Hyperunstable matrix proteins in the byssus of Mytilus galloprovincialis.

The marine mussel Mytilus galloprovincialis is tethered to rocks in the intertidal zone by a holdfast known as the byssus. Functioning as a shock absorber, the byssus is composed of threads, the primary molecular components of which are collagen-containing proteins (preCOLs) that largely dictate the higher order self-assembly and mechanical properties of byssal threads. The threads contain additional matrix components that separate and perhaps lubricate the collagenous microfibrils during deformation in tension.

Production of shelf-stable ranch dressing using high-pressure processing.

High-pressure processing (HPP) can reduce or eliminate microorganisms of concern in food without deteriorating product quality; however, quality benefits must justify the substantial capital investment for the utilization of this technology. HPP is particularly a beneficial preservation technology for products damaged by thermal treatments or when product quality could be improved by reformulation to raise pH or eliminate chemical preservatives. The primary objectives of this study were to determine the efficacy of HPP to protect premium ranch dressing (pH 4.

Fluorescence Investigations into Complex Coacervation between Polyvinylimidazole and Sodium Alginate.

Electrostatic interactions between the imidazole-based cationic homopolymer, polyvinylimidazole (PVIm), and anionic polysaccharide, sodium alginate, lead to the formation of colloidal aggregates known as complex coacervates in the pH range 4-6.5. PVIm was labeled with the fluorescent reporter pyrene to investigate the coacervation-induced changes in and around PVIm chains.

Collagen insulated from tensile damage by domains that unfold reversibly: in situ X-ray investigation of mechanical yield and damage repair in the mussel byssus.

The byssal threads of the California mussel, Mytilus californianus, are highly hysteretic, elastomeric fibers that collectively perform a holdfast function in wave-swept rocky seashore habitats. Following cyclic loading past the mechanical yield point, threads exhibit a damage-dependent reduction in mechanical performance. However, the distal portion of the byssal thread is capable of recovering initial material properties through a time-dependent healing process in the absence of active cellular metabolism.

Isolation and identification of spoilage microorganisms using food-based media combined with rDNA sequencing: ranch dressing as a model food.

Investigating microbial spoilage of food is hampered by the lack of suitable growth media and protocols to characterize the causative agents. Microbial spoilage of salad dressing is sporadic and relatively unpredictable, thus processors struggle to develop strategies to minimize or prevent spoilage of this product. The objectives of this study were to (i) induce and characterize spoilage events in ranch-style dressing as a model food, and (ii) isolate and identify the causative microorganisms using traditional and food-based media, coupled with rDNA sequence analysis.

Stiff coatings on compliant biofibers: the cuticle of Mytilus californianus byssal threads.

For lasting holdfast attachment, the mussel Mytilus californianus coats its byssal threads with a protective cuticle 2-5 microm thick that is 4-6 times stiffer than the underlying collagen fibers. Although cuticle hardness (0.1 GPa) and stiffness (2 GPa) resemble those observed in related mussels, a more effective dispersion of microdamage enables M.

Comparison and evaluation of methods for liver segmentation from CT datasets.

This paper presents a comparison study between 10 automatic and six interactive methods for liver segmentation from contrast-enhanced CT images. It is based on results from the "MICCAI 2007 Grand Challenge" workshop, where 16 teams evaluated their algorithms on a common database. A collection of 20 clinical images with reference segmentations was provided to train and tune algorithms in advance.

Metals and the integrity of a biological coating: the cuticle of mussel byssus.

The cuticle of mussel byssal threads is a robust natural coating that combines high extensibility with high stiffness and hardness. In this study, fluorescence microscopy and elemental analysis were exploited to show that the 3,4-dihydroxyphenyl-L-alanine (dopa) residues of mussel foot protein-1 colocalize with Fe and Ca distributions in the cuticle of Mytilus galloprovincialis mussel byssal threads. Chelated removal of Fe and Ca from the cuticle of intact threads resulted in a 50% reduction in cuticle hardness, and thin sections subjected to the same treatment showed a disruption of cuticle integrity.

Enhanced inactivation of foodborne pathogenic and spoilage bacteria by FD&C Red no. 3 and other xanthene derivatives during ultrahigh pressure processing.

Variability among microorganisms in barotolerance has been demonstrated at genus, species, and strain levels. Identification of conditions and additives that enhance the efficacy of ultrahigh pressure (UHP) against important foodborne microorganisms is crucial for maximizing product safety and stability. Preliminary work indicated that FD&C Red No.

T cell-dendritic cell immunological synapses contain TCR-dependent CD28-CD80 clusters that recruit protein kinase C theta.

Short-lived TCR microclusters and a longer-lived protein kinase Ctheta-focusing central supramolecular activation cluster (cSMAC) have been defined in model immunological synapses (IS). In different model systems, CD28-mediated costimulatory interactions have been detected in microclusters, the cSMAC, or segregated from the TCR forming multiple distinct foci. The relationship between TCR and costimulatory molecules in the physiological IS of T cell-dendritic cell (DC) is obscure.

Ragworm jaw-inspired metal ion cross-linking for improved mechanical properties of polymer blends.

Several naturally occurring biomacromolecular structures, particularly those containing histidine-rich proteins, have been shown to depend on metal ion complexation for hardness and stiffness. In this study, water-soluble metal-binding polymers and copolymers based on vinylimidazole were utilized to mimic the glycine- and histidine-rich proteins of ragworm jaws. Blends of these polymers with agarose exhibited a significant capacity for Zn(II) and Cu(II) complexation.

Role of transition metals in sclerotization of biological tissue.

Biomimetics seeks to elucidate the biochemical and structural principles governing functionality in biological systems and exploit them in the design of synthetic materials. Although the lure has been great, breakthroughs have been rare. The overwhelming complexity of chemical compositions and structural motifs in biology renders the task of "reverse engineering" a formidable challenge.

Mussel-designed protective coatings for compliant substrates.

The byssus of marine mussels has attracted attention as a paradigm of strong and versatile underwater adhesion. As the first of the 3,4-dihydroxyphenylalanine (Dopa)-containing byssal precursors to be purified, Mytilus edulis foot protein-1 (mefp-1) has been much investigated with respect to its molecular structure, physical properties, and adsorption to surfaces. Although mefp-1 undoubtedly contributes to the durability of byssus, it is not directly involved in adhesion.

Factors impacting equine sperm recovery rate and quality following cushioned centrifugation.

Two experiments were conducted to investigate modifications in cushioned centrifugation of stallion semen. Specifically, the effects of tube type, centrifugation medium, cushion type, and centrifugation force on post-centrifugation sperm recovery rate and quality were evaluated. In Experiment 1, sperm recovery rate was higher (P<0.

Cutting edge structural protein from the jaws of Nereis virens.

The fang-like jaws of the marine polychaete Nereis virens possess remarkable mechanical properties considering their high protein content and lack of mineralization. Hardness and stiffness properties in the jaw tip are comparable to human dentin and are achieved by extensive coordination of Zn (2+) by a histidine-rich protein framework. In the present study, the predominant protein in the jaw tip, Nvjp-1, was purified and characterized by partial peptide mapping and molecular cloning of a partial cDNA from a jaw pulp library.

pH-dependent locking of giant mesogens in fibers drawn from mussel byssal collagens.

Byssal threads are tough collagenous fibers that mussels use to secure themselves against dislodgement by waves in the marine intertidal zone. Here, preCol, a family of hybrid collagens comprising up to 96% of the protein content in certain regions of byssal threads, was purified in mg amounts from mussel foot tissue for the first time. Conditions for drawing preCols into quality fibers ex vivo were investigated.

The transition from stiff to compliant materials in squid beaks.

The beak of the Humboldt squid Dosidicus gigas represents one of the hardest and stiffest wholly organic materials known. As it is deeply embedded within the soft buccal envelope, the manner in which impact forces are transmitted between beak and envelope is a matter of considerable scientific interest. Here, we show that the hydrated beak exhibits a large stiffness gradient, spanning two orders of magnitude from the tip to the base.

Hepatitis C virus window-phase infections: closing the window on hepatitis C virus.

Background: The detection of hepatitis C virus (HCV) infection is of major importance for the prevention of transfusion-transmitted hepatitis. The testing of donations by nucleic acid testing (NAT) techniques may not be feasible or economic. Combined antigen and antibody assays are now available, and the performance of two combined assays on window-phase donations is evaluated.

Effects of hydration on mechanical properties of a highly sclerotized tissue.

The jaws of the bloodworm Glycera dibranchiata consist principally of protein and melanin scaffolds with small amounts of unmineralized copper (Cu) and mineralized atacamite (Cu(2)Cl(OH)(3)) fibers in distinct regions. Remarkably, when tested in air, the regions containing unmineralized Cu are the hardest, stiffest, and most abrasion resistant. To establish the functions of jaw constituents in physiologically relevant environments, this study examines the effects of hydration on their response to indentation, scratching, and wear.

Holdfast heroics: comparing the molecular and mechanical properties of Mytilus californianus byssal threads.

The marine mussel Mytilus californianus Conrad inhabits the most wave-exposed regions of the rocky intertidal by dint of its extraordinary tenacity. Tenacity is mediated in large part by the byssus, a fibrous holdfast structure. M.

Contribution of wine components to inactivation of food-borne pathogens.

Wine is a complex solution containing several components with several likely antimicrobial properties. Low pH (3.0 to 4.

A nonmineralized approach to abrasion-resistant biomaterials.

The tooth-like mouthparts of some animals consist of biomacromolecular scaffolds with few mineral components, making them intriguing paradigms of biostructural materials. In this study, the abrasion resistance of the jaws of one such animal, the bloodworm Glycera dibranchiata, has been evaluated by nanoindentation, nanoscratching, and wear testing. The hardest, stiffest, and most abrasion-resistant materials are found within a thin (<3 microm) surface layer near the jaw tip and a thicker (10-20 microm) subsurface layer, both rich in unmineralized Cu.

Complex signatures of selection and gene conversion in the duplicated globin genes of house mice.

Results of electrophoretic surveys have suggested that hemoglobin polymorphism may be maintained by balancing selection in natural populations of house mice, Mus musculus. Here we report a survey of nucleotide variation in the adult globin genes of house mice from South America. We surveyed nucleotide polymorphism in two closely linked alpha-globin paralogs and two closely linked beta-globin paralogs to test whether patterns of variation are consistent with a model of long-term balancing selection.