Study on changes of proliferation, migration and invasion abilities of radiation-induced polyploid colon cancer SW1116 cells and their progeny and the related mechanisms / 肿瘤研究与临床

Objective:To investigate the characteristics related to proliferation, migration and invasion of radiation-induced polyploid colon cancer SW1116 cells and their progeny.Methods:Colon cancer SW1116 cells were conventionally cultured in Leibovitz's L-15 medium containing 10% fetal bovine serum. SW1116 cells at logarithmic growth stage were irradiated with 7 Gy X-ray, and the morphological changes of the cells were observed by inverted microscope on days 3, 5, 10 and 19 after radiation induction. According to the morphological changes of the cells, the cells at day 3 after radiation induction were labeled as polyploid giant cancer cell (PGCC) group, and the cells at day 19 were recorded as PGCC progeny group. SW1116 cells without radiation induction were used as control group. Flow cytometry was used to detect cell ploidy in the control, PGCC and PGCC progeny groups, CCK-8 assay was used to detect the proliferation ability of the three groups, cell migration and invasion abilities of the three groups were detected by cell scratch assay and Transwell assay, and Western blotting was used to detect the expressions of cell cycle and proliferation-related proteins and epithelial-mesenchymal transition (EMT) marker N-cadherin (N-cad) in the three groups.Results:The volume of SW1116 cells gradually became larger on days 3, 5 and 10 after radiation induction, and returned to normal on day 19. The proportions of polyploid (DNA content >4N) cell subsets in the control group, PGCC group and PGCC progeny group were (2.3±1.1)%, (23.1±8.1)% and (3.2±0.5)%, the difference was statistically significant ( F = 18.52, P < 0.05), and the proportion of polyploid cell subpopulations in the PGCC group was higher than that in the control group ( t = 5.38, P < 0.01), but the differences between the PGCC progeny group and the control group were not statistically significant ( t = 0.22, P > 0.05). After 72 h of culture, the cell proliferation rates of the control, PGCC and PGCC progeny groups were (100.0±4.1)%, (73.5±0.7)% and (123.9±3.5)%, and the difference was statistically significant ( F = 190.27, P < 0.001). After 48 h of cell scratching, the scratch healing rates in the control, PGCC and PGCC progeny groups were (38.0±2.7)%, (41.5±4.0)% and (63.7±4.2)%, and the difference was statistically significant ( F = 43.05, P < 0.001). After 24 h of culture, the number of invasive cells in the control, PGCC and PGCC progeny groups was 12.9±1.2, 3.4±0.6 and 23.7±1.5, and the difference was statistically significant ( F = 63.64, P < 0.001). The expression levels of cell cycle-related proteins P-cdc25c, cdc25c and cdc2 in the PGCC group were lower than those in the control group (all P < 0.05), and the expression levels of transcription factor-related proteins E2F-2, E2F-3 and EMT marker N-cad were downregulated compared with the control group (all P < 0.05); the expression levels of P-cdc25c, cdc25c, cdc2, E2F-2, E2F-3 and N-cad proteins in the PGCC progeny group were higher than those in the control group (all P < 0.05). Conclusions:Radiation can induce colon cancer SW1116 cells to produce polyploid, which may then generate daughter cells through asymmetric mitosis and gain new life, and then promote the recurrence and metastasis of colon cancer.

Cellular polyploidy in organ homeostasis and regeneration

Polyploid cells, which contain more than one set of chromosome pairs, are very common in nature. Polyploidy can provide cells with several potential benefits over their diploid counterparts, including an increase in cell size, contributing to organ growth and tissue homeostasis, and improving cellular robustness via increased tolerance to genomic stress and apoptotic signals. Here, we focus on why polyploidy in the cell occurs and which stress responses and molecular signals trigger cells to become polyploid. Moreover, we discuss its crucial roles in cell growth and tissue regeneration in the heart, liver, and other tissues.

Cytogenetics of Chilean land plants (Embryophyta): state-of-the-art and prospects / CItogenética de plantas terrestres Chilenas (Embryophyta): estado del arte y perspectivas

ABSTRACT Chile is located in the south-western region of South America along the Pacific Ocean and contributes to the worldwide flora with ca. 6,120 species of Bryophyta, Pteridophyta, Pinophyta, Gnetophyta, and Magnoliophyta (1.9% of worldwide total species), exhibiting high endemism across all plant divisions. Little is known about the genetic diversity of Chilean land plants worldwide, including their cytogenetic and molecular characteristics. In 2012 we published the first state-of-the-art review in Cytogenetics of Chilean Angiosperms. The article gathered 78 publications from 1924 to 2010 accounting for approximately 139 species (2.8% of total Chilean species). The aim of this paper was to review the advances in cytogenetic studies of Chilean land plants, reporting additional cytogenetic data for species of four botanical divisions until 2020. Cytogenetic data were searched in the CPCD (Chilean Plants Cytogenetic Database). In total, we found 180 publications from both Chilean and foreign researchers. To date, cytogenetic data have been reported for 499 Chilean land plant species (8.2% of total) belonging to 244 genera and 117 families. In this context, the 2001-2020 period has been among the most productive regarding publications, with 74 available reports that include 163 additional species. Based on chromosome numbers, angiosperms and bryophytes registered the greatest diversity with 55 and 29 different 2n, respectively; both divisions having the greatest number of studied species. Given the importance of increasing information on Chilean land plants, it is expected that more publications will contribute to the knowledge of their cytogenetic diversity in the near future.

RESUMEN Chile está ubicado en la región suroeste de América del Sur a lo largo del Océano Pacífico y contribuye a la flora mundial con aproximadamente 6.120 especies de Bryophyta, Pteridophyta, Pinophyta, Gnetophyta y Magnoliophyta (1,9% del total de especies en todo el mundo), que presentan un alto endemismo en todas las divisiones de plantas. Poco se conoce sobre la diversidad genética de las plantas terrestres chilenas en todo el mundo, incluidas sus características citogenéticas y moleculares. En 2012 publicamos la primera revisión sobre el estado del arte en Citogenética de Angiospermas Chilenas. El artículo reunió 78 publicaciones desde 1924 hasta 2010, que representan aproximadamente 139 especies (2,8% del total de especies chilenas). El objetivo de este trabajo fue revisar los avances en estudios citogenéticos de plantas terrestres chilenas, reportando datos citogenéticos adicionales para especies de cuatro divisiones botánicas hasta el 2020. Los datos citogenéticos se buscaron en el CPCD (Base de Datos Citogenéticos de Plantas Chilenas). En total, encontramos 180 publicaciones sobre citogenética de plantas terrestres chilenas, con datos citogenéticos para 499 especies (8,2% del total) pertenecientes a 244 géneros y 117 familias. En este contexto, el período 2001-2020 ha sido uno de los más productivos en cuanto a publicaciones, con 74 artículos disponibles que incluyen 163 especies adicionales. Basado en los números cromosómicos, angiospermas y briófitos registran la mayor diversidad, con 55 y 29 2n diferentes, respectivamente; ambas divisiones tienen también el mayor número de especies estudiadas. Dada la importancia de incrementar la información sobre plantas terrestres chilenas, se espera que más publicaciones contribuyan al conocimiento de su diversidad citogenética en un futuro próximo.

Evolutionary dynamics of autopolyploids in natural populations: the case of Turnera sidoides complex / Dinámica evolutiva de autopoliploides en poblaciones naturales: el caso del complejo Turnera sidoides

ABSTRACT Turnera sidoides (x=7) is one of the few well-studied South American autopolyploid complexes. Since polyploidy has played a prominent role within this complex, ongoing studies in T. sidoides focus on understanding the mechanisms involved in the origin and the establishment of polyploids using integrative approaches. This paper synthesises the results of more than 20 years of research on this topic. Cytogenetics analysis provided evidences for the production of unreduced male and female gametes, supporting the hypothesis of bilateral sexual polyploidization as the mechanism of origin of polyploids in T. sidoides. The finding of viable triploids suggested that unilateral sexual polyploidization could also be an important mechanism for the origin of tetraploids in T. sidoides. The occurrence of plants continuously forming many unreduced gametes would play a key role in the establishment of neopolyploids in natural populations. Also, the higher number of propagules that tetraploids contribute to subsequent generations, the ability to multiply asexually by rhizomes, and the occurrence of occasional cases of self-compatibility and successful illegitimate crosses in polyploids increase the likelihood that a low frequency of neopolyploids can be maintained in natural populations of T. sidoides. In addition, integration of cytogeographic and genetic divergence data together with past niche modelling provided further insights supporting the hypothesis that historical climatic and geomorphological events provided favourable conditions for the establishment of autopolyploids, with the wider distribution of tetraploids of T. sidoides being the result of their range expansion.

RESUMEN Turnera sidoides (x=7) es uno de los pocos complejos autopoliploides sudamericanos bien estudiados. Como la poliploidía ha tenido un papel destacado en el complejo, los estudios en curso en T. sidoides se centraron en la comprensión de los mecanismos implicados en el origen y el establecimiento de los poliploides mediante diferentes enfoques. En este trabajo se sintetizan los resultados de más de 20 años de investigación sobre este tema. El análisis citogenético proporcionó evidencias de la producción de gametos masculinos y femeninos no reducidos, sustentando la hipótesis de la poliploidización sexual bilateral como mecanismo de origen de los poliploides en T. sidoides. Sin embargo, el hallazgo de triploides fértiles sugirió que la poliploidización sexual unilateral también sería un mecanismo importante de origen de tetraploides en T. sidoides. La ocurrencia de plantas que forman continuamente gametos no reducidos desempeñaría un papel clave en el establecimiento de neopoliploides. Además, el mayor número de propágulos que los tetraploides aportan a las siguientes generaciones, la capacidad de multiplicación asexual por rizomas y los casos ocasionales de autocompatibilidad y cruzamientos ilegítimos exitosos aumentarían la probabilidad de que se mantenga una baja frecuencia de neopoliploides en las poblaciones naturales de T. sidoides. Asimismo, la integración de datos citogeográficos y de divergencia genética junto con el modelado de nicho en el pasado aportó información que sustenta la hipótesis de que los eventos climáticos y geomorfológicos históricos proporcionaron las condiciones favorables para el establecimiento y expansión de los tetraploides de T. sidoides.

Variedades de cultivo de líquido amniótico para el diagnóstico in vitro de poliploidías / Amniotic fluid culture varietys for poliploydies in vitro diagnosis

RESUMEN Fundamento: El cultivo celular permite el análisis directo de las células vivas mediante un microscopio. El estudio de las células contenidas en el líquido amniótico, mediante técnicas de cultivo, detecta anomalías en número y morfología de los cromosomas, que pueden relacionarse con enfermedades genéticas. Objetivo: Caracterizar las variedades de cultivo de líquido amniótico para el diagnóstico in vitro de poliploidías. Metodología: Se realizó un estudio descriptivo transversal, en el Centro Provincial de Genética Médica de Camagüey, en el periodo de noviembre de 2016 a abril de 2018.La población de estudio estuvo constituida por 1571 muestras útiles de líquido amniótico obtenidas por amniocentesis, en gestantes en el segundo trimestre, evaluadas en consulta multidisciplinaria con criterios clínicos de estudios cromosómicos según lo establecido en el diagnóstico prenatal citogenético, previo consentimiento informado. Se utilizaron 20 mL de líquido amniótico para la siembra de células fetales, y se aplicaron tres variantes de cultivo abierto (directo, centrifugado y expandido). Se determinó el complemento cromosómico en cada variedad. Resultados: Predominó el complemento cromosómico normal. Las tetraploidías prevalecieron en el cultivo expandido. El índice mitótico fue similar en las tres variedades de cultivo y el cultivo directo tuvo el más bajo índice de poliploidías. Conclusiones: El cariotipo normal fue predominante. Las tetrapolidías fueron las alteraciones más frecuentes y prevalecieron en el cultivo expandido. En el cultivo directo se presentó el más bajo índice de errores inducidos in vitro.

ABSTRACT Background: Cell culture allows direct analysis of live cells under a microscope. The cell study contained in amniotic fluid, by culture techniques, detects abnormalities in chromosome number and morphology, which can be related to genetic diseases. Objective: To describe amniotic fluid culture strains for the in vitro diagnosis of polyploidy. Methodology: A cross-sectional descriptive study was conducted at the Camagüey Provincial Center of Medical Genetics, from November 2016 to April 2018.The study population consisted of 1571 useful amniotic fluid samples obtained by amniocentesis, in pregnant women in the second trimester, evaluated by multidisciplinary discussion with clinical criteria for chromosomal studies as established in the cytogenetic prenatal diagnosis, prior informed consent. 20 mL of amniotic fluid were used for fetal cell seeding, and three open culture strains (direct, centrifuged and expanded) were applied. Chromosomal complement was determined in each variety. Results: Normal chromosome complement was predominant. Tetraploidy prevailed in the expanded culture. The mitotic index was similar in the three culture strains and the direct culture had the lowest polyploidy index. Conclusions: Normal karyotype was predominant. Tetraploidy were the most frequent modifications and prevailed in the expanded culture. Direct culture had the lowest rate of the in vitro induced errors.

Paleo-polyploidization in Lycophytes / 基因组蛋白质组与生物信息学报·英文版

Lycophytes and seed plants constitute the typical vascular plants. Lycophytes have been thought to have no paleo-polyploidization although the event is known to be critical for the fast expansion of seed plants. Here, genomic analyses including the homologous gene dot plot analysis detected multiple paleo-polyploidization events, with one occurring approximately 13-15 million years ago (MYA) and another about 125-142 MYA, during the evolution of the genome of Selaginella moellendorffii, a model lycophyte. In addition, comparative analysis of reconstructed ancestral genomes of lycophytes and angiosperms suggested that lycophytes were affected by more paleo-polyploidization events than seed plants. Results from the present genomic analyses indicate that paleo-polyploidization has contributed to the successful establishment of both lineages-lycophytes and seed plants-of vascular plants.

Inducción de poliploidía con clochicina en vitroplantas de Aloe vera (L.) / Induction of polyploidy with colchicine in vitroplants of Aloe vera (L.)

RESUMEN La inducción artificial de la poliploidía es una técnica de fitomejoramiento empleado en plantas de interés medicinal. Sin embargo, pocas especies del género Aloe han sido sometidas a este tratamiento. El objetivo de esta investigación fue estandarizar la técnica de inducción de poliploidía en vitroplantas de Aloe vera (L.). Se realizó un diseño experimental con dos grupos (control y experi mental) a los cuales se les aplicó un estudio citogenético pre y postratamiento por tres generaciones consecutivas. Se evaluaron tres concentraciones de colchicina (0,05; 0,10 y 0,15%) y dos tiempos de exposición (48 y 72 horas). Las vitroplantas controles mantenidas en agua destilada (sin colchicina) por 48 y 72 (T y T2 respectivamente) y las tratadas con solución de colchicina al 0,05% por 48 y 72 horas (T3 y T4 respectivamente), presentaron pocos cambios citogenéticos, siendo la mayoría de sus células diploides. Las plantas tratadas con solución de colchicina a 0,10% por 48 y 72 horas (T5 y T6 respectivamente), lograron la duplica ción cromosómica en más del 50% del tejido. Las tratadas con una concentración de 0,15% por 48 horas (T7) mostraron tejido quimérico con un alto predominio de células poliploides y al aumentar el tiempo de exposición a 72 horas (T8), todas las células fueron poliploides, pero el desarrollo de estas plantas in vitro, fue anormal y con tejido necrótico. Las plantas con T5, se desarrolla ron mejor que con el T6. Se recomienda el uso de la colchicina a una concentración de 0,10% por 48 horas para obtener vitro plantas poliploides en A. vera.

ABSTRACT The artificial induction of polyploidy is a plant breeding technique used in plants of medicinal interest. However, few species of the genus Aloe have been subjected to this treatment. The objective of this research is to standardize the induction technique of polyploidy in vitroplants of Aloe vera (L.). An experimental design was performed with two groups (control and experimental), to which a cytogenetic study was applied pre and post treatment for three consecutive generations. Three concentrations of colchi cine (0.05, 0.10 and 0.15%) and two exposure times (48 and 72 hours) were considered. The control vitroplants kept in distilled water (without colchicine) for 48 and 72 hours (T1 and T2 respectively) and those treated with colchicine's solution at 0.05% for 48 and 72 hours (T3 and T4 respectively), presented few cytogenetic changes, being diploid most of their cells. Plants treated with 0.10% colchicine's solution for 48 and 72 hours (T5 and T6 respectively) achieved chromosomal duplication in more than the 50% of the tissue. Those treated with a concentration of 0.15% for 48 hours (T7) showed chimeric tissue with a high predominance of polyploid cells, and by increasing the exposure time to 72 hours (T8) all cells were polyploid, but the development of these plants in vitro were abnormal and with necrotic tissue. Plants with T5, developed better than with T6. The use of colchicine at a concen tration of 0.10% for 48 hours is recommended to obtain polyploid vitroplants in A. vera.

Cytological and genome size data analyzed in a phylogenetic frame: Evolutionary implications concerning Sisyrinchium taxa (Iridaceae: Iridoideae)

Abstract Sisyrinchium is the largest genus of Iridaceae in the Americas and has the greatest amount of cytological data available. This study aimed at investigating how genomes evolved in this genus. Chromosome number, genome size and altitude from species of sect. Viperella were analyzed in a phylogenetic context. Meiotic and pollen analyses were performed to assess reproductive success of natural populations, especially from those polyploid taxa. Character optimizations revealed that the common ancestor of sect. Viperella was probably diploid (2n = 2x =18) with two subsequent polyplodization events. Total DNA content (2C) varied considerably across the phylogeny with larger genomes detected mainly in polyploid species. Altitude also varied across the phylogeny, however no significant relationship was found between DNA content changes and altitude in our data set. All taxa presented regular meiosis and pollen viability (> 87%), except for S. sp. nov. aff. alatum (22.70%), suggesting a recent hybrid origin. Chromosome number is mostly constant within this section and polyploidy is the only source of modification. Although 2C varied considerably among the 20 taxa investigated, the diversity observed cannot be attributed only to polyploidy events because large variations of DNA content were also observed among diploids.

Expression and clinical significance of MCL-1 and FBW7 proteins in breast cancer polyploid induced by spindle poisons / 天津医药

Objective To investigate the expression and clinical significance of myeloid cell leukemia-1 (MCL-1) and F-box and WD repeat domain-containing 7 (FBW7) in breast cancer polyploid induced by spindle poisons. Methods (1) Nocodazole spindle poison was used to treat breast cancer cell MDA-MB-231. The morphological changes of cells were ob?served under microscope, and cells were harvested in 0, 6, 12, 24, 48 and 72 h. The cell cycle and DNA-ploidy changes were examined by flow cytometry. The expressions of FBW7 and MCL-1 proteins were detected by Western blot assay. (2) A multikinase inhibitor (Sorafenib) with Nocodazole or Taxol was used to treat MDA-MB-231 cells. MCL-1 protein expression was detected by Western blot assay after 48 h treatment. The cell cycle and DNA-ploidy changes were examined by flow cy?tometry after 48 h treatment. MTT method was used to observe cell proliferation after 48 and 72 h treatment. Results (1)Af?ter treatment by Nocodazole, polyploid characteristics of large cell size and nucleus were appeared. The percentages of octa?ploid were (0.8±0.2)%, (8.5±2.3)%, (7.8±2.0)%, (9.9±0.9)%, (28.2±0.8)%and (35.1±4.9)%after 0, 6, 12, 24, 48 and 72 h treatment, showing the increasing trend in turn (P<0.001). The number of polyploidy (tetraploid and octaploid) cells was as high as (97.6±0.7)%after 48 h treatment. The expression level of FBW7 protein was decreased significantly but the expres?sion of MCL-1 protein was increased significantly after 48 h treatment. (2) After 48 h treatment, the expression level of MCL-1 protein, polyploidy percentage and cell proliferation decreased significantly in Nocodazole+Sorafenib group and Taxol+Sorafenib group compared with those of Nocodazole group and Taxol group (P<0.05). Conclusion The lower expression of FBW7 protein and over-expression of MCL-1 protein are correlated with the formation of breast cancer polyploidy. Sorafenib can reduce polyploid tumor cells by inhibiting MCL-1 protein expression.

Lavandula L. - aplicação da cultura in vitro à produção de óleos essenciais e seu potencial económico em Portugal / Lavandula L. - application of in vitro cultivation for the essential oils production and their economic potential in Portugal

RESUMO Os óleos essenciais são metabolitos secundários que possuem diversas propriedades com elevado interesse, nomeadamente as biológicas. Estas propriedades englobam todas as atividades que esta mistura de compostos voláteis (principalmente monoterpenos, sesquiterpenos e fenilpropanóides) exerce sobre os seres humanos, animais e outras plantas. Os óleos essenciais apresentam grande valor económico, sendo os do género Lavandula dos mais comercializados e estudados devido à sua aplicabilidade industrial e propriedades terapêuticas As lavandulas são colhidas na natureza ou propagadas por técnicas convencionais, nomeadamente por estacaria. Mais recentemente, protocolos de micropropagação foram desenvolvidos para algumas espécies, permitindo a produção de plantas em larga escala disponíveis em qualquer período do ano e sem comprometer a biodiversidade das espécies. O desenvolvimento de plantas tetraplóides capazes de aumentar a produção de óleo essencial nas suas flores é outro meio eficaz para aumentar potencialmente o valor das espécies de Lavandula. Em Portugal existem 5 espécies nativas do género Lavandula, amplamente distribuídas pelo país. Contudo, o seu potencial industrial permanece praticamente inexplorado e em termos de mercado o seu reconhecimento é muito reduzido. Trabalhos recentes, baseados na avaliação das propriedades biológicas dos óleos essenciais e a forma como eles podem exercer os seus efeitos contribuíram para a valorização do potencial económico das lavandulas em Portugal. Esta revisão tenta dar uma visão geral de que forma a aplicação das culturas in vitro pode levar a uma maior produção de óleos essenciais em Lavandula spp., dando especial ênfase às lavandulas nativas de Portugal.

ABSTRACT Essential oils are secondary metabolites plants and, among other features, they own several biological properties. The term “biological” includes all activities that these mixtures of volatile compounds (mainly monoterpenes, sesquiterpenes, and phenylpropanoids) maintain on humans, animals and other plants. Essential oils have great economic value, being the genus Lavandula one of the most commercialized and studied type due to its dits industrial applicability and therapeutic properties. Lavenders are harvested in the nature or propagated using traditional methodologies. More recently micropropagation protocols have been developed for several Lavandula species allowing a production of a high amount of plants available at any time of the year without compromising the biodiversity of the species. Another efficient way to potentially increase the value of Lavandula species is through the development of tetraploid plants, capable of raising the production of essential oils in flowers. In Portugal, there are 5 native species of the genus Lavandula, widely distributed throughout the country. However, native Portuguese lavenders remain mainly unexplored and have received poor recognition in markets. A recent study was carried out in order to evaluate the biological properties of the oils and also to understand how they may exercise their effects, contributing to enhance the economic potential of lavandulas in Portugal. This review attempts to provide an overview about the application of in vitrocultivations for the production of essential oils in Lavandulaspp., with special emphasis on native lavandulas of Portugal.

Genetic Instability and Herpes Simplex Virus.

Although inhibitory mechanisms that safeguard cells against DNA damages occur in all cells, genetic instability is widely present throughout living world. Some well known viruses cause alterations in host genome, leading to the formation of malignant transformations. Throughout this review we discuss some forms of instabilities caused by herpes simplex virus. Herpes simplex virus may induce chromosomal instabilities by various mechanisms, such as by formation of syncytium or ICP0-induced degradation of constitutive centromere proteins as well as may induce accumulation of point mutations by means of oxidative stress in neurons. We believe that further investigation of the ability of herpes simplex virus to cause genetic instability may help us to increase our understanding about the nature of this phenomenon.

Chromosome characterization and variability in some Iridaceae from Northeastern Brazil

The chromosomes of 15 species of Iridaceae of the genera Alophia, Cipura, Eleutherine, Neomarica and Trimezia (subfamily Iridoideae) were examined after conventional Giemsa staining. The karyotypes of Alophia drummondii (2n = 14+1B, 28, 42 and 56), Cipura paludosa (2n = 14), C. xanthomelas (2n = 28) and Eleutherine bulbosa (2n = 12) were asymmetric; Neomarica candida, N. caerulea, N. humilis, N. glauca, N. gracilis, N. northiana and Neomarica sp. (2n = 18); N. cf. paradoxa (2n = 28), Trimezia fosteriana (2n = 52), T. martinicensis (2n = 54) and T. connata (2n = 82) were all generally symmetric. New diploid numbers of 2n = 56 for Alophia drummondii, 2n = 18 for N. candida, N. humilis, N. glauca, and N. gracilis, 2n = 28 for N. cf. paradoxa, and 2n = 82 for T. connata are reported. The karyotypic evolution of the studied species is discussed.

Cytogenetic aberrations in primary cell cultures of the ovarian surface epithelium / Aberraciones citogenéticas en cultivos primarios del epitelio superficial del ovario

Our objective was to determine the presence of chromosomal abnormalities in primary cultures of ovarian surface epithelial cells in women of different ages with no history of cancer. Throughout conventional cytogenetic techniques, we analyzed chromosome spreads of cultured ovarian epithelial cells from 10 donors who were 50 or more years old (B) and 16 controls between 20 and 49 years old (A), belonging to the mestizo population in Bogota DC, Colombia. Of the 26 cultures that were analyzed in passage 1, 61.5% had an abnormal chromosome complement (62.5% in A, and 60% in B). Abnormalities included polyploidies, endoduplications and monosomies. Deletions in chromosomes 3 and 11 were found in just one metaphase. None of the samples showed weaknesses or breakpoints. After transforming and applying the exact student’s t-test for variance heterogeneity, we found significant differences in the frequency of metaphases, that were higher in A than in B (p=0.05), and in the frequency of polyploidies, which were higher in B than in A (p=0.044). Through the application of the Mann-Whitney test, we determined that the frequency of endoduplications was higher in A than in B (p=0.126), without reaching significant differences. There were no significant differences in the frequency of monosomies. The level of significance was set at p £ 0.05. Taking into account that polyploidization is a marker of chromosomal instability and that the risk of cancer arising from the ovarian surface epithelium augments substantially after menopause, the increase in the frequency of age-associated polyploidies could be used as a predictor of ovarian cancer in women from an ethnically homogeneous population as the mestizo one in Bogota DC.

El objetivo del presente trabajo fue determinar la presencia de anormalidades cromosómicas en cultivos primarios de células del epitelio superficial ovárico en mujeres de diferentes edades, sin antecedentes de cáncer. Mediante técnicas de citogenética convencional fueron analizados extendidos de células epiteliales ováricas histológicamente normales, provenientes de cultivos primarios de 10 donantes de 50 o más años (B) y de 16 donantes entre 20 y 49 años que se utilizaron como grupo control (A), pertenecientes a la población mestiza de Bogotá DC, Colombia. De 26 cultivos examinados en pase 1, 61,5% presentó complemento cromosómico anormal, 62,5% en A y 60% en B. Las anomalías numéricas halladas, todas en mosaico, incluyeron poliploidías, endoduplicaciones y monosomías. En una única célula en metafase de un cultivo, se presentaron deleciones en los cromosomas 3 y 11. Ninguna muestra presentó fragilidades o roturas. Previa aplicación de transformaciones, con la prueba exacta t-student para varianzas heterogéneas, se encontraron diferencias significativas en la frecuencia de células con metafase normal, mayor en A que en B (p=0,05) y en la de poliploidías, mayor en B que en A (p=0,044). Con la prueba exacta de Mann-Whitney se determinó que la frecuencia de endoduplicaciones en A fue mayor que en B (p=0,126), sin alcanzar diferencias significativas y que no hubo diferencias significativas en la frecuencia de monosomías. El nivel de significación fue p £ 0,05. Si se tiene en cuenta que la poliploidización es un marcador de inestabilidad cromosómica y, que además, el riesgo de aparición de cáncer derivado del epitelio superficial del ovario aumenta sustancialmente después de la menopausia, el incremento en la frecuencia de poliploidías asociado con la edad podría ser utilizado como predictor de cáncer ovárico en mujeres de una población étnicamente homogénea como la población mestiza de Bogotá DC.

A new approach for obtaining rapid uniformity in rice (Oryza sativa L. ) via a 3x x 2x cross

A triploid (2n = 3x = 36) rice plant was obtained by screening a twin seedling population in which each seed germinated to two or three sprouts that were then crossed with diploid plants. One diploid plant was chosen among the various F1 progenies and developed into an F2 population via self-pollination. Compared with the control variety Shanyou 63, this F2 population had a stable agronomical performance in field trials, as confirmed by the F-test. The stability of the F2 population was further substantiated by molecular analysis with simple sequence repeat markers. Specifically, of 160 markers assayed, 37 (covering all 12 chromosomes) were polymorphic between the parental lines. Testing the F1 hybrid individually with these markers showed that each PCR product had only a single band instead of two bands from each parent. The bands were identical to either maternal (23 markers) or paternal (eight markers) bands or distinct from both parents (six markers). The amplified bands of all 60 randomly selected F2 plants were uniform and identical to those of the F1 hybrid. These results suggest that the F1 plant is a non-segregating hybrid and that a stable F2 population was obtained. This novel system provides an efficient means for shortening the cycle of hybrid rice seed production.

Chromosome studies in Orchidaceae from Argentina

The center of diversity of Argentinean orchids is in the northeast region of the country. Chromosome numbers and karyotype features of 43 species belonging to 28 genera are presented here. Five chromosome records are the first ones at the genus level; these taxa are Aspidogyne kuckzinskii (2n = 42), Eurystyles actinosophila (2n = 56), Skeptrostachys paraguayensis (2n = 46), Stigmatosema polyaden (2n = 40) and Zygostates alleniana (2n = 54). In addition, a chromosome number is presented for the first time for 15 species: Corymborkis flava (2n = 56), Cyclopogon callophyllus (2n = 28), C. oliganthus (2n = 64), Cyrtopodium hatschbachii (2n = 46), C. palmifrons (2n = 46), Galeandra beyrichii (2n = 54), Habenaria bractescens (2n = 44), Oncidium edwallii (2n = 42), O. fimbriatum (2n = 56), O. pubes (2n = 84), O. riograndense (2n = 56), Pelexia ekmanii (2n = 46), P. lindmanii (2n = 46) and Warrea warreana (2n = 48). For Oncidium longicornu (2n = 42), O. divaricatum (2n = 56) and Sarcoglottis fasciculata (2n = 46+1B?, 46+3B?), a new cytotype was found. Chromosome data support phylogenetic relationships proposed by previous cytological, morphologic and molecular analyses, and in all the cases cover some gaps in the South American literature on orchid chromosomes.

Unusual chromosome numbers in Paspalum L. (Poaceae: Paniceae) from Brazil

Somatic chromosome numbers were determined for 20 new germplasm accessions of Paspalum, belonging to 17 species collected in Brazil. Chromosome number is reported for the first time for P. reduncum (2n = 18), P. cinerascens (2n = 20), P. cordatum (2n = 20), P. filgueirasii (2n = 24), P. ammodes (2n = 36), P. bicilium (2n = 40), P. heterotrichon (2n = 40), and P. burmanii (2n = 48). New cytotypes were confirmed for two germplasm accessions of P. carinatum (2n = 30) and P. trachycoleon (2n = 36), one of P. clavuliferum (2n = 40) and one of P. lanciflorum (2n = 40), indicating variability in these species. The remaining chromosome numbers reported here confirm previous counts. The unexpected chromosome numbers 2n = 18, 24, 36, and 48 in Paspalum species, which are usually shown to be multiples of 10, suggest that much more collection and cytogenetic characterization are necessary to assess the whole chromosomal and genomic multiplicity present in the genus, which seems to be much more diverse than currently thought to be.

Natural triploidy in Leporinus cf. elongatus bearing sex chromosomes

Although several cases of natural triploidy in fish have already been described, spontaneous polyploidy in species with differentiated sex chromosomes are rare. We report the occurrence of a triploid fish (3n = 81) Leporinus cf. elongatus, a species characterized by a highly differentiated ZZ/ZW sex chromosome system, from the São Francisco river. The occurrence of a ZZZ triploid adult indicates the viability of this chromosome constitution in this fish.

Incongruent evolution of chromosomal size in rice

To investigate genome size evolution, it is usually informative to compare closely related species that vary dramatically in genome size. A whole genome duplication (polyploidy) that occurred in rice (Oryza sativa) about 70 million years ago has been well documented based on current genome sequencing. The presence of three distinct duplicate blocks from the polyploidy, of which one duplicated segment in a block is intact (no sequencing gap) and less than half the length of its syntenic duplicate segment, provided an excellent opportunity for elucidating the causes of their size variation during the post-polyploid time. The results indicated that incongruent patterns (shrunken, balanced and inflated) of chromosomal size evolution occurred in the three duplicate blocks, spanning over 30 Mb among chromosomes 2, 3, 6, 7, and 10, with an average of 20.3% for each. DNA sequences of chromosomes 2 and 3 appeared to had become as short as about half of their initial sequence lengths, chromosomes 6 and 7 had remained basically balanced, and chromosome 10 had become dramatically enlarged (approximately 70%). The size difference between duplicate segments of rice was mainly caused by variations in non-repetitive DNA loss. Amplification of long terminal repeat retrotransposons also played an important role. Moreover, a relationship seems to exist between the chromosomal size differences and the nonhomologous combination in corresponding regions in the rice genome. These findings help shed light on the evolutionary mechanism of genomic sequence variation after polyploidy and genome size evolution.

The synthesis of a new cassava-derived species, Manihot vieiri Nassar

A new species was synthesized artificially by chromosome doubling in a hybrid. The ensuing polyploid type exhibits an apomictic nature and maintains its morphological characteristics in the progeny. It showed a frequency of multiembryonic sacs of 29% in the ovules examined, whereas sacs were absent in the diploid type.

Microsporogenesis in tetraploid accessions of Brachiaria nigropedata (Ficalho & Hiern) Stapf (Gramineae)

The genus Brachiaria (Trin.) Griseb. has achieved considerable importance to cattle production systems, as a result of the good production and adaptation of a few cultivars to poor and acid soils of the Brazilian savannas. Many of its species and accessions are polyploid and apomictic, which limits direct hybridization. To assist the breeding program, cytogenetic characterization has been undertaken on the accessions of Brachiaria collection at the Embrapa Beef Cattle Research Center. In this study, chromosome number and meiotic behavior are reported for the Brachiaria nigropedata (Ficalho & Hiern) Stapf collection. The 20 available accessions are tetraploid (2n = 4x = 36). Chromosomes paired preferentially as bivalents, but quadrivalents were found in high frequencies in some cells. Meiotic behavior was, in general, irregular, and varied among accessions. Most accessions presented more than 20% of abnormal tetrads. The most common meiotic abnormalities were those related to irregular chromosome segregation due to polyploidy, leading to micronuclei formation in the tetrad stage. A low frequency of other meiotic abnormalities such as the absence of cytokinesis, chromosome stickiness, cell fusion, anaphase bridges, and chromosome transfer among microsporocytes were also recorded in some accessions. Limitations of these accessions for use in hybridization programs are discussed.