Chromosome Banding in Amphibia. XXXVII. Y-Autosome Translocations in Anura

A detailed cytogenetic study on anurans belonging to the unranked taxon Terraranae revealed the existence of microscopically recognizable XY♂/XX♀ or ZZ♂/ZW♀ sex chromosomes in 11 species. Furthermore, in some species Y-autosome translocations were found, of which 5 could be confirmed. The male individuals carrying the Y-autosome translocations still coexist with the males showing the original karyotypes. The present report gives an overview on the mitotic and meiotic structure, staining and banding properties, functional importance, and similarities and differences of these Y-autosome translocations which are very rare in vertebrates. A mathematical model was constructed that calculates the various probabilities of further chromosome rearrangements in these karyotypes with Y-autosome translocations. The localization of the differential segment containing the hypothetical male sex-determining gene in the Y chromosome is discussed.

Establishment of Vibration Differential Equation and Analysis of Dynamics Characteristics for Curved Beam

In this paper, a differential segment of curved beam in the vibration state is analyzed, and the internal force equilibrium equations are established, then the vibration differential equations of curved beam are derived by considering Timoshenko’s geometric equations and physical equations. The vibration differential equations derived are similar to the Vlasov’s static differential equation of curved beam. By analyzing the vibration differential equations, some characteristics of vibration are obtained, and ideas of solving the vibration differential equations are also proposed. The vibration differential equations of curved beam can be reduced to those of corresponding straight beams, validating the derived vibration differential equation of curved beam.

DETERMINATION OF BREAKPOINT POSITIONS IN BARLEY TRANSLOCATIONS BY KARYOTYPE ANALYSIS OF PERMANENT RINGS OF SIX CHROMOSOMES

Five T1-5 and 10 T1-6 barley translocations were crossed with the translocation T1-7f. Plants in which the T1-5 and T1-6 translocations had been combined with T1-7f due to crossing over in the differential segment were selected in the F2 generation. One of the chromosomes present in plants carrying the translocations in the combined form is made up of parts of the three chromosomes involved in the two translocations, and the segmental arrangement of this tripartite chromosome is determined by the position of the breakpoints in chromosome 1. The karyotypes of these stocks were analyzed and the breakpoints in seven of the translocations were assigned to the same arm and eight to the opposite arm of chromosome 1 relative to the position of the breakpoint in T1-7f.