Esterase polymorphism in remanant populations of Aspidosperma polyneuron Müll.Arg. (Apocynaceae)

The population genetic structure of the endangered tree species Aspidosperma polyneuron Mull.Arg. (Apocynaceae) was reported based on analysis of esterase polymorphism in two remanant populations. Allelic variation was detected at three isoesterase loci (Est-3, Est-9, and Est-10). The proportion of polymorphic loci for both populations was 30% and deviation from Hardy-Weinberg equilibrium was observed for the Est-3 locus observed in the northern population. Segregation distortion and the lower level of observed and expected heterozygosity in this population were attributed to founder genotype. The high genetic identity values for northern and northwestern populations are in accordance with the low levels of interpopulation genetic divergence demonstrated by the F(ST) (0.03) value. The F(IS) value (0.23) indicated moderate levels of inbreeding. A. polyneuron can be indicated as an example of endangered species suggesting high genetic variation in contrast to the low genetic variation reported for endangered species. The esterase isozymes may be a good genetic marker for studies of natural A. polyneuron populations.

Genetic structure and diversity of Copaifera langsdorffii Desf. in Cerrado fragments of the São Paulo State, Brazil

The loss of large areas of Cerrado (Brazilian savanna) in Brazil can lead to reduced biodiversity and to the extinction of species. Therefore, the present study aimed to investigate the genetic fragility of populations of Copaifera langsdorffii Desf exposed to different anthropic conditions in fragments of Cerrado in the state of São Paulo. The study was carried out in two Experimental Stations operated by the Forest Institute (Assis and Itirapina), in one fully protected conservation unit (Pedregulho) and in one private property (Brotas). Analyses were conducted using leaf samples from 353 adult specimens and eight pairs of microsatellite loci. The number of alleles per locus ranged from 13 to 15 in all populations, but the mean number of effective alleles was approximately half this value (7.2 to 9-1). Observed heterozygosity was significant and lower than the expected in all populations. Consequently, all populations deviated from Hardy-Weinberg expected frequencies. Fixation indexes were significant for all populations, with the Pedregulho population having the lowest value (0.189) and Itirapina having the highest (0.283). The analysis of spatial genetic structure detected family structures at distance classes of 20 to 65 m in the populations studied. No clones were detected in the populations. Estimates of effective population size were low, but the area occupied by each population studied was large enough for conservation, medium and long term. Recent reductions or bottlenecks were detected in all four populations. Mean Gst’ (genetic divergence) indicated that most of the variation was within populations. Cluster structure analysis based on the genotypes detected K= 4 clusters with distinct allele frequencies patterns. The genetic differentiation observed among populations is consistent with the hypothesis of genetic and geographic isolation. Therefore, it is essential to adopt conservation strategies that raise the gene flow between fragments.

k-Casein gene frequencies support subdivision and historical origin of Argentine Creole cattle

Gene frequencies at the k-casein locus were estimated in six different herds (N = 180) of Argentinean Creole cattle. The results showed a strong influence of subdivision and independent evolution on the divergence of the observed gene frequencies. These results suggest that the population structure of these herds favor the maintenance of polymorphism, which is of crucial importance for the long-time survival of populations.

Conflicting genomes, the demic theory & biodiversity

Organismic-centered Darwinism, in order to use direct phenotypes to measure natural selection's effect, necessitates genome's harmony and uniform coherence plus large population sizes. However, modern gene-centered Darwinism has found new interpretations to data that speak of genomic incoherence and disharmony. As a result of these two conflicting positions a conceptual crisis in Biology has arisen. My position is that the presence of small, even pocket-size, demes is instrumental in generating divergence and phenotypic crisis. Moreover, the presence of parasitic genomes as in acanthocephalan worms, which even manipulate suicidal behavior in their hosts; segregation distorters that change meiosis and Mendelian ratios; selfish genes and selfish whole chromosomes, such as the case of B-chromosomes in grasshoppers; P-elements in Drosophila; driving Y-chromosomes that manipulate sex ratios making males more frequent, as in Hamilton's X-linked drive; male strategists and outlaw genes, are eloquent examples of the presence of real conflicting genomes and of a non-uniform phenotypic coherence and genome harmony. Thus, we are proposing that overall incoherence and disharmony generate disorder but also more biodiversity and creativeness. Finally, if genes can manipulate natural selection, they can multiply mutations or undesirable characteristics and even lethal or detrimental ones, hence the accumulation of genetic loads. Outlaw genes can change what is adaptively convenient even in the direction of the trait that is away from the optimum. The optimum can be "negotiated" among the variants, not only because pleiotropic effects demand it, but also, in some cases, because selfish, outlaw, P-elements or extended phenotypic manipulation require it. With organismic Darwinism the genome in the population and in the individual was thought to act harmoniously without conflicts, and genotypes were thought to march towards greater adaptability. Modern Darwinism has a gene-centered vision in which genes, as natural selection's objects can move in dissonance in the direction which benefits their multiplication. Thus, we have greater opportunities for genomes in permanent conflict.

Characterization of six rat strains (Rattus norvegicus) by mitochondrial DNA restriction fragment length polymorphism

Restriction fragment length polymorphism (RFLP) was used to examine the extent of mtDNA polymorphism among six strains of rats (Rattus norvegicus) - Wistar, Wistar Munich, Brown Norway, Wistar Kyoto, SHR and SHR-SP. A survey of 26 restriction enzymes has revealed a low level of genetic divergence among strains. The sites of cleavage by EcoRI, NcoI and XmnI were shown to be polymorphic. The use of these three enzymes allows the 6 strains to be classified into 4 haplotypes and identifies specific markers for each one. The percentage of sequence divergence among all pairs of haplotypes ranged from 0.035 to 0.33%, which is the result of a severe population constriction undergone by the strains. These haplotypes are easily demonstrable and therefore RFLP analysis can be employed for genetic monitoring of rats within animal facilities or among different laboratories.

Comparative sequence analysis of the P-, M- and L-coding region of the measles virus CAM-70 live attenuated vaccine strain

Measles virus is a highly contagious agent which causes a major health problem in developing countries. The viral genomic RNA is single-stranded, nonsegmented and of negative polarity. Many live attenuated vaccines for measles virus have been developed using either the prototype Edmonston strain or other locally isolated measles strains. Despite the diverse geographic origins of the vaccine viruses and the different attenuation methods used, there was remarkable sequence similarity of H, F and N genes among all vaccine strains. CAM-70 is a Japanese measles attenuated vaccine strain widely used in Brazilian children and produced by Bio-Manguinhos since 1982. Previous studies have characterized this vaccine biologically and genomically. Nevertheless, only the F, H and N genes have been sequenced. In the present study we have sequenced the remaining P, M and L genes (approximately 1.6, 1.4 and 6.5 kb, respectively) to complete the genomic characterization of CAM-70 and to assess the extent of genetic relationship between CAM-70 and other current vaccines. These genes were amplified using long-range or standard RT-PCR techniques, and the cDNA was cloned and automatically sequenced using the dideoxy chain-termination method. The sequence analysis comparing previously sequenced genotype A strains with the CAM-70 Bio-Manguinhos strain showed a low divergence among them. However, the CAM-70 strains (CAM-70 Bio-Manguinhos and a recently sequenced CAM-70 submaster seed strain) were assigned to a specific group by phylogenetic analysis using the neighbor-joining method. Information about our product at the genomic level is important for monitoring vaccination campaigns and for future studies of measles virus attenuation.

An analysis of the electrocardiogram QT interval

No reports testing the efficacy of the use of the QT/RR ratio <1/2 for detecting a normal QTc interval were found in the literature. The objective of the present study was to determine if a QT/RR ratio <=1/2 can be considered to be equal to the normal QTc and to compare the QT and QTc measured and calculated clinically and by a computerized electrocardiograph. Ratios (140 QT/RR) of 28 successive electrocardiograms obtained from 28 consecutive patients in a tertiary level teaching hospital were analyzed clinically by 5 independent observers and by a computerized electrocardiograph. The QT/RR ratio provided 56% sensitivity and 78% specificity, with an area under the receiver operator characteristic curve of 75.8% (95%CI: 0.68 to 0.84). The divergence in QT and QTc interval measurements between clinical and computerized evaluation were 0.01 ± 0.03 s (95%CI: 0.04-0.02) and 0.01 ± 0.04 s (95%CI: -0.05-0.03), respectively. The QT and QTc values measured clinically and by a computerized electrocardiograph were similar. The QT/RR ratio <=1/2 was not a satisfactory index for QTc evaluation because it could not predict a normal QTc value.

The use of light-emitting diodes to stimulate mitochondrial function and liver regeneration of partially hepatectomized rats

The biostimulating effect of laser radiation has been observed in many areas of Medicine. However, there are still several questions to be answered, among them the importance of light coherence in the stimulatory process. In the present study, we used light-emitting diodes (LED) to promote the stimulation of liver regeneration after partial hepatectomy in rats. Fourteen male Wistar rats weighing 200-250 g were submitted to partial hepatectomy (70%) followed by LED light irradiation (630 nm) of the remaining part of the liver at two doses, i.e., 10 (N = 7) and 140 (N = 7) J/cm². A group irradiated with laser, 590 nm (N = 7, 15 J/cm²) was performed for the study of proliferating cell nuclear antigen-labeling index. Data are reported as mean ± SEM. Statistical comparisons of the groups were performed by analysis of variance for parametric measurements followed by the Bonferroni post-test, with the level of significance set at P < 0.05. Respiratory mitochondrial activity was increased in the irradiated groups (states 3 and 4; P < 0.05), with better results for the group exposed to the lower LED dose (10 J/cm²). The proliferating cell nuclear antigen-labeling index, by immunohistochemical staining, was similar for both LED-exposed groups (P > 0.05) and higher than for the control group (P < 0.05). The cell proliferation index obtained with LED and laser were similar (P > 0.05). In conclusion, the present results suggest that LED irradiation promotes biological stimulatory effects during the early stage of liver regeneration and that LED is as effective as laser light, independent of the coherence, divergence and cromaticity.

Investigation of glutathione peroxidase activity in chicken meat under different experimental conditions

Due to the fact that previous studies on the enzymatic activity of Glutathione peroxidase (GSH-Px) diverge widely in their methodology and results, this study aimed to investigate the influence of different analytical conditions on GSH-Px activity in chicken thighs from broilers that were fed different diets with different sources and concentrations of selenium. GSH-Px activity was evaluated six hours after slaughter and 120 days after frozen storage at -18 ºC. The different analytical conditions included time of pre-incubation (0, 10 and 30 minutes), reaction medium, types of substrate (H2O2 (0.72 mM, 7.2 mM, and 72 mM) and Terc-butil hydroperoxide 15 mM), and different buffer concentrations (buffer 1, potassium phosphate 50 mM pH 7.0 + EDTA 1 mM + mercaptoethanol 1 mM, and buffer 2, tris-HCl 50 mM pH 7.6 + EDTA 1 mM + mercapthanol 5 mM). The results show that the highest GSH-Px activity was observed when enzyme and substrate were in contact at 22 ºC without any pre-incubation, and that, when used at concentrations above 0.72 mM, hydrogen peroxide saturated the GSH-Px enzyme and inhibited its activity. The enzyme presented higher affinity to hydrogen peroxide when compared to terc-butil peroxide, and the addition of a buffer containing mercaptoethanol did not increase GSH-Px enzymatic activity. The activity of GSH-Px was not influenced by the source and concentration of selenium in the diet either. The obtained results allowed the determination of the best temperature of contact between the enzyme and substrate (22 ºC), the optimum concentration, and the type of substrate and buffer to be used. This information is extremely useful for future studies on GSH-Px activity in meat due to the divergence and little information found in the literature.

Um modelo evolucionário Norte-Sul

This work expands the classical Nelson and Winter model of Schumpeterian competition by including two sectors and a North-South dynamics, with a view to analyzing how different institutions and technological regimes affect the processes of convergence and divergence in the international economy. The results suggest that convergence may emerge out of the efforts for imitation in the South when the technological regime is cumulative. But when the regime is science-based, imitation is not enough for a successful catching-up. In this case convergence requires the South to invest in innovation as well. The work also analyses the robustness of the model results using Montecarlo techniques.

Emerging markets and the international financial architecture: a blueprint for reform

If emerging markets are to achieve their objective of joining the ranks of industrialized, developed countries, they must use their economic and political influence to support radical change in the international financial system. This working paper recommends John Maynard Keynes's "clearing union" as a blueprint for reform of the international financial architecture that could address emerging market grievances more effectively than current approaches. Keynes's proposal for the postwar international system sought to remedy some of the same problems currently facing emerging market economies. It was based on the idea that financial stability was predicated on a balance between imports and exports over time, with any divergence from balance providing automatic financing of the debit countries by the creditor countries via a global clearinghouse or settlement system for trade and payments on current account. This eliminated national currency payments for imports and exports; countries received credits or debits in a notional unit of account fixed to national currency. Since the unit of account could not be traded, bought, or sold, it would not be an international reserve currency. The credits with the clearinghouse could only be used to offset debits by buying imports, and if not used for this purpose they would eventually be extinguished; hence the burden of adjustment would be shared equally - credit generated by surpluses would have to be used to buy imports from the countries with debit balances. Emerging market economies could improve upon current schemes for regionally governed financial institutions by using this proposal as a template for the creation of regional clearing unions using a notional unit of account.