Optimizing purebred selection for crossbred performance using QTL with different degrees of dominance

A method was developed to optimize simultaneous selection for a quantitative trait with a known QTL within a male and a female line to maximize crossbred performance from a two-way cross. Strategies to maximize cumulative discounted response in crossbred performance over ten generations were derived by optimizing weights in an index of a QTL and phenotype. Strategies were compared to selection on purebred phenotype. Extra responses were limited for QTL with additive and partial dominance effects, but substantial for QTL with over-dominance, for which optimal QTL selection resulted in differential selection in male and female lines to increase the frequency of heterozygotes and polygenic responses. For over-dominant QTL, maximization of crossbred performance one generation at a time resulted in similar responses as optimization across all generations and simultaneous optimal selection in a male and female line resulted in greater response than optimal selection within a single line without crossbreeding. Results show that strategic use of information on over-dominant QTL can enhance crossbred performance without crossbred testing.     

Effect of postnatal development on calcium currents and slow charge movement in mammalian skeletal muscle

Single- (whole-cell patch) and two-electrode voltage-clamp techniques were used to measure transient (Ifast) and sustained (Islow) calcium currents, linear capacitance, and slow, voltage-dependent charge movements in freshly dissociated fibers of the flexor digitorum brevis (FDB) muscle of rats of various postnatal ages. Peak Ifast was largest in FDB fibers of neonatal (1-5 d) rats, having a magnitude in 10 mM external Ca of 1.4 +/- 0.9 pA/pF (mean +/- SD; current normalized by linear fiber capacitance). Peak Ifast was smaller in FDB fibers of older animals, and by approximately 3 wk postnatal, it was so small as to be unmeasurable. By contrast, the magnitudes of Islow and charge movement increased substantially during postnatal development. Peak Islow was 3.6 +/- 2.5 pA/pF in FDB fibers of 1-5-d rats and increased to 16.4 +/- 6.5 pA/pF in 45-50-d-old rats; for these same two age groups, Qmax, the total mobile charge measurable as charge movement, was 6.0 +/- 1.7 and 23.8 +/- 4.0 nC/microF, respectively. As both Islow and charge movement are thought to arise in the transverse-tubular system, linear capacitance normalized by the area of fiber surface was determined as an indirect measure of the membrane area of the t-system relative to that of the fiber surface. This parameter increased from 1.5 +/- 0.2 microF/cm2 in 2-d fibers to 2.9 +/- 0.4 microF/cm2 in 44-d fibers. The increases in peak Islow, Qmax, and normalized linear capacitance all had similar time courses. Although the function of Islow is unknown, the substantial postnatal increase in its magnitude suggests that it plays an important role in the physiology of skeletal muscle.     

A study on the minimum number of loci required for genetic evaluation using a finite locus model

For a finite locus model, Markov chain Monte Carlo (MCMC) methods can be used to estimate the conditional mean of genotypic values given phenotypes, which is also known as the best predictor (BP). When computationally feasible, this type of genetic prediction provides an elegant solution to the problem of genetic evaluation under non-additive inheritance, especially for crossbred data. Successful application of MCMC methods for genetic evaluation using finite locus models depends, among other factors, on the number of loci assumed in the model. The effect of the assumed number of loci on evaluations obtained by BP was investigated using data simulated with about 100 loci. For several small pedigrees, genetic evaluations obtained by best linear prediction (BLP) were compared to genetic evaluations obtained by BP. For BLP evaluation, used here as the standard of comparison, only the first and second moments of the joint distribution of the genotypic and phenotypic values must be known. These moments were calculated from the gene frequencies and genotypic effects used in the simulation model. BP evaluation requires the complete distribution to be known. For each model used for BP evaluation, the gene frequencies and genotypic effects, which completely specify the required distribution, were derived such that the genotypic mean, the additive variance, and the dominance variance were the same as in the simulation model. For lowly heritable traits, evaluations obtained by BP under models with up to three loci closely matched the evaluations obtained by BLP for both purebred and crossbred data. For highly heritable traits, models with up to six loci were needed to match the evaluations obtained by BLP.     

Maximized sampling of butterflies to detect temporal changes in tropical communities

There are few papers describing long-term fluctuations and general patterns of temporal diversity in butterfly assemblages in the Neotropical region. The present paper presents a long-term study on the variation in richness and composition of butterflies in a fragment of semi-deciduous forest in Southeastern Brazil, and examines the viability of using maximized butterfly transect counts as a methodology to rapidly and adequately access the local characteristics of butterfly communities. Based on the eight annual standard lists, 518 species in six butterfly families were recorded, representing 74 % of the total butterfly fauna known from the study site. Hesperiidae was the richest family (248 species), followed by Nymphalidae (154), Lycaenidae (49), Riodinidae (29), Pieridae (26), and Papilionidae (12). The accumulation curves show that 8 years of sampling were not enough to result in stable species totals for all butterfly families, especially Hesperiidae and Lycaenidae, which are still increasing in number of species. A great similarity in species composition was observed among all the years (54 %). Comparing the similarity between two standard lists at different time intervals (from 1 to 8 years), a clear pattern of increasing dissimilarity was observed in most families. Our results show that the maximized sampling method is effective in revealing temporal patterns of diversity across several years and could be valuable in monitoring temporal variation in butterfly assemblages for conservation purposes, since the obtained standard lists can be successfully compared to temporal patterns over large periods of time.     

Apoptosis,cytokine and chemokine induction by non-structural 1 (NS1) proteins encoded by different influenza subtypes

Background

Influenza pandemic remains a serious threat to human health. Viruses of avian origin, H5N1, H7N7 and H9N2, have repeatedly crossed the species barrier to infect humans. Recently, a novel strain originated from swine has evolved to a pandemic. This study aims at improving our understanding on the pathogenic mechanism of influenza viruses, in particular the role of non-structural (NS1) protein in inducing pro-inflammatory and apoptotic responses.

Methods

Human lung epithelial cells (NCI-H292) was used as an in-vitro model to study cytokine/chemokine production and apoptosis induced by transfection of NS1 mRNA encoded by seven infleunza subtypes (seasonal and pandemic H1, H2, H3, H5, H7, and H9), respectively.

Results

The results showed that CXCL-10/IP10 was most prominently induced (> 1000 folds) and IL-6 was slightly induced (< 10 folds) by all subtypes. A subtype-dependent pattern was observed for CCL-2/MCP-1, CCL3/MIP-1α, CCL-5/RANTES and CXCL-9/MIG; where induction by H5N1 was much higher than all other subtypes examined. All subtypes induced a similar temporal profile of apoptosis following transfection. The level of apoptosis induced by H5N1 was remarkably higher than all others. The cytokine/chemokine and apoptosis inducing ability of the 2009 pandemic H1N1 was similar to previous seasonal strains.

Conclusions

In conclusion, the NS1 protein encoded by H5N1 carries a remarkably different property as compared to other avian and human subtypes, and is one of the keys to its high pathogenicity. NCI-H292 cells system proves to be a good in-vitro model to delineate the property of NS1 proteins.

     

Cryopreservation of caprine ovarian tissue using dimethylsulphoxide and propanediol

The caprine ovary is a rich source of potentially viable immature oocytes enclosed in preantral follicles (PF). Previous experiments showed that these oocytes can be successfully cryopreserved in ovarian tissue of several species. However, until now, no information about the caprine PF cryopreservation is available in the literature. The aim of the present research was to evaluate the structural and ultrastructural characteristics of caprine PF after treatment and cryopreservation of ovarian tissue with 1.5 and 3 M dimethylsulphoxide (DMSO) and propanediol (PROH). One fragment of ovarian tissue was immediately fixed for histological examination and ultrastructural analysis, after slaughter (control). Four fragments were equilibrated at 20 degrees C/20 min in 1.8 ml of minimum essential medium (MEM) containing 1.5 or 3 M DMSO or PROH for the toxicity test, and the other four fragments were slowly frozen in each cryoprotectant at the concentrations previously described. After toxicity test and freezing/thawing procedures, the ovarian fragments were fixed for histological examination. The results showed that after toxicity test and cryopreservation of ovarian tissue using both cryoprotectants, the percentage of normal PF was less (P < 0.05) as compared with the control group. The present study revealed that the percentage of normal PF after toxicity test and cryopreservation in 1.5 M DSMO was significantly greater (P < 0.05) as compared with results obtained with 3 M DMSO or 1.5 and 3 M PROH. This result was confirmed by transmission electron microscopy, which showed that the PF were preserved in a higher quality state with 1.5 M DMSO. In conclusion, the present study demonstrated that caprine PF can be cryopreserved in ovarian tissue using 1.5 M DMSO.