Scielo RSS <![CDATA[Biological Research]]> https://scielo.conicyt.cl/rss.php?pid=0716-976020070002&lang=en vol. 40 num. 2 lang. en <![CDATA[SciELO Logo]]> https://scielo.conicyt.cl/img/en/fbpelogp.gif https://scielo.conicyt.cl <![CDATA[<b>Toll-like Receptors are Key Participants in Innate Immune Responses</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200001&lng=en&nrm=iso&tlng=en During an infection, one of the principal challenges for the host is to detect the pathogen and activate a rapid defensive response. The Toll-like family of receptors (TLRs), among other pattern recognition receptors (PRR), performs this detection process in vertebrate and invertebrate organisms. These type I transmembrane receptors identify microbial conserved structures or pathogen-associated molecular patterns (PAMPs). Recognition of microbial components by TLRs initiates signaling transduction pathways that induce gene expression. These gene products regulate innate immune responses and further develop an antigen-specific acquired immunity. TLR signaling pathways are regulated by intracellular adaptor molecules, such as MyD88, TIRAP/Mal, between others that provide specificity of individual TLR- mediated signaling pathways. TLR-mediated activation of innate immunity is involved not only in host defense against pathogens but also in immune disorders. The involvement of TLR-mediated pathways in auto-immune and inflammatory diseases is described in this review article <![CDATA[<b>The threat from creationism to the rational teaching of biology</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200002&lng=en&nrm=iso&tlng=en Most biologists outside the USA and a few other countries, like Australia and Canada, are under the impression that the threat to the teaching of biology represented by creationism does not concern them directly. This is unfortunately no longer true: the recent growth of creationism, especially in its pseudo-scientific manifestation known as "intelligent design", has been obvious in several countries of Western Europe, especially the UK, Germany and Poland, and it is beginning to be noticeable in Brazil, and maybe elsewhere in Latin America. The problem is complicated by the fact that there are not just two possibilities, evolution and creationism, because creationism comes in various incompatible varieties. Turkey is now a major source of creationist propaganda outside the USA, and is especially significant in relation to its influence on Muslim populations in Europe. The time for biologists to address the creationist threat is now <![CDATA[<b>Stimulus specificity in the acquisition and extinction of conditioned taste aversion</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200003&lng=en&nrm=iso&tlng=en An experiment evaluated whether the acquisition and extinction of conditioned taste aversion in the rat is stimulus-specific by testing the degree of response transfer between sweet and salty tastes. Animals in the paired-same and paired-different groups received a presentation of a gustatory CS and a cyclophosphamide injection US. Nonconditioned control groups received unpaired CS /US presentations or the CS followed by a vehicle injection. Taste avoidance was evaluated in three nonreinforced test sessions. In the paired-same, unpaired and vehicle groups, all test sessions were conducted with the same flavor as originally used in training, whereas the paired-different group was tested with a novel flavor on the first and second sessions and with the originally trained flavor in last session. Stimulus specific acquisition was apparent in the first test session, when the animals in the group paired-same exhibited lower fluid intake than the other three groups. Evidence of specificity of extinction was apparent in the last test session, when animals in the group paired-different exhibited lower fluid intake than the other three groups. These results provide further evidence of stimulus specificity in acquisition and extinction of conditioned taste aversion, supporting the associative interpretation of these phenomena <![CDATA[<b>The ingestión of a <i>Nectandra membranácea </i>extract changes the bioavailability of technetium-99m radiobiocomplex in rat organs</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200004&lng=en&nrm=iso&tlng=en The radiobiocomplexes labeled with technetium-99m (Tc-99m) have been widely used in nuclear medicine in single photon emission computed tomography and in basic research. The aim of this study was to assess the influence of a Nectandra membranácea extract on the bioavailability of the sodium pertechnetate (Na99mTc0(4)) radiobiocomplex in rat organs. The animals were treated with a N. membranácea extract (30 mg/ ml), for 6 days. Na99mTc0(4) was injected, the organs were isolated and weighed, and the radioactivity was determined in each organ (%ATI/organ). The %ATI/organ was divided by the mass of each organ to calculate the %ATI/g. A significant increase of the %ATI/organ of Na99mTc0(4) was observed in muscle and thyroid as well as in the %ATI/g in the heart, kidney and thyroid. These findings could result from the interaction between components of the plant extract and the radiobiocomplex which may influence the uptake Na99mTc0(4) in rat organs. Therefore, precaution is suggested in the interpretation of nuclear medicine results in patients using this herb <![CDATA[<b>Changes in PEP Carboxylase, Rubisco and Rubisco activase mRNA levels from maize <i>(Zea mays) </i>exposed to a chronic ozone stress</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200005&lng=en&nrm=iso&tlng=en We quantified the ozone impact on levels of Zea mays L. cv. Chambord mRNAs encoding C4-phosphoenolpyruvate carboxylase (C4-PEPc), ribulose-l,5-bisphosphate carboxylase/oxygenase small and large subunits (Rubisco-SSU and Rubisco-LSU, respectively) and Rubisco activase (RCA) using real-time RT-PCR. Foliar pigment content, PEPc and Rubisco protein amounts were simultaneously determined. Two experiments were performed to study the ozone response of the 5th and the 10th leaf. For each experiment, three ozone concentrations were tested in open-top chambers: non-filtered air (NF, control) and non-filtered air containing 40 (+40) and 80 nL L-1 (+80) ozone. Regarding the 5th leaf, +40 atmosphere induced a loss in pigmentation, PEPc and Rubisco activase mRNAs. However, it was unable to notably depress carboxylase protein amounts and mRNAs encoding Rubisco. Except for Rubisco mRNAs, all other measured parameters from 5th leaf were depressed by +80 atmosphere. Regarding the 10th leaf, +40 atmosphere increased photosynthetic pigments and transcripts encoding Rubisco and Rubisco activase. Rubisco and PEPc protein amounts were not drastically changed, even if they tended to be increased. Level of C4-PEPc mRNA remained almost stable. In response to +80 atmosphere, pigments and transcripts encoding PEPc were notably decreased. Rubisco and PEPc protein amounts also declined to a lesser extent. Conversely, the level of transcripts encoding both Rubisco subunits and Rubisco activase that were not consistently disturbed tended to be slightly augmented. So, the present study suggests that maize leaves can respond differentially to a similar ozone stress <![CDATA[<b>Antioxidant effect of 5-amino salicylic acid on copper-mediated LDL oxidation</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200006&lng=en&nrm=iso&tlng=en The antioxidant effect of 5-Aminosalicylic acid (5-ASA) on copper-mediated LDL oxidation was followed either by the emitted chemiluminiscence (CL) or by UV-vis spectroscopy. 5-ASA addition extends the lag phase in a concentration-dependent manner without changes in the rate of the process in the autoaccelerated phase. The antioxidant behavior of 5-ASA was very similar to that of Trolox, a very efficient water soluble antioxidant. The copper-binding capacity of 5-ASA was evaluated by UV-visible spectroscopy. The addition of copper to a 5-ASA solution increases the absorbance at 332 nm and generates a new band at 298 nm. These changes in the UV-vis spectra indicate formation of a complex between 5-ASA and copper. However, LDL protection by 5-ASA is unrelated to its copper chelating capacity <![CDATA[<b>Species composition and seasonal succession of saprophagous calliphorids in a rural area of Córdoba</b>: <b>Argentina</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200007&lng=en&nrm=iso&tlng=en During 2004, four experiments were carried out, one each season, in order to determine the species composition and seasonal dynamics of Calliphoridae in a rural area of Córdoba (Argentina). Two pigs (Sus seroja L.), weighing approximately 8 Kg each, were used in each experiment. They were killed with a blow to the head and immediately placed in a variant of the Schoenly et al. (1991) trap. One pig was exposed in the shade and the other one under direct sunlight. The insect fauna was collected daily during the four first weeks and every two or three days thereafter. A total of 16.609 adults of Calliphoridae were collected, and later on identified as one of the following seven species: Chrysomya albiceps (Wiedemann), Chrysomya megacephala (Fabricius), Phaenicia sericata (Meigen), Phaenicia eximia (Wiedemann), Cochliomyia macellaria (Fabricius), Sarconesia chlorogaster (Wiedemann) and Calliphora vicina Robineau-Desvoidy. C. albiceps was the dominant species in summer, autumn and spring, being replaced in winter by C. vicina, S. chlorogaster and P. sericata. The analysis of the seasonal distribution of the species revealed that the greater incidences are in the months of summer, autumn and spring <![CDATA[<b>Construction of an immunotoxin by linking a monoclonal antibody against the human epidermal growth factor receptor and a hemolytic toxin</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200008&lng=en&nrm=iso&tlng=en Hybrid molecules obtained through conjugation of monoclonal antibodies and toxins constitute an approach under exploration to generate potential agents for the treatment of cancer and other diseases. A frequently employed toxic component in the construction of such immunotoxins is ricin, a plant toxin which inhibits protein synthesis at ribosomal level and so requires to be internalized by the cell. A hemolytic toxin isolated from the sea anemone Stichodactyla helianthus, which is active at the cell membrane level, was linked through a disulfide bond to the anti-epidermal growth factor receptor monoclonal antibody ior egf/r3. The resulting immunotoxin did not exhibit hemolytic activity except under reducing conditions. It was toxic for H125 cells that express the human epidermal growth factor receptor, but non-toxic for U1906 cells that do not express this receptor <![CDATA[<b>The chromatin structure of the lysozyme GAS41 origin of DNA replication changes during the cell cycle</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200009&lng=en&nrm=iso&tlng=en We used a rapid and simple protocol using lysolecithin for mapping HS sites in vivo. The protocol is based on partial digestion with DNase I of exponentially growing cells following permeabilization by short treatment with lysolecithin. Using this protocol, we analyzed the chromatin structure of the region surrounding two overlapping elements, an origin of bidirectional DNA replication and the GAS41 promoter, in chicken myelomonocytic HD11 cells arrested in G0, G0 and S phases as well as at the G0/S border. The results show that the chromatin of this region became more nuclease sensitive when cells were arrested in G0 phase and that this change in chromatin structure was reversible after the cells began to enter S phase <![CDATA[<b>Interplay between the morphometry of the lungs and the mode of locomotion in birds and mammals</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200010&lng=en&nrm=iso&tlng=en We studied the lung diffusion parameters of two species of birds and two species of mammals to explore how structural and functional features may be paralleled by differences in life style or phylogenetic origin. We used two fast-flying species (one mammal and one bird), one running mammal and one bird species that flies only occasionally as models. The harmonic mean thickness of the air-blood barrier was very thin in the species we studied. An exception was the Chilean tinamou Notoprocta perdicaria, which only flies occasionally. It showed an air-blood barrier as thick as that of flightless Galliformes. We found that the respiratory surface density was significantly greater in flying species compared to running species. The estimated values for the oxygen diffusion capacity, DtO2 follow the same pattern: the highest values were obtained in the flying species, the bat and the eared dove. The lowest value was in N. perdicaria. Our findings suggest that the studied species show refinements in their morphometric lung parameters commensurate to their energetic requirements as dictated by their mode of locomotion, rather than their phylogenetic origin. The air-blood barrier appears to be thin in most birds and small mammals, except those with low energetic requirements such as the Chilean tinamou. In the species we studied, the respiratory surface density appears to be the factor most responsive to the energetic requirements of flight <![CDATA[<b>Fluorescent serum and urinary advanced glycoxidation end-products in non- diabetic subjects</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200011&lng=en&nrm=iso&tlng=en Introduction: Advanced glycoxidation end-products (AGEs) are involved in age-related conditions and diabetic complications. Diet intake contributes to their circulating concentrations. Aim: To measure serum and urinary AGEs in non-diabetic volunteers and relate their concentration to body composition, blood chemistry and dietary ingestión. Methods: We studied 41 adult men (31 middle-aged adults and 10 elderly). A nutritional assessment including a dietary recall designed for detection of AGE ingestión (specifically carboxymethyl-lysine(CML)), and anthropometric measurements were performed. Also serum lipoproteins, insulin, glucose, leptin and C reactive protein (CRP). AGEs were measured in serum and urine samples using size exclusion chromatography and flow injection assay (FIA); the technical procedures were first employed in 11 heterogeneous diabetics, as positive controls for this methodology. Results: Serum and urinary chromatograms indicated that areas under the curve were not different in younger compared with elderly adults. AGEs did not correlate with dietary intake, body composition, nor metabolic parameters, however they correlated significantly with renal function and CRP concentration. Discussion: In these non-diabetic volunteers, with low CML intake, serum and urinary concentration of AGEs were not related to dietary intake. AGEs were related to renal function and CRP, but not to body composition, lipoproteins, insulin and glucose <![CDATA[<b>Genital Sensory Stimulation Shifts Estradiol Intraoviductal Signaling from Nongenomic to Genomic Pathways, Independently from Prolactin Surges</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200012&lng=en&nrm=iso&tlng=en Estradiol (E2) accelerates oviductal egg transport through nongenomic pathways involving oviductal protein phosphorylation in non-mated rats, and through genomic pathways in mated rats. Here we investigated the ability of cervico-vaginal stimulation (CVS) to switch the mode of action of E2 in the absence of other male-associated components. Pro-estrous rats were subjected to CVS with a glass rod and 12 hours later were injected subcutaneously with E2 and intrabursally with the RNA synthesis inhibitor Actinomycin D or the protein phosphorylation inhibitor H-89. The number of eggs in the oviduct, assessed 24 h later, showed that Actinomycin D, but not H-89 blocked the E2-induced egg transport acceleration. This clearly indicates that CVS alone, without other mating-associated signals, is able to shift E2 signaling from nongenomic to genomic pathways. Since mating and CVS activate a neuroendocrine reflex that causes iterative prolactin (PRL) surges, the involvement of PRL pathway in this phenomenon was evaluated. Prolactin receptor mRNA and protein expression in the rat oviduct was demonstrated by RT-PCR and Western blot, but their levels were not different on day 2 of the cycle (C2) or pregnancy (P2). Activated ST AT 5a/b (phosphorylated) was detected by Western blot on P2 in the ovary, but not in the oviduct, showing that mating does not stimulate this PRL signalling pathway in the oviduct. Other rats subjected to CVS in the evening of pro-estrus were treated with bromoergocriptine to suppress PRL surges. In these rats, H-89 did not block the E2-induced acceleration of egg transport suggesting that PRL surges are not essential to shift E2 signaling pathways in the oviduct. We conclude that CVS is one of the components of mating that shifts E2 signaling in the oviduct from nongenomic to genomic pathways, and this effect is independent of PRL surges elicited by mating <![CDATA[<b>XV-2c and KM</b>: <b>19 haplotype analysis in Chilean patients with cystic fibrosis and unknown CFTR gene mutations</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200013&lng=en&nrm=iso&tlng=en Cystic fibrosis (CF) is caused by mutations in the CFTR gene. More than 1600 mutations have been described, with frequencies that differ worldwide according to the ethnic origin of patients. A small group of mutations are recurrent on several populations. It has been shown that they each tend occur on specific chromosome 7 haplotypes, supporting the notion of a single origin for them. Less than 50% of mutations in Chilean patients have been identified to date. To indirectly assess the possible presence of a predominant founder mutation in the remaining unknown alíeles, we evaluated 2 polymorphic markers, XV-2c and KM.19, tightly linked to the CFTR locus. The study was done in Chilean CF patients with unknown or delt F508 ( F508) CFTR mutations and their haplotypes were compared to affected family-based controls. F508 showed marked linkage disequilibrium with XV-2c/KM.19 haplotype B, with 90% of alíeles on that haplotype. There was no difference in haplotype distribution between unknown mutations and normal controls. These results support a European origin for F508 alíeles in Chilean patients, and make unlikely the presence of a predominant founder mutation in the so-far unknown alíeles <![CDATA[<b>Evaluation of the role of the Endoplasmic Reticulum-Golgi transit in the biogenesis of peroxisomal membrane proteins in wild type and peroxisome biogenesis mutant CHO cells</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200014&lng=en&nrm=iso&tlng=en Peroxisomes are thought to be formed by division of pre-existing peroxisomes after the import of newly synthesized proteins. However, it has been recently suggested that the endoplasmic reticulum (ER) provides an alternative de novo mechanism for peroxisome biogenesis in some cells. To test a possible role of the ER-Golgi transit in peroxisome biogenesis in mammalian cells, we evaluated the biogenesis of three peroxisomal membrane proteins (PMPs): ALDRP (adrenoleukodystrophy related protein), PMP70 and Pex3p in CHO cells. We constructed chimeric genes encoding these PMPs and green fluorescent protein (GFP), and transiently transfected them to wild type and mutant CHO cells, in which normal peroxisomes were replaced by peroxisomal membrane ghosts. The expressed proteins were targeted to peroxisomes and peroxisomal ghosts correctly in the presence or absence of Brefeldin A (BFA), a drug known to block the ER-Golgi transit. Furthermore, low temperature did not disturb the targeting of Pex3p-GFP to peroxisomes. We also constructed two chimeric proteins of PMPs containing an ER retention signal "DEKKMP": GFP-ALDRP-DEKKMP and myc- Pex3p-DEKKMP. These proteins were mostly targeted to peroxisomes. No colocalization with an ER maker was found. These results suggest that the classical ER-Golgi pathway does not play a major role in the biogenesis of mammalian PMPs <![CDATA[<b>The CK1 gene family</b>: <b>expression patterning in zebrafish development</b>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000200015&lng=en&nrm=iso&tlng=en Protein kinase CK1 is a ser/thr protein kinase family which has been identified in the cytosol cell fraction, associated with membranes as well as in the nucleus. Several isoforms of this gene family have been described in various organisms: CK1á, CK1ß, CK1δ, CK1å and CK1γ. Over the last decade, several members of this family have been involved in development processes related to wnt and sonic hedgehog signalling pathways. However, there is no detailed temporal information on the CK1 family in embryonic stages, even though orthologous genes have been described in several different vertebrate species. In this study, we describe for the first time the cloning and detailed expression pattern of five CK1 zebrafish genes. Sequence analysis revealed that zebrafish CK1 proteins are highly homologous to other vertebrate orthologues. Zebrafish CK1 genes are expressed throughout development in common and different territories. All the genes studied in development show maternal and zygotic expression with the exception of CK1å. This last gene presents only a zygotic component of expression. In early stages of development CK1 genes are ubiquitously expressed with the exception of CK1å. In later stages the five CK1 genes are expressed in the brain but not in the same way. This observation probably implicates the CK1 family genes in different and also in redundant functions. This is the first time that a detailed comparison of the expression of CK1 family genes is directly assessed in a vertebrate system throughout development