Diversity of European habitat types is correlated with geography more than climate and human pressure

Habitat richness, that is, the diversity of ecosystem types, is a complex, spatially explicit aspect of biodiversity, which is affected by bioclimatic, geographic, and anthropogenic variables. The distribution of habitat types is a key component for understanding broad‐scale biodiversity and for developing conservation strategies. We used data on the distribution of European Union (EU) habitats to answer the following questions: (i) how do bioclimatic, geographic, and anthropogenic variables affect habitat richness? (ii) Which of those factors is the most important? (iii) How do interactions among these variables influence habitat richness and which combinations produce the strongest interactions? The distribution maps of 222 terrestrial habitat types as defined by the Natura 2000 network were used to calculate habitat richness for the 10 km × 10 km EU grid map. We then investigated how environmental variables affect habitat richness, using generalized linear models, generalized additive models, and boosted regression trees. The main factors associated with habitat richness were geographic variables, with negative relationships observed for both latitude and longitude, and a positive relationship for terrain ruggedness. Bioclimatic variables played a secondary role, with habitat richness increasing slightly with annual mean temperature and overall annual precipitation. We also found an interaction between anthropogenic variables, with the combination of increased landscape fragmentation and increased population density strongly decreasing habitat richness. This is the first attempt to disentangle spatial patterns of habitat richness at the continental scale, as a key tool for protecting biodiversity. The number of European habitats is related to geography more than climate and human pressure, reflecting a major component of biogeographical patterns similar to the drivers observed at the species level. The interaction between anthropogenic variables highlights the need for coordinated, continental‐scale management plans for biodiversity conservation.     

GAP-43 mediates retinal axon interaction with lateral diencephalon cells during optic tract formation

GAP-43 is an abundant intracellular growth cone protein that can serve as a PKC substrate and regulate calmodulin availability. In mice with targeted disruption of the GAP-43 gene, retinal ganglion cell (RGC) axons fail to progress normally from the optic chiasm into the optic tracts. The underlying cause is unknown but, in principle, can result from either the disruption of guidance mechanisms that mediate axon exit from the midline chiasm region or defects in growth cone signaling required for entry into the lateral diencephalic wall to form the optic tracts. Results here show that, compared to wild-type RGC axons, GAP-43-deficient axons exhibit reduced growth in the presence of lateral diencephalon cell membranes. Reduced growth is not observed when GAP-43-deficient axons are cultured with optic chiasm, cortical, or dorsal midbrain cells. Lateral diencephalon cell conditioned medium inhibits growth of both wild-type and GAP-43-deficient axons to a similar extent and does not affect GAP-43-deficient axons more so. Removal or transplant replacement of the lateral diencephalon optic tract entry zone in GAP-43-deficient embryo preparations results in robust RGC axon exit from the chiasm. Together these data show that RGC axon exit from the midline region does not require GAP-43 function. Instead, GAP-43 appears to mediate RGC axon interaction with guidance cues in the lateral diencephalic wall, suggesting possible involvement of PKC and calmodulin signaling during optic tract formation.     

Physicochemical aspects of the antiseptic action of nanohydroxyapatite

The mechanism of interaction of nanocrystals of hydroxyapatite with Staphylococcus aureus bacteria has been investigated. It was shown that the growth of bacteria and their colonies both in the presence and absence of hydroxyapatite nanocrystals can be described using the Fokker-Planck equation. It was found that hydroxyapatite nanocrystals adhere in a particular orientation on the surface of bacteria, decreasing substantially their colony-forming ability.     

Proteolytic fragment of protein kinase C (kinase M) phosphorylates in vitro phosphatidylinositol-4-phosphate.

Limited tryptic proteolysis of homogeneous protein kinase C induces the formation of a catalytically active fragment of 50 kDa (kinase M) which, unlike native PK C acquires the ability to phosphorylate PIP. Both ATP and GTP were found to be capable of serving as phosphate donors in this process. Incubation of purified kinase M with a preparation of rat brain membrane fraction enhanced the level of phosphorylation of PIP in the presence and in the absence of exogenous PIP. A scheme of the interrelationship of phosphoinositide metabolism and the proteolytic processing of protein kinase C is proposed.     

Structure-directed discovery of potent non-peptidic inhibitors of human urokinase that access a novel binding subsite

BACKGROUND: Human urokinase-type plasminogen activator has been implicated in the regulation and control of basement membrane and interstitial protein degradation. Because of its role in tissue remodeling, urokinase is a central player in the disease progression of cancer, making it an attractive target for design of an anticancer clinical agent: Few urokinase inhibitors have been described, which suggests that discovery of such a compound is in the early stages. Towards integrating structural data into this process, a new human urokinase crystal form amenable to structure-based drug design has been used to discover potent urokinase inhibitors. RESULTS: On the basis of crystallographic data, 2-naphthamidine was chosen as the lead scaffold for structure-directed optimization. This co-crystal structure shows the compound binding at the primary specificity pocket of the trypsin-like protease and at a novel binding subsite that is accessible from the 8-position of 2-napthamidine. This novel subsite was characterized and used to design two compounds with very different 8-substituents that inhibit urokinase with K(i) values of 30-40 nM. CONCLUSIONS: Utilization of a novel subsite yielded two potent urokinase inhibitors even though this site has not been widely used in inhibitor optimization with other trypsin-like proteases, such as those reported for thrombin or factor Xa. The extensive binding pockets present at the substrate-binding groove of these other proteins are blocked by unique insertion loops in urokinase, thus necessitating the utilization of additional binding subsites. Successful implementation of this strategy and characterization of the novel site provides a significant step towards the discovery of an anticancer clinical agent.     

Cytotoxic action of conjugates of alpha-fetoprotein and epidermal growth factor with photoheme, chlorines, and phthalocyanines

Covalently bound conjugates of alpha-fetoprotein (AFP) and epidermal growth factor (EGF) with photoheme (PH), 3-desvinyl-3-formylchlorine p6 (Chl p6), chlorine e6 (Chl e6), aluminum disulfochloride phthalocyanine (PC(Al)), and cobalt octa-4,5-carboxyphthalocyanine (teraphthal, TP(Co)) were synthesized. Their molar ratios were 1:4 for AFP-cytotoxin conjugates (cf. 1:10 for AFP-TP(Co)) and 1:2 for EGF conjugates (cf. 1:1 for EGF-PC(Al)). Dark toxicity of both protein conjugates with PH, chlorines, and PC(Al) was much lower than their phototoxicity. Studies on phototoxicity demonstrated that PC(Al) conjugates with AFP and EGF and also EGF-Chl p6 were the most effective. The cytotoxic activity (CTA) of AFP-PC(Al) and EGF-Chl p6 was 80% and of EGF-PC(Al) 64% higher than the CTA of the free drugs. Conjugates with TP(Co) were much more toxic on their activation with ascorbic acid (AA): in the presence of AA the CTA of AFP-TP(Co) and of EGF-TP(Co) was 19 and 61.1% higher, respectively, than the CTA of the free TP(Co).     

Separation of abnormal cell wall composition from penicillin resistance through genetic transformation of Streptococcus pneumoniae.

Compared with most penicillin-susceptible isolates of Streptococcus pneumoniae, penicillin-resistant clinical isolate Hun 663 contains mosaic penicillin-binding protein (PBP) genes encoding PBPs with reduced penicillin affinities, anomalous molecular sizes, and also cell walls of unusual chemical composition. Chromosomal DNA prepared from Hun 663 was used to transform susceptible recipient cells to donor level penicillin resistance, and a resistant transformant was used next as the source of DNA in the construction of a second round of penicillin-resistant transformants. The greatly reduced penicillin affinity of the high-molecular-weight PBPs was retained in all transformants through both genetic crosses. On the other hand, PBP pattern and abnormal cell wall composition, both of which are stable, clone-specific properties of strain Hun 663, were changed: individual transformants showed a variety of new, abnormal PBP patterns. Furthermore, while the composition of cell walls resembled that of the DNA donor in the first-round transformants, it became virtually identical to that of susceptible pneumococci in the second-round transformants. The findings indicate that genetic elements encoding the low affinity of PBPs and the penicillin resistance of the bacteria are separable from determinants that are responsible for the abnormal cell wall composition that often accompanies penicillin resistance in clinical strains of pneumococci.     

Mechanism of action of cAMP-dependent protein kinase. V. Free energy spectra

The catalytic subunit of cAMP-dependent protein kinase from pig brain was shown to catalyse an isotope exchange reaction ATP in equilibrium with ADP. The kinetic parameters of the exchange were determined. The enzyme can also use GTP as the donor substrate; phosphotransferase and "GTPase" reactions were investigated. Based on the kinetic data obtained in this and in the previous paper the free energy profiles of protein kinase catalysed reactions are discussed.