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showing 10 items of 38174 documents
A protective role for interleukin 18 in interferon γ-mediated innate immunity to Cryptosporidium parvum that is independent of natural killer cells.
2012
Innate immunity against some intracellular parasitic protozoa involves interleukin 18 (IL-18)-mediated interferon γ (IFN-γ) production by natural killer (NK) cells, but the role of IL-18 in innate resistance to Cryptosporidium infection is unknown. Adult Rag2(-/-)γc(-/-) mice that lack NK cells, T cells, and B cells demonstrated resistance to Cryptosporidium parvum infection that was IFN-γ dependent. Treatment with anti-IL-18-neutralizing antibodies resulted in loss of resistance correlating with reduced intestinal IFN-γ expression. Intestinal mature IL-18 expression increased in vivo during infection and also in the intestinal epithelial cell line CMT-93 following combined IFN-γ treatment/…
Hemocyanin in mollusks--a molecular survey and new data on hemocyanin genes in Solenogastres and Caudofoveata.
2008
The most common respiratory protein of mollusks is the blue, copper-containing hemocyanin (van Holde and Miller, 1995). It is not bound to hemocytes but suspended in the hemolymph. Its molecular mass ranges from 3500 10 to 8000 10 Da (dalton) or even more (Herskovits, 1988). These differences in molecular weight are due to the fact that the basic decamers that constitute the barrel-shaped protein may aggregate to didecamers or multidecameric elongated particles (Herskovits, 1988). In cephalopods and chitons (Polyplacophora), there are exclusively decamers, whereas in protobranch bivalves and gastropods the predominantly observed aggregation state is didecamers (Herskovits, 1988; van Holde a…
Analysis of a soluble lipid-protein complex carrying endogenous 11-cis retinaldehyde from bovine retinal pigment epithelium.
1989
A soluble lipid-protein complex in bovine retinal pigment epithelium is shown to carry endogenous 11-cis retinaldehyde, in the extent of 15% of the total 11-cis retinaldehyde found in this tissue. The complex, analyzed with respect to its chemical composition, exhibits a lipid composition close resembling the lipid composition of the rod outer segment membrane; the SDS-PAGE evidences the presence of a number of protein bands, two of which of 34 and 27 kDa appear glycoproteins. Finally, the lipid-protein complex exhibits a discrete level of a Cathepsin D-like protease activity. From the above, the possibility is discussed that the soluble lipid-protein complex could represent some phagolysos…
A hyaluronic acid/cyclodextrin based injectable hydrogel for local doxorubicin delivery to solid tumors
2020
Localized delivery of anticancer drugs is often the most useful therapeutic approach for the treatment of solid tumors. The use of injectable polymeric systems that maximize drug concentration in the proximal area of the tumor represents an extremely advantageous therapeutic strategy. Here, the development of an injectable in situ forming hydrogel was accomplished by exploiting the azo-type Michael reaction between an amine derivative of hyaluronic and vinylsulfone functionalized -cyclodextrins complexing doxorubicin. This injectable system can be easily prepared and administered with timelines compatible with normal operating room procedures, as demonstrated by rheological tests. In vitro…
Differential regulation of hexameric and dodecameric hemocyanin from A. leptodactylus
2013
The oxygen binding properties of hemocyanins are regulated on a short time scale by effectors such as l-lactate, urate and protons, and on longer time scales by expression of the different types of subunits. For Astacus leptodactylus it was shown previously that acclimation to higher temperatures leads to increased levels of a 6-meric hemocyanin species, whereas at lower temperatures the 12-meric form prevails. Here we show that the temperature dependence of the two forms supports the idea, that the maintenance of high affinity towards oxygen is the driving force for the differential expression of these hemocyanins. Furthermore, the two different types of hemocyanin differ not only in the a…
Production and characterization of the recombinant Sphingomonas chlorophenolica pentachlorophenol 4-monooxygenase.
2001
Abstract Pentachlorophenol 4-monooxygenase (PCP4MO) from Sphingomonas chlorophenolica is a flavoprotein that hydroxylates PCP in the presence of NADPH and oxygen. In order to investigate the structure and function of active site, recombinant PCP4MO (rePCP4MO) was produced in Escherichia coli as a glutathione S-transferase (GST) fusion protein. Moreover, a tobacco etch virus (TEV) protease cleavage site (EKLYFQG) was introduced into GST-PCP4MO and a his-tagged TEV protease was employed. Hence, a two-step purification protocol was developed which allowed obtaining 15–20 mg of rePCP4MO from 1 L culture. The rePCP4MO revealed identity with native enzyme by SDS–PAGE and N-terminal sequence analy…
On the Ultrastructure and Function of Rhogocytes from the Pond Snail Lymnaea stagnalis
2015
Rhogocytes, also termed “pore cells”, occur as solitary or clustered cells in the connective tissue of gastropod molluscs. Rhogocytes possess an enveloping lamina of extracellular matrix and enigmatic extracellular lacunae bridged by cytoplasmic bars that form 20 nm diaphragmatic slits likely to act as a molecular sieve. Recent papers highlight the embryogenesis and ultrastructure of these cells, and their role in heavy metal detoxification. Rhogocytes are the site of hemocyanin or hemoglobin biosynthesis in gastropods. Based on electron microscopy, we recently proposed a possible pathway of hemoglobin exocytosis through the slit apparatus, and provided molecular evidence of a common phylog…
Hydrolytic enzyme activity of Paenibacillus sp. strain B2 and effects of the antagonistic bacterium on cell integrity of two soil-borne pathogenic fu…
2000
Paenibacillus sp. strain B2, isolated from the mycorrhizosphere of Sorghum bicolor and having an antagonistic activity towards soil-borne fungal pathogens, possessed extracellular cellulolytic, proteolytic, chitinolytic and pectinolytic enzyme activities. The eventual role of these lytic enzymes in cellular interactions between Paenibacillus sp. strain B2 and Phytophthora parasitica and Fusariumoxysporum was investigated by electron microscopy and molecular cytology. Electron microscopic observations showed that the presence of Paenibacillus sp. strain B2 resulted in disorganisation of cell walls and/or cell contents of P. parasitica and F. oxysporum. However, when P. parasitica was treated…
Kinetic properties of catecholoxidase activity of tarantula hemocyanin
2008
Phenoloxidases occur in almost all organisms, being essentially involved in various processes such as the immune response, wound healing, pigmentation and sclerotization in arthropods. Many hemocyanins are also capable of phenoloxidase activity after activation. Notably, in chelicerates, a phenoloxidase has not been identified in the hemolymph, and thus hemocyanin is assumed to be the physiological phenoloxidase in these animals. Although phenoloxidase activity has been shown for hemocyanin from several chelicerate species, a characterization of the enzymatic properties is still lacking. In this article, the enzymatic properties of activated hemocyanin from the tarantula Eurypelma californi…
Bacteriophage Adherence to Mucus Mediates Preventive Protection against Pathogenic Bacteria
2019
The mucosal surfaces of animals are habitat for microbes, including viruses. Bacteriophages—viruses that infect bacteria—were shown to be able to bind to mucus. This may result in a symbiotic relationship in which phages find bacterial hosts to infect, protecting the mucus-producing animal from bacterial infections in the process. Here, we studied phage binding on mucus and the effect of mucin on phage-bacterium interactions. The significance of our research is in showing that phage adhesion to mucus results in preventive protection against bacterial infections, which will serve as basis for the development of prophylactic phage therapy approaches. Besides, we also reveal that exposure to m…