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1.
L Minghetti G Bartolini M Orlandi M Chiricolo F Licastro C Franceschi V Tomasi 《Biochimica et biophysica acta》1988,958(3):315-322
It has previously been shown that a heat- and acid-stable component of human and animal sera was capable of stimulating prostanoid biosynthesis in human blood monocytes, very probably by a mechanism involving cyclooxygenase induction. Many physico-chemical characteristics of this factor are similar to those of identified platelet factors. Here we show that human platelets are a rich source of this factor (serum monocytotropic factor) and that results from experiments using arachidonic acid or thrombin as releasers are consistent with its presence in platelet membranes. Serum monocytotropic factor has been purified 1500-fold by three chromatographic steps. Purification was more difficult when starting from platelet releasates or lysates. The purified serum monocytotropic factor had an apparent molecular mass of 70,000 as judged by Sephadex G-75 chromatography and by polyacrylamide gel electrophoresis; however, when subjected to HPLC on a gel permeation column in the presence of 6 M urea, one major peak corresponding to a relative molecular mass (Mr) of 30,000-35,000 was observed, which suggests a homodimeric structure. It is therefore very likely that human platelets store, in addition to the two well-identified polypeptide growth factors, platelet-derived growth factor and transforming growth factor-beta, a third polypeptide capable of regulating prostanoid production in monocytes. 相似文献
2.
G Bartolini M Orlandi M Chiricolo L Minghetti F Guerrini M Fidan C Franceschi V Tomasi 《Biochimica et biophysica acta》1986,876(3):486-493
It has previously been shown that platelet-free human monocytes, when properly incubated in the presence of animal and human sera, became capable of producing large amounts of thromboxane A2 and prostaglandin E2. The characteristics of these processes are reported here. Prostaglandin biosynthesis was time and cell concentration dependent; 24 h of incubation at 37 degrees C and 0.5 X 10(6) cells per ml medium were found to give the most reproducible results. Human monocytes produced thromboxane A2 and prostaglandin E2 in a typical ratio which ranged from 2.0 to 5.0 (28 experiments). Animal and human sera were similarly effective, while serum obtained from platelet-free blood was much less active. The activity of all sera tested was stable to heating (100 degrees C for 2-10 min) and extreme pH values (pH 2 and 11). It was unstable when the serum was heated at pH 11 and after 2-mercaptoethanol treatment. These observations prompted us to check the effect of polypeptide growth factors having properties similar to those reported above, such as platelet-derived growth factor, fibroblast growth factor, epidermal growth factor as well as insulin and transferrin. None of these, alone or in various combinations, was capable of eliciting a stimulation comparable with that of serum. Stimulation due to sera was, as expected, dose dependently inhibited by acetylsalicylic acid and more efficiently by indomethacin; unexpectedly it was also inhibited by protein synthesis inhibitors such as actinomycin D and cycloheximide in conditions under which no toxic effect of the drugs was evident. On the basis of these results we conclude that: (a) polypeptide growth factor(s) with a molecular weight at least 30 000 (as judged by Amicon ultrafiltration) is involved in the regulation of prostaglandin biosynthesis); (b) such a factor(s) acts by inducing rather than by activating the cyclooxygenase system. 相似文献
3.
In the setting of an aerobiological study of confined environments and environmental prevention of nosocomial infections, aerobiological monitoring of 22 areas in Montescano Medical Rehabilitation Centre (Pavia) was performed in three different months: February, May, and August, 1994. A Lanzoni 3000 spore trap was used for the monitoring. Examination of the results showed that, in the environments monitored, the indoor presence of fungi increased progressively over the three periods considered. The behaviour of individual genera of fungi differed. In the winter periodPenicillium andAspergillus were the most commonly encountered genera.Cladosporium was the dominant genus from the spring to the summer while the yeasts had their maximum counts in the spring morning. The use of air conditioning, combined with the low air exchange between outdoors and indoors in some of the environments certainly played a part in the low concentrations of these latter aerofungi. 相似文献
4.
Serafina Salvati Lucilla Attorri Lorenzo Malvezzi Campeggi Antonella Olivieri Mariella Sorcini Stefano Fortuna Annita Pintor 《Neurochemical research》1994,19(9):1181-1186
The effect of hypothyroidism on the lipid composition of synaptosomes, density and affinity of muscarinic receptor sites, and acetylcholinesterase activity in the cerebral cortex of young and aged rats was investigated. The animals were made hypothyroid by adding 0.05% propyl-2-thiouracil to their drinking water for four weeks. This pathological state induced an increase in the relative percentage of sphingomyelin in young rats. In aged rats hypothyroidism induced a decrease of sphingomyelin and glycerophosphocholine and an increase of cholesterol. The effect of hypothyroid state on cerebral cortex resulted in an increase of acethylcholinesterase activity both in young and aged rats and was also reflected in an increase of density of M1-AChRs but only in the former. 相似文献
5.
Dall'Olio Fabio; Mariani Erminia; Tarozzi Andrea; Meneghetti Alessandra; Chiricolo Mariella; Lau Joseph T. Y.; Facchini Andrea 《Glycobiology》1997,7(4):507-513
The extent of processing of N-linked oligosaccharides and thesialylation of the target cell membranes has been positivelycorrelated with resistance to lysis mediated by NK cells, buta conclusive evidence has never been reached. Colon cancer tissuesexpress an increased activity of ß-ga-lactoside 相似文献
6.
Inbok Paek Lelio Orci Mariella Ravazzola Hediye Erdjument-Bromage Mylene Amherdt Paul Tempst Thomas H. S?llner James E. Rothman 《The Journal of cell biology》1997,137(5):1017-1028
We report the identification and characterization of ERS-24 (Endoplasmic Reticulum SNARE of 24 kD), a new mammalian v-SNARE implicated in vesicular transport between the ER and the Golgi. ERS24 is incorporated into 20S docking and fusion particles and disassembles from this complex in an ATP-dependent manner. ERS-24 has significant sequence homology to Sec22p, a v-SNARE in Saccharomyces cerevisiae required for transport between the ER and the Golgi. ERS-24 is localized to the ER and to the Golgi, and it is enriched in transport vesicles associated with these organelles.Newly formed transport vesicles have to be selectively targeted to their correct destinations, implying the existence of a set of compartment-specific proteins acting as unique receptor–ligand pairs. Such proteins have now been identified (Söllner et al., 1993a
; Rothman, 1994): one partner efficiently packaged into vesicles, termed a v-SNARE,1 and the other mainly localized to the target compartment, a t-SNARE. Cognate pairs of v- and t-SNAREs, capable of binding each other specifically, have been identified for the ER–Golgi transport step (Lian and Ferro-Novick, 1993; Søgaard et al., 1994), the Golgi–plasma membrane transport step (Aalto et al., 1993; Protopopov et al., 1993; Brennwald et al., 1994) in Saccharomyces cerevisiae, and regulated exocytosis in neuronal synapses (Söllner et al., 1993a
; for reviews see Scheller, 1995; Südhof, 1995). Additional components, like p115, rab proteins, and sec1 proteins, appear to regulate vesicle docking by controlling the assembly of SNARE complexes (Søgaard et al., 1994; Lian et al., 1994; Sapperstein et al., 1996; Hata et al., 1993; Pevsner et al., 1994).In contrast with vesicle docking, which requires compartment-specific components, the fusion of the two lipid bilayers uses a more general machinery derived, at least in part, from the cytosol (Rothman, 1994), which includes an ATPase, the N-ethylmaleimide–sensitive fusion protein (NSF) (Block et al., 1988; Malhotra et al., 1988), and soluble NSF attachment proteins (SNAPs) (Clary et al., 1990; Clary and Rothman, 1990; Whiteheart et al., 1993). Only the assembled v–t-SNARE complex provides high affinity sites for the consecutive binding of three SNAPs (Söllner et al., 1993b
; Hayashi et al., 1995) and NSF. When NSF is inactivated in vivo, v–t-SNARE complexes accumulate, confirming that NSF is needed for fusion after stable docking (Søgaard et al., 1994).The complex of SNAREs, SNAPs, and NSF can be isolated from detergent extracts of cellular membranes in the presence of ATPγS, or in the presence of ATP but in the absence of Mg2+, and sediments at ∼20 Svedberg (20S particle) (Wilson et al., 1992). In the presence of MgATP, the ATPase of NSF disassembles the v–t-SNARE complex and also releases SNAPs. It seems likely that this step somehow initiates fusion.To better understand vesicle flow patterns within cells, it is clearly of interest to identify new SNARE proteins. Presently, the most complete inventory is in yeast, but immunolocalization is difficult in yeast compared with animal cells, and many steps in protein transport have been reconstituted in animal extracts (Rothman, 1992) that have not yet been developed in yeast. Therefore, it is important to create an inventory of SNARE proteins in animal cells. The most unambiguous and direct method for isolating new SNAREs is to exploit their ability to assemble together with SNAPs and NSF into 20S particles and to disassemble into subunits when NSF hydrolyzes ATP. Similar approaches have already been successfully used to isolate new SNAREs implicated in ER to Golgi (Søgaard et al., 1994) and intra-Golgi transport (Nagahama et al., 1996), in addition to the original discovery of SNAREs in the context of neurotransmission (Söllner et al., 1993a
).Using this method, we now report the isolation and detailed characterization of ERS-24 (Endoplasmic Reticulum SNARE of 24 kD), a new mammalian v-SNARE that is localized to the ER and Golgi. ERS-24 is found in transport vesicles associated with the transitional areas of the ER and with the rims of Golgi cisternae, suggesting a role for ERS-24 in vesicular transport between these two compartments. 相似文献
7.
Crystal structure of the receptor-binding protein head domain from Lactococcus lactis phage bIL170
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Ricagno S Campanacci V Blangy S Spinelli S Tremblay D Moineau S Tegoni M Cambillau C 《Journal of virology》2006,80(18):9331-9335
Lactococcus lactis, a gram-positive bacterium widely used by the dairy industry, is subject to lytic phage infections. In the first step of infection, phages recognize the host saccharidic receptor using their receptor binding protein (RBP). Here, we report the 2.30-A-resolution crystal structure of the RBP head domain from phage bIL170. The structure of the head monomer is remarkably close to those of other lactococcal phages, p2 and TP901-1, despite any sequence identity with them. The knowledge of the three-dimensional structures of three RBPs gives a better insight into the module exchanges which have occurred among phages. 相似文献
8.
Thiago F. Rodrigues Aline M. B. Mantellatto Mariella Superina Adriano G. Chiarello 《Biological reviews of the Cambridge Philosophical Society》2020,95(1):1-21
Awareness of the natural ecological processes provided by organisms that benefit human well‐being has significantly progressed towards the goal of making conservation a mainstream value. Identifying different services and the species that provide them is a vital first step for the management and maintenance of these so‐called ecosystem services. Herein, we specifically address the armadillos, which play key functional roles in terrestrial ecosystems, including as ecosystem engineers, predators, and vectors of invertebrates and nutrients, although these roles have often been overlooked. Armadillos can control pests, disperse seeds, and be effective sentinels of potential disease outbreaks or bioindicators of environmental contaminants. They also supply important material (meat, medicines) and non‐material (learning, inspiration) contributions all over the Americas. We identify key gaps in the understanding of ecosystem services provided by armadillos and areas for future research required to clarify their functional role in terrestrial ecosystems and the services they supply. Such information will produce powerful arguments for armadillo conservation. 相似文献
9.
10.
Unfolding and refolding of porcine odorant binding protein in guanidinium hydrochloride: equilibrium studies at neutral pH 总被引:1,自引:0,他引:1
Parisi M Mazzini A Sorbi RT Ramoni R Grolli S Favilla R 《Biochimica et biophysica acta》2003,1652(2):115-125
Unfolding and refolding studies on porcine odorant binding protein (pOBP) have been performed at pH 7 in the presence of guanidinium hydrochloride (GdnHCl). Unfolding, monitored by following changes of protein fluorescence and circular dichroism (CD), was found to be a reversible process, in terms of recovered structure and function. The equilibrium transition data were fitted by a simple two-state sigmoidal function of denaturant concentration and the thermodynamic folding parameters, derived from the two techniques, were very similar (average values: C(1/2) approximately 2.4 M, m approximately 2 kcal mol(-1) M(-1), DeltaG(unf,w)(0) approximately 4.7 kcal mol(-1)). The transition was independent of protein concentration, indicating that only monomeric species are involved. Only a minor protective effect by the fluorescent ligand 1-amino-anthracene (AMA) against protein unfolding was detected, whereas dihydromyrcenol (DHM) stabilised the protein to a larger extent (DeltaC(1/2) approximately 0.5 M). Refolding was complete, when the protein, denatured with GdnHCl, was diluted with buffer. On the other hand, refolding by dialysis was largely prevented by concomitant aggregation. The present results on pOBP are compared with those on bovine OBP (bOBP) [Biochim. Biophys. Acta 1599 (2002) 90], where subunit folding is accompanied by domain swapping. We finally suggest that the generally observed two-state folding of many lipocalins is probably favoured by their beta-barrel topology. 相似文献