Chronic wounds affect 12–15% of patients with diabetes and are associated with a drastic decrease in their quality of life. Here we demonstrate that purified mature naïve B220+/CD19+/IgM+/IgD+ B cells improve healing of acute and diabetic murine wounds after a single topical application. B cell treatment significantly accelerated acute wound closure by 2–3 days in wild-type mice and 5–6 days in obese diabetic mice. The treatment led to full closure in 43% of chronic diabetic wounds, as compared to only 5% in saline-treated controls. Applying equivalent numbers of T cells or disrupted B cells failed to reproduce these effects, indicating that live B cells mediated pro-healing responses. Topically-applied B cell treatment was associated with significantly reduced scar size, increased collagen deposition and maturation, enhanced angiogenesis and increased nerve growth into and under the healing wound. β-III tubulin+ nerve endings in scars of wounds treated acutely with B cells showed increased relative expression of growth-associated protein 43. The improved healing associated with B cell treatment was supported by significantly increased fibroblast proliferation and decreased apoptosis in the wound bed and edges, altered kinetics of neutrophil infiltration, as well as an increase in TGF-β and a significant reduction in MMP2 expression in wound granulation tissue. Our findings indicate that the timeline and efficacy of wound healing can be experimentally manipulated through the direct application of mature, naive B cells, which effectively modify the balance of mature immune cell populations within the wound microenvironment and accelerate the healing process.

The weakly electric fish Apteronotus leptorhynchus produces wave-like electric organ discharges distinguished by a high degree of regularity. Transient amplitude and frequency modulations ("chirps") can be evoked in males by stimulation with the electric field of a conspecific. During these interactions, the males examined in this study produced six types of chirps, including two novel ones. Stimulation of a test fish with a conspecific at various distances showed that two electrically interacting fish must be within 10 cm of each other to evoke chirping behavior in the neighboring fish. The chirp rate of all but one chirp type elicited by the neighboring fish was found to be negatively correlated with the absolute value of the frequency difference between the two interacting fish, but independent of the sign of this difference. Correlation analysis of the instantaneous rates of chirp occurrence revealed two modes of interactions characterized by reciprocal stimulation and reciprocal inhibition. Further analysis of the temporal relationship between the chirps generated by the two fish during electric interactions showed that the chirps generated by one individual follow the chirps of the other with a short latency of approximately 500-1,000 ms. We hypothesize that this "echo response" serves a communicatory function.

In contrast to mammals, teleost fish exhibit an enormous potential to regenerate adult spinal cord tissue after injury. However, the mechanisms mediating this ability are largely unknown. Here, we analyzed the major processes underlying structural and functional regeneration after amputation of the caudal portion of the spinal cord in Apteronotus leptorhynchus, a weakly electric teleost. After a transient wave of apoptotic cell death, cell proliferation started to increase 5 days after the lesion and persisted at high levels for at least 50 days. New cells differentiated into neurons, glia, and ependymal cells. Retrograde tract tracing revealed axonal re-growth and innervation of the regenerate. Functional regeneration was demonstrated by recovery of the amplitude of the electric organ discharge, a behavior generated by spinal motoneurons. Computer simulations indicated that the observed rates of apoptotic cell death and cell proliferation can adequately explain the re-growth of the spinal cord.

The social nature of termites has allowed them to become an ecologically dominant taxon. However, their nesting and foraging habits (decayed wood and/or soil), combined with frequent social interactions, enhances the risk of pathogen transmission. New dispersing kings and queens are especially vulnerable to pathogens due to the metabolic demands of nest construction, courtship, mating, oogenesis, and parental care, all while mounting an immune response to novel pathogens encountered upon leaving the natal nest. To quantify differential allocation of resources during colony establishment in response to disease exposure, Zootermopsis angusticollis kings and queens were paired after one or both individuals received an injection of saline, heat-killed Serratia marcescens (ecologically relevant, Gram-negative, soil bacterium), a sub-lethal dose of live S. marcescens, or were left untreated. We then quantified several indices of fitness, including the survival of the reproductive pair, onset and likelihood of oviposition, number of eggs produced, and egg quality as a function of parental immunological treatment. Our results uncovered complex and dynamic interactions between these fitness measures and pathogenic stress. Overall, pathogenic stress reduced the survival of kings and queens, the likelihood of oviposition and egg total, but not the onset of oviposition or egg quality, indicating that, in the face of disease, queens "opt" to maintain offspring quality over quantity. These impacts appear to be context-dependent-modulated by colony of origin, sex, mass, and the presence of a mate-rather than absolute. The acquisition of resources prior to colony foundation, combined with the effects of pathogenic exposure, can dramatically limit the success of termites. Based on these empirical data, we have developed a conceptual model of the first 30 days of colony life, involving two successive fitness checkpoints, survival and oviposition, followed by an initial growth phase in which the first egg cohort is produced. In summary, we identified not only the intrinsic and extrinsic factors that influence successful termite colony foundation, but also the maternal and paternal pathogen-induced effects. Such effects alter resource allocation decisions of parents toward their offspring, with cascading consequences on colony fitness.

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Zupanc GK, Ilieş I, Sîrbulescu RF, Zupanc MM. Large-scale identification of proteins involved in the development of a sexually dimorphic behavior. J Neurophysiol 111: 1646 -1654, 2014. First published January 29, 2014 doi:10.1152/jn.00750.2013.-Sexually dimorphic behaviors develop under the influence of sex steroids, which induce reversible changes in the underlying neural network of the brain. However, little is known about the proteins that mediate these activational effects of sex steroids. Here, we used a proteomics approach for large-scale identification of proteins involved in the development of a sexually dimorphic behavior, the electric organ discharge of brown ghost knifefish, Apteronotus leptorhynchus. In this weakly electric fish, the discharge frequency is controlled by the medullary pacemaker nucleus and is higher in males than in females. After lowering the discharge frequency by chronic administration of ␤-estradiol, 2-dimensional difference gel electrophoresis revealed 62 proteins spots in tissue samples from the pacemaker nucleus that exhibited significant changes in abundance of Ͼ1.5-fold. The 20 identified protein spots indicated, among others, a potential involvement of astrocytes in the establishment of the behavioral dimorphism. Indeed, immunohistochemical analysis demonstrated higher expression of the astrocytic marker protein GFAP and increased gapjunction coupling between astrocytes in females compared with males. We hypothesize that changes in the size of the glial syncytium, glial coupling, and/or number of glia-specific potassium channels lead to alterations in the firing frequency of the pacemaker nucleus via a mechanism mediating the uptake of extracellular potassium ions from the extracellular space. sexual dimorphism; weakly electric fish; proteomics; neural oscillator; astrocytes SEX DIFFERENCES IN BEHAVIOR are widespread among animals and occur most commonly during social interactions, particularly in the context of courtship and parental care. It is wellestablished that sex steroids play an overarching role in the control of this sexual dimorphism of behavior by influencing the organization of brain structures during development and by inducing reversible changes in neural circuits of the adult brain (Baum 2003;Morris et al. 2004). However, whereas sex differences in brain structures that control specific sexually dimorphic behaviors have been well-characterized (Cooke et al. 1998; Kelley 1988), little is known about the multitude of genes and proteins that regulate these behaviors and mediate the activational effects of sex steroids (Xu et al. 2012). To address this issue, we employed an unbiased, large-scale approach to identify such proteins using the electric organ discharge (EOD) of the weakly electric brown ghost knifefish (Apteronotus leptorhynchus) as a behavioral model that exhibits a reversible sexual dimorphism.In this species, the EOD is produced continuously by synchronous depolarization of modified axonal terminals of spinal electromotor neurons that constitute t...

Exogenously applied mature naïve B220+/CD19+/IgM+/IgD+ B cells are strongly protective in the context of tissue injury. However, the mechanisms by which B cells detect tissue injury and aid repair remain elusive. Here, we show in distinct models of skin and brain injury that MyD88‐dependent toll‐like receptor (TLR) signaling through TLR2/6 and TLR4 is essential for the protective benefit of B cells in vivo, while B cell‐specific deletion of MyD88 abrogated this effect. The B cell response to injury was multi‐modal with simultaneous production of both regulatory cytokines, such as IL‐10, IL‐35, and transforming growth factor beta (TGFβ), and inflammatory cytokines, such as tumor necrosis factor alpha (TNFα), IL‐6, and interferon gamma. Cytometry analysis showed that this response was time and environment‐dependent in vivo, with 20%–30% of applied B cells adopting an immune modulatory phenotype with high co‐expression of anti‐ and pro‐inflammatory cytokines after 18–48 h at the injury site. B cell treatment reduced the expression of TNFα and increased IL‐10 and TGFβ in infiltrating immune cells and fibroblasts at the injury site. Proteomic analysis further showed that B cells have a complex time‐dependent homeostatic effect on the injured microenvironment, reducing the expression of inflammation‐associated proteins, and increasing proteins associated with proliferation, tissue remodeling, and protection from oxidative stress. These findings chart and validate a first mechanistic understanding of the effects of B cells as an immunomodulatory cell therapy in the context of tissue injury.

The knifefish Apteronotus leptorhynchus exhibits indeterminate growth throughout adulthood. This phenomenon extends to the spinal cord, presumably through the continuous addition of new neurons and glial cells. However, little is known about the developmental dynamics of cells added during adult growth. The present work characterizes the structural and functional development of the adult spinal cord in this model organism through a comprehensive quantitative analysis of the spatial and temporal dynamics of new cells at various developmental stages. This analysis, based on a novel statistical mapping approach, revealed within the adult spinal cord a wide distribution of both mitotically active and quiescent Sox2-expressing stem/progenitor cells (SPCs). While such cells are particularly concentrated within the ependymal layer near the central canal, the majority of them reside in the parenchyma, resembling the distribution of SPCs observed in the mammalian spinal cord. The active SPCs in the adult knifefish spinal cord give rise to transit amplifying progenitor cells that undergo a few additional mitotic divisions before developing into Hu C/D+ neurons and S100+ glial cells. There is no evidence of long-distance migration of the newborn cells. The persistence of cell proliferation and differentiation, combined with low levels of apoptosis, leads to a continuous addition of cells to the existing tissue. Newly generated neurons have functional and behavioral relevance, as indicated by the integration of axons of new electromotor neurons into the electric organ of these weakly electric fish. This results in a gradual increase in the amplitude of the electric organ discharge during adult development. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1269-1307, 2017.