Voltage-Dependent Anion-Selective Channels and Other Mitochondrial Membrane Proteins Form Diverse Complexes in Beetroots Subjected to Flood-Induced Programmed Cell Death.

In plants, programmed cell death (PCD) is involved in both the development and the response to biotic and abiotic aggressions. In early stages of PCD, mitochondrial membranes are made permeable by the formation of permeability transition pores, whose protein composition is debated. Cytochrome c (cyt c) is then released from mitochondria, inducing the degradation of chromatin characteristic of PCD. Since flooding stress can produce PCD in several plant species, the first goal of this study was to know if flooding stress could be used to induce PCD in Beta vulgaris roots. To do this, 2-month-old beet plants were flood-stressed from 1 to 5 days, and the alterations indicating PCD in stressed beetroot cells were observed with a confocal fluorescence microscope. As expected, nuclei were deformed, and chromatin was condensed and fragmented in flooded beetroots. In addition, cyt c was released from mitochondria. After assessing that flood stress induced PCD in beetroots, the composition of mitochondrial protein complexes was observed in control and flood-stressed beetroots. Protein complexes from isolated mitochondria were separated by native gel electrophoresis, and their proteins were identified by mass spectrometry. The spectra count of three isoforms of voltage-dependent anion-selective channels (VDACs) increased after 1 day of flooding. In addition, the size of the complexes formed by VDAC was higher in flood-stressed beetroots for 1 day (∼200 kDa) compared with non-stressed ones (∼100 kDa). Other proteins, such as chaperonin CPN60-2, also formed complexes with different masses in control and flood-stressed beetroots. Finally, possible interactions of VDAC with other proteins were found performing a cluster analysis. These results indicate that mitochondrial protein complexes formed by VDAC could be involved in the process of PCD in flood-stressed beetroots. Data are available via ProteomeXchange with identifier PXD027781.

Exploración de las decisiones académicas en estudiantes con alta capacidad / Exploração de decisões acadêmicas em estudantes de alta capacidade / Exploration des décisions académiques chez les étudiants à haute capacité / Exploration of the academic decisions of highly able students

Resumen La elección de carrera en estudiantes con alta capacidad (AC) no está exenta de dificultades. En STEM (Science, Technology, Engineering, Mathematics) las mujeres con AC no eligen dichas áreas en la misma proporción que los hombres. Se buscó entender cómo los factores contextuales influyen en las decisiones académicas. Es un estudio cualitativo donde se realizaron ocho focus group de estudiantes con AC e intereses en STEM. Los resultados muestran a los padres como modelos; sin embargo, el mensaje paterno puede ser amenazante para las mujeres. Los profesores inspiran y entregan orientaciones claras basadas en las habilidades más que desde un desafío real. Las actividades escolares permiten una experiencia directa con la disciplina, pero producen poca vinculación con reales áreas de interés.

Resumo A escolha da carreira de alunos superdotados não está livre de dificuldades. No tocante à STEM (Science, Technology, Engineering, Mathematics), as mulheres superdotadas não escolhem tais áreas na mesma proporção que os homens. Tentou-se entender de que maneira os fatores contextuais influenciam as decisões acadêmicas. Trata-se de um estudo qualitativo no qual foram realizados oito focus groups de alunos superdotados e com interesses em STEM. Os resultados mostram os pais como modelos; no entanto, a mensagem paterna pode ser ameaçadora para as mulheres. Os professores inspiram e transmitem orientações claras baseadas mais em habilidades que em um desafio real. As atividades escolares permitem uma experiência direta com a disciplina, porém produzem pouca ligação com áreas reais de interesse.

Resumé Le choix de la carrière des elèves à haut potentiel n'est pas libre de difficultés. En ce qui concerne STEM (Science, Technology, Engineering, Mathematics) les femmes à haut potentiel ne choisissent pas tels domaines dans la même proportion que les hommes. On a essayé de comprendre de quelle manière les facteurs du contexte influencent les décisions académiques. Il s'agit d'une étude qualitative pour laquelle on été réalisés huit focus groups d'élèves à haut potentiel intéressés à STEM. Les résultats montrent les parents comme modèle, pourtant le message paternel peut être menaçant pour les femmes. Les enseignants inspirent et transmettent des orientations claires basées plus dans des habilités que dans des défis réels. Les activités scolaires permettent une expérience directe avec la discipline, cependant elles produisent peu de liens avec les vrais domaines d'intérêt.

Abstract The choice of career for students with high ability (HA) is not without its difficulties. In STEM (Science, Technology, Engineering, Mathematics), women with HA do not choose such areas in the same proportion as men. We sought to understand how contextual factors influence the academic decisions of HA students. In this qualitative study, eight focus groups with students with HA and interests in STEM were conducted. The results show parents as role models; however, fathers' messages can be threatening for female students. Results also show that teachers inspire and provide clear guidance based on skills, rather than on real challenge, and that school activities allow direct experience of discipline, but produce little linkage to real areas of interest.

Membrane proteins involved in transport, vesicle traffic and Ca(2+) signaling increase in beetroots grown in saline soils.

MAIN CONCLUSION: By separating plasma membrane proteins according to their hydropathy from beetroots grown in saline soils, several proteins probably involved in salt tolerance were identified by mass spectrometry. Beetroots, as a salt-tolerant crop, have developed mechanisms to cope with stresses associated with saline soils. To observe which plasma membrane (PM) proteins were more abundant in beet roots grown in saline soils, beet root plants were irrigated with water or 0.2 M NaCl. PM-enriched membrane preparations were obtained from these plants, and their proteins were separated according to their hydropathy by serial phase partitioning with Triton X-114. Some proteins whose abundance increased visibly in membranes from salt-grown beetroots were identified by mass spectrometry. Among them, there was a V-type H(+)-ATPase (probably from contaminating vacuolar membranes), which increased with salt at all stages of beetroots' development. Proteins involved in solute transport (an H(+)-transporting PPase and annexins), vesicle traffic (clathrin and synaptotagmins), signal perception and transduction (protein kinases and phospholipases, mostly involved in calcium signaling) and metabolism, appeared to increase in salt-grown beetroot PM-enriched membranes. These results suggest that PM and vacuolar proteins involved in transport, metabolism and signal transduction increase in beet roots adapted to saline soils. In addition, these results show that serial phase partitioning with Triton X-114 is a useful method to separate membrane proteins for their identification by mass spectrometry.

Purification and characterization of a calcium-dependent protein kinase from beetroot plasma membranes.

Several calcium-dependent protein kinases (CDPKs) are located in plant plasma membranes where they phosphorylate enzymes and transporters, like the H(+)-ATPase and water channels, thereby regulating their activities. In order to determine which kinases phosphorylate the H(+)-ATPase, a calcium-dependent kinase was purified from beetroot (Beta vulgaris L.) plasma membranes by anion-exchange chromatography, centrifugation in glycerol gradients and hydrophobic interaction chromatography. The kinetic parameters of this kinase were determined (V(max): 3.5 micromol mg(-1) min(-1), K(m) for ATP: 67 microM, K(m) for syntide 2: 15 microM). The kinase showed an optimum pH of 6.8 and a marked dependence on low-micromolar Ca(2+) concentrations (K(d): 0.77 microM). During the purification procedure, a 63-kDa protein with an isoelectric point of 4.7 was enriched. However, this protein was shown not to be a kinase by mass spectrometry. Kinase activity gels showed that a 50-kDa protein could be responsible for most of the activity in purified kinase preparations. This protein was confirmed to be a CDPK by mass spectrometry, possibly the red beet ortholog of rice CDPK2 and Arabidopsis thaliana CPK9, both found associated with membranes. This kinase was able to phosphorylate purified H(+)-ATPase in a Ca(2+)-dependent manner.