Showing papers in "Communicative & Integrative Biology in 2015"
TL;DR: The features, function and widespread occurrence of EPs among metabolosomes are reviewed, and an expanded role for EPs in the assembly of diverse BMCs is proposed.
Abstract: Bacterial microcompartments (BMCs) are proteinaceous organelles used by a broad range of bacteria to segregate and optimize metabolic reactions. Their functions are diverse, and can be divided into anabolic (carboxysome) and catabolic (metabolosomes) processes, depending on their cargo enzymes. The assembly pathway for the β-carboxysome has been characterized, revealing that biogenesis proceeds from the inside out. The enzymes coalesce into a procarboxysome, followed by encapsulation in a protein shell that is recruited to the procarboxysome by a short (∼17 amino acids) extension on the C-terminus of one of the encapsulated proteins. A similar extension is also found on the N- or C-termini of a subset of metabolosome core enzymes. These encapsulation peptides (EPs) are characterized by a primary structure predicted to form an amphipathic α-helix that interacts with shell proteins. Here, we review the features, function and widespread occurrence of EPs among metabolosomes, and propose an expanded role for EPs in the assembly of diverse BMCs.
63 citations
TL;DR: This study provides the first evidence that oxytocin promotes social play in the domestic dog, and uses these results to hypothesize on the potential therapeutic use of Oxytocin for promoting social behaviors and treating social deficits in the Domestic dog.
Abstract: In a recent paper,(1) we examined whether oxytocin in the domestic dog modulates the maintenance of close social bonds in non-reproductive contexts. We found that exogenous oxytocin promotes positive social behaviors not only toward conspecifics, but also toward human partners. Here we examined in further detail the effect that oxytocin manipulation has on social play. When sprayed with oxytocin, subjects initiated play sessions more often and played for longer periods of time than when sprayed with saline. Furthermore, after oxytocin nasal intake dogs displayed play signals more often than after saline administration, suggesting that oxytocin enhances dogs' play motivation. To our knowledge, this study provides the first evidence that oxytocin promotes social play in the domestic dog. We use these results to hypothesize on the potential therapeutic use of oxytocin for promoting social behaviors and treating social deficits in the domestic dog.
49 citations
TL;DR: The evolutionary analysis is extended to MICOS-interacting proteins (e.g., Sam50, Mia40, DNAJC11, DISC-1, QIL1, Aim24, and Cox17) and discusses the implications for both derived and ancestral functions of MICOS.
Abstract: The MItochondrial Contact Site and Cristae Organizing System (MICOS) is required for the biogenesis and maintenance of mitochondrial cristae as well as the proper tethering of the mitochondrial inner and outer membranes. We recently demonstrated that the core components of MICOS, Mic10 and Mic60, are near-ubiquitous eukaryotic features inferred to have been present in the last eukaryote common ancestor. We also showed that Mic60 could be traced to α-proteobacteria, which suggests that mitochondrial cristae evolved from α-proteobacterial intracytoplasmic membranes. Here, we extend our evolutionary analysis to MICOS-interacting proteins (e.g., Sam50, Mia40, DNAJC11, DISC-1, QIL1, Aim24, and Cox17) and discuss the implications for both derived and ancestral functions of MICOS.
44 citations
TL;DR: relevant data in regenerating planaria, metamorphosing insects, and hibernating ground squirrels is discussed, which will have important implications for cognitive science, regenerative medicine of the brain, and the development of non-traditional computational media in synthetic bioengineering.
Abstract: One of the most important features of the nervous system is memory: the ability to represent and store experiences, in a manner that alters behavior and cognition at future times when the original stimulus is no longer present. However, the brain is not always an anatomically stable structure: many animal species regenerate all or part of the brain after severe injury, or remodel their CNS toward a new configuration as part of their life cycle. This raises a fascinating question: what are the dynamics of memories during brain regeneration? Can stable memories remain intact when cellular turnover and spatial rearrangement modify the biological hardware within which experiences are stored? What can we learn from model species that exhibit both, regeneration and memory, with respect to robustness and stability requirements for long-term memories encoded in living tissues? In this Perspective, we discuss relevant data in regenerating planaria, metamorphosing insects, and hibernating ground squirrels. While much remains to be done to understand this remarkable process, molecular-level insight will have important implications for cognitive science, regenerative medicine of the brain, and the development of non-traditional computational media in synthetic bioengineering.
42 citations
TL;DR: Time-related expression profiles for HSP40 and HSP70 indicated rapid (<30 min) induction for both transcripts, which indicated the effect of thermal stress on HSP gene expression in the nervous system was investigated.
Abstract: Organisms exposed to environmental stressors respond by rapidly synthesising a suite of highly conserved proteins called heat shock proteins (HSPs). Environmental stress can also enhance and/or block memory formation, with long-term memory formation requiring gene activation and protein synthesis. Thermal stress in the pond snail Lymnaea stagnalis can enhance memory formation, and, in this study, the effect of thermal stress on HSP gene expression in the nervous system was investigated. Time-related expression profiles for HSP40 and HSP70 indicated rapid ( 100 fold and expression did not return to control levels within 8 h.
35 citations
TL;DR: The plasmodium of slime mold Physarum polycephalum behaves as an amorphous reaction-diffusion computing substrate and is capable of apparently ‘intelligent’ behavior, but how does intelligence emerge in an acellular organism?
Abstract: The plasmodium of slime mold Physarum polycephalum behaves as an amorphous reaction-diffusion computing substrate and is capable of apparently 'intelligent' behavior. But how does intelligence emerge in an acellular organism? Through a range of laboratory experiments, we visualize the plasmodial cytoskeleton-a ubiquitous cellular protein scaffold whose functions are manifold and essential to life-and discuss its putative role as a network for transducing, transmitting and structuring data streams within the plasmodium. Through a range of computer modeling techniques, we demonstrate how emergent behavior, and hence computational intelligence, may occur in cytoskeletal communications networks. Specifically, we model the topology of both the actin and tubulin cytoskeletal networks and discuss how computation may occur therein. Furthermore, we present bespoke cellular automata and particle swarm models for the computational process within the cytoskeleton and observe the incidence of emergent patterns in both. Our work grants unique insight into the origins of natural intelligence; the results presented here are therefore readily transferable to the fields of natural computation, cell biology and biomedical science. We conclude by discussing how our results may alter our biological, computational and philosophical understanding of intelligence and consciousness.
34 citations
TL;DR: The recent research suggests an alternative hypothesis, namely a change in reward orientation, from a short-term materialistic orientation to a long-term spiritual one, in the Axial Age.
Abstract: The 'Axial Age' (500-300 BCE) refers to the period during which most of the main religious and spiritual traditions emerged in Eurasian societies. Although the Axial Age has recently been the focus of increasing interest,(1-5) its existence is still very much in dispute. The main reason for questioning the existence of the Axial Age is that its nature, as well as its spatial and temporal boundaries, remain very much unclear. The standard approach to the Axial Age defines it as a change of cognitive style, from a narrative and analogical style to a more analytical and reflective style, probably due to the increasing use of external memory tools. Our recent research suggests an alternative hypothesis, namely a change in reward orientation, from a short-term materialistic orientation to a long-term spiritual one.(6) Here, we briefly discuss these 2 alternative definitions of the Axial Age.
31 citations
TL;DR: It is proposed that at least 3 major signaling pathways for land plant hormone response are functional in Klebsormidiophyceae, including auxin mediated signal transduction and jasmonic acid only the receptor JAR1 was found, but the further steps were absent in the analyzed K. crenulatum transcriptome.
Abstract: The origin of phytohormones has been a puzzling question for decades; however, with the availability of large transcriptomic and genomic datasets of the early branching streptophytic green alga Klebsormidium this question can be addressed from a fresh perspective. Klebsormidium has recently been examined extensively for physiological and structural reactions to desiccation or cold temperatures, natural factors in soil crust living algae. Ecological influences have been made responsible for fine scaled structuring of genotypes and differentiation of cryptic species. But how do these organisms sense their changing environments? In this addendum article, we explore our own data set from a transcriptomic study of severe desiccation stress in Klebsormidium crenluatum. The cells were desiccated for 2.5 h under monitored conditions over silicagel at »10% relative humidity. The relative water content of the desiccated cells was 6.54 § 1.89%. For the molecular analysis we established a high-coverage reference transcriptome database which contained 24,183 contigs with a mean sequence length of 1,327b (N50 D 1,462). This database was used to evaluate which phytohormone pathways are present in Klebsormidium and might be involved for cellular response to desiccation stress. Desiccation is well studied in embryophytes, and the cytokinin, ethylene and abscisic acid (ABA) signaling pathways have been implicated in stress response. Given these facts we wondered whether ABA and/or ethylene and/or cytokinin signaling are involved in desiccation tolerance in K. crenulatum, and searched for the most similar transcripts to the K. flaccidum proteins reported to be putative orthologues of these 3 (ABA, cytokinin, ethylene) plant phytohormones signaling components. Here, we propose that at least 3 major signaling pathways for land plant hormone response are functional in Klebsormidiophyceae. Based on our transcriptomic data of severe desiccation stress auxin mediated signal transduction seem to be missing and in the case of jasmonic acid (JA) only the receptor JAR1 was found, but the further steps were absent in the analyzed K. crenulatum transcriptome.
30 citations
TL;DR: Exposure of tomato plants to volatile chemicals emitted from common cutworm (Spodoptera litura)-infested conspecifics led to accumulation of the glycoside, (Z)-3-hexenyl vicianoside, suggesting that Arabidopsis might convert a broad range of volatile alcohols into the corresponding glucosides.
Abstract: Exposure of tomato plants to volatile chemicals emitted from common cutworm (Spodoptera litura)-infested conspecifics led to accumulation of the glycoside, (Z)-3-hexenyl vicianoside. Accumulation of (Z)-3-hexenyl vicianoside in the exposed plants has adverse impacts on the performance of the common cutworms. The aglycon of (Z)-3-hexenyl vicianoside is derived from airborne (Z)-3-hexenol emitted from infested plants. The ability to incorporate and convert (Z)-3-hexenol to its corresponding glycoside is widely conserved in an array of plant species. However, the specificity of this ability to discriminate between the chemical structures of different volatile alcohols remains unknown. In this study, we investigated glycosylation of several volatile alcohols in Arabidopsis (Arabidopsis thaliana). The exposure of Arabidopsis to a variety of volatile alcohols, (Z)-2-pentenol, (Z)-3-hexenol, (Z)-3-heptenol, (Z)-3-octenol, (Z)-3-nonenol, cyclohexanol, benzyl alcohol, verbenol, perillyl alcohol, myrtenol, geraniol, or linalool led to the detection of the putative corresponding glucosides. These results suggest that Arabidopsis might convert a broad range of volatile alcohols into the corresponding glucosides.
27 citations
TL;DR: An attempt has been made to highlight a few relevant developments supporting a sentient view of life in scientific research, which has caused a paradigm shift in the authors' understanding of life and its origin.
Abstract: In the past, philosophers, scientists, and even the general opinion, had no problem in accepting the existence of consciousness in the same way as the existence of the physical world. After the advent of Newtonian mechanics, science embraced a complete materialistic conception about reality. Scientists started proposing hypotheses like abiogenesis (origin of first life from accumulation of atoms and molecules) and the Big Bang theory (the explosion theory for explaining the origin of universe). How the universe came to be what it is now is a key philosophical question. The hypothesis that it came from Nothing (as proposed by Stephen Hawking, among others), proves to be dissembling, since the quantum vacuum can hardly be considered a void. In modern science, it is generally assumed that matter existed before the universe came to be. Modern science hypothesizes that the manifestation of life on Earth is nothing but a mere increment in the complexity of matter - and hence is an outcome of evolution of matter (chemical evolution) following the Big Bang. After the manifestation of life, modern science believed that chemical evolution transformed itself into biological evolution, which then had caused the entire biodiversity on our planet. The ontological view of the organism as a complex machine presumes life as just a chance occurrence, without any inner purpose. This approach in science leaves no room for the subjective aspect of consciousness in its attempt to know the world as the relationships among forces, atoms, and molecules. On the other hand, the Vedāntic view states that the origin of everything material and nonmaterial is sentient and absolute (unconditioned). Thus, sentient life is primitive and reproductive of itself - omne vivum ex vivo - life comes from life. This is the scientifically verified law of experience. Life is essentially cognitive and conscious. And, consciousness, which is fundamental, manifests itself in the gradational forms of all sentient and insentient nature. In contrast to the idea of objective evolution of bodies, as envisioned by Darwin and followers, Vedānta advocates the idea of subjective evolution of consciousness as the developing principle of the world. In this paper, an attempt has been made to highlight a few relevant developments supporting a sentient view of life in scientific research, which has caused a paradigm shift in our understanding of life and its origin.
27 citations
TL;DR: Current understanding of performance on the Aesop's Fable tasks is reviewed, and it is suggested that studies controlling for feedback and object preferences will help to determine exactly what animals understand about the cause and effect of water displacement.
Abstract: The Aesop's Fable paradigm - in which subjects drop stones into tubes of water to obtain floating out-of-reach rewards - has been used to assess causal understanding in rooks, crows, jays and human children. To date, the performance of corvids suggests that they can recognize the functional properties of a variety of objects including size, weight and solidity, and they seem to be more capable of learning from causal information than arbitrary information. However, 2 alternative explanations for their performance have yet to be ruled out. The perceptual-motor feedback hypothesis suggests that subjects may attend solely to the movement of the reward, repeating actions which bring the reward closer, while the object-bias hypothesis suggests that subjects could pass certain tasks by preferring to handle objects that resemble natural stones. Here we review our current understanding of performance on the Aesop's Fable tasks, and suggest that studies controlling for feedback and object preferences will help us determine exactly what animals understand about the cause and effect of water displacement.
TL;DR: This addendum focuses on changes in Bradyrhizobium during soybean growth, suggesting that soybean plants select for symbiotic partners.
Abstract: Soybean is an important crop, with processed soybeans being the second largest source of vegetable oil and the largest source of animal protein feed in the world. Nodules on soybean roots are responsible for symbiotic nitrogen fixation, enabling soybean plants to obtain sufficient nitrogen for growth and seed production. Because nitrogen is an essential, but often limiting, nutrient for plant growth, improvements in nitrogen fixation are highly required in agriculture. We recently reported a comprehensive analysis of rhizosphere bacterial communities during soybean growth in a field in Kyoto prefecture, Japan. The bacterial communities of the rhizosphere changed significantly during growth, with potential plant growth-promoting rhizobacteria, including Bacillus, Bradyrhizobium, and Rhizobium, increasing in a stage-specific manner. In this addendum, we focus on changes in Bradyrhizobium during soybean growth, suggesting that soybean plants select for symbiotic partners.
TL;DR: The extent to which the Orch OR hypothesis is applicable to plants is examined, and it is argued that, within the plant body, the most likely tissue where OR events could be located and promote protoconsciousness is to be found in the system of ray cells of tree trunks in which bundled MTs and actin filaments are prevalent.
Abstract: Whether or not plants exhibit consciousness in the sense that they possess a ‘sensation of self’ is uncertain. Unlike humans and certain animals, plants cannot be interrogated directly on this matter. In any case, it is possible that states of consciousness, like brains and nervous systems of animals, have evolved and developed in different ways, depending on their phylogeny. However, some of the criteria by which consciousness is inferred to be present in animals are met by plants. For example, plants display features of cognition (sensing and response) and of learning and memory which, in animals, contribute to the conscious state. Plants also possess a rudimentary nervous system similar to that found in basal animals and have, perhaps, a simple brain, as well as showing slow and fast transmissable electrical activity, all of which are strong correlates of consciousness in animals. However, the question of consciousness in general can be approached in a different way. This is by taking the Orch OR (Orchestrated Objective Reduction) hypothesis of Hameroff and Penrose as a starting point. The Orch OR hypothesis, which is based in quantum physics, proposes that, when a sufficient mass of tubulin molecules has assembled into cytoskeletal microtubules (MTs) within neuronal cells of the brain, these structures become sites of quantum computation and of quantum state reduction (OR) events resulting in moments of protoconsciousness. Because plant cells also have large populations of MTs, and because plant MTs share properties with those of animal neuronal MTs, which putatively orchestrate OR events, plant MTs might also be sites of quantum reduction events and, hence, lead to momentary protoconsciousness. The extent to which the Orch OR hypothesis is applicable to plants is examined, and it is argued that, within the plant body, the most likely tissue where OR events could be located and promote protoconsciousness is to be found in the system of ray cells of tree trunks in which bundled MTs and actin filaments are prevalent. A single complete ray complex is estimated to contain about as many tubulin molecules as a single human cerebral neuron. Inferential evidence used by Hameroff and Penrose to support their Orch OR hypothesis leads in another direction. These authors presented estimates of the frequency of protoconscious or conscious moments. This frequency turns out to be similar to the frequency of successive Earthly quantal time units, according to a theory proposed by G. Dorda. These time units are also intimately linked with simultaneous changes of quantal mass, both mass and time being structured according to the motions of Earth and Moon around the Sun. In the case of cellular tissues, quantised mass takes the form of aggregates of water, and these are hypothesized to move in and out of cells in response to the passage of quantal time. In humans, the passage of time and its association with quantised water flux might account for a sense of self gained during meditative practices and govern also sleep-wakefulness rhythms, a principle which could apply to all living organisms. In plants, a similar quantised
TL;DR: The findings suggest that stress during adolescence can prepare rats to better function under future threat, which supports hypotheses describing an adaptive role for the long-term consequences of early stress (e.g. the thrifty phenotype and maternal mismatch hypotheses).
Abstract: Recently we have shown that adult rats exposed to chronic stress during adolescence increase foraging performance in high-threat conditions by 43% compared to rats reared without stress. Our findings suggest that stress during adolescence can prepare rats to better function under future threat, which supports hypotheses describing an adaptive role for the long-term consequences of early stress (e.g. the thrifty phenotype and maternal mismatch hypotheses). These hypotheses often predict that early stress will impair performance in low-threat conditions later in life. However, we did not find any difference in performance under low-threat conditions between adolescent-stressed and unstressed adult animals. To understand why stress during adolescence may affect performance in high-threat but not in low-threat conditions, we discuss our findings in the framework of the Yerkes-Dodson law, a key precept of psychology that has been used for over a century to describe how stress affects performance.
TL;DR: Comparison ofMEF2A and MEF2C genome-wide mapping in mouse cortical neurons by ChIP-seq reveals that MEF1 A and MEf2C each orchestrate similar epigenomic programs mainly through the binding of enhancer regulatory elements in proximity of target genes involved in neuronal plasticity and calcium signaling.
Abstract: The transcription factors of the myocyte enhancer factor 2 family (MEF2 A-D) are highly expressed in the brain and play a key role in neuronal survival/apoptosis, differentiation and synaptic plasticity. However, the precise genome-wide mapping of different members of the family has not yet been fully elucidated. Here, we report the comparative analysis of MEF2A and MEF2C genome-wide mapping in mouse cortical neurons by ChIP-seq, a powerful approach to elucidate the genomic functions of transcription factors and to identify their transcriptional targets. Our analysis reveals that MEF2A and MEF2C each orchestrate similar epigenomic programs mainly through the binding of enhancer regulatory elements in proximity of target genes involved in neuronal plasticity and calcium signaling. We highlight the differences in the enhancer networks and molecular pathways regulated by MEF2A and MEF2C, which might be determined by the combinatorial action of different transcription factors.
TL;DR: Why such a huge redundancy is required and what does that mean for the search process?
Abstract: A key limiting step in fertility is the search for the oocyte by spermatozoa. Initially, there are tens of millions of sperm cells, but a single one will make it to the oocyte. This may be one of the most severe selection processes designed by evolution, whose role is yet to be understood. Why such a huge redundancy is required and what does that mean for the search process? we discuss here these questions and consequently new lines of interdisciplinary research needed to find possible answers.
TL;DR: The notion that non-human primates are generally not very motivated to share their experiences of external objects or events with others, which removes most reasons for referential signaling, is addressed.
Abstract: We comment on a recent behavioral study in which we describe a human-like beckoning gesture in 2 groups of bonobos, used in combination with sexual solicitation postures. The beckoning gesture fulfils key criteria of deixis and iconicity, in that it communicates to a distant recipient the desired travel path in relation to a specific social intention, i.e., to have sex at another location. We discuss this finding in light of the fact that, despite the documented great ape capacity and obvious communicative advantage, referential gestures are still surprisingly rare in their natural communication. We address several possibilities for this peculiar underuse and are most compelled by the notion that non-human primates are generally not very motivated to share their experiences of external objects or events with others, which removes most reasons for referential signaling.
TL;DR: Results indicate a phosphorylation-dependent tuning of the period length by a regulatory network of multiple kinases and reveal an essential role of CaMKII in the cellular oscillation mechanism.
Abstract: Molecular oscillation of the circadian clock is based on E-box-mediated transcriptional feedback loop formed with clock genes and their encoding products, clock proteins. The clock proteins are regulated by post-translational modifications such as phosphorylation. We investigated the effects of a series of kinase inhibitors on gene expression rhythms in Rat-1 fibroblasts. The period of the cellular circadian rhythm in culture was lengthened by treatment with SB203580 (p38 MAPK inhibitor), SP600125 (JNK inhibitor), IC261 (CKI inhibitor) and Roscovitine (CDK inhibitor). On the other hand, the period was shortened by SB216763 (GSK-3 inhibitor) or KN93 (CaMKII inhibitor) treatment. Application of 20 μM KN93 completely abolished the rhythmic gene expression. The activity of CaMKII exhibited circadian variation in a phase close to the E-box-mediated transcriptional rhythms. In vitro kinase assay revealed that CaMKII directly phosphorylates N-terminal and Ser/Pro-rich domains of CLOCK, an activator of E-box-mediated transcription. These results indicate a phosphorylation-dependent tuning of the period length by a regulatory network of multiple kinases and reveal an essential role of CaMKII in the cellular oscillation mechanism.
TL;DR: It is revealed that cofilin1 regulation by hydrogen peroxide contributes to directional cell migration, and established a template for discovering additional proteins that are regulated in an analogous manner.
Abstract: Directional cell migration is a complex process that requires spatially and temporally co-ordinated regulation of actin cytoskeleton dynamics. In response to external cues, signals are transduced to elicit cytoskeletal responses. It has emerged that reactive oxygen species, including hydrogen peroxide, are important second messengers in pathways that influence the actin cytoskeleton, although the identities of key proteins regulated by hydrogen peroxide are largely unknown. We recently showed that oxidation of cofilin1 is elevated in migrating cells relative to stationary cells, and that the effect of this post-translational modification is to reduce cofilin1-actin binding and to inhibit filamentous-actin severing by cofilin1. These studies revealed that cofilin1 regulation by hydrogen peroxide contributes to directional cell migration, and established a template for discovering additional proteins that are regulated in an analogous manner.
TL;DR: IFNγ-inducible PV ubiquitination constitutes a critical event in cell-autonomous immunity to C. trachomatis and T. gondii in mice and humans, but the molecular machinery underlying PV Ubiquitination is expected to be multifaceted and possibly host species-specific.
Abstract: Many intracellular bacterial and protozoan pathogens reside within host cell vacuoles customized by the microbial invaders to fit their needs. Within such pathogen-containing vacuoles (PVs) microbes procure nutrients and simultaneously hide from cytosolic host defense systems. Among the many PV-resident human pathogens are the bacterium Chlamydia trachomatis and the protozoan Toxoplasma gondii. Immune responses directed against their PVs are poorly characterized. We reported that activation of host cells with IFNγ triggers the attachment of polyubiquitin chains to Toxoplasma- and Chlamydia-containing vacuoles and thereby marks PVs for destruction. In murine cells PV ubiquitination is dependent on IFNγ-inducible Immunity Related GTPases (IRGs). Human cells also decorate PVs with ubiquitin upon IFNγ priming; however, the molecular machinery promoting PV ubiquitination in human cells remains unknown and is likely to be distinct from the IRG-dependent pathway we described in murine cells. Thus, IFNγ-inducible PV ubiquitination constitutes a critical event in cell-autonomous immunity to C. trachomatis and T. gondii in mice and humans, but the molecular machinery underlying PV ubiquitination is expected to be multifaceted and possibly host species-specific.
TL;DR: It is proposed that the PKA-ezrin-Cx43 macromolecular complex regulating gap junction communication constitutes a general mechanism to control opening of Cx43 gap junctions by phosphorylation in response to cAMP signaling in various cell types.
Abstract: Anchored protein kinase A (PKA) bound to A Kinase Anchoring Protein (AKAP) mediates effects of localized increases in cAMP in defined subcellular microdomains and retains the specificity in cAMP-PKA signaling to distinct extracellular stimuli. Gap junctions are pores between adjacent cells constituted by connexin proteins that provide means of communication and transfer of small molecules. While the PKA signaling is known to promote human trophoblast cell fusion, the gap junction communication through connexin 43 (Cx43) is a prerequisite for this process. We recently demonstrated that trophoblast fusion is regulated by ezrin, a known AKAP, which binds to Cx43 and delivers PKA in the vicinity gap junctions. We found that disruption of the ezrin-Cx43 interaction abolished PKA-dependent phosphorylation of Cx43 as well as gap junction communication and subsequently cell fusion. We propose that the PKA-ezrin-Cx43 macromolecular complex regulating gap junction communication constitutes a general mechanism to control opening of Cx43 gap junctions by phosphorylation in response to cAMP signaling in various cell types.
TL;DR: Social network analyses in wild chimpanzees are used to provide direct evidence for social transmission of a behavioral innovation, moss-sponging, to extract water from a tree hole and discuss the implications and how the new methodological approach could help future studies of social learning and culture in wild apes.
Abstract: For years, the animal culture debate has been dominated by the puzzling absence of direct evidence for social transmission of behavioral innovations in the flagship species of animal culture, the common chimpanzee. Although social learning of novel behaviors has been documented in captivity, critics argue that these findings lack ecological validity and therefore may not be relevant for understanding the evolution of culture. For the wild, it is possible that group-specific behavioral differences emerge because group members respond individually to unspecified environmental differences, rather than learning from each other. In a recent paper, we used social network analyses in wild chimpanzees (Pan troglodytes schweinfurthii) to provide direct evidence for social transmission of a behavioral innovation, moss-sponging, to extract water from a tree hole. Here, we discuss the implications of our findings and how our new methodological approach could help future studies of social learning and culture in wild apes.
TL;DR: This study investigated a potential endogenous role of prion protein in synaptic signaling, the lack of which could resemble a lack-of-function phenotype in prion disease.
Abstract: Neurodegenerative disorders are characterized by synaptic and neuronal dysfunction which precedes general neuronal loss and subsequent cognitive or behavioral anomalies. Although the exact early cellular signaling mechanisms involved in neurodegenerative diseases are largely unknown, a view is emerging that compromised synaptic function may underlie the initial steps in disease progression. Much recent research has been aimed at understanding these early underlying processes leading to dysfunctional synaptic signaling, as this knowledge could identify putative sites of interventions, which could potentially slow progression and delay onset of disease. We have recently reported that synaptic function in a Drosophila melanogaster model can be modulated by the presence of native mouse prion protein and this modulation is negatively affected by a mutation within the protein which is associated with the Gerstmann-Straussler-Scheinker syndrome, a human form of prion disease. Indeed, wild-type prion protein facilitates synaptic release, whereas the mutated form induced diminished phenotypes. It is believed that together with the gain-of-function of neurotoxic misfolded prion signaling, the lack of prion protein contributes to the pathology in prion diseases. Therefore, our study investigated a potential endogenous role of prion protein in synaptic signaling, the lack of which could resemble a lack-of-function phenotype in prion disease.
TL;DR: This work sheds light on the mechanisms of radial transport of nutrients across the different cell types of plant roots toward the vascular tissues and raises interesting parallel with iron transport in mammals.
Abstract: Plasma membrane proteins play pivotal roles in mediating responses to endogenous and environmental cues. Regulation of membrane protein levels and establishment of polarity are fundamental for many cellular processes. In plants, IRON-REGULATED TRANSPORTER 1 (IRT1) is the major root iron transporter but is also responsible for the absorption of other divalent metals such as manganese, zinc and cobalt. We recently uncovered that IRT1 is polarly localized to the outer plasma membrane domain of plant root epidermal cells upon depletion of its secondary metal substrates. The endosome-recruited FYVE1 protein interacts with IRT1 in the endocytic pathway and plays a crucial role in the establishment of IRT1 polarity, likely through its recycling to the cell surface. Our work sheds light on the mechanisms of radial transport of nutrients across the different cell types of plant roots toward the vascular tissues and raises interesting parallel with iron transport in mammals.
TL;DR: A working model is proposed in which DEK1, by maintaining cell-cell contacts, and thus communication between neighboring cells, influences HD-ZIP IV gene expression and epidermis differentiation.
Abstract: Plant epidermis development requires not only the initial acquisition of tissue identity, but also the ability to differentiate specific cell types over time and to maintain these differentiated states throughout the plant life. To set-up and maintain differentiation, plants activate specific transcriptional programs. Interfering with these programs can prevent differentiation and/or force differentiated cells to lose their identity and re-enter a proliferative state. We have recently shown that the Arabidopsis Defective Kernel 1 (DEK1) protein is required both for the differentiation of epidermal cells and for the maintenance of their fully differentiated state. Defects in DEK1 activity lead to a deregulation of the expression of epidermis-specific differentiation-promoting HD-ZIP IV transcription factors. Here we propose a working model in which DEK1, by maintaining cell-cell contacts, and thus communication between neighboring cells, influences HD-ZIP IV gene expression and epidermis differentiation.
TL;DR: This text first discusses hybridizing Maturana and Varela's biological theory of autopoiesis with Andy Clark's hypothesis of extended cognition, establishing a procedural protocol to research biological domains from which design could source data/insight from biosemiotics, sensory plants, and biocomputation.
Abstract: To incorporate metabolic, bioremedial functions into the performance of buildings and to balance generative architecture's dominant focus on computational programming and digital fabrication, this text first discusses hybridizing Maturana and Varela's biological theory of autopoiesis with Andy Clark's hypothesis of extended cognition. Doing so establishes a procedural protocol to research biological domains from which design could source data/insight from biosemiotics, sensory plants, and biocomputation. I trace computation and botanic simulations back to Alan Turing's little-known 1950s Morphogenetic drawings, reaction-diffusion algorithms, and pioneering artificial intelligence (AI) in order to establish bioarchitecture's generative point of origin. I ask provocatively, Can buildings think? as a question echoing Turing's own, "Can machines think?"
TL;DR: The finding that Rab7b can control actomyosin reorganization reveals yet another important role for Rab proteins, in addition to their already established role as master regulators of intracellular transport.
Abstract: Rab proteins are small GTPases essential for controlling and coordinating intracellular traffic. The small GTPase Rab7b regulates the retrograde transport from late endosomes toward the Trans-Golgi Network (TGN), and is important for the proper trafficking of several receptors such as Toll-like receptors (TLRs) and sorting receptors. We recently identified the actin motor protein myosin II as a new interaction partner for Rab7b, and found that Rab7b transport is dependent on myosin II. Interestingly, we also discovered that Rab7b influences the phosphorylation state of myosin II by controlling the activation status of the small GTPase RhoA. Consequently, Rab7b is important for the remodeling of actin filaments in processes such as stress fiber formation, cell adhesion, polarization and cell migration. Our finding that Rab7b can control actomyosin reorganization reveals yet another important role for Rab proteins, in addition to their already established role as master regulators of intracellular transport. Here we discuss our findings and speculate how they can explain the importance of Rab7b in dendritic cells (DCs).
TL;DR: Experienced and naïve Eastern painted turtles as they sought new habitats when their pond was drained suggested that learning during a critical period may be important for how animals respond to changing environments, highlighting the importance of incorporating cognition into conservation.
Abstract: Animals inhabiting changing environments show high levels of cognitive plasticity. Cognition may be a means by which animals buffer the impact of environmental change. However, studies examining the evolution of cognition seldom compare populations where change is rapid and selection pressures are strong. We investigated this phenomenon by radiotracking experienced and naive Eastern painted turtles (Chrysemys picta) as they sought new habitats when their pond was drained. Resident adults repeatedly used specific routes to permanent water sources with exceptional precision, while adults translocated to the site did not. Naive 1-3 y olds from both populations used the paths taken by resident adults, an ability lost by age 4. Experience did not, however, influence the timing of movement or the latency to begin navigation. This suggests that learning during a critical period may be important for how animals respond to changing environments, highlighting the importance of incorporating cognition into conservation.
TL;DR: Proteomic analysis of acidocalcisomes of T. brucei procyclic stages provides direct evidence that acidocalCisomes are especially adapted to accumulate polyP bound to cations and for calcium signaling.
Abstract: Trypanosoma brucei, the causative agent of African trypanosomiasis, is a unicellular parasite that possesses lysosome-related organelles known as acidocalcisomes. These organelles have been found from bacteria to human cells, and are characterized by their acidic nature and high calcium and polyphosphate (polyP) content. Our proteomic analysis of acidocalcisomes of T. brucei procyclic stages, together with in situ epitope-tagging and immunofluorescence assays with specific antibodies against selected proteins, established the presence of 2 H(+) pumps, a vacuolar H(+)-ATPase and a vacuolar H(+)-pyrophosphatase, that acidify the organelles as well as of a number of transporters and channels involved in phosphate metabolism, cation uptake and calcium signaling. Together with recent work in other organisms, these results provide direct evidence that acidocalcisomes are especially adapted to accumulate polyP bound to cations and for calcium signaling.
TL;DR: By exploiting gene-targeted mice, the relevance of ADF for excitatory synapses is demonstrated, and novel functions for ADF/cofilin in presynaptic physiology and behavior are unraveled.
Abstract: Actin filaments (F-actin) are the major structural component of excitatory synapses. In excitatory synapses, F-actin is enriched in presynaptic terminals and in postsynaptic dendritic spines, and actin dynamics - the spatiotemporally controlled assembly and disassembly of F-actin - have been implicated in pre- and postsynaptic physiology, additionally to their function in synapse morphology. Hence, actin binding proteins that control actin dynamics have moved into the focus as regulators of synapse morphology and physiology. Actin depolymerizing proteins of the ADF/cofilin family are important regulators of actin dynamics, and several recent studies highlighted the relevance of cofilin 1 for dendritic spine morphology, trafficking of postsynaptic glutamate receptors, and synaptic plasticity. Conversely, almost nothing was known about the synaptic function of ADF, a second ADF/cofilin family member present at excitatory synapses, and it remained unknown whether ADF/cofilin is relevant for presynaptic physiology. To comprehensively characterize the synaptic function of ADF/cofilin we made use of mutant mice lacking either ADF or cofilin 1 or both proteins. Our analysis revealed presynaptic defects (altered distribution and enhanced exocytosis of synaptic vesicles) and behavioral abnormalities reminiscent of attention deficit-hyperactivity disorder in double mutants that were not present in single mutants. Hence, by exploiting gene-targeted mice, we demonstrated the relevance of ADF for excitatory synapses, and we unraveled novel functions for ADF/cofilin in presynaptic physiology and behavior.