scholarly journals Molecular analysis of Drosophila melanogaster B chromosomes reveals their origin, composition, and structure

2018 ◽  
Author(s):  
Stacey L. Hanlon ◽  
Danny E. Miller ◽  
Salam Eche ◽  
R. Scott Hawley
Keyword(s):  
Drosophila Melanogaster ◽  
Molecular Analysis ◽  
Model Organism ◽  
B Chromosome ◽  
B Chromosomes ◽  
Individual Species ◽  
Satellite Repeat ◽  
Supernumerary Chromosomes ◽  
Laboratory Stock ◽  
Composition And Structure

ABSTRACTThe number of chromosomes carried by an individual species is one of its defining characteristics. Some species, however, can also carry supernumerary chromosomes referred to as B chromosomes. B chromosomes were recently identified in a laboratory stock of Drosophila melanogaster—an established model organism with a wealth of genetic and genomic resources—enabling us to subject them to extensive molecular analysis. We isolated the B chromosomes by pulsed-field gel electrophoresis and determined their composition through next-generation sequencing. Although these B chromosomes carry no known euchromatic sequence, they are rich in transposable elements and long arrays of short nucleotide repeats, the most abundant being the uncharacterized AAGAT satellite repeat. Fluorescent in-situ hybridization on metaphase chromosome spreads revealed this repeat is located on Chromosome 4, strongly suggesting the origin of the B chromosomes is Chromosome 4. Cytological and quantitative comparisons of signal intensity between Chromosome 4 and the B chromosomes supports the hypothesis that the structure of the B chromosome is an isochromosome. We also report the identification of a new B chromosome variant in a related laboratory stock. This B chromosome has a similar repeat signature as the original but is smaller and much less prevalent. We examined additional stocks with similar genotypes and did not find B chromosomes, but did find these stocks lacked the AAGAT satellite repeat. Our molecular characterization of D. melanogaster B chromosomes is the first step towards understanding how supernumerary chromosomes arise from essential chromosomes and what may be necessary for their stable inheritance.

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 Origin, Composition, and Structure of the Supernumerary B Chromosome of Drosophila melanogaster

Genetics ◽  
2018 ◽  
Vol 210 (4) ◽  
pp. 1197-1212 ◽  
Author(s):  
Stacey L. Hanlon ◽  
Danny E. Miller ◽  
Salam Eche ◽  
R. Scott Hawley
Keyword(s):  
Drosophila Melanogaster ◽  
B Chromosome ◽  
Composition And Structure

scholarly journals Karyological study of cicindelidia trifasciata (coleoptera, cicindelidae) from cuba: evidence of B chromosomes

1999 ◽  
Vol 22 (1) ◽  
pp. 45-48 ◽  
Author(s):  
Sónia J.R. Proença ◽  
M.J. Collares-Pereira ◽  
A.R.M. Serrano
Keyword(s):  
Sex Chromosome ◽  
B Chromosome ◽  
B Chromosomes ◽  
Karyological Study ◽  
Supernumerary Chromosomes ◽  
Sex Chromosome System ◽  
Well Differentiated ◽  
Germinal Tissue

Metaphases from germinal tissue of eight males and seven females of Cicindelidia trifasciata from Cuba were analyzed. The species karyotype does not fit the pattern described for Nearctic cicindelids (2n = 18 + XXY): it has 11 autosome pairs and a sex chromosome system of the X1X2X3Y/ X1X1X2X2 X3X3 type, thus a diploid value of 2n = 26 in males and 2n = 28 in females. The first two autosome pairs were almost twice as large as the remaining chromosomes, and the sex elements were morphologically well differentiated. This population was found to be polymorphic for supernumerary chromosomes at both the intraindividual and interindividual levels. An extra small B chromosome was observed in all metaphases of one male (2n = 27), and every female showed metaphases with one to three small Bs, with a clearly higher frequency of cytotype 2n = 29.

Multiple supernumerary chromosomes in the pseudogamous parthenogenetic flatworm Polycelis nigra: lineage markers or remnants of genetic leakage?

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 850-856 ◽  
Author(s):  
Timothy F. Sharbel ◽  
Leo W. Beukeboom ◽  
Laas P. Pijnacker
Keyword(s):  
Chromosome Doubling ◽  
B Chromosome ◽  
B Chromosomes ◽  
Banding Technique ◽  
Free Living ◽  
Transmission Rates ◽  
Supernumerary Chromosomes ◽  
C Banding ◽  
Male Line ◽  
Lineage Markers

Polycelis nigra is a free-living simultaneous hermaphroditic flatworm that has amphimictic and pseudogamous parthenogenetic biotypes. Sexual individuals are always diploid (2n = 16) and pseudogamous parthenogens are polyploid (usually triploid). Two types of supernumerary chromosomes are found in parthenogens, those resembling autosomes ("A-like") and typical B chromosomes, both of which reach frequencies in populations of close to 100%. Experiments measuring the transmission rates of the B chromosomes indicated that they are potentially inherited via the male line, escaping expulsion by pseudogamous parthenogenesis. This study used the C-banding technique to demonstrate (i) that there is a single morphologically distinct B chromosome (B1) and (ii) that there are two "A-like" chromosomes that can be considered B chromosomes (B2 and B3) and which are not simple polysomics of one of the eight autosomes. As there is no genetic exchange between pseudogamous parthenogenetic lineages, two different individuals carrying a similar B morph must either have received it through common ancestry (a lineage marker) or have acquired it horizontally from another parthenogenetic lineage (leakage). C-banding further revealed intra-individual heteromorphy for band regions on chromosomes 5 and 8. This supports the karyotypic observation that oogenesis is preceded by premeiotic chromosome doubling followed by pairing of replicate homologues.Key words: B chromosome, C-banding, heterochromatin, heteromorphy, pseudogamous parthenogenesis.

scholarly journals B Chromosomes in the Drosophila Genus

Genes ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 470 ◽  
Author(s):  
Stacey Hanlon ◽  
R. Hawley
Keyword(s):  
Drosophila Melanogaster ◽  
Next Generation Sequencing ◽  
Current Knowledge ◽  
Genomic Analysis ◽  
B Chromosome ◽  
B Chromosomes ◽  
Next Generation ◽  
Satellite Repeats ◽  
Genomic Tools ◽  
Generation Sequencing

Our current knowledge of B chromosome biology has been augmented by an increase in the number and diversity of species observed to carry B chromosomes as well as the use of next-generation sequencing for B chromosome genomic analysis. Within the genus Drosophila, B chromosomes have been observed in a handful of species, but recently they were discovered in a single laboratory stock of Drosophila melanogaster. In this paper, we review the B chromosomes that have been identified within the Drosophila genus and pay special attention to those recently found in D. melanogaster. These newly-discovered B chromosomes have centromeres, telomeres, and a number of simple satellite repeats. They also appear to be entirely heterochromatic since next-generation sequencing of isolated B chromosomes did not detect sequences associated with known genic regions. We also summarize what effects the B chromosomes have been found to have on the A chromosomes. Lastly, we highlight some of the outstanding questions regarding B chromosome biology and discuss how studying B chromosomes in Drosophila melanogaster, which is a versatile model system with a wealth of genetic and genomic tools, may advance our understanding of the B chromosome’s unique biology.

B Chromosome Diversity and Repetitive Sequence Distribution in an Isolated Population of Akodon montensis (Rodentia, Sigmodontinae)

2018 ◽  
Vol 154 (2) ◽  
pp. 79-85
Author(s):  
Amanda A. Soares ◽  
Jonathan P. Castro ◽  
Pedro Balieiro ◽  
Sidnei Dornelles ◽  
Tiago M. Degrandi ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Repetitive Sequences ◽  
5S Rdna ◽  
B Chromosome ◽  
B Chromosomes ◽  
Telomeric Sequences ◽  
Supernumerary Chromosomes ◽  
Dna Libraries ◽  
Eukaryotic Species ◽  
Size And Morphology

B chromosomes are supernumerary chromosomes found in the karyotypes of approximately 15% of all eukaryotic species. They present parasitic behavior and do not follow the standard Mendelian pattern of inheritance, resulting in an imbalance in gametogenesis. The evolutionary dynamics of B chromosomes is still unknown for many species, but studies indicate that the accumulation of repetitive sequences plays an important role in the differentiation of these elements. We analyzed morphology, frequency, and possible homologies amongst different B chromosomes found in an isolated Akodon montensis population in southern Brazil. Repetitive sequences (18S, 5S rDNA and telomeric sequences) were used to test for their accumulation on the supernumerary chromosomes and describe their localization in the species. The results indicate 4 different B chromosome morphotypes, and DNA libraries were generated for 3 of them. 18S rDNA was labelled polymorphically, except in the B chromosomes, whereas the 5S rDNA was located exclusively in an interstitial position on the long arm of chromosome 5. Chromosome painting with the B probes based on FISH revealed a homologous composition for all B chromosome morphotypes and no homology with the chromosomes in the A complement. B chromosomes found in this population may have a common origin and subsequently diversified in size and morphology.

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 Differential Expression of Genes Related to Sexual Determination Can Modify the Reproductive Cycle of Astyanax scabripinnis (Characiformes: Characidae) in B Chromosome Carrier Individuals

Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 909 ◽  
Author(s):  
Jonathan Pena Castro ◽  
Ricardo Shohei Hattori ◽  
Túlio Teruo Yoshinaga ◽  
Duílio Mazzoni Zerbinato de Andrade Silva ◽  
Francisco J. Ruiz-Ruano ◽  
...  
Keyword(s):  
Differential Expression ◽  
Reproductive Cycle ◽  
Model Organism ◽  
B Chromosome ◽  
B Chromosomes ◽  
Astyanax Scabripinnis ◽  
Expression Of Genes ◽  
Sexual Determination ◽  
The Difference ◽  
Differential Expression Of Genes

The species complex Astyanax scabripinnis is one of the most studied with respect to origin, distribution, and frequency of B chromosomes, and is considered a model organism for evolutionary studies. Research using population inferences about the occurrence and frequency of the B chromosome shows seasonal variation between sexes, which is associated with the presence of this supernumerary element. We hypothesized that the B chromosome could influence the sex ratio of these animals. Based on this assumption, the present work aimed to investigate if differences exist among levels of gene expression with qRT-PCR of the amh (associated with testicular differentiation) and foxl2a (associated with ovarian differentiation) genes between B-carrier and non-B-carrier individuals. The results showed that for the amh gene, the difference in expression between animals with B chromosomes was not accentuated compared to that in animals without this chromosome. Expression of foxl2a in B-carrier females, however, was reduced by 73.56% compared to females that lacked the B chromosome. Males had no difference in expression of the amh and foxl2a genes between carriers and non-carriers of the B chromosome. Results indicate that the presence of B chromosomes is correlated with the differential expression of sex-associated genes. An analysis of these results integrated with data from other studies on the reproductive cycle in the same species reveals that this difference in expression may be expanding the reproductive cycle of the species.

scholarly journals Evolution of Plant B Chromosome Enriched Sequences

2018 ◽  
Author(s):  
André Marques ◽  
Sonja Klemme ◽  
Andreas Houben
Keyword(s):  
Repetitive Sequences ◽  
B Chromosome ◽  
B Chromosomes ◽  
Supernumerary Chromosomes ◽  
Formation And Evolution ◽  
Chromosome Formation ◽  
The Impact ◽  
Normal Standard ◽  
Shed Light

B chromosomes are supernumerary chromosomes which are found in addition to the normal standard chromosomes (A chromosomes). B chromosomes are well known to accumulate several types of repeats. Although the evolution of B chromosomes has been subject of numerous studies, the mechanisms of accumulation and evolution of repetitive sequences is not fully understood. Recently, new genomic approaches have shed light on the origin and accumulation of different classes of repetitive sequences in the process of B chromosome formation and evolution. Here we discuss the impact of repetitive sequences accumulation on the evolution of plant B chromosomes.

Sign in / Sign up

Export Citation Format

Share Document