Transcranial Direct Current Stimulation (tDCS) Induces Adrenergic Receptor-Dependent Microglial Morphological Changes in Mice.

Transcranial direct current stimulation (tDCS) has been reported for its beneficial effects on memory formation and various brain disorders. While the electrophysiological readout of tDCS effects is subtle, astrocytes have been demonstrated to elicit Ca2+ elevations during tDCS in a rodent model. This study aimed to elucidate the effects of tDCS on another major glial cell type, microglia, by histology and in vivo imaging. tDCS performed in awake conditions induced a significant change in the pixel intensity distribution of Iba-1 immunohistochemistry, and microglial somata were enlarged when examined 3 h after tDCS. These effects were blocked by adrenergic receptor antagonists or in IP3R2 (inositol trisphosphate receptor type 2)-deficient mice, which lack large cytosolic Ca2+ elevations in astrocytes. No obvious changes were observed in isoflurane-anesthetized mice. Furthermore, in vivo two-photon imaging of microglia showed a reduction of motility that was blocked by a ß2-adrenergic receptor antagonist. Our observations add support for the influence of noradrenaline in tDCS and suggest possible interactions between microglia and astrocytes to express functional changes associated with tDCS.

Elimination of eosinophils using anti-IL-5 receptor alpha antibodies effectively suppresses IL-33-mediated pulmonary arterial hypertrophy.

Interleukin (IL)-5 is a critical regulator of eosinophils and a therapeutic target for asthma. The administration of anti-IL-5 or anti-IL-5 receptor (IL-5R) antibodies has been shown to reduce eosinophil counts and ameliorate asthmatic symptoms in studies on animal models of allergy as well as in human clinical trials. In order to explore other potential clinical uses of IL-5R antibodies, we used an animal model of IL-33-mediated pulmonary arterial hypertrophy. We first generated chimeric monoclonal antibodies against the mouse IL-5 receptor α chain (IL-5Rα), which comprised an Fc region from human IgG1 and a Fab region from a previously established anti-mouse IL-5Rα monoclonal antibody. To investigate the role of antibody-dependent cell-mediated cytotoxicity (ADCC), chimeric antibodies that lacked ADCC were prepared. These antibodies recognized IL-5Rα to the same extent as the ADCC-sufficient antibodies. Administration of chimeric antibodies with ADCC resulted in the elimination of eosinophils from the lung and thus suppressed the development of arterial hypertrophy. This effect was attenuated in mice treated with antibodies lacking ADCC. Taken together, the results of this study provided a potential use for anti-IL-5Rα antibodies in the treatment of arterial hypertrophy, which leads to pulmonary hypertension.

Astroglial glutamate transporter deficiency increases synaptic excitability and leads to pathological repetitive behaviors in mice.

An increase in the ratio of cellular excitation to inhibition (E/I ratio) has been proposed to underlie the pathogenesis of neuropsychiatric disorders, such as autism spectrum disorders (ASD), obsessive-compulsive disorder (OCD), and Tourette's syndrome (TS). A proper E/I ratio is achieved via factors expressed in neuron and glia. In astrocytes, the glutamate transporter GLT1 is critical for regulating an E/I ratio. However, the role of GLT1 dysfunction in the pathogenesis of neuropsychiatric disorders remains unknown because mice with a complete deficiency of GLT1 exhibited seizures and premature death. Here, we show that astrocyte-specific GLT1 inducible knockout (GLAST(CreERT2/+)/GLT1(flox/flox), iKO) mice exhibit pathological repetitive behaviors including excessive and injurious levels of self-grooming and tic-like head shakes. Electrophysiological studies reveal that excitatory transmission at corticostriatal synapse is normal in a basal state but is increased after repetitive stimulation. Furthermore, treatment with an N-methyl-D-aspartate (NMDA) receptor antagonist memantine ameliorated the pathological repetitive behaviors in iKO mice. These results suggest that astroglial GLT1 has a critical role in controlling the synaptic efficacy at corticostriatal synapses and its dysfunction causes pathological repetitive behaviors.

Retroviral vectors for homologous recombination provide efficient cloning and expression in mammalian cells.

Homologous recombination technologies enable high-throughput cloning and the seamless insertion of any DNA fragment into expression vectors. Additionally, retroviral vectors offer a fast and efficient method for transducing and expressing genes in mammalian cells, including lymphocytes. However, homologous recombination cannot be used to insert DNA fragments into retroviral vectors; retroviral vectors contain two homologous regions, the 5'- and 3'-long terminal repeats, between which homologous recombination occurs preferentially. In this study, we have modified a retroviral vector to enable the cloning of DNA fragments through homologous recombination. To this end, we inserted a bacterial selection marker in a region adjacent to the gene insertion site. We used the modified retroviral vector and homologous recombination to clone T-cell receptors (TCRs) from single Epstein Barr virus-specific human T cells in a high-throughput and comprehensive manner and to efficiently evaluate their function by transducing the TCRs into a murine T-cell line through retroviral infection. In conclusion, the modified retroviral vectors, in combination with the homologous recombination method, are powerful tools for the high-throughput cloning of cDNAs and their efficient functional analysis.

A new cloning and expression system yields and validates TCRs from blood lymphocytes of patients with cancer within 10 days.

Antigen-specific T cell therapy, or T cell receptor (TCR) gene therapy, is a promising immunotherapy for infectious diseases and cancers. However, a suitable rapid and direct screening system for antigen-specific TCRs is not available. Here, we report an efficient cloning and functional evaluation system to determine the antigen specificity of TCR cDNAs derived from single antigen-specific human T cells within 10 d. Using this system, we cloned and analyzed 380 Epstein-Barr virus-specific TCRs from ten healthy donors with latent Epstein-Barr virus infection and assessed the activity of cytotoxic T lymphocytes (CTLs) carrying these TCRs against antigenic peptide-bearing target cells. We also used this system to clone tumor antigen-specific TCRs from peptide-vaccinated patients with cancer. We obtained 210 tumor-associated antigen-specific TCRs and demonstrated the cytotoxic activity of CTLs carrying these TCRs against peptide-bearing cells. This system may provide a fast and powerful approach for TCR gene therapy for infectious diseases and cancers.

Cerebral blood flow modulation by Basal forebrain or whisker stimulation can occur independently of large cytosolic Ca2+ signaling in astrocytes.

We report that a brief electrical stimulation of the nucleus basalis of Meynert (NBM), the primary source of cholinergic projection to the cerebral cortex, induces a biphasic cerebral cortical blood flow (CBF) response in the somatosensory cortex of C57BL/6J mice. This CBF response, measured by laser Doppler flowmetry, was attenuated by the muscarinic type acetylcholine receptor antagonist atropine, suggesting a possible involvement of astrocytes in this type of CBF modulation. However, we find that IP3R2 knockout mice, which lack cytosolic Ca2+ surges in astrocytes, show similar CBF changes. Moreover, whisker stimulation resulted in similar degrees of CBF increase in IP3R2 knockout mice and the background strain C57BL/6J. Our results show that neural activity-driven CBF modulation could occur without large cytosolic increases of Ca2+ in astrocytes.

Astrocyte calcium signaling transforms cholinergic modulation to cortical plasticity in vivo.

Global brain state dynamics regulate plasticity in local cortical circuits, but the underlying cellular and molecular mechanisms are unclear. Here, we demonstrate that astrocyte Ca(2+) signaling provides a critical bridge between cholinergic activation, associated with attention and vigilance states, and somatosensory plasticity in mouse barrel cortex in vivo. We investigated first whether a combined stimulation of mouse whiskers and the nucleus basalis of Meynert (NBM), the principal source of cholinergic innervation to the cortex, leads to enhanced whisker-evoked local field potential. This plasticity is dependent on muscarinic acetylcholine receptors (mAChR) and N-methyl-d-aspartic acid receptors (NMDARs). During the induction of this synaptic plasticity, we find that astrocytic [Ca(2+)](i) is pronouncedly elevated, which is blocked by mAChR antagonists. The elevation of astrocytic [Ca(2+)](i) is crucial in this type of synaptic plasticity, as the plasticity could not be induced in inositol-1,4,5-trisphosphate receptor type 2 knock-out (IP(3)R2-KO) mice, in which astrocytic [Ca(2+)](i) surges are diminished. Moreover, NBM stimulation led to a significant increase in the extracellular concentration of the NMDAR coagonist d-serine in wild-type mice when compared to IP(3)R2-KO mice. Finally, plasticity in IP(3)R2-KO mice could be rescued by externally supplying d-serine. Our data present coherent lines of in vivo evidence for astrocytic involvement in cortical plasticity. These findings suggest an unexpected role of astrocytes as a gate for cholinergic plasticity in the cortex.

Hybrid male sterility between the fresh- and brackish-water types of ninespine stickleback Pungitius pungitius (Pisces, Gasterosteidae).

Two ecologically distinct forms, fresh- and brackish-water types, of ninespine stickleback co-exist in several freshwater systems on the coast of eastern Hokkaido. Recent genetic analyses of 13 allozyme loci revealed genetic separation between the two types even though their spawning grounds were in close proximity. On the other hand, there is only a small difference in mitochondrial DNA (mtDNA) sequence between the two types suggesting that they diverged quite recently or that mtDNA introgression occurred between them. To test for postzygotic reproductive isolating mechanisms and hybrid mediated gene flow, we examined the viability and reproductive performance of reciprocal F1 hybrids. The hybrids grew to the adult size normally and both sexes expressed secondary sexual characters in the reciprocal crosses. The female hybrids were reciprocally fertile, while the male hybrids were reciprocally sterile. Histological and flow-cytometric analyses of the hybrid testis revealed that the sterility pattern was classified as 'gametic sterility,' with gonads of normal size but abnormal spermatogenesis. To our knowledge, the present finding is a novel example of one sex hybrid sterility in the stickleback family (Gasterosteidae).

Localized maternal factors are required for zebrafish germ cell formation.

Maternally supplied factors in fertilized eggs play essential roles in the establishment of primordial germ cells. In zebrafish, cytoplasm at the distal ends of the first and second cleavage furrows has been assumed to contain germ lineage determinants, since maternal transcripts of germ lineage-specific genes are localized to ends of the cleavage furrows. To investigate whether these parts of cytoplasm are required for germ cell formation, we removed all four regions of the cytoplasm by glass capillary at the 4-cell stage. Histological analysis revealed that the ablation of cytoplasm at the ends of the cleavage planes resulted in a severe reduction in the number of germ cells. In addition, the expression of germ lineage markers was eliminated by cytoplasmic ablation. These results demonstrated that cytoplasm at the distal ends of cleavage furrows is essential for germ cell formation. We also found novel localization patterns for zDazl and brul mRNAs along the cleavage planes. Our findings provide the first direct evidence that localized cytoplasmic factors are indispensable for germ cell establishment in zebrafish.

Pluripotency of cryopreserved blastomeres of the goldfish.

To examine the pluripotency of cryopreserved blastomeres, we transplanted them into blastula. Donor blastomeres were prepared from blastula of goldfish (Carassius auratus) and cryopreserved in liquid nitrogen for two months. Fifty-five percent and 44% of blastomeres survived after thawing. Cryopreserved blastomeres were transplanted to the blastula of triploid crucian carp (C. a. longsdorfii), which reproduces gynogenetically in nature. At four days after the operation, resultant chimeric embryos transplanted with cryopreserved blastomeres showed a survival rate (41.6%) lower than that of embryos transplanted with unfrozen blastomeres (57.1%). Transplanted blastomeres were histologically identified in various organs derived from all three germ layers. A primordial germ cell differentiated from a cryopreserved blastomere was detected in one of the 32 chimeric fish examined. These results suggest blastomeres that survive after cryopreservation retain their pluripotency and are able to differentiate into both somatic and germ cell lines.

Germ cell lineage from a single blastomere at 8-cell stage in shiro-uo (ice goby).

Shiro-uo (ice goby; teleost fish), Leucopsarion petersii, shows a unique cleavage pattern characterized by two tires of blastomeres at 8-cell stage, like that of echinoderm and amphibian embryo. Such a pattern is suitable to isolation and cell lineage experiments. In this study, cell lineage of germ-line was traced by histological observation and cell labelling experiment at the 8-cell stage. Primordial germ cells (PGCs) were first detected histologically at the 10-somite stage, and migrated to gonadal anlage at 10 days post-fertilization, through usual way described in other teleost species. When a single blastomere was labelled with tracer dye at 8-cell stage, both upper and lower tires generated labelled PGCs at gonadal anlage although upper tires occasionally. This result suggests that all blastomeres at the 8-cell stage have potential to produce PGCs in shiro-uo.