bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of inbreeding on ovulation rate and foetal mortality in mice
Authors: Falconer D. S. , Roberts R. C. 
Published: September 2009

Dissections were made of 16-day-pregnant female mice with the object of discovering the developmental stage at which litter size is reduced by inbreeding. Counts were made of the numbers of corpora lutea, implantation sites, and live embryos, and comparisons were made between females with inbreeding coefficients of 50–60% and non-inbred females. Except in one group the embryos were all non-inbred, so that the comparisons showed the effect of inbreeding in the mother of the litter. No influence of inbreeding in the male parent was found.The only difference found between inbred and non-inbred females was in the number of eggs or embryos lost before implantation. The greater pre-implantation loss in inbred females was enough to account for the smaller number of young born alive in their litters.There was no difference between the inbred and non-inbred females in the ovulation rate, measured by the number of corpora lutea, or in the post-implantation mortality of the embryos.There was a positive correlation between ovulation rate and weight at 6 weeks. For reasons explained in the Discussion, the inbred females did not differ in weight from the non-inbred females. If, under other conditions, the weight declined on inbreeding, the ovulation rate would be expected to decline also.
Genetical studies on the skeleton of the mouse XXVI. Pintail
Authors: Berry R. J. 
Published: September 2009

1. The gene for Pintail (symbol Pt) shows no dominance. Heterozygotes are viable and fertile; many homozygotes die early in life, but the survivors appear to breed normally. Pt reinforces the effects of Sd and T on the tail; there is no evidence for interaction between Pt and + /vt.2. The gene produces a shortening of the tail, but the most marked effect on the adult is in the great reduction of the nucleus pulposus of the intervertebral discs, which may lead to tail kinks in some animals.3. Pintail embryos can be recognized from the eleventh day stage of development onwards by the possession of a much smaller notochord than normal. This reduced notochord is the result of a reduced rate of cell division which first manifests itself in 10-day embryos. Perhaps this reduced rate is the result of altered relations of the notochord with tail-gut and neural tube in 10-day embryos.
The cytology of Aspergillus nidulans
Authors: Elliott Charles G. 
Published: September 2009

In haploid strains of Aspergillus nidulans, asci arise from croziers. The two nuclei of the young ascus (the penultimate cell of the crozier) fuse, and the zygote nucleus immediately undergoes meiosis. At diakinesis and first metaphase eight bivalents are seen: three large (one, Chromosome 2, with a satellite), two medium sized (Chromosomes 4 and 5), two small (Chromosomes 6 and 7) and one very small (Chromosome 8). The perithecia of haploid strains are packed with asci and have very few sterile hyphae.Diploid strains (heterozygotes made by Roper's technique) are very different from haploids in that the perithecia contain many sterile hyphae with little cytoplasm and coiled hyphae with dense cytoplasm made up mainly of uninucleate cells, and there are few asci in a perithecium. Croziers are absent: some of the cells of the coiled hyphae become asci. At diakinesis and first metaphase, the same chromosome configurations are seen as in a cross between the haploid strains from which the diploid was synthesized; the chromosomes are bivalents. The young ascus thus has a single (diploid) nucleus which undergoes meiosis, and asci develop apogamously. No evidence of nuclear fusion in the young ascus and of a tetraploid meiosis was obtained. Cultures from ascopores isolated by micro-manipulation from perithecia of diploids were all haploid. Meiosis appears to proceed normally to first metaphase, but typical later stages, and asci with spores, are rarely seen. First anaphase frequently fails to occur, and the chromosomes clump together.In the strain ad2 y, obtained from a normal strain by X-irradiation, nine bivalents are present, one a very small fragment. In crosses between ad2 y and a normal strain, and in a diploid made from them, the fragment pairs with Chromosome 6. Asci in the cross between ad2 y and a normal haploid are highly irregular, often with less than the usual eight spores.
Structural polymorphism in Drosophila subobscura Coll. from various localities in Scotland
Authors: Knight G. R. 
Published: September 2009

1. Gunson's salivary chromosome preparations of Drosophila subobscura from widely separated sites in Scotland have been re-examined and inversions recorded according to the Mainx nomenclature.2. Sixty-four diploid sets only were available. Of these, thirty-seven sets were found to be structurally homozygous on all chromosomes.3. From Drumnadrochit in the north-central area of Scotland, the inversion found on the E-chromosome, so far as is known, has not previously been described. Its break-points have been noted, and the inversion is named E14.4. A strain of D. subobscura from the small western island of Iona was the only one found to be completely homozygous in the five long arms of the chromosome set.5. Samples of D. subobscura from two closely related localities in Midlothian, Scotland, also have been examined. Results are based on the analysis of 120 haploid sets in hybrids between the local race and the standard Küsnacht stock.6. A slight difference in type and frequency of inversions has been noted between the two populations. The inversion E1+2 was recorded from Dalkeith, but was absent at Heriot, while U1, present at Heriot, was replaced by UST at Dalkeith.7. The A-chromosome was structurally homozygous throughout.8. Scottish samples of D. subobscura are characterized by their qualitative simplicity of polymorphism, the variety of inversion types being small. Chromosome orders analysed have been compared with those occurring in Western Europe and Israel.
Asymmetrical response to selection for rate of development inDrosophila subobscura
Authors: Clarke Jean M. , Smith J. Maynard , Sondhi K. C. 
Published: September 2009

Starting from a geographically hybrid foundation population ofDrosophila subobscura, selection for fast and for slow development has been practised without inbreeding on a diet with an unusually high level of protein. Realized heritabilities in the fast and slow lines were + 0·063 ± 0·029 and + 0·186 ± 0·031 respectively. A half-sib analysis of the foundation population and full-sib analyses of the first two and the last two selected generations were carried out. Hybrids between the two lines were approximately intermediate between their parents.Two types of genetic explanation of the asymmetrical response are discussed. The first assumes directional dominance of alleles for fast development. Such an assumption can explain the asymmetrical response, but runs into difficulties in explaining the nature of the genetic variance in the selected populations and the intermediacy of the hybrids between the two lines.A second assumption, which appears to fit the facts better, is that there exists a ‘developmental barrier’ preventing development at a rate appreciably faster than that of the foundation population. In physiological terms this implies that more rapid development requires a more profound modification of the population than could be achieved by a few generations of selection. In genetic terms, it implies epistatic interactions between genes at different loci: gene substitutions at a given locus which increase development rate on a genetic background causing slow development have little or no effect on a genetic background causing rapid development. In other words, there is a law of diminishing returns as more and more alleles for fast development are accumulated in the genotype. It is suggested that genetic situations of this kind may be common in populations which have been exposed to directional selection for a long time in reasonably large populations, either in nature or in domestication.
Linkage relations and some pleiotropic effects of the dreher mutant of the house mouse
Authors: Lyon Mary F. 
Published: September 2009

Linkage studies with the mutant dreher (dr) of the mouse (Mus musculus L.) have shown that it lies in linkage group XIII and that the order of loci is dr–Dh–ln. The recombination between dr and Dh was 22·3 ± 4·1%.Two previously undescribed pleiotropic effects of the dr gene were observed. The first was a tendency to white spotting in the belt region, and the second an interaction with brachyury (T) such that drdr T+ animals had shorter tails on the average than + dr T +.
Effects of dominance and size of population on response to mass selection
Authors: Kojima Ken-Ichi 
Published: September 2009

A theory of mass selection in a small population was developed, and the mean change in gene frequencies, the variance of gene frequency changes and the expected gain in the mean phenotypic value of an offspring population were formulated in terms of a generalized selection differential and the additive and dominance effects of genes.The magnitude of the variance of changes in gene frequency was compared with the magnitude of the variance expected from the genetic random drift in a population with the same gene frequency and of the same size in absence of selection. The former was found to be usually smaller than the latter when the gene frequency ranged from intermediate to high and when selection was directed for a high performance.The usual prediction equation for gain from selection in an infinite population was compared with the expected gain formula derived for a small population. The size of the population did not cause a serious difference between the two expected gains when there was no dominance effect of genes. Dominance alone could cause the usual prediction to be slightly more biased. The joint effects of the finite size of population and dominance gene action could amount to a considerable bias in the usual prediction equation. Such a bias can be, in the main, accounted for by the inbreeding depression.
The ecological genetics of growth inDrosophila4. The influence of larval nutrition on the manifestation of dominance
Authors: Robertson Forbes W. 
Published: September 2009

(1) Two lines have been selected for small wing cell size from the cage Pacific population. Body size was reduced by about 10% and 15% in the two lines which did not regress when selection was relaxed.(2) The effects of crossing each line to the unselected population has been determined in a number of repeated tests on the live yeast medium and also on various sub-optimal synthetic media.(3) The size of the F1, relative to the size of the parents, is greatly influenced by the composition of the larval diet. The F1may coincide with the mid-parent value but generally significantly exceeds it and is often the same size as the unselected parent population.(4) In crosses to an unselected population on alternative media the F1was either the same size as the unselected population or exceeded it.(5) Crosses between the selected lines produced an F1which exceeded the larger parent but remained well below the level of the unselected population.(6) To test for interaction between genes at different loci, chromosomes from the unselected population were substituted in the genetic background of each of the selected lines to provide an array of genotypes in which one, two or three pairs of major chromosomes had homologues derived from different strains. Leastsquares analysis indicated differences between the lines in the distribution of effects among the chromosomes together with the presence of interaction between chromosomes and this was greater for the substitutions in the line which showed the greater consistency of recessive behaviour in crosses to the unselected population.(7) At the end of the selection experiment two lines were selected for large body size from the F2of the cross between the two selected lines. Both responded to selection for three to four generations and then fluctuated at a level slightly below that of the unselected population.(8) The physiological changes which involve correlated changes in body and cell size differ from those which result from selection for smaller body size, at least in the early stages of such selection, and are associated with differences in genetic behaviour. The apparently recessive property, which involves extensive non-allelic interaction, is progressively established during the course of selection. Apparently selection for smaller cell size is particularly effective in disturbing the normal homeostasis of growth and is accompanied by relatively greater loss of heterozygosis than is likely with equivalent reduction in size due to selection for smaller body as opposed to cell size.
Two linkage groups inCoprinus lagopus
Authors: Day P. R. , Anderson G. E. 
Published: September 2009

Sixty-six independently produced markers have been tested for linkage with theAandBmating-type factors. Six loci linked withAand three linked withBwere found. Maps of the two linkage groups which include the centromeres were constructed.Non-identical alleles at two loci,paba-1 andchol-1, were found and crosses between different mutants were used to map the positions of the mutant sites within each locus.
The ecological genetics of growth inDrosophilaV. Gene-environment interaction and inbreeding
Authors: Prabhu S. S. , Robertson F. W. 
Published: September 2009

1. The growth of a number of inbred lines from the Pacific cage population have been compared under different conditions of temperature and nutrition. Body size and duration of the larval period were taken as measures of performance. Sub-optimal diets were provided by growing larvae on chemically defined synthetic media.2. Gene-environment interaction is widespread and often very great. The phenotypic effects of inbreeding on body size, even on a live yeast medium, may be greatly influenced by temperature. In one set of comparisons, inbred lines averaged 20% smaller at 25° C. but only 3% smaller at 18° C.3. Sub-optimal diets of different chemical composition, which lead to about the same average decline in body size, may differ greatly in the level of heterogeneity of response among the same set of inbred lines. Thus much greater heterogeneity was found on diets deficient in RNA than on diets with low protein levels. Such information is a useful guide to further study of gene-environment interaction in the outbred population.4. Diets which lead to a decline in body size of flies of the foundation population do not necessarily cause greater proportional decline on the part of inbred lines. Individual lines have been encountered in which body size is quite unaffected by changes in diet which reduce the size of the outbred flies by 25% or more.5. A series of crosses between lines from the same foundation population showed a striking level of homeostasis. The average body size and development time of the F1's was close to that of the population of flies on the favourable and two alternative sub-optimal diets. Also, compared with the parent lines, there was little evidence of gene-environment interaction among the crosses.
Linear heritability estimates
Authors: Abplanalp Hans 
Published: September 2009

A method for obtaining linear estimates of heritability and genetic correlation is given. It is based, essentially, on selecting, from a pedigreed population, prospective parents for which estimates of average genotype and phenotype values are obtained; a regression of genotype on phenotype value is then determined from a straight line fitted through points representing the population mean genotype and phenotype on one hand and the mean genotype and phenotype of selected parents on the other.The method permits an evaluation of asymmetry in response for a trait selected in both directions, as well as asymmetry in correlated response to selection of two different traits, with data from a single pedigreed population.
Erythrocytic antigenic differences between individuals of the deer mouse,Peromyscus maniculatus
Authors: Rasmussen David I. 
Published: September 2009

1. Antigenic polymorphism between individuals of the subspeciesPeromyscus maniculatus gracilisis demonstrated.2. Absorption analysis of heteroimmune rabbit sera using erythrocytes of individual mice revealed two unitary complete (saline) agglutinins, designated as anti-A and anti-B, reactive to erythrocytic antigens in this species.Isoimmunization apparently demonstrated these same antigenic differences.3. The two antigenic characters (A and B) defined by the agglutinins are inherited as if simply related to allelic factors designated PmAand PmBrespectively.4. These two antigens are found in representatives of both the subspeciesP. m. gracilisandP. m. bairdii, and, in addition, the A antigen was observed in a laboratory stock ofP. polionotus. Tested individuals of the speciesP. leucopusandMus musculus, however, possessed neither antigen, and samples of human blood also lacked both antigens.5. Species-specific agglutinins distinguishing individuals of the speciesP. leucopusandP. maniculatus, and population-specific agglutinins which distinguished between individuals of the subspeciesP. m. bairdiiandP. m. gracilis, have been observed.
Regular responses to selection 2. Recombination and accelerated response
Authors: Thoday J. M. , Gibson J. B. , Spickett S. G. 
Published: September 2009

1. It has been shown that the lines dp 1, dp 2, vg 4 and vg 6 of Thoday & Boam (1961) each have two high sternopleural chaeta number genes or ‘effective factors’ between h and eyg in chromosome III. Their line dp 6 does not contain these two genes.2. Lines derived from ancestors of dp 2 and vg 4 before the latter produced their accelerated responses have third chromosomes affecting chaeta number as if they had only one or other of these genes.3. Of the three stocks from which all the lines derived, one, Inbred Oregon, lacks these genes. The second, vg/vg, has third chromosomes similar in effect to Oregon. The third, dp/dp, was heterogeneous, having a class of third chromosomes similar in effect to those of Oregon and a class similar to those having one high gene.4. It is suggested that the history of the accelerated response in dp 1, dp 2 and vg 4 was as follows. Initially most of these third chromosomes were − − at the two loci, but a minority (derived from the dp/dp stock) were + − and − + (where + indicates the allele increasing chaeta number. Selection would reduce the frequency of − −, and hence increase the proportion of + −/− + heterozygotes and the probability of recombination to produce + +. Origin and multiplication of + + would account for the accelerated response.
Immunogenetic analysis of proteins ofParameciumV. Detection of specific determinants in strains lacking a surface antigen
Authors: Finger Irving , Heller Carol 
Published: September 2009

Several stocks ofParamecium aureliathat had never expressed an E serotype were examined for E-reacting material. The regular presence of the cross-reacting antigen G in these stocks ruled out the use of hapten inhibition and other standard immunological techniques. Consequently, a genetic approach was attempted in which hybrids of the E-deficient strains and non-E stocks were bred, and antigen isolated and tested for the existence of molecules with a specificity differing from that of the E-containing parent.Gel diffusion analysis suggested that E antigen from a hybrid indeed could differ from the ‘normal’ E. One of these hybrid clones which behaved as though its E antigen may have possessed a determinant contributed by the E-deficient strain was used as an immunizing antigen. The antibodies elicited possessed specificity unique for the hybrid. Thus the possession of E-like determinants by E-deficient stocks was confirmed.
Immunogenetic analysis of proteins ofParameciumVI. Additional evidence for the expression of several loci in animals of a single antigenic type
Authors: Seed J. Richard , Shafer Stephen , Finger Irving , Heller Carol 
Published: September 2009

A paramecium generally bears on its surface but one immobilization antigen from among the many it may have the potentiality for expressing. By assaying soluble extracts of whole cells, it had been demonstrated previously that animals of the E serotype may possess the cross-reacting G antigen. Now the existence of these secondary antigens—immobilization antigens undetected byin vivotests—has been extended to include unrelated antigens, e.g. G antigen in animals of C serotype.The amount of these cryptic immobilization antigens varies from stock to stock; also within a stock cultures harvested at different times may have quite different quantities.The secondary and primary G antigens appear to be indistinguishable by the criteria of antigenic specificities, immunoelectrophoretic mobilities sedimentation rates and ammonium sulfate solubilities. As to their distribution within the cell, both secondary and primary antigens are located primarily on or within the cilia.
The genetics and morphology of two ‘luxoid’ mutants in the house mouse
Authors: Searle A. G. 
Published: September 2009

1. Dominant hemimelia (Dh) and postaxial hemimelia (px) both belong to the luxoid group of mouse mutants, tending to cause luxation of limb-bones associated with hemimelia and polydactyly or oligodactyly.2. Dh is about 4·8 units from leaden in linkage group XIII, while px is about 2·9 units from the microphthalmia locus in linkage group XI.3. The nature and range of skeletal anomalies found in Dh heterozygotes closely mimic those found in luxate heterozygotes and homozygotes. As in luxate, only the preaxial side of the hind-limb is affected, with (i) polydactyly or oligodactyly (sometimes also syndactyly), (ii) tibial hemimelia, (iii) reduction and fragmentation of the femur, (iv) reduction of the pubis. The more proximal the anomaly the less frequently does it occur; about 4% of Dh/ + mice show no limb anomaly. The defects in Dh homozygotes are similar but usually more extreme, with severe oligodactyly, loss of tibia, fragmentation of femur and reduction of pubis.4. All mice carrying Dh lack the spleen. Stomach size is reduced slightly in Dh/ + and greatly in Dh/Dh mice. In Dh/ + mice, the left kidney is either flattened antero-ventrally or (less frequently) hydropic; the right seems normal. Dh/Dh mice nearly always have severe hydronephrosis, as well as posterior visceral defects similar to those of the ‘uro-recto-caudal syndrome’. They usually die before weaning, but a few survive to maturity and a female has even bred.5. Preliminary developmental studies show that Dh/Dh skeletal defects can be traced back to the precartilaginous stage.6. When homozygous, px affects the postaxial side of the fore-limb and sometimes of the hind-limb also; a large ‘foramen infraspinatum’ is always present in the scapula. There may also be (i) oligodactyly and occasional syndactyly, (ii) ulnar hemimelia, (iii) distal reduction and distortion of the femur. Fore-limbs tend to be more severely affected on the right, but hind-limbs on the left. Extra sesamoid bones occur on the extensor side of digits in all four feet and are associated with extra tendons.7. Both sexes are sterile and show anomalies of the paramesonephric (Müllerian) ducts. In the female, the vagina is wholly or partly double and the uterine tubes uncoiled, with an abnormal relationship to the ovary. In the male the paramesonephric duct persists in the adult, while the vas deferens runs into the distal end of the vesicular gland instead of into the urethra. The epidermis of manus and pes shows abnormal dark papillae on the extensor side.8. The mean number of presacral vertebrae is reduced by 0·8 in Dh/ + and 1·6 in Dh/Dh mice. It is also reduced in high-grade postaxial hemimelics.9. The relationships of these two genes to other luxoid mutants are discussed.