Growth of an ice phase in frozen tissue studied by proton NMR-spectroscopy

Development of an ice phase in frozen tissue is a severe problem in cryo-ultramicrotomy. It is assumed that the growth-rate of such an ice phase is controlled by the mobility of the water molecules in the tissue. In order to verify this, wide-line nmr-spectroscopy has been performed on the protons of frozen whole blood, with and without protective agent, in the temperature range −100 °C- −40 °C. The molecular motion may be characterized by a correlation time, τ, which can be thought of as roughly the mean time between proton jumps. The value of τ can be approximately evaluated from the width of the proton resonance line. It is shown that τ varies rapidly with temperature, in a similar manner to maximum storage time for frozen blood in blood banks. Addition of glycerol increases τ at low temperature, which is consistent with its use as a protective agent in cryobiology. At high temperature, addition of glycerol reduces τ, which is in agreement with reported light-microscope observations on the growth-rate of an ice phase in the same temperature range, nmr-spectroscopy seems to be a useful tool in the further development of cryo-ultramicrotomy. However, to estimate the value in full, more data is required than is presented here.     

Dominating species of entomophilous ascomycetes anamorphs in West Siberia,Primorsky krai,and Kyrgyzstan

The paper studies mycobiota of the dead insects in West Siberia, Primorsky krai, and Kyrgyzstan. Ascomycetes anamorphs of 13 genera are revealed. In all regions Beauveria bassiana (Bals.-Criv.) Vuill. dominated comprising on average 68% of the total number of isolates. The fungus hosts list the insects of 7 orders and 32 families with Coleoptera, Lepidoptera, and Hemiptera dominating. The rarely found entomopathogens include Tolypocladium inflatum Gams (primarily on Lepidoptera), Metarhizium anisopliae (Metschn.) Sorokin (on Coleoptera). The mortality rate of the insects due to micromycetes is observed mainly on enzootic level. The study of the pathogenic properties of the dominating species (B. bassiana) show the absence of specificity of its environmental isolates for a number of representatives of Orthoptera, Lepidoptera, Coleoptera, and Diptera.