scholarly journals Transmission rate variation among three B chromosome variants in the fish Prochilodus lineatus (Characiformes, Prochilodontidae)

2013 ◽  
Vol 85 (4) ◽  
pp. 1371-1377 ◽  
Author(s):  
MANOLO PENITENTE ◽  
TATIANA A. VOLTOLIN ◽  
JOSE A. SENHORINI ◽  
JEHUD BORTOLOZZI ◽  
FAUSTO FORESTI ◽  
...  
Keyword(s):  
Transmission Rate ◽  
B Chromosome ◽  
B Chromosomes ◽  
Rate Variation ◽  
Parental Line ◽  
Prochilodus Lineatus ◽  
Extinction Process ◽  
Cytogenetic Studies ◽  
Acrocentric Chromosomes ◽  
Interesting System

Cytogenetic studies were developed in Prochilodus lineatus (Valenciennes 1836), describing an interesting system of small supernumerary chromosomes. The purpose of this work is to study the frequency and morphology of B chromosomes in individuals from the parental line and the inheritance patterns of these elements in individuals obtained from controlled crosses in the species P. lineatus. The transmission rate of B chromosomes revealed a kB=0.388 for the acrocentric type, a kB=0.507 for the metacentric type and a kB=0.526 for the submetacentric type. The obtained results raise hypothesis that B-acrocentric chromosomes are involved in an extinction process in this species, while the metacentric and submetacentric supernumerary elements comprises a neutral mechanism and follows a Mendelian transmission rate.

scholarly journals Transmission Behavior of B Chromosomes in Prochilodus lineatus (Characiformes, Prochilodontidae)

2015 ◽  
Vol 147 (2-3) ◽  
pp. 179-185
Author(s):  
Manolo Penitente ◽  
Sandro N. Daniel ◽  
José A. Senhorini ◽  
Fausto Foresti ◽  
Fábio Porto-Foresti
Keyword(s):  
Distribution Pattern ◽  
B Chromosome ◽  
B Chromosomes ◽  
Prochilodus Lineatus ◽  
Supernumerary Chromosomes ◽  
Transmission Pattern ◽  
Extinction Process ◽  
Controlled Crosses

The population of Prochilodus lineatus found in the Mogi-Guaçu River is karyotypically polymorphic, carrying acrocentric, metacentric, and submetacentric B chromosomes. The analysis of each B chromosome frequency in this species revealed a variation in the distribution pattern, with the metacentric type having the highest frequency (73.30%), followed by submetacentric (25.22%) and acrocentric B chromosomes (1.48%). The transmission pattern of the supernumerary chromosomes was identified by controlled crosses, and it was shown that the acro- and submetacentric B chromosomes have a transmission pattern below the Mendelian rate (kB = 0.333 and kB = 0.385, respectively), but the metacentric variant has a cumulative transmission pattern (kB = 0.587). These results indicate that the acro- and submetacentric B chromosomes are undergoing an extinction process, while the metacentric B chromosomes appear to be accumulating in frequency with each generation.

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 MAINTENANCE OF A "PARASITIC" B CHROMOSOME IN THE GRASSHOPPER MELANOPLUS FEMUR-RUBRUM

Genetics ◽  
1977 ◽  
Vol 87 (3) ◽  
pp. 499-512
Author(s):  
Uzi Nur
Keyword(s):  
New York ◽  
Transmission Rate ◽  
B Chromosome ◽  
B Chromosomes ◽  
High Rate ◽  
Adult Males ◽  
High Transmission ◽  
In The Wild ◽  
Males And Females ◽  
The Mean

ABSTRACT About 10-15% of the males and females of the grasshopper Melanoplus femur-rubrum collected near Rochester, New York, possessed a supernumerary B chromosome. The frequency of the B chromosome remained fairly constant during the years 1971-1974. The B chromosome was shown previously to be transmitted at a rate of about 0.5 and 0.8 by 1B males and females, respectively. This study was designed to determine the forces preventing the B chromosome from increasing in frequency due to the high rate of transmission by the females. Eighty inseminated females collected in the wild were analyzed cytologically together with their embryos (10-20 per female). Ten of the 80 females had a B chromosome, and they transmitted it at a rate of about 0.75. Among the 983 embryos analyzed, 0.141 had one B, 0.007 had two, and the mean number of B chromosomes per embryo was 0.155. The frequency of the B chromosome in the sperm pool (0.061) was consistent with a 0.5 rate of transmission. Individuals with two B chromosomes apparently have low viability, because about six were expected, but none was found among 851 adult males and females examined. The data suggest that the viability of the 1B individuals was only about 0.86 that of the OB individuals. There was no evidence that the B chromosome increased the fecundity of either the 1B males or females. It was concluded, therefore, that the B chromosome reduced the fitness of all the individuals carrying it and was thus "parasitic," and that it was maintained in the population only because of its high transmission rate. The maintenance of other B chromosomes with high transmission rates is reviewed.

scholarly journals Repetitive DNA landscape in essential A and supernumerary B chromosomes of Festuca pratensis Huds

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Rahman Ebrahimzadegan ◽  
Andreas Houben ◽  
Ghader Mirzaghaderi
Keyword(s):  
Repetitive Sequences ◽  
Nuclear Genome ◽  
B Chromosome ◽  
B Chromosomes ◽  
Festuca Pratensis ◽  
Ltr Retrotransposons ◽  
Chromosome Identification ◽  
Satellite Repeats ◽  
Low Pass ◽  
Illumina Sequence

AbstractHere, we characterized the basic properties of repetitive sequences in essential A and supernumerary B chromosomes of Festuca pratensis Huds. This was performed by comparative analysis of low-pass Illumina sequence reads of B chromosome lacking (−B) and B chromosome containing (+B) individuals of F. pratensis. 61% of the nuclear genome is composed of repetitive sequences. 43.1% of the genome are transposons of which DNA transposons and retrotransposons made up 2.3% and 40.8%, respectively. LTR retrotransposons are the most abundant mobile elements and contribute to 40.7% of the genome and divided into Ty3-gypsy and Ty1-copia super families with 32.97% and 7.78% of the genome, respectively. Eighteen different satellite repeats were identified making up 3.9% of the genome. Five satellite repeats were used as cytological markers for chromosome identification and genome analysis in the genus Festuca. Four satellite repeats were identified on B chromosomes among which Fp-Sat48 and Fp-Sat253 were specific to the B chromosome of F. pratensis.

scholarly journals Spatial organization of fibroblast and spermatocyte nuclei with different B-chromosome content in Korean field mouse, Apodemus peninsulae (Rodentia, Muridae)

Genome ◽  
2017 ◽  
Vol 60 (10) ◽  
pp. 815-824 ◽  
Author(s):  
Tatyana V. Karamysheva ◽  
Anna A. Torgasheva ◽  
Yaroslav R. Yefremov ◽  
Anton G. Bogomolov ◽  
Thomas Liehr ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Spatial Organization ◽  
Constitutive Heterochromatin ◽  
B Chromosome ◽  
B Chromosomes ◽  
Laser Scanning Microscopy ◽  
Field Mouse ◽  
Apodemus Peninsulae ◽  
Basic Set ◽  
Korean Field Mouse

Korean field mouse (Apodemus peninsulae) shows a wide variation in the number of B chromosomes composed of constitutive heterochromatin. For this reason, it provides a good model to study the influence of the number of centromeres and amount of heterochromatin on spatial organization of interphase nuclei. We analyzed the three-dimensional organization of fibroblast and spermatocyte nuclei of the field mice carrying a different number of B chromosomes using laser scanning microscopy and 3D fluorescence in situ hybridization. We detected a co-localization of the B chromosomes with constitutive heterochromatin of the chromosomes of the basic set. We showed a non-random distribution of B chromosomes in the spermatocyte nuclei. Unpaired B chromosomes showed a tendency to occur in the compartment formed by the unpaired part of the XY bivalent.

scholarly journals B Chromosomes in Populations of Mammals Revisited

Genes ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 487 ◽  
Author(s):  
Mladen Vujošević ◽  
Marija Rajičić ◽  
Jelena Blagojević
Keyword(s):  
Mammalian Species ◽  
B Chromosome ◽  
Molecular Techniques ◽  
B Chromosomes ◽  
General View ◽  
Protein Coding ◽  
Host Parasite Interactions ◽  
Quantitative Characteristics ◽  
Host Parasite

The study of B chromosomes (Bs) started more than a century ago, while their presence in mammals dates since 1965. As the past two decades have seen huge progress in application of molecular techniques, we decided to throw a glance on new data on Bs in mammals and to review them. We listed 85 mammals with Bs that make 1.94% of karyotypically studied species. Contrary to general view, a typical B chromosome in mammals appears both as sub- or metacentric that is the same size as small chromosomes of standard complement. Both karyotypically stable and unstable species possess Bs. The presence of Bs in certain species influences the cell division, the degree of recombination, the development, a number of quantitative characteristics, the host-parasite interactions and their behaviour. There is at least some data on molecular structure of Bs recorded in nearly a quarter of species. Nevertheless, a more detailed molecular composition of Bs presently known for six mammalian species, confirms the presence of protein coding genes, and the transcriptional activity for some of them. Therefore, the idea that Bs are inert is outdated, but the role of Bs is yet to be determined. The maintenance of Bs is obviously not the same for all species, so the current models must be adapted while bearing in mind that Bs are not inactive as it was once thought.

B-chromosome frequency stability in Prochilodus lineatus (Characiformes, Prochilodontidae)

Genetica ◽  
2009 ◽  
Vol 138 (3) ◽  
pp. 281-284 ◽  
Author(s):  
Tatiana Aparecida Voltolin ◽  
José Augusto Senhorini ◽  
Claudio Oliveira ◽  
Fausto Foresti ◽  
Jehud Bortolozzi ◽  
...  
Keyword(s):  
B Chromosome ◽  
Frequency Stability ◽  
Prochilodus Lineatus

scholarly journals Potential impact of seasonal forcing on a SARS-CoV-2 pandemic

2020 ◽  
Author(s):  
Richard A. Neher ◽  
Robert Dyrdak ◽  
Valentin Druelle ◽  
Emma B. Hodcroft ◽  
Jan Albert
Keyword(s):  
Seasonal Variation ◽  
Infection Control ◽  
Transmission Rate ◽  
Health Care Systems ◽  
Control Measures ◽  
Rate Variation ◽  
Small Peak ◽  
Infection Control Measures ◽  
Care Systems ◽  
Novel Coronavirus

A novel coronavirus (SARS-CoV-2) first detected in Wuhan, China, has spread rapidly since December 2019, causing more than 80,000 confirmed infections and 2,700 fatalities (as of Feb 27, 2020). Imported cases and transmission clusters of various sizes have been reported globally suggesting a pandemic is likely.Here, we explore how seasonal variation in transmissibility could modulate a SARS-CoV-2 pandemic. Data from routine diagnostics show a strong and consistent seasonal variation of the four endemic coronaviruses (229E, HKU1, NL63, OC43) and we parameterize our model for SARS-CoV-2 using these data. The model allows for many subpopulations of different size with variable parameters. Simulations of different scenarios show that plausible parameters result in a small peak in early 2020 in temperate regions of the Northern Hemisphere and a larger peak in winter 2020/2021. Variation in transmission and migration rates can result in substantial variation in prevalence between regions.While the uncertainty in parameters is large, the scenarios we explore show that transient reductions in the incidence rate might be due to a combination of seasonal variation and infection control efforts but do not necessarily mean the epidemic is contained. Seasonal forcing on SARS-CoV-2 should thus be taken into account in the further monitoring of the global transmission. The likely aggregated effect of seasonal variation, infection control measures, and transmission rate variation is a prolonged pandemic wave with lower prevalence at any given time, thereby providing a window of opportunity for better preparation of health care systems.

Identification of a family of repeated sequences on the rye B chromosome

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 908-913 ◽  
Author(s):  
Michael J. Sandery ◽  
John W. Forster ◽  
Richard Blunden ◽  
R. Neil Jones
Keyword(s):  
Secale Cereale ◽  
Direct Evidence ◽  
B Chromosome ◽  
Repeat Sequence ◽  
B Chromosomes ◽  
Repeated Sequences ◽  
Significant Heterogeneity ◽  
Origin And Evolution ◽  
The Family

A novel family of highly repeated sequences on the B chromosome of rye (Secale cereale) has been identified. The D1100 family has not been detected on the rye A chromosomes and shows little or no homology to any previously described repeat sequence in rye. In addition, different rye species, and different B chromosomes within the same species, show significant heterogeneity in the arrangement of the D1100 sequences. An EcoRI clone of a member of the family has been obtained. These results provide direct evidence for the organisation and nature of the B-chromosome DNA in rye, and they are discussed in relation to the origin and evolution of rye B chromosomes.Key words: B chromosome, Secale cereale, repeated sequences.

MOSAICISM OF AN ABNORMALLY LONG B CHROMOSOME IN A BOY WITH PHYSICAL AND MENTAL RETARDATION

PEDIATRICS ◽  
1967 ◽  
Vol 39 (1) ◽  
pp. 68-74
Author(s):  
Lillian Y. F. Hsu ◽  
Iris Nemhauser ◽  
Hilda K. Bettmann ◽  
Edna H. Sobel
Keyword(s):  
Mental Retardation ◽  
Short Stature ◽  
Cell Line ◽  
Normal Cell ◽  
B Chromosome ◽  
B Chromosomes ◽  
Normal Cell Line

An 11-year-old boy with short stature, mental retardation, low-set ears, simian creases, unusual dermatoglyphic patterns, and bilateral dysplastic mid-phalanges of the fifth fingers was found to have mosaicism in both leukocyte and fibroblast (skin) cultures. The normal cell-line predominated and the second cell-line contained an abnormally long chromosome B. The autoradiographic studies suggest that the abnormally long chromosome may involve a No. 5 which contains a translocated on inserted segment of an unknown donor autosome. The possible mechanism for the occurrence of this abnormality is discussed. Nine other instances of abnormally long B chromosomes (with lengthened long arm due to translocation) are reviewed and compared.

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