RESUMO
Classical approaches to the development of vaccines have provided mankind with a number of safe and effective vaccines (think of the world-wide eradication of smallpox). Nevertheless, some obstacles e.g. the production of a safe Hepatitis B vaccine, could not be taken by classical techniques. In several cases, recombinant-DNA technology provided an elegant solution, though in other cases, this technique also failed. The present paper presents a brief review of the role of recombinant-DNA technology in the current development of vaccines.
Assuntos
Vacinação/veterinária , Vacinas Atenuadas/isolamento & purificação , Vacinas/isolamento & purificação , Adjuvantes Imunológicos , Animais , DNA Recombinante , Vacinas Atenuadas/administração & dosagem , Vacinas de Produtos Inativados/isolamento & purificação , Vacinas Sintéticas/isolamento & purificaçãoAssuntos
Baculoviridae/genética , Vetores Genéticos , Vacinas Sintéticas/biossíntese , Vacinas Virais/biossíntese , Animais , Células Cultivadas , Regulação Viral da Expressão Gênica , Humanos , Insetos , Processamento de Proteína Pós-Traducional , Vacinas Sintéticas/genética , Proteínas Virais/biossíntese , Proteínas Virais/metabolismo , Vacinas Virais/genéticaRESUMO
The nucleotide sequences of the genes coding for tRNAArgUCU, tRNAArgACG and tRNAAsnGUU on chloroplast DNA of Spirodela oligorhiza have been determined. All three genes are expressed. 5' Proximal to these genes sequences are found homologous to prokaryotic promoter sequences, which might be involved as transcriptional start motifs.
Assuntos
Cloroplastos/fisiologia , RNA de Transferência , Arginina , Asparagina , Sequência de Bases , Clonagem Molecular , Genes , Conformação de Ácido Nucleico , PlantasRESUMO
The genes for the two large ribosomal RNAs (16S and 23S) and for the 4.5S rRNA in Spirodela oligorhiza chloroplast DNA are transcribed as one large, 7,000 nucleotides long precursor rRNA.Using S1-nuclease mapping, we have determined that the transcript ends 135 nucleotides 3' distal of the 4.5S rRNA gene. 5S rRNA therefore, is most likely transcribed separately.Northern blotting of chloroplast RNA with distinct probes derived from the rDNA region reveals RNAs, which can be described as intermediates in the processing of the large precursor. With these findings a pathway for the maturation of this precursor is proposed.
RESUMO
The nucleotide sequences of the flanking regions of the genes coding for Spirodela oligorhiza chloroplast ribosomal RNA's have been determined. We have compared these sequences to the corresponding ones in chloroplast DNA of other plants and of E. coli and find a striking sequential or structural homology. The region 5'-proximal to the gene coding for 16S rRNA contains a gene coding for tRNAval, which is transcribed from the same strand. In this area three prokaryotic promoter motifs are found: one located in front of the tRNAval gene and two in the intergenic space between this gene and the 16S rRNA gene. The middle one is used for the start of the transcription of the large ribosomal RNA precursor.
Assuntos
Cloroplastos/metabolismo , DNA/genética , Genes , Plantas/genética , RNA Ribossômico/genética , Sequência de Bases , Enzimas de Restrição do DNA , Escherichia coli/genética , Conformação de Ácido Nucleico , Especificidade da EspécieRESUMO
The base sequence of Spirodela oligorhiza chloroplast DNA coding for 4.5S and 5S ribosomal RNA, the flanking regions and the spacer between these two genes has been determined. We have compared these sequences with the corresponding ones in other higher plants. Besides a high degree of homology, some interesting differences are found.
Assuntos
Cloroplastos/análise , DNA/genética , Genes , RNA Ribossômico/genética , Sequência de Bases , Enzimas de Restrição do DNA , DNA Ribossômico , Peso Molecular , Conformação de Ácido Nucleico , Plantas/genéticaRESUMO
The organization of the chloroplast ribosomal RNA genes in Spirodela oligorhiza has been determined. We have therefore characterized two cloned BamHI fragments containing the genes for the large and small rRNA genes, and two PstI fragments, each containing one of the two large, invertedly repeated regions of chloroplast DNA. Characterization was performed by restriction endonuclease mapping, DNA/RNA hybridization and electronmicroscopic R-loop analysis.The results show that the rRNA genes are present in the order 16S, 23S, 4.5S and 5S. The 16S (1.5 kb) and 23S (2.9 kb) rRNA genes are separated by a spacer of 2.25 kb. There appears to be a close resemblance between the organization of the chloroplast rRNA genes in Spirodela oligorhiza and other higher plants so far examined.