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Showing papers in "Journal of Genetics in 1959"


Journal ArticleDOI
TL;DR: In experimentally produced triploidGasterosteus aculeatus, the body size is similar to that of the normal diploid forms, but the proportions of the trunk and tail to the bodysize are different.
Abstract: 1. In experimentally produced triploidGasterosteus aculeatus, the body size is similar to that of the normal diploid forms, but the proportions of the trunk and tail to the body size are different. In triploids the trunk is proportionately shorter and the tail longer than in the diploid controls. 2. In the triploids, the nucleus and the cell size in cartilage, blood and nerve cells etc. are much larger and approximately bear a ratio of 3:2 to those of the corresponding cells in the diploid individuals. 3. The different organs like brain, retina, occipital arch, pronephric ducts etc., remain of the same size in both the triploids and the diploids; however, the number of cells in the triploid organs is less than those of the diploid. 4. In the triploid forms, the increase in size of the cells is compensated by a corresponding decrease in the number of cells, because in both the cases the size of the different organs remains more or less the same.

122 citations




Journal ArticleDOI
TL;DR: The resistance of Baumforth A to Amphorophora rubi is shown to be controlled by a single dominant gene, A1, which is linked with the normal allele of a semi-lethal gene,fr, designated Frilly, which confers high resistance both to the seedling and to the mature plant.
Abstract: The resistance of Baumforth A toAmphorophora rubi (Kalt.), is shown to be controlled by a single dominant gene,A 1, which is linked with the normal allele of a semi-lethal gene,fr, designated Frilly. The cross-over value of these two loci is approximately 3·3%. The geneA 1 confers high resistance both to the seedling and to the mature plant.

32 citations


Journal ArticleDOI
TL;DR: Significant sex differences in longevity were found in six of the nine inbred lines, in one of the twoF1 hybrid populations, and in the Galilee population, showing the importance of genes with sex-limited effects on longevity.
Abstract: Adult expectation of life ofDrosophila subobscura at 20°C. has been measured for nine inbred lines, for two kinds ofF1 hybrid between inbred lines, for theF1 from wild females caught in Kent, and for theF1 andF2 from wild females caught in Galilee.

32 citations


Journal ArticleDOI
TL;DR: This paper presents a meta-analyses of the effect of radiation on mitotic activity as observed through mitotic index determinations on exponentially increasing populations and the role of colchicine in this activity.
Abstract: V VI V I I V I I I I X Introduction Principle of the method Materials and experimental methods The effect of radiation on mitotic activity as observed through mitotic index determinations The effect of radiation on mitotic rate; mitotic delay Discussion and Conclusions Summary References Appendix I Quantitative details of the action of colchicine X Appendix I I 392 Analysis fbr exponentially increasing populations 371 373 378 387 388 389

31 citations


Journal ArticleDOI
TL;DR: It is suggested thatdpTP2 arose during the course of phenocopy selection as a consequence of the hot-shock treatment, and that this is the major difference between the dumpy and crossveinless experiments.
Abstract: 1. The phenocopy “dumpy”, produced by 40°C treatment of 16–18 hour pupae, was selected for 30 generations. The duration of treatment was gradually reduced from 4 1/2 to 2 hours. Phenocopy frequency in the last generation was 95%. 2. In untreated flies weakly dumpy wings first appeared in generation 25. From these an assimilated stock was established in which, after 8 generations of selection, penetrance was 58%. 3. The genetical analysis of this stock showed that assimilated dumpy is produced only in the presence of the recessive lethal genedp TP2. 4. There is evidence that a second recessive lethal gene, which forms withdp TP2 a balanced lethal system, enhances, and possibly is obligatory for, the production of the dumpy phenotype bydp TP2. 5. The frequency ofdp TP2, and possibly also of the second gene, was increased by phenocopy selection; the frequency of both genes was increased by selection without treatment. 6. Successful selection for expression in the assimilated dumpy stock indicated that modifying genes are also involved. The assimilation of dumpy, like that of crossveinless, appears therefore to have depended on major-genes and modifiers. 7. It is suggested thatdp TP2 arose during the course of phenocopy selection as a consequence of the hot-shock treatment, and that this is the major difference between the dumpy and crossveinless experiments.

31 citations



Journal ArticleDOI
TL;DR: Observation that blebs occur on pseudencephalic embryos is incompatible with Bonnevie’s hypothesis that they originate as cerebrospinal fluid in the myelencephalon; other observations support Plagens’ hypothesis that the blebs originate as mesenchymal intercellular fluid.
Abstract: The morphology and development of the many defects in mice of the Little & Bagg X-rayed stock have been reinvestigated, in an attempt to resolve the conflicts in the findings of earlier investigators. The observation that blebs occur on pseudencephalic embryos is incompatible with Bonnevie’s hypothesis that they originate as cerebrospinal fluid in the myelencephalon; other observations support Plagens’ hypothesis that the blebs originate as mesenchymal intercellular fluid. No unitary gene action was found. Four pedigrees of causes were constructed covering, respectively, defects of the central nervous system, bleb-induced lesions and defects of the body wall, morphological defects of the hind limbs, and defects of the urogenital system; there were cross-correlations between defects in the first three pedigrees, but the underlying mechanisms were not identified.

27 citations


Journal ArticleDOI
TL;DR: In this article, methods for identifying S allele homozygotes in inbred families from parents heterozygous for alleles which may have four possible dominance relations are discussed. But the authors did not consider the effect of self-incompatible plants on the identification of S alleles.
Abstract: 1. Methods for recognising S allele homozygotes in inbred families from parents heterozygous for alleles which may have four possible dominance relations are discussed. 2. Examples are given of the recognition in inbred families of homozygotes for two S alleles present in the parents when one allele is dominant in both pollen and style, when one allele is dominant in the pollen only, when one allele is dominant in the style only, and finally when both alleles are active in both pollen and style. 3. Self-compatible plants in the inbred offspring of self-incompatible plants may be either homozygous for a self-fertility allele in the S series or for a recessive allele independent of the S allele series. Female sterility may also be due to genes linked with the S alleles or independent of them. 4. Pseudo-compatibility occurred in many families, but it was possible to ignore it in the analysis of the pollination results for the recognition of S allele homozygotes.

26 citations


Journal ArticleDOI
TL;DR: The purpose of this paper is to find out to what extent there are regional differences in gene fiequencies and in quantitative characters in cat populations in different parts of the world, and what light these facts throw on the evolution of the domestic cat and on evolutionary phenomena in general.
Abstract: The domestic cat can, for several reasons, be regarded as very suitable material for work on population genetics. I t is polymorphic for coat colour, pattern, and various other :characters; moreover the genetics of this variation is fairly well understood. I t is common in large cities throughout the world, where it is usually divided into two social groups with little mr tua l intercourse. Show-cats comprise the smaller group; 'the}' are ,carefully bred and selected by, fancier's for exhibition purposes and are therefore much subject to human interference. The other larger and more heterogeneous group can .be called \"alley-cats\", including ordinary house-cats and feral or gear-feral \"strays\". These m'e commonly regarded as domesticated, yet they are much less dependent on man .than most animals of this category; so the?, can, in my opinion, be treated in man?, ways as natural populations. London alley-cats, for instance, appear to mate at random (Searle, 194-9), which suggests that human influence on their choice of mates is negligible. Human selection is exercised almost entirely by keeping some kittens and discarding others. Those discarded may be kiIled or just left by the wayside to fend for themselves, adding to the feral group if they survive. In much of Europe, but less commonly in Asia, human selection also operates by sterilising a high proportion of aduh males and some females too. Any differential effect which these selective forces may have, tending to change the frequency of a particuIar variant, can be ganged by making appropriate tests. This paper and a previous ot~.e on London's cats (Searle, 1949) are part of what is hoped will be a series, studying fiom an evolutionary aspect cat populations in different parts of the world. Its purpose wilt be to find out (i) to what extent there are regional differences in gene fiequencies and in quantitative characters, (ii) how far these are due to natural selection, artificial selection, local nmtations or other causes, (iii) what light :these facts throw on the evolution of the domestic cat and on evolutionary phenomena in general. Thc present paper deals particularly with a sample of the alley-cat polgulation of Singapore, analysing its polymorphism with respect to known genes. I t also gives data on a number of quantitative skull characters, which are likely to show geographical .variation, and considers a tooth character (loss of upper first molars) which turns out to be an example o1\" quasi-continuous variation. Details are given of the interesting \"kinky-tail '~ abnormality, which is apparently common throughout South-East Asia, but is very rare in Europe. Oene fi-equencv estimates for Singapore are compared with .figures for J a p a n and London; some striking differences are found and the meaning of these is discussed.

Journal ArticleDOI
TL;DR: It was found that the method is less efficient for measuring mutation rates than the specific-locus method, and a lower limit was set for the X-ray dose required to induce one recessive autosomal lethal genes in spermatogonia.
Abstract: A search has been made for X-ray induced recessive autosomal lethal genes in the mouse, using a method proposed by J.B.S. Haldane; the experiment was intended primarily to test the method. It was found that the method is less efficient for measuring mutation rates than the specific-locus method. Data obtained enabled a lower limit to be set for the X-ray dose required to induce one recessive autosomal lethal in spermatogonia, namely 810r; no upper limit could be set. Relevance to human problems is discussed.

Journal ArticleDOI
TL;DR: Oxygen consumption of the triploidGasterosteus aculeatus and their diploid controls has been determined by Winkler's method and the difference in the rate of respiration of triploids and diploids fish is significant if calculated per unit area of body surface.
Abstract: 1. Oxygen consumption of the triploidGasterosteus aculeatus and their diploid controls has been determined by Winkler’s method. 2. Triploids take less oxygen than the diploids. 3. The difference in the rate of respiration of triploid and diploid fish is significant if calculated per unit area of body surface instead of per gm. of body weight.

Journal ArticleDOI
TL;DR: Ferns belonging to the same area and representing the families Dennstaedtiaceae, Hypolepidaeeae, Lindsayaceae, Davalliaceae and Oleandraceae (classification according to Ching 1940) are worked out and it is felt that on the basis of chromosome data gathered so far and other morphological considerations the earlier part of Copeland's Pteridaceae should best be split into the families proposed by Ching.
Abstract: In some previo~ls communications (Mehra el. al. 1955, 56, 57a, b) the cytology of some ferns bclonging to the Darjeeling HimaIayas was described. In this communication some more ferns belonging to the same area and representing the families Dennstaedtiaceae, Hypolepidaeeae, Lindsayaceae, Davalliaceae and Oleandraceae (classification according to Ching 1940) are worked out. We do not agree with the classification of Polypodiaceae by Ching entirely, but we do feel that on the basis of chromosome data gathered so far and other morphological considerations the earlier part of Copeland's Pteridaceae should best be split into the families proposed by Ching, and we have followed him in the present paper. Manton and Sledge (1954) have already pointed out the unnaturalness of Copeland's comprehensive family Pteridaceae. The technique used was the same as previously described. All the plants were not uniformly suitable for cytological investigation. The members of Lindsayaceae and Davalliaceae were easy to work because of the large size of their spore mother cells and the readiness with which their chromosomes pick up the stain. About Dennstaedtia, the statement that Britton (1953) made should be repeated. \"The cytologist is confronted with another difficult subject. The chromosomes and spore mother cells are both small, consequently it is difficult to obtain outstanding plates\". This in fact is true also of other members of Dennstaedtiaceae investigated. tfypofepis deserves special mention because of its small sized chromosomes and difficulty in staining them; with-more mordanting than usual they would go black and stain erratically. Better methods could not be at tempted as the material was tried in the field. Hence it has not been possible to give an unequivocal number for this genus. A summary of the results obtained in the present investigation along with those of other authors on the same genera is presented in the Table I preceding discussion. Our sincere thanks are due to Mr. A. H. Alston of the British Museum for identifying the species of Aficrolepia and to Mr. R. S. Pathania of this department for taking the microphotographs.

Journal ArticleDOI
TL;DR: Following an outcross to a nonrelated production-bred strain, a White Leghorn stock no longer segregated for diplopodia in the normal 3:1 phenotypic ratio but produced significant deficiencies of diplodia phenotypes as mentioned in this paper.
Abstract: Following an outcross to a nonrelated production-bred strain, a White Leghorn stock no longer segregated for diplopodia in the normal 3:1 phenotypic ratio but produced significant deficiencies of diplopod phenotypes. A program of selection over a period of seven years was successful in creating three lines producing significantly different ratios. Line I was restored to the normal 3:1 ratio (26·2% diplopods); line III produced an average incidence ranging from 7·8% to a low of 4·3%; and line II gave intermediate levels ranging from a high value of 17·4% to 8·2% in the last year’s progeny.



Journal ArticleDOI
TL;DR: In this paper, several acid amides, namely acetamide, propionamide, butyramide, caproamide and benzamide, were found to increase the number of eye facets in theGlued Stubble (Gl, Sb/LVM) and brown mutants of D. melanogaster when they are taken with the agar-molasses food.
Abstract: 1. Several acid amides, namely acetamide, propionamide, butyramide, caproamide and benzamide were found to increase the number of eye-facets in theGlued Stubble (Gl, Sb/LVM) andbrown (bw) mutants ofD. melanogaster when they are taken with the agar-molasses food.

Journal ArticleDOI
TL;DR: Stickiness of the coat has been observed in some guinea-pigs bred in the Department of Pathology, Cambridge and chemical investigation has shown that an excessive amount of lipid is present on the hair.
Abstract: Stickiness of the coat has been observed in some guinea-pigs bred in the Department of Pathology, Cambridge. The condition has been found to be controlled by a single recessive factor with full penetrance and no effect on viability or fertility. Chemical investigation has shown that an excessive amount of lipid is present on the hair. The composition of the lipid differs from that on normal hair. No structural defect of the hair or skin has been discovered and no abnormality of the major organs has been found.

Journal ArticleDOI
TL;DR: The diplotene-diakinesis suppression appears to be correlated with the precocious activity of the division centres and dissolution of the nuclear membrane which result in the appearance of the spindle and chromosomal orientation so that the bivalents, after the pachytene, have not got enough time to undergo a regular course.
Abstract: 1. The cytological analysis of male meiosis inPeriplaneta americana does not reveal any chiasma formation in the natural population.

Journal ArticleDOI
TL;DR: Analysis of data from spaced plant nurseries on spread or “creep” of alfalfa parents and individual offspring indicated unexpectedly large estimates of genetic variance for clones and plants within families.
Abstract: Analysis of data from spaced plant nurseries on spread or “creep” of alfalfa parents and individual offspring indicated unexpectedly large estimates of genetic variance for clones and plants within families. These enhanced variances could not be explained by tetrasomy, linkage, or epistasis. The data could be largely explained by postulating a positive correlation between genetic effects and environmental effects. The rationale underlying the postulate was given. The chief consequence to the breeder was seen to be lowered heritability, and on that account, trivial gains from selection under the conditions of these trials.

Journal ArticleDOI
TL;DR: Several acid amides, namely acetamide, propionamide, butyramide, caproamide and benzamide were found to increase the number of eye-facets in the Glued Stubble andbrown mutant mutants of D. melanogaster when they are taken with the agar-molasses food.
Abstract: Summary1. Several acid amides, namely acetamide, propionamide, butyramide, caproamide and benzamide were found to increase the number of eye-facets in theGlued Stubble (Gl, Sb/LVM) andbrown (bw) mutants ofD. melanogaster when they are taken with the agar-molasses food.2. Each acid amide had a limited range of concentration at which its facet activity is well marked. If the concentration is slightly above this range, the mortality becomes very high, due to the toxicity of the chemical agents.3. The resistance of the two mutants towards the toxicity of the acid amides is the same.4. All the amides so far examined have augmented the eye of thebrown mutant to the size or even larger than that of the wild eye. This can be regarded as a phenocopy of the wild type.5. The effect of the acid amides is pronounced in the female but less distinct in the male.6. The action of the acid amides would seem not to be directly connected with the operation of theBar gene.

Journal ArticleDOI
TL;DR: All ureids and acid amides tested were found to be effective in increasing the eye-facets of theroughoid eye (rug) of D. melanogaster.
Abstract: Summary1. All ureids and acid amides tested were found to be effective in increasing the eye-facets of theroughoid eye (rug) ofD. melanogaster. This has been previously demonstrated forGlued Stubble andbrown.2. Each ureid or acid amide has a limited range of concentrations, at which its facet-increasing activity is marked. Within this range, there is an optimal concentration at which the facet number attains its maximum.3. It is emphasized that the increase of facets depends mainly on the nature and concentration of the ureid and acid amides tested as well as on the genotype and sex of the fly.4. The effect of the ureids is mostly, but not always, pronounced in the female and less distinct in the male.

Journal ArticleDOI
TL;DR: In this article, several amino acids, namely glycine, methionine, sarcosine, glycocyamine and creatine, were found to be effective in increasing the facet number of the roughoid eye of Drosophila melanogaster.
Abstract: 1. Several amino acids, namely glycine, methionine, sarcosine, glycocyamine and creatine were found to be effective increasing the facet number of theroughoid eye (ru g) ofDrosophila melanogaster. 2. Kaji’s claim (1955) that it is in the main, the substances which possess the — C O. N H.—group which have a marked effect in increasing the facet number of theBar eye is not applicable to theroughoid mutant. 3. The effect of the amino acids is more pronounced in the female than in the male.