Topography of digestive enzymes in small intestine and activity of corresponding hydrolases in liver and kidney of adult pigs

Distribution of activities of disaccharidases (saccharase, maltase), amino- and dipeptidases, dipeptidyl peptidase IV (DPP) and alkaline phosphatase along the small intestine and of these hydrolases in liver and kidney, as well as distribution of the digestive enzyme activities between the membrane and cytosol fractions of enterocytes is characterized in adult 6-month old pigs. It has been shown that maximum of the studied enzyme activities, except for DPP, takes place in ileum. A higher level of the activities of the soluble form of saccharase, maltase, and aminopeptidase M and a less significant level of the activity of the glycyl-L-leucine dipeptidase soluble form in jejunum and ileum is found than those in rats and monkeys. The obtained data demonstrate the existence of the complex enzyme system in small intestine, liver, and kidney that participate in realization of nutritive and trophic-barrier functions.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 1, 2005, pp. 39–43.Original Russian Text Copyright © 2005 by Smirnova, Gordova, Timofeeva, Shcherbakov.     

Role of 5-aminolevulinic acid in the formation of winter rape resistance to sulfonylurea herbicides

Growing of winter rape (Brassica napus L.) plants for 7–8 days in the presence of a sulfonylurea herbicide Magnum (methsulfuron methyl; 200 and 500 mg/L) exerted an organ-specific influence on the seedlings: suppressed hypocotyl and root growth and increased the accumulation of fresh weight of cotyledonary leaves. Exogenous 5-aminolevulinic acid (ALA; 0.1, 1.0, and 10 mg/L) partially negated the adverse effect of Magnum on the length and fresh weight of roots and hypocotyls and stimulated the development of cotyledons. The herbicide suppressed the activity of ascorbate peroxidase (APX). The addition of ALA to the 200 mg/L herbicide solution caused a steady activation of APX as compared with the effect of herbicide alone. In plants grown on Magnum solutions, the activity of glutathione reductase (GR) rose. Positive effect of exogenous ALA was only observed when 500 mg/L herbicide was used (Magnum-500 type of treatment). In plants grown on the Magnum solution, the content of reduced and oxidized forms of glutathione rose. In contrasty, exogenous ALA reduced the total content of glutathione but in this case the ratio between its reduced and oxidized forms rose. In the presence of the herbicide, the content of anthocyans considerably decreased and upon the addition of exogenous ALA their levels rose. In rape plants treated with Magnum, the ability to generate superoxide anion radical was essentially the same as in control plants; however, the content of hydrogen peroxide (H₂O₂) therein rose. The addition of ALA to the herbicide reduced the ability to generate superoxide anion radical and the level of H₂O₂. The activity of acetolactate synthase remained on the control level when 200 mg/L Magnum was used, decreased in the plants of Magnum-500 treatment, and rose upon the addition of exogenous ALA to this type of treatment. It was concluded that ALA had a positive effect on the development of winter rape resistance to Magnum via stimulation of growth processes, activation of APX and GR, predominant elevation of the content of reduced glutathione and anthocyans, and partial recovery of acetolactate synthase activity, which on the whole caused a decrease in the H₂O₂ level and in the ability of plants to generate superoxide anion radical.     

Directed mutagenesis of Mycobacterium smegmatis 16S rRNA to reconstruct the in vivo evolution of aminoglycoside resistance in Mycobacterium tuberculosis

Drug resistance in Mycobacterium tuberculosis is a global problem, with major consequences for treatment and public health systems. As the emergence and spread of drug‐resistant tuberculosis epidemics is largely influenced by the impact of the resistance mechanism on bacterial fitness, we wished to investigate whether compensatory evolution occurs in drug‐resistant clinical isolates of M. tuberculosis. By combining information from molecular epidemiology studies of drug‐resistant clinical M. tuberculosis isolates with genetic reconstructions and measurements of aminoglycoside susceptibility and fitness in Mycobacterium smegmatis, we have reconstructed a plausible pathway for how aminoglycoside resistance develops in clinical isolates of M. tuberculosis. Thus, we show by reconstruction experiments that base changes in the highly conserved A‐site of 16S rRNA that: (i) cause aminoglycoside resistance, (ii) confer a high fitness cost and (iii) destabilize a stem‐loop structure, are associated with a particular compensatory point mutation that restores rRNA secondary structure and bacterial fitness, while maintaining to a large extent the drug‐resistant phenotype. The same types of resistance and associated mutations can be found in M. tuberculosis in clinical isolates, suggesting that compensatory evolution contributes to the spread of drug‐resistant tuberculosis disease.     

Combined pre-seed treatment with microbial inoculants and Mo nanoparticles changes composition of root exudates and rhizosphere microbiome structure of chickpea (<Emphasis Type="Italic">Cicer arietinum L.</Emphasis>) plants

Lichenicolous (lichen-dwelling) fungi have been extensively researched taxonomically over many years, and phylogenetically in recent years, but the biology of the relationship between the invading fungus and the lichen host has received limited attention, as has the effects on the chemistry of the host, being difficult to examine in situ. Raman spectroscopy is an established method for the characterization of chemicals in situ, and this technique is applied to a lichenicolous fungus here for the first time. Xanthoriicola physciae occurs in the apothecia of Xanthoria parietina, producing conidia at the hymenium surface. Raman spectroscopy of apothecial sections revealed that parietin and carotenoids were destroyed in infected apothecia. Those compounds protect healthy tissues of the lichen from extreme insolation and their removal may contribute to the deterioration of the apothecia. Scytonemin was also detected, but was most probably derived from associated cyanobacteria. This work shows that Raman spectroscopy has potential for investigating changes in the chemistry of a lichen by an invading lichenicolous fungus.     

Biodamage on Phylladoderma leaves from the Upper Permian of the Pechora Basin

A new insect damage type on leaves Phylladoderma arberi Zalessky, 1913 from the Upper Permian of the Pechora Basin (Adz’va River, Russia) is described. These are punctures about 120 μm in diameter surrounded by circular spots with a dark rim. We suppose that these feeding traces were made by palaeodictyopteroid nymphs.     

Development of Search Strategy for Peptide Inhibitors of Immune Checkpoints

Current strategy for the blockade of molecules inhibiting T-cell immunity, the immune checkpoints (ICP), such as CTLA-4, PD-1, and B7-H1(PD-L1), using monoclonal antibodies (mAbs), showed significant clinical effects in cancer immunotherapy. In this kind of therapy, antibodies do not kill tumor cells directly, but block inhibitory signals for T lymphocytes, resulting in activation of the immune response cascade that eliminate malignant cells and lead to tumor degradation. However, the mAb preparations have some limitations, and the development of new low-molecular-weight antagonists (for example, peptides) is an important issue. In this study, we used peptide microarrays and phage display libraries to search for peptides that interact with the immune checkpoints. We found peptides that specifically bind CTLA-4, PD-1, B7-1, B7-2 and B7-H1(PD-L1) which play important role in the regulation of the immune responses. These synthetic peptides can be applied to the development of new immunomodulating drugs for cancer immunotherapy.     

Membrane mechanics can account for fusion pore dilation in stages.

Once formed, fusion pores rapidly enlarge to semi-stable conductance values. The membranes lining the fusion pore are continuous bilayer structures, so variations of conductance in time reflect bending and stretching of membranes. We therefore modeled the evolution of fusion pores using the theory of the mechanics of deforming homogeneous membranes. We calculated the changes in length and width of theoretical fusion pores according to standard dynamical equations of motion. Theoretical fusion pores quickly achieve semi-stable dimensions, which correspond to energy minima located in a canyon between energy barriers. The height of the barrier preventing pore expansion diminishes along the dimensions of length and width. The bottom of the canyon slopes gently downward along increasing length. As a consequence, theoretical fusion pores slowly lengthen and widen as the dimensions migrate along the bottom of the canyon, until the barrier vanishes and the pore rapidly enlarges. The dynamics of growth is sensitive to tension, spontaneous curvature, bending elasticity, and mobilities. This sensitivity can account for the quantitative differences in pore evolution observed in two experimental systems: HA-expressing cells fusing to planar bilayer membranes and beige mouse mast cell degranulation. We conclude that the mechanics of membranes could cause the phenomenon of stagewise growth of fusion pores.     

Elastic stability of chains of magnetosomes in magnetotactic bacteria

Electron micrographs of magnetotactic bacteria reveal that chains of magnetosomes are often bent. This is surprising inasmuch as straight chains are actually the most favourable arrangement for magnetonavigation achieving the maximum value of the bacterial net magnetic moment. In order to answer the question of what causes the chains to bend, we calculated the stability limit of straight magnetosome chains by taking into account elastic and magnetic forces. For several scenarios, the threshold values of external forces leading to elastic instability were computed. From our calculations and observations on freeze-dried cells, we conclude that, under normal conditions, magnetosome chains are straight or only slightly bent, whereas shrinkage during preparation may cause severe artifacts such as kinks or zig-zag structures in the chains. Received: 10 February 1997 / Accepted: 9 April 1997     

Outer membranes of a lipopolysaccharide-protein complex (LPS-17 kDa protein) as chemical tularemia vaccines

Abstract Immunisation with outer membranes of Francisella tularensis induced an efficient protection in guinea pigs against challenge with the virulent strains 503 or 144/713 (type B biovar holarctica ), both clinical isolates, and prevented the development of typical signs of infection in hamadryads (baboons), challenged with the virulent strain Schu (type A, biovar tularensis ) of F. tularensis . Immunisation with a lipopolysaccharide protein complex isolated from the outer membranes afforded protection in CBA mice against challenge with strain 503. Another LPS-protein complex obtained by the simple mixture of LPS preparations from strain 503 and a 17-kDa membrane protein from the avirulent R-variant of the vaccine strain 15 also demonstrated protective properties against experimental tularemia in mice.