Expression and properties of human TNF peptide fragments

The tumor necrosis factor (TNF) is a proinflammatory cytokine that plays a pivotal role in the regulation of the human immune system. Studies of the TNF functional topography are a challenging task in bioengineering. We have produced genes encoding the peptides D1 (3–30), D2 (31–85), D3 (86–114), and D4 (115–157), which correspond to isolated fragments of the informational structure of TNF. These genes were expressed in E. coli cells at a high level in a soluble form. We have shown that hybrid proteins SD2 and SD4 tend to form high-molecular aggregates, which can be destroyed by urea treatment. Purified peptides D1, D3, and D4 possess a similar secondary structure with dominating beta-structural elements. The analysis of the biological activity of these peptides has shown that they do not exhibit cytotoxic properties on L929 murine fibroblasts. The simultaneous addition of D1 with full-length TNF results in the concentration dependent suppression of TNF activity.     

VENOM FROM THE ECTOPARASITIC WASP Habrobracon hebetor ACTIVATES CALCIUM‐DEPENDENT DEGRADATION OF Galleria mellonella LARVAL HEMOCYTES

Ectoparasitoids inject venom into hemolymph during oviposition. We determined the influence of envenomation by the parasitoid, Habrobracon hebetor, on the hemocytes of its larval host, Galleria mellonella. An increase in both intracellular Са²⁺ content and phospholipase C activity of the host hemocytes was recorded during 2 days following envenomation by the parasitoid. The decreased hemocyte viability was detected 1, 2, and 24 h after the envenomation. Injecting of the crude venom (final protein concentration 3 μg/ml) into the G. mellonella larvae led to the reduced hemocyte adhesion. The larval envenomation caused a decrease in transmembrane potential of the hemocytes. These findings document the suppression of hemocytic immune effectors in the parasitized host larvae.     

Predicted bacteriorhodopsin from Exiguobacterium sibiricum is a functional proton pump

The predicted Exigobacterium sibiricum bacterirhodopsin gene was amplified from an ancient Siberian permafrost sample. The protein bacteriorhodopsin from Exiguobacterium sibiricum (ESR) encoded by this gene was expressed in Escherichia coli membrane. ESR bound all-trans-retinal and displayed an absorbance maximum at 534 nm without dark adaptation. The ESR photocycle is characterized by fast formation of an M intermediate and the presence of a significant amount of an O intermediate. Proteoliposomes with ESR incorporated transport protons in an outward direction leading to medium acidification. Proton uptake at the cytoplasmic surface of these organelles precedes proton release and coincides with M decay/O rise of the ESR.     

Occurrence of neutral and alkaline cellulases among alkali-tolerant micromycetes

600 different natural strains of alkali-tolerant micromycetes belonging to 4 classes, 38 genera and 119 species were tested on their ability to produce neutral and alkaline cellulases. Frequency of occurrence of neutral and alkaline cellulases producers among the studied strains was estimated. It is concluded that 72% of all tested strains produce cellulases at neutral and alkaline pH values. But the largest number of neutral and alkaline cellulases producers belong to the following classes which are tolerant to extreme environmental factors: namely Hyphomycetes (genera Acremonium, Alternaria, Cylindrocarpon, Fuzarium, Penicillium, Verticillium, Myrothecium, Ulocladium, Gliocladium), Ascomycetes (genus Chaetomium) and Coelomycetes (genera Phoma, Microsphaeropsis, Aposphaeria).     

Azemiopsin from Azemiops feae viper venom, a novel polypeptide ligand of nicotinic acetylcholine receptor

Azemiopsin, a novel polypeptide, was isolated from the Azemiops feae viper venom by combination of gel filtration and reverse-phase HPLC. Its amino acid sequence (DNWWPKPPHQGPRPPRPRPKP) was determined by means of Edman degradation and mass spectrometry. It consists of 21 residues and, unlike similar venom isolates, does not contain cysteine residues. According to circular dichroism measurements, this peptide adopts a β-structure. Peptide synthesis was used to verify the determined sequence and to prepare peptide in sufficient amounts to study its biological activity. Azemiopsin efficiently competed with α-bungarotoxin for binding to Torpedo nicotinic acetylcholine receptor (nAChR) (IC(50) 0.18 ± 0.03 μm) and with lower efficiency to human α7 nAChR (IC(50) 22 ± 2 μm). It dose-dependently blocked acetylcholine-induced currents in Xenopus oocytes heterologously expressing human muscle-type nAChR and was more potent against the adult form (α1β1εδ) than the fetal form (α1β1γδ), EC(50) being 0.44 ± 0.1 μm and 1.56 ± 0.37 μm, respectively. The peptide had no effect on GABA(A) (α1β3γ2 or α2β3γ2) receptors at a concentration up to 100 μm or on 5-HT(3) receptors at a concentration up to 10 μm. Ala scanning showed that amino acid residues at positions 3-6, 8-11, and 13-14 are essential for binding to Torpedo nAChR. In biological activity azemiopsin resembles waglerin, a disulfide-containing peptide from the Tropidechis wagleri venom, shares with it a homologous C-terminal hexapeptide, but is the first natural toxin that blocks nAChRs and does not possess disulfide bridges.     

Dentition in Pacific walrus (Odobenus rosmarus divergens) calves of the year

The oral cavity and teeth were examined in Pacific walrus calves of the year that died or were harvested on Cape Vancarem and Koluchin Island, the Chukchi Sea, in September to October 2010. The order of gingival eruption of teeth, the resultant dental formula in calves of the year and 1.5-year-old animals, and the dental formula after alveolar eruption of teeth were determined. The number of teeth after gingival eruption in calves of the year did not depend on their body length and sex. The loss of some teeth, mainly incisors, was recorded in individuals aged 5?C6 months. Already at early developmental stages, functional teeth were found to differ significantly from other (rudimentary) teeth in their weight, total size, and the size of apical foramen. Some individuals had milk teeth, which were either gingivally erupted or partly remained within soft tissues. Cases of aberration in dentition that require additional studies were recorded.     

Effect of Dexamethasone on Rat Respiratory Pathways

It has been shown that a short-term application (10–15 min) of dexamethasone at a concentration of 1.0 µg/ml decreases the muscular contraction amplitude of the trachea and large bronchi to 76.2 ± 3.5% and increases the dilatational effect of histamine (1.0 µg/ml) to 47.4 ± 8.1% at stimulation of pre- and postganglionic nerve fibers. Atropine eliminates completely the effect of dexamethasone on the respiratory tract preparation at the stimulation of pre- and postganglionic nerve fibers. The ganglioblocker decreases the dilatational effect at a simultaneous application of atropine and dexamethasone from 47.4 ± 8.1 to 67.2 ± 5.3%. It is concluded that the dexamethasone effect is due to its action on tracheobronchial epithelial receptors and that this effect is mediated by intramural ganglionic neurons.