Scielo RSS <![CDATA[Biological Research]]> https://scielo.conicyt.cl/rss.php?pid=0716-976020080003&lang=en vol. 41 num. 3 lang. en <![CDATA[SciELO Logo]]> https://scielo.conicyt.cl/img/en/fbpelogp.gif https://scielo.conicyt.cl <![CDATA[<b>Microtubule proteins and their post-translational forms in the cerebrospinal fluid of patients with paraparesis associated with HTLV-I infection and in SH-SY5Y cells</b>: <b>An <i>in vitro </i>model of HTLV-I-induced disease</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300001&lng=en&nrm=iso&tlng=en HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is characterized by axonal degeneration of the corticospinal tracts. The specific requirements for transport of proteins and organelles to the distal part of the long axon are crucial in the corticospinal tracts. Microtubule dysfunction could be involved in this disease, configuring an axonal transport disease. We measured tubulin and its post-translational modified forms (acetylated and tyrosinated) in CSF of patients and controls, as well as tau and its phosphorylated forms. There were no significant differences in the contents of tubulin and acetyl-tubulin between patients and controls; tyrosyl-tubulin was not detected. In HAM/TSP, tau levéis were significantly reduced, while the ratio of pT181/total tau was higher in patients than in controls, this being completely different from what is reported in other neurodegenerative diseases. Phosphorylation at T181 was also confirmed by Mass Spectrometry analysis. Western Blotting with monospecific polyclonal antibodies against pS199, pT205, pT231, pS262, pS356, pS396, pS404 and pS422 did not show differences in phosphorylation in these residues between patients and controls. Treating human SH-SY5Y neuroblastoma cells, a well-known in vitro neurite retraction model, with culture supernatant of MT-2 cells (HTLV-I infected cell line that secretes the viral Tax protein) we observed neurite retraction and an increase in tau phosphorylation at T181. A disruption of normal phosphorylation of tau protein in T181 could result in its dysfunction, contributing to axonal damage. <![CDATA[<b>Misclassification probability as obese or lean in hypercaloric and normocaloric diet</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300002&lng=en&nrm=iso&tlng=en The aim of the present study was to determine the classification error probabilities, as lean or obese, in hypercaloric diet-induced obesity, which depends on the variable used to characterize animal obesity. In addition, the misclassification probabilities in animáis submitted to normocaloric diet were also evaluated. Male Wistar rats were randomly distributed into two groups: normal diet (ND; n=31; 3,5 Kcal/g) and hypercaloric diet (HD; n=31; 4,6 Kcal/g). The ND group received commercial Labina rat feed and HD animáis a cycle of five hypercaloric diets for a 14-week period. The variables analysed were body weight, body composition, body weight to length ratio, Lee Índex, body mass Índex and misclassification probability. A 5% significance level was used. The hypercaloric pellet-diet cycle promoted increase of body weight, carcass fat, body weight to length ratio and Lee Índex. The total misclassification probabilities ranged from 19.21% to 40.91%. In conclusión, the results of this experiment show that misclassification probabilities occur when dietary manipulation is used to promote obesity in animáis. This misjudgement ranges from 19.49% to 40.52% in hypercaloric diet and 18.94% to 41.30% in normocaloric diet. <![CDATA[<b>Hematopoietic potential of mouse placenta with the application of placenta flushing</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300003&lng=en&nrm=iso&tlng=en Several major vascular tissues, such as the aorta-gonad-mesonephros región (AGM), yolk sac, and fetal liver have been confirmed to possess hematopoietic function. Recently, the placenta has been demonstrated as another hematopoietic organ. However, it is not conclusive whether the placenta possesses hematopoietic ability. Therefore, we undertook a series of experiments to study the hematopoietic functions of placenta. Fetal blood circulation in the placenta is difficult to be eliminated and its interference in the study of placental hematopoiesis is inevitable. With the application of placental flushing, fetal blood contained in the placenta was eliminated. We then made the further study of placental hematopoiesis after the El2.5 placenta was flushed. Our studies showed that placental cells expressing Sca-1, CD117 and CD34 were mainly restricted to the embryonic vessels of E12.5 placenta. The results of fluorescence activated cell sorter (FACs) analysis and colony forming cells (CFC) assay demonstrated that both placenta and placental blood contained hematopoietic stem/progenitor cells (HS/PCs), including CFU-GMs, CFU-GEMMs, BFU-Es, and HPP-CFCs. The frequency of HS/PCs in the placenta was 2-3 times that of placental blood. Therefore, it is necessary to clear placental blood out of the placenta in the studies of the hematopoietic potential of placenta. The placenta still possessed the hematopoietic potential after the fetal blood is flushed out. These observations provide further evidences that the placenta is a hematopoietic organ, as has been proposed for other embryonic hematopoietic sites. <![CDATA[<b>Methodological considerations related to sleep paradigm using event related potentials</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300004&lng=en&nrm=iso&tlng=en In the last few decades, several works on event related potentials (ERPs hereafter) during sleep have been reported. In spite of numerous studies, clear methodological rules for this kind of study are often missing, making it difficult to valorize the scope of these results. We propose here a description of methodological aspects to be considered when evaluating ERPs during sleep. The use of Rechtschaffen and Kales rules versus automatic methods is assessed, plus the additional use of certain quantitative measures. Additionally, two topics are discussed which must be controlled in ERPs sleep studies: the First Night Effect, and sleep disturbances. Better control of experimental paradigms is relevant for the growth of the neuroscience of sleep. <![CDATA[<b>Biocidal activity of partially purified fractions from methanolic extract of Garcinia kola (Heckel) seeds on bacterial isolates</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300005&lng=en&nrm=iso&tlng=en The in vitro antibacterial activity of crude methanolic extract of the seeds of Garcinia kola was investigated. The extracts exhibited antibacterial activities with zones of inhibition ranging from 10 mm to 25 mm. The minimum inhibitory concentration of the diethyl ether fraction was between 0.313 and 5.0 mg/ml, while that of butanol fraction varied from 0.157 to 5.0 mg/ml. The butanol fraction killed about 77% of Bacillus anthracis and 79% of Escherichia coli cells within 120 min at a concentration of 5.0 mg/ml. Protein leakage from the B. anthracis and E. coli cells when exposed to the butanol and diethyl ether fractions was observed. We conclude that Garcinia kola seed extract has a broad spectrum antibacterial activity, with the butanol and diethyl ether fractions being bactericidal as exemplified by the killing rate and protein leakage regimes, which suggest cell membrane disruption as a mechanism of action of the extract. <![CDATA[<b><i>Daucus carota </i></b><b>as a novel model to evaluate the effect of light on carotenogenic gene expression</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300006&lng=en&nrm=iso&tlng=en Carotenoids are synthesized in prokaryotic and eukaryotic organisms. In plants and algae, these lipophilic molecules possess antioxidant properties acting as reactive oxygen species scavengers and exert functional roles in hormone synthesis, photosynthesis, photomorphogenesis and in photoprotection. During the past decade almost all carotenogenic genes have been identified as a result of molecular, genetic and biochemical approaches utilizing Arabidopsis thaliana as the model system. Studies carried out in leaves and fruits of A. thaliana and tomato determined that light regulates carotenoid biosynthesis preferentially through the modulation of carotenogenic gene transcription. In this work we showed for the first time that light induces accumulation of psy 1, pds and zds2 transcripts in leaves of Daucus carota (carrot), a novel plant model. In addition, modified roots of carrots exposed to light accumulate zdsl, whereas the pds gene is highly repressed, suggesting that some carotenogenic genes, which are expressed in roots, are regulated by light. Additionally, light negatively regulates the development of the modified carrot root in a reversible manner. Therefore, this suggests that light affects normal growth and carotenogenic gene expression in the modified root of carrot plants. The molecular insight gained into the light-regulated expression of carotenoid genes in this and other model systems will facilitate our understanding of the regulation of carotenoid biosynthesis to improve the prospects for the metabolic engineering of carotenoid production in plants. <![CDATA[<b>DNA methylation profile in diffuse type gastric cancer</b>: <b>evidence for hypermethylation of the BRCA1 promoter region in early-onset gastric carcinogenesis</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300007&lng=en&nrm=iso&tlng=en Diffuse type gastric carcinoma is the most aggressive type of gastric cáncer. This type of tumor is not preceded by precancerous changes and is associated with early-onset and hereditary syndromes. To test the hypothesis that DNA methylation profile would be useful for molecular classification of the diffuse type gastric carcinoma, DNA methylation patterns of the CpG Island of 17 genes were studied in 104 cases and 47 normal adjacent gastric mucosa by Methylation-specific PCR, Immunohistochemistry and Hierarchical clustering analysis. The most frequent methylated genes were FHIT, E-cadherin, BRCA1 and APC (>50%), followed by pl4, pl6, pl5, p73, MGMT and SEMA3B (20-49%). Hierarchical clustering analysis reveáis four groups with different clinical features. The first was characterized by hypermethylation of BRCA1 and younger age (&lt;45 years oíd), and the second by hypermethylation of pl4 and pl6 genes, male predominance and Epstein-Barr virus infection. The third group was characterized by hypermethylation of FHIT and antrum located tumors and the fourth was not associated with any clinical variables. In normal adjacent mucosa only the p73 gene was significantly less methylated in comparison to tumor mucosa. DNA methylation identified subgroups of diffuse type gastric cáncer. Hypermethylation of BRCA1 associated with young age suggests a role in early-onset gastric carcinoma. <![CDATA[<b>Ethanol Intake during Lactation Alters Milk Nutrient Composition and Growth and Mineral Status of Rat Pups</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300008&lng=en&nrm=iso&tlng=en Lactating Wistar rats were fed a liquid diet containing either ethanol [ethanol-fed group (EFG)] or an isocaloric amount of carbohydrate [pair-fed group (PFG)] from day 1 postpartum up to day 14 of lactation, to investigate micro/macronutrient milk composition and the mineral status of pups. EFG presented a reduction of daily milk production and milk composition was significantly higher in protein and lower in carbohydrate, while the lipid content was similar to that of PFG. When compared to PFG, the milk of EFG had a decreased proportion of C22:6 n-3 fatty acid and an increase in medium-chain fatty acids and of several minerals. Pups of EFG showed reduced growth and a lower concentration of Cu and Sr in plasma and lower concentrations of Ca, P and Cl, and higher concentrations of Cd in the brain. We conclude that maternal EtOH intake greatly impairs lactational performance and modifies the mineral status of pups. <![CDATA[<b>Positive effects of Green Tea on hepatic dysfunction, lipid peroxidation and antioxidant defence depletion induced by cadmium</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300009&lng=en&nrm=iso&tlng=en Cadmium (Cd) is a highly toxic environmental and industrial cumulative pollutant that affeets many organs, especially the liver. The present study was designed to evalúate the antioxidant effect of green tea on cadmium-induced hepatic dysfunction and oxidative stress in rats. Adult male Wistar rats were administered cadmium by injection of 20 emoles /kg bw/ every 3 days for six months. This study revealed significant (p < 0.05) liver dysfunction, lipid peroxidation and a decline in antioxidant enzyme activities in the liver of cadmium-treated rats compared to control animáis. Compared to control rats, the activities of lactate dehydrogenase (LDH), gammaglutamyl transferase (GGT), acid phosphatase (PAC), phosphatase alkaline (PAL), as well as bilirubin and thiobarbituric acid-reactive substances (TBARs), were significantly (p < 0.05) increased in Cd-treated rats. Moreover, antioxidant enzyme activities, such as superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase, were significantly (p < 0.05) decreased in the liver of cadmium-treated rats. The oral administration of 5% aqueous green tea extract, along with cadmium treatment for six months, caused a significant (p < 0.05) improvement in cadmium-induced toxicity by significantly decreasing (p < 0.05) the activities of enzymatic markers of liver dysfunction (LDH, GGT, PAC, PAL activities, as well as the bilirubin rate). Indeed, green tea extract significantly increased (p < 0.05) antioxidant enzymatic activities (SOD, Catalase, GPX) in rat liver, compared to those given cadmium alone. Thus, the oral administration of green tea, along with cadmium significantly (p < 0.05) improves cadmium-induced liver dysfunction and stress oxidant in rats' liver. <![CDATA[<b>Chlorpheniramine impairs spatial choice learning in telencephalon-ablated fish</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300010&lng=en&nrm=iso&tlng=en This work investigated the effect of the Hj receptor blockade in the forebrain of ablated Carassius auratus in a simple stimulus-response learning task using a T-maze test with positive reinforcement. The goldfish were submitted to surgery for removal of both telencephalic lobes five days before beginning the experiment. A T-shaped glass aquarium was employed, with two feeders located at the extremities of the long arm. One of the two feeders was blocked. The experimental triáis were performed in nine consecutive days. Each fish was individually placed in the short arm and confined there for thirty seconds, then it was allowed to swim through the aquarium to search for food for ten minutes (máximum period). Time to find food was analysed in seconds. Animáis were injected intraperitoneally with chlorpheniramine (CPA) at 16 mg/kg of body weight or saline after every trial, ten minutes after being placed back in the home aquarium. The results show that all the training latencies of the A-SAL group were higher than the latencies of the S-SAL group. The S-SAL group had decreased latencies from the second trial on, while the S-CPA group showed decreased latencies after the fourth trial. The A-SAL group showed reduced latencies after the fifth trial, but the A-CPA group mainteined the latencies throughout the experiment. This suggests that CPA impairs the consolidation of learning both on telencephalon ablated animáis and in sham-operated ones through its action on mesencephalic structures of the brain and/or on the cerebellum in teleost fish. <![CDATA[Gluconate as suitable potential reduction supplier in <i>Corynebacterium glutamicum</i>: Cloning and expression of <i>gntP </i>and <i>gntK </i>in <i>Escherichia coli</i>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300011&lng=en&nrm=iso&tlng=en Corynebacterium glutamicum is widely used in the industrial production of amino acids. We have found that this bacterium grows exponentially on a mineral médium supplemented with gluconate. Gluconate permease and Gluconokinase are expressed in an inducible form and, 6-phosphogluconate dehydrogenase, although constituvely expressed, shows a 3-fold higher specific level in gluconate grown cells than those grown in fructose under similar conditions. Interestingly, these activities are lower than those detected in the strain Escherichia coli Ml-8, cultivated under similar conditions. Additionally, here we also confirmed that this bacterium lacks 6-phosphogluconate dehydratase activity. Thus, gluconate must be metabolized through the pentose phosphate pathway. Genes encoding gluconate transport and its phosphorylation were cloned from C. glutamicum, and expressed in suitable E. coli mutants. Sequence analysis revealed that the amino acid sequences obtained from these genes, denoted as gntP and gntK, were similar to those found in other bacteria. Analysis of both genes by RT-PCR suggested constitutive expression, in disagreement with the inducible character of their corresponding activities. The results suggest that gluconate might be a suitable source of reduction potential for improving the efficiency in cultures engaged in amino acids production. This is the first time that gluconate specific enzymatic activities are reported in C. glutamicum. <![CDATA[<b>Código de Ética de la Sociedad de Biología de Chile</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300012&lng=en&nrm=iso&tlng=en Corynebacterium glutamicum is widely used in the industrial production of amino acids. We have found that this bacterium grows exponentially on a mineral médium supplemented with gluconate. Gluconate permease and Gluconokinase are expressed in an inducible form and, 6-phosphogluconate dehydrogenase, although constituvely expressed, shows a 3-fold higher specific level in gluconate grown cells than those grown in fructose under similar conditions. Interestingly, these activities are lower than those detected in the strain Escherichia coli Ml-8, cultivated under similar conditions. Additionally, here we also confirmed that this bacterium lacks 6-phosphogluconate dehydratase activity. Thus, gluconate must be metabolized through the pentose phosphate pathway. Genes encoding gluconate transport and its phosphorylation were cloned from C. glutamicum, and expressed in suitable E. coli mutants. Sequence analysis revealed that the amino acid sequences obtained from these genes, denoted as gntP and gntK, were similar to those found in other bacteria. Analysis of both genes by RT-PCR suggested constitutive expression, in disagreement with the inducible character of their corresponding activities. The results suggest that gluconate might be a suitable source of reduction potential for improving the efficiency in cultures engaged in amino acids production. This is the first time that gluconate specific enzymatic activities are reported in C. glutamicum. <![CDATA[<b>FE DE ERRATAS</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602008000300013&lng=en&nrm=iso&tlng=en Corynebacterium glutamicum is widely used in the industrial production of amino acids. We have found that this bacterium grows exponentially on a mineral médium supplemented with gluconate. Gluconate permease and Gluconokinase are expressed in an inducible form and, 6-phosphogluconate dehydrogenase, although constituvely expressed, shows a 3-fold higher specific level in gluconate grown cells than those grown in fructose under similar conditions. Interestingly, these activities are lower than those detected in the strain Escherichia coli Ml-8, cultivated under similar conditions. Additionally, here we also confirmed that this bacterium lacks 6-phosphogluconate dehydratase activity. Thus, gluconate must be metabolized through the pentose phosphate pathway. Genes encoding gluconate transport and its phosphorylation were cloned from C. glutamicum, and expressed in suitable E. coli mutants. Sequence analysis revealed that the amino acid sequences obtained from these genes, denoted as gntP and gntK, were similar to those found in other bacteria. Analysis of both genes by RT-PCR suggested constitutive expression, in disagreement with the inducible character of their corresponding activities. The results suggest that gluconate might be a suitable source of reduction potential for improving the efficiency in cultures engaged in amino acids production. This is the first time that gluconate specific enzymatic activities are reported in C. glutamicum.