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11.
Burckbuchler V Kjøniksen AL Galant C Lund R Amiel C Knudsen KD Nyström B 《Biomacromolecules》2006,7(6):1871-1878
Interactions in semidilute solutions of a hydrophobically modified alginate (HM-alginate) in the presence of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) monomer or a beta-cyclodextrin polymer (poly(beta-CD)) have been characterized at different temperatures with the aid of rheology and small-angle neutron scattering (SANS). The viscosity results for the HM-alginate/HP-beta-CD system reveal progressive deactivation of the hydrophobic associations as the concentration of HP-beta-CD increases. For the HM-alginate/poly(beta-CD) system, on the other hand, addition of poly(beta-CD) sets up bridges between adjacent polymer chains and thereby strengthens the associative network. A novel shear-thickening effect is observed at fairly high shear rates for the HM-alginate/poly(beta-CD) system, and this feature is influenced by temperature. Elevated temperature induces higher chain mobility and the formation of weaker network associations. Analyses of the SANS data disclosed that the association strength in HM-alginate/poly(beta-CD) mixtures increases strongly with increasing cosolute concentration, whereas no effect or a moderate weakening of the strength can be traced in HM-alginate/HP-beta-CD solutions upon addition of HP-beta-CD. The value of the correlation length xi is virtually not affected by the addition of cosolute for the HM-alginate/poly(beta-CD) system, whereas the decoupling of hydrophobic moieties of the polymer upon addition of HP-beta-CD gives rise to a smaller value of xi, suggesting that the size of the heterogeneity patches is reduced. The SANS results suggest that compact association structures are formed in the HM-alginate/poly(beta-CD) solutions. 相似文献
12.
Type IX collagen is a key component of the extracellular matrix of
cartilage where it occurs at the surfaces of type II collagen fibrils as a
glycanated molecule. The function of the glycosaminoglycan (GAG) side chain
of the molecule is, however, unknown. We have shown that type IX collagen
in chicken sternal cartilage is synthesized with a unimodal distribution of
GAG chain size, but at post 17 days of development three predominant
glycanforms of type IX collagen accumulate. Such accumulation did not occur
in sterna from day 15 embryos. In day 17 embryos predominant glycanforms
were found in the caudal region of the sternum. By day 19 of development
the three predominant glycanforms are widespread throughout the caudal and
cephalic regions. The results indicate that developmental and anatomical
changes occur to type IX collagen that depend on the size of the GAG chain
attached to the alpha2(IX) chain of the molecule.
相似文献
13.
Feng B. Quan Christophe Dubessy Sonya Galant Natalia B. Kenigfest Lydia Djenoune Jér?me Leprince Claire Wyart Isabelle Lihrmann Hervé Tostivint 《PloS one》2015,10(3)
Urotensin II (UII) is an evolutionarily conserved neuropeptide initially isolated from teleost fish on the basis of its smooth muscle-contracting activity. Subsequent studies have demonstrated the occurrence of several UII-related peptides (URPs), such that the UII family is now known to include four paralogue genes called UII, URP, URP1 and URP2. These genes probably arose through the two rounds of whole genome duplication that occurred during early vertebrate evolution. URP has been identified both in tetrapods and teleosts. In contrast, URP1 and URP2 have only been observed in ray-finned and cartilaginous fishes, suggesting that both genes were lost in the tetrapod lineage. In the present study, the distribution of urp1 mRNA compared to urp2 mRNA is reported in the central nervous system of zebrafish. In the spinal cord, urp1 and urp2 mRNAs were mainly colocalized in the same cells. These cells were also shown to be GABAergic and express the gene encoding the polycystic kidney disease 2-like 1 (pkd2l1) channel, indicating that they likely correspond to cerebrospinal fluid-contacting neurons. In the hindbrain, urp1-expressing cells were found in the intermediate reticular formation and the glossopharyngeal-vagal motor nerve nuclei. We also showed that synthetic URP1 and URP2 were able to induce intracellular calcium mobilization in human UII receptor (hUT)-transfected CHO cells with similar potencies (pEC50=7.99 and 7.52, respectively) albeit at slightly lower potencies than human UII and mammalian URP (pEC50=9.44 and 8.61, respectively). The functional redundancy of URP1 and URP2 as well as the colocalization of their mRNAs in the spinal cord suggest the robustness of this peptidic system and its physiological importance in zebrafish. 相似文献
14.
Macroautophagy (hereafter autophagy) is a regulated intracellular process during which cytoplasmic cargo engulfed by double-membrane autophagosomes is delivered to the vacuole or lysosome for degradation and recycling. Atg8 that is conjugated to phosphatidylethanolamine (PE) during autophagy plays an important role not only in autophagosome biogenesis but also in cargo recruitment. Conjugation of PE to Atg8 requires processing of the C-terminal conserved glycine residue in Atg8 by the Atg4 cysteine protease. The Arabidopsis plant genome contains 9 Atg8 (AtATG8a to AtATG8i) and 2 Atg4 (AtATG4a and AtATG4b) family members. To understand AtATG4’s specificity toward different AtATG8 substrates, we generated a unique synthetic substrate C-AtATG8-ShR (citrine-AtATG8-Renilla luciferase SuperhRLUC). In vitro analyses indicated that AtATG4a is catalytically more active and has broad AtATG8 substrate specificity compared with AtATG4b. Arabidopsis transgenic plants expressing the synthetic substrate C-AtAtg8a-ShR is efficiently processed by endogenous AtATG4s and targeted to the vacuole during nitrogen starvation. These results indicate that the synthetic substrate mimics endogenous AtATG8, and its processing can be monitored in vivo by a bioluminescence resonance energy transfer (BRET) assay. The synthetic Atg8 substrates provide an easy and versatile method to study plant autophagy during different biological processes. 相似文献
15.
In 59 samples of periphyton and phytoplankton collected in 2002 - 2003 from the Nahal Qishon (Qishon River), northern Israel, we found 178 species from seven divisions of algae and cyanoprocaryotes. Diatoms, clorophytes, and cyanoprocaryotes prevail. Nitzschia and Navicula (Bacillariophyta) are the most abundant. Most of the species are cosmopolitan or widespread, except Lagynion janei (Chrysophyta), which is endemic for the Mediterranean Realm. About 17% of species (26) are new for Israel and five of them represent the first recorded genera: Crinalium endophyticum Crow, Actinocyclus normanii (Gregory) Hustedt, Rhizoclonium hieroglyphicum (Agardh) Kütz (Chlorophyta), Lagynion janei Bourelly, and Stylococcus aureus Chodat. Most of them come from a rare riverine assemblage with red alga Audouinella pygmea, as well as from the estuarine assemblage. Alkaliphiles predominate among the indicators of acidity, with few acidophiles confined to the communities under the impact of industrial wastes. Among the indicators of salinity, most numerous are the oligohalobien-indifferents and species adapted to a moderate salinity level. The relative species richness of ecological groups and the indices of saprobity are correlated with changes in conductivity, pH, and N-nitrate concentration. Indicators of organic pollution fall in the range of betameso- to alfamesosaprobic self-purification grades. Our studies show ecological significance of the Nahal Qishon as a model for a strongly disturbed aquatic ecosystem in the coastal zone of eastern Mediterranean. 相似文献
16.
Francielle Mina Clarissa M. Comim Diogo Dominguini Omar J. Cassol-Jr Dhébora M. Dall`Igna Gabriela K. Ferreira Milena C. Silva Leticia S. Galant Emílio L. Streck João Quevedo Felipe Dal-Pizzol 《Molecular neurobiology》2014,49(2):1069-1076
Sepsis is defined as the host's reaction to infection and characterised by a systemic inflammatory response with important clinical implications. Central nervous system dysfunction secondary to sepsis is associated with local generation of pro- and anti-inflammatory cytokines, impaired cerebral microcirculation, an imbalance of neurotransmitters, apoptosis and cognitive impairment. It's known that the IL-1β is one of the first cytokines to be altered. Thus, the objective of this study was to evaluate the role of IL-1β in cognitive parameters in brain tissue through the use of an IL-1β (IL-1ra) receptor antagonist up to 10 days and to assess blood–brain barrier permeability, cytokine levels, oxidative parameters and energetic metabolism up to 24 h, after sepsis induction. To this aim, we used sham-operated Wistar rats or submitted to the cecal ligation and perforation (CLP) procedure. Immediately after, the animals received one dose of 10 μg of IL-1ra. After 24 h, the rats were killed and were evaluated for biochemical parameters in the pre-frontal cortex, hippocampus and striatum. After 10 days, the animals were submitted to the habituation to the open field and step-down inhibitory avoidance task. We observed that the use of IL-1ra reverted the increase of blood–brain barrier permeability in the pre-frontal cortex, hippocampus and striatum; the increase of IL-1β, IL1-6 and TNF-α levels in the pre-frontal cortex and striatum; the decrease of complex I activity in the pre-frontal, hippocampus and striatum; the increase of oxidative parameters in pre-frontal cortex, hippocampus and striatum; and cognitive impairment. In conclusion, the results observed in this study reinforce the role of acute brain inflammatory response, in particular, the IL1β response, in the cognitive impairment associated with sepsis. 相似文献
17.
Giselli Scaini Meline O. S. Morais Leticia S. Galant Francieli Vuolo Dhébora M. Dall’Igna Matheus A. B. Pasquali Vitor M. Ramos Daniel P. Gelain Jose Claudio F. Moreira Patrícia F. Schuck Gustavo C. Ferreira Francisco G. Soriano Felipe Dal-Pizzol Emilio L. Streck 《Molecular neurobiology》2014,50(2):358-367
Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a severe deficiency in the activity of the branched-chain α-keto acid dehydrogenase complex, leading to accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine, and valine. Infections have a significant role in precipitating acute metabolic decompensation in patients with MSUD; however, the mechanisms underlying the neurotoxicity in this disorder are poorly understood. In this study, we subjected rats to the coadministration of lipopolysaccharide (LPS), which is a major component of gram-negative bacteria cell walls, and high concentrations of BCAA (H-BCAA) to determine their effects on the permeability of the blood–brain barrier (BBB) and on the levels of matrix metalloproteinases (MMP-2 and MMP-9). Our results demonstrated that the coadministration of H-BCAA and LPS causes breakdown of the BBB and increases the levels of MMP-2 and MMP-9 in the hippocampus of these rats. On the other hand, examination of the cerebral cortex of the 10- and 30-day-old rats revealed a significant difference in Evan’s Blue content after coadministration of H-BCAA and LPS, as MMP-9 levels only increased in the cerebral cortex of the 10-day-old rats. In conclusion, these results suggest that the inflammatory process associated with high levels of BCAA causes BBB breakdown. Thus, we suggest that BBB breakdown is relevant to the perpetuation of brain inflammation and may be related to the brain dysfunction observed in MSUD patients. 相似文献
18.
Molecular phylogeny of Neotropical bioluminescent beetles (Coleoptera: Elateroidea) in southern and central Brazil 下载免费PDF全文
Bioluminescence in beetles is found mainly in the Elateroidea superfamily (Elateridae, Lampyridae and Phengodidae). The Neotropical region accounts for the richest diversity of bioluminescent species in the world with about 500 described species, most occurring in the Amazon, Atlantic rainforest and Cerrado (savanna) ecosystems in Brazil. The origin and evolution of bioluminescence, as well as the taxonomic status of several Neotropical taxa in these families remains unclear. In order to contribute to a better understanding of the phylogeny and evolution of bioluminescent Elateroidea we sequenced and analyzed sequences of mitochondrial NADH2 and the nuclear 28S genes and of the cloned luciferase sequences of Brazilian species belonging to the following genera: (Lampyridae) Macrolampis, Photuris, Amydetes, Bicellonycha, Aspisoma, Lucidota, Cratomorphus; (Elateridae) Conoderus, Pyrophorus, Hapsodrilus, Pyrearinus, Fulgeochlizus; and (Phengodidae) Pseudophengodes, Phrixothrix, Euryopa and Brasilocerus. Our study supports a closer phylogenetic relationship between Elateridae and Phengodidae as other molecular studies, in contrast with previous morphologic and molecular studies that clustered Lampyridae/Phengodidae. Molecular data also supported division of the Phengodinae subfamily into the tribes Phengodini and Mastinocerini. The position of the genus Amydetes supports the status of the Amydetinae as a subfamily. The genus Euryopa is included in the Mastinocerini tribe within the Phengodinae/Phengodidae. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
19.
Philip W Fowler Murali K Bollepalli Markus Rapedius Ehsan Nematian-Ardestani Lijun Shang Mark SP Sansom Stephen J Tucker Thomas Baukrowitz 《Channels (Austin, Tex.)》2014,8(6):551-555
In a previous study we identified an extensive gating network within the inwardly rectifying Kir1.1 (ROMK) channel by combining systematic scanning mutagenesis and functional analysis with structural models of the channel in the closed, pre-open and open states. This extensive network appeared to stabilize the open and pre-open states, but the network fragmented upon channel closure. In this study we have analyzed the gating kinetics of different mutations within key parts of this gating network. These results suggest that the structure of the transition state (TS), which connects the pre-open and closed states of the channel, more closely resembles the structure of the pre-open state. Furthermore, the G-loop, which occurs at the center of this extensive gating network, appears to become unstructured in the TS because mutations within this region have a ‘catalytic’ effect upon the channel gating kinetics. 相似文献
20.
S. Aydin H Ozercan F. Dagli S. Aydin O. Dogru S. Celebi O. Akin SP Guzel 《Biotechnic & histochemistry》2005,80(3):163-168
Ghrelin (G-HH) synthesized in several tissues including salivary and stomach glands stimulates appetite in humans by modulating neuropeptide Y neurons in the hypothalamic arcuate nucleus. Loss of appetite is one of the most important symptoms of stomach cancer. We conducted a study using immunohistochemistry to determine whether salivary glands and stomach cancer tissues produce ghrelin. We determined that negative ghrelin immunohistochemistry discriminates tumors from normal tissues and may therefore further our understanding of the clinically important problem of reduced food intake and anorexia in cancer patients. Radioimmunoassay analyses confirmed that cancer cells do not produce a G-HH peptide, whereas normal cells yield this peptide. 相似文献