Ground beetle (Coleoptera, Carabidae) assemblages inhabiting Scots pine stands of Puszcza Piska Forest: six-year responses to a tornado impact

Ground beetle assemblages were studied during 2003-08 in the Pisz Forest by comparing stands disturbed by a tornado to undisturbed control stands. The following exploratory questions were put forward. (1) How do the carabid assemblages change during six years following the tornado impact? (2) Does the carabid assemblage recovery begin during the six first post-tornado years? To assess the state of carabid assemblages we used two indices: the MIB (Mean Individual Biomass) and the SPC (Sum of Progressive Characteristics). Carabid assemblages in the disturbed and in the control stands, as expressed by these two indices, were compared using the length of a regression distance (sample distance in a MIB:SPC coordinate system). A cluster analysis revealed that the assemblages of the disturbed and the control stands were different. The tornado-impacted stands produced lower carabid catch rates, but species richness was significantly higher there than in the control stands. They hosted lower proportions of individuals of European species, of large zoophages, and of forest and brachypterous species, than the control stands. The observed reduction in SPC and MIB, and an increase in the regression distances may indicate that the carabid assemblages had not started to recover from the tornado-caused disturbance. Carabid assemblages apparently responded to the tornado in two steps. Firstly, the first three years were characterized by moderate decreases of index values. Secondly, from the fourth to the sixth year after the tornado, many observed changes became magnified. We did not observe clear signals of the recovery of forest carabid assemblages during the six follow-up years.     

Liver-specific Commd1 knockout mice are susceptible to hepatic copper accumulation

Canine copper toxicosis is an autosomal recessive disorder characterized by hepatic copper accumulation resulting in liver fibrosis and eventually cirrhosis. We have identified COMMD1 as the gene underlying copper toxicosis in Bedlington terriers. Although recent studies suggest that COMMD1 regulates hepatic copper export via an interaction with the Wilson disease protein ATP7B, its importance in hepatic copper homeostasis is ill-defined. In this study, we aimed to assess the effect of Commd1 deficiency on hepatic copper metabolism in mice. Liver-specific Commd1 knockout mice (Commd1(Δhep)) were generated and fed either a standard or a copper-enriched diet. Copper homeostasis and liver function were determined in Commd1(Δhep) mice by biochemical and histological analyses, and compared to wild-type littermates. Commd1(Δhep) mice were viable and did not develop an overt phenotype. At six weeks, the liver copper contents was increased up to a 3-fold upon Commd1 deficiency, but declined with age to concentrations similar to those seen in controls. Interestingly, Commd1(Δhep) mice fed a copper-enriched diet progressively accumulated copper in the liver up to a 20-fold increase compared to controls. These copper levels did not result in significant induction of the copper-responsive genes metallothionein I and II, neither was there evidence of biochemical liver injury nor overt liver pathology. The biosynthesis of ceruloplasmin was clearly augmented with age in Commd1(Δhep) mice. Although COMMD1 expression is associated with changes in ATP7B protein stability, no clear correlation between Atp7b levels and copper accumulation in Commd1(Δhep) mice could be detected. Despite the absence of hepatocellular toxicity in Commd1(Δhep) mice, the changes in liver copper displayed several parallels with copper toxicosis in Bedlington terriers. Thus, these results provide the first genetic evidence for COMMD1 to play an essential role in hepatic copper homeostasis and present a valuable mouse model for further understanding of the molecular mechanisms underlying hepatic copper homeostasis.     

The role of intracellular cAMP in renal gluconeogenesis in view of differential action of various cAMP analogues

Effects of various cAMP analogues on gluconeogenesis in isolated rabbit kidney tubules have been investigated. In contrast to N(6),2'-O-dibutyryladenosine-3',5'-cyclic monophosphate (db-cAMP) and cAMP, which accelerate renal gluconeogenesis, 8-bromoadenosine-3',5'-cyclic monophosphate (Br-cAMP) and 8-(4-chlorophenylthio)-cAMP (pCPT-cAMP) inhibit glucose production. Stimulatory action of cAMP and db-cAMP may be evoked by butyrate and purinergic agonists generated during their extracellular and intracellular metabolism resulting in an increase in flux through fructose-1,6-bisphosphatase and in consequence acceleration of the rate of glucose formation. On the contrary, Br-cAMP is poorly metabolized in renal tubules and induces a fall of flux through glyceraldehyde-3-phosphate dehydrogenase. The contribution of putative extracellular cAMP receptors to the inhibitory Br-cAMP action is doubtful in view of a decline of glucose formation in renal tubules grown in the primary culture supplemented with forskolin. The presented data indicate that in contrast to hepatocytes, in kidney-cortex tubules an increased intracellular cAMP level results in an inhibition of glucose production.     

The inhibitor protein of the F1F0-ATP synthase is associated to the external surface of endothelial cells

The ATPase inhibitor protein (IP) of mitochondria was detected in the plasma membrane of living endothelial cells by flow cytometry, competition assays, and confocal microscopy of cells exposed to IP antibodies. The plasma membranes of endothelial cells also possess beta-subunits of the mitochondrial ATPase. Plasma membranes have the capacity to bind exogenous IP. TNF-alpha decreases the level of beta-subunits and increases the amount of IP, indicating that the ratio of IP to beta-subunit exhibits significant variations. Therefore, it is probable that the function of IP in the plasma membrane of endothelial cells is not limited to regulation of catalysis.     

Circular dichroism and aggregation studies of amyloid beta (11-8) fragment and its variants

Aggregation of Abeta peptides is a seminal event in Alzheimer's disease. Detailed understanding of Abeta assembly would facilitate the targeting and design of fibrillogenesis inhibitors. Here comparative conformational and aggregation studies using CD spectroscopy and thioflavine T fluorescence assay are presented. As a model peptide, the 11-28 fragment of Abeta was used. This model peptide is known to contain the core region responsible for Abeta aggregation. The structural and aggregational behaviour of the peptide was compared with the properties of its variants corresponding to natural, clinically relevant mutants at positions 21-23 (A21G, E22K, E22G, E22Q and D23N). In HFIP (hexafluoro-2-propanol), a strong alpha-helix inducer, the CD spectra revealed an unexpectedly high amount of beta-sheet conformation. The aggregation process of Abeta(11-28) variants provoked by water addition to HFIP was found to be consistent with a model of an alpha-helix-containing intermediate. The aggregation propensity of all Abeta(11-28) variants was also compared and discussed.     

Activity of oil-formulated conidia of the fungal entomopathogens Nomuraea rileyi and Isaria tenuipes against lepidopterous larvae

The fungi Nomuraea rileyi and Isaria tenuipes (=Paecilomyces tenuipes) are ecologically obligate, widespread pathogens of lepidopterans. Bioassays were carried out to evaluate the activity of oil-suspended conidia of N. rileyi and I. tenuipes against larvae of Spodoptera frugiperda, Spodoptera exigua, Helicoverpa zea, and Heliothis virescens. The tests consisted of two bioassay sets. In the first set, conidia of N. rileyi and I. tenuipes were suspended in water + Tween 80, and in vegetable (canola, soybean) and mineral (proprietary mixture of alkanes and cyclic paraffins) oils, and tested against S. frugiperda. Both fungi were highly compatible with oils and caused mortalities near 100% in all oil treatments; the lowest LT₅₀ values were 4.7 days for N. rileyi in mineral oil and 6.0 days for I. tenuipes in soybean oil. The second set included additional fungal strains and oil formulations (mineral, canola, sunflower, olive and peanut oils) tested against larvae of S. exigua, S. frugiperda, H. zea and H. virescens. The highest activity was that of N. rileyi in mineral oil against Spodoptera spp., with LT₅₀ values of 2.5 days (strain ARSEF 135) and 3 days (strain ARSEF 762) respectively. For two different isolates of I. tenuipes the lowest LT₅₀ values (5.1-5.6 days respectively) were obtained with mineral oil formulations against Spodoptera spp. and H. zea respectively. Additionally, we tested both fungi against prepupae of all four lepidopteran species. Mortalities with I. tenuipes against S. exigua ranged from 90% to 100% (strains ARSEF 2488 and 4096); N. rileyi caused 95% mortality on S. frugiperda. The activity of formulations depended on host species and oil used; Spodoptera spp. was more susceptible to these fungi than Heliothis and Helicoverpa. The results indicate that a comprehensive evaluation of these entomopathogens in agriculture using oil application technologies is advisable, particularly, in organic and sustainable settings.     

Bcl-2 changes conformation to inhibit Bax oligomerization

Bcl-2 inhibits apoptosis by regulating the release of cytochrome c and other proteins from mitochondria. Oligomerization of Bax promotes cell death by permeabilizing the outer mitochondrial membrane. In transfected cells and isolated mitochondria, Bcl-2, but not the inactive point mutants Bcl-2-G145A and Bcl-2-V159D, undergoes a conformation change in the mitochondrial membrane in response to apoptotic agonists such as tBid and Bax. A mutant Bcl-2 with two cysteines introduced at positions predicted to result in a disulfide bond that would inhibit the mobility of alpha5-alpha6 helices (Bcl-2-S105C/E152C) was only active in a reducing environment. Thus, Bcl-2 must change the conformation to inhibit tBid-induced oligomerization of integral membrane Bax monomers and small oligomers. The conformationally changed Bcl-2 sequesters the integral membrane form of Bax. If Bax is in excess, apoptosis resumes as Bcl-2 is consumed by the conformational change and in complexes with Bax. Thus, Bcl-2 functions as an inhibitor of mitochondrial permeabilization by changing conformation in the mitochondrial membrane to bind membrane-inserted Bax monomers and prevent productive oligomerization of Bax.