A Soluble Chloroplast Protease Processes the Euglena Polyprotein Precursor to the Light Harvesting Chlorophyll a/b Binding Protein of Photosystem II

The Euglena light harvesting chlorophyll a/b binding proteinof photosystem II (LHCPII) is synthesized as a polyprotein precursorscomposed of 8 LHCPIIs covalently joined by a decapeptide. Asoluble chloroplast protease releases LHCPII from the polyprotein.The polyprotein processing peptidase has a pH optima between8.0 and 9.0. It is inhibited by Zn²⁺, Cu²⁺, phenylmethylsulfonylfluoride and E64 suggesting it is a novel thiol protease. ¹ Present address: Department of Food Sciences, Ishikawa AgriculturalCollege, Nonoichi, Ishikawa, 921 Japan.     

Expression profiles and functional characterization of common carp (Cyprinus carpio) T2Rs

Bitter taste perception is mediated by a family of G protein-coupled receptors (T2Rs) in vertebrates. Common carp (Cyprinus carpio), which has experienced an additional round of whole genome duplication during the course of evolution, has a small number of T2R genes similar to zebrafish, a closely related cyprinid fish species, and their expression pattern at the cellular level or their cognate ligands have not been elucidated yet. Here, we showed through in situ hybridization experiments, that three common carp T2R (ccT2R) genes encoding ccT2R200-1, ccT2R202-1, and ccT2R202-2, were specifically expressed in the subsets of taste receptor cells in the lips and gill rakers. ccT2R200-1 was co-expressed with genes encoding downstream signal transduction molecules, such as PLC-β2 and Gαia. Heterologous expression system revealed that each ccT2R showed narrowly, intermediately, or broadly tuned ligand specificity, as in the case of zebrafish T2Rs. However, ccT2Rs showed different ligand profiles from their orthologous zebrafish T2Rs previously reported. Finally, we identified three ccT2Rs, namely ccT2R200-1, ccT2R200-2, and ccT2R203-1, to be activated by natural bitter compounds, andrographolide and/or picrotoxinin, which elicited no response to zebrafish T2Rs, in a dose-dependent manner. These results suggest that some ccT2Rs may have evolved to function in the oral cavity as taste receptors for natural bitter compounds found in the habitats in a species-specific manner.     

Postembryonic development of the ovary in the penicillate diplopod,Eudigraphis nigricans (Miyosi) (Diplopoda,Penicillata)

Postembryonic development of the ovary through the larval stages was studied in a penicillate diplopod, Eudigraphis nigricans. In the first instar larva a single young cell cluster, consisting of about 20 spherical gonial cells and some smaller interstitial cells, exists beneath the alimentary canal in the third body segment. The gonadal epithelium encompasses the upper surface of this young cell cluster by the end of the first instar. The epithelium then extends forward and backward to form a single long sac-like gonad, leaving the young cell cluster on the center of the gonadal floor as a mound-shaped germarium. In an early second-instar larva, very early previtellogenic oocytes accompanied by some interstitial cells appear in the front and rear surfaces of the ovarian germarium. During the period from the third through the seventh (the last) larval instar, some cell clusters containing several previtellogenic oocytes and interstitial cells successively separate forward and backward from the germarium to form a series of paired patch-shaped vitellarial areas on the extending ventral ovarian epithelium. In each vitellarial area, some of the interstitial cells surround the oocytes to form the follicles. In the seventh instar, the ovarian lumen is extremely expanded, and the late previtellogenic oocytes in the vitellarial areas encroach upward into the ovarian lumen. These oocytes floating in the ovarian lumen are still connected with their own vitellarial areas by partial extensions of their follicles. Some phylogenetic implications of the basic characteristics in structure and postembryonic development of the ovary are discussed. © 1995 Wiley-Liss, Inc.     

Detection of the Leghemoglobin Gene on Two Chromosomes of Phaseolus vulgaris by in situ PCR Linked-Fluorescent in situ Hybridization (FISH)

The leghemoglobin (Lb) gene on the metaphase chromosomes ofPhaseolus vulgaris was amplified by in situ PCR. The amplifiedLb gene could be detected on two chromosomes by fluorescentin situ hybridization (FISH) using the short Lb gene probe. (Received January 9, 1998; Accepted April 30, 1998)