PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Gene duplication”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1992

Hereditary hypertension caused by chimaeric gene duplications and ectopic expression of aldosterone synthase.

Patients with glucocorticoid-remediable aldosteronism (GRA) from 12 kindreds possess chimaeric gene duplications arising from unequal crossing-over, fusing regulatory sequences of steroid 11 beta-hydroxylase to coding sequences of aldosterone synthase. These chimaeric genes are specific for GRA and explain the biochemistry, physiology and genetics of this form of hypertension. Sites of crossing over range from intron 2 to intron 4. Most mutations have arisen independently from either sister or non-sister chromatid exchange between these genes, which are only 45 kilobases apart. The possibility of a susceptibility allele for GRA of Irish origin is suggested. These findings indicate the utility of a direct genetic test for this disorder.

Alleles↗
PubMedDate not supplied

Gene duplication at an isocitrate dehydrogenase locus in Scaphiopus.

Spadefoot toads of the subgenus Scaphiopus have two isocitrate dehydrogenase loci, with no intergenic interaction between them. Toads of the subgenus Spea have three Idh loci, with intergenic enzymes formed between two of them, providing strong evidence for their homology and the origin of one through a duplication process. The Idh phenotype of interspecific hybrids is consistent with the theory of a gene duplication.

Animals↗
PubMed1977

Duplicate gene expression in diploid and tetraploid loaches (Cypriniformes, Cobitidae).

Botia macracantha and B. modesta have been demonstrated to be tetraploid species on the basis of their karyotypes and on the basis of the expression of a number of isozymes encoded by duplicate loci. A rather low percentage of duplicate loci was detected by electrophoresis, compared to that for other tetraploid Cypriniformes. Several hypotheses have been advanced to account for the low levels of duplicate gene expression observed. Lastly, many of the duplicate loci have diverged to unique patterns of expressions in different tissues or different levels of activity within a single tissue.

Animals↗
PubMed1977

Influence of gene duplication and X-inactivation on mouse mitochondrial malic enzyme activity and electrophoretic patterns.

We have investigated, with and without the influence of X-inactivation, the relationship between autosomal gene-dosage and gene-product in a mammalian system, the mouse. The gene was mitochondrial malic enzyme (Mod-2), shown to lie on Chromosome 7 between the albino (c) and shaker-1 (sh-1) loci, and the enzyme was its product, mitochondrial malic enzyme (MOD-2). Gene duplication, with and without the influence of X-inactivation, was achieved using a translocation that involves the insertion of a portion of Chr 7, including Mod-2, into the X, T(X;7)1Ct. A 1:1 relationship for Mod-2 dosage and MOD-2 activity was found in heart mitochondria. Evidence of X-inactivation of Mod-2 was noted in heart and kidney preparations from females carrying a Mod-2 duplication (one copy of Mod-2 in the X and two copies of Mod-2 on Chr 7). We conclude that the expression of an autosomal locus attached to X-chromatin depends upon whether the translocation is in a balanced or unbalanced state.

Alleles↗
PubMed1977

[Gene duplication and protein evolution. Case of aminoacyl-t-RNA synthetases].

Aminoacyl-tRNA synthetases are a functionally homologous group of enzymes which catalyse the first step of protein synthesis. The accumulation of data on the oligomeric structures of these enzymes has revealed a wide diversity in the sizes and organization of the protomers. This is not consistent with the idea of a family with homologous primary and tertiary structures. Howewer recent studies have shown that all these enzymes may have evolved from a common ancestor through gene duplication and fusion which has led to extensive repeating sequences in the corresponding subunits.

Amino Acid Sequence↗
PubMed1975

Gene duplication as a mechanism of genetic adaptation in Saccharomyces cerevisiae.

It has been shown that specific mutations of the gene that codes for the general acid monophophatase (Aphtase) of S. cerevisiae can increase the affinity of this enzyme for beta-glycerophosphate (BGP) and thereby provide this organism with the capacity to exploit extremely low concentrations of this organic phosphate (Francis and Hansche 1973). In this report two additional avenues are demonstrated to be available to this organism for increasing its capacity to exploit low concentrations of organic phosphates. One avenue is through mutations that increase the amount of Aphtase that associates with the cell wall, where it catalizes the hydrolysis of exogenous organic phosphates. The other avenue is through duplication of the gene that codes for Aphtase, doubling the amount of Aphtase synthesized.--The spontaneous duplication of the structural gene of Aphtase and the incorporation of the duplicate into this experimental population as a means of exploiting low concentrations of exogenous organic phosphates provides direct support for the first step of the mechanism through which new metabolic functions are postulated to evolve.

Acid Phosphatase↗
PubMed1978

Gene duplication in Saccharomyces cerevisiae.

Five independent duplications of the acid-phosphatase (aphtase) structural gene (acp1) were recovered from chemostat populations of S. cerevisiae that were subject to selection for in vivo hyper-aphtase activity. Two of the duplications arose spontaneously. Three of them were induced by UV. All five of the duplication events involved the transpositioning of the aphtase structural gene, acp1, and all known genes distal to acp1 on the right arm of chromosome II, to the terminus of an arm of other unknown chromosomes. One of the five duplicated regions of the right arm of chromosome II was found to be transmitted mitotically and meiotically with very high fidelity. The other four duplicated regions of the right arm of chromosome II were found to be unstable, being lost at a rate of about 2% per mitosis. However, selection for increased fidelity of mitotic transmission was effective in one of these strains. No tandem duplications of the aphtase structural gene were found.

Acid Phosphatase↗
PubMed2026

Adaptive deletion of functional duplicate genes in Drosophila.

Gene deletion is traditionally viewed as a nonadaptive mechanism that eliminates functional redundancy, yet emerging evidence indicates that it disproportionately affects tissue-specific duplicates with unique functions. Here, we test whether gene deletion preferentially removes weakly constrained, degenerating duplicates or instead eliminates functionally active duplicates through an adaptive process. To identify the evolutionary and functional factors that determine which duplicates are lost, we systematically analyzed 100 gene deletion events in Drosophila by integrating sequence, expression, interaction, and structural data. We uncovered a strong bias toward the loss of younger child copies among functionally unique duplicates, whereas no such bias was observed for redundant duplicates. Contrary to expectations under relaxed constraint, deleted functionally unique genes evolve more slowly, show higher expression, engage in more protein-protein interactions, and do not exhibit elevated structural divergence or intrinsic disorder relative to redundant duplicates. When compared with single-copy genes, deleted functionally unique genes display similar evolutionary rates, slightly lower expression, greater network connectivity, comparable structural divergence, and lower intrinsic disorder. These patterns suggest that deletion frequently affects functionally active rather than degenerate genes. Collectively, our results support the hypothesis that gene deletion in Drosophila can represent an adaptive process acting on transiently functional duplicates, potentially driven by either genome streamlining or context-dependent deleterious effects.

evolution↗
PubMed1979

Polymorphism and loss of duplicate gene expression: a theoretical study with application of tetraploid fish.

We studied the fixation of null alleles at independent duplicate loci, assuming that wild-type active alleles mutate irreversibly to nonfunctional null alleles and that the population is finite and panmictic. Solving the two-dimensional Kolmogorov backward equation numerically, we obtained the rate at which one of the active genes is lost and the amount of heterozygosity at specified times. Previously harmful genes, including recessive lethals, can be fixed at one of the duplicate loci, which would not happen with a single locus. Examination of data from several fish families showed that the rate of fixation of null alleles is too slow and the amount of heterozygosity too small to be compatible with complete recessivity at all loci. Our conclusion differs in this regard from that of Bailey et al. [Bailey, G.S., Poulter, R. T. M. & Stockwell, P. A. (1978) Proc. Natl. Acad. Sci. USA 75, 5575--5579]. They also reported that the time taken for 50% of the loci to be fixed for null alleles is approximately 15N + v-3/4, in which N and v are the effective population sizgote is lethal. We found that the fixation rate depends not only on N, but also on Nv.

Alleles↗
PubMed1977

Gene duplication in salmonid fishes: evidence for duplicated but catalytically equivalent A4 lactate dehydrogenases.

Skeletal muscle tissues from many species of salmonid fish are known to exhibit a set of three of five isozymes for A4-type lactate dehydrogenase (L-lactate: NAD oxidoreductase, E.C. 1.1.1.27), but the genetic basis for this isozyme system has not previously been assessed. This isozyme system was purified to homogeneity from salmon (Oncorhynchus tshawytscha) and shown to be composed of two polypeptides. Aalpha and Abeta, in binomial tetrameric combinations. Amino acid analysis revealed that Aalpha and Abeta are closely related but genetically distinct proteins, and thus are coded for the recently duplicated structural loci. Catalytic studies on the purified intact salmon isozyme system and on the isozymically pure Aalpha4 and Abeta4 homotetramers from brown trout (Salmo trutta) revealed no significant differences in catalytic properties among these enzymes, suggesting equivalent catalytic function of Aalpha and Abeta. These results, in combination with studies on polypeptide and isozyme ratios, suggest that one of the duplicated loci in salmon may be drifting toward a nonfunctional state by accumulation of mutations in regulatory DNA rather than in the structural gene itself.

Amino Acid Sequence↗