Table of Contents

Volume 3, Issue 4

  July/August 2010

  Pages 295 - 391

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VIEW POINT

Open Access Article

Extraversion predicts individual differences in face recognition

Jingguang Li, Moqian Tian, Huizhen Fang, Miao Xu, He Li and Jia Liu
Pages 295 - 298
http://dx.doi.org/10.4161/cib.3.4.12093
Abstract | PDF

In daily life, one of the most common social tasks we perform is to recognize faces. However, the relation between face recognition ability and social activities is largely unknown. Here we ask whether individuals with better social skills are also better at recognizing faces. We found that extraverts who have better social skills correctly recognized more faces than introverts. However, this advantage was absent when extraverts were asked to recognize non-social stimuli (e.g., flowers). In particular, the underlying facet that makes extraverts a better face recognizer was mainly due to the gregariousness facet that measures the degree of inter-personal interaction. In addition, the link between Extraversion and face recognition ability was independent of general cognitive abilities. These findings provide the first evidence that links face recognition ability to our daily activity in social communication, supporting the hypothesis that extraverts are better at decoding social information than introverts.




MINI-REVIEWS

Open Access Article

Gadkin: A novel link between endosomal vesicles and microtubule tracks

Tanja Maritzen and Volker Haucke
Pages 299 - 302
http://dx.doi.org/10.4161/cib.3.4.11835
Abstract | PDF

Different types of endosomal vesicles show distinct distribution patterns within cells. While early endosomes can be found throughout the cell, recycling endosomal vesicles and tubules tend to cluster near the microtubule organizing center in the perinuclear region in most cell types. The molecular mechanisms underlying the steady-state distribution and dynamics of various types of endosomal vesicles has long remained enigmatic. However, during the past decade it has become evident that microtubule-based motor proteins of the kinesin family play a pivotal role in the positioning of endosomes. Early endosomes were shown to cluster in the perinuclear area in the absence of KIF16B,¹ KIF3A is required for the steady-state distribution of late endosomes/lysosomes,²,and KIF13A directs M6PR-containing vesicles from the TGN to the plasma membrane³ to name only a few examples. In the case of Tf-containing recycling endosomes antibody-injection experiments implicated kinesin-1, a heteromer comprised of KIF5 heavy and KLC light chains, as a motor for their transport towards the cell periphery.⁴ Indeed, KIF5B knockdown experiments confirmed that kinesin-1 is necessary to maintain the peripheral pool of recycling endosomes.⁵ But how is kinesin-1 linked to endosomal vesicles? Work from our own laboratory has identified the AP-1-binding protein Gadkin as a molecular link between AP-1-mediated traffic and kinesin-1-based transport along microtubules.⁵ This work as well as hypothetical models for kinesin-dependent endosomal membrane traffic will be discussed here.

Open Access Article

Do invertebrates have culture?

Étienne G.J. Danchin, Simon Blanchet, Frédérick Mery and Richard H. Wagner
Pages 303 - 305
http://dx.doi.org/10.4161/cib.3.4.11970
Abstract | PDF

A recent paper in Current Biology¹ showed for the first time that female invertebrates (Drosophila melanogaster) can perform mate choice copying. Here, we discuss how female mating preferences in this species may be transmitted culturally. If culture occurs in invertebrates, it may be a relatively ancient evolutionary process that may have contributed to the evolution of many different taxa. This would considerably broaden the taxonomic range of cultural processes, and suggest the need to include cultural inheritance in all animals into the general theory of evolution.^2-4

Open Access Article

Emerging roles for tubulin folding cofactors at the centrosome

Mónica López Fanarraga, Gerardo Carranza, Raquel Castaño, Victoria Jiménez, Juan Carlos Villegas and Juan Carlos Zabala
Pages 306 - 308
http://dx.doi.org/10.4161/cib.3.4.11976
Abstract | PDF

Despite its fundamental role in centrosome biology, procentriole formation both in the canonical and in the de novo replication pathways remains poorly understood, and the molecular components that are involved in human cells are not well established. We found that one of the tubulin cofactors, TBCD, is localized at centrosomes and the midbody, and is required for spindle organization, cell abscission, centriole formation, and ciliogenesis. Our studies have established a molecular link between the centriole and the midbody, demonstrating that this cofactor is also necessary for microtubule retraction during cell abscission. TBCD is the first centriolar protein identified that plays a role in the assembly of both “centriolar rosettes” during early ciliogenesis, and at the procentriole budding site by S/G2, a discovery that directly implicates tubulin cofactors in the cell division, cell migration, and cell signaling research fields.

Open Access Article

Heterokairy as an anti-predator strategy for parasitic species

Frédéric B. Muratori
Pages 309 - 312
http://dx.doi.org/10.4161/cib.3.4.11977
Abstract | PDF

Heterokairy refers to plasticity in the timing of onset of developmental events at the level of an individual. When two developmental stages do not share the same ecological niche, referred to as ‘ontogenetic niches’, the control of the niche shift through a change in developmental timing can be advantageous for the individual (e.g. when mortality risk is different in the two niches). Heterokairy can arise either from plasticity in developmental rate (ontogenetic shift) or by a purely behavioural decision (behavioural shift). Parasitic species living inside of their hosts often inherit the predators of their hosts. To cope with the predation risk on their hosts, parasites and parasitoids show either host-manipulation abilities or either host-leaving strategies. Nevertheless, leaving the host should be associated with developmental costs, since the parasitic individuals are usually unable to parasitize another host. This process is thus related to the classical trade-off between size and developmental time. Recent studies provided examples of behavioural heterokairy in invertebrates. The goal of this publication is to review and discuss recent results on developmental plasticity in parasitic species in an evolutionary perspective.




REVIEWS

Open Access Article

Transduction of wound and herbivory signals in plastids

Gustavo Bonaventure and Ian T. Baldwin
Pages 313 - 317
http://dx.doi.org/10.4161/cib.3.4.11834
Abstract | PDF

Plastids are the central orchestrators of the early and late responses to wounding and herbivory in plants. This organelle houses some of the most important enzymes involved in the biogenesis of intra and extracellular signals that mediate defense responses against these stresses. Among these enzymes are the ones initiating the biosynthesis of oxylipins (e.g., jasmonic acid (JA) and C₆ volatiles), terpenoid volatiles and phenolic compounds, including both volatile (e.g., methyl-salicylate (MeSA)) and non-volatile compounds (e.g., salicylic acid (SA)). Plastids also play a major role in orchestrating changes in primary metabolism during herbivory and thereby in the reallocation of carbon and nitrogen to different functions in response to herbivory. How the primary stress signals generated by mechanical damage and herbivory reach the plastid to activate the rapid synthesis of these signal molecules is at present largely unknown.

Open Access Article

A genomic glance at the components of the mRNA export machinery in Plasmodium falciparum

Renu Tuteja and Jatin Mehta
Pages 318 - 326
http://dx.doi.org/10.4161/cib.3.4.11886
Abstract | PDF

Nuclear export of mRNAs is one of the steps critically important for gene expression and different steps of mRNA processing are linked to the export of the mRNA out of the nucleus. This coupling probably provides a quality control mechanism as well as a higher efficiency for the synthesis of mRNAs. The mRNA is synthesized in the nucleus and then exported to the cytoplasm through the nuclear pore complexes (NPCs), which are embedded in the nuclear envelope. The Mex67-Mtr2 complex in yeast and its counterpart Tap-p15 in higher eukaryotes function as an mRNA exporter through the NPC. Some of the DEAD box proteins such as UAP56 and Dbp5 have been implicated in mRNA export also. In this report using the bioinformatics approach we have analyzed the components of the mRNA export machinery in Plasmodium falciparum and also highlighted the salient features of some of the components. Further detailed studies on various components of nuclear mRNA export in Plasmodium falciparum will be essential to understand this important pathway.

Open Access Article

The homeodomain transcription factor Ste12: Connecting fungal MAPK signaling to plant pathogenicity

Nicolas Rispail and Antonio Di Pietro
Pages 327 - 332
http://dx.doi.org/10.4161/cib.3.4.11908
Abstract | PDF

A conserved mitogen-activated protein kinase (MAPK) cascade orthologous to the mating/filamentation MAPK pathway in yeast is required for fungal pathogenicity on plants. One of the key targets of this signaling pathway is the homeodomain transcription factor Ste12. Mutational analysis of ste12 orthologues in a variety of plant pathogenic fungi suggests that Ste12 functions as a master regulator of invasive growth. In this review we highlight recent progress in understanding the role of Ste12 in filamentous fungi and discuss future challenges of unravelling the mechanisms by which Ste12 controls fungal virulence downstream of the Pathogenicity MAPK cascade.




ARTICLE ADDENDA

Open Access Article

Competition-colonization dynamics: An ecology approach to quasispecies dynamics and virulence evolution in RNA viruses

Samuel Ojosnegros, Niko Beerenwinkel and Esteban Domingo
Pages 333 - 336
http://dx.doi.org/10.4161/cib.3.4.11658
Abstract | PDF

A single and purified clone of foot-and-mouth disease virus diversified in cell culture into two subpopulations that were genetically distinct. The subpopulation with higher virulence was a minority and was suppressed by the dominant but less virulent one. These two populations follow the competition-colonization dynamics described in ecology. Virulent viruses can be regarded as colonizers because they killed the cells faster and they spread faster. The attenuated subpopulation resembles competitors because of its higher replication efficiency in coinfected cells. Our results suggest a new model for the evolution of virulence which is based on interactions between components of the quasispecies. Competition between viral mutants takes place at two levels, intracellular competition, and competition for new cells. The two strategies are subjected to density-dependent selection.

Open Access Article

Application of the heterochrony framework to the study of behavior and cognition

Victoria Wobber, Richard Wrangham and Brian Hare
Pages 337 - 339
http://dx.doi.org/10.4161/cib.3.4.11762
Abstract | PDF

Heterochrony, or the evolution of ontogeny, has been well studied in embryology and skeletal development, providing insight into morphological and genetic mechanisms of evolution.^1-5 However, heterochronic studies of behavior and cognition lag behind in comparison. In a recent study we investigated the ontogeny of social behavior and cognition in humans’ closest living relatives, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). These two species are estimated to have had a chimpanzee-like common ancestor between 0.86 and 1.8 mya.^6,7 Bonobos have been argued to exhibit morphological indications of paedomorphism relative to chimpanzees, especially in the cranium, and to exhibit paedomorphic behavior as adults.^6-11 We found that bonobos exhibit developmental delays relative to chimpanzees in several aspects of their social behavior and cognition. Here, we describe how placing these results in the framework of heterochrony contributes to understanding behavioral and cognitive differences between adults of these two species and to our knowledge of hominid evolution in general.

Open Access Article

Neurogranin and synaptic plasticity balance

Ling Zhong and Nashaat Z. Gerges
Pages 340 - 342
http://dx.doi.org/10.4161/cib.3.4.11763
Abstract | PDF

Learning-related modifications of synaptic transmission at CA1 hippocampal excitatory synapses are activity- and NMDA receptor (NMDAR)-dependent. While a postsynaptic increase in Ca2+ is absolutely required for synaptic plasticity induction, the molecular mechanisms underlying the transduction of synaptic signals to postsynaptic changes are not clearly understood. In our recent study, we found that the postsynaptic calmodulin (CaM)-binding protein neurogranin (Ng) enhances synaptic strength in an activity- and NMDAR-dependent manner. Furthermore we have shown that Ng is not only required for the induction of long-term potentiation (LTP), but its mediated synaptic potentiation also mimics and occludes LTP. Our results demonstrate that Ng plays an important role in the regulation of hippocampal synaptic plasticity and synaptic function. Here, we summarize our findings and further discuss their possible implications in aging-related synaptic plasticity deficits.

Open Access Article

Probing novel GPCR interactions using a combination of FRET and TIRF

Stephanie B. Boyer and Paul A. Slesinger
Pages 343 - 346
http://dx.doi.org/10.4161/cib.3.4.11764
Abstract | PDF

Recent work on G-protein coupled receptors (GPCRs) has highlighted the importance of homo- and heterodimerization in all areas of GPCR function, including trafficking, signaling and desensitization. Novel GPCR dimers and even high-order oligomers are constantly being discovered. Advances in techniques such as fluorescent microscopy have improved our ability to detect these interactions. As GPCRs represent the largest class of transmembrane signaling molecules in biology, these new insights into their function could vastly improve our understanding of the complex physiological role GPCRs play in cellular signaling. Utilizing a combination of classic biochemical approaches and newer techniques such as fluorescence resonance energy transfer (FRET) and total internal reflection fluorescence microscopy (TIRF), we recently demonstrated a novel interaction between M₂ muscarinic receptors and GABA_B receptors. In this addendum, we address technical aspects of combining FRET and TIRF to study GPCR interactions and further discuss the physiological implications of the M₂-GABA_B heterodimer.

Open Access Article

SynDIG1 regulation of synaptic AMPA receptor targeting

Elva Díaz
Pages 347 - 349
http://dx.doi.org/10.4161/cib.3.4.11765
Abstract | PDF

Excitatory synapses are composed of several specialized domains including the presynaptic bouton containing several hundred synaptic vesicles (SVs), the presynaptic active zone where SVs dock and fuse with the plasma membrane, and the juxtaposed postsynaptic density (PSD) composed of an electron dense meshwork of proteins including NMDA and AMPA receptors, ion channels, and various signaling components. Cell adhesion molecules (CAMs) extend across the synaptic cleft to stabilize this macromolecular complex. During development of the central nervous system (CNS), certain CAMs also serve as inductive signals that trigger the establishment of pre- and postsynaptic specializations.^1-4 Early events in synapse development include clustering of SVs to the active zone and NMDA receptors to the PSD, whereas later events include targeting of AMPA receptors and synaptic activity that might direct whether synapses will be stabilized, eliminated or strengthened. Regulating the number of AMPA receptors located at the PSD is a key mechanism underlying synaptic strength and plasticity implicated in learning and memory.^5-10 Thus, a current avenue of investigation is the identification of interacting proteins that influence targeting of synaptic AMPA receptors. The discovery that the transmembrane protein stargazin controls synaptic AMPA-R targeting represented a major paradigm shift in the field.¹¹ My colleagues and I recently reported the discovery of a novel type II transmembrane protein SynDIG1 (Synapse Differentiation Induced Gene I) that functions as a critical regulator of excitatory synapse development in dissociated rat hippocampal neurons.¹² Specifically, knock-down of SynDIG1 in cultured neurons reduces AMPA receptor content at developing synapses by ~50% as determined by immunocytochemistry and electrophysiology.¹² The magnitude of this effect matches that of TARPs and PSD-95 identifying SynDIG1 as a previously unknown central regulator of postsynaptic AMPA receptor targeting. In this addendum I further discuss the implications of these data.

Open Access Article

The natural selection of fidelity in social learning

Nicolas Claidière and Dan Sperber
Pages 350 - 351
http://dx.doi.org/10.4161/cib.3.4.11829
Abstract | PDF

Social learning mechanisms are usually assumed to explain both the spread and the persistence of cultural behavior. In a recent article, we showed that the fidelity of social learning commonly found in transmission chain experiments is not high enough to explain cultural stability. Here we want to both enrich and qualify this conclusion by looking at the case of song transmission in song birds, which can be faithful to the point of being true replication. We argue that this high fidelity results from natural selection pressure on cognitive mechanisms. This observation strengthens our main argument. Social learning mechanisms are unlikely to be faithful enough to explain cultural stability because they are generally selected not for high fidelity but for generalization and adjustment to the individual’s needs, capacities and situation.

Open Access Article

Cholesterol and synaptic vesicle exocytosis

Patrizia Rosa and Alessandra Fratangeli
Pages 352 - 353
http://dx.doi.org/10.4161/cib.3.4.11831
Abstract | PDF

Lipids may affect synaptic function in at least two ways: by acting as ligands for effector proteins (e.g. phosphatidylinositol (4,5) bisphosphate, diacylglycerol-mediated signalling) or by modifying the physicochemical properties and molecular organisation of synaptic membranes. One that acts in the latter manner is cholesterol, an essential structural component of plasma membranes that is largely enriched in the membranes of synapses and synaptic vesicles, in which it may be involved in lipid-lipid and protein-lipid interactions. Cholesterol is an important constituent of the “membrane rafts” that may play a role in recruiting and organising the specific proteins of the exocytic pathways. Furthermore, many synaptic proteins bind directly to cholesterol. The regulation of cholesterol and lipid levels may therefore influence the specific interactions and activity of synaptic proteins, and have a strong impact on synaptic functions.

Open Access Article

Scaffolding proteins and non-proliferative functions of ERK1/2

Sarah Appel and Kathleen G. Morgan
Pages 354 - 356
http://dx.doi.org/10.4161/cib.3.4.11832
Abstract | PDF

Studies of ERK1/2 generally focus on the regulation of nuclear ERK1/2 function mainly related to proliferation, whereas less attention has been drawn to the role ERK1/2 plays in the cytosol. Scaffolding proteins for ERK1/2 have been shown to control the time point and also the intracellular location of ERK1/2 activation. Hence, by concentrating ERK1/2 within subcellular compartments, scaffolding proteins restrict the substrate specificity of ERK1/2 and thus optimize the cell response for specific signal transduction programs in order to manipulate specific cellular functions. We have presented evidence that the F-actin binding protein calponin represents a new type of ERK1/2 scaffold, controlling the activation of a subfraction of ERK1/2 which is connected solely to contractile and/or migratory events in a cell.

Open Access Article

Addiction-like behavior in Drosophila

Anita V. Devineni and Ulrike Heberlein
Pages 357 - 359
http://dx.doi.org/10.4161/cib.3.4.11885
Abstract | PDF

Alcohol abuse is a pervasive problem known to be influenced by genetic factors, yet our understanding of the mechanisms underlying alcohol addiction is far from complete. Drosophila melanogaster has been established as a model for studying the molecular mechanisms that mediate the acute and chronic effects of alcohol. However, the Drosophila model has not yet been extended to include more complex alcohol-related behaviors such as self-administration. We recently established a paradigm to characterize ethanol consumption and preference in flies. We demonstrated that flies prefer to consume ethanol-containing food over regular food, and this preference exhibits several features of alcohol addiction: flies increase ethanol consumption over time, they consume ethanol to pharmacologically relevant concentrations, they will overcome an aversive stimulus in order to consume ethanol, and they exhibit relapse after a period of ethanol deprivation. Thus, ethanol preference in flies provides a new model for studying important aspects of addiction and their underlying mechanisms. One mutant that displayed decreased ethanol preference, krasavietz, may represent a first step toward uncovering those mechanisms.

Open Access Article

Eusocial insects as superorganisms: insights from metabolic theory

James F. Gillooly, Chen Hou and Michael Kaspari
Pages 360 - 362
http://dx.doi.org/10.4161/cib.3.4.11887
Abstract | PDF

We recently published a paper titled “Energetic Basis of Colonial Living in Social Insects” showing that basic features of whole colony physiology and life history follow virtually the same size-dependencies as unitary organisms when a colony’s mass is the summed mass of individuals. We now suggest that these results are evidence, not only for the superorganism hypothesis, but also for colony level selection. In addition, we further examine the implications of these results for the metabolism and lifetime reproductive success of eusocial insect colonies. We conclude by discussing the mechanisms which may underlie the observed mass-dependence of survival, growth and reproduction in these colonies.

Open Access Article

A model for the biogenesis of Turnip mosaic virus replication factories

Romain Grangeon, Sophie Cotton and Jean-François Laliberté
Pages 363 - 365
http://dx.doi.org/10.4161/cib.3.4.11968
Abstract | PDF

Nicotiana benthamiana plants were agroinfiltrated with an infectious clone of the Turnip mosaic virus (TuMV) that was engineered to tag replication vesicles with either GFP or mCherry fluorescent proteins. Punctuate vesicle structures were observed in the cytoplasm of infected cells corresponding to viral replication factories. The vesicles were highly motile and co-aligned with the microfilaments. Utilization of latrunculin B, an inhibitor of microfilament polymerization, reduced accumulation of the virus, suggesting that microfilaments are necessary during infection. To investigate biogenesis of the vesicles, leaves were infected simultaneously with two recombinant TuMV infectious clones, one that labeled vesicles in red and one that labeled them in green. We observed cell with green only and red only vesicles indicating a single viral genome origin. In some cases, vesicles exhibited sectors of green, red, and yellow fluorescence were also observed, demonstrating that fusion among individual vesicles is possible. Based on those results we propose a model for the biogenesis of viral factory, where viral translation and replication are tightly coupled within virus-induced vesicles.

Open Access Article

Direct internalization of cell-surface BST-2/tetherin by the HIV-1 accessory protein Vpu

Yukie Iwabu, Hideaki Fujita, Yoshitaka Tanaka, Tetsutaro Sata and Kenzo Tokunaga
Pages 366 - 369
http://dx.doi.org/10.4161/cib.3.4.11971
Abstract | PDF

The host transmembrane protein BST-2/tetherin is a powerful antiviral factor that blocks the production of enveloped viruses. The HIV-1 accessory protein Vpu inhibits the antiviral activity of BST-2; however, the degradation pathway by which Vpu downregulates BST-2 from the cell surface and the actual subcellular location where Vpu targets BST-2 for downregulation remain controversial. Whereas one study showed that Vpu acts on constitutively endocytosed BST-2, we recently reported that Vpu can internalize BST-2 from the cell surface. Because the evidence for this conclusion was derived from indirect results, we present direct evidence in this study using an antibody internalization assay with an endocytosis-defective mutant of BST-2. The internalization of the BST-2 protein into cells coexpressing wild-type Vpu was observed when the cells were preincubated with antibodies against BST-2 at 37˚C, but not at 4˚C, for 10 min. These results strongly support our previous finding that continuously expressed de novo BST-2 at the cell surface is internalized by functional Vpu protein.

Open Access Article

Multicolor bleach-rate imaging enlightens in vivo sterol transport

Daniel Wüstner and Daniel Sage
Pages 370 - 373
http://dx.doi.org/10.4161/cib.3.4.11972
Abstract | PDF

Elucidation of in vivo cholesterol transport and its aberrations in cardiovascular diseases requires suitable model organisms and the development of appropriate monitoring technology. We presented recently a new approach to visualize transport of the intrinsically fluorescent sterol, dehydroergosterol (DHE) in the genetically tractable model organism Caenorhabditis elegans (C. elegans). DHE is structurally very similar to cholesterol and ergosterol, two sterols used by the sterol-auxotroph nematode. We developed a new computational method measuring fluorophore bleaching kinetics at every pixel position, which can be used as a fingerprint to distinguish rapidly bleaching DHE from slowly bleaching autofluorescence in the animals. Here, we introduce multicolour bleach-rate sterol imaging. By this method, we demonstrate that some DHE is targeted to a population of basolateral recycling endosomes (RE) labelled with GFP-tagged RME-1 (GFP-RME- 1) in the intestine of both, wild-type nematodes and mutant animals lacking intestinal gut granules (glo1-mutants). DHE-enriched intestinal organelles of glo1-mutants were decorated with GFPrme8, a marker for early endosomes. No co-localization was found with a lysosomal marker, GFPLMP1. Our new methods hold great promise for further studies on endosomal sterol transport in C. elegans.

Open Access Article

On classical and quantum error-correction in ciliate mate selection

Kevin B. Clark
Pages 374 - 378
http://dx.doi.org/10.4161/cib.3.4.11974
Abstract | PDF

Ciliated protozoa sensing pheromones secreted from nonself mating types engage in preconjugal “courtship” dances and contacts. Using simulated “social” trials, I recently showed the heterotrich ciliate, Spirostomum ambiguum, can learn to advertise degrees of mating fitness to “suitors” and “rivals” when serially contracting or (ciliary) reversing at variable rates. Conspicuous consumers signal higher quality reproductive status by playing “harder-to-get” via metabolically wasteful avoidance displays that hinder the exchange of preconjugal touches between “courting” couples. Conversely, prudent savers conserve energy pending situations more favorable for conjugating a partner. These ciliates reply with lower avoidance frequencies, guaranteeing nearby conspecifics of being “easier-to-get”. By deciding to switch from behavioral strategies signaling conspicuous consumption to those signaling prudent savings, fitter ciliates learn to altruistically sacrifice net payoffs and persuade suitors to participate in paired reproduction. Less fit ciliates, unable to sustain long periods of high response rates, switch their behavioral strategies of prudent savings to briefly emit conspicuous consumption and thus learn to opportunistically cheat superior rivals. Mating competency depends, in part, on the efficiency of heuristics formed from recursive strategy searches and use. Heuristics represent stored patterns of action which evolve into ordered computational networks supporting entire courting repertoires. As ciliates expand signaling skills over many trials, the connectivity between strategies strengthens from Hebbian-like learning, leading to faster decisions about the appropriateness of courting messages and replies. The best experts master signaling decisions at efficiencies comparable to finding target solutions from superposed states with Grover’s quantum search algorithm. I here append these findings with a critique on the feasibility of serial behavioral strategies to perfect ciliate mate selection via classical repetition and quantum bit-flip error-correction codes that safeguard transmitted social information from noise and might be exploited for signal encryption.

Open Access Article

Vestibular deficits do not underlie looping behavior in achiasmatic fish

Ying-Yu Huang, Markus Tschopp, Dominik Straumann and Stephan C.F. Neuhauss
Pages 379 - 381
http://dx.doi.org/10.4161/cib.3.4.11975
Abstract | PDF

Zebrafish belladonna (bel) mutants carry a mutation in the lhx2 gene that encodes a Lim domain homeobox transcription factor, leading to a defect in the retinotectal axon pathfinding. As a result, a large fraction of homozygous bel mutants is achiasmatic. Achiasmatic bel mutants display ocular motor instabilities, both reserved optokinetic response (OKR) and spontaneous eye oscillations, and an unstable swimming behavior, described as looping. All these unstable behaviors have been linked to the underlying optic nerve projection defect. Looping has been investigated under different visual stimuli and shown to be vision dependent and contrast sensitive. In addition, looping correlates perfectly with reversed OKR and the spontaneous oscillations of the eyes. Hence, it has been hypothesized that looping is a compensatory response to the perception of self-motion induced by the spontaneous eye oscillations. However, both ocular and postural instabilities could also be caused by a yet unidentified vestibular deficit. In this paper, we performed a preliminary test of the vestibular function in achiasmatic bel larval mutants in order to clarify the potential role of a vestibular deficit in looping. We found that the vestibular ocular reflex (VOR) is normally directed in both bel mutants and wild types and therefore exclude the possibility that nystagmus and looping in reverse to the rotating optokinetic drum can be attributed to an underlying vestibular deficit.

Open Access Article

Shedding light on the role of photosynthesis in pathogen colonization and host defense

Betiana S. Garavaglia, Ludivine Thomas, Natalia Gottig, Tamara Zimaro, Cecilia G. Garofalo, Chris Gehring and Jorgelina Ottado
Pages 382 - 384
http://dx.doi.org/10.4161/cib.3.4.12029
Abstract | PDF

The role of photosynthesis in plant defense is a fundamental question awaiting further molecular and physiological elucidation. To this end we investigated host responses to infection with the bacterial pathogen Xanthomonas axonopodis pv. citri, the pathogen responsible for citrus canker. This pathogen encodes a plant-like natriuretic peptide (XacPNP) that is expressed specifically during the infection process and prevents deterioration of the physiological condition of the infected tissue. Proteomic assays of citrus leaves infected with a XacPNP deletion mutant (∆XacPNP) resulted in a major reduction in photosynthetic proteins such as Rubisco, Rubisco activase and ATP synthase as a compared with infection with wild type bacteria. In contrast, infiltration of citrus leaves with recombinant XacPNP caused an increase in these host proteins and a concomitant increase in photosynthetic efficiency as measured by chlorophyll fluorescence assays. Reversion of the reduction in photosynthetic efficiency in citrus leaves infected with ∆XacPNP was achieved by the application of XacPNP or Citrus sinensis PNP lending support to a case of molecular mimicry. Finally, given that ∆XacPNP infection is less successful than infection with the wild type, it appears that reducing photosynthesis is an effective plant defense mechanism against biotrophic pathogens.

Open Access Article

Cellular machinery to fuse antimicrobial autophagosome with lysosome

Nobumichi Furuta and Atsuo Amano
Pages 385 - 387
http://dx.doi.org/10.4161/cib.3.4.12030
Abstract | PDF

Autophagy is an intracellular bulk degradation/recycling system that turns over cellular constituents and also functions to degrade intracellular foreign microbial invaders by a process termed xenophagy (antimicrobial autophagy). We previously showed that intracellular group A Streptococcus (GAS) organisms are captured by xenophagosomes, then degraded following fusion with lysosomes. Very recently, we analyzed the molecular mechanism underlying xenophagosome/lysosome fusion and found that endocytic soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are involved. Knockdown of the combinational SNARE proteins Vti1b and VAMP8 with siRNAs disturbed autophagic fusion with lysosomes, and cellular bactericidal efficiency was significantly diminished. Furthermore, knockdown of those SNAREs inhibited the fusion of canonical autophagosomes with lysosomes. In addition, important findings showed that Vti1b is derived from autophagic compartments, whereas VAMP8 originates from lysosomes. Together, these results strongly suggest that SNARE proteins Vti1b and VAMP8 mediate the fusion of antimicrobial and canonical autophagosomes with lysosomes, an essential event for autophagic degradation.

Open Access Article

Both nymphs and adults of the maize orange leafhopper induce galls on their host plant

Keiichiro Matsukura, Masaya Matsumura and Makoto Tokuda
Pages 388 - 389
http://dx.doi.org/10.4161/cib.3.4.12031
Abstract | PDF

The maize orange leafhopper, Cicadulina bipunctata is a multivoltine insect that induces galls on various plants of the Poaceae. A previous study revealed that galls produced by this leafhopper were induced by dose-dependent stimulation on distant leaves from the feeding site, probably by chemical(s) injected from adults during feeding. In this paper, we examined the gall-inducing ability of C. bipunctata nymphs. The degree of gall induction gradually increased depending on the number of feeding nymphs and there were no significant differences from the positive control (feeding by five male adults) when seedlings were exposed to five or more nymphs. These results indicate that both adults and nymphs of C. bipunctata have the ability to induce galls on their host plants, a unique feature among gall-inducing insects. This feature may be related to the free-living, multivoltine, and polyphagous habits of C. bipunctata.

Open Access Article

Intracellular cryptococci suppress Fc-mediated cyclin D1 elevation

Yong Luo and Arturo Casadevall
Pages 390 - 391
http://dx.doi.org/10.4161/cib.3.4.12090
Abstract | PDF

Cryptococcus neoformans (Cn) is the only encapsulated fungal pathogen pathogenic to humans and macrophages play a vital role in the Cn infection pathway. Previously we documented that phagocytosis or crosslinking of FcγR on macrophage cell surface promoted macrophage cell cycle progression via the activation of MAPK pathway. However, we seldom observed sustained macrophage growth after they phagocytosed live Cn. In fact, many macrophages were finally observed to undergo apoptotic changes after phagocytosis of live Cn. Here we report that cyclin D1 elevation in macrophages promoted by phagocytosis was suppressed by intracellular Cn cells. This suggests a novel cytotoxic mechanism for host cells of intracellular cryptococci.