Possibility of production of amino acids by impact reaction using a light-gas gun as a simulation of asteroid impacts.

In order to investigate impact production of carbonaceous products by asteroids on Titan and other satellites and planets, simulation experiments were carried out using a 2-stage light gas gun. A small polycarbonate or metal bullet with about 6.5 km/s was injected into a pressurized target chamber filled with 1 atm of nitrogen gas, to collide with a ice + iron target or an iron target or a ice + hexane + iron target. After the impact, black soot including fine particles was deposited on the chamber wall. The soot was carefully collected and analyzed by High Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FT-IR), and Laser Desorption Time-of-Flight Mass Spectrometry (LD-ToF-MS). As a result of the HPLC analysis, about 0.04-8 pmol of glycine, and a lesser amount of alanine were found in the samples when the ice + hexane + iron target was used. In case of the ice + iron target and the iron target, less amino acids were produced. The identification of the amino acids was also supported by FTIR and LD-ToF-MS analysis.

Differential display analysis reveals the expression of glutathione S-transferase omega and novel genes through an ITAM-containing receptor in ascidian immunocytes.

The immunoreceptor tyrosine-based activation motif (ITAM) plays an important role in signal transduction through antigen receptors in mammalian lymphocytes. We previously reported that an ITAM-containing receptor, ascidian hemocyte ITAM-containing receptor 1 (AhITAMR1), exists on the hemocyte surfaces of the ascidian Halocynthia roretzi, and is involved in both phagocytosis and hemocyte aggregation. In this study, we carried out differential display screening of upregulated genes during H. roretzi hemocyte aggregation and found that at least three genes are upregulated. One encodes glutathione S-transferase omega (GSTomega), while the other two encode novel proteins. The expression of all three genes was induced by treatment with a specific monoclonal antibody against AhITAMR1, while their expression was inhibited by wortmannin, BAPTA-AM, and cyclosporin A. We also found that the expression of GSTomega was induced by treatment with anti-T cell receptor antibody in mouse peripheral T cells. We propose that signal transduction pathways mediated by ITAM-containing receptors are conserved from ascidian hemocytes to mammalian T cells.