Change of the crossing-over frequency inDrosophila during selection for resistance to temperature fluctuations

Genetica ◽  
1985 ◽  
Vol 67 (1) ◽  
pp. 73-78 ◽  
Author(s):  
A. A. Zhuchenko ◽  
A. B. Korol ◽  
L. P. Kovtyukh
Keyword(s):  
Temperature Fluctuations ◽  
Crossing Over ◽  
Selection For

scholarly journals Deleterious mutations as an evolutionary factor: 1. The advantage of recombination

1984 ◽  
Vol 44 (2) ◽  
pp. 199-217 ◽  
Author(s):  
Alexey S. Kondrashov
Keyword(s):  
Recombination Frequency ◽  
Decisive Role ◽  
Crossing Over ◽  
Whole Genome ◽  
Critical Number ◽  
Deleterious Mutations ◽  
Mutation Load ◽  
Sexual Population ◽  
Physiological Cost ◽  
Selection For

SUMMARYA population with u deleterious mutations per genome per generation is considered in which only those individuals that carry less than a critical number of k mutations are viable. It has been shown previously that under such conditions sexual reproduction is advantageous. Here we consider selection at a locus that determines recombination frequency of the whole genome. The value v = u/ √ k has been found to play the decisive role. When v < 0·35 the direction of selection for recombination may be different for different cases, but the intensity of selection is always very small. The advantage of recombination becomes considerable when v > 0·5, its growth under increasing v being approximately linear. If v > 2 no less than 95% of the progeny are bound to die because of the selection against deleterious mutations. Since this seems to be too great a mutation load, we may assume 0·5 < v < 2·0 for any sexual population if mutation really maintains crossing-over. Results on selection at a locus which controls mutability provide evidence that v is located within the specified interval if the physiological cost of a twofold reduction of the mutation rate is within the range 10–80%. A number of consequences of this hypothesis about the mechanism of selection for sex and recombination are discussed.

scholarly journals SELECTION FOR REDUCED CROSSING OVER IN DROSOPHILA MELANOGASTER

Genetics ◽  
1974 ◽  
Vol 76 (3) ◽  
pp. 447-451
Author(s):  
Nasr F Abdullah ◽  
Brian Charlesworth
Keyword(s):  
Drosophila Melanogaster ◽  
Regression Coefficient ◽  
Selection Line ◽  
Crossing Over ◽  
Base Population ◽  
The Third ◽  
Significant Difference ◽  
Selection For ◽  
Significant Regression ◽  
Recombination Value

ABSTRACT Selection was practiced for reducing crossing over between the third chromosome genes Sb and H2 of Drosophila melanogaster, the method employed was to select the repulsion double heterozygotes Sb+/+H2 every generation. Two replicate selection lines were maintained. After 24 generations of selection, Line 1 showed no significant difference from the control, although the regression of recombination value on generation was significant. In generation 20, Line 2 had a significantly lower recombination value than the control, as well as having a highly significant regression coefficient. No chromosome rearrangements were involved in the response. It was concluded that there was substantial genic variability in the frequency of crossing over between Sb and H2 in the base population.

scholarly journals Somatic and germinal recombination of a direct repeat in Arabidopsis.

Genetics ◽  
1992 ◽  
Vol 132 (2) ◽  
pp. 553-566
Author(s):  
F F Assaad ◽  
E R Signer
Keyword(s):  
Homologous Recombination ◽  
Transgenic Line ◽  
Direct Repeat ◽  
Crossing Over ◽  
Neomycin Phosphotransferase ◽  
Concerted Action ◽  
Somatic Recombination ◽  
High Fraction ◽  
Selection For ◽  
Or Gene

Abstract Homologous recombination between a pair of directly repeated transgenes was studied in Arabidopsis. The test construct included two different internal, non-overlapping deletion alleles of npt (neomycin phosphotransferase) flanking an active HPT (hygromycin phosphotransferase) gene. This construct was introduced into Arabidopsis by agrobacterium-mediated transformation with selection for resistance to hygromycin, and two independent single-insert lines were analyzed. Selection for active NPT by resistance to kanamycin gave both fully and partly (chimeric) recombinant seedlings. Rates for one transgenic line were estimated at less than 2 x 10(-5) events per division for germinal and greater than 10(-6) events per division for somatic recombination, a much smaller difference than between meiotic and mitotic recombination in yeast. Southern analysis showed that recombinants could be formed by either crossing over or gene conversion. A surprisingly high fraction (at least 2/17) of the recombinants, however, appeared to result from the concerted action of two or more independent simple events. Some evolutionary implications are discussed.

Framework for Selecting Vocabulary for Preliterate Children Who Use Augmentative and Alternative Communication

2019 ◽  
Vol 28 (3) ◽  
pp. 1000-1009
Author(s):  
Allison Bean ◽  
Lindsey Paden Cargill ◽  
Samantha Lyle
Keyword(s):  
Language Impairment ◽  
Augmentative And Alternative Communication ◽  
Developmentally Appropriate ◽  
School Age Children ◽  
Alternative Communication ◽  
School Based ◽  
Selection For ◽  
Nonverbal Children ◽  
Grammatical Structures ◽  
Insufficient Knowledge

Purpose Nearly 50% of school-based speech-language pathologists (SLPs) provide services to school-age children who use augmentative and alternative communication (AAC). However, many SLPs report having insufficient knowledge in the area of AAC implementation. The objective of this tutorial is to provide clinicians with a framework for supporting 1 area of AAC implementation: vocabulary selection for preliterate children who use AAC. Method This tutorial focuses on 4 variables that clinicians should consider when selecting vocabulary: (a) contexts/environments where the vocabulary can be used, (b) time span during which the vocabulary will be relevant, (c) whether the vocabulary can elicit and maintain interactions with other people, and (d) whether the vocabulary will facilitate developmentally appropriate grammatical structures. This tutorial focuses on the role that these variables play in language development in verbal children with typical development, verbal children with language impairment, and nonverbal children who use AAC. Results Use of the 4 variables highlighted above may help practicing SLPs select vocabulary that will best facilitate language acquisition in preliterate children who use AAC.

Teaching Partners to Support Communication for Adults with Acquired Communication Impairment

2013 ◽  
Vol 22 (1) ◽  
pp. 4-15 ◽  
Author(s):  
Laura J. Ball ◽  
Joanne Lasker
Keyword(s):  
Practice Patterns ◽  
Communicative Competence ◽  
Communication Disorders ◽  
Communication Impairment ◽  
Communication Partner ◽  
Communication Partners ◽  
Selection For ◽  
Communication Needs ◽  
End Of Life Communication ◽  
Lateral Sclerosis

Abstract For adults with acquired communication impairment, particularly those who have communication disorders associated with stroke or neurodegenerative disease, communication partners play an important role in establishing and maintaining communicative competence. In this paper, we assemble some evidence on this topic and integrate it with current preferred practice patterns (American Speech-Language-Hearing Association, 2004). Our goals are to help speech-language pathologists (SLPs) identify and describe partner-based communication strategies for adults with acquired impairment, implement evidence-based approaches for teaching strategies to communication partners, and employ a Personnel Framework (Binger et al., 2012) to clarify partners? roles in acquiring and supporting communication tools for individuals with acquired impairments. We offer specific guidance about AAC techniques and message selection for communication partners involved with chronic, degenerative, and end of life communication. We discuss research and provide examples of communication partner supports for person(s) with aphasia and person(s) with amyotrophic lateral sclerosis who have complex communication needs.

Identifying Measurement Invariant Item Sets in Cross-Cultural Settings Using an Automated Item Selection Procedure

Methodology ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 177-188 ◽  
Author(s):  
Martin Schultze ◽  
Michael Eid
Keyword(s):  
Measurement Invariance ◽  
Optimal Solution ◽  
Selection Procedure ◽  
Cross Cultural ◽  
Item Selection ◽  
Ant System ◽  
Item Quality ◽  
Ant System Algorithm ◽  
Selection For ◽  
Selection Of

Abstract. In the construction of scales intended for the use in cross-cultural studies, the selection of items needs to be guided not only by traditional criteria of item quality, but has to take information about the measurement invariance of the scale into account. We present an approach to automated item selection which depicts the process as a combinatorial optimization problem and aims at finding a scale which fulfils predefined target criteria – such as measurement invariance across cultures. The search for an optimal solution is performed using an adaptation of the [Formula: see text] Ant System algorithm. The approach is illustrated using an application to item selection for a personality scale assuming measurement invariance across multiple countries.

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