Research and assessment of forest soil properties in South-Eastern Lithuania / Pietryčių Lietuvos miško dirvožemio savybių tyrimai ir vertinimas

Along with chemical research on the Scots pine (Pinus sylvestris L.) growing in the South – Eastern part of Lithuania, the analysis of soil properties was given close attention. The analysed forest soil samples were collected in the spring and summer seasons of 2011. Before sampling, a grid of the area covering 10×10 km including all biggest forest areas of the territory was made. In total, 42 composite forest soil samples were examined. The conducted analysis measured soil moisture, pH and the content of total organic carbon. The assessment of these parameters and performed statistical analysis has disclosed that the content of total organic carbon positively and significantly correlates with pH and the content of soil moisture. Additionally, it has been determined that the content of total organic carbon tends to increase when pH of soil is close to neutral and a total value of soil moisture does not reach 0,61%. Santrauka Tiriant Pietryčių Lietuvos paprastosiose pušyse (Pinus sylvestris L.) susikaupusių metalų kiekius, daug dėmesio buvo skiriama dirvožemio savybių analizei. Straipsnyje aptariami miško dirvožemio ėminiai, imti 2011 m. pavasarį ir vasarą. Prieš atliekant lauko tyrimus buvo sudarytas 10 ×10 km dydžio ėminių ėmimo tinklelis, apimantis didžiausius Pietryčių Lietuvos miškų masyvus. Iš viso ištirti 42 sudėtiniai miško dirvožemio ėminiai. Buvo nustatomas dirvožemio drėgnis, pH ir bendrosios organinės anglies kiekis. Įvertinus šiuos parametrus ir atlikus statistinę analizę nustatyta, kad dirvožemio bendrosios organinės anglies kiekis priklauso nuo dirvožemio pH ir drėgnio. Taip pat įvertinus organinės anglies kiekio priklausomybę nuo abiejų minėtųjų parametrų, pastebėta tendencija, kad bendrosios organinės anglies kiekis gali siekti net 30–50 mg/kg (vidutinė koncentracija Pietryčių Lietuvoje yra 6–10 mg/kg), dirvožemio pH vertė – 6–8, o dirvožemio drėgnis mažesnis nei 0,6 %. Raktiniai žodžiai: miškas; dirvožemio pH; bendroji organinė anglis; dirvožemio drėgni

Ryanodine receptor fragmentation and sarcoplasmic reticulum Ca2+ leak after one session of high-intensity interval exercise.

High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly demanding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca(2+) release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent experiments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expression of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-dependent RyR1 fragmentation, calpain activation, increased SR Ca(2+) leak at rest, and depressed force production due to impaired SR Ca(2+) release upon stimulation. In conclusion, HIIT exercise induces a ROS-dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca(2+)-handling trigger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group