bluuebunny/crossref_metadata_2025_split huggingface dataset:
INTERGROUP PHYLOGENIES IN DROSOPHILA AS DETERMINED BY COMPARISONS OF SALIVARY BANDING PATTERNS
Authors: Stalker Harrison D 
Published: January 2021

ABSTRACT
A salivary gland chromosome phylogeny is presented which summarizes the evolutionary relationships of twenty-two species belonging to the sub-genus Drosophila, and members of the twelve species groups: D. melanica, D. repleta, D. carbonaria, D. polychaeta, D. annulimana, D. robusta, D. carsoni, D. virilis, D. funebris and the "picture-wing," D. mimica and D. crassifemur groups (of Hawaii).—Photographic salivary chromosome maps were prepared for all twenty-two species studied. While the chromosomes of different species belonging to the same group can usually be homologized almost completely, so that construction of intragroup phylogenies is easy, chromosomes of members of different groups are so modified structurally that in most cases only short sections can be fully homologized, and these in only one or two chromosome elements.—Broadly homologous chromosome elements were compared for three species at a time, and on the basis of overlapping homologous sections, or overlapping inversions included within homologous sections, the trio of chromosomes, and the species to which they belonged can often be arranged in a two-step phylogenetic series. Detection of many such ordered trios permits construction of a single phylogenetic scheme encompassing all species.—D. nigromelanica, of the D. melanica group is found to be chromosomally intermediate between the rest of its group and the species belonging to other groups, suggesting that it is the most nearly ancestral member of its group. When trios of species including D. nigromelanica and members of two other species groups are compared, it is found that in twelve of fourteen such comparisons the chromosomes of D. nigromelanica are structurally intermediate between those of the members of the other two species groups, indicating the central position of D. nigromelanica in the phylogeny as a whole.—Available cytological evidence indicates that among the nine continental groups studied, it is the D. robusta group which is chromosomally closest to the Hawaiian "picture-wing" groups. Among the members of the Hawaiian groups it is D. primaeva and D. attigua which are found to be closest to the continental species. This finding tends to confirm the earlier conclusion of Carson and Stalker, based on different evidence, that the above two species were in an ancestral position in the Hawaiian phylogeny.—The relationship of the D. robusta and D. melanica groups demonstrated in this paper, the phylogenies within each of these two groups earlier worked out by Narayanan and by Stalker, and the present geographical distributions of the species within them, require that at least three Asiatic–New World migrations must have occurred during the evolution of the two groups.
GENES INFLUENCING SELECTIVE FERTILIZATION IN NEUROSPORA CRASSA
Authors: Egashira Takeshi , Nakamura Kuzuo 
Published: January 2021

ABSTRACT
The mutual attraction of conidia to protoperithecia of the opposite mating type was studied genetically in crosses where a mixture of conidia from two different strains, one of which was marked by an ascospore color mutant gene tan spore (ts), was applied to protoperithecia. Selective fertilization was measured as the frequency of perithecia fertilized by conidia from one strain in competition with conidia from another strain. Selective fertilization by a given strain varied throughout the range from 10 to 97% according to the strains of protoperithecial parent. The selective fertilization was revealed to be under the control of two or more loci, which appeared to have multiplicative action. No indication of a cytoplasmic effect on selective fertilization was obtained. The strength of the mutual attraction between conidia and protoperithecia decreased as genetic similarity increased.
MUTANTS OF THE BIOLOGICAL CLOCK IN CHLAMYDOMONAS REINHARDI
Authors: Bruce Victor G 
Published: January 2021

ABSTRACT
A genetic analysis of the biological clock in Chlamydomonas reinhardi has been initiated. Of six wild-type strains tested (3 mt+ and 3 mt−), five had periods close to 24 hr whereas one had a 21-hr period. Mutants with altered clock period have been isolated. The periods of 3 of these variant strains are temperature compensated. Genetic crosses involving a long-period mutant suggest that a single gene confers the long-period character, and in general clock-period length seems to be a useful phenotypic measure of alterations in the clock due to genetic differences. One phase mutant was found but its behavior was variable and the phase of the rhythm, relative to a light–dark transition which initiates the rhythm, does not seem to be reliable as a parameter of clock differences. No markers have yet been mapped.
EXTRACHROMOSOMAL ELEMENT DELTA IN DROSOPHILA MELANOGASTER. VIII. INSEPARABLE ASSOCIATION WITH SENSITIVE SECOND CHROMOSOME
Authors: Minamori Sumio 
Published: January 2021

ABSTRACT
The presence of delta is always accompanied by a sensitive second chromosome in Drosophila melanogaster or vice versa. The separability of delta and the chromosome line was investigated in experiments designed to eliminate delta or to suppress its multiplication for a number of generations. Cy/Sb-5 males which transmit a minute amount of delta b (retained by chromosome Sb, kills Sb/Sb and Sb/Sr zygotes) to their progeny were backcrossed for 61 generations to Cy/Pm females which carried no delta. After backcrossing 465 Cy/Sb-5 males were individually examined for retention of delta, and all were found to retain delta b in its latent state. A homozygous strain for the Sr-20B chromosome which retained a minute amount of delta r (retained by chromosome Sr, kills Sr/Sr zygotes) was obtained. 1,252 Cy/Sr-20B females derived from the homozygous strains at the 21st generation were tested individually for delta retention. All females tested were found to retain delta r in its latent state. The delta retention in Sb-5 chromosome lines isolated from Sr-Cy/Sb-5 heterozygous strains which carried delta r but not delta b was examined. The descendant Cy/Sb-5 lines from the heterozygous strains had accumulated their specific delta, delta b. These findings are consistent with those obtained in an earlier study, and lead to the conclusion that delta is associated inseparably with each specific sensitive chromosome.
FACTORS AFFECTING RECOGNITION AND DISJUNCTION OF CHROMOSOMES AT DISTRIBUTIVE PAIRING IN FEMALE DROSOPHILA MELANOGASTER. II. THE EFFECT OF A SECOND ARM
Authors: Moore Charleen M , Grell Rhoda F 
Published: January 2021

ABSTRACT
The behavior of heterozygously inverted X chromosomes that were members of the distributive pool at least 70% of the time was studied when the other pool members were either two free 4's or one compound 4. The X's were structurally modified by additions or deletions of heterochromatin, so that the two homologues differed in both size and configuration or in size alone. In the noncompetitive situation, with two free 4's, recognition between the X's remained high despite the modifications, and primary X nondisjunction was low. In the competitive situation, with the compound 4, distributive nondisjunction of the X's increased approximately two orders of magnitude, and trivalent formation was indicated. Disjunction from the trivalent varied with X size and configuration. When both X's were acrocentric, the smaller X directed the larger X and the very small (see PDF) to the same pole; when the larger X carried a second arm, it assumed the directing role; when the size ratio of the smaller, one-armed X to the larger, two-armed X became less than ∼5/9, the smaller X again directed the other two.
INHERITANCE OF HAIR CONSTRICTIONS IN MICE
Authors: Mann Stanley J , Straile William E 
Published: January 2021

ABSTRACT
The frequencies of multi-constricted hairs in the pelage is the same (75%) in the caudal mid-dorsum of C57BL/10 and CBA inbred mice, but there are more single-constricted hairs in C57BL mice (9.41%) than in CBA mice (0.13%). This structural feature is used as a basis for genetic analysis of the hair coat.—The frequency of single-constricted hairs (4.41%) in F1 mice is intermediate between the frequencies observed in the CBA and C57BL parent strains. Data from the F2 crosses and backcrosses to the respective parent strains indicate that the presence of numerous single-constricted hairs in the pelage is an inherited characteristic. The mode of inheritance is controlled primarily by a semi-dominant autosomal gene (single-constriction; Hct), without the involvement of maternal factors.
RATE OF DECREASE OF GENETIC VARIABILITY IN A TWO-DIMENSIONAL CONTINUOUS POPULATION OF FINITE SIZE
Authors: Maruyama Takeo 
Published: January 2021

ABSTRACT
The rate of decay of genetic variability was investigated for two-dimensional continuous populations of finite size. The exact value of the rate involves a rather complicated expression (formula (4-1)). However, numerical examples indicate that in a population habitat size L × L and density D, the rate is approximately equal to (see PDF) where σ2 is the variance of dispersion distance assuming isotropical migration. The value given in (2) is equal to that of a panmictic population of size DL 2. It is remarkable that whether the rate assumes the value given by (1) or by (2) depends only on Dσ2 (a local property), which is independent of the habitat size. Since, in a one-dimensional population, this depends on both Dσ2 and the habitat size, there is an essential difference between the two types of population structure.—The function giving the probability of two homologous genes separated by a given distance being different alleles was also obtained, (formula (5-1)).
THE ANATOMY AND FUNCTION OF A SEGMENT OF THE X CHROMOSOME OF DROSOPHILA MELANOGASTER
Authors: Judd B H , Shen M W , Kaufman T C 
Published: January 2021

ABSTRACT
An average size chromomere of the polytene X chromosome of Drosophila melanogaster contains enough DNA in each haploid equivalent strand to code for 30 genes, each 1,000 nucleotides long. We have attempted to learn about the organization of chromosomes by asking how many functional units can be localized within a chromomere. This was done by 1) recovery of mutants representative of every cistron in the 3A2-3C2 region; 2) the characterization of the function of each mutant type and grouping by complementation tests; 3) the determination of the genetic and cytological position of each cistron by recombination and deletion mapping. The data clearly show one functional group per chromomere. It is postulated that a chromomere is one cistron within which much of the DNA is regulatory in function.
SEGMENTAL ANEUPLOIDY AND THE GENETIC GROSS STRUCTURE OF THE DROSOPHILA GENOME
Authors: Lindsley Dan L , Sandler L , Baker Bruce S , Carpenter Adelaide T C , Denell R E , Hall Jeffrey C , Jacobs Patricia A , Miklos George L Gabor , Davis Brian K , Gethmann R C , Hardy R W , Hessler A , Miller Steven M , Nozawa Hiroshi , Parry Dilys M , Gould-Somero M 
Published: January 2021

ABSTRACT
By combining elements of two Y-autosome translocations with displaced autosomal breakpoints, it is possible to produce zygotes heterozygous for a deficiency for the region between the breakpoints, and also, as a complementary product, zygotes carrying a duplication for precisely the same region. A set of Y-autosome translocations with appropriately positioned breakpoints, therefore, can in principle be used to generate a non-overlapping set of deficiencies and duplications for the entire autosomal complement.—Using this method, we have succeeded in examining segmental aneuploids for 85% of chromosomes 2 and 3 in order to assess the effects of aneuploidy and to determine the number and location of dosage-sensitive loci in the Drosophila genome (Figure 5). Combining our data with previously reported results on the synthesis of Drosophila aneuploids (see Lindsley and Grell 1968), the following generalities emerge.—1. The X chromosome contains no triplo-lethal loci, few or no haplo-lethal loci, at least seven Minute loci, one hyperploid-sensitive locus, and one locus that is both triplo-abnormal and haplo-abnormal. 2. Chromosome 2 contains no triplo-lethal loci, few or no haplo-lethal loci, at least 17 Minute loci, and at least four other haplo-abnormal loci. 3. Chromosome 3 contains one triplo-lethal locus that is also haplo-lethal, few or no other haplo-lethal loci, at least 16 Minute loci, and at least six other haplo-abnormal loci. 4. Chromosome 4 contains no triplo-lethal loci, no haplo-lethal loci, one Minute locus, and no other haplo-abnormal loci.—Thus, the Drosophila genome contains 57 loci, aneuploidy for which leads to a recognizable effect on the organism: one of these is triplo-lethal and haplo-lethal, one is triplo-abnormal and haplo-abnormal, one is hyperploid-sensitive, ten are haplo-abnormal, 41 are Minutes, and three are either haplo-lethals or Minutes. Because of the paucity of aneuploid-lethal loci, it may be concluded that the deleterious effects of aneuploidy are mostly the consequence of the additive effects of genes that are slightly sensitive to abnormal dosage. Moreover, except for the single triplo-lethal locus, the effects of hyperploidy are much less pronounced than those of the corresponding hypoploidy.
LACK OF DNA HOMOLOGY BETWEEN THE LEGUME GLYCINE MAX AND ITS SYMBIOTIC RHIZOBIUM BACTERIA
Authors: Rake Adrian V 
Published: January 2021

ABSTRACT
Any common genes of Glycine max and its symbiotic rhizobium bacteria 61A76 represent less than 0.6% of the bacterial genome. Thus, if any sizable exchange of DNA between host and symbiote occurs it must result in unstable DNA association which is lost with subsequent generations.
ON THE MECHANISM OF CHROMATIN LOSS INDUCED BY THE B CHROMOSOME OF MAIZE
Authors: Rhoades M M , Dempsey Ellen 
Published: January 2021

ABSTRACT
Knobbed regions of the regular maize complement frequently are eliminated at the second microspore division in spores which have two or more B chromosomes. Evidence is presented that no or little loss occurs in spores with one B and that the rate is not increased in spores with more than two B's.—The B chromosomes from an unrelated strain proved as effective in inducing loss as did the B's of the original high loss stock.—Chromatin loss induced by B's is restricted to knobbed A chromosomes and occurs only at the second microspore division. Knobbed chromosomes 3, 5, and 9 have been tested and all interact with B's to give loss. Chromosomes with large knobs are more frequently broken than are those with smaller knobs and knobless chromosomes show negligible loss.—Although knobs and B's are essential for chromatin elimination, modifying genes can markedly affect the rate of loss.——Two knobbed heterologous chromosomes undergo simultaneous loss more frequently than expected from independent events. The data indicate that joint loss occurs in competent cells and that preferential assortment of the two deficient chromosomes to specific poles is unlikely.—B chromosomes and deficient chromosomes assort independently at the second microspore anaphase.—Genetic data from crosses with marker genes in both arms of chromosome 3 show that breakage of the postulated dicentric bridge does not occur solely at the centric region since a variety of deficient chromosomes were recovered.—Nondisjunction of B chromosomes and elimination of knobbed chromatin take place during the second microspore mitosis. The argument is advanced that the two phenomena result from faulty replication of heterochromatic segments. The position of the nonreplicating segment in the two kinds of chromosomes determines whether nondisjunction or breakage takes place.—Finally, it is suggested that all of the reported effects of the B chromosome can be accounted for if the B is a parasitic entity having no genetic function other than controlling the replication of its proximal heterochromatic knob and increasing the ability of B-containing sperm cells to compete successfully for fertilization of the egg.
MESODERM-ECTODERM INTERACTION IN THE PRODUCTION OF THE AGOUTI PIGMENTATION PATTERN IN MICE
Authors: Mayer Thomas C , Fishbane Jill L 
Published: January 2021

ABSTRACT
Alleles at the agouti locus in the mouse determine the synthesis of either phaeomelanin or eumelanin by follicular melanocytes by altering the hair follicle environment. The method of dermal-epidermal recombination of mouse skin from C57BL/6J a/a and C57BL/6J Aw-J/Aw-J embryos was used in this study to establish the precise site of agouti gene action within the hair follicle. The pigmentary pattern of hairs formed in the recombination skin grafts was specific for the genotype of the dermal (mesodermal) component of the hair follicle. The genotype of the epidermal (ectodermal) component had no influence on the type of hair pigmentary pattern. These results indicate that future studies on gene mechanisms should focus on the dermis as the determining factor in altering the hair follicle environment.
TANDEM DUPLICATIONS OF THE rII REGION OF BACTERIOPHAGE T4D
Authors: Parma David H , Ingraham Laura J , Snyder Marlene 
Published: January 2021

Abstract
Genetic analyses of ten duplication strains of bacteriophage T4D isolated from an rJ101 × rl589 cross reveal that all ten duplications segregate structurally normal chromosomes (r segregants); six of the duplications have been shown to segregate inviable particles, presumed triplications, with the same frequency that they yield r segregants; viable triplication segregants have been isolated from four of the duplications; the rII region from the r1589 parent maps to the left of that from the rJ101 parent in nine of the duplications, while the tenth exhibits the reverse order. These observations are consistent with the hypothesis that the duplications are tandem duplications of a portion of the genome which includes the rII region. The evidence for triplications segregated from the duplications is not readily compatible with stabilized terminal redundancies as the basis of the duplications. Evidence is presented that the length of the duplication is compensated by a deletion of non-essential information elsewhere in the phage genome.
FECUNDITY AND LONGEVITY OF F1 FEMALES OF HABROBRACON FROM SPERM X-RAYED WITH 3000r
Authors: Heidenthal Gertrude , Nelson Wayne , Clark Leonard 
Published: January 2021

Abstract
Our purpose was to compare with respect to fecundity and longevity two groups of F1 diploid virgins of Habrobracon the fathers of which had been X-rayed with 3000r. Sorting of wasps into two groups was based on low or high hatchability of their F2 haploid eggs. Wasps with low hatchability (below 60%) are heterozygous for induced embryonic lethals such as recessives and translocations; wasps with high hatchability (100–60%) are free of lethals or possibly heterozygous for mild detrimentals. The F1s showing high hatchability laid significantly more eggs on the average; the average difference in lifespan was almost statistically significant (7% level). A more sensitive analysis by regression indicated a highly significant linear regression of survival of all F1s on hatchability of their eggs: F1s whose eggs showed 100% hatchability lived 1.84 days longer on the average than those whose eggs showed no hatchability. Furthermore, the former laid 4.99 more eggs on the average than the latter. The data also showed a very highly significant positive correlation coefficient between eggs laid and survival of mothers (0.122***) and a very highly significant positive partial correlation coefficient (0.105***) with hatchability held constant. The latter indicates that the F1s which laid more eggs also live longer, regardless of the hatchability of their eggs and hence of the heterozygosity of the mothers for lethals and other detrimentals.
SALMONELLA TYPHIMURIUM-ESCHERICHIA COLI HYBRIDS FOR THE TRYPTOPHAN REGION
Authors: Mojica-A T , Middleton R B 
Published: January 2021

ABSTRACT
Fifty-eight hybrids were analyzed for their phenotypic stability, presence and nature of cryptic trp alleles and by P22-mediated transduction to yield percent homologies. The hybrids fall into 5 distinguishable classes: a haploid class in which selected E. coli genes replace equivalent sites in the S. typhimurium chromosome; three merodiploid classes in which the selected E. coli genes are integrated at novel sites in the S. typhimurium chromosome—on the same transducing fragment as the female genes selected against, with or without cryptic damage to a nearby gene, or not on the same transducing fragment; and one class in which recombination has not taken place and the E. coli DNA is presumed to be an exogenote. The homology values are heterogeneous and do not permit an accurate determination of the relative frequency of incorporation of the integrated male genetic material. A further study of 20 hybrids indicates that genetic rearrangements can occur in the hybrids.
CHROMOSOMAL RECOMBINATION IN HAEMOPHILUS INFLUENZAE
Authors: Stuy Johan H , Hoffmann Joan F , Duket Lea H 
Published: January 2021

ABSTRACT
Haemophilus influenzae cultures doubly lysogenic for defective phage HP1, with a prophage marker sequence +b+/a+c, always contained some free wild-type phage. Single ultraviolet-irradiated cells produced either no wild-type phage or large numbers of them. This suggested that the phage was not released by the original double lysogen but by internal recombinants, i.e., by double lysogens with altered prophage marker sequence such as +++/abc or +b+/++c. Thirty-one wild-type phage-producing clones have been isolated independently from cultures of this double lysogen and identified. They fell in five classes. Two classes, still possessing all three prophage markers, can be explained by Campbell's (1963) prophage recombination model. The other classes had lost one or more markers. They can be explained by interchromosomal double-strand DNA breakage and rejoining. A single-DNA-strand gene conversion model is discussed in view of the fact that genetic transformation involves single-DNA-strand exchanges. A number of potentially interesting mutants has been analyzed of which only the derivatives of rec1 mutant DB117 (obtained from Dr. J. Setlow) were incapable of internal recombination.
PRELIMINARY CHARACTERIZATION OF "SEX RATIO" AND REDISCOVERY AND REINTERPRETATION OF "MALE SEX RATIO" IN DROSOPHILA AFFINIS
Authors: Voelker Robert A 
Published: January 2021

ABSTRACT
In D. affinis "sex ratio" (sr), a form of meiotic drive characterized by the production of mostly or only female progeny by certain males, is associated with two different X chromosome sequences, XS-I XL-II and XS-II XL-IV. The behavior of the two sequences differed, depending on the Y chromosome constitution, being either Y L or 0. Males with sequence XS-II XL-IV and Y L produced progenies with nearly normal sex ratios; males with the same X chromosome sequence but in the absence of a Y chromosome in some cases gave progenies with nearly normal sex ratios but in other cases gave progenies which tended toward phenotypic sr. Males with sequence XS-I XL-II and Y L gave progenies which were characteristically sr (0.97–0.98 females); in the absence of a Y chromosome males with this sequence produced progenies which were virtually all-male. This latter finding is presumably identical to Novitski's (1947) "male sex ratio" (msr). The interpretation offered here attributes msr to an interaction between sr sequence XS-I XL-II and the 0 condition. A general consideration of the available data on sr in D. affinis is presented.
QUINACRINE FLUORESCENT CHROMOSOME ANALYSIS OF THE SNELL TRANSLOCATION IN THE MOUSE
Authors: Miller D A , Allderdice P W , Kouri R E , Dev V G , Grewal M S , Miller O J , Hutton J J 
Published: January 2021

ABSTRACT
The chromosomes involved in the T(2;4)Sn (formerly designated T(5;8) Sn) or Snell translocation in the mouse have been identified as numbers 2 and 4 by analysis of the fluorescent banding patterns of quinacrine mustard-stained chromosomes in primary cultures from heterozygous and homozygous embryos.