Tyrosinases of motile Azospirillum strains

A number of motile strains of Azospirillum brasilense, A. lipoferum, and A. irakense, were found to possess tyrosinase activity both on the surface of and inside the cells. A. brasilense Sp245, Sp7, and A. irakense KBC-1 each possessed two forms of tyrosinase of different molecular masses; A. lipoferum 43, A. lipoferum 59b, and A. irakense KA-3 each had a single tyrosinase form of approximately the same molecular mass; and A. brasilense Sp107 possessed a single form of tyrosinase different from all the other forms.     

The ability of the rhizobacterium Azospirillum brasilense to reduce selenium(IV) to selenium(0)

Effect of selenium(+4) as selenite (Se ₃ ^2? ) on two Azospirillum brasilense strains, which occupy different ecological niches (an epiphyte Sp7 and a facultative endophyte Sp245), was studied. The cultures grown in the medium with sodium selenite exhibited intense red coloration. Transmission electron microscopy and X-ray fluorescence analysis revealed accumulation of elementary selenium within the cells of both strains as nanoparticles 50–400 nm in diameter. The ability to reduce inorganic selenium(+4) to elementary selenium (as nanoparticles) has not been previously reported for azospirilla. Our results indicate the possibility to apply Azospirillum strains as microsymbionts for phytoremediation of, and cereal cultivation on, selenium-contaminated soils. The ability of azospirilla to synthesize selenium nanoparticles may be of interest for nanobiotechnology.     

Biosynthesis of silver nanoparticles with the participation of extracellular Mn-dependent peroxidase from <Emphasis Type="Italic">Azospirillum</Emphasis>

The accumulation of nanoparticles of colloidal silver with spherical shape in culture liquid of Azospirillum brasilense has been shown by transmission electron microscopy. Bacterial extracellular Mn-peroxidases were found to participate in silver reduction from silver nitrate with the formation of nanoparticles. A mechanism of extracellular biosynthesis of silver nanoparticles by A. brasilense bacteria was proposed.     

Expression of plant antimicrobial peptide <Emphasis Type="Italic">pro-SmAMP2</Emphasis> gene increases resistance of transgenic potato plants to <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Fusarium</Emphasis> pathogens

The chickweed (Stellaria media L.) pro-SmAMP2 gene encodes the hevein-like peptides that have in vitro antimicrobial activity against certain harmful microorganisms. These peptides play an important role in protecting the chickweed plants from infection, and the pro-SmAMP2 gene was previously used to protect transgenic tobacco and Arabidopsis plants from phytopathogens. In this study, the pro-SmAMP2 gene under control of viral CaMV35S promoter or under control of its own pro-SmAMP2 promoter was transformed into cultivated potato plants of two cultivars, differing in the resistance to Alternaria: Yubiley Zhukova (resistant) and Skoroplodny (susceptible). With the help of quantitative real-time PCR, it was demonstrated that transgenic potato plants expressed the pro-SmAMP2 gene under control of both promoters at the level comparable to or exceeding the level of the potato actin gene. Assessment of the immune status of the transformants demonstrated that expression of antimicrobial peptide pro-SmAMP2 gene was able to increase the resistance to a complex of Alternaria sp. and Fusarium sp. phytopathogens only in potato plants of the Yubiley Zhukova cultivar. The possible role of the pro-SmAMP2 products in protecting potatoes from Alternaria sp. and Fusarium sp. is discussed.     

Structural and functional analysis of new plant promoter pro-SmAMP1 from <Emphasis Type="Italic">Stellaria media</Emphasis>

The nucleotide sequence of a fragment of the promoter region of pro-SmAMP1 gene, having a length of 1257 bp and encoding antifungal peptides, was determined in chickweed (Stellaria media (L.) Vill.). Computer analysis of the nucleotide sequence revealed a number of cis-elements that are typical strong plant promoters. Five 5′-deletion variants were created taking into account the distribution of cis-elements:–1235,–771,–714,–603, and–481 bp of pro-SmAMP1 gene promoter, which were fused to the coding region of the uidA reporter gene in pCambia1381Z plant expression vector. The efficacy of pro-SmAMP1 promoter deletion variants was determined by transient expression in plants of Nicotiana benthamiana and using sequential generations of transgenic Nicotiana tabacum plants. It was found that the levels of GUS reporter protein activity in the extracts from transgenic and agroinfiltrated plants using all deletion variants of pro-SmAMP1 gene promoter were 3–5 times higher than those of 35S CaMV viral promoter. The highest activity of GUS protein was observed in the leaves of transgenic tobacco plants and closely correlated with the mRNA level of encoding gene. The levels of GUS activity did not differ significantly among 11 independent homozygous lines of T₂ generation of N. tabacum plants with different deletion variants of pro-SmAMP1 promoter. The results give reason to assume that all deletion variants of pro-SmAMP1 promoter provide stable and high level of expression of controlled genes. The shortest deletion variant–481 bp of pro-SmAMP1 promoter should be viewed as a potentially strong plant promoter for the genetic engineering of plants.     

Protocol of a prospective study on the diagnostic value of transcranial duplex scanning of the substantia nigra in patients with parkinsonian symptoms

Background  

Parkinson's disease (PD) is the second most common neurodegenerative disorder. As there is no definitive diagnostic test, its diagnosis is based on clinical criteria. Recently transcranial duplex scanning (TCD) of the substantia nigra in the brainstem has been proposed as an instrument to diagnose PD. We and others have found that TCD scanning of substantia nigra duplex is a relatively accurate diagnostic instrument in patients with parkinsonian symptoms. However, all studies on TCD so far have involved well-defined, later-stage PD patients, which will obviously lead to an overestimate of the diagnostic accuracy of TCD.     

Phenol oxidase activity in bacteria of the genus <Emphasis Type="Italic">Azospirillum</Emphasis>

Phenol oxidase activity was detected for the first time in a number of strains belonging to various Azospirillum species. Both extracellular and intracellular activities of laccase, Mn-peroxidase, lignin peroxidase, and tyrosinase were observed. Extracellular enzymes were found to have higher activity. Significant differences in phenol oxidase activities were observed between species and strains.     

Enzymes of the xylotrophic basidiomycete Lentinus edodes F-249 in the course of morphogenesis

It has been shown that the fungus Lentinus edodes grown on a solid wort agar substrate produces intracellular enzymes, including Mn-dependent peroxidase, laccase, and tyrosinase as a family of isoforms. The composition of the complex (containing one to four forms of each enzyme) varied during the basidiomycete life cycle. The activity of oxidases was maximal at the stage of nonpigmented mycelium and at the stages of a brown mycelial mat and a fruit body. The activity of tyrosinase increased in the course of mycelium pigmentation and had two maxima: at the stage of a brown mycelial mat and at the stage of a fruit body. Laccase and tyrosinase activities were shown to increase sharply upon addition of oak sawdust extract to the culture medium as compared with the enzyme activities of mycelium grown on wort agar alone. It was established that the effect of phenol oxidase substrates on the growing mycelium consists in a twofold acceleration of the process of morphogenesis in the fungus L. edodes.