bluuebunny/crossref_metadata_2025_split huggingface dataset:
MULTIPLE FORMS OF MAIZE ENDOSPERM ADP-GLUCOSE PYROPHOSPHORYLASE AND THEIR CONTROL BY SHRUNKEN-2 AND BRITTLE-2
Authors: Hannah L C , Tuschall D M , Mans R J 
Published: April 2021

ABSTRACT
Heat-labile and heat stable forms of ADP-glucose pyrophosphorylase were identified in the maize endosperm. The heat-labile form is destroyed by normal electrophoretic conditions. The heat-stable form corresponds to pyrophosphorylase B. In wild type, 96% of the total activity is heat labile. Both forms are reduced in 11 brittle-2 (bt2) and 12 shrunken-2 (sh2) mutants. The heat-labile form is reduced to a greater extent than is the heat-stable form in each of the 23 mutants. Deletion of sh2 abolishes both forms. The original ratio of the two forms is restored after sh2 function is expressed via transposition of Dissociation from sh2. The possible roles of these genes in the control of ADP-glucose pyrophosphorylase are discussed.
NEW LOCI IN DICTYOSTELIUM DISCOIDEUM DETERMINING PIGMENT FORMATION AND GROWTH ON BACILLUS SUBTILIS
Authors: Morrissey James H , Wheeler Steven , Loomis William F 
Published: April 2021

ABSTRACT
Seventeen independently isolated pigmentless (white) mutations in Dictyostelium discoideum are all recessive and fall into three complementation groups identifying two new whi loci in addition to the previously characterized whiA locus. whiB and whiC map to linkage groups III and IV, respectively. In addition, it was discovered that our laboratory stock of NC4, the wild-type strain from which these mutants were derived, has spontaneously lost the ability to grow on Bacillus subtilis. This new mutation, bsgB500, maps to linkage group VII and is not allelic to bsgA. bsgB500 is the first spontaneously derived mutation in D. discoideum that can be used to select heterozygous diploids, and for the first time allows genetic analysis to be routinely performed on strains derived from an unmutagenized background.
THE EFFECT OF GAMETOGENESIS REGIMES ON THE CHLOROPLAST GENETIC SYSTEM OF CHLAMYDOMONAS REINHARDTII
Authors: Sears Barbara B , Boynton John E , Gillham Nicholas W 
Published: April 2021

ABSTRACT
In Chlamydomonas reinhardtii, gamete differentiation is induced by nitrogen deprivation. While cellular nitrogen content and amount of chloroplast DNA in cells of both mating types are reduced during gametogenesis, the spontaneous transmission of paternal (mt -) chloroplast alleles in crosses is specifically affected by the stringency of the nitrogen starvation regime used for pregrowth and gametogenesis of the mt - parent. In all cases, reciprocal crosses yielded biparental zygospores whose clones contain predominantly cells expressing only the chloroplast alleles from the maternal (mt +) parent. No differences attributable to strain divergence were seen in chloroplast gene inheritance pattern, DNA content, or the relative frequency of transmission of paternal chloroplast alleles to progeny of biparental zygospores.
CORRELATION BETWEEN MAP POSITION AND PHENOTYPE OF CTI MUTANTS IN THE C CISTRON OF RHIZOBIUM MELILOTI PHAGE 16—3
Authors: Dudás Brigitta , Orosz László 
Published: April 2021

ABSTRACT
Nine temperature-sensitive clear mutations (Cti) in the C cistron (coding for the repressor protein) of Rhizobium meliloti temperate phage 16—3 were characterized according to the inductive temperature, the immunity of cells lysogenic for these mutant phages to superinfection by homoimmune weak virulent mutants, the phenotype of double-ti mutants and interallelic complementation. The results indicate that mutations of similar phenotypic expression are clustered on the genetic map. Furthermore, it seems probable that the C cistron of the original phage 16—3 is identical to that of the independently isolated phage strain 36.
TEMPERATURE-SENSITIVE MUTANTS BLOCKED IN THE FOLDING OR SUBUNIT ASSMBLY OF THE BACTERIOPHAGE P22 TAILSPIKE PROTEIN. I. FINE-STRUCTURE MAPPING
Authors: Smith Donna H , Berget Peter B , King Jonathan 
Published: April 2021

ABSTRACT
As part of a study of protein folding, we have constructed a fine-structure map of 9 existing and 29 newly isolated UV- and hydroxylamine-induced temperature-sensitive (ts) mutations in gene 9 of Salmonella bacteriophage P22. Gene 9 specifies the polypeptide chain of the multimeric tail spikes, six of which form the cell attachment organelle of the phage. The 38 ts mutants were mapped against deletion lysogens with endpoints in gene 9. They mapped in 10 of the 15 deletion intervals. Two- and three-factor crosses between mutants within each interval indicated that at least 31 ts sites are represented among the 38 mutants. To determine the distribution of ts sites within the physical map, we identified the protein fragments from infection of su- hosts with 10 gene 9 amber mutants. Their molecular weights, ranging from 13,900 to 55,000 daltons, were combined with the genetic data to yield a composite map of gene 9. The 31 ts sites were distributed through most of the gene, but were most densely clustered in the central third.—None of the ts mutant pairs tested exhibited intragenic complementation. Studies of the defective phenotypes of the ts mutants (Goldenberg and King 1981; Smith and King 1981) revealed that most do not affect the thermostability of the mature protein, but instead prevent the folding or subunit assembly of the mutant chains synthesized at restrictive temperature. Thus, many of thes ts mutations identify sites in the polypeptide chain that are critical for the folding or maturation of the tail-spike protein.
MUTANTS AFFECTED IN ALKALINE PHOSPHATASE EXPRESSION: EVIDENCE FOR MULTIPLE POSITIVE REGULATORS OF THE PHOSPHATE REGULON IN ESCHERICHIA COLI
Authors: Wanner Barry L , Latterell Patrick 
Published: April 2021

ABSTRACT
The expression of alkaline phosphatase (the product of the phoA gene) in Escherichia coli is believed to be subject to both positive control by the phoB gene product and negative control by the phoR gene product. We have isolated a large number of PhoA- mutants in the phoR - genetic background. Among mutants altered in the positive control of alkaline phosphatase, some were phoB mutants; others had a mutation in a new gene, designated phoM. We believe that the phoM gene codes for a positive regulator that acts together with the phoB gene product in phoA gene expressions.—The PhoM phenotype was found to be masked in phoR + strains. This and other evidence support a positive regulatory role for the phoR gene product as well.—Our experiments demonstrate that phoA is under positive control by three different positive regulators: the products of the phoB, phoM and phoR genes. The phoB gene product is always needed together with either the phoR or phoM gene product. In addition, the phoR gene product acts as a negative regulator.—We describe a model for phoA gene expression consistent with this new evidence.
MEIOSIS IN NEUROSPORA CRASSA. II. GENETIC AND CYTOLOGICAL CHARACTERIZATION OF THREE MEIOTIC MUTANTS
Authors: DeLange A M , Griffiths A J F 
Published: April 2021

ABSTRACT
Three recessive meiotic mutants, asc(DL95), asc(DL243) and asc(DL879), were detected by the abortion of many of their ascospores and were analyzed using both cytological and genetic methods. Even though asc(DL95), asc(DL243) and the previously studied meiotic mutant, mei-1 (Smith 1975; Lu and Galeazzi 1978), complement one another in crosses, they apparently do not recombine (DeLange and Griffiths 1980). Thus, they may represent alleles of the same gene or comprise a gene cluster. Ascospore abortion in these mutants is caused by abnormal disjunction of meiotic chromosomes. In crosses homozygous for asc(DL95), asc(DL879) or mei-1, both pairing of homologs and meiotic recombination frequencies are reduced. In each case, this primary defect is followed by the formation of univalents at metaphase I and their irregular segregation. The mutant asc(DL243) has a defect in ascus formation, and later in disjunction during the second meiotic and post-meiotic divisions. The first-acting defect before or during karyogamy results in the abortion of most cells. Some cells manage to proceed past this block. During the second meiotic division, most chromosomes of the few resulting asci are attached to only one of the two spindle-pole bodies. Disjunction at the postmeiotic division is also highly irregular. This mutant appears to be defective in the attachment of one spindle-pole body to a set of chromosomes. The defect may involve either a centromere-associated product or a spindle-pole body.
TWO-LOCUS PROBLEMS IN TRANSMISSION GENETICS OF MITOCHONDRIA AND CHLOROPLASTS
Authors: Ohta Tomoko 
Published: April 2021

ABSTRACT
A problem in transmission genetics was studied theoretically by regarding a cell as a population of organelle chromosomes. A hybrid cell of the two strains is assumed to consist initially of equal numbers of the two types of nucleoids, each containing an equal number of chromosomes. The two parent strains have different alleles at the two loci, and the two-locus dynamics of the hybrid cell line was analyzed. Within each nucleoid, stochastic matching and gene conversion are assumed to occur between the chromosomes, and at a certain rate fusion and division are assumed to take place between the nucleoids within the cell. Under this model, the changes of average genotype frequencies at the two loci within a nucleoid and within a cell were formulated, and the final frequencies of recombinant chromosomes were obtained. Random segregation of nucleoids at cell division was incorporated into the analyses; in addition, the increase of homozygosity in the cell was formulated. The results may be useful for interpreting the observed data on organelle genetics of some species of algae and yeast.
SELECTIVE NEUTRALITY OF 6PGD ALLOZYMES IN E. COLI AND THE EFFECTS OF GENETIC BACKGROUND
Authors: Dykhuizen Daniel , Hartl Daniel L 
Published: April 2021

ABSTRACT
We have used gluconate-limited chemostats to study selective differences between isogenic strains of Escherichia coli K12 into which four naturally occurring alleles coding for allozymes of 6-phosphogluconate dehydrogenase (6PGD) had been transferred. The limit of detectability of selection with our procedures is a selection coefficient of 0.5%. In the normal E. coli K12 genetic background, all alleles are selectively neutral or nearly neutral. The absence of detectable selection does, however, depend on genetic background and on such environmental factors as cell density. In a genetic background containing a mutation that cuts off the alternative metabolic route for 6-phosphogluconate, selection between allozymes can be detected, and the selection is in the direction expected from the measured apparent Km values of the allozymes. Even when the alternative metabolic route is not blocked by mutation, one of the 6PGD allozymes has a detrimental, but density-dependent, interaction with a mutation conferring resistance to bacteriophage T5. In all cases, the observed selection is due to the allozymes themselves (or to associated regulatory elements), as the selection disappears when the chemostats are limited by a different carbon source (ribose plus succinate). Nevertheless, the four alleles do seem to be selectively neutral or nearly neutral in the normal E. coli K12 genetic background. Moreover, the distribution of allele frequencies in natural populations of E. coli is in accord with the expectations of selective neutrality.
I am inclined to suspect that we see, at least in some [cases], variations which are of no service to the species, and which consequently have not been seized on and rendered definite by natural selection…. Variations neither useful nor injurious would not be affected by natural selection, and would be left either a fluctuating element, as perhaps we see in certain polymorphic species, or would ultimately become fixed…. We may easily err in attributing importance to characters, and in believing that they have been developed through natural selection;… many structures are now of no direct use to their possessors, and may never have been of any use to their progenitors…. [On the other hand,] we are much too ignorant in regard to the whole economy of any organic being to say what slight modifications would be of importance or not.
BEHAVIORAL AND BIOCHEMICAL DEFECTS IN TEMPERATURE-SENSITIVE ACETYLCHOLINESTERASE MUTANTS OF DROSOPHILA MELANOGASTER
Authors: Hall Jeffrey C , Alahiotis Stamatis N , Strumpf David A , White Kristin 
Published: April 2021

ABSTRACT
Temperature-sensitive (ts) mutants of the Ace gene, which codes for acetylcholinesterase (AChE) in Drosophila melanogaster, were analyzed for defects in viability, behavior and function of the enzyme. The use of heat-sensitive and cold-sensitive mutations permited the function of AChE in the nervous system to be analyzed temporally. All ts mutations were lethal, or nearly so, when animals expressing them were subjected to restrictive temperatures during late embryonic and very early larval stages. Heat treatments to Ace-ts mid- and late larvae had little effect on the behavior of these animals or on the viability or behavior of the eventual adults. Heat-sensitive mutants exposed to nonpermissive temperatures as pupae, by contrast, had severe defects in phototaxis and locomotor activity as adults. AChE extracted from adult ts mutants that had developed at a permissive temperature were abnormally heat labile, and they had reduced substrate affinity when assayed at restrictive temperatures. However, enzyme activity did not decline during exposure of heat-sensitive adults to high temperatures even though such treatments caused decrements in phototaxis (29°) and, eventually, cessation of movement (31°). The cold-sensitive mutant also produced readily detectable levels of AChE when exposed to a restrictive temperature during the early developmental stage when this mutation causes almost complete lethality. We suggest that the relationship among the genetic, biochemical and neurobiological defects in these mutants may involve more than merely temperature-sensitive catalytic functions.
LACK OF GENIC VARIATION IN THE ABUNDANT PROTEINS OF HUMAN KIDNEY
Authors: Smith Sandra C , Racine Robert R , Langley Charles H 
Published: April 2021

ABSTRACT
Abundant proteins of 25 human kidneys were surveyed for genic variation by means of two-dimensional electrophoresis. Eighty-three (83) proteins were scored, and no genic variation was detected. This reduction in genic heterozygosity corroborates results determined with two-dimensional electrophoresis in mice and flies. These results suggest that previous estimates of electrophoretic variation may have been in error because of biased selection of loci.
A RARE-MALE ADVANTAGE IN THE HOUSEFLY INDUCED BY WING CLIPPING AND SOME GENERAL CONSIDERATIONS FOR DROSOPHILA
Authors: Bryant Edwin H , Kence Aykut , Kimball Kay T 
Published: April 2021

ABSTRACT
Multiple-choice crosses among five geographic strains of the housefly, Musca domestica L., were carried out in equal (10:10) and low-frequency (4:16) ratios. Initially, a low-frequency-male mating advantage was apparent, but further analyses related this minority advantage to a reduction of male mating success during marking by wing clipping. When there are fluctuating differences in the level of sexual vigor between competing male types over replicate trials of a cross, a mating advantage will accrue to the minority type. Even if males from the two competing strains are equally vigorous, such fluctuating differences will occur during sampling of flies. Harming the flies during marking will serve to enhance this effect and make significant departures toward greater mating success of rare males highly likely. This statistical bias in favor of minority males was substantiated in simulations of the Kence-Bryant model of mating success and compared with our results of a minority advantage in the housefly and with published results of a minority advantage in Drosophila. Our evidence, though circumstantial, that an advantage to minority males could have been induced by such an experimental bias suggests that a re-examination of existing data, as well as new experimentation, is necessary to discern whether or not a real rare-male advantage exists.
SUPPRESSORS OF MUTATIONS IN THE rII GENE OF BACTERIOPHAGE T4 AFFECT PROMOTER UTILIZATION
Authors: Hall Dwight H , Snyder Ronald D 
Published: April 2021

ABSTRACT
Homyk, Rodriguez and Weil (1976) have described T4 mutants, called sip, that partially suppress the inability of T4rII mutants to grow in λ lysogens. We have found that mutants sip1 and sip2 are resistant to folate analogs and overproduce FH2 reductase. The results of recombination and complementation studies indicate that sip mutations are in the mot gene. Like other mot mutations (Mattson, Richardson and Goodin 1974; Chace and Hall 1975; Sauerbier, Hercules and Hall 1976), the sip2 mutation affects the expression of many genes and appears to affect promoter utilization. The mot gene function is not required for T4 growth on most hosts, but we have found that it is required for good growth on E. coli CTr5X. Homyk, Rodriguez and Weil (1976) also described L mutations that reverse the effects of sip mutations. L2 decreases the folate analog resistance and the inability of sip2 to grow on CTr5X. L2 itself is partially resistant to a folate analog, and appears to reverse the effects of sip2 on gene expression. These results suggest that L2 affects another regulatory gene related to the mot gene.
A TWO-SEX POLYGENIC MODEL FOR THE EVOLUTION OF PREMATING ISOLATION. I. DETERMINISTIC THEORY FOR NATURAL POPULATIONS
Authors: Sved J A 
Published: April 2021

ABSTRACT
It is proposed that mating behavior is normally determined by independent genetic systems in the male and female. A specific model is put forward in which mating behavior is determined by additive gene contributions in both sexes, and the strength of mating attraction is maximized when mating "scores" in the two sexes are equalized. This type of model, which may be described as a "facilitation" model, is related to models proposed by a number of authors. It is pointed out that a second class of models exists, "avoidance" models, and that these, although less tractable analytically, could be more realistic. —An organism is assumed to be divided into two strains, and selection is introduced through lethality or sterility of the hybrid (postmating isolation). The selective tendency for divergence of mating behavior in one sex is then shown to be proportional to the amount of divergence that already exists in the opposite sex, multiplied by a quantity that can be described as the heritability of mating attraction. The situation in which no initial divergence exists in either sex constitutes an equilibrium that is unstable, but one that requires substantial deviations before any selective progress can be made. Thus, the evolution of premating isolation to reinforce postmating isolation may be an inefficient process. The process would occur much more efficiently if some initial chance divergence in mating behavior occurred during the period in which postmating isolation evolved.
A TWO-SEX POLYGENIC MODEL FOR THE EVOLUTION OF PREMATING ISOLATION. II. COMPUTER SIMULATION OF EXPERIMENTAL SELECTION PROCEDURES
Authors: Sved J A 
Published: April 2021

ABSTRACT
A Monte-Carlo simulation program is described for a polygenic mating model introduced in the first paper in this series (Sved 1981). The program is used to simulate the situation in laboratory experiments in which two strains are allowed to mass-mate, hybrids are artificially eliminated and the establishment of mating isolation is studied. It is shown that, if mating choice is sufficiently precise, a combination of chance fluctuation and selection can lead to divergence in mating behavior. However, for small population sizes, the variability would usually be considerably reduced by the time some divergence is established, leading to low eventual levels of isolation. For larger population sizes, on the other hand, it may take many generations for any divergence to be established. —A dissection of the selective forces involved in the divergence shows that the major force potentially responsible for initial selective response is the tendency for divergent females and males to reject mates from the wrong strain. However, this is nullified in mixed-strain matings by the tendency of such individuals equally to reject mates from the correct strain. To overcome this problem, it is suggested that the usual mixed-strain mating procedure be replaced by procedures specifically designed to select for rejection of interstrain matings. Two procedures are suggested for this, and computer simulation shows that one or other of the procedures will work under the assumptions of the mating model. Other possible outcomes of selection, including asymmetrical divergence, are discussed for cases in which the assumptions of the mating model are invalid.
THE ISOLATION OF MMS- AND HISTIDINE-SENSITIVE MUTANTS IN NEUROSPORA CRASSA
Authors: Delange A M , Mishra N C 
Published: April 2021

ABSTRACT
A simple method of replica plating has been used to isolate mutants of Neurospora crassa that have increased sensitivity to methyl methanesulfonate (MMS) and/or to histidine. Twelve mutants with increased sensitivity to MMS and one mutant with increased sensitivity to histidine showed Mendelian segregation of the mutant phenotypes. Three mutants were mapped to loci not previously associated with MMS sensitivity. Two others were allelic to the UV- and MMS-sensitive mutant, mei-3. Survival curves indicate that conidia (mutant or wild-type) survive on much higher concentrations of MMS at 25° than at 37°. In contrast, mycelial growth is more resistant to MMS at 37°. The possibility of qualitatively different repair processes at these two temperatures is discussed.
INSERTIONS OF THE TRANSPOSON Tn1 INTO THE PSEUDOMONAS AERUGINOSA CHROMOSOME
Authors: Krishnapillai V , Royle Pamela , Lehrer Joanna 
Published: April 2021

ABSTRACT
The transposon Tnl has been translocated to the chromosome of Pseudomonas aeruginosa from plasmid R18, iollowing hydro,xylamine mutagenesis of the plasmid. Twelve insertions were mapped to six distinct sites distal to 55 min of the origin of chromosome transfer by the plasmid FP2. These map locations were confirmed by host chromosome mobilization tests mediated by plasmids RI8 or R91-5, due to Tni homology between plasmid and host chromosome. All the Tnl chromosomal inserts were retransposable to other plasmids (Sa, R931 and R38). The behavior of Tnl in P. aemginosa was very similar to its behavior in Escherichia coli with respect to regional specificity, orientation of insertion and in serving as regions of homology for host chromosome mobilization by plasmids. This last property has permitted the demonstration that Tnl on RI8 and R91-5 is in opposite orientation with respect to the origin of transfer (oriT) of the two plasmids.
THE GENETIC BASIS OF DOSAGE COMPENSATION OF ALCOHOL DEHYDROGENASE-1 IN MAIZE
Authors: Birchler James A 
Published: April 2021

ABSTRACT
The levels of alcohol dehydrogenase (ADH) do not exhibit a structural gene-dosage effect in a one to four dosage series of the long arm of chromosome one (1L) (BIRCHLER19 79). This phenomenon, termed dosage compensation, has been studied in more detail. Experiments are described in which individuals aneuploid for shorter segments were examined for the level of ADH in order to characterize the genetic nature of the compensation. The relative ADH expression in segmental trisomics and tetrasomics of region IL 0.72–0.90, which includes the Adh locus, approaches the level expected from a strict gene dosage effect. Region IL 0.20–0.72 produces a negative effect upon ADH in a similar manner to that observed with other enzyme levels when IL as a whole is varied (BIRCHLEF1I9 79). These and other comparisons have led to the concept that the compensation of ADH results from the cancellation of the structural gene effect by the negative aneuploid effect. The example of ADH is discussed as a model for certain other cases of dosage compensation in higher eukaryotes.