Vaccination of adults with Wistar RA 27/3 rubella vaccine

Thirty-three adults were vaccinated subcutaneously with Wistar RA. 27/3 (live attenuated) rubella vaccine at the Wellcome Research Laboratories, Beckenham. All subjects with pre-vaccination haemagglutinating-inhibiting antibody titres of 1/20 or less and three of seven subjects with pre-vaccination titres of 1/40 showed at least fourfold rises of titre. Reactions encountered were mild and of short duration.

Chromosomal polymorphism in Pissodes weevils: further on incompatibility in P. terminalis

The North American Pissodes terminalis exhibits dual sexual dichotomy of its karyotype. Whereas females are invariably homozygous both for the sex chromosomes and a pair of metacentric autosomes (XC/XC), all males are double heterozygotes (XC/Ycc), one C being replaced by its corresponding twin acrocentrics. Consequently females produce only X/C eggs but, since meiotic orientation of the XY II and the Ccc III is random, males should produce four types of spermatozoa in equal proportions. If so, to render the dual dichotomy permanent, effective fertilization must perforce be solely by XC and Ycc sperms.Hybrids have been obtained between different taxa that are monomorphic either for two C-metacentrics or for their equivalent twin c-acrocentrics. When the cs in hybrid males are of paternal origin, the semi-incompatibility system (SIS), as seen in terminalis, is immediately synthesized and thereafter faithfully perpetuated. When, however, they are of maternal origin, free recombination ensues both in the F2and backcrosses. An identical alternate scheme of inheritance is displayed when terminalis is one or the other parent. Egg viability, sex ratio, late mortality, and family size in SIS hybrids show no significant deviation relative to those of monomorphic species or non-SIS hybrids. It is therefore concluded that the autosomal heterozygosity of SIS males is a consequence not of a balanced lethal mechanism but of selective fertilization. This system can be formally ascribed to translocation of a factor from one of the twin acrocentrics to the Y (Xcc: Ycc → Xcc/Y+c−c); thereby these two mutually compensating chromosomes became permanently linked in heredity and concomitantly excluded from females.The synthesis of the SIS in intra-complex hybrids demonstrates that the seeming random recombination in c-acrocentric species is illusory. They likewise possess a built-in SIS, one that is only exposed after crossing to C-metacentric females. Significantly, other species complexes in the genus also have an innate SIS, but they fail to conceal it because in males their c/c−II is readily visible. Thus it follows that the mutation did not originate in terminalis, a species of obvious recent origin.The absence of the system from C-metacentric taxa, we attribute to their obvious Robertsonian origin from c-acrocentric SIS species by centric fusion of nonhomologues. Such a fusion, by arising in the female, exempts the male c−from direct participation and, following introduction of the newly formed C chromosome into males(v. terminalis), merely await loss of the plus factor from the Y+to ensure the free recombination currently seen in C:C taxa, for Yc−c gametes should thereby be totally incapacitated.

Chilocorus similis Rossi: Disinterment and Case History

Cytological proof is presented that the Asiatic predator Chilocorus similis (Coleoptera, Coccinellidae), liberated in California sometime between the years 1923 and 1947, has since been masquerading there under the name C. orbus.

Unique Incompatibility System in a Hybrid Species

All males of the weevil Pissodes terminalis Hopp. are heterozygous for an autosomal fusion (cc --> C); all females are homozygous (CC). A mechanism is operative whereby union of like gametes gives rise to females and of unlike gametes gives rise to males, and union of half-alike gametes is totally excluded. The perpetuation of this sexual dimorphism of karyotypes following crossing implicates P. yosemite Hopk. in the hybrid origin of P. terminalis..