The Dr-nanos gene is essential for germ cell specification in the planarian Dugesia ryukyuensis

Homologs of nanos are required for the formation and maintenance of germline stem cell (GSC) systems and for gametogenesis in many metazoans. Planarians can change their reproductive mode seasonally, alternating between asexual and sexual reproduction; they develop and maintain their somatic stem cells (SSCs) and GCSs from pluripotent stem cells known as neoblasts. We isolated a nanos homolog, Dr-nanos, from the expressed sequence tags (ESTs) of the sexualized form of Dugesia ryukyuensis. We examined the expression of Dr-nanos in asexual and sexualized planarians by in situ hybridization and analyzed its function using RNA interference (RNAi) together with a planarian sexualization assay. A nanos homolog, Dr-nanos, was identified in the planarian D. ryukyuensis. Dr-nanos expression was observed in the ovarian primordial cells of the asexual worms. This expression increased in proportion to sexualization and was localized in the early germline cells of the ovaries and testes. In X-ray-irradiated worms, the expression of Dr-nanos decreased to a large extent, indicating that Dr-nanos is expressed in some subpopulations of stem cells, especially in GSCs. During the sexualization process, worms in which Dr-nanos was knocked down by RNAi exhibited decreased numbers of oogonia in the ovaries and failed to develop testes, whereas the somatic sexual organs were not affected. We conclude that Dr-nanos is essential for the development of germ cells in the ovaries and testes and may have a function in the early stages of germ cell specification, but not in the development of somatic sexual organs.     

Proteomic analysis of endogenous nitrotryptophan-containing proteins in rat hippocampus and cerebellum

Nitration of tryptophan residues is a novel post-translational modification. In the present study, we examined whether NO₂Trp (nitrotryptophan)-containing proteins are produced in the hippocampus and cerebellum of the adult rat under physiological conditions in vivo. Using Western blot analysis with anti-6-NO₂Trp-specific antibody, we found many similar immunoreactive spots in the protein extracts from both regions. These spots were subsequently subjected to trypsin digestion and LC-ESI-MS/MS (LC-electrospray ionization-tandem MS) analysis. We identified several cytoskeletal proteins and glycolytic enzymes as NO₂Trp-containing proteins and determined the position of nitrated tryptophan residues with significant ion score levels (P<0.05) in several proteins in both regions. We also observed that the total amount of NO₂Trp-containing proteins in the cerebellum was significantly greater than that in the hippocampus (P<0.05). Moreover, IP (immunoprecipitation) assays using anti-aldolase C antibody showed that the relative intensity of immunostaining for NO₂Trp over aldolase C was much higher in cerebellum than in hippocampus. The amounts of nNOS (neuronal nitric oxide synthase) and eNOS (endothelial nitric oxide synthase) were much greater in cerebellum than in hippocampus. This is the first evidence of several specific sites of nitrated tryptophan in proteins under physiological conditions in vivo.     

Involvement of nicotinic acetylcholine receptor in the proliferation of mouse induced pluripotent stem cells

AimsAs the clinical use of induced pluripotent stem (iPS) cells may have the potential to overcome current obstacles in stem cell-based therapy, the molecular mechanisms that regulate the proliferation of iPS cells are of great interest. However, to our knowledge, no previous studies have examined whether stimulation with nicotinic acetylcholine receptor (nAchR) enhances the growth of iPS cells. In the present study, we examined the involvement of nAchR in the proliferation of mouse iPS cells.Main methodsWe performed immunofluorescence staining to determine whether mouse iPS cells could express nAchRs. Mouse iPS cells were treated with nicotine for 24 h under feeder-free conditions in the presence of leukemia inhibitory factor (LIF). The DNA synthesis was examined by the BrdU incorporation assay. Intracellular calcium levels were measured using Fluo-4-acetoxymethyl (a cell-permeable calcium indicator). In addition, we examined the involvement of the CaMKП pathway in nicotine-enhanced proliferation of mouse iPS cells.Key findingsThe fluorescence images revealed that α₄-nAchR and α₇-nAchR are expressed on mouse iPS cells. Treatment of the cells with 300 nM nicotine significantly increases DNA synthesis. This is significantly inhibited by pretreatment with antagonists of α₄-nAchR and α₇-nAchR or a CaMKП inhibitor. In addition, treatment with nicotine increases the intracellular Ca²⁺ level dose-dependently in mouse iPS cells. Treatment with nicotine significantly enhances CaMKП phosphorylation.SignificanceThe present study indicates that stimulation of α₄-nAchR and α₇-nAchR may lead to a significant increase in the rate of mouse iPS cell proliferation through enhancement of the CaMKП signaling pathway.     

Optical silencing of C. elegans cells with arch proton pump

BACKGROUND: Optogenetic techniques using light-driven ion channels or ion pumps for controlling excitable cells have greatly facilitated the investigation of nervous systems in vivo. A model organism, C. elegans, with its small transparent body and well-characterized neural circuits, is especially suitable for optogenetic analyses. METHODOLOGY/PRINCIPAL FINDINGS: We describe the application of archaerhodopsin-3 (Arch), a recently reported optical neuronal silencer, to C. elegans. Arch::GFP expressed either in all neurons or body wall muscles of the entire body by means of transgenes were localized, at least partially, to the cell membrane without adverse effects, and caused locomotory paralysis of worms when illuminated by green light (550 nm). Pan-neuronal expression of Arch endowed worms with quick and sustained responsiveness to such light. Worms reliably responded to repeated periods of illumination and non-illumination, and remained paralyzed under continuous illumination for 30 seconds. Worms expressing Arch in different subsets of motor neurons exhibited distinct defects in the locomotory behavior under green light: selective silencing of A-type motor neurons affected backward movement while silencing of B-type motor neurons affected forward movement more severely. Our experiments using a heat-shock-mediated induction system also indicate that Arch becomes fully functional only 12 hours after induction and remains functional for more than 24 hour. CONCLUSIONS/SGNIFICANCE: Arch can be used for silencing neurons and muscles, and may be a useful alternative to currently widely used halorhodopsin (NpHR) in optogenetic studies of C. elegans.     

Effects of geographic distance and climatic dissimilarity on species turnover in alpine meadow communities across a broad spatial extent on the Tibetan Plateau

Understanding the underlying mechanisms that generate species turnover or beta diversity among biological communities is a central theme in ecology. Here, we distinguish the effects of geographic distance and climatic dissimilarity on species turnover of vascular plants in alpine meadow communities on the Tibetan Plateau in China. We calculated species turnover between each pair of 17 sites, using the Jaccard??s and Simpson??s indices. We selected six variables to quantify climate at each site, and subjected values of the climatic variables to a principal component analysis. We applied a variance partitioning approach to disentangle the effects of geographic distance and climatic dissimilarity on species turnover in alpine meadow communities. We also examined the effect of elevation variation on species turnover. Geographic distance and climate dissimilarity together explained 49.1?% of the variation in compositional difference between alpine meadow communities; the amount of the variation explained purely by geographic distance and purely by climatic dissimilarity was 6.8?% and 2.8?%, respectively. When geographic distance, climate dissimilarity, and elevation difference were included in an analysis, they together explained 55?% of the variation in compositional difference between alpine meadow communities; the pure effect of each of the three sets of explanatory variables was 4.8, 4.3, and 3.5?%, respectively. The fact that the vast majority of the variation explained by geographic distance and climatic dissimilarity cannot be independently attributed to either factor suggests that the two factors operate together in determining regional patterns of species composition in alpine meadows on the Tibetan Plateau.     

Molecular Evolution of Hemagglutinin (H) Gene in Measles Virus Genotypes D3, D5, D9, and H1

We studied the molecular evolution of H gene in four prevalent Asian genotypes (D3, D5, D9, and H1) of measles virus (MeV). We estimated the evolutionary time scale of the gene by the Bayesian Markov Chain Monte Carlo (MCMC) method. In addition, we predicted the changes in structure of H protein due to selective pressures. The phylogenetic tree showed that the first division of these genotypes occurred around 1931, and further division of each type in the 1960–1970s resulted in four genotypes. The rate of molecular evolution was relatively slow (5.57×10⁻⁴ substitutions per site per year). Only two positively selected sites (F476L and Q575K) were identified in H protein, although these substitutions might not have imparted significant changes to the structure of the protein or the epitopes for phylactic antibodies. The results suggested that the prevalent Asian MeV genotypes were generated over approximately 30–40 years and H protein was well conserved.     

Dysregulation of suppressor of cytokine signaling 3 in keratinocytes causes skin inflammation mediated by interleukin-20 receptor-related cytokines

Homeostatic regulation of epidermal keratinocytes is controlled by the local cytokine milieu. However, a role for suppressor of cytokine signaling (SOCS), a negative feedback regulator of cytokine networks, in skin homeostasis remains unclear. Keratinocyte specific deletion of Socs3 (Socs3 cKO) caused severe skin inflammation with hyper-production of IgE, epidermal hyperplasia, and S100A8/9 expression, although Socs1 deletion caused no inflammation. The inflamed skin showed constitutive STAT3 activation and up-regulation of IL-6 and IL-20 receptor (IL-20R) related cytokines, IL-19, IL-20 and IL-24. Disease development was rescued by deletion of the Il6 gene, but not by the deletion of Il23, Il4r, or Rag1 genes. The expression of IL-6 in Socs3 cKO keratinocytes increased expression of IL-20R-related cytokines that further facilitated STAT3 hyperactivation, epidermal hyperplasia and neutrophilia. These results demonstrate that skin homeostasis is strictly regulated by the IL-6-STAT3-SOCS3 axis. Moreover, the SOCS3-mediated negative feedback loop in keratinocytes has a critical mechanistic role in the prevention of skin inflammation caused by hyperactivation of STAT3.     

Disruption of rolandic gamma-band functional connectivity by seizures is associated with motor impairments in children with epilepsy

Although children with epilepsy exhibit numerous neurological and cognitive deficits, the mechanisms underlying these impairments remain unclear. Synchronization of oscillatory neural activity in the gamma frequency range (>30 Hz) is purported to be a mechanism mediating functional integration within neuronal networks supporting cognition, perception and action. Here, we tested the hypothesis that seizure-induced alterations in gamma synchronization are associated with functional deficits. By calculating synchrony among electrodes and performing graph theoretical analysis, we assessed functional connectivity and local network structure of the hand motor area of children with focal epilepsy from intracranial electroencephalographic recordings. A local decrease in inter-electrode phase synchrony in the gamma bands during ictal periods, relative to interictal periods, within the motor cortex was strongly associated with clinical motor weakness. Gamma-band ictal desychronization was a stronger predictor of deficits than the presence of the seizure-onset zone or lesion within the motor cortex. There was a positive correlation between the magnitude of ictal desychronization and impairment of motor dexterity in the contralateral, but not ipsilateral hand. There was no association between ictal desynchronization within the hand motor area and non-motor deficits. This study uniquely demonstrates that seizure-induced disturbances in cortical functional connectivity are associated with network-specific neurological deficits.     

Differences in Salivary Alpha-Amylase and Cortisol Responsiveness following Exposure to Electrical Stimulation versus the Trier Social Stress Tests

Background

Cortisol is an essential hormone in the regulation of the stress response along the HPA axis, and salivary cortisol has been used as a measure of free circulating cortisol levels. Recently, salivary alpha-amylase (sAA) has also emerged as a novel biomarker for psychosocial stress responsiveness within the sympathetic adrenomedullary (SAM) system.

Principal Findings

We measured sAA and salivary cortisol in healthy volunteers after exposure to the Trier Social Stress Test (TSST) and electric stimulation stress. One hundred forty-nine healthy volunteers participated in this study. All subjects were exposed to both the TSST and electric stimulation stress on separate days. We measured sAA and salivary cortisol levels three times immediately before, immediately after, and 20 min after the stress challenge. The State (STAI-S) and Trait (STAI-T) versions of the Spielberger Anxiety Inventory test and the Profile of Mood State (POMS) tests were administered to participants before the electrical stimulation and TSST protocols. We also measured HF, LF and LF/HF Heart Rate Variability ratio immediately after electrical stimulation and TSST exposure. Following TSST exposure or electrical stimulation, sAA levels displayed a rapid increase and recovery, returning to baseline levels 20 min after the stress challenge. Salivary cortisol responses showed a delayed increase, which remained significantly elevated from baseline levels 20 min after the stress challenge. Analyses revealed no differences between men and women with regard to their sAA response to the challenges (TSST or electric stimulations), while we found significantly higher salivary cortisol responses to the TSST in females. We also found that younger subjects tended to display higher sAA activity. Salivary cortisol levels were significantly correlated with the strength of the applied electrical stimulation.

Conclusions

These preliminary results suggest that the HPA axis (but not the SAM system) may show differential response patterns to distinct kinds of stressors.