scholarly journals A MODIFIED MODEL OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1980 ◽  
Vol 95 (3) ◽  
pp. 693-706
Author(s):  
Yuichiro Hiraizumi ◽  
Diana W Martin ◽  
Irene A Eckstrand
Keyword(s):  
Drosophila Melanogaster ◽  
Segregation Distortion ◽  
Necessary Condition ◽  
S Locus ◽  
Multiple Alleles ◽  
Modified Model ◽  
E Coli ◽  
Repressor Complex ◽  
S Alleles ◽  
Sperm Dysfunction

ABSTRACT Elements of the Segregation Distorter (SD) system of Drosophila melanogaster, Sd and Rsp, were analyzed and the following points were established: (1) The model of multiple alleles at the Rsp  s locus proposed by MARTIN and HIRAIZUMI (1979) is supported by our observations. (2) A modifier of SD, tentatively symbolized M(SD), was found close to cn (2R-57.5). (3) Sd heterozygous males were found to show, under certain genotypic condition, almost complete sterility.——Based upon these observations, the following modified model of segregation distortion is proposed: (1) The M(SD) locus produces a multimeric repressor protein that binds to the Rsp locus as a necessary condition for normal spermiogenesis. M(SD) homozygotes produce a repressor M(SD)/M(SD); whereas, a homozygote for its normal allele M+(SD) produces a M+(SD)/M+(SD) repressor. M(SD)/M+(SD) heterzygotes produce a M(SD)/M+(SD) repressor. (2) The Sd locus produces a certain product that, like an inducer in the lactose system of E. coli, tends to bind with the repressor complexed with the Rsp locus. This binding disrupts the repressor-Rsp complex, causing Rsp locus to be turned on. The product of Rsp transcription, in turn, results in sperm dysfunction. (3) Rsp  i, an allele of Rsp, has a strong complexing affinity with the repressor such that the Rsp  i-repressor complex is "resistant" to the inducing activity of Sd product. Rsp  s, on the other hand, has a weaker complexing affinity than that of Rsp  i, and the degree of affinity varies among different Rsp  s alleles.——A possible extension of the above model is discussed.

ON THE MODELS OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1979 ◽  
Vol 93 (2) ◽  
pp. 423-435
Author(s):  
Diana W Martin ◽  
Yuichiro Hiraizumi
Keyword(s):  
Drosophila Melanogaster ◽  
Segregation Distortion ◽  
Regulatory Protein ◽  
Segregation Ratio ◽  
Major Elements ◽  
Necessary Condition ◽  
Slight Reduction ◽  
Mendelian Segregation ◽  
Multiple Alleles ◽  
Actual Observation

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.

scholarly journals Mapping the Incompatibility and Style Color Loci in Two Hazelnut Progenies

HortScience ◽  
2014 ◽  
Vol 49 (3) ◽  
pp. 250-253 ◽  
Author(s):  
Colton Ives ◽  
Vidyasagar R. Sathuvalli ◽  
Brooke C. Colburn ◽  
Shawn A. Mehlenbacher
Keyword(s):  
Ssr Markers ◽  
Simple Sequence Repeat ◽  
Random Amplified Polymorphic Dna ◽  
S Locus ◽  
Sequence Repeat ◽  
Leaf Color ◽  
Multiple Alleles ◽  
S Alleles ◽  
Reference Map ◽  
Simple Sequence

Pollen–stigma incompatibility in european hazelnut (Corylus avellana L.) is of the sporophytic type and under the control of a single locus with multiple alleles (haplotypes). The S-locus was previously assigned to linkage group 5 (LG5) and linked DNA markers were identified. The loci that control leaf color and style color are linked to the S-locus. We investigated segregation for leaf and style color and S-alleles in two progenies, mapped the loci, and compared the two new maps with the LG5 reference map using simple sequence repeat (SSR) markers. Segregation for color, S-alleles and SSR markers fit expectations. The color loci and the S-locus mapped to LG5 between SSR markers B028 and B774. The three maps aligned and the SSR markers were collinear. The SSR markers closest to the S-locus are KG819, KG847, and BR259. In progeny 05050, which segregated for style and leaf color, no recombination was observed between the two traits. Recombination between the S-locus and the style color locus was 5.4 cM in progeny 05050 and 10.1 cM in progeny 00064. The style color locus was placed very close to SSR marker B028 in both progenies. On the reference map, random amplified polymorphic DNA (RAPD) markers 564-500M, 345-1050dF, and 204-950dF and intersequence simple sequence repeat (ISSR) marker 815-540dF are very close to the S-locus. The identification of closely linked markers will facilitate the map-based cloning of the S-locus and color loci in hazelnut.

scholarly journals Incompatibility Alleles of Hazelnut Cultivars

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 832F-832
Author(s):  
Shawn A. Mehlenbacher
Keyword(s):  
Fluorescence Microscopy ◽  
Corylus Avellana ◽  
S Locus ◽  
Multiple Alleles ◽  
S Alleles ◽  
Incompatibility Alleles ◽  
New Alleles

Incompatibility in hazelnut (Corylus avellana L.) is of the sporophytic type and is under the control of a single S-locus with multiple alleles. Tests in recent years have identified four new alleles, bringing the total to 26. Improved pollen testers have been identified for several alleles. The S-alleles of more than 90 cultivars have been identified by fluorescence microscopy and will be presented. These cultivars (and their alleles) include Tonda di Giffoni (2 23), San Giovanni (2 8), Gasaway (3 26), Gunslebert (5 23), Kadetten (20 25), Lang Tidlig Zeller (4 20), Nocciolino Sangrato (7 17), Rode Zeller (6 11), Segorbe (9 23), and Simon (6 22).

scholarly journals EXTRACHROMOSOMAL ELEMENT DELTA IN DROSOPHILA MELANOGASTER. IX. INDUCTION OF DELTA-RETAINING CHROMOSOME LINES BY MUTATION AND GENE MAPPING

Genetics ◽  
1973 ◽  
Vol 74 (3) ◽  
pp. 477-487
Author(s):  
Sumio Minamori ◽  
Kinue Sugimoto
Keyword(s):  
Drosophila Melanogaster ◽  
Crossing Over ◽  
Chromosomal Gene ◽  
Ethyl Methane Sulfonate ◽  
Methane Sulfonate ◽  
Multiple Alleles ◽  
Ethyl Methane ◽  
Extrachromosomal Element ◽  
Polygenic System ◽  
Killing Action

ABSTRACT [Delta b], symbolized as [δb], is retained by Sb chromosome lines and transmitted through the females to their progeny. Transmission through the males is not directly demonstrable (Minamori 1969a). [delta r], symbolized as [δr], is retained by Sr chromosome lines and transmitted biparentally (Minamori 1971). The multiplication of delta is suppressed at low temperature. All descendant lines derived from Sb-carrying or Sr-carrying flies in which the presence of delta cannot be demonstrated gradually accumulate their specific delta factors over many generations (Minamori 1969b, 1972). The delta factors and the sensitive chromosomes are inseparably associated. This observation led to the assumption that delta may be a copy of a chromosomal gene or a certain agent integrated into the chromosome (Minamori 1972). This assumption was examined in the present study by experiments designed to induce delta-retaining sensitive chromosomes, and to map the gene(s) responsible for delta-retention and/or for sensitivity to the killing action of delta factor. One sensitive chromosome which retained [δb] (Sb chromosome) was obtained in the presence of [δb] out of 2492 insensitive chromosomes which retained no delta; in addition one Sb chromosome was obtained in the presence of [δr] out of 2131 insensitives. The latter finding suggests that Sb might be induced by a mutation caused by [δb] or [δr], but not by integration of either delta into the chromosome. Four Sb chromosomes and one sensitive chromosome which retained [δr] (Sr chromosome) were obtained out of 1970 insensitives when males carrying the chromosome were fed an alkylating mutagen, ethyl methane sulfonate (EMS). The location of delta-retaining genes was examined by crossing-over experiments employing eight Sb and five Sr chromosomes. The genes on these chromosomes were found to be located in the same region or near one another. The gene for [δb], symbolized as Dab, and the gene for [δr], symbolized as Dar, are assumed to be multiple alleles of a locus at 2-24.9. The sensitivity of the chromosomes was modified appreciably by recombination; hence, the genes controlling this trait are assumed to be a polygenic system. The findings obtained in this study lead to the hypothesis that delta may be produced by a chromosomal gene (Da) and transmitted extrachromosomally.

scholarly journals THE MECHANISM OF A BROODING EFFECT ASSOCIATED WITH SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1973 ◽  
Vol 74 (4) ◽  
pp. 619-631
Author(s):  
D L Hartl
Keyword(s):  
Drosophila Melanogaster ◽  
Segregation Distortion ◽  
Mature Sperm ◽  
Temperature Sensitive ◽  
Short Time

ABSTRACT The recovery of the SD chromosome from a heterozygous SD male increases with brood. This is independent of the age of the female, occurs during the time the sperm are stored in the females, disappears when the segregation distortion is suppressed, and is temperature-sensitive-temperature shocks above or below 25°C applied to the mature sperm both tend to accelerate the increase in the recovery of SD. All this suggests the existence of a class of sperm affected by SD in which the sperm are able to fertilize eggs for a short time following ejaculation but become dysfunctional thereafter.

scholarly journals GENETIC ANALYSIS OF THE CENTROMERIC HETEROCHROMATIN OF CHROMOSOME 2 OF DROSOPHILA MELANOGASTER: DEFICIENCY MAPPING OF EMS-INDUCED LETHAL COMPLEMENTATION GROUPS

Genetics ◽  
1976 ◽  
Vol 83 (4) ◽  
pp. 765-782
Author(s):  
Arthur J Hilliker
Keyword(s):  
Drosophila Melanogaster ◽  
Present Report ◽  
Heterochromatic Region ◽  
Centromeric Heterochromatin ◽  
Genetic Constitution ◽  
Genetic Dissection ◽  
Chromosome 2 ◽  
Multiple Alleles ◽  
Products Analysis ◽  
Dominance Tests

ABSTRACT Until recently, little was known of the genetic constitution of the heterochromatic segments of the major autosomes of Drosophila melanogaster. Our previous report described the genetic dissection of the proximal, heterochromatic region of chromosome 2 of Drosophila melanogasterby means of a series of overlapping deficiencies generated by the detachment of compound second autosomes (Hilliker and Holm 1975). Analysis of these deficiencies by inter se complementation, pseudo-dominance tests with proximal mutations and allelism tests with known deficiencies provided evidence for the existence of at least two loci between the centromere and the light locus in 2L and one locus in 2R between the rolled locus and the centromere. These data in conjunction with cytological observations demonstrated that light and rolled and three loci lying between them are located within the proximal heterochromatin of the second chromosome.——The present report describes the further analysis of this region through the induction with ethyl methanesulphonate (EMS) of recessive lethals allelic to the 2L and 2R proximal deficiencies associated with the detachment products. Analysis of the 118 EMS-induced recessive lethals and visible mutations recovered provided evidence for seven loci in the 2L heterochromatin and six loci in the 2R heterochromatin, with multiple alleles being obtained for most sites. Of these loci, one in 2L and two in 2R fall near the heterochromatic-euchromatic junctions of 2L and 2R respectively. None of the 113 EMS lethals behaved as a deficiency, implying that the heterochromatic loci uncovered in this study represent nonrepetitive cistrons. Thus functional genetic loci are found in heterochromatin, albeit at a very low density relative to euchromatin.

Sign in / Sign up

Export Citation Format

Share Document