A propos de l'article ?The B-chromosomes of Locusta migratoria I. Detection of negative correlation between mean chiasma frequency and the rate of accumulation of the B's; a reanalysis of the available data about the transmission of these B-chromosomes?, par. J. Cabrero, E. Viseras et J. P. M. Camacho

Genetica ◽  
1985 ◽  
Vol 66 (2) ◽  
pp. 151-151
Author(s):  
R. Lespinasse
Keyword(s):  
Negative Correlation ◽  
Chiasma Frequency ◽  
Locusta Migratoria ◽  
B Chromosomes ◽  
Rate Of Accumulation

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.

Microdissection and chromosome painting of X and B chromosomes in Locusta migratoria

2008 ◽  
Vol 17 (1) ◽  
pp. 11-18 ◽  
Author(s):  
María Teruel ◽  
Josefa Cabrero ◽  
Eugenia E. Montiel ◽  
Manuel J. Acosta ◽  
Antonio Sánchez ◽  
...  
Keyword(s):  
Chromosome Painting ◽  
Locusta Migratoria ◽  
B Chromosomes

THE EFFECTS OF SUPERNUMERARY CHROMATIN IN THREE SPECIES OF GRASSHOPPER

1974 ◽  
Vol 16 (2) ◽  
pp. 285-296 ◽  
Author(s):  
Gilbert L. Schroeter ◽  
Godfrey M. Hewitt
Keyword(s):  
Life Cycle ◽  
Chiasma Frequency ◽  
Genetic Material ◽  
B Chromosomes ◽  
Population Variability ◽  
The Other ◽  
Direct Effects ◽  
Apparent Effect ◽  
Other Hand ◽  
The Mean

The chiasma frequencies in males of three species of grasshopper with and without B-chromosomes and supernumerary segments were scored at diplotene. The partially heterochromatic B's found in some individuals of Chimarocephala pacifica pacifica have no effect on chiasma frequencies. On the other hand, heterochromatic supernumerary segments in Oedaleonotus phryneicus males significantly increase the mean chiasma frequencies over individuals without them but not the between-cell variances. In Camnula pellucida neither the mitotically unstable B's nor supernumerary segments have any apparent effect on chiasma.frequencies. The supernumerary elements in Chimarocephala pacifica and Camnula pellucida may, however, produce other effects during the life cycle These and previous observations suggest that polymorphism involving extra genetic material in grasshoppers can result in increased population variability via two different means: (1) by producing variation in chiasma frequency or (2) through direct effects in the individuals possessing it. The importance of such a mechanism for producing variation is discussed.

scholarly journals Population Cytology of the Genus Phaulacridium VI. Seasonal Changes in the Frequency of the B Chromosome in a Population of Ph. vittatum

1977 ◽  
Vol 30 (4) ◽  
pp. 329 ◽  
Author(s):  
M Westerman ◽  
J Dempsey
Keyword(s):  
Seasonal Changes ◽  
Chiasma Frequency ◽  
Sequential Sampling ◽  
Late Summer ◽  
B Chromosome ◽  
B Chromosomes ◽  
Adult Males ◽  
University Campus ◽  
Maximum Value ◽  
Significant Difference

Sequential sampling of adult males from the La Trobe University campus population of Ph. Vittatum has been carried out over two successive years. Within each year there is seen to be a similar change in frequency of males carrying a large, mitotically stable B chromosome. Early in the summer, when adults first appear, the B frequency of the population is low; it then rises to a maximum value in late summer and then declines once more. Possible reasons for this change in B frequency are discussed. Chiasma frequency scores of individuals with and without B chromosomes were also recorded for each sample. It was found that although at anyone time there was no significant difference between individuals with and without B chromosomes, due no doubt to the small numbers sampled, nonetheless the chiasma frequency of the former was always higher than the latter. Since this was the finding for collections over three years, it is concluded that the B chromosomes of Ph. vittatum, like those of other acridids, raise mean cell chiasma frequency.

scholarly journals Mitotic instability of B chromosomes during embryo development in Locusta migratoria

Heredity ◽  
1995 ◽  
Vol 74 (2) ◽  
pp. 164-169 ◽  
Author(s):  
M C Pardo ◽  
M D Lopez-Leon ◽  
E Viseras ◽  
J Cabrero ◽  
J P M Camacho
Keyword(s):  
Embryo Development ◽  
Locusta Migratoria ◽  
B Chromosomes ◽  
Mitotic Instability

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.

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