University of Turku

About: University of Turku is a education organization based out in Turku, Finland. It is known for research contribution in the topics: Population & Galaxy. The organization has 16296 authors who have published 45124 publications receiving 1505428 citations. The organization is also known as: Turun yliopisto & Åbo universitet.

Nutrient stress: an explanation for plant anti-herbivore responses to defoliation

Abstract: A hypothesis is put forward that the long-lasting inducible responses of trees to herbivores, particularly lepidopteran defoliators, may not be active defensive responses, but a by-product of mechanisms which rearrange the plant carbon/nutrient balance in response to nutrient stress caused by defoliation. When defoliation removes the foliage nutrients of trees growing in nutrient-poor soils, it increases nutrient stress wich in turn results in a high production of carbon-based allelochemicals. The excess of carbon that cannot be diverted to growth due to nutrient stress is diverted to the production of plant secondary metabolites. The level of carbon-based secondary substances decays gradually depending on the rate at which nutrient stress is relaxed after defoliation. In nutrient-poor soils and in plant species with slow compensatory nutrient uptake rates the responses induced by defoliation can have relaxation times of several years. The changes in leaf nitrogen and phenolic content of mountain birch support this nutrient stress hypothesis. Defoliation reduces leaf nitrogen content while phenolic content increases. These responses of mountain birch to defoliation are relaxed within 3–4 years.

Morphologic criteria and detection of apoptosis.

Abstract: Apoptosis is an organized, energy dependent process, which leads to cell death. Its definition is based on distinct morphological features [10] and demonstration of internucleosomal DNA degradation [27], executed by selectively activated DNAses [4, 22]. The morphologic hallmarks of apoptosis include chromatic margination, nuclear condensation and fragmentation, and condensation of the cell with preservation of organelles. The process is followed by fragmentation of the cell into membrane-bound apoptotic bodies, which undergo phagocytosis by nearby cells without associated inflammation [10, 11]. Apoptosis characteristically occurs in isolated single cells. The duration of apoptosis is estimated to be from 12 to 24 hours, but in cell culture visible morphologic changes are accomplished in less than two hours [10, 16]. Non-apoptotic cell death, a prototype of which is cell death due to ischemia (oncosis), is characterized by depletion of intracellular ATP stores, swelling of the cell with disruption of organelles and rupture of the plasma membrane [15]. Groups of necrotic cells and inflammation are found in tissues [10, 15].

Responses in the start of Betula (birch) pollen seasons to recent changes in spring temperatures across Europe

Abstract: A shift in the timing of birch pollen seasons is important because it is well known to be a significant aeroallergen, especially in NW Europe where it is a notable cause of hay fever and pollen-related asthma. The research reported in this paper aims to investigate temporal patterns in the start dates of Betula (birch) pollen seasons at selected sites across Europe. In particular it investigates relationships between the changes in start dates and changes in spring temperatures over approximately the last 20 years. Daily birch pollen counts were used from Kevo, Turku, London, Brussels, Zurich and Vienna, for the core period from 1982 to 1999 and, in some cases, from 1970 to 2000. The sites represent a range of biogeographical situations from just within the Arctic Circle through to North West Maritime and Continental Europe. Pollen samples were taken with Hirst-type volumetric spore traps. Weather data were obtained from the sites nearest to the pollen traps. The timing of birch pollen seasons is known to depend mostly on a non-linear balance between the winter chilling required to break dormancy, and spring temperatures. Pollen start dates and monthly mean temperatures for January through to May were compiled to 5-year running means to examine trends. The start dates for the next 10 years were calculated from regression equations for each site, on the speculative basis that the current trends would continue. The analyses show regional contrasts. Kevo shows a marked trend towards cooler springs and later starts. If this continues the mean start date will become about 6 days later over the next 10 years. Turku exhibits cyclic patterns in start dates. A current trend towards earlier starts is expected to continue until 2007, followed by another fluctuation. London, Brussels, Zurich and Vienna show very similar patterns in the trends towards earlier start dates. If the trend continues the mean start dates at these sites will advance by about 6 days over the next 10 years. Following this work, amendments will be needed to pollen calendars and local predictive models. It will also be important to assess the implications of earlier seasons for allergy sufferers.

A possible link between early probiotic intervention and the risk of neuropsychiatric disorders later in childhood: a randomized trial.

Abstract: Recent experimental evidence suggests that gut microbiota may alter function within the nervous system providing new insight on the mechanism of neuropsychiatric disorders. Seventy-five infants who were randomized to receive Lactobacillus rhamnosus GG (ATCC 53103) or placebo during the first 6 mo of life were followed-up for 13 y. Gut microbiota was assessed at the age of 3 wk, 3, 6, 12, 18, 24 mo, and 13 y using fluorescein in situ hybridization (FISH) and qPCR, and indirectly by determining the blood group secretor type at the age of 13 y. The diagnoses of attention deficit hyperactivity disorder (ADHD) and Asperger syndrome (AS) by a child neurologist or psychiatrist were based on ICD-10 diagnostic criteria. At the age of 13 y, ADHD or AS was diagnosed in 6/35 (17.1%) children in the placebo and none in the probiotic group (P = 0.008). The mean (SD) numbers of Bifidobacterium species bacteria in feces during the first 6 mo of life was lower in affected children 8.26 (1.24) log cells/g than in healthy children 9.12 (0.64) log cells/g; P = 0.03. Probiotic supplementation early in life may reduce the risk of neuropsychiatric disorder development later in childhood possible by mechanisms not limited to gut microbiota composition.

Striatal dopamine D1 and D2 receptors in burning mouth syndrome.

Abstract: Animal studies have indicated that the nigrostriatal dopaminergic system is involved in central pain modulation. In a recent positron emission tomography (PET) study, we demonstrated presynaptic dysfunction of the nigrostriatal dopaminergic pathway in burning mouth syndrome, which is a chronic pain state. The objective of the present study was to examine striatal dopamine D1 and D2 receptors in these patients. We used 11C-NNC 756 and 11C-raclopride to study D1 and D2 receptor binding in a PET study in ten burning mouth patients and 11 healthy controls. Patients underwent a structured psychiatric evaluation and an electrophysiological test for the excitability of the blink reflex. The striatal uptake of 11C-NNC 756 did not differ between patients and controls. In a voxel-level analysis, the uptake of 11C-raclopride was statistically significantly higher in the left putamen in burning mouth patients (corrected P-value 0.038 at cluster-level). In the region of interest analysis, the D1/D2 ratio was 7.7% lower in the right putamen (0.64+/-0.04 vs. 0.69+/-0.04, P=0.01) and 6.4 % lower in the left putamen (0.65+/-0.05 vs. 0.70+/-0.05, P=0.05) when compared to controls. Increased 11C-raclopride uptake and the subsequent decrease in the D1/D2 ratio may indicate a decline in endogenous dopamine levels in the putamen in burning mouth patients.