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...

Host genetic control of the incubation period of Creutzfeldt-Jakob disease (CJD) was studied using various inbred strains of mice, including B10 congenic strains. Various incubation periods were found in mice injected either intracerebrally or intraperitoneally with the Fukuoka 1 strain of the CJD agent; NZW/Sea and A/JJms had the shortest, and B10.AKM/Ola and C57BL/6J the longest, incubation p...

"Ecological" speciation occurs when reproductive isolation evolves as a consequence of divergent selection between populations exploiting different resources or environments. We tested this hypothesis of speciation in a young stickleback species pair by measuring the direct contribution of ecological selection pressures to hybrid fitness. The two species (limnetic and benthic) are strongly diff...

The genetic basis of hybrid male sterility in house mice is complex, highly polygenic, and strongly X linked. Previous work suggested that there might be interactions between the Mus musculus musculus X and the M. m. domesticus Y with a large negative effect on sperm head morphology in hybrid males with an F1 autosomal background. To test this, we introgressed the M. m. domesticus Y onto a M. m...

Hybrid sterility in the heterogametic sex is a common feature of speciation in animals. In house mice, the contribution of the Mus musculus musculus X chromosome to hybrid male sterility is large. It is not known, however, whether F1 male sterility is caused by X-Y or X-autosome incompatibilities or a combination of both. We investigated the contribution of the M. musculus domesticus Y chromoso...

In this communication it is demonstrated that T cells from fully allogeneic A replaced by B radiation bone marrow chimeras are alloreactive against the hybrid Ia molecules expressed on the surface of heterozygous A X B cells. These results suggested that previous failures to generate cytotoxic T lymphocyte (CTL) responses from fully allogeneic chimeras by sensitizing the chimeric T cells to ant...

the identification of parental inbred lines to develop superior hybrids is a rather costly and time-consuming step in maize breeding. in some cases, pedigree information has been used to select diverse parental lines. in the case of iranian maize inbred lines, this information is not fully available. in this study we investigated the genetic distance (gd) based on simple sequence repeats (ssr) ...

Antigen-specific major histocompatibility complex (MHC)-restricted helper T cell precursors were induced to proliferate in cultures of keyhole limpet hemocyanin-primed lymph node cells. Clones of F1 hybrid helper T cells were isolated in limiting-dilution cultures. Each positive culture at a limiting-dilution of lymph node cells gave rise to > 10 helper T cells with a single MHC-restricted spec...

PURPOSE To determine the relationship between maximum workload (W(peak)), the workload at the onset of blood lactate accumulation (W(OBLA)), the lactate threshold (W(LTlog)) and the D(max) lactate threshold, and the average power output obtained during a 90-min (W(90-min)) and a 20-min (W(20-min)) time trial (TT) in a group of well-trained cyclists. METHODS Nine male cyclists (.VO(2max) 62.7 ...