Cell Attachment to cllagen: The requirement for energy

It has previously been demonstrated that cell attachment to collagen depends on the presence of a serum-derived cell attachment factor. Two steps in the cell attachment process have been defined. First, the cell attachment factor can bind to collagen in the absence of divalent cations. Secondly, either Ca⁺⁺ or Mg⁺⁺ are required for cells to attach to the collagen-cell attachment factor complex. A third requirement for cell attachment to collagen is demonstrated here; namely, cellular metabolic energy. A simple method for the assay of ATP in tissue culture cells is presented.     

On the So-called Mantle Muscle Scars on Shells of the Margaritiferidae (Mollusca, Pelecypoda), with Observations on Mantle-Shell Attachment in the Unionoida and Trigonioida

Mantle attachment scars on the inner surface of shells of the Margaritiferidae have been traditionally regarded as sites of mantle muscle attachment; however, the actual occurrence of muscle tissue at points of attachment has never been verified. Mantle attachment scars occur on shells of seven examined species of margaritiferids. Gross and histological investigation of the mantle of five species reveals that mantle attachment involves modification of mantle epithelial cells and associated connective fibers within the mantle. The connective fibers within the mantle do not appear to have contractile properties, but along with the attachment cells probably provide support for the mantle. Mantle-shell attachment scars similar to those of margaritiferids also occur in shells of recent trigonids, thus strengthening arguments for a phylogentic link between the Unionoida and Trigonioida.     

Analysis of the spatial organization of the XL chromosome attachment site in nurse cell nuclei of the malaria mosquito Anopheles atroparvus

The spatial position of the site of XL chromosome attachment to the nuclear envelope of ovarian nurse cells relative to the oocyte has been analyzed in the malaria mosquito Anopheles atroparvus. The XL chromosome attachment sites in the oocyte-nurse cell system of this species have been demonstrated to be orderly arranged, with the attachment sites in two out of three nurse cells in the same layer identically oriented relative to the oocyte.     

The effects of plant epicuticular waxy blooms on attachment and effectiveness of predatory insects

Phytophagous insects and their natural enemies frequently must cling to plants in order to forage. Typically, this involves attachment to the layer of lipophilic materials, or 'epicuticular waxes' (EW) that covers all primary plant surfaces. EW occurring as crystalline waxy 'blooms' can provide a defense against herbivory by interfering with attachment to plants by phytophagous insects. On the other hand, EW blooms can reduce attachment by predators and parasitoids, potentially releasing populations of phytophagous insects from regulation by their natural enemies. The net effect of EW blooms on herbivory should therefore vary from system to system. When it has been measured, EW bloom typically reduces the attachment forces insects can generate on plants. Some herbivores and predators preferentially forage on plants with EW blooms. Among these, some appear to have physiological or behavioral adaptations that either improve attachment to EW blooms or cope with reduced attachment to plants surfaces bearing EW blooms. How EW blooms disrupt insect attachment and how insects potentially overcome this challenge has not been determined. Some hypotheses are offered in this review. Their elucidation may help understand the mechanics of attachment to plants, with applications including helping to improve biological control of some insect pests.     

Analysis of the spatial organization of the XL chromosome attachment site in nurse cell nuclei of the malaria mosquito <Emphasis Type="Italic">Anopheles atroparvus</Emphasis>

The spatial position of the site of XL chromosome attachment to the nuclear envelope of ovarian nurse cells relative to the oocyte has been analyzed in the malaria mosquito Anopheles atroparvus van Thiel. The XL chromosome attachment sites in the oocyte-nurse cell system of this species have been demonstrated to be orderly arranged, with the attachment sites in two out of three nurse cells in the same layer identically oriented relative to the oocyte.     

Cell surface attachment structures contribute to biofilm formation and xylem colonization by Erwinia amylovora

Biofilm formation plays a critical role in the pathogenesis of Erwinia amylovora and the systemic invasion of plant hosts. The functional role of the exopolysaccharides amylovoran and levan in pathogenesis and biofilm formation has been evaluated. However, the role of biofilm formation, independent of exopolysaccharide production, in pathogenesis and movement within plants has not been studied previously. Evaluation of the role of attachment in E. amylovora biofilm formation and virulence was examined through the analysis of deletion mutants lacking genes encoding structures postulated to function in attachment to surfaces or in cellular aggregation. The genes and gene clusters studied were selected based on in silico analyses. Microscopic analyses and quantitative assays demonstrated that attachment structures such as fimbriae and pili are involved in the attachment of E. amylovora to surfaces and are necessary for the production of mature biofilms. A time course assay indicated that type I fimbriae function earlier in attachment, while type IV pilus structures appear to function later in attachment. Our results indicate that multiple attachment structures are needed for mature biofilm formation and full virulence and that biofilm formation facilitates entry and is necessary for the buildup of large populations of E. amylovora cells in xylem tissue.     

Glycolipid receptor depletion as an approach to specific antimicrobial therapy

Mucosal pathogens recognize glycoconjugate receptors at the site of infection, and attachment is an essential first step in disease pathogenesis. Inhibition of attachment may prevent disease, and several approaches have been explored. This review discusses the prevention of bacterial attachment and disease by agents that modify the glycosylation of cell surface glycoconjugates. Glycosylation inhibitors were tested in the urinary tract infection model, where P-fimbriated Escherichia coli rely on glycosphingolipid receptors for attachment and tissue attack. N-butyldeoxynojirimycin blocked the expression of glucosylceramide-derived glycosphingolipids and attachment was reduced. Bacterial persistence in the kidneys was impaired and the inflammatory response was abrogated. N-butyldeoxynojirimycin was inactive against strains which failed to engage these receptors, including type 1 fimbriated or nonadhesive strains. In vivo attachment has been successfully prevented by soluble receptor analogues, but there is little clinical experience of such inhibitors. Large-scale synthesis of complex carbohydrates, which could be used as attachment inhibitors, remains a technical challenge. Antibodies to bacterial lectins involved in attachment may be efficient inhibitors, and fimbrial vaccines have been developed. Glycosylation inhibitors have been shown to be safe and efficient in patients with lipid storage disease and might therefore be tested in urinary tract infection. This approach differs from current therapies, including antibiotics, in that it targets the pathogens which recognize these receptors.     

Effect of glycosaminoglycans on fibronectin-mediated cell attachment

In this study, the role of glycosaminoglycans in fibronectin-mediated cell attachment to collagen has been investigated. While it has been established that fibronectin possesses binding sites for several glycosaminoglycans, it was found that only dextran sulfate and macromolecular heparin could decrease the initial rate of cell attachment to collagen. Low molecular weight heparin was inactive. This study suggests that the glycosaminoglycan binding site of fibronectin plays a role in the mechanism of cell attachment.     

Gehechtheid als beïnvloedende factor van gedrags- en psychologische symptomen bij dementie

Contemporary research has increasingly acknowledged the importance of attachment on stress-related processes in ageing. Congruent with this, there has been much research on attachment in older adults over the past three decades. In this article, the main findings of this research are summarized, with a focus on attachment and dementia. Results show that, in general, the number of attachment figures decreases in old age. Moreover, their identity changes as adult children, deceased loved ones and God become more prominent. With relation to the quality of attachment, anxiety in close relations appears to diminish as people age, while attachment avoidance remains relatively stable. Individuals with high levels of attachment security also report greater well-being and a more positive attitude towards ageing compared to persons with low levels of attachment security. Furthermore, individuals characterized by insecure attachment show more behavioral and psychological problems in dementia. Also, caregiver burden, depression, as well as the quality of care giving and future caregiver commitment differ depending on the quality of attachment of the caregiver. There is preliminary evidence for the efficacy of attachment-based interventions in dementia. Finally, there is a need for greater methodological uniformity and the use of measures that are validated for an older population.     

Attachment of plastic fluidic components to glass sensing surfaces.

Two types of flow manifolds have been developed in order to provide a reliable method for attaching plastic microfluidic systems to glass sensing surfaces. A permanently mounted flow manifold has grooves in the inter-channel barriers to confine the epoxy used for attachment. The reusable flow manifold has inter-channel barriers composed of both plexiglass for rigidity and polydimethysiloxane for leak-free attachment.     

Testican-1 inhibits attachment of Neuro-2a cells.

Testican-1 is a highly conserved, multidomain, chondroitin sulfate proteoglycan that is most abundantly transcribed in the brain by neurons. This testican messenger RNA is not detected in normal quiescent astrocytes, but is up regulated when these cells are activated in response to injury such as cerebral stroke. Other chondroitin sulfate proteoglycans found in glial scars, including neurocan, have been shown to inhibit neural cell attachment and neurite extensions and may thus impede axonal regeneration. Here we report the expression and purification of a proteoglycan form of recombinant testican and its effects on neuron-derived cells in culture. We demonstrate that testican inhibits attachment of Neuro-2a cells and their ability to form neurite extensions. Both testican proteoglycan and the core glycoprotein that has been depleted of chondroitin sulfate inhibit cell attachment. Pre-treatment of the culture substratum with testican inhibits Neuro-2a attachment, but pre-treatment of the cells with testican does not inhibit their attachment. Testican, therefore, blocks attachment sites on cultureware and may also block attachment sites in the extracellular matrix of the brain.     

An attachment perspective on psychopathology

In recent years, attachment theory, which was originally formulated to describe and explain infant-parent emotional bonding, has been applied to the study of adolescent and adult romantic relationships and then to the study of psychological processes, such as interpersonal functioning, emotion regulation, coping with stress, and mental health. In this paper, we offer a brief overview of the attachment perspective on psychopathology. Following a brief account of attachment theory, we go on to explain how the study of individual differences in adult attachment intersects with the study of psychopathology. Specifically, we review research findings showing that attachment insecurity is a major contributor to mental disorders, and that the enhancement of attachment security can facilitate amelioration of psychopathology.     

Attachment and growth of mammalian cells on microcarriers with different ion exchange capacities

In the design of microcarriers for animal cell growth, the exchange capacity has been considered a critical factor. However, charge densities of microcarriers under culture conditions are not the same as the exchange capacities. Furthermore, the charge density requirement for optimum attachment is not necessarily the same as that required for optimum growth. We demonstrate that charge is not the sole factor affecting the attachment and growth of animal cells on microcarriers. We also show that supplemental serum in the growth medium has a negative effect on cell attachment to microcarriers.     

Adhesion and fusion of the extraembryonic epiblast

A tissue culture model system has been devised to examine the attachment, expansion, and fusion of epithelial cell sheets. A normal embryonic epithelial tissue, the extraembryonic epiblast of the chick, is isolated mechanically and cultured on its natural substratum, the vitelline membrane. This persistently migratory tissue has distinct adhesive and non-adhesive regions. A serum-free chemically-defined culture medium has been formulated that permits determination of the effects of individual growth and trophic factors. Attachment of transferred epiblasts is dependent upon the presence of mineralocorticoids in the medium. This suggests that fluid transport is required for the cell sheet to make its initial attachment to the culture substratum. Expansion of the cell sheet following attachment, and the fusion of epiblasts advancing toward each other, does not require the presence of mineralocorticoid. No exogenous adhesive glycoproteins are required for attachment, expansion, or fusion. Antibody localization shows that endogenous laminin is present on the attachment surface of the specialized adhesive edge region of the extraembryonic epiblast. Following fusion of confronted epiblasts into one coherent cell sheet, the laminin disappears. Throughout these studies the adhesive and non-adhesive regions of the epiblast are identified by their characteristic distributions of actin microfilaments, localized using rhodamine-phalloidin staining.     

Cell surface receptors for picornaviruses

Picornaviruses can be divided into at least six receptor families based on results of competition binding and receptor antibody studies. It has been proposed that a canyon present within the virion capsid harbors the viral attachment site for this group of viruses. Cell surface proteins involved in viral attachment have been identified for both rhinoviruses and coxsackie B viruses. Several monoclonal antibodies have been isolated which specifically block the binding of some picornaviruses.     

Abnormalities of the attachment clamps of representatives of the family Diplozoidae

A comparative study has been made of the haptoral morphology of four species of diplozoon (Monogenea: Diplozoidae) from the gills of fish exposed to different levels of water pollution in two river systems in eastern Europe. An examination of the haptors of Paradiplozoon homoion (Bychowsky & Nagibina 1959), Paradiplozoon ergensi (Pejcoch 1968) and Paradiplozoon megan (Bychowsky & Nagibina 1959) from chub caught in the River Morava, Czech Republic and of Diplozoon paradoxum (Nordmann 1832) from bream recovered from the River Volga, Russia has revealed abnormalities to the attachment clamps. Two abnormal conditions were found: structural alterations to the attachment clamps and changes in the number of attachment clamps; these occurred both singly and in combination. A higher frequency of abnormal attachment clamps was found in diplozoons from fish caught in the more polluted localities of both rivers. The abnormalities have been recorded and their morphology compared in the light of conditions of environmental stress.     

The fine structure of the interrelationship of cells in the human epidermis

In the present investigation an analysis has been made of the fine structure of the interrelationships of cells in human forearm epidermis by means of the electron microscope. The "intercellular bridges," here called attachment zones, are more complex than has previously been recognized. It is shown that dense oval thickenings, called attachment plaques, appear in apposed areas of adjacent epidermal cell membranes. The tonofibrils terminate at the internal face of the attachment plaque and do not traverse the 300 A distance between apposed plaques. Seven intervening layers of unidentified substance occupy the space between attachment plaques. The attachment zones appear in all of the classical histological layers of the epidermis. The portions of epidermal cell membrane not involved in intercellular attachments have extensive surface area resulting from plication of the membrane, and its further modification to form microvilli. The possible functional significance of these observations is discussed. Prior observations concerning the basement membrane of epidermis are confirmed. Identification of epidermal melanocytes is achieved, the finer morphology of their dendritic processes is described, and their relationship to epidermal cells is discussed.     

Photoactivated covalent binding of [3H]bilirubin to human serum albumin.

A one-step procedure has been developed for the preparation of [3H]bilirubin IX-alpha in good yield from unlabelled bilirubin. Irradiation of an aqueous solution of [3H]bilirubin IX-alpha in the presence of human serum albumin results in the covalent attachment of the bilirubin to the protein. Preliminary degradation studies have been carried out to locate the site of attachment of the bilirubin to the albumin.     

The biliverdin chromophore binds covalently to a conserved cysteine residue in the N-terminus of Agrobacterium phytochrome Agp1

Phytochromes are widely distributed biliprotein photoreceptors. Typically, the chromophore becomes covalently linked to the protein during an autocatalytic lyase reaction. Plant and cyanobacterial phytochromes incorporate bilins with a ring A ethylidene side chain, whereas other bacterial phytochromes utilize biliverdin as chromophore, which has a vinyl ring A side chain. For Agrobacterium phytochrome Agp1, site-directed mutagenesis provided evidence that biliverdin is bound to cysteine 20. This cysteine is highly conserved within bacterial homologues, but its role as attachment site has as yet not been proven. We therefore performed mass spectrometry studies on proteolytic holopeptide fragments. For that purpose, an Agp1 expression vector was re-engineered to produce a protein with an N-terminal affinity tag. Following proteolysis, the chromophore co-purified with a ca. 5 kDa fragment during affinity chromatography, showing that the attachment site is located close to the N-terminus. Mass spectrometry analyses performed with the purified chromopeptide confirmed the role of the cysteine 20 as biliverdin attachment site. We also analyzed the role of the highly conserved histidine 250 by site-directed mutagenesis. The homologous amino acid plays an important but yet undefined role in plant phytochromes and has been proposed as chromophore attachment site of Deinococcus phytochrome. We found that in Agp1, this amino acid is dispensable for covalent attachment, but required for tight chromophore-protein interaction.     

The attachment response of the cercaria of Schistosoma mansoni. Influence of natural substrates and temperature (author's transl)]

The behaviour of the cercaria, following contact with different animal and human substrates during swimming, has been studied. Four patterns of behavior related to the intensity of stimulation can be distinguished: 1. backward reaction, 2. stopping, 3. forward reaction, 4. attachment (Figs. 2 and 3). Mechanical stimulation of the cercaria by touching or water turbulence, prior to contact with the substrate has an insignificant effect on attachment. Both attachment and the first step in penetration (crawling over the substrate) are stimulated by a rise in temperature (Figs. 4 and 5) and the chemical properties of the substrate. However, the steps in penetration may possibly be stimulated by chemical components and perceived by receptors different from those involved in attachment.