Scielo RSS <![CDATA[Biological Research]]> vol. 42 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Leptospirosis research</b>: <b>fast, easy and reliable enumeration of mobile leptospires</b>]]> Leptospirosis caused by Leptospira interrogans is the most widespread zoonosis and a major public health problem worldwide. Based on light-scattering and absorption, quantification of leptospires using UV-VIS spectroscopy was used as an indirect counting technique by measuring the optical density and comparing this to automated direct counting using a counting chamber in combination with imaging and analyzing software. Two serovars, Bangkok and Copenhagenii, from log-phase growth were used for the establishment of standard curves. They were found to be linear and slightly different in gradient for each serovar. The ease, rapidity, and reliability of these two adapted and optimized counting techniques may provide a useful alternative enumeration technique for leptospirosis research. <![CDATA[<b>Genistein affects the morphology of pituitary ACTH cells and decreases circulating levels of ACTH and corticosterone in middle-aged male rats</b>]]> The soybean phytoestrogen, genistein, is increasingly consumed as an alternative therapeutic for age-related diseases, namely cardiovascular conditions, cancer and osteoporosis. However, despite the beneficial effects on health, concern has been raised that this isoflavone also acts as an endocrine-disrupting chemical. The aim of this study was to examine the effects of genistein on immunohistomorphometric features of pituitary adrenocorticotropic cells (ACTH) and blood concentrations of ACTH and corticosterone in orchidectomized middle-aged male rats. Sixteen-month-old Wistar rats were divided into sham-operated (SO), orchidectomized (Orx) and genistein-treated orchidectomized (Orx+G) groups. Genistein (30mg/kg/day) was administered subcutaneously for three weeks, while the control groups received the vehicle alone. ACTH cells were identified by the peroxidase-antiperoxidase (PAP) immunohistochemical procedure. Circulating concentrations of ACTH and corticosterone were measured by immunoassay. Orchidectomy reduced (p<0.05) the cell volume and the relative volume of ACTH cells in comparison to SO rats. Genistein treatment further decreased (p<0.05) these morphometric parameters and reduced (p<0.05) circulating ACTH and corticosterone concentrations by more than 20% in comparison to both Orx and SO rats. In conclusión, genistein modulated the immunohistomorphometric features of ACTH cells and decreased blood ACTH and corticosterone levels, which supports evidence that this isoflavone affects the hypothalamic-pituitary-adrenal axis and suppresses glucocorticoid hormone secretion. <![CDATA[<b>Ultrastructural changes of the egg apparatus associated with fertilisation of natural tetraploid <i>Trifolium pratense L. </i>(Fabaceae)</b>]]> The aim of this study is to describe the ultrastructural changes of the egg apparatus associated with fertilisation of the natural tetraploid Trifolium pratense. The pollen tube enters one of the synergids through the filliform apparatus from the micropyle. Before the entry of the pollen tube into the embryo sac, one of the synergids begins to degenerate, as indicated by increased electron density and a loss of volume. This cell serves as the site of entry for the pollen tube. Following fertilization, the vacuolar organisation in the zygote changes; in addition to the large micropylar vacuole, there are several small vacuoles of varying size. Ribosomal concentration increases significantly after fertilisation. In T. pratense, ultrastructural changes between the egg cell and zygote stages are noticeable. Several marked changes occur in the egg cell because of fertilisation. The zygote cell contains ribosomes has many mitochondria, plastids, lipids, vacuoles. After fertilization, most of the food reserves are located in the integument in the form of starch. The zygote shows ultrastructural changes when compared to the egg cell and appears to be metabolically active. <![CDATA[<b>Ethanol in low chronic dose level attenuates major organic effects in malnourished rats</b>]]> The aim of the present study was to evaluate the chronic toxicity of ethanol low blood levels in malnourished rats. Female Wistar rats (220 g) were subjected to either an ad libitum diet (W, well-nourished, n=10) or food restriction (M, malnourished, n=10). Water (WW and MW) or ethanol solution (W5% and M5%) was offered to half of each nutritional group (n=5) as the only fluid source. The treatment was continued for two months. After sacrifice, blood biochemical parameters and macroscopic, histologic and morphometric evaluation of the liver were performed. Results indicated that: Ethanol consumption was higher in malnourished rats and minimized body weight loss in malnourished rats, while it decreased the body weight gain in well-nourished ones. Behavioral ethanol intoxication was more severe in malnourished rats. Malnutrition decreased hematocrit and hemoglobin but, on the other hand, ethanol was a protective factor of that effect (hemoglobin: MW 10.6 mg/dl / ME 13.02 mg/dl, p< 0.05). Ethanol increased the relative liver weight of both well-nourished and malnourished rats. Ethanol intake minimized iron pigment, collagen area and binuclear hepatocyte/ field increased by malnutrition. These data are in accordance with previous reports which showed ethanol as an important source of calories and, even chronically, ethanol still attenuates the effects of malnutrition. <![CDATA[<b>Recombinant <i>in vitro </i>assembled hepatitis C virus core particles induce strong specific immunity enhanced by formulation with an oil-based adjuvant</b>]]> In the present work, immunogenicity of recombinant in vitro assembled hepatitis C virus core particles, HCcAg.120-VLPs, either alone or in combination with different adjuvants was evaluated in BALB/c mice. HCcAg.120-VLPs induced high titers of anti-HCcAg.120 antibodies and virus-specific cellular immune responses. Particularly, HCcAg.120-VLPs induced specific delayed type hypersensitivity, and generated a predominant T helper 1 cytokine pro file in immunized mice. In addition, HCcAg.120-VLPs prime splenocytes proliferate in vitro against different HCcAg.120-specific peptides, depending on either the immunization route or the adjuvant used. Remarkably, immunization with HCcAg.120-VLPs/Montanide ISA888 formulation resulted in a significant control of vaccinia virus titer in mice after challenge with a recombinant vaccinia virus expressing HCV core protein, vvCore. Animals immunized with this formulation had a marked increase in the number of IFN-γ producing spleen cells, after stimulation with P815 cells infected with vvCore. These results suggest the use of recombinant HCV core particles as components of therapeutic or preventive vaccine candidates against HCV. <![CDATA[<b>Superoxide dismutase and catalase</b>: <b>tissue activities and relation with age in the long-lived species <i>Margaritifera margaritifera</i></b>]]> Free radicals are extremely reactive and produce damage and modify cell functions. Furthermore, superoxide dismutase and catalase are believed to play a key role in the enzymatic defence of the cells. Indeed, some authors have argued that reduced free-radical damage could explain increased longevity. Margaritifera margaritifera is one of the longest-lived animals in the world (up to 100-200 years). Furthermore, this organism may serve as a useful model for gerontologists interested in exploring the mechanisms that promote long life and the slowing of senescence. The present study estimated for the first time individual enzymatic activity for superoxide dismutase isozymes (Cu,Zn-SOD and Mn-SOD) and catalase in tissue preparations of gills, digestive glands and mantles of two natural populations of M. margaritifera. Superoxide dismutase activities showed significant differences in the tissues analysed of specimens from the same river and in specimens from different rivers for the same tissue. Catalase activity levels also showed significant variation, but differences among tissues, within tissues or between rivers were of relatively little interest. We failed to find any relationship between individual enzymatic activities and the age estimated for each mussel. Indeed, the wide variation found in activity levels can be principally interpreted as an adaptation to the unpredictable and changing nature of freshwater natural habitats. <![CDATA[<b>Molecular Cloning, Sequence Identification and Tissue Expression Profile of Three Novel Sheep (<i>Ovis aries</i>) Genes - BCKDHA, NAGA and HEXA</b>]]> The complete coding sequences of three sheep genes- BCKDHA, NAGA and HEXA were amplified using the reverse transcriptase polymerase chain reaction (RT-PCR), based on the conserved sequence information of the mouse or other mammals. The nucleotide sequences of these three genes revealed that the sheep BCKDHA gene encodes a protein of 313 amino acids which has high homology with the BCKDHA gene that encodes a protein of 447 amino acids that has high homology with the Branched chain keto acid dehydrogenase El, alpha polypeptide (BCKDHA) of five species chimpanzee (93%), human (96%), crab-eating macaque (93%), bovine (98%) and mouse (91%). The sheep NAGA gene encodes a protein of 411 amino acids that has high homology with the alpha-N-acetylgalactosaminidase (NAGA) of five species human (85%), bovine (94%), mouse (91%), rat (83%) and chicken (74%). The sheep HEXA gene encodes a protein of 529 amino acids that has high homology with the hexosaminidase A(HEXA) of five species bovine (98%), human (84%), Bornean orangután (84%), rat (80%) and mouse (81%). Finally these three novel sheep genes were assigned to GenelDs: 100145857, 100145858 and 100145856. The phylogenetic tree analysis revealed that the sheep BCKDHA, NAGA, and HEXA all have closer genetic relationships to the BCKDHA, NAGA, and HEXA of bovine. Tissue expression profile analysis was also carried out and results revealed that sheep BCKDHA, NAGA and HEXA genes were differentially expressed in tissues including muscle, heart, liver, fat, kidney, lung, small and large intestine. Our experiment is the first to establish the primary foundation for further research on these three sheep genes. <![CDATA[<b>Polytypic and polymorphic cytogenetic variations in the widespread anuran <i>Physalaemus cuvieri </i>(Anura, Leiuperidae) with emphasis on nucleolar organizing regions</b>]]> We investigated the NOR distribution in ten populations of Physalaemus cuvieri from different regions of Brazil and Argentina. A high variability in NOR pattern was observed and provided a useful tool in grouping several populations. The specimens from the state of Tocantins, northern Brazil, could easily be distinguished from all the other analyzed populations, since its karyotype presented NORs in the chromosome pairs 1,3,4 and 10 (and sometimes also in chromosome 5), and several pericentromeric C-bands. A NOR-site in chromosome 9 characterized three populations from the northeastern region of Brazil. Interestingly, the P. cuvieri populations located in opposite extremes of the geographic distribution had, as a fixed condition, the presence of NORs in 8q int and llp. Besides interpopulational divergences, intrapopulational variability was observed in the number of NORs, except for populations from the states of Bahia and Minas Gerais, which are boundary states respectively in the northeastern and southeastern regions of Brazil. In relation to NOR size, interindividual variations occurred in all Brazilian and Argentinean populations. Additionally, intraindividual variability in NOR size was detected in specimens from Minas Gerais. The data presented herein revealed substantial geographic polytypic variation in P. cuvieri and indicated that a taxonomic reexamination of this species is necessary. <![CDATA[<b>Hepatoprotective effect of Cinnamon extracts against carbon tetrachloride induced oxidative stress and liver injury in rats</b>]]> Cinnamon is used to flavor most foods in Arabian countries. The aim of this study was to evaluate the medicinal importance, reflecting an important trend in research. The hepatoprotective activity of aqueous and ethanolic extracts of cinnamon was investigated against carbon tetrachloride (CC1(4)) induced lipid peroxidation and hepatic injury in rats. The elevated serum AST and ALT enzymatic activities induced by CC1(4) were significantly restored to near normal by oral administration of 200 mg/kg of either extracts once daily for 7 days, as compared to untreated rats. There was a significant elevation in the level of liver malondialdhyde (MDA), while the activities of antioxidant enzymes superoxide dismutase and catalase (SOD and CAT) were significantly decreased in CC1(4) intoxicated rats. The results obtained indicated that ethanolic extract has more potent hepatoprotective action than water extract against CC1(4) by lowering the MDA level and elevating antioxidants enzymes activities (SOD and CAT). The possible mechanism of this activity may be free radical-scavenging polyphenol compounds. The hepatoprotective properties were documented by the histopathological data obtained. Consequently, this extract can be used as a therapeutic regime in treatment of some hepatic disorders without any side effects. Further study will be done for separation and identification of active components and for testing antitumor activity. <![CDATA[<b>Quantification of Japanese Quail Eggshell Colour by Image Analysis</b>]]> The Japanese quail lays eggs with colourful and patterned shells which make the eggshell colour difficult to classify. In this study, the method of measuring colour of patchy eggs using image analyses and its power to discriminate among individual variation were established. Estimated repeatability for egg colour and proportion of patterned areas was high (>0.58), suggesting intermedíate or high heritability of eggshell colour characteristics. Three components have been identified as significant in discriminant function analysis. These three components explained 91.4% of the total variance in egg colour characteristics. In cluster analysis, 78.3% of the eggs that were collected from 15 females were correctly classified. This study indicates that eggshell colour characteristics can be reliably studied by image analyses and that this method can provide a unified character list for future examinations and interpretations of quail egg characteristics. <![CDATA[<b>Analysis of the Intercaste Transcriptional Profile of <i>Melipona scutellaris </i>Latreille, 1811 (Hymenoptera, Apidae, Meliponini) by mRNA Differential Display</b>]]> In colonies of Melipona scutellaris Latreille, 1811 workers can be found with four ganglion nerve cells, a morphological characteristic of the queen. It is hypothesized that these workers, called intercastes, or phenocopies, are phenotypically-like workers, but genotypically identical to queens due to this specific trait. Workers with the same number of ganglion as queens seem to be intercastes between queens and workers. Our objective was to analyze the mRNA pro files of workers, queens, and intercastes of M. scutellaris through DDRT-PCR. Three hundred (300) pupae with white eyes were collected and externally identified according to the number of abdominal nerve ganglions: workers (5 ganglions), queens (4 ganglions) and intercastes (4 ganglions). The analysis identified differentially expressed transcripts that were present only in workers, but absent in intercastes and queens, confirming the hypothesis, by demonstrating the environmental effect on the queen genotype that generated phenotype-like workers. <![CDATA[<b>Nicotine-evoked cytosolic Ca<sup>2+</sup> increase and cell depolarization in capillary endothelial cells of the bovine adrenal medulla</b>]]> Endothelial cells are directly involved in many functions of the cardiovascular system by regulating blood flow and blood pressure through Ca2+ dependent exocitosis of vasoactive compounds. Using the Ca2+ indicator Fluo-3 and the patch-clamp technique, we show that bovine adrenal medulla capillary endothelial cells (B AMCECs) respond to acetylcholine (ACh) with a cytosolic Ca2+ increase and depolarization of the membrane potential (20.3±0.9 mV; n=23). The increase in cytosolic Ca2+ induced by 10µM ACh was mimicked by the same concentration of nicotine but not by muscarine and was blocked by 100 µM of hexamethonium. On the other hand, the increase in cytosolic Ca2+ could be depressed by nifedipine (0.01 -100 µM) or withdrawal of extracellular Ca2+. Taken together, these results give evidence for functional nicotinic receptors (nAChRs) in capillary endothelial cells of the adrenal medulla. It suggests that nAChRs in B AMCECs may be involved in the regulation of the adrenal gland's microcirculation by depolarizing the membrane potential, leading to the opening of voltage-activated Ca2+ channels, influx of external Ca2+ and liberation of vasoactive compounds. <![CDATA[<b>The possible role of Myosin light chain in myoblast proliferation</b>]]> Skeletal muscles have the potential to regenerate by activation of quiescent satellite cells, however, the molecular signature that governs satellite cells during muscle regeneration is not well defined. Myosin light chains (Myls) are sarcomere-related proteins as traditional regulator of muscle contraction. In this report, we studied the possible role of Myl in the proliferation of skeletal muscle-derived myoblasts. Compared to diaphragm-derived myoblasts, the extraocular muscle-derived myoblasts with lower levels of Myl proliferated faster, maintained a longer proliferation phase, and formed more final myotubes. It was found that blockading Myl with anti-Myl antibody or knockdown of Myll by siRNA targeted against Myll could enhance the myoblast proliferation and delay the differentiation of myoblasts. Our results suggested that Myl, likely Myll, can negatively affect myoblast proliferation by facilitating myoblast withdrawal from cell cycle and differentiation.