AAV Vector Mediated Delivery of NG2 Function Neutralizing Antibody and Neurotrophin NT-3 Improves Synaptic Transmission, Locomotion, and Urinary Tract Function after Spinal Cord Contusion Injury in Adult Rats.

NG2 is a structurally unique transmembrane chondroitin sulfate proteoglycan (CSPG). Its role in damaged spinal cord is dual. NG2 is considered one of key inhibitory factors restricting axonal growth following spinal injury. Additionally, we have recently detected its novel function as a blocker of axonal conduction. Some studies, however, indicate the importance of NG2 presence in the formation of synaptic contacts. We hypothesized that the optimal treatment would be neutralization of inhibitory functions of NG2 without its physical removal. Acute intraspinal injections of anti-NG2 monoclonal antibodies reportedly prevented an acute block of axonal conduction by exogenous NG2. For prolonged delivery of NG2 function neutralizing antibody, we have developed a novel gene therapy: adeno-associated vector (AAV) construct expressing recombinant single-chain variable fragment anti-NG2 antibody (AAV-NG2Ab). We examined effects of AAV-NG2Ab alone or in combination with neurotrophin NT-3 in adult female rats with thoracic T10 contusion injuries. A battery of behavioral tests was used to evaluate locomotor function. In vivo single-cell electrophysiology was used to evaluate synaptic transmission. Lower urinary tract function was assessed during the survival period using metabolic chambers. Terminal cystometry, with acquisition of external urethral sphincter activity and bladder pressure, was used to evaluate bladder function. Both the AAV-NG2Ab and AAV-NG2Ab combined with AAV-NT3 treatment groups demonstrated significant improvements in transmission, locomotion, and bladder function compared with the control (AAV-GFP) group. These functional improvements associated with improved remyelination and plasticity of 5-HT fibers. The best results were observed in the group that received combinational AAV-NG2Ab+AAV-NT3 treatment.SIGNIFICANCE STATEMENT We recently demonstrated beneficial, but transient, effects of neutralization of the NG2 proteoglycan using monoclonal antibodies delivered intrathecally via osmotic mini-pumps after spinal cord injury. Currently, we have developed a novel gene therapy tool for prolonged and clinically relevant delivery of a recombinant single-chain variable fragment anti-NG2 antibody: AAV-rh10 serotype expressing scFv-NG2 (AAV-NG2Ab). Here, we examined effects of AAV-NG2Ab combined with transgene delivery of Neurotrophin-3 (AAV-NT3) in adult rats with thoracic contusion injuries. The AAV-NG2Ab and AAV-NG2Ab+AAV-NT3 treatment groups demonstrated significant improvements of locomotor function and lower urinary tract function. Beneficial effects of this novel gene therapy on locomotion and bladder function associated with improved transmission to motoneurons and plasticity of axons in damaged spinal cord.

Behavioral and environmental contributions to drosophilid social networks.

Animals interact with each other in species-specific reproducible patterns. These patterns of organization are captured by social network analysis, and social interaction networks (SINs) have been described for a wide variety of species including fish, insects, birds, and mammals. The aim of this study is to understand the evolution of social organization in Drosophila Using a comparative ecological, phylogenetic, and behavioral approach, the different properties of SINs formed by 20 drosophilids were compared. We investigate whether drosophilid network structures arise from common ancestry, a response to the species' past climate, other social behaviors, or a combination of these factors. This study shows that differences in past climate predicted the species' current SIN properties. The drosophilid phylogeny offered no value to predicting species' differences in SINs through phylogenetic signal tests. This suggests that group-level social behaviors in drosophilid species are shaped by divergent climates. However, we find that the social distance at which flies interact correlated with the drosophilid phylogeny, indicating that behavioral elements of SINs have remained largely unchanged in their evolutionary history. We find a significant correlation of leg length to social distance, outlining the interdependence of anatomy and complex social structures. Although SINs display a complex evolutionary relationship across drosophilids, this study suggests that the ecology, and not common ancestry, contributes to diversity in social structure in Drosophila.

Critical period regulation across multiple timescales.

Brain plasticity is dynamically regulated across the life span, peaking during windows of early life. Typically assessed in the physiological range of milliseconds (real time), these trajectories are also influenced on the longer timescales of developmental time (nurture) and evolutionary time (nature), which shape neural architectures that support plasticity. Properly sequenced critical periods of circuit refinement build up complex cognitive functions, such as language, from more primary modalities. Here, we consider recent progress in the biological basis of critical periods as a unifying rubric for understanding plasticity across multiple timescales. Notably, the maturation of parvalbumin-positive (PV) inhibitory neurons is pivotal. These fast-spiking cells generate gamma oscillations associated with critical period plasticity, are sensitive to circadian gene manipulation, emerge at different rates across brain regions, acquire perineuronal nets with age, and may be influenced by epigenetic factors over generations. These features provide further novel insight into the impact of early adversity and neurodevelopmental risk factors for mental disorders.

Characterizing the Protein Isoforms of foraging (for), the PKGI Ortholog in Drosophila melanogaster.

The foraging (for) gene of Drosophila melanogaster encodes a cGMP-dependent protein kinase (PKG), which is a major effector of the cGMP signaling pathway involved in the regulation of behaviour and metabolic traits. Despite being well studied at the transcript level, little is known about the for gene at the protein level. Here, we provide a detailed characterization of the for gene protein (FOR) products and present new tools for their study, including five isoform-specific antibodies and a transgenic strain that carries an HA-labelled for allele (forBAC::HA). Our results showed that multiple FOR isoforms were expressed in the larval and adult stages of D. melanogaster and that the majority of whole-body FOR expression arises from three (P1, P1α, and P3) of eight putative protein isoforms. We found that FOR expression differed between the larval and adult stages and between the dissected larval organs we analyzed, which included the central nervous system (CNS), fat body, carcass, and intestine. Moreover, we showed that the FOR expression differed between two allelic variants of the for gene, namely, fors (sitter) and forR (rover), that are known to differ in many food-related traits. Together, our in vivo identification of FOR isoforms and the existence of temporal, spatial, and genetic differences in their expression lay the groundwork for determining their functional significance.

The Drosophila melanogaster foraging gene affects social networks.

Drosophila melanogaster displays social behaviors including courtship, mating, aggression, and group foraging. Recent studies employed social network analyses (SNAs) to show that D. melanogaster strains differ in their group behavior, suggesting that genes influence social network phenotypes. Aside from genes associated with sensory function, few studies address the genetic underpinnings of these networks. The foraging gene (for) is a well-established example of a pleiotropic gene that regulates multiple behavioral phenotypes and their plasticity. In D. melanogaster, there are two naturally occurring alleles of for called rover and sitter that differ in their larval and adult food-search behavior as well as other behavioral phenotypes. Here, we hypothesize that for affects behavioral elements required to form social networks and the social networks themselves. These effects are evident when we manipulate gene dosage. We found that flies of the rover and sitter strains exhibit differences in duration, frequency, and reciprocity of pairwise interactions, and they form social networks with differences in assortativity and global efficiency. Consistent with other adult phenotypes influenced by for, rover-sitter heterozygotes show intermediate patterns of dominance in many of these characteristics. Multiple generations of backcrossing a rover allele into a sitter strain showed that many but not all of these rover-sitter differences may be attributed to allelic variation at for. Our findings reveal the significant role that for plays in affecting social network properties and their behavioral elements in Drosophila melanogaster.

Pharmacist intervention in colorectal cancer screening initiative.

OBJECTIVES: To assess the novel approach of using the community pharmacist as the primary health care team member to facilitate colorectal cancer (CRC) risk counseling and screening in socioeconomically disadvantaged populations. SETTING: A collaborative effort between the UConn Health Colon Cancer Prevention Program and UConn School of Pharmacy in conjunction with large independent chain pharmacies (medium to medium-high volume) located in metropolitan areas of Connecticut, including Hartford, Bridgeport, New Haven, and Stamford. Pharmacies located in hospitals, across the street from a large physician practice, or within the community. PRACTICE DESCRIPTION: The study involved 2 phases. The first phase involved education and training for community pharmacists regarding counseling approaches for patients on the topic of CRC. The second phase of the study involved patient recruitment and counseling with subsequent fecal immunohistochemical testing (FIT). PRACTICE INNOVATION: A community pharmacist provided face-to-face counseling on CRC risk factor reduction and provided CRC screening to patients who were without insurance or underinsured. No CRC screening or education program existed beforehand. EVALUATION: A target sample size of 60 participants was needed with a type 1 error rate of 5% and a power of 80%. Exploration of variables using multivariate logistic regression model included any variable with a univariate P < 0.2. Multivariate P values < 0.05 were considered independent predictors. RESULTS: After approaching 312 consumers, 16 of them consented to the study. The majority of participants (88%) were African American or Latino, and 69% were currently unemployed. Eight participants agreed to complete FIT, and 88% of participants completed FIT correctly. Only 1 positive FIT result was observed, but a subsequent colonoscopy was negative. Of the 12 questions that assessed baseline CRC knowledge in the initial survey, 16 participants answered an average of 2.6 (range, 0-6, SD, 1.6) questions incorrectly. Only 4 participants completed the follow-up survey of CRC knowledge and program satisfaction; thus, exploration of variables was not conducted. Patients indicated high satisfaction with the program of education and FIT dispensing. CONCLUSION: This study faced difficulty in recruiting pharmacists to participate, with the main reason being lack of compensation and disruption to workflow. Patient participation in the trial was also low because of a lack of time or interest in participation. Of the patients who did participate, the level of satisfaction in having the pharmacist speak to them about CRC screening was high. This service is an excellent example of how the pharmacist can provide a more accessible, convenient, and responsive approach to patients' needs while improving health equity. Future studies that employ a revenue model to build the infrastructure and capacity necessary to offer this service efficiently and consistently are needed.

A Symphony of Signals: Intercellular and Intracellular Signaling Mechanisms Underlying Circadian Timekeeping in Mice and Flies.

The central pacemakers of circadian timekeeping systems are highly robust yet adaptable, providing the temporal coordination of rhythms in behavior and physiological processes in accordance with the demands imposed by environmental cycles. These features of the central pacemaker are achieved by a multi-oscillator network in which individual cellular oscillators are tightly coupled to the environmental day-night cycle, and to one another via intercellular coupling. In this review, we will summarize the roles of various neurotransmitters and neuropeptides in the regulation of circadian entrainment and synchrony within the mammalian and Drosophila central pacemakers. We will also describe the diverse functions of protein kinases in the relay of input signals to the core oscillator or the direct regulation of the molecular clock machinery.

The neurogenetics of group behavior in Drosophila melanogaster.

Organisms rarely act in isolation. Their decisions and movements are often heavily influenced by direct and indirect interactions with conspecifics. For example, we each represent a single node within a social network of family and friends, and an even larger network of strangers. This group membership can affect our opinions and actions. Similarly, when in a crowd, we often coordinate our movements with others like fish in a school, or birds in a flock. Contributions of the group to individual behaviors are observed across a wide variety of taxa but their biological mechanisms remain largely unknown. With the advent of powerful computational tools as well as the unparalleled genetic accessibility and surprisingly rich social life of Drosophila melanogaster, researchers now have a unique opportunity to investigate molecular and neuronal determinants of group behavior. Conserved mechanisms and/or selective pressures in D. melanogaster can likely inform a much wider phylogenetic scale. Here, we highlight two examples to illustrate how quantitative and genetic tools can be combined to uncover mechanisms of two group behaviors in D. melanogaster: social network formation and collective behavior. Lastly, we discuss future challenges towards a full understanding how coordinated brain activity across many individuals gives rise to the behavioral patterns of animal societies.

Phylogeny, environment and sexual communication across the Drosophila genus.

Social behaviour emerges from the local environment but is constrained by the animal's life history and its evolutionary lineage. In this perspective, we consider the genus Drosophila and provide an overview of how these constraints can shape how individuals interact. Our focus is restricted to visual and chemical signals and how their use varies across species during courtship - currently the only social behaviour well-studied across many Drosophila species. We broadly categorize species into four climatic groups - cosmopolitan, tropical, temperate and arid - which serve as discussion points as we review comparative behavioural and physiological studies and relate them to the abiotic conditions of a species environment. We discuss how the physiological and behavioural differences among many fly species may reflect life history differences as much as, or even more than, differences in phylogeny. This perspective serves not only to summarize what has been studied across drosophilids, but also to identify questions and outline gaps in the literature worth pursuing for progressing the understanding of behavioural evolution in Drosophila.

Low Serum Vitamin D: A Surrogate Marker for Advanced Colon Adenoma?

AIMS: To examine the association between low 25-OH Vitamin D levels and prevalence of advanced adenomas (AAs) in screening/surveillance colonoscopy patients. RATIONALE: Low serum 25-OH Vitamin D has been associated with an increased risk for colon cancer. In the Adenoma-Carcinoma pathway, a subset of colon polyps (AA) have been regarded as high-risk precursor lesions. We used a retrospective case-control design to examine the association between Vitamin D deficiency and the prevalence of AA in a high-risk population. MATERIALS AND METHODS: We examined a total of 354 patients who presented for initial screening or surveillance colonoscopy at our Colon Cancer Prevention Program. Our main exposure variable was serum Vitamin D levels and the outcome was AAs defined as those adenomas that were large (≥1 cm) or had advanced pathology (>25% villous components or high-grade dysplasia). Known risk factors were also collected from the patients' charts including gender, age, smoking, and family history. Bivariate and multivariate analyses were performed to examine the relationship between serum 25-OH Vitamin D levels and AAs. A total of 354 patients [(males, 188; females, 166); average age, 61 y] charts were reviewed. Vitamin D levels ranged between 4 and 70 ng/mL, with a mean of 25 ng/mL (clinical laboratory normal>30 ng/mL). There was no significant association between serum levels and time of the year of blood draw. Risk for tubular adenoma and AA increased as Vitamin D levels decreased to <30 ng/mL (P=0.002). In total, 80% of AAs were detected in patients whose levels were below this value (odds ratio, 3.36; 95% confidence interval, 1.40-8.03; P=0.007). Bivariate analysis also showed a positive association between smokers with AA as well as those with a family history of colon cancer (P=0.011) and low Vitamin D levels (P=0.001). A multivariate analysis using quintiles of Vitamin D levels demonstrated an increased risk of AAs for patients with levels in the second quintile (33 ng/mL) (odds ratio, 4.3; P=0.01) MAIN CONCLUSIONS:: Most patients presenting in our Colon Cancer Prevention Program have low levels of serum 25-OH Vitamin D. Analysis of the results of both screening and surveillance colonoscopies demonstrated an inverse relation between serum 25-OH Vitamin D level and AAs.

Regulation of onset of female mating and sex pheromone production by juvenile hormone in Drosophila melanogaster.

Juvenile hormone (JH) coordinates timing of female reproductive maturation in most insects. In Drosophila melanogaster, JH plays roles in both mating and egg maturation. However, very little is known about the molecular pathways associated with mating. Our behavioral analysis of females genetically lacking the corpora allata, the glands that produce JH, showed that they were courted less by males and mated later than control females. Application of the JH mimic, methoprene, to the allatectomized females just after eclosion rescued both the male courtship and the mating delay. Our studies of the null mutants of the JH receptors, Methoprene tolerant (Met) and germ cell-expressed (gce), showed that lack of Met in Met(27) females delayed the onset of mating, whereas lack of Gce had little effect. The Met(27) females were shown to be more attractive but less behaviorally receptive to copulation attempts. The behavioral but not the attractiveness phenotype was rescued by the Met genomic transgene. Analysis of the female cuticular hydrocarbon profiles showed that corpora allata ablation caused a delay in production of the major female-specific sex pheromones (the 7,11-C27 and -C29 dienes) and a change in the cuticular hydrocarbon blend. In the Met(27) null mutant, by 48 h, the major C27 diene was greatly increased relative to wild type. In contrast, the gce(2.5k) null mutant females were courted similarly to control females despite changes in certain cuticular hydrocarbons. Our findings indicate that JH acts primarily via Met to modulate the timing of onset of female sex pheromone production and mating.

Abrogation of ß-catenin signaling in oligodendrocyte precursor cells reduces glial scarring and promotes axon regeneration after CNS injury.

When the brain or spinal cord is injured, glial cells in the damaged area undergo complex morphological and physiological changes resulting in the formation of the glial scar. This scar contains reactive astrocytes, activated microglia, macrophages and other myeloid cells, meningeal cells, proliferating oligodendrocyte precursor cells (OPCs), and a dense extracellular matrix. Whether the scar is beneficial or detrimental to recovery remains controversial. In the acute phase of recovery, scar-forming astrocytes limit the invasion of leukocytes and macrophages, but in the subacute and chronic phases of injury the glial scar is a physical and biochemical barrier to axonal regrowth. The signals that initiate the formation of the glial scar are unknown. Both canonical and noncanonical signaling Wnts are increased after spinal cord injury (SCI). Because Wnts are important regulators of OPC and oligodendrocyte development, we examined the role of canonical Wnt signaling in the glial reactions to CNS injury. In adult female mice carrying an OPC-specific conditionally deleted ß-catenin gene, there is reduced proliferation of OPCs after SCI, reduced accumulation of activated microglia/macrophages, and reduced astrocyte hypertrophy. Using an infraorbital optic nerve crush injury, we show that reducing ß-catenin-dependent signaling in OPCs creates an environment that is permissive to axonal regeneration. Viral-induced expression of Wnt3a in the normal adult mouse spinal cord induces an injury-like response in glia. Thus canonical Wnt signaling is both necessary and sufficient to induce injury responses among glial cells. These data suggest that targeting Wnt expression after SCI may have therapeutic potential in promoting axon regeneration.

Entrapment via synaptic-like connections between NG2 proteoglycan+ cells and dystrophic axons in the lesion plays a role in regeneration failure after spinal cord injury.

NG2 is purportedly one of the most growth-inhibitory chondroitin sulfate proteoglycans (CSPGs) produced after spinal cord injury. Nonetheless, once the severed axon tips dieback from the lesion core into the penumbra they closely associate with NG2+ cells. We asked if proteoglycans play a role in this tight cell-cell interaction and whether overadhesion upon these cells might participate in regeneration failure in rodents. Studies using varying ratios of CSPGs and adhesion molecules along with chondroitinase ABC, as well as purified adult cord-derived NG2 glia, demonstrate that CSPGs are involved in entrapping neurons. Once dystrophic axons become stabilized upon NG2+ cells, they form synaptic-like connections both in vitro and in vivo. In NG2 knock-out mice, sensory axons in the dorsal columns dieback further than their control counterparts. When axons are double conditioned to enhance their growth potential, some traverse the lesion core and express reduced amounts of synaptic proteins. Our studies suggest that proteoglycan-mediated entrapment upon NG2+ cells is an additional obstacle to CNS axon regeneration.

Specialized cells tag sexual and species identity in Drosophila melanogaster.

Social interactions depend on individuals recognizing each other, and in this context many organisms use chemical signals to indicate species and sex. Cuticular hydrocarbon signals are used by insects, including Drosophila melanogaster, to distinguish conspecific individuals from others. These chemicals also contribute to intraspecific courtship and mating interactions. However, the possibility that sex and species identification are linked by common chemical signalling mechanisms has not been formally tested. Here we provide direct evidence that a single compound is used to communicate female identity among D. melanogaster, and to define a reproductive isolation barrier between D. melanogaster and sibling species. A transgenic manipulation eliminated cuticular hydrocarbons by ablating the oenocytes, specialized cells required for the expression of these chemical signals. The resulting oenocyte-less (oe(-)) females elicited the normal repertoire of courtship behaviours from males, but were actually preferred over wild-type females by courting males. In addition, wild-type males attempted to copulate with oe(-) males. Thus, flies lacking hydrocarbons are a sexual hyperstimulus. Treatment of virgin females with the aversive male pheromone cis-vaccenyl acetate (cVA) significantly delayed mating of oe(-) females compared to wild-type females. This difference was eliminated when oe(-) females were treated with a blend of cVA and the female aphrodisiac (7Z,11Z)-heptacosadiene (7,11-HD), showing that female aphrodisiac compounds can attenuate the effects of male aversive pheromones. 7,11-HD also was shown to have a crucial role in heterospecific encounters. Specifically, the species barrier was lost because males of other Drosophila species courted oe(-) D. melanogaster females, and D. simulans males consistently mated with them. Treatment of oe(-) females with 7,11-HD restored the species barrier, showing that a single compound can confer species identity. These results identify a common mechanism for sexual and species recognition regulated by cuticular hydrocarbons.

Social structures depend on innate determinants and chemosensory processing in Drosophila.

Flies display transient social interactions in groups. However, whether fly-fly interactions are stochastic or structured remains unknown. We hypothesized that groups of flies exhibit patterns of social dynamics that would manifest as nonrandom social interaction networks. To test this, we applied a machine vision system to track the position and orientation of flies in an arena and designed a classifier to detect interactions between pairs of flies. We show that the vinegar fly, Drosophila melanogaster, forms nonrandom social interaction networks, distinct from virtual network controls (constructed from the intersections of individual locomotor trajectories). In addition, the formation of interaction networks depends on chemosensory cues. Gustatory mutants form networks that cannot be distinguished from their virtual network controls. Olfactory mutants form networks that are greatly disrupted compared with control flies. Different wild-type strains form social interaction networks with quantitatively different properties, suggesting that the genes that influence this network phenotype vary across and within wild-type populations. We have established a paradigm for studying social behaviors at a group level in Drosophila and expect that a genetic dissection of this phenomenon will identify conserved molecular mechanisms of social organization in other species.

Atypical protein kinase C and Par3 are required for proteoglycan-induced axon growth inhibition.

When the CNS is injured, damaged axons do not regenerate. This failure is due in part to the growth-inhibitory environment that forms at the injury site. Myelin-associated molecules, repulsive axon guidance molecules, and extracellular matrix molecules including chondroitin sulfate proteoglycans (CSPGs) found within the glial scar inhibit axon regeneration but the intracellular signaling mechanisms triggered by these diverse molecules remain largely unknown. Here we provide biochemical and functional evidence that atypical protein kinase C (PKCζ) and polarity (Par) complex proteins mediate axon growth inhibition. Treatment of postnatal rat neurons in vitro with the NG2 CSPG, a major component of the glial scar, activates PKCζ, and this activation is both necessary and sufficient to inhibit axonal growth. NG2 treatment also activates Cdc42, increases the association of Par6 with PKCζ, and leads to a Par3-dependent activation of Rac1. Transfection of neurons with kinase-dead forms of PKCζ, dominant-negative forms of Cdc42, or mutant forms of Par6 that do not bind to Cdc42 prevent NG2-induced growth inhibition. Similarly, transfection with either a phosphomutant Par3 (S824A) or dominant-negative Rac1 prevent inhibition, whereas expression of constitutively active Rac1 inhibits axon growth on control surfaces. These results suggest a model in which NG2 binding to neurons activates PKCζ and modifies Par complex function. They also identify the Par complex as a novel therapeutic target for promoting axon regeneration after CNS injury.

Neutralization of inhibitory molecule NG2 improves synaptic transmission, retrograde transport, and locomotor function after spinal cord injury in adult rats.

NG2 belongs to the family of chondroitin sulfate proteoglycans that are upregulated after spinal cord injury (SCI) and are major inhibitory factors restricting the growth of fibers after SCI. Neutralization of NG2's inhibitory effect on axon growth by anti-NG2 monoclonal antibodies (NG2-Ab) has been reported. In addition, recent studies show that exogenous NG2 induces a block of axonal conduction. In this study, we demonstrate that acute intraspinal injections of NG2-Ab prevented an acute block of conduction by NG2. Chronic intrathecal infusion of NG2-Ab improved the following deficits induced by chronic midthoracic lateral hemisection (HX) injury: (1) synaptic transmission to lumbar motoneurons, (2) retrograde transport of fluororuby anatomical tracer from L5 to L1, and (3) locomotor function assessed by automated CatWalk gait analysis. We collected data in an attempt to understand the cellular and molecular mechanisms underlying the NG2-Ab-induced improvement of synaptic transmission in HX-injured spinal cord. These data showed the following: (1) that chronic NG2-Ab infusion improved conduction and axonal excitability in chronically HX-injured rats, (2) that antibody treatment increased the density of serotonergic axons with ventral regions of spinal segments L1-L5, (3) and that NG2-positive processes contact nodes of Ranvier within the nodal gap at the location of nodal Na(+) channels, which are known to be critical for propagation of action potentials along axons. Together, these results demonstrate that treatment with NG2-Ab partially improves both synaptic and anatomical plasticity in damaged spinal cord and promotes functional recovery after HX SCI. Neutralizing antibodies against NG2 may be an excellent way to promote axonal conduction after SCI.

The gene "degrees of kevin bacon" (dokb) regulates a social network behaviour in Drosophila melanogaster.

Social networks are a mathematical representation of interactions among individuals which are prevalent across various animal species. Studies of human populations have shown the breadth of what can spread throughout a social network: obesity, smoking cessation, happiness, drug use and divorce. 'Betweenness centrality' is a key property of social networks that indicates an individual's importance in facilitating communication and cohesion within the network. Heritability of betweenness centrality has been suggested in several species, however the genetic regulation of this property remains enigmatic. Here, we demonstrate that the gene CG14109, referred to as degrees of kevin bacon (dokb), influences betweenness centrality in Drosophila melanogaster. We identify strain-specific alleles of dokb with distinct amino acid sequences and when the dokb allele is exchanged between strains, flies exhibit the betweenness centrality pattern dictated by the donor allele. By inserting a GAL4 reporter into the dokb locus, we confirm that dokb is expressed in the central nervous system. These findings define a novel genetic entry point to study social network structure and thereby establish gene-to-social structure relationships. While dokb sequence homology is exclusive to Diptera, we anticipate that dokb-associated molecular pathways could unveil convergent neural mechanisms of social behaviour that apply in diverse animal species.

Planetary Protection Knowledge Gap Closure Enabling Crewed Missions to Mars.

As focus for exploration of Mars transitions from current robotic explorers to development of crewed missions, it remains important to protect the integrity of scientific investigations at Mars, as well as protect the Earth's biosphere from any potential harmful effects from returned martian material. This is the discipline of planetary protection, and the Committee on Space Research (COSPAR) maintains the consensus international policy and guidelines on how this is implemented. Based on National Aeronautics and Space Administration (NASA) and European Space Agency (ESA) studies that began in 2001, COSPAR adopted principles and guidelines for human missions to Mars in 2008. At that point, it was clear that to move from those qualitative provisions, a great deal of work and interaction with spacecraft designers would be necessary to generate meaningful quantitative recommendations that could embody the intent of the Outer Space Treaty (Article IX) in the design of such missions. Beginning in 2016, COSPAR then sponsored a multiyear interdisciplinary meeting series to address planetary protection "knowledge gaps" (KGs) with the intent of adapting and extending the current robotic mission-focused Planetary Protection Policy to support the design and implementation of crewed and hybrid exploration missions. This article describes the outcome of the interdisciplinary COSPAR meeting series, to describe and address these KGs, as well as identify potential paths to gap closure. It includes the background scientific basis for each topic area and knowledge updates since the meeting series ended. In particular, credible solutions for KG closure are described for the three topic areas of (1) microbial monitoring of spacecraft and crew health; (2) natural transport (and survival) of terrestrial microbial contamination at Mars, and (3) the technology and operation of spacecraft systems for contamination control. The article includes a KG data table on these topic areas, which is intended to be a point of departure for making future progress in developing an end-to-end planetary protection requirements implementation solution for a crewed mission to Mars. Overall, the workshop series has provided evidence of the feasibility of planetary protection implementation for a crewed Mars mission, given (1) the establishment of needed zoning, emission, transport, and survival parameters for terrestrial biological contamination and (2) the creation of an accepted risk-based compliance approach for adoption by spacefaring actors including national space agencies and commercial/nongovernment organizations.