A long‐term record of Quercus decline,logging and fires in a southern Swedish Fagus‐Picea forest

Abstract. We reconstructed forest development and disturbance events (fire and logging) during the last 1000 yr with tree‐ring data, pollen and charcoal analysis from a semi‐natural Fagus sylvatica‐Picea abies forest (ca. 1 km²) in the hemiboreal zone. According to pollen analysis, Quercus robur together with Pinus sylvestris was abundant in the forest until the turn of the 18th/19th centuries when these species disappeared completely (Quercus) or nearly completely (Pinus) and were replaced by Fagus and Picea. The disappearance of Quercus was corroborated by the remarkable discovery of a single Quercus stump that had been cut in the 18th century and had become overgrown and preserved by a very old Picea. In total 11 fires were dated from 1555 to 1748 from fire scars in several Pinus stumps cut 100 ‐ 200 yr ago. Since the last fire in 1748, no Quercus or Pinus have regenerated in the core of the reserve apart from single pines in neighbouring managed forest (80 yr ago). During the period of documented fires Fagus was protected from fires in a refuge made up of large boulders. Picea colonized the region at the time when the fires ceased 250 yr ago. We hypothesize that most of the fires were probably of human origin because of their patchiness and high frequency compared to the natural background levels of lightning ignitions in the region. On a 300‐yr time scale, logging and fire suppression seem to strongly overshadow the effect of climate change on forest composition and dynamics.     

Protein mediated glycolipid transfer is inhibited FROM sphingomyelin membranes but enhanced TO sphingomyelin containing raft like membranes

The mammalian glycolipid transfer protein, GLTP, catalyzes the transfer in vitro of glycolipids between membranes. In this study we have examined on one hand the effect of the variations in the donor vesicle composition and on the other hand the effects of variations in the acceptor vesicle composition on the GLTP-catalyzed transfer kinetics of galactosylceramide between bilayer vesicles. For this purpose a resonance energy transfer assay was used, the energy donor being anthrylvinyl-galactosylceramide and the energy acceptor DiO-C₁₆. First, we show that the transfer of anthrylvinyl-galactosylceramide from palmitoyl-oleoyl-phosphatidylcholine donor vesicles was faster than from dipalmitoyl-phosphatidylcholine vesicles, and that there is no transfer from palmitoyl-sphingomyelin vesicles regardless of the cholesterol amount. In this setup the acceptor vesicles were always 100% palmitoyl-oleoyl-phosphatidylcholine. We also showed that the transfer in general is faster from small highly curved vesicles compared to that from larger vesicles. Secondly, by varying the acceptor vesicle composition we showed that the transfer is faster to mixtures of sphingomyelin and cholesterol compared to mixtures of phosphatidylcholines and cholesterol. Based on these experiments we conclude that the GLTP mediated transfer of anthrylvinyl-galactosylceramide is sensitive to the matrix lipid composition and membrane bending. We postulate that a tightly packed membrane environment is most effective in preventing GLTP from accessing its substrates, and cholesterol is not required to protect the glycosphingolipid in the membrane from being transferred by GLTP. On the other hand GLTP can more easily transfer glycolipids to ‘lipid raft’ like membranes, suggesting that the protein could be involved in raft assembly.     

Synthesis and evaluation of Hsp90 inhibitors that contain the 1,4-naphthoquinone scaffold

High-throughput screening of a library of diverse molecules has identified the 1,4-naphthoquinone scaffold as a new class of Hsp90 inhibitors. The synthesis and evaluation of a rationally-designed series of analogues containing the naphthoquinone core scaffold has provided key structure–activity relationships for these compounds. The most active inhibitors exhibited potent in vitro activity with low micromolar IC₅₀ values in anti-proliferation and Her2 degradation assays. In addition, 3g, 12, and 13a induced the degradation of oncogenic Hsp90 client proteins, a hallmark of Hsp90 inhibition. The identification of these naphthoquinones as Hsp90 inhibitors provides a new scaffold upon which improved Hsp90 inhibitors can be developed.     

Regional stiffening of the mitral valve anterior leaflet in the beating ovine heart

Left atrial muscle extends into the proximal third of the mitral valve (MV) anterior leaflet and transient tensing of this muscle has been proposed as a mechanism aiding valve closure. If such tensing occurs, regional stiffness in the proximal anterior mitral leaflet will be greater during isovolumic contraction (IVC) than isovolumic relaxation (IVR) and this regional stiffness difference will be selectively abolished by β-receptor blockade. We tested this hypothesis in the beating ovine heart. Radiopaque markers were sewn around the MV annulus and on the anterior MV leaflet in 10 sheep hearts. Four-dimensional marker coordinates were obtained from biplane videofluoroscopy before (CRTL) and after administration of esmolol (ESML). Heterogeneous finite element models of each anterior leaflet were developed using marker coordinates over matched pressures during IVC and IVR for CRTL and ESML. Leaflet displacements were simulated using measured left ventricular and atrial pressures and a response function was computed as the difference between simulated and measured displacements. Circumferential and radial elastic moduli for ANNULAR, BELLY and EDGE leaflet regions were iteratively varied until the response function reached a minimum. The stiffness values at this minimum were interpreted as the in vivo regional material properties of the anterior leaflet. For all regions and all CTRL beats IVC stiffness was 40–58% greater than IVR stiffness. ESML reduced ANNULAR IVC stiffness to ANNULAR IVR stiffness values. These results strongly implicate transient tensing of leaflet atrial muscle during IVC as the basis of the ANNULAR IVC–IVR stiffness difference.     

Differential Cell Counting in Fraction-Collected Milk from Dairy Cows

Cell con-centrations and cell populations were studied in fraction-collected milk by use of cytofluorometric methods. The results indicate differences in the condition of udders producing milk with more and less than 100 000 cells per ml, respectively     

Interactions of the heme-regulated eIF-2 alpha kinase with heat shock proteins in rabbit reticulocyte lysates.

Inhibition of protein synthesis in rabbit reticulocyte lysates occurs in response to a variety of conditions including heme deficiency, addition of oxidants, and heat stress. The inhibition of translation is due to the activation of a heme-regulated protein kinase (HRI) which specifically phosphorylates the alpha-subunit of the eukaryotic initiation factor eIF-2. In this report, immunoadsorption with monoclonal antibodies (mAbs) and Western blot analysis were used to investigate the interaction of HRI, the 90-kDa heat shock protein (hsp 90), hsp 70, and the EC1 antigen in rabbit reticulocyte lysates under protein synthesizing conditions. The data indicate that hsp 90, hsp 70, and the EC1 antigen interact with HRI in rabbit reticulocyte lysate. The EC1 antigen is a protein that has been demonstrated to be associated with several steroid hormone receptor-hsp 90 complexes and reacts with the KN 382/EC1 mAb (EC1). The association of HRI with hsp 90 and the EC1 antigen in the reticulocyte lysate was found to be dependent on the presence of hemin at a concentration of 5 microM or higher; little HRI was coadsorbed by the 8D3 anti-hsp 90 mAb or the EC1 mAb in the absence of hemin. Hsp 70 remains associated with HRI in the absence of hemin, suggesting that hsp 90 and 70 may bind to HRI at different sites. The immunological properties of the hsp 70 associated with HRI indicate that it may be the constitutively express heat shock cognate protein (hsc 73). The results suggest that the association of HRI with hsp 90 and the EC1 antigen may be in a dynamic equilibrium, in which complex formation is either facilitated or stabilized by the presence of hemin, and supports the notion that these proteins in conjunction with hsp 70 may play a role in regulating HRI activity or activation in situ.