[Phylogenetic analysis of partial nucleotide sequences of 18S rRNA for 14 plant species]. / Filogeneticheskii analiz chastichnykh nukleotidnykh posledovatel'- nostei 18S rRNK 14 vidov rastenii.

The variable 260 base long region from the interior of 18S rRNA of 14 plant species was determined by chain termination method with the use of reverse transcriptase. The hairpin revealed in this region appeared to be conservative in all species compared. Thermodynamic stability of such hairpin is lower than of an alternative structure with different base pairing mode. From sequence data dendrograms were produced by clustering algorithms and by the compatibility method. In addition to the plant sequences these dendrograms included also the homologous regions from yeast and Xenopus 18S rRNAs. The compatibility method seems to be more reliable. Inferences were drawn on relations between gymnosperms and angiosperms, monocots and dicots on the bases of the analysis of this tree.

[Development of a PCR-based method for diagnostics of mycoses]. / Razrabotka i aprobatsiia sistem PTSR-detektsii dlia vyiavleniia invasivnykh mikozov.

Since the express-diagnostics of mycoses in immune-deficit patients still remains an acute problem, we developed an effective test system (Kan-Am) to detect DNA Candida albicans, which is a leader in the list of causative agents of candidosis. A comparison study of three PCR-systems used to detect a broad spectrum of fungoid pathogens was carried out, and a universal system (FungAm), which ensures the detection of DNAs of above 78 strains of 25 types of pathogenic fungi, was selected. The results of clinical testing of the species-specific and universal PCR-systems are well confirmed by the culture method, and they are indicative of the efficacy of applying them for the diagnostics of mycoses in neonatology. The use of the mentioned systems is a promising factor for the express-diagnostics of mycoses in immunodeficiency patients. The high sensitivity of the method makes it possible to detect 10 to 100 cells of a causative agent in 100 mcl of the examined biological material, which is compatible with the culture method. A kit of dry reagents (IonoMix) designed for an accelerated sample preparation and isolation, from them, of DNAs on the basis of Chelex-100 and of proteinase K was worked out; the kit is portable and meant for a long-term storing.

Angiosperm origin and early stages of seed plant evolution deduced from rRNA sequence comparisons.

Complete or partial nucleotide sequences of five different rRNA species, coded by nuclear (18S, 5.8S, and 5S) or chloroplast genomes (5S, 4.5S) from a number of seed plants were determined. Based on the sequence data, the phylogenetic dendrograms were built by two methods, maximum parsimony and compatibility. The topologies of the trees for different rRNA species are not fully congruent, but they share some common features. It may be concluded that both gymnosperms and angiosperms are monophyletic groups. The data obtained suggest that the divergence of all the main groups of extant gymnosperms occurred after the branching off of the angiosperm lineage. As the time of divergence of at least some of these gymnosperm taxa is traceable back to the early Carboniferous, it may be concluded that the genealogical splitting of gymnosperm and angiosperm lineages occurred before this event, at least 360 million years ago, i.e., much earlier than the first angiosperm fossils were dated. Ancestral forms of angiosperms ought to be searched for among Progymnospermopsida. Genealogical relationships among gymnosperm taxa cannot be deduced unambiguously on the basis of rRNA data. The only inference may be that the taxon Gnetopsida is an artificial one, and Gnetum and Ephedra belong to quite different lineages of gymnosperms. As to the phylogenetic position of the two Angiospermae classes, extant monocotyledons seem to be a paraphyletic group located near the root of the angiosperm branch; it emerged at the earliest stages of angiosperm evolution. We may conclude that either monocotyledonous characters arose independently more than once in different groups of ancient Magnoliales or that monocotyledonous forms rather than dicotyledonous Magnoliales were the earliest angiosperms. Judging by the rRNA trees, Magnoliales are the most ancient group among dicotyledons. The most ancient lineage among monocotyledons leads to modern Liliaceae.