The inheritance of response phenotype to Heligmosomoides polygyrus was investigated in F1 hybrid progeny of fast and slow responder mouse strains. The fast responses of SJL(H-2s) and SWR(H-2q) mice were mediated by dominant genes complementing each other in F1 hybrids which lost worms earlier and produced faster parasite-specific IgG1 antibody responses than either parent. However, the response...

The expression of mammary tumor virus (MTV) antigen in the milk and various organs of three non-inbred dd mouse stocks (ddO, ddN and ddY) was examined by the immunodiffusion (ID) and micro-immunodiffusion (micro-ID) tests. The rate of MTV antigen expression in the milk was 100% at the first lactation in ddO (6/6) and ddN mice (10/10), and 23% in ddY mice (3/13). Mammary tumor incidence was 13% ...

Hybrids between Rhipicephalus appendiculatus and R. zambeziensis were reared and glucose-phosphate-isomerase isoenzymes were resolved by agarose electrophoresis. By phenotyping hybrids in F1 and F2 generations autosomal transmission of 2 GPI genes was demonstrated. Identification of a hybrid phenotype provides a method for identifying hybrids in field collections.

aegilops triuncialis l. (2n=4x=28; ctctutut) is one of the tetraploid aegilops species harboring valuable genes for resistance to many biotic and abiotic stresses. in the present study the bread wheat cultivars mv17, navid, omid, pishgam, zarin were crossed with an accession of ae. triuncialis and the resulted f1 and f2 (obtained by the selfing of f1 plants) hybrids studied using the convention...

Background: The consequences of hybridization vary depending on the fitness of hybrids and pure species plants. Herbivory and fungal infection may affect fitness and often differ in their effect on hybrid versus pure-species genotypes. Questions: Do herbivory and fungal infection rates differ between pure species and hybrids? What is the underlying genetic basis of resistance to herbivory and f...

Chromosomal rearrangements can contribute to the evolution of postzygotic reproductive isolation directly, by disrupting meiosis in F1 hybrids, or indirectly, by suppressing recombination among genic incompatibilities. Because direct effects of rearrangements on fertility imply fitness costs during their spread, understanding the mechanism of F1 hybrid sterility is integral to reconstructing th...

We investigated patterns of cytonuclear disequilibrium between nuclear allozyme loci and partial mitochondrial COI and COII restriction fragment length polymorphism patterns within a population of hybridizing chrysomelid beetles and assessed to what degree the genotype frequencies of F1 hybrids were consistent with patterns of mate choice or endosymbiont infection. We document that in this popu...

F1 hybrids in Arabidopsis and crop species are uniform and high yielding. The F2 generation loses much of the yield advantage and the plants have heterogeneous phenotypes. We generated pure breeding hybrid mimic lines by recurrent selection and also selected a pure breeding small phenotype line. The hybrid mimics are almost completely homozygous with chromosome segments from each parent. Four p...

Tomato (Solanum lycopersicum) production in tropical and subtropical regions of the world is limited by the endemic presence of Tomato yellow leaf curl virus (TYLCV). Breeding programmes aimed at producing TYLCV-resistant tomato cultivars have utilized resistance sources derived from wild tomato species. So far, all reported breeding programmes have introgressed TYLCV resistance from a single w...

A pivotal-differential evolution pattern is when two allopolyploids share a common genome, which is called pivotal, and differ with respect to the other genome or genomes, called differential. This feature induces the intergenomic recombination between chromosomes of differential genomes, which can lead to speciation. Our study is a cytomolecular insight into this mechanism which was adapted fo...