Anthocyanins and glutathione S-transferase activities in response to low temperature and frost hardening in Vaccinium myrtillus (L.)

Anthocyanin (Acy) contents and GST activities of bilberry (Vaccinium myrtillus L.) were investigated in two experiments conducted in June (Exp. I: active growth) and in August September (Exp. II: beginning of frost hardening) in Northern Finland (65 degrees N). Bilberry plants were subjected to +2 degrees C and +18 degrees C in Exp. I or +5/0 degrees C (day/night) and +18/+13 degrees C (day/night) in Exp. II. GST activities were assessed using either 1-chloro-2,4-dinitrobenzene (CDNB) or trans-cinnamic acid (tCA) as substrates. We found temperature to have no effect on Acy during either active growth or frost hardening. Acy increased several-fold from active growth to the beginning of frost hardening, but no increment was observed during the development of frost hardening. This suggests a role of Acy in photoprotection at low temperatures rather than their direct involvement in the development of freezing tolerance. The lack of response of GST activity to frost hardening and to temperature in autumn may indicate an indirect role of GSTs in frost hardening as protective enzymes. GST activity was the same with the two substrates studied (CDNB, tCA), supporting the assumption that GSTs could catalyze reactions with endogenous phenylpropanoids.     

Post-genomic insight into thylakoid membrane lateral heterogeneity and redox balance

Photosynthetic machinery requires balanced distribution of excitation energy from the light-harvesting complexes to photosystems. The efficiency of light-harvesting is regulated by thermal dissipation of excess energy, while the distribution of energy between photosystems is dependent on STN7 kinase and phosphorylation of thylakoid proteins. The regulation of excitation energy transfer has been linked to the lateral segregation of photosynthetic complexes along the thylakoid membrane. The study of photosynthetic regulation mechanisms using Arabidopsis mutants, which have been available for the last ten years, has challenged traditional views on regulation of excitation energy distribution. Here, we discuss an urgent need to create a holistic view of the dynamics of the thylakoid membrane using systematic research of the mutants available today.     

Bovine Campylobacter jejuni Strains Differ from Human and Chicken Strains in an Analysis of Certain Molecular Genetic Markers

The association of four new genetic markers with a chicken, bovine, or human host was studied among 645 Campylobacter jejuni isolates. The γ-glutamate transpeptidase gene and dmsA were common in human and chicken isolates but uncommon among bovine isolates. In the t test, bovine isolates differed significantly (P < 0.05) from human and chicken isolates.