Showing papers in "Journal of Genetics in 1958"

The genetics of armadillidium vulgare latr: IV. Lines breeding true for amphogeny and thelygeny

Abstract: Summary1. Sex ratios of broods were studied in two lines of the woodlouse,Armadillidium vulgare. The two lines originated from two females, pregnant when collected from a wild population.2. One line was found to breed true for amphogeny (1:1 sex ratios), and the other line bred almost true for thelygeny (nearly 100% females).3. In the amphogenic line there was a small excess of females over males. Similar excesses of females are found in broods from amphogenic females of other woodlouse species.4. Sex determination in woodlice, the origin of monogenic broods, and the inheritance of monogeny are discussed.

The spread of genes by natural and artificial selection in closed poultry flock

Abstract: The pedigrees of birds in a poultry flock under artificial selection were analysed to trace the spread of genes from original flock members. The changes in gene percentage from generation to generation were separated into parts attributed to chance, natural and artificial selection. The changes due to artificial selection were related to various production characters. The spread of the male's genes was 70% determined by a progeny test which also 25% determined the spread of genes of birds mated to him. The progeny test of the female did not contribute equally to determination of the gene spread. This was attributed to lesser accuracy of the female progeny test and less complete determination of spread of genes by value of genotype. Despite avoidance of sib matings, inbrecding has increased 2% per generation. Evidence that natural selection was opposing artificial selection was suggestive but inconclusive. It was suggested that assortative mating would increase the determination of gene spread by genotypic value. This was considered worth testing.

Variation between strains of mice in phenomena associated with sperm penetration and fertilization

Abstract: :!:Itll.becoming apparent that not only do species within an Order differ between, them::s in respect of many, of the phenomena associated with ovulation, sperm passage, :'.Sperm penetration and earl),development of the egg, but that differences also exist ':be{ween strains within a sing]e species. Such variations constitute evidence for the !.g:~hgtic control os these phenomena, though whether few or many genes are invotved is .qu!te unknown. Interstrain variation in the incidence of abnormalities of egg matura:ii0n :and s has been. described in an earlypaper (Braden, 1957a); the variations .d~att' ~(,ith in the present paper are physiological rather than pathological. :;i .it has recentIy been shown that in many mammals the zona pelIucida, a macoprotein membrane that surrounds the vitellus, changes after the entry of the first sperm so as to . ; , . . ,

Further investigations on cytology of members of commelinaceae with special reference to the role of polyploidy and the origin of ecotypes

Abstract: Previous records 1lave sl~own the possibility of the occurrence of xaaturaI cytologlcaI -variants in several species of the family Commelinaceae. In an earlier commu~ica:tion by the author, the investigations were carried out chiefly o~a materlals collected from the plains. Hence a study of the different ecotypes within the same species could not be made. The reports of certain rare cases and the unusual cytological data, presezated formerly b y the senior author (Sharma, 1955) distinctly indicated the scope of cytologicalstudy of :::ecotypes within this family. [In Indian species too, the role ofpotyploidy and aneuploidy i n t h e evolution of differelat forms was clearly indicated. The most interesting fact :emerging from this paper was the evidence of tl~e presence of individuals wltla different : Chromosome xmmbers in the same species. Encouraged by these results, the different ecotypes, as well as other species, occurring i n the temperate and sub-temperate zo~ae of the Himalayas, were collected. The aim in view was to make a thorough study of the detailed cytoiogv of these different ecotypes ahd species. The project was materially laelped by the invention, of a number of improved techniques, recently devised from this Laboratory, critlcal enough to bring out even the minute cl~romosomal details. : In the present report, cytological data of eleven different species and ecotypes have )been incorporated. This sturdy clearly demo~strates the role of polyploidy in bringing :about tlae diversification of the members of thisfamily,

Genetic studies of the Syrian hamster I. The mutant genes cream, ruby-eye and piebald

Abstract: Three mutations in the Syrian hamster are described (cream, ruby-eye and piebald) and the six possible comparisons between the three mutants and sex have been studied for genetic linkage. No evidence for linkage could be found for five comparisons. The sixth comparison (ruby-eye-piebald) exhibited an aberrant segregation which could result from autosomal linkage or from an inviability interaction between the two mutants concerned. Two mutants (ruby-eye, piebald) display significant prenatal inviability and an attempt has been made to elucidate the nature of the prenatal loss. The hypothesis is discussed that the inviabilities observed are a consequence of an inter-dependence between “normal” foetal atrophy and the expected Mendelian proportion of susceptible phenotypes. Since hamster genetics is in its infancy—a plea is made for the publication of all segregation data (negative or otherwise), which can be collated biometrically at a later date.

The relationship between anthocyanidins and flavonols in different genotypes ofAntirrhinum majus

Abstract: In recet~_t years the flavonoid constituents of the petals of colou.r genotypes of Amirrhir*.u~n majus have been extensively investigated by Geissman and his associates in California (Geissman, Jorgensen and Johnson, 1954; Jorgensen arid. Geissman, 1955 a and b; Geissman and Harborne, 1955; Seikel, 1955) and a genetical study of flower colour in A. majus, using less rigorous chemical methods, has been made in this laboratoryby T. O. Dayton (1956). The results of these investigations differed in that the former workers fbund a greater number offlavonoid aglycones in different genotypes. In addition to aplgenin, luteolin, pelargonidin and cyanidln, reported by Dayton, they detected kaempferoI and quercetin. Kaempferot was shown to occur only in genotypes containing pelargonldin, and quercctin to occur in those containing cyanid.in. These several aglyeones were also shown by two-dimensional paper chromatography to be present in a much larger number ofglycosidated forms than was revealed in the study of Dayton. She reported, however, two glycosides of apigenin which only accompanied peIargonidin and an unidentified pigment which accompanied cyanidin. Because of the biosynthetic and genetical implications of the joint occurrence of pairs of compounds with a similar hydroxylation pattern, it is important to resolve the discrepancies between these two investigations. This has been attempted by comparing the homozygous genotypes used by Dayton with those used by Geissman et al.~ to determine the aglycones present in each. of the two groups.

A note on Reeve’s method for estimating heritability with assortative mating

Abstract: A modification is presented of Reeve’s (1953) method of estimating heritability from progeny tests when the parents are selected and mated assortatively.

Heritabilities of body length, depth, width, fore cannon length, fold score, and mutton score in Australian Merino sheep

Abstract: Data for body length, depth, width, fore cannon length, fold score and mutton score were collected on two groups of Peppin Merino ewe lambs. The experimental animals comprised 284 ewe lambs born in the spring of 1951 (group ‘A’) and 273 born in the autumn of 1952 (group ‘W’) at the Trangie Agricultural Experiment Station of the New South Wales Department of Agriculture.