bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE PARTHENOGENETIC CAPACITIES AND GENETIC STRUCTURES OF SYMPATRIC POPULATIONS OF DROSOPHILA MERCATORUM AND DROSOPHILA HYDEI
Authors: Templeton Alan R 
Published: April 2021

ABSTRACT
Drosophila mercatorum is a sexual species that can reproduce parthenogenetically in the laboratory. A previous study showed that a natural population of D. mercatorum inhabiting the Kamuela garbage dump on the Island of Hawaii could produce both viable parthenogenetic adults and self-sustaining parthenogenetic lines. The present study deals with a second screen for parthenogenesis and an isozyme survey performed on natural populations of D. mercatorum and D. hydei caught in patches of Opuntia tuna about 10 kilometers from Kamuela. Both cactus-patch species produced viable partheno-genetic adults, but only D. mercatorum produced parthenogenetic females themselves capable of parthenogenesis. Moreover, D. mercatorum produced several "hot" lines characterized by high parthenogenetic rates, while all lines of D. hydei had a homogenous low rate. The parthenogenetic capacity of the cactus-patch D. mercaiorum was lower than that of the garbage-dump D. mercatorum. Moreover, both the cactus-patch D. mercatorum and D. hydei had lower levels of polymorphism (26% and 22%, respectively) then the garbage-dump D. mercatorum (44%), and both cactus-patch populations had heterozygote deficiencies with respect to Hardy-Weinberg equilibrium, unlike the garbage-dump population. Consequently, these data do not support the idea that decreased levels of heterozygosity in a sexual population increase the chance that sexual females will produce totally homozygous, parthenogenetic progeny.
THE EFFECTS OF INTERSPECIFIC COMPETITION ON THE DYNAMICS OF A POLYMORPHISM IN AN EXPERIMENTAL POPULATION OF DROSOPHILA MELANOGASTER
Authors: Clark Andrew 
Published: April 2021

ABSTRACT
Populations of Drosophila melanogaster with a fourth-chromosome polymorphism were subjected to different levels of competition with Drosophila simulans. The dynamics of the polymorphism and the equilibrium frequencies of the sparkling allele were seen to depend on the competitive level, while the higher productivity of the competing populations was shown to be due to the initial parental density. The effects of competition on fitness components were quantified by fitting the data to both a two-stage selection model and a fertility model. Additional experiments were performed to verify that the interspecific competition caused the changes in fitness. The results are discussed in light of the importance of considering selection components in models of ecological genetics.
POPULATION GENETICS OF HAPLODIPLOID INSECTS
Authors: Lester L J , Selander R K 
Published: April 2021

ABSTRACT
Genic variation of seven species of Hymenoptera is described, using electrophoretic techniques. The heterozygosities range from 0.033 to 0.084. An average heterozygosity is calculated for 23 species of haplodiploid insects, and this value is significantly different from the same value for 18 Drosophila species or for W diploid insect species (including Drosophila). The niche width-gepetic variation hypothesis is rejected as an explanation. A comparison of selection models and neutral models shows that both hypotheses are capable of explaining the data.
GENETIC ANALYSIS OF GAMMA-RAY MUTAGENESIS IN YEAST. I. REVERSION IN RADIATION-SENSITIVE STRAINS
Authors: McKee Richard H , Lawrence Christopher W 
Published: April 2021

ABSTRACT
The frequency of revertants induced by 6OCo γ rays of the ochre allele, cyc1-9, has been measured in radiation-sensitive strains carrying one of 19 nonallelic mutations and in wild-type strains. The results indicate that ionizing radiation mutagenesis depends on the activity of the RAD6 group of genes and that the gene functions employed are very similar, but probably not identical, to those that mediate UV mutagenesis. Repair activities dependent on the functions of the RAD50 through RAD57 loci, the major pathway for the repair of damage caused by ionizing radiation, do not appear to play any part in mutagenesis. A comparison between the γ-ray data and those obtained previously with UV (LAWRENCE and CHRISTENSEN 1976) and chemical mutagens (PRAKASH 1976) suggests that the RAD6 "mutagenic pathway" is in fact composed of a set of processes, some of which are concerned with error-prone, and some with error-free, recovery activities.
MUTATIONAL ANALYSIS OF NATURAL ALLELES IN AND AFFECTING THE B INCOMPATIBILITY FACTOR OF SCHIZOPHYLLUM
Authors: Koltin Y , Stamberg Judith , Bawnik N , Tamarkin A , Werczberger R 
Published: April 2021

ABSTRACT
Primary mutations in the alleles α1 and β7 of the B incompatibility factor of Schizophyllum were induced with X rays. An additional mutation unlinked to the B factor and affecting its regulatory function was detected. This mutation is effective in monokaryons with most B-factor specificities. The spectra of induced mutations in different alleles is discussed in reference to a polarity in the expression of the recognition function and the regulatory function by each locus of the B incompatibility factor.
THE BROOD PATTERN OF MITOMYCIN-C-INDUCED TRANSLOCATIONS IN DROSOPHILA MELANOGASTER MALES: THE EFFECT OF TIME
Authors: Shukla P T , Auerbach C 
Published: April 2021

ABSTRACT
Translocations between the two large autosomes were scored in the progeny of males that had been fed mitomycin-C. The frequencies were the same in spermatogonia sampled after 12 and 25 days and in spermatozoa stored for the same periods in untreated females.
ON THE MODELS OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER
Authors: Martin Diana W , Hiraizumi Yuichiro 
Published: April 2021

ABSTRACT
The Segregation Distorter system of Drosophila melanogaster consists of two major elements, Sd and Rsp. There are two allelic alternatives of Rsp—sensitive (Rsp8) and insensitive (Rspi); a chromosome carrying Rspi is not distorted. According to the model proposed by HARTL (1973), these two elements interact to cause segregation distortion. For a sperm to complete the maturation process, it is assumed that the Rsp locus has to be complexed with the product of the Sd locus. This product is assumed to be a multimetric regulatory protein. Three kinds of regulatory multimers may be distinguished: Sd+/Sd+, which is assumed to complex with both Rsp8 and Rspi; Sd+/Sd heteromultimers, which complex preferentially with Rspi; and Sd/Sd hmomultimers, which complex with neither Rsp8 nor Rspi. Most of the regulatory protein in the Sd+/Sd heterozygous male is assumed to be the Sd+/Sd heteromultimer. ——Some modifications of HARTL'S model were made by GANETZEY (1977). Rather than the binding of a product of Sd at the Rsp locus being a necessary condition for normal spermigenesis, this binding causes sperm dysfunction. It is assumed that the product of Sd complexes more readily with Rsp8 than with Rspi and that the amount of Sd product is limited with respect to the number of binding sites available. No function is ascribed to the Sd+ locus. In order to explain reduced male fertility of some genotypes, GANETZKY further assumes that the Sd product, when not competed for by an Rsp8 locus, can bind to an Rspi locus.——Two consequences of these models were criticically examined: according to these models (1) an Sd Rsp8/Sd+ RspS male should not show any segregation distortion, and (2) an Sd Rsps/Sd Rsp8 male should show much reduced fertility, if not complete sterility.—The results of the present study bear on these two points. (1) Rsp8 locus seems to consist of multiple alleles, each having a different degree of ability to interact with the product of the Sd locus. An Sd Rsp8/Sd+RspS male shows a certain degree of segregation distortion when the two RspS alleles are different, but it shows a normal Mendelian segregation ratio when the Rsp8 alleles are homozygous. The first prediction of the models is supported by actual observation when the two Rsps alleles are the same. (2) There is a suggestion of slight reduction in fertility, but generally Sd Rsp8/Sd Rsp8 males are quite fertile. Thus, the second prediction is not supported by actual observation. The mechanism of segregation distortion is still open for future studies.
A MODEL OF THE NEGATIVE CORRELATION BETWEEN MALE RECOMBINATION AND TRANSMISSION FREQUENCY IN DROSOPHILA MELANOGASTER
Authors: Hiraizumi Yuichiro 
Published: April 2021

ABSTRACT
A model is proposed to account for the phenomenon of negative correlation between male recombination (θ) and transmission frequency (k) in Drosophila melanogaster.
The model assumes that, in some stage or stages of development, the male recombination elements cause a particular event that does not occur in normal males and that this event, in turn, induces with certain probabilities male recombination and/or sperm dysfunction.
The regression equations of θ on k predicted by the model were compared with those actually observed. There was generally excellent agreement between them.
THE GENETICS OF DROSOPHILA SUBOBSCURA POPULATIONS. IX. STUDIES ON LINKAGE DISEQUILIBRIUM IN FOUR NATURAL POPULATIONS
Authors: Loukas M , Krimbas C B , Vergini Y 
Published: April 2021

ABSTRACT
Gametic frequencies were obtained in four natural populations of D. subobscura by extracting wild chromosomes and subsequently analyzing them for inversions and allozymes. The genes Lap and Pept-1, both located within the same inversions of chromosome 0, were found in striking nonrandom associations with them of the same kind and degree in all populations studied. On the contrary, the gene Acph, also located within the previously mentioned inversions, was found in linkage disequilibrium with them only in two populations and of opposite directions. This is also the case for the genes Est-9 and Hk, both located within chromosome E inversions. While the gene Est-9 was in strong linkage disequilibrium with the inversions, of the same kind and degree in all populations studied, Hk was found to be in linkage equilibrium.
Allele frequencies for the 29 genes studied do not show geographical variation except for the genes Lap, Pept-1 and Est-9, the ones found in linkage disequilibria with the geographically varying gene arrangements. Although mechanical or historical explanations for these equilibria cannot be ruled out, these data cannot be explained satisfactorily by the "middle gene explanation," which states that loci displaying such linkage disequilibria are the ones located near the break points of inversions, while the ones displaying linkage equilibria with them are located in the middle of them.
There is no evidence for consistent linkage disequilibria between pairs of loci, except for the closely linked genes of the complex locus, Est-9. This would imply, if it is not a peculiarity of the Est-9 complex, that the linkage disequilibria aye found only between very closely linked loci or that, far less closely linked genes, the associations are too weak to be detected by the usual samples sizes.
PROTOPLASMIC INCOMPATIBILITY IN PODOSPORA ANSERINA: A POSSIBLE ROLE FOR ITS ASSOCIATED PROTEOLYTIC ACTIVITY
Authors: Labarere Jacques , Bernet Jean 
Published: April 2021

ABSTRACT
A mutation (modD) was selected in a gene involved in the control of protoplasmic incompatibility. Previous results (LABARERE and BERNET 1979) showed that modD decreased the density of protoperithecia and caused a defect in ascospore germination. In addition, modD has a third defect: when modD stationary cells were isolated in order to obtain further development, renewal of growth rarely ensued. Instead, the modD cells lysed or produced microthalli from which normal growth never occurred. These defects were suppressed by β-phenyl pyruvic acid, a protease inhibitor, and by the presence of a mutation (modC) that suppresses the proteases associated with protoplasmic incompatibility. The stationary wild-type cells' regeneration was inhibited by β-phenyl pyruvic acid at levels that maintained modD cells' regeneration. These results suggest a biological role for the proteases associated with protoplasmic incompatibility.
UNIDIRECTIONAL GENE CONVERSION ASSOCIATED WITH TWO INSERTIONS IN NEUROSPORA CRASSA MITOCHONDRIAL DNA
Authors: Mannella Carmen A , Lambowitz Alan M 
Published: April 2021

ABSTRACT
The mitochondrial phenotype of [poky] and other extranuclear Neurospora mutants is known to predominate over that of wild type in hetero-plasmons. In the present work, we have investigated the interaction between wild-type and [poky] mtDNAs using as many as four physical markers to distinguish the two types of mtDNAs. Two insertions, one of 1200 bp in Eco RI-5 and the other 50 bp in Eco RI-9, are identified as sites of high frequency, unidirectional gene conversion leading to their spread through mtDNA populations in heteroplasmons. However, the transmission of the [poky] mutation does not appear to be correlated with the transmission of either of these insertions or of other physical markers. The possibility that other loci of nonreciprocal recombination might be responsible for the "dominance" of Neurospora extranuclear mutants is discussed.
GENETIC MODULATION OF RNA METABOLISM IN DROSOPHILA. IV. MEASUREMENT OF RATES OF RNA SYNTHESIS BY DENSITY LABELING
Authors: Strausbaugh Linda D , Clark Stephen H , Grainger Robert M 
Published: April 2021

ABSTRACT
Accumulation of RNA was measured in adult males of two genotypes: car bb/Ybb- and car bb/YbbSuvar-5. The two genotypes have similar amounts of rDNA, which is reduced in comparison to wild type (CLARK, STRAUSBAUGH and KIErm 1977). Although genotypically bobbed, car bb/YbbSuVar-5 flies have a wild-type phenotype; car bb/Ybb- flies are both phenotypically and genotypically bobbed (CLARK, STRAUSBAUGH and KIEFER 1977). The wild-type phenotype observed in the car bb/YbbsuVar-5 flies is thought to be the result of an increased rate of rRNA synthesis due ot the presence of the YbbSuVar-5 chromosome (SHERMOEN and KIFFER 1975; CLARK, STRAUSBAUGH and KIEFER 1977; CLARK and KIEFER 1977). To further define this phenomenon, the absolute accumulation of RNA was measured in the two genotypes, using density labeling methods. The accumulation of RNA is 1.4 to 1.8 times higher in car bb/YbbSuVar-5 flies than in car bb/Ybb- flies, demonstrating that there is genetic regulation of synthesis in this genotype. The use of density-labeled nucleosides has clearly shown that there is no difference in precusor pool sizes or use between the two genotypes studied.
IDENTIFICATION OF AN R-LOCUS REGION THAT CONTROLS THE TISSUE SPECIFICITY OF ANTHOCYANIN FORMATION IN MAIZE
Authors: Dooner Hugo K 
Published: April 2021

ABSTRACT
The R locus in maize controls the tissue specificity of anthocyanin formation. Recombination between two different R-locus alleles with unique pigmentation domains has resulted in the generation of a nonparental allelic type that displays a third kind of tissue specificity. These novel changes in tissue specificity occurred in very low frequency (1 x 10-5). In light of this finding and of recent results concerning the regulation by R of the enzyme UDPG: flavonoid 3-O-glucosyltransferase, specified by the Bz locus, a model dealing with the genetic control of tissue-specific functions in multicellular organisms is proposed.
ISOZYME POLYMORPHISM IN NATURAL POPULATIONS OF A LIVERWORT, PLAGIOCHILA ASPLENIOIDES
Authors: Krzakowa M , Szweykowski J 
Published: April 2021

ABSTRACT
Assays of five Polish populations of Plagiochila asplenioides (Hepaticae, Plagiochilaceae) for peroxidase isozymes revealed three bands differing in electrophoretic mobility. The phenotypes observed appear to be governed by three loci; each locus has two alleles, one of which produces a band and the other no band, i.e., the second allele is silent, or null. Marked variability in enzyme phenotypes was found both within and between populations. The evolutionary implications of this variability are discussed in terms of the persistent haplophase and ephemeral diplophase of this organism.
CYTOGENETIC ANALYSIS OF CHROMOSOME 3 IN DROSOPHILA MELANOGASTER: THE HOMOEOTIC GENE COMPLEX IN POLYTENE CHROMOSOME INTERVAL 84A-B
Authors: Kaufman Thomas C , Lewis Ricki , Wakimoto Barbara 
Published: April 2021

ABSTRACT
Cytogenetic evidence is presented demonstrating that the 84A-B interval in the proximal portion of the right arm of chromosome 3 is the residence of a homoeotic gene complex similar to the bithorax locus. This complex, originally defined by the Antennapedia (A n t p) mutation, controls segmentation in the anterior portion of the organism. Different lesions within this complex homoeotically transform portions OI the prothorax, proboscis, antenna and eye and present clear analogies to similar lesions within the bithorax locus.
THE STEPWISE MUTATION MODEL: AN EXPERIMENTAL EVALUATION UTILIZING HEMOGLOBIN VARIANTS
Authors: Fuerst Paul A , Ferrell Robert E 
Published: April 2021

ABSTRACT
The stepwise mutation model of OHTA and KIMURA (1973) was proposed to explain patterns of genetic variability revealed by means of electrophoresis. The assumption that electrophoretic mobility was principally determined by unit changes in net molecular charge has been criticized by JOHNSON (1974, 1977). This assumption has been tested directly using hemoglobin. Twenty-seven human hemoglobin variants with known amino acid substitutions, and 26 nonhuman hemoglobins with known sequences were studied by starch gel electrophoresis. Of these hemoglobin% 60 to 70% had electrophoretic mobilities that could be predicted solely on the basis of net charge calculated from the amino acid composition alone, ignoring tertiary structure. Only four hemoglobins showed a mobility that was clearly different from an expected mobility calculated using only the net charge of the molecule. For the remaining 30% of hemoglobins studied, mobility was determined by a combination. of net charge and other unidentified components, probably reflecting changes in ionization of some amino acid residues as a result of small alterations in tertiary structure due to the amino acid substitution in the variant. For the nonhuman hemoglobins, the deviation of a sample from its expected mobility increased with increasing amino acid divergence from human hemoglobin A.—It is concluded that the net electrostatic charge of a molecule is the principal determinant of electrophoretic mobility under the conditions studied. However, because of the significant deviation from strict stepwise mobility detected for 30 to 40% of the variants studied, it is further concluded that the infinite-allele model of KIMURA and CROW (1964) or a "mixed model" such as that proposed by LI (1976) may be more appropriate than the stepwise mutation model for the analysis of much of the available electrophoretic data from natural populations.
MATING-TYPE INHERITANCE AND MATURITY TIMES IN CROSSES BETWEEN SUBSPECIES OF TETRAHYMENA PIGMENTOSA
Authors: Simon Ellen M 
Published: April 2021

ABSTRACT
Subspecies 6 and 8 of T . pigmentosa (formerly syngens 6 and 8 of T . pyriformis) share a mating-type system controlled by three alleles with "peck-order'' dominance at a single locus. The system is apparently closed and limited to three mating types that are homologous, but not identical, in the subspecies. These relationships are reflected in new mating-type designations. —The viability in some intersyngenic crosses is excellent, and the inheritance of major mating types in first-generation hybrids and their progeny follows the pattern of subspecies 8.—The period of immaturity is shorter than that previously reported for subspecies 8, with 50% of the subclones maturing between 46 and 100 fissions after conjugation. Maturity curves are generally sigmoid, but some are apparently biphasic. The onset of maturity in triplicate sublines from the same synclone is usually highly correlated.
GENETIC MAPPING AND SOME CHARACTERIZATION OF THE rnpA49 MUTATION OF ESCHERICHIA COLI THAT AFFECTS THE RNA-PROCESSING ENZYME RIBONUCLEASE P
Authors: Apirion David 
Published: April 2021

ABSTRACT
A mutant defective in the enzyme RNase P was isolated by P. SCHEDL and P. PRIMAKOFF (1973). The mutation rnpA49 found in this strain, which confers temperature sensitivity on carrier strains, was mapped by conjugation and transduction experiments and located around minute 82 of the E . coli map, with the suggested order rnpA bglB phoS rbsP ilv. As expected, the rnpA49 mutation is recessive. Even though this mutation is conditional, it is manifested at temperatures at which the carrier strains can grow.
GENETIC EVIDENCE FOR INTERACTION BETWEEN NONHOMOLOGOUS PROTEINS IN YEAST AND A CASE OF SUPPRESSION AT THE HIS1 LOCUS
Authors: Snow Richard 
Published: April 2021

ABSTRACT
The HIS1 and THR4 loci are the structural genes for phosphoribosyl-ATP pyrophosphorylase and threonine synthetase, respectively. The allele his1-IS has no enzyme activity at 30", but does have activity at 15" provided the cell contains the wild-type THR4 allele or a suppressing allele at another locus, designated SUP(his1-1S). Under these conditions, cells with the hisl-IS mutation are capable of growth on minimal medium at 15". Three kinds of reversions of a hisl-IS thr4 sup(his1-IS) strain to histidine prototrophy have been obtained: (1) his1-IS locus reversions to HIS1 that restore growth without added histidine at 30", (2) thr4 reversions to THR4 that simultaneously eliminate the requirement for threonine and restore the low-temperature effect on the his1-IS allele, and (3)mutations from sup to SUP. The SUP allele is not an ochre suppressor, and it is not linked to either HISI, THR4 or a centromere. It may represent a missense suppressor. I t is proposed that the effect ofTHR4 is caused by aggregation of the wild-type threonine synthetase with defective his1-IS monomers, causing a favorable conformational change in the histidine protein that restores limited enzymatic activity. This can be regarded as a case of complementation between nonhomologous proteins.
PROPAGATION OF CORTICAL DIFFERENCES IN TETRAHYMENA
Authors: Frankel Joseph 
Published: April 2021

ABSTRACT
Progeny clones were derived froin crosses arranged so that the number of ciliary meridians (corticotype) was unusually high in one partner, and normal in the other. An analysis of the propagation of corticotypes during maintenance of these clones for up to 1,000 fissions indicated that corticotypos above 21 undergo a rapid downward shift, while corticotypes in the range of 18 to 21 change slowly. Although these observations are consistent with NANNEY'Sea rlier deduction of a "stability center" at corticotype 19, there appears to be little if any difference in the stability of perpetuation of corticotypes 18, 19 and 20. Within this "stability range," the inertia of maintenance of pre-existing corticotypes is sufficiently strong that sister clones derived from an exconjugant pair can remain different for 1,000 fissions. These findings are consistent with observations made earlier, and those in the present study, indicating that cells in stock cultures express a substantial range of corticotypes even when maintained with frequent transfer. The results suggest that mechanisms of spatially ordered structural assembly within the cell can show sufficient fidelity to allow long-term vegetative perpetuation of phenotypic differences without artificial selection.