bluuebunny/crossref_metadata_2025 huggingface dataset:
A CLASS OF GENES AFFECTING B FACTOR-REGULATED DEVELOPMENT IN SCHIZOPHYLLUM COMMUNE
Authors: Dubovoy Celia
Published: April 2021

Twelve mutations affecting nuclear migration, a major developmental phase in Schizophyllum commune, display a complex pattern of complementation and recombination. They are expressed only when a genetic factor controlling this phase of development, the B incompatibility factor, is operative. All twelve mutations are linked to the B factor, nine in a cluster and three in distinct loci outside the cluster. A linear map cannot be constructed from the frequency of recombination. Complementation maps are not linear. There is little correlation between the complementation groups and the groups based on recombination. Many pairs of mutations that do not complement recombine with frequencies of 1.1% to 26.9%. The genes represented by the twelve mutations are located in a linked group of about 18 known genes involved in the specific phase of development controlled by the B factor.
AVIAN RIBOFLAVINURIA IX. QUALITATIVE ACTION OF A MUTANT GENE IN CHICKEN ON RIBOFLAVIN-BINDING PROTEIN SYNTHESIS
Authors: Hammer C H , Buss E G , Clagett C O
Published: April 2021

Laying chickens normally produce a riboflavin-binding protein (RBP) essential for the transfer of vitamin B2 to the egg. A mutant line of chickens (rdrd) is incapable of synthesizing functional RBP. The rdrd laying hens contain a component in the liver and the magnum of the oviduct which crossreacts with rabbit antiserum specific for RBP. No crossreacting material (CRM) was observed in eggs or blood of rdrd hens. CRM is absent in extracts of livers of rdrd males, but it can be induced in roosters of this genotype by estradiol. CRM appears to be less immunogenic on a weight basis than RBP, and it carries less net negative charge. No measurable riboflavin-binding capacity was found for newly isolated or degraded CRM.
COMPARATIVE AUTOSOMAL LINKAGE IN MAMMALS: GENETICS OF ESTERASES IN MUS MUSCULUS AND RATTUS NORVEGICUS
Authors: Womack James E , Sharp Mark
Published: April 2021

Recombination between Esterase-4 and Esterase-2 in the rat was not observed in 278 backcross offspring. Es-4 is thus included within the "esterase cluster" in Linkage group V. A new map of this region was constructed and the relationship of the four esterase loci was found to be: Es-4-(9.6 ± 1.6 cM)-Es-2, Es-4-(1.5 ± 0.7 cM)-Es-3. Homology of this region with a region of Linkage Group XVIII (Chromosome 8) of the mouse was proposed on the basis of tissue distribution, subcellular localization and response of enzymes to inhibitors. Specifically, rat Es-1 was suggested as the homolog of mouse Es-2, rat Es-2as the homolog of mouse Es-1, and rat Es-4 as the homolog of mouse Es-6. An autosomal segment comprising at least 15 cM of the rat and mouse genomes appears to have remained relatively intact with respect to genetic content during rodent speciation. In addition, a new polymorphism for mouse esterase was described. The locus was designated Esterase-10 (Es-10) and proposed as the mouse homolog of human Esterase D. Linkage of Es-10 with nucleoside phosphorylase-1 (Np-1) on Chromosome 14 was established.
GALACTOKINASE MUTANTS OF CHINESE HAMSTER SOMATIC CELLS RESISTANT TO 2-DEOXYGALACTOSE
Authors: Thirion Jean-Paul , Banville Denis , Noel Henri
Published: April 2021

The growth of Chinese hamster somatic cells was inhibited by 0.2 mg/cc of 2-deoxygalactose. Mutants partially or fully resistant to 2-deoxygalactose were isolated in a single-step or two-step selection. Some of them did not grow as well as the wild type; one of them which lacked galactokinase (EC.2.7.1.6) activity did not grow at all in galactose medium. The galactokinase kinetic properties (Vmax & Kmax) of the other mutants and of the wild type were different. Therefore resistance resulted either from the possible absence of galactokinase synthesis or from a structural mutation, possibly a missence mutation, in the galactokinase gene.—A simple diagnostic test for juvenile cataract is proposed.
EFFECT OF GENES CONTROLLING RADIATION SENSITIVITY ON CHEMICALLY INDUCED MUTATIONS IN SACCHAROMYCES CEREVISIAE
Authors: Prakash Louise
Published: April 2021

The effect of 16 different genes (rad) conferring radiation sensitivity on chemically induced reversion in the yeast Saccharomyces cerevisiae was determined. The site of reversion used was a well-defined chain initiation mutant mapping in the structural gene coding for iso-1-cytochrome c. High doses of EMS and HNO2 resulted in decreased reversion of cyc1-131 in rad6, rad9 and rad15 strains compared to the normal RAD+ strains. In addition, rad52 greatly decreased EMS reversion of cyc1-131 but had not effect on HNO2-induced reversion; rad18, on the other hand, increased HNO2-induced reversion but did not alter EMS-induced reversion. When NQO was used as the mutagen, every rad gene tested, except for rad14, had an effect on reversion; rad6, rad9, rad15, rad17, rad18, rad22, rev1, rev2 and rev3 lowered NQO reversion while rad1, rad2, rad3, rad4, rad10, rad12 and rad16 increased it compared to the RAD+ strain. The effect of rad genes on chemical mutagenesis is discussed in terms of their effect on UV mutagenesis. It is concluded that although the nature of the repair pathways may differ for UV- and chemically-induced mutations in yeast, a functional repair system is required for the induction of mutation by the chemical agents NQO, EMS and HNO2.
CHLOROPLAST GENETICS OF CHLAMYDOMONAS. III. CLOSING THE CIRCLE
Authors: Singer Burt , Sager Ruth , Ramanis Zenta
Published: April 2021

A novel mapping procedure is presented for organelle genes or any other genetic system exhibiting a measurable frequency of exchanges occurring at a constant rate over a measurable time interval. For a set of markers in a multiply-marked cross, the exchange rates measure relative map distances from a centromere-like attachment point.

With this method, we present mapping data and a linear map of genes in the chlcroplast genome of Chlamydomonas. The data are plotted as log (percent remaining heterozygotes) against time and map distances are taken as proportional to slope.

A statistical method which is an adaptation of jackknife methodology to a regression problem was developed to estimate slope values. A single line is fitted to pooled data for each marker from several crosses, and then lines are re-fit to a series of pooled data sets in each of which the observations from a single cross have been omitted. From these data sets a final summary slope is computed as well as a statement of its variability. The relative positions of new markers present in single crosses can then be estimated utilizing data from many crosses.

The method does not distinguish between one-armed and two-armed linear or circular maps. However, evaluation of this map in conjunction with cosegregation frequency data (Sager and Ramanis 1976b) provides unambiguous evidence of the genetic circularity of the Chlamydomonas chloroplast genome.
GENETIC CHANGE IN MUTATIONS AT THE T/t-LOCUS IN THE MOUSE
Authors: Bennett Dorothea , Dunn L C , Artzt Karen
Published: April 2021

Recessive lethal or semilethal alleles at the T/t locus in the mouse generate new t-variants, with characteristics different from the parent allele at a rate of about 10-3. Almost invariably the variant chromosome carries marker genes derived from the opposite parental chromosome. New t-mutations obtained in this way are sometimes recessive lethals that are indistinguishable from those in already known complementation groups. Most derived t-mutations are viable, however. This paper summarizes data on the rate and types of variants produced by members of each of the six lethal complementation groups, and by semilethal alleles. It appears that particular complementation groups preferentially generate certain types of variants, and that in general, the pattern of variant production runs "uphill," that is, to less abnormal states. The data are compatible with the hypothesis that t-mutations represent some extent of altered chromosome and that variants are produced by loss of abnormal material.
GROWTH RATE, BODY COMPOSITION, CELLULAR GROWTH AND ENZYME ACTIVITIES IN LINES OF TRIBOLIUM CASTANEUM SELECTED FOR 21-DAY PUPA WEIGHT
Authors: Medrano Juan F , Gall G A E
Published: April 2021

Growth rate, body composition, cell number, cell size, and the activity of four dehydrogenase enzymes were studied from 10 to 25 days of age in one control (1C) and three lines (3, 9, 10) of Tribolium castaneumthat had been subjected to long term selection for large 21-day pupae weight.—Selected lines were two- to three-fold larger in size than the control line throughout development. No major differences in percent of protein were detected among the lines but at any particular age, the selected lines were found to have a higher fat content than the control line. The differences in fat content were closely correlated with development such that all the lines reached very similar levels of percent of fat just prior to pupation. Water content showed an inverse relation to percent of fat.—Selection was observed to have caused major changes in the cellular response to growth. The selected lines had an average of from 17% to 48% larger cells (measured as protein/DNA) and were found to have from 37 to 62% more cells (measured as total DNA) than the control line at all ages from 10 to 19 days of age. In addition, the selected lines had a higher RNA content at all ages studied and higher RNA:DNA ratios at the young ages. In contrast the enzyme activities of ICDH and LDH were 60% lower. The results are interpreted as indicating that a more efficient metabolic machinery had evolved in the rapidly growing selected lines.
HIGH RATES OF OCCURRENCE OF SPONTANEOUS CHROMOSOME ABERRATIONS IN DROSOPHILA MELANOGASTER
Authors: Yamaguchi Osamu , Cardellino Ricardo A , Mukai Terumi
Published: April 2021

Spontaneous mutations were accumulated for 40 generations in 140 unrelated second chromosomes with the standard gene arrangement. These were extracted from the same population by using the marked inversion technique, and the following findings were obtained: (1) In 42 out of the 140 chromosome lines, chromosome aberrations were detected by examining the salivary gland chromosomes: 40 paracentric and 15 pericentric inversions, 2 reciprocal translocations between the second and the third chromosomes, and 6 transpositions. (2) In 63 out of the 90 originally lethal-free lines, recessive lethal mutations occurred. (3) There were only 3 lines that acquired chromosome aberrations (inversions) with no lethal effects in the homozygous condition. (4) In a comparison of these results with those of the (CH), (PQ), and (RT) chromosomes in which no chromosome aberrations occurred after accumulating mutations for 22058 chromosome·generations (Yamaguchi and Mukai 1974), it was concluded that some of these 140 chromosomes carried a kind of mutator. (5) The frequency of mutator-carrying chromosome lines was estimated to be 0.66 on the basis of the distribution of the break-points on the chromosome lines and the frequency of lines that acquired neither recessive lethal mutations nor chromosome aberrations. Thus, the average number of breaks per mutator-carrying chromosome was estimated to be about 0.19/generation.

On the basis of these estimates, the nature of the mutator factor was discussed.
INDUCIBLE MONOOXYGENASE ACTIVITIES AND 3-METHYLCHOLANTHRENE-INITIATED TUMORIGENESIS IN MOUSE RECOMBINANT INBRED SUBLINES
Authors: Atlas Steven A , Taylor Benjamin A , Diwan Bhalchandra A , Nebert Daniel W
Published: April 2021

The induction of a certain group of hepatic monooxygenase activities by polycyclic aromatic compounds is regulated by the same locus or gene cluster controlling the formation of cytochrome P1–450 (P–448) in mice. Certain inbred strains of mice are "responsive" (Ahb) to such induction, whereas others are "nonresponsive" (Ahd). A pair of closely related sublines that differ with respect to the Ahlocus (for aromatic hydrocarbon responsiveness) were used to identify or confirm the pleiotropic effects of this gene. The lines were derived by sibling-mating without selection from (C57L/J × AKR/J)F2 mice; the two sublines were separated at the F12 generation. Ten microsomal monooxygenase activities and one cytosol enzyme activity known to be associated with the Ah locus were similarly associated with cytochrome P1–450 formation in these recombinant inbred sublines as well. Nine additional hepatic monooxygenase activities studied were found not to be associated with the Ah locus; certain of these activities were increased slightly, following treatment of nonresponsive as well as responsive mice with polycyclic aromatic compounds. The Ahb-containing subline was highly susceptible to 3-methylcholanthrene-induced subcutaneous sarcomas, whereas the Ah-d-containing subline was relatively resistant. These results emphasize the potential importance of this particular enzyme for the study of coordinated regulation in mammals.
GENE EXPRESSION IN ALLOPLOIDS: GENETIC CONTROL OF LIPOPUROTHIONINS IN WHEAT
Authors: De Caleya R Fernandez , Hernandez-Lucas C , Carbonero Pilar , Garcia-Olmedo F
Published: April 2021

Lipopurothionins are complexes of basic polypeptides and polar lipids found in petroleum ether extracts of wheat endosperm. Location of the structural genes for the protein moiety and of genes probably controlling the lipid moiety has been achieved by analysis of compensated nulli-tetrasomic and ditelosomic lines of Triticum aestivum L. cv. Chinese Spring, as well as of other genetic stocks. There are two electrophoretic variants of the apoprotein designated α and β purothionins. Structural genes for α purothionins are located in the long arm of chromosomes 1B and 1D, and for the β variant in the long arm of 1A. These genes have been tentatively designated Pur-A1, Pur-B1, and Pur-D1. The aminoacid composition of purified α and β purothionins from Triticum aestivum (genomes AABBDD) and T. durum (AABB), and of β purothionin from T. monococcum (AA) is also consistent with this conclusion and suggests that the α purothionin encoded by gene Pur-B1 probably differs from that encoded by gene Pur-D1 in at least three positions of the aminoacid sequence. A gene (or genes) located in the short arm of chromosome 5D markedly affects the level of lipopurothionin but does not affect apoprotein synthesis. It is concluded that they control the lipid moiety which is required for solubility in petroleum ether.
Q- AND C-BAND CHROMOSOME MARKERS IN INBRED STRAINS OF MUS MUSCULUS
Authors: Miller D A , Tantravahi R , Dev V G , Miller O J
Published: April 2021

Differences in the number of chromosomes with secondary constrictions and in the size of the C-band region on certain chromosomes have been observed among the following inbred strains of Mus musculus: C57BL/10J, C57BR/cdJ, DBA/1J, CBA/J, BALB/cJ, and AKR. These differences are useful as indicators of the location of rRNA genes and as normal chromosome markers. The size of each C-band region appears to remain constant over many generations. Only one probable change in the size of a C-band region was found.
REGULATION OF PHOSPHATE METABOLISM IN NEUROSPORA CRASSA: IDENTIFICATION OF THE STRUCTURAL GENE FOR REPRESSIBLE ALKALINE PHOSPHATASE
Authors: Lehman John F , Metzenberg Robert L
Published: April 2021

Five additional mutants of Neurospora crassa have been isolated that lack the repressible alkaline phosphatase. The mutations in these strains map at a previously assigned locus on Linkage Group V designated pho-2 (Gleason and Metzenberg 1974). The five new mutants, as well as three previously isolated by Gleason and Metzenberg (1974), were examined for the presence of cross-reacting material to antibody prepared against purified wild-type enzyme. Two of the mutants produced high levels of cross-reacting material, thus providing evidence that the pho-2 locus includes the structural gene for the repressible alkaline phosphatase. Two revertants were obtained from one of the mutants that contained cross-reacting material. Neither revertant produced an enzyme that could be distinguished physicochemically from that of wild type. A method for measuring very low levels of repressible alkaline phosphatase in crude extracts is also described.
HETEROZYGOUS EFFECTS OF IRRADIATED CHROMOSOMES ON VIABILITY IN DROSOPHILA MELANOGASTER
Authors: Simmons Michael J
Published: April 2021

Two large experiments were conducted in order to evaluate the heterozygous effects of irradiated chromosomes on viability. Mutations were accumulated on several hundred second chromosomes by delivering doses of 2,500r over either two or four generations for total X-ray exposures of 5,000r or 10,000r. Chromosomes treated with 5,000r were screened for lethals after the first treatment, and surviving nonlethals were used to generate families of fully treated chromosomes. The members of these families shared the effects of the first irradiation, but differed with respect to those of the second. The chromosomes treated with 10,000r were not grouped into families since mutations were accumulated independently on each chromosome in that experiment. Heterozygous effects on viability of the irradiated chromosomes were tested in both isogenic (homozygous) and nonisogenic (heterozygous) genetic backgrounds. In conjunction with these tests, homozygous viabilities were determined by the marked-inversion technique. This permitted a separation of the irradiated chromosomes into those which were drastic when made homozygous and those which were not. The results indicate that drastic chromosomes have deleterious effects in heterozygous condition, since viability was reduced by 2-4% in tests performed with the 10,000r chromosomes, and by 1% in those involving the 5,000r material. Within a series of tests, the effects were more pronounced when the genetic background was homozygous. Nondrastic irradiated chromosomes did not show detectable heterozygous effects. They also showed no homozygous effects when compared to a sample of untreated controls. In addition, there was no evidence for an induced genetic component of variance with respect to viability in these chromosomes. These results suggest that the mutants induced by high doses of X-rays are principally drastic ones which show deleterious effects on viability in heterozygous condition.
HIDDEN GENETIC VARIABILITY WITHIN ELECTROMORPHS IN FINITE POPULATIONS
Authors: Chakraborty Ranajit , Nei Masatoshi
Published: April 2021

The amount of hidden genetic variability within electromorphs in finite populations is studied by using the infinite site model and stepwise mutation model simultaneously. A formula is developed for the bivariate probability generating function for the number of codon differences and the number of electromorph state differences between two randomly chosen cistrons. Using this formula, the distribution as well as the mean and variance of the number of codon differences between two identical or nonidentical electromorphs are studied. The distribution of the number of codon differences between two randomly chosen identical electromorphs is similar to the geometric distribution but more leptokurtic. Studies are also made on the number of codon differences between two electromorphs chosen at random one from each of two populations which have been separated for an arbitrary number of generations. It is shown that the amount of hidden genetic variability is very large if the product of effective population size and mutation rate is large.
THE FREQUENCY AND ALLELISM OF LETHAL CHROMOSOMES IN ISOLATED DESERT POPULATIONS OF DROSOPHILA PSEUDOOBSCURA
Authors: Bryant Stephen H
Published: April 2021

Second-chromosome lethals were extracted from four populations of Drosophila pseudoobscura in Southern California. Two of the populations were from desert oases and two from the classic habitat on Mt. San Jacinto, previously studied by Dobzhansky. Allelism tests were made on the lethals within and between all locations. The frequency of lethal second-chromosomes in each location was 0.18, and this was not different from the results of other workers for samples throughout the species range. Interpopulational allelism rates were about 0.005, and not different from earlier results of Dobzhansky. Intrapopulational rates in this study were, with one exception, the same as the interpopulational rates, and significantly lower than Dobzhansky found using the third chromosome. This may be due to lethals being linked with heterotic third-chromosome inversions. The allelism rate of the exceptional population (about 0.03 and equal to Dobzhansky's intrapopulational results) may be due to heterotic lethals, or a founder effect. Two lethals were found in three populations each, possibly due to migration among these populations, which are up to 334 km apart.
GENE DIFFERENCES BETWEEN THIRD-CHROMOSOME INVERSIONS OF DROSOPHILA PSEUDOOBSCURA
Authors: Prakash Satya
Published: April 2021

Associations of alleles of the acid phosphatase-3 locus with the different third-chromosome inversions from different populations of D. pseudoobscura are described. We observe only the allele AP-31.0 in the Standard and Arrow-head inversions and the allele AP-3.98 in the Santa Cruz, Treeline, Cuernavaca and the Pikes Peak arrangements. The Chiricahua gene arrangement is polymorphic.
THE NATURE OF QUANTITATIVE GENETIC VARIATION IN DROSOPHILA. III. MECHANISM OF DOSAGE COMPENSATION FOR SEX-LINKED ABDOMINAL BRISTLE POLYGENES
Authors: Frankham R
Published: April 2021

Seventeen lines, each homozygous for a different × chromosome but all with a common autosomal genetic background, were constructed and assayed for abdominal bristle number to determine whether dosage compensation operates for sex-linked genes affecting this character.—The regression coefficient of male mean on female mean using a logarithmic scale was 0.90 ± 0.13 and the genetic regression coefficient 0.92, neither differing significantly from unity. The genetic components of variance in males and females were also very similar (0.000234 or 0.000228, respectively). These results indicate that dosage compensation is complete (or nearly so) for sex-linked genes affecting this character. The bristle scores of females did not differ in reciprocal crosses between these lines, thus dosage compensation does not operate by paternal × inactivation.—The question of an adequate scale for abdominal bristle number had to be examined during the study. A logarithmic scale appeared to be adequate for both genotypic and environmental differences.
PROTEINASE MUTANTS OF SACCHAROMYCES CEREVISIAE
Authors: Jones Elizabeth W
Published: April 2021

Fifty-nine mutants with reduced ability to cleave the chymotrypsin substrate N-acetyl-DL-phenylalanine β-naphthyl ester have been isolated in S. cerevisiae. All have reduced levels of one or more of the three well-characterized proteinases in yeast. All have reduced levels of proteinase C (carboxy-peptidase Y). These mutations define 16 complementation groups.
CHROMOSOMAL POLYMORPHISMS OF CONSTITUTIVE HETEROCHROMATIN AND INVERSIONS IN DROSOPHILA
Authors: Baimai Visut
Published: April 2021

A simple technique for preparing mitotic metaphases from a larval ganglion of Drosophila is described. Parallel examination of polytene and metaphase chromosome groups shows that inversion polymorphism in chromosome 3 of D. recticilia from East Maui (Hawaii) manifests a one-to-one correlation with a metaphase karyotype polymorphism due to the presence of an extra heterochromatic portion. These observations are consistent with the previous findings on other species of Hawaiian Drosophila. They strongly support the hypothesis that when one breakpoint of a long inverted segment of a chromosome element occurs in the vicinity of the constitutive heterochromatin, it may exert an effect in eliciting the production of heterochromatic material in the same chromosome.
VARIANCE OF GENE FREQUENCIES FROM RECURRENT SELECTION IN FINITE POPULATIONS
Authors: Park Young Chul
Published: April 2021

An equation was derived for estimation of the variance of gene frequencies due to drift in the presence of recurrent selection. The equation assumes knowledge of gene frequencies in successive generations. These can be approximated in at least three ways. Simulation data demonstrated that when satisfactory approximations are used, the variances supplied by the derived formula agree well with observed variances.
INBREEDING ESTIMATION FROM POPULATION DATA: MODELS, PROCEDURES AND IMPLICATIONS
Authors: Spielman Richard S , Neel James V , Li Francis H F
Published: April 2021

Four different estimation procedures for models of population structure are compared. The parameters of the models are shown to be equivalent and, in most cases, easily expressed in terms of the parameters Wright calls "F-statistics." We have estimated the parameters of each of these models with data on nine codominant allele pairs in 47 Yanomama villages, and we find that the different estimators for a given parameter all yield more or less equivalent results.

F-statistics are often equated to inbreeding coefficients that are defined as the probability of identity by descent from alleles taken to be unique in some founding population. However, we are led to infer from computer simulation and general historical considerations that all estimates from genotype frequencies greatly underestimate the inbreeding coefficient for alleles in the founding population of American Indians in the western hemisphere. We surmise that in the highly subdivided tribal populations which prevailed until the recent advent of civilization, the probability of identity by descent for homologous alleles was roughly 0.5. We consider some consequences of working with the customary, much lower, estimates—0.005 to 0.01—if, on the time scale of human evolution, these represent only a very recent departure from the inbreeding intensity that prevailed before civilization.
A CYTOGENETIC ANALYSIS OF CYCLIC NUCLEOTIDE PHOSPHODIESTERASE ACTIVITIES IN DROSOPHILA
Authors: Kiger John A , Golanty Eric
Published: April 2021

The genome of Drosophila melanogaster has been surveyed for chromosomal regions which exert a dosage effect on the activities of cAMP phosphodiesterase or cGMP phosphodiesterase. Two regions increase cAMP phosphodiesterase activity when present as duplications. A region of the X chromosome increases cAMP phosphodiesterase activity when duplicated and decreases that activity when deficient. This region has been delimited to chromomeres 3D3 and 3D4, with 3D4 being the most probable locus, and may contain a structural gene for cAMP phosphodiesterase. A region on the third chromosome, 90E-91B, increase cAMP phosphodiesterase activity when duplicated but has no affect on the activity when deficient. Two regions increase cGMP phosphodiesterase activity when present as duplications. A region of the X chromosome, 5D-9C, increases cGMP phosphodiesterase activity when duplicated, but smaller duplications covering this region fail to show such an increase, indicating that a single locus is not responsible for the increase observed for the larger duplication. A region of the third chromosome, 88C-91B, also increases cGMP phosphodiesterase activity when duplicated. Smaller duplications covering this region show smaller increases than that observed for the larger duplication, suggesting that at least three loci between 88C and 91B contribute to the observed increase by that region. Deficiencies covering region 88C-91B do not affect cGMP phosphodiesterase activity. No locus for a presumptive structural gene for cGMP phosphodiesterase has been found. Limitations of the use of segmental aneuploidy in locating structural genes for enzymes are discussed.
CORRELATIONS BETWEEN CHROMOSOME SEGMENTS AND FITNESS IN DROSOPHILA MELANOGASTER. I. THE X CHROMOSOME AND EGG PRODUCTION
Authors: Chapco William
Published: April 2021

Unmarked segments within the X chromosomes of four different Drosophila melanogaster isogenic lines were assessed with respect to egg production. By making a series of crosses among original and derived recombinant lines, it was possible to estimate parameters representing additive, dominance and interaction effects of the segments. It was shown that whereas most of the segments were additive for egg production when homozygous, they all displayed dominance in the heterozygous condition. Two of the strains were characterized by intersegmental interaction. A possible position effect was detected for these same two strains, with flies in the coupling phase laying more eggs than those in the repulsion configuration. There was no apparent relationship between the number of eggs laid and the amount of heterozygosity within the X chromosome.
MATERNAL INHERITANCE OF ENZYMES IN THE MEALYBUG PSEUDOCOCCUS OBSCURUS (HOMOPTERA)
Authors: Nur Uzi
Published: April 2021

In the mealybug Pseudococcus obscurus Essig (Pseudococcidae) two esterases, a tyrosinase and a mannosephosphate isomerase, exhibited an unusual type of maternal inheritance. Electromorphs (alleles) were transmitted by both parents but segregation was delayed by one generation and full sisters always had the same phenotype. Moreover, for esterase-1, in which three alleles were present, some of the females exhibited all three alleles. Several other polymorphic loci exhibited normal transmission and segregation. This mode of inheritance can be readily explained by assuming that most or all of the enzymes coded for by these loci are produced by the mycetocytes. The mycetocytes house intracellular bacteria-like symbionts and are usually formed by the fusion of the polar bodies and one or more cleavage nuclei. For a locus with two alleles exhibiting this type of inheritance, the expected frequencies of the three phenotypes are p  3, 3pq and q  3. An equation is presented for estimating the frequency of alleles from the frequencies of the phenotypes and it is shown that for three samples from wild populations there is a good agreement between the expected and observed frequencies of the phenotypes.
MULTIPLE INTERACTIONS OF A DNA-BINDING PROTEIN IN VIVO. III. PHAGE T4 GENE-32 MUTATIONS DIFFERENTIALLY AFFECT INSERTION-TYPE RECOMBINATION AND MEMBRANE PROPERTIES
Authors: Mosig Gisela , Berquist William , Bock Susan
Published: April 2021

We have investigated the in vivo roles of T4 gene-32 protein in recombination. We have studied the effects of gene-32 mutations under conditions that allow normal DNA replication and are permissive for progeny production. Under these conditions, certain gene- 32 mutations specifically reduce insertion-type (short-interval) recombination but none affect crossover-type (long-interval) recombination (see Figure 5). Heterozygote frequencies in all gene-32 mutants are similar to or higher than in a gene-32  + background and are not correlated with recombination deficiencies. "Recombination-deficient" alleles are dominant or codominant over the "recombination-proficient" gene-32 mutation tsL171. This explains apparent discrepancies between a gene-32 map deduced from two-factor crosses and the map derived from three-factor crosses.

We have also found that the "recombination proficient" mutation tsL171 and its homoalleles suppress the characteristic plaque morphology of rll mutants. Under restrictive conditions, tsL171 is partially suppressed by rll mutations, which allow the use of host ligase in recombination.

Our present and previous results are discussed in terms of current recombination models. We conclude that gene-32 protein functions in recombination by forming a complex with DNA, with recombination enzymes and with membrane components. Since gene-32 protein interacts with many components of this recombination complex, gene-32 mutations may differentially affect various recombination steps.
INHERITANCE OF THE 2μm DNA PLASMID FROM SACCHAROMYCES
Authors: Livingston Dennis M
Published: April 2021

A variety of Saccharomyces strains were examined for the presence of 2µ DNA and, if present, for the pattern of fragments produced by its digestion with site-specific (restriction) endonucleases. Two strains were found that did not contain detectable levels of 2µ DNA, and two strains contained 2µ DNA molecules having only one EcoRI restriction endonuclease recognition site rather than the usual two.—A haploid containing 2µ DNA with one EcoRI restriction site was mated with a haploid containing 2µ DNA with two EcoRI restriction sites and the resulting diploid maintained both types during vegetative growth. Sporulation of the diploid produced four spores, and the clones from these spores contained both types.—A haploid lacking 2µ DNA was mated with a haploid containing 2µ DNA and the resulting diploid contained 2µ DNA. The four clones derived from the haploid spores after sporulation of this diploid all contained 2µ DNA. A rho  - strain without 2µ DNA was mated to a rho  + strain with 2µ DNA, and heteroplasmons were selected that had received the nucleus from the strain without 2µ DNA and the mitochondria from the strain with 2µ DNA. Twelve of twenty-four such clones contained 2µ DNA.—I conclude that: (1) the different types of 2µ DNA identified in these strains do not restrict one another, (2) the different types are inherited extrachromosomally, (3) lack of 2µ DNA in two strains is not due to the absence of genes needed for maintenance and (4) the approximately 100 copies of 2µ DNA contained within a single cell are probably clustered within one or a few cytoplasmic organelles.
EVIDENCE FOR DUPLICATION AND DIVERGENCE OF THE STRUCTURAL GENE FOR PHOSPHOGLUCOISOMERASE IN DIPLOID SPECIES OF CLARKIA
Authors: Gottlieb L D
Published: April 2021

Formal genetic analysis of the mode of inheritance of the electrophoretic phenotypes for phosphoglucoisomerase (PGI) in the annual plants Clarkia rubicunda and C. xantiana showed that these diploid species have two and three genes, respectively, that specify PGI subunits. Electrophoretic examination of seven other diploid species of Clarkia revealed that species assigned to ancestral sections in the current taxonomy have two PGI genes, whereas more specialized species have three PGI genes. Together with evidence that diploid species in two closely related genera have two PGI genes, this suggests the third PGI gene arose within Clarkia. Intergenic heterodimers are formed between polypeptides specified by the third gene and one of the other PGI genes, indicating they have a high degree of structural similarity. The combined genetic, biochemical, and phylogenetic evidence suggests that the third PGI gene resulted from a process of gene duplication. The apparent Michaelis constants (F6P to G6P) of the most common electrophoretic variants of the ancestral gene in C. xantiana and in C. rubicunda are closely similar, but that of the duplicate enzyme is much higher. The intergenic heteromer has an intermediate value. Four alleles have been identified for the duplicate PGI gene in C. xantiana, including a null allele which eliminates the activity of its product. This allele is one of the few examples of a "silenced" duplicate gene. The ancestral and duplicate genes assort independently in C. xantiana. In conjunction with the substantial chromosomal rearrangements that characterize species of Clarkia, this may mean that the duplicate PGI marks a duplicated chromosomal segment that originated from a cross between partially overlapping reciprocal translocations rather than from unequal crossing over.
NUCLEOLUS ORGANIZERS IN MUS MUSCULUS SUBSPECIES AND IN THE RAG MOUSE CELL LINE
Authors: Dev V G , Tantravahi R , Miller D A , Miller O J
Published: April 2021

Silver staining has been used to detect active nucleolus organizer regions (NOR's). By this criterion six mouse chromosomes, numbers 12, 15, 16, 17, 18 and 19, can have an NOR. The number and distribution of chromosomes with NOR's vary among inbred strains of Mus musculus musculus (C57BL/6J, BALB/cJ, C3H/HeJ and C3H/StCr1BR) and in M. musculus molossinus. In a musculus x molossinus F1 hybrid, nucleolus organizers from each parent are silver stained.—Chromosomes which have NOR's in diploid cells also show them in tetraploid cells and in established cell lines. The BALB/cJ strain shows Ag-staining of NOR's on chromosomes 12, 15, 18 and occasionally 16. In the RAG cell line, which was derived from BALB/c, active NOR's are seen on 12, 15 and 18, even after these chromosomes have undergone structural rearrangements in the cell line. Some correlation exists between the amount of Ag-stain and the size of a secondary construction region, with a large amount of Ag-stain present on a chromosome which has a prominent secondary constriction. There is no correlation between the amount of Ag-stain and the presence or absence of C-band material.
THE EFFECTS OF GENOTYPIC FREQUENCY AND POPULATION DENSITY ON FITNESS DIFFERENTIALS IN ESCHERICHIA COLI
Authors: Smouse Peter , Kosuda Kazuhiko
Published: April 2021

Two strains of Escherichia coli K-12, a lac  + wild type and a lac  - auxotroph, were grown both as pure and mixed cultures, using a serial transfer procedure. Four different growth media were employed, consisting of the same minimal salts solution, but different total concentrations of the sugars lactose, arabinose, and glucose (in proportions 5:4:1). Population densities and genotypic frequencies were assayed every 48 hours, at the time of transfer. Population density of the pure lac  + culture was greater than that of the pure lac  - culture for all media; this was expected, since the latter cannot utilize lactose. Mixed cultures quickly approached the same density as the corresponding lac  + controls, and the frequency of the lac  + genotype increased steadily for all media. Trajectories of Λ = log (P ÷ Q) were strictly nonlinear, indicating a dependence of the selective differential on population density and genotypic frequency. The rate of substitution decreased slightly with increasing sugar concentration, contrary to theoretical expectation. It was speculated that either the generation interval was longer for denser cultures (higher substrate concentrations) or that buildup of organic by-products reduced the selective differential in denser cultures. For a single medium, however, the behavior of competing genotypic strains was reasonably well predicted by theoretical models of frequency and density-dependent selection, the parameters of which may be related to the experimental inputs.
CHARACTERIZATION OF SALMONELLA TYPHIMURIUM MUTANTS WITH ALTERED GLUTAMINE SYNTHETASE ACTIVITY
Authors: Funanage Vicky L , Brenchley Jean E
Published: April 2021

A number of glutamine auxotrophs of Salmonella typhimurium were isolated and characterized genetically. Three of the mutations appear to be closely linked and are complemented by episomes carrying the glnA region of Escherichia coli. The lesions in these strains are approximately 20% linked by P1 transduction with a mutation in the rha gene, but are unlinked to ilv. Another mutation causing glutamine auxotrophy in strain JB674 is genetically distinct from the others. Strain JB674 grown in glucose medium containing ammonia as the nitrogen source has reduced levels of glutamine synthetase that is more adenylylated than in the parent strain, suggesting that the enzyme can not be deadenylylated normally. The lesion causing glutamine auxotrophy in JB674 lies in the region corresponding to the glnB and glnE genes affecting glutamine synthetase modification in Klebsiella areogenes. Four Gln+ revertants of JB674 have glutamine synthetase activities 4 to 6 fold higher than normal. One mutation causing this increased enzyme synthesis has been shown by three-factor crosses with the glnA mutations to lie near or within the glnA gene.
VIRUS-LIKE PARTICLES IN USTILAGO MAYDIS: MUTANTS WITH PARTIAL GENOMES
Authors: Koltin Yigal
Published: April 2021

Mutants with partial genomes for the virus-like particles of U. maydis were recovered following treatment with nitrosoguanidine. Examination of the properties retained by progeny of genetic crosses indicates that the 2.9 × 106 dalton component of double-stranded RNA contains the information for capsid formation and dsRNA replication. Other components appear to contain the information for killer function and immunity to killer. The use of such mutants for studies on the evolution of viruses with segmented genomes is discussed.
EVIDENCE FOR A SET OF CLOSELY LINKED AUTOSOMAL GENES THAT INTERACT WITH SEX-CHROMOSOME HETEROCHROMATIN IN DROSOPHILA MELANOGASTER
Authors: Sandler L
Published: April 2021

It is proposed that there exists a special region in the euchromatin of the left arm of chromosome 2 (contained within sections 31-32 of the standard salivary gland chromosome map) that is defined by a set of genes, each one of which interacts with a specific sex-chromosome heterochromatic segment. The evidence for the existence of this region is, first, the exhibition, mapping, and analysis of five different maternal-effect, embryonic semi-lethals located in region 31-32. Secondly, in each case the consequence of the maternal effect is markedly influenced by the amount of X- or Y-chromosome heterochromatin carried by the progeny of mutant mothers. The nature of this interaction and possible reasons for the existence of the cluster of autosomal genes are discussed
Is the Use of Routine Echocardiograms Warranted in Large Pediatric Burns?
Authors: Wilmot Ivan , Chang Philip , Fowler Laura , Warner Petra
Published: April 2021

Cardiac dysfunction can develop in large pediatric burns during the acute and recovery phase. When occurring in this population, the cardiac abnormality appears as left ventricular dysfunction or dilated cardiomyopathy. Recent studies have demonstrated perioperative and long-term cardiac dysfunction resulting in longer hospital stays for patients over 40% total body surface area. The objective of this study was to assess if early use of echocardiograms in large burns would allow for early recognition of patients at risk for cardiac dysfunction. Pediatric burn patients ages 0 to 18 years who sustained a burn injury of 30% TBSA or more or developed cardiac dysfunction during hospital course were evaluated. Echocardiograms were obtained upon admission with monthly repeats until three normal studies were attained or the patient was discharged and when symptomatic. Of the 130 acute burn patients admitted during 7/2017 to 10/2018, 10 patients met criteria for enrollment in this study. The average age was 5 years (0.8–10 years), 70% were males and 90% sustained flame injuries.Total TBSA average was 45% (24–70%) with average full-thickness burns of 33% (0–67%). Twenty echocardiogram studies were obtained. One patient with 25% TBSA burn, demonstrated severe left ventricular dysfunction with an ejection fraction (EF) of 25% from post-arrest myocardial stunning. Repeat echocardiogram studies demonstrated full recovery with normal EF. The remaining patients, despite large TBSA injuries, did not exhibit any abnormalities on echocardiogram examinations. No cardiac interventions were required. Use of echocardiograms is best performed on symptomatic burn patient populations.
Age Is Just a Number: Considerations for Older Adults in Cancer Clinical Trials
Authors: Habr Dany , McRoy Lynn , Papadimitrakopoulou Vassiliki A
Published: April 2021

Older adults continue to be underrepresented in cancer clinical trials, despite most cancer occurrence peaking in the later decades of life. Consequently, diagnostic and management strategies are commonly extrapolated from data on younger patients, thus challenging the delivery of informed cancer care in this patient population. Several recommendations and calls to action have been released by cancer societies, advocacy organizations, and regulatory agencies to guide inclusion of older adults in clinical trials. Effective implementation, however, requires awareness and close collaboration between all stakeholders involved in the clinical trial journey. We herein provide insights and experience from a drug developer on key considerations to optimize participation and retention of older adults in cancer clinical trials and discuss those under 4 key domains: trial eligibility and design, assessments and endpoints, patients and oncologists, and data reporting.
Mail Routes and the Costs of Expansion, 1866–83
Authors: Blevins Cameron
Published: April 2021

Chapter 4 examines the transportation of mail in the western United States. During the 1860s and 1870s the Post Office Department contracted with private stagecoach companies to carry the mail on its behalf, allowing it to extend mail routes across the region without establishing its own costly public infrastructure. Government mail contracts effectively subsidized the western stagecoach industry and facilitated the region’s breakneck growth during these decades. But staging companies began to lobby, collude, and bribe their way into exorbitant contracts worth millions of dollars, and by the end of the 1870s the situation had devolved into a full-fledged institutional crisis. This chapter is a story about mismanagement, fraud, and corruption, but it also speaks to the federal government’s lack of centralized administrative capacity. The decentralized agency model may have allowed the US Post to rapidly spread across the West, but this frenetic regional expansion project came with considerable costs.
Money Orders and National Integration, 1864–95
Authors: Blevins Cameron
Published: April 2021

Chapter 6 traces the expansion of the postal money order system between the 1860s and 1890s, a service that allowed people to send small sums of money safely and cheaply through the mail. This chapter offers another counterpoint to assumptions about the inevitable tides of bureaucratization and national integration in the 19th-century West. First, unlike much of the US Post, the money order system was a centralized bureaucracy, managed by a career technocrat named Charles Macdonald. But Macdonald’s efficient management was predicated on limiting its spatial coverage to a relatively small number of western post offices. Second, money orders allowed westerners to conduct long-distance transactions that helped integrate them into a national consumer market. Mapping where the residents of one western town actually sent money orders during the 1890s reveals the unexpected pattern that despite an age of nationalizing forces, their remittances stayed largely within a regional orbit.
Perceiving and capturing opportunities through social interaction
Authors: Elfring Tom , Klyver Kim , van Burg Elco
Published: April 2021

This chapter presents an entrepreneurship-as-networking perspective on opportunity perception, evaluation, and action. Entrepreneurial opportunities are seen as relationally constituted; thus, social networks are a fundamental aspect of all opportunity-related processes. The network ties upon which entrepreneurs can draw largely influence their opportunity perceptions and, conversely, entrepreneurs intentionally shape their networks to get to those opportunities. In opportunity evaluation, the feedback of others is essential to identify an opportunity’s feasibility and desirability. At the same time, these others often engage in shaping and co-creating the opportunities. In opportunity action, entrepreneurs tend to create strong embeddedness by forming their teams and hiring their employees from among their close ties. By discussing the key networking mechanisms of embedding, accessing, transferring, diversifying, and socializing for each of these opportunity-related processes, the authors highlight both the positive and negative generative aspects of the social interactions and social networks in relation to entrepreneurial opportunities.