scholarly journals FURTHER STUDY ON THE GENETIC CORRELATION BETWEEN MEMBERS OF A MULTIGENE FAMILY

Genetics ◽  
1981 ◽  
Vol 99 (3-4) ◽  
pp. 555-571
Author(s):  
Tomoko Ohta
Keyword(s):  
Natural Selection ◽  
Family Size ◽  
Multigene Family ◽  
Crossing Over ◽  
Total Size ◽  
Small Shift ◽  
Unequal Crossing Over ◽  
The Family ◽  
Number Of Genes ◽  
The Mean

ABSTRACT The extent of genetic similarity (in terms of identity coefficients) was investigated among members of a multigene family that is evolving under mutation, unequal crossing over and random genetic drift. The method of KIMURA and OHTA (1979) was used, but the possibility was incorporated that the length of the shift (in terms of the number of genes) involved in unequal crossing over can be more than one gene unit. Extensive numerical analyses show that, at equilibrium, the identity coefficients between two gene members are practically independent of their distance apart on the chromosome when the mean length of the shift at unequal crossing over is more than 10% of the total size of the family. In that case, the approximate treatment by OHTA (1980) is shown to be valid, but when the mean length of the shift is less than IO%, the average identity coefficient at equilibrium is underestimated. In order to clarify the effect of natural selection responsible for keeping the family size stable, Monte Carlo simulation studies were performed. The results indicate that the identity coefficients are not greatly influenced by natural selection on gene family size, particularly when the number of genes shifted is small compared to the family size. In addition, with sufficiently strongselection on family size, unequal crossovers with a large shift (such as with maximum shift of 90% of the family size) become ineffective and almost indisdnguishable from those with a small shift.

scholarly journals Possible role of natural selection in the formation of tandem-repetitive noncoding DNA.

Genetics ◽  
1994 ◽  
Vol 136 (1) ◽  
pp. 333-341
Author(s):  
W Stephan ◽  
S Cho
Keyword(s):  
Natural Selection ◽  
Satellite Dna ◽  
Repeat Length ◽  
Crossing Over ◽  
Recombination Rates ◽  
Noncoding Dna ◽  
Satellite Dnas ◽  
Unequal Crossing Over ◽  
Wide Range ◽  
Long Range Ordering

Abstract A simulation model of sequence-dependent amplification, unequal crossing over and mutation is analyzed. This model predicts the spontaneous formation of tandem-repetitive patterns of noncoding DNA from arbitrary sequences for a wide range of parameter values. Natural selection is found to play an essential role in this self-organizing process. Natural selection which is modeled as a mechanism for controlling the length of a nucleotide string but not the sequence itself favors the formation of tandem-repetitive structures. Two measures of sequence heterogeneity, inter-repeat variability and repeat length, are analyzed in detail. For fixed mutation rate, both inter-repeat variability and repeat length are found to increase with decreasing rates of (unequal) crossing over. The results are compared with data on micro-, mini- and satellite DNAs. The properties of minisatellites and satellite DNAs resemble the simulated structures very closely. This suggests that unequal crossing over is a dominant long-range ordering force which keeps these arrays homogeneous even in regions of very low recombination rates, such as at satellite DNA loci. Our analysis also indicates that in regions of low rates of (unequal) crossing over, inter-repeat variability is maintained at a low level at the expense of much larger repeat units (multimeric repeats), which are characteristic of satellite DNA. In contrast, the microsatellite data do not fit the proposed model well, suggesting that unequal crossing over does not act on these very short tandem arrays.

scholarly journals Genetic variation in small multigene families

1981 ◽  
Vol 37 (2) ◽  
pp. 133-149 ◽  
Author(s):  
Tomoko Ohta
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Globin Gene ◽  
Gene Organization ◽  
Crossing Over ◽  
Random Genetic Drift ◽  
Cycle Model ◽  
Unequal Crossing Over ◽  
Biological Phenomena ◽  
Chromosomal Recombination

SUMMARYIn order to understand the evolution of genetic systems in which two genes are tandemly repeated (small multigene family) such as has been recently found in the haemoglobin α loci of primates, haemoglobin β loci of mouse and rarbit and other proteins, a population genetics approach was used. Special reference was made to the probarility of gene identity (identity coefficient), when unequal crossing-over is continuously occurring as well as random genetic drift, inter-chromosomal recombination and mutation. Two models were studied, cycle and selection models. The former assumes that unequal crossing-over occurs in cycles of duplication and deletion, and that the equilibrium identity coefficients were obtained. The latter is based on more realistic biological phenomena, and in this model it is assumed that natural selection is responsible for eliminating chromosomes with extra or deficient gene dose. Unequal crossing-over, inter-chromosomal recombination and natural selection lead to a duplication-deletion balance, which can then be treated as though it were a cycle model. The basic parameter is the rate of duplication-deletion which is shown to be approximately equal to 2(u + 2β)X, where u is the unequal crossing-over rate, 2β is the inter-chromosomal recombination rate and X is the frequency of chromosomes with three genes or of that with one gene. Genetic variation of the globin gene family, of which gene organization is known in most detail, is discussed in the light of the present analyses.

Family Size from the Child's Point of View

1982 ◽  
Vol 14 (3) ◽  
pp. 319-327 ◽  
Author(s):  
C. M. Langford
Keyword(s):  
Great Britain ◽  
Family Size ◽  
Point Of View ◽  
Number Of Children ◽  
The Family ◽  
Mean Size ◽  
The Mean ◽  
Using Data

SummaryThe mean size of sibship in which children are reared is greaterthan the mean number of children born to those children's parents' generation. In this paper, family size is considered from the child's point of view, and estimates made of how many siblings (and some other relatives) children have, using data from a survey carried out in Great Britain in the late 1960s. The size of the ‘family’ experienced by children is largerthan may at first sight appear. For example, women who married in the period 1941–55 onaverage had 2·2 children, but these women's children grew up, on average, in sibships of3·5 children; 38% of them grew up in a family with four children or more. Moreover, on average, these women's children had six uncles and aunts and possibly twice that number of first cousins. More than half of the children had at least one parent who was brought up in a family with six children or more and almost one in five had at least one parent who came from a family with ten children or more.

scholarly journals Simulating Evolution by Gene Duplication

Genetics ◽  
1987 ◽  
Vol 115 (1) ◽  
pp. 207-213 ◽  
Author(s):  
Tomoko Ohta
Keyword(s):  
Natural Selection ◽  
Single Gene ◽  
Genetic Load ◽  
Gene Families ◽  
Functional Gene ◽  
Gene Copy ◽  
Crossing Over ◽  
Random Drift ◽  
Unequal Crossing Over ◽  
New Gene

ABSTRACT By considering the recent finding that unequal crossing over and other molecular interactions are contributing to the evolution of multigene families, a model of the origin of repetitive genes was studied by Monte Carlo simulations. Starting from a single gene copy, how genetic systems evolve was examined under unequal crossing over, random drift and natural selection. Both beneficial and deteriorating mutations were incorporated, and the latter were assumed to occur ten times more frequently than the former. Positive natural selection favors those chromosomes with more beneficial mutations in redundant copies than others in the population, but accumulation of deteriorating mutations (pseudogenes) have no effect on fitness so long as there remains a functional gene. The results imply the following: (1) Positive natural selection is needed in order to acquire gene families with new functions. Without it, too many pseudogenes accumulate before attaining a functional gene family. (2) There is a large fluctuation in the outcome even if parameters are the same. (3) When unequal crossing over occurs more frequently, the system evolves more rapidly. It was also shown, under realistic values of parameters, that the genetic load for acquiring a new gene is not as large as J. B. S. Haldane suggested, but not so small as in a model in which a system for selection started from already redundant genes.

scholarly journals AN EXTENSION OF A MODEL FOR THE EVOLUTION OF MULTIGENE FAMILIES BY UNEQUAL CROSSING OVER

Genetics ◽  
1979 ◽  
Vol 91 (3) ◽  
pp. 591-607
Author(s):  
Tomoko Ohta
Keyword(s):  
Population Genetics ◽  
Diffusion Equation ◽  
Multigene Family ◽  
Gene Families ◽  
Multigene Families ◽  
Crossing Over ◽  
Homologous Chromosomes ◽  
Unequal Crossing Over ◽  
Random Frequency ◽  
Two Measures

ABSTRACT Evolution of a multigene family is studied from the standpoint of population genetics. It is assumed that the multigene family is undergoing continuous interchromosomal unequal crossing over, mutation and random frequency drift. The equilibrium properties of the probability of gene identity (clonality) are investigated, using two measures: identity probability within and between chromosomes. The measures represent homogeneity of genes within a family in one chromosome and $milarity of gene families between two homologous chromosomes. The means, the variances and the covariance of these two measures of identity probability are obtained by using the diffusion equation method. It is shown that the means and the variances are generally smaller than those predicted in the previous model assuming intrachromosomal (sister chromatid) unequal crossing over (OHTA 1978a,b).

scholarly journals THEORETICAL POPULATION GENETICS OF REPEATED GENES FORMING A MULTIGENE FAMILY

Genetics ◽  
1978 ◽  
Vol 88 (4) ◽  
pp. 845-861
Author(s):  
Tomoko Ohta
Keyword(s):  
Multigene Family ◽  
Finite Population ◽  
Gene Families ◽  
Crossing Over ◽  
The Family ◽  
Random Frequency ◽  
Theoretical Population ◽  
Two Measures ◽  
Theoretical Population Genetics ◽  
Repeated Genes

ABSTRACT The evolution of repeated genes forming a multigene family in a finite population is studied with special reference to the probability of gene identity, i.e., the identity probability of two gene units chosen from the gene family. This quantity is called clonality and is defined as the sum of squares of the frequencies of gene lineages in the family. The multigene family is undergoing continuous unequal somatic crossing over, ordinary interchromosomal crossing over, mutation and random frequency drift. Two measures of clonality are used: clonality within one chromosome and that between two different chromosomes. The equilibrium properties of the means, the variances and the covariance of the two measures of clonality are investigated by using the diffusion equation method under the assumption of constant number of gene units in the multigene family. Some models of natural selection based on clonality are considered. The possible significance of the variance and covariance of clonality among the chromosomes on the adaptive differentiation of gene families such as those producing antibodies is discussed.

scholarly journals An Analysis of Rotational Line Mating Using Computer Simulation

2005 ◽  
pp. 35-39
Author(s):  
Szilvia Szőke ◽  
István Komlósi
Keyword(s):  
Family Size ◽  
First Generation ◽  
Random Mating ◽  
Rotational Line ◽  
Gene Frequencies ◽  
The Family ◽  
Discrete Population ◽  
Males And Females ◽  
The Mean ◽  
Better Than

In a simulation examination, we analyzed the effect of the family size and the rate of pairing on the survival of rare genes, to keep the level of variation of the genepool and to avoid the loss of alleles.The population size was 360 animals. In the simulation, we calculated on the basis of a discrete population. We placed the 360 animals into different clusters, with 3 types of frequencies of alleles and 3 types of groups. We assumed 2, 3 or 4 alleles in 8 loci. We generated 15 generations using the same mating and selection system used in practise. The simulation was written with Scilab 2.7.2 software, and evaluated with SPSS software.There were significant changes in the effect of family size on the genetic variation in the following cases: when the base population had the same gene frequencies in all loci, and when the gene frequencies were between 0.125-0.75. In these cases, we found that the smaller families (10 animals/cluster) were better than the larger families (30 or 90 animals/cluster). The first generation where there accured a loss of alleles was averagely earliest in larger families (90 animal/cluster). This average was 3.37 generations. When we are searched the effects of the different rates of pairing we found those cases most favourable when the ratio of males and females was 1:2 or 1:4 as compared to 1:9. The first generation where there was a loss of alleles was averagely earliest at the ratio of pairing male and females of 1:9 (the mean was 3.05 generations) when the frequency of the rarest allele was 0.0069.The recently introduced rotating-random mating system is an eligible method for small populations for the preservation of genes.

scholarly journals Simulation study of a multigene family, with special reference to the evolution of compensatory advantageous mutations.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 247-252 ◽  
Author(s):  
C J Basten ◽  
T Ohta
Keyword(s):  
Model Selection ◽  
Gene Conversion ◽  
Simulation Study ◽  
Multigene Family ◽  
Negative Selection ◽  
Crossing Over ◽  
Simulation Studies ◽  
Unequal Crossing Over ◽  
Deleterious Alleles ◽  
Compensatory Mutations

Abstract We investigate the evolution of a multigene family incorporating the forces of drift, mutation, gene conversion, unequal crossing over and selection. The use of simulation studies is required due to the complexity of the model. Selection is modeled in two modes: positive selection as a function of the number of different beneficial alleles and negative selection against deleterious alleles. We assume that gene conversion is unbiased, and that all mutations are initially deleterious. Compensation between mutants creates beneficial and neutral alleles, and allowances are made for compensatory mutations either within or between the members of a multigene family. We find that gene conversion can enhance the rate of acquisition of compensatory advantageous mutations when genes are redundant.

Mapping Unequal Crossing over Hotspot Region of Simple Sequence Repeat in Maize

2009 ◽  
Vol 35 (5) ◽  
pp. 958-961
Author(s):  
Ji-Hua TANG ◽  
Xi-Qing MA ◽  
Wen-Tao TENG ◽  
Jian-Bing YAN ◽  
Jing-Rui DAI ◽  
...  
Keyword(s):  
Simple Sequence Repeat ◽  
Crossing Over ◽  
Sequence Repeat ◽  
Unequal Crossing Over ◽  
Simple Sequence

scholarly journals Patent Value and Survival of Patents

2021 ◽  
Vol 7 (2) ◽  
pp. 119
Author(s):  
Jung-Tae Hwang ◽  
Byung-Keun Kim ◽  
Eui-Seob Jeong
Keyword(s):  
Family Size ◽  
Positive Impact ◽  
European Patent ◽  
Patent Data ◽  
Patent Value ◽  
Traditional Family ◽  
Ex Post ◽  
The Family ◽  
Research Findings ◽  
Private Value

This study investigated the effect of patent value on the renewal (survival) of patents. The private value of patents can be one of the main pillars sustaining a firm’s value, and the estimation of the value may contribute to the strategic management of firms. The current study aimed to confirm the recent research findings with survival analysis, focusing on the more homogeneous patent data samples. In this study, a dataset is constructed from a cohort of 6646 patents from the 1996 and 1997 application years, using patent data from the European Patent Office (EPO). We found that the family size and non-patent backward citations exhibited profound impacts on patent survival. This result is in line with numerous studies, indicating the positive impact of science linkages in the biotechnology and pharmaceutical fields. It was also found that the effect of the ex-post indicator is not as strong as the ex-ante indicators, like traditional family size and backward citations. In short, the family size matters most for the survival of patents, according to the current research.

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