Growth and Nitrogen Fixation Activity of Soybeans in the Presence of Bean Pod Mottle Virus

Pathological and physiological responses associated with the host-microsymbiont interaction of soybeans (Glycine max‘Franklin’, ‘Dyer’, ‘Centennial’, ‘Marshall’, ‘Williams’, ‘Bedford’, and ‘Peking’), which were nodulated with Rhizobium japonicum (USDA strain 3I1b-110) and inoculated with bean pod mottle virus (BPMV) in the greenhouse, varied with the cultivar and the substrate in which the plants were grown. In plants grown in a soil mixture, the virus significantly reduced canopy growth, nodulation, total N, and ureide-N content of most cultivars but symbiotic N₂ fixation was significantly reduced only for ‘Centennial’ and ‘Peking’. In vermiculite, in which the plants depended almost exclusively on symbiotically fixed N_,2, the virus reduced canopy and nodule mass of some cultivars but these reductions were significant only for ‘Franklin’. In plants grown in this substrate, however, the virus had little effect as increases or decreases in measured components of symbiotic N metabolism were nonsignificant except for the increase in leaf ureides in ‘Marshall’. Results suggest that in either soil or vermiculite the symbiotic process in certain soybean cultivars can function at nearly a normal level despite root noduleinfection with this virus.     

Potentiation of diacylglycerol-activated protein kinase C by acyl-coenzyme A thioesters of hypolipidaemic drugs

Acyl-Coenzyme A thioesters of the hypolipidaemic and cancerinogenic peroxisome proliferators clofibric acid, nafenopin, ciprofibrate, bezafibrate and tibric acid were found to greatly increase the activity of rat brain protein kinase C. Maximal activation required the simultaneous presence of Ca+2, phosphatidylserine and diolein, thus differentiating their action from that of other tumor promoters such as phorbol esters. Under similar conditions the unesterified drugs were comparatively ineffective. Similar results were obtained using the rat liver enzyme. The data suggest that acylcoenzyme A thioesters of hypolipidaemic drugs, may play a role in the induction of liver tumors by these compounds, through the potentiation of protein kinase C.     

An invisible ubiquitin conformation is required for efficient phosphorylation by PINK1

The Ser/Thr protein kinase PINK1 phosphorylates the well‐folded, globular protein ubiquitin (Ub) at a relatively protected site, Ser65. We previously showed that Ser65 phosphorylation results in a conformational change in which Ub adopts a dynamic equilibrium between the known, common Ub conformation and a distinct, second conformation wherein the last β‐strand is retracted to extend the Ser65 loop and shorten the C‐terminal tail. We show using chemical exchange saturation transfer (CEST) nuclear magnetic resonance experiments that a similar, C‐terminally retracted (Ub‐CR) conformation also exists at low population in wild‐type Ub. Point mutations in the moving β5 and neighbouring β‐strands shift the Ub/Ub‐CR equilibrium. This enabled functional studies of the two states, and we show that while the Ub‐CR conformation is defective for conjugation, it demonstrates improved binding to PINK1 through its extended Ser65 loop, and is a superior PINK1 substrate. Together our data suggest that PINK1 utilises a lowly populated yet more suitable Ub‐CR conformation of Ub for efficient phosphorylation. Our findings could be relevant for many kinases that phosphorylate residues in folded protein domains.     

Cell membrane permeabilization via connexin hemichannels in living and dying cells

Vertebrate cells that express connexins likely express connexin hemichannels (Cx HCs) at their surface. In diverse cell types, surface Cx HCs can open to serve as a diffusional exchange pathway for ions and small molecules across the cell membrane. Most cells, if not all, also express pannexins that form hemichannels and increase the cell membrane permeability but are not addressed in this review. To date, most characterizations of Cx HCs have utilized cultured cells under resting conditions have and revealed low open probability and unitary conductance close to double that of the corresponding gap junction channels. In addition, the cell membrane permeability through Cx HCs can be markedly affected within seconds to minutes by various changes in the intra and/or extracellular microenvironment (i.e., pH, pCa, redox state, transmembrane voltage and intracellular regulatory proteins) that affect levels, open probability and/or (single channel) permeability of Cx HC. Net increase or decrease in membrane permeability could result from the simultaneous interaction of different mechanisms that affect hemichannels. The permeability of Cx HCs is controlled by complex signaling cascades showing connexin, cell and cell stage dependency. Changes in membrane permeability via hemichannels can have positive consequences in some cells (mainly in healthy cells), whereas in others (mainly in cells affected by acquired and/or genetic diseases) hemichannel activation can be detrimental.     

Hypochaeris alliatae group (Asteraceae) in the western Mediterranean Region

A taxonomic, ecological, and phytogeographical revision of the Hypochaeris alliatae group is made. As a result, the name of H. alliatae (vs H. laevigata ) is proposed. The recent taxa H. leontodontoides var. glauca and H. rutea are synonymised with H. alliatae , and H. leontodontoides var. atlantica var. nov ., is described. Using chromosomal counts, morphological and histological characters, H. angustifolia is excluded from the H. alliatae group. A phylogenetic and phytogeographical assay has been made in the context of geologic phenomena from the Miocene and Pliocene in the western Mediterranean Basin.     

El Niño‐Southern Oscillation cyclical modulation of macrobenthic community structure in the Humboldt Current ecosystem

Understanding how natural communities confront different types of natural and anthropogenic stressors has gained much more attention as global climate change imposes nearly unpredictable ecosystem states or regimes. In the Humboldt Current ecosystem this seems to be a priority task due to the complex dynamics caused by the El Niño Southern Oscillation (ENSO). Herein a 17‐year (1991–2007) time‐series data‐set of macrobenthic community structure and environmental parameters from seasonal sampling from four fixed stations off Punta Coloso (23°45’S, 70°28’W northern of Chile) is analyzed. The aim of this study was to assess benthic responses to ENSO‐associated anomalies. nMDS analysis revealed changes in community structure associated to El Niño (1997–1998) and La Niña (1999–2000). From 1991, communities gradually increased in dissimilarity up to 1998 but after 2000 dissimilarity decreased, thus approaching the early community structure in a counterclockwise like direction. This suggested a cyclical pattern throughout time, which was tested with a cyclicity analysis. The test showed a significant correlation between the dissimilarity biotic matrix and a perfect cyclicity model matrix. The finding of a 17‐year cycle in the variation of community structure adds new insights and contrast to previous observations of increments in diversity and alternation of dominant taxa associated to environmental forcing. It needs to be revealed if this cycle forms part of a major decadal oscillation in the benthic subsystem. Nevertheless, this result is in line with the decadal pattern of variability observed for pelagic communities associated to warm and cold phases of ENSO.     

New Immigrant Youth Interpreting in White Public Space

ABSTRACT   Bilingual children are frequently called on to use their linguistic and communicative virtuosity to interpret for monolingual speakers. In this article, we theorize child interpreters' positionalities within the interstices of several borderlands: as children; as interpreters and translators interpreting different languages, registers, and discourses; and as immigrants seeking services within white public space. We analyze how youths are positioned to provide service and surveillance within overdetermined interpreter-mediated practices. In examining these practices, we raise to consciousness some of the social and ideological conditions that circumscribe working-class Latino/a and new Mexican immigrant children within inherently unequal subject positions. [Keywords: interpreter-mediated interactions, childhood, Mexican new immigrants, racialization, white public space]