The Atp-dependent Rna Helicase Hrpb Plays An Important Role In Motility And Biofilm Formation In Xanthomonas Citri Subsp Citri

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)RNA helicases are enzymes that catalyze the separation of double-stranded RNA (dsRNA) using the free energy of ATP binding and hydrolysis. DEAD/DEAH families participate in many different aspects of RNA metabolism, including RNA synthesis, RNA folding, RNA-RNA interactions, RNA localization and RNA degradation. Several important bacterial DEAD/DEAH-box RNA helicases have been extensively studied. In this study, we characterize the ATP-dependent RNA helicase encoded by the hrpB (XAC0293) gene using deletion and genetic complementation assays. We provide insights into the function of the hrpB gene in Xanthomonas citri subsp. citri by investigating the roles of hrpB in biofilm formation on abiotic surfaces and host leaves, cell motility, host virulence of the citrus canker bacterium and growth in planta. Results: The hrpB gene is highly conserved in the sequenced strains of Xanthomonas. Mutation of the hrpB gene (Delta hrpB) resulted in a significant reduction in biofilms on abiotic surfaces and host leaves. Delta hrpB also exhibited increased cell dispersion on solid medium plates. Delta hrpB showed reduced adhesion on biotic and abiotic surfaces and delayed development in disease symptoms when sprayed on susceptible citrus leaves. Quantitative reverse transcription-PCR assays indicated that deletion of hrpB reduced the expression of four type IV pili genes. The transcriptional start site of fimA (XAC3241) was determined using rapid amplification of 5'-cDNA Ends (5' RACE). Based on the results of fimA mRNA structure predictions, the fimA 5' UTR may contain three different loops. HrpB may be involved in alterations to the structure of fimA mRNA that promote the stability of fimA RNA. Conclusions: Our data show that hrpB is involved in adherence of Xanthomonas citri subsp. citri to different surfaces. In addition, to the best of our knowledge, this is the first time that a DEAH RNA helicase has been implicated in the regulation of type IV pili in Xanthomonas.16INCT CitrusCAPES/PSDE fellowship [99999.002657/2014-07]CNPqCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Looking to the future of zebrafish as a model to understand the genetic basis of eye disease

In this brief commentary, we provide some of our thoughts and opinions on the current and future use of zebrafish to model human eye disease, dissect pathological progression and advance in our understanding of the genetic bases of microphthalmia, andophthalmia and coloboma (MAC) in humans. We provide some background on eye formation in fish and conservation and divergence across vertebrates in this process, discuss different approaches for manipulating gene function and speculate on future research areas where we think research using fish may prove to be particularly effective

Early exposure to alcohol leads to permanent impairment of dendritic excitability in neocortical pyramidal neurons

Exposure to alcohol in utero is a well known cause of mental retardation in humans. Using experimental models of fetal alcohol spectrum disorder, it has been demonstrated that cortical pyramidal neurons and their projections are profoundly and permanently impaired. Yet, how the functional features of these cells are modified and how such modifications impact cognitive processes is still unknown. To address this, we studied the intrinsic electrophysiological properties of pyramidal neurons in young adult rats (P30-P60) exposed to ethanol inhalation during the first week of postnatal life (P2-P6). Dual whole-cell recordings from the soma and distal apical dendrites were performed and, following the injection of depolarizing current into the dendrites, layer 5 neurons from ethanol-treated (Et) animals displayed a lower number and a shorter duration of dendritic spikes, attributable to a downregulation of calcium electrogenesis. As a consequence, the mean number of action potentials recorded at the soma after dendritic current injection was also lower in Et animals. No significant differences between Et and controls were observed in the firing pattern elicited in layer 5 neurons by steps of depolarizing somatic current, even though the firing rate was significantly lower in Et animals. The firing pattern and the firing rate of layer 2/3 neurons were not affected by alcohol exposure

Action naming in dementia

Recent studies of action naming in dementia report contradictory results. Some studies have shown that naming of pictured actions is impaired and indeed worse than naming of pictured objects, whereas other studies report the opposite result, i.e. action naming is better preserved than object naming. One reason for these conflicting results may be that actions vary in their relationships with object knowledge. Instrumental actions, e.g. hammering, require access to knowledge about a specific object (a tool), whereas non-instrumental actions can be named correctly without access to knowledge about a specific object, e.g. running. Moreover, many instrumental action names share a name relationship with the instrument used to perform the action (homophony), whereas other action names do not, e.g. digging. In this case report, we describe an anomic patient RS with dementia affecting his access to knowledge about objects from visual, verbal and tactile input. By contrast, RS displays relatively well-preserved knowledge and naming of actions. We found an effect of instrumentality on pictured action naming, i.e. actions that depict an actor using a tool are named less accurately than actions that depict an actor performing an action without a tool. We argue that the instrumentality effect is independent of the name relationship between the action and the object and also the visual complexity of the action. We consider several explanations of the instrumentality effect and conclude that an impairment to the areas underpinning sensory feature and sensorimotor information (specific to manipulation) can account for an effect of instrumentality on action naming in dementia.link_to_subscribed_fulltex

Looking to the future of zebrafish as a model to understand the genetic basis of eye disease

In this brief commentary, we provide some of our thoughts and opinions on the current and future use of zebrafish to model human eye disease, dissect pathological progression and advance in our understanding of the genetic bases of microphthalmia, andophthalmia and coloboma (MAC) in humans. We provide some background on eye formation in fish and conservation and divergence across vertebrates in this process, discuss different approaches for manipulating gene function and speculate on future research areas where we think research using fish may prove to be particularly effective