Part B: Comparative Biochemistry.
Top co-authors
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Institutions
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1984–2009
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Austral University of Chile
- Facultad de Ciencias
Puerto Montt, Region de Los Lagos, Chile
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2001–2008
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Universidad Andrés Bello
Santiago, Region Metropolitana de Santiago, Chile
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