Effect of marinobufagenin on the primary reinforcing effect of ethanol]

Intraperitoneal administration of marinobufagenin resulted in a reliable and dose-dependent suppression of ethanol self-administration in drug- and experimentally naive DBA/2 mice. The findings suggest that Na/K-ATPase contributes to both mediation of the ethanol reinforcing properties and the mood regulation.     

Biosynthesis and use of coproporphyrins and uroporphyrins and their metal complexes in immune analysis and diagnostic methods]

Methods of synthesis of coproporphyrin and uroporphyrin by using bacteria of the genus Arthrobacter are proposed. Metal complexes of coproporphyrin and uroporphyrin with Pt, Pd, and Zn were synthesized. Their structures were identified by spectrophotometry, IR spectrometry, 1H-NMR, mass spectrometry, and HPLC. Data showing the possibility to use coproporphyrin III-metal complexes as luminophores for fluorescence detection of tumors. The current and prospective uses of metal complexes of water-soluble natural porphyrins in advanced immunofluorescence assays are discussed.     

Changes in Wheat Leaf Extracellular Proteolytic Activity after Infection with Septoria tritici

The proteolytic activity of the leaf extracellular space of wheat cultivars Pigüé and Isla Verde was estimated after inoculation of either detached leaves or plants with the fungus Septoria tritici. Pigüé is resistant, whereas Isla Verde is susceptible to the disease caused by S. tritici. Viable conidiospores of the fungus caused similar increases in both hydrogen peroxide production and chitinase activity of the cultivars studied. In contrast, they caused a decrease in the extracellular serine proteinase activity of Isla Verde and a significant increase in that of Pigüé. Independently of the cultivar from which it was extracted, the extracellular serine proteinase inhibited the germination of Septoria tritici conidiospores. These results suggest that the proteolytic activity of the leaf extracellular space can participate in the defence of wheat plants against Septoria tritici. Its regulation may be controlled by specific defence components of each cultivar.     

Retrospective estimate of the individual history of life in population studies on mammals]

Analysis of the recording structures in mammals, such as dentine, cementum, or bone tissue, makes it possible to estimate the parameters of individual history of life: age at the moment of death, seasons of death and birth, growth rate, age of sexual maturation, etc. Using the reindeer (Rangifer tarandus) as an example, it has been shown what specific life features essential for population studies may be estimated when only mandibles with teeth are available.     

Termite Prey Specialization in the Pitcher Plant Nepenthes albomarginata--Evidence from Stable Isotope Analysis

Old World pitcher plants (Nepenthes spp., Nepenthaceae) trapand digest invertebrate prey to derive nutrients, primarilynitrogen (N). In the majority of lowland Nepenthes species studiedto date, ants (Hymenoptera, Formicidae) are numerically thedominant prey taxon. Nepenthes albomarginata is unusual in showingan apparent bias towards the capture of termites (Isoptera).We tested the hypothesis that N. albomarginata derives N fromtermite capture, by comparison of foliar stable N isotope abundance(     

Specificity of GlcNAc-PI de-N-acetylase of GPI biosynthesis and synthesis of parasite-specific suicide substrate inhibitors.

The substrate specificities of Trypanosoma brucei and human (HeLa) GlcNAc-PI de-N-acetylases were determined using 24 substrate analogues. The results show the following. (i) The de-N-acetylases show little specificity for the lipid moiety of GlcNAc-PI. (ii) The 3'-OH group of the GlcNAc residue is essential for substrate recognition whereas the 6'-OH group is dispensable and the 4'-OH, while not required for recognition, cannot be epimerized or substituted. (iii) The parasite enzyme can act on analogues containing betaGlcNAc or aromatic N-acyl groups, whereas the human enzyme cannot. (iv) Three GlcNR-PI analogues are de-N-acetylase inhibitors, one of which is a suicide inhibitor. (v) The suicide inhibitor most likely forms a carbamate or thiocarbamate ester to an active site hydroxy-amino acid or Cys or residue such that inhibition is reversed by certain nucleophiles. These and previous results were used to design two potent (IC50 = 8 nM) parasite-specific suicide substrate inhibitors. These are potential lead compounds for the development of anti-protozoan parasite drugs.     

DNA helicase-mediated packaging of adeno-associated virus type 2 genomes into preformed capsids.

Helicases not only catalyse the disruption of hydrogen bonding between complementary regions of nucleic acids, but also move along nucleic acid strands in a polar fashion. Here we show that the Rep52 and Rep40 proteins of adeno-associated virus type 2 (AAV-2) are required to translocate capsid-associated, single-stranded DNA genomes into preformed empty AAV-2 capsids, and that the DNA helicase function of Rep52/40 is essential for this process. Furthermore, DNase protection experiments suggest that insertion of AAV-2 genomes proceeds from the 3' end, which correlates with the 3'-->5' processivity demonstrated for the Rep52/40 helicase. A model is proposed in which capsid-immobilized helicase complexes act as molecular motors to 'pump' single-stranded DNA across the capsid boundary.     

Crystal structure of a dynamin GTPase domain in both nucleotide-free and GDP-bound forms.

Dynamins form a family of multidomain GTPases involved in endocytosis, vesicle trafficking and maintenance of mitochondrial morphology. In contrast to the classical switch GTPases, a force-generating function has been suggested for dynamins. Here we report the 2.3 A crystal structure of the nucleotide-free and GDP-bound GTPase domain of Dictyostelium discoideum dynamin A. The GTPase domain is the most highly conserved region among dynamins. The globular structure contains the G-protein core fold, which is extended from a six-stranded beta-sheet to an eight-stranded one by a 55 amino acid insertion. This topologically unique insertion distinguishes dynamins from other subfamilies of GTP-binding proteins. An additional N-terminal helix interacts with the C-terminal helix of the GTPase domain, forming a hydrophobic groove, which could be occupied by C-terminal parts of dynamin not present in our construct. The lack of major conformational changes between the nucleotide-free and the GDP-bound state suggests that mechanochemical rearrangements in dynamin occur during GTP binding, GTP hydrolysis or phosphate release and are not linked to loss of GDP.