Role of pH in a nitric oxide-dependent increase in cytosolic Cl \u3csup\u3e-\u3c/sup\u3e in retinal amacrine cells

Nitric oxide (NO) synthase-expressing neurons are found throughout the vertebrate retina. Previous work by our laboratory has shown that NO can transiently convert inhibitory GABAergic synapses onto cultured retinal amacrine cells into excitatory synapses by releasing Cl - from an internal store in the postsynaptic cell. The mechanism underlying this Cl -release is currently unknown. Because transport of Cl - across internal membranes can be coupled to proton flux, we asked whether protons could be involved in the NO-dependent release of internal Cl -. Using pH imaging and whole cell voltage-clamp recording, we addressed the relationship between cytosolic pH and cytosolic Cl - in cultured retinal amacrine cells. We found that NO reliably produces a transient decrease in cytosolic pH. A physiological link between cytosolic pH and cytosolic Cl - was established by demonstrating that shifting cytosolic pH in the absence of NO altered cytosolic Cl - concentrations. Strong buffering of cytosolic pH limited the ability of NO to increase cytosolic Cl -, suggesting that cytosolic acidification is involved in generating the NO-dependent elevation in cytosolic Cl -. Furthermore, disruption of internal proton gradients also reduced the effects of NO on cytosolic Cl -. Taken together, these results suggest a cytosolic environment where proton and Cl - fluxes are coupled in a dynamic and physiologically meaningful way. © 2011 the American Physiological Society

Conserved Roles for Polycomb Repressive Complex 2 in the Regulation of Lateral Organ Development in Aquilegia X Coerulea 'Origami'

Background: Epigenetic regulation is necessary for maintaining gene expression patterns in multicellular organisms. The Polycomb Group (PcG) proteins form several complexes with important and deeply conserved epigenetic functions in both the plant and animal kingdoms. One such complex, the Polycomb Repressive Complex 2 (PRC2), is critical to many developmental processes in plants including the regulation of major developmental transitions. In addition, PRC2 restricts the expression domain of various transcription factor families in Arabidopsis, including the class I KNOX genes and several of the ABCE class MADS box genes. While the functions of these transcription factors are known to be deeply conserved, whether or not their regulation by PRC2 is similarly conserved remains an open question. Results: Here we use virus-induced gene silencing (VIGS) to characterize the function of the PRC2 complex in lateral organ development of Aquilegia x coerulea 'Origami', a member of the lower eudicot order Ranunculales. Leaves with PRC2 down-regulation displayed a range of phenotypes including ruffled or curled laminae, additional lobing, and an increased frequency of higher order branching. Sepals and petals were also affected, being narrowed, distorted, or, in the case of the sepals, exhibiting partial homeotic transformation. Many of the petal limbs also had a particularly intense yellow coloration due to an accumulation of carotenoid pigments. We show that the A. x coerulea floral MADS box genes AGAMOUS1 (AqAG1), APETALA3-3 (AqAP3-3) and SEPALLATA3 (AqSEP3) are up-regulated in many tissues, while expression of the class I KNOX genes and several candidate genes involved in carotenoid production or degradation are largely unaffected. Conclusions: PRC2 targeting of several floral MADS box genes may be conserved in dicots, but other known targets do not appear to be. In the case of the type I KNOX genes, this may reflect a regulatory shift associated with the evolution of compound leaves.Organismic and Evolutionary Biolog

Nitric oxide transiently converts synaptic inhibition to excitation in retinal amacrine cells

Nitric oxide (NO) is generated by multiple cell types in the vertebrate retina, including amacrine cells. We investigate the role of NO in the modulation of synaptic function using a culture system containing identified retinal amacrine cells. We find that moderate concentrations of NO alter GABAA receptor function to produce an enhancement of the GABA-gated current. Higher concentrations of NO also enhance GABA-gated currents, but this enhancement is primarily due to a substantial positive shift in the reversal potential of the current. Several pieces of evidence, including a similar effect on glycine-gated currents, indicate that the positive shift is due to an increase in cytosolic Cl-. This change in the chloride distribution is especially significant because it can invert the sign of GABA- and glycine-gated voltage responses. Furthermore, current- and voltage-clamp recordings from synaptic pairs of GABAergic amacrine cells demonstrate that NO transiently converts signaling at GABAergic synapses from inhibition to excitation. Persistence of the NO-induced shift in ECl- in the absence of extracellular Cl- indicates that the increase in cytosolic Cl- is due to release of Cl- from an internal store. An NO-dependent release of Cl- from an internal store is also demonstrated for rat hippocampal neurons indicating that this mechanism is not restricted to the avian retina. Thus signaling in the CNS can be fundamentally altered by an NO-dependent mobilization of an internal Cl- store. Copyright © 2006 The American Physiological Society

Characterization of Aquilegia Polycomb Repressive Complex 2 homologs reveals absence of imprinting

Epigenetic regulation is important for maintaining gene expression patterns in multicellular organisms. The Polycomb Group (PcG) proteins form several complexes with important and deeply conserved epigenetic functions in both the plant and animal kingdoms. The plant Polycomb Repressive Complex 2 (PRC2) contains four core proteins, Enhancer of Zeste (E(z)), Suppressor of Zeste 12 (Su(z)12), Extra Sex Combs (ESC), and Multicopy Suppressor of IRA 1 (MSI1), and functions in many developmental transitions. In some plant species, including rice and Arabidopsis, duplications in the core PRC2 proteins allow the formation of PRC2s with distinct developmental functions. In addition, members of the plant specific VEL PHD family have been shown to associate with the PRC2 complex in Arabidopsis and may play a role in targeting the PRC2 to specific loci. Here we examine the evolution and expression of the PRC2 and VEL PHD families in Aquilegia, a member of the lower eudicot order anunculales and an emerging model for the investigation of plant ecology, evolution and developmental genetics. We find that Aquilegia has a relatively simple PRC2 with only one homolog of Su(z)12, ESC and MSI1 and two ancient copies of E(z), AqSWN and AqCLF. Aquilegia has four members of the VEL PHD family, three of which appear to be closely related to Arabidopsis proteins known to associate with the PRC2. The PRC2 and VEL PHD family proteins are expressed at a relatively constant level throughout Aquilegia vulgaris development, with the VEL PHD family and MSI1 expressed at higher levels during and after vernalization and in the inflorescence. Both AqSWN and AqCLF are expressed in Aquilegia endosperm but neither copy is imprinted.Organismic and Evolutionary Biolog

Sex In Advertising: An Exploratory Study Of The Heterosexual Perception

In this paper, we theorise and empirically investigate how consumers' attitudes and perceptions relating to sexual imagery in advertising are perceived. In addition, we address the link between sexual imagery and the attitudes it creates and maintains within consumers today. With the growing prevalence of sexualised imagery in modern day advertisements it is crucial for not only marketers and advertising practitioners to gain deeper insights into how consumers perceive sexual advertising content, but to understand the emotional aspects of how it influences them. The theoretical work is informed by areas of research including the history of sexual imagery in advertising, what makes an advertisement sexy, and gender roles in regards to sexual imagery. For the purpose of needing to elicit deep consumer insights the Zaltman Metaphor Elicitation Technique (ZMET) was employed. Using ZMET four main themes were found: elements that make an advertisement sexual; symbolic metaphors for sexual imagery; descriptive adjectives that distinguish particular types of sexualised images; attitudes and beliefs regarding topics in sexual imagery. The focus on surfacing metaphors linked to sexual imagery provides a deeper understanding of consumer’s both conscious and hidden thoughts and the motivation behind their behaviour

Sex In Advertising: An Exploratory Study Of The Heterosexual Perception

In this paper, we theorise and empirically investigate how consumers' attitudes and perceptions relating to sexual imagery in advertising are perceived. In addition, we address the link between sexual imagery and the attitudes it creates and maintains within consumers today. With the growing prevalence of sexualised imagery in modern day advertisements it is crucial for not only marketers and advertising practitioners to gain deeper insights into how consumers perceive sexual advertising content, but to understand the emotional aspects of how it influences them. The theoretical work is informed by areas of research including the history of sexual imagery in advertising, what makes an advertisement sexy, and gender roles in regards to sexual imagery. For the purpose of needing to elicit deep consumer insights the Zaltman Metaphor Elicitation Technique (ZMET) was employed. Using ZMET four main themes were found: elements that make an advertisement sexual; symbolic metaphors for sexual imagery; descriptive adjectives that distinguish particular types of sexualised images; attitudes and beliefs regarding topics in sexual imagery. The focus on surfacing metaphors linked to sexual imagery provides a deeper understanding of consumer’s both conscious and hidden thoughts and the motivation behind their behaviour

Conserved Genetic Modules Controlling Lateral Organ Development: Polycomb Repressive Complex 2 and ASYMMETRIC LEAVES1 Homologs in the Lower Eudicot Aquilegia (Columbine).

Development in multicellular organisms relies on establishing and maintaining gene expression profiles that give cells identity. Transcription factors establish gene expression profiles by integrating positional, temporal, and environmental cues to regulate genes essential for a cell's identity. These signals are often short lived while the differentiated state may persist for a long time. Epigenetic factors maintain these gene expression profiles by making heritable chemical alterations to target gene chromatin to stabilize transcriptional patterns. Here we explore the evolution and function of an epigenetic regulator, the Polycomb Repressive Complex 2 (PRC2), and a transcription factor, ASYMMETRIC LEAVES 1 (AS1) , in the lower eudicot Aquilegia. PRC2 is an important and deeply conserved epigenetic regulator, which is critical to many plant developmental processes, including the regulation of major developmental transitions and lateral organ development. We find that Aquilegia has a relatively simple complement of PRC2 genes that are expressed throughout development. Contrary to findings in other plant species, two members of the Aquilegia PRC2, AqSWN and AqCLF, are not imprinted in Aquilegia endosperm. Using virusinduced gene silencing (VIGS), we determined that Aquilegia PRC2 regulates aspects of lateral organ development, including branching within the leaf and lamina expansion, along with caroteinoid production in floral organs. PRC2 targeting of several floral MADS box genes may be conserved in Aquilegia, but other known targets such as the class I KNOX gene are not. AS1 is a transcription factor that plays a conserved role in controlling differentiation and polarity of lateral organs. In species with simple leaves, AS1 promotes cell determination by suppressing the expression of the class I KNOX genes in leaf primordia and regulates abaxial-adaxial polarity in the developing leaf. However, in species with compound leaves, KNOX genes and AS1 often work together to control leaflet initiation and arrangement. In Aquilegia, AqAS1 appears to primarily contribute to proper regulation of class I KNOX genes with a more minor role in leaflet polarity and positioning. Most interestingly, these combined datasets suggest that contrary to the widely held model, class I KNOX genes are neither necessary nor sufficient for leaf complexity in Aquilegia

Online learning for infectious disease fellows-A needs assessment

BACKGROUND: Online resources and social media have become increasingly ubiquitous in medical education. Little is known about the need for educational resources aimed at infectious disease (ID) fellows. METHODS: We conducted an educational needs assessment through a survey that aimed to describe ID fellows\u27 current use of online and social media tools, assess the value of online learning, and identify the educational content preferred by ID fellows. We subsequently convened focus groups with ID fellows to explore how digital tools contribute to fellow learning. RESULTS: A total of 110 ID fellows responded to the survey. Over half were second-year fellows (61, 55%). Although many respondents were satisfied with the educational resources provided by their fellowship program (70, 64%), the majority were interested in an online collaborative educational resource (97, 88%). Twitter was the most popular social media platform for education and the most valued online resource for learning. Focus groups identified several themes regarding social medial learning: broadened community, low barrier to learning, technology-enhanced learning, and limitations of current tools. Overall, the focus groups suggest that fellows value social media and online learning. CONCLUSIONS: ID fellows are currently using online and social media resources, which they view as valuable educational tools. Fellowship programs should consider these resources as complementary to traditional teaching and as a means to augment ID fellow education