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Über dieses Buch

J. Herbert Waite Like many graduate students before and after me I was There are so many species about which nothing is known, mesmerized by a proposition expressed years earlier by and the curse of not knowing is apathy. Krogh (1929) – namely that “for many problems there is Bioadhesion is the adaptation featured in this book, an animal on which it can be most conveniently studied”. and biology has many adhesive practitioners. Indeed, This opinion became known as the August Krogh Prin- every living organism is adhesively assembled in the ciple and remains much discussed to this day, particu- most exquisite way. Clearly, speci? c adhesion needs to larly among comparative physiologists (Krebs, 1975). be distinguished from the opportunistic variety. I think The words “problems” and “animal” are key because of speci? c adhesion as the adhesion between cells in the they highlight the two fundamental and complementary same tissue, whereas opportunistic adhesion might be the foci of biological research: (1) expertise about an animal adhesion between pathogenic microbes and the urinary (zoo-centric), which is mostly observational and (2) a tract, or between a slug and the garden path. If oppor- mechanistic analysis of some problem in the animal’s life nistic bioadhesion is our theme, then there are still many history or physiology (problem-centric), which is usually practitioners but the subset is somewhat more select than a hypothesis-driven investigation. before.



Part A


1. Bonding Single Pollen Grains Together: How and Why?

In their early developmental stages, the anthers (the pollen-producing organs of a male flower) form a tapetum between the sporogeneous tissue and the anther wall; both the tapetal cells and the sporogeneous cells have developed originally from the same subepidermal tissue. The tapetum is of considerable physiologic significance because all the nutritional material entering the microspores and later on the pollen grains passes or originates from it. In addition, during certain periods of pollen development, it accumulates substantial quantities of reserve compounds (e.g., starch and/or protein crystals in plastids, lipid droplets inside and outside the plastids, soluble polysaccharides in the vacuoles). These stored substances successively disappear during and after the tapetum degeneration, but several characters of mature pollen grains, which are of considerable interest in pollination, depend just on these substances. For details of tapetum development and ultrastructure the reader is referred to (1993); (1997); and (2005).
Michael Hesse

2. Deadly Glue — Adhesive Traps of Carnivorous Plants

Carnivorous plants trap and utilize animals in order to improve their supply with mineral nutrients. One strategy for prey capture is the use of adhesive traps, i.e., leaves that produce sticky substances. Sticky shoots are widespread in the plant kingdom and serve to protect the plant, especially flowers and seeds. In some taxa, mechanisms have been developed to absorb nutrients from the decaying carcasses of animals killed by the glue. In carnivorous plants sensu stricto, additional digestive enzymes are secreted into the glue to accelerate degradation of prey organisms.
The glues are secreted by glands that are remarkably uniform throughout all taxa producing adhesive traps. They follow the general scheme of plant glandular organs: the glands consist of a stalk, a neck equipped with a suberin layer that separates the gland from the rest of the plant, and the glandular cells producing sticky secretions. This glue always forms droplets at the tip of the glandular hairs. In most genera, these glands produce only glue whereas enzymes for prey digestion are secreted by a second type of gland. Two types of glue can be distinguished, polysaccharide mucilage in Droseraceae, Lentibulariaceae and their relatives, and terpenoid resins in Roridulaceae. On the ultrastructural level, mucilage is produced by the Golgi apparatus. Resins can be expected to be produced by the endoplasmic reticulum and by leucoplasts.
Adhesive traps are suitable not only for the capture of small animals but also for the collection of organic particles like pollen grains. The glue may contain toxic compounds but the prey usually dies from suffocation by clogging of its tracheae. In Pinguicula and Drosera, the performance of the traps is improved by a slow movement, i.e., the folding of the leaf around the prey animal upon stimulation. In some species of Nepenthes, a pitcher with smooth walls is filled with a sticky digestive fluid. Some organisms, however, have developed strategies to survive on the deadly traps. Several species of Hemiptera are able to walk on the sticky traps and nourish on the prey; their faeces are absorbed by the plant. In Roridula, this relationship is highly specialized and essential for both the plant and the insect. Mutualistic fungi and bacteria are common in many adhesive traps where they degrade and dissolve the plant’s prey. The traps of Drosera, on the other hand, are virtually sterile.
In spite of the extensive literature on adhesive traps, numerous questions still remain. Only a small percentage of “sticky” plants have actually been tested for carnivory. The properties and composition of their glues are widely unknown. In advanced adhesive traps, the mechanisms regulating secretion and absorption are poorly understood. Thereby, some glues may be applicable for human as they are non-toxic, quite stable under environmental conditions, and partly exhibit mildly antibiotic properties. Some carnivorous plants with adhesive traps have been used by humans for the capture of insects as well as for food processing.
Wolfram Adlassnig, Thomas Lendl, Marianne Peroutka, Ingeborg Lang

3. Bonding Tactics in Ctenophores — Morphology and Function of the Colloblast System

Ctenophores are a group of animals found in all the world’s seas, from coastal areas to the deep sea and from the tropics to the poles (Hyman, 1940). They are sometimes called “comb jellies” because they have a jelly-like appearance and distinctive rows of comb plates (ctenes) that are used for locomotion. Most ctenophores are transparent or translucent, and range from millimeters up to two meters in length, although most are in the few centimeter range (Ruppert et al., 2004).
Janek von Byern, Claudia E. Mills, Patrick Flammang

4. Gastropod Secretory Glands and Adhesive Gels

Gastropod molluscs are known for slime, yet the complexity and variety of their slimes is not always appreciated. These snails and slugs secrete visco-elastic mucous gels with functions that include feeding, protection, reproduction, locomotion, lubrication, defense, and adhesion (Denny, 1983). While the functional demands of such disparate tasks obviously vary widely, there has been little work on the biochemical variations and different secretory structures that give rise to these functional differences. The general structure and mechanics of Molluscan mucus have been reviewed (Denny, 1983; Smith, 2002), and the biochemical structure of some adhesive gels has been analyzed (Smith, 2006). Nevertheless, we still have a long way to go in characterizing the diversity of these gels and linking differences in structure to differences in their functional properties.
Andrew M. Smith

5. Characterization of the Adhesive Systems in Cephalopods

Cephalopods are highly evolved invertebrates; since ancient times, they have been admired for their intelligence, their ability to change color within milliseconds and their flexible arms, equipped with suckers or hooks. The suckers are versatile, mainly used to attach mechanically (by a reduced-pressure systems with a low pressure up to 0.01 MPa) to hard or soft surfaces (Smith, 1996; Kier and Smith, 2002; Pennisi, 2002); its usage and force strength varies, from a “soft sensing” of unknown objects to a fast and forceful holding of resisting prey. The suckers also have a sensory function and are equipped with a large repertoire of numerous mechano- and chemoreceptors (Nixon and Dilly, 1977).
Norbert Cyran, Lisa Klinger, Robyn Scott, Charles Griffiths, Thomas Schwaha, Vanessa Zheden, Leon Ploszczanski, Janek von Byern

6. Unravelling the Sticky Threads of Sea Cucumbers — A Comparative Study on Cuvierian Tubule Morphology and Histochemistry

Cuvierian tubules are peculiar organs found in several species of sea cucumbers, all belonging to the family Holothuriidae (order Aspidochirotida). Two main types of tubules can be differentiated on the basis of their gross external morphology, lobulated and smooth (Fig. 6.1; Table 6.1) (Lawrence, 2001). Lobulated tubules occur exclusively in the genus Actinopyga; they are never expelled and are not sticky (VandenSpiegel and Jangoux, 1993). On the other hand, smooth tubules are present in the genera Bohadschia, Holothuria, and Pearsonothuria, in which they generally appear as sticky white threads that function as a defence mechanism (Hamel and Mercier, 2000; Flammang, 2006). Indeed, once ejected, they can release a glue allowing instantaneous adhesion on any object, and can therefore entangle a predator in a matter of seconds (Zahn et al., 1973; VandenSpiegel and Jangoux, 1987). Smooth Cuvierian tubules will be the main focus of the present Chapter.
Pierre T. Becker, Patrick Flammang

7. Adhesion Mechanisms Developed by Sea Stars: A Review of the Ultrastructure and Composition of Tube Feet and Their Secretion

Like all animals belonging to the phylum Echinodermata, sea stars are characterized by a water-vascular system. This sophisticated hydraulic system consists of a series of interconnected canals: a central ring canal that encircles the gut of the animal and from which arise a single axial canal, the stone canal, communicating with the external seawater through a perforated plate (the madreporite), and five radial canals which extend into each arm of the sea star. The radial canals lead to a multitude of specialized external appendages, the tube feet (Nichols, 1966). According to the sea star species, tube feet may be involved in one or several of the following functions: locomotion, fixation to the substratum, feeding and burrowing. These different functions are allowed by the mobility of the proximal part of the tube foot (the so-called stem) as well as by the attachment of the distal part of the tube foot to the substratum (Flammang, 1996). Tube foot attachment is temporary. Indeed, although tube feet can adhere very strongly to the substratum, they are also able to detach easily and voluntarily before reinitiating another attachment-detachment cycle (Thomas and Hermans, 1985; Flammang, 1996). Suction has long been regarded as a major mean of tube foot attachment in sea stars (Paine, 1926; Smith, 1937; Nichols, 1966). However, a number of more recent observations argue for an adhesive process principally, if not exclusively, mediated by the secretion of an adhesive material (Chaet, 1965; Thomas and Hermans, 1985; Flammang et al., 1994, 1998). For instance, sea star tube feet can adhere very strongly to meshed or perforated substrata, or with only the margin of their distal part, two situations which prevent the use of suction by tube feet (Thomas and Hermans, 1985; Flammang et al., unpubl. obs.).
Elise Hennebert

8. Adhesive Exocrine Glands in Insects: Morphology, Ultrastructure, and Adhesive Secretion

A literature survey is provided summarizing the available information on exocrine epidermal glands that produce adhesive secretions in insects. The focus is on both the ultrastructure of the gland cells and the identity and function of the chemical secretion produced by them. Insects employ adhesives for various functions such as tarsal attachment during locomotion, resisting external detachment forces, mating, phoresy and parasitism, egg anchorage, retreat building, self-grooming, prey capture, and active and passive defence. The available studies on the ultrastructure and the secretion of adhesive insect glands cover a broad spectrum of developmental stages and higher taxa, i.e., the Elliplura, the Ephemeroptera, the Polyneoptera, the Acercaria, the Coleoptera, the Amphiesmenoptera, the Hymenoptera, and the Diptera (Table 8.1). Based on this diversity of biological contexts and systematic groups, adhesive structures are found at various tagmata of the body, mainly at the head, the abdomen, and the legs, but also within the thorax in the form of the metapleural glands of ants. Class 1 epidermal cells are the predominant glandular cell type among the adhesive gland systems in insects. With respect to their ultrastructure, the adhesive class 1 cells show features (in terms of their provision with endoplasmic reticulum, Golgi system, free ribosomes, and secretion vesicles and granules) that are either indicative of predominant non-proteinaceous (lipid) or protein secretion. In class 1 cells that are employed in locomotion (i.e., reversible tarsal adhesion to natural substrates such as plant surfaces), lipoidal secretion seems to prevail (although these secretions often appear to be complex mixtures of lipids with proteins and carbohydrates), whereas in the contexts of more permanent body or egg anchorage and of retreat building, protein-based secretion dominates. Oenocyte-like class 2 adhesive gland cells have hitherto only been found in the defence systems of Aphidoidea and Tingidae (both Hemiptera). Adhesive class 3 glands are almost always bicellular, consisting of a terminal secretorily active cell and an adjacent canal cell that surrounds the cuticular conducting duct.
The constituents found in insect adhesives belong to aliphatic compounds, to carbohydrates, to phenols, to isoprenoids, to heterocyclic compounds, and to amino acids, peptides, and proteins. Insect adhesives do not consist of one compound only but are highly complex (often emulsion-like) structural and chemical mixtures whose chemical and micromechanical functions are often poorly understood. The possible functional aspects of such mixtures include (1) the polar and nonpolar interactions of aliphatic compounds with the substratum, (2) the in situ differentiation of alkanes and alkenes at ambient temperatures forming colloid suspensions of solid wax crystals within a liquid matrix, (3) the non- Newtonian rheological behavior of colloid- and emulsion-like adhesive fluids, (4) the lipoid shields that prevent the aqueous fraction of an adhesive from desiccation and sticking to the walls of the outlet ductule, (5) those hydrocarbon properties (e.g., chain length and degree of unsaturation) that are decisive for the adhesive performance, (6) the rapid hardening of triglyceride- based adhesives caused by processes other than polymerization, (7) the water attractance of the large carbohydrate component of glycoproteins, (8) the quinone tanning induced by protein-polymerizing quinones, (9) the increased wetting properties toward lipophilic surfaces caused by monoterpenes combined with dissolved diterpenes that retard the rapid vaporization of the monoterpenes, (10) the production of aqueous lipid- glycoprotein- mucopolysaccharide mixtures, (11) those glues based on hydrophilic proteins (e.g., sericin with high Ser levels) coupling adhesion with high levels of extension and showing extensive hydrogen bonding, ester linkage, and/or ionic linkage, and (12) the proteinaceous underwater glues with their high levels of Cys (forming disulfide bonds) and charged amino acids.
Those adhesives that work mechanically might comprise high-molecular compounds containing proteins, terpenes (resins), mixtures of long-chain hydrocarbons and mucopolysaccharides, or waxes. However, defensive adhesive secretions in particular not only function mechanically, but also concomitantly develop a chemical irritant function caused by reactive substances of a low-molecular weight that are mixed within the sticky secretion to produce “toxic glue”.
Oliver Betz

9. Mechanisms of Adhesion in Adult Barnacles

Barnacles belong to the phylum Crustacea (following the taxonomy of Newman, 1987), which makes them segmented animals with jointed limbs, an exoskeleton that periodically moults, and a complex lifecycle involving metamorphosis between larval and adult forms. The group of crustaceans to which barnacles belong, the Cirripedia, has a unique larval form — the cyprid. This life history stage is adapted to locate a spot on which to permanently settle, develop, grow, and survive for the rest of its life. Barnacles have a worldwide distribution and various lifestyles, from parasitic species on the gills of decapod crustaceans to free-living groups. The free-living groups are adapted to permanently attach via cement onto other living organisms, rocks or man-made materials, and barnacle “fouling” on marine installations and cargo ships is increasingly of economic concern (Adamson and Brown, 2002). Within the free-living barnacles, a further division is recognized between acorn (Order Sessilia) and stalked (Order Pedunculata) forms. Certain stalked species are termed “pleustonic” due to a lifestyle at the air/water interface (see Bainbridge and Roskell, 1966) and these are the species which will be emphasized in this chapter (Fig.9.1A-C).
Anne Marie Power, Waltraud Klepal, Vanessa Zheden, Jaimie Jonker, Paul McEvilly, Janek von Byern

10. Morphology of the Adhesive System in the Sandcastle Worm, Phragmatopoma californica

The marine Sandcastle worm (P. californica) and related species live in composite mineralized tubes for shelter. They gather the mineral phase for free from the environment as sand grains and seashell bits with a crown of ciliated tentacles. The captured mineral particles are conveyed for inspection to the building organ — a pincer-shaped pair of dexterous palps in front of the mouth (Fig. 10.1). A dab of proteinaceous adhesive (Jensen and Morse, 1988) is secreted from the building organ onto suitable particles as they are pressed onto the end of the tube. The major protein components of the adhesive are a group of heterogeneous proteins, referred to as Pc3x, characterized by serial runs of 10–14 serine residues punctuated with single tyrosine residues (Zhao et al., 2005). Phosphorylation of more than 90% of the serines (Stewart et al., 2004) makes the Pc3 proteins polyacidic (pI<3). Other potential protein components identified biochemically (Waite et al., 1992) and by sequencing random cDNAs from an adhesive gland library (Endrizzi and Stewart, 2009) are generally polybasic with predicted pIs greater than 9. Amino acid analysis of secreted glue revealed that, in total, close to 50% of the adhesive protein residues are charged when serine phosphorylation is taken into account. The adhesive also contains Mg2+ and Ca2+ and a large fraction of the tyrosines are post-translationally hydroxylated to form 3,4-dihydroxyphenylalanine (DOPA), a residue shared with the adhesive plaque proteins of the mussel (Waite and Tanzer, 1981). Phosphates and o-dihydroxyphenols are well-known adhesion promoters.
Ching Shuen Wang, Kelli K. Svendsen, Russell J. Stewart

11. Adhesive Dermal Secretions of the Amphibia, with Particular Reference to the Australian Limnodynastid Genus Notaden

The class Amphibia includes three orders: the Caudata or Urodela, commonly known as salamanders and newts and characterized by possessing four limbs and a tail, the Gymnophiona or Caecilians, which are worm-like, have narrow bodies and lack limbs, and the Anura, which are the frogs and toads characterized by the possession of limbs but lack of a tail in the adult.
Michael J. Tyler

Part B


12. Renewable (Biological) Compounds in Adhesives for Industrial Applications

In the summer of 1991, a German couple hiking in the Alps came upon the newly revealed body of a man sticking out of the ice. He was 5000 years old and his possessions included a quiver of arrows. The arrow feathers were glued to the shafts with birch sap, an adhesive from a natural, renewable raw material. Furniture buried with the great kings of Egypt was beautifully made with fine wood veneers. The veneers were glued to a core with adhesives made by boiling hooves and hides of animals.
Hermann Onusseit

13. Bio-inspired Polyphenolic Adhesives for Medical and Technical Applications

Nature has been developing adhesives for millions of years, mankind for just a few thousands of years. For this reason it is worth having a closer look at what nature does and how we can develop bio-inspired adhesives for technical and medical applications. Some examples of natural materials which have already been used for technical adhesives are casein, latex rubber, tree gum, and adhesives derived from natural sources used for the waterproofing of natural textiles, the production of paper, and the sealing of jars (Papov et al., 1995; Creton and Papon, 2003). Bio-inspired adhesives can be found in all areas of the natural world. Because of their origin, those adhesives are also called biological adhesives or bioadhesives and they fulfill several different functions (Smith and Callow, 2006; Carrington, 2008; Antonietti and Fratzl, 2010). Plants use adhesives, for example, for self-healing and for protecting themselves against wood defects, while animals use sticky materials for protecting themselves against predators and for hunting prey (Keckes et al., 2003; Schreiber et al., 2005; Flammang, 2006; Voigt and Gorb, 2008; Plaza et al., 2009). Microorganisms use adhesive material for settlement, surface attachment, and colonization (Melzer et al., 2008; Flammang et al., 2009; Santos et al., 2009; Scholz et al., 2009). Higher organisms, such as humans, rely on an inducible adhesive system: the wound healing promoter fibrinogen ((Berlind et al., 2010), which is discussed in detail in Chapter 15, p. 225 of this book).
Klaus Rischka, Katharina Richter, Andreas Hartwig, Maria Kozielec, Klaus Slenzka, Robert Sader, Ingo Grunwald

14. Medical Products and Their Application Range

Of all dysfunctions of the human body physical injuries are intuitively the easiest to comprehend: if a bone is broken or a tissue ruptured, there treatment will in all likelihood lead to a full recovery of health. It is therefore hardly surprising that wound treatment and healing of broken bones are among the oldest disciplines of medicine. Physical injuries were and are part of daily life because accidents do occur. In addition, ancient medicine was strongly influenced by warfare. In those ages the strength of an army depended very much on the number and on the condition of its soldiers. For this reason military surgeons and their science were held in high esteem. The treatises on wound healing by well-known ancient physicians such as Hippocrates of Cos (ca. 460 BC -ca. 370 BC) or, e.g., the suggestions of Aristotle (384 BC-322 BC) to stock up on certain medicinal plants prior to going to war are witnesses to the history of medicine (Schlathölter, 2005).
Jessica Blume, Willi Schwotzer

15. Fibrin: The Very First Biomimetic Glue — Still a Great Tool

The phenomenon of blood clotting fascinated even the very earliest of philosophers and scientists. They marveled at the fact that the body could repair itself, stopping blood flow and healing its own defect. The idea of using the clotting mechanism to heal and close wounds also seems to have been a dream of the first medical doctors. Galen (129–199 AD) observed the clotting process in more detail and described “fibrae” or “threads” in both circulating blood and in clots and in 1666 Malpighi found “long tough threads” and “a nerve-like network of threads” in washed clots. These “threads” or fibers would later be identified as fibrin, the substance that is the end product of the coagulation cascade and that forms the basis of the blood clot. In 1905, the modern coagulation cascade as we know it was consolidated by Morawitz.
James Ferguson, Sylvia Nürnberger, Heinz Redl

16. Properties and Potential Alternative Applications of Fibrin Glue

Clot formation is an essential mechanism for wound closure and its principle is ubiquitous in the animal kingdom, comprising invertebrates such as arthropods, echinoderms, and cephalopods as well as all classes of vertebrates (Alsberg and Clark, 1908; Xu and Doolittle, 1990; Feral, 2010). The general principle of coagulation is the conversion of proteins to fibrous material by enzyme reaction in the presence of blood cells. Although the reacting partners (proteins, enzymes, and cell types) strongly differ between the animal groups, the final product always consists mainly or partly of fibrous material. Its functionality seems to rely on the formation of a gauze-like cover sealing the lesion.
Sylvia Nürnberger, Susanne Wolbank, Anja Peterbauer-Scherb, Tatjana J. Morton, Georg A. Feichtinger, Alfred Gugerell, Alexandra Meinl, Krystyna Labuda, Michaela Bittner, Waltraud Pasteiner, Lila Nikkola, Christian Gabriel, Martijn van Griensven, Heinz Redl

17. Biodegradable (Meth)acrylate-based Adhesives for Surgical Applications

The use of adhesives in surgery is an old but mostly unfulfilled dream (Donkerwolcke et al., 1998). Compared to conventional bonding techniques employed in surgery today like stitching, fixing with screws, pins, and plates, gluing has several advantages because it represents a fast and uncomplicated technique that causes no or only slight injuries of surrounding tissue and enables a homogenous load distribution between bonded materials (Rimpler, 1996). If such an adhesive would be gradually self-degrading in the body, newly formed tissue could replace the adhesive during the healing process and a complete regeneration of the damaged tissue would be possible. A gradual degradation of the adhesive would also maintain the necessary bonding strength within the tissue repair period and finally no foreign material would remain in the body.
Albrecht Berg, Fabian Peters, Matthias Schnabelrauch

18. Byssus Formation in Mytilus

The ability of the Mytilus genus of mussels (Phylum Mollusca, Class Bivalvia, and Family Mytilidae) to adhere in marine environments has fascinated researchers from numerous disciplines of science for decades. These relatively small, sessile bivalves attach to a wide range of surfaces present in their natural intertidal and subtidal ocean habitats (rocks, wood, seaweed, other animals, and ship hulls, for example) as well as to surfaces commonly tested in research laboratory settings (glass, plastics [including Teflon®], metals, and biological materials such as teeth, bones, cells, and tissues). No single man-made product on the market to date can claim to possess such a vast application range. An understanding of the unique biological adhesive system in Mytilus species (sp.) will undoubtedly aid in the development of biomimetic glues and related products for use in virtually every industry requiring bonding of two materials.
Heather G. Silverman, Francisco F. Roberto

19. Wet Performance of Biomimetic Fibrillar Adhesives

A number of legged organisms have evolved sophisticated, fibrillar attachment schemes that exhibit functional qualities highly desirable in synthetic reversible adhesives: substrate compliance, high adhesive strength, and sustained performance over many attach/release cycles (Creton and Gorb, 2007; Peattie, 2008). While a number of early synthetic mimics of fibrillar adhesives as well as the biological systems that inspired them are effective in ambient or low humidity environments, they are less effective in highly humid environments and function poorly in the presence of excess water. Yet, adhesives that function well under wet conditions are greatly desired for numerous industrial and consumer adhesive applications, as well as for biomedical uses (Yanik, 2009). This review chapter summarizes recent efforts in adapting or combining features of multiple biological adhesive strategies to develop biomimetic systems with enhanced wet adhesive performance. On-going research and development efforts are anticipated to lead to practical implementations of wet adhesives for a variety of uses.
K. H. Aaron Lau, Phillip B. Messersmith


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