Scielo RSS <![CDATA[Biological Research]]> vol. 36 num. 2 lang. en <![CDATA[SciELO Logo]]> <![CDATA[LA FALTA DE UN ADECUADO RECONOCIMIENTO DE LAS CAPACIDADES EXISTENTES AFECTA EL DESARROLLO CIENTÍFICO EN CHILE]]> <![CDATA[On the Biol Res issue dedicated to F. Varela]]> <![CDATA[CONTRIBUCIÓN DE LAS NORMAS CIOMS 2002 AL DESARROLLO BIOTECNOLÓGICO: LA CORRESPONSABILIZACIÓN DEL CIENTÍFICO]]> La revolución biotecnológica afronta grandes retos, entre ellos la participación social, la bioseguridad y la protección tanto del germoplasma como del conocimiento ancestral que de él se derivan. Para afrontar estos dilemas se plantea la necesidad de buscar una corresponsabilización de todos los actores del desarrollo biotecnológico. En este artículo se realiza un correlato partiendo de la reflexión ya iniciada por la comunidad médica con sus pautas éticas internacionales para la investigación biomédica en seres humanos, CIOMS, versus la biotecnología para buscar una corresponsabilización de los tecnocientíficos, biotecnólogos en sus investigaciones con la pretensión utópica de buscar un desarrollo biotecnológico mas respetuoso con el hombre y con su entorno y que dé respuesta a los problemas que la biotecnología está generando. <![CDATA[Comparative study of inter-and intrahemispheric cortico-cortical connections in gerbil auditory cortex]]> Topographic distributions and laminar pattern of cortico-cortical projections from the primary auditory field (AI), anterior auditory field (AAF), dorsoposterior field (DP), ventroposterior field (VP), dorsal field (D) and ventral field (V) were studied in relation to tonotopic maps in combined anatomical, electrophysiological and 2-deoxyfluoro-D-glucose (2DG) experiments. Distributions of axons were examined by means of retrogradely-transported fluorescent tracer Fast Blue (FB) injected in the primary (AI) and anterior (AAF) auditory field. Injections of fluorescent tracer were placed in electrophysiologically-identified locations of AI and AAF. Neurons in AAF, DP, VP and V project to AI in the ipsilateral hemisphere. This area also receives projections from AI, AAF and D from the contralateral hemisphere. In AI, DP and VP, neurons are connected with AAF in the ipsilateral hemisphere and AI and AAF in the opposite hemisphere. In all cases, patches of labeling are distributed along 2DG bands oriented parallel to the isofrequency line. Substantial numbers of retrogradedly labeled neurons with similar best frequencies (BFs) were observed in the ipsilateral and moderate to scant numbers in the contralateral hemisphere. In general, regions near the injection sites receive more densely-labeled projections than do more distant targets. In both hemispheres, the supragranular layer III contains the greatest concentration of cortico-cortical cells bodies; the granular and infragranular layer V contains a somewhat lower concentration. <![CDATA[Quantitation of diarrhetic shellfish poisoning toxins in Chilean Mussel using pyrenyldiazomethane as fluorescent labeling reagent]]> Diarrhetic shellfish poisoning (DSP) is a gastrointestinal disease caused by lipid soluble polyether toxins produced by dinoflagellates and accumulated in shellfish. Diarrhetic shellfish poisoning is a worldwide threat to public health and the shellfish industry. To date, only four lipid soluble polyethers have been known as diarrhetic shellfish toxins. Among them, Okadaic acid (OA), Dinophysistoxin 1 (DTX-1, 35-methyl OA), Dinophysistoxin 2 (DTX-2, OA isomers) and Dinophysistoxin 3 (DTX-3, 7-O-acyl-35-methyl OA), all of which have free carboxilic groups. To perform quantitative analysis of DSP toxins in shellfish samples is a requirement, because DSP toxins are endemic in the Chilean mollusks of the southern regions, and although human symptoms of DSP appear relatively mild in comparison with the Paralytic Shellfish Poisoning (PSP), the necessity of monitoring the chronic effects of continued uptake of low doses of DSP toxins more closely is imperative, since DSP toxins have been described as potent tumor promoters. This paper shows the synthesis pathway of a chromophore, 1-pyrenyldiazomethane (PDAM), a fluorescent labeling reagent for determination of carboxilic acids, using High Performance Liquid Chromatography with fluorescence on-line detection . This procedure was developed in order to have a quantitative method for DSP toxins analysis that would be useful for health public services and private shellfish industries. The features of this labeling reagent are compared against ADAM and used for quantitative analysis of DSP toxins in Chilean mussels and cultured dinoflagellates samples. <![CDATA[Effect of salinity on the quantity and quality of carotenoids accumulated by <i>Dunaliella salina</i> (strain CONC-007) and <i>Dunaliella bardawil</i> (strain ATCC 30861) Chlorophyta]]> Dunaliella salina and D. bardawil are well-known microalgae accumulating high levels of b-carotene under growth-limiting conditions. In both taxa, this pigment is primarily composed of the isomers 9-cis and all-trans. The 9-cis b-carotene occurs only in natural sources and is the most attractive from a commercial point of view. The conditions that enhance the preferred accumulation of 9-cis b-carotene in D. salina are controversial and they have not been well established yet. This study examined the effect of salinity on the quantity and quality of total carotenoids and b-carotene isomers accumulated by D. salina (strain CONC-007) and D. bardawil (strain ATCC 30861) grown in two media with different nutritional compositions (PES and ART) and at salt concentrations of 1M, 2M and 3M NaCl. Total carotenoids were determined by spectrophotometry and b-carotene isomers, by HPLC. The highest carotenoid contents per cell were obtained at 2M NaCl in both taxa. In both media, an increase of the 9-cis/all-trans b-carotene ratio was observed in D. bardawil when the salt concentration increased, with a maximum value of 2.6 (in ART medium at 3M NaCl). In D. salina this ratio did not exhibit the same pattern, and the salt concentrations for maximal ratios were different in both media. The highest ratio obtained for this strain was 4.3 (in ART medium at 2M NaCl). <![CDATA[Spatial Memory in Long Evans and <i>Rattus Norvegicus</i> rats]]> Rodents in search of food use visual environmental signals and complex spatial strategies and do not return to previously-visited locations, known as the win-shift strategy. The solution to the Olton Octagonal Maze (OOM) involves Working Memory (WM). A modified OOM was used that allows for measuring WM and Long Term Memory (LTM). The delayed spatial win-shift task consisted of a Training and Test phase separated by a delay. Prior to the Training phase, four arms were chosen at random and blocked, and food pellets were placed in the food cups of the four remaining open arms. Each rat was allowed to retrieve the pellets from the four open arms and then return to its home cage for the delay period (either 5 or 20 min). In the Test phase all 8 lanes were open, and the bait was placed in those blocked in the previous phase. Two experimental groups of rats, Long Evans and Norvegicus, and their corresponding control groups were trained. The experimental subjects performed Training-Delay-Test. The controls were only trained in the Test phase. Revisiting an arm previously explored in the 1st Phase was considered a LTM error. Revisiting an arm in the same trial constituted a WM error. It was concluded that the experimental groups do in fact possess LTM, with differences in favor of Norvegicus. There was no difference with respect to WM errors. The Norvegicus control group changes its strategy from allocentric to egocentric, which did not occur in the Long Evans control group. <![CDATA[Complete sequence of the genome of the human isolate of Andes virus CHI-7913: comparative sequence and protein structure analysis]]> We report here the complete genomic sequence of the Chilean human isolate of Andes virus CHI-7913. The S, M, and L genome segment sequences of this isolate are 1,802, 3,641 and 6,466 bases in length, with an overall GC content of 38.7%. These genome segments code for a nucleocapsid protein of 428 amino acids, a glycoprotein precursor protein of 1,138 amino acids and a RNA-dependent RNA polymerase of 2,152 amino acids. In addition, the genome also has other ORFs coding for putative proteins of 34 to 103 amino acids. The encoded proteins have greater than 98% overall similarity with the proteins of Andes virus isolates AH-1 and Chile R123. Among other sequenced Hantavirus, CHI-7913 is more closely related to Sin Nombre virus, with an overall protein similarity of 92%. The characteristics of the encoded proteins of this isolate, such as hydrophobic domains, glycosylation sites, and conserved amino acid motifs shared with other Hantavirus and other members of the Bunyaviridae family, are identified and discussed. <![CDATA[Homeostasis and Heterostasis: from Invariant to Dimensionless Numbers]]> In the present paper we have examined the applicability of dimensionless and invariant numbers (DN & IN) to the analysis of the cardiovascular system of mammals, whose functions were measured at standard metabolic conditions. The calculated IN did not change when we compared these figures with those obtained in dogs while they were submitted to graded exercise on a treadmill. In both instances, rest and exercise, the constancy of the IN prevailed, in accordance with Cannon's principle of "homeostasis" (1929). On the contrary, when dogs were examined during a standardized hypovolemic shock, we observed a breakdown of the IN, and the resulting DN evolved as a reliable index of the condition of "heterostasis" as defined by H. Selye. The robustness of the homeostatic regulations is based on high-gain integral feedback mechanisms, while "heterostasis" could be associated with low-gain integral feedback processes, when organisms are submitted to unitary step disturbances or to changes of the set-point at the entrance of the feedback loop. <![CDATA[The complete sequence of the mitochondrial genome of the Chinook salmon, <i>Oncorhynchus tshawytscha</i>]]> The complete sequence of the mitochondrial genome of Chinook salmon, Oncorhynchus tshawytscha, has been determined. The circular genome consisting of 16,644 base pairs encodes thirteen proteins, the 12S and 16S ribosomal RNAs, and 22 transfer RNAs. These genes are ordered in the same way as most other vertebrates. The nucleotide and amino acid sequences of the ribosomal RNAs and the thirteen protein-coding genes were compared with those of other salmonids such as Oncorhynchus mykiss, Salmo salar, Salvelinus fontinalis, Salvelinus alpinus and Coregonus lavaretus. The sequence features of the control region (D-loop), the origin of L-strand replication and a putative peptide codified by the 16S mitochondrial RNA are described and discussed. <![CDATA[Effects of Steroidal and Non Steroidal Drugs on the Neovascularization Response Induced by Tumoral TA3 Supernatant on CAM from Chick Embryo]]> Angiogenesis, the development of new blood vessels from the existing vascular network, may result as a consequence of the increase or decrease of proangiogenic or antiangiogenic factors, respectively. The tumor itself could up-regulate the production of angiogenic factors. Recently, we established that the steroidal drug betamethasone in low concentration inhibit the neovascularization promoted by TA3 Ts on CAM of chick embryos. We describe here the effects of the non-steroidal drug ketoprofen, alone or in association with betamethasone, on the angiogenesis promoted by TA3 Ts on CAM. The main finding reported here is that the formation of new blood vessels is strongly inhibited by low concentrations of ketoprofen. The association of both drugs produced a synergistic effect, significantly decreasing tumoral supernatant angiogenesis. It is known that steroidal anti-inflammatory drugs inhibit the enzymes required for the production of prostaglandins through a nuclear GR mediated mechanism. This may operate as a general mechanism in endothelial cells as well. Considering that the induction of COX 1 and COX2 are inhibited by ketoprofen, and that these enzymes are located in the stromal compartment of the CAM, we propose that its antiangiogenic effect may occur via inhibition of the two COX isoforms. In fact, we found that ketoprofen induced apoptosis in both the stromal fibroblast and endotelial cells. The potentiated effect of the combination of betamethasone and ketoprofen may have some therapeutic projections in the control of pathological angiogenesis <![CDATA[Genomic organization of the rDNA cistron of the teleost fish <i>Cyprinus carpio</i>]]> 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. <![CDATA[Antitumor Activities of Iodoacetate and Dimethylsulphoxide Against Solid Ehrlich Carcinoma Growth in Mice]]> Treatment of tumor-bearing mice with LD12.5 values of iodoacetate; IAA (1.84 mg/100g b.w.) and/or dimethylsulphoxide; DMSO (350 mg/ 100g b.w.) significantly increased the cumulative mean survival time and percentage of survivors and reduced the mean tumor weight, compared to tumor-bearing controls, however, a more pronounced effect is recorded in the combined treatment. Also, an increase in the life span (ILS%) and tumor growth inhibition ratio (T/C%) are reported and amounted to 145.78 and 43.80%, 195.54 and 61.30% and 220.77 and 78.40% in IAA, DMSO and combined-treated groups, respectively. Results obtained from biochemical studies reveal that a single IAA treatment of tumor-bearing mice significantly increased the levels of plasma lactate dehydrogenase (LDH) activity, while it also significantly decreased the levels of plasma glucose and liver total protein, RNA and DNA, compared to normal controls. On the other hand, a single DMSO treatment significantly elevated the activities of blood antioxidant enzymes, i.e. glutathione peroxidase (GPx) and glucose-6-phosphate dehydrogenase (G6PDH) and decreased the liver RNA and DNA levels. Combined treatment increased significantly the levels of plasma LDH and erythrocytes G6PDH activities, as well as liver glycogen, and in contrast it decreased the levels of liver total protein, RNA and DNA, compared to normal controls. <![CDATA[The MAP Kinases are Differently Utilized by CD28 and CD2 Adhesion Pathways in Superantigen-Activated Jurkat T cells]]> To mimic the two-signal requirements for T cell activation mediated by ligands, we exposed the superantigens SEA or SEE (signal 1) to T cells incubated with HLA-DR/LFA-3 or HLA-DR/B7-1-CHO transfected cells (signal 2). LFA-3 costimulation was able to induce T cell proliferation as well as IFN-g and IL-4 production at similar levels as in cells induced by B7-1. Analysis of the CD28RE of the IL-2 promoter showed specific transcription factor recruitment at the CD28RE element upon induction by B7-1/SEE. Further functional studies with an IL-2 enhancer-promoter carrying either wild type or mutated versions of the CD28RE site revealed that this element is necessary for full activation upon B7-1 costimulation. While both CD28/B7-1 and CD2/LFA-3 costimulation resulted in the up-regulation of IL-4 and IFN-g promoters, IL-2 promoter activity and production of IL-2 were only seen after B7-1 costimulation. However, contrary to what has been previously proposed, we show that costimulation with either B7-1 or LFA-3 further enhanced the ERK-2 activity and strongly activated the p38 MAPK pathway, but only B7-1 costimulation induced high levels of JNK-1 activity. These data suggest that the differential effect of CD28 vs. CD2 can be related to the difference in the ability of the two pathways to induce JNK-1 activity. <![CDATA[p53 Codon 72 Polymorphism and Risk of Cervical Cancer]]> Storey et al. (1998) implicated the proline/argine polymorphism of the codon 72 of the tumor-suppressor gene p53 in the development of cervical cancer (CC) with the observation that the p53 protein is more efficiently inactivated by the E6 oncoprotein of human papillomavirus in p53 arginine as compared with its proline isoform. These authors further noted that in the United Kingdom, individuals homozygous for the arginine allele were several times more susceptible to HPV-associated tumorigenesis that proline/arginine heterozygotes. Subsequent studies in different countries failed to unanimously confirm this association. Motivated by the high incidence of CC in Chile, we undertook a case control study obtaining the following frequencies for genotypes PP, AP and AA in 60 ICC cases and 53 carefully selected controls: 0.067, 0.250, 0.683 and 0.075, 0.453, 0.472 respectively. A significant difference (X² = 3.19 p < 0.02) and an odds ratio of 2.62 supported Storey et al (1998)'s results. In addition, rejecting previous hypotheses about the world distribution of the p53 codon 72 polymorphism, we conclude that this distribution most likely represents ancient human dispersal routes. Several methodological and biological explanations for the results obtained in previous negative association studies are briefly discussed.