Showing papers in "Journal of Genetics in 1960"
TL;DR: Lurcher, Lc, a new mutant of the house mouse with neuromuscular action, is semidominant and is lethal in the homozygote, which dies soon after birth.
Abstract: Lurcher, Lc, a new mutant of the house mouse with neuromuscular action, is semidominant and is lethal in the homozygote, which dies soon after birth. The cause of death is not known. It is in Linkage Group XI, lying about 8 centimorgans beyondwaved-1 with respect toWhite. Lurcher females have smaller litters.
158 citations
TL;DR: The all-male broods are not the result of some lethal factor which inhibited the development of the females, but of a genetical mechanism probably similar to that in the Platyfish as described by Gordon.
Abstract: 1. An un-named Tilapia belonging to themossambica group has been imported from Zanzibar and crossed with theTilapia mossambica Peters which has become acclimatised in Malaya. 2. Where an African male was mated with a Malayan female fish, the offspring were all males, or nearly so. 3. Where a Malayan male was mated with an African female, the offspring tended to show approximately a Mendelian sex-ratio of three males to one female. 3. Whereas the broods produced in the cross Malayan male by African female tended to be fewer than those produced by the pure-bred fish, the all-male broods resulting from the cross African male by Malayan female did not contain fewer fingerlings than the broods resulting from the crossing of pure-bred fish, in which there are about equal numbers of male and female fingerlings. 4. Therefore, the all-male broods are not the result of some lethal factor which inhibited the development of the females, but of a genetical mechanism probably similar to that in the Platyfish as described by Gordon. 5. The practical implications of the ability to breed fingerlings almost wholly of one sex, for the purpose of stocking commercial fishponds, are briefly stated.
144 citations
TL;DR: The present result offers a new theory of dominance which can account for the partial dominance in fitness of the normal alleles of “recessive” deleterious genes.
Abstract: It is demonstrated that by introducing what may be called the principle of minimum genetic load, the spontaneous mutation rate and the average degree of dominance of deleterious mutant genes may be derived theoretically from the total genetic damage and the rate of substitution of genes in horotelic evolution. The relations connecting these quantities may be expressed by a pair of equations:
$$\left. \begin{gathered} \Sigma _\mu = \frac{{0 \cdot 3419E}}{{\bar h}}\left( {1 + 1 \cdot 720\bar h + ...} \right) \hfill \\ \bar h = 0 \cdot 6838\sqrt {\frac{E}{{2D}}} \left( {1 + 1 \cdot 018 \sqrt {\frac{E}{{2D}}} + ...} \right) \hfill \\ \end{gathered} \right\}$$
, where Σμ is the spontaneous mutation rate per gamete per generation,h is the average degree of dominance in fitness of deleterious mutant genes,D is the total mutational damage or approximately the rate of inbreeding depression in fitness per unit increase in the inbreeding coefficient andE is the rate of substitution of genes in horotelic evolution. The above formulae are sufficiently simple to be checked by observational data now available. The present result offers, as a byproduct, a new theory of dominance which can account for the partial dominance in fitness of the normal alleles of “recessive” deleterious genes.
98 citations
TL;DR: A graphical method is given by which the selection differentials of the traits as well as the optimum combination of culling levels can be determined for any proportion of animals retained.
Abstract: The phenotypic and genetic effects of selection for two correlated traits at two independent culling levels are derived. A graphical method, accompanied by four charts, is given by which the selection differentials of the traits as well as the optimum combination of culling levels can be determined for any proportion of animals retained.
64 citations
TL;DR: The cost of natural selection is reduced by nearly 30% if one genotype is twice as fit as another.
Abstract: More precise expressions are given for the cost of natural selection. It is reduced by nearly 30% if one genotype is twice as fit as another.
46 citations
39 citations
35 citations
TL;DR: When two varieties of rice are planted together, either fully mixed, in alternate rows, or in separate halves of the same small plot surrounded by a dam, each may influence the yield of the other, the effect is as often unfavourable as favourable.
Abstract: When two varieties of rice are planted together, either fully mixed, in alternate rows, or in separate halves of the same small plot surrounded by a dam, each may influence the yield of the other. The effect is as often unfavourable as favourable. However cooperation occurs, and in the case most fully investigated the yield from alternate rows was 126% of the mean yield when the varieties were grown separately. In this case at least the favourable interaction takes place mainly through water, and disappears if the area is flooded.
32 citations
TL;DR: The results suggest that any proposal designed to explain homeostasis in maize must satisfy these two kinds of evidence: heterozygote superiority and differences among homozygotes.
Abstract: Within-plot coefficients of variability of F1 maize hybrids and of their inbred parents were determined for several plant and ear characteristics over a two-year period. The heterozygous hybrids as a group were found to be better buffered (lower coefficients of variation) than the homozygous parents in every characteristic. There appeared to be significant differences in buffering among the hybrids only for ear node height; the inbred parents, however, differed significantly among themselves in buffering for plant height, ear node height, maturity, ear weight, and ear length. These results suggest that any proposal designed to explain homeostasis in maize must satisfy these two kinds of evidence: heterozygote superiority and differences among homozygotes. A proposal is outlined invoking systems of alternative biosynthetic pathways which function under different environmental optima. These systems are controlled in maize heterozygotes by alternative alleles of a single gene or by non-alleles of two or more loci. In maize homozygotes they are controlled by non-alleles. The essential role of genic function at diverse environmental optima is emphasized.
31 citations
TL;DR: Inheritance ofHypertrichosis pinnae auris is investigated in two Brahman and one Aryakshatriya pedigrees from Andhra Pradesh and the mode of inheritance is compatible with the hypothesis that the character is Y-linked.
Abstract: Inheritance ofHypertrichosis pinnae auris is investigated in twoBrahman and oneAryakshatriya pedigrees from Andhra Pradesh. The mode of inheritance is compatible with the hypothesis that the character is Y-linked. The age of onset seems to be in late puberty. The improbability of alternative hypotheses is considered. About 6% of an unselected sample of 345 adult males in Andhra Pradesh were found to show such hypertrichosis.
27 citations
TL;DR: There was, however, a clear indication of reduced fertility with chromosome loss, as expected, and there is not enough evidence to support the view that the same chromosomes always pair and that the remainder are therefore relatively inert genetically and more expendable.
Abstract: 1. Aneuploidy occurs rarely in roses: about a hundred instances have been recorded since 1920. All reports are on cultivated (mostly hybrid) seedlings: none has so far been found in the wild. 2. Chromosome variation in progenies is always associated with phenotypic variation, but it is not possible to determine which changes are due to loss or gain of chromosomes and which to genetical segregation. 3. The aneuploids show no tendency to revert to euploids in the germ line, and in the one case tested even breed true for their somatic number. 4. Nearly all reports of aneuploidy belong to species of the one Section Caninae, which is characterised by heterogametic reproduction in which only half to one-third of the chromosomes pair, the remainder staying as univalents. But until some means can be found of identifying individual chromosomes, there is not enough evidence to support the view that the same chromosomes always pair and that the remainder are therefore relatively inert genetically and more expendable. 5. In straight competition with euploids, the aneuploids are not necessarily weaker, shorter lived or less fit. In one family only were aneuploids found that were obviously subnormal, and these had a maximum deficiency of 2 to 4 chromosomes. Thus neither competition between cells nor competition between whole plants would be expected to eliminate aneuploids in nature. There was, however, as expected, a clear indication of reduced fertility with chromosome loss. 6. The failure to discover aneuploids in the wild in the past has been fortuitous and due to the preference for cultivated plants as a convenient source of material.
TL;DR: Genetic progress in the progenies is likely to be more, if the seed parent is selected on high yield of copra and of nuts rather than on weight per husked-nut and flowering-period.
Abstract: Heritability values for the flowering-period, yield of nuts, yield of copra and weight per husked-nut of the coconut palm, have been estimated. Genetic correlations between these four characters have been ascertained. The heritability values for yield of copra and weight per husked-nut are high, for yield of nuts intermediate, and for the flowering-period low. The genetic correlation between yield of nuts and copra is high and positive, correlation between yield of copra and flowering-period is high and negative. Genetic progress in the progenies is likely to be more, if the seed parent is selected on high yield of copra and of nuts rather than on weight per husked-nut and flowering-period.
TL;DR: It has been suggested that the species of this genus represent a homogeneous assemblage in spite of the fact that inconstancy in chromosome number is noted within a species, and the presence of a number of chromosomal biotypes indicates that such aneuploid numbers often arise.
Abstract: Detailed study of the structure and behaviour of chromosomes in the somatic tissue of twenty-one species of the genusDracaena has been made and the “normal” chromosome numbers of all these species have been reported for the first time in this paper. The previous and the present records suggest that most of the species possess a number of chromosomal biotypes. These biotypes mainly differ with respect to their chromosome numbers. Relationship between species showing multiples of different series of chromosome numbers, viz. eight, ten, thirteen, seventeen and nineteen has been indicated. On the basis of the fact that a general resemblance in gross morphology of chromosomes and similarity in total amount of chromatin length are present amongst different species of the genusDracaena, it has been suggested that the species of this genus represent a homogeneous assemblage in spite of the fact that inconstancy in chromosome number is noted within a species. The different lines have mainly been assumed to have come out through continued production of aneuploid numbers during evolution. The presence of a number of chromosomal biotypes indicates that such aneuploid numbers often arise. Minor differences in details of chromosome morphology, and the presence of super-numerary constrictions in certain species, have been regarded as proving that structural changes of chromosomes have also played a distinct role in evolution of the species. As the different species ofDracaena are propagated exclusively through vegetative means, the only explanation for the origin of biotypes which can be suggested is that the recorded variant nuclei enter into the formation of new daughter shoots from which new individuals originate with different genomic constitutions. As flowers are scarcely noted and sexual reproduction is entirely ineffective with respect to propagation, this seems to be the only way through which speciation is effected here.
TL;DR: The distribution of phenotypes in the selected populations suggests that the developmental system is such that scores of more than 11 or less than 2 cannot easily be obtained, and both the variance of the score and the sex difference in score were greatest in populations whose mean score was at the centre of the range.
Abstract: The present investigation describes the effect of selection and of outbreeding and inbreeding on expression of theocelli-less mutant, variable for the number of ocelli and head bristles, inDrosophila subobscura.
TL;DR: Hypocatalasaemia in guinea-pigs, which is accompanied by hypoenzymic catalasea of other organs, is transmitted by heredity independent of the sex of the animal, and is a recessive character.
Abstract: Hypocatalasaemia in guinea-pigs, which is accompanied by hypoenzymic catalasea of other organs, is transmitted by heredity independent of the sex of the animal, and is a recessive character. While with the first generation produced from the crossing of hypocatalasaemic and normal animals the blood contains the normal quantity of catalase, in the second generation about 25% of the offspring display hypocatalasaemia.
TL;DR: Karp’s data on the genetical determination of viability, longevity and fertility in Drosophila melanogaster are analysed and it is shown that Heterozygosity is not always advantageous.
Abstract: Karp’s data on the genetical determination of viability, longevity and fertility inDrosophila melanogaster are analysed. These characters are usually affected alike by the substitution of chromosome segments. Heterozygosity is not always advantageous.
TL;DR: The published data on possible genetic linkage are reviewed and statistically combined to provide estimates of the closest linkage compatible with the apparent random assortment or the recombination fraction where random assortment is contradicted.
Abstract: The published data on possible genetic linkage are reviewed and statistically combined to provide estimates of (a) the closest linkage compatible with the apparent random assortment or (b) the recombination fraction where random assortment is contradicted. Various aspects of linkage detection and linkage analysis are discussed.
TL;DR: Comparison of seed fertilities of the three clones with their cytology suggests that embryo-sac formation is limiting to fertility in at least two of them, and in ‘Gros Michel’, by contrast, embryo sac frequency far exceeds fertility, thus giving some encouragement to the banana breeder's hope of manipulating the seed yield of this clone.
Abstract: The female cytology of three edible triploid banana clones (‘Mysore’, ‘Pisang awak’, ‘Bluggoe’) is described. Irregularities of meiosis and embryo-sac formation are numerous and development is often delayed in respect to ovary development or altogether arrested. Mature embryo-sacs are therefore rare. Comparison of seed fertilities of the three clones with their cytology suggests that embryo-sac formation is limiting to fertility in at least two of them. In ‘Gros Michel’, by contrast, embryo sac frequency far exceeds fertility, thus giving some encouragement to the banana breeder’s hope of manipulating the seed yield of this clone. The observations, for technical and statistical reasons, give little information about the origin of polyploid progeny; indirect inference suggests that both “Rosenberg” and “Musa-type” restitutions are concerned.
TL;DR: An analysis of Carter's data on the induction by X-rays of autosomal recessive genes in mice leads to the conclusion that he almost certainly obtained two, and very probably three such lethals in his irradiated stock, whereas he only claims to have obtained one.
Abstract: An analysis of Carter’s data on the induction by X-rays of autosomal recessive genes in mice leads to the conclusion that he almost certainly obtained two, and very probably three such lethals in his irradiated stock, whereas he only claims to have obtained one.
TL;DR: The occurrence of pairing within the haploid set of chromosomes derived from one diploid species appears to be suggestive of the possible existence of two subgenomes within the Haploid genome but further studies of the whole genus are required for a verification of this possibility.
Abstract: The nature of chromosome pairing at meiosis in some tuberiferous Solanums (2n, 3n and 4n) is described. A number of abnormalities have been noted at meiosis in the diploids including the formation of multivalents and univalents. Although the occurrence of univalents as early as diakinesis suggested that chromosomal differences do exist, the evidence from the diploids as to the nature of the basic genome in Solanum is not clear cut. An examination of meiosis in triploid hybrids (4n × 2n) revealed a considerably higher value for the mean number of bivalents plus trivalents per cell at metaphase I (14.2; 13.5; and 13.3) than has heretofore been reported. The maximum number of such associations recorded was 16. It appears that in the hybrid between the induced tetraploidS. chacoense (n=24) andS. neohawkesii (n=12), at least 8 out of the 12 chromosomes from the diploid parent are capable of exhibiting partial homology. The analysis of pairing in the triple hybrids ((6n × 2n) × 4n) is more complicated. However, there are some indications that autosyndetic pairing within the complement of chromosomes derived from the 4n parent may exist. The occurrence of pairing within the haploid set of chromosomes derived from one diploid species appears to be suggestive of the possible existence of two subgenomes within the haploid genome but further studies of the whole genus are required for a verification of this possibility.
TL;DR: Expressions are given for the effect of selection in a population in which variation is due to a pair of genes at one locus, and the fraction culled in each generation is constant.
Abstract: Expressions are given for the effect of selection in a population in which variation is due to a pair of genes at one locus, and the fraction culled in each generation is constant.
TL;DR: The mean lengths of the long styles on the first two plants show a significant rise and later a decrease as the day temperature rose and fell during the season, therefore such a variation could play some part in the evolution of both dioecy and dicliny.
Abstract: The lengths of 3,427 styles from five bushes ofBauhinia acuminata L. ranged from 2 mm to 27 mm with modes at 5 and 20 millimetres. No flower had a style of 11 mm in length and only 26 flowers had style lengths between 8 mm and 10 mm. The fractions of short styled flowers obtained from the 5 bushes were 24.2%, 11.4%, 22.6%, 21.9%, and 6.1%. No order has yet been recognised in the position of the two types of flowers on any of the five bushes.
TL;DR: An iteration relation is obtained for the estimation of heterozygosity at any generation from the previous generation in cases of the plants where either selfing or natural cross-fertilization or both occur in varying proportions and the recessive phenotypes are completely eliminated.
Abstract: The estimation of the amount of heterozygosity at any generation in plants helps the breeders in successful selection procedure and in the task of hybridization. An iteration relation is obtained for the estimation of heterozygosity at any generation from the previous generation in cases of the plants where either selfing or natural cross-fertilization or both occur in varying proportions and the recessive phenotypes are completely eliminated. The relationship is of the form:h n+1=ψ (h n ), whereh n is the proportion of heterozygosity andψ (h n ) is a nonlinear equation. The proportions of heterozygosity up to the 40th generation for different values of the proportion of natural crossing (c), ranging fromc=0.0 toc=1.0 are worked out. The study was made for getting suitable expressions ofh n in terms ofn for different values of the proportions of natural crossing.
TL;DR: Xenia is of small importance in kernel weight and % protein, but of considerable importance in % oil, as well as other characters in maize.
Abstract: Published data are analysed to investigate the effect of the pollen parent on various characters in maize. Xenia is of small importance in kernel weight and % protein, but of considerable importance in % oil.
TL;DR: Hibisctls sabda@~-a L., which yields an important bast fibre, has gained considerable commercial importance in recent years as a close substitute for jute.
Abstract: Hibisctls sabda@~-a L., which yields an important bast fibre, has gained considerable commercial importance in recent years as a close substitute for jute. Howard and Howard (1911, t924) in com'se of their investigations of Indian fibre plants, studied. the different pigmentation patterns of this species and isolated and described four Varieties, namely tuber, dbus, inlermedius and bhagalpuriensis. Tt~ey stated that excep~ for the pigmentation character, all the four varieties were ahnost identical morphologi:cally; only in the variety bhagatpuriensis, the calyx was slightly obtuse and more twisted ~than ~r~ the other varieties. None of these varieties were, however, suitable for fibre :production as they were dwarf and bushy in habits. The main distinguishing characters :el\" the varieties as described by the Howards are summarised below : -
TL;DR: By using the method of Generating Functions, it is shown that in case of full-sib-matings in each generation, the Coefficient of Inbreeding in then-th generation is 0·948e−9·212n [1 + (−1)n].
Abstract: By using the method of Generating Functions, it is shown that in case of full-sib-matings in each generation, the Coefficient of Inbreeding in then-th generation (assuming that in the “zero-th” generation, where the inbreeding began, this coefficient was zero) is 0·948e−9·212n [1 + (−1)n. 0·0557e−0·962n].
TL;DR: High frequency of phage induced mutations in strain H-6 ofActinomyces olivaceus, amounting in some cases to 98%, is shown experimentally, and the term “mutational spectrum” is introduced.
Abstract: 1. High frequency of phage induced mutations in strain H-6 ofActinomyces olivaceus, amounting in some cases to 98%, is shown experimentally. Certain types of phage induced mutations resemble those induced by ultra-violet irradiation. 2. Each phage is shown to have its specific mutagenic effect, both for the frequency and the character of mutations. On this basis the term “mutational spectrum” is introduced. 3. The character of genetic information of actinophage, i.e. “mutational spectrum”, is shown to be determined by the genetic characteristics of the actinomycete culture, on which the actinophage is reproduced. 4. Biochemical mutants are shown to be produced under the action of actinophage.
TL;DR: This study was undertaken to complete a deficiency in knowledge on the relative importance of heredity and environment in mutton type and fleece characteristics in Australian Merino sheep.
Abstract: The Australian Merino is primari[y a wool I)roduciag sheep. Investigations into the factors alt'ecLiug mutton production in this breed seems desirable, however, in case the development of the artificial fibres lowers the relative importance of wool, and because the Meriao is a maintenance breed in the str~lification of the Australian sheep industry (Nichols 1945). Taneja (1955 a, b, c) studied the characte~'istics desired for selection for improving the mutton qualities in this breed. The heritabilities of and the genetic correlations amongst these characteristics have also been reported (Taneja 1958 a, b). In order to improve both mutton and wool qualities in this breed, the knowledge of genetic and phenotypic parameters is essential. Morley (1951, 1956) reported the heritabilities of, and the genetic correlations amongst the fleece characteristics in Australian Merino sheep. Itowever, no study has been made t~ estimate the genetic correlations of each of the fleece characteristics with mutton type. Besides this, knowledge on the relative importance of heredity and environment in mutton type and fleece characteristics is also lacking. This study was, therefore, undertaken to complete this deficiency.