scholarly journals ROLE OF BIASED GENE CONVERSION IN ONE-LOCUS NEUTRAL THEORY AND GENOME EVOLUTION

Genetics ◽  
1983 ◽  
Vol 105 (2) ◽  
pp. 461-468
Author(s):  
James Bruce Walsh
Keyword(s):  
Gene Conversion ◽  
Substitution Rate ◽  
Neutral Theory ◽  
Gene Families ◽  
The Family ◽  
Biased Gene Conversion ◽  
Fixation Probabilities ◽  
Time Required ◽  
New Alleles

ABSTRACT The implications of biased gene conversion acting on selectively neutral alleles are investigated for a single diallelic locus in a finite population. Even a very slight conversion bias can significantly alter fixation probabilities. We argue that most newly arising mutants will be at a conversion disadvantage, resulting in a potentially greatly decreased substitution rate of new alleles compared with predictions from strict neutral theory. Thus, conversion bias potential allows for conservation of particular alleles without having to invoke selection. Conversely, we also show that bias can be important in the maintenance of repeated gene families without altering the substitution rate at other loci that experience the same amount of conversion bias, provided that the number of genes in the family is sufficiently large. Bias can, therefore, be important at the genomic level and yet be unimportant at the populational level. Finally, we discuss the role of biased gene conversion in speciation events, concluding that this type of molecular turnover acting independently at many individual loci is very unlikely to decrease the time required for two allopatric populations to speciate.

scholarly journals The Role of GC-Biased Gene Conversion in Shaping the Fastest Evolving Regions of the Human Genome

2011 ◽  
Vol 29 (3) ◽  
pp. 1047-1057 ◽  
Author(s):  
D. Kostka ◽  
M. J. Hubisz ◽  
A. Siepel ◽  
K. S. Pollard
Keyword(s):  
Human Genome ◽  
Gene Conversion ◽  
Biased Gene Conversion

scholarly journals HUMA ORANG BADUY DALAM PEMBENTUKAN SIKAP SWASEMBADA PANGAN

2015 ◽  
Vol 7 (3) ◽  
pp. 559
Author(s):  
Yudi Putu Satriadi
Keyword(s):  
Land Use ◽  
Descriptive Analysis ◽  
Production Costs ◽  
Survey Method ◽  
Traditional Management ◽  
Self Sufficiency ◽  
The Family ◽  
Time Required ◽  
Depth Interviews

AbstrakPenelitian ini bertujuan untuk mengkaji peran budaya lokal dalam mendukung program ketahanan pangan. Penelitian dilakukan di daerah Baduy menggunakan metoda survei, observasi, wawancara mendalam dan analis deskriptif. Fokus kajian dilakukan terhadap huma sebagai sumber penghasil pangan untuk memenuhi kebutuhan keluarga. Hasil penelitian menunjukkan bahwa huma sebagai sumber penghasil pangan diatur pengelolaannya mengikuti adat yang dilestarikan dengan  beberapa kriteria yaitu mempertahankan tata ruang melalui pembatasan perubahan tata guna lahan; memerhatikan  waktu yang diperlukan   untuk pengembalian status nutrisi lahan dan optimasi komponen biotik dan abiotik untuk mendukung produksi; mempertahankan komponen ekosistem untuk mendukung produktivitas huma, meminimalisasi biaya produksi melalui pembatasan pengolahan lahan, tidak merokok, mengurangi pembicaraan yang tidak produktif, lebih mengefisienkan waktu kerja, serta mengatur peruntukan padi dan beras dengan pengaturan pendistribusian yang ketat.  Penelitian ini memberikan 3 rekomendasi yaitu (i) kearifan lokal tetap dipertahankan dengan memerhatikan kemajuan ilmu pengetahuan dan teknologi untuk mendukung swasembada pangan; (ii) menyesuaikan daya dukung lingkungan dengan program eksploitasi;  (iii)  menyusun tata ruang berdasarkan potensi penggunaan lahan dan kajian sosial budaya.  AbstractThis study aims to assess the role of local culture in supporting security programs of food self-supporting in the Baduyarea.  This research conducted a survey method, observation, in-depth interviews and descriptive analysis. This study focusonhuma as a source of food to meet the needs of the family. The results showed that the huma as a source of food is set to follow the traditional management preserved with some criteria.They are: maintaining spatial through the restrictions on land use changing, paying attention to the time required for returning the nutritional status of the land and optimizingthe biotic and abiotic components to support production, maintaining ecosystem components to support huma productivity, minimizing production costs through restrictions on land management, not smoking, reducing unproductive talks, being more efficient in working time, as well as regulating the allotment of rice and rice with a tightdistribution. This study provides three recommendations: (i) local knowledge is maintained by taking into account the advancement of science and technology to support food self-sufficiency; (ii) adjusting the carrying capacity of the environment to the exploitation program; (iii) developing spatial based on potential land use and socio-cultural studies.

scholarly journals Genomic Structure and Evolution of Multigene Families: “Flowers” on the Human Genome

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Hie Lim Kim ◽  
Mineyo Iwase ◽  
Takeshi Igawa ◽  
Tasuku Nishioka ◽  
Satoko Kaneko ◽  
...  
Keyword(s):  
Human Genome ◽  
Gene Conversion ◽  
Genomic Structure ◽  
Gene Families ◽  
Protein Coding ◽  
Average Gene Density ◽  
The Mean ◽  
Average Gene ◽  
Computer Simulation Studies

We report the results of an extensive investigation of genomic structures in the human genome, with a particular focus on relatively large repeats (>50 kb) in adjacent chromosomal regions. We named such structures “Flowers” because the pattern observed on dot plots resembles a flower. We detected a total of 291 Flowers in the human genome. They were predominantly located in euchromatic regions. Flowers are gene-rich compared to the average gene density of the genome. Genes involved in systems receiving environmental information, such as immunity and detoxification, were overrepresented in Flowers. Within a Flower, the mean number of duplication units was approximately four. The maximum and minimum identities between homologs in a Flower showed different distributions; the maximum identity was often concentrated to 100% identity, while the minimum identity was evenly distributed in the range of 78% to 100%. Using a gene conversion detection test, we found frequent and/or recent gene conversion events within the tested Flowers. Interestingly, many of those converted regions contained protein-coding genes. Computer simulation studies suggest that one role of such frequent gene conversions is the elongation of the life span of gene families in a Flower by the resurrection of pseudogenes.

scholarly journals SELECTION AND BIASED GENE CONVERSION IN A MULTIGENE FAMILY: CONSEQUENCES OF INTERALLELIC BIAS AND THRESHOLD SELECTION

Genetics ◽  
1986 ◽  
Vol 112 (3) ◽  
pp. 699-716
Author(s):  
James Bruce Walsh
Keyword(s):  
Gene Family ◽  
Gene Conversion ◽  
Finite Population ◽  
Gene Families ◽  
Threshold Selection ◽  
Population Sampling ◽  
Fitness Functions ◽  
Limit Model ◽  
Biased Gene Conversion ◽  
Arbitrary Frequency

ABSTRACT In a previous paper, I investigated the interactions in a gene family of additive selection and biased gene conversion in a finite population when conversion events are rare. Here I extend my "weak-conversion limit" model by allowing biased interallelic conversion (conversion between alleles at the same locus) of arbitrary frequency and various threshold selection schemes for rare interlocus conversion events. I suggest that it is not unreasonable for gene families to experience threshold fitness functions, and show that certain types of thresholds can greatly constrain the rate at which advantageous alleles are fixed as compared to other fitness schemes, such as additive selection. It is also shown that the double sampling process operating on a gene family in a finite population (sampling over the number of genes in the gene family and over the number of individuals in the population) can have interesting consequences. For selectively neutral alleles that experience interallelic bias, the probability of fixation at each single locus may be essentially neutral, but the cumulative effects on the entire gene family of small departures from neutrality can be significant, especially if the gene family is large. Thus, in some situations, gene families can respond to directional forces that are weak in comparison to drift at single loci.

Palliative Care Work, Between Death and Discharge

2005 ◽  
Vol 21 (2) ◽  
pp. 97-102 ◽  
Author(s):  
Margaret O'Connor ◽  
Louise Peters ◽  
Susan Lee ◽  
Cecilia Webster
Keyword(s):  
Palliative Care ◽  
Turnover Time ◽  
Her Family ◽  
Care Services ◽  
The Family ◽  
Palliative Care Services ◽  
Time Required ◽  
Death Care

This paper discusses a small study that was undertaken in a palliative care unit (PCU) to demonstrate reasons for the lengthy patient turnover time after the death of a patient. The study arose from a managerial challenge about the PCU's efficiency in comparison to other settings of care. While Palliative care services in Australia are loosely funded on a per diem rate, casemix funding models for inpatient services in other settings reward efficiency in terms of length of stay (1). The aim of the study was to undertake a post-death survey, from the nursing perspective, of activities and the time required to deliver follow-up care, as required, to the deceased patient and his/her family. Details of the post-death episode for all patients who died in the PCU over two time periods were collected using a newly designed tool. This paper does not argue for the incorporation of post-death nursing work as a measure of efficiency or quality; rather, it is a demonstration of the type of work and the time involved in carrying out post-death work. This nursing work is an essential but hidden and generally unacknowledged element of palliative care and, not surprisingly, there is a dearth of literature describing the role of the nurse in providing care of the family and others after the patient has died. This project has provided important information about the factors that Protract after-death care, and gives some insight into the role of the nurse after a death occurs in a PCU.

scholarly journals Intracellular selection, conversion bias, and the expected substitution rate of organelle genes.

Genetics ◽  
1992 ◽  
Vol 130 (4) ◽  
pp. 939-946 ◽  
Author(s):  
J B Walsh
Keyword(s):  
Gene Conversion ◽  
Substitution Rate ◽  
Germ Line ◽  
Genome Replication ◽  
Initial Fixation ◽  
Conversion Rates ◽  
Degradation Rates ◽  
Biased Gene Conversion ◽  
Multiple Copies ◽  
Probability Of Fixation

Abstract A key step in the substitution of a new organelle mutant throughout a population is the generation of germ-line cells homoplasmic for that mutant. Given that each cell typically contains multiple copies of organelles, each of which in turn contains multiple copies of the organelle genome, processes akin to drift and selection in a population are responsible for producing homoplasmic cells. This paper examines the expected substitution rate of new mutants by obtaining the probability that a new mutant is fixed throughout a cell, allowing for arbitrary rates of genome turnover within an organelle and organelle turnover within the cell, as well as (possibly biased) gene conversion and genetic differences in genome and/or organelle replication rates. Analysis is based on a variation of Moran's model for drift in a haploid population. One interesting result is that if the rate of unbiased conversion is sufficiently strong, it creates enough intracellular drift to overcome even strong differences in the replication rates of wild-type and mutant genomes. Thus, organelles with very high conversion rates are more resistant to intracellular selection based on differences in genome replication and/or degradation rates. It is found that the amount of genetic exchange between organelles within the cell greatly influences the probability of fixation. In the absence of exchange, biased gene conversion and/or differences in genome replication rates do not influence the probability of fixation beyond the initial fixation within a single organelle. With exchange, both these processes influence the probability of fixation throughout the entire cell. Generally speaking, exchange between organelles accentuates the effects of directional intracellular forces.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals GC-biased gene conversion conceals the prediction of the nearly neutral theory in avian genomes

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Paulina Bolívar ◽  
Laurent Guéguen ◽  
Laurent Duret ◽  
Hans Ellegren ◽  
Carina F. Mugal
Keyword(s):  
Gene Conversion ◽  
Neutral Theory ◽  
Biased Gene Conversion ◽  
Nearly Neutral Theory ◽  
Avian Genomes

scholarly journals Influence of Recombination and GC-biased Gene Conversion on the Adaptive and Nonadaptive Substitution Rate in Mammals versus Birds

2018 ◽  
Vol 36 (3) ◽  
pp. 458-471 ◽  
Author(s):  
Marjolaine Rousselle ◽  
Alexandre Laverré ◽  
Emeric Figuet ◽  
Benoit Nabholz ◽  
Nicolas Galtier
Keyword(s):  
Gene Conversion ◽  
Substitution Rate ◽  
Biased Gene Conversion

Non-Normative Events and Family Functioning: The Role of the Family Psychologist

1993 ◽  
Author(s):  
Michele Harway ◽  
◽  
Nancy Boyd-Franklin ◽  
Robert Geffner ◽  
Marsali Hansen ◽  
...  
Keyword(s):  
Family Functioning ◽  
The Family

Mental Health of War-Affected Youth in Two Conflicts: The Role of the Family, Community and Classroom

2008 ◽  
Author(s):  
Ivelina Borisova ◽  
Theresa Betancourt ◽  
Wietse Tol ◽  
Ivan Komproe ◽  
Mark Jordans ◽  
...  
Keyword(s):  
Mental Health ◽  
The Family
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