Difference in Germination Traits between Congeneric Native and Exotic Species May Affect Invasion.

Germination traits are components of invasion potential, and comparing seed traits in sympatric native and invasive species can offer insights into the invasion process. We characterized seed germination traits and how they influenced the success of Eragrostis mexicana, a native species, and Eragrostis tenuifolia, an exotic species (Poaceae) in Mexico, in the context of their potential for biological invasion. Seeds from both species were collected from four sites in a natural protected area in Mexico City, and the germination of seeds of different ages was conducted in experiments at different temperatures. E. tenuifolia exhibited higher germination percentages than the native E. mexicana across all treatments. Seed age had differential effects, with older seeds of the native E. mexicana germinating better, while E. tenuifolia performed better with younger seeds. Temperature positively impacted germination for both species, although E. mexicana was limited at lower temperatures. Exotic E. tenuifolia can germinate over a wider temperature range with earlier germination rates, and generate a seed bank lasting several years, which may contribute to naturalization. The importance of germination traits in the context of invasive species establishment underscores the potential role of seed banks in facilitating biological invasions.

ZEB1 and ZEB2 transcription factors are potential therapeutic targets of canine mammary cancer cells.

Mammary tumours are the most frequent in female dogs as in women and half are malignant. Tumorigenicity and invasiveness are important acquired characteristics for the development and progression of cancers and could be regulated by transcription factors associated with epithelial-mesenchymal transition (EMT) as ZEB1, ZEB2, SNAI1, SLUG and STAT3. Thus, here, we evaluate the expression of EMT-associated transcription factors in canine mammary cancer (CMC) cell lines characterized for invasiveness and tumorigenicity to determine if these could be considered good targets for future development of therapies. Five CMC cell lines were characterized regarding their morphology, doubling time and expression of intermediate and actin filaments. In addition, gene expression of SLUG, STAT3, ZEB1, ZEB2 and CDH1, tumorigenicity and invasiveness were assessed. Two of these cells presented an epithelial-like morphology (E20 and E37) and three a mesenchymal-like morphology (M5, M25 and CF41.Mg). M25 and CF41.Mg presented higher invasiveness. Furthermore, only mesenchymal-like cells formed tumorspheres and CF41.Mg made more and larger tumorspheres. The mesenchymal-like cells are more malignant than the epithelial-like cells being the CF41.Mg the most malignant. This cell presented higher ZEB1 and ZEB2 and lower CDH1 gene expression. Finally, our results revealed that there is a positive correlation between ZEBs and the tumorsphere number and size. In conclusion, these findings support ZEB1 and ZEB2 as potential therapeutic targets for CMC cells, demonstrating a great potential of canine models for comparative and translational studies.

Interaction of temperature and light on seed germination in Tecoma stans L. Juss. ex Kunth (Bignoniaceae)

The effects of the temperature and light on the control of seeds germination in Tecoma stans was studied in the present work. The influence of constant temperatures from 10 to 45ºC, with 5ºC intervals, under the white light and darkness were tested. The optimum temperature for the germination of the seeds was between 25 and 30ºC, for both the light and the dark treatments. The maximal germination was reached in the range of 15 to 35ºC under the light and of 20 to 40ºC in the darkness. The seeds showed highest synchronization of the germination near the optimal temperature. The germination in the field was tested under the two light conditions. The highest percent of germination occurred under the direct sunlight (86.1%) than under the canopy (69%). However, under the canopy, the seedling presented 1.5% of the recruitment, while under the direct sunlight, 96.9 %. Results showed that T. stans seeds germinated well in the open areas with the occurrence of high seedling recruitment indicating the invasion potential of the species in such light conditions.

Os efeitos da temperatura e da luz na germinação de Tecoma stans foram determinados no presente trabalho. Foram testadas temperaturas constantes de 10 a 45ºC, com intervalos de 5ºC, sob luz branca e escuro. Verificou-se que a temperatura ótima para a germinação da espécie está entre 25 e 30ºC, tanto na luz como no escuro, já o intervalo de máxima germinabilidade está entre 15 e 35ºC na luz e 20 e 40ºC no escuro. Suas sementes apresentaram uma maior sincronização da germinação próxima à temperatura ótima. A germinação de sementes de Tecoma stans em condições naturais foi testada sob radiação solar direta e na sombra de vegetação. A maior porcentagem de emergência ocorreu no ambiente de sol (86,1%), porém com menor velocidade em relação à sombra, embora na sombra também ocorreu a emergência, mas em menor proporção (69%). Entretanto, o índice de recrutamento na sombra foi de 1,5% enquanto a pleno sol foi de 96,9%. Estes resultados indicam que as sementes de Tecoma stans germinam e recrutam suas plântulas em ambientes abertos confirmando o potencial invasor da espécie.