Genotype x environment interaction for age at first calving in Brazilian and Colombian Holsteins

The objective was to determine whether there is a genotype x environment interaction for age at first calving (AFC) in Holstein cattle in Brazil and Colombia. Data included 51,239 and 25,569 first-lactation records from Brazil and Colombia, respectively. Of 4230 sires in the data, 530 were North American sires used in both countries. Analyses were done using the REML bi-trait animal model, and AFC was considered as a distinct characteristic in each country. Fixed effects of contemporary group (herd-calving year), sire genetic group, and cow genetic group, and random effects of animal and residual variation were included in the model. Average AFC in Brazil and Colombia were 29.5 ± 4.0 and 32.1 ± 3.5 mo, respectively. Additive and residual genetic components and heritability coefficient for AFC in Brazil were 2.21 mo 2, 9.41 mo 2, and 0.19, respectively, whereas for Colombia, they were 1.02 mo 2, 6.84 mo 2, and 0.13, respectively. The genetic correlation of AFC between Brazil and Colombia was 0.78, indicating differences in ranking of sires consistent with a genotype x environment interaction. Therefore, in countries with differing environments, progeny of Holstein sires may calve at relatively younger or older ages compared with contemporary herdmates in one environment versus another.

Toxic and genotoxic effects of trivalent and hexavalent chromium - A review

During the last years, the emission of heavy metals to the environment has increased, causing a severe negative impact to the ecosystems and seriously compromising human health due to their mutagenic potential. Tri- (III) and hexavalent (VI) chromium (Cr) constitute the oxidative states of the metal chromium that are active in living organisms. These two oxidation states of the chromium differ with regards to their cellular effects, mainly due to the different abilities they possess in relation to easy of transport through biological membranes. Cr VI is transported into the cell through transference channels of endogenous anions that are isostructural and isoelectronical to Cr VI, such as SO 4 -2 and HPO 4 -2. On the other hand, Cr III is unable to diffuse through the cell membrane. Its existence inside the cells is generally due to the reduction of Cr VI, the endocytosis, or the absortion by the cells via phagocytosis. Cr III acts directly on the DNA molecule, while Cr VI reacts little with this molecule. In the ecosystem, however, Cr VI is more dangerous since this is the form that presents greater reactivity with biological membranes, crossing them and being easily incorporated into the cell. In the cell it is biotransformed to Cr III, a potentially mutagenic molecule. In vivo and in vitro studies have shown that organisms exposed to Cr VI present greater induction to a variety of damages to the DNA molecule. Among the damages induced by Cr, changes in the structure of the DNA molecule have been reported, with breaks of the major chain and base oxidation. In the organisms, these alterations generate chromosomal aberrations, micronucleus formation, sister chromatid exchanges, and errors in DNA synthesis.

Genetic effects on preweaning weight gain of Nelore-Hereford calves according to different models and estimation methods

Additive and nonadditive genetic effects on preweaning weight gain (PWG) of a commercial crossbred population were estimated using different genetic models and estimation methods. The data set consisted of 103,445 records on purebred and crossbred Nelore-Hereford calves raised under pasture conditions on farms located in south, southeast, and middle west Brazilian regions. In addition to breed additive and dominance effects, the models including different epistasis covariables were tested. Models considering joint additive and environment (latitude) by genetic effects interactions were also applied. In a first step, analyses were carried out under animal models. In a second step, preadjusted records were analyzed using ordinary least squares (OLS) and ridge regression (RR). The results reinforced evidence that breed additive and dominance effects are not sufficient to explain the observed variability in preweaning traits of Bos taurus x Bos indicus calves, and that genotype x environment interaction plays an important role in the evaluation of crossbred calves. Data were ill-conditioned to estimate the effects of genotype x environment interactions. Models including these effects presented multicolinearity problems. In this case, RR seemed to be a powerful tool for obtaining more plausible and stable estimates. Estimated prediction error variances and variance inflation factors were drastically reduced, and many effects that were not significant under ordinary least squares became significant under RR. Predictions of PWG based on RR estimates were more acceptable from a biological perspective. In temperate and subtropical regions, calves with intermediate genetic compositions (close to 1/2 Nelore) exhibited greater predicted PWG. In the tropics, predicted PWG increased linearly as genotype got closer to Nelore. ©2006 American Society of Animal Science. All rights reserved.

Thermoeconomic model considering the environment impacts on thermoelectric power plants: Natural gas versus diesel

In this paper a comparative analysis of the environmental impact caused by the use of natural gas and diesel in thermoelectric power plants utilizing combined cycle is performed. The objective is to apply a thermoeconomical analysis in order to compare the two proposed fuels. In this analysis, a new methodology that incorporates the economical engineering concept to the ecological efficiency once Cardu and Baica [1, 2], which evaluates, in general terms, the environmental impacts caused by CO2, SO2, NOx and Particulate Matter (PM), adopting as reference the air quality standards in vigour is employed. The thermoeconomic model herein proposed utilizes functional diagrams that allow the minimization the Exergetic Manufacturing Cost, which represents the cost of production of electricity incorporating the environmental impact effects to study the performance of the thermoelectric power plant [3,4], It follows that it is possible to determine the environmental impact caused by thermoelectric power plants and, under the ecological standpoint, the use of natural gas as a fuel is the best option compared to the use of the diesel, presenting ecological efficiency values of 0.944 and 0.914 respectively. From the Exergoeconomic point of view of, it was found out that the EMC (Exergetic Manufacturing Cost) is better when natural gas is used as fuel compared to the diesel fuel. Copyright © 2006 by ASME.

Effects of atrazine on female Wistar rats: Morphological alterations in ovarian follicles and immunocytochemical labeling of 90 kDa heat shock protein

Fertility in female mammals may be affected by a variety of endocrine disrupters present in the environment. Herbicide atrazine is an example of endocrine disrupter employed in agriculture, which disrupts estrous cyclicity in rats. Aiming to characterize morphologically the effect of low and sublethal doses of atrazine on the ovaries of Wistar rats, in an effort to determine the possible intrafollicular target site through which this herbicide acts adult females were submitted to both subacute and subchronic treatments. Additionally, immunocytochemical labeling of 90 kDa heat shock protein (HSP90) was performed in order to evaluate the role played by this protein in the ovary, under stressed conditions induced by herbicide exposure. The results indicated that atrazine induced impaired folliculogenesis, increased follicular atresia and HSP90 depletion in female rats submitted to subacute treatment, while the subchronic treatment with low dose of atrazine could compromise the reproductive capacity reflected by the presence of multioocytic follicle and stress-inducible HSP90. © 2007 Elsevier Ltd. All rights reserved.

Effects of the biodegradation on biodegradable polymer blends and polypropylene

The large use of plastics in the world generates a large amount of waste which persists around 200 years in the environment. To minimize this effect is important to search some new polymer materials: the blends of biodegradable polymers with synthetic polymers. It is a large area that needs an Intensive research to investigate the blends properties and its behavior face to the different treatments to aim at the blodegradation. The blends used In this work are: some blodegradable polymers such as: poly(hydroxybutyrate) (PHB) and poly(s-polycaprolactone) (PCL) with a synthetic polymer, polypropylene (PP), in lower concentration. These blends were prepared using an internal mixer (Torque Rheometer), and pressed. These films were submitted to fungus biotreatment. The films analyses will be carried out by Fourier Transform Infrared (FTIR), UV-Vis absorption (UV-Vis), Scanning Electronic Microscopy (SEM), DSC and TGA. © 2008 American Institute of Physics.

Effects of the density, aviary type, breed, and age on the behaviors of laying hens kept in cages

An experiment was carried out in order to investigate the behaviors of laying hens due to the environmental factors of: density inside of the cage, aviary type, breed, and age. The experiment was configured as a factorial 4x2x2x2 study, with treatments being four different ages, two different breeds, two different cage densities, and two different aviaries. The birds' behaviors were recorded using video cameras installed in the cages, using samples of 15 minutes recorded from 12 PM to 4 PM. The observed behaviors, frequency and duration of behaviors (measured in seconds) were identified and noted related to each bird. The study was initiated in March 2007, during four non-consecutive weeks. The observed behaviors were: opening wings, stretching, threatening, ruffling feathers, drinking water, aggressive pecking, eating, running, lying down, stretching head out of the cage, preening, mounting, prostrating, and doing nothing (inactivity). Due to the non-normality of the data recorded, the Kruskal-Wallis statistical test of the MINITAB Statistical Software® was used to compare the medians of the variables. For breed factor, only the durations of the eating presented significant differences (p-value< 0.05). For cage density, there was a significant median difference (p-value< 0.05) for almost all behaviors observed. The average length of time of behaviors was higher for the lowest cage density. However, the frequency of behaviors was lmerfor the lowest cage density. The frequency of the behaviors to preen feathers, to lie down, to drink water and to stretch the head were higher in the aviary, where the groups of birds were smaller. The observed behaviors were particularly affected by experimental factors cage density, and aviary type, which directly affects the available space for each bird.

The effects of stressful broodstock handling on hormonal profiles and reproductive performance of rhamdia quelen (Quoy & Gaimard) females

A stressful environment induces cortisol that might affect fish breeding and reproduction. In the present work, which aimed to mimic aquacultural conditions of the jundia (Rhamdia quelen) hatcheries in southern South America, females were submitted to normal or stressful handling and the effects of cortisol on serum levels of 17β-estradiol (E2) and testosterone (T) were determined. In addition, the effect of stress on reproductive parameters such as eggs and swim-up fry production was also measured. Eight females from a group submitted to stressful handling (SH) conditions and eight females from a group with normal handling (NH) conditions were captured for blood sampling at D 0 and at D 1, 10, 20, 30, and 40 of the experiment. A typical cortisol response was observed in the SH females group in that they presented higher cortisol level in contrast to the NH female group, in all days sampled, except at D 0. In the 10th and 20th d, the E2 levels were lower in SH females, but cortisol levels were higher, suggesting an effect of cortisol on E2 production and/or release. Stressful handling appeared to affect both the number and the quality of the gametes because a lower number of oocytes was stripped from SH females, and from SH fertilized eggs, a lower number of viable swim-up fry was obtained to be transferred to earthen larviculture ponds. Taken together, the results indicated that stressful handling of broodstock impairs R. quelen reproduction. © Copyright by the World Aquaculture Society 2008.

Multi-dimensional effects on Cladoceran (Crustacea, Anomopoda) assemblages in two cascade reservoirs in Southeast Brazil

The Cladocera assemblages in two cascade reservoirs located in the Paranapanema River in Brazil were studied during two consecutive years. Upstream Chavantes Reservoir is an accumulation system, with a long water retention time, high depth and oligo-mesotrophic status. The downstream Salto Grande Reservoir is a small, run-of-river reservoir, with a short water retention time, shallow depth and meso-eutrophic status. The goal of this study was to determine the inter- and intra-reservoir limnological differences with emphasis on the Cladocerans assemblages. The following questions were posed: (i) what are the seasonal dynamics of the reservoir spatial structures; (ii) how dynamics, seasonally, is the reservoirs spatial structure; and (iii) are the reservoir independent systems? A total of 43 Cladoceran species were identified in this study. Ceriodaphnia silvestrii was the most abundant and frequent species found in Chavantes Reservoir, while C. cornuta was most abundant and frequent in Salto Grande Reservoir. The Cladoceran species richness differed significantly among sampling sites for both reservoirs. In terms of abundance, there was a significant variation among sampling sites and periods for both reservoirs. A cluster analysis indicated a higher similarity among the deeper compartments, and the intermediate river-reservoir zones was grouped with the riverine sampling sites. For the smaller Salto Grande Reservoir, the entrance of a middle size tributary causes major changes in the system. A distinct environment was observed in the river mouth zone of another small tributary, representing a shallow environment with aquatic macrophyte stands. A canonical correlation analysis between environmental variables and Cladoceran abundance explained 75% of the data variability, and a complementary factorial analysis explained 65% of the variability. The spatial compartmentalization of the reservoirs, as well as the particular characteristics of the two study reservoirs, directly influenced the structure of the Cladoceran assemblages. The conditions of the lacustrine (dam) zone of the larger Chavantes Reservoir were reflected in the upstream zone of the smaller downstream Salto Grande Reservoir, highlighting the importance of plankton exportation in reservoir cascade systems. The comparative spatial-temporal analysis indicated conspicuous differences between the two reservoirs, reinforcing the necessity of considering tropical/subtropical reservoirs as complex, multi-compartmental water systems. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Asia Pty Ltd.

Small- and medium-sized enterprises' restructuring in a context of transition: a shared process: inter-player effects on efficient boundary choice in the Argentine manufacturing sector

Includes bibliography

The Mexican maquila industry and the environment: an overview of the issues

Includes bibliography

Threshold effects in the relationship between inward foreign direct investment and import productivity growth in Latin America and the Caribbean

Includes bibliography

The effects of soil pollution and its relation with morbidity in shoreline areas

Soil and subsoil pollution is not only significant in terms of environmental loss, but also a matter of environmental and public health. Solid, liquid and gaseous residues are the major soil contamination agents. They originate from urban conglomerates and industrial areas in which it is impossible to emphasize the chemical, petrochemical and textile industry; thermoelectric, mining, and ironmaster activities. The contamination process can thus be defined as a compound addition to soil, from what qualitative and or quantitative manners can modify soil's natural characteristics and use, producing baneful and deteriorative effects on human health. Studies have shown that human exposition to high concentration of some heavy metals found on soil can cause serious health problems, such as pulmonary or kidney complications, liver and nervous system harm, allergy, and the chronic exposition that leads to death. The present study searches for the correlation among soil contamination, done through a geochemical baseline survey of an industrial contamination area on the shoreline of Sao Paulo state. The study will be conducted by spatial analysis using Geographical Information Systems for mapping and regression analysis. The used data are 123 soil samples of percentage concentration of heavy metals. They were sampled and spatially distributed by geostatistics methods. To verify if there is a relation between heavy metals soil pollution and morbidity an executed correlation and regression analysis will be done using the pollution registers as the independent variables and morbidity as dependable variables. It is expected, by the end of the study, to identify the areas relation between heavy metals soil pollution and morbidity, moreover to be able to provide assistance in terms of new methodologies that could facilitate soil pollution control programs and public health planning. © 2010 WIT Press.

Buffalo milk production in brazil and colombia: Genotype by environment interaction

The objective of this study was to determine whether there is a genotype by environment interaction (GxE) for dairy buffaloes in Brazil and Colombia. The (co)variance components were estimated by using a bi-trait repeatability animal model with the REML method. Each trait consisted in the milk yield obtained in both countries. Contemporary group (herd, year and season of parity) and age at parity (linear and quadratic covariate) fixed effects, along with the additive genetic, permanent environment, and the residual random effects were included in the model. Genetic, permanent environmental and residual variance and heritabilities were different for both countries. The genetic correlations for milk yield between Brazil and Colombia were low (between 0.10 and 0.13), indicating a GxE interaction between both countries. Knowing that this interaction influences the genetic progress of buffalo populations in Brazil and Colombia, we recommend choosing sires tested in the country they will be used, along with conducting joint genetic evaluations that consider GxE interaction effects.

Genotype by environment interaction in different birth seasons for weight at 240, 365 and 450 days of age in Tabapuã cattle

The objective of this study was to evaluate the effect of genotype by environment interaction (GEI) on the weight of Tabapuã cattle at 240 (W240), 365 (W365) and 450 (W450) days of age. In total, 35,732 records of 8,458 Tabapuã animalswhich were born in the state of Bahia, Brazil, from 1975 to 2001, from 167 sires and 3,707 dams, were used. Two birth seasons were tested as for the environment effect: the dry (D) and rainy (R) ones. The covariance components were obtainedby a multiple-trait analysis using Bayesian inference, in which each trait was considered as being different in each season. Covariance components were estimated by software gibbs2f90. As for W240, the model was comprised of contemporary groups and cow age (in classes) as fixed effects; animal and maternal genetic additive, maternal permanent environmental and residual were considered as random effects. Concerning W365 and W450, the model included only the contemporary aged cow groups as fixed effects and the genetic additive and residual effects of the animal as the random ones. The GEI was assessed considering the genetic correlation, in which values below 0.80 indicated the presence of GEI. Regarding W365 and W450, the GEI was found in both seasons. As for post-weaning weight (W240), the effect of such interaction was not observed. ©2012 Sociedade Brasileira de Zootecnia.