Home About us Contact
|
Home About us Contact | ||
|
|
||
Secretory System (secretory + system)
Selected AbstractsExpression and secretion of an ,-amylase gene from a native strain of Bacillus licheniformis in Escherichia coli by T7 promoter and putative signal peptide of the geneJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2003M. Shahhoseini Abstract The gene encoding a hyperthermostable , -amylase from a Bacillus licheniformis native strain was cloned in pET24d transcription vector containing T7 promoter, and expressed in Escherichia coli BL21(DE3) cells. Having confirmed the , -amylase activity through activity staining method on SDS,PAGE gel, the yields of production were determined in two separated intra and inter-cellular phases and compared using enzymatic assay methods. Extracellular production of the active recombinant enzyme implies the recognition of the putative signal peptide of this Bacillus sp. by E. coli secretory system. This may be because of the amino acid sequence of this signal peptide which covers all the structural parameters of a standard signal peptide processed by Lep B, the major signal peptidase in E. coli secretory system. This study recommends the use of this signal peptide for extracellular production of other foreign proteins in E. coli. [source] Tissue-engineered tear secretory system: Functional lacrimal gland acinar cells cultured on matrix protein-coated substrataJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Shivaram Selvam Abstract Dry eye is a general term that refers to a myriad of ophthalmic disorders resulting in the inadequate wetting of the corneal surface by the tear film. Dry eyes are typically treated by the application of artificial tears. However, patients with lacrimal insufficiencies such as Stevens-Johnson syndrome, chemical and thermal injuries, or ocular cicatricial pemphigoid have very limited options because of the short duration and action of lubricating agents. As a therapeutic strategy, we are working to develop a bioengineered tear secretory system for such patients. This article describes the growth and physiological properties of purified rabbit lacrimal gland acinar cells (pLGACs) on several matrix protein-coated polymers such as silicone, collagen I, copolymers of poly- D,L -lactide- co -glycolide (PLGA; 85:15 and 50:50), poly- L -lactic acid (PLLA), and Thermanox® plastic cell culture coverslips. Monolayers of acinar cells were established on all of the polymeric substrata. An assay of ,-hexosaminidase activity in the supernatant medium showed significant increases in protein secretion, following stimulation with 100 ,M carbachol on matrix protein-coated and uncoated polymers such as silicone, PLGA 85:15, and PLLA. Our study demonstrates that PLLA supported the morphological and physiological properties of purified rabbit lacrimal gland epithelial cells more successfully than the others. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Evolution of Protein Targeting into "Complex" Plastids: The "Secretory Transport Hypothesis"PLANT BIOLOGY, Issue 4 2003O. Kilian Abstract: In algae different types of plastids are known, which vary in pigment content and ultrastructure, providing an opportunity to study their evolutionary origin. One interesting feature is the number of envelope membranes surrounding the plastids. Red algae, green algae and glaucophytes have plastids with two membranes. They are thought to originate from a primary endocytobiosis event, a process in which a prokaryotic cyanobacterium was engulfed by a eukaryotic host cell and transformed into a plastid. Several other algal groups, like euglenophytes and heterokont algae (diatoms, brown algae, etc.), have plastids with three or four surrounding membranes, respectively, probably reflecting the evolution of these organisms by so-called secondary endocytobiosis, which is the uptake of a eukaryotic alga by a eukaryotic host cell. A prerequisite for the successful establishment of primary or secondary endocytobiosis must be the development of suitable protein targeting machineries to allow the transport of nucleus-encoded plastid proteins across the various plastid envelope membranes. Here, we discuss the possible evolution of such protein transport systems. We propose that the secretory system of the respective host cell might have been the essential tool to establish protein transport into primary as well as into secondary plastids. [source] Photosynthetic Eukaryotes of Freshwater Wetland Biofilms: Adaptations and Structural Characteristics of the Extracellular Matrix in the Green Alga, Cosmarium reniforme (Zygnematophyceae, Streptophyta)THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 4 2009DAVID S. DOMOZYCH ABSTRACT. Cosmarium reniforme (Zygnematophyceae, Streptophyta) is a green alga that is commonly found in biofilms of wetlands of the Adirondack region, NY (USA). Two distinctive characteristics that are critical to this alga's survival in a benthic biofilm are its elaborate cell morphology and extracellular matrix (ECM). In this study, ultrastructural, immunocytochemical, and experimental methodologies were employed in order to elucidate the cellular characteristics that are critical for survival in a biofilm. The ECM consists of a thick, outwardly lobed cell wall (CW), which contains a patterned network of structurally complex pores. Each pore consists of a narrow channel, terminating internally at a bulb that invaginates localized regions of the plasma membrane. The outer region of the pore contains arabinogalactan protein-like and extensin epitopes that are likely involved in adhesion mechanisms of the cell. External to the CW is the extracellular polymeric substance that is employed in ensheathment of the cell to the substrate and in gliding motility. The architectural design/biochemical make-up of the CW and a secretory system that encompasses the coordinated activities of the endomembrane and cytomotile/cytoskeletal systems provide the organism with effective mechanisms to support life within the biofilm complex. [source] Modulation of insulin release by adenosine A1 receptor agonists and antagonists in INS-1 cells: The possible contribution of 86Rb+ efflux and 45Ca2+ uptakeCELL BIOCHEMISTRY AND FUNCTION, Issue 8 2008M. Töpfer Abstract Due to the lack of specific agonists and antagonists the role of adenosine receptor subtypes with respect to their effect on the insulin secretory system is not well investigated. The A1 receptor may be linked to different 2nd messenger systems, i.e. cAMP, K+ - and 45Ca2+ channel activity. Partial A1 receptor agonists are going to be developed in order to improve diabetes (increase in insulin sensitivity, lowering of FFA and triglycerides). In this study newly synthesized selective A1 receptor agonists and antagonists were investigated thereby integrating three parameters, insulin release (RIA), 45Ca2+ uptake and 86Rb+ efflux (surrogate for K+ efflux) of INS-1 cells, an insulin secretory cell line. The presence of A1 -receptors was demonstrated by Western blotting. The receptor nonselective adenosine analogue NECA (5,- N -ethylcarboxyamidoadenosine) at high concentration (10,µM) had no effect on insulin release and 45Ca2+ uptake which could be interpreted as the sum of effects mediated by mutual antagonistic adenosine receptor subtypes. However, an inhibitory effect mediated by A1 receptor agonism was detected at 10,nM NECA and could be confirmed by adding the A1 receptor antagonist PSB-36 (1-butyl-8-(3-noradamantyl)-3-(3-hydroxy-propyl)xanthine). NECA inhibited 86Rb+ efflux which, however, did not fit with the simultaneous inhibition of insulin secretion. The selective A1 receptor agonist CHA (N6 -cyclohexyladenosine) inhibited insulin release; the simultaneously increased Ca2+ uptake (nifedipine dependent) and inhibition of 86Rb+ efflux did not fit the insulin release data. The CHA effect (even the maximum effect at 50,µM) can be increased by 10,µM NECA indicating that CHA and NECA have nonspecific and physiologically non-relevant effects on 86Rb+ efflux in addition to their A1 -receptor interaction. Since PSB-36 did not influence the NECA-induced inhibition of 86Rb+ efflux, the NECA effect is not mediated by potassium channel-linked A1 receptors. The nonselective adenosine receptor antagonist caffeine increased insulin release which was reversed by CHA as expected when hypothesizing that both act via A1 receptors in this case. In conclusion, stimulation of A1 receptors by receptor selective and nonselective compounds reduced insulin release which is not coupled to opening of potassium channels (86Rb+ efflux experiments) or inhibition of calcium channels (45Ca2+ uptake experiments). It may be expected that of all pleiotropic 2nd messengers, the cAMP system (not tested here) is predominant for A1 receptor effects and the channel systems (K+ and Ca2+) are of minor importance and do not contribute to insulin release though being coupled to the receptor in other tissues. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||