scholarly journals THE REGULATION OF WHITE LOCUS EXPRESSION: A DOMINANT MUTANT ALLELE AT THE WHITE LOCUS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1980 ◽  
Vol 95 (2) ◽  
pp. 341-353
Author(s):  
Paul M Bingham
Keyword(s):  
Drosophila Melanogaster ◽  
Mutant Allele ◽  
Chromosomal Rearrangements ◽  
Wild Type Allele ◽  
Wild Type ◽  
Type Allele ◽  
Dominant Mutant ◽  
White Locus ◽  
Somatic Pairing

ABSTRACT A new mutant allele (wDZL)at the white locus of Drosophila melanogaster is dominant to the wild-type allele, but apparently only when the two alleles are synapsed. When chromosomal rearrangements prevent somatic pairing between the two white alleles, wDZL is rendered recessive to wild type. This observation suggests that the dominance of wDZL is sensitive to a synapsis (transvection) effect. On the basis of this and other properties, it is proposed that wDZL causes the repression of transcription of a synapsed w+ allele, but not of a w+ allele elsewhere in the same nucleus. One model to account for this supposes that wDzL produces a repressor of white-locus transcription. This repressor is presumed to be so unstable that other white genes, removed from wDZL but in the same nucleus, are not detectably repressed. These properties may be simply understood if it is assumed that the repressor produced by the wDZL allele is an RNA molecule.

scholarly journals Short and sweet: foreleg abnormalities in Havanese and the role of the FGF4 retrogene

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Kim K. L. Bellamy ◽  
Frode Lingaas
Keyword(s):  
Mutant Allele ◽  
Large Degree ◽  
Population Increase ◽  
Wild Type Allele ◽  
Wild Type ◽  
Gradual Decline ◽  
Type Allele ◽  
Population Frequency ◽  
Welfare Implications

Abstract Background Cases of foreleg deformities, characterized by varying degrees of shortened and bowed forelegs, have been reported in the Havanese breed. Because the health and welfare implications are severe in some of the affected dogs, further efforts should be made to investigate the genetic background of the trait. A FGF4-retrogene on CFA18 is known to cause chondrodystrophy in dogs. In most breeds, either the wild type allele or the mutant allele is fixed. However, the large degree of genetic diversity reported in Havanese, could entail that both the wild type and the mutant allele segregate in this breed. We hypothesize that the shortened and bowed forelegs seen in some Havanese could be a consequence of FGF4RG-associated chondrodystrophy. Here we study the population prevalence of the wild type and mutant allele, as well as effect on phenotype. We also investigate how the prevalence of the allele associated with chondrodystrophy have changed over time. We hypothesize that recent selection, may have led to a gradual decline in the population frequency of the lower-risk, wild type allele. Results We studied the FGF4-retrogene on CFA18 in 355 Havanese and found variation in the presence/absence of the retrogene. The prevalence of the non-chondrodystrophic wild type is low, with allele frequencies of 0.025 and 0.975 for the wild type and mutant allele, respectively (linked marker). We found that carriers of the beneficial wild type allele were significantly taller at the shoulder than mutant allele homozygotes, with average heights of 31.3 cm and 26.4 cm, respectively. We further found that wild type carriers were born on average 4.7 years earlier than mutant allele homozygotes and that there has been a gradual decline in the population frequency of the wild type allele during the past two decades. Conclusions Our results indicate that FGF4RG-associated chondrodystrophy may contribute to the shortened forelegs found in some Havanese and that both the wild type and mutant allele segregate in the breed. The population frequency of the wild type allele is low and appear to be decreasing. Efforts should be made to preserve the healthier wild type in the population, increase the prevalence of a more moderate phenotype and possibly reduce the risk of foreleg pathology.

scholarly journals THE MUTATION SK(ad-3A) CANCELS THE DOMINANCE OF ad-3A  + OVER ad-3A IN THE ASCUS OF NEUROSPORA

Genetics ◽  
1981 ◽  
Vol 97 (2) ◽  
pp. 237-246
Author(s):  
A M Delange
Keyword(s):  
Mutant Allele ◽  
Wild Type Allele ◽  
Wild Type ◽  
Equal Frequency ◽  
Type Allele ◽  
Spore Killer ◽  
Induced Mutant ◽  
Ascospore Formation

ABSTRACT A newly induced mutant of Neurospora, when crossed with an ad-3A mutant, produces asci with four viable black and four inviable white ascospores. The survivors always contain the new mutant allele, never ad-3A. The new allele, which is called SK(ad-3A) (for spore killer of ad-3A), is located at or very near the ad-3A locus. —In crosses homozygous for ad-3A, each ascus contains only inviable white ascospores. This defect in ascospore maturation is complemented by the wild-type allele, ad-3A  + (crosses heterozygous for ad-3A and ad-3A  + produce mainly viable ascospores), but it is not complemented by the new SK(ad-3A) allele (all ad-3A ascospores from crosses heterozygous for SK(ad-3A) and ad-3A are white and inviable). In crosses homozygous for SK(ad-3A) or heterozygous for SK(ad-3A) and ad-3A  +, each ascus contains only viable black ascospores. SK(ad-3A) does not require adenine for growth, and forced heterokaryons between SK(ad-3A) and ad-3A grow at wild-type rates and produce conidia of both genotypes with approximately equal frequency. Thus, the action of SK(ad-3A) is apparently restricted to ascospore formation. Possible mechanisms of the action of this new allele are discussed.

THE DEVELOPMENTAL GENETICS OF THE TEMPERATURE-SENSITIVE LETHAL ALLELE OF THE SUPPRESSOR OF FORKED, l(1)su(f)ts67g, IN DROSOPHILA MELANOGASTER

Genetics ◽  
1974 ◽  
Vol 76 (3) ◽  
pp. 487-510
Author(s):  
Marianne E Dudick ◽  
Theodore R F Wright ◽  
Lynda Lee Brothers
Keyword(s):  
Drosophila Melanogaster ◽  
Ribosomal Protein ◽  
Sensitive Period ◽  
Developmental Genetics ◽  
Temperature Sensitive ◽  
Wild Type Allele ◽  
Wild Type ◽  
Type Allele ◽  
Lethal Allele

ABSTRACT A temperature-sensitive lethal allele of suppressor of forked, l(1)su(f)ts67g (ts67), has been discovered and characterized as follows: Flies which are hemizygous for ts67 live at 18° and 25° but die at 30° primarily as larvae. The temperature-sensitive period for ts67 homozygotes or hemizygotes begins in second instar and ends at pupation. ts67 is lethal at 30° when heterozygous with suppressor of forked (su(f)), a deficiency for suppressor of forked (su(f)  -), and a non-conditional lethal allele of suppressor of forked (3DES). It is viable at 30° when heterozygous with the wild-type allele of suppressor of forked. At 25° but not at 18° forked bristles are suppressed in flies of the following genotypes: fsts67/Y, fsts67/fsts67, fsts67/fssu(f), futs67/fs3DES, futs67/fssu(f)  -, futs67/fssu(f). There is some suppression of forked bristles at 25° in the heterozygote, fsts67/fs+su(f). The forked bristle phenotype is not suppressed at either temperature in flies of the genotypes futs67/Y, futs67/futs67/ (fs and fu indicating suppressible and unsuppressible alleles of forked). The temperature-sensitive period for suppression of forked bristles begins at pupation and extends through the period of bristle synthesis. The deficiency phenotype (bristles reduced in size or absent, wing wrinkled or blistered, eyes rough) typical of flies of the genotype fssu(f)/fssu(f)  - at 18° and 25°, is exhibited by flies of the genotypes fsts67/fssu(f)  - at 25° and futs67/fssu(f) at 29°. An allele of lozenge (lz1) which can be suppressed by su(f) is suppressed at 25° but not at 18° in lz1ts67/Y males. ts67 homozygous females are fertile at 25° but sterile at 30°. The hypothesis is discussed that the su(f) locus codes for a ribosomal protein and that suppression and enhancement are affected by mutations at the locus by mutant ribosome-induced misreading. The possibility is presented that ts67 may be used to determine the translation time in development of any gene.

scholarly journals Positive control of sulphate reduction in Escherichia coli. The nature of the pleiotropic cysteineless mutants of E. coli K 12

1968 ◽  
Vol 110 (3) ◽  
pp. 597-602 ◽  
Author(s):  
M. C. Jones-Mortimer
Keyword(s):  
Escherichia Coli ◽  
Mutant Allele ◽  
Positive Control ◽  
Wild Type Allele ◽  
Wild Type ◽  
E Coli ◽  
Type Allele ◽  
K 12 ◽  
Sulphite Reductase

1. The function of the wild-type alleles of the pleiotropic mutants cysB and cysE of Escherichia coli was investigated. 2. The wild-type allele cysB+ is dominant to the mutant allele cysB in stable and transient heterozygotes. 3. The wild-type allele cysE+ is dominant to the mutant allele cysE, as predicted. 4. Sulphur-starved cultures of cysB or cysE strains contain less than 0·2nmole of free cysteine/mg. dry wt. 5. Complementation in vitro is not observed between extracts of cysB mutants and mutants lacking sulphite reductase only. 6. A scheme, involving positive control of the enzymes of sulphate activation and reduction, is suggested to account for the control of cysteine biosynthesis.

scholarly journals MULTIPLEX PCR BASED SINGLE NUCLEOTIDE POLYMORPHISMS ANALYSIS OF HBS POINT MUTATION

2020 ◽  
pp. 1-4
Author(s):  
Jignisha S Patel ◽  
Jignaben P Naik ◽  
Yazdi M Italia
Keyword(s):  
Multiplex Pcr ◽  
Point Mutation ◽  
Sickle Cell ◽  
Mutant Allele ◽  
Snp Analysis ◽  
Wild Type Allele ◽  
Wild Type ◽  
Single Nucleotide ◽  
Type Allele ◽  
Cell Carrier

Introduction: Sickle hemoglobin (HbS), an autosomal recessive hemoglobinopathy cause of Sickle cell disease (SCD), is widely sprayed around the globe affecting millions of people . SCD results from single nucleotide polymorphism (SNP) or point mutation causing amino acid substitution from Glutamic acid to Valine leads to sickled shape red blood cells. SNPs can be well studied by using allele-specific amplification (ASA) technique. Aims & Objective: To develop a simple, rapid, easy and accurate genotyping method for SNP analysis of SCD. Materials and methods: By performing different tests, a well characterized sample panel of 150 different types of samples was prepared. From this sample panel DNA was extracted and used for SNP-genotyping of SCD. Specific primers were used for performing monoplex PCR amplification of wild type allele (HbAA) and mutant allele (HbSS) were performed individually. By using the same primers multiplex PCR assay was experimented. Results and conclusion: This is a simple and low cost molecular method for the detection of point mutation and useful tool for the diagnosis of SCD. The entire analysis can be performed in one reaction mixture, which results in higher speed, higher accuracy, and the need for smaller samples. This technique might be of great value for genotyping of homozygous sickle cell patients (SS) and heterozygous sickle cell trait (AS). But we found one discrepancy with double heterozygous (sickle β-thalassaemia) samples. We were not able to differentiate sickle cell carrier state (AS) from the double heterozygous like sickle β-thalassaemia state. So we conclude that for simultaneous detection of thalassaemia along with sickle cell requires addition of more primers specific for thalassaemia mutation. In addition to this when two bands, one for wild type allele and second for mutant allele appears, care must be taken to conclude whether the person is a sickle cell carrier (AS) or having double heterozygous (sickle β-thalassaemia) like condition.

Genetic Analysis of theHybrid male rescueLocus of Drosophila

Genetics ◽  
2000 ◽  
Vol 155 (1) ◽  
pp. 225-231 ◽  
Author(s):  
H Allen Orr ◽  
Shannon Irving
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Wild Type Allele ◽  
Wild Type ◽  
Hybrid Male ◽  
Gain Of Function ◽  
Hybrid Inviability ◽  
Type Allele ◽  
Proximate Causes

AbstractSeveral hybrid rescue mutations—alleles that restore the viability of normally lethal hybrids—have been discovered in Drosophila melanogaster and its relatives. Here we analyze one of these genes, Hybrid male rescue (Hmr), asking two questions about its role in hybrid inviability. (1) Does the wild-type allele from D. melanogaster (Hmrmel) cause hybrid embryonic inviability? (2) Does Hmrmel cause hybrid larval inviability? Our results show that the wild-type product of Hmr is neither necessary nor sufficient for hybrid embryonic inviability. Hmrmel does, however, appear to lower the viability of hybrid larvae. The data further suggest (though do not prove) that Hmrmel acts as a gain-of-function poison in hybrids. These findings support previous claims that hybrid embryonic and larval lethalities are genetically distinct and suggest that Hmrmel is at least one of the proximate causes of hybrid larval inviability.

scholarly journals SELECTIVE ALLELE LOSS IN MIXED INFECTIONS WITH T4 BACTERIOPHAGE

Genetics ◽  
1973 ◽  
Vol 73 (1) ◽  
pp. 1-11
Author(s):  
Wendy C Benz ◽  
Hillard Berger
Keyword(s):  
Mutant Allele ◽  
Deletion Mutants ◽  
Mixed Infections ◽  
Repair System ◽  
Wild Type Allele ◽  
Wild Type ◽  
Heteroduplex Dna ◽  
E Coli ◽  
Type Allele ◽  
T4 Bacteriophage

ABSTRACT Evidence is presented that when E. coli B is mixedly infected with T4D wild type and rII deletion mutants, the excess DNA of the wild type allele is lost. No loss is seen in mixed infections with rII point mutants and wild type. In similar experiments with lysozyme addition mutants, the mutant allele is lost. We believe these results demonstrate a repair system which removes "loops" in heteroduplex DNA molecules. A number of phage and host functions have been tested for involvement in the repair of the excess DNA, and T4 genes x and v have been implicated in this process.

scholarly journals DOMINANCE MODIFIERS IN NEUROSPORA CRASSA: PHENOCOPY SELECTION AND INFLUENCE ON CERTAIN ASCUS MUTANTS

Genetics ◽  
1972 ◽  
Vol 71 (2) ◽  
pp. 233-245
Author(s):  
Peter J Russell ◽  
Adrian M Srb
Keyword(s):  
Neurospora Crassa ◽  
Mutant Allele ◽  
Detectable Effect ◽  
Wild Type Allele ◽  
Wild Type ◽  
Group V ◽  
Type Allele ◽  
Dominance Relationships ◽  
Mutant Strains ◽  
Dominant Peak

ABSTRACT When homozygous in zygotes, mutant alleles at the peak locus in linkage group V of Neurospora crassa initiate aberrant asci that are nonlinear, in contrast to the linear asci characteristic of wild type. Most mutant alleles are recessive, inasmuch as crosses of the mutant strains with wild type give linear asci. However, five different mutant alleles, when heterozygous with the wild-type allele, act in varying degrees as zygote dominants, initiating both linear and nonlinear asci, the relative proportions depending on the allele. Five modifiers that act on the dominance relationships of at least one of the five possible heterozygotes of a dominant peak and its wild-type allele have been characterized, four of them having been obtained by selection directed against a phenocopy of these mutants induced by treatment of wild type with l-sorbose. The pattern of modifier specificity observed among the various dominant peak heterozygotes indicates that the phenotypic effects are produced by a complex relationship between the modifiers and the dominant peak alleles in relation to their wild-type allele. In all but two cases the direction of modification, where present, is towards decreasing the dominance of the mutant allele in the heterozygote, evidenced by an increase in the percentage of linear asci when compared with control data. The modifiers exert their maximum modification when they themselves are heterozygous with their wild-type alleles and when the dominant peak allele is heterozygous with its wild-type allele. No modification occurs when heterozygous modifiers are included in zygotes homozygous for a dominant peak allele, reinforcing the notion that the modifiers act on the dominance relationship existent between a dominant peak allele and its wild-type allele, rather than influencing some activity of the mutant allele itself. The modifiers have no detectable effect of their own on ascus morphology, since homozygous modifier zygotes initiate entirely linear asci when only wild-type alleles of peak are present in the zygotes. Their only detectable effect, other than dominance modification, appears to be in conferring sorbose resistance to the mycelium. The modifiers are unlinked to the peak locus, and, except for two of them, they are nonallelic.

scholarly journals Genetic Analysis of Delta, a Neurogenic Gene of Drosophila melanogaster

Genetics ◽  
1987 ◽  
Vol 116 (3) ◽  
pp. 433-445
Author(s):  
Harald Vässin ◽  
Jose A Campos-Ortega
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Phenotypic Expression ◽  
Wild Type Allele ◽  
Wild Type ◽  
Type Allele ◽  
Embryonic Lethal ◽  
Complementation Groups ◽  
Interallelic Complementation ◽  
Hypomorphic Alleles

ABSTRACT We report here the results of a genetic analysis of the gene Delta (Dl) of Drosophila melanogaster. Dl has been mapped to the band 92A2, on the basis of two pieces of evidence: (1) this band is the common breakpoint of several chromosomal aberrations associated with Dl mutations and (2) recombination mapping of alleles of five different lethal complementation groups that are uncovered by Df(3R)DlFX3 (breakpoints at 91F11; 92A3). Dl was found to map most distally of all five complementation groups. The analysis of a large number of Dl alleles demonstrates the considerable genetic and functional complexity of Dl. Three types of Dl alleles are distinguishable. Most alleles behave as amorphic or hypomorphic recessive embryonic lethal alleles, which in addition cause various defects in heterozygosity over the wild-type allele. The defects are due to haplo-insufficient expression of the locus and can be suppressed by a duplication of the wild-type allele. The second class is comprised of three alleles with antimorphic expression. The phenotype of these alleles can only be reduced, rather than suppressed, by a duplication of the wild-type allele. The third group is comprised of three visible, predominantly hypomorphic alleles with an antimorphic component of phenotypic expression. The pattern of interallelic complementation is complex. On the one hand, there is a group of hypomorphic, fully penetrant embryonic lethal alleles which complement each other. On the other hand, most alleles, including all amorphic alleles, are viable over the visible ones; alleles of antimorphic expression, however, are lethal over visible alleles. These results are compatible with a rather complex genetic organization of the Dl locus.

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