B chromosomes of the grasshopper Heteracris littoralis: meiotic behaviour and endophenotypic effects in both sexes

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 797-801 ◽  
Author(s):  
M. I. Cano ◽  
J. L. Santos
Keyword(s):  
Chiasma Frequency ◽  
Main Type ◽  
Natural Populations ◽  
Meiotic Drive ◽  
B Chromosome ◽  
B Chromosomes ◽  
Female Meiosis ◽  
Accumulation Mechanism ◽  
Cell Variance ◽  
High Level

A main type of a large supernumerary B chromosome has been found in several natural populations of the grasshopper Heteracris littoralis. A study on the geographical distribution of the polymorphism and the meiotic behavior of Bs in both sexes has been carried out with special reference to their effect on two endophenotypic parameters: recombination level and macrospermatid production. Male B bivalents are characterized by a high level of pairing and a strict proximal localization of chiasmata. In the females the B chromosome always divides reductionally at anaphase I indicating the possible existence of an accumulation mechanism based on meiotic drive. There is no effect of Bs on either mean chiasma frequency or between-cell variance in either of the sexes. However, in males a positive correlation between the number of Bs and production of abnormal spermatids (macrospermatids) was found.Key words: B chromosomes, chiasma frequency, female meiosis.

Transmission analysis of mitotically unstable B chromosomes in Locusta migratoria

Genome ◽  
1994 ◽  
Vol 37 (6) ◽  
pp. 1027-1034 ◽  
Author(s):  
M. C. Pardo ◽  
M. D. López-León ◽  
J. Cabrero ◽  
J. P. M. Camacho
Keyword(s):  
Germ Line ◽  
Current Knowledge ◽  
Locusta Migratoria ◽  
Sexual Transmission ◽  
Natural Populations ◽  
Meiotic Drive ◽  
B Chromosome ◽  
B Chromosomes ◽  
The Other ◽  
Mitotic Instability

Seventeen controlled crosses in which the mitotically unstable B chromosome of Locusta migratoria was carried by one parent only have provided evidence that B chromosomes are significantly eliminated during sexual transmission in males, at a mean rate that almost counteracts the premeiotic accumulation derived from mitotic instability during germ line development. On the other hand, B chromosomes are significantly accumulated in females, presumably by their preferential migration to the secondary oocyte during the first meiotic division. These results substantially change the current knowledge about this B chromosome system, because the main B accumulation occurs in females and not in males, as was hitherto thought. Furthermore, this case shows that the maintenance of a single B system in natural populations may be the result of many different forces and mechanisms acting for and against B chromosomes.Key words: locust, Locusta migratoria, B chromosomes, accumulation mechanisms, meiotic drive, B elimination, parthenogenesis.

The dynamics of B chromosomes in populations of the Australian plague locust, Chortoicetes terminifera (Walker)

1984 ◽  
Vol 26 (2) ◽  
pp. 194-208 ◽  
Author(s):  
P. C. Gregg ◽  
G. C. Webb ◽  
M. A. Adena
Keyword(s):  
New South ◽  
Female Parent ◽  
B Chromosome ◽  
Average Frequency ◽  
B Chromosomes ◽  
Banding Patterns ◽  
South Wales ◽  
Random Fashion ◽  
Accumulation Mechanism ◽  
Males And Females

The B chromosomes of Chortoicetes terminifera possess an accumulation mechanism. B chromosomes were transmitted at a rate of 0.766 in one B(♂) × zero B(♀) crosses and 0.477 in zero B(♂) one × B(♀) crosses. In crosses where the female had a B chromosome, there were significant differences in transmission rates between pods, but these were not related to differences in G-banding patterns of the B chromosomes involved. In crosses where either the male or female parent had two B chromosomes the B chromosomes did not segregate perfectly, nor did they segregate in a random fashion. The closest resemblance to the behaviour of normal bivalents occurred when the two B chromosomes were of the same, rather than different, G-banding variants, and when they were present in the male rather than the female parent. B chromosomes occurred at eight localities scattered throughout New South Wales. No locality was found where they were not present. The average frequency of B chromosomes was 14.0% for one-B individuals and 0.8% for two-B individuals. There were no significant differences in B-chromosome frequency between males and females. Of the eight localities, only one had a B-chromosome frequency significantly different from any other locality. This relatively uniformity of B-chromosome distribution is interpreted as a consequence of the migratory nature of C. terminifera. A model was constructed to simulate the dynamics of B chromosomes in locust populations. Three main dynamic patterns were recognized, and these were related to differences in the fitness of one-B and two-B individuals. It was concluded that the B chromosome of C. terminifera is probably parasitic, although the simulation model revealed some difficulties which suggest that caution should be applied to the description of any B chromosome as purely parasitic.Key words: B chromosomes, locust, meiotic drive, G-banding, fitness. Chortoicetes terminifera (Walker).

scholarly journals The B chromosome of Pseudococcus viburni: a selfish chromosome that exploits whole-genome meiotic drive

2021 ◽  
Author(s):  
Isabelle M. Vea ◽  
Andrés G. de la Filia ◽  
Kamil S. Jaron ◽  
Andrew Joseph Mongue ◽  
Fransico J. Ruiz-Ruano ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Expression Data ◽  
Meiotic Drive ◽  
B Chromosome ◽  
Male Meiosis ◽  
B Chromosomes ◽  
Whole Genome ◽  
Expression Data ◽  
Fair Process ◽  
Pseudococcus Viburni

Meiosis, the key process underlying sexual reproduction, is generally a fair process: each chromosome has a 50% chance of being included into each gamete. However in some organisms meiosis has become highly aberrant with some chromosomes having a higher chance of making it into gametes than others. Yet why and how such systems evolve remains unclear. Here we study the unusual reproductive genetics of mealybugs, in which only maternal-origin chromosomes are included into the gametes during male meiosis, while paternally-derived chromosomes degrade. This whole genome meiotic drive occurs in all males and is evolutionarily conserved. However one species - the obscure mealybug Pseudococcus viburni - has a segregating B chromosome that increases in frequency by escaping paternal genome elimination. Here we present whole-genome and gene expression data from laboratory lines with and without B chromosomes. These data allow us to identify B-linked sequences including >70 protein-coding genes as well as a B-specific satellite repeat that makes up a significant proportion of the chromosome. We also used these data to investigate the evolutionary origin of the B chromosome. The few paralogs between the B and the core genome are distributed throughout the genome, showing that it is unlikely that the B originated through a simple duplication of one of the autosomes. We also find that while many of the B-linked genes do not have paralogs within the P.viburni genome, but they do show orthology with genes in other hemipteran insects suggesting that the B might have originated from fission of one of the autosomes, possibly followed by further translocations of individual genes. Finally in order to understand the mechanisms by which the B is able to escape elimination when paternally-derived we generated gene expression data for males and females with and without B chromosomes. We find that at the developmental stage when meiosis is taking place only a small number of B-linked genes show significant expression. Only one gene was significantly over-expressed during male meiosis, which is when the drive occurs: a acetyltransferase involved in H3K56Ac, which has a putative role in meiosis and is therefore a promising candidate for further studies. Together, these results form a promising foundation for studying the mechanisms of meiotic drive in a system that is uniquely suited for this approach.

scholarly journals B Chromosomes in Free-Living Flatworms of the Genus Macrostomum (Platyhelminthes, Macrostomorpha)

2021 ◽  
Vol 22 (24) ◽  
pp. 13617
Author(s):  
Kira S. Zadesenets ◽  
Nikolay B. Rubtsov
Keyword(s):  
Genome Duplication ◽  
Natural Populations ◽  
B Chromosome ◽  
Laboratory Culture ◽  
B Chromosomes ◽  
Free Living ◽  
Transmission Rates ◽  
Supernumerary Chromosomes

B chromosomes (Bs) or supernumerary chromosomes are extra chromosomes in the species karyotype that can vary in its copy number. Bs are widespread in eukaryotes. Usually, the Bs of specimens collected from natural populations are the object of the B chromosome studies. We applied another approach analyzing the Bs in animals maintained under the laboratory conditions as lines and cultures. In this study, three species of the Macrostomum genus that underwent a recent whole-genome duplication (WGD) were involved. In laboratory lines of M. lignano and M. janickei, the frequency of Bs was less than 1%, while in the laboratory culture of M. mirumnovem, it was nearer 30%. Their number in specimens of the culture varied from 1 to 14. Mosaicism on Bs was discovered in parts of these animals. We analyzed the distribution of Bs among the worms of the laboratory cultures during long-term cultivation, the transmission rates of Bs in the progeny obtained from crosses of worms with different numbers of Bs, and from self-fertilized isolated worms. The DNA content of the Bs in M. mirumnovem was analyzed with the chromosomal in situ suppression (CISS) hybridization of microdissected DNA probes derived from A chromosomes (As). Bs mainly consisted of repetitive DNA. The cytogenetic analysis also revealed the divergence and high variation in large metacentric chromosomes (LMs) containing numerous regions enriched for repeats. The possible mechanisms of the appearance and evolution of Bs and LMs in species of the Macrostomum genus were also discussed.

scholarly journals Changing sex for selfish gain: B chromosomes of Lake Malawi cichlid fish

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Frances E. Clark ◽  
Thomas D. Kocher
Keyword(s):  
Linkage Group ◽  
Transmission Rate ◽  
Cichlid Fish ◽  
Meiotic Drive ◽  
B Chromosome ◽  
Lake Malawi ◽  
B Chromosomes ◽  
Normal Complement ◽  
Biased Sex Ratio ◽  
Average Transmission

AbstractB chromosomes are extra, non-essential chromosomes present in addition to the normal complement of A chromosomes. Many species of cichlid fish in Lake Malawi carry a haploid, female-restricted B chromosome. Here we show that this B chromosome exhibits drive, with an average transmission rate of 70%. The offspring of B-transmitting females exhibit a strongly female-biased sex ratio. Genotyping of these offspring reveals the B chromosome carries a female sex determiner that is epistatically dominant to an XY system on linkage group 7. We suggest that this sex determiner evolved to enhance the meiotic drive of the B chromosome. This is some of the first evidence that female meiotic drive can lead to the invasion of new sex chromosomes solely to benefit the driver, and not to compensate for skewed sex ratios.

scholarly journals Genetic Variation in Rates of Nondisjunction: Association of Two Naturally Occurring Polymorphisms in the Chromokinesin nod With Increased Rates of Nondisjunction in Drosophila melanogaster

Genetics ◽  
1999 ◽  
Vol 152 (4) ◽  
pp. 1605-1614 ◽  
Author(s):  
Michael E Zwick ◽  
Jennifer L Salstrom ◽  
Charles H Langley
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Chromosome Segregation ◽  
Natural Populations ◽  
Intermediate Frequency ◽  
Female Meiosis ◽  
X Chromosomes ◽  
Naturally Occurring ◽  
High Level ◽  
Female Specific

Abstract Genetic variation in nondisjunction frequency among X chromosomes from two Drosophila melanogaster natural populations is examined in a sensitized assay. A high level of genetic variation is observed (a range of 0.006-0.241). Two naturally occurring variants at the nod locus, a chromokinesin required for proper achiasmate chromosome segregation, are significantly associated with an increased frequency of nondisjunction. Both of these polymorphisms are found at intermediate frequency in widely distributed natural populations. To account for these observations, we propose a general model incorporating unique opportunities for meiotic drive during female meiosis. The oötid competition model can account for both high mean rates of female-specific nondisjunction in Drosophila and humans as well as the standing genetic variation in this critical fitness character in natural populations.

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 The Behavior of the Maize B Chromosome and Centromere

Genes ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 476 ◽  
Author(s):  
Handong Su ◽  
Yalin Liu ◽  
Yang Liu ◽  
James Birchler ◽  
Fangpu Han
Keyword(s):  
De Novo ◽  
B Chromosome ◽  
B Chromosomes ◽  
Genetic Studies ◽  
Accumulation Mechanism

The maize B chromosome is a non-essential chromosome with an accumulation mechanism. The dispensable nature of the B chromosome facilitates many types of genetic studies in maize. Maize lines with B chromosomes have been widely used in studies of centromere functions. Here, we discuss the maize B chromosome alongside the latest progress of B centromere activities, including centromere misdivision, inactivation, reactivation, and de novo centromere formation. The meiotic features of the B centromere, related to mini-chromosomes and the control of the size of the maize centromere, are also discussed.

GENOTYPES SUPPRESSING MEIOTIC DRIVE OF A B CHROMOSOME IN THE MEALYBUG, PSEUDOCOCCUS OBSCURUS

Genetics ◽  
1985 ◽  
Vol 110 (1) ◽  
pp. 73-92 ◽  
Author(s):  
Uzi Nur ◽  
Betty Lou H Brett
Keyword(s):  
Genetic Factors ◽  
Female Parent ◽  
Meiotic Drive ◽  
B Chromosome ◽  
B Chromosomes ◽  
Isofemale Line ◽  
Maternal Origin ◽  
Isofemale Lines ◽  
Rapid Loss

ABSTRACT The rate of transmission (k) of a supernumerary B chromosome in male mealybugs is shown to depend strongly on the chromosome set of maternal origin. When both parents came from an isofemale line in which the frequency of the B chromosome increased rapidly and stabilized at a mean of more than 4.0 B chromosomes per individual, k was 0.92 and 0.95 in two series of crosses. However, when the female parent came from one of two isofemale lines in which the frequency of the B chromosome decreased from 2.0 to 0 in a few generations, k ranged from 0.53 to 0.78. The high ks, which represent a strong meiotic drive, are apparently responsible for the observed increase in the frequency of the B chromosome in several lines from a mean of about 0.5 to more than 4.0 in about 20 generations. The rapid loss of the B chromosome in other lines is attributed to genetic factors which caused the reduction in the rate of transmission of the B chromosome.

Factors affecting the meiotic pairing behaviour of B chromosomes in the grasshopper Eyprepocnemis plorans

1984 ◽  
Vol 26 (6) ◽  
pp. 664-668 ◽  
Author(s):  
N. Henriques-Gil ◽  
P. Arana ◽  
J. L. Santos
Keyword(s):  
Chiasma Frequency ◽  
Chiasma Formation ◽  
B Chromosome ◽  
B Chromosomes ◽  
Meiotic Pairing ◽  
Eyprepocnemis Plorans ◽  
Factors Affecting ◽  
Chiasma Localization ◽  
A Site ◽  
Pairing Behaviour

A study of the meiotic behaviour of different B-chromosome variants in the acridid grasshopper Eyprepocnemis plorans demonstrates that pairing and chiasma formation in these supernumerary chromosomes depend both on genotypic factors and on the structure of the B chromosomes themselves. Genotypic effects are evidenced by the differences in chiasma frequency which the same B-chromosome combinations show in different individuals. Structural effects can be inferred from the fact that 9 of the 14 known known B variants carry a unique site to which interstitial chiasmata are confined, whereas such a site is lacking in the other five variants.Key words: B chromosomes, C-bands, chiasma frequency, chiasma localization.

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