Molecular structures of packageable ColE1 hybrids and the generation of deletion mutants from one of the hybrids

ColE1 derivatives carrying cohesive end sites of lambda phage genome (= cos lambda) can be packaged within lambda phage particles. The DNA structure of the prototype ColE1-cos lambda derivative named pKY2257 was studied because of its potential usefulness in various fields in molecular biology. pKY2257, which carries an intact galactose operon of E. coli, is a convenient replicon to detect Tn3 translocation. It was found that one of the PK2257::Tn3 derivatives, pKY2113, generated various small plasmids in E. coli. The molecular structures of some of these deletion mutants were compared with each other and with those of parental plasmid DNAs by heteroduplex analysis and restriction enzyme digestion. A possible mechanism, which seems to be unique to this kind of deletions, is discussed on the basis of the present results.     

Selection for the inviability of sterile hybrids

Complementary lethal, semilethal, and dwarfing genes whose effects appear to be expressed only in (usually sterile) interspecific hybrids are not uncommon in plants. Accounting for these genes by Darwinian selection has been somewhat puzzling. However, if luxuriant, sterile hybrid progeny compete with and tend to eliminate their pure-species half-sibs, genes that are detrimental to the growth and development of hybrid progeny will be favored by Darwinian selection; the selective advantage lies in the improved fertility of parental plants. This account, which deals largely with the corky gene of New World cotton species, contrasts events that may occur in plant and animal species.     

Determination of "hybrids" in simple hybrids of maize by SSR-PCR

The results of SSRP-analysis of molecular-genetic polymorphism in maize inbred lines and simple hybrids are presented. Character of inheritance of amplicons obtained by SSR-PCR-method was investigated. Test-system for determination of hybridity of simple maize hybrids was proposed, which showed high probability of exclusion of unrelative male forms.     

Species hybrids ofDigitalis

Molecular Genetics and Genomics -