Anti-adhesive properties of fish tropomyosins

Aims:  We have recently found that preconditioning of stainless steel surfaces with an aqueous fish muscle extract can significantly impede bacterial adhesion. The purpose of this study was to identify and characterize the primary components associated with this bacteria-repelling effect.
Methods and Results:  The anti-adhesive activity was assayed against Escherchia coli K-12, and bacterial adhesion was quantified by crystal violet staining and sonication methods. Proteolytic digestion, elution and fractionation experiments revealed that the anti-adhesive activity of the extract was linked to the formation of a proteinaceous conditioning film composed primarily of fish tropomyosins. These fibrous proteins formed a considerable anti-adhesive conditioning layer on and reduced bacterial adhesion to several different materials including polystyrene, vinyl plastic, stainless steel and glass. The protein adsorption profiles obtained from the various materials did not differ significantly, but elution was often incomplete making minor qualitative/quantitative differences indiscernible.
Conclusions:  The data highlights the significance of protein conditioning films on bacterial adhesion and emphasizes the importance of substratum's physiochemical properties and exposure time with regards to protein adsorption/elution efficiency and subsequent bacterial adhesion.
Significance and Impact of the Study:  Fish tropomyosin-coatings could potentially offer a nontoxic and relatively inexpensive measure of reducing bacterial colonization of inert surfaces.     

Scanning electron-microscopy of starch granules, with or without amylase attack

Scanning electron-microscopy (SEM) revealed that, for starch granules relatively susceptible to amylase, numerous pin holes could be observed on the surfaces of granules attacked by amylase. We also observed that the pores penetrated into the inner layers of granules during the enzyme action and some of the granules exhibited a terraced or step-shaped apperance in their inner portions. These internal characteristics are most probably indicative of layered internal structures of the granules. The other characteristic observations by SEM were striated structures on the surfaces of starch granules of banana, lily, and lotus attacked by pancreatin.     

Nanoscale design of snake skin for reptation locomotions via friction anisotropy.

Multi-mode scanning probe microscopy is employed to investigate the nanostructure of dermal samples from three types of snakes. Sophisticated friction modifying nanostructures are described. These include an ordered microfibrillar array that can function to achieve mission adaptable friction characteristics. Significant reduction of adhesive forces in the contact areas caused by the 'double-ridge' nanoscale microfibrillar geometry provides ideal conditions for sliding in forward direction with minimum adhesive forces and friction. Low surface adhesion in these local contact points may reduce local wear and skin contamination by environmental debris. The highly asymmetric, 'pawl-like' profile of the microfibrillar ends with radius of curvature 20-40 nm induces friction anisotropy in forward backward motions and serves as an effective stopper for backward motion preserving low friction for forward motion. The system of continuous micropores penetrating through the snake skin may serve as a delivery system for lubrication/anti-adhesive lipid mixture that provides for boundary lubrication of snake skins.     

Springtails (Hexapoda,Collembola) of Tundra Landscapes of the Kola Peninsula

A quantitative study of collembolan assemblages on the Barents Sea coast of the Kola Peninsula was performed. Altogether, 104 collembolan species of 55 genera and 16 families were found. Analysis of the faunal composition revealed its high similarity to that of the faunas of the neighboring regions of Norway as well as a marked decline in species richness as compared to the Siberian analogues. A high share of littoral forms with increased vagility and the predominance of species with “southern” (= boreal) and “western” distribution patterns are the main characteristics of the fauna studied; only a few true arctic forms were found, always with low abundance and occurrence levels. Most of the studied collembolan assemblages are characterized by the dominance of a few species which inhabit a part of or the entire range of plant communities. As a result, collembolan assemblages under various types of vegetation cover in different landscape elements often show only insignificant differences.     

Vertical stratification of rainforest collembolan (Collembola: Insecta) assemblages: description of ecological patterns and hypotheses concerning their generation

We describe a complex vertical stratification of collembolan assemblages from rainforest leaf litter samples and identify distinct assemblages associated with forest floor, lower canopy and upper canopy samples. Leaf litter samples were collected from the forest floor and deposits of leaf litter suspended in epiphytes in the canopy of a subtropical rainforest site at Lamington National Park in southeast Queensland. The patterns of relationship among assemblages of Collembola extracted from these samples were examined using a variety of analyses of a matrix of similarities between samples. The results of ANOSIM analyses showed that forest floor, lower canopy and tipper canopy samples formed discrete groups. These results permit a discussion of these groups as three distinct collembolan assemblages. Analysis of the dissimilarities between these assemblages revealed a gradient of similarity from the forest floor through the lower to the upper canopy. This gradient represents a more complex vertical stratification than has previously been identified in rainforest canopy arthropods. We suggest that limitations on the dispersal of some forest floor species into the canopy may be responsible for this pattern. We also identify a second gradient of similarities among these assemblages. We show that dissimilarity among samples from forest floor is significantly lower than dissimilarity among samples from within the lower canopy, and that the level of dissimilarity between samples from within the upper canopy is significantly higher again. We suggest that dispersal barriers and higher probabilities of extinction in upper canopy collembolan colonies may be responsible for higher heterogeneity of species composition and abundance among samples from the upper canopy. We outline a number of testable hypotheses aimed at determining the importance of these processes in producing the patterns we have observed.     

Biosurfactants as Agents to Reduce Adhesion of Pathogenic Bacteria to Polystyrene Surfaces: Effect of Temperature and Hydrophobicity

Polystyrene surfaces were conditioned with surfactin and rhamnolipid biosurfactants and then assessed regarding the attachment of Staphylococcus aureus, Listeria monocytogenes, and Micrococcus luteus. The effect of different temperatures (35, 25, and 4°C) on the anti-adhesive activity was also studied. Microbial adhesion to solvents and contact angle measurements were performed to characterize bacteria and material surfaces. The results showed that surfactin was able to inhibit bacterial adhesion in all the conditions analyzed, giving a 63–66% adhesion reduction in the bacterial strains at 4°C. Rhamnolipid promoted a slight decrease in the attachment of S. aureus. The anti-adhesive activity of surfactin increased with the decrease in temperature, showing that this is an important parameter to be considered in surface conditioning tests. Surfactin showed good potential as an anti-adhesive compound that can be explored to protect surfaces from microbial contamination.     

Characterization and Distribution of Water-repellent, Self-cleaning Plant Surfaces

During the last 20 years, a wealth of data dealing with scanningelectron microscopy of plant surfaces has been published. Theultrastructure of epidermal surfaces has been investigated withrespect to taxonomic, as well as functional aspects. Withinthe latter, water-repellency has received much attention andhas been well documented. Water-repellency is based on surfaceroughness caused by different microstructures (trichomes, cuticularfolds and wax crystals), together with the hydrophobic propertiesof the epicuticular wax. In addition, contaminating particlesare carried away by water droplets, resulting in a cleaned surface(Lotus-effect). Therefore, rough, waxy leaves are not only water-repellentbut anti-adhesive with respect to particulate contamination.Based on 200 water-repellent plant species, the present papersurveys micromorphological characteristics of anti-adhesiveplant surfaces. Leaves that are permanently water-repellentcan be differentiated by distictively convex to papillose epidermalcells and a very dense layer of epicuticular waxes. Leaves thatare water-repellent for only a limited period of time have onlyslightly convex epidermal cells and often have a less densewax layer. Finally, an overview is given on the occurrence ofwater-repellency among different life forms and within differenthabitats. Water-repellency is concentrated in herbaceous species,while it is rare in trees. Among different habitats, subtropicalregions, wetlands and disturbed areas appear to have more specieswith water-repellent leaves. The importance of roughness andwater-repellency, respectively, as the basis of an anti-adhesive,self-cleaning surface, in comparison to other functions of microstructures,is discussed.     

Skin glands,poison and mimicry in dendrobatid and leptodactylid amphibians

In amphibians, secretions of toxins from specialized skin poison glands play a central role in defense against predators. The production of toxic secretions is often associated with conspicuous color patterns that warn potential predators, as it is the case of many dendrobatid frogs, including Ameerega picta. This species resembles the presumably nontoxic Leptodactylus lineatus. This study tests for mimicry by studying the morphology and distribution of skin glands, components of skin secretion, and defensive behavior. Dorsal skin was studied histologically and histochemically, and skin secretions were submitted to sodium dodecyl sulfate polyacrylamide gel electrophoresis, reversed phase high performance liquid chromatography and assays for proteolytic activity. We found that poison glands in A. picta are filled with nonprotein granules that are rich in carbohydrates, while L. lineatus glands present protein granules. Accordingly, great amounts of proteins, at least some of them enzymes, were found in the poison of L. lineatus but not in that of A. picta. Both species differ greatly on profiles of gland distribution: In L. lineatus, poison glands are organized in clusters whose position coincides with colored elements of the dorsum. These regions are evidenced through a set of displays, suggesting that poison location is announced to predators through skin colors. In contrast, A. picta presents lower densities of glands, distributed homogeneously. This simpler profile suggests a rather qualitative than quantitative investment in chemical defense, in agreement with the high toxicity attributed to dendrobatids in general. Our data suggest that both species are toxic or unpalatable and transmit common warning signals to predators, which represents a case of Müllerian mimicry. J. Morphol. 2012. © 2011 Wiley Periodicals, Inc.     

Development of chicken epidermis cultured with embryo extract

The epidermis from 11-day-old chick embryo shank skin was cultured with 11-day-old chick embryo extract. The growth and the differentiation of the epidermis in culture were studied histologically, electron microscopically and with polyacrylamide gel electrophoresis of keratin proteins. The epidermis cultured with the chick embryo extract proliferated and stratum structures developed simultaneously with the increase in epidermal cell layers. Finally, a keratinized layer was observed after 10 days in culture. Electron microscopic observations revealed that tonofilaments were produced after 2 days in culture and increased thereafter with culture time, becoming condensed with desmosomes. Keratohyaline granules were observed in 7-day cultures. These keratinization characteristics occurring during culture showed the general characteristics of the alpha stratum observed in the skin of in ovo embryos during the early stages of development. However, the development of peridermal and subperidermal granules was poor and the stratum granulosum, which develops at the late stages between the stratum intermedium and the stratum corneum, was not observed. Polyacrylamide gel electrophoresis of S-carboxymethylated keratin proteins showed that the keratin protein band patterns of the culture differed from those of in ovo skin epidermis.     

Inhibition of cell adhesion by high molecular weight kininogen

An anti-cell adhesion globulin was purified from human plasma by heparin-affinity chromatography. The purified globulin inhibited spreading of osteosarcoma and melanoma cells on vitronectin, and of endothelial cells, platelets, and mononuclear blood cells on vitronectin or fibrinogen. It did not inhibit cell spreading on fibronectin. The protein had the strongest antiadhesive effect when preadsorbed onto the otherwise adhesive surfaces. Amino acid sequence analysis revealed that the globulin is cleaved (kinin-free) high molecular weight kininogen (HKa). Globulin fractions from normal plasma immunodepleted of high molecular weight kininogen (HK) or from an individual deficient of HK lacked adhesive activity. Uncleaved single-chain HK preadsorbed at neutral pH, HKa preadsorbed at pH greater than 8.0, and HKa degraded further to release its histidine-rich domain had little anti-adhesive activity. These results indicate that the cationic histidine-rich domain is critical for anti-adhesive activity and is somehow mobilized upon cleavage. Vitronectin was not displaced from the surface by HKa. Thus, cleavage of HK by kallikrein results in both release of bradykinin, a potent vasoactive and growth-promoting peptide, and formation of a potent anti-adhesive protein.     

Response of collembolan communities to land-use change and grassland succession

This study focuses on the long-term changes of collembolan communities occurring after the conversion of arable land to managed grassland. We analysed collembolan communities at grassland sites of different age that had been gradually converted over a period of 50 yr. Abundance and biomass responded rapidly and very positively to the conversion of arable land to grassland, while species richness was not affected. Collembolan assemblages changed only little during grassland maturation. The impact of land-use change on community structure was more obvious at the functional level because the colonization processes observed in our study mostly relied on hemiedaphic species. Vegetation and soil parameters were good predictors of collembolan community structure during development of managed grassland. The present study demonstrated that past landscape patterns and processes like land-use conversion and subsequent succession had a considerable impact on the present day pattern of species richness and community composition of Collembola within a landscape. Our results strongly differ from those obtained for other invertebrate groups, highlighting on the one hand the very diverse reactions of invertebrates to a common factor, and on the other hand the need to survey more than one taxa in order to draw conclusions on effects of land-use change on faunistic communities.     

Interaction with heparin and matrix metalloproteinase 2 cleavage expose a cryptic anti-adhesive site of fibronectin

We recently found that fibronectin (FN) had a functional site [YTIYVIAL sequence in the heparin-binding domain 2 (Hep 2)] that was capable of suppressing the integrin-mediated cell adhesion to extracellular matrix. However, our results also indicated that this anti-adhesive site seemed to be usually buried within the Hep 2 domain structure because of its hydrophobic nature, raising a question as to the physiological significance of the cryptic anti-adhesive activity of FN. The present study demonstrates that the cryptic anti-adhesive activity can be exposed through the physiological processes. A 30-kDa chymotryptic FN fragment derived from Hep 2 domain (Hep 2 fragment), which had no effect on adhesion of MSV-transformed nonproducer 3T3 cell line (KN(7)8) to FN, expressed the anti-adhesive activity after treatment with 6 M urea. Light scattering and circular dichroism measurements showed that the urea treatment induced the conformational change of the Hep 2 fragment from a more compact form to an unfolded one. Incubation of the Hep 2 fragment with heparin also induced similar conformational changes and expression of anti-adhesive activity. Additionally, both the urea and heparin treatments made the Hep 2 fragment and intact FN much more accessible to the polyclonal antibody (alphaIII14A), with a recognition site near the anti-adhesive site of FN. Specific cleavage of either the Hep 2 fragment or intact FN by matrix metalloproteinase 2 (MMP-2) released a 10-kDa fragment with the anti-adhesive activity, which was shown to have the exposed anti-adhesive site on the amino-terminal region. Thus, the cryptic anti-adhesive activity of FN can be expressed upon conformational change and proteolytic cleavage of Hep 2 domain.     

Recolonization by Collembola of rehabilitated bauxite mines in Western Australia

Abstract The collembolan faunas of 30 bauxite mines rehabilitated by a range of different methods between 1966 and 1977, and three forest plots were surveyed in the spring and summer of 1978–79 with the aim of studying the restoration of decomposer activity in degraded areas. The rehabilitation methods included seeding and planting with a variety of native or exotic plant species. Physical and botanical parameters of the plots were also measured. Sixty species of Collembola were collected from the rehabilitated areas; nine of the 28 species found in the forest plots were not present on the mined sites. Principal components analysis suggested that the species richness of the collembolan community in rehabilitated areas is positively correlated with plot age. A parametric correlation analysis using a number of collembolan community characteristics revealed that, among other factors, the development of a species rich collembolan fauna is positively correlated with plant species richness and diversity, and also with percentage plant cover. These results provide directions for improving rehabilitation practices.     

三江平原农田土壤跳虫多尺度空间自相关性

土壤动物多尺度空间自相关性特征是土壤动物空间异质性和空间共存格局研究的重要基础。以土壤跳虫为研究对象,以中国科学院三江平原沼泽湿地生态实验站为研究区,于2011年8月和10月,选取具30 a以上耕作历史的旱地为实验样地,以5 m为步长设置一个50 m×50 m的实验样地,采用地统计中的全局Moran's I指数和局部Moran's I指数相结合的方法,研究土壤跳虫多尺度空间自相关性特征。全局空间自相关结果表明,土壤跳虫群落总密度和多数跳虫种类存在显著的多尺度空间自相关特征,多数为显著的正的空间自相关性,形成明显的空间集群。局部空间自相关结果表明,土壤跳虫群落总密度和所有跳虫种类均存在显著的局部空间自相关性,在局部地区形成"高—高"和/或"低—低"的空间集群,并和"高—低"和/或"低—高"的空间孤立区相伴发生,即形成"斑块"和"孔隙"相间分布的水平镶嵌格局;这种镶嵌格局具一定的时间动态特征,从夏季到秋季斑块大小和空间分布范围略有变化。研究表明,土壤跳虫具有明显的多尺度空间自相关性;空间集群是土壤跳虫的常见空间分布格局,在样地内形成"斑块"和"孔隙"相间分布的水平镶嵌格局,这种格局具年内时间变异性。     

“Collembola of the Western Taimyr:” Forty years later

A quantitative study of Collembola was carried out in 2010 in the area of the former Tareya Field Station of the Komarov Botanical Institute of the USSR Academy of Sciences, situated on the Taimyr Peninsula within the central part of the typical tundra subzone. The present-day collembolan assemblages were compared with those revealed 40 years ago, based on the results of a study performed in the region during the International Biological Program. Despite the absence of notable changes in the flora and vegetation, collembolan assemblages of all the plant associations studied in 2010 were clearly different from the complexes that had existed in the same territory at the end of the 1960s. Nevertheless, both the local collembolan fauna and the studied collembolan assemblages did not become more similar to their southern analogues and still fit well the characteristics typical of the region’s zonal position.     

Effect of habitat structural complexity on collembolan communities

We investigated soil microarthropod communities in two physically dissimilar inorganic soil materials and in a mixture of these two materials to examine the effect of the structural complexity of a habitat on microarthropod abundance and communities, teasing it out from that of nutritional factors. Mesh boxes were filled with perlite (a highly porous material), similar size of granite gravels (no pores inside), or their mixture, and placed on a forest floor. The boxes were collected after 8 or 20 months, and the microarthropods were extracted and identified to the species level, with a focus on Collembola. We also evaluated fine-root biomass and the amount of organic matter in the boxes. It was found that the mixture of perlite and granite enhanced microarthropod abundance and root development. A partial redundancy analysis revealed that collembolan communities developed differently among the substrate materials. We also found that variation in the collembolan communities was related to fine-root development and the abundance of other microarthropods, implying that habitat structural complexity affects collembolan communities indirectly by affecting soil food webs.     

Pituitary Secretory Granule Topography: Influence of Different Electron Microscopic Preparation Procedures on the Surface of Epon Sections

Human, rat and mouse pituitary tissues have been examined electron microscopically in transmission (TEM), scanning-transmission (STEM) and scanning (SEM) modes for the surface appearance of the secretory granules in tissue sections. Cryofixed and cryosectioned tissue showed only slightly protruding granule profiles which had a smooth surface. Cryofixed, freeze-dried and Epon embedded pituitaries, on the other hand, demonstrated swollen and furrowed surfaces over the granules after contact with water. This topography could also be seen after glutaraldehyde fixation but less after post-fixation in OsO₄. The surface alterations in the sections of pituitary secretory granules are thought to be due to differences in the homogeneity of the resin infiltration, leaving resin-free openings where water can enter. It also seems probable that the Epon resin is more influenced by water than has been previously assumed, based on the findings of efficient elimination of osmium from the granules after incubation of tissue sections in water for only 10 min.     

Springtails (Collembola) of eastern Chukotka: Characteristics of the fauna and species assemblages

A total of 139 collembolan species from 55 genera were found in coastal tundra near the settlement of Lavrentiya in the eastern part of the Chukchi Peninsula. The local fauna of the region is quite “Beringian” in species composition but its structure appears to be in full agreement with the known characteristics of southern tundra faunas of other sectors in the Arctic. The specificity of collembolan complexes of the main plant associations in the studied area is not very high because the predominant collembolan species usually inhabit a wide range of communities. The performed study on Collembola fails to confirm the conventional view of a significantly higher diversity of northeastern Palaearctic faunas. Despite the rather southern position of the studied coastal tundra, the species richness of its collembolan fauna seems to be the same as or only slightly higher than that of analogous landscapes in the other Arctic sectors. The apparent discrepancy between relatively low diversity of Collembola at the local level as shown herein and its rich regional fauna may be the result of increased differentiation of the collembolan fauna of the region characterized by very complex orography and extremely contrasting climatic conditions.     

Pituitary Secretory Granule Topography: Influence of Different Electron Microscopic Preparation Procedures on the Surface of Epon Sections

Human, rat and mouse pituitary tissues have been examined electron microscopically in transmission (TEM), scanning-transmission (STEM) and scanning (SEM) modes for the surface appearance of the secretory granules in tissue sections. Cryofixed and cryosectioned tissue showed only slightly protruding granule profiles which had a smooth surface. Cryofixed, freeze-dried and Epon embedded pituitaries, on the other hand, demonstrated swollen and furrowed surfaces over the granules after contact with water. This topography could also be seen after glutaraldehyde fixation but less after post-fixation in OsO₄. The surface alterations in the sections of pituitary secretory granules are thought to be due to differences in the homogeneity of the resin infiltration, leaving resin-free openings where water can enter. It also seems probable that the Epon resin is more influenced by water than has been previously assumed, based on the findings of efficient elimination of osmium from the granules after incubation of tissue sections in water for only 10 min.     

Chromaffin granules and their cellular location in human skin

Summary In a series of biopsies from human skin chromaffin granules were demonstrated in the corium by means of approved tinctorial methods. Characteristically shaped cells with protrusions are described as carriers of the granules.In a supplementary series of human and animal materials, as well as of skin and other tissues the same types of granules and cells were observed. An irregular distribution was demonstrated in the corium, i. e. increase around vessels, nerve fibres and glands, and in the subepithelial layer of the connective tissue. Preliminary calculations showed 2 to 4 times larger amounts in skin from the calf than in skin from the abdomen. In skin from the calf a considerable reduction of the chromaffin granules and typical cells could be demonstrated 24 hours after death. The tinctorial superiority of the modified Sevki method is emphasized. In the material examined, this method proved capable of disclosing chromaffin substance to a much larger extent than other staining procedures. An account is given of the possibilities to differentiate between mast-cell granules and chromaffin granules.Histochemical demonstration of noradrenalin and adrenalin was successful in human skin and in skin, adrenal glands and prostate from a cat and, finally, in skin from rats. The characteristically stained granules seem to be identical with chromaffin granules stained differently. Certain findings are thought to rule out that the cells might appertain to the enterochromaffin system.