We examine the basis of Darwin's corollary to Haldane's rule, which describes viability and fertility differences between F1 produced from reciprocal crosses. We analyzed asymmetries in hybrid viability from >100 reciprocal crosses involving 36 toad species to test whether relatively high rates of mitochondrial vs. nuclear evolution produce dams with systematically less viable F1 hybrid progeny...

Caryotypic analysis of the cells dividing in mouse parent-hybrid MLC showed an F1 hybrid cell proliferation, which varied depending upon the source of lymphoid cells used: strong in spleen MLC (sometimes equal to that of the parental cells), less marked in lymph node cell MLC, and most often absent in MLC between cortisone-resistant (CR) thymocytes. MLC between parental spleen cells and F1 CR t...

In this study, the intergeneric hybrids F1, F2, BC1F1, BC1F2, and BC2F1 from Elytrigia elongata and Triticum aestivum crosses were produced to study their chromosome pairing behavior. The average E. elongata chromosome configuration of the two F1 hybrids agreed with the theoretical chromosome configuration of 21I+7II, indicating that the genomic constitution of this F1 hybrid was ABDStStEeEbEx....

Chinese cabbage (Brassica rapa L. var. pekinensis) is an important vegetable in Asia, and most Japanese commercial cultivars of Chinese cabbage use an F1 hybrid seed production system. Self-incompatibility is successfully used for the production of F1 hybrid seeds in B. rapa vegetables to avoid contamination by non-hybrid seeds, and the strength of self-incompatibility is important for harvesti...

Two F1 hybrids one between wild C. annuum var glabrisculum and C. frutescens (H1) and another between wild C. annuum var antigua and C. frutescens (H2) were obtained. Cytogenetic analysis of F1 hybrids showed that the parental genomes differ from each other by 2 or 1 translocations, 1 inversion and some minor structural alterations leading to reduced homologies between the respective parental g...

Evidence is presented that MHC restriction of foreign transplantation antigens occurs when tolerance is induced. Whereas PVG and F344 rats rendered tolerant at birth with (DA X PVG)F1 and (DA X F344)F1 hybrid bone marrow cells (BMC), respectively, accept ACI skin grafts, presumably because the foreign transplantation antigens of these third party grafts, which are MHC-compatible with DA, are re...

To study graft-versus-host reaction (GVHR) in small-bowel transplantation and its underlying mechanisms and to find methods for circumventing GVHR, we used an unidirectional GVHR model in which F1 Lewis (LEW) x Wistar King A (WKA) hybrid rats received small-bowel transplants from either LEW or WKA parent rats. The survival time of F1 hybrid rats that received full-length small-bowel transplanta...

Th is study has two main approaches. First, it exploits the susceptibility of tomato cultivars as a prophylactic measure to detect auto resistance characters of the tested tomato varieties against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Secondly, it evaluates the effi cacy of diff erent bio-rational insecticides against B. tabaci under greenhouse conditions. Th e results exhibited ...

European water frog hybrids Rana esculenta (Rana ridibunda x Rana lessonae) reproduce hemiclonally, transmitting only their ridibunda genome to gametes. We compared fitness-related larval life-history traits of natural R. esculenta from Poland with those of the two sympatric parental species and of newly generated F1 hybrids. Compared with either parental species, F1 hybrid offspring had higher...

A method is described for isolating the beta subunit from spinach chloroplast F1 (CF1). The isolated beta subunit reconstituted an active F1 hybrid with the F1 of Rhodospirillum rubrum chromatophores from which the beta subunit had been removed. The CF1 beta subunit was similar to the isolated beta subunit of Escherichia coli F1 (Gromet-Elhanan, Z., Khananshivili, D., Weiss, S., Kanazawa, H., a...