FURTHER CHARACTERIZATION OF GENETIC ELEMENTS ASSOCIATED WITH THE SEGREGATION DISTORTER PHENOMENON IN DROSOPHILA MELANOGASTER

Genetics ◽  
1985 ◽  
Vol 110 (4) ◽  
pp. 671-688
Author(s):  
Cecil B Sharp ◽  
Arthur J Hilliker ◽  
David G Holm
Keyword(s):  
Drosophila Melanogaster ◽  
Chromosome 2 ◽  
Major Focus ◽  
Genetic Components ◽  
Segregation Distorter ◽  
Crossover Analysis ◽  
Radiation Induced ◽  
Definition Of ◽  
The Right

ABSTRACT Segregation Distorter, SD, associated with the second chromosome of Drosophila melanogaster, is known to cause sperm bearing the non-SD homologue to dysfunction in heterozygous males. In earlier studies, using different, independently derived, SD chromosomes, three major loci were identified as contributing to the distortion of segregation ratios in males. In this study the genetic components of the SD-5 chromosome have been the subjects of further investigation, and our findings offer the following information. Crossover analysis confirms the mapping of the Sd locus to a position distal to but closely linked with the genetic marker pr. Spontaneous and radiation-induced recombinational analyses and deficiency studies provide firm support to the notion that the Rsp(Responder) locus lies within the proximal heterochromatin of chromosome 2, between the genetic markers lt and rl and most likely in the heterochromatin of the right arm. The major focus of this study, however, has been on providing a better definition of the genetic properties of the Enhancer of SD [E(SD)]. Our findings place this locus within the region of the two most proximal essential genes in the heterochromatin of the left arm of chromosome 2. Moreover, our analysis reveals a probable association of the E(SD) locus with a meiotic drive independent of that caused by Sd.

scholarly journals ON THE COMPONENTS OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1977 ◽  
Vol 86 (2) ◽  
pp. 321-355
Author(s):  
Barry Ganetzky
Keyword(s):  
Drosophila Melanogaster ◽  
Segregation Distortion ◽  
Meiotic Drive ◽  
Chromosome 2 ◽  
Induced Mutations ◽  
Distorted Segregation ◽  
X Ray ◽  
Naturally Occurring ◽  
Segregation Distorter

ABSTRACT The segregation distorter (SD) complex is a naturally occurring meiotic drive system with the property that males heterozygous for an SD-bearing chromosome 2 and an SD  +-bearing homolog transmit the SD-bearing chromosome almost exclusively. This distorted segregation is the consequence of an induced dysfunction of those sperm that receive the SD  + homolog. From previous studies, two loci have been implicated in this phenomenon: the Sd locus which is required to produce distortion, and the Responder (Rsp) locus that is the site at which Sd acts. There are two allelic alternatives of Rsp—sensitive (Rspsens) and insensitive (Rspins); a chromosome carrying Rspins is not distorted by SD. In the present study, the function and location of each of these elements was examined by a genetic and cytological characterization of X-ray-induced mutations at each locus. The results indicate the following: (1) the Rsp locus is located in the proximal heterochromatin of 2R; (2) a deletion for the Rsp locus renders a chromosome insensitive to distortion; (3) the Sd locus is located to the left of pr(2-54.5), in the region from 37D2-D7 to 38A6-B2 of the salivary chromosome map; (4) an SD chromosome deleted for Sd loses its ability to distort; (5) there is another important component of the SD system, E(SD), in or near the proximal heterochromatin of 2L, that behaves as a strong enhancer of distortion. The results of these studies allow a reinterpretation of results from earlier analyses of the SD system and serve to limit the possible mechanisms to account for segregation distortion.

scholarly journals A NOTE ON THE MATERNAL EFFECT MUTANTS DAUGHTERLESS AND ABNORMAL OOCYTE IN DROSOPHILA MELANOGASTER

Genetics ◽  
1973 ◽  
Vol 73 (1) ◽  
pp. 73-86
Author(s):  
Arthur P Mange ◽  
L Sandler
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Sex Chromosome ◽  
Chromosome 2 ◽  
Dominant Marker ◽  
Enhancing Effect ◽  
X Irradiation ◽  
The Right ◽  
Chromosome Breakpoint ◽  
Special Region

ABSTRACT Two deficiencies for, and a dominant enhancer of, the second chromosome maternal effect mutant, "daughterless" (da), were induced with X-irradiation. Their properties were studied with respect to both da and the linked maternal effect mutant, "abnormal oocyte" (abo), with the following conclusions. (1) The most probable map positions of da and abo are: J–½–da–2½–abo, where J is a dominant marker located at 41 on the standard map. (2) The da locus is in bands 31CD-F on the polytene chromosome map; abo is to the right of 32A. (3) Because homozygous da individuals survive while individuals carrying da and a deficiency for da are lethal, it is concluded that da is hypomorphic. (4) From a weak da-like maternal effect in heterozygous da females induced by an "Enhancer of da," we have confirmed a previous report that (a) the amount of sex chromosome heterochromatin contributed by the father can influence the severity of the da maternal effect, and (b) the sex chromosome heterochromatin which influences the da effect is different from that which influences the abo effect. (5) The possibility that da and abo are in a special region of chromosome 2 concerned with the regulation of sex chromosome heterochromatin is strengthened by the observation that the Enhancer of da appears to rescue abnormal eggs produced by homozygous abo mothers. (6) The Enhancer of da is a translocation between chromosomes 2 and 3 with the second chromosome breakpoint in the basal heterochromatin; because the enhancing effect maps in this region of chromosome 2, it is possible that autosomal, as well as sex chromosomal, heterochromatin interacts with da and abo.

scholarly journals THE GENETICS OF DOPA DECARBOXYLASE IN DROSOPHILA MELANOGASTER. II. ISOLATION AND CHARACTERIZATION OF DOPA-DECARBOXYLASE-DEFICIENT MUTANTS AND THEIR RELATIONSHIP TO THE α-METHYL-DOPA-HYPERSENSITIVE MUTANTS

Genetics ◽  
1976 ◽  
Vol 84 (2) ◽  
pp. 287-310
Author(s):  
Theodore R F Wright ◽  
Glenn C Bewley ◽  
Allen F Sherald
Keyword(s):  
Drosophila Melanogaster ◽  
Recombination Frequency ◽  
Dopa Decarboxylase ◽  
Isolation And Characterization ◽  
Methyl Dopa ◽  
Level Of Activity ◽  
The Right ◽  
Balancer Chromosome

ABSTRACT Of 84 lethals isolated over the dopa decarboxylase (DDC) deficiency Df(2L)50, 8 have been identified as DDC-deficient alleles on the basis of their effect on DDC activity when heterozygous over the CyO balancer chromosome with activities ranging from 28% to 53% of controls. Some of the Ddc-deficient alleles exhibit intracistronic complementation. Most of the complementing pairs of alleles are much reduced in viability, e.g. < 5% of expected, and express a common syndrome of mutant phenes which can reasonably be inferred to derive from inadequately sclerotinized cuticle. Individuals heterozygous for the noncomplementing allele, Ddcn7, over the 12-band DDC deficiency, Df(2L)130, die at the end of embryogenesis as unhatched larvae with unpigmented mouth parts. The Ddc alleles and the l(2)amd α-methyl dopa (αMD) hypersensitive alleles are both located within the 11 band region 37B10-C7. The l(2)amd locus is immediately to the right of hk(2-53.9).Ddc has been mapped within 0.004 Map Units to the right of l(2)amd with a maximum estimated recombination frequency of 0.01%. None of the Ddc/CyO strains are sensitive to the dietary administration of α-methyl dopa (αMD), and complementation occurs between the Ddc deficient alleles and the l(2)amd alleles both on the basis of viability and DDC activity. No effect on DDC by the amd alleles has been found to date. Even in the complementing heterozygote, amdH1/amdH89, the level of activity, thermostability, and in vitro αMD inhibition of DDC remains unaffected. Although no biochemical phene has yet been established for the αMD hypersensitive amd alleles, it seems likely that the two groups of mutants are functionally related.

scholarly journals ON THE COMPONENTS OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER. II. DELETION MAPPING AND DOSAGE ANALYSIS OF THE SD LOCUS

Genetics ◽  
1983 ◽  
Vol 103 (4) ◽  
pp. 659-673
Author(s):  
John G Brittnacher ◽  
Barry Ganetzky
Keyword(s):  
Salivary Gland ◽  
Segregation Distortion ◽  
Complete Loss ◽  
Deletion Mapping ◽  
Chromosome 2 ◽  
Isolation And Characterization ◽  
Segregation Distorter ◽  
Sperm Dysfunction ◽  
Made In

ABSTRACT Segregation distorter (SD) chromosomes are preferentially transmitted to offspring from heterozygous SD/SD  + males owing to the induced dysfunction of the SD  +-bearing sperm. This phenomenon involves at least two major loci: the Sd locus whose presence is necessary for distortion to occur and the Rsp locus which acts as the site of Sd action. Several additional loci on SD chromosomes enhance distortion.—In a previous study deletions were used to map the Sd locus and to determine some of its properties. We have extended this analysis with the isolation and characterization of 14 new deletions in the Sd region. From our results we conclude (1) SD chromosomes contain a single Sd locus located in region 37D2-6 of the salivary gland chromosome map. Deletion of this locus in any of three SD chromosomes now studied results in complete loss of ability to distort a sensitive chromosome; (2) the reduced male fecundity observed in many homozygous SD or SDi/SDj combinations is due at least in part to the action of the Sd locus. The fecundity of these males can be substantially increased by deletion of one Sd locus. Thus, it is the presence of two doses of Sd rather than the absence of Sd  + that produces the lowered male fecundity in SD homozygotes; (3) Sd behaves as a neomorph, whereas Sd  +, if it exists at all, is amorphic with respect to segregation distortion; (4) these results support a model in which the Sd product is made in limiting amounts and the interaction of this product with the Rsp locus causes sperm dysfunction. The Sd product appears to act preferentially at Rsps (sensitive-Responder) but may also act at Rspi (insensitive-Responder).

scholarly journals Segregation of centric Y-autosome translocations in Drosophila melanogaster: II. Segregation determinants in females

1985 ◽  
Vol 45 (1) ◽  
pp. 81-93 ◽  
Author(s):  
Raphael Falk ◽  
Ana Rahat ◽  
Shula Baker
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Chromosome ◽  
Break Point ◽  
Chromosome Length ◽  
Segregation Pattern ◽  
Chromosome 2 ◽  
Chromosomal Segregation ◽  
Analysis Of Results ◽  
The Right

SummaryThis is a study of the chromosomal segregation patterns in females of 15 Experimental stocks of Drosophila melanogaster, each carrying one element of a T (Y; 2) with a centric break-point. In each Experimental stock the relative frequency of all eight possible meiotic configurations of four relevant chromosomal elements was followed: an attached-X chromosome, a multiply-inverted chromosome 2, a free arm of chromosome 2, and a half-translocation element. Although the 15 translocation elements were broken at different sites, there were no basic differences among the Experimental stocks in their segregation patterns. The three two-by-two configurations were the most common. Comparison of this pattern with that of the segregation pattern of stocks similar but for an inversion-free chromosome 2, showed that in the Experimental stocks exchange pairing did not play a significant role in the determination of the segregation pattern.The results of these experiments, together with the analysis of results from other published studies provide evidence against the model that had been forwarded by Grell. According to this model, chromosomes that did not participate in exchange pairing undergo another pairing cycle, in which total chromosome length is a factor in the determination of segregation.We support a modified version of Novitski's model of premetaphase chromocenter-like chromosome aggregation. Disjunction of non-exchange chromosomes is regulated by determinants located in the proximal heterochromatin of the sex chromosomes and the autosomes. However, the specificity, especially that of the autosomal determinants, is not high. Thus, if an autosome and a sex chromosome are available, their determinants may interact-to-disjoin by default. More frequently, the determinants of the left-arm autosomal element may interact-to-disjoin with those of the right-arm chromosomal element.

Genetic analysis of the second chromosome centromeric heterochromatin of Drosophila melanogaster

Genome ◽  
2003 ◽  
Vol 46 (3) ◽  
pp. 343-352 ◽  
Author(s):  
Alistair B Coulthard ◽  
Daniel F Eberl ◽  
Cecil B Sharp ◽  
Arthur J Hilliker
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Centromeric Heterochromatin ◽  
Chromosome 2 ◽  
Lethal Mutant ◽  
Genetic Elements ◽  
Unpublished Work ◽  
Segregation Distorter ◽  
Mutant Phenotypes

Here we bring together our published and unpublished work with recent published findings of other laboratories to provide a revised map of the centromeric heterochromatin of chromosome 2 and descriptions of the 21 genetic elements therein. These elements consist of 16 vital loci, one male and one female sterile loci, one Minute locus, and two components of the Segregation Distorter system. Based on our latest analysis of the lethal mutant phenotypes of the vital genes, we have provided names for several genes that were previously known by their lethal number assignments.Key words: heterochromatin, Drosophila, cytogenetics.

scholarly journals Characterization of sub-daily rainfall properties in three raingauges located in northeast Brazil

2014 ◽  
Vol 364 ◽  
pp. 345-350 ◽  
Author(s):  
J. V. Coutinho ◽  
C. D. N. Almeida ◽  
A. M. F. Leal ◽  
L. R. Barbosa
Keyword(s):  
Daily Rainfall ◽  
Northeast Brazil ◽  
Rainfall Events ◽  
Event Time ◽  
Accumulated Rainfall ◽  
Semi Arid Region ◽  
Definition Of ◽  
The Right ◽  
Experimental Basins

Abstract. This paper aims to evaluate the characteristics of rainfall events of three experimental basins located in northeast Brazil. The study areas are located, one in Ceará State and two in Paraíba State. Thus, the definition of rainfall events was based on two characteristics: minimum inter-event time and minimum event depth. Then, they were classified according to the shape of the hyetograph: to the left rectangular, triangular, and triangular with peak, and to the right, bimodal and unshaped. Evaluation of the percentages of each type of hyetograph and the main characteristics of rainfall events (peak, duration and intensity) was carried out. The results shows that the two experimental basins located in the semi-arid region have similar characteristics, and shapeless events have significant accumulated rainfall.

Further observations on the nature of radiation-induced chromosomal interchanges recovered from Drosophila sperm

Genome ◽  
1989 ◽  
Vol 32 (5) ◽  
pp. 847-855 ◽  
Author(s):  
Daniel F. Eberl ◽  
Arthur J. Hilliker ◽  
Cecil B. Sharp ◽  
Silvija N. Trusis-Coulter
Keyword(s):  
Drosophila Melanogaster ◽  
Chromosomal Rearrangements ◽  
Strong Tendency ◽  
Chromosome 3 ◽  
Chromosome 2 ◽  
Mitotic Metaphase ◽  
Genetic Approach ◽  
Intercalary Heterochromatin ◽  
Chromosome Breaks ◽  
Radiation Induced

The induction and analysis of numerous translocations (identified genetically and characterized cytologically) between chromosomes 2 and 3 of Drosophila melanogaster have allowed us to reexamine three issues concerning the nature of radiation-induced interchanges in spermatozoa. First, our results support the idea that, relative to their mitotic metaphase length, all major chromosomal regions are similar in their breakability, whether euchromatic (proximal or distal) or heterochromatic. Second, analysis of all our reciprocal exchanges between the two chromosomes shows a statistically significant dependence of the position of the chromosome 2 breakpoint on that of the chromosome 3 breakpoint. Thirdly, our combined cytological and genetic approach strengthens the results of previous analyses, which suggested a strong tendency for chromosomal interchanges to be of the reciprocal type in multiple-break rearrangements. This indicates that if radiation induces chromosome breaks, then the resulting broken ends tend to rejoin in pairs rather than independently.Key words: Drosophila melanogaster, radiation mutagenesis, chromosomal rearrangements, heterochromatin, intercalary heterochromatin.

scholarly journals Segregation of centric Y-autosome translocations in Drosophila melanogaster: I. Segregation determinants in males

1985 ◽  
Vol 45 (1) ◽  
pp. 51-79 ◽  
Author(s):  
Raphael Falk ◽  
Shula Baker ◽  
Ana Rahat
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Chromosome ◽  
Chromosome 2 ◽  
Chromosome X ◽  
Complete Independence ◽  
Group 2 ◽  
The Right ◽  
Complete Dependence ◽  
Group 1 ◽  
Chromosome Disjunction

SummaryA special screening procedure for the detection of induced Y-autosome translocations with centric breakpoints was applied. A series of Experimental stocks was constructed, each containing a different half of one of the induced T(Y; 2)'s (T element). The three other elements that were involved in the segregation experiments in each stock were a sex chromosome (X element), an inverted chromosome 2 (A element), and a free arm of chromosome 2 (F element). It is not feasible to determine the relative frequencies of all the 16 possible gamete types by mating an Experimental stock to one tester, nor to different testers that have each at least one class of progeny of the same genotype. Each Experimental stock was mated to four different Tester stocks and the data were calibrated so that a coherent segregation pattern could be obtained.Segregation patterns in meiosis of males from 15 Experimental stocks, each with a different T element were studied. In most Experimental stocks the T element was of the left autosomal arm, while the F element was of the right autosomal arm. In four Experimental stocks the X element segregated independently of the A, F and T elements. In these Group 1 stocks, both the F and the T elements disjoined regularly from the A element. It was concluded that the T element of these stocks had no sex-chromosome disjunction determinants (‘S-determinants’) to interact with the determinants on the X element. Both the T elements and the F elements carried autosomal disjunction determinants (‘H-determinants’) that secured the segregation of the autosomal elements. The H-determinants of the left autosomal arm were qualitatively different from those of the right arm.In the remaining 11 Group-2 Experimental stocks the X and T elements disjoined regularly, indicating the presence of S-determinants on the T elements of these stocks. The segregation of the T and the A elements in these stocks varied from nearly complete dependence to complete independence. It was concluded that this gradation reflected differences in the quantity of H-determinants present on the T elements of these Experimental stocks. It was impossible to discriminate between a model of continuous H determinants activity and one of a finite discrete number of determinants. The results do not agree with the claim that there are no autosomal disjunction determinants in the proximal heterochromatin of chromosome 2.The S-determinants on the BsYy+ chromosome were located both adjacent to the centromere and distally on the long arm. The latter were probably translocated to the Y chromosome together with the Bs marker.

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