Contact guidance of Walker carcinosarcoma cells by the underlying normal fibroblasts is inhibited by RGD-containing synthetic peptides

The metastatic spread of malignant neoplasms is associated with active migration of cancer cells. The migration of neoplastic cells during the metastatic process may be affected by various extracellular factors, including chemoattractants, haptotactic signals, electric fields, substrate anisotropy, and cell-to-cell contacts. We examined the effect of homotypic collisions and heterotypic interactions with normal human skin fibroblasts on the motile activity of Walker carcinosarcoma cells. It was found that Walker carcinosarcoma cells moving in a dense population neither show contact inhibition of movement when colliding with one another nor increase their motile activity as a result of contact stimulation of motility. On the other hand, when plated onto the surface of aligned fibroblasts, Walker carcinosarcoma cells migrated mainly along the long axes of underlying fibroblasts as a result of contact guidance. The directional character of movement (but not the speed of migration) of Walker carcinosarcoma cells on the surface of aligned fibroblasts was completely effaced by RGD-containing synthetic peptide at a concentration of 1 mg/ml but not by 5 microM verapamil (selective voltage-gated calcium channel inhibitor) or 10 microM gadolinium chloride (non-specific blocker of mechanosensitive ion channels). The suppression of directional character of migration of tumour cells by RGD-containing peptide was associated with the decrease in the amount of fibronectin macromolecules attached to fibroblasts. This suggests that alignment and anisotropic distribution of fibronectin macromolecules may be responsible for contact guidance of tumour cells moving on the surface of fibroblasts.     

The ParB protein of Streptomyces coelicolor A3(2) recognizes a cluster of parS sequences within the origin-proximal region of the linear chromosome

The mycelial prokaryote Streptomyces coelicolor A3(2) possesses a large linear chromosome (8.67 Mb) with a centrally located origin of replication (oriC). Recently, chromosome partitioning genes (parA and parB) and putative ParB binding sites (parS sequences) were identified in its genome. The S. coelicolor chromosome contains more parS sequences than any other bacterial chromosome characterized so far. Twenty of the 24 parS sequences are densely packed within a relatively short distance (approximately 200 kb) around oriC. A series of in vitro and in vivo experiments showed that S. coelicolor ParB protein interacts specifically with the parS sequences, albeit with a rather low affinity. Our results suggested that the binding of ParB is not only determined by the parS sequence, but also by the location of target DNA close to oriC. The unusually high number and close proximity to each other of the parS sites, together with in vivo and in vitro evidence that multiple ParB molecules may assemble along the DNA from an initial ParB-parS complex, suggest that a large DNA segment around the replication origin may form a massive nucleoprotein complex as part of the replication-partitioning cycle.     

Ex vivo apoptotic potential of peripheral blood mononuclear cells of the elderly human subject

Studies of immunosenescence have led to a detailed knowledge of immune system dysfunctions in the ageing human being. Apoptosis seems to be one of the process regulating an immune response after the antigenic stimulation. We examined whether commonly used methods of assessing apoptosis in the elderly human subject produce comparable results to young subjects. PBMC of young and elderly volunteers were isolated from the venous blood and cultured for 6 or 24 h with antigens of anti-influenza vaccine or PMA. The intensity of apoptosis was measured using the annexinV test, flow cytometric evaluation of DNA content (sub-G1 peak in DNA histograms), 'ladder' by DNA gel electrophoresis, and fluorescence microscope. Apoptosis in 6 h-lasting cultures of the elderly was more intense in annexinV test, while it was decreased assessing subG1 peak. Additionally, in the aged group, those changes were associated with cell cycle arrest. Our results suggest that the apoptosis after the stimulation with the vaccine antigens seems to be some kind of activation-induced cell death (AICD). Different patterns of apoptosis after stimulation may be associated with the cell cycle arrest of the PBMC in the elderly.     

Binding abilities of dehydropeptides towards Cu(II) and Ni(II) ions. Impact of Z-E isomerization on metal ion binding

The study on the binding ability of dehydro-tri- and tetrapeptides has shown that the ,β-double bond has a critical effect on the peptide coordination to metal ions. It may affect the binding of the vicinal amide nitrogens by the electronic effect and stabilize the complex due to steric effects. The (Z) isomer is the most effective in stabilizing of the complexes formed. The presence of large side chain in the dehydroamino acid residue may also be critical for the coordination mode in the metallopeptide systems.     

Inhibition of the D-fructose transporter protein GLUT5 by fused-ring glyco-1,3-oxazolidin-2-thiones and -oxazolidin-2-ones

The glucose transporter 5 (GLUT5)-a specific D-fructose transporter-belongs to a family of facilitating sugar transporters recently enlarged by the human genome sequencing. Prompted by the need to develop specific photolabels of these isoforms, we have studied the interaction of conformationally locked D-fructose and L-sorbose derived 1,3-oxazolidin-2-thiones and 1,3-oxazolidin-2-ones to provide a rational basis for an interaction model. The inhibition properties of the D-fructose transporter GLUT5 by glyco-1,3-oxazolidin-2-thiones and glyco-1,3-oxazolidin-2-ones is now reported. In vitro, the fused-rings systems tested showed an efficient inhibition of GLUT5, thus bringing new insights on the interaction of D-fructose with GLUT5.     

A dual layer hair array of the brown lacewing: repelling water at different length scales

Additional weight due to contamination (water and/or contaminating particles) can potentially have a detrimental effect on the flight capabilities of large winged insects such as butterflies and dragonflies. Insects where the wing surface area-body mass ratio is very high will be even more susceptible to these effects. Water droplets tend to move spontaneously off the wing surface of these insects. In the case of the brown lacewing, the drops effectively encounter a dual bed of hair springs with a topographical structure which aids in the hairs resisting penetration into water bodies. In this article, we demonstrate experimentally how this protective defense system employed by the brown lacewing (Micromus tasmaniae) aids in resisting contamination from water and how the micro- and nanostructures found on these hairs are responsible for quickly shedding water from the wing which demonstrates an active liquid-repelling surface.     

Antimicrobial and antioxidative potential of free and immobilised cellobiose dehydrogenase isolated from wood degrading fungi

Cellobiose dehydrogenase (CDH, EC 1.1.99.18) is a glycoprotein having many biotechnological applications. In the present study, CDHs isolated from Phlebia lindtneri (PlCDH), Phanerochaete chrysosporium (PchCDH), Cerrena unicolor (CuCDH), and Pycnoporus sanguineus (PsCDH) were studied the first time for their ability to generate antioxidant and antimicrobial agents. The aim of the research was to evaluate the antioxidant and antimicrobial activity of systems composed of four CDHs and lactose or cellobiose as a reaction substrate. The free radical scavenging effect of free and immobilised enzymes was evaluated using the DPPH method. The lowest values of EC₅₀ (10.04 ± 0.75 $\text{μg}$/ml) was noted for PlCDH/lactose and for PlCDH/cellobiose (12.06 ± 1.35 $\text{μg}$/ml). The EC₅₀value reached 12.6 ± 1.51 $\text{μg}$/ml in the case of PsCDH/lactose and 15.96 ± 1.35 for PsCDH. The CDH preparations were also effectively immobilised in alginate (the immobilisation efficiency expressed as a protein yield ranged from 61.6 to 100 %). The operational stability expressed as a scavenging effect showed the possibility of using the alginate beads 4 times. Both the free and immobilised CDHs as well as the CDH/substrate were tested against Gram-negative Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Gram-positive Staphylococcus aureus ATCC 25923 bacteria. All samples, except PlCDH, were potentially effective in suppression of bacterial growth. The highest percentage of inhibition (100 %) was obtained for S. aureus bacteria using PsCDH and PchCDH with lactose as a substrate, whereas a slightly lesser effect was observed for E. coli and P. aeruginosa bacterial cells, i.e. 64.1 % and 86.5 % (PsCDH) and 94.1 % and 41.4 % (PchCDH), respectively. Furthermore, the concentrations of the reaction products (aldonic acids and hydrogen peroxide) were quantified and the surface morphology of the alginate beads was analysed using SEM visualisation.