The Contribution of Coevolving Residues to the Stability of KDO8P Synthase

The evolutionary tree of 3-deoxy-D-manno-octulosonate 8-phosphate (KDO8P) synthase (KDO8PS), a bacterial enzyme that catalyzes a key step in the biosynthesis of bacterial endotoxin, is evenly divided between metal and non-metal forms, both having similar structures, but diverging in various degrees in amino acid sequence. Mutagenesis, crystallographic and computational studies have established that only a few residues determine whether or not KDO8PS requires a metal for function. The remaining divergence in the amino acid sequence of KDO8PSs is apparently unrelated to the underlying catalytic mechanism.The multiple alignment of all known KDO8PS sequences reveals that several residue pairs coevolved, an indication of their possible linkage to a structural constraint. In this study we investigated by computational means the contribution of coevolving residues to the stability of KDO8PS. We found that about 1/4 of all strongly coevolving pairs probably originated from cycles of mutation (decreasing stability) and suppression (restoring it), while the remaining pairs are best explained by a succession of neutral or nearly neutral covarions.Both sequence conservation and coevolution are involved in the preservation of the core structure of KDO8PS, but the contribution of coevolving residues is, in proportion, smaller. This is because small stability gains or losses associated with selection of certain residues in some regions of the stability landscape of KDO8PS are easily offset by a large number of possible changes in other regions. While this effect increases the tolerance of KDO8PS to deleterious mutations, it also decreases the probability that specific pairs of residues could have a strong contribution to the thermodynamic stability of the protein

Aprendizagem de sinais vitais utilizando objetos educacionais digitais: opinião de estudantes de enfermagem Opiniones de estudiantes de enfermería cuanto el trabajo en grupo con apoyo de la informática Undergraduated nursing student's opinion about group work in online project

Estudo com o objetivo de conhecer as opiniões de estudantes de enfermagem quanto à prática pedagógica sobre sinais vitais fundamentada na aprendizagem baseada em problemas, apresentada na forma de objetos educacionais digitais. A pesquisa, na metodologia do estudo de caso qualitativo, contou com dez sujeitos. Os dados foram obtidos por meio de entrevistas semi-estruturadas analisadas pela técnica da análise temática. Identificou-se três categorias finais: a aprendizagem com o apoio da informática, a organização do trabalho em grupo e a avaliação do projeto de aprendizagem de sinais vitais. A atividade foi uma experiência nova para os alunos, considerada positiva pela facilitação do acesso aos conteúdos e da comunicação entre colegas, porém apontaram a falta da presença física do professor. O trabalho em grupo transcorreu, na sua maioria, de forma colaborativa. Constatou-se a importância de disponibilizar, a estudantes de enfermagem, atividades mediadas pelo computador associadas à metodologia da aprendizagem baseada em problemas.<br>Este estudio buscó conocer las opiniones de estudiantes de enfermería cuanto a la práctica pedagógica sobre señales vitales fundamentada en el aprendizaje basado en problemas, integrado a objetos educacionales digitales. La investigación, un estudio de caso cualitativo, contó con diez sujetos. Los datos fueron obtenidos por medio de entrevistas semiestructuradas analizadas a través del análisis temático. Se identificaron tres categorías finales: el aprendizaje con el apoyo de la informática, la organización del trabajo en grupo y la evaluación del proyecto de aprendizaje de señales vitales. La actividad fue una experiencia nueva para los alumnos, considerada positiva por la facilitación del acceso a los contenidos y de la comunicación entre colegas, pero echaron de menos la presencia física del profesor. El trabajo en grupo transcurrió, en gran parte, de forma colaborativa. Se constató la importancia de ofrecer, a estudiantes de enfermería, actividades mediadas por ordenadores asociadas al aprendizaje basado en problemas.<br>The purpose of this study was to know undergraduated nursing students' opinions about the pedagogical practice in vital signs founded on the problem-based learning presented in the form of digital educational objects. Ten individuals participated in the research, which used the methodology of a qualitative case study. Data were obtained by means of semi-structured interviews analyzed through thematic analysis. Three final categories were identified: computer-based learning, group work organization, and vital sign learning project evaluation. The activity was a new experience for the students, who considered it as positive because it made easy both the access to contents and the communication between classmates. However, the students missed the physical presence of the professor. The group work was conducted, most of the time, in a collaborative way. Offering computer-mediated activities associated to the problem-based learning methodology to nursing students has proven to be important

Diet overlap between the newly introduced Lamprichthys tanganicanus and the Tanganyika sardine in Lake Kivu, Eastern Africa

This study evaluates the possible competition for food between Lamprichthys tanganicanus, recently introduced in Lake Kivu, and Limnothrissa miodon, which has been the basis of the pelagic fishery in this lake for several decades. Since 2006, L. tanganicanus has expanded in the lake and its numbers have increased in the captures, raising concern for the sardine fishery. We carried out a 2-year monthly survey, based on experimental captures in littoral and pelagic stations, which demonstrated the invasive dispersal of L. tanganicanus in littoral and pelagic waters. The diet of both species was determined on the basis of gut content analyses, taking into account the influence of site and season, and a diet overlap index was calculated. In the pelagic zone, where almost all size classes of both species were present and essentially fed upon mesozooplankton, the diet overlap was high. This situation stems from the fact that L. tanganicanus has colonized the pelagic zone in Lake Kivu, likely in search for more abundant mesozooplankton. Inshore, the diet overlap between the two species was lower, as L. tanganicanus consumed a broad range of food, whereas L. miodon strongly selected insects and, chiefly for the largest specimens, fishes. These results suggest a likelihood of interspecific competition, particularly offshore, where mesozooplankton is the main available food type, and call for further monitoring of the sardine fishery, to assess a possible impact of the invader. © 2011 Springer Science+Business Media B.V