Populacja bobrów (Castor fiber L., 1758) w Puszczy Augustowskiej

The study on the distribution and abundance of beaver families in the Augustowska Primeval Forest was conducted in the years 2000 -2003. It embraced all seven Forest Inspectorates administering the Forest. The study consisted in the penetration of banks along watercourses, lakes and drainage ditches. Lodges, bank dens, dams and the length of the banks colonized by beaver families were plotted on maps. Habitat types contained within the territories of individual beaver families were established on the basis of the maps obtained from Forest Inspectorates. The percentage of bank utilisation by beavers in various types of water bodies was determined. The number of beaver lodges and bank dens, as well as their number per family were established. Also, habitat preferences of beavers in individual water bodies were verified. The presented study has the form of a report which can be used for further monitoring of beaver populations in the Augustowska Primeval Forest.W latach 2000–2003 prowadzono badania nad populacją bobrów w Puszczy Augustowskiej. Ogółem w 7 nadleśnictwach stwierdzono 290 rodzin (Tab. 1). Analizowano 5 typów akwenów: rzeka Czarna Hańcza, Kanał Augustowski, inne rzeki, jeziora i rowy melioracyjne. Największe zagęszczenie bobrów w Puszczy stwierdzono przy ciekach i jeziorach. Z ogólnej liczby 290 rodzin ujawniono 35 rodzin na rowach melioracyjnych. W każdym typie akwenów analizą objęto: położenie żeremi, nor, długość areałów rodzin i wybiorczość siedlisk. Określono w % wykorzystanie brzegów akwenów (Tab. 2) oraz długość brzegu zajętego przez jedną rodzinę (Tab. 3), wybiorczość siedlisk przez bobry (Tab. 4, 5, 6). Ponadto określono liczbę żeremi, nor i gniazd łącznie w rożnych akwenach w poszczególnych nadleśnictwach (Tab. 7), a także ich liczbę przypadającą na jedną rodzinę (Tab. 8). Dane dotyczące rodzin na rowach melioracyjnych przedstawiono w tabelach 9– 11

The FAD-Shielding Residue Phe1395 Regulates Neuronal Nitric-Oxide Synthase Catalysis by Controlling NADP+ Affinity and a Conformational Equilibrium Within the Flavoprotein Domain

Phe1395 stacks parallel to the FAD isoalloxazine ring in neuronal nitric-oxide synthase (nNOS) and is representative of conserved aromatic amino acids found in structurally related flavoproteins. This laboratory previously showed that Phe1395 was required to obtain the electron transfer properties and calmodulin (CaM) response normally observed in wild-type nNOS. Here we characterized the F1395S mutant of the nNOS flavoprotein domain (nNOSr) regarding its physical properties, NADP+ binding characteristics, flavin reduction kinetics, steady-state and pre-steady-state cytochrome c reduction kinetics, and ability to shield its FMN cofactor in response to CaM or NADP(H) binding. F1395S nNOSr bound NADP+ with 65% more of the nicotinamide ring in a productive conformation with FAD for hydride transfer and had an 8-fold slower rate of NADP+ dissociation. CaM stimulated the rates of NADPH-dependent flavin reduction in wild-type nNOSr but not in the F1395S mutant, which had flavin reduction kinetics similar to those of CaM-free wild-type nNOSr. CaM-free F1395S nNOSr lacked repression of cytochrome c reductase activity that is typically observed in nNOSr. The combined results from pre-steady-state and EPR experiments revealed that this was associated with a lesser degree of FMN shielding in the NADP +-bound state as compared with wild type. We conclude that Phe 1395 regulates nNOSr catalysis in two ways. It facilitates NADP + release to prevent this step from being rate-limiting, and it enables NADP(H) to properly regulate a conformational equilibrium involving the FMN subdomain that controls reactivity of the FMN cofactor in electron transfer

Post-transcriptional regulation of the arginine transporter Cat-1 by amino acid availability

The regulation of the high affinity cationic amino acid transporter (Cat-1) by amino acid availability has been studied. In C6 glioma and NRK kidney cells, cat-1 mRNA levels increased 3.8-18-fold following 2 h of amino acid starvation. The transcription rate of the cat-1 gene remained unchanged during amino acid starvation, suggesting a post-transcriptional mechanism of regulation. This mechanism was investigated by expressing a cat-1 mRNA from a tetracycline-regulated promoter. The cat-1 mRNA contained 1.9 kilobase pairs (kb) of coding sequence, 4.5 kb of 3'-untranslated region, and 80 base pairs of 5'-untranslated region. The full-length (7.9 kb) mRNA increased 5-fold in amino acid-depleted cells. However, a 3.4-kb species that results from the usage of an alternative polyadenylation site was not induced, suggesting that the cat-1 mRNA was stabilized by cis-acting RNA sequences within the 3'-UTR. Transcription and protein synthesis were required for the increase in full-length cat-1 mRNA level. Because omission of amino acids from the cell culture medium leads to a substantial decrease in protein synthesis, the translation of the increased cat-1 mRNA was assessed in amino acid-depleted cells. Western blot analysis demonstrated that cat-1 mRNA and protein levels changed in parallel. The increase in protein level was significantly lower than the increase in mRNA level, supporting the conclusion that cat-1 mRNA is inefficiently translated when the supply of amino acids is limited, relative to amino acid-fed cells. Finally, y(+)-mediated transport of arginine in amino acid-fed and -starved cells paralleled Cat-1 protein levels. We conclude that the cat-1 gene is subject to adaptive regulation by amino acid availability. Amino acid depletion initiates molecular events that lead to increased cat-1 mRNA stability. This causes an increase in Cat-1 protein, and y(+) transport once amino acids become availabl