PR-domain 9 (Prdm9) is the first hybrid sterility gene identified in mammals. The incompatibility between Prdm9 from Mus musculus domesticus (Mmd; the B6 strain) and the Hstx2 region of chromosome (Chr) X from M. m. musculus (Mmm; the PWD strain) participates in the complete meiotic arrest of mouse intersubspecific (PWD×B6)F1 hybrid males. Other studies suggest that also semisterile intersubspe...

On 16 December 2016, Vanessa Cameron retires as Chief Executive of the Royal College of Psychiatrists. She started working there in September 1980 and in 1984 she became Secretary of the College, the role that preceded chief executive. The College was formed in 1971, so Vanessa has been present for most of its lifetime. It has been a period of continuous change that has seen psychiatry leave th...

A combination of mouse inbred strains was studied, in which foetal but not placental weight is greater in the F1 hybrid than in the inbred litters. Gestation period was found to be shorter for the F1 hybrid than for the inbred litters. It is concluded that, insofar as the length of gestation is inversely related to the mass of the conceptuses, it is the foetus rather than the placenta which mat...

The attributes of the test grafts with which putatively tolerant rats are challenged influence their immune response. Lewis (Lew) rats inoculated at birth with Lew/BN F1 hybrid bone marrow cells accept large skin allografts more readily than small allografts, and F1 hybrid skin grafts survive better than BN transplants. The results indicate that the survivals of these major histocompatibility c...

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...