Bacterial Killing Via A Type Iv Secretion System.

Type IV secretion systems (T4SSs) are multiprotein complexes that transport effector proteins and protein-DNA complexes through bacterial membranes to the extracellular milieu or directly into the cytoplasm of other cells. Many bacteria of the family Xanthomonadaceae, which occupy diverse environmental niches, carry a T4SS with unknown function but with several characteristics that distinguishes it from other T4SSs. Here we show that the Xanthomonas citri T4SS provides these cells the capacity to kill other Gram-negative bacterial species in a contact-dependent manner. The secretion of one type IV bacterial effector protein is shown to require a conserved C-terminal domain and its bacteriolytic activity is neutralized by a cognate immunity protein whose 3D structure is similar to peptidoglycan hydrolase inhibitors. This is the first demonstration of the involvement of a T4SS in bacterial killing and points to this special class of T4SS as a mediator of both antagonistic and cooperative interbacterial interactions.

O papel da interação no processo de ensino-aprendizagem de português para alunos surdos em uma escola inclusiva

In this article, it is discussed the role of interaction in the process of teaching and learning Portuguese of deaf students at an inclusive school. In the context where the research took place, the hearing teacher does not understand sign language, and there are, in her classroom, hearing students and four deaf students, being three of them sign language users. As the communication between the hearing teacher and the deaf students occurred in different codes - Portuguese and Brazilian sign language - and having a social-interactional approach of language (MOITA LOPES, 1986; FREIRE, 1999), we observed if the interaction among the subjects enabled the deaf students to understand what was being taught. The results showed that the fact of having four deaf students in the same classroom allowed them to work in a cooperative way. Besides, the sign language became more visible in this institution. On the other hand, the interaction between the teacher and her deaf students revealed to be of little significance to the learning process of this small group.

Qualidade de vida e cultura solidária : o caso da Cooperativa Nossa Senhora Aparecida

Universidade Estadual de Campinas . Faculdade de Educação Física