bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetical studies on the skeleton of the mouse XXIX. Pudgy
Authors: Grüneberg Hans
Published: September 2009

The recessive mutant pudgy in the mouse has a greatly shortened vertebral column with highly irregular fusions between vertebrae and fragments of vertebrae. Ribs and sternum are also involved, but the rest of the skeleton is quite normal. The deformities arise from a defective segmentation. Although the paraxial mesoderm forms somite tissue with an epithelially arranged outer layer, this material either shows only an abortive segmentation into somites or, in the tail, none at all. A belated segmentation into dermomyotomes ultimately takes place, but the sclerotomic material remains continuous and gives rise to erratically abnormal blastemata which then chondrify and ultimately ossify.
Pairing interaction as a basis for negative interference
Authors: Maccacaro G. A. , Hayes W.
Published: September 2009

The recurring problem of negative interference in conjugal crosses ofEscherichia coliK-12 (Rothfels, 1952; Cavalli-Sforza & Jinks, 1956; Wollman, Jacob & Hayes, 1956) has been periodically overshadowed by new discoveries concerning the mechanism of genetic transfer in this organism, such as unidirectional and partial transfer (Hayes, 1953; Wollmanet al., 1956) and the genetic heterogeneity of zygotes formed in F+× F−crosses (Jacob & Wollman, 1957), which have led to reappraisal of the interpretation of the genetic data. While some of those data (e.g. those of Rothfels, 1952) can be interpreted entirely on the basis of prezygotic elimination of the male genetic contribution, others (e.g. those of Cavalli-Sforza & Jinks, 1956) could not be, and were not, explained entirely on such a basis but demanded the introduction of the notion of incomplete pairing. Meanwhile the problem of negative interference became an important issue in other microorganisms such as bacteriophage,Aspergillus, Neurosporaand yeast (review, Pritchard, 1960). The most plausible current model of localized negative interference in these organisms postulates that chromosome pairing is discontinuous and random, and that recombination only occurs within those small regions where pairing is effective (Pritchard, 1955; Chase & Doermann, 1958); thus the ‘coincidence of recombination in two intervals would occur with greater than random frequency if these intervals were short enough and close enough to be frequently included within one effectively paired segment’ (Pritchard, 1960). The mean distance over which such negative interference operates is very small, being of the order of only a few cistrons in both bacteriophage andAspergillus(Pritchard, 1960).
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.
Polygene analysis II. Selection
Authors: Gilbert Neil
Published: September 2009

A modest theory of polygene selection is presented. Recently published data show that the curved model of gene action (presented in a previous paper) is insufficiently general. The curved model does, however, show that the scaling tests (used in the additive type of polygene analysis) do not guarantee additivity; they guarantee a state of indeterminacy, in which additivity is one of a range of reasonable possibilities. These different possibilities give entirely different predictions of selective advance. The failure (in practice) of polygene analysis does not reduce the value of polygene concepts.
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.
Non-random segregation of chromosomes inAscobolus immersus
Authors: Surzycki S. , Paszewski A.
Published: September 2009

Genetic consequences of non-random segregation of chromosomes are discussed. In the experimental part preferential segregation of two linkage groups inAscobolus immersusis described. This was established in several crosses involving mutants164, XXVIand231(all in the same linkage group) and mutant726.
Chiasmata in spermatocytes of Drosophila melanogaster
Authors: Slizynski B. M.
Published: September 2009

On the basis of chromosome behaviour in three strains of Drosophila melanogaster males—a wild-type strain, a translocation heterozygote strain and a double translocation strain—it is concluded that the cytologically detected apparent chiasmata in the autosomes are only surface associations of homologous chromosomes and do not involve exchange of chromosome material. Such chiasma-like associations occur also between non-homologous chromosomes. The stainable, Feulgen-positive material of the chromosomes is thought to be responsible for the surface associations.
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.
Selection for a threshold character in Drosophila I. An analysis of the phenotypic variance on the underlying scale
Authors: Latter B. D. H.
Published: September 2009

The short-term response to artificial selection in a wild-type population for increased scutellar bristle number, has been interpreted in terms of two alternative threshold models. Both models have been shown to give a satisfactory transformation of the scale of measurement, in that the underlying variable shows an effectively linear response in terms of the accumulated selection differential, and the pheno-typic variance on the underlying scale remains virtually unchanged over a period of generations sufficient to increase the incidence of extra-bristles to almost 100%.

A genetic analysis based on the bivariate model, which to a large extent takes account of the location of the supernumerary bristles, has shown the phenotypic variance on the underlying scale to have the following composition: the additive genetic variance is 27·2 ± 0·9% of the total, and the developmental error or ‘chance’ variance accounts for a further 63·8 ± 2·6%, so that the remaining 9·0 ± 2·7% of the variance must be due to environmental differences among individuals and to non-additive genetic effects.

The relative magnitudes of these parameters are remarkably similar to those observed for two quasi-continuous variables in the same population, viz. abdominal and sternopleural hair number. In view of the ease with which scutellar bristles may be scored, the character can therefore serve as an extremely useful model character for quantitative genetic experiments.
Complementation in balanced heterokaryons and heterozygous diploids ofAspergillus nidulans
Authors: Roberts C. F.
Published: September 2009

1. Two total and five leaky sorbitol mutants isolated inAspergillus nidulansby defective growth on the sugar are all recessive. The mutants are closely linked, they appear to represent three linked genes spanned by a deletion.

2. Mutants which complement in heterozygous diploids do not complement in balanced heterokaryons. Failure to complement is a property of the mutants and not the result of a nutritional interaction or an unfavourable nuclear ratio in the heterokaryons.

3. Sorbitol is oxidized by an inducible enzyme system in the wild-type. There are at least two enzymes concerned in the oxidative assimilation of sorbitol, an initial oxidative enzyme, which is defective in the leaky mutants, and a later enzyme defective in the total mutants. There may also be a second non-oxidative pathway for sorbitol metabolism.

4. In diploids complementary pairs of mutants oxidized sorbitol at 75% the rate of the wild-type but non-complementary mutants did not oxidize the sugar. In balanced heterokaryons none of the pairs of mutants oxidized the substrate. It is concluded that failure ofinter-genic complementation in the heterokaryons is the result of a failure of either enzyme formation or enzyme function. Models to account for differences in enzyme formation in heterokaryons and diploids are suggested.
Egg albumen polymorphisms in the fowl: The ovalbumin locus
Authors: Lush I. E.
Published: September 2009

1. Ovalbumin was shown, by starch gel electrophoresis, to exist in two genetically different forms, A and B. It was suggested that these are determined by two alleles at one locus, namedOv.

2. Ovalbumin of each genetic type is electrophoretically heterogeneous. Dephos-phorylation of each type with human prostatic phosphatase and calf intestinal phosphatase removed some of the heterogeneity, but some remained.

3. The genetic difference was shown not to reside in the fragment released from ovalbumin by the proteolytic enzyme subtilisin.

4. The genetic difference was evident in the ovalbumin present in the fluid contained in right oviduct cysts.
Episomic suppression of phenotype inSalmonella
Authors: Smith-Keary P. F. , Dawson G. W. P.
Published: September 2009

1. An auxotroph ofSalmonella typhimurium, pro-401, was isolated in a strain that was unstable at thesu-leuAlocus. The auxotrophy ofpro-401is probably due to the attachment of a controlling episome to the proline region of the genome where it suppresses gene expression.

2. The controlling episome frequently transposes over short distances so that all clones consist of cells, mixed for the site at which the controlling episome is attached; homologous transductions yield prototrophs.

3. The controlling episome can transpose to a different complementation group; homologous transductions yield abortive transductants; syntrophism occurs between cells that are ‘mutant’ in different complementation groups to give reversions consisting entirely of auxotrophic cells which are called auxotrophic reversions.

4. The controlling episome transposes over very short distances and never to beyond the limits of this proline region of the genome; no wild-type reversions were found.

5. The controlling episome can be located at relatively distant proline sites in different clones; prototrophs from transductions between clones that are separated by many subculturings can be 100 times more frequent than from homologous transductions.

6. The controlling episome has its frequency of transposition to different complementation groups increased by UV; irradiation increases the frequency of auxotrophic reversions.

7. The controlling episome continues to transpose in stored cells.

8. The pattern of reversions ofpro-401is different in these studies from its pattern two years previously. This is discussed.
Evidence of linkage between two egg albumen loci in the domestic fowl
Authors: Buvanendran V.
Published: September 2009

The ovalbumin locus and locus II (Lush, 1961) were found to segregate in a closed flock of White Leghorns. Three of the nine expected genotypic classes were absent and from this it is concluded that the two loci are very tightly linked.
A gene conferring actidione resistance and abnormal morphology onPhysarum polycephalumplasmodia
Authors: Dee Jennifer , Poulter Russell T. M.
Published: September 2009

Plasmodia ofP. polycephalumhomozygous and heterozygous for a mutation (act) which confers resistance to actidione on the haploid amoebal stage have been tested for resistance to actidione in liquid semidefined medium. Growth of homozygous resistant (act/act) plasmodia determined by protein or pigment assay was inhibited less by actidione than growth of homozygous-sensitive or heterozygous plasmodia. The mutant (act) is therefore recessive but, contrary to a previous report, confers resistance on homozygous plasmodia. The same mutation affects the morphology of homozygous (act/act) plasmodia on agar medium, causing slow growth, fragmentation and excessive sliminess.
Repression of induction by u.v. of λ phage byexrAmutations inEscherichia coli
Authors: Donch John , Greenberg Joseph , Green Michael H. L.
Published: September 2009

The effect of ultraviolet radiation (u.v.) onλlysogens ofexrAstrains ofEscherichia coliwas studied.exrAstrains could be lysogenized with, as well as support the vegetative reproduction of, λ. However, though spontaneous induction of λ occurred inexrA(λ) strain at 10% the frequency ofexrA+(λ) strain,exrA(λ) strains were not induced by u.v. Because λ was not induced inexrA(λ) strains, lysogens of these strains were no more sensitive to u.v. than were non-lysogens.

The heat-inducible mutant λhcI857could be induced inexrAstrains at elevated temperatures. Furthermore, u.v. irradiation ofexrA(λhcI857) strain did not prevent the heat induction of this λ mutant. TheexrAmutation appeared to interfere only with the inactivation of λ repressor by u.v.

Among theexrAstrains studied was strainBs1(exr A uvrB). Whereas the λ lysogen of strain Bsl could not be induced by u.v. and was no more sensitive to u.v. than its non-lysogen, theexrA+uvrB(λ) derivative of strain Bsl could be induced by u.v. and was more sensitive to u.v. than its non-lysogen.
Selection in experimental populations ofDrosophila pseudoobscurawith different initial frequencies of chromosomal variants
Authors: Watanabe T. , Anderson W. W. , Dobzhansky Th. , Pavlovsky O.
Published: September 2009

Eight experimental populations ofDrosophila pseudoobscurawere made in laboratory population cages. All were polymorphic for ST, AR, CH, and PP gene arrangements in their third chromosomes, and all the chromosomes were of the same geographic origin. The initial frequencies of the gene arrangements were, however, different in the different populations. Natural selection has caused frequency changes in all the populations, from which we have attempted to infer the adaptive values of the different karyotypes. There was no evidence that the adaptive values were different in the populations begun from different initial frequencies of the inversions, although our ability to demonstrate such differences is severely limited. The selection process in these populations has been complex, and the simple model of constant adaptive values does not fit.
The nature of the leucine requirement of the barley mutant Xan-b61
Authors: Land J. B. , Norton G.
Published: September 2009

Contrary to previous reports, evidence has been presented which indicates that Xan-b61, a Xantha mutant of barley, does not have an auxotrophic requirement for leucine. It has been shown that this mutant, when grown under appropriate conditions in the absence of leucine, will synthesize leucine and will continue to grow for an extended period of time.
Genetic fine structure of the albino (al) region ofNeurospora crassa
Authors: Subden R. E. , Threlkeld S. F. H.
Published: September 2009

By crossing a pair of albino strains each with a different adjacent nutritional marker and then crossing the same pair of albino markers with the nutritional markers transposed it was possible to order a series ofalmutants with a resolution approaching that available for nutritional markers. A genetic map with approximated distances is provided demonstrating a grouping of mutant sites for a range of discrete carotenoidless phenotypes.
A search for temperature-sensitive mutants ofUstilago maydisblocked in DNA synthesis
Authors: Unrau P. , Holliday R.
Published: September 2009

Over 400 temperature-sensitive mutants ofUstilago maydishave been tested for DNA synthesis at the restrictive temperature of 32°C by measuring14C adenine incorporation into DNA and RNA. Five mutants were defective in DNA synthesis but none was completely blocked. One mutant,tsd-1, which is unlinked to the others, forms long uninucleate filaments at 32°C which die exponentially after 4h temperature treatment. The phenotype is comparable to that of thymine-starved bacteria, but it is possible that rather than being specifically defective in DNA synthesis the mutant is blocked in nuclear division.
Genetic and phenotypic relationships between ovulation rate and body weight in the mouse
Authors: Land R. B.
Published: September 2009

The genetic and phenotypic regressions and correlations between ovulation rate and body weight were examined in a random bred strain (Q) of laboratory mice during the course of three experiments. These experiments were (1) a sib analysis; (2) selection for natural and induced primiparous ovulation rate; and (3) replicated selection for 6-week weight. The following results were obtained:

(a) The genetic correlations between body weight and natural and induced ovulation rate were positive, and approximately equal to 0·4 and 0·6 respectively.

(b) The genetic regressions of natural and of induced ovulation rate on body weight were approximately 0·4 and 0·9 eggs per gram respectively.

(c) The genetic regressions of body weight on natural and on induced ovulation rate were approximately 0·5 and 0·25 g per egg respectively.

(d) The phenotypic correlation between natural ovulation rate and body weight was approximately 0·4 and the corresponding regression of ovulation rate on body weight approximately 0·4 eggs per gram.

(e) The phenotypic correlation between induced ovulation rate and body weight declined from 0·4 at 6 weeks of age to zero at the time of scoring, the corresponding regressions of ovulation rate on body weight declining from 0·1 eggs per gram to zero.

It was concluded that natural ovulation rate itself, and both its components (FSH activity and ovarian sensitivity) are positively genetically correlated with body weight. Furthermore, the observation that large mice shed at least as many eggs as small ones in response to the same dose of PMS showed that the response was more closely related to the absolute dose than to the resultant concentration.
Controlling elements in the mouse X-chromosome
Authors: Cattanach B. M. , Perez J. N. , Pollard C. E.
Published: September 2009

The frequency and nature of the changes in ‘state’ of the mouse X-chromosome controlling element (inactivation centre) have been investigated on an inbred background. The results indicate with near-certainty that meiotic crossing over is the responsible mechanism and that the frequency of recombination between theT(1; X)Ctbreakpoint and the locus of the controlling element is approximately 3%. Maize-type ‘changes in state’ may occur under other experimental conditions. The data do not distinguish on which side of the autosomal insertion the element lies but when combined with observations of other investigators suggest that the location must be on theMo-Taside and very close toTa.
The effect of individual rye chromosomes on the amino acid content of wheat grains
Authors: Riley Ralph , Ewart J. A. D.
Published: September 2009

At the present time attempts are being made to improve the nutritional value of wheat by increasing the content of certain essential amino acids, particularly lysine, in the proteins of the grain. Rye grain has a considerably higher lysine content than that of wheat. Consequently in the present work studies were made of the amino acid contents of the grains of the wheat variety Holdfast, the rye variety King II, the Triticale derived from these parental varieties and the seven lines in which, in turn, each pair of chromosomes of King II are separately added to Holdfast.

Rye chromosome I increased the lysine content of wheat by 8·7% and associated changes in the proportions of other amino acids suggest that this increase is meaningful. Rye chromosome I is in homoeologous group 5 and other reports have indicated a relationship between changed lysine content and another character determined by chromosomes of this group. Consequently there is a suggestion that group 5 chromosomes may be of particular significance in the determination of lysine content in wheat grains. Confirmation of this would lead to a more rational approach to breeding for higher lysine content.
A gene triplet in the mouse
Authors: Searle A. G. , Truslove Gillian M.
Published: September 2009

Mice heterozygous for rump-white (Rw) have white hair in lumbo-sacral and caudal regions, although the tail-tip is sometimes pigmented. The homozygote is lethal in utero. No recombination has been found between Rw and the very closely linked spotting genes patch (Ph) and the viable allele of W (Wv). The compounds between these genes are all viable and fertile, although individual homozygotes are either lethal (Ph, Rw) or sterile and anaemic (Wv). It is concluded that they are non-allelic, but form a gene triplet. Close linkage between a cluster of dominant spotting genes and an angora gene in mouse and rabbit provide evidence for homology of part of linkage group II in the rabbit and part of linkage group XVII in the mouse.
A note on the diffusion approximation for the variance of the number of generations until fixation of a neutral mutant gene
Authors: Narain P.
Published: September 2009

A general expression is derived for the variance of time to fixation of a neutral gene in a finite population using a diffusion approximation. The results are compared with exact values derived by matrix methods for a population size of 8.
Cell number in early embryos from strains of mice selected for large and small body size
Authors: Bowman Patricia , McLaren Anne
Published: September 2009

Embryos were recovered 3½ days post coitum from females of three replicate large- and small-selected Q-strain lines, together with their unselected control lines. Selection had been carried out by D.S. Falconer, resulting in large and small lines which differed two-fold in adult body weight. Females of the large lines yielded significantly more embryos than those of the other lines. Embryo cell number showed significant heterogeneity among replicates, but was similar in large, small and unselected lines. The data are not consistent with the hypothesis that the divergence in adult body weight is due to a uniform difference in rate of cell division throughout development.
Association of genetic polymorphisms with embryonic mortality in the chicken: II. The B blood-group system and the pure and crossbred progeny of two populations
Authors: Gilmour D. G. , Morton J. R.
Published: September 2009

We have studied the association of the ten possibleBblood-group genotypes with mortality during incubation in the 1966 generation of two relatively noninbred populations of Light Sussex chickens. These were related substrains 6D and 6F derived in the 1964 generation by equal division of strain 6, which we had previously studied in its 1962 generation. TheBblood-group genotypes of zygotes but not of dams were associated with marked mortality differences in 6F, while in 6D almost no differences were found. Comparisons of the findings in 6D and 6F with the results previously published for the ancestor strain 6, after adjustment for overall between-population differences, showed marked changes between 6 and 6F in the mortalities associated with the five most frequent genotypes. In four of these, the mortalities in 6D were about half way between those in 6 and 6F. Taken together, these results provide evidence that the selective pressures on theBlocus from differential embryonic mortality vary from generation to generation and even between populations differing apparently only slightly in environment and genetic composition.

In progeny of crosses between females from 6D and 6F with males from 5D and 5F respectively, the latter being two related Rhode Island Red/New Hampshire substrains, embryonic mortality was much lower than in the pure matings within 6D and 6F, and only a few associations withBblood-group genotypes of zygotes were found.

The results are discussed in relation to the general lack of association of polyallelic polymorphisms with aspects of fitness reported by other workers; and the importance is stressed of studying associations of genotypes rather than genes or serological factors.
A rapid and efficient replica plating technique
Authors: Wood Thomas H. , Mahajan Suresh K.
Published: September 2009

A new type of apparatus for replica plating is described, which reduces operator error and fatigue. Several replica plates can be made immediately, thus eliminating the need for a master plate in many cases.
DNA feeding and directed mutagenesis in Drosophila melanogaster
Authors: Chopra V. L.
Published: September 2009

The mutagenic effects of feeding calf-thymus DNA to larvae of Drosophila melanogaster have been studied on second chromosome recessive lethals, sex-linked dominant and recessive visibles and dominant autosomal visible mutations. While a positional specificity of DNA-induced lethals has been confirmed, no evidence has been obtained for a preponderance of visible mutations or for a specificity of phenotype among the visibles.
Some new mutants of the Large Milkweed BugOncopeltus fasciatusDall
Authors: Lawrence Peter A.
Published: September 2009

Three new autosomal mutants of the milkweed bug,Oncopeltus, obtained by treatment with ethylmethane sulphonate, are described and compared with the two other previously known variants. Preliminary data are given on the results of testcrosses and of chromatographic analysis of some pteridene pigments.
Small, inherited differences in blood glucose levels in mice
Authors: Charlesworth Deborah
Published: September 2009

Blood glucose levels of mice from five strains were measured. The results showed that each strain was different from the others for genes affecting blood glucose level, although the strain differences were small.

Within strains, the chief sources of variation were sex differences, differences between mice from different litters of the same mother, and between mice assayed in different months. Repeatability of measurements on individual mice was low. Genetic analysis, even by biometrical techniques, was not possible because the small genetic effects were obscured by variation due to other causes.
A lethal factor in a strain ofVibrio El Tor
Authors: Iyer S. S. , Bhaskaran K.
Published: September 2009

The advantage in using membrane filters for crosses between P+(donor) and P−(recipient) strains ofVibrio cholerae(Bhaskaran, 1964; Bhaskaran, Sinha & Iyer, 1967) is probably due to more frequent and effective contacts between the cells on the surface of the membrane than is possible in fluid media with actively motile cells of this species. The transfer of the fertility (P) factor itself, as well as the yield of genetic recombinants, was considerably improved by this procedure.
The effect of homozygous deletions upon heterozygote formation in bacteriophage T4D
Authors: Kvelland Ingerid
Published: September 2009

Experiments were designed to investigate the effect of homozygous deletions upon the frequency and the average length of heterozygous regions in bacteriophage T4D. A long deletion,rdf41, which covers at least the wholerII region, was found to increase the heterozygosity forr48, while no increase was observed when a short deletion was employed. The long deletion was found to increase the average length ofamber-HETs by a length approximately the size of therII region.

A drastic reduction in average HET length was found in FUDR crosses homozygous for the long deletionrdf41, indicating that the type of HET that does increase in FUDR is very short.

In the cross with no deletion in either parent, premature lysis HETs were found to be much longer than normal lysis HETs. Assuming that redundancy HETs are long compared to heteroduplex HETs this result indicates that redundancy HETs are made earlier in the latent period than heteroduplex HETs. A fluctuation in HET frequencies was found for different markers, especially in FUDR.

About half of all HETs, both in normal crosses and in FUDR crosses, was found to be parental for outside markers.

In non-FUDR crosses, polarized segregation was shown by 12 out of 27 multi-marker HETs after normal lysis and 5 out of 22 multi-marker HETs after premature lysis. In FUDR crosses, 24 out of 77 multi-marker HETs showed polarity.
Chromosomal transfer mediated by de-repressed R factors in F−Escherichia coliK 12
Authors: Cooke Marylyn , Meynell Elinor
Published: September 2009

Conjugation brought about by each of eight different R factors was as efficient as with F in the production of genetic recombinants for a variety of genes located throughout the chromosome ofEscherichia coliK12.
Cytoplasmic isocitrate dehydrogenase variation within the C3H inbred strain
Authors: McLaren Anne , Taita Andrew
Published: September 2009

Two allelic forms of the supernatant NADP isocitrate dehydrogenase (IDH) are found in inbred strains of mice (Henderson, 1965). The five C3H substrains tested, namely C3H/HeJ, C3H/Re-sl, C3H/N-wJ+, C3H/J-WX+ and C3HeB/FeJ, all proved to be of the Id-la/Id-la genetic constitution. (For the nomenclature of inbred strains and substrains of mice see Staats, Committee on Standardized Nomenclature for Inbred Strains of Mice, Cancer Res. 24 (1964), 147–168.) All these substrains were obtained from E. S. Russell at the Jackson Memorial Laboratory, Bar Harbor, Maine, and were presumably all derived from C3H/He mice.
Effect of arecAgene on cell division and capsular poly-saccharide production in alonstrain ofEscherichia coli
Authors: Green Michael H. L. , Greenberg Joseph , Donch John
Published: September 2009

InEscherichia colithe u.v. sensitivity generecAsuppressed u.v.-induced filamentation in alonu.v. sensitive strain without affecting capsular polysaccharide production.recAappears to prevent the stimulus that leads to filamentation in alonstrain.
Muted, a new mutant affecting coat colour and otoliths of the mouse, and its position in linkage group XIV
Authors: Lyon Mary F. , Meredith R.
Published: September 2009

The autosomal recessive gene muted, mu, which arose spontaneously, dilutes coat and eye colour and causes absence of otoliths in some but not all homozygotes. Its locus is in linkage group XIV of the mouse, and the order of loci was shown to be bg–Xt–sa–mu–f–pe.
Sexual and parasexual analysis ofUstilago violacea
Authors: Day A. W. , Jones J. K.
Published: September 2009

Forty-two mutants of the anther smut fungusUstilago violaceawere mapped by means of complementation tests, mitotic haploidization, and meiotic segregation. Spontaneous mitotic haploidization was very rare, but haploids were induced at a high frequency usingp–fluorophenylalanine (PFP). Haploid segregants appeared as fast-growing, spherical colonies (papillae) which grew away from the diploid growth on PFP medium. Thirty-three markers, classified by complementation tests into 21 genes, were mapped by mitotic haploidization in 10–12 linkage groups. There were no discrepancies in the linkage data, and all the markers could be assigned unequivocally to linkage groups. Although about 250 diploids were analysed, there were no segregants in which mitotic crossing-over and mitotic haploidization appeared to have occurred simultaneously.

Thirteen of the 33 markers, in six or seven genes, were expressed infrequently (0–5%) in the papillae produced on PFP medium. These markers, which behaved unusually and were designated missing-markers, were found to be on two chromosomes which tended to remain disomic on PFP medium. Thus 8–10 chromosomes haploidize readily on PFP medium, whereas two other chromosomes are resistant to the effects of PFP and remain disomic. Meiotic segregation was investigated in crosses of genetically marked haploid stocks and also hi diploids, using the host plant. Some of the results enabled preliminary maps to be made of three linkage groups. The results from meiotic segregation were fully compatible with those from mitotic haploidization and the complementation tests.

The genetical evidence for a haploid chromosome number of at least 10–12 is in conflict with the observations of several cytologists thatn= 2 in this species.
Controlling elements in the mouseX-chromosome: I. Interaction with the X-linked genes
Authors: Cattanach B. M. , Pollard C. E. , Perez J. N.
Published: September 2009

The mouseX-chromosome controlling elements, detected by their influence on the position effect variegation caused by theX-autosome translocationT(1;X)Ct, have been found to modify the heterozygous phenotypes of twoX-linked genes. It is proposed thatX-inactivation can be incomplete, the level of inactivation or the frequency of cells in which inactivation is incomplete being dependent upon the ‘state’ of the controlling element located in theX. The data suggest that this is a consequence of a reversal, or partial reversal, of inactivation of theXas a whole in some cells rather than a vairable spread of inactivation along the length of theX.
Genetical studies on growth and form in the fowl: 2. The complexity of changes in skeletal proportions produced by selection
Authors: Cock A. G.
Published: September 2009

Comparisons of skeletal dimensions are made between adult females of four lines of fowl, selected respectively for relatively long and short shanks (HI and LI) and for high and low body wieght (HW and LW) at 10 weeks of age. It is shown that elongation of the leg in HI compared with LI is greatest in the tarsometatarsus, least in the femur. HW and LW are intermediate in this respect. There is no comparable proximo-distal gradient of elongation in the wing. HI differs from LI in a manner comparable to ectomorphy in humans: limb bones are all longer in HI but relatively (and in most instances absolutely) thicker in LI. HW is again intermediate in this respect. The nasal region of the skull is disproportionately elongated in HI compared with LI. In certain bones HI and LI differ widely in cross-sectional shape of the shaft: LI is flatter than HI in the tarsometatarsus, less flat in the coracoid and scapula. HW resembles in each case the line with the less flattened cross-section.
Phenotypic suppression by streptomycin-adenylate and bluensomycin-adenylate
Authors: Harwood J. H. , Smith David H.
Published: September 2009

An arg−conditionally Sm-dependentE. coliB strain became unable to grow on minimal agar containing low levels of Sm when the strain acquired an R factor which mediates Sm and Blu adenylation. The same R-containing strain, however, grew normally when Blu was substituted for Sm in the agar. The data strongly suggest that Sm-adenylate does not suppress the arg−phenotype in anin vivosystem. The possibility that Blu-adenylate can cause phenotypic suppression without being bactericidalin vivois discussed.
Methionine suppressors inAspergillus nidulans: their genetics and behaviour in heterokaryons and diploids
Authors: Ayling P. D.
Published: September 2009

Nine methionine mutants ofAspergillus nidulans(six new mutants plus three isolated previously) were examined; five responded to homocysteine, none responded to cystathionine or cysteine.

Ten revertants of one of the mutants,methB3, blocked before homocysteine, were shown to be due to suppressor mutations. The suppressors were divided into six genes on the basis of complementation tests and recombination data. Mutants of two of the genes were semi-dominant in the heterokaryon but recessive in the diploid. Experiments in which conidial ratios in the heterokaryons were determined suggested that semi-dominance of these suppressors is due to a shift in nuclear ratios in the heterokaryon in favour of the suppressor nuclei.

Some of the suppressors were tested for suppression of two other methionine loci; they acted onmethG1blocked before homocysteine, but not onmethH2blocked after homocysteine, although four out of 13 crosses tested gave ambiguous results.
Interactions between de-repressed F-like R factors and wild type Colicin B factors: superinfection immunity and represser susceptibility
Authors: Frydman Anna , Meynell Elinor
Published: September 2009

F-like R factors are related to ColB-K77, but not to ColB-K98 or ColB-K166, by the criterion of superinfection immunity. Tests of de-repressed mutant R factors for susceptibility to repression by ColB-K98, known to produce represser for F, showed that these could be either repressor-sensitive or insensitive. The former were independently shown not to produce repressor, which was thus, presumably the reason for their de-repressed state.
Location of the Mup-a locus on mouse linkage group VIII
Authors: Finlayson J. S. , Hudson D. M. , Armstrong B. L.
Published: September 2009

By the use of pintail (Pt) and brown (b) as markers, the location of Mup-a, a locus controlling electrophoretic variation of one of the components of the major urinary protein (MUP) complex, on mouse linkage group VIII has been determined. The order and intervals determined from recombination frequencies in 121 offspring from a back-cross were Pt 4·1 b 6·6 Mup-a.