Relatedness between numerically small Dutch Red dairy cattle populations and possibilities for multibreed genomic prediction.

Red dairy breeds are a valuable cultural and historical asset, and often a source of unique genetic diversity. However, they have difficulties competing with other, more productive, dairy breeds. Improving competitiveness of Red dairy breeds, by accelerating their genetic improvement using genomic selection, may be a promising strategy to secure their long-term future. For many Red dairy breeds, establishing a sufficiently large breed-specific reference population for genomic prediction is often not possible, but may be overcome by adding individuals from another breed. Relatedness between breeds strongly decides the benefit of adding another breed to the reference population. To prioritize among available breeds, the effective number of chromosome segments (Me) can be used as an indicator of relatedness between individuals from different breeds. The Me is also an important parameter in determining the accuracy of genomic prediction. The Me can be estimated both within a population and between 2 populations or breeds, as the reciprocal of the variance of genomic relationships. We investigated relatedness between 6 Dutch Red cattle breeds, Groningen White Headed (GWH), Dutch Friesian (DF), Meuse-Rhine-Yssel (MRY), Dutch Belted (DB), Deep Red (DR), and Improved Red (IR), focusing primarily on the Me, to predict which of those breeds may benefit from including reference animals of the other breeds. All of these breeds, except MRY, are under high risk of extinction. Our results indicated high variability of Me, especially between Me ranging from ∼3,500 to ∼17,400, indicating different levels of relatedness between the breeds. Two clusters are especially important, one formed by MRY, DR, and IR, and the other comprising DF and DB. Although relatedness between breeds within each of these 2 clusters is high, across-breed genomic prediction is still limited by the current number of genotyped individuals, which for many breeds is low. However, adding MRY individuals would increase the reference population of DR substantially. We estimated that between 11 and 133 individuals from other breeds are needed to achieve accuracy of genomic prediction equivalent to using one additional individual from the same breed. Given the variation in size of the breeds in this study, the benefit of a multibreed reference population is expected to be lower for larger breeds than for the smaller ones.

Constitutive interferon expression from retroviral vector.

A genomic fragment with the human beta-interferon gene was cloned into a pL3-4, a defective Moloney murine leukemia virus (M-MuLV) vector. Here we show that clones selected after viral infection of mouse NIH 3T3 cells constitutively produced 128 IU/ml of human beta-interferon. Constitutive synthesis of retroviral RNA was confirmed by dot blot hybridization of RNA isolated from two of the selected clones. Poly(I) x poly(C) and cycloheximide induction resulted in an increased RNA level, but this was not reflected in an increased production of biologically active interferon.

Molecular evidence for increased hematopoietic proliferation in the spleen of the b/b laboratory rat.

The splenomegaly and the appearance of a significant number of CFU-E (erythroid colony-forming units) and BFU-E1 (erythroid burst-forming units) in the Belgrade laboratory rat (b/b) spleen prompted us to analyse further the molecular evidence for increased hematopoietic proliferation in the b/b spleen. Messenger RNAs (mRNAs) specific for globins, proteins for iron transport and deposition and the band 3 protein were used in rat erythropoietic tissues as markers for proliferation and erythroid differentiation. In the b/b spleen, all mRNAs analysed display an erythroid-specific pattern of expression. This analysis also revealed an enhanced level of mRNA for ferritin in the +/b spleen, whereas erythrocyte-specific mRNA production was normal.

The disbalance of alpha- and beta-globins in anemic Belgrade rat red blood cells.

The Belgrade Laboratory (b/b) rat has an autosomal mutation which in homozygous state induces severe anemia. This study was based on solubilization of total rat globin chains and their separation into alpha- and beta-globins using a 20% SDS polyacrylamide gel. These analyses demonstrated that the disbalance of alpha/beta globins in b/b red blood cells (RBC) is due to decreased level of alpha-globins. Iron-dextran administration corrected the level and globin ratio in b/b RBC thus confirming that the iron deficiency is the primary defect in b/b rats.