Identification of endogenous peroxidase-containing cells as eosinophils in the gastrointestinal system

 Endogenous peroxidase (EPX) activity in certain cells in the gastrointestinal system interferes with immunohistochemical methods based on the horseradish peroxidase-catalyzed substrate deposition. We studied the distribution and characteristics of these cells. We also report an effective and antigen-preserving EPX blocking method, to make possible the evaluation of immunoperoxidase stainings in cryostat sections. The EPX-containing cells (EPX cells) are present in every part of the gastrointestinal tract, predominantly in the tunica propria. We identified them as eosinophil cells in May-Grünwald-Giemsa stained sections. The complete match was confirmed by different fluorescence techniques. Firstly, the EPX cells were labeled by a red fluorochrome-conjugated substrate of peroxidase enzymes, rhodamine-tyramide, whereas the eosinophil cells were labeled by the green fluorochrome, 1-hydroxy-3,6,8-pyrenetrisulfonic acid, which is known to label exclusively eosinophilic granules at pH 10. Secondly, all the EPX cells reacted with a monoclonal antibody against the eosinophil peroxidase enzyme. Finally, a set of commercially available leukocyte markers was used to characterize the EPX cells colabeled by fluorochrome-tyramides. Neither macrophages nor mast cells showed EPX activity. Increased numbers and altered distribution were seen in stressed rats and in ulcerated human stomach. Accepted: 16 July 1996     

The crystal structure of the processive endocellulase CelF of Clostridium cellulolyticum in complex with a thiooligosaccharide inhibitor at 2.0 A resolution.

The mesophilic bacterium Clostridium cellulolyticum exports multienzyme complexes called cellulosomes to digest cellulose. One of the three major components of the cellulosome is the processive endocellulase CelF. The crystal structure of the catalytic domain of CelF in complex with two molecules of a thiooligosaccharide inhibitor was determined at 2.0 A resolution. This is the first three-dimensional structure to be solved of a member of the family 48 glycosyl hydrolases. The structure consists of an (alpha alpha)6-helix barrel with long loops on the N-terminal side of the inner helices, which form a tunnel, and an open cleft region covering one side of the barrel. One inhibitor molecule is enclosed in the tunnel, the other exposed in the open cleft. The active centre is located in a depression at the junction of the cleft and tunnel regions. Glu55 is the proposed proton donor in the cleavage reaction, while the corresponding base is proposed to be either Glu44 or Asp230. The orientation of the reducing ends of the inhibitor molecules together with the chain translation through the tunnel in the direction of the active centre indicates that CelF cleaves processively cellobiose from the reducing to the non-reducing end of the cellulose chain.     

Interaction between pools of binocular disparity detectors tuned to different disparities

Unambiguous dots (having one binocular disparity) when inserted in an ambiguous random-dot stereogram (with multiple disparity values) could pull the ambiguous percept. The unambiguous bias carried that ambiguous depth percept whose disparity was nearest to the disparity of the bias. The closer the disparities were to each other, the stronger the pulling effect that was observed. Even a physical bias of 4% density was adequate to overcome the natural bias of most observers. The stimulus duration had to be over 50 msec to provide a strong pulling effect. In all experiments the stimulus duration was 160 msec or shorter, indicating that the pulling effect was a product of neural interactions, rather than convergence movement of the eyes. As a result of these findings a parallel model of stereopsis has been proposed, which extends the spring-coupled dipole model of Julesz (1971).     

Effects of elastase on the mechanical and failure properties of engineered elastin-rich matrices.

Pulmonary emphysema and vessel wall aneurysms are diseases characterized by elastolytic damage to elastin fibers that leads to mechanical failure. To model this, neonatal rat aortic smooth muscle cells were cultured, accumulating an extracellular matrix rich in elastin, and mechanical measurements were made before and during enzymatic digestion of elastin. Specifically, the cells in the cultures were killed with sodium azide, the cultures were lifted from the flask, cut into small strips, and fixed to a computer-controlled lever arm and a force transducer. The strips were subjected to a broadband displacement signal to study the dynamic mechanical properties of the samples. Also, quasi-static stress-strain curves were measured. The dynamic data were fit to a linear viscoelastic model to estimate the tissues' loss (G) and storage (H) modulus coefficients, which were evaluated before and during 30 min of elastase treatment, at which point a failure test was performed. G and H decreased significantly to 30% of their baseline values after 30 min. The failure stress of control samples was approximately 15 times higher than that of the digested samples. Understanding the structure-function relationship of elastin networks and the effects of elastolytic injury on their mechanical properties can lead to the elucidation of the mechanism of elastin fiber failure and evaluation of possible treatments to enhance repair in diseases involving elastolytic injury.     

Transport of horseradish peroxidase by processes of radial glia from the pial surface into the mouse brain

Summary The transport of horseradish peroxidase (HRP) applied to exposed pial surfaces of the brain was studied in newborn, 4-, 7- and 12-day-old, and adult mice. In the telencephalon the cell bodies of radial glia were found to accumulate the tracer. Labeled cells occurred in the subventricular zone of the lateral ventricle during the first postnatal week; they became gradually restricted to an area around the stria terminalis (ventrolateral ventricular corner) by day 12. At later stages no HRP transport could be traced from the surface of the telencephalon. In the cerebellum, HRP was transported from the surface to the cell bodies of Bergmann glia in all age groups studied including adult animals. It is concluded that radial glia and their derivatives share the capacity of transporting material between various cerebrospinal fluid compartments.     

New ichnospecies of Linichnus Jacobsen & Bromley, 2009

Abstract

A new ichnospecies, Linichnus bromleyi, is described on bone substrate as the result of a very likely predator/scavenger interaction. L. bromleyi consists of a single groove with a non-serrated edge. This new ichnotaxon is compared with L. serratus which was defined as a single elongate serrate-edged groove. L. bromleyi has been identified over the surface of bones of marine mammals (in particular, cetaceans and pinnipeds) from two Pliocene outcrops of Andalusia, southern Spain. The new ichnospecies can be clearly related with a trophic interaction between sharks and marine mammals (mainly whales, dolphins and seals).     

Ichnogeny and bivalve bioerosion: examples from shell and wood substrates

Abstract

The ichnospecies Gastrochaneolites dijugus Kelly and Bromley 1984 Kelly, S. R. A., and R. G. Bromley. 1984. “Ichnological Nomenclature of Clavate Borings.” Palaeontology 27: 793–807.[Web of Science ®] , [Google Scholar] and Teredolites longissimus Kelly and Bromley 1984 Kelly, S. R. A., and R. G. Bromley. 1984. “Ichnological Nomenclature of Clavate Borings.” Palaeontology 27: 793–807.[Web of Science ®] , [Google Scholar], attributed to the boring activity of gastrochaenoid and pholadid bivalves, are described respectively from the Miocene Vilanova Basin and the Pliocene Almería-Níjar Basin. Miocene and Pliocene traces are preserved as positive casts associated to invertebrate shells and wood fragments, respectively; in both cases, the host substrate (shells and wood) has been lost almost entirely by different taphonomic processes (mainly dissolution). For the first time in the fossil record, the complete ichnogenetic sequence of these two ichnospecies is described and figured.