Salmo trutta fario L. 1758, presented a chromosome number 2n = 80 and a fundamental number NF = 100. The haploid chromosome set consists of seven metacentric chromosomes, three submetacentric, one subtelocentric and 29 telocentrics. The Ag-NOR are located at conserved position in the short arm of pair 11 (st), with the presence of additional NOR on the short arm of pair 9 (sm) which is rare in others taxa previously studied.Salmo truttafario L. 1758, presenta un número cromosómico 2n=80 y un número fundamental NF=100. El juego cromosómico haploide está constituido por siete cromosomas metacéntricos, tres submetacéntricos, un subtelocéntrico y 29 telocéntricos. Los Ag-NOR se localizan en posición conservada en el brazo corto del par 11 (st), con la existencia de NOR adicionales en el brazo corto del par 9 (sm) el que es poco frecuente en otros taxa previamente estudiados

Capetillo Arcos, J.

Jara Seguel, Pedro

Lam, N.

Northland Leppe, Irma

Repositorio Digital Académico (Univ. Catolica Temuco)

45CHROMOSOMES AND Ag-NOR LOCATION IN FLUVIATE POPULATIONSOF SALMO TRUTTA FARIO  L. 1758  (SALMONIFORMES: SALMONIDAE)FROM ATACAMA DESERT, CHILECROMOSOMAS Y LOCALIZACION DE Ag-NOR EN POBLACIONESFLUVIALES DE SALMO TRUTTA FARIO L. 1758 (SALMONIFORMES:SALMONIDAE) DEL DESIERTO DE ATACAMA, CHILEIrma Northland-Leppe1*, Natalia Lam2 , Pedro Jara-Seguel3 & †Juana Capetillo-Arcos11 Departamento Biomédico, Facultad de Ciencias de la Salud, Universidad de Antofagasta,Casilla 170, Antofagasta-Chile. e-mail: inorthland@yahoo.com2 Programa de Genética Humana, Facultad de Medicina, Universidad de Chile, Casilla 70061, Santiago-Chile.3 Escuela de Ciencias Ambientales, Facultad de Recursos Naturales, Universidad Católica de Temuco,Casilla 15-D, Temuco-Chile.ABSTRACTSalmo trutta fario L. 1758, presented a chromosome number 2n = 80 and a fundamental number NF = 100. The haploidchromosome set consists of seven metacentric chromosomes, three submetacentric, one subtelocentric and 29 telocentrics.The Ag-NOR are located at conserved position in the short arm of pair 11 (st), with the presence of additional NOR onthe short arm of pair 9 (sm) which is rare in others taxa previously studied.KEYWORDS : Salmo trutta fario, Chromosomes, Atacama region, Chile.RESUMENSalmo trutta fario L. 1758, presenta un número cromosómico 2n=80 y un número fundamental NF=100. El juegocromosómico haploide está constituido por siete cromosomas metacéntricos, tres submetacéntricos, un subtelocéntricoy 29 telocéntricos. Los Ag-NOR se localizan en posición conservada en el brazo corto del par 11 (st), con la existenciade NOR adicionales en el brazo corto del par 9 (sm) el que es poco frecuente en otros taxa previamente estudiados.PALABRAS CLAVE: Salmo trutta fario, Cromosomas, Región  Atacama, Chile.Chromosomal studies carried out on Salmonidaehave constituted an important step to investigationson genetic variation, phylogeny, taxonomy andevolution, as well as to the analysis of the structure,dynamic and diversity of their genomes. At present,the number of contributions on chromosomes forSalmonidae overtake one-hundred publications, thusconstituting a robust framework utile forbiosystematics studies and for genetic manipulation(Hartley & Horne 1984, Hartley 1987, Phillips &Ráb 2001, Hulata 2001). In the case of Salmo truttaL. 1758 an ubiquitous members of the family,numerous investigations on chromosome number,karyotype morphology, Ag-NOR bearing, restrictionenzymes, C-banding and CMA3 fluorescence havebeen documented, although all the studies have beencarried out in north hemisphere taxa includingnatural populations and hatchery stocks (Nygren etal. 1971, Capanna et al. 1973, Zenzes & Voiculescu1975, Raicu & Taisescu 1977, Mayr et al. 1986,Sánchez et al. 1990, Sánchez et al. 1991, Martínezet al. 1991, Karakousis et al. 1992, Woznicki &Luczynski 1997, Woznicki et al. 2000, Reza et al.2006). It is remarkable that S. trutta shows a broadrange of variation in chromosome number,fundamental number (2n = 78-84, NF= 98-104) andGayana 73(1): 45-48, 2009 ISSN 0717-652X46Gayana 73(1), 2009Ag-NOR location among their subspecies  (Zenzes& Voiculescu 1975, Hartley & Horne 1984, Mayret al. 1986, Castro et al. 2001, Reza et al. 2006),which can be attributable to its considerablevariability in ecological and geographical patterns(Martínez et al. 1991). Within the species, S. truttafario is a subspecies introduced in Chile from early1,900 within a geographical range from 36°S to 56°S(Soto et al. 2006), although on latter years hascolonized freshwater bodies to the north with theexistence of marginal populations in rivers of theAtacama Desert. Preliminary chromosome resultsfor Chilean populations of Salmo trutta fario thatinhabit in the central zone with humid climates havebeen communicated at zoological meetings (Iturraet al. 1986), but nothing is known for marginalpopulations that inhabit in fluviatile environmentsin northern Chile.In this study the chromosome complements andAg-NOR location for two populations of  Salmotrutta  fario that inhabit in rivers of the AtacamaDesert are shown for the first time.The specimens were collected in the Loa andSalado rivers near to Chiu Chiu locality (22°20´S;68°39´W). In the laboratory, the fishes were injectedwith colchicine 0.5% (p/v) for 12 – 16 hours. Laterthe gills were excised and treated following theprotocol described by Bogart (1973) with somemodifications (the gill were washed in distilledwater, fixed in 50% v/v glacial acetic acid and theepithelial cells were scraped on the slides).Metaphases were obtained by squashing of epithelialgill-cells using a phase-contrast microscope. Tostudy the standard karyotype the chromosomes werestained using 4% Giemsa in phosphate buffer at pH7.2. Metaphases were photographed with an opticalphotomicroscope Leitz Laborlux 12. Thechromosomes were measured in photographicenlargements and standardized as a percentage ofthe total haploid set length. The karyogram wasmade up with the chromosomes paired on the basisof shape and size, and ordered following theFIGURE 1. Kariogram of Salmo trutta fario, 2n=80 (FN=100).  The inserted square shows the Ag-NOR location in theshort arms of the chromosome pairs 9 and 11. The chromosomes of the haploid set are: seven metacentric (1 to 7), threesubmetacentric (8 to10), one subtelocentric (11) and 29 telocentric (12 to 40). Bar = 5 µm.FIGURA 1. Cariograma de Salmo trutta fario, 2n=80 (FN=100). El cuadro inserto muestra la localización de los Ag-NORen los brazos cortos de los pares cromosómicos 9 y 11. Los cromosomas del juego haploide son: siete metacéntricos (1al 17), tres submetacéntricos (8 al 10), un subtelocéntrico (11) y 29 telocéntricos (12 al 40). Barra =  5 µm.47categories proposed by Levan et al. (1964). To studyNOR location in the chromosomes, the silver nitratestaining method was performed according to thetechnique described by Sánchez-Rufas et al. (1982).The chromosome number for both Chilean fluviatilepopulations of S. trutta fario from Atacama Desertwas 2n=80 (Fig. 1) showing similitude with thosenumber previously documented for Romania andPoland populations (Raicu & Taisescu 1977,Woznicki et al. 1997), as well as for other subspeciesfrom north hemisphere (Karacousis et al. 1992, Rezaet al. 2006). Nevertheless, some variations havebeen observed regarding to fundamental numbersand karyotype formulas among the subspecies (Rezaet al. 2006). Several authors have discussed suchvariations in fundamental number pointing outaneuploidization mechanisms or technical artefacts(Capanna et al. 1973, Raicú & Taisscu 1977),whereas other have justify the real existence ofpolymorphism based in the occurrence ofRobertsonian traslocations (Zenzes & Voiculescu1975, Hartley & Horne 1984) or modifications inshort arm lengths of those NOR chromosomes carrier(Martínez et al. 1991). For Chilean populations of S.trutta fario the fundamental number was FN=100,being within the range described for north hemispherepopulations whose fundamental numbersdocumented are 100, 102 and 104 (Raicu & Taisescu1977, Woznicki et al. 1997, Woznicki et al. 2000).On the other hand, the haploid karyotype formulafor Chilean S. trutta fario was 7m + 3 sm + 1st + 29t,showing resemblance with Poland populations whoseformula was 7m + 4sm + 29 st/t. It is remarkable thatall the complements described within S. trutta areasymmetric with most of 70% of the chromosomeswithin the subtelocentric and/or telocentric categories,tendency broadly described in Salmonidae (Phillips& Ráb 2001).Large Ag-NOR were observed on the short armsof both homologous of the chromosome pairs 9 (sm)and 11 (st) in the two populations of S. trutta fariostudied in this work (Fig.1, see inserted square).Such signals were coincident with one and twonucleolus observed in interphase nuclei (data notshown). Previous studies in S. trutta have showedthat the NORs are located in both homologous ofthe chromosome pair 11 and in one homologous ofthe pair 14, although variation in NOR size and inthe number of active NORs per genome has beenreported ((Mayr et al. 1986, Martínez et al. 1991).Interesting polymorphism with 13 active and stabletelomeric NORs has been described for Spainpopulations of S. trutta, thus suggesting thattransposition phenomenon responsible for NORjumping could be still active (Castro et al. 2001).In the present work a relative conservationism inchromosome number and karyotype morphologywas demonstrated for populations of S. trutta fariofrom northern Chile, being similar to otherpopulations from north hemisphere. Nevertheless,although NOR location described here for S. truttafario is conservative in the chromosome pair 11, anadditional NOR in the chromosome pair 9 is anuncommon feature in other taxa. Further studies inS. trutta fario using cytological techniques widelyperformed in other subspecies (e.g., C-banding,CMA3 fluorochrome) are necessary to be done, thusincreasing the antecedents to evaluate possiblekaryological variation or stability throughout itswide distributional range in Chile.BIBLIOGRAPHYBOGART, J. 1973. Method for obtaining chromosomes.Caldasia 11(52): 29-40.CAPANNA, E., S. CATAUDELLA & T. GENTILE DE FRONZA.1973. Some remarks on the karyotype of anintergeneric hybrid, Salmo trutta x Salmofontinalis (Pisces: Salmoniforms). Genetica 44:194-206.CASTRO, J., S. RODRIGUEZ, B. PARDO, L. SANCHEZ & P.MARTINEZ. 2001. Population analysis of an unusualNOR-site polymorphism in brown trout (Salmotrutta L.). Hereditas 86: 291-302.ITURRA, P., R. MORENO & A. VELOSO. 1986. Variacióncromosómica en truchas de Chile Central. XCongreso Latinoamericano de Zoología. p. 137.KARAKOUSIS, M., J. PASCHOS & C. TRIANTAPHYLLIDIS. 1992.Chromosomal studies in Brown trout Salmo truttaL. populations. Cytobios 72: 266-269.HARTLEY, S. & M. HORNE. 1984. Chromosomerelationships in the genus Salmo. Chromosoma90: 229-237.HARTLEY, S. 1987. The chromosomes of salmonid fishes.Biological Review 62: 197-214.HULATA, G. 2001. Genetic manipulation in aquaculture: areview of stock improvement by classical andmodern technologies. Genetica 111: 155-173.MARTÍNEZ, P., A. VIÑAS, C. BOUZA, J. ARIAS, R. AMARO &L. SÁNCHEZ. 1991. Cytogenetical characterizationof hatchery stocks and natural populations of Seaand Brown trout from northwestern Spain.Heredity 66: 9-17.MAYR, B., P. RAB & M. KALAT. 1986. Localisation of NORsand counterstain-enhanced fluorescence studiesin Salmo gairdneri and Salmo trutta (Pisces,Chromosomes and ag-nor location in fluviate populations: NORTHLAND-LEPPE, I. ET AL.48Gayana 73(1), 2009Salmonidae). Theorethical  Applied Genetics 71:703-707.NYGREN, A., B. NILSSON & M. JAHNKE. 1971. Cytologicalstudies in Salmo trutta alpinus. Hereditas 67:259-268.PHILLIPS, R. & P. RÁB. 2001. Chromosome evolution inthe Salmonidae (Pisces): an update. BiologicalReview 76: 1-25.RAICU, P. & E. TAISESCU. 1977. Cytogenetic study in Salmoirideus and Salmo trutta fario. Cytologia 42 : 311-314.REZA, M., S. DORAFSHAN, T. TAVAKOLIAN, M. KHAZAB &H. ABDOLHAY.  2006. Karyological analysis ofendangered Caspian salmon Salmo trutta caspius(Kessler, 1877). Aquaculture Research 37: 1341-1347.SÁNCHEZ-RUFAS, J., P. ITURRA, W. DE SOUZA & E. ESPONDA.1982. Simple silver staining procedures for thelocation of nucleolus and nucleolar organizerunder light and electron microscopy. ArchiveBiology 93: 267-274.SÁNCHEZ, L., P. MARTÍNEZ, P. VIÑAS & BOUZA. 1990.Analysis of the structure and variability ofnucleolar organizer regions of Salmo trutta by C-Ag and restriction endonuclease banding.Cytogenetic Cell Genetic 54: 6-9.SÁNCHEZ, L., P. MARTINEZ, C. BOUZA & A. VIÑAS. 1991.Chromosomal heterochromatin differentiation inSalmo trutta with restriction enzymes. Hereditas66: 241-249.SOTO D., I. ARISMENDI, J. GONZÁLEZ, J. SANZANA, F. JARA,C. JARA, E. GUZMAN & A. LARA. 2006. SouthernChile, trout and salmon country: invasion patternsand threats for native species. Revista Chilena deHistoria Natural 79: 97-117.WOZNICKI, P. & M. LUCZYNSKI. 1997. Chromosome studiesin Salmo trutta m. fario from  Poland:Hypothetical evolution of the 11th, 12th and 14thchromosome pairs in the Salmo karyotype.Cytobios 91: 207-214.WOZNICKI, P., L. SANCHEZ, P. MARTINEZ, B. PARDO & M.JANKUN. 2000. A population analysis of the structureand variability of NOR in Salmo Trutta by Ag,CMA3 and ISH. Genetica 108(6): 113-118.ZENZES, M. & I. VOICULESCU. 1975. C-banding patterns inSalmo trutta, a species of tetraploid origin.Genetica 45: 531-536.Recibido: 12.12.08Aceptado: 05.05.09

Chromosomes and Ag-NOR location in fluviate populations of Salmo trutta fario L. 1758 (Salmoniformes: Salmonidae) from Atacama Desert, Chile

http://repositoriodigital.uct.cl/bitstream/handle/10925/632/Chromosomes_AgNOR.pdf?sequence=3

Cromosomas y localizacion de Ag-NOR en poblaciones fluviales de Salmo trutta fario L. 1758 (Salmoniformes: Salmonidae) del Desierto de Atacama, Chile

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