Fluctuating ungulate density shapes tree recruitment in natural stands of the Białowieża Primeval Forest,Poland

Question: What are the main driving factors in 70 years of natural dynamics in tree recruitment in the Bia?owie?a National Park? Location: Bia?owie?a National Park, Poland, is one of the least disturbed temperate, lowland forest systems in Europe. Methods: We tested whether fluctuations in large herbivore populations, changes in climate and openness of the forest explained compositional dynamics. Tree recruitment (to size class DBH≥5 cm) was measured on permanent transects (in total, 14.9 ha) six times between 1936‐2002. These data were related to existing data on ungulate density, climatic parameters and estimates of forest openness collected during the same period. Results: Total recruitment of all tree species combined was negatively correlated with total ungulate density and red deer density. The variation in response between species was related to the preferences of herbivores; the more preferred forage species (especially Carpinus betulus) were positively and the less preferred species negatively related to herbivore density. Total tree recruitment rates were not related to climatic parameters and openness of the forest. Only Alnus glutinosa recruitment was significantly related to climatic parameters, and Ulmus glabra related to forest openness, but there were no predictable patterns in recruitment among species in relation to these factors. Conclusion: The present study indicated that changes in large herbivore density have played an important role in driving patterns in tree recruitment and species composition during the last 70 years in Bia?owie?a National Park. In contrast to other studies, increasing herbivore numbers were associated with higher recruitment of preferred and browsing‐tolerant species. Periodical crashes in ungulate numbers, whether human‐induced or caused by natural factors, may offer windows of opportunity for regeneration of a range of tree species and facilitate more diverse and dynamic forest development.     

Anticonvulsant evaluation of aminoalkanol derivatives of 2- and 4-methylxanthone

A series of 17 new aminoalkanol derivatives of 6-methoxy- or 7-chloro-2-methylxanthone as well as 6-methoxy-4-methylxanthone was synthesized and evaluated for anticonvulsant activity. All compounds were verified in mice after intraperitoneal (ip) administration in maximal electroshock (MES) and subcutaneous pentetrazole (scMet) induced seizures as well as neurotoxicity assessment. Eleven of the tested substances showed protection against electrically evoked seizures in the majority of the tested mice at the dose of 100 mg/kg. Additionally, one was effective at the dose of 30 mg/kg. Five substances were active at the dose of 300 mg/kg or at the dose of 100 mg/kg in the minority of the tested mice. The most promising compound revealed ED₅₀ value of 47.57 mg/kg in MES (mice, ip, 1 h after administration) and at the same time its TD₅₀ was evaluated as above 400 mg/kg. Those values gave PI (calculated as TD₅₀/ED₅₀) of more than 8.41. Three other synthesized xanthone derivatives also proved to act as anticonvulsants and showed ED₅₀ values in MES test (mice, ip) ranged 80–110 mg/kg. Results were quite encouraging and suggested that in the group of xanthone derivatives new potential anticonvulsants might be found.     

Detection of three rotational correlation times for a rigid asymmetric molecule using frequency-domain fluorometry

We measured the frequency response of the polarized emission of Y_t-base in propylene glycol at 10 ° C. Data were obtained for excitation wavelengths of 290, 312 and 346 nm, for which the fundamental anisotropies are 0.05, 0.19 and 0.32, respectively. Additionally, data were obtained using CCl₄, to decrease the mean decay time from 9.1 to 4.2 ns. These nine sets of data were analyzed globally to recover the anisotropy decay law. Three correlation times were needed to fit the data, 0.8, 3.0 and 5.6 ns, a range of only 7-fold. We believe this is the first reported detection of three correlation times for a rigid molecule.     

Fluorescence-detected polymerization kinetics of human α1-antitrypsin

The time dependence of the humanα ₁-antitrypsin polymerization process was studied by means of the intrinsic fluorescence stopped-flow technique as well as the fluorescence-quenching-resolved spectra (FQRS) method and native PAGE. The polymerization was induced by mild denaturing conditions (1 M GuHCl) and temperature. The data show that the dimer formation reaction under mild conditions was followed by an increase of fluorescence intensity. This phenomenon is highly temperature sensitive. The structure ofα ₁-antitrypsin dimer resembles the conformation of antithrombin III dimer. In the presence of the denaturant the polymerization process is mainly limited to the dimer state. Theα ₁-antitrypsin activity measurements confirm monomer-to-dimer transition under these conditions. These results are in contrast to the polymerization process induced by temperature, where the dimer state is an intermediate step leading to long-chain polymers. On the basis of stopped-flow and electrophoretic data it is suggested that both C-sheet as well as A-sheet mechanisms contribute to the polymerization process under mild conditions.     

Germination of soybean seeds exposed to the static/alternating magnetic field and algal extract

In the present study, the effect of the static and alternating magnetic field applied individually and in combination with an algal extract on the germination of soybean seeds (Glycine max (L.) Merrill) and chlorophyll content was examined. The exposure time of seeds to the static magnetic field was 3, 6, and 12 min, whereas to the alternating magnetic field was 1, 2.5, and 5 min. The static magnetic field was obtained by means of a permanent magnets system while the alternating magnetic field by means of magnetic coils. Algal extract was produced from a freshwater macroalga—Cladophora glomerata using ultrasound homogenizer. In the germination tests, 10% extract was applied to the paper substrate before sowing. This is the first study that compares the germination of soybean seeds exposed to the static and alternating magnetic field. The best effect on the germination and chlorophyll content in seedlings had synergistic action of the static magnetic field on seeds for 3 min applied together with the extract and alternating magnetic field used for 2.5 min. It is not possible to clearly state which magnetic field better stimulated the germination of seeds, but the chlorophyll content in seedlings was much higher for alternating magnetic field.     

Error Normality Testing in a Model of Two-Way Nested Classification

The paper deals with the construction of a normality test for the verification of the assumption about normal distribution of random errors in a fixed model of two-way nested classification. For this purpose adequate linear transformations and orthogonal observable random vectors have been presented. To the adjusted residual vector obtained after these transformations, the D'Agostino normality test has been applied.