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 ON THE COMPONENTS OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER. III. NATURE OF ENHANCER OF SD

Genetics ◽  
1984 ◽  
Vol 107 (3) ◽  
pp. 423-434
Author(s):  
John G Brittnacher ◽  
Barry Ganetzky
Keyword(s):  
Drosophila Melanogaster ◽  
Segregation Distortion ◽  
Allelic Variation ◽  
Meiotic Drive ◽  
Dependent Manner ◽  
X Ray ◽  
Segregation Distorter ◽  
In Cis ◽  
General Component

ABSTRACT Analysis of X-ray-induced deletions in the Segregation Distorter (SD) chromosome, SD-5, revealed that this chromosome had a gene proximal to lt in the centric heterochromatin of 2L that strongly enhanced the meiotic drive caused by the SD chromosome. This Enhancer of Segregation Distortion [E(SD)] locus had not been characterized in earlier studies of SD chromosomes because it cannot be readily separated by recombination from the Responder (Rsp) locus in the proximal heterochromatin of 2R.—To determine whether E(SD) is a general component of all SD chromosomes and to examine further its effects on distortion, we produced deletions of E(SD) in three additional SD chromosomes. Analysis of these deletions leads to the following conclusions: (1) along with Sd and Rsp, E(SD) is common to all SD chromosomes; (2) the E(SD) allele on each SD chromosome enhances distortion by the same amount, which indicates that allelic variation at the E(SD) locus is not responsible for the different drive strengths seen among SD chromosomes; (3) E(SD) causes very little or no distortion by itself in the absence of Sd; (4) E(SD), like Sd, acts in a dosage-dependent manner; (5) E(SD) exerts its effect in cis or trans to Sd; and (6) if E(SD)  + exists, its function is not related to SD.

Linkage and segregation distortion in Drosophila melanogaster

Genome ◽  
1989 ◽  
Vol 32 (5) ◽  
pp. 840-846 ◽  
Author(s):  
Cecil B. Sharp ◽  
Arthur J. Hilliker
Keyword(s):  
Drosophila Melanogaster ◽  
Y Chromosome ◽  
Segregation Distortion ◽  
Homologous Chromosome ◽  
Meiotic Drive ◽  
Major Effect ◽  
Chromosome 2 ◽  
Genetic Elements ◽  
Segregation Distorter ◽  
Per Se

Segregation distortion is caused by a group of genetic elements in and near the centric heterochromatin of chromosome 2 of Drosophila melanogaster. These elements promote their preferential recovery in heterozygous males by rendering sperm bearing the homologous chromosome dysfunctional. Previous work has shown that numerous Y–autosome translocations are associated with the suppression of the segregation distorter phenotype. The present study examined the effects of translocations between the major autosomes upon the expression of segregation distortion. Autosomal translocations involving either the segregation distorter chromosome or its sensitive homologue had no significant effect upon the expression of segregation distortion. These results argue that linkage arrangement per se may not have a major effect on segregation distortion. The suppression of SD by specific Y–autosomal translocations may be due to the disruption of elements on the Y chromosome that are important for the expression of SD.Key words: segregation distortion, meiotic drive, translocations, Drosophila melanogaster.

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 Examination of a mutable system affecting the components of the segregation distorter meiotic drive system of Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 125 (1) ◽  
pp. 51-76
Author(s):  
K G Golic
Keyword(s):  
Drosophila Melanogaster ◽  
Transposable Element ◽  
X Chromosome ◽  
Segregation Distortion ◽  
Chromosomal Rearrangements ◽  
Meiotic Drive ◽  
Drive System ◽  
Partial Loss ◽  
Segregation Distorter ◽  
Relationship Of

Abstract Segregation distortion in Drosophila melanogaster is the result of an interaction between the genetic elements Sd, a Rsp sensitive to Sd, and an array of modifiers, that results in the death of sperm carrying Rsp. A stock (designated M-5; cn bw) has been constructed which has the property of inducing the partial loss of sensitivity from previously sensitive cn bw chromosomes, the partial loss of distorting ability from SD chromosomes, and a concomitant acquisition of modifiers on the X chromosome and possibly also on the autosomes. By several criteria the changes exhibited under the influence of M-5; cn bw are characteristic of the transposable-element systems which produce hybrid dysgenesis. In the first place, the magnitude of these effects depends on the nature of the crosses performed. The analogy is further strengthened by the observation that the changes induced by M-5; cn bw share other stigmata of Drosophila transposable-element systems, including high sterility among the progeny of outcrosses, and the production of chromosomal rearrangements. The possible relationship of this system to the P, I and hobo transposable element systems is discussed, as well as its bearing on aspects of the Segregation Distorter phenomenon which have yet to be explained.

scholarly journals On the components of segregation distortion in Drosophila melanogaster. V. Molecular analysis of the Sd locus.

Genetics ◽  
1991 ◽  
Vol 129 (1) ◽  
pp. 133-144 ◽  
Author(s):  
P A Powers ◽  
B Ganetzky
Keyword(s):  
Drosophila Melanogaster ◽  
Sequence Analysis ◽  
Molecular Analysis ◽  
Tandem Duplication ◽  
Meiotic Drive ◽  
Northern Blots ◽  
Sequence Identity ◽  
Naturally Occurring ◽  
Segregation Distorter ◽  
Genomic Probes

Abstract Segregation Distorter (SD) is a naturally occurring meiotic drive system comprising at least three distinct loci: Sd, Rsp and E(SD). Heterozygous SD/SD+ males transmit the SD chromosome in vast excess over the normal homolog. The distorted transmission involves the induced dysfunction of the spermatids that receive the SD+ chromosome. In the 220-kb region of DNA that contains the Sd gene, we identified a 5-kb tandem duplication that is uniquely associated with all SD chromosomes, absent in SD+ chromosomes, and detectably altered in Sd revertants. On northern blots, genomic probes from the tandem duplication detect an SD-specific 4-kb transcript in addition to several smaller transcripts present in both SD and SD+. Seven classes of cDNAs derived from these transcripts have been isolated. All of these cDNAs share extensive sequence identity at their 3' ends but differ at their 5' ends. Sequence analysis indicates that these cDNAs potentially encode four distinct, but related, polypeptides. Introduction of the tandem duplication into SD+ flies by germline transformation did not confer the dominant gain-of-function Sd phenotype. This result, taken together with our analysis of the Sd cDNAs, suggests that the duplication is part of a much larger gene that encodes several different polypeptides.

scholarly journals Characterization of two Segregation distorter revertants: evidence that the tandem duplication is necessary for Sd activity in Drosophila melanogaster.

Genetics ◽  
1994 ◽  
Vol 136 (1) ◽  
pp. 209-215
Author(s):  
M F Palopoli ◽  
P Doshi ◽  
C I Wu
Keyword(s):  
Drosophila Melanogaster ◽  
Tandem Duplication ◽  
Tandem Repeats ◽  
Direct Evidence ◽  
Consistent Difference ◽  
Naturally Occurring ◽  
Segregation Distorter ◽  
Topoisomerase 2 ◽  
Flanking Regions

Abstract Segregation Distorter (SD) is a naturally occurring system of meiotic drive in Drosophila melanogaster. Males heterozygous for an SD second chromosome and a normal homolog (SD+) transmit predominantly SD-bearing sperm. To accomplish this, the Segregation distorter (Sd) locus induces the dysfunction of those spermatids that receive the SD+ chromosome. Recently, P. A. Powers and B. Ganetzky isolated overlapping DNA clones spanning the region of DNA known to contain the Sd gene and identified a 5-kb tandem duplication that is present on all SD chromosomes examined, but is apparently absent from wild-type chromosomes. Here we report a molecular analysis of two spontaneous revertants from an Australian SD chromosome (SD-Arm28). Both of these revertants have lost the 5-kb tandem duplication along with the ability to distort transmission; the critical observation, however, is that they retain the DNA haplotype in the flanking regions (both proximally and distally) that is characteristic of the original SD-Arm28. We propose unequal sister chromatid exchange between the tandem repeats as the only plausible explanation for loss of a repeat while retaining flanking markers. This provides direct evidence that the tandem duplication is indeed necessary for the Sd phenotype. Further, we examined testes-specific levels of both RNA and protein for the nearby Topoisomerase 2 gene. Neither revealed a consistent difference between SD and SD+ strains. We also measured testes-specific levels of RNA using the tandem duplication itself as probe. Our results suggest that there is strong up-regulation of one or several 2.0-2.3-kb transcripts from the duplicated region in the testes of an SD strain.(ABSTRACT TRUNCATED AT 250 WORDS)

SD-72 has a temperature-sensitive period during spermiogenesis

1983 ◽  
Vol 25 (6) ◽  
pp. 662-667 ◽  
Author(s):  
Kathleen Matthews ◽  
Mark A. Mortin
Keyword(s):  
Drosophila Melanogaster ◽  
High Temperature ◽  
Segregation Distortion ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Proximate Cause ◽  
Naturally Occurring ◽  
Segregation Distorter

Segregation distorter (SD) chromosomes in Drosophila melanogaster are naturally occurring second chromosomes which produce greatly altered transmission frequencies when present in heterozygous males (Hartl and Hiraizumi 1976). The proximate cause of segregation distortion is abortion of spermatids carrying the non-SD homologue (Tokuyasu et al. 1977). SD-72, a chromosome previously shown (Mange 1968) to be unaffected by high temperature treatment of spermatocytes, a stage when several SD genotypes are temperature sensitive, has a temperature-sensitive period during spermiogenesis. SD-72/cn bw males exposed to a 24-h pulse of 29 °C, then brooded for 24 h, experience a decrease in segregation distortion of approximately two-thirds. The timing of the reduction in distortion indicates that the temperature-sensitive period is postmeiotic.

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.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

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