Brain regeneration from pluripotent stem cells in planarian

How can planarians regenerate their brain? Recently we have identified many genes critical for this process. Brain regeneration can be divided into five steps: (1) anterior blastema formation, (2) brain rudiment formation, (3) pattern formation, (4) neural network formation, and (5) functional recovery. Here we will describe the structure and process of regeneration of the planarian brain in the first part, and then introduce genes involved in brain regeneration in the second part. Especially, we will speculate about molecular events during the early steps of brain regeneration in this review. The finding providing the greatest insight thus far is the discovery of the nou-darake (ndk; ‘brains everywhere’ in Japanese) gene, since brain neurons are formed throughout the entire body as a result of loss of function of the ndk gene. This finding provides a clue for elucidating the molecular and cellular mechanisms underlying brain regeneration. Here we describe the molecular action of the nou-darake gene and propose a new model to explain brain regeneration and restriction in the head region of the planarians.     

Analysis of changes in DNA copy number in radiation-induced thymic lymphomas of susceptible C57BL/6, resistant C3H and hybrid F1 Mice

Radiation-induced thymic lymphoma in mice is a useful model for studying both the mechanism of radiation carcinogenesis and genetic susceptibility to tumor development. Using array-comparative genomic hybridization, we analyzed genome-wide changes in DNA copy numbers in radiation-induced thymic lymphomas that had developed in susceptible C57BL/6 and resistant C3H mice and their hybrids, C3B6F1 and B6C3F1 mice. Besides aberrations at known relevant genetic loci including Ikaros and Bcl11b and trisomy of chromosome 15, we identified strain-associated genomic imbalances on chromosomes 5, 10 and 16 and strain-unassociated trisomy of chromosome 14 as frequent aberrations. In addition, biallelic rearrangements at Tcrb were detected more frequently in tumors from C57BL/6 mice than in those from C3H mice, suggesting aberrant V(D)J recombination and a possible link with tumor susceptibility. The frequency and spectrum of these copy-number changes in lymphomas from C3B6F1 and B6C3F1 mice were similar to those in C57BL/6 mice. Furthermore, the loss of heterozygosity analyses of tumors in F(1) mice indicated that allelic losses at Ikaros and Bcl11b were caused primarily by multilocus deletions, whereas those at the Cdkn2a/Cdkn2b and Pten loci were due mainly to uniparental disomy. These findings provide important clues to both the mechanisms for accumulation of aberrations during radiation-induced lymphomagenesis and the different susceptibilities of C57BL/6 and C3H mice.     

Cav2.1 Voltage-dependent Ca<Superscript>2+</Superscript> Channel Current is Inhibited by Serum from Select Patients with Guillain-Barré Syndrome

To investigate the pathophysiological mechanisms of immune-mediated peripheral neuropathies, we studied the effects of sera from patients with Guillain-Barré syndrome (GBS) on the Cav2.1 voltage-dependent calcium channel (VDCC) current in Purkinje cells. Using the whole-cell recording technique, Cav2.1 VDCC current was measured in cerebellar Purkinje cells in the presence of serum from GBS patients with acute motor axonal neuropathy (AMAN) or acute inflammatory demyelinating polyneuropathy (AIDP). The AMAN patient sera significantly inhibited the Cav2.1 VDCC current compared with healthy volunteer sera, and this inhibition was fully reversible by washing out the AMAN serum. Similarly, IgG purified from AMAN sera also inhibited the Cav2.1 VDCC current. However, the activation and inactivation kinetics of the Cav2.1 VDCC currents were not affected by serum from an AMAN patient. Moreover, the VDCC current of Purkinje cells was also inhibited by IgG anti-GM1 monoclonal antibody (anti-GM1 mAb). In an immunocytochemical study using double fluorescence staining, Purkinje cells were stained by monoclonal IgG anti-GM1 mAb. In contrast, AIDP patient and healthy volunteer sera did not affect the Cav2.1 VDCC current. These results suggest that in some case of GBS, particularly of AMAN patients with IgG anti-GM1 mAb, muscle weakness may be induced by dysfunction of Cav2.1 VDCC functioning at the motor nerve terminals. Special issue article in honor of Dr. George DeVries.     

Tonometric biosensor with a differential pressure sensor for chemo-mechanical measurement of glucose

A tonometric biosensor for glucose was constructed using a chemo-mechanical reaction unit and a differential pressure sensor. The reaction unit was fabricated by using both liquid and gas cells separated by an enzyme diaphragm membrane, in which glucose oxidase was immobilized onto the single (gas cell) side of the dialysis membrane. By applying glucose solution (0, 25.0, 50.0, 100, 150 and 200 mmol/l) into the liquid cell of the chemo-mechanical reaction unit, the pressure in the gas cell decreased continuously with a steady de-pressure slope because the oxygen consumption in the gas cell was induced by the glucose oxidase (GOD) enzyme reaction at the enzyme side of the porous diaphragm membrane. The steady de-pressure slope in the gas cell showed the linear relationship with the glucose concentration in the liquid cell between 25.0 and 200.0 mmol/l (correlation coefficient of 0.998). A substrate regeneration cycle coupling GOD with l-ascorbic acid (AsA: 0, 1.0, 3.0, 10.0 and 50.0 mmol/l; as reducing reagent system) was applied to the chemo-mechanical reaction unit in order to amplify the output signal of the tonometric biosensor. 3.0 mmol/l concentration of AsA could optimally amplify the sensor signal more than 2.5 times in comparison with that of non-AsA reagent.     

Development of continuous flow type hydrothermal reactor for hemicellulose fraction recovery from corncob

The semi-pilot scale of continuous flow type hydrothermal reactor has been investigated to separate hemicellulose fraction from corncob. We obtained the effective recovery of hemicellulose using tubular type reactor at 200 °C for 10 min. From constituent sugar analysis of corncob, 82.2% of xylan fraction was recovered as mixture of xylose, xylooligosaccharides and higher-xylooligosaccharide which has more than DP 10. During purification of solubilized fraction by hydrothermal reaction such as ultrafiltration and ion exchange resin, higher-xylooligosaccharide was recovered as the precipitate. This precipitate was identified as non-blanched xylan fraction which has from DP 11 to DP 21 mainly. In this system, only a small amount of furfural has been generated. This tubular reactor has a characteristic controllability of thermal history, and seems to be effective for sugar recovery from soft biomass like corncob.     

Extracellular matrix is required for the survival and differentiation of transplanted hepatic progenitor cells

Engelbreth-Holm-Swarm (EHS) gel has been reported to maintain the mature hepatocyte phenotypes in primary cultured hepatocytes. We investigated the effect of EHS gel on the differentiation of fetal liver cells, which contain stem/progenitor cells. The isolated fetal liver cells cultured on EHS gel formed a spherical shape and increased liver-specific gene expressions compared with cells cultured on collagen. The hepatic progenitor cells that were transplanted subcutaneously to BALB/c nude mice could survive and express hepatocyte marker alpha-fetoprotein when the cells were suspended with EHS gel. These findings demonstrate that EHS gel supports cytodifferentiation from immature progenitor cells to hepatocytes and maintain its differentiated phenotypes in vitro and in vivo.