RESUMEN
It is currently thought that chloroplasts of higher plants were derived from endosymbiont oxygenic photosynthetic bacteria (primary endosymbiosis), while Euglena, a photosynthetic protista, gained chloroplasts by secondary endosymbiosis (i.e., incorporation of a photosynthetic eukaryote into heterotrophic eukaryotic host). To examine if the protein transport inside chloroplasts is similar between these organisms, we carried out heterologous protein import experiments with Euglena precursor proteins and spinach chloroplasts. The precursor of a 30-kDa subunit of the oxygen-evolving complex (OEC30) from the thylakoid lumen of Euglena chloroplasts contained the N-terminal signal, stroma targeting, and thylakoid transfer domains. Truncated preOEC30s lacking the N-terminal domain were post-translationally imported into spinach chloroplasts, transported into the thylakoid lumen, and processed to a mature protein. These results showed that protein translocations within chloroplasts in Euglena and higher plants are similar and supported the hypothesis that Euglena chloroplasts are derived from the ancestral Chlorophyta.
Asunto(s)
Proteínas Algáceas , Cloroplastos/metabolismo , Cloroplastos/fisiología , Euglena/metabolismo , Proteínas del Complejo del Centro de Reacción Fotosintética/metabolismo , Complejo de Proteína del Fotosistema II , Proteínas/metabolismo , Proteínas Protozoarias , Adenosina Trifosfato/farmacología , Secuencia de Aminoácidos , Animales , Evolución Biológica , ADN Complementario/metabolismo , Relación Dosis-Respuesta a Droga , Electroforesis en Gel de Poliacrilamida , Euglena/química , Datos de Secuencia Molecular , Proteínas del Complejo del Centro de Reacción Fotosintética/química , Plásmidos/química , Biosíntesis de Proteínas , Procesamiento Proteico-Postraduccional , Estructura Terciaria de Proteína , Transporte de Proteínas , Homología de Secuencia de Aminoácido , Spinacia oleracea/química , Spinacia oleracea/metabolismo , Tilacoides/química , Factores de Tiempo , Transcripción GenéticaAsunto(s)
Antineoplásicos/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias del Colon/tratamiento farmacológico , Ensayo de Unidades Formadoras de Colonias , Neoplasias Ováricas/tratamiento farmacológico , Ensayo de Tumor de Célula Madre , Ensayos Clínicos como Asunto , Evaluación Preclínica de Medicamentos , Femenino , Humanos , Técnicas In VitroRESUMEN
Colony forming ability of solid tumor cells was studied in a tumor colony assay (human tumor stem cell assay). In 50 cases of solid tumors, cloning efficiencies of 5 X 10(5) cells plated were as follows: breast cancer 12/12 (100%), colon cancer 10/11 (91%), ovarian cancer 9/9 (100%), sarcomas 7/9 (78%), gastric cancer 3/6 (50%), endometrial cancer 2/2 and pancreatic cancer 1/1. An overall cloning efficiency was 88% (44/50) and this rate is higher than those reported in literatures. Ovarian cancer showed the highest plating efficiency of 0.07% (number of colonies/number of cells plated X 100%) in various solid tumors tested. Subsequently, plating efficiencies of colon and breast cancer were 0.03 and 0.01%, respectively. In the cases of sarcomas and gastric cancer, low plating efficiencies were seen (0.008%, 0.003%). The overall rate succeeded colony growth of solid tumors was somewhat higher in enzymatically treated tumor cells, that is, cloning efficiencies in mechanical and enzymatic methods were 85 and 90%, respectively. The enzymatic disaggregation is an advantageous method in gastric cancer and sarcomas. Various solid tumors can be formed colonies in soft agar and chemosensitivity test using in vitro colony assay is expected in solid tumors.