scholarly journals CHLOROPLAST GENETICS OF CHLAMYDOMONAS. I. ALLELIC SEGREGATION RATIOS

Genetics ◽  
1976 ◽  
Vol 83 (2) ◽  
pp. 303-321
Author(s):  
Ruth Sager ◽  
Zenta Ramanis
Keyword(s):  
Pedigree Analysis ◽  
Wild Type ◽  
Significant Excess ◽  
Chloroplast Markers ◽  
Preferential Segregation ◽  
Segregation Ratios ◽  
Allelic Segregation ◽  
Allele Specificity ◽  
Chloroplast Genetics ◽  
Map Location

ABSTRACT This paper presents allelic segregation data from a series of 16 crosses segregated for nuclear and chloroplast genes. By means of pedigree analysis, segregants of chloroplast markers occurring in the zygote have been distinguished from those occurring in zoospore clones. The genes ac1, ac2, and tm1 showed little if any deviation from 1:1 either in zygotic segregation or in zoospore clones. The genes sm2, ery, and spc showed a significant excess of the allele from the mt  + parent in zygotes. However, in zoospores, mt  + excess was seen only when that allele was the mutant (resistant) form but not when it was wild type (sensitive). These results show that the extent of preferential segregation differs in zygotes and in zoospores, and that preferential segregation is influenced by map location and by allele specificity. A comparison of progeny from zygotes mated after 0, 15˝, 30˝, and 50˝ UV irradiation of the mt  + gametes demonstrated the lack of an effect of UV upon allelic segregation ratios. In total, these results exclude the multi-copy model of chloroplast genome segregation suggested by Gillham, Boynton and Lee (1974) and support the diploid model we have previously proposed (Sager and Ramanis 1968, 1970; Sager 1972).

scholarly journals CHLOROPLAST GENETICS OF CHLAMYDOMONAS. II. MAPPING BY COSEGREGATION FREQUENCY ANALYSIS

Genetics ◽  
1976 ◽  
Vol 83 (2) ◽  
pp. 323-340
Author(s):  
Ruth Sager ◽  
Zenta Ramanis
Keyword(s):  
Frequency Analysis ◽  
Single Gene ◽  
Average Frequency ◽  
Pedigree Analysis ◽  
Type Ii ◽  
Chloroplast Genes ◽  
Type Iii ◽  
Chloroplast Genetics ◽  
Map Location ◽  
Positive Interference

ABSTRACT This paper presents segregation and cosegregation data for a set of 15 chloroplast genes of Chlamydomonas, and uses these data to generate a linear map of the chloroplast genome. The data were derived from pedigree analysis of a total of 1596 zoospore clones resulting from 12 crosses in each of which 4 to 7 pairs of chloroplast alleles were segregating. The crosses are a subset of those previously described (Sager and Ramanis 1976). By means of pedigree analysis, Type II segregations (nonreciprocal conversion-like events) were distinguished from Type III segregations (reciprocal events). The average frequency of Type II segregation was found to be the same for all 15 genes, indicating randomness of this event with respect to map location (Figure 1). Type III segregations occurred with a different and characteristic frequency for each gene, and were interpreted as a measure of the distance of each gene from the postulated centromere-like attachment point. Cosegregations, involving two or more genes, occurred with frequencies characteristic of the particular genes and much lower than expected for the product of single-gene events, indicating strong positive interference. Pairwise cosegregation frequencies provided unambiguous data for the gene order, confirmed by cosegregation runs of three or more genes. Apparent lengths of cosegregation runs, as fractions of the total map, indicate much longer stretches of gene conversion-like events than have been reported for other genetic systems. Comparisons of cosegregation frequencies in cross 20 after 15˝, 30˝ and 15˝ UV irradiation of the mt  + before mating, indicate little if any consistent effect of this irradiation on segregation events.

scholarly journals Obesity is potentially associated with a novel mitochondrial tRNAGly 10029A>G mutation in a Chinese family

2019 ◽  
Author(s):  
Jinling Wang ◽  
Ningning Zhao ◽  
Xiaoting Mao ◽  
Feilong Meng ◽  
Ke Huang ◽  
...  
Keyword(s):  
Molecular Profiling ◽  
Pedigree Analysis ◽  
Elevated Risk ◽  
Dynamics Simulation ◽  
Chinese Family ◽  
Obesity Risk ◽  
Wild Type ◽  
Clinical Genetic ◽  
Codon Recognition ◽  
Public Health Challenges

Abstract Background Obesity is one of the most prominent public health challenges globally. Mutations in mitochondrial genes can similarly lead to the onset of childhood obesity remains unclear. Methods we conducted a clinical, genetic, and molecular profiling of a Han Chinese family with evident of matrilineally-inherited obesity. Obesity was evident in 2/6 matrilineal relatives in a single generation of this family (of 3 available generations). When the mitochondrial DNA of these individuals was sequences and a pedigree analysis was performed. Results We were able to identify a novel homoplasmic mutation of the mitochondrial tRNAGly gene (10029A>G) in these individuals. This mutation was linked to destabilization of a conserved base pair in the anticodon of this tRNA. This position (position 43) is known to be important for mediating effective codon recognition and tRNA stability. Consistent with the importance of this conserved site, we found that the predicted structure of a tRNAGly structure bearing a 10029A>G mutation was markedly altered in a molecular dynamics simulation relative to the wild-type isoform. All other mutations identified in the mtDNA of this individual were known variants associated with Asian haplogroup D4. Conclusion Our report provides novel evidence of a link between a tRNA mutation and an elevated risk of maternally-transmissible obesity risk, offering potentially novel insights into the underlying nature of obesity.

scholarly journals The effect of suppressing crossing-over on the response to selection in Drosophila melanogaster

1970 ◽  
Vol 16 (1) ◽  
pp. 1-16 ◽  
Author(s):  
C. P. McPhee ◽  
Alan Robertson
Keyword(s):  
Drosophila Melanogaster ◽  
Dominant Gene ◽  
Crossing Over ◽  
Linkage Equilibrium ◽  
Selection Experiment ◽  
Base Population ◽  
Response To Selection ◽  
Wild Type ◽  
Segregation Ratios

SUMMARYA selection experiment for sternopleural bristles in Drosophila melanogaster was undertaken to measure the effect of suppressing crossing-over on chromosomes II and III using the inversions Curly and Moiré marked with a dominant gene, which severely reduce crossing-over. In one set of lines selected wild-type males were mated to selected females, heterozygous for Cy and Mé, and in a parallel set selected males carrying the inversions were mated to selected wild-type females. Because there is no crossing-over in the males in this species, crossing-over is much reduced in the first set and is at its usual level in the second. The effect of the selection was measured on flies which did not carry the inversions. The suppression of crossing-over reduced the advance at the limit by 28 ± 8% for selection upwards and by 22 ± 7% for selection downwards. The segregation ratios of the inversions were observed throughout the experiment. At the end, the proportion of wild-type flies emerging was not different in the two sets of lines. The results are consistent with an assumption of initial linkage equilibrium between loci affecting sternopleural bristles in the base population.

scholarly journals Obesity associated with a novel mitochondrial tRNACys 5802A>G mutation in a Chinese family

2020 ◽  
Vol 40 (1) ◽  
Author(s):  
Jinling Wang ◽  
Ningning Zhao ◽  
Xiaoting Mao ◽  
Feilong Meng ◽  
Ke Huang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Profiling ◽  
Pedigree Analysis ◽  
Dynamics Simulation ◽  
Chinese Family ◽  
Wild Type ◽  
Clinical Genetic ◽  
Single Generation ◽  
Codon Recognition ◽  
Stem Position

Abstract A Chinese family with matrilineally inherited obesity was assessed and its clinical, genetic, and molecular profiling was conducted. Obesity was observed in matrilineal relatives (3 out of 7) of a single generation (of 3 alive generations) in this family. On pedigree analysis and sequencing of their mitochondrial DNA (mtDNA), a novel homoplasmic mutation of the mitochondrial tRNACys gene (5802A>G) was identified in these individuals. This mutation correlated with a destabilized conserved base pair in this tRNA anticodon stem. Position 30 is known to be crucial for carrying out effective codon recognition and stability of tRNA. In accordance with the importance of this conserved site, we observed that the predicted structure of tRNACys with the mutation was noticeably remodeled in a molecular dynamics simulation when compared with the isoform of the wild-type. All other 46 mutations observed in the individual’s mtDNA were known variants belonging to haplogroup D4. Thus, this is the first report that provides evidence of the association between a mutation in tRNA and an enhanced risk of maternally transmissible obesity, offering more insights into obesity and its underlying nature.

scholarly journals Inheritance of the Flower Types of Gerbera hybrida

2004 ◽  
Vol 129 (6) ◽  
pp. 802-810 ◽  
Author(s):  
Wesley E. Kloos ◽  
Carol G. George ◽  
Laurie K. Sorge
Keyword(s):  
North Carolina ◽  
Single Gene ◽  
Dominant Gene ◽  
Wild Type ◽  
Male Sterile ◽  
Gerbera Hybrida ◽  
The North ◽  
Wide Range ◽  
Segregation Ratios ◽  
Linkage Relationships

Cultivated gerbera daisies [Gerbera hybrida (G. jamesonii Bolus ex Adlam × G. viridifolia Schultz-Bip)] have several different flower types. They include single and crested cultivars that have normal florets with elliptical (ligulate) outer corolla lips and spider cultivars that have florets with laciniated (split) outer corolla lips appearing as several pointed lobes. The objective of this investigation was to determine the mode of inheritance of the major flower types of gerberas in the North Carolina State Univ. collection. The collection contained parents and four generations of progeny representing a wide range of single and crested cultivars and some spider cultivars. Genotypes of parents used in crosses were determined by testcrosses to single-flowered, ligulate floret cultivars similar in phenotype to the wild, parental gerbera species. Testcrosses indicated that the wild type was recessive to the crested and spider flower types and given the genotype crcrspsp. For each of the types, a series of crosses were made to produce PA, PB, F1, F2, BC1A, and BC1B progeny. Allelism was tested operationally by crossing genotypes in all possible combinations and observing single-gene-pair ratios. Linkage relationships among the crested and spider loci were tested using dihybrid crosses and testcrosses. Phenotypic segregation ratios suggested the presence of two dominant alleles, Crd and Cr, determining the enlarged disk and trans floret, male-sterile and enlarged trans floret, male-fertile crested types, respectively, and an unlinked dominant gene, Sp, determining the spider type. Dominance appeared to be incomplete due to the reduction of trans floret length in most Crdcr and Crcr heterozygotes compared to crested homozygotes and the appearance of the quasi-spider type (spider trans and disk florets and ligulate and/or slightly notched ray florets) among certain crested Spsp heterozygotes.

scholarly journals Generating Autotetraploid Sporophytes and Their Use in Analyzing Mutations Affecting Gametophyte Development in the Fern Ceratopteris

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 809-814
Author(s):  
Brody DeYoung ◽  
Todd Weber ◽  
Barbara Hass ◽  
Jo Ann Banks
Keyword(s):  
Sex Determination ◽  
Dna Content ◽  
Meiotic Chromosome ◽  
Complementation Analysis ◽  
Recessive Mutation ◽  
Wild Type ◽  
Gametophyte Development ◽  
Segregation Ratios ◽  
Mutant Phenotypes ◽  
Mother Cells

The haploid gametophytes of the fern Ceratopteris richardii are autotrophic and develop independently of the diploid sporophyte plant. While haploid genetics is useful for screening and characterizing mutations affecting gametophyte development in Ceratopteris, it is difficult to assess whether a gametophytic mutation is dominant or recessive or to determine allelism by complementation analysis in a haploid organism. This report describes how apospory can be used to produce genetically marked polyploid sporophytes whose gametophyte progeny are heterozygous for mutations affecting sex determination in the gametophyte and a known recessive mutation affecting the phenotype of both the gametophyte and sporophyte. The segregation ratios of wild-type to mutant phenotypes in the gametophyte progeny of polyploid sporophyte plants indicate that all of the mutations examined are recessive. The presence of many multivalents and few univalents in meiotic chromosome preparations of spore mother cells confirm that the sporophyte plants assayed are polyploid. The DNA content of the sperm of their progeny gametophytes was also found to be approximately twice that of sperm from wild-type haploid gametophytes.

VIABILITY ESTIMATES FOR SIXTY TOMATO MUTANTS

1977 ◽  
Vol 19 (1) ◽  
pp. 31-38 ◽  
Author(s):  
L. Butler
Keyword(s):  
Chromosomal Rearrangement ◽  
Sudden Change ◽  
Lethal Gene ◽  
Chromosome 2 ◽  
Wild Type ◽  
First Case ◽  
Segregation Ratios ◽  
Uniform Background ◽  
Slow Growing ◽  
Types Of Change

Monogenic segregation data for 60 mutants show that for 42 of them the observed number was less than the expected and 25 of these 42 were significantly less. In many cases the discrepancy was too small to de detected in populations; of less than 500 plants. In no case was the mutant more viable than the wild type allele unless one accepts data for mutants H and o which appear to be cases of misclassification. The cause of the inviability was obvious in many cases where the mutant was slow growing (I, dil, tf), or poor germinating (ro, au, dpy), but in many cases the mutant wais as vigorous as the wild type. There were two types of change in viability, in the first case newly arisen mutants became more viable as the result of selection on different genetic backgrounds, in the second case there was a sudden change in viability because the mutant became associated in coupling phase with a lethal gene. The segregation ratios of genes at the proximal end of chromosome 2 are affected by the gametic eliminator (gt) whereas segregations in the central region, in the vicinity of aw, are affected by a chromosomal rearrangement. Genes at the distal end of chromosome 2 may have distorted ratios because of a lethal near the bip locus. The importance of uniform background and planned experiments is pointed out.

scholarly journals Identification of neurofibromin mutants that exhibit allele specificity or increased Ras affinity resulting in suppression of activated ras alleles.

1996 ◽  
Vol 16 (5) ◽  
pp. 2496-2503 ◽  
Author(s):  
P Morcos ◽  
N Thapar ◽  
N Tusneem ◽  
D Stacey ◽  
F Tamanoi
Keyword(s):  
Critical Role ◽  
Yeast Cells ◽  
Single Amino Acid ◽  
Wild Type ◽  
Ras Protein ◽  
High Affinity ◽  
Gtpase Activating Proteins ◽  
Allele Specific ◽  
Allele Specificity ◽  
Mutant Forms

Neurofibromin plays a critical role in the downregulation of Ras proteins in neurons and Schwann cells. Thus, the ability of neurofibromin to interact with Ras is crucial for its function, as mutations in NF1 that abolish this interaction fail to maintain function. To investigate the neurofibromin-Ras interaction in a systematic manner, we have carried out a yeast two-hybrid screen using a mutant of H-ras, H-rasD92K, defective for interaction with the GTPase-activated protein-related domain (GRD) of NF1. Two screens of a randomly mutagenized NF1-GRD library led to the identification of seven novel NF1 mutants. Characterization of the NF1-GRD mutants revealed that one class of mutants are allele specific for H-raSD92K. These mutants exhibit increased affinity for H-raSD92K and significantly reduced affinity for wild-type H-ras protein. Furthermore, they do not interact with another H-ras mutant defective for interaction with GTPase-activating proteins. Another class of mutants are high-affinity mutants which exhibit dramatically increased affinity for both wild-type and mutant forms of Ras. They also exhibit a striking ability to suppress the heat shock sensitive traits of activated RAS2G19v in yeast cells. Five mutations cluster within a region encompassing residues 1391 to 1436 (region II). Three NF1 patient mutations have previously been identified in this region. Two mutations that we identified occur in a region encompassing residues 1262 to 1276 (region I). Combining high-affinity mutations from both regions results in even greater affinity for Ras. These results demonstrate that two distinct regions of NF1-GRD are involved in the Ras interaction and that single amino acid changes can affect NF1's affinity for Ras.

scholarly journals Inheritance of Powdery Mildew Resistance and Leaf Macrohair Density in Gerbera hybrida

HortScience ◽  
2005 ◽  
Vol 40 (5) ◽  
pp. 1246-1251 ◽  
Author(s):  
Wesley E. Kloos ◽  
Carol G. George ◽  
Laurie K. Sorge
Keyword(s):  
Powdery Mildew ◽  
Low Density ◽  
State University ◽  
Dominant Allele ◽  
Wild Type ◽  
Gerbera Hybrida ◽  
North Carolina State University ◽  
The North ◽  
Segregation Ratios ◽  
Linkage Relationships

The cultivated gerbera daisy [Gerbera hybrida (G. jamesonii Bolus ex Adlam × G. viridifolia Schultz-Bip)] often contracts powdery mildew (PM) when grown under conditions of high humidity. During field and greenhouse performance trials conducted with gerberas of the North Carolina State University collection, two half-sib field plants and two of their greenhouse-grown progeny were identified as being highly resistant to PM caused by Podosphaera (Sphaerotheca) fusca (Fr.) Blumer emend. Braun & Takamatsu. These plants were also unusual in having smooth glossy leaves with very low numbers of bristle macrohairs (MHs) on the adaxial leaf surface compared to wild type. The primary objectives of this investigation were to determine the mode of inheritance of PM resistance and MH density traits and determine if there was a causal relationship between the phenotypes. Parental genotypes were determined by testcrosses to wild-type, PM-susceptible and MH-high-density leaf cultivars. For each trait, a series of crosses were made to produce PA, PB, F1, F2, BC1A, and BC1B progeny. Linkage relationships among PM resistance and MH density loci were examined by testcrosses. Phenotypic segregation ratios suggested the presence of a dominant allele, Pmr1, determining PM resistance and an unlinked dominant allele, Mhd, determining low density of adaxial bristle MHs and moderate reduction in abaxial smooth MHs. The Pmr1 allele appeared to be incompletely dominant in some heterozygotes where one parent was from a highly PM susceptible background. Modifying genes may have some affect on the level of PM resistance or susceptibility. The Mhd allele appeared to be incompletely dominant in some heterozygotes. Segregation ratios indicated that the wild-type alleles were recessive to the PM-resistance and MH-low-density alleles and given the designation pmr1 and mhd, respectively. Density of leaf MHs did not affect PM resistance.

scholarly journals New Insights into the Melanophilin (MLPH) Gene Affecting Coat Color Dilution in Rabbits

Genes ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 430 ◽  
Author(s):  
Julie Demars ◽  
Nathalie Iannuccelli ◽  
Valerio Utzeri ◽  
Gerard Auvinet ◽  
Juliette Riquet ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Frameshift Mutation ◽  
Coat Color ◽  
Exon Skipping ◽  
Transcript Level ◽  
Causal Variant ◽  
Wild Type ◽  
Acceptor Splice Site ◽  
Allelic Segregation ◽  
The Stability

Coat color dilution corresponds to a specific pigmentation phenotype that leads to a dilution of wild type pigments. It affects both eumelanin and pheomelanin containing melanosomes. The mode of inheritance of the dilution phenotype is autosomal recessive. Candidate gene approaches focused on the melanophilin (MLPH) gene highlighted two variants associated with the dilution phenotype in rabbits: The c.111-5C>A variant that is located in an acceptor splice site or the c.585delG variant, a frameshift mutation. On the transcript level, the skipping of two exons has been reported as the molecular mechanism responsible for the coat color dilution. To clarify, which of the two variants represents the causal variant, (i) we analyzed their allelic segregation by genotyping Castor and Chinchilla populations, and (ii) we evaluated their functional effects on the stability of MLPH transcripts in skin samples of animals with diluted or wild type coat color. Firstly, we showed that the c.585delG variant showed perfect association with the dilution phenotype in contrast to the intronic c.111-5C>A variant. Secondly, we identified three different MLPH isoforms including the wild type isoform, the exon-skipping isoform and a retained intron isoform. Thirdly, we observed a drastic and significant decrease of MLPH transcript levels in rabbits with a coat color dilution (p-values ranging from 10−03 to 10−06). Together, our results bring new insights into the coat color dilution trait.

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