Abundance of two threatened woodpecker species in relation to the proportion of spruce plantations in native pine forests of western Norway

In a comparative study we investigated woodpecker abundance in forest landscapes with different proportion of native pine forest and spruce plantations in western Norway. In 100 circular study plots of 100ha each we recorded 38 white-backed –Dendrocopos leucotos, 22 grey-headed –Picus canus, 13 great spotted –Dendrocopos major, 6 green –Picus viridis, and 2 lesser spotted –Dendrocopos minor woodpeckers in the breeding season. The mean number of recorded woodpecker species peaked at 20–40% spruce plantations. The two most common species in the study, the white-backed and the grey-headed woodpeckers are both Red-listed species in Norway and among the rarest woodpeckers in Europe. The white-backed woodpecker preferred plots with higher than average proportions of standing dead trees and deciduous trees, and low proportions of spruce plantations in the plots. The grey-headed woodpecker preferred plots in the western (coastal) parts of the study area with presence of large aspen Populus tremula trees. Logistic regression models did not reveal any clear threshold values with respect to proportion of spruce plantations in plots, although both woodpecker species were extremely rare in plots with >60% spruce plantations. We recommend spruce plantations to be kept at moderate levels to ensure viable populations of woodpeckers in western Norway.     

Mechanisms and significance of bifunctional NK4 in cancer treatment

Based on the background that hepatocyte growth factor (HGF) and c-Met/HGF receptor tyrosine kinase play a definite role in tumor invasion and metastasis, NK4, four-kringles containing intramolecular fragment of HGF, was isolated as a competitive antagonist for the HGF-c-Met system. Independent of its HGF-antagonist action, NK4 inhibited angiogenesis induced by vascular endothelial cell growth factor and basic fibroblast growth factor, as well as HGF, indicating that NK4 is a bifunctional molecule that acts as an HGF-antagonist and angiogenesis inhibitor. Interestingly, kringle domains in distinct types of proteins, e.g., plasminogen, prothrombin, plasminogen activators, apolipoprotein(a), and HGF, share angioinhibitory actions. In experimental models of distinct types of cancers, NK4 protein administration or NK4 gene therapy inhibited tumor invasion, metastasis, and angiogenesis-dependent tumor growth. Cancer treatment with NK4 may prove to suppress malignant tumors to be 'static' in both tumor growth and spreading, as based on biological characteristics of malignant tumors.     

A secreted form of P-cadherin is expressed in malignant melanoma

Cadherins are Ca-dependent homophilic cell-cell adhesion molecules which are responsible for correct location of cells and tissue integrity. They are critical for development and maintenance of epithelial architecture. Aberrantly expressed cadherins are known to be involved in malignant transformation of different types of tissues. In this study, we show the expression of a short truncated 50 kDa form of the N-terminal part of P-cadherin in seven melanoma cell lines compared to melanocytes and keratinocytes. In vitro protein analysis on cell culture supernatant as well as immunohistochemistry of primary and metastatic melanoma tissue revealed the expression of this short form of P-cadherin. Furthermore, analysis showed that this short 50 kDa form of P-cadherin is secreted by melanoma cells in contrast to the membrane bound form in melanocytes. Analysis on mRNA level detected only exon 1 to 10 of P-cadherin resulting in the 50 kDa form missing the transmembrane and cytoplasmatic region. Genomic sequence analysis did not show any mutations in melanoma cells neither in the exons nor in the exon-intron boundaries. Furthermore, there was no loss of exons 11-16 on the genomic level. Functionally, the secreted form of P-cadherin could play a role as regulator of the homophilic interaction between P-cadherin molecules by antagonizing their biological role acting as a dominant negative form to interrupt cell-cell attachment.     

The physical resistance of grass patches to invasion

One of the important factors determining success in plant competition is the ability of a plant to extend laminae in order to capture resources.To do this in mixed swards the laminae of one plant must first grow into the volume that contains laminae of another. The ability of laminae to overcome the resistance presented by a neighbour, and the ability to resist this ingress, was examined for the grasses Agrostis capillaris, Festuca rubra, Holcus lanatus, Lolium perenne and Poa trivialis that were subject to 3 cm and 6 cm cutting treatments. These abilities were inferred from the behaviour of ‘indicator ’ leaves as they were pushed into monoculture target patches of each species. The 3 cm treatment resisted ingress significantly more than the 6 cm. Species patches differed significantly both in their ability to resist the ingress by the indicator species and in the ability of different indicator species to penetrate the target swards. These effects were still present when differences in leaf density (leaves cm^–2) had been taken into account. The results suggest that grasses can vary in the physical resistance that they present to the leaves of an invading neighbour.     

Air-liquid interface promotes invasive growth of laryngeal squamous cell carcinoma with or without hypoxia

Air-liquid interface (ALI) is a microenvironment of aerodigestive tract. In our previous study, ALI promoted invasive growth of laryngeal squamous cell carcinoma (SCC); but its mechanism was unclear. Hypoxia is also related to cancer spread. Here we show that ALI with or without hypoxia accelerated invasive growth of laryngeal SCC cells, using collagen gel invasion assay. Submerged condition (SMC) without ALI did not induce the invasion with or without hypoxia. ALI enhanced expression of the following growth-, invasion-, and motility-related molecules in the cells with or without hypoxia more greatly than SMC: c-Met, Ras, mitogen-activated protein kinase cascade proteins (Raf-1, MEK-1, and ERK-1/2), matrix metalloproteinase-1, and filamin A. The data indicate that ALI promotes invasive growth of SCC cells by enhancement of the invasive growth-related molecules above, through mechanisms that differ from hypoxia, suggesting that ALI microenvironment should be taken into account for the study of cancer biology.     

Invasion success of Fibrillanosema crangonycis, n.sp., n.g.: a novel vertically transmitted microsporidian parasite from the invasive amphipod host Crangonyx pseudogracilis

Parasitism is known to be an important factor in determining the success of biological invasions. Here we examine Crangonyx pseudogracilis, a North American amphipod invasive in the United Kingdom and describe a novel microsporidium, Fibrillanosema crangonycis n.sp., n.g. The primary site of infection is the female gonad and the parasite is transovarially transmitted to the eggs. PCR screening reveals a female bias in the distribution of parasites (96.6% of females, N=29; 22.2% of males, N=27), which is indicative of host sex ratio distortion. The morphological and molecular characterisations of this new microsporidium place it outside all currently established genera. On the basis of these differences, we erect the new genus Fibrillanosema n.g. While F. crangonycis is morphologically identical to uncharacterised microsporidia from populations of North American amphipods, it is distinct from microsporidia found in European populations of amphipods. These data support the hypothesis that vertically transmitted parasites may be selectively retained during invasion events. Furthermore where vertical transmission is combined with host sex ratio distortion these parasites may directly enhance host invasion success through increased rates of population growth.     

Inhibition of pancreatic adenocarcinoma cellular invasiveness by blebbistatin: a novel myosin II inhibitor

Blebbistatin is a novel 1-phenyl-2-pyrrolidinone derivative capable of inhibiting non-muscle myosin II activity with a high degree of specificity. We examined the effects of blebbistatin on pancreatic adenocarcinoma cellular migration, invasion, adhesion, and spreading. Blebbistatin dose-dependently inhibited cellular migration and invasiveness, quantified by modified Boyden chamber assay. Matrix metalloproteinase 2 and 9 activities were unaffected by blebbistatin and cellular proliferation was inhibited only by concentrations of blebbistatin exceeding those required to inhibit myosin II activity and to interfere with migration and invasion. While blebbistatin treatment did not affect cell adhesion to the extracellular matrix component fibronectin, it markedly impaired cell spreading on this substrate. Cell surface expression of the archetypal fibronectin receptor (alpha(5)beta(1) integrin) was unaffected by blebbistatin. Our observations illustrate the critical role of non-muscle myosin II in pancreatic adenocarcinoma cellular invasiveness and extracellular matrix interaction and suggest that therapeutic strategies targeting myosin II warrant further investigation.     

Multidrug-resistant tumor cells with decreased malignancy: a role for integrin alphavbeta3

We studied whether acquisition of multidrug resistance (MDR) by tumor cells can alter their integrin profile and malignant behavior. Hamster fibroblast cell line HET-SR-2SC-LNM was selected for MDR, yielding the 2SC/20 subline. Compared with the parental cells, the 2SC/20 subline weakly adhered to denatured collagen (dCol) which correlated with decreased expression of alphavbeta3, a dCol receptor. Importantly, 2SC/20 subline demonstrated significantly decreased activity of collagenase MMP-2, lower ability to invade Matrigel, and attenuated metastasis in syngeneic animals. We provide evidence for the first time that selection for MDR can be associated with down-regulation of alphavbeta3 integrin, supporting our recent proof of the pro-apoptotic role of this integrin (Oncogene 20 (2001) 4710). Lack of alphavbeta3 expression may link cell survival under toxic conditions with decreased malignancy of the resulting drug resistant tumor.     

Characterization of the calcium-binding sites of Listeria monocytogenes InlB

The Listeria monocytogenes protein InlB promotes invasion of mammalian cells through activation of the receptor tyrosine kinase Met. The InlB N-cap, a approximately 40 residue part of the domain that binds Met, was previously observed to bind two calcium ions in a novel and unusually exposed manner. Because subsequent work raised questions about the existence of these calcium-binding sites, we assayed calcium binding in solution to the InlB N-cap. We show that calcium ions are bound with dissociation constants in the low micromolar range at the two identified sites, and that the sites interact with one another. We demonstrate that the calcium ions are not required for structure, and also find that they have no appreciable effect on Met activation or intracellular invasion. Therefore, our results indicate that the sites are fortuitous in InlB, but also suggest that the simple architecture of the sites may be adaptable for protein engineering purposes.