Capsule formation in the causative agent of glanders

Electron-microscopic and electron-cytochemical method were used to indicate the capability of Pseudomonas mallei (str. N 10230) to produce extracellular slime during the agent growth on the meat-peptone agar. In case of guinea pigs infection the agent forms a capsule that defends the pathogen from phagocytosis.     

<Emphasis Type="Italic">Artemisia lerchiana</Emphasis> as a producer of essential oil

Abstrac  The composition of essential oil of Artemisia lerchiana Web. plants growing in Volgograd oblast was studied. Sampling was performed from plots contrasting in climatic and soil characteristics. Essential oil was obtained by hydrodistillation. The content of essential oil in shoot biomass increased gradually during shoot formation, flower bud formation, and flowering beginning and then decreased. The highest content of essential oil varied from 1.1 to 1.5% of plant dry weight at the stage of flower bud formation. More than thirty compounds were identified by gas chromatography-mass spectrometry. The following major components were found: camphor, borneol, bornylacetate, camphene, and 1,8-cineole. Some of compounds (sesquiterpenes and sesquiterpenoids) were identified for the first time. The time-course of accumulation of essential oil components strongly depended on habitat edaphic factors and climatic conditions during the year of sampling. The results permit a conclusion that A. lerchiana is a valuable producer of essential oils. Original Russian Text ? E.B. Kirichenko, Yu.V. Orlova, D.V. Kurilov, 2008, published in Fiziologiya Rastenii, 2008, Vol. 55, No. 6, pp. 934–941.     

Study of structure-activity relationship among similar analogues of GSB-106, a dipeptide mimetic of a brain-derived neurotrophic factor

In the previous work, we synthesized a dimeric dipeptide mimetic of the 4th loop of BDNF, i.e., hexamethylenediamide bis(N-monosuccinil-L-seryl-L-lysine) (GSB-106), which has neuroprotective activity in vitro in a concentration range of 10^?5–10^?8 M and antidepressant activity in vivo at intraperitoneal doses of 0.1 and 1 mg/kg in rats. We studied the structural and functional relationships among analogues of GSB-106. A glycine scan was performed, and a number of corresponding compounds were synthesized: GT-105 (where lysine was replaced by glycine), GT-107 (where serine was replaced by glycine), and GT-106Ac (where the monosuccinic radical was replaced by the acetyl group). We studied the dependence of the activity on the configuration of amino acid residues in the following compounds: GT-107D (D-enantiomer of GT-107), GT-106DL (L-serine was replaced by D-serine), GT-106LD (L-lysine was replaced by D-lysine). The investigation of these compounds in the HT22 cell culture in conditions of oxidative stress showed that only two analogues of GSB-106 had the neuroprotective effect, i.e., in the case of the replacement of serine by glycine and the succinic radical by the acetic group. This effect disappeared when the lysine residue was replaced by glycine or D-lysine and the L-serine residue, by D-serine. The results indicate the key role of the lysine side group in GSB-106 for its neuroprotective activity. The L-configuration is necessary for both the lysine and serine residues. The configuration of the lysine residue remains critical in the absence of the serine side group. Thus, the minimum neuroprotective pharmacophore of the beta-turn of the 4th loop of BDNF is the following fragment: HOOC-CH₂-CH₂-CO-NH-(S)CH(CH2OH)-CO-NH-(S)CH((CH₂)₄NH₂)-CO-NH-(CH₂)₃ Only GT-106Ac out of two analogues of GSB-106 having the neuroprotective activity showed the antidepressant activity. This indicates more stringent structural requirements for the manifestation of the antidepressant activity. The results can be useful for designing new active mimetics of BDNF.     

Immunoenzyme analysis of antigen-specific determination of HBsAG-containing circulating immune complexes (CIC HBsAG/IgM and CIC HBsAG/IgG) in blood serum of patients with HBV-infection]

A complex enzyme immunoassay (ELISA) has been designed for antigen-specific determination of HBsAg-containing circulating immune complexes (CIC HBsAg/IgM and CIC HBsAg/IgG) in human blood sera in parallel with registration of free HBsAg and specific antibodies to viruses of hepatitis A, B and D. It is shown that effective formation of HBsAg-containing CIC serologically is registered predominantly as a mutually incompatible marker with detection of free HBsAg (in 70-85% of the cases). CIC HBsAg/IgM and CIC HBsAg/IgG may be registered both in parallel and as mutually exclusive markers. Effective formation of HBsAg-containing CIC in the presence of anti-HBsAg occurs in case of a mild course of viral hepatitis of epidemic and sporadic type, while in severe forms of VH-free HBsAg is predominantly detected thus pointing either to ineffective formation of HBsAg-containing CIC or to their continuous registration with demonstration of the effect of delay of witching of anti-HBsM over to anti-HBsG (or CIC HBsAg/IgM to CIC HBsAg/IgG). It was also found that in case of epidemic VH in Tajik SSR (1987) serologically marked as VH both A and B convalescent phase was characterized by parallel disappearance (or lowering of the titer levels) of HBsAg-containing CIC and class M antibodies to both hepatitis A (anti-HAV M) and B (anti-HBcM, anti-HBsM) along with the containing parallel registration of relevant G-antibodies (anti-HAV G/anti-HBcG). This observation requires further studies both in terms of close association of viruses of hepatitides A and B and with regards to possible antigenic mimicry.     

Study of electron-dense thylakoids in chloroplasts of Stevia rebaudiana Bertoni in relation to the biosynthesis of diterpenoids

Using transmission electronic microscopy and mass spectrometry electron-dense thylakoids of chloroplasts of Stevia rebaudiana leaves during active vegetable growth of this plant were studied in relation to the biosynthesis of diterpenoid glycosides (DGs). It was found that these compounds are absent in these thylakoids, but they contain a water-insoluble weakly polar ent-kauren, a known biosynthetic precursor of DGs as well as gibberellins. This finding provides a base for the suggestion that similar, electron-dense, thylakoids were observed earlier by other authors in other plant species. These data allowed us to conclude that an intensive biosynthesis of ent-kauren is likely related to adaptation of the short-day plants including Stevia rebaudiana to vegetable growth under the long day conditions.     

New Plant Growth Stimulants Based on Water-Soluble Nanoparticles of N-Substituted Monoamino-Acid Derivatives of Fullerene C60 and the Study of their Mechanisms of Action

Growth-stimulating effects of water-soluble nanoparticles of N-substituted monoamino-acid derivatives of fullerene C₆₀ (L- and D-alanine, L- and D-valine, L- and D-aspartic acid, β-alanine, and γ-aminobutyric and ε-aminocaproic acids in potassium salt form) were investigated. It was found that the nanoparticle size and relative antiradical activity of fullerene derivatives were factors that influence such physiological parameters of field peas as seed germination rate, germination energy, and root growth capacity. It was shown that the relative antiradical activity of nanoparticles in the selected group of compounds was determined by the total surface area of the nanoparticles regardless of the structure of the amino-acid substituent. The possibility of using amino-acid derivatives of fullerene as effective growth stimulating substances has been demonstrated. A dose-dependent effect of N-(monohydrofullerenyl)-D-alanine potassium salt in a concentration range of 10^–9–10^–11 M on the seed-germination rate and germination energy of field peas has been demonstrated.

     

Immunobiological properties of Burkholderia pseudomallei and Burkholderia mallei capsular substances

The biopolymer composition, immunotropic and immunogenic properties of the fractions of B. pseudomallei and B. mallei were under study. The first two capsular fractions of these agents were found to be similar in their biopolymer composition that was indicative of their close relations. At the same time the causative agents of glanders proved to have decreased content of high molecular glycoproteids and LPS fragments. In the causative agents of melioidosis, capsular fractions K3 and K4 were characterized by the domination of proteins with a molecular weight of 42-25 kD. Fraction K4 in B. pseudomallei and fraction K1 in B. mallei had pronounced immunosuppressing properties ensuring the protection of encapsulated microbial cells in the body. The biopolymers forming fractions K1, K2, K3 in B. pseudomallei and fraction K2 in B. mallei were characterized by immunomodulating properties.     

A mathematical model of the response of semicircular canal and otolith to head rotation under gravity

The mathematical model of the system composed of two sensors: semicircular canal and sacculus, is presented. The system is described by three series of blocks: biomechanical block, mechanoelectrical transduction mechanism and hair cell ionic currents and membrane potential dynamics. The response of the aforecited system to various stimuli (head rotation under gravity and falling) was investigated. The identification of the model parameters was fulfilled for the experimental data, obtained for the axolotle (Ambystoma tigrinum) in Institute of Physiology, Autonomous University of Puebla, Mexico. The comparative analysis of canal and sacculus membrane potential was realized.     

The role of capsule formation in Burkholderia mallei for its persistence in vivo

When studied in vivo (in guinea pigs) with the use of electron microscopy, B. mallei (strains C-5, 10230) were found to form a capsule. In the subacute course of infection, the encapsulated forms of B. mallei parasitized mainly in the cells of the system of mononuclear phagocytes in the liver, the spleen and the lungs. The capsule formed by B. mallei was shown to be one of the factors facilitating its persistence in the body.