Gene flow between populations that are adapting to distinct environments may be restricted if hybrids inherit maladaptive, intermediate phenotypes. This phenomenon, called extrinsic postzygotic isolation (EPI), is thought to play a critical role in the early stages of speciation. However, despite its intuitive appeal, we know surprisingly little about the strength and prevalence of EPI in natur...

We crossed the C3 species Atriplex prostrata with the C4 species Atriplex rosea to produce F1 and F2 hybrids. All hybrids exhibited C3-like δ(13)C values, and had reduced rates of net CO2 assimilation compared with A. prostrata. The activities of the major C4 cycle enzymes PEP carboxylase, NAD-malic enzyme, and pyruvate-Pi dikinase in the hybrids were at most 36% of the C4 values. These results...

Eight CMS lines were crossed as lines with 31 genotypes as ‘testers’ to get 248 hybrids. The 248 hybrids were subjected to pollen and spikelet fertility analysis. Among the 248 hybrids 168 hybrids were expressed as restorers 52 as PR, 28 as maintainers. Ten tester’s viz., IR 62037, IR 72865, IR 68427, MDU5, TP1021, RR363-1, RR 347-1, RR 286-1, ACK 99017 and ASD06-08 were identified as restorers...

The river floodplain species Rorippa amphibia, Rorippa sylvestris, and their hybrid Rorippa x anceps were studied here, with the aim of identifying potential species differences with respect to flooding tolerance, and of assessing their expression in F1 hybrids. Parents and their F1 hybrids were subjected to three flooding treatments mimicking natural conditions, and growth-related and leaf mor...

Incidence of insect damage, and association of insect damage with mycotoxigenic corn ear molds and mycotoxins was examined in commercial fields of Bt and non-Bt hybrids of different backgrounds in Illinois in 1998 and 1999. Nearly 50% Helicoverpa zea (Boddie) infestation sometimes occurred in Bt hybrids that express high levels of the protein in silks and kernels. Damage by European corn borer,...

Development of Leishmania infantum/Leishmania major hybrids was studied in two sand fly species. In Phlebotomus papatasi, which supported development of L. major but not L. infantum, the hybrids produced heavy late-stage infections with high numbers of metacyclic promastigotes. In the permissive vector Lutzomyia longipalpis, all Leishmania strains included in this study developed well. Hybrids ...

Somatic cell hybrids generated from transgenic mouse cells have been used to examine the developmental regulation of human gamma-to-beta-globin gene switching. In hybrids between mouse erythroleukemia (MEL) cells and transgenic erythroblasts taken at various stages of development, there was regulated expression of the human fetal gamma and adult beta genes, reproducing the in vivo pattern prior...

Recently, dendritic cells (DCs) and DC-tumor cell hybrids (DC-tumor hybrids) have been used for cancer vaccine therapy in a clinical trial. DC-tumor hybrids combine the potent antigen-presenting capacity of DCs with the ability to present all tumor antigens expressed on tumor cells to T cells. We used DC-tumor hybrids as stimulator cells to induce tumor-specific cytotoxic T lymphocytes (CTLs) i...

Whole-cell fusion between zebrafish fibroblast-like ZF4 cells and mouse B78 melanoma cells resulted in hybrids containing one or a few zebrafish chromosome segments in a murine chromosomal background. Fluorescence in situ hybridization to hybrid cell metaphases with a zebrafish genomic DNA probe revealed that many hybrids contained zebrafish chromosome segments that were either inserted or tran...