The role of granivores and soil pathogens in seedling recruitment of invasive tree species: the case of northern red oak and ash-leaved maple

Wydział BiologiiZbadałam interakcje między drzewami a gryzoniami i mikroorganizmami glebowymi, w szczególności: Dokonałam przeglądu obecnej wiedzy na temat roli gryzoni w odnowieniu lasu po zaburzeniach, w szczególności w lasach gospodarczych klimatu umiarkowanego. Rozpatrzyłam dwojaki wpływ gryzoni, co obejmuje mutualistyczne i antagonistyczne interakcje z nasionami drzew; Przetestowałam, czy gatunki gryzoni współwystępujące na danym terenie różnią się efektywnością jako roznosiciele nasion Quercus rubra na jego rodzimym obszarze. Gryzonie różniące się wielkością ciała miały odmienny wpływ na los żołędzi; Przedstawiłam, jak różnice w roznoszeniu nasion wpływają na podatność odmiennych siedlisk na inwazję roślin. Zbadałam los nasion inwazyjnego Q. rubra i rodzimego Q. robur wynoszonych przez rodzime gatunki gryzoni w różnych typach lasów. Moje wyniki wskazują, że wzorce roznoszenia nasion zależne od rodzaju siedliska mogą sprzyjać odnowieniu dębu czerwonemu na granicy jego występowania poza jego naturalnym zasięgiem; Sprawdziłam, czy efekt Janzena-Connella spowodowany działalnością mikroorganizmów glebowych odmiennie wpływa na introdukowane i rodzime gatunki drzew. Wyniki wykazały, że osłabiony efekt J-C może przyczynić się do postępującej inwazji niektórych gatunków drzew. Moje wyniki pomogą lepiej zrozumieć rolę wybranych czynników w odnowieniu rodzimych i introdukowanych gatunków drzew.I examined tree-rodent and tree-soil microbiota interactions, in particular: I reviewed current knowledge about the role of rodents in forest regeneration after disturbance, particularly in temperate managed forest stands. I discussed a dual effect of the rodents on forest regeneration, which includes both mutualistic and antagonistic interactions with tree seeds; I examined whether various members of a granivorous rodent community differ in their effectiveness as seed removal agents in Quercus rubra in its native range. I found that granivorous rodents of different body sizes strongly vary in their interactions with acorns; I described how habitat-related differences in seed dispersal affect susceptibility of distinct habitat types to plant invasions. I examined the fate of invasive Q. rubra and native Q. robur acorns dispersed by native rodents in different European forest types. My findings suggest that habitat-dependent patterns in seed dispersal may promote recruitment of Q. rubra at the edges of invaded range; I tested whether introduced and native tree species are differentially influenced by the Janzen-Connell effect caused by soil-borne organisms. The results indicated that weakened J-C effect may contribute to successful invasions of some alien trees. My findings improve general understanding of factors involved in the recruitment of native and invasive tree species

Degradation of glycine and alanine on irradiated quartz

Recent researches suggest participation of minerals in the formation of life under primordial conditions. Among all of the minerals, quartz seems to be one of the most probable to take part in such processes. However, an external source of energy is needed, e.g. electric discharge. A device simulating the proposed conditions was designed and was used to simulate prebiotic conditions. Investigation of processes occurring during the stimulation of quartz with electric discharge was studied by means of Ultraviolet-visible (UV-VIS) spectroscopy, in order to monitor the generation kinetics of free radicals. Additionally, infrared spectroscopy was applied to identify chemical reaction products created in a solution of alanine or glycine, in the presence of quartz treated with electric discharge. Formation of increased amounts of free radicals, compared to experiments performed without quartz and/or amino acid, is reported, along with identification of possible degradation products of alanine. No synthetic reactions were observed

It is raining mice and voles: which weather conditions influence the activity of Apodemus flavicollis and Myodes glareolus?

Rodents constitute a crucial part of food chains in many ecosystems; thus, changes in their activity might influence many other species in the community. Moreover, daily variations in activity appear to be an important adaptation, helping rodents to cope with fluctuating intensity of predation pressure and food availability. We investigated how the nightly activity of the yellow-necked mouse (Apodemus flavicollis) and the bank vole (Myodes glareolus) changes with weather conditions. Increased cloud cover enhanced activity of mice, but this effect tended to be weaker during the full moon. In turn, the activity of bank voles was positively influenced by moon phase regardless of cloud cover. Temperature had a negative effect on the activity of both species. Rainfall positively influenced A. flavicollis capture numbers, but tended to decrease the activity of M. glareolus. Therefore, while the activity of both mice and voles was under a strong influence of weather variables, their responses to weather were largely species specific.Polish Ministry of Science and Higher Education Grant NN304391537, Adam Mickiewicz Foundatio

Topology testing of phylogenies using least squares methods

BACKGROUND: The least squares (LS) method for constructing confidence sets of trees is closely related to LS tree building methods, in which the goodness of fit of the distances measured on the tree (patristic distances) to the observed distances between taxa is the criterion used for selecting the best topology. The generalized LS (GLS) method for topology testing is often frustrated by the computational difficulties in calculating the covariance matrix and its inverse, which in practice requires approximations. The weighted LS (WLS) allows for a more efficient albeit approximate calculation of the test statistic by ignoring the covariances between the distances. RESULTS: The goal of this paper is to assess the applicability of the LS approach for constructing confidence sets of trees. We show that the approximations inherent to the WLS method did not affect negatively the accuracy and reliability of the test both in the analysis of biological sequences and DNA-DNA hybridization data (for which character-based testing methods cannot be used). On the other hand, we report several problems for the GLS method, at least for the available implementation. For many data sets of biological sequences, the GLS statistic could not be calculated. For some data sets for which it could, the GLS method included all the possible trees in the confidence set despite a strong phylogenetic signal in the data. Finally, contrary to WLS, for simulated sequences GLS showed undercoverage (frequent non-inclusion of the true tree in the confidence set). CONCLUSION: The WLS method provides a computationally efficient approximation to the GLS useful especially in exploratory analyses of confidence sets of trees, when assessing the phylogenetic signal in the data, and when other methods are not available

Empagliflozin. Results of the EMPA-REG OUTCOME trial. A breakthrough in treatment of type 2 diabetes?

Cardiovascular (CV) complications are the main health challenge among type 2 diabetic patients. They may cause premature death, disability and reduce the quality of life. Administering a multifactorial intervention aimed at controlling glycaemia, lipaemia and arterial blood pressure allows to reduce the risk of their occurrence. FDA ruled that all newly introduced hypoglycaemic agents must undergo tests for CV safety. The EMPAREG OUTCOME trial was conducted on a group of type 2 diabetic patients at high CV risk. It showed that including empagliflozin in the standard therapy reduces the risk of primary outcome (death from CV causes, non-fatal myocardial infarction or non-fatal stroke) by 14% and all-cause mortality by 32%. The causes of this effect of empagliflozin — an inhibitor of SGLT2, which is an enzyme present only in renal proximal tubules — are unclear. Reduction in insulin resistance and in oxidative stress, changes in lipid levels, reduction in uric acid levels, in albuminuria, in blood pressure and reduction in sympathetic activity are all named as potential mechanisms underlying the  rotective effect of empagliflozin. Results of the EMPA-REG OUTCOME trial are a breakthrough in the treatment of diabetes, and if other SGLT2 inhibitors are found to have similar effects, a fundamental change in therapy recommendations for this patient population may be made

Caffeine enhances the antidepressant-like activity of common antidepressant drugs in the forced swim test in mice

Caffeine is the most widely used behaviorally active drug in the world which exerts its activity on central nervous system through adenosine receptors. Worrying data indicate that excessive caffeine intake applies to patients suffering from mental disorders, including depression. The main goal of the present study was to evaluate the influence of caffeine on animals’ behavior in forced swim test (FST) as well as the effect of caffeine (5 mg/kg) on the activity of six typical antidepressants, such as imipramine (15 mg/kg), desipramine (10 mg/kg), fluoxetine (5 mg/kg), paroxetine (0.5 mg/kg), escitalopram (2 mg/kg), and reboxetine (2.5 mg/kg). Locomotor activity was estimated to verify and exclude false-positive/negative results. In order to assess the influence of caffeine on the levels of antidepressant drugs studied, their concentrations were determined in murine serum and brains using high-performance liquid chromatography. The results showed that caffeine at a dose of 10, 20, and 50 mg/kg exhibited antidepressant activity in the FST, and it was not related to changes in locomotor activity in the animals. Caffeine at a dose of 5 mg/kg potentiated the activity of all antidepressants, and the observed effects were not due to the increase in locomotor activity in the animals. The interactions between caffeine and desipramine, fluoxetine, escitalopram, and reboxetine were exclusively of pharmacodynamic character, because caffeine did not cause any changes in the concentrations of these drugs neither in blood serum nor in brain tissue. As a result of joint administration of caffeine and paroxetine, an increase in the antidepressant drug concentrations in serum was observed. No such change was noticed in the brain tissue. A decrease in the antidepressant drug concentrations in brain was observed in the case of imipramine administered together with caffeine. Therefore, it can be assumed that the interactions caffeine-paroxetine and caffeine-imipramine occur at least in part in the pharmacokinetic phase

Influence of the CB1 and CB2 cannabinoid receptor ligands on the activity of atypical antidepressant drugs in the behavioural tests in mice

Available data support the notion that cannabinoids, whose therapeutic value is limited due to severe adverse reactions, could be beneficial as adjunctive agents in the management of mood disorders. Polytherapy, which is superior to monotherapy in the terms of effectiveness, usually requires lower doses of the individual components. Therefore, the main objective of our study was to determine whether administration of cannabinoid (CB) receptor ligands would enhance the antidepressant activity of atypical antidepressant drugs, i.e. agomelatine and tianeptine. To evaluate the antidepressant-like potential of the tested combinations, the mouse forced swim test (FST) and the tail suspension test (TST) were used. The HPLC method was applied to assess the brain levels of agomelatine and tianeptine. Both behavioural tests demonstrated that per se an ineffective intraperitoneal dose of oleamide (CB1 receptor agonist, 5 mg/kg) potentiated the anti-immobility activity of tianeptine (15 mg/kg), whereas AM251 (CB1 receptor inverse agonist/antagonist, 0.25 mg/kg) enhanced the antidepressant effects of tianeptine and agomelatine (20 mg/kg). Intraperitoneal co-administration of per se inactive doses of AM630 (CB2 receptor inverse agonist/antagonist) and agomelatine or tianeptine significantly reduced the immobility time of animals only in the FST. CB receptor ligands did not affect the brain levels of the tested atypical antidepressants. In summary, the outcomes of the present study showed that activation and inhibition of CB1 receptors as well as inhibition of CB2 receptors may increase the antidepressant activity of tianeptine, whereas only inhibition of CB1 and CB2 receptors has a potential to augment the antidepressant activity of agomelatine

Novel biomarkers of overactive bladder syndrome

The social aspect of overactive bladder syndrome (OAB) and the lack of objective diagnostic methods for this syndrome have spurred research into its potential biomarkers which can constitute useful diagnostic tools, while also allowing the evaluation of the intensity of clinical symptoms and the efficacy of implemented pharmacotherapy in OAB patients. Due to the complex etiopathogenesis of this syndrome, the researchers are seeking biomarkers connected with inflammation or nerve growth. The aim of this review was to analyse the latest literature data regarding potential biomarkers in OAB. The most promising opportunities are connected with the diagnostic use of the nerve growth factor (NGF), the brain derived neurotrophic factor (BDNF), C-reactive protein (CRP), prostaglandins and cytokines. Despite the most promising results to date having been obtained with regards to neurotrophic factors, it seems that, at the moment, none of these meets the criteria for becoming an isolated OAB marker. It is also suggested that the combined use of several biomarkers will facilitate obtaining the appropriate level of specificity and selectivity to allow their use in clinical practice