bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEX DETERMINATION IN BEES. IV. GENETIC CONTROL OF JUVENILE HORMONE PRODUCTION IN MELIPONA QUADRIFASCIATA (APIDAE)
Authors: Kerr Warwick Estevam , Akahira Yukio , Camargo Conceição A 
Published: April 2021

ABSTRACT
Cell number and volume of corpora allata was determined for 8 phases of development, the first prepupal stage to adults 30 days old, in the social Apidae Melipona quadrifasciata. In the second prepupal stage a strong correlation was found between cell number and body weight (r=0.651**), and cell number and corpora allata volume in prepupal stage (r=0.535*), which indicates that juvenile hormone has a definite role in caste determination in Melipona. The distribution of the volume of corpus allatum suggest a 3:1 segregation between bees with high volume of corpora allata against low and medium volume. This implies that genes xa and xb code for an enzyme that directly participates in juvenile hormone production. It was also concluded that the number of cells in the second prepupal stage is more important than the weight of the prepupa for caste determination. A scheme summarizing the genic control of sex and caste determination in Melipona bees in the prepupal phase is given.
THE GENETIC STRUCTURE OF A TRIBAL POPULATION, THE YANOMAMA INDIANS. XIV. CLINES AND THEIR INTERPRETATION
Authors: Ward R H , Neel James V 
Published: April 2021

ABSTRACT
The Yanomama Indians are a South American tribe distributed over an irregular area approximately 200 × 300 miles. The gene frequencies observed at 12 loci in 47 villages within this area have been analyzed for the occurrence of clines. Apparently significant clines are observed for alleles of the Rh, MNSs, Kidd, Gm, Inv and serum albumin system. Available data concerning recent tribal expansion and admixture permit a tentative analysis of the causes of these clines. Although the action of selection cannot be rigorously excluded, it seems unlikely to be the major cause. Admixture with surrounding tribes plays a role which can be quantified because of the fortuitous circumstance of two genetic markers for admixture. It is suggested that an important factor in the origin of these clines is the manner in which the tribe has recently expanded through successive village fissionings and a predominantly centrifugal pattern of village migration.
TWO-WAY SELECTION FOR GROWTH RATE IN THE COMMON CARP (CYPRINUS CARPIO L.)
Authors: Moav R , Wohlfarth G 
Published: April 2021

ABSTRACT
The domesticated European carp was subjected to a two-way selection for growth rate. Five generations of mass selection for faster growth rate did not yield any response, but subsequent selection between groups (families) resulted in considerable progress while maintaining a large genetic variance. Selection for slow growth rate yielded relatively strong response for the first three generations. Random-bred control lines suffered from strong inbreeding depression and when two lines were crossed, the F1 showed a high degree of heterosis. Selection was performed on pond-raised fish, but growth rate was also tested in cages. A strong pond-cage genetic interaction was found. A theoretical explanation was suggested involving overdominance for fast growth rate and amplification through competition of intra-group but not inter-group variation.
ISOLATION AND CHARACTERIZATION OF AMBER SUPPRESSORS IN YEAST
Authors: Liebman Susan W , Sherman Fred , Stewart John W 
Published: April 2021

ABSTRACT
Nonsense suppressors were obtained in a haploid yeast strain containing eight nutritional mutations, that are assumed to be amber or ochre, and the cyc1-179 amber mutation that has a UAG codon corresponding to position 9 in iso-1-cytochrome c. Previous studies established that the biosynthesis and function of iso-1-cytochrome c is compatible with replacements at position 9 of amino acids having widely different structures (Stewart and Sherman 1972). UV-induced revertants, selected on media requiring the reversion of one or two of the amber nutritional markers, were presumed to contain a suppressor if there was the unselected reversion of at least one other marker. The 1088 suppressors that were isolated could be divided into 78 phenotypic classes. Only 43 suppressors of three classes caused the production of more than 50% of the normal amount of iso-1-cytochrome c in the cyc1-179 strain. Genetic analyses indicated that all of these highly efficient amber suppressors are allelic to one or another of the eight suppressors which cause the insertion of tyrosine at ochre (UAA) codons (Gilmore, Stewart and Sherman 1971). Furthermore, only tyrosine has been identified at position 9 in iso-1-cytochrome cin cyc1-179 strains suppressed with these efficient amber suppressors.
LINKAGE RELATIONSHIPS AND CHROMOSOME ASSIGNMENT OF FOUR ESTERASE LOCI IN THE MOSQUITO ANOPHELES ALBIMANUS
Authors: Vedbrat Sharanjit S , Whitt Gregory S 
Published: April 2021

ABSTRACT
Although anopheline mosquitoes are important vectors of malaria, their genetic makeup has not yet been extensively investigated. The present studies concentrate on the genetic basis of esterases in Anopheles albimanus. Nine zones of esterase activity have been resolved by gel electrophoresis. Four of these esterases: EST-2, EST-4, EST-6, and EST-8 are present throughout all developmental stages and also possess allelic variation. Mass matings were carried out with homozygous males and females heterozygous for two or more loci. The analyses of progeny from single egg batches revealed that the four esterase systems mentioned above are encoded in separate loci with codominant alleles. Analyses of two-point and three-point crosses have indicated the following linkage relationship: Est-8 — 12% — Est-4 — 22% — Est-2 — 9% — Est-6. The assignment of this linkage group to chromosome 3 has been accomplished by the use of a Y-2 chromosome translocation.
SUPPRESSION OF THE KILLER PHENOTYPE IN USTILAGO MAYDIS
Authors: Koltin Y , Day P R 
Published: April 2021

ABSTRACT
Nineteen sensitive cell lines of U. maydis were crossed with three killer strains and sample progenies were screened for killer segregation patterns. Crosses involving 11 lines gave killer frequencies ranging from 71%-100% of the progeny and 4:0 segregations in tetrads. Segregations in some crosses involving each of the remaining 8 lines gave killer frequencies from 0%-58% and mixed tetrads containing both non-killer and killer meiotic products. Many of the killers were unstable on further culture. Killer suppression showed varying degrees of specificity, appeared to be cytoplasmically determined for at least one strain, and was associated with possession of dsRNA in this strain and one other. No dsRNA was detected in two other suppressive strains. There was no evidence for segregation of nuclear maintainer genes for any of the killer determinants.
SYNAPTONEMAL COMPLEXES DURING PREMEIOTIC DNA SYNTHESIS IN OOCYTES OF DROSOPHILA MELANOGASTER
Authors: Day John W , Grell Rhoda F 
Published: April 2021

ABSTRACT
Well-synchronized populations of oocytes obtained by means of the "pupal system" (Grell, 1973a) have been examined to determine the time of appearance of the synaptonemal complex. The complex first appears in the most advanced oocytes between 132 and 138 hr of female development. Between 138 and 156 hr the complex apparently undergoes a fourfold increase in length. At 150 and 156 hr the complex system is extensive and present in virtually all oocytes. Previous studies using the pupal system have placed the period of premeiotic DNA synthesis between 132 and 162 hr. Thus, indirect evidence indicates that a significant portion of synaptonemal complex formation is coextensive with the main DNA replication in the oocyte. Direct evidence that DNA synthesis and complex formation occur simultaneously in oocytes has been obtained by electron microscope autoradiography. By definition, then, the stage of synaptonemal complex formation in Drosophila must include premeiotic interphase.
SPECIALIZED TRANSDUCING PHAGES DERIVED FROM PHAGE P22 THAT CARRY THE proAB REGION OF THE HOST, SALMONELLA TYPHIMURIUM: GENETIC EVIDENCE FOR THEIR STRUCTURE AND MODE OF TRANSDUCTION
Authors: Jessop Adrienne P 
Published: April 2021

ABSTRACT
Two independently isolated specialized transducing phages, P22pro-1 and P22pro-3, have been studied. Lysates of P22pro-1contain a majority of transducing phages which can go through the lytic cycle only in mixed infection; these defective phages transduce by lysogenization in mixed infection and by substitution in single infection. A few of the transducing phages in P22pro-1 lysates appear to be non-defective, being able to form plaques and to transduce by lysogenization in single infection. Transduction by P22pro-3 lysates is effected by non-defective transducing phages, which transduce by lysogenization; these lysates also contain a majority of defective phages which do not co-operate in mixed infection.
The P22pro-1 genome is thought to contain an insertion of bacterial DNA longer than the terminal repetition present in P22 wild type, so that at maturation a population of differently defective phages is produced. The exact structure of the P22pro-3 genome is open to conjecture, but it seems clear that the insertion of bacterial DNA is smaller than that in P22pro-1. Both P22pro-1 and P22pro-3 are defective in integration at ataA under non-selective conditions, although both integrate on medium that lacks proline.
MUTATIONAL ANALYSIS OF NATURAL ALLELES AT THE B INCOMPATIBILITY FACTOR OF SCHIZOPHYLLUM COMMUNE: α2 AND β6
Authors: Raudaskoski Marjatta , Stamberg Judith , Bawnik Nurit , Koltin Y 
Published: April 2021

ABSTRACT
The B incompatibility factor of the fungus Schizophyllum commune having allelic specificity α2–β6 was subjected to mutagenesis by X-irradiation. Five types of mutations were recovered, four of them new types previously unreported. All lead to loss of the B-factor regulatory function; three of the five have retained their allelic specificity. The mutations map in three closely linked sites: Bα, Bβ, and between Bα and Bβ.
REMARKS ON THE EVOLUTIONARY EFFECT OF NATURAL SELECTION
Authors: Ewens W J 
Published: April 2021

ABSTRACT
The so-called "Fundamental Theorem of Natural Selection", that the mean fitness of a population increases with time under natural selection, is known not to be true, as a mathematical theorem, when fitnesses depend on more than one locus. Although this observation may not have particular biological relevance, (so that mean fitness may well increase in the great majority of interesting situations), it does suggest that it is of interest to find an evolutionary result which is correct as a mathematical theorem, no matter how many loci are involved. The aim of the present note is to prove an evolutionary theorem relating to the variance in fitness, rather than the mean: this theorem is true for an arbitrary number of loci, as well as for arbitrary (fixed) fitness parameters and arbitrary linkage between loci. Connections are briefly discussed between this theorem and the principle of quasi-linkage equilibrium.
THIALYSINE-RESISTANT MUTANT OF SALMONELLA TYPHIMURIUM WITH A LESION IN THE thrA GENE
Authors: Jegede Victor A , Spencer Friederica , Brenchley Jean E 
Published: April 2021

ABSTRACT
A mutant of Salmonella typhimurium was selected for its spontaneous resistance to the lysine analog, thialysine (S-2-aminoethyl cysteine). This strain, JB585, exhibits a number of pleiotropic properties including a partial growth requirement for threonine, resistance to thiaisoleucine and azaleucine, excretion of lysine and valine, and inhibition of growth by methionine. Genetic studies show that these properties are caused by a single mutation in the thrA gene which encodes the threonine-controlled aspartokinase-homoserine dehydrogenase activities. Enzyme assays demonstrated that the aspartokinase activity is unstable and the threonine-controlled homoserine dehydrogenase activity absent in extracts prepared from the mutant. These results explain the growth inhibition by methionine because the remaining homoserine dehydrogenase isoenzyme would be repressed by methionine, causing a limitation for threonine. The partial growth requirement for threonine during growth in glucose minimal medium may also, by producing an isoleucine limitation, cause derepression of the isoleucine-valine enzymes and provide an explanation for both the valine excretion, and azaleucine and thiaisoleucine resistance. The overproduction of lysine may confer the thialysine resistance.
TEMPERATURE-SENSITIVE YEAST MUTANTS DEFECTIVE IN MEIOTIC RECOMBINATION AND REPLICATION
Authors: Roth Robert 
Published: April 2021

ABSTRACT
A system is described for isolating temperature-sensitive mutants of Saccharomyces cerevisiae with defects in early meiotic events. We used an otherwise haploid strain disomic (n+1) for chromosome III, and heteroallelic at the leucine-2 locus. Meiotic development was initiated by exposure of the strain to acetate sporulation medium, and monitored by the appearance of leucine-independent intragenic recombinants. Mutant isolation was based on the recovery of thermally induced defects in recombination. The temperature-sensitive characteristic was included to allow eventual characterizations of the temporal period during meiosis when each gene performs its essential function. Following mutagenesis with either ethyl methane sulfonate or nitrosoguanidine individual clones were tested at 34° and 24° for acetate-induced recombination. Starting with 2700 clones, derived from cells that survived mutagenic treatment, we isolated 48 strains with thermally induced lesions in recombination. In the majority of mutants premeiotic replication occurred normally, or nearly normally, at the restrictive temperature, indicating that the meiotic cycle was initiated and that there was a defect in an event required for intragenic recombination. We also detected mutants where the thermally induced lesion in recombination resulted from temperature-sensitive premeiotic DNA synthesis.
MUTAGENESIS OF CULTURED PLANT CELLS
Authors: Sung Z Renee 
Published: April 2021

ABSTRACT
Experiments were designed to study the effectiveness of the chemical mutagens ethylmethane sulfonate and nitrosoguanidine on plant cells growing in liquid suspensions. Mutation frequency was defined as the number of colonies appearing on selective plates divided by the number of colonies growing on non-selective plates. The compounds tested usually increased mutation frequency by one order of magnitude over the spontaneously occurring rate, although the increase ranged from one to 140-fold. Cell killing was found to be directly correlated with mutation frequency.
ENVIRONMENTAL DETERMINATION OF SELECTIVE SIGNIFICANCE OR NEUTRALITY OF AMYLASE VARIANTS IN DROSOPHILA MELANOGASTER
Authors: De Jong G , Scharloo W 
Published: April 2021

ABSTRACT
Strains homozygous at the amylase locus were derived from a polymorphic laboratory population of Drosophila melanogaster. The Amy 4,6 strain has higher enzyme activity than the Amy1 strain.—Maltose has the same nutritional value as starch.—The effect of starch in pure culture depends on the yeast level. At low yeast level increasing starch increases survival, at high yeast level increasing starch increases mean dry weight. The strains do not differ in survival or mean dry weight in pure culture.—In mixed cultures at 50% input of Amy 4,6 and Amy1 as larvae the percentage Amy4,6 in adults increases with increasing starch at low yeast levels, but equals input frequency at high yeast levels. No increase in percentage Amy4,6 in adults is present with increasing maltose at low yeast levels in mixed culture. The increase in percentage Amy4,6 with increasing starch must be due to selection on the amylase locus working by competition for food in the larval stage. The single locus selection coefficient is determined by the environment and can reach quite high values.—Viability selection in the presence of starch is in the direction indicated by the enzyme activities.
THE STRUCTURAL GENE FOR α-MANNOSIDASE-1 IN DICTYOSTELIUM DISCOIDEUM
Authors: Free S J , Schimke R T , Loomis W F 
Published: April 2021

ABSTRACT
We have isolated 4 independent mutations affecting α-mannosidase-1, a a developmentally regulated activity in Dictyostelium discoideum. Three of these result in a thermolabile α-mannosidase-1 activity. One mutation also affects the substrate affinity (Km) of the activity. In diploids these mutations show a gene dosage effect and are all alleles. The structural gene for α-mannosidase-1, as defined by these mutations, defines a new linkage group, linkage group VI. α-Mannosidase-1 is probably a homopolymer with subunits of 54,000 daltons.
REGULATION OF PHOSPHATE METABOLISM IN NEUROSPORA CRASSA: IDENTIFICATION OF THE STRUCTURAL GENE FOR REPRESSIBLE ACID PHOSPHATASE
Authors: Nelson Robert E , Lehman John F , Metzenberg Robert L 
Published: April 2021

ABSTRACT
A mutant of Neurospora crassa with an altered repressible acid phosphatase has been isolated. The enzyme is much more thermolabile than that of wild type, and has an increased Michaelis constant. Tests of allelic interactions (in partial diploids) and in vitro mixing experiments were consistent with the mutation being in the structural gene for the enzyme. This gene, pho-3, was found to be located in the right arm of Linkage Group IV (LG IV). Thus, pho-3 and the structural gene for repressible alkaline phosphatase, pho-2 (LG V), map in separate linkage groups and cannot be part of the same operon. Neither of these structural genes is linked to the known regulatory genes, nuc-1 (LG I), nuc-2 (LG II), and preg (LG II).
THE GENETICS OF DOPA DECARBOXYLASE IN DROSOPHILA MELANOGASTER I. ISOLATION AND CHARACTERIZATION OF DEFICIENCIES THAT DELETE THE DOPA-DECARBOXYLASE-DOSAGE-SENSITIVE REGION AND THE α-METHYL-DOPA-HYPERSENSITIVE LOCUS
Authors: Wright Theodore R F , Hodgetts Ross B , Sherald Allen F 
Published: April 2021

ABSTRACT
A detailed cytogenetic investigation of 16 overlapping deficiencies in the 36C-40A region on the left arm of the second chromosome (2L) in Drosophila melanogaster is reported. These deficiencies permit a localization of both the dopa-decarboxylase-dosage-sensitive region and the α-methyl-dopa-hypersensitive locus, l(2)amd, to the same region, 37B10-37C7.
ENZYMES AND REPRODUCTION IN NATURAL POPULATIONS OF DROSOPHILA EURONOTUS
Authors: Stalker Harrison D 
Published: April 2021

ABSTRACT
Populations of Drosophila euronotus, one from southern Louisiana (3 samples), and one from Missouri (2 samples), were classified for allele frequencies at alkaline phosphatase (APH) and acid phosphatase (ACPH) loci. The two populations differed consistently in allele frequencies at both loci. The APH locus is on the inversion-free X chromosome; the chromosomal locus of the autosomal ACPH is unknown, and could involve inversion polymorphism. Wild females from Missouri and Louisiana populations heterozygous at the APH locus carried more sperm at capture than did the corresponding homozygotes. This heterotic association was significant for the combined samples, and whether it was the result of heterosis at the enzyme locus studied, or due to geographically widespread close linkage with other heterotic loci, it should help to maintain heterozygosity at the APH locus. In a Louisiana collection which included large numbers of sperm-free females, simultaneous homozygosity at both enzyme loci was significantly associated with lack of sperm. It is suggested that the latter association is the result of young heterozygous females achieving sexual maturity earlier than do the double homozygotes. The average effective sperm load for 225 wild females was only 29.4, suggesting the necessity for frequent repeat-mating in nature to maintain female fertility. A comparison of the sex-linked APH genotypes of wild females with those of their daughters indicated that among 295 wild-inseminated females from five populations, 35% had mated more than once, and of this 35%, six females had mated at least three times. Because of ascertainment difficulties, it is clear that the true frequency of multiple-mating in nature must have been much higher than the observed 35%. Laboratory studies indicate that multiple-mating in this species does not involve sperm displacement, possibly due to the small number of sperms transmitted per mating, and the fact that the sperm receptacles are only partially filled by a given mating.
CHARACTERIZATION OF POSTREPLICATION REPAIR IN MUTAGEN-SENSITIVE STRAINS OF DROSOPHILA MELANOGASTER
Authors: Boyd J B , Setlow R B 
Published: April 2021

ABSTRACT
Mutants of Drosophila melanogaster, with suspected repair deficiencies, were analyzed for their capacity to repair damage induced by X-rays and UV radiation. Analysis was performed on cell cultures derived from embryos of homozygous mutant stocks. Postreplication repair following UV radiation has been analyzed in mutant stocks derived from a total of ten complementation groups. Cultures were irradiated, pulse-labeled, and incubated in the dark prior to analysis by alkaline sucrose gradient centrifugation. Kinetics of the molecular weight increase in newly synthesized DNA were assayed after cells had been incubated in the presence or absence of caffeine. Two separate pathways of postreplication repair have been tentatively identified by mutants derived from four complementation groups. The proposed caffeine sensitive pathway (CAS) is defined by mutants which also disrupt meiosis. The second pathway (CIS) is caffeine insensitive and is not yet associated with meiotic functions. All mutants deficient in postreplication repair are also sensitive to nitrogen mustard. The mutants investigated display a normal capacity to repair single-strand breaks induced in DNA by X-rays, although two may possess a reduced capacity to repair damage caused by localized incorporation of high specific activity thymidine-3H. The data have been employed to construct a model for repair of UV-induced damage in Drosophila DNA. Implications of the model for DNA repair in mammals are discussed.
VARIATION IN THE NUMBER OF GENES CODING FOR SALIVARY AMYLASE IN THE BANK VOLE, CLETHRIONOMYS GLAREOLA
Authors: Nielsen Jørn Tønnes 
Published: April 2021

ABSTRACT
A Danish population of bank voles is polymorphic for three electrophoretically different salivary amylases, A, H and S, of which A is the most common. Both single-, double- and triple banded phenotypes were observed, and in several crosses two electrophoretic forms cosegregated. In addition to the qualitative variation, some individuals show consistent quantitative variation in the relative activities of their amylase bands. This variation has been qualified by spectrophotometrical measurements of the relative amounts of amylase protein in the various bands.—Seventy wild chromosomes were analyzed by determining the amounts of amylase they produced when heterozygous with a laboratory stock chromosome known to carry two closely linked amylase genes, both coding for a fourth electrophoretic variant, B. The amount of A-protein divided by half the amount of B-protein was used as an estimate of the number of A-genes on the tested chromosomes. The wild chromosomes fell into three clearly distinguishable classes: 9 clustered around a gene number estimate of one, 45 chromosomes yielded estimates around two genes, and the gene number estimate of the remaining 16 was close to three. The integer values of the gene number estimates and the cosegregation of electrophoretically different salivary amylases are consistent with the model that the population is polymorphic for chromosomes with either one, two, or three closely linked amylase genes. It is suggested that such gene number variation may be more common than generally recognized, and some other reported cases of quantitative enzyme variation, for instance that of human red cell acid phosphatase, are interpreted in terms of variation in the number of genes involved.