The extracellular protease from Pseudomonas fluorescens.

An extracellular protease has been purified from cultures of Pseudomonas fluorescens. It is a metalloenzyme with a molecular weight of 37,000 +/- 3,700, able to digest casein, hemoglobin and gelatine.     

The amino acid composition of histidine ammonialyase fromPseudomonas putida NCIB 10807

Summary The amino acid composition of histidine ammonia-lyase fromPseudomonas putida NCIB 10807 suggests that this enzyme may be different from thePseudomonas testosteroni NCIB 10808 histidine ammonia-lyase, whose amino acid composition is known.Acknowledgment. I wish to thank the Department of Biochemistry and Biophysics, Leeds University, England, for the use of their excellent laboratory facilities.     

Isolation of plant growth regulators fromPseudomonas amygdali

Summary Trans-zeatin and indole-3-acetic acid were isolated, as the main components of the cytokinin and indole mixtures respectively from culture filtrates ofPseudomonas amygdali, the causal agent of hyperplastic bacterial canker of almond.     

The extracellular matrix during heart development

The embryonic extracellular matrix, which is comprised of glycosaminoglycans, glycoproteins, collagens, and proteoglycans, is believed to play multiple roles during heart morphogenesis. Some of these ECM components appear throughout development, however, certain molecules exhibit an interesting transient spatial and temporal distribution. Due to significant new data that have been gathered predominantly in the past 10 years, a comprehensive review of the literature is needed. The intent of this review is to highlight work that addresses mechanisms by which extracellular matrix influences vertebrate heart development.     

The determination of extracellular space using hemoglobin

Summary The ECS of guinea-pig atria and frog sartorii can be determined using hemoglobin. For guinea-pig atria an ECS of (32.2±2.6)% wet wt for frog sartorii an ECS of (12.4±1.0)% wet wt can be measured.This work was supported by the Deutsche Forschungsgemeinschaft SFB 114 Bionach.     

The extracellular matrix of theDictyostelium discoideum slug

In this review, we detail the current understanding of the extracellular matrix (ECM) of the migratory slug phase of the cellular slime mould,Dictyostelium discoideum. We describe some structural and non-structural molecules which comprise the ECM, and how these molecules reflect both plant and animal ECM systems. We also describe zones of the multicellular slug that are known to make ECM components, including the role of the prestalk cells and the slug epithelium-like layer. Finally, we review the contributions of studies on mutant to our understanding of the ECM ofD. discoideum, and relate this to differentiation and development in more complex eukaryotic systems.     

The extracellular matrix of the hematopoietic microenvironment

The bone marrow microenvironment plays an important role in promoting hematopoietic progenitor cell proliferation and differentiation and the controlled egress of these developing hematopoietic cells. The establishment of long-term bone marrow cultures, which are thought to mimic hematopoiesis in vitro, and various stromal cell lines has greatly facilitated the analysis of the functions of this microenvironment. Extracellular matrix (ECM) molecules of all three categories (collagens, proteoglycans and glycoproteins) have been identified as part of this microenvironment and have been shown to be involved in, different biological functions such as cell adhesion and anti-adhesion, binding and presentation of various cytokines and regulation of cell growth. It is suggested that these matrix molecules in combination with cytokines are crucial for compartmentalization of the bone marrow. Although many cell adhesion molecules have been characterized on the surface of hematopoietic progenitor cells, the nature of cellular receptors for the ECM components is less well defined. During leukemia, many immature blood cells are released from bone marrow, but it is not yet known whether these abnormalities in hematopoiesis are also caused by an altered microenvironment or altered composition of its extracellular matrix. The elucidation of the involvement of specific ECM-isoforms and as yet not characterized ECM components and their receptors in the bone marrow will certainly help towards a better understanding of these phenomena.     

Isolation of indole-3-acetic acid methyl ester,a metabolite of indole-3-acetic acid fromPseudomonas amygdali

From the culture filtrates ofPseudomonas amygdali the methyl ester of indole-3-acetic acid (IAA), a product of indole-3-acetic acid metabolism which has the same auxin activity as the free acid, has been isolated. This is the first report of its occurrence as a microbial metabolite.     

Action de la (+)-catéchine surPseudomonas fluorescens

Summary The (+)-catechin stimulates the multiplication and the protidic biosynthesis ofP. fluorescens. Its effect seems related to a modification of the terminal respiratory pathway.     

The ubiquitin-specific protease USP25 interacts with three sarcomeric proteins

The biological functions of the more than one hundred genes coding for deubiquitinating enzymes in the human genome remain mostly unknown. The USP25 gene, located at 21q11.2, encodes three protein isoforms produced by alternative splicing. While two of the isoforms are expressed nearly ubiquituously, the expression of the longer USP25 isoform (USP25m) is restricted to muscular tissues and is upregulated during myogenesis. USP25m interacts with three sarcomeric proteins: actin alpha-1 (ACTA1), filamin C (FLNC), and myosin binding protein C1 (MyBPC1), which are critically involved in muscle differentiation and maintenance, and have been implicated in the pathogenesis of severe myopathies. Biochemical analyses demonstrated that MyBPC1 is a short-lived proteasomal substrate, and its degradation is prevented by over-expression of USP25m but not by other USP25 isoforms. In contrast, ACTA1 and FLNC appear to be stable proteins, indicating that their interaction with USP25m is not related to their turnover rate. Received 7 November 2005; received after revision 7 January 2006; accepted 13 January 2006     

The biology of cell locomotion within three-dimensional extracellular matrix

Cell migration in three-dimensional (3-D) extracellular matrix (ECM) is not a uniform event but rather comprises a modular spectrum of interdependent biophysical and biochemical cell functions. Haptokinetic cell migration across two-dimensional (2-D) surfaces consists of at least three processes: (i) the protrusion of the leading edge for adhesive cell-substratum interactions is followed by (ii) contraction of the cell body and (iii) detachment of the trailing edge. In cells of flattened morphology migrating slowly across 2-D substrate, contact-dependent clustering of adhesion receptors including integrins results in focal contact and stress fiber formation. While haptokinetic migration is predominantly a function of adhesion and deadhesion events lacking spatial barriers towards the advancing cell body, the biophysics of the tissues require a set of cellular strategies to overcome matrix resistance. Matrix barriers force the cells to adapt their morphology and change shape and/or enzymatically degrade ECM components, either by contact-dependent proteolysis or by protease secretion. In 3-D ECM, in contrast to 2-D substrate, the cell shape is mostly bipolar and the cytoskeletal organization is less stringent, frequently lacking discrete focal contacts and stress fibers. Morphologically large spindle-shaped cells (i.e., fibroblasts, endothelial cells, and many tumor cells) of high integrin expression and strong cytoskeletal contractility utilize integrin-dependent migration strategies that are coupled to the capacity to reorganize ECM. In contrast, a more dynamic ameboid migration type employed by smaller cells expressing low levels of integrins (i.e., T lymphocytes, dendritic cells, some tumor cells) is characterized by largely integrin-independent interaction strategies and flexible morphological adaptation to preformed fiber strands, without structurally changing matrix architecture. In tumor invasion and angiogenesis, migration mechanisms further comprise the migration of entire cell clusters or strands maintaining stringent cell-cell adhesion and communication while migrating. Lastly, cellular interactions, enzyme and cytokine secretion, and tissue remodeling provided by reactive stroma cells (i.e. fibroblasts and macrophages) contribute to cell migration. In conclusion, depending on the cellular composition and tissue context of migration, diverse cellular and molecular migration strategies can be developed by different cell types.     

The importance of extracellular calcium for acetylcholine-evoked salivary secretion

Zusammenfassung 5 min nach Beginn der Perfusion der Submandibularisdrüse der Katze mit einer kalziumfreien Flüssigkeit ist die Acetylcholin-induzierte Sekretionsrate nich reduziert, während dieselbe 5 min nach Einführen einer Na-freien Saccharoselösung blockiert ist. Dies zeigt, dass der Sekretionsprozess nicht durch Einströmen von Ca aus dem Extrazellulär- in den Intrazellulärraum ausgelöst wird.

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The technical assistance ofB. Lynderup andG. Pedersen is gratefully acknowledged.     

Proteinaceous cysteine protease inhibitors

Studies of proteinaceous cysteine protease inhibitors originated with the discovery of cystatins in the 1960s. Since that time, a rich and fascinating world of proteins that control and regulate a multitude of important physiological processes, ranging from the basics of protein turnover to development and brain function, has been uncovered. Failures in such important and complex systems inevitably lead to pathologies. Many threatening diseases such as cancer or neurological disorders, to mention only some, are attributed to deregulation of proteaseinhibitor balance. Moreover, important aspects of infection pathology and host defense rely on proteolysis and protease inhibition. Recent advances in the field of protease inhibitors have drawn attention to the possible use of this collected knowledge to control related pathological processes. This review attempts to familiarize the reader with proteinaceous cysteine protease inhibitors by providing an overview of current knowledge. The work primarily highlights biological processes in which the inhibitors are involved and focuses on pathologies resulting from aberrant protease-inhibitor balance, pointing out emerging possibilities for their correction.Received 11 October 2004; received after revision 29 November 2004; accepted 6 December 2004     

The importance of extracellular sodium and potassium for acetylcholine-evoked salivary secretion

Zusammenfassung Es wird gezeigt, dass die Speichelsekretionsrate der perfundierten SubmandibulardrÜse der Katze stark von der Natriumkonzentration im Perfusat abhängt. Die Sekretionsrate wird erhöht bei Perfusion mit kaliumfreier Lösung und reduziert während der Perfusion mit Lösungen erhöhter Kaliumkonzentrationen. Es ist möglich, dass ein durch Acetylcholin induzierter Natriumstrom in die Azinarzellen hinein den Sekretions mechanismus aktiviert.

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With the technical assistance of G.Pedersen.     

A trypsin-like protease in guinea-pig skin

Zusammenfassung Eine der vaso-aktiven Proteinfraktionen, aus Meerschweinchenhautextrakt gewonnen, hydrolisiert Kasein und N-()-benzoyl-l-Arginin Ethyl Ester. Substratspezifität, optimaler pH-Wert und Inaktivierung durch eine speziellen Trypsininhibitor (TLCK) beweisen, dass diese Proteinfraktion eine trypsinähnliche Protease enthält.