Showing papers in "Journal of Genetics in 1935"
TL;DR: The rate of mutation at which the gene for haemophilia appears in the population of London is estimated at about once in 50,000 human life cycles, with the milder type arising less frequently by mutation than the severe type.
Abstract: The rate of mutation at which the gene for haemophilia appears in the population of London is estimated at about once in 50,000 human life cycles. There are probably two distinct allelomorphs at the same locus, the milder type arising less frequently by mutation than the severe type.
495 citations
201 citations
TL;DR: Separation in multivalmlts--Tei;r~l)loid segregation, and the attached X line of .Drosol)hila, are presented.
Abstract: CONTENTS, I~AGE Introduction 53 Sop~ra~ion in bivMents 54 (i) Cy~ologic,~l considerations 54 (ii) UnequN bivalen~s 61 (iii) ToLrad ~nalysis iH bhe lower plan~s 62 (iv) The mosMo S~l'Mn of ]3om.bffx ,mori 6-1 (v) ])~oduction oorroh~tion bebween fl'eely recombiuing genes 65 (vi) The attached X line of .Drosol)hila, 66 Separation in multivalmlts--Tei;r~l)loid segregation 70 Summ~ry 76 ~efe, rences 77
180 citations
TL;DR: It appears that in a population in which the mean of some measurable character is at the optimum, the parent-offspring and fraternal correlations in adaptive value are approximately the squares of the corresponding correlations with respect to the character itself, whatever environmental complications there may be.
Abstract: The formulae for the mean and variance of squared deviations from an optimum are given for the cases of no dominance and of complete dominance, first assuming no environmental complications but later removing this restriction. The variance in each case is analysed into contributions due to (1) additive gene effects, (2) dominance deviations, (3) epistatic deviations, (4) environmental effects and (5) nonadditive joint effects of heredity and environment. In the case of complete dominance, formulae are developed which apply to epistatic relations in general. These lead to formulae for the correlations between parent and offspring and between two offspring. It appears that in a population in which the mean of some measurable character is at the optimum, the parent-offspring and fraternal correlations in adaptive value are approximately the squares of the corresponding correlations with respect to the character itself, whatever environmental complications there may be. Where the mean is not at the optimum, there is less difference between the correlations in adaptive value and the corresponding ones with respect to the character itself.
178 citations
TL;DR: The conclusion has been drawn that a single rare dominant gene is the main causative factor and the mutation rate of this gene in man may be as high as 1/60,000 per individual per generation and is not likely to be lower than 1/120,000.
Abstract: Twenty family histories of institutional cases suffering from mental defect associated with sebaceous adenoma have been investigated The conclusion has been drawn that a single rare dominant gene is the main causative factor An appreciable number of cases—the majority of whom are idiots—are thought to have arisen by mutation It is estimated that the mutation rate of this gene in man may be as high as 1/60,000 per individual per generation and is not likely to be lower than 1/120,000 The great variety found in the clinical manifestations is attributed to the influence of extraneous modifying factors which are mainly independent genes
118 citations
TL;DR: The chromosome numbers of about 120 species representing 25 genera of the family Malvaceae have been described and the cytological groups in these genera appear to be associated with taxonomical groups or certain morphological characters.
Abstract: Summary1. In the present study the chromosome numbers of about 120 species representing 25 genera of the family Malvaceae have been described. The following chromosome numbers were found: 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 25, 26, 28, 33, 35, 36, 38, 39, 42, 46, 56 and 65.2. Evidence has been presented in favour of the following chromosome series: (a) a five series (5, 10, 15, 25); (b) a six series (12, 18, 36); (c) a seven series (7, 14, 21, 28, 35, 42, 56); (d) an eleven series (11, 22, 33); and (e) a thirteen series (13, 26, 39, 65).3. In most genera, all species examined are members of the same chromosome series (i.e. Althaea, Pavonia, Gossypium). Some genera, however, contain different chromosome series,i.e. Abutilon (8 and 7 series);Malvastrum (12 and 15 series, and a few numbers represented by a single specimen); andHibiscus (11, 12 (18, 36), 14 (28), 17, 19 and several others). The cytological groups in these genera appear to be associated with taxonomical groups or certain morphological characters (cf. Discussion and General Summary).
96 citations
TL;DR: Gossypium Davidsonii (n = 13), a wild species from California, has smaller chromosomes than G. Sturtii (N = 13) from Australia as discussed by the authors, which enables a distinction between the paternal and the maternal chromosomes to be made.
Abstract: 1.Gossypium Davidsonii (n = 13), a wild species from California, has smaller chromosomes thanG. Sturtii (n = 13), a wild species from Australia. This difference in chromosome size is maintained in the hybrid, and enables a distinction between the paternal and the maternal chromosomes to be made. 2. The chromosome pairing in the hybrid is incomplete, but allosyndesis takes place about nine times more often than autosyndesis. Univalents are just as frequent between the small chromosomes fromG. Davidsonii, as between the larger chromosomes fromG. Sturtii. 3. The chiasma frequency is the same in the pure species despite the difference in chromosome size. Contrasted with the pure species, the chiasma frequency in the hybrid is significantly smaller in the bivalents containing aDavidsonii and aSturtii chromosome. 4. The difference in the size of the chromosomes of the species under observation is in all probability neither the result of genetic factors, nor associated with a difference in pairing blocks.
86 citations
TL;DR: Interaction of factors (a) Interaction of Y and I and (b) Infieraetion ofA ~nd I . (e) Interact ion of B and I .
Abstract: Off) Interaction of factors (a) Interaction of Y and I . (b) Infieraetion ofA ~nd I . (e) Interact ion of B and I . (d) Interaction of Y with A and B (c) l!)~fiflerns (f) Cumulative effects l)~rfi If. Chemistry . (i) The flower pigments of Dahlia . (c 0 Fla,vones (b) Anthocyalfins (ii) GeneticM ~speet of ehemicM results (a) Dahlic~ sI)eeios ~md species hybrids (b) D. variabilis . (1) ]J'lowers wi th non-yellow grounds (2) Flowers ~dth yellow grounds (3) ]~'[Ut o,tions (c) CqenerM observations Journ . of Genetics x x x rAGE 156 157 159 159 159 162 166 166 t68 168 168 173 178 181 185 186 187 187 187 190 196
65 citations
TL;DR: When a foreign gene is being bred into a pure line, or when a population with a lethal gene, incomplete sex linkage, heterostylism, or self-sterility is being inbred, the population is kept heterozygous for a particular gene or chromosome segment, but otherwise inbred.
Abstract: When a foreign gene is being bred into a pure line, or when a population with a lethal gene, incomplete sex linkage, heterostylism, or self-sterility is being inbred, the population is kept heterozygous for a particular gene or chromosome segment, but otherwise inbred. In these cases expressions are found for the probability of introducing a gene linked with the given gene, or for finding such a linked gene still heterozygous after inbreeding. Expressions are also found for the mean length of foreign chromosome introduced, or the length of chromosome remaining heterozygous (Table VI). The difficulty of introducing a single gene without any linked genes is emphasised.
65 citations
TL;DR: In this paper, a linkage test was made between the genes for single-comb and for the Creeper condition in fowl, and four geographically different lines or Creeper chickens were used in the matings.
Abstract: Linkage tests were made between the genes for single-comb and for the Creeper condition in fowl. Four geographically different lines or Creeper chickens were used in the matings. Chickens which were heterozygous for Creeper and rose-comb were crossed to others which were homozygous for the two recessive genes (normal skeleton and single-comb). Both heterozygous males and females were used in these back-crosses. The experiments extended over the first and second laying year. The total progeny of these matings amounted to 6627 individuals.
63 citations
TL;DR: The multivalent configurations in the triploid and tetraploid Lycopersicum esculentum are of the types which would be expected, if they were determined by a random distribution of chiasmata, as they vary in frequency from cell to cell, but remain statistically constant at successive stages.
Abstract: 1. The multivalent configurations in the triploid and tetraploidLycopersicum esculentum are of the types which would be expected, if they were determined by a random distribution of chiasmata. 2. They vary in frequency from cell to cell, but remain statistically constant at successive stages, as they would be expected to do on this assumption. 3. The configurations (contrary to the opinion of previous authors, but as is expected on analogy with all other cases of chiasma pairing) are constant between diplotene and metaphase. 4. The metaphase chiasma frequency is highest in the diploid and lowest in the triploid. This is attributed to a similar difference in original chiasma frequency rather than to a greater reduction in number in the triploid during terminalisation. 5. The curve of variance is higher in the polyploids than in the diploids, as has previously been found inTulipa andHyacinthus. 6. The formation of trivalents and univalents in the triploid gives rise to irregularities in the second division, and to the formation of restitution nuclei. 7. The formation of quadrivalents in the tetraploid leads to numerical non-disjunction which is reflected in reduced fertility.
TL;DR: The linkage values found in different families show a remarkable constancy, and in two regions linkage is tighter on the male than on the female side, in two looser, while in two others it is nearly the same.
Abstract: Summary1. Fifteen factors have been located on four out of the twelve chromosomes. Some other linkages are suspected, and a new case of multiple allelomorphism or very close linkage is described.2. As compared withDrosophila, interference is definitely less marked, though it certainly occurs.3. In two regions linkage is tighter on the male than on the female side, in two looser, while in two others it is nearly the same. Apart from this the figures are inadequate for a judgment.4. In one chromosome the genetical data from the tetraploid permit the rough location of a spindle attachment.5. The linkage values found in different families show a remarkable constancy.6. New mathematical methods are given for dealing with goodness of fit, combination of linkage data, and allowance for double cross-overs when mapping.
TL;DR: Evidence is presented indicating that some of the unbalanced zygotes may develop normally, and this rules out the possibility that they are the result of the segregation of a simple recessive gene.
Abstract: A line of mice, designated as the T1 stock, which has been derived from a single male whose father was X-rayed, is characterised by the production of about 4·6 per cent. of abnormal embryos, and of a somewhat smaller percentage of abnormal young at term. The abnormality consists of a failure of the neural groove to close throughout a portion of its anterior end. In most of the defective embryos the diencephalon, mesencephalon, and metencephalon are open, in a few only the diencephalon and mesencephalon, but no two embryos are exactly alike in the extent of the defect. Apart from the open condition of the brain roof, most of the parts of the brain have formed in a normal or almost normal fashion, but in some of the embryos curious aberrations in the development of the telencephalon or of the plexuses or of other brain regions are to be found. In the embryos at term, the roof of the cranium is lacking, though the roofing bones are represented at least by centres of ossification at the sides of the head. The abnormal embryos are produced not only when two individuals of the T1 stock are mated together, but also when certain individuals of this stock are mated to normals from untreated stocks. This rules out the possibility that they are the result of the segregation of a simple recessive gene. They probably are caused by the segregation of an X-ray-induced translocation. Mice heterozygous for the translocation produce occasional gametes carrying unbalanced chromosome combinations, and these gametes give rise to the abnormal embryos. Evidence is presented indicating that some of the unbalanced zygotes may develop normally.
TL;DR: Univalent formation in progeny from a diploid branch of a haploid individual ofCrepis capillaris belonging to theX strain is caused through failure of chiasma formation between homologous chromosomes which are shown to be regularly associated at pachytene.
Abstract: Part I. 1. Univalent formation in progeny from a diploid branch of a haploid individual ofCrepis capillaris belonging to theX strain is caused through failure of chiasma formation between homologous chromosomes which are shown to be regularly associated at pachytene. 2. A significant difference in the amount of univalent formation is found between two plants, and between two buds on the same plant. 3. Chiasma frequency is reduced in all three kinds of bivalents, and there is an almost direct relation between the amount of chiasma formation and the size of chromosomes. This is shown by the percentage of univalents and the mean number of chiasmata per bivalent. 4. Univalent homologous chromosomes frequently lie in juxtaposition at diakinesis. This is considered to be due to their previous association and coiling at pachytene and early diplotene. Part II. 5. TheA bivalents in a single plant ofCrepis capillaris have a reduced frequency and an abnormal distribution of chiasmata. In bivalents with single interstitial chiasmata, 95 per cent. have the chiasma in a subterminal position at the end of the long arm. Univalents of these chromosomes are occasionally found, and unpaired threads are observed at pachytene. Chiasma formation and possibly pairing are therefore restricted in one region of the chromosome.
TL;DR: It is a revolution for one who is accustomed to genetics through a microscope to be tempted to examine a problem which has only assumed a cytological aspect the last few years, and any theories about crossing-over must rest either on the evidence of cytology or on that of genetics.
Abstract: Caoss:Nc,-ovEa has always in practice been a geneticist's problem. We think of crossing-over in terms of the work of experimental breeding first carried out with DrosophiZe~. at Columbia University. I t is therefore something o~ a revolution for one who is accustomed to s tudy genetics through a microscope to a t tempt to examine a problem which has only assumed a cytological aspect dm'ing the last few years. But though ]3ateson, a geneticist, discovered linkage between Mendelian factors, it was Janssens, a cytologist, who invented the idea of crossing-over between chromosomes which was later used by the geneticists to explain this linkage f\" I believe that aanssens was as ignorant, in the early stages, of the work of Bateson, as Bateson was of t h a t of Janssens. There was an unfortunate separation between the two sciences of cytology andgenetics which still persists to the present day, and may perhaps always persist. This separation is unfortm:ate when it is based on lack of understanding. If it occurs it must be deliberate, and a deliberate separation is indeed necessary for certain purposes, paradoxical though this may seem. We must rest any theories we may have about crossing-over either on the evidence of cytology or on that of genetics. We must induce the principles of the behaviour of the hereditary mechanism from one set of observations or the other, separately, in order that we may know what assumptions we have made (cytological or genetical) in arriving at each particular
TL;DR: In the course of a study of an interspecific hybrid between Arena sativa gigantica and A. fatua (Philp, 1933) it was found that one family 28- 360, 28-360-30 consisted of 9 green and 61 albino seedlings, which died within a few weeks.
Abstract: IN the course of a cy~ogenetic s tudy of an interspecific hybrid between Arena sativa gigantica and A. fatua (Philp, 1933) it was found that one/~,~ family 28-360, 28-360-30 (two family numbers are used since members of the family were grown in two years) consisted of 9 green and 61 albino seedlings. The albinos were pure white and had no green chloroplasts: they died within a few weeks (Plate XI, fig. 1). The data on the inheritance of albinism from the/~1 to the f 7 generation are given in Table I. The plants were allowed f,o set, naturally selfed
TL;DR: The eolour and pattern variMJon ha La, pldariobomb~ls The taxonomic groups of La,,p2da,riobombz~s .
Abstract: I. I¢~troduciiion . (l.) EeologicM disi)ribufJon of~!m cuckoos . (2) C/cogi:aphica,1 distribul~ion of host and cuckoo I I . Ecological and gcographlcM dist, ribuffion of Bombers la.pi&o'h~s rind Psithyn~s r~q)est.rls I I I . The colour and p~l~f~ern variaf~ion iu Psl lh,yrz~s ra,pestrls . IV. The eolour and pattern variMJon ha La, pldariobomb~ls The taxonomic groups of La,,p2da,riobombz~s . The Bombus lapidarius L. group . The Bombus lcerie';l, sis ~ . ~{or. group The Bombers slcheH P~ad. group The Bombers 'nlfofascia.t~s Smith group h r. [Discussion of the restflts VI. The ecological va.lue of film similarity l)e~;wema hosI; rind cuckoo VII. Conclusions VII I . Summary IX. Acknowledgments , lCeferences Explanation of Plate XV
TL;DR: According to the increased number of communications on the transplantation of neoplastic tissue, it seems advisable to review this material and attempt to summarise the results and determine the validity of the genetic theory of transplantation.
Abstract: Ow:rNc~ to the increased number of communications on the transplantation of neoplastic tissue, it seems advisable to review this material and attempt go summarise the results. Woglom(4o, ,n) has pu.blished two very exhaustive reviews on gum our work, the latter considering mainly work on immunity. A short summary of the genetic work was made by Little (m). In this article we wish to consider only the data resulting fl:om the inoculation of transplantable turnouts into indivi~tuats from inbred strains of animals and their hybrid generations. An effort will also be made to determine the validity of the genetic theory of transplantation (so).
TL;DR: A review of earlier cytological investigations of Musc showed that this hypothesis differs from the findings of Tischler and white who both record counts in multiples oi 4, but is consistent with those of D'Angremond(1,2).
Abstract: I~ a previous paper of this series (8) the suggestion was advanced ~hat the basic haploid chromosome number of the banana complex is 11. A review of earlier cytological investigations of Musc~, which need not be repeated here, showed that this hypothesis differs from the findings of Tischler(17) and white(S0) who both record counts in multiples oi 4, but is consistent with those of D'Angremond(1,2). Determination of the true nmnber is of ftmdamental importance hi its bearing on the bananabreeding programmes upon which we are both engaged[, and further evidence has been collected in an endeavour to lay a sotmd foundation for further applied researches. Cotmting of chromosomes in the species and varieties ha the Imperial College banana collection has been going on as opportunity offered for some years. During 1931-2 the second author was studying at the John Innes Horticultural Institution, h([erton, and took the opporttmity to make emmts on material available a~ Kew. The Kew material included some varieties in quarantine on their way to Trinidad, and some from which offshoots had already been sent, and that aeeotmts for a few duplications in the tables. A third set of figures has been collected in Jamaica during 1938. In the tables given below, the author responsible for the count is indicated in each case by an initial letter.
TL;DR: The form of any horse’s skull, either ancient or modern, is analysed as the manifestation of the characteristic equine skull pattern modified only by the absolute extent of growth.
Abstract: 1. Very extensive changes of form appear during foetal and post-natal development in the horse as quantitative functions of increase in total size. 2. These developmental changes of skull shape correspond precisely, if comparison be made between specimens of the same absolute magnitude, to those shape transformations arising during the evolution of the horse. 3. Since progressive pre-optic preponderance in the individual and in the race is algebraically the same function of total size, one may analyse the form of any horse’s skull, either ancient or modern, as the manifestation of the characteristic equine skull pattern modified only by the absolute extent of growth. The post-optic extension ofHyracotherium and the pre-optic preponderance ofEquus are believed to represent a single embryological pattern, of which diverse manifestations occur as a function of total size. 4. The appearance of an “orthogenetic” trend in the evolution of the equine skull is due to the attainment of successively greater adult sizes by the more recent genera. 5. One may interpret the progressive augmentation of racial size as a fortuitous occurrence, possibly aided by some natural selection, perhaps chemically determined by the mutation tendencies of certain size genes, but not inconsistent with the nature of probability.
TL;DR: The fragment chromatid does not divide in either meiotic division, although the “tertiary” split of diakinesis is very clearly seen in it at all stages.
Abstract: A chromatid fragment lacking an attachment has been found to occur in about 12 per cent. of the pollen mother cells in two plants ofTrillium erectum L.
TL;DR: The partially sex-linked genebb changes its place between theX- andY-chromosome in the male Drosophila melanogaster both by double crossing- over and inverted crossing-over.
Abstract: The partially sex-linked genebb changes its place between theX- andY-chromosome in the maleDrosophila melanogaster both by double crossing-over and inverted crossing-over. The frequency of these events is about 1 in 3000 in these experiments.
TL;DR: There is yet no evidence for the belief that specific mutations governing differences of form (in animals of equal stature) have played any significant part in the facial evolution of the equine skull.
TL;DR: The technique of breeding and the life history of Chorthippus parallelus are described and the action of 14 genes in C. parallelus, and the segregation of 10 of them, are described.
Abstract: 1. Several species of Acrididae provide valuable material for both cytological and genetical research.
TL;DR: The method proposed enlarges the possibilities of the investigation of the human karyotype, and enables the karyological investigation of any anthropogenetical or medical phenomena.
Abstract: 1. In the cultures of leucocytes of normal human blood under definite conditions of cultivation there appear periods of mass multiplication of cells in mitotic fashion. 2. The mass multiplication is observed in the polyblasts (macrophages) at the stage of their mutation into stable cells, and in the fibrocytes originating in haemocultures from polyblasts. 3. For obtaining the maximal quantity of mitoses the best time for fixation is the second 24 hours after the renewal of the medium, this latter being performed not later than the end of the fourth 24 hours after the planting of the culture. 4. After appropriate fixation, the figures of divisions may be used for karyological analysis. 5. The method proposed enlarges the possibilities of the investigation of the human karyotype, and enables us to undertake the karyological investigation of any anthropogenetical or medical phenomena.
TL;DR: Characters studied are flower colour and sex in both species, poor development of petals in the former and leaf blotch in the latter species, evidence is given that these have all a genetic basis, but the ratios are often disturbed by the occurrence of apomixis.
Abstract: This paper is a continuation of two previous papers on the genetics ofRanunculus bulbosus andR. acris. Characters studied are flower colour and sex in both species, poor development of petals in the former and leaf blotch in the latter species. Evidence is given that these have all a genetic basis, but the ratios are often disturbed by the occurrence of apomixis and, particularly inR. acris, semi-lethality and perhaps of lethality with certain gene combinations.
TL;DR: In this paper, Snapt, tilt and sepia are three genes on the left arm of the X-chromosome and on the right are eosin, an allelomorph of white, and cuprous, an allele of yellow.
Abstract: 1. Snapt, tilt and sepia are three genes on the left arm of theX-chromosome. On the right are eosin, an allelomorph of white, and cuprous, an allele of yellow.
TL;DR: The unusual frequency of crossing-over in females heterozygous for the new inversion as compared with that in other known inversions is regarded as being due to its great length, and perhaps to the position of the right break very near the spindle fibre, which seems to facilitate the formation of a crossed loop in pairing at meiosis.
Abstract: 1. An inversion of theX-chromosome ofDrosophila melanogaster is described which arose simultaneously with a rough-eye surface gene after X-ray treatment.