bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic evidence of an unorthodox chromosomal system in the lac insectKerria lacca(Kerr)
Authors: Chauhan N. S. 
Published: September 2009

SUMMARYThe colour difference (crimson and yellow) inKerria lacca(Kerr) was used to test the ‘Lecanoid’ system of chromosome behaviour proposed on cytological evidence. The colour strains bred true for colour. Reciprocal matings between the colour strains produced only crimson sons and daughters, confirming that the colour difference is not sex-linked and that the male is somatically a diploid. The phenotypes of the F2and the backcross generations differed according to the heterozygosity and the direction of cross of the F1parents, since heterozygous females produced two kinds of gamete but heterozygous males produced only the maternal kind. Thus, while elimination of the paternal gene and hence chromosome was confirmed during the formation of male sex-cells, demonstration of somatic diploidy of the male is not compatible with a ‘Lecanoid’ system inK. lacca. Instead, the available cytogenetic evidence is suggestive of a chromosome system with heterochromatization and elimination of the paternal chromosome-set confined to the male germ line.
Chromosomal analysis of cultured skin fibroblasts from patients with infectious mononucleosis
Authors: Monteleone Patricia L. , Cherry James D. , Monteleone James A. 
Published: September 2009

SUMMARYIn the present study, skin fibroblasts and leukocyte cultures from patients with acute infectious mononucleosis were examined to determine if any in vitro marker chromosomes could be detected. No alterations in chromosomes could be found in fibroblasts either from the region of the typical rash or from other areas of skin. This would tend to suggest but does not necessarily prove that this tissue was not extensively involved in the disease process.
Two mutations giving low-level streptomycin resistance inEscherichia coliK12
Authors: Roberts Lilian M. , Reeve E. C. R. 
Published: September 2009

SUMMARYA mutation inEscherichia coliK12 giving resistance to about 5 μg/ml of streptomycin was found to be cotransducible by P1 withproAandproB, and is located at about 8·5 min on the chromosome map. The locus is namedstrB. A second mutation to the same resistance level was not cotransducible with eitherproAorproBand must be located elsewhere. Both mutations cause a marked increase in R-factor mediated streptomycin resistance, and significant decreases in resistance to several other antibiotics, both in the presence and absence of an R-factor determinant for the same antibiotic. The two mutations differ in their effects on bacterial sensitivity to crystal violet and EDTA.
Factor responsible for spermatozoan abnormality located on theYchromosome in mice
Authors: Krzanowska H. 
Published: September 2009

Two inbred strains of mice differing in the mean percentage of spermatozoa with abnormal heads were used: KE (16·1%) and CBA (5·9%). TheF1resulting from the crosses exhibited a heterosis effect, while in the backcrosses an obvious segregation of genotypes was observed; both generations showed a reciprocal difference, depending on the source of theYchromosome. The character of sperm head abnormality seems to be polygenically determined, one of the genes being located on chromosomeY.Seven generations of backcrosses were performed in which theYchromosome from CBA was introduced to the genetical background of the KE strain. In the seventh generation 10·2% of abnormal spermatozoa were found, which is significantly lower than in the KE strain. The difference shows the net effect of theY-linked locus. A correlated difference was found in the fertilization rate, indicating that a factor influencing male fertility is located on chromosomeY. It does not seem to influence the shape of normal spermatozoan heads.Karyotype analysis did not reveal gross abnormalities in the KE strain.
Genetic studies of ovulation rate in the mouse
Authors: Land R. B. , Falconer D. S. 
Published: September 2009

Genetic and physiological studies of ovulation rate, both natural and induced, in a random bred population of laboratory mice led to the following results.(1) The heritability of natural ovulation rate in nulliparous females was 22±19%, estimated from the correlation between paternal half-sibs.(2) Selection applied to natural ovulation in primiparous females led to a response in both directions, with a realized heritability of 31% (h2within litters = 0·18 ± 0·013). The number of eggs shed by the High, Control and Low lines after 12 generations were respectively 21, 16 and 14.(3) Selection applied to ovulation induced by 4 i.u. of PMS led also to a response in both directions, with a realized heritability of 22% (h2within litters = 0·11 ± 0·038). The induced ovulation rates of the High, Control and Low lines after 12 generations were respectively 29, 19 and 14 eggs.(4) PMS-equivalents were calculated from dose-response curves, and were found to be nearly the same in all lines except the line selected for high natural ovulation rate, which had a PMS-equivalent nearly double that of the Control. From this it was inferred that the increase of ovulation rate resulting from selection for high natural ovulation was due to an increased FSH activity, whereas the changes of ovulation rate resulting from selection for low natural ovulation and for both high and low induced ovulation were due to changes of ovarian sensitivity.(5) Genetic correlations, estimated from correlated responses to selection, were: (i) between natural and induced ovulation in primiparous females, 0·33; (ii) between primiparous and nulliparous females in natural ovulation, 0·46; (iii) between primiparous and nulliparous females in induced ovulation, 0·82.(6) The selection for induced ovulation produced changes in litter size following natural ovulation that were nearly equal to the changes in natural ovulation rate. The selection for natural ovulation, however, produced no clear changes of litter size.
Investigation of the mating system of Pseudomonas aeruginosa strain 1: IV. Mapping of distal markers
Authors: Loutit J. S. 
Published: September 2009

Thirteen selected distal markers have been mapped by time of entry studies and linkage analysis. They appear to fall on two distinct linkage groups and with the ten previously described there are nineteen markers on one group and four on the other. There is as yet no clear evidence that the two groups are linked, but this possibility has not been excluded.Of the thirteen markers described, six can be mapped by measuring their time of entry into suitable recipients. It should now be possible to establish the order of any further marker and to provide more accurate information for any marker transferred within 35 min from the time of mixing the cells.
On the theory of artificial selection in finite populations
Authors: Hill W. G. 
Published: September 2009

The effect of selection on individual performance for a quantitative trait is studied theoretically for populations of finite size. The trait is assumed to be affected by environmental error and by segregation at a single locus. Exact formulae are derived to predict the change in gene frequency at this locus, initially by finding the probability distribution of the numbers of each genotype selected from a finite population of specified genotypic composition. Assuming that there is random mating and no natural selection the results are extended to describe repeated cycles of artificial selection for a monecious population. The formulae are evaluated numerically for the case of normally distributed environmental errors.Using numerical examples comparisons are made between the exact values for the predicted change in gene frequency with values obtained using approximate, but simpler, methods. Unless the gene has a large effect (α) on the quantitative trait, relative to the standard deviation of the environmental errors, the agreement between exact and approximate methods is satisfactory for most predictive purposes. The chance of fixation after repeated generations of selection is also evaluated using the exact method, and by means of a diffusion approximation and simple transition probability matrix methods. Except for very small values of population size (N) and large α the results from the diffusion equation agree closely with those from the exact method. Similar results are found from tests made of the prediction from the diffusion equation that the limit is only a function ofNα for a given intensity of selection and initial frequency, and that the rate of advance in gene frequency is proportional to 1/Nfor the same set of parameters.
Selection for larval growth inTriboliumunder two levels of nutrition
Authors: Yamada Yukio , Bell A. E. 
Published: September 2009

Selection for large and small 13-day larval weight inTribolium castaneumwas studied for sixteen generations in a replicated experiment to evaluate the effectiveness of various selection methods and the importance of genotype by environment interactions under two levels of nutrition.Direct selection responses generally were larger than correlated ones under both Good and Poor nutritional environments. However, contrary to theoretical expectations, those populations selected on average performance in both environments were not superior for this attribute.Asymmetrical responses were observed to be dependent on the environment of selection. When selection was based on performance in the optimal environment, the asymmetry was observed toward small size. This situation in the sub – optimal environment was completely reversed. This phenomenon was discussed in terms of physiological limits rather than gene frequency and directional dominance.It was proposed that selection of compound traits such as body weight at a fixed age may affect the component characters quite differently. As the latter are differentiated by direction and environment of selection, the compound trait may reflect parametric changes and enhanced genotype by environment interactions. Such changes hamper the precision of current selection theory for predicting response even in the short run.
A comparison of some biological characteristics of the mouse-passaged scrapie agents, 22A and ME7
Authors: Dickinson A. G. , Meikle Veronica M. H. 
Published: September 2009

Two mouse-adapted scrapie agents of different sheep origin were compared. The titre, reached in the brains of mice in the terminal stage of scrapie, is of the same order for both agents. There is a threefold difference between the incubation periods of the two agents in some mouse strains, of which C57 is one, and in this strain incubation of the 22A agent, given as a large dose by a peripheral route, occupies almost the whole life-span.The most fundamental difference between the agents concerns the reversal of the ranking of incubation periods, typically in the VM and C57 mouse strams: incubation of ME7 in VM takes almost twice as long as in C57, whereas most sub-lines of 22A take half as long in VM as in C57. The implications of this type of host-genotype, agent-strain interaction are discussed in terms of the possible nature of agent differences, the possibility of latent infection and the consequences for scrapie eradication programmes.
The spread of genes in random mating control populations
Authors: James J. W. 
Published: September 2009

1. The effect of genetic sampling, when this sampling is without replacement, on variation in gene frequency is studied, and equations describing the genetic drift are derived. The effective size turns out to be about one greater than under sampling with replacement.2. The relation between ‘spread of genes’ and genetic drift is worked out.3. The University of Queensland control poultry flock is analysed by these methods.4. The design of control populations is discussed with particular reference to the relative importance of genetic drift and phenotypic sampling.
Recombination in a Myxomycete, Physarum polycephalum Schw.
Authors: Dee Jennifer 
Published: September 2009

1. Techniques were developed to facilitate genetic analysis of a Myxomycete, Physarum polycephalum. The uninucleate cells that form part of the life-cycle (the ‘amoebae’), in two-membered culture with Pseudomonas fluorescens, were found to be suitable for handling by some of the standard techniques of microbial genetics, including plating.2. As reported previously, a single-factor (+/−) mating-type system was discovered in P. polycephalum controlling the formation of plasmodia by the amoebae. Plasmodia are formed only when amoebae of different mating-type are mixed together. A single spore gives a culture of amoebae of one mating-type only, which may be assumed to be a clone.3. A strain of amoebae resistant to emetine hydrochloride was isolated and was found to maintain its resistance through many subcultures in the absence of the drug.4. A cross was made between the emetine-resistant strain (mating-type −) and an emetine-sensitive strain (mating-type +). Spores obtained from the hybrid plasmodium were plated and four sets of isolates of amoebae were made from these spores, and separately tested for mating-type and for emetine resistance.5. The results of testing these isolates agree with the hypothesis that mating-type and emetine resistance are determined by pairs of alleles at two unlinked loci provided that factors disturbing the segregation for emetine resistance are assumed to be present.6. Consideration of factors that could have disturbed the segregation for emetine resistance shows that selfing did not occur in the cross but that some misclassification for emetine resistance probably did occur.
The efficiency of food utilization, digestibility of foodstuffs and energy expenditure of mice selected for large or small body size
Authors: Fowler Ruth E. 
Published: September 2009

The efficiency of food utilization, the digestibility of foodstuffs, energy metabolism, and body activity have been studied in three lines of mice, one selected for large, another for small body size, and a third, control, line.The gross efficiency of food utilization was highest in the large line, intermediate in the control line and lowest in the small line between 21 and approximately 35 days of age. During this period, gross efficiency declined in the large and control lines with increasing size and decreasing growth-rate, presumably due to an increase in maintenance costs in comparison with the weight gained. In the small line, the efficiency of food utilization increased up to 35 days of age but declined thereafter. The energetic efficiency (measured in Calories) was higher in the large than in the small line up to 4 weeks of age, i.e. when the growth-rate was high, and after 6 weeks of age, when fat was being deposited at an increased rate.The increased efficiency of large mice was not entirely associated with a greater proportion of the ingested food being absorbed from the gut. Large mice absorbed a greater proportion of protein, though the difference was not sufficient to account for the large weight difference between the large and small lines.The energy expenditure of mice of the large line was greater than that of the small line at all ages and similar for the same body weights. The reduced growth-rate of small mice was not due to abnormally high or low energy costs. There was no evidence that body activity determined or restricted the rate of growth in either line.Mice selected for small size were phenotypically unlike pituitary dwarf mice, although the low nitrogen retention during the growing-period indicated a deficiency of some growth stimulus.
Genetical studies on the skeleton of the mouse XXXII. The Development of Shaker with Syndactylism
Authors: Grüneberg Hans 
Published: September 2009

1. The first known effect of the gene for shaker with syndactylism (sy) in the mouse is a reduction, both preaxial and postaxial, of the foot plates at the 12½-day stage. This reduction forces the blastemata of digits 2, 3 and 4 to be laid down more nearly parallel to each other, with a subsequent tendency for adjacent blastemata to coalesce with each other. The possibility is considered that this essentially quantitative reduction of the foot plate material may itself be the consequence of some more specific and qualitative (but hitherto undiscovered) change in the limb buds.2. The physiological connexion between syndactylism and the systemic changes in the cartilaginous and osseous skeleton which arise later in sy/sy mice remains obscure.
The application of tissue-culture techniques to the chromosomal analysis of Bos taurus
Authors: Crossley R. , Clarke G. 
Published: September 2009

Until 1960 all the chromosome counts performed on cells of this species were done on histologically prepared specimens of testicular tissue. In January 1960, Chiarelli et al. published the results of their experiments to grow renal tissue in culture. Their specimens were obtained from male and female calves. They confirmed that 2n = 60 and described the chromosomes as being all acrocentric except the X chromosome, which was submetacentric.The purpose of the work described below was to try to apply the peripheral-blood culture technique of Moorhead to bovine blood, and to attempt to grow bovine muscle cells in a tissue culture.
The size and endocrine activity of the pituitary in mice selected for large or small body-size
Authors: Edwards R. G. 
Published: September 2009

Mice of two strains, N and C, were used in studies on body-size, pituitary size, and endocrine potency of the pituitary. Strain N had been selected for large (NL) and small (NS) body-size; strain C had also been selected for large body-size (CL) but had been crossed to an outbred strain segregating pituitary dwarfism.Pituitary weights and body-weights were highly correlated, the regression lines being common in NL and NS mice. Female pituitaries were considerably heavier than male pituitaries in CL mice. In relation to body-weight, CL pituitaries were consistently heavier than those of NL or NS mice.No differences were detected in the unit potency of gonadotrophins in the pituitaries of NL and NS mice as estimated by the uterine response of immature outbred mice to subcutaneous injections of pituitary tissue. The uptake of 131I into the thyroid was comparable in NL and NS mice per unit of body-weight, and the thyroid secretion rate was also similar using animals of the same body-weight. Immature mice of both lines responded by increased growth to injections of growth hormone or fresh mouse pituitary, though the response was greater in NS than in NL mice.The primary response to selection has probably been in the size of the pituitary rather than in its unit potency. The interrelationships between body-size, body components, organ size and endocrine levels are discussed.
The phenogenetics of hair mutants in the house mouse: Opossum and Ragged
Authors: Mann Stanley J. 
Published: September 2009

1. The development and morphology of the semi-dominant mutations Ragged and Opossum are compared. The results of the present study support evidence of previous linkage studies which suggest that Ragged (Ra) and Opossum (Raop) are alleles.2. Examination of embryos from 18-day-old first parity matings of + + × Raop + reveals that there is no deficiency of Raop + embryos. However, in Ra + × Raop + and Raop + × Raop + matings some Raop + embryos die in utero in addition to the pre-natal death of the RaRaop and RaopRaop embryos.3. In all matings of Ragged and Opossum, there is a high frequency of oedematous Raop + embryos. In + + × Raop + matings, the frequency of oedema increases with increased age of the embryos.4. Although the pattern of hair follicle formation is the same in both the mutant and normal embryos, follicles begin initiation later in the mutant embryos. The delay in follicle initiation is increased in the following order: Ra +, Raop + (non-oedemic), RaRa and Raop + (oedemic).5. Heterozygous Opossum and Ra + mice have a full complement of pelage follicle primordia, but some follicles fail to differentiate. The differentiating follicles pass through the same developmental stages and require the same time for development as follicles in + + mice.6. Heterozygous Ragged and Raop + mice have a full complement of tylotrichs, whereas the concentration of awls is variable. In Ra + mice there is a reduction in zigzags, and Raop + mice usually lack zigzags. No auchenes are observed in the mutant mice.7. Hair growth is asynchronous in Ra + and Raop + mice, with the exception of the first pelage coat. The quiescent phase of the hair growth cycle is short or even missing.8. The degree of Ra and Raop gene activity is in the following order of increased severity: Ra +, Raop + (semi-lethal), RaRa (semi-lethal), RaRaop (lethal) and RaopRaop (lethal).
F-prime transfer and multiplication of sexduced cells
Authors: de Haan P. G. , Stouthamer A. H. 
Published: September 2009

A variable delay among mating pairs in the time between contact formation and the initiation ofFtransfer was found. The conjugation process has no effect on the multiplication of the recipient cell.In liquid medium newly infectingF-particles multiply faster than the host cell.The experiment strongly suggests that the number of episomes per cell is small and that the distribution of theF-factor among the daughter cells is non-random.
Mutations of theAmating type factor inCoprinus lagopus
Authors: Day P. R. 
Published: September 2009

TenAfactor mutants and an unlinkedAsuppressor mutant were isolated from fruit bodies formed by commonAheterokaryons ofCoprinus lagopus. AllAfactor mutants formed false clamps and lackedAmating-type specificity. FourA5and twoA6mutants had functional α sub-units which were recovered in tests for intra-factor recombination in matings between mutant and wild-type factors. No functional β sub-units were recovered in tests of two of theA5mutants and the twoA6mutants which possessed functional α sub-units. From three other mutants (twoA5and oneA6) neither α nor β sub-units were recovered.The suppressor mutant also formed false clamps but was recessive since stocks carrying it retained theirAandBspecificities when mated with wild-type testers. Fruit bodies formed by monokaryons carrying the suppressor mutant had pale gills bearing varying proportions of abnormal tetrads with less than four spores.
Serum transferrins in Merino sheep
Authors: Ashton G. C. , Ferguson K. A. 
Published: September 2009

Serum samples from 1963 Merino sheep were examined for serum transferrin type. Two of the five transferrin alleles previously described in British breeds of sheep, viz.T fAandT fc, were found, butT fB,T fDandT fEwere absent. Evidence for seven further transferrin alleles was obtained. These alleles were codedT fF,T fG,T fH,T fJ,T fN,T fKandT fLin decreasing order of mobility of the zones they produce in starch gel.Gene frequency data is presented for the populations studied.