Influence of Extracts from Bark of Deciduous Trees on the Activity of the Amylolytic Enzyme - Alpha Amylase

The effect of water extracts obtained from bark of growing in Latvia and widely spread in Europe grey alder (Alnusincana), black alder (Alnusglutinosa) and aspen tree (Populustremula), on the amylase activity in human saliva was evaluated. The extracts were obtained using advanced ACE equipment and distilled hot water as a solvent. The total yields of extractives from bark were rather similar and varied from 16 % to 21 % based on dry bark. However, the content of proantocianidine and salicine derivatives used as diagnostic characteristic for evaluation of effect of extracts on activity of amylase – a glucose-polymers cleavage enzyme - differed significantly. The results of in-vitro tests realized using the model of human gastrointestinal pass have shown that the abovementioned extracts in micro dosages are able to increase significantly activity of amylase. However, this effect is dose dependent and when the dose is exceeded the opposite effect – inhibition of amylase activity - is observed. This effect is explained by increasing of proantocianidins component in the volume of the tested extract dose, because pure proantocianidins, isolated from grey alder bark significantly inhibited activity of amylase. The further investigation is necessary in order to estimate effective and safe dosages for application of extracts providing a guaranteed unambiguous effect of activation or inhibition of amylase activity.

INFLUENCE OF THE MANAGED FORESTS ON CO2 BALANCE IN EARTH’S ATMOSPHERE

Technical energy costs required for forest cultivation, estimation of C-CO2 fluxes in model experiments with coniferous species of pine Pinus sylvestris L. and leaves species, natural form and gene modified clone of the ordinary aspen tree Populus tremula L., have been analyzed. At plantation cultivation of transgenic aspen clone with nitrogen fertilizers indirect costs of technical energy made up 85 % of total power input. A new three-stage method has been developed for assessing the impact of forests on the CO2 balance in the Earth's atmosphere. The final value of CO2 sink from the atmosphere at afforestation depends on the way wood is used.

Functional imaging of microbial interactions with tree roots using a microfluidics setup

Coupling microfludics with microscopy has emerged as a powerful approach to study at cellular resolution the dynamics in plant physiology and root-microbe interactions. Most devices have been designed to study the model plant Arabidopsis thaliana at higher throughput than conventional methods. However, there is a need for microfluidic devices which enable in vivo studies of root development and root-microbe interactions in woody plants. Here, we developed the RMI-chip, a simple microfluidic setup in which Populus tremuloides (aspen tree) seedlings can grow for over a month, allowing continuous microscopic observation of interactions between live roots and rhizobacteria. We find that the colonization of growing aspen roots by Pseudomonas fluorescens in the RMI-chip involves dynamic biofilm formation and dispersal, in keeping with previous observations in a different experimental set-up. Also, we find that whole-cell biosensors based on the rhizobacterium Bacillus subtilis can be used to monitor compositional changes in the rhizosphere but that the application of these biosensors is limited by their efficiency at colonizing aspen roots and persisting. These results indicate that functional imaging of dynamic root-bacteria interactions in the RMI-chip requires careful matching between the host plant and the bacterial root colonizer.

Precommercial thinning of trembling aspen in northern Ontario: Part 1 – Growth responses

In Ontario, trembling aspen (Populus tremuloides Michx.) utilization has increased over the past 20 years and this trend is expected to continue. With this increased demand, questions are being raised about stand conditions required for optimum growth. In 1979, a study was initiated across the commercial range of aspen in northern Ontario to determine the optimum precommercial thinning intensities for aspen tree and stand growth. Six pure aspen stands between the ages of five and 22 years were thinned to residual spacings of 2 × 2 m, 3 × 3 m, 4 × 4 m, and 5 × 5 m. Unthinned and thinned plots were measured at regular intervals for up to 17 years after treatment. Diameter increased significantly with residual tree spacing over the range of site conditions, geographic locations, and tree ages. Precommercial thinning resulted in significantly increased height in three of the stands, and height generally increased with increased residual spacing. Fifteen to 17 years after treatment, gross total volume (GTV) was highest in the unthinned plots for all six stands and decreased as residual tree spacing increased. Gross merchantable volume (GMV) did not vary significantly with thinning in all but the oldest stand. The results of this study do not support the use of precommercial thinning to increase aspen fibre yield. However, if the management goal is maximizing individual tree growth, precommercial thinning of aspen should be considered. Key words: Trembling aspen, precommercial thinning, DBH response, height response, northern Ontario

Identification of Armillaria species isolated from bigtooth aspen based on rDNA RFLP analysis

Restriction fragment length polymorphism analysis (RFLP) of the intergenic region (IGR-1) between the 3 ' end of the 26S ribosomal RNA gene and the 5 ' end of the 5S rRNA gene was used to identify 39 isolates of Armillaria species collected from live or recently dead bigtooth aspen (Populus grandidentata Michx.) trees and sucker sprouts in the Tioga State Forest, Pennsylvania. The unknown isolates were identified by comparing their restriction fragment patterns with 18 isolates of known Armillaria species common to the northeastern United States. Twenty of the unknown isolates (50%) were identified as either Armillaria gallica or Armillaria calvescens. Eighteen (46%) of the isolates were identified as Armillaria ostoyae. One isolate of Armillaria sinapina was obtained from a recently dead aspen tree. One isolate of Armillaria mellea, considered to be the most divergent of the Armillaria species, was obtained from basidiomes fruiting on a recently dead aspen tree near Berwick, Pennsylvania. In some instances, amplification of DNA was possible by adding mycelial scrapes directly to the polymerase chain reaction (PCR) mix, thus precluding the need for DNA extraction. Advancements in RFLP analysis may offer a method able to provide rapid and precise identification of most North American and European Armillaria isolates.