The B chromosomes of Locusta migratoria. II. Effects on chiasma frequency

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 118-123 ◽  
Author(s):  
Esther Viseras ◽  
F. Javier Salcedo ◽  
Juan Pedro M. Camacho
Keyword(s):  
Environmental Factors ◽  
Genetic Relationship ◽  
Chiasma Frequency ◽  
Locusta Migratoria ◽  
B Chromosomes ◽  
A Cell ◽  
Genetic And Environmental Factors ◽  
Close Genetic Relationship ◽  
Accessory Chromosomes

The effects of accessory chromosomes of Locusta migratoria have been tested at intra- and inter-individual levels. Intraindividual analysis demonstrated that chiasma frequency of a cell is independent of the number of B-chromosomes that it contains. Interindividual analysis was done using males with a close genetic relationship (brother–brother and father–son) as well as males not showing such relationship. This analysis demonstrated the importance of both genetic and environmental factors in determining chiasma frequency. It was concluded that B chromosomes have no influence on this character.Key words: Locusta, B chromosomes, chiasma frequency.

Meiosis in mammals: recombination, non-disjunction and the environment

2006 ◽  
Vol 34 (4) ◽  
pp. 574-577 ◽  
Author(s):  
P.A. Hunt
Keyword(s):  
Environmental Factors ◽  
Meiotic Recombination ◽  
Maternal Age ◽  
Control Mechanisms ◽  
Human Female ◽  
Meiotic Process ◽  
A Cell ◽  
Males And Females ◽  
Genetic And Environmental Factors ◽  
Combined Data

By comparison with other species, the meiotic process in the human female is extraordinarily error-prone. In addition to the well-known effect of advancing maternal age, recent studies have demonstrated that the number and location of meiotic recombination events influences the likelihood of meiotic non-disjunction in our species. Although this association extends to many other organisms, the factors that influence the number and placement of exchanges within a cell remain poorly understood. Like other aspects of meiosis, the control of recombination is likely to be subject to variation among species. In this review we summarize data from recent studies in mammals; the combined data suggest that both genetic and environmental factors influence recombination in mammals and, importantly, that control mechanisms probably differ between males and females.

The B chromosomes of Locusta migratoria. III. Effects on the activity of nucleolar organizer regions

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 387-394 ◽  
Author(s):  
F. Javier Salcedo ◽  
Esther Viseras ◽  
Juan Pedro M. Camacho
Keyword(s):  
Locusta Migratoria ◽  
Nucleolar Organizer ◽  
Cellular Level ◽  
B Chromosomes ◽  
Nucleolar Organizer Regions ◽  
Type I ◽  
Positive Dependence ◽  
Different Populations ◽  
The Mean ◽  
Genetic And Environmental Factors

Active nucleolus organizing regions (NORs) have been studied in two controlled crosses in the locust Locusta migratoria. NOR activity was detected in all the chromosomes of the standard complement but not in the B chromosomes. On the basis of both the frequency with which they are active and the size of the resulting nucleolus, NORs in this species can be classified in three groups: (i) type I primary NORs that are active in the majority of cells and give rise to large nucleoli; (ii) type II primary NORs that are active in the majority of cells but produce small nucleoli; and (iii) secondary NORS that are active in a minority of cells and yield small nucleoli. The presence of B chromosomes influences the mean activity of some NORs, particularly those giving rise to small nucleoli (groups ii and iii), although different populations yield contradictory results. Our findings indicate that NOR activity in L. migratoria is regulated by genetic and environmental factors, and can be influenced by the presence of B chromosomes which tend to increase the cellular level of NOR activity. An analysis of dependence between NORs for activity demonstrated the existence of a positive dependence between many of the NORs that give rise to small nucleoli. The presence of B chromosomes, however, favoured these enhancement relationships between nonhomologous NORs.Key words: Locusta, B chromosomes, nucleolar organizer.

Reductionist thinking and animal models in neuropsychiatric research

2019 ◽  
Vol 42 ◽  
Author(s):  
Nicole M. Baran
Keyword(s):  
Animal Models ◽  
Mental Disorders ◽  
Environmental Factors ◽  
Neuropsychiatric Disorders ◽  
Model Organisms ◽  
Developmental Genetic ◽  
Term Study ◽  
Genetic And Environmental Factors ◽  
Mechanisms Of Plasticity

AbstractReductionist thinking in neuroscience is manifest in the widespread use of animal models of neuropsychiatric disorders. Broader investigations of diverse behaviors in non-model organisms and longer-term study of the mechanisms of plasticity will yield fundamental insights into the neurobiological, developmental, genetic, and environmental factors contributing to the “massively multifactorial system networks” which go awry in mental disorders.

The Association Between Chronic Disease and Psychological Distress: An Australian Twin Study

2020 ◽  
Vol 23 (6) ◽  
pp. 322-329
Author(s):  
Jessica Tyler ◽  
Janine Lam ◽  
Katrina Scurrah ◽  
Gillian Dite
Keyword(s):  
Psychological Distress ◽  
Chronic Disease ◽  
Environmental Factors ◽  
Twin Study ◽  
Disease Status ◽  
Adult Health ◽  
Linear Regression Models ◽  
Cross Sectional ◽  
Genetic And Environmental Factors ◽  
Distress Scale

AbstractThere is a commonly observed association between chronic disease and psychological distress, but many potential factors could confound this association. This study investigated the association using a powerful twin study design that can control for unmeasured confounders that are shared between twins, including genetic and environmental factors. We used twin-paired cross-sectional data from the Adult Health and Lifestyle Questionnaire collected by Twins Research Australia from 2014 to 2017. Linear regression models fitted using maximum likelihood estimations (MLE) were used to test the association between self-reported chronic disease status and psychological distress, measured by the Kessler Psychological Distress Scale (K6). When comparing between twin pairs, having any chronic disease was associated with a 1.29 increase in K6 (95% CI: 0.91, 1.66; p < .001). When comparing twins within a pair, having any chronic disease was associated with a 0.36 increase in K6 (95% CI: 0.002, 0.71; p = .049). This within-pair estimate is of most interest as comparing twins within a pair naturally controls for shared factors such as genes, age and shared lived experiences. Whereas the between-pair estimate does not. The weaker effect found within pairs tells us that genetic and environmental factors shared between twins confounds the relationship between chronic disease and psychological distress. This suggests that associations found in unrelated samples may show exaggerated estimates.

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