RESUMEN
Syzygium album is a plant species with extremely small population and endemic to Yun-xiao County, Fujian Province. We examined its population status and conservation evaluation. The results showed that there were 25 individuals of S. album, with only one mother tree. Except for the mother tree and one small tree, the others were all young seedlings, which was rare in abundance and lack of age stage of middle and strong trees. The spatial distribution of young seedlings was not uniform, with most of individuals within the range of 10-25 m from the mother tree. The age class structure of the population was not continuous and the population development was unsustainable. The competition mainly came from other species. Cryptocarya chinensis accounted for 66.6% of the total competition index, which was much higher than other species. We established a comprehensive evaluation index system for the protection of rare and endangered plants with extremely small populations and evaluated the protection of S. album from three aspects, i.e., endangered degree, protection value, and protection priority. The endangered degree of S. album was level â (the endangered degree index was 4.510), belonging to extremely endangered species, the protection value was level â (the protection value index was 4.052), which was of great value, and the protection priority was level â (the protection priority index was 4.016), which should be listed as the highest priority protection level.
Asunto(s)
Syzygium , Animales , Ecosistema , Especies en Peligro de Extinción , Humanos , Plantas , ÁrbolesRESUMEN
Mouse embryonic stem (ES) cells can be differentiated into neural lineage cells, but the differentiation efficiency remains low. This study revealed two important factors that influence the neural differentiation efficiency of mouse ES cells: the first is the quality of embryonic bodies (EBs); good quality of EBs consistently originated from a suspension culture of 1x10(5) ES cells/ml serum-free chemically defined neural inducing medium and they exhibited a smooth round shape, with a dark central region surrounded by a light band. Such EBs are capable of attaining high neural differentiation efficiency. However, poor quality EBs originated from a suspension culture of 1x10(6) ES cells/ml serum-free chemically defined neural inducing medium and exhibited an irregular shape or adhered to the bottom of the dish; they displayed low neural differentiation efficiency. The second factor is the seeding density of EBs: a low seeding density (5 EBs/cm2) induced cells to differentiate into a more caudalized subtypes compared to the cells obtained from high seeding density (20 EBs/cm2). These findings provided fresh insight into the neural induction of mouse ES cells.
Asunto(s)
Diferenciación Celular , Embrión de Mamíferos/citología , Células Madre Embrionarias/citología , Neuronas/citología , Animales , Factor Neurotrófico Derivado del Encéfalo/farmacología , Recuento de Células , Diferenciación Celular/efectos de los fármacos , Línea Celular , Linaje de la Célula/efectos de los fármacos , Forma de la Célula/efectos de los fármacos , Células Madre Embrionarias/efectos de los fármacos , Ratones , Neuronas/efectos de los fármacos , Factores de TiempoRESUMEN
Six human embryonic stem cell lines were established from surplus blastocysts. The cell lines expressed alkaline phosphatase and molecules typical of primate embryonic stem cells, including Oct-4, Nanog, TDGF1, Sox2, EBAF, Thy-1, FGF4, Rex-1, SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81. Five of the six lines formed embryoid bodies that expressed markers of a variety of cell types; four of them formed teratomas with tissue types representative of all three embryonic germ layers. These human embryonic stem cells are capable of producing clones of undifferentiated morphology, and one of them was propagated to become a subline. Human embryonic stem cell lines from the Chinese population should facilitate stem cell research and may be valuable in studies of population genetics and ecology.