Showing papers in "Journal of Genetics in 1965"

The nature of human genetic loads

Abstract: The rare recessive human genes which increase the mortality of inbred human beings may not all be kept in being by mutation. They may include relic genes which were useful in the past but are harmful today. They may also include genes kept in being by greater fitness of the heterozygote at loci where the other homozygote has a lowered fertility rather than a lowered viability.

Selection for a single pair of allelomorphs with complete replacement

Abstract: Recurrence equations are given for genotype frequencies at an autosomal or a sex-linked locus when selection is entirely prenatal, and all matings are equally fertile. In some cases stable polymorphism is possible. These do not necessarily require greater fitness of heterozygotes.

Genetic variation of differential growth ratio among individual organisms ofGerris lacustris linn. (hemiptera—heteroptera)

Abstract: Change in size and form of an organism or its part is a. natural outcome of growth. Orgaifisms reach their adult form by differerltial growth in different directions, caused by growths of parts of the body at rates diffcren t from the entire body. A formula, developed chiefly by Huxley, and known as the 'simple allometry formula or equation' or 'the 'law of constant differentid~ growth ratio' has been shown by him and others (Huxley, I982, 1950; Reeve and Huxley, 1945; Richards and Kavanagh, !945; Teissier, 1948, 1955; etc.) to be of wide usefulness in 'the study of form-differences associated with the growth of an organic life and in the understanding of the physiology of growth implicit in the development of form. The equation is,

Radiation-induced morphological mutant of jute

Abstract: Treatment of dry seeds ofCorchorus capsularis L. var. ‘D. 154’ with 18,000 r X-rays resulted in isolation of a true breeding morphological mutation in the X3 generation. The mutant was characterized by being dwarf, bearing small, narrow leaves, half opened flowers, fruits of varying sizes and low seed setting. The frequency and types of chromosomal abnormalities during meiosis in pollen mother cells and pollen grain sterility in the mutant and control plants in the X3 and X4 generations were studied. The regular occurrence of various types of meiotic abnormalities in a number of mutant generations was probably due to the presence of a mutated. gene or a number of genes. The inheritance of the mutant characteristic was apparently controlled by a recessive gene. The failure of formation of normal fruits and seeds was due to disturbances in megasporogenesis also.

A plan for evolving a new breed of dairy cattle by crossing indigenous and exotic breeds

Abstract: A plan for evolving a new breed of dairy cattle for increased milk production through inter-se breeding of Indian and exotic breeds, taking into account both the genetical and statistical considerations, has been discussed in detail. The choice of exotic and indigenous breeds to be used for cross-breeding, the specification of the strength of foundation stock and the manner of securing F2s and then interbreeding thereafter have been discussed. The pattern of selection among the females in successive stages of lactation which would maximise genetic gain per year has been worked out. The programme to be adopted for evaluation of sires and for their selection for further propagation has also been outlined.

A preliminary study on the direction of leaf spiral and phyllotaxy in jute

Abstract: Under the general conditions obtaining at this station, left and right spirals show close association with 2/5 and 3/8 phyllotaxis respectively in thecapsularis jute strain JRC-212.