Full pedigree quantitative trait locus analysis in commercial pigs using variance components

In commercial livestock populations, QTL detection methods often use existing half-sib family structures and ignore additional relationships within and between families. We reanalyzed the data from a large QTL confirmation experiment with 10 pig lines and 10 chromosome regions using identity-by-descent (IBD) scores and variance component analyses. The IBD scores were obtained using a Monte Carlo Markov Chain method, as implemented in the LOKI software, and were used to model a putative QTL in a mixed animal model. The analyses revealed 61 QTL at a nominal 5% level (out of 650 tests). Twenty-seven QTL mapped to areas where QTL have been reported, and eight of these exceeded the threshold to claim confirmed linkage (P < 0.01). Forty-two of the putative QTL were detected previously using half-sib analyses, whereas 46 QTL previously identified by half-sib analyses could not be confirmed using the variance component approach. Some of the differences could be traced back to the underlying assumptions between the two methods. Using a deterministic approach to estimate IBD scores on a subset of the data gave very similar results to LOKI. We have demonstrated the feasibility of applying variance component QTL analysis to a large amount of data, equivalent to a genome scan. In many situations, the deterministic IBD approach offers a fast alternative to LOKI.     

The implications of various silvicultural funding arrangements for privately managed public forest land in Canada

When devising policies for financing private silvicultural operations on public forest land, government agencies should consider carefully the benefits and costs of alternative arrangements and how they arc likely to affect tenure holders' behavior. Three general methods of achieving silvicultural objectives arc discussed — the creation of incentives for private voluntary expenditures, reimbursement by governments of expenditures on approved or required silvicultural operations, and required silvicultural operations at the tenure holder's expense.Private firms will only invest voluntarily in silviculture on public lands if they have adequate security of tenure and hold sufficient equity in the timber values resulting from their activities. If firms' silvicultural costs arc reimbursed, their behavior will depend on the extent of reimbursement and whether they have a financial interest in the outcomes of their reimbursed activities. Generally, reimbursement of expenditures must be supported by minimum performance standards and costly monitoring and enforcement procedures. If silvicultural operations are required at the tenure holder's expense, firms will only undertake silviculture to avoid penalties and have a strong incentive to achieve required standards at minimum cost. More stringent monitoring and enforcement procedures may be necessary than if costs arc reimbursed.The impact of policy alternatives is illustrated by means of a survey of silvicultural expenditures on two forest tenure types in British Columbia.     

Pyramiding genes for resistance to bean common mosaic virus

Summary Gene pyramiding in Phaseolus vulgaris is being utilized to develop more effective resistance to the temperature-insensitive-necrosis-inducing (TINI) strains of Bean Common Mosaic Virus (BCMV) present in the USA. Our data indicate that contrary to previous work, the bc-3 gene is effective against these strains in the absence of the strain unspecific bc-u gene in genotypes possessing the I gene. The epistatic bc-3 gene interferes with traditional efforts to pyramid the other recessive resistance genes by masking their activity. Indirect selection based on markers linked to the other recessive resistance genes would likewise be ineffective without the ability to also select for the bc-u gene which is required for expression of the bc-2 ² gene in germplasm carrying the I gene. Because the most resistant genotype (I, bc-u, bc-I ², bc-2², bc-3) can only be introduced into a wide range of germplasm through the use of molecular markers linked to the different resistance genes, the search for a marker linked to the strain unspecific bc-u gene should also be given priority.     

Antioxidant properties of bran extracts from "Akron" wheat grown at different locations

Bran extracts of Akron wheat grown at four nonirrigated and one irrigated testing locations were examined and compared for their free radical scavenging properties against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(*)) and the radical cation ABTS(*)(+), chelating capacities, and total phenolic content (TPC) to determine the potential effects of environmental factors on the antioxidant properties of hard winter wheat. The environmental factors included total solar radiation, average daily solar radiation, and number of hours exceeding 32 degrees C. The results showed that bran samples from different growing locations may significantly differ in their radical scavenging activities against both DPPH(*) and ABTS(*)(+), chelating capacities, and TPC. A significant negative correlation was detected between the chelating activities of the bran samples from the four nonirrigated locations and total solar or daily average solar radiation (r = -0.999 and P = 0.001). These data suggest potential influences of growing conditions on the antioxidant properties of hard winter wheat and the possibility of producing wheat that is strong in a selected antioxidant property by optimizing the growing conditions of a selected wheat variety. More research is required to further investigate the relationship among antioxidant properties and environmental factors using different wheat varieties and larger sample sizes.     

Human-mouse cell hybrids: a suggestion of structural mutation for dipeptidase-2 deficiency in mouse cells

The dipeptidase-2 enzyme is inactive in certain cultured cell lines from the mouse. In somatic cell hybrids between such deficient cells and diploid human fibroblasts, the mouse deficiency was complemented when the homologous human peptidase-A was retained. The results suggested that the murine peptidase deficiency was the result of a structural mutation, rather than a regulatory one.     

A protein sensor for siRNA asymmetry

To act as guides in the RNA interference (RNAi) pathway, small interfering RNAs (siRNAs) must be unwound into their component strands, then assembled with proteins to form the RNA-induced silencing complex (RISC), which catalyzes target messenger RNA cleavage. Thermodynamic differences in the base-pairing stabilities of the 5' ends of the two approximately 21-nucleotide siRNA strands determine which siRNA strand is assembled into the RISC. We show that in Drosophila, the orientation of the Dicer-2/R2D2 protein heterodimer on the siRNA duplex determines which siRNA strand associates with the core RISC protein Argonaute 2. R2D2 binds the siRNA end with the greatest double-stranded character, thereby orienting the heterodimer on the siRNA duplex. Strong R2D2 binding requires a 5'-phosphate on the siRNA strand that is excluded from the RISC. Thus, R2D2 is both a protein sensor for siRNA thermodynamic asymmetry and a licensing factor for entry of authentic siRNAs into the RNAi pathway.     

Thyroid neoplasms in a colony of beagle dogs

The histologic, clinicopathologic, and epidemiologic features of spontaneous thyroid neoplasms were evaluated in a control population of Beagle dogs. The mean age of thyroid tumor-bearing dogs (16.2 years) as significantly higher than non-tumor-bearing dogs (13.6 years). Thirteen benign and 18 malignant tumors were identified, with the incidence of both tumors increasing rapidly near the mean age of 16.2 years for tumor-bearing dogs. The age-specific incidence of tumors was 1.1% per year at 8 to 12 years, increasing to 4.0% per year by 12 to 15 years and 67% over 17 years of age. Numbers of malignant tumors were greater than benign tumors at an earlier age. Approximately 44% of the malignant tumors metastasized but only 22% resulted in death of the dog. There was no difference in tumor incidence when compared according to sex, if total tumor numbers were considered or if tumors were separated into benign and malignant categories. The age at death of tumor-bearing dogs was not increased significantly by the surgical resection of the thyroid tumors. Of dogs with thyroid tumors, 15% had clinical diagnoses of hypothyroidism, and no dogs with thyroid tumors had diagnoses of hyperthyroidism.     

The effects of weaning beef calves in two stages on their behavior and growth rate

Four trials were conducted to explore possible advantages of weaning beef calves in two stages compared with the traditional method of weaning by abrupt separation. In the two-stage treatment, calves were prevented from nursing their dam for a period (Stage 1) before their separation (Stage 2). Control calves nursed from their dams until they were separated. Calf weights and behavior were recorded before and after the separation of cows and calves. Following separation, calves weaned in two stages vocalized 96.6% less (P = 0.001) and spent 78.9% less time walking (P = 0.001), 23.0% more time eating (P = 0.001), and 24.1% more time resting (P = 0.001) than control calves. Compared with controls, two-stage calves had lower (P < 0.001) ADG when nursing was deprived (Stage 1), but greater (P < 0.001) ADG during the 7 d following separation. In Trial 3, calves weaned by the two-stage method had greater (P = 0.05) growth rates than control calves for 7 wk after separation, but no treatment effects on ADG were detected (P > 0.38) in Trials 1 and 2. Over the entire study period (before and after separation), ADG did not differ (P > 0.10) for both treatments. In Trial 4, calves weaned in two stages walked 1.3 km/d more (P < 0.05) during the 4-d period when nursing was prevented (Stage 1) and 5.8 km/d less (P < 0.05) during the 4-d period after separation than controls. Differences between treatments were the greatest in the 2 d after separation. On the first day after separation, two-stage calves walked 5.2 +/- 0.5 km/ d, whereas control calves walked 16.7 +/- 3.1 km/d. Calves weaned in two stages were less distressed than calves weaned by the traditional method of abrupt separation based on behavioral data, but overall calf ADG did not differ for either method in this study. Nutritional management of two-stage weaned calves during the nursing-deprived period should be evaluated in future research because poor pasture conditions may have decreased gains by calves weaned by the two-stage method in this study.