Validation of DNA methylation profiling in formalin-fixed paraffin-embedded samples using the Infinium HumanMethylation450 Microarray

A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array.     

Patterns of occurrence of myxomycetes in a spruce forest in South Sweden

A 4-yr field study was carried out on selected species of myxomycetes. Reticularia jurana, Symphytocarpus flaecidus, Amaurochaete atra , and A. tubulina occur predominantly in May–June. Ceratiomyxa fruticulosa, Stemonitis axifera, S. fusca, S. hyperopta , and Fuligo septica in June–August, and Colloderma oculatum, Trichia botrytis, T. decipiens , and Fuligo muscorum in September–October. Lycogala epidendrum may occur from May to October. Whereas several species seem to be restricted to late autumn, those appearing in spring and early summer are occasionally found also later in the season. Many species with large plasmodia are rare under arid conditions. Complex factors probably influence spore germination, and it is often impossible to explain a sudden abundance of a species merely from temperature and precipitation. Several species show clear substrate preferences. Plasmodia may develop in cavities in wood and then move out to the surface to fructify. Insects are probably important for the dispersal of several species. Invertebrates, among them snails, are predators on plasmodia as well as on fructifications.     

Arginase,an s-phase enzyme in a human cell line

Suspension cultures of ‘Chang liver’ cells were synchronized by preincubation in a glutamine-deficient medium or by thymidine blockade. Specific arginase activity varied in the synchronized cultures, being high when the number of S-phase cells was maximal. A relationship between high arginase activity and a high percentage of (S+G₂) cells was also found when unsynchronized cells were separated by velocity sedimentation. The increase in arginase activity near the G₁/S border was totally inhibited in the presence of cycloheximide. The rate of decrease in activity after addition of the drug indicated that the variations in the rate of synthesis of the enzyme, while the rate of degradation was more or less constant, corresponding to 4–6% per h. The role of arginase in cells lacking a urea cycle and the regulation of arginase activity in ‘Chang liver’ cells is discussed.