First constitutive heterochromatin characterization and Karyotype of white stork Ciconia ciconia (Aves: Ciconiidae) / Primeira caracterização constitutiva de heterocromatina e cariótipo de cegonhabranca Ciconia ciconia (Aves: Ciconiidae)

The karyotype and constitutive heterochromatin pattern of the white stork Ciconia ciconia samples obtained from Manzala lake, Dimiaat, Egypt was described. Somatic cells of Ciconia ciconia samples have diploid number 2n= 68 chromosomes. Out of 68 chromosomes, 11 pairs including sex chromosomes were macrochromosomes and the remaining pairs were microchromosomes. Of the 11 macrochromosome pairs, no.1, 2, 4 and 5 were submetacentric and pairs no. 6, 7 and 8 were described as metacentric. In addition, the autosome pair no.3 was subtelocentric, while autosome pair no.9 was acrocentric. Also, the sex chromosome Z represents the fourth one in size and it was classified as submetacentric while, W chromosome appeared as medium size and was acrocentric. Furthermore, C-banding pattern (constitutive heterochromatin) revealed variation in their sizes and occurrence between macrochromosomes. Pairs no. 7 and 8 of autosomes exhibited unusual distribution of heterochromatin, where they appeared as entirely heterochromatic. This may be related to the origin of sex chromosomes Z and W. However, there is no sufficient evidence illustrate the appearance of entirely heterochromatic autosomes. Therefore, there is no available cytogenetic literature that describes the C-banding and karyotype of Ciconia Ciconia, so the results herein are important and may assist in cytogenetic study and evolutionary pattern of Ciconiiformes.

O cariótipo e o padrão constitutivo de heterocromatina das amostras de cegonha-branca Ciconia ciconia obtidas no lago Manzala, Dimiaat, Egito, foram descritos. As células somáticas de amostras de Ciconia ciconia possuem número diploide 2n = 68 cromossomos. Dos 68 cromossomos, 11 pares incluindo cromossomos sexuais eram macrocromossomos e os pares restantes eram microcromossomos. Dos 11 pares de macrocromossomos, os nos 1, 2, 4 e 5 eram submetacêntricos, e os pares nos 6, 7 e 8 foram descritos como metacêntricos. Além disso, o par de autossomos no 3 era subtelocêntrico, enquanto o par de autossomos no 9 era acrocêntrico. Além disso, o cromossomo sexual Z representa o quarto em tamanho e foi classificado como submetacêntrico, enquanto o cromossomo W apareceu como de tamanho médio e acrocêntrico. Além disso, o padrão de bandamento C (heterocromatina constitutiva) revelou variação em seus tamanhos e ocorrência entre macrocromossomos. Pares nºs 7 e 8 dos autossomos exibiram distribuição incomum de heterocromatina, onde apareceram como totalmente heterocromáticos. Isso pode estar relacionado à origem dos cromossomos sexuais Z e W. No entanto, não há evidências suficientes para ilustrar o aparecimento de autossomos totalmente heterocromáticos. Portanto, não há literatura citogenética disponível que descreva o bandamento C e o cariótipo de Ciconia ciconia, portanto os resultados aqui apresentados são importantes e podem auxiliar no estudo citogenético e no padrão evolutivo de Ciconiiformes.

First constitutive heterochromatin characterization and Karyotype of white stork Ciconia ciconia (Aves: Ciconiidae)

Abstract The karyotype and constitutive heterochromatin pattern of the white stork Ciconia ciconia samples obtained from Manzala lake, Dimiaat, Egypt was described. Somatic cells of Ciconia ciconia samples have diploid number 2n= 68 chromosomes. Out of 68 chromosomes, 11 pairs including sex chromosomes were macrochromosomes and the remaining pairs were microchromosomes. Of the 11 macrochromosome pairs, no.1, 2, 4 and 5 were submetacentric and pairs no. 6, 7 and 8 were described as metacentric. In addition, the autosome pair no.3 was subtelocentric, while autosome pair no.9 was acrocentric. Also, the sex chromosome Z represents the fourth one in size and it was classified as submetacentric while, W chromosome appeared as medium size and was acrocentric. Furthermore, C-banding pattern (constitutive heterochromatin) revealed variation in their sizes and occurrence between macrochromosomes. Pairs no. 7 and 8 of autosomes exhibited unusual distribution of heterochromatin, where they appeared as entirely heterochromatic. This may be related to the origin of sex chromosomes Z and W. However, there is no sufficient evidence illustrate the appearance of entirely heterochromatic autosomes. Therefore, there is no available cytogenetic literature that describes the C-banding and karyotype of Ciconia Ciconia, so the results herein are important and may assist in cytogenetic study and evolutionary pattern of Ciconiiformes.

Resumo O cariótipo e o padrão constitutivo de heterocromatina das amostras de cegonha-branca Ciconia ciconia obtidas no lago Manzala, Dimiaat, Egito, foram descritos. As células somáticas de amostras de Ciconia ciconia possuem número diploide 2n = 68 cromossomos. Dos 68 cromossomos, 11 pares incluindo cromossomos sexuais eram macrocromossomos e os pares restantes eram microcromossomos. Dos 11 pares de macrocromossomos, os nos 1, 2, 4 e 5 eram submetacêntricos, e os pares nos 6, 7 e 8 foram descritos como metacêntricos. Além disso, o par de autossomos no 3 era subtelocêntrico, enquanto o par de autossomos no 9 era acrocêntrico. Além disso, o cromossomo sexual Z representa o quarto em tamanho e foi classificado como submetacêntrico, enquanto o cromossomo W apareceu como de tamanho médio e acrocêntrico. Além disso, o padrão de bandamento C (heterocromatina constitutiva) revelou variação em seus tamanhos e ocorrência entre macrocromossomos. Pares nos 7 e 8 dos autossomos exibiram distribuição incomum de heterocromatina, onde apareceram como totalmente heterocromáticos. Isso pode estar relacionado à origem dos cromossomos sexuais Z e W. No entanto, não há evidências suficientes para ilustrar o aparecimento de autossomos totalmente heterocromáticos. Portanto, não há literatura citogenética disponível que descreva o bandamento C e o cariótipo de Ciconia ciconia, portanto os resultados aqui apresentados são importantes e podem auxiliar no estudo citogenético e no padrão evolutivo de Ciconiiformes.

First constitutive heterochromatin characterization and Karyotype of white stork Ciconia ciconia (Aves: Ciconiidae) / Primeira caracterização constitutiva de heterocromatina e cariótipo de cegonha-branca Ciconia ciconia (Aves: Ciconiidae)

Abstract The karyotype and constitutive heterochromatin pattern of the white stork Ciconia ciconia samples obtained from Manzala lake, Dimiaat, Egypt was described. Somatic cells of Ciconia ciconia samples have diploid number 2n= 68 chromosomes. Out of 68 chromosomes, 11 pairs including sex chromosomes were macrochromosomes and the remaining pairs were microchromosomes. Of the 11 macrochromosome pairs, no.1, 2, 4 and 5 were submetacentric and pairs no. 6, 7 and 8 were described as metacentric. In addition, the autosome pair no.3 was subtelocentric, while autosome pair no.9 was acrocentric. Also, the sex chromosome Z represents the fourth one in size and it was classified as submetacentric while, W chromosome appeared as medium size and was acrocentric. Furthermore, C-banding pattern (constitutive heterochromatin) revealed variation in their sizes and occurrence between macrochromosomes. Pairs no. 7 and 8 of autosomes exhibited unusual distribution of heterochromatin, where they appeared as entirely heterochromatic. This may be related to the origin of sex chromosomes Z and W. However, there is no sufficient evidence illustrate the appearance of entirely heterochromatic autosomes. Therefore, there is no available cytogenetic literature that describes the C-banding and karyotype of Ciconia Ciconia, so the results herein are important and may assist in cytogenetic study and evolutionary pattern of Ciconiiformes.

Resumo O cariótipo e o padrão constitutivo de heterocromatina das amostras de cegonha-branca Ciconia ciconia obtidas no lago Manzala, Dimiaat, Egito, foram descritos. As células somáticas de amostras de Ciconia ciconia possuem número diploide 2n = 68 cromossomos. Dos 68 cromossomos, 11 pares incluindo cromossomos sexuais eram macrocromossomos e os pares restantes eram microcromossomos. Dos 11 pares de macrocromossomos, os nos 1, 2, 4 e 5 eram submetacêntricos, e os pares nos 6, 7 e 8 foram descritos como metacêntricos. Além disso, o par de autossomos no 3 era subtelocêntrico, enquanto o par de autossomos no 9 era acrocêntrico. Além disso, o cromossomo sexual Z representa o quarto em tamanho e foi classificado como submetacêntrico, enquanto o cromossomo W apareceu como de tamanho médio e acrocêntrico. Além disso, o padrão de bandamento C (heterocromatina constitutiva) revelou variação em seus tamanhos e ocorrência entre macrocromossomos. Pares nos 7 e 8 dos autossomos exibiram distribuição incomum de heterocromatina, onde apareceram como totalmente heterocromáticos. Isso pode estar relacionado à origem dos cromossomos sexuais Z e W. No entanto, não há evidências suficientes para ilustrar o aparecimento de autossomos totalmente heterocromáticos. Portanto, não há literatura citogenética disponível que descreva o bandamento C e o cariótipo de Ciconia ciconia, portanto os resultados aqui apresentados são importantes e podem auxiliar no estudo citogenético e no padrão evolutivo de Ciconiiformes.

Causes and consequences of DNA content variation in Zea / Causas y consecuencias de la variación del contenido de ADN en Zea

ABSTRACT Cytogenetic evidence indicates that Zea, which comprises maize (Z. mays ssp. mays) and its wild relatives, is an allopolyploid genus. Our research group has carried out numerous cytogenetic studies on Zea species, mainly focused on native Argentinian and Bolivian maize landraces. We found a wide inter- and intraspecific genome size variation in the genus, with mean 2C-values ranging between 4.20 and 11.36 pg. For the maize landraces studied here, it varied between 4.20 and 6.75 pg. The objectives of this work are to analyze the causes of genome size variation and to discuss their adaptive value in Zea. This variation is mainly attributed to differences in the heterochromatin located in the knobs and to the amount of interspersed DNA from retrotransposons. Polymorphisms in presence or absence of B-chromosomes (Bs) and the population frequency of Bs are also a source of genome size variation, with doses ranging between one and eight in the landraces analyzed here. Correlation analysis revealed that the percentage of heterochromatin is positively correlated with genome size. In addition, populations cultivated at higher altitudes, which are known to be precocious, have smaller genome sizes than do those growing at lower altitudes. This information, together with the positive correlation observed between the length of the vegetative cycle and the percentage of heterochromatin, led us to propose that it has an adaptive role. On the other hand, the negative relationship found between Bs and heterochromatic knobs allowed us to propose the existence of an intragenomic conflict between these elements. We hypothesize that an optimal nucleotype may have resulted from such intranuclear conflict, where genome adjustments led to a suitable length of the vegetative cycle for maize landraces growing across altitudinal clines.

RESUMEN La evidencia citogenética indica que el género Zea, el maíz (Z. mays ssp. mays) y sus parientes silvestres, posee un origen alopoliploide. Nuestro grupo de investigación ha realizado numerosos estudios en especies de Zea, principalmente en maíces nativos de Argentina y Bolivia. En este género, hallamos una amplia variación inter e intraespecífica en el tamaño del genoma, con valores 2C medios que oscilan entre 4,20 y 11,36 pg. El valor 2C medio de los maíces nativos estudiados varió entre 4,20 y 6,75 pg. Los objetivos de este trabajo son analizar las causas de la variación del tamaño del genoma en Zea y discutir su valor adaptativo. Esta variación se atribuye principalmente a las diferencias en la heterocromatina de los knobs y en la cantidad de ADN intercalado de los retrotransposones. Otras fuentes de variación son los polimorfismos para presencia/ausencia de cromosomas B (Bs) y para la frecuencia poblacional de Bs en las razas analizadas, con dosis que oscilan entre uno y ocho Bs. El porcentaje de heterocromatina se correlaciona positivamente con el tamaño del genoma. Las poblaciones cultivadas en altitudes altas, que son precoces, tienen tamaños de genoma más pequeños que las que crecen en bajas altitudes. Esta información, junto con la correlación positiva observada entre la duración del ciclo vegetativo y el porcentaje de heterocromatina, nos llevó a proponer el rol adaptativo de la heterocromatina. Por otro lado, la relación negativa encontrada entre Bs y knobs heterocromáticos nos permitió proponer la existencia de un conflicto intragenómico entre estos elementos. Hipotetizamos que de este conflicto intranuclear habría resultado el nucleotipo óptimo, donde ajustes genómicos condujeron a una duración adecuada del ciclo vegetativo en las razas de maíz que crecen a lo largo de clines altitudinales.

Chromosomic studies in Zephyranthes citrina baker (Amaryllidaceae), a polyploid ornamental / Estudios cromosómicos en Zephyranthes citrina baker (Amaryllidaceae), un poliploide ornamental

ABSTRACT Zephyranthes citrina is an ornamental American bulbous plant used as an ornamental garden crop for the aesthetic qualities of its yellow perigonium. The objective of this work was to characterize the species by classical chromosome staining and fluorochrome banding. A sporophytic chromosome number of 2n=8x=48 chromosomes was observed, being the karyotypic formula 20 m + 26 sm + 2 st. Satellites were detected in the short arm of metacentric chromosomes 8, 9, 11 and 12, which colocalized with constitutive heterochromatin CMA+/DAPI-/0 bands. The karyotype comprised chromosome pairs with terminal constitutive heterochromatin bands that included satellites and heteromorphic clusters indicating that it is an allooctoploid. These results will be used as a tool for monitoring genetic improvement, in interspecific crosses and its progenies and in biotechnological procedures by in vitro culture.

RESUMEN Zephyranhtes citrina es una planta bulbosa americana, ornamental, utilizada en jardines por las cualidades estéticas de su perigonio amarillo. El objetivo de este trabajo fue caracterizar citogenéticamente la especie con tinción clásica convencional y bandeo cromosómico. Se observó un número cromosómico esporofítico de 2n=8x=48, siendo la fórmula cariotípica 20 m + 26 sm + 2st. Se detectaron satélites en el brazo corto de los cromosomas metacéntricos 8, 9, 11 y 12, que co-localizaron con bandas de heterocromatina constitutiva CMA+/DAPI-. El cariotipo comprendió pares de cromosomas con bandas de heterocromatina constitutivas terminales que incluyeron satélites y grupos heteromórficos que indican que es un alooctoploide. Estos resultados serán usados como herramientas en el monitoreo del mejoramiento genético, en análisis de cruzamientos interespecíficos y progenies y en procedimientos biotecnológicos de cultivo in vitro.

Alteraciones citogenéticas en pacientes con diagnóstico de infertilidad en Lima, Perú / Cytogenetic abnormalities in patients with infertility diagnosis in Lima, Peru

INTRODUCCIÓN: La infertilidad es una enfermedad multicausal y el componente genético representa uno de sus principales eventos. Si bien la distribución de la infertilidad puede variar entre poblaciones, las parejas de los países con bajos y medianos ingresos pueden verse más afectadas por la infertilidad, con una proporción de alteraciones citogenéticas aún no esclarecidas. OBJETIVO: Evaluar la frecuencia de alteraciones citogenéticas y su correlación con el número de abortos en pacientes peruanas con diagnóstico de infertilidad. MÉTODO: Se realizó un estudio de corte transversal en 400 pacientes de 18 a 60 años, de ambos sexos, con diagnóstico de infertilidad. Se registraron las características clínicas disponibles durante el examen genético y el análisis citogenético convencional fue con bandeo GTG en muestras de sangre periférica. El análisis de correlación se realizó con la prueba de Spearman. RESULTADOS: Del total, 389 pacientes cumplieron los criterios de inclusión, y de estos, 169 (43,44%) tuvieron reportes de abortos (promedio: 2,25, rango: 1-7). Hallamos una correlación significativa ente el número de abortos y las alteraciones citogenéticas (p < 0,000). Reportamos 25/289 (6,43%) alteraciones cromosómicas, de las que 11/25 (44%) fueron heterocromatinas constitutivas y 6/25 (24%) fueron translocaciones reciprocas. Las alteraciones citogenéticas más frecuentes fueron 16qh+ y 9qh+ (ambas con un 16%), y afectaron a 17 (68%) varones. CONCLUSIONES: Existe una moderada frecuencia de alteraciones citogenéticas en pacientes peruanos con diagnóstico de infertilidad, y las alteraciones más frecuentes fueron heterocromatina constitutivas. Además, evidenciamos una correlación significativa ente el número de abortos y las alteraciones citogenéticas.

INTRODUCTION: Infertility is a multicausal disease and the genetic component represents one of its main events. Although the distribution of infertility may vary between populations, couples in low-and-middle-income countries may be more affected by infertility with a proportion of cytogenetic alterations still unclear. OBJECTIVE: To evaluate the frequency of cytogenetic alterations and their correlation with the number of abortions in Peruvian patients with a diagnosis of infertility. METHOD: A cross-sectional study was carried out in 400 patients between 18 and 60 years-old, of both genders with a diagnosis of infertility. The clinical characteristics available during the genetic examination were recorded and the conventional cytogenetic analysis was with GTG banding in peripheral blood samples. The correlation analysis was performed with the Spearman test. RESULTS: Of the total 389 patients who met the inclusion criteria, of these 169 (43.44%) patients had reports of abortions (mean: 2.25, range: 1-7). We found a significant correlation between the number of abortions and cytogenetic alterations (p < 0.000). We report 25/289 (6.43%) chromosomal alterations, where 11/25 (44%) were constitutive heterochromatin, and 6/25 (24%) were reciprocal translocations. The most frequent cytogenetic alterations were 16qh + and 9qh + (both 16%), and affected 17 (68%) men. CONCLUSIONS: There is a moderate frequency of cytogenetic alterations in Peruvian patients diagnosed with infertility, where the most frequent alterations were constitutive heterochromatin. Furthermore, we evidenced a significant correlation between the number of abortions and cytogenetic alterations.

Chromosomal karyotypes and C-band analysis of Triatoma rubrofasciata in China / 中国血吸虫病防治杂志

Objective To investigate the karyotypes and C bands of Triatoma rubrofasciata in China, so as to understand its chromosome number, morphology and C-band staining of T. rubrofasciata. Methods The testis specimens were sampled from male T. rubrofasciata collected from Shunde City, Guangdong Province, prepared into slides of metaphase chromosomes and subjected to Giemsa staining and C-band staining. The morphology of metaphase chromosomes and the location of heterochromatin were observed using microscopy, and the long arm and short arm of each chromosome and total chromosome length were recorded to analyze the karyotypes and C bands of T. rubrofasciata. Results The male T. rubrofasciata presented a chromosome number of 2n = 25, including 22 autosomes and 3 sex chromosomes. The relative length of chromosomes ranged from 3.59% to 12.76%, the arm ratio was 1.06 to 1.24, and the centromere index was 44.76% to 48.47%. All chromosomes were metacentric chromosomes and the karyotype formula was 2n = 22 metacentric + X1X2Y, and the C bands varied on different chromosomes. No heterochromatin was found in the X chromosome, and the overall staining appeared pale, while heterochromatin was detected in all regions of the Y chromosome, and the overall staining appeared dark. In addition, heterochromatin was present in both ends of the autosome. Conclusions The male T. rubrofasciata presents a chromosome number of 2n = 25 in China, and the karyotype formula is 2n = 22 metacentric + X1X2Y. C-banding shows dark staining of the Y chromosome, pale staining of the X chromosome, and dark staining of both ends of the autosome. Our data may provide insights into the investigation on the origin, evolution and gene mapping of T. rubrofasciata in China.

Chromosome analysis in Saccodon wagneri (Characiformes) and insights into the karyotype evolution of Parodontidae

Parodontidae is a relatively small group of Neotropical characiform fishes consisting of three genera (Apareiodon, Parodon, and Saccodon) with 32 valid species. A vast cytogenetic literature is available on Apareiodon and Parodon, but to date, there is no cytogenetic data about Saccodon, a genus that contains only three species with a trans-Andean distribution. In the present study the karyotype of S. wagneri was described, based on both conventional (Giemsa staining, Ag-NOR, C-bands) and molecular (repetitive DNA mapping by fluorescent in situ hybridization) methods. A diploid chromosome number of 2n = 54 was observed in both sexes, and the presence of heteromorphic sex chromosomes of the ZZ/ZW type was detected. The W chromosome has a terminal heterochromatin band that occupies approximately half of the long arm, being this band approximately half the size of the Z chromosome. The FISH assay showed a synteny of the 18S-rDNA and 5S-rDNA genes in the chromosome pair 14, and the absence of interstitial telomeric sites. Our data reinforce the hypothesis of a conservative karyotype structure in Parodontidae and suggest an ancient origin of the sex chromosomes in the fishes of this family.(AU)

Parodontidae é um grupo relativamente pequeno de peixes caraciformes neotropicais que consiste em três gêneros (Apareiodon, Parodon e Saccodon) com 32 espécies válidas. Uma vasta literatura citogenética está disponível sobre Apareiodon e Parodon, mas até o momento não há dados citogenéticos sobre Saccodon, um gênero que contém apenas três espécies com distribuição transandina. No presente estudo foi descrito o cariótipo de S. wagneri, baseado em métodos convencionais (coloração de Giemsa, Ag-NOR, bandas C) e moleculares (mapeamento de DNA repetitivo por hibridização fluorescente in situ). Um número cromossômico diplóide de 2n = 54 foi observado, e a presença de cromossomos sexuais heteromórficos do tipo ZZ/ZW foi revelada. O cromossomo W possui uma banda terminal heterocromática que ocupa aproximadamente metade do braço longo, sendo esta banda aproximadamente a metade do tamanho do cromossomo Z. O ensaio FISH mostrou uma sintenia dos genes 18S-rDNA e 5S-rDNA no par de cromossomos 14, e a ausência de sítios teloméricos intersticiais. Nossos dados reforçam a hipótese de uma estrutura cariotípica conservadora em Parodontidae e sugerem uma origem ancestral dos cromossomos sexuais nos peixes desta família.(AU)

Phase-separation in chromatin organization

The organization of chromatin into different types of compact versus open states provides a means to fine tune generegulation. Recent studies have suggested a role for phase-separation in chromatin compaction, raising new possibilities for regulating chromatin compartments. This perspective discusses some specific molecular mechanismsthat could leverage such phase-separation processes to control the functions and organization of chromatin

Targeted Downregulation of kdm4a Ameliorates Tau-engendered Defects in Drosophila melanogaster

BACKGROUND: Tauopathies, a class of neurodegenerative diseases that includes Alzheimer's disease (AD), are characterized by the deposition of neurofibrillary tangles composed of hyperphosphorylated tau protein in the human brain. As abnormal alterations in histone acetylation and methylation show a cause and effect relationship with AD, we investigated the role of several Jumonji domain-containing histone demethylase (JHDM) genes, which have yet to be studied in AD pathology. METHODS: To examine alterations of several JHDM genes in AD pathology, we performed bioinformatics analyses of JHDM gene expression profiles in brain tissue samples from deceased AD patients. Furthermore, to investigate the possible relationship between alterations in JHDM gene expression profiles and AD pathology in vivo, we examined whether tissue-specific downregulation of JHDM Drosophila homologs (kdm) can affect tauR406W-induced neurotoxicity using transgenic flies containing the UAS-Gal4 binary system. RESULTS: The expression levels of JHDM1A, JHDM2A/2B, and JHDM3A/3B were significantly higher in postmortem brain tissue from patients with AD than from non-demented controls, whereas JHDM1B mRNA levels were downregulated in the brains of patients with AD. Using transgenic flies, we revealed that knockdown of kdm2 (homolog to human JHDM1), kdm3 (homolog to human JHDM2), kdm4a (homolog to human JHDM3A), or kdm4b (homolog to human JHDM3B) genes in the eye ameliorated the tauR406W-engendered defects, resulting in less severe phenotypes. However, kdm4a knockdown in the central nervous system uniquely ameliorated tauR406W-induced locomotion defects by restoring heterochromatin. CONCLUSION: Our results suggest that downregulation of kdm4a expression may be a potential therapeutic target in AD.

Variation of the interphase heterochromatin in Artemia (Crustacea, Anostraca) of the Americas is related to changes in nuclear size and ionic composition of hipersaline habitats / Variação da heterocromatina interfásica em Artemia (Crustacea, Anostraca) das Américas está relacionada a mudanças no tamanho nuclear e composição iônica em habitats hipersalinos

Abstract The populations of Artemia (or brine shrimp) from the Americas exhibit a wide variation in the amount of interphase heterochromatin. There is interest in understanding how this variation affects different parameters, from the cellular to the organismal levels. This should help to clarify the ability of this organism to tolerate brine habitats regularly subject to strong abiotic changes. In this study, we assessed the amount of interphase heterochromatin per nucleus based on chromocenter number (N-CHR) and relative area of chromocenter (R-CHR) in two species of Artemia, A. franciscana (Kellog, 1906) (n=9 populations) and A. persimilis (Piccinelli and Prosdocimi, 1968) (n=3 populations), to investigate the effect on nuclear size (S-NUC). The relationship of the R-CHR parameter with the ionic composition (IC) of brine habitats was also analysed. Our results indicate a significant variation in the amount of heterochromatin both within and between species (ANOVA, p<0.001). The heterochromatin varied from 0.81 ± 1.17 to 12.58 ± 3.78 and from 0.19 ± 0.34% to 11.78 ± 3.71% across all populations, for N-CHR and R-CHR parameters, respectively. N-CHR showed less variation than R-CHR (variation index 15.5-fold vs. 62-fold). At least five populations showed a significant association (p<0.05) between R-CHR and S-NUC, either with negative (four populations, r= from -0.643 to -0.443), or positive (one population, r= 0.367) values.Within each species, there were no significant associations between both parameters (p>0.05). The R-CHR and IC parameters were associated significantly for the magnesium ion (r= 0.496, p<0.05) and also for the chloride, sodium and calcium ions (r = from -0.705 to -0.478, p<0.05). At species level, a significant association between both parameters was also found in A. franciscana populations, for the sulphate and calcium ions, in contrast to A. persimilis. These findings suggest that the amount of interphase heterochromatin modifies the nuclear size in Artemia. Our data also indicate that change in the amount of interphase heterochromatin is in line with the ionic composition of brines. This would be a species-specific phenomenon, whose occurrence may be involved in the ability of this organism to survive in these environments.

Resumo As populações de Artemia (ou camarão de salinas) das Américas apresentam uma grande variação na quantidade de heterocromatina interfásica. Há interesse em compreender como esta variação afeta diferentes parâmetros, desde o nível celular até os organismos. Isso deve ajudar a esclarecer a capacidade destes organismos tolerarem habitats extremos de água hipersalinas, que normalmente são submetidos a fortes mudanças abióticas. Neste estudo, avaliou-se a quantidade heterocromatina interfásica por núcleo através do número de cromocentros (N-CHR) e a área relativa de cromocentros (R-CHR) em duas espécies de Artemia, A. franciscana (Kellog, 1906) (n=9 populações) e A. persimilis (Piccinelli e Prosdocimi, 1968) (n=3 populações), para investigar o seu efeito no tamanho nuclear (S-NUC). Também foi analisada a relação de R-CHR com a composição iónica (CI) dos habitats hipersalinos. Nossos resultados indicam uma variação significativa na quantidade de heterocromatina dentro e entre espécies (ANOVA, p<0,001). Em todas as populações, a heterocromatina variou de 0,81 ± 1,17 para 12,58 ± 3,78 e de 0,19 ± 0,34% para 11,78 ± 3,71% para os parâmetros R-CHR e N-CHR, respectivamente. N-CHR apresentou menor variação do que R-CHR (amplitude de variação de 15,5 vezes vs. 62 vezes). Pelo menos cinco populações apresentaram uma associação significativa (p<0,05) entre R-CHR e S-NUC, seja com valores negativos (quatro populações, r = -0,643 a -0,443) ou positivo (uma população, r = 0,367). Os parâmetros R-CHR e CI foram associados significativamente para o íon de magnésio (r = 0,496, p<0,05) e também para os íons cloreto, sódio e cálcio (r = -0,705 a -0,478, p<0,05). Ao nível de espécie, foi também encontrada uma associação significativa entre esses dois parâmetros em populações de A. franciscana para os íons de sulfato e de cálcio, em contraste com A. persimilis. Estes achados sugerem que a quantidade heterocromatina interfásica modifica o tamanho nuclear em Artemia. Os nossos dados também indicam que a mudança na quantidade de heterocromatina interfásica está associada com a composição iónica das salinas. Este seria um fenómeno específico da espécie, cuja ocorrência pode estar envolvida na capacidade deste organismo sobreviver em tais ambientes.

Prenatal diagnosis of interchromosomal insertion of Y chromosome heterochromatin in a family

Interchromosomal insertion of Y chromosome heterochromatin in an autosome was identified in a fetus and a family. A fetal karyotype was analyzed as 46,XX,dup(7)(?q22q21.1) in a referred amniocentesis at 16 weeks of gestation for advanced maternal age. In the familial karyotype analyses for identification of der(7), the mother, the first daughter and the maternal grandmother showed the same der(7) as the fetus's. CBG-banding was positive at 7q22 region of der(7) that indicated inserted material was originated from heterochromatin. The origin of heterochromatic insertion region in der(7) of the fetus and the mother was found in Yq12 region by fluorescent in situ hybridization with a DYZ1 probe. In the specific analysis of Y chromosomal heterochromatic region of ins(7;Y) of the mother, 15 sequence tagged sites from Yp11.3 region including SRY to Yq11.223 region was not detected. Final karyotypes of the mother, the first daughter and the maternal grandmother were reported as 46,XX,der(7)ins(7;Y)(q21.3;q12q12). All female carriers of ins(7;Y) in the family showed normal phenotype and the mother and the maternal grandmother were fertile. A healthy girl was born at term. We report a rare case of familial interchromosomal insertion of Y chromosome heterochromatin detected only in female family members with normal phenotype that was diagnosed prenatally.

First cytogenetic record for a species of Otothyropsis Ribeiro, Carvalho & Melo, 2005 (Loricariidae, Hypoptopomatinae)

Hypoptopomatinae is a monophyletic subfamily that includes 147 species, distributed in 20 genera. Otothyropsis is a genus of Hypoptopomatinae, recently described. Here, we provided the first cytogenetic information of Otothyropsis . The specimens were collected from córrego Dourado, a small tributary of rio Iguatemi, which flows into rio Paraná. The specimens of Otothyropsis cf. polyodon were analyzed with respect to diploid number, C-Band and Ag-NOR patterns. The diploid number was 54 chromosomes, distributed in 18 metacentric, 28 submetacentric, and 8 subtelocentric chromosomes, with single Ag-NOR and conspicuous heterochromatic blocks on the short and long arms of the 24th pair of chromosomes. Our study highlights the conservation trend of the diploid number (2n=54) and fundamental number (FN = 108) among the species of Hypoptopomatinae. However, the karyotype formula (18m+28sm+8st) seems to be specific to O. cf. polyodon , considering the other Hypoptopomatinae species already analyzed.

Hypoptopomatinae é uma subfamília monofilética que inclui 147 espécies distribuídas em 20 gêneros, sendo Otothyropsis um gênero recentemente descrito. Aqui, fornecemos a primeira informação citogenética do gênero Otothyropsis . Espécimes foram coletados no córrego Dourado, um pequeno tributário do rio Iguatemi, o qual deságua no rio Paraná. Espécimes de Otothyropsis cf. polyodon foram analisados em relação ao número diploide e padrões de Banda-C e Ag-NOR. O número diploide foi de 54 cromossomos, distribuídos em 18 metacêntricos, 28 submetacêntricos e 8 subtelocêntricos, com Ag-NOR simples e blocos heterocromáticos evidentes no braços curto e longo do par de cromossomos 24. Nosso estudo destaca a tendência de conservação do número diploide (2n=54) e número fundamental (NF=108) entre as espécies de Hypoptopomatinae. Entretanto, a fórmula cariotípica (18m+28sm+8st) parece ser específica para O. cf. polyodon, considerando as outras espécies de Hypoptopomatinae já analisadas.

Description of Karyotype of Kerodon acrobata, an endemic rodent in Brazilian Cerrado / Primeira descrição do cariótipo de Kerodon acrobata, um roedor endêmico do semiárido brasileiro

Kerodon acrobata is a caviidae rodent endemic from Brazilian Cerrado. It was described only in 1997 and the data about it is very scarce. The aim of this work was to characterize the karyotype of K. acrobata. Giemsa staining, nucleolar organizer region (NOR) banding, C-positive heterochromatin banding and DAPI fluorescence were used in N metaphases of a specimen collected in Asa Branca Farm, in Aurora do Tocantins municipality, Tocantins state, Brazil. K. acrobata showed the same diploid number, fundamental number and chromosome morphology as Kerodon rupestris. But its NOR location and heterochromatin distribution patterns indicated a unique cytogenetic profile when compared to its sister species, emphasizing the evolutionary uniqueness of this relatively new and unknown species. This record also extends the distribution of this species northward.

Kerodon acrobata é um roedor caviídeo endêmico do Cerrado brasileiro. A espécie foi descrita apenas em 1997, e as informações sobre ela são muito escassas. O objetivo deste trabalho foi caracterizar o cariótipo K. acrobata. Coloração em Giemsa, bandeamento da região organizadora do nucléolo, bandeamento da heterocromatina C-positiva e fluorescência DAPI foram utilizados em N metáfases de um espécime coletado na fazenda Asa Branca, na cidade de Aurora do Tocantins, estado do Tocantins, Brasil. K. acrobata apresentou o mesmo número diplóide, número fundamental e morfologia dos cromossomos de Kerodon rupestris. Mas a localização de sua NOR e os padrões de distribuição de heterocromatina indicam um perfil citogenético único quando comparado com sua espécie irmã, enfatizando a singularidade evolutiva desta espécie pouco conhecida. Este registro também estende a distribuição desta espécie em direção ao norte.

The Heterochromatin-1 Phosphorylation Contributes to TPA-Induced AP-1 Expression

Activator protein-1 (AP-1) is an inducible transcription factor that contributes to the generation of chronic inflammation in response to oxidative and electrophilic stress. Previous studies have demonstrated that the PI3K/Akt1 pathway plays an important role in the transcriptional regulation of AP-1 expression. Although the histone post-translational modifications (PTMs) are assumed to affect the AP-1 transcriptional regulation by the PI3K/Akt pathway, the detailed mechanisms are completely unknown. In the present study, we show that heterochromatin 1 gamma (HP1gamma) plays a negative role in TPA-induced c-Jun and c-Fos expression. We show that TPA-induced Akt1 directly phosphorylates HP1gamma, abrogates its suppressive function and increases the interaction between histone H3 and 14-3-3epsilon. Collectively, these our data illustrate that the activation of PI3K/Akt pathway may play a permissive role in the recruitment of histone readers or other coactivators on the chromatin, thereby affecting the degree of AP-1 transcription.

Diversity and chromosomal evolution in the genus Ancistrus Kner, 1854 (Loricariidae: Ancistrini) from three hydrographic basins of Mato Grosso State, Brazil

Cytogenetic analyses were carried out in 117 specimens of seven species of the genus Ancistrus from three hydrographic in Mato Grosso State: Paraguay, Araguaia-Tocantins and Amazon basins. Conventional cytogenetic techniques were used to obtain mitotic chromosomes. C-banding was performed to detect heterochromatic regions and silver nitrate staining was used to identify nucleolar organizer regions (Ag-NORs). The counted and paired chromosomes revealed diploid numbers ranging from 2n = 40 to 2n = 54 with karyotype formulae varying from FN = 80 to FN = 86. Single marks in distinct chromosomes identified the nucleolar organizer regions. The constitutive heterochromatin was scarce in the diploid number from 2n = 50 to 2n = 54 and conspicuous blocks were observed in a single species with 2n = 40 chromosomes. These data corroborate the hypotheses of reduction of diploid number in species with derived features such as presence of sex chromosomes and polymorphisms, besides allowing inferences about the evolutionary mechanisms and the ancestor karyotype that favored the diversification of this important genus in the tribe Ancistrini.

Foram realizadas análises citogenéticas de 117 espécimes do gênero Ancistrus de três bacias hidrográficas do estado de Mato Grosso: Paraguai, Araguaia-Tocantins e Amazônica, utilizando as técnicas de citogenética convencional para obtenção de cromossomos mitóticos, visualização de regiões heterocromáticas e regiões organizadoras de nucléolos. Os cromossomos pareados revelaram uma variação no número diploide de 2n = 40 a 2n = 54 e número fundamental de NF = 80 a NF = 86. As regiões organizadoras de nucléolos foram evidenciadas em um único par de cromossomos para todas as espécies e a heterocromatina é escassa nas espécies com números diploides elevados (2n = 50 a 2n = 54). Os blocos heterocromáticos mais evidentes foram observados nos pares portadores das AgRONs e em cromossomos da espécie com 2n = 40. Estes dados contribuem para a hipótese de redução do número diploide nas espécies que apresentam polimorfismos cromossômicos e cromossomos sexuais, além de contribuir para inferências sobre os mecanismos de evolução cariotípica que favoreceu a diversificação do gênero Ancistrus, o mais representativo na tribo Ancistrini.

Interplay between Epigenetics and Genetics in Cancer

Genomic instability, which occurs through both genetic mechanisms (underlying inheritable phenotypic variations caused by DNA sequence-dependent alterations, such as mutation, deletion, insertion, inversion, translocation, and chromosomal aneuploidy) and epigenomic aberrations (underlying inheritable phenotypic variations caused by DNA sequence-independent alterations caused by a change of chromatin structure, such as DNA methylation and histone modifications), is known to promote tumorigenesis and tumor progression. Mechanisms involve both genomic instability and epigenomic aberrations that lose or gain the function of genes that impinge on tumor suppression/prevention or oncogenesis. Growing evidence points to an epigenome-wide disruption that involves large-scale DNA hypomethylation but specific hypermethylation of tumor suppressor genes, large blocks of aberrant histone modifications, and abnormal miRNA expression profile. Emerging molecular details regarding the modulation of these epigenetic events in cancer are used to illustrate the alterations of epigenetic molecules, and their consequent malfunctions could contribute to cancer biology. More recently, intriguing evidence supporting that genetic and epigenetic mechanisms are not separate events in cancer has been emerging; they intertwine and take advantage of each other during tumorigenesis. In addition, we discuss the collusion between epigenetics and genetics mediated by heterochromatin protein 1, a major component of heterochromatin, in order to maintain genome integrity.

Karyotype differentiation and cytotaxonomic considerations in species of Serrasalmidae (Characiformes) from the Amazon basin

Six species of Serrasalmidae from the central Amazon, representatives of the genera Serrasalmus (S. elongatus, S. maculatus, S. cf. rhombeus, and S. rhombeus), Pygocentrus (P. nattereri), and Colossoma (C. macropomum), were analyzed regarding the distribution of the Ag-NORs, C-positive heterochromatin and 18S and 5S rRNA genes on the chromosomes. All specimens had 2n = 60 chromosomes, except S. cf. rhombeus, with 2n = 58, and C. macropomum with 2n = 54 chromosomes. The Ag-NORs were multiple and located on the short arms of subtelo-acrocentric chromosomes in all Serrasalmus species and in P. nattereri, but were found on metacentric chromosomes in C. macropomum. The 18S rDNA sites were usually coincident with Ag-NORs, although some species had a higher number and/or a distinct localization of these sites. C-positive heterochromatin was preferentially situated in centromeric regions, remarkably on metacentric pair number 7 in all Serrasalmus species and number 3 in P. nattereri, which beared a conspicuous proximal C-band on the long arms. The 5S rDNA sites were detected in a single chromosomal pair in all species. In Serrasalmus and P. nattereri, this pair was the number 7 and 3, respectively, thereby revealing its co-localization with the conspicuous heterochromatic band. However, in C. macropomum, only one homologue (probably belonging to pair number 12) exhibited 5S rDNA sites on the short arms, close to the centromere. The present data revealed reliable cytotaxonomic markers, enabling the evaluation of karyotype differentiation and interrelationships among Serrasalmidae, as well as the probable occurrence of a species complex in S. rhombeus.

Seis espécies de Serrasalmidae da Amazônia central, representantes dos gêneros Serrasalmus (S. elongatus, S. maculatus, S. cf. rhombeus e S. rhombeus ), Pygocentrus (P. nattereri) e Colossoma (C. macropomum), foram analisadas quanto à distribuição das Ag-RONs, heterocromatina C-positiva e dos genes de RNAr 18S e 5S nos cromossomos. Todos os espécimes apresentaram 2n = 60 cromossomos, exceto S. cf. rhombeus, com 2n = 58, e C. macropomum com 2n = 54 cromossomos. As Ag-RONs foram múltiplas e localizadas nos braços curtos de cromossomos subtelo-acrocêntricos em todas as espécies de Serrasalmus e em P. nattereri, mas foram encontrados em cromossomos metacêntricos em C. macropomum. Os sítios de DNAr 18S, foram geralmente coincidentes com as Ag-RONs, embora algumas espécies tenham apresentado um maior número e/ou uma localização distinta desses sítios. A heterocromatina C-positiva foi preferencialmente encontrada como uma conspícua banda proximal no par metacêntrico número 7 em todas as espécies de Serrasalmus e número 3 em P. nattereri. Os sítios de DNAr 5S foram detectados em um único par cromossômico nas seis espécies sendo que nas espécies de Serrasalmus, este par foi o de número 7 e em P. nattereri o de número 3, colocalizados com bandas heterocromáticas conspícuas. No entanto, em C. macropomum, apenas um homólogo (provavelmente pertencente ao par número 12) apresentou sítios de DNAr 5S nos braços curtos, próximos ao centrômero. Os dados apresentados revelaram confiáveis marcadores citotaxonômicos, permitindo a avaliação da diferenciação cariotípica, e as inter-relações entre Serrasalmidae, bem como a provável ocorrência de um complexo de espécies em S. rhombeus.

Algunas certeza entre las tantas preguntas de os últimos diez años acerca dell genoma de los primaess / Some Certainties Among the Manyquestions of the Last 10 Years about the Primate Genome

En el año 2000 se presentó lo que se dio en llamar nuestro libro de la vida, el primer borrador del genoma humano. Aquello generó grandes expectativas por sus potenciales en beneficio de las ciencias biológicas. ¿Qué ha sucedido diez años después? Se conoce el número de genes que forman parte de nuestro genoma y se determinó la función de algunos de ellos. Se conocen las secuencias de tres genomas completos de mamíferos, Mus musculus, Pan troglodytes y Sus scrofa y genomas completos o borradores de otros numerosos eucariota (otros animales, plantas, hongos y protistas) y procariota (Archea y Bacterias), ver: http://ncbi.nlm.nih.gov/genomes. Sin embargo, el estudio del genoma no se limita a la mera descripción de las secuencias que lo componen. Las respuestas que se elaboren tendrán enfoques muy diversos, desde evolución y conservación de la biodiversidad hasta terapia génica y transformación maligna, donde el estudio de las particularidades individuales y poblacionales requiere fuentes de información tanto pasadas como actuales sobre estos genomas en estudio. Así, los avances en ciencia siempre son provisorios y por tanto, plausible de continuarse, completarse e incluso reinterpretarse ya que, conforme avanzamos en el conocimiento van surgiendo nuevos interrogantes.

In 2000 the first draft of the human genome, what became known as our book of life, was presented. It generated high expectations for its potential applications to the benefit of the biological sciences. What happened 10 years later? We know how many genes we have in our genome and analyzed the function of some of them. Nowadays, we know the sequences of 3 mammalians genomes: M. musculus, P. troglodytes y S. scrofa and the genomes or borradores from other eucaryotes (other animals, plants, fungi and protists) and procaryotes (Archea and Bacterias). However, the study of the genome is not merely a description of the sequences that compose it. The answers provided will have very different approaches from evolution and conservation of biodiversity to gene therapy and malignant transformation, where the study of individual and population particularities requires sources of information both past and present on these genomes under survey. Thus, advances in science are always provisional and therefore liable to be continued, completed and even reinterpreted as we advance in knowledge, new questions arise.