bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetically determined organ specific responses to the teratogenic action of 6-aminonicotinamide in the mouse
Authors: Goldstein Marc , Pinsky Merrille Feiner , Fraser F. C. 
Published: September 2009

1. A two-hour relative deficiency of nicotinamide, produced by maternal treatment with 6-aminonicotinamide, resulted in a maximum frequency of vertebral fusions following treatment on day 9·5 of gestation, and a maximum frequency of cleft palates following treatment on day 13·5.2. Both defects appeared with higher frequencies in the A/Jax than in the C57BL/6J inbred strain.3. The frequency of induced vertebral fusions in F1embryos from crosses between the strains was higher when the father was from the A/Jax strain than when the mother was—a patroclinous reciprocal cross difference.4. The frequency of induced cleft palate in F1embryos from crosses between the strains was higher when the mother was from the A/Jax strain than when the father was—a matroclinous reciprocal cross difference.5. Since the reciprocal cross differences in frequency of vertebral fusions and for cleft palates were in opposite directions, the hereditary factors influencing susceptibility to the teratogen appear to differ for the respective organ anlage. These differences appear to be, in part, cytoplasmic.6. The frequency of induced cleft palate in the offspring of backcrosses of (untreated) F1female hybrids to A/Jax males differed according to the cytoplasmic origin of the F1mothers. Thus the susceptibility of an embryo to the teratogen appears to be influenced by factors transmitted through the cytoplasm.
Formal and physiological genetics of ascospore colour in Aspergillus nidulans
Authors: Apirion D. 
Published: September 2009

By nitrous acid or UV treatment ascospore colour mutants of two kinds, blue and colourless, were obtained in Aspergillus nidulans (wild-type has red ascospores). Four blue mutants were located in linkage group II within 0·5 unit of one another (locus symbol: b11). Of the colourless mutants, four were located in linkage group I within one unit of one another (locus symbol: c16), and one in linkage group IV (locus symbol: c14). In diploids the mutants were recessive. Colourless was epistatic to blue.In crosses these characters behaved as ‘non-autonomous’ both in the ascospores and in the asci; all the ascospores of the asci in one perithecium as well as the perithecium wall were of the same colour. In crosses between strains with blue perithecia and strains with colourless perithecia, red, blue and colourless perithecia were found; each type included both crossed and selfed perithecia. Red selfed perithecia were of either parental genotype but blue or colourless selfed perithecia always had the corresponding genotype.The phenotype of the perithecium (perithecial wall and ascospores) is considered to be determined by the homo- or heterokaryotic constitution of the protoperi-thecium which gave origin to it.
Genetic stability of the Cornell randombred control population of White Leghorns
Authors: King Steven C. , Van Vleck L. Dale , Doolittle Donald P. 
Published: September 2009

Six years of data collected from two shifts of Cornell random bred control matings each year are analysed. Approximately 900 progeny were tested per year from 50 sires mated to 250 dams.Means for the important economic traits are presented by years and regressions for nine such traits, together with their standard deviations, are shown. The only significant regressions are those for both egg production and specific gravity score in shift II. An abnormally low egg production the first year for this shift is considered responsible for this result and the reality of the regression is discounted.Genetic variances are presented by trait and year. Year to year variability is evident, but no trends are indicated.Estimates of heritability and genetic correlations between traits are presented. These estimates are considered to be quite reliable and will be useful as estimates of genetic parameters when this population is used in selection experiments. Estimates of heritability from the sire components of variance were as follows: 8-week body-weight, 0·29; 32-week body-weight, 0·48; 55-week body-weight, 0·44; age at maturity, 0·09; egg production to 500 days, 0·07; 32-week egg-weight, 0·51; 55-week egg-weight, 0·53; USDA albumen score, 0·29; blood spot score, 0·13; and specific gravity score, 0·34.Important maternal effects were found for 8, 32 and 55-week body-weight, sexual maturity and egg production. Selection programmes should take into consideration the fact that maternal effects accounted for 13% of the total variation in egg production. Genetic correlations utilizing combined sire and dam components revealed no serious antagonisms between egg production and other economic traits. However, this conclusion must be considered in the light of what influence maternal effects may have, since correlations computed from sire and dam components separately may have opposite signs and be important.The many negative estimates of interaction components (SH, genetic by environment) and (I, sire by dam) indicate that these elements of the model contributed little to the variation of the traits studied.
Genetical control of the anaphylactoid reaction in rats
Authors: Harris J. M. , Kalmus H. , West G. B. 
Published: September 2009

1. A recessive autosomal gene, dx, preventing the anaphylactoid reaction has been discovered in a stock of Wistar albino rats from the Agricultural Research Council, Compton.2. Segregation occurred in the F2 generation derived from crossing pure-bred reactor rats and pure-bred non-reactor rats.3. Non-reactivity was outbred into non-albino stocks and was shown to segregate independently of the albino gene c and not to be closely linked to the colour genes, P and A.4. The mutation from Dx to dx may have arisen a few years ago in one of the Wistar colonies before it was split into sub-lines.5. The dx gene is fixed in several brother-sister mated sub-lines and appears to be in equilibrium with Dx in some less inbred closed-populations.
Selection using assortative mating inDrosophila melanogaster
Authors: McBride Glenorchy , Robertson Alan 
Published: September 2009

The effectiveness of the assortative mating of selected individuals in increasing selection response was tested, using abdominal chaeta score inDrosophila melanogaster. Three paired comparisons were made. In two sets of lines with 10 matings per line, individual score was used for selection and as the basis for the assortative mating. In the third set with 20 matings per line an index of individual and family score, designed to maximize rate of response, was used.The intensity of selection was one in ten in all lines. Flies were raised in vials and individual pedigrees were kept.In all comparisons, assortative mating gave a greater selection response, this being partly due to a greater realized heritability and partly to a greater selection differential. The effect of the assortative mating was largest in the index selected lines. With random mating, the effectiveness of the index selection itself when compared to individual selection was in accordance with theory.In two comparisons, assortative mating increased the rate of inbreeding. The highest rate of inbreeding was observed with index selection and assortative mating, even though there were here twice as many matings as in the individually selected lines.In the individual selection lines, the effective population size was 7·4 pairs of parents, compared to the actual value of 10 and in the index lines 7·0 compared to 20. In the former, only one-half of the matings in the initial generations made any permanent contributions to the line and in the index lines only one-third. Within generations and lines, there was a significant positive correlation between the mean score of a family and its inbreeding coefficient.It is suggested that assortative mating is a method of increasing selection response in some situations. Its particular characteristic is that it becomes more powerful when the heritability is high whereas all of the other environmental aids to individual selection are more effective when the heritability is low.
On the maximum avoidance of inbreeding
Authors: Kimura Motoo , Crow James F. 
Published: September 2009

Mating systems in which the least related individuals are mated have been designated by Wright as having maximum avoidance of inbreeding. For such systems the initial rate of decrease in heterozygosity is minimum. However, some other systems have a lower rate of decrease in later generations.Circular mating, in which each individual is mated with the one to his right and to his left, leads to an asymptotic rate of decrease in heterozygosity of 1– λ ˜ π2/(2N+ 4)2compared with 1/4Nfor maximum avoidance systems. Circular pair mating, in which for example each male progeny is moved one cage to the right, leads to 1– λ ~ π2/(N+ 12)2. Other similar systems are discussed.For minimum gene frequency drift, a mating system should have a constant number of progeny per parent and the population should be broken up as rapidly as possible into the maximum number of lines. The gene frequency variance at generationTwithin a line iswhereNis the number in the line andHtis the proportion of heterozygotes in generationt. Although the three mating systems, circular, circular pair, and maximum avoidance (and many others) have the same amount of random drift ultimately, at any generation circular mating has the smallest drift variance,VT, and circular pair next smallest.
The interpretation of data from transduction experiments
Authors: Dawson G. W. P. 
Published: September 2009

1. Data from transduction experiments withSalmonella typhimuriumcan be interpreted in terms of frequencies of recombination by accepting the arguments of Ozeki that all transduced fragments that include a particular locus are equal in length.2. From a two-point transduction the ratio of the two classes of transductants is not a measure of the ratio of the frequencies of recombination in the two relevant regions but only provides maximum and minimum values for this ratio.3. From three-point transductions the frequencies of recombination in the regions between the markers, and between the terminal markers and the ends of the fragment, can be estimated.4. The difficulties of interpreting data from experiments in which a single factor is transduced are briefly discussed.
The effect of inbreeding on temperature acclimatization inDrosophila subobscura
Authors: Bowler K. , Hollingsworth M. J. 
Published: September 2009

1. Rates of gain and loss of acclimatization to temperature of males from two inbred lines and the hybrids between them were measured by recording their survival times in dry air at a lethal temperature (34°C).2. All hybrid males lost acclimatization to temperature more quickly than did inbred males. B/K males gained acclimatization to temperature more quickly than any other group, but the K inbred males gained acclimatization more quickly than did either the K/B males or the B males. In all cases acclimatization is gained more quickly than it is lost.3. The extent of acclimatization to temperature, as measured by the difference in survival times of 15°C. and 25°C. acclimatized flies in a range of lethal temperatures, was not found to be different in inbreds and hybrids.4. The results suggest that hybrids can produce the enzymes necessary for acclimatization to temperature more rapidly than inbreds and confirms the hypothesis that hybrids are biochemically more versatile than inbreds.5. The difference between the rates of gain and loss of acclimatization to temperature suggests that the processes involved in the enzyme changes are temperature dependent.6. The absence of a difference in the extent of acclimatization to temperature indicates that both inbred and hybridD. subobscuraare capable of producing those enzymes necessary for temperature acclimatization.7. The high values of the temperature coefficients for heat death indicate that this process involves protein (enzyme) denaturation.8. An ageing effect was observed in inbred flies.
A developmental-genetic study on panicle characters in rice, Oryza sativa L.
Authors: Sakai Kan-Ichi , Shimamoto Yoshiya 
Published: September 2009

By comparing genetic correlations between an X-rayed and a control population of rice, parameters for the strength of pleiotropic effects of quantitative genes have been estimated. It is evident that the gene-set which is responsible for main rachis formation and is therefore of primary importance for panicle formation, is pleiotropically controlling the development of rachillas and basal internode. It is found that the pleiotropic control over the development of higher rachillas is very powerful but less strong over the lower ones and basal internode.Developmental relationships among these characters have also been investigated by measuring the genetic correlations between their developmental instabilities. The basis of our inference is the hypothesis that if two characters which are found to be pleiotropically controlled by the same set of genes take their own developmental paths from a very early stage, they will show only slight correlation between their developmental instabilities. If, on the contrary, they are taking the same developmental path and their differentiation sets in late, the correlation coefficient will be high.
The production of recessive lethals by calf-thymus DNA in Drosophila
Authors: Mathew C. 
Published: September 2009

Calf-thymus DNA was mixed with the larval food of Drosophila melanogaster and complete and mosaic lethals were scored in both the X- and 2nd chromosomes. There was a decided mutagenic effect on the 2nd chromosome in both sexes. No complete sex-linked lethals were produced in males, but the production of a moderate number of complete lethals in females and of mosaic lethals in both sexes suggests that, in the absence of germinal selection, the X-chromosome is not completely refractory to the treatment.The extension of the 2nd chromosome test to later generations showed that mosaics often gave rise to further mosaic progeny. Tests for allelism showed that lethals in the same mosaic line formed series of overlapping deficiencies, indicating that the primary effect in these cases was a transmitted instability of a narrow chromosomal region. Cases in which several mosaics arose out of one mosaic parent show that this instability must have replicated as instability.
Transferrin and post-albumin polymorphism in East African cattle
Authors: Ashton G. C. , Lampkin G. H. 
Published: September 2009

The serum transferrin and post-albumin phenotype distributions of 228 Sahiwal, 138 Nganda, 265 Boran, 114 Tanganyika Shorthorned Zebu, 72 Teso and 267 Ankole cattle from East Africa were determined.Five transferrin alleles, TfA, TfB, TfD, TfE, and TfF were present in all the breeds examined, and a sixth allele, TfG, was present in three of the Borans. TfE and TfF were the most frequent alleles, except in the Nganda cattle where TfA was the most frequent. TfB had a frequency of less than 0·1 in each breed. Two post-albumin alleles, PaF and Pas, were present in each breed. In each breed except Sahiwal PaF was two to three times more frequent than Pas. In the Sahiwal PaF and Pas had about the same frequency. It was concluded that both transferrin and post-albumin gene frequencies in East African cattle differ significantly from the corresponding frequencies in European cattle.There was no evidence of an excess of heterozygotes in the post-albumin system other than that expected from the use of relatively small numbers of bulls in these herds. However, allowing for the same factor in the transferrin system, there appeared to be an excess of transferrin heterozygotes in the cattle populations sampled although the extent of this excess could not be calculated accurately.
The two-way selection of mutants and revertants in respect of acetate utilization and resistance to fluoro-acetate in Aspergillus nidulans
Authors: Apirion David 
Published: September 2009

An extension of two-way selection (i.e. selection of mutant from wild-type and vice versa within the same locus and with the same efficiency) to four different mutational or segregational situations was made possible by using acetate, fluoro-acetate and other substances related to their metabolism.Two types of mutants resistant to fluoro-acetate were selected, the first of which (designated fac) cannot grow on acetate as the sole carbon source, while the second (designated fan) can.Commencing with either a fac or a fan strain a double fac fan strain may be isolated, which is much more resistant to fluoro-acetate than either single mutant strain. Such double mutant strains may also be obtained by crossing a fac to a fan strain. Various characteristics of growth response of these strains on various media were observed.fac mutants are recessive and map in three meiotically unlinked loci, one in linkage group V and two in linkage group VIII.fan mutants are recessive and map in five loci, one in each of the linkage groups V, VII and VIII, and two linked in linkage group VI.Most fac mutants isolated did not revert and this failure is considered genuine. Of the revertants tested, most resulted from extra-cistron suppressors, while revertants of two fac mutants resulted from very closely linked or intra-cistron suppressors.It is argued that the findings indicate the existence of two pathways for acetate utilization in Aspergillus nidulans, a major and a minor; fac mutants are blocked in the major pathway, fan mutants in the minor pathway.
The effects of mating systems and selection on pupa weight inTribolium
Authors: Wilson S. P. , Kyle W. H. , Bell A. E. 
Published: September 2009

An experimental evaluation of the effect of mating systems and selection upon an additive trait thought to be highly heritable was made. There were two similar replications. Each consisted of a mass selected and randomly selected group, with five mating systems within each group.Realized heritabilities in the mass selected lines were considerably less than was expected prior to the initiation of the experiment, and averaged approximately fourteen percentage points less than heritability estimated from the zero generation. This in turn resulted in smaller correlations between the genotypes of mates than had been previously expected in the assortatively and disassortatively mated lines.The average response of the mass selected, assortatively mated lines was slightly more than the mass selected, randomly mated lines, though not statistically significant. This result seems to conform to theoretical expectations.In the mass selected lines, estimates of phenotypic and genetic variance declined regardless of mating systems. There was a tendency for phenotypic variances to decrease in the randomly selected lines, but this was not the case for estimates of genetic variance.As an aid to selection, it seems that assortative mating would be of little value with traits of low or intermediate heritability but might be useful if the trait is highly heritable.
Genetic analysis of liver catalase activity in two substrains of C57BL mice
Authors: Heston W. E. , Hoffman Harold A. , Rechcigl Miloslav 
Published: September 2009

The level of liver catalase activity in substrain C57BL/6 mice is only approximately half that in substrain C57BL/He. That this difference was due to a single major gene with low level of activity dominant to high was indicated by analysis of the F1, F2, and backcross hybrids and confirmed by progeny tests of first back-cross male segregants. The gene symbolCeis suggested.The absence of any difference between reciprocal hybrids indicated no extra-chromosomal maternal influence.There was no evidence that this gene controlling liver catalase had any influence on the level of kidney catalase activity for this did not vary between the two parent substrains or the hybrid groups.Males consistently had higher liver and kidney catalase activity than females. The difference was more pronounced in respect to kidney catalase, males having about twice the activity found in females.
The replication of metagons and mu particles from Paramecium in another cell—Didinium
Authors: Gibson Ian 
Published: September 2009

1. The maintenance of mu particles and metagons from Paramecium aurelia (stock 540, syngen 1) in another ciliate protozoan Didinium nasutum has been shown to occur.2. It has been shown that mu particles could not be supported in Didinium without metagons. One particular strain of Didinium has, however, never been able to support mu even when metagons were present.3. The continued production of metagons in Didinium was shown to take place even when the Didinium was fed on killer Paramecium of genotype m1m1m2m2.4. After destruction of the metagons in Didinium by ribonuclease there was no subsequent reappearance of metagon activity.5. Metagons and mu particles were eliminated from Didinium during encystment.6. It is considered that the increase of metagons in Didinium is due to self-replication. In Paramecium the metagons replicate only slowly or not at all.7. It is concluded that the metagon is a gene product in Paramecium which takes on at least one other property, replication, when introduced into Didinium.
Some observations on asymmetrical correlated responses to selection
Authors: Bohren B. B. , Hill W. G. , Robertson A. 
Published: September 2009

The pattern of changes of the genetic covariance between two characters on selection was examined in an effort to explain the asymmetry of correlated responses in two traits, or of the same trait in two environments, frequently observed in experimental results.The algebraic conclusions were further examined by model selection experiments using a computer. The computer was programmed to calculate the change in gene frequency from generation to generation and to calculate from it the expected changes in genetic variances and covariance as selection proceeded. This procedure was carried out with several models of gene effects and gene frequencies.Asymmetry of the genetic covariance, and consequently of the correlated responses, resulted when the relative change in gene frequency at the loci contributing positively and negatively to the covariance depended on the trait selected. The conditions necessary for the development of asymmetry were examined and the results suggest that any symmetry found in an experiment is perhaps more surprising than asymmetry. Probably the most frequent contribution to asymmetry in practice will be from loci contributing negatively to the covariance and having frequencies other than 0·5.Accurate prediction of correlated response over many generations is therefore not possible without prior knowledge of the composition of the genetic covariance, as well as its magnitude. The validity of existing theory for the prediction of correlated responses is likely to be much poorer than for the prediction of direct responses. Predictions would then have to be based on the genetic parameters estimated in each generation.