RESUMEN
Dunaliella is a genus of wall-less unicellular eukaryotic green alga. Its exceptional resistances to salt and various other stresses have made it an ideal model for stress tolerance study. However, very little is known about its genome and genomic sequences. In this study, we sequenced and analyzed a 29,268 bp genomic fragment from Dunaliella viridis. The fragment showed low sequence homology to the GenBank database. At the nucleotide level, only a segment with significant sequence homology to 18S rRNA was found. The fragment contained six putative genes, but only one gene showed significant homology at the protein level to GenBank database. The average GC content of this sequence was 51.1%, which was much lower than that of close related green algae Chlamydomonas (65.7%). Significant segmental duplications were found within this fragment. The duplicated sequences accounted for about 35.7% of the entire region. Large amounts of simple sequence repeats (microsatellites) were found, with strong bias towards (AC)(n) type (76%). Analysis of other Dunaliella genomic sequences in the GenBank database (total 25,749 bp) was in agreement with these findings. These sequence features made it difficult to sequence Dunaliella genomic sequences. Further investigation should be made to reveal the biological significance of these unique sequence features.
Asunto(s)
Chlorophyta/genética , Genoma de Planta , Animales , Composición de Base , Chlamydomonas/genética , Bases de Datos de Ácidos Nucleicos , Secuencias Repetitivas de Ácidos Nucleicos , Análisis de Secuencia de ADN , Homología de Secuencia de Ácido NucleicoRESUMEN
FCA and FY are flowering time related genes involved in the autonomous flowering pathway in Arabidopsis. FCA interacts with FY to regulate the alternative processing of FCA pre-mRNA. The FCA/FY interaction is also required for the regulation of FLC expression, a major floral repressor in Arabidopsis. However, it is not clear if the regulation of this autonomous flowering pathway is also present in monocot plants, such as rice. Recently, alternative RNA processing of OsFCA was observed in rice, which strongly suggested the existence of an autonomous flowering pathway in rice. In this work, we cloned the cDNA of the autonomous flowering pathway gene OsFY from rice. The predicted OsFY protein contained a conserved 7 WD-repeat region and at least two Pro-Pro-Leu-Pro motifs compared to Arabidopsis FY. The protein-protein interaction between OsFY and OsFCA-gamma, the key feature of their gene function, was also demonstrated using the yeast two-hybrid system. The GenBank database search provided evidence of expression for other autonomous pathway gene homologs in rice. These results indicate that the autonomous flowering pathway is present in monocots, and the regulation through FY and FCA interaction is conserved between monocots and dicots.
Asunto(s)
Oryza/genética , Proteínas de Plantas/genética , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , Genes de Plantas , Datos de Secuencia Molecular , Proteínas de Plantas/metabolismo , Estructura Terciaria de Proteína , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Alineación de SecuenciaRESUMEN
Plasmid pSP124S with ble gene was transformed into D. salina cell by electroporation. The retention and expression of foreign gene in D.salina was explored, proper parameters were established. A large amount of foreign plasmid was found to be introduced into cells. The plasmid was degraded gradually, but can be detected within 96 hours. The ble gene was efficiently transcribed from foreign promoter and transcription was maintained at least 72 hours. The ble gene can be translated correctly and so can be used as a selectable marker for the research of genetic tranformation in D. salina.
Asunto(s)
Proteínas Bacterianas/metabolismo , Chlorophyta/metabolismo , Proteínas Bacterianas/genética , Western Blotting , Chlorophyta/genética , Electroporación , Plásmidos/genética , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The mono-component ribozyme RZ1, RZ3 and RZ4 were ligated in different orders into two tri-component ribozymes RZ134 and RZ413.Both tri-component ribozymes could cleave individual specific substrate sequences from different regions of the tobacco mosaic virus (TMV) RNA. The cleavage efficiency and specificity of each unit-ribozymes in the tri-component ribozymes to its substrate was similar to its mono-ribozyme counterpart. When the three substrates were mixed and used as substrates for the tri-component ribozymes, only the activity of the unit-ribozymes RZ4 was clearly observed, the activities of the other two unit-ribozymes were greatly reduced. The reduction was mainly due to the fact that the two substrates BT2(+) and BT2(-) for RZ1 and RZ3 were complementary in sequence to each other and therefore formed duplex in the target region, thus must have strongly prevented the two ribozymes from forming the correct structures required for cleavage activity. In addition to its activity on the substrate BT2(+), the ribozyme RZ1 was found unexpectedly to be able to cleave BT4(-) specifically into various unique products.
RESUMEN
Two defective mutants of the tobacco mosaic virus (TMV), TMVRP and TMVCP were constructed and assembled in vitro. In TMVRP, the 3'-end and part of the TMV coat protein (CP) gene was deleted; in TMRCP, most of the replicase genes were deleted. These mutant particles were separately or complementally inoculated into the tobacco protoplasts by electroporation. The synthesis of TMV coat protein was deteted by immuno dot-blot technique at 2 h after inoculation only in those complementally infected protoplasts. In addition, using the RT/PCR technique, the minus-strand viral RNA of the TMV 3'-end including CP gene was also only detected in those protoplasts which were complementally infected with both of the mutant particles. The synthesis of the minus-strand RNA started to be detectable at 1h after inoculation and it was confirmed by Southern blot analysis.