Scielo RSS <![CDATA[Biological Research]]> https://scielo.conicyt.cl/rss.php?pid=0716-976020070001&lang=en vol. 40 num. 1 lang. en <![CDATA[SciELO Logo]]> https://scielo.conicyt.cl/img/en/fbpelogp.gif https://scielo.conicyt.cl <![CDATA[<b>Quantitative genetic variation of metabolism in the nymphs of the sand cricket, <i>Gryllus firmus</i>, inferred from an analysis of inbred-lines</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100001&lng=en&nrm=iso&tlng=en Compared with morphological and life history traits, quantitative genetic variation of metabolic and related traits in animals has been poorly studied. We used flow-through VC0(2) respirometry and simultaneous activity measurement on nymphs of the sand cricket {Gryllus firmus) from inbred lines to estimate broad-sense heritability of four metabolic variables. In addition, we measured a number of linear dimensions in the adults from the same inbred lines. There were significant multivariate effects of inbred lines for all traits and broad-sense heritability for physiological traits was 4.5%, 5.2%, 10.3% and 8.5% for average, resting, minimum and maximum C0(2) production in nymphs, respectively. Though the MANOVA indicated significant genetic variation among inbred lines in adult morphology, the broad-sense heritabilities were relatively low ranging from 0-18%. Our results indicate that the heritabilities of metabolic measures are large enough to potentially respond to selection <![CDATA[<b>Antioxidant activity of extract from <i>Polygonum cuspidatum</i></b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100002&lng=en&nrm=iso&tlng=en Numerous diseases are induced by free radicals via lipid peroxidation, protein peroxidation and DNA damage. It has been known that a variety of plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum cuspidatum Sieb. et Zuce has antioxidant activity is unknown. In this study, dried roots of Polygonum cuspidatum were extracted by ethanol and the extract was lyophilized. Free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays were employed to study antioxidant activities. The results indicate that the IC50 value oí Polygonum cuspidatum extract is 110 µg/ml in free radical scavenging assays, 3.2 µg/ml in superoxide radical scavenging assays, and 8 µg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum cuspidatum extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 641.1 ± 42.6 mg/g and 62.3 ± 6.0 mg/g. The results indicate that Polygonum cuspidatum extract clearly has antioxidant effects <![CDATA[<b>Multicolor fluorescence <i>in situ </i>hybridization with combinatorial labeling probes enables a detailed karyotype analysis of <i>Larix</i><i> principis-rupprechtii</i></b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100003&lng=en&nrm=iso&tlng=en The chromosomes (2n = 2x = 24) of Larix principis-rupprechtii are composed of six pairs of large metacentrics and six pairs of medium-sized submetacentrics. The identification of homologous pairs is hampered by their high degree of similarity at the morphological level in each group. As one of the most extensively used methods in molecular cytogenetics producing chromosome landmarks, fluorescence in situ hybridization (FISH) has significantly facilitated karyotype construction, especially in species with morphologically similar chromosomes. This study developed a simple but effective use of combinatorial labeling probes to distinguish chromosomes of Larix principis-rupprechtii by multicolor FISH. Three highly repetitive sequences in Larix were selected: 25S rDNA hybridized at all of the secondary constrictions of two pairs of metacentrics and the largest pair of submetacentrics; 5S rDNA hybridized at subtelomeric sites of one pair of metacentrics that also harboured 25S rDNA on different arms; LPD family sequences are tandem repeats hybridized at proximal regions of 22 chromosomes. The three different probes were labeled with only two different labels, hybridized to metaphase chromosomes of Larix principis-rupprechtii, simultaneously visualized, and unequivocally distinguished in a single FISH experiment. These multicolor FISH marks largely improved the karyotype analysis of Larix principis-rupprechtii <![CDATA[<b>Relationship between DAPI-fluorescence fading and nuclear DNA content</b>: <b>An alternative method to DNA quantification?</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100004&lng=en&nrm=iso&tlng=en In observations by confocal or conventional fluorescence microscopy, important factors should be considered in order to obtain accurate images. One of them, such as the fluorescence bleaching from highest intensity to lowest signal of fluorescence is a common problem with several DNA fluorochromes and especially for DAPI stain. The fluorescence of DAPI fades rapidly when it is exposed to UV light, under optimal conditions of observation. Although the fading process can be retarded using a mounting medium with antifading reagents, the photochemical process underlying the fluorescence decay has not yet been fully explained. In addition, no relationship between fluorescence fading and nuclear DNA content has been tested. In order to test this relationship, we measured by means of image analysis the DAPI-fluorescence intensity in several cellular types (spermatozoa, erythrocytes and haemocytes) during their fluorescence bleaching. An algorithm specifically built in MATLAB software was used for this approach. The correlation coefficient between nuclear DNA content and DAPI-fluorescence fading was found equal to 99%. This study demonstrates the feasibility to measure nuclear DNA content by fluorescence fading quantification, as an alternative method concurrently with image analysis procedures <![CDATA[<b>Human erythroid progenitors from adult bone marrow and cord blood in optimized liquid culture systems respectively maintained adult and neonatal characteristics of globin gene expression</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100005&lng=en&nrm=iso&tlng=en In vitro suspension culture procedures for erythroid progenitor cells make it possible for us to obtain large cultures of erythrocyte populations for the investigation of globin gene switching. In this study we aimed to establish optimized culture systems for neonatal and adult erythroblasts and to explore the globin expression patterns in these culture systems. To culture CD34+ cells purified from human umbilical cord blood (CB) and adult bone marrow (BM), we respectively replaced the fetal bovine serum (FBS) with human cord serum and human adult serum. These CD34+ cells were then induced to erythroid differentiation. All the globin mRNA (including á-, ξ-, β-, γ-and ε-globin), the hemoglobin (Hb)-producing erythroid cells and the cellular distribution of fetal hemoglobin (Hb F) were identified during the culture process. The results showed that the globin expression pattern during erythroid differentiation in our culture systems closely recapitulated neonatal and adult patterns of globin expression in vivo, suggesting that our specially optimized culture systems not only overcame the higher Hb F levels in the BM-derived CD34+ culture in FBS-containing medium but also eliminated the disadvantages of low cell proliferation rate and low globin mRNA levels in serum-free medium <![CDATA[<b>Influence of time at which oxytocin is administered during labor on uterine activity and perinatal death in pigs</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100006&lng=en&nrm=iso&tlng=en Oxytocin is extensively used to induce or augment uterine contractions, especially to facilitate the third stage of labor in humans. Administration of oxytocin to parturient sows reduces duration of labor whereas mortality of the offspring may remain unchanged. This study aimed to evaluate whether time of administration of oxytocin during parturition may alter the uterine response and fetal outcomes. Two hundred parturient sows were randomly assigned to intramuscularly receive either saline solution (control group) or oxytocin 0.083 IU/kg immediately after the delivery of the 1st, 4th or 8th piglet (groups O-1, 0-4 and 0-8, respectively). Uterine effects and fetal outcomes were registered in all groups. The duration of labor was 20-40 min shorter (P < 0.0001) and time interval between babies was reduced by 3-5 min (P < 0.0001) in the three groups receiving oxytocin. The duration and intensity of contractions, meconium-stained piglets and intrapartum deaths decreased as time at which oxytocin administered during labor was increased. In group 0-8, we observed approximately 70% less meconium-stained piglets and intrapartum deaths than in the control group. In conclusion, oxytocin administered at early phases of parturition to sows may increase duration and intensity of uterine contractions as well as adverse fetal outcomes <![CDATA[<b>Asexual Recombination in a <i>uvsH </i>Mutant of <i>Aspergillus nidulans</i></b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100007&lng=en&nrm=iso&tlng=en Mutations in the gene uvsH of Aspergillus nidulans result in increased spontaneous chromosome instability and increased intragenic and intergenic mitotic recombination in homozygous diploids. The aim of the present work was to obtain a uvs mutant of A. nidulans and to use it for the isolation of asexual recombinants (parameiotic segregants). The mutant uvsH, named B511, showed normal frequency of meiotic recombination in sexual crosses and high frequency of parameiotic segregants in the parasexual crossings with master strains (B511//A757 and B511//A288). Asexual haploid recombinants (parameiotic segregants), diploid and aneuploid segregants were recovered directly from the uvs//uvs+ heterokaryons (B511//A757 and B511// A288). Parameiotic segregants originated through mitotic crossing-over and independent assortment of chromosomes <![CDATA[<b>Expression of the carotenoid biosynthesis genes in <i>Xanthophyllomyces dendrorhous</i></b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100008&lng=en&nrm=iso&tlng=en In the yeast Xanthophyllomyces dendrorhous the genes idi, crtE, crtYB, crtl and ast are involved in the biosynthesis of astaxanthin from isopentenyl pyrophosphate. The carotenoid production and the kinetics of mRNA expression of structural genes controlling the carotenogenesis in a wild-type ATCC 24230 and in carotenoid overproducer deregulated atxS2 strains were studied. The biosynthesis of carotenoid was induced at the late exponential growth phase in both strains. However, the cellular carotenoid concentration was four times higher in atxS2 than in the wild-type strain in the exponential growth phase, suggesting that carotenogenesis was deregulated in atxS2 at the beginning of growth. In addition, the maximum expression of the carotenogenesis genes at the mRNA level was observed during the induction period of carotenoid biosynthesis in the wild-type strain. The mRNA level of the crtYB, crtl, ast genes and to a lesser extent the idi gene, decayed at the end of the exponential growth phase. The mRNA levels of the crtE gene remained high along the whole growth curve of the yeast. In the atxS2 strain the mRNA levels of crtE gene were about two times higher than the wild-type strain in the early phase of the growth cycle <![CDATA[<b>Evaluation of different DNA-based fingerprinting methods for typing <i>Photobacterium damselae </i>ssp. <i>piscicida</i></b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000100009&lng=en&nrm=iso&tlng=en This study evaluates the effectiveness of three different molecular techniques, repetitive extragenic palindromic PCR (REP-PCR), enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) and the random amplified polymorphic DNA (RAPD-PCR) for rapid typing of Photobacterium damselae ssp. piscicida strains isolated from different species of marine fish and geographic areas. The results obtained by the three methods showed that RAPD and ERIC-PCR were more discriminative for suitable rapid typing of Ph. damselae ssp. piscicida than REP-PCR. The analysis of DNA banding patterns generated by both molecular methods (RAPD and ERIC-PCR) clearly separated the strains into two main groups that strongly correlated with their geographic origin. Moreover, the REP-PCR analysis was less reproducible than the RAPD and ERIC-PCR methods and does not allow the establishment of genetic groups. RAPD and ERIC-PCR constitute valuable tools for molecular typing of Ph. damselae ssp. piscicida strains, which can be used in epidemiological studies of photobacteriosis infections