Holocene paleoenvironmental records from Nikolay Lake, Lena River Delta, Arctic Russia

Radiocarbon-dated pollen, rhizopod, chironomid and total organic carbon records from NikolayLake (73°20'N, 124°12'E), Arga Island, Russia reflect mid- to late Holocene vegetation andclimate changes in the Lena Delta area. Shrubby Alnus fruticosa and Betula nana tundra existedon Arga Island during 6000-4200 14C yr BP, and gradually disappeared after that time. Pollen-based climate reconstructions suggest that climate was relatively warm during 6000-5300 14C yrBP, and rather unstable between ca 5100-3500 14C yr BP. Both qualitative interpretation of pollendata and results of quantitative reconstruction imply that climate and vegetation became similarto modern-day conditions after ca 3400 14C yr BP

On the cultivation of dental spirochetes

The method of cultivation of most spirochaetes is not yet generally available to every bacteriological laboratory; cultivation is associated with considerable, sometimes even insurmountable difficulties, both in relations to preparation of nutrient media and cultivation technique itself, and especially in terms of obtaining pure cultures. For preparation of nutrient media one usually needs blood serum of human, horse, rabbit, ram or guinea pig, or ascitic fluid or hydrocele fluid.</jats:p