Heterologous expression of the lndYR and wblA gh genes in Streptomyces nogalater LV65, S. echinatus DSM40730, and S. peucetius subsp. Caesius ATCC27952 (producers of anthracycline antibiotics)

Strains of the actinomycetes Streptomyces nogalater Lv65, S. echinatus DSM40730, and S. peucetius subsp. caesius ATCC27952 are producers of the anthracycline antibiotics nogalamycin, aranciamycin, and doxorubicin, respectively. This work was focused on the impact produced by the expression of the regulatory lndYR and wblA _gh genes on the secondary metabolism and morphogenesis of these bacteria. Introducing regulators into the composition of replicative plasmids in the streptomycetes in question leads to a decrease in the synthesis of anthracyclines, whereas the expression of lndYR in cells of S. peucetius subsp. caesius ATCC27952 suppresses the sporulation of the doxorubicin producer which may indicate the presence of their homologues in the genomes. The identification of these genes for the purpose of their further directed inactivation may be a successful tool for obtaining strains with an increased level of synthesis of clinically important compounds, as well as it can allow us to establish particular stages in the regulation of the secondary metabolism of anthracycline antibiotics.     

Molecular phylogeny of a green microalga isolated from White Sea sponge <Emphasis Type="Italic">Halichondria panicea</Emphasis> (Pallas, 1766)

Molecular identification of eukaryotic microalga 1Hp86E-2 isolated from White Sea sponge Halichondria panicea (Pallas, 1766) was conducted, and phylogenetic analysis was carried out using the nucleotide sequence of 18S rRNA gene (GenBank, no. JX437624). Isolated microalga was classified to the genus Desmodesmus. Microalga 1Hp86E-2 proved to be closely related to the algae Desmodesmus sp. 3Dp86E-1, Desmodesmus sp. 2C166E, and Desmodesmus sp. 1Pm66B isolated from White Sea invertebrates. Phylogenetic analysis showed that these closely related organisms belong to a monophyletic group.     

Pleiotropic regulatory genes bldA,adpA and absB are implicated in production of phosphoglycolipid antibiotic moenomycin

Unlike the majority of actinomycete secondary metabolic pathways, the biosynthesis of peptidoglycan glycosyltransferase inhibitor moenomycin in Streptomyces ghanaensis does not involve any cluster-situated regulators (CSRs). This raises questions about the regulatory signals that initiate and sustain moenomycin production. We now show that three pleiotropic regulatory genes for Streptomyces morphogenesis and antibiotic production—bldA, adpA and absB—exert multi-layered control over moenomycin biosynthesis in native and heterologous producers. The bldA gene for tRNA^Leu_UAA is required for the translation of rare UUA codons within two key moenomycin biosynthetic genes (moe), moeO5 and moeE5. It also indirectly influences moenomycin production by controlling the translation of the UUA-containing adpA and, probably, other as-yet-unknown repressor gene(s). AdpA binds key moe promoters and activates them. Furthermore, AdpA interacts with the bldA promoter, thus impacting translation of bldA-dependent mRNAs—that of adpA and several moe genes. Both adpA expression and moenomycin production are increased in an absB-deficient background, most probably because AbsB normally limits adpA mRNA abundance through ribonucleolytic cleavage. Our work highlights an underappreciated strategy for secondary metabolism regulation, in which the interaction between structural genes and pleiotropic regulators is not mediated by CSRs. This strategy might be relevant for a growing number of CSR-free gene clusters unearthed during actinomycete genome mining.     

Responses of crayfish neurons and glial cells to photodynamic impact: Intracellular signaling,ultrastructural changes,and neuroglial interactions

Photodynamic therapy (PDT), an inducer of oxidative stress, is used for treatment of cancer, including brain tumors. To study the mechanisms of photodynamic injury of neurons and glial cells (GC), we used a simple model object — isolated crayfish mechanoreceptor consisting of a single sensory neuron surrounded by a multilayered glial envelope. PDT caused inhibition and elimination of neuronal activity, impairment of intracellular organelles involved in the biosynthetic, bioenergetic, and transport processes and neuroglial interactions, necrosis of neurons and glial cells, and in glial apoptosis. PDT-induced death of a neuron and GC was mediated by intercellular molecular messengers and intracellular signaling cascades. PDT-induced inhibition and elimination of neuronal activity was associated with opening of mitochondrial permeability transition pores, Ca²⁺ release into cytosol, protein kinase C and NO synthase activities. Necrosis of neurons was mediated by protein kinases B/Akt, GSK-3β and mTOR, opening of mitochondrial permeability transition pores and Ca²⁺/calmodulin/CaMKII pathway. NO and GDNF reduced neuronal necrosis. Multiple signal pathways, such as phospholipase C/Ca²⁺, Ca²⁺/calmodulin/CaMKII, Ca²⁺/PKC, Akt/mTOR, MEK/p38, and protein kinase G mediated PDT-induced necrosis both in glial cells and in neurons. NOS/NO and neurotrophic factors NGF and GDNF protected glial cells and demonstrated antinecrotic activity. Glial apoptosis was reduced by neurotrophic factors NGF and GDNF, protein kinase C, and MAP kinase JNK. In contrast, mitochondrial permeability transition pores and phospholipase C, which mobilize intracellular Ca²⁺, NOS/NO/protein kinase G, proteins GSK-3β and mTOR, stimulated apoptosis of glial cells. The schemes of involvement of various inter- and intracellular signaling processes in the responses of neurons and GC to PDT are developed.     

Coordination of export and glycosylation of landomycins in Streptomyces cyanogenus S136

In Streptomyces cyanogenus S136 gene cluster for biosynthesis of polyglycosylated angucycline landomycin A (LaA), a divergently oriented gene pair for a TetR-family regulator ( lanK ) and an efflux protein ( lanJ ) is located, whose functions remained obscure. Overexpression and disruption studies showed that lanK and lanJ genes control LaA resistance. Also, a constitutive lanK overexpression led to predominant accumulation of LaA precursors bearing shorter glycoside chains. These data as well as the results of in vitro and in vivo assays of LanK activity are consistent with the idea that LanK represses lanJ and some downstream genes involved in conversion of landomycin D (a disaccharide LaA precursor) into LaA. LaA and some of its precursors accumulate in the producing cell and relieve repression by LanK, thus amplifying the biosynthesis and export of landomycins with long glycoside chains. Therefore, the main biological role of LanK appears to be the inhibition of premature extrusion of early LaA precursors from the cells, which in turn creates the optimal conditions for accumulation of LaA as the major landomycin in S. cyanogenus S136.     

First records of hindwings of Permian beetles (Coleoptera)

Three isolated hindwings of beetles are described from the locality of Isady, late Middle Permian of northern European Russia. The wings share all main features characteristic of beetles and combine plesiomorphic and apomorphic states of characters found in different suborders. The wings most probably belonged to beetles of the families Asiocoleidae and/or Taldycupedidae.     

A contribution to the morphological study of acute changes in the blood vessels of the central nervous system of rats following irradiation with high-energy (4 GeV/nucleon) helium ions

Rats were irradiated with helium ions (4 GeV/nucleon; 2 or 4 Gy). After 4-9 hours or three days, a perfusion was performed and sections of the cerebral cortex were investigated under light and electron microscopes. Changes observed in the vessels of the telencephalic cortex are described. Most of the vessels in the sections analysed showed no signs of damage. In some cases there was a dilated perivascular space; a comparison of its occurrence in irradiated and control animals showed a statistically significant increase in frequency of the phenomenon at a shorter interval after irradiation with a larger dose. Electron microscopical analysis showed that the main locality of damage was the border of the perivascular foot of the astrocytes, which exhibited various degrees of edema. The discussion stresses the peculiarities of the interaction of helium ions with living tissues, particularly the heterogeneity of the distribution of absorbed energy. The consequence is in accordance with the nature of the changes observed.     

Chemical and serological studies of liposaccharides of bacteria of the genus Azospirillum

The analysis of the lipopolysaccharides (LPS) of nine strains of azospirilla revealed the presence of the characteristic components of these glycopolymers: carbohydrates, hydroxylated fatty acids, and 2-keto-3-deoxyoctonic acid (KDO). SDS electrophoresis revealed the heterogeneous nature and the strains differences in the ratio of the molecular S and R forms present in the LPS. Polyclonal rabbit antibodies (Ab) were obtained against the isolated LPS(Cd), LPS(Sp59b), LPS(Sp7), LPS(S17), and LPS(KBC1) preparations. Based on the results of the serological studies of the LPS, the bacterial strains investigated in the work were divided into two main serogroups. Based on the immunoblotting data, Ab(Sp59b) and Ab(Cd) were found to be formed in response to both the S and R forms of the LPS molecules, whereas all the rest formed in response to the S forms only. It was shown that the heterogeneity of the antigenic determinants is typical of the second LPS group. It was suggested that rhamnose plays one of the key roles in the specific interactions between the azospirillum membrane LPS and Ab.