bluuebunny/crossref_metadata_2025_split huggingface dataset:
Courtship Anomalies Caused by doublesex Mutations in Drosophila melanogaster
Authors: Villella Adriana , Hall Jeffrey C 
Published: January 2021

Abstract
The role played by the sex-deterrnining gene doublesex (dsx) and its influence on Drosophila courtship were examined. Against a background of subnormal male-like behavior that is reported to be an attribute of haplo-X flies homozygous for the original dsx mutation, and given that a sex-specific muscle is unaffected by genetic variation at this locus, analyses of several reproductive behaviors and control for genetic background effects indicated that XY dsx mutants are impaired in their willingness to court females. When they did court, certain behavioral actions were normal, including components of courtship song. However, these mutants never produced courtship humming sounds. Mature XY dsx flies elicited anomalously high levels of courtship; that this occurs merely because of a delay in imaginal development was experimentally discounted. The current analysis reconciled two ostensibly conflicting reports involving the courtship-stimulating qualities of this mutant type. Such experiments also uncovered a new behavioral anomaly: dsx mutations caused chromosomal males to court other males at abnormally high levels. These results are discussed from the perspective of doublesex's influence on internal tissues of adult Drosophila involved in the triggering and neural control of male- and female-like elements of courtship, reproductive pheromone production, or a combination of such factors.
The yl Gene of Maize Codes for Phytoene Synthase
Authors: Buckner Brent , Miguel Phillip San , Janick-Buckner Diane , Bennetzen Jeffrey L 
Published: January 2021

Abstract
The cloned yl locus of maize was sequenced and found to encode phytoene synthase. Different “wild-type” alleles of the locus were found to differ by the insertion of transposable elements in their promoter and polyA addition regions, and by the length of a CCA tandem repeat series, without any obvious effect on function of the gene. A dominant Yl (“wild-type”) allele was observed to be expressed at highest levels in the seedling but also in the embryo and endosperm. The Mu3 transposable element insertion responsible for a pastel allele of yl, which gives lowered levels of carotenoids in the endosperm of kernels and seedlings grown at high temperatures, was located in the 5′ end of the gene. Although the size of the transcript from this yl mutation suggests that the Mu3 element provides the promoter for this allele, leaf tissue in this mutant line contained approximately normal amounts of yl mRNA. A recessive allele of yl, which conditions normal levels of carotenoids in the embryo and seedling, but almost no carotenoids in the endosperm, was found to accumulate normal amounts of yl mRNA in the seedling and embryo, while yl transcripts were not detected in the endosperm.
A Generalization of the Mixture Model in the Mapping of Quantitative Trait Loci for Progeny From a Biparental Cross of Inbred Lines
Authors: Fisch R D , Ragot M , Gay G 
Published: January 2021

Abstract
The recent advent of molecular markers has created a great potential for the understanding of quantitative inheritance. In parallel to rapid developments and improvements in molecular marker technologies, biometrical models have been constructed, refined and generalized for the mapping of quantitative trait loci (QTL). However, current models present restricitions in terms of breeding designs to which they apply. In this paper, we develop an approach for the generalization of the mixture model for progeny from a single bi-parental cross of inbred lines. Detailed derivations are given for genetic designs involving populations developed by selfing, i.e., where marker genotypes are obtained from Fx (x ≤ 2) individuals and where phenotypes are measured on Fy (y ≥ x) individuals or families. Extensions to designs involving doubled-haploids, backcrossderived individuals and random matings are outlined. The derivations presented here can easily be combined with current QTL mapping approaches.
Establishing Genetic Interactions by a Synthetic Dosage Lethality Phenotype
Authors: Kroll Eugene S , Hyland Katherine M , Hieter Philip , Li Joachim J 
Published: January 2021

Abstract
We have devised a genetic screen, termed synthetic dosage lethality, in which a cloned “reference” gene is inducibly overexpressed in a set of mutant strains carrying potential “target” mutations. To test the specificity of the method, two reference genes, CTF13, encoding a centromere binding protein, and ORC6, encoding a subunit of the origin of replication binding complex, were overexpressed in a large collection of mutants defective in either chromosome segregation or replication. CTF13 overexpression caused synthetic dosage lethality in combination with ctf14-42 (cbf2, ndc10), ctf17-61 (ch14), ctf19-58 and ctf19-26. ORC6 overexpression caused synthetic dosage lethality in combination with cdc2-1, cdc6-l, cdc14-1, cdcl6-1 and cdc46-1. These relationships reflect specific interactions, as overexpression of CTF13 caused lethality in kinetochore mutants and overexpression of ORC6 caused lethality in replication mutants. In contrast, only one case of dosage suppression was observed. We suggest that synthetic dosage lethality identifies a broad spectrum of interacting mutations and is of general utility in detecting specific genetic interactions using a cloned wild-type gene as a starting point. Furthermore, synthetic dosage lethality is easily adapted to the study of cloned genes in other organisms.
Suppression Analysis Reveals a Functional Difference Between the Serines in Positions Two and Five in the Consensus Sequence of the C-Terminal Domain of Yeast RNA Polymerase II
Authors: Yuryev Anton , Corden Jeffry L 
Published: January 2021

Abstract
The largest subunit of RNA polymerase II contains a repetitive C-terminal domain (CTD) consisting of tandem repeats of the consensus sequence TyrlSer2Pro3Thr4Ser5Pro6Ser7. Substitution of nonphosphe rylatable amino acids at positions two or five of the Saccharomyces cerevisiae CTD is lethal. We developed a selection ssytem for isolating suppressors of this lethal phenotype and cloned a gene, SCA1 (suppressor of CTD alanine), which complements recessive suppressors of lethal multiple-substitution mutations. A partial deletion of SCA1 (sca1Δ::hisG) suppresses alanine or glutamate substitutions at position two of the consensus CTD sequence, and a lethal CTD truncation mutation, but SCA1 deletion does not suppress alanine or glutamate substitutions at position five. SCA1 is identical to SRB9, a suppressor of a cold-sensitive CTD truncation mutation. Strains carrying dominant SRB mutations have the same suppression properties as a sca1Δ::hisG strain. These results reveal a functional difference between positions two and five of the consensus CTD heptapeptide repeat. The ability of SCA1 and SRB mutant alleles to suppress CTD truncation mutations suggest that substitutions at position two, but not at position five, cause a defect in RNA polymerase II function similar to that introduced by CTD truncation.
Meiotic Recombination Initiated by a Double-Strand Break in rad50Δ Yeast Cells Otherwise Unable to Initiate Meiotic Recombination
Authors: Malkova A , Ross L , Dawson D , Hoekstra Merl F , Haber J E 
Published: January 2021

Abstract
Meiotic recombination in Saccharomyces cerevisiae is initiated by double-strand breaks (DSBs). We have developed a system to compare the properties of meiotic DSBs with those created by the site-specific HO endonuclease. HO endonuclease was expressed under the control of the meiotic-specific SPO13 promoter, creating a DSB at a single site on one of yeast's 16 chromosomes. In Rad+ strains the times of appearance of the HO-induced DSBs and of subsequent recombinants are coincident with those induced by normal meiotic DSBs. Physical monitoring of DNA showed that SPO13::HO induced gene conversions both in Rad+ and in rad50Δ cells that cannot initiate normal meiotic DSBs. We find that the RAD50 gene is important, but not essential, for recombination even after a DSB has been created in a meiotic cell. In rad50Δ cells, some DSBs are not repaired until a broken chromosome has been packaged into a spore and is subsequently germinated. This suggests that a broken chromosome does not signal an arrest of progression through meiosis. The recombination defect in rad50Δ diploids is not, however, meiotic specific, as mitotic rad50 diploids, experiencing an HO-induced DSB, exhibit similar departures from wild-type recombination.
DLH1 is a Functional Candida albicans Homologue of the Meiosis-Specific Gene DMC1
Authors: Diener Andrew C , Fink Gerald R 
Published: January 2021

Abstract
DMC1/LIM15 homologue 1 (DLH1), a gene related to meiosis-specific genes, has been isolated from Candida albicans, a fungus thought not to undergo meiosis. The deduced protein sequence of DLH1 contains 74% amino acid identity with Dmclp from Saccharomyces cermisiae and 63% with Liml5p from the plant Lilium long)lmm, meiosisspecific homologues of Escherichia coli RecA. Candida DLH1 complements a dmcl/dmcl null mutant in S. cermisiae: High copy expression of DLH1 restores both sporulation and meiotic recombination to a Saccharomyces dmclΔ/dmclΔ strain. Unlike the DMCl gene, which is transcribed only in meiotic cells, the heterologous Candida DLH1 gene is transcribed in both vegetative and meiotic cells of S. cermisiae. Transcription of DLH1 is not detected or induced in C. albicans under conditions that induce DMC1 and meiosis in S. cermisiae. The presence of an intact homologue of a meiosis-specific gene in C. albicans raises the possibility that this organism has a cryptic meiotic pathway.
Genetic Map of Diploid Wheat, Triticum monococcum L., and Its Comparison With Maps of Hordeum vulgare L.
Authors: Dubcovsky Jorge , Luo Ming-Cheng , Zhong Gan-Yuan , Bransteitter Ronda , Desai Amrita , Kilian Andrzej , Kleinhofs Andris , Dvořák Jan 
Published: January 2021

Abstract
A genetic map of diploid wheat, Triticum monococcum L., involving 335 markers, including RFLP DNA markers, isozymes, seed storage proteins, rRNA, and morphological loci, is reported. T. monococcum and barley linkage groups are remarkably conserved. They differ by a reciprocal translocation involving the long arms of chromosomes 4 and 5, and paracentric inversions in the long arm of chromosomes 1 and 4; the latter is in a segment of chromosome arm 4L translocated to 5L in T. monococcum. The order of the markers in the inverted segments in the T. monococcum genome is the same as in the B and D genomes of T. aestivum L. The T. monococcum map differs from the barley maps in the distribution of recombination within chromosomes. The major 5s rRNA loci were mapped on the short arms of T. monococcum chromosomes 1 and 5 and the long arms of barley chromosomes 2 and 3. Since these chromosome arms are colinear, the major 5s rRNA loci must be subjected to positional changes in the evolving Triticeae genome that do not perturb chromosome colinearity. The positional changes of the major 5s rRNA loci in Triticeae genomes are analogous to those of the 18S5.8S26S rRNA loci.
A Genetic Analysis of pannier, a Gene Necessary for Viability of Dorsal Tissues and Bristle Positioning in Drosophila
Authors: Heitzler Pascal , Haenlin Marc , Ramain Philippe , Calleja Manuel , Simpson Pat 
Published: January 2021

Abstract
A genetic and phenotypic analysis of the gene pannier is described. Animals mutant for strong alleles die as embryos in which the cells of the amnioserosa are prematurely lost. This leads to a dorsal cuticular hole. The dorsal-most cells of the imagos are also affected: viable mutants exhibit a cleft along the dorsal midline. pannier mRNA accumulates specifically in the dorsal-most regions of the embryo and the imaginal discs. Viable mutants and mutant combinations also affect the thoracic and head bristle patterns in a complex fashion. Only those bristles within the area of expression of pannier are affected. A large number of alleles have been studied and reveal that pannier may have opposing effects on the expression of achaete and scute leading to a loss or a gain of bristles.
The Broom of the Sorcerer's Apprentice: The Fine Structure of a Chromosomal Region Causing Reproductive Isolation Between Two Sibling Species of Drosophila
Authors: Davis Andrew W , Wu Chug-I 
Published: January 2021

Abstract
How many genes contribute to reproductive isolation between closely related species? We determined the number of genes located in the 9D-12B region of the Drosophila mauritiana X chromosome that cause hybrid male sterility in a D. simulans background. Previous low resolution studies suggested that a single hybrid sterility factor was associated with this region. In this study, by taking advantage of a cluster of visible and DNA markers, we identified three D. mauritiana factors in this region and then subjected one of them to detailed analysis. This factor again turned out to be comprised of three factors; one of which, mapped to within 200 kb, may in fact be two factors. The title refers to this exercise of splitting sterile introgressions into ever smaller ones, each of which retains partial or full sterility effects. In a region representing a mere 3% of the Drosophila genome, no fewer than six loci of hybrid sterility were identified between two sibling species that have not shown clear divergence at the molecular level. These results suggest that levels of genetic divergence between closely related species may be quite high for functionally important traits even when the opposite is true for randomly chosen loci.
Speciation by Reinforcement: A Model Derived from Studies of Drosophila
Authors: Kelly John K , Noor Mohamed A F 
Published: January 2021

Abstract
Reinforcement is an increase in premating reproductive isolation between taxa resulting from selection against hybrids. We present a model of reinforcement with a novel type of selection on female mating behavior. Previous models of reinforcement have focused on the divergence of female mating preferences between nascent species. We suggest that an increase in the level of female mating discrimination can yield reinforcement without further divergence of either male characters or female preferences. This model indicates that selection on mating discrimination is a viable mechanism for reinforcement and may allow speciation under less stringent conditions than selection on female preference. This model also incorporates empirical results from genetic studies of hybrid fitness determination in Drosophila species. We find that the details of inheritance, which include sex-linked transmission, sex-limited fertility reduction, and X-autosome epistasis, have important effects on the likelihood of reinforcement. In particular, X-autosome epistasis for hybrid fitness determination facilitates reinforcement when hybrid fertility reduction occurs in males, but hinders the process when it occurs in females. Haldane's rule indicates that hybrid sterility will generally evolve in males prior to females within nascent species. Thus, Haldane's rule and X-autosome epistasis provide conditions that are surprisingly favorable for reinforcement in Drosophila.
Repair of Double-Strand Breaks in Bacteriophage T4 by a Mechanism That Involves Extensive DNA Replication
Authors: George James W , Kreuzer Kenneth N 
Published: January 2021

Abstract
We investigated double-strand break (dsb) repair in bacteriophage T4 using a physical assay that involves a plasmid substrate with two inverted DNA segments. A dsb introduced into one repeat during a T4 infection induces efficient dsb repair using the second repeat as a template. This reaction is characterized by the following interesting features. First, the dsb induces a repair reaction that is directly coupled to extensive plasmid replication; the repaired/replicated product is in the form of long plasmid concatemers. Second, repair of the dsb site is frequently associated with exchange of flanking DNA. Third, the repair reaction is absolutely dependent on the products of genes uvsX, uusY, 32, 46, and 59, which are also required for phage genomic recombination-dependent DNA replication. Fourth, the coupled repair/replication reaction is only partly dependent on endonuclease VII (gp49), suggesting that either another Holliday-junction-cleaving activity or an alternate resolution pathway is active during T4 infections. Because this repair reaction is directly coupled to extensive replication, it cannot be explained by the Szostak et al. model. We present and discuss a model for the coupled repair/replication reaction, called the extensive chromosome replication model for dsb repair.
Isolation of Degradation-Deficient Mutants Defective in the Targeting of Fructose-1,6-bisphosphatase into the Vacuole for Degradation in Saccharomyces cerevisiae
Authors: Hoffman Mark , Chiang Hui-Ling 
Published: January 2021

Abstract
The key regulatory enzyme in the gluconeogenesis pathway, fructose-1,6-bisphosphatase (FBPase), is induced when Saccharomyces cerevisiae are grown in medium containing a poor carbon source. FBPase is targeted to the yeast vacuole for degradation when glucose-starved cells are replenished with fresh glucose. To identify genes involved in the FBPase degradation pathway, mutants that failed to degrade FBPase in response to glucose were isolated using a colony-blotting procedure. These vacuolar import and degradation-deficient (vid) mutants were placed into 20 complementation groups. They are distinct from the known sec, ups or pep mutants affecting protein secretion, vacuolar sorting and vacuolar proteolysis in that they sort CpY correctly and regulate osmotic pressure normally. Despite the presence of FBPase antigen in these mutants, FBPase is completely inactivated in all uid mutants, indicating that the c-AMP-dependent signal transduction pathway and inactivation must function properly in vid mutants. vid mutants block FBPase dzgradation by accumulating FBPase in the cytosol and also in small vesicles in the cytoplasm. FBPase may be targeted to small vesicles before uptake by the vacuole.
The Product of the het-C Heterokaryon Incompatibility Gene of Neurospora crassa Has Characteristics of a Glycine-Rich Cell Wall Protein
Authors: Saupe Sven J , Kuldau Gretchen A , Smith Myron L , Glass N Louise 
Published: January 2021

Abstract
Filamentous fungi are capable of hyphal fusion, but heterokaryon formation between different isolates is controlled by specific loci termed het loci. Heterokaryotic cells formed between strains of different het genotype are rapidly destroyed or strongly inhibited in their growth. In Neurospora crassa, at least 11 loci, including the mating type locus, affect the capacity to form a heterokaryon between different isolates. In this report, we describe the molecular characterization of the vegetative incompatibility locus, het-C. The het-COR allele was cloned by genetically identifying the het-C locus in a chromosome walk, and the activity of clones containing the het-COR allele was tested in a functional transformation assay. The het-COR allele encodes a 966amino acid polypeptide with a putative signal peptide, a coiled-coil motif and a Gterminal glycine-rich domain, similar to glycine-rich domains detected in various extracellular and structural cell envelope proteins. Both the coiled-coil and one-third of the glycine-rich carboxyl terminal domains were required for full het-COR activity. Mutants of het-COR were obtained by repeat-induced point mutation (RIP) ; these mutants were indistinguishable from wild type during vegetative growth and sexual reproduction hut displayed dual compatibility with both of two mutually incompatible het-COR and het-cPA strains.
The Regulatory Properties of Autonomous Subtelomeric P Elements Are Sensitive to a Suppressor of variegation in Drosophila melanogaster
Authors: Ronsseray Stéphane , Lehmann Monique , Nouaud Danielle , Anxolabéhère Dominique 
Published: January 2021

Abstract
Genetic recombination was used in Drosophila melanogaster to isolate P elements, inserted at the telomeres of X chromosomes (cytological site 1A) from natural populations, in a genetic background devoid of other P elements. We show that complete maternally inherited P repression in the germline (P cytotype) can be elicited by only two autonomous P elements at 1A and that a single element at this site has partial regulatory properties. The analysis of the surrounding chromosomal regions of the P elements at 1A shows that in all cases these elements are flanked by Telomeric Associated Sequences, tandemly repetitive noncoding sequences that have properties of heterochromatin. In addition, we show that the regulatory properties of P elements at 1A can be inhibited by some of the mutant alleles of the Su(var)205 gene and by a deficiency of this gene. However, the regulatory properties of reference P strains (Harwich and Texas 007) are not impaired by Su(var)205 mutations. Su(var)205 encodes Heterochromatin Protein 1 (HP1). These results suggest that the HP1 dosage effect on the P element properties is sitedependent and could involve the structure of the chromatin.
Rapid Evolution of a Coadapted Gene Complex: Evidence From the Segregation Distorter (SD) System of Meiotic Drive in Drosophila melanogaster
Authors: Palopoli Michael F , Wu Chung-I 
Published: January 2021

Abstract
Segregation Distorter (SD) is a system of meiotic drive found in natural populations of Drosophila melanogaster. Males heterozygous for an SD second chromosome and a normal homologue (SD +) produce predominantly SD-bearing sperm. The coadapted gene complex responsible for this transmission advantage spans the second chromosome centromere, consisting of three major and several minor interacting loci. To investigate the evolutionary history of this system, we surveyed levels of polymorphism and divergence at six genes that together encompass this pericentromeric region and span seven map units. Interestingly, there was no discernible divergence between SD and SD + chromosomes for any of these molecular markers. Furthermore, SD chromosomes harbored much less polymorphism than did SD + chromosomes. The results suggest that the SD system evolved recently, swept to appreciable frequencies worldwide, and carried with it the entire second chromosome centromeric region (roughly 10% of the genome). Despite its well-documented genetic complexity, this coadapted system appears to have evolved on a time scale that is much shorter than can be gauged using nucleotide substitution data. Finally, the large genomic region hitchhiking with SD indicates that a multilocus, epistatically selected system could affect the levels of DNA polymorphism observed in regions of reduced recombination.