scholarly journals Analysis of a Strong Suppressor of Segregation Distorter in Drosophila melanogaster

Genetics ◽  
2020 ◽  
Vol 215 (4) ◽  
pp. 1085-1105 ◽  
Author(s):  
Rayla Greenberg Temin
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Populations ◽  
Drive System ◽  
Deletion Mapping ◽  
Naturally Occurring ◽  
New Information ◽  
The Stability ◽  
Insight Into ◽  
Mendelian Transmission

Segregation Distorter (SD) is a naturally occurring male meiotic drive system in Drosophila melanogaster, characterized by almost exclusive transmission of the SD chromosome owing to dysfunction of sperm receiving the SD+ homolog. Previous studies identified at least three closely linked loci on chromosome 2 required for distortion: Sd, the primary distorting gene; E(SD) (Enhancer of SD), which increases the strength of distortion; and Rsp (Responder), the apparent target of Sd. Strength of distortion is also influenced by linked upward modifiers including M(SD) (Modifier of SD) and St(SD) (Stabilizer of SD), and by various unlinked suppressors. Although Sd is known to encode a mutant RanGAP protein, none of the modifiers have been molecularly identified. This work focuses on the genetic and cytological characterization of a strong X-linked suppressor, Su(SD), capable of restoring Mendelian transmission in SD/SD+ males. Sd and its cohort of positive modifiers appear to act semiquantitatively in opposition to Su(SD) with distortion strength depending primarily on the total number of distorting elements rather than which particular elements are present. Su(SD) can also suppress male sterility observed in certain SD genotypes. To facilitate its eventual molecular identification, Su(SD) was localized by deletion mapping to polytene region 13C7-13E4. These studies highlight the polygenic nature of distortion and its dependence on a constellation of positive and negative modifiers, provide insight into the stability of Mendelian transmission in natural populations even when a drive system arises, and pave the way for molecular characterization of Su(SD) whose identity should reveal new information about the mechanism of distortion.

Genetic location and biochemical characterization of eye-colour mutants from natural populations of Drosophila melanogaster

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 203-208 ◽  
Author(s):  
M. Luisa Aparisi ◽  
Carmen Nájera
Keyword(s):  
Drosophila Melanogaster ◽  
Biochemical Characterization ◽  
Natural Populations ◽  
High Variability ◽  
Genetic Location ◽  
Eye Colour ◽  
Different Seasons ◽  
Allelism Tests ◽  
Mutation And Selection

From six captures of Drosophila melanogaster carried out in three different habitats (cellar, vineyard, and pinewood) in two different seasons of the year (spring and autumn), 60 eye-colour mutations were isolated, which were reduced to 29 loci by means of allelism tests within and between populations. Forty-five of these mutations were analyzed genetically and biochemically; of these 33 turned out to be previously described mutants and mapped to a total of 17 loci. Twelve new mutants were discovered and they mapped to 12 new loci, distributed on chromosomes X, II, and III. The eye-colour mutants show large effects on the red and brown pigments. The high variability of the eye-colour loci is discussed in relation to the mutation and selection hypotheses.Key words: eye-colour mutants, variability, mapping, Drosophila melanogaster, pigment patterns.

THE ANATOMY AND FUNCTION OF A SEGMENT OF THE X CHROMOSOME OF DROSOPHILA MELANOGASTER

Genetics ◽  
1972 ◽  
Vol 71 (1) ◽  
pp. 139-156
Author(s):  
B H Judd ◽  
M W Shen ◽  
T C Kaufman
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Functional Group ◽  
Deletion Mapping ◽  
Mutant Type ◽  
Functional Units ◽  
Average Size ◽  
And Function

ABSTRACT An average size chromomere of the polytene X chromosome of Drosophila melanogaster contains enough DNA in each haploid equivalent strand to code for 30 genes, each 1,000 nucleotides long. We have attempted to learn about the organization of chromosomes by asking how many functional units can be localized within a chromomere. This was done by 1) recovery of mutants representative of every cistron in the 3A2-3C2 region; 2) the characterization of the function of each mutant type and grouping by complementation tests; 3) the determination of the genetic and cytological position of each cistron by recombination and deletion mapping. The data clearly show one functional group per chromomere. It is postulated that a chromomere is one cistron within which much of the DNA is regulatory in function.

scholarly journals Characterization of natural populations of Drosophila melanogaster with regard to the hobo system: a new hypothesis on the invasion

1997 ◽  
Vol 69 (3) ◽  
pp. 197-208 ◽  
Author(s):  
ERIC BONNIVARD ◽  
DOMINIQUE HIGUET ◽  
CLAUDE BAZIN
Keyword(s):  
Drosophila Melanogaster ◽  
Reference Strain ◽  
Natural Populations ◽  
Hybrid Dysgenesis ◽  
Molecular Characteristics ◽  
Male Recombination ◽  
System A ◽  
Genetic Level ◽  
New Hypothesis

Until now, with regard to the hobo system of hybrid dysgenesis, natural populations of Drosophila melanogaster have been investigated using only two criteria: at the molecular level, the presence or absence of XhoI fragments 2·6 kb long or smaller; and/or at the genetic level, the ability to induce gonadal dysgenesis sterility in crosses A (females of an E reference strain crossed with males under test) and A* (females under test crossed with males of an H reference strain). Recently, analyses of laboratory strains using these criteria as well as the mobilization of two reporter genes, the male recombination and the number of ‘TPE’ repeats in the S region, revealed a lack of correlation between the different dysgenic parameters themselves, and also between these parameters and the molecular characteristics of the strains. Thirteen current strains derived from world populations were therefore investigated with regard to all these dysgenic traits, to determine discriminating criteria providing a robust method of classifying natural populations and deducing the dynamics of hobo elements in these populations. We show, as in laboratory strains, a lack of correlation between the parameters studied. Therefore, the significance of each of them as well as the nature of hobo hybrid dysgenesis are discussed, to propose an analysis method of the hobo system applicable to natural populations. According to the geographical distribution of hobo activities in world populations and to the variable polymorphism of the number of ‘TPE’ repeats, we propose a new scenario for the invasion of D. melanogaster by hobo elements.

scholarly journals Lack of underdominance in a naturally occurring pericentric inversion in Drosophila melanogaster and its implications for chromosome evolution.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 791-802
Author(s):  
J A Coyne ◽  
S Aulard ◽  
A Berry
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Selection ◽  
Genetic Drift ◽  
Related Species ◽  
Pericentric Inversion ◽  
Chromosome Evolution ◽  
Natural Populations ◽  
Crossing Over ◽  
Closely Related Species ◽  
Naturally Occurring

Abstract In(2LR)PL is a large pericentric inversion polymorphic in populations of Drosophila melanogaster on two Indian Ocean islands. This polymorphism is puzzling: because crossing over in female heterokaryotypes produces inviable zygotes, such inversions are thought to be underdominant and should be quickly eliminated from populations. The observed fixation for such inversions among related species has led to the idea that genetic drift can cause chromosome evolution in opposition to natural selection. We found, however, that In(2LR)PL is not underdominant for fertility, as heterokaryotypic females produce perfectly viable eggs. Genetic analysis shows that the lack of underdominance results from the nearly complete absence of crossing over in the inverted region. This phenomenon is probably caused by mechanical and not genetic factors, because crossing over is not suppressed in In(2LR)PL homokaryotypes. Our observations do not support the idea that the fixation of pericentric inversions among closely related species implies the action of genetic drift overcoming strong natural selection in very small populations. If chromosome arrangements vary in their underdominance, it is those with the least disadvantage as heterozygotes, like In(2LR)PL, that will be polymorphic or fixed in natural populations.

scholarly journals CHARACTERIZATION OF ALLOZYME NULL AND LOW ACTIVITY ALLELES FROM TWO NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1984 ◽  
Vol 107 (2) ◽  
pp. 295-306
Author(s):  
Barbara Dickson Burkhart ◽  
Elizabeth Montgomery ◽  
Charles H Langley ◽  
Robert A Voelker
Keyword(s):  
Enzyme Activity ◽  
Drosophila Melanogaster ◽  
Transposable Element ◽  
Natural Populations ◽  
Biochemical Properties ◽  
Chromosome Rearrangements ◽  
Regulatory Sequences ◽  
Interallelic Complementation ◽  
Low Activity

ABSTRACT Null and low enzyme activity alleles recovered from two natural populations were analyzed for a number of genetic and biochemical properties. Analysis of 58 mutations at 14 loci showed that all but one allele were genetically viable and fertile, four alleles were associated with chromosome rearrangements, 28 alleles retained some enzyme activity, 13 alleles formed an active heterodimer with active alleles and five alleles showed partial interallelic complementation. Available evidence indicates that this sample includes mutations resulting from lesions in both coding and regulatory sequences. Certain mutations may be caused by transposable element insertions.

scholarly journals Identification and Characterization of Breakpoints and Mutations on Drosophila melanogaster Balancer Chromosomes

2020 ◽  
Vol 10 (11) ◽  
pp. 4271-4285 ◽  
Author(s):  
Danny E. Miller ◽  
Lily Kahsai ◽  
Kasun Buddika ◽  
Michael J. Dixon ◽  
Bernard Y. Kim ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Repetitive Sequences ◽  
Intestinal Cell ◽  
Induced Mutations ◽  
Telomeric Sequences ◽  
Long Read ◽  
The Stability ◽  
Induced Apoptosis ◽  
Balancer Chromosomes

Balancers are rearranged chromosomes used in Drosophila melanogaster to maintain deleterious mutations in stable populations, preserve sets of linked genetic elements and construct complex experimental stocks. Here, we assess the phenotypes associated with breakpoint-induced mutations on commonly used third chromosome balancers and show remarkably few deleterious effects. We demonstrate that a breakpoint in p53 causes loss of radiation-induced apoptosis and a breakpoint in Fucosyltransferase A causes loss of fucosylation in nervous and intestinal tissue—the latter study providing new markers for intestinal cell identity and challenging previous conclusions about the regulation of fucosylation. We also describe thousands of potentially harmful mutations shared among X or third chromosome balancers, or unique to specific balancers, including an Ankyrin 2 mutation present on most TM3 balancers, and reiterate the risks of using balancers as experimental controls. We used long-read sequencing to confirm or refine the positions of two inversions with breakpoints lying in repetitive sequences and provide evidence that one of the inversions, In(2L)Cy, arose by ectopic recombination between foldback transposon insertions and the other, In(3R)C, cleanly separates subtelomeric and telomeric sequences and moves the subtelomeric sequences to an internal chromosome position. In addition, our characterization of In(3R)C shows that balancers may be polymorphic for terminal deletions. Finally, we present evidence that extremely distal mutations on balancers can add to the stability of stocks whose purpose is to maintain homologous chromosomes carrying mutations in distal genes. Overall, these studies add to our understanding of the structure, diversity and effectiveness of balancer chromosomes.

scholarly journals The relative conformational stability of the alcohol dehydrogenase alleloenzymes of the fruitfly Drosophila melanogaster

1981 ◽  
Vol 197 (1) ◽  
pp. 111-117 ◽  
Author(s):  
D R Thatcher ◽  
R Sheikh
Keyword(s):  
Drosophila Melanogaster ◽  
Alcohol Dehydrogenase ◽  
Conformational Stability ◽  
Effect Of Temperature ◽  
Net Charge ◽  
Subunit Dissociation ◽  
Naturally Occurring ◽  
Transverse Temperature ◽  
The Stability ◽  
Temperature Optima

The effect of temperature on four purified alleloenzymes of the alcohol dehydrogenase (Adhs, Adhf, AdhD and Adhn-5) of the fruitfly Drosophila melanogaster was investigated in detail. Initial-velocity studies showed that the naturally occurring Adhf and Adhs enzymes differed only in their temperature optima, and evidence of kinetic adaptation to high and low temperature was not apparent. All four alleloenzymes denatured irreversibly on heating purified enzyme solutions at pH 6.0. This technique revealed only small differences in thermostability between Adhf and Adhs, although the two mutant enzymes from AdhD and Adhn-5 were considerably more labile. Electrophoresis of the enzymes though a stable transverse temperature gradient proved to be a discriminating and reproducible technique. Enzymes of different net charge were compared on the same polyacrylamide gel. The Adhf enzyme was shown to be significantly less stable than the Adhs enzyme. Subunit interchange was observed at temperatures below the point at which the unfolding occurred. At pH 4.0, the Adhf/Adhs heterodimer was as stable as the Adhs homodimeric enzyme, and more stable than the Adhf homodimer. Adhn-5 and AdhD alleloenzymes were relatively thermolabile. The stability of the alleloenzymes towards urea denaturation was studied by urea-gradient electrophoresis. Only small differences in stability between the Adhf and Adhs enzymes were observed. The AdhD and Adhn-5 mutants were denatured at the same urea concentration, which was much lower than in the case of the wild-type enzymes. Except at pH 4.0, subunit dissociation could not be distinguished from the unfolding of the monomer.

scholarly journals The Role of Hydraulic Hysteresis on the Hydrological Response of Pyroclastic Silty Covers

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 628 ◽  
Author(s):  
Guido Rianna ◽  
Luca Comegna ◽  
Luca Pagano ◽  
Luciano Picarelli ◽  
Alfredo Reder
Keyword(s):  
Slope Failure ◽  
Hysteretic Behavior ◽  
Recent Experience ◽  
Hydrological Response ◽  
Hydraulic Hysteresis ◽  
The Stability ◽  
Hydrological Effects ◽  
Insight Into

A significant part of the recent geotechnical literature concerning pyroclastic soils is focused on the characterization of the hydrological effects of precipitations and their implications for the stability conditions of unsaturated sloping covers. Recent experience shows that suction-induced strength reduction is influenced by various factors including hydraulic hysteresis. A deeper insight into the hysteretic water retention behavior of these materials and its effects upon their response to dry/wetting conditions is a major goal of this paper, which exploits the data provided by the monitoring of a volcanic ash. Based on the parameters retrieved from data calibration, the hydrological response of a virtual slope subject to one-dimensional rainfall infiltration is investigated by numerical analyses and compared with the results obtained through the usually adopted non-hysteretic approaches. The analysis demonstrates that considering the hysteretic behavior may be crucial for a proper evaluation of the conditions leading to slope failure.

Preparation and Characterization of Genipin-Crosslinked Chitosan Microspheres for the Sustained Release of Salidroside

2015 ◽  
Vol 11 (3) ◽  
pp. 323-333 ◽  
Author(s):  
Mei Luo ◽  
Hailong Peng ◽  
Zhonghua Deng ◽  
Zhonghua Yin ◽  
Qiang Zhao ◽  
...  
Keyword(s):  
Sustained Release ◽  
Functional Foods ◽  
Anomalous Behavior ◽  
Fickian Diffusion ◽  
Release Behavior ◽  
Chitosan Microspheres ◽  
Naturally Occurring ◽  
The Stability

Abstract Chitosan microspheres (CsMs) that encapsulate salidroside (Sal) were prepared by the emulsion crosslinking method with naturally occurring genipin (Gp) and then examined for their in vitro release. Sal-loaded CsMs (Sal-CsMs) showed nearly spherical and smooth surfaces with internal voids. The particle size of Sal-CsMs ranged within 0.56–5.01 μm, and their encapsulation efficiency and loading capacity were beyond 77.58% and 23.29%, respectively. The stability of Sal improved after entrapment into the CsMs. The release rate of Sal from CsMs was initially rapid, followed by sustained release. The release behavior depended on the pH of the release medium. The main release mechanisms underlying the release procedure were anomalous behavior and Fickian diffusion. These results indicated that CsMs with a novel crosslinker of Gp was a potential carrier system for producing functional foods containing Sal.

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