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El cariotipo del pejelagarto Atractosteus tropicus se describe por medio de tinción Giemsa de 295 preparaciones cromosómicas en mitosis a partir de 120 larvas y 15 adultos (5 hembras y diez machos) de la población que habita en Tabasco, sureste de México. El número diploide 2n=56 cromosomas se dio en 281 dispersiones cromosómicas de un total de 445 muestras, de ellas 73 dispersiones provinieron de 206 metafases larvales, y 208 dispersiones de 239 metafases de adultos. Se observó variación en el número de cromosomas desde 46 hasta 64 elementos cromosómicos (larvas). Las metafases con 58 cromosomas fueron el segundo valor más abundante, después del número diploide 2n=56 (35%). En los adultos esa variación no fue relevante. Esta variación cromosómica se relaciona con microcromosomas móviles. El cariotipo se determinó de seis dispersiones cromosómicas bien definidas de tres hembras y tres machos; y el cariotipo promedio se integró de ocho pares de cromosomas metacéntricos (m), cuatro pares de cromosomas submetacéntricos (sm), ocho pares de telocéntricos (t), y ocho pares de microcromosomas telocéntricos (*t) El número fundamental observado en el cariotipo típico promedio fue NF = 80 brazos cromosómicos. No se detectaron diferencias sexuales.Karyotype of the tropical gar Atractosteus tropicus Lepisosteiformes: Lepisosteidae) and chromosomal variation in their larval and adults. The karyotype of the tropical gar Atractosteus tropicus is described from conventional Giemsa-staining of 295 mitotic chromosome slides from 120 larvae and 15 adults (five females and ten males) from Tabasco, southern of Mexico. The diploid number 2n = 56 chromosomes was calculated (73 spreads from 206 larval and 208 adult metaphases). Variation on chromosome number was from 46 (4.4%) to 64 (3.9%) chromosome elements on larval samples, whereas 58 (11.7 %) chromosomes were the second most abundant after the diploid number of 2n = 56 (35%). Such variation was related with the presence of mobile microchromosomes. The karyotype was determined from six clear chromosome spreads photographed from three females and three males. The averaged karyotype was integrated by eight pairs of metacentric (m) chromosomes, four submetacentric (sm) pairs, eight telocentric (t) pairs and eight pairs of telocentric micro-chromosomes (*t). The fundamental number was FN = 80 chromosome arms. We saw no sexual differences on chromosome structure. Rev. Biol. Trop. 57 (3): 529-539. Epub 2009 September 30.

La sabaleta Brycon henni, es un pez nativo del occidente colombiano importante para la seguridad alimentaria de las poblaciones ribereñas y para la pesca deportiva por sus característica combativas. El desarrollarse entre los 18 y 28ºC la convierte en una especie de cultivo promisoria. Un estudio citogenético a partir de células branquiales indicó diferentes complementos cromosómicos. Este trabajo aplicó la técnica de cultivo de linfocitos a muestras de sangre de adultos. Las muestras de sangre total fueron sembradas en 4 ml de medio de cultivo Ham-F12, suplementado con 0.5 ml de Suero Fetal Bovino y 0.7 ml del mitógeno Fitohemaglutinina M (Gibco®) durante 96 hr a 28ºC; 1.5 hr antes de la cosecha agregamos 100µl de Colcemid al 10% como factor antimitótico. Cada cultivo se incubó con 10 ml de solución hipotónica KCl 0.56% por 24 min a 37ºC, para continuar con tres fijaciones sucesivas, centrifugaciones y tinción Giemsa al 5%. Las mejores metafases fueron fotografiadas en microscopio, correspondientes a 6 machos y 8 hembras, indicando un número diploide de 50 cromosomas, clasificados en Metacéntricos (26M), Submetacéntricos (16SM) y Subtelocéntricos (8ST), para un número fundamental (NF) de 100 brazos. La tendencia evolutiva hallada fue de tipo B; no se encontraron cromosomas supernumerarios pero sí un primer par de cromosomas metacéntricos grandes, considerado marcador para el género Brycon, no determinante de heteromorfismo sexual. Estos resultados coinciden con los demás bricónidos investigados, en donde se podría considerar un ancestro común con un número cromosómico básico y cariotipos simétricos.Cytogenetic characterization of the neotropical fish Brycon henni (Pisces: Characidae). Brycon henni, is a native fish from Western Colombia is important as food and in sport fishing, and could be cultured in waters between 18 and 28ºC. A previous cytogenetic study in branchial cells indicated different chromosomal complements. Total blood samples were seeded in 4 ml Ham-F12 culture medium, supplemented with 0.5 ml Bovine Fetal Serum and 0.7 ml Phyitohemaglutinin M (Gibco®) during 96 hr at 28ºC; an antimitotic factor (100µl Colcemid® 10%) was added. Cells were incubated in 10 ml KCl hypotonic solution (0.56%) for 24 min at 37ºC, fixed in methanol; acetic acid (3: 1) three times, separated by centrifugations, extended drip, and the chromosomes slides were stained with 5% Giemsa (5%). The best metaphases (6 males and 8 females) were photographed. There was a diploid number of 50 chromosomes: Metacentrics (26M), Submetacentrics (16SM) and Subtelocentrics (8ST). The fundamental number is 100 arms. The evolutionary tendency is type B with no supernumerary chromosomes; a first pair of big metacentric chromosomes is characteristic for Brycon, while no chromosomic sexual heteromorfism was detected. Rev. Biol. Trop. 56 (4): 1619-1628. Epub 2008 December 12.

En los últimos años se ha registrado una disminución importante en el número de individuos de la tortuga marina Caretta caretta anidantes en el Caribe colombiano, situación que pone en evidencia la posibilidad de su extinción a mediano plazo. Por esto, es necesario implementar planes para su manejo y conservación. En este estudio se determinaron los requerimientos del cultivo de linfocitos de Caretta caretta para la obtención de cariotipos que permitan la identificación citogenética, el estudio inmunológico y toxicológico de individuos sin necesidad de sacrificarlos. Se muestrearon 47 individuos de C. caretta de Santa Marta, Colombia obteniendo sangre periférica con la que se realizaron ensayos de las diferentes variables hasta obtener las condiciones óptimas para el cultivo convencional de linfocitos. El cariotipo obtenido presentó 56 cromosomas: 32 macrocromosomas y 24 microcromosomas. El ideograma mostró que C. caretta tiene cuatro grupos de cromosomas: el grupo A compuesto por doce (12) pares de cromosomas de mayor tamaño. El Grupo B compuesto por cuatro (4) pares de cromosomas medianos y pequeños y el Grupo C conformado por 12 pares de microcromosomas. No se observaron cromosomas sexuales. Estos resultados están en desacuerdo con el cariotipo descrito por Kamesaki (1989), debido posiblemente a que las muestras analizadas en ese estudio fueron colectadas en el Océano Pacifico (Japón). El presente estudio es el primero realizado con tortugas del Océano Atlántico que cuenta con la descripción completa de la morfología cromosómica. Es posible, que una de las estrategias adaptativas de esta especie sea el intercambio genético con otras especies de la familia, que produce individuos híbridos viables. En este aspecto se ha descrito la hibridación de tortugas Caretta caretta con Eretmochelys imbricata, Chelonia mydas y Lepidochelys kempii, esto sugiere la posibilidad que los individuos caracterizados en este estudio sean híbridos viables de C. caretta, por lo tanto, se hace necesario realizar estudios a nivel molecular.Lymphocyte culture and partial karyotype of the marine turtle Caretta caretta (Testudines: Cheloniidae) in Santa Marta, Colombian Caribbean. Over the past few years an important reduction in the number of nesting marine turtle Caretta caretta individuals has been registered in the Colombian Caribbean, raising the question of a possible extinction in the medium term. A conservation plan is needed. We studied the culture requirements for C. caretta lymphocytes and preliminary karyotype analysis for cytogenetic identification, immunological study and toxicology without the need to kill individuals. Peripheral blood samples were obtained from 47 individuals in Santa Marta, Colombia and tests were made until optimal conditions were established for lymphocyte culture. The karyotype had 56 chromosomes, 32 macrochromosomes and 24 micro-chromosomes. An ideogram showed that C. caretta has four groups of chromosomes. Sexual chromosomes were not observed. These results do not coincide with the karyotype described from the Pacific (Japan). The present study is the first to include a complete description of the chromosome morphology of turtles from the Atlantic Ocean. it is possible that one of the adaptive strategies of this species is genetic interchange with other species of the family, producing viable hybrids. individuals in this study might be viable hybrids of C. caretta and further molecular studies are needed. Rev. Biol. Trop. 56 (3): 1459-1469. Epub 2008 September 30.

El cariotipo de Plicopurpura pansa y P. columellaris fue determinado a partir de 17 y 13 especímenes adultos respectivamente. Adicionalmente, se utilizaron ocho cápsulas de P. pansa. Contamos 186 campos mitóticos en P. pansa: 59 en los adultos y 127 en los embriones; y 118 campos en P. columellaris. En ambas especies se observaron números cromosómicos desde 30 hasta 42. Las variaciones en número cromosómico fueron identificadas en cada individuo, no habiendo ninguna relación con los tejidos (branquias, músculo y estómago) empleados. El número modal diploide típico fue de 2n=36 cromosomas en ambas especies. En los especímenes adultos seleccionamos cinco de las mejores dispersiones cromosómicas para armar el cariotipo. Calculamos los estadísticos citogenéticos clásicos, longitudes relativas, proporción de brazos, índice centromérico y la diferencia entre brazos. Identificamos en ambas especies tres pares de cromosomas metacéntricos y quince pares de cromosomas telocéntricos. Esta clasificación no fue suficientemente robusta, por lo que dividimos el complemento cromosómico de cada especie en cuatro grupos ("a", "b", "c" y "d") utilizando como criterio las longitudes relativas (p+q). Hubo diferencias significativas entre grupos cromosómicos por especie y entre especies, los tres primeros pares de cromosomas (grupo "a" birrámeos) y los dos últimos pares (grupo "d" monorrámeos menores) (análisis de varianza de dos vías, pKaryotypes of the purple snails Plicopurpura pansa and Plicopurpura columellaris (Gastropoda: Muricidae). The karyotypes of the purple snails Plicopurpura pansa (Gould, 1853) and P. columellaris (Lamarck, 1816) were established from 17 and 13 adults, respectively; and from eight capsules with embryos of P. pansa. In P. pansa were counted 59 mitotic fields in the adults and 127 in embryos; and 118 fields in P. columellaris. Chromosome numbers from 30 to 42 were observed in both species. Such a variation was notorious in each sample and there was no evidence of any relationship with tissue (gill, muscle and stomach). Both species has a typical modal number of 2n=36 chromosomes. Five good quality chromosome spreads were selected from adults of each species to assemble the karyotype. Classic cytogenetics statistics like relative lengths, arm ratio, centromeric index and the difference between long and short arms are presented. There were three pairs of metacentric and fifteen pairs of telocentric chromosomes in both species. This classification was not strong enough, so the chromosome complement by species was divided in four groups ("a", "b", "c" and "d") on the basis of relative lengths (p+q). A comparison of p+q in each chromosome pair was estimated within and between species by two ways analysis of variance and Tukey tests (P

Para contribuir con el ordenamiento de las especies de la familia Cichlidae, se realizó el estudio citogenético de la mojarra pinta Parachromis managuensis. Fueron utilizados veintiún organismos, ocho machos y trece hembras,colectados en Villahermosa, Tabasco, México. Los especímenes se procesaron por técnicas citogenéticas convencionales (con ligeras modificaciones). Se obtuvieron campos mitóticos y meióticos de buena calidad, de los que fueron seleccionados catorce cariotipos para ser analizados merística y estadísticamente. Los especímenes presentaron número modal diploide de 2n=48 cromosomas, similar al reportado para otros cíclidos neotropicales. Cinco pares fueron cromosomas metacéntricos-submetacéntricos (birrámeos) y 19 pares cromosomas subtelocéntricos-telocéntricos (monorrámeos),con número fundamental (NF) de 58 brazos.El número haploide se ratificó por conteo de campos meióticos en metafase I. Los campos mitóticos observados y los cariotipos de machos y hembras no presentaron evidencias heteromórficas para identificar cromosomas sexuales.Citogenetic characterization of the tropical freshwater fish Parachromis managuensis (Pisces: Cichlidae). To describe the cytogenetics of the jaguar cichlid fish Parachromis managuensis, we collected eight males and 13 females in Villahermosa, Tabasco, México. The specimens were processed with standard cytogenetic techniques (slightly modified), and high quality fields of chromosomes in mitosis and meiosis were obtained; 14 of these fields were analyzed by meristics and statistics methods. The specimens presented a diploid modal number of 2n=48 chromosomes, which is similar to the number reported for others Central American cichlids; five pairs were submetacentric-metacentrics(biarmed)and 19 were subtelocentric-telocentric (uni-armed),giving a fundamental number (NF)of 58.The haploid number was confirmed by counting meiotic fields in metaphase I. There was not evidence of heteromorphism: sexual chromosomes were not identifiable. Rev. Biol. Trop. 54 (1): 35-42. Epub 2006 Mar 31.

The karyotype of the tropical gar Atractosteus tropicus is described from conventional Giemsa-staining of 295 mitotic chromosome slides from 120 larvae and 15 adults (five females and ten males) from Tabasco, southern of Mexico. The diploid number 2n = 56 chromosomes was calculated (73 spreads from 206 larval and 208 adult metaphases). Variation on chromosome number was from 46 (4.4%) to 64 (3.9%) chromosome elements on larval samples, whereas 58 (11.7 %) chromosomes were the second most abundant after the diploid number of 2n = 56 (35%). Such variation was related with the presence of mobile microchromosomes. The karyotype was determined from six clear chromosome spreads photographed from three females and three males. The averaged karyotype was integrated by eight pairs of metacentric (m) chromosomes, four submetacentric (sm) pairs, eight telocentric (t) pairs and eight pairs of telocentric microchromosomes (*t). The fundamental number was FN = 80 chromosome arms. We saw no sexual differences on chromosome structure. [ABSTRACT FROM AUTHOR]

Cytogenetic characterization of the neotropical fish Brycon henni (Pisces: Characidae). Brycon henni, is a native fish from Western Colombia is important as food and in sport fishing, and could be cultured in waters between 18 and 28°C. A previous cytogenetic study in branchial cells indicated different chromosomal complements. Total blood samples were seeded in 4 ml Ham-F12 culture medium, supplemented with 0.5 ml Bovine Fetal Serum and 0.7 ml Phyitohemaglutinin M (Gibco®) during 96 hr at 28°C; an antimitotic factor (100μl Colcemid® 10%) was added. Cells were incubated in 10 ml KCl hypotonic solution (0.56%) for 24 min at 37°C, fixed in methanol; acetic acid (3: 1) three times, separated by centrifugations, extended drip, and the chromosomes slides were stained with 5% Giemsa (5%). The best metaphases (6 males and 8 females) were photographed. There was a diploid number of 50 chromosomes: Metacentrics (26M), Submetacentrics (16SM) and Subtelocentrics (8ST). The fundamental number is 100 arms. The evolutionary tendency is type B with no supernumerary chromosomes; a first pair of big metacentric chromosomes is characteristic for Brycon, while no chromosomic sexual heteromorfism was detected. [ABSTRACT FROM AUTHOR]

Over the past few years an important reduction in the number of nesting marine turtle Caretta caretta individuals has been registered in the Colombian Caribbean, raising the question of a possible extinction in the medium term. A conservation plan is needed. We studied the culture requirements for C. caretta lymphocytes and preliminary karyotype analysis for cytogenetic identification, immunological study and toxicology without the need to kill individuals. Peripheral blood samples were obtained from 47 individuals in Santa Marta, Colombia and tests were made until optimal conditions were established for lymphocyte culture. The karyotype had 56 chromosomes, 32 macrochromosomes and 24 microchromosomes. An ideogram showed that C. caretta has four groups of chromosomes. Sexual chromosomes were not observed. These results do not coincide with the karyotype described from the Pacific (Japan). The present study is the first to include a complete description of the chromosome morphology of turtles from the Atlantic Ocean. It is possible that one of the adaptive strategies of this species is genetic interchange with other species of the family, producing viable hybrids. Individuals in this study might be viable hybrids of C. caretta and further molecular studies are needed. [ABSTRACT FROM AUTHOR]

Karyotypes of the purple snails Plicopurpura pansa and Plicopurpura columellaris (Gastropoda: Muricidae). The karyotypes of the purple snails Plicopurpura pansa (Gould, 1853) and P. columellaris (Lamarck, 1816) were established from 17 and 13 adults, respectively; and from eight capsules with embryos of P. pansa. In P. pansa were counted 59 mitotic fields in the adults and 127 in embryos; and 118 fields in P. columellaris. Chromosome numbers from 30 to 42 were observed in both species. Such a variation was notorious in each sample and there was no evidence of any relationship with tissue (gill, muscle and stomach). Both species has a typical modal number of 2n=36 chromosomes. Five good quality chromosome spreads were selected from adults of each species to assemble the karyotype. Classic cytogenetics statistics like relative lengths, arm ratio, centromeric index and the difference between long and short arms are presented. There were three pairs of metacentric and fifteen pairs of telocentric chromosomes in both species. This classification was not strong enough, so the chromosome complement by species was divided in four groups ("a", "b", "c" and "d") on the basis of relative lengths (p+q). A comparison of p+q in each chromosome pair was estimated within and between species by two ways analysis of variance and Tukey tests (P<0.05). Significant differences were identified among chromosome groups in each species; the differences between species were given by the first three pairs of chromosomes (group "a" biarmed) and the last two pairs (group "d" uniarmed). Deviations in chromosome number and relative lengths probably are given by chromosome rearrangements, related with chromosome polymorphism and presence of the atypical microchromosome "B". The fundamental number in both species was characterized by 42 chromosome arms. No sex chromosomes were identified. [ABSTRACT FROM AUTHOR]