Colonization strategy of the endophytic plant growth-promoting strains of Pseudomonas fluorescens and Klebsiella oxytoca on the seeds, seedlings and roots of the epiphytic orchid, Dendrobium nobile Lindl.

AIMS: Orchids form strong mycorrhizal associations, but their interactions with bacteria are poorly understood. We aimed to investigate the distribution of plant growth promoting rhizobacteria (PGPR) at different stages of orchid development and to study if there is any selective specificity in choosing PGPR partners. METHODS AND RESULTS: Colonization patterns of gfp-tagged Pseudomonas fluorescens and Klebsiella oxytoca were studied on roots, seeds, and seedlings of Dendrobium nobile. Endophytic rhizobacteria rapidly colonized velamen and core parenchyma entering through exodermis and the passage cells, whereas at the early stages, they stayed restricted to the surface and the outer layers of the protocorms and rhizoids. The highest amounts of auxin (indole-3-acetic acid) were produced by K. oxytoca and P. fluorescens in the nitrogen-limiting and NO3 -containing media respectively. Bacterization of D. nobile seeds resulted in promotion of their in vitro germination. The plant showed no selective specificity to the tested strains. Klebsiella oxytoca demonstrated more intense colonization activity and more efficient growth promoting impact under tryptophan supplementation, while P. fluorescens revealed its growth-promoting capacity without tryptophan. CONCLUSIONS: Both strategies are regarded as complementary, improving adaptive potentials of the orchid when different microbial populations colonize the plant. SIGNIFICANCE AND IMPACT OF THE STUDY: This study enlarges our knowledge on orchid-microbial interactions, and provides new features on application of the nonorchid PGPR in orchid seed germination and conservation.

[The Effects of Optokinetic Stimulation on Visual-Manual Tracking under Support-Proprioceptive Deprivation.]

To determine the effects of additional visual stimuli (retinal optokinetic stimulation - ROKS) on characteristics of the visual-manual tracking (VMT) without support and with decreased proprioceptive afferentation there was used a horizontal "dry" immersion. Altogether 18 subjects aged from 19 to 31 years participated in the study and they were submerged into the immersion bath from 5 to 7 days. There was evaluated performance of the VMT in tasks to pursue the jerky (saccadically) and smooth (linear, pendular and circular) movement of a point visual stimulus before, during and after immersion. Eye movements were recorded using electrooculography, hand movements - by ajoystick with a biological visual feedback (one of the two visible stimuli on the screen matched the current angle of thejoystick handle). Computerized visual stimulation programs were presented to subject using a virtual reality glasses with and without additional ROKS. We analyzed time, amplitude and velocity characteristics of the visual and manual tracking (VT and MT), including efficiency ratio (e) and gain (g) as ratios of respectively amplitudes and velocities of eyes/hand movements to the stimulus movement. Without ROKS efficiency ratio and gain of both VT and MT were significantly decreased in comparison with baseline during the whole immersion and up to the R + 3 day after. The most pronounced deterioration was observed in parameters of the VT. When using a "threshold" ROKS parameters of the VT and MT weren't changed before immersion, during and after immersion - they improved (on 1-5-7 days during immersion and on R + 3 day after there was a significant improvement of the VT and MT in comparison to same tests without ROKS). The greatest impact of the ROKS was observed in parameters of the VT. Evaluations of the vestibular function (VF) were performed before and after immersion using videooculography approach. We analyzed statical torsional otolith-cervical-ocular reflex (OCOR), dynamical vestibular-cervical-ocular reactions (VCOR) and vestibular reactivity (VR), spontaneous eye movements (SpEM). On R + 1 day after immersion in 28% of subjects there was found a significant decrease of the gain of OCOR (0.12 value in comparison to 0.25 baseline) with simultaneous significant increase of parameters of VCOR/VR. There was found a correlation between parameters of VT and MT, between VF and VT and no correlation between VF and MT. It was found that removal of the support and minimization of the proprioceptive afferentation has a greater impact-upon accuracy of the VT then accuracy of the MT. When using ROKS correlations between the studied parameters were not only preserved, but also intensified. The results obtained indicate the development of sensory deprivation (and afferent deficit) under the immersion exposure and the possibility of its correction with additional ROCKS.

[EFFECT OF REPEATED SPACE FLIGHTS ON OCULAR TRACKING].

The paper reports the results of studying the vestibular and ocular intersensory interactions and eye tracking function in 32 cosmonauts on maiden and repeated missions to the International space station. Mission duration ranged from 125 to 215 days. The cosmonauts were tested twice pre launch (baseline data collection) and on days R + 1/2, 4/5 and 8/9. Video oculography was used to test eye movements. It was found that in the majority of cosmonauts who had no experience of long-duration space missions the eye tracking function remained impaired significantly till R + 8/9. In cosmonauts who had already encountered with microgravity, obvious changes in eye tracking were observed on R + 1/2 only and, residual, on R + 4/5. On recovery, a new eye tracking strategy was acquired only by cosmonauts who had the first touch with spaceflight microgravity.

[VESTIBULAR FUNCTION AFTER REPEATED SPACE FLIGHTS].

Results of the vestibular function testing of 32 cosmonauts on return from repeated 125- to 215-day space flights (SF) on the International space station are presented. The cosmonauts were tested twice before flight (baseline data collection) and on days 1-2, 4-5 and 8-9 after landing. Electro- and video-oculography were used to register simultaneously eye and head movements. It was found that deadaptation following a repeated stay in long-duration SF takes statistically much shorter time. Most often, atypical vestibular disorders and changed patterns of the otolith-semicircular canal interaction are observed in cosmonauts who have made their maiden flights to microgravity.

Whole genome sequence data of Lactobacillus fermentum HFD1, the producer of antibacterial peptides.

Here we report the whole genome sequence of Lactobacillus fermentum HFD1 strain, the producer of antibacterial peptides. The genome consists of one circular chromosome with 2101878 bp in length and GC-content of 51.8%, and includes linear DNA with 5386 bp in length with 100% identity to bacteriophage phiX174. The analysis of the genome has revealed 2049 genes encoding for proteins including 867 proteins without known function and 70 genes encoding for RNAs (10 rRNAs, 59 tRNAs and 1 tmRNA). Putative genes responsible for the biosynthesis of 4 antimicrobial peptides were identified. The NCBI Bioproject has been deposited at NCBI under the accession number PRJNA615901 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA615901/) and consist of full annotated genome and raw sequence data.

[Direct site-specific cleavage of double-stranded DNA by conjugates of bleomycin A5 with triplex-forming oligonucleotide].

Monofunctional conjugates of 15-mer triplex-forming oligonucleotide (TFO) with covalently attached bleomycin A5 residue at the 5'-end (Blm-p15) were synthesized. Bifunctional conjugates of TFO containing, in addition to Blm, the residues of intercalator 6-chloro-2-methoxy-9-aminoacridine (Acr) or (N-(2-hydroxyethyl)phenazinium (Phn) were obtained for the first time. The Acr and Phn residues were attached to the 3'-phosphate group of TFO through L1 and L2 linkers, respectively, resulting in the compounds Blm-p15pL1-Acr and Blm-p15pL2-Phn. The values of dissociation constants of the corresponding triplexes were evaluated using the gel retardation method. The Acr residue in Blm-p15pL1-Acr was shown to enhance the stability of the formed triplex by one order of magnitude. It was demonstrated that all synthesized conjugates are capable of specifically and nonspecifically damaging a target DNA, forming direct breaks and alkaline-labile sites. The extent of the specific cleavage of the target DNA was 15% in the case of a fivefold excess of the conjugates over the DNA duplex. The site-specific triplex-mediated cleavage of a target DNA was shown for the first time to occur predominantly (> 90%) with the formation of the direct breaks of both DNA strands. The results show the availability of bleomycin-containing oligonucleotides as antigene compounds.