Comparing Arachnids in Rovno Amber with the Baltic and Bitterfeld Deposits

Paleontological Journal - So far 107 families of chelicerates are known from the Rovno amber, which is comparable with those known from the Baltic amber (144 families) and three times more than in...     

Clustered carbohydrates as a target for natural killer cells: a model system

Membrane-associated oligosaccharides are known to take part in interactions between natural killer (NK) cells and their targets and modulate NK cell activity. A model system was therefore developed using synthetic glycoconjugates as tools to modify the carbohydrate pattern on NK target cell surfaces. NK cells were then assessed for function in response to synthetic glycoconjugates, using both cytolysis-associated caspase 6 activation measured by flow cytometry and IFN-γ production. Lipophilic neoglycoconjugates were synthesized to provide their easy incorporation into the target cell membranes and to make carbohydrate residues available for cell–cell interactions. While incorporation was successful based on fluorescence monitoring, glycoconjugate incorporation did not evoke artifactual changes in surface antigen expression, and had no negative effect on cell viability. Glycoconjugates contained Le^x, sulfated Le^x, and Le^y sharing the common structure motif trisaccharide Le^x were revealed to enhance cytotoxicity mediated specifically by CD16 ⁺CD56⁺NK cells. The glycoconjugate effects were dependent on saccharide presentation in a polymeric form. Only polymeric, or clustered, but not monomeric glycoconjugates resulted in alteration of cytotoxicity in our system, suggesting that appropriate presentation is critical for carbohydrate recognition and subsequent biological effects.     

A study of the peripheral quaternary ligand binding site of cholinesterase with the use of ethidium bromide

The peripheral binding site of horse serum cholinesterase (EC 3.1.1.7) for quaternary ligands was investigated by fluorescent probing with the use of ethidium bromide. Spectral evidence for the participation of the tryptophan indole group of the peripheral site of horse serum cholinesterase in the formation of a cholinesterase complex with ethidium bromide is presented. The mechanism of cholinesterase effect on ethidium bromide fluorescence is proposed.     

Contribution to the study of the structure of amber forest communities based on analysis of syninclusions in the Rovno amber (Late Eocene of Ukraine)

The composition of syninclusions was analyzed in three representative samples of the Late Eocene Rovno amber. Statistical analysis revealed a stable connection between three pairs of taxa in all three samples, viz., the midges Chironomidae and Ceratopogonidae; the flies Dolichopodidae and aphids Germaraphis; and the mite Glaesacarus rhombeus and Sciara zone dipterans (Sciaroidea, Tipuloidea, etc.). The first pair is interpreted as representing the assemblage of aeroplankton insects; the second, the assemblage of dwellers of the trunks of amber trees; and the third pair, the assemblage of dead wood consumers. The results, although provisional, support the idea that the study of syninclusions is a useful instrument for understanding the structure of past communities.