1
|
Gallardo-Escárate C, Valenzuela-Muñoz V, Nuñez-Acuña G, Valenzuela-Miranda D, Tapia FJ, Yévenes M, Gajardo G, Toro JE, Oyarzún PA, Arriagada G, Novoa B, Figueras A, Roberts S, Gerdol M. Chromosome-Level Genome Assembly of the Blue Mussel Mytilus chilensis Reveals Molecular Signatures Facing the Marine Environment. Genes (Basel) 2023; 14:876. [PMID: 37107634 PMCID: PMC10137854 DOI: 10.3390/genes14040876] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/28/2023] [Accepted: 03/30/2023] [Indexed: 04/29/2023] Open
Abstract
The blue mussel Mytilus chilensis is an endemic and key socioeconomic species inhabiting the southern coast of Chile. This bivalve species supports a booming aquaculture industry, which entirely relies on artificially collected seeds from natural beds that are translocated to diverse physical-chemical ocean farming conditions. Furthermore, mussel production is threatened by a broad range of microorganisms, pollution, and environmental stressors that eventually impact its survival and growth. Herein, understanding the genomic basis of the local adaption is pivotal to developing sustainable shellfish aquaculture. We present a high-quality reference genome of M. chilensis, which is the first chromosome-level genome for a Mytilidae member in South America. The assembled genome size was 1.93 Gb, with a contig N50 of 134 Mb. Through Hi-C proximity ligation, 11,868 contigs were clustered, ordered, and assembled into 14 chromosomes in congruence with the karyological evidence. The M. chilensis genome comprises 34,530 genes and 4795 non-coding RNAs. A total of 57% of the genome contains repetitive sequences with predominancy of LTR-retrotransposons and unknown elements. Comparative genome analysis of M. chilensis and M. coruscus was conducted, revealing genic rearrangements distributed into the whole genome. Notably, transposable Steamer-like elements associated with horizontal transmissible cancer were explored in reference genomes, suggesting putative relationships at the chromosome level in Bivalvia. Genome expression analysis was also conducted, showing putative genomic differences between two ecologically different mussel populations. The evidence suggests that local genome adaptation and physiological plasticity can be analyzed to develop sustainable mussel production. The genome of M. chilensis provides pivotal molecular knowledge for the Mytilus complex.
Collapse
Affiliation(s)
| | | | - Gustavo Nuñez-Acuña
- Center for Aquaculture Research, University of Concepción, Concepción 4070386, Chile
| | | | - Fabian J. Tapia
- Center for Aquaculture Research, University of Concepción, Concepción 4070386, Chile
| | - Marco Yévenes
- Laboratorio de Genética, Acuicultura & Biodiversidad, Departamento de Ciencias Biológicas y Biodiversidad, Universidad de Los Lagos, Osorno 5310230, Chile
| | - Gonzalo Gajardo
- Laboratorio de Genética, Acuicultura & Biodiversidad, Departamento de Ciencias Biológicas y Biodiversidad, Universidad de Los Lagos, Osorno 5310230, Chile
| | - Jorge E. Toro
- Facultad de Ciencias, Instituto de Ciencias Marinas y Limnológicas (ICML), Universidad Austral de Chile, Valdivia 5110566, Chile
| | - Pablo A. Oyarzún
- Centro de Investigación Marina Quintay (CIMARQ), Universidad Andres Bello, Quintay 2340000, Chile
| | - Gloria Arriagada
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad Andrés Bello, Santiago 8370186, Chile
- FONDAP Center for Genome Regulation, Santiago 8370415, Chile
| | - Beatriz Novoa
- Instituto de Investigaciones Marinas (IIM), Consejo Superior de Investigaciones Científicas (CSIC), 36208 Vigo, Spain
| | - Antonio Figueras
- Instituto de Investigaciones Marinas (IIM), Consejo Superior de Investigaciones Científicas (CSIC), 36208 Vigo, Spain
| | - Steven Roberts
- School of Aquatic and Fishery Sciences (SAFS), University of Washington, Seattle, WA 98195, USA
| | - Marco Gerdol
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
| |
Collapse
|
2
|
Molecular cytogenetics in the study of repetitive sequences helping to understand the evolution of heterochromatin in Melipona (Hymenoptera, Meliponini). Genetica 2021; 149:55-62. [PMID: 33449238 DOI: 10.1007/s10709-020-00111-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 11/27/2020] [Indexed: 10/22/2022]
Abstract
The eukaryote genome is enriched by different types of repetitive DNA sequences and is most abundant in heterochromatin regions. Historically, no function has been assigned to these sequences, which makes them the target of studies that have demonstrated their structural and functional importance in the genome. Despite having a constant chromosome number, the genus Melipona has species with wide variation in heterochromatin content, from 8 to 73%, which is an important feature to be investigated regarding its origin and evolution. In the present study, a repetitive DNA sequence of Melipona mondury was isolated by restriction enzyme digestion. This sequence was used to hybridize chromosomes of eight Melipona species that include representatives of the four subgenera and present divergent characteristics in relation to the heterochromatin content. Considering that rDNA localization has shown differences in Melipona, 16 species of this genus were analyzed with 18S rDNA probe. Our data suggest that heterochromatin growth occurred independently in the Michmelia and Melikerria subgenera, considering that the isolated repetitive DNA sequence was shared only by the Michmelia species. Amplification possibly occurred from the centromeric region, causing the displacement of the rDNA sites to the ends of the chromosomes. The repetitive DNA sequence used is a constituent of Michmelia heterochromatin, which that arose from the common ancestor of the species of this subgenus.
Collapse
|
3
|
Al-Saad A, Khatir Z, Al-Maslamani I, Leitão A. Cytogenetic Characterization of Three Arabian Gulf Bivalve Species. MALACOLOGIA 2020. [DOI: 10.4002/040.063.0105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Aysha Al-Saad
- Environmental Science Center (ESC), Qatar University, P. O. Box 2713, Doha, Qatar
| | - Zenaba Khatir
- Environmental Science Center (ESC), Qatar University, P. O. Box 2713, Doha, Qatar
| | - Ibrahim Al-Maslamani
- Environmental Science Center (ESC), Qatar University, P. O. Box 2713, Doha, Qatar
| | - Alexandra Leitão
- Environmental Science Center (ESC), Qatar University, P. O. Box 2713, Doha, Qatar
| |
Collapse
|
4
|
Petkevičiūtė R, Stunžėnas V, Stanevičiūtė G. Comments on species divergence in the genus Sphaerium (Bivalvia) and phylogenetic affinities of Sphaerium nucleus and S. corneum var. mamillanum based on karyotypes and sequences of 16S and ITS1 rDNA. PLoS One 2018; 13:e0191427. [PMID: 29360839 PMCID: PMC5779677 DOI: 10.1371/journal.pone.0191427] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 01/04/2018] [Indexed: 11/28/2022] Open
Abstract
Chromosome, 16S and ITS1 rDNA sequence analyses were used to obtain reliable diagnostic characters and to clarify phylogenetic relationships of sphaeriid bivalves of the genus Sphaerium. The species studied were found to be diploid, with modal number 2n = 28 in S. nucleus and 2n = 30 in S. corneum var. mamillanum. Small, biarmed, C- negative B chromosomes were found in all studied populations of both species. Karyological and molecular markers revealed no differences between S. corneum s. str. and S. corneum var. mamillanum. No intraspecific differences were found in the basic karyotype of S. nucleus. Molecular analyses, however, uncovered three genetically distinct ITS1 lineages: one comprised of samples from Lithuania, Slovakia, and Russia, another from Czech, and a third from Ukraine. Additionally to known 16S haplotype from Ukraine, three new 16S haplotypes of S. nucleus were detected: one in the samples from Lithuania and Russia, one in Slovakian and one in Czech population. In the ITS1 phylogenetic tree, all branches of S. nucleus clustered in one clade. In the 16S phylogenetic tree, however, the haplotype of Czech S. nucleus formed a separate branch, distant from three other haplotypes of S. nucleus. Molecular results indicate that in the context of the Evolutionary Species Concept the S. nucleus morphospecies may represent a complex of separate taxa, however referring on the Biological Species Concept the genetic lineages could represent the intraspecific variability.
Collapse
Affiliation(s)
- Romualda Petkevičiūtė
- P. B. Šivickis Laboratory of Parasitology, Nature Research Centre, Vilnius, Lithuania
| | - Virmantas Stunžėnas
- P. B. Šivickis Laboratory of Parasitology, Nature Research Centre, Vilnius, Lithuania
| | - Gražina Stanevičiūtė
- P. B. Šivickis Laboratory of Parasitology, Nature Research Centre, Vilnius, Lithuania
| |
Collapse
|
5
|
Wang JH, Zheng XD. Cytogenetic studies in three octopods, Octopusminor, Amphioctopusfangsiao, and Cistopuschinensis from the coast of China. COMPARATIVE CYTOGENETICS 2018; 12:373-386. [PMID: 30275929 PMCID: PMC6160780 DOI: 10.3897/compcytogen.v12i3.25462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 08/12/2018] [Indexed: 05/17/2023]
Abstract
To provide markers to identify chromosomes in the genome of octopods, chromosomes of three octopus species were subjected to NOR/C-banding. In addition, we examined their genome size (C value) to submit it to the Animal Genome Size Database. Silver staining revealed that the number of Ag-nucleoli was 2 (Octopusminor (Sasaki, 1920)), 2 (Amphioctopusfangsiao (d'Orbigny, 1839)) and 1 (Cistopuschinensis Zheng et al., 2012), respectively, and the number of Ag-nucleoli visible was the same as that of Ag-NORs on metaphase plates in the same species. In all analyzed metaphases, Ag-NORs were mainly located terminally on the long arms of chromosomes 3 (3rd) of O.minor and on the short arms of chromosomes 4 (4th) of A.fangsiao, whereas only one of the chromosomes 23 (23rd) was found Ag-NORs of C.chinensis. C-bands were localized predominantly in the centromeric regions of chromosomes in the three species, while other conspicuous stable C-bands were observed in terminal regions, including the Ag-NORs. That means these three chromosome pairs (3rd, 4th and 23rd) could be considered species-specific cytogenetic markers. The mean C values of O.minor, A.fangsiao and C.chinensis were 7.81±0.39 pg (0.070 pg per unit length), 8.31±0.18 pg (0.068 pg per unit length) and 5.29±0.10 pg (0.038 pg per unit length), respectively, and results showed that C values of the three species were not proportional to the relative length of the chromosomes. These cytogenetic characteristics will provide more theoretical foundation for further researches on chromosome evolution in octopods.
Collapse
Affiliation(s)
- Jin-hai Wang
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, ChinaOcean University of ChinaQingdaoChina
- Key Laboratory of Mariculture, Ocean University of China, Ministry of Education, ChinaOcean University of ChinaQingdaoChina
| | - Xiao-dong Zheng
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, ChinaOcean University of ChinaQingdaoChina
- Key Laboratory of Mariculture, Ocean University of China, Ministry of Education, ChinaOcean University of ChinaQingdaoChina
| |
Collapse
|
6
|
De Witte B, Devriese L, Bekaert K, Hoffman S, Vandermeersch G, Cooreman K, Robbens J. Quality assessment of the blue mussel (Mytilus edulis): comparison between commercial and wild types. MARINE POLLUTION BULLETIN 2014; 85:146-55. [PMID: 24969855 DOI: 10.1016/j.marpolbul.2014.06.006] [Citation(s) in RCA: 404] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/29/2014] [Accepted: 06/03/2014] [Indexed: 05/18/2023]
Abstract
This study compared species identity, microplastics, chemical and microbial contamination between consumption mussels and wild type mussels, collected at Belgian department stores and Belgian groynes and quaysides, respectively. Species identification based on genetic analysis showed a high number of Mytilus (M.) edulis compared to M. galloprovincialis and M. edulis/galloprovincialis hybrid mussels. The number of total microplastics varied from 2.6 to 5.1 fibres/10 g of mussel. A higher prevalence of orange fibres at quaysides is related to fisheries activities. Chemical contamination of polycyclic aromatic hydrocarbons and polychlorobiphenyls could be related to industrial activities and water turbidity, with maximum concentrations at the quayside of port Zeebrugge. The inverse was noted for Escherichia coli contamination, which was relatively low at Zeebrugge quayside with a total count of 3.9 × 10(2)CFU/100 g tissue, due to limited agricultural effluents. Results of this complementary analysis stress the importance of integrated monitoring and quality assessment.
Collapse
Affiliation(s)
- B De Witte
- Institute of Agricultural and Fisheries Research, Animal Sciences Unit - Aquatic Environment and Quality, Ankerstraat 1, 8400 Ostend, Belgium.
| | - L Devriese
- Institute of Agricultural and Fisheries Research, Animal Sciences Unit - Aquatic Environment and Quality, Ankerstraat 1, 8400 Ostend, Belgium.
| | - K Bekaert
- Institute of Agricultural and Fisheries Research, Animal Sciences Unit - Aquatic Environment and Quality, Ankerstraat 1, 8400 Ostend, Belgium.
| | - S Hoffman
- Institute of Agricultural and Fisheries Research, Animal Sciences Unit - Aquatic Environment and Quality, Ankerstraat 1, 8400 Ostend, Belgium.
| | - G Vandermeersch
- Institute of Agricultural and Fisheries Research, Animal Sciences Unit - Aquatic Environment and Quality, Ankerstraat 1, 8400 Ostend, Belgium.
| | - K Cooreman
- Institute of Agricultural and Fisheries Research, Animal Sciences Unit - Aquatic Environment and Quality, Ankerstraat 1, 8400 Ostend, Belgium.
| | - J Robbens
- Institute of Agricultural and Fisheries Research, Animal Sciences Unit - Aquatic Environment and Quality, Ankerstraat 1, 8400 Ostend, Belgium.
| |
Collapse
|
7
|
Pérez-García C, Morán P, Pasantes JJ. Karyotypic diversification in Mytilus mussels (Bivalvia: Mytilidae) inferred from chromosomal mapping of rRNA and histone gene clusters. BMC Genet 2014; 15:84. [PMID: 25023072 PMCID: PMC4106214 DOI: 10.1186/1471-2156-15-84] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 07/10/2014] [Indexed: 11/17/2022] Open
Abstract
Background Mussels of the genus Mytilus present morphologically similar karyotypes that are presumably conserved. The absence of chromosome painting probes in bivalves makes difficult verifying this hypothesis. In this context, we comparatively mapped ribosomal RNA and histone gene families on the chromosomes of Mytilus edulis, M. galloprovincialis, M. trossulus and M. californianus by fluorescent in situ hybridization (FISH). Results Major rRNA, core and linker histone gene clusters mapped to different chromosome pairs in the four taxa. In contrast, minor rRNA gene clusters showed a different behavior. In all Mytilus two of the 5S rDNA clusters mapped to the same chromosome pair and one of them showed overlapping signals with those corresponding to one of the histone H1 gene clusters. The overlapping signals on mitotic chromosomes became a pattern of alternate 5S rRNA and linker histone gene signals on extended chromatin fibers. Additionally, M. trossulus showed minor and major rDNA clusters on the same chromosome pair. Conclusion The results obtained suggest that at least some of the chromosomes bearing these sequences are orthologous and that chromosomal mapping of rRNA and histone gene clusters could be a good tool to help deciphering some of the many unsolved questions in the systematic classification of Mytilidae.
Collapse
Affiliation(s)
| | | | - Juan J Pasantes
- Dpto, Bioquímica, Xenética e Inmunoloxía, Universidade de Vigo, E-36310 Vigo, Spain.
| |
Collapse
|
8
|
López-Piñón MJ, Insua A, Méndez J. Chromosome Analysis and Mapping of Ribosomal Genes by One- and Two-Color Fluorescent in situ Hybridization in Hinnites distortus (Bivalvia: Pectinidae). J Hered 2004; 96:52-8. [PMID: 15598716 DOI: 10.1093/jhered/esi001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Metaphase chromosomes of the scallop Hinnites distortus were analyzed using Giemsa staining, chromosome measurements, silver staining, one- and two-color fluorescent in situ hybridization (FISH) ribosomal DNA (rDNA) probes, and 4',6-diamidino-2-phenylindole (DAPI) banding compatible with in situ hybridization. The karyotype (2n = 38) consists of three submetacentric-metacentric, one submetacentric, one subtelocentric-submetacentric, and 14 subtelocentric pairs. The 18S-28S rDNA maps at the centromeric level of two subtelocentric pairs, but not more than two nucleolus organizer region (NOR)-bearing chromosomes were transcriptionally active. The 5S rDNA seems to show a conventional tandem arrangement with a repeat unit of about 450 bp and it maps at the pericentromeric region of the long arm of one subtelocentric pair. Two-color FISH demonstrated that 18S-28S rDNA and 5S rDNA are not syntenic. Sequential FISH/Giemsa staining and subsequent chromosome pairing allow us to propose that pairs 9 and 12 carry the 18S-28S rDNA and pair 13 carries the 5S rDNA. All chromosomes are characterized as containing constitutive heterochromatin at the centromeric region. The data provided are the first contribution toward construction of the molecular karyotype of H. distortus and will be useful in assessing evolutionary relationships within scallops.
Collapse
Affiliation(s)
- M J López-Piñón
- Departamento de Biología Celular y Molecular, Universidade da Coruña, A Zapateira s/n, 15071 A Coruña, Spain
| | | | | |
Collapse
|
9
|
Rolan-Alvarez E, Buño I, Gosalvez J. Sex is Determined by Sex Chromosomes in Littorina Saxatilis (Olivi) (Gastropoda, Prosobranchia). Hereditas 2004. [DOI: 10.1111/j.1601-5223.1996.00261.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
10
|
Martínez-Lage A, Rodríguez F, González-Tizón A, Prats E, Cornudella L, Méndez J. Comparative analysis of different satellite DNAs in four Mytilus species. Genome 2002; 45:922-9. [PMID: 12416625 DOI: 10.1139/g02-056] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report the characterization of three satellite DNAs in four species of mussel: Mytilus edulis, Mytilus galloprovincialis, Mytilus trossulus, and Mytilus californianus. The monomers of the Apa I satellite DNAs were 173, 161, and 166 bp long. These satellite monomers were used to construct phylogenetic trees to infer relationships among these species. The topologies obtained clearly indicate that M. californianus is the most divergent species with respect to the other three. Furthermore, localization of satellite DNAs on metaphase chromosomes was performed using fluorescent in situ hybridization (FISH). Fluorescent signals revealed a different organization and distribution of these three satellite DNAs.
Collapse
Affiliation(s)
- A Martínez-Lage
- Dept. Biología Celular y Molecular, Universidade de Coruña, La Coruña, Spain
| | | | | | | | | | | |
Collapse
|
11
|
González-Tizón AM, Martínez-Lage A, Rego I, Ausió J, Méndez J. DNA content, karyotypes, and chromosomal location of 18S-5.8S-28S ribosomal loci in some species of bivalve molluscs from the Pacific Canadian coast. Genome 2000; 43:1065-72. [PMID: 11195339 DOI: 10.1139/g00-089] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The DNA content of 10 species of bivalve molluscs from British Columbia coast was determined by image analysis, and the karyotypes of the horse clam Tressus capax, the bent-nose macoma Macoma nasuta, and the nuttall's mahogany clam Nuttallia nuttallii are described here for the first time. We also have analyzed the location of rDNA loci using a 28S-5.8S-18S probe in four of these species: Mytilus californianus, M. trossulus, Macoma nasuta and N. nuttallii. Results obtained report new data about cytogenetic characteristics of bivalve molluscs.
Collapse
Affiliation(s)
- A M González-Tizón
- Departamento de Biología Celular y Molecular, Universidad de La Coruña, Spain
| | | | | | | | | |
Collapse
|
12
|
Fernández A, García T, Asensio L, Rodríguez MA, González I, Céspedes A, Hernández PE, Martín R. Identification of the clam species Ruditapes decussatus (Grooved carpet shell), Venerupis pullastra (Pullet carpet shell), and Ruditapes philippinarum (Japanese carpet shell)by PCR-RFLP. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2000; 48:3336-3341. [PMID: 10956112 DOI: 10.1021/jf0002185] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
PCR-RFLP analysis has been applied to the identification of three clam species: Ruditapes decussatus (grooved carpet shell), Venerupis pullastra (pullet carpet shell), and Ruditapes philippinarum (Japanese carpet shell). PCR amplification was carried out using a set of primers designed from the DNA nucleotide sequences reported for alpha-actins from humans and various animals. Restriction endonuclease analysis based on sequence data of the PCR products of each clam species revealed the presence of species-specific polymorphic sites for MaeIII and RsaI endonucleases. Electrophoretic analysis of the amplicons digested with MaeIII and RsaI produced species-specific profiles that allowed the genetic identification of the three clam species.
Collapse
Affiliation(s)
- A Fernández
- Departamento de Nutrición y Bromatología III, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Vitturi R, Gianguzza P, Colomba M, Riggio S. Cytogenetic characterization ofBrachidontes pharaonis(Fisher P., 1870): Karyotype, banding and fluorescentin situhybridization (fish) (Mollusca: Bivalvia: Mytilidae). ACTA ACUST UNITED AC 2000. [DOI: 10.1080/00785236.1999.10409430] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
14
|
Insua A, Méndez J. Physical mapping and activity of ribosomal RNA genes in mussel Mytilus galloprovincialis. Hereditas 1998; 128:189-94. [PMID: 9760868 DOI: 10.1111/j.1601-5223.1998.00189.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In bivalve molluscs, NOR analysis was carried out by silver staining, and extensive intra- and interindividual differences in the apparent number of NORs were reported. In this work, we determine the physical mapping of 18S and 28S ribosomal genes of the mussel M. galloprovincialis by fluorescence in situ hybridization (FISH). We also apply silver staining to the same individuals in order to determine if structural changes are involved in the heteromorphism detected by this technique. Our results show that rDNA loci map on the telomeric region of the long arm of two submetacentric-subtelocentric chromosome pairs. In addition to variations in NOR expression, we found some cases of structural variations that affect the number of rDNA loci between individuals and the location of the rDNA locus between the cells of the individual. We suggest that FISH should be applied to other bivalves to assess the variation of rDNA loci and undertake more accurate interspecific comparisons.
Collapse
Affiliation(s)
- A Insua
- Departamento de Biología Celular y Molecular, Universidad de A Coruña, Spain
| | | |
Collapse
|
15
|
Insua A, López-Piñón MJ, Méndez J. Characterization of Aequipecten opercularis (Bivalvia: Pectinidae) chromosomes by different staining techniques and fluorescent in situ hybridization. Genes Genet Syst 1998; 73:193-200. [PMID: 9880917 DOI: 10.1266/ggs.73.193] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The chromosomes of the queen scallop Aequipecten opercularis were studied using conventional Giemsa staining, chromosome measurements, C-banding, silver staining, and fluorescent in situ hybridization (FISH) with 18S-28S rDNA and 5S rDNA probes. The karyotype (2n = 26) consists of large metacentric (pairs 1 and 2), telocentric (pairs 3, 4, 5, 6, 7, 8, and 9), and small metacentric chromosomes (pairs 10, 11, 12, and 13). The C-bands observed can be described as major and minor C-bands which are differentiated according to the intensity of the fluorescence and the frequency of the detection. Major C-bands were found on the long arm of the chromosome pairs 6, 7, 8, and 9 in an intercalary or subterminal position. Minor C-bands were located in the centromeric region in all chromosomes of the complement and also on one arm of pairs 12 and 13 in a terminal position. Silver spots were detected on the telomere of the long arms of one or two chromosomes of pair 7 in every case, although in two individuals up to four additional silver spots were detected. These were located on pairs 8 and 9 in the same position as the C-bands. 18S-28S ribosomal genes were found by FISH on the long arm of chromosome pair 7.5S ribosomal genes were located subterminally on one arm of metacentric pair 1, but two sites were differentiated in the case of elongated chromosomes. The results obtained allow for the identification of at least six different chromosome pairs in A. opercularis and contribute to the construction of an idiogram that is suitable for gene mapping and establishing accurate interspecific comparisons in scallops.
Collapse
Affiliation(s)
- A Insua
- Departamento de Biología Cellular y Molecular, Universidade da Coruña, A Zapateira, Spain
| | | | | |
Collapse
|