Lund University

About: Lund University is a education organization based out in Lund, Sweden. It is known for research contribution in the topics: Population & Cancer. The organization has 42345 authors who have published 124676 publications receiving 5016438 citations. The organization is also known as: Lunds Universitet & University of Lund.

Shifts in the structure of soil microbial communities in limed forests as revealed by phospholipid fatty acid analysis

Abstract: The effects of lime and wood-ash on the microbial community structure were evaluated by analyzing the phospholipid fatty acid (PLFA) composition of soils from two areas in the south of Sweden. A pine forest was amended with lime or ash at two concentrations, and a spruce forest was limed at one concentration. The treatments were carried out 5–6 years before sampling and raised the pH from approx. 4.0 to values between 4.8 and 7.0. At both sites there was a difference in the PLFA composition between the treated plots and the controls. The changes found were similar at both sites and correlated to the pH changes. No difference was found between limed plots and those treated with wood-ash. The methyl-branched fatty acids i15:0, i16:0 and 10Me16:0, the monounsaturated fatty acids 16: 1ω 7t and 18: 1ω 9, the cyclopropane fatty acid cy 19:0, and the saturated fatty acid 20:0 were more abundant in the control plots. In the plots with the highest pH there was a three-fold increase in the fatty acid 16: lω 5. An increase was also found for the fatty acids i14:0, 16:lω9, 16:lω 7c, cy17:0, 18:lω 7 and 10Me18:0. No effect on 18:2ω6 was found. The changes in PLFA pattern indicated that the increased pH caused a shift in the bacterial community to more Gram-negative and fewer Gram-positive bacteria, while the amount of fungi was unaffected. The increase in 10Me18:0 in limed soils indicated an increase in actinomycetes.

Human Aging, Muscle Mass, and Fiber Type Composition

Abstract: To assess the age-related loss of muscle mass and to determine the mechanisms behind this aging atrophy, the muscle structure and fiber type composition have been estimated, using invasive and noninvasive techniques. Limb muscles from older men and women are 25-35% smaller and have significantly more fat and connective tissue than limb muscles from younger individuals. Comparisons of muscle biopsies from younger and older individuals reveal that type 2 (fast-twitch) fibers are smaller in the old, while the size of type 1 (slow-twitch) fibers is much less affected. Studies of whole muscle cross sections also show a significantly smaller number of muscle fibers, a significantly lower relative type 2 fiber area, and a significant increase in fiber type grouping with increasing age. These results indicate a gradual decrease in size/volume with advancing age, accompanied by a replacement by fat and connective tissue. This aging atrophy seems to be due to a reduction in both number and size of muscle fibers, mainly of type 2, and is to some extent caused by a slowly progressive neurogenic process.