Translational in vitro activity of the 3a gene and the coat protein gene derived from brome mosaic virus RNA 3 by site-specific cleavage with RNase H

AbstractTwo translationally active fragments were derived from the dicistronic Brome Mosaic Virus (BMV) RNA 3 by site-specific cleavage with RNase H from E.coli: the 5′-proximal (L)fragment encoding the 32 kDa protein and the 3′-proximal (Sh) fragment carrying the coat protein gene. The translational efficiency of the L- and Sh-fragments was compared with those of the native BMV RNA 3 and RNA 4, encoding the 32 kDa and coat proteins, respectively. The Sh-fragment template activity was similar to that of RNA 4, although it was uncapped and contained 20–22 additional 5′-terminal nucleotides in comparison with BMV RNA 4

A Tobamovirus Genome That Contains an Internal Ribosome Entry Site Functionalin Vitro

AbstractMost eukaryotic mRNAs are translated by a “scanning ribosome” mechanism. We have found that unlike the type member of the genusTobamovirus,translation of the 3′-proximal coat protein (CP) gene of a crucifer infecting tobamovirus (crTMV) (Dorokhovet al.,1993; 1994) occurredin vitroby an internal ribosome entry mechanism. Three types of synthetic dicistronic RNA transcripts were constructed and translatedin vitro:(i) “MP-CP-3′NTR” transcripts contained movement protein (MP) gene, CP gene and the 3′-nontranslated region of crTMV RNA. These constructs were structurally equivalent to dicistronic subgenomic RNAs produced by tobamovirusesin vivo.(ii) “ΔNPT-CP” transcripts contained partially truncated neomycin phosphotransferase I gene and CP gene. (iii) “CP-GUS” transcripts contained the first CP gene and the gene ofEscherichia coliβ-glucuronidase (GUS) at the 3′-proximal position. The results indicated that the 148-nt region upstream of the CP gene of crTMV RNA contained an internal ribosome entry site (IRESCP) promoting internal initiation of translationin vitro.Dicistronic IRESCP, containing chimeric mRNAs with the 5′-terminal stem–loop structure preventing translation of the first gene (MP, ΔNPT, or CP), expressed the CP or GUS genes despite their 3′-proximal localization. The capacity of crTMV IRESCPfor mediating internal translation distinguishes this CP tobamovirus from the well-known-type member of the genus, TMV UI. The equivalent 148-nt sequence from TMV RNA was incapable of mediating internal translation. Two mutants were used to study structural elements of IRESCP. It was concluded that integrity of IRESCPwas essential for internal initiation. The crTMV provides a new example of internal initiation of translation, which is markedly distinct from IRESs shown for picornaviruses and other viral and eukaryotic mRNAs

Features of special joints of grain boundaries in polysilicon films of equiaxial and dendritic structures

Comparative analysis of special grain boundary joints in polysilicon films with equiaxial and dendritic (undoped and phosphorus-doped) structure, prepared by low-pressure chemical vapor deposition, has been carried out using atomic force microscopy and transmission electron microscopy. The formation mechanisms of special grain boundary joints have been analyzed for different film structures. The effect of phosphorus on formation of grain boundary joints has been analyzed.Методами атомной силовой микроскопии и просвечивающей электронной микроскопии проведен сравнительный анализ специальных стыков границ зерен в поликристал-лических пленках кремния с равноосной и дендритной структурой (нелегированных и легированных фосфором), полученных методом химического осаждения из газовой фазы в реакторе пониженного давления. Рассмотрены механизмы формирования специальных стыков в пленках разных структурных модификаций. Проанализирована роль фосфора в формировании стыков границ зерен.Методами атомної силової мікроскопії та просвічуючої електронної мікроскопії проведено порівняльний аналіз спеціальних стиків границь зерен та поверхневих неоднорідностей у полікристалічних плівках кремнію з рівноосьовою та дендритною структурою (нелегованих і легованих фосфором), отриманих методом хімічного осадження з газової фази в реакторі зниженого тиску. Розглянуто механізми формування спеціальних стиків у плівках різних структурних модифікацій. Проаналізовано роль фосфору у формуванні стиків границь зерен

Translation enhancing properties of the 5′-leader of potato virus X genomic RNA

AbstractThe double-stranded DNA copy corresponding to the 5′-nontranslated αβ-leader of potato virus X (PVX) genomic RNA (positions −3 to −85 according to AUG initiator) was chemically synthesized and fused to the transcription plasmids containing three different reporter genes: neomycinphosphotransferase type II (NPT II) gene, Bacillus thuringiensis coleopteran-specific toxic protein gene and β-glucuronidase (GUS) gene. Expression of the reporter genes in vitro and in plant protoplasts (in the case of GUS gene) reveals that the αβ-leader of PVX RNA acts as a translation enhancer despite the presence of the upstream vector-derived sequence and irrespective of the length of the spacer sequence preceding the reporter genes

Ganges in crystal structure of fullerene films at alloying and radiation defect formation

The crystal structure of the C₆₀ fullerene films with their alloying by the oxygen molecules and copper atoms in studied and under the influence of high energy eletron irradiation (Ee = 1.8 MeV) is investigated. It is shown that the crystal structure of the C₆₀ and C₇₀ films changes in the dependence on the concentration of impurity elements and radiation damages substantially infuluences the electronic and vibration spectra of fullerenes and is the result of the appearance in this case of additional Coulomb intermolecular interaction