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181.
Troy S Soty M Ribeiro L Laval L Migrenne S Fioramonti X Pillot B Fauveau V Aubert R Viollet B Foretz M Leclerc J Duchampt A Zitoun C Thorens B Magnan C Mithieux G Andreelli F 《Cell metabolism》2008,8(3):201-211
Unlike the adjustable gastric banding procedure (AGB), Roux-en-Y gastric bypass surgery (RYGBP) in humans has an intriguing effect: a rapid and substantial control of type 2 diabetes mellitus (T2DM). We performed gastric lap-band (GLB) and entero-gastro anastomosis (EGA) procedures in C57Bl6 mice that were fed a high-fat diet. The EGA procedure specifically reduced food intake and increased insulin sensitivity as measured by endogenous glucose production. Intestinal gluconeogenesis increased after the EGA procedure, but not after gastric banding. All EGA effects were abolished in GLUT-2 knockout mice and in mice with portal vein denervation. We thus provide mechanistic evidence that the beneficial effects of the EGA procedure on food intake and glucose homeostasis involve intestinal gluconeogenesis and its detection via a GLUT-2 and hepatoportal sensor pathway. 相似文献
182.
Andrea C. Highfield Aliya El Nagar Luke C. M. Mackinder Laure M.-L. J. No?l Matthew J. Hall Stephen J. Martin Declan C. Schroeder 《Applied and environmental microbiology》2009,75(22):7212-7220
The worldwide decline in honeybee colonies during the past 50 years has often been linked to the spread of the parasitic mite Varroa destructor and its interaction with certain honeybee viruses. Recently in the United States, dramatic honeybee losses (colony collapse disorder) have been reported; however, there remains no clear explanation for these colony losses, with parasitic mites, viruses, bacteria, and fungal diseases all being proposed as possible candidates. Common characteristics that most failing colonies share is a lack of overt disease symptoms and the disappearance of workers from what appears to be normally functioning colonies. In this study, we used quantitative PCR to monitor the presence of three honeybee viruses, deformed wing virus (DWV), acute bee paralysis virus (ABPV), and black queen cell virus (BQCV), during a 1-year period in 15 asymptomatic, varroa mite-positive honeybee colonies in Southern England, and 3 asymptomatic colonies confirmed to be varroa mite free. All colonies with varroa mites underwent control treatments to ensure that mite populations remained low throughout the study. Despite this, multiple virus infections were detected, yet a significant correlation was observed only between DWV viral load and overwintering colony losses. The long-held view has been that DWV is relatively harmless to the overall health status of honeybee colonies unless it is in association with severe varroa mite infestations. Our findings suggest that DWV can potentially act independently of varroa mites to bring about colony losses. Therefore, DWV may be a major factor in overwintering colony losses.Deformed wing virus (DWV), acute bee paralysis virus (ABPV), and black queen cell virus (BQCV) are single-stranded positive-sense RNA viruses of the order Picornavirales and are regularly detected in honeybee populations in the United Kingdom (1). ABPV has been assigned to the family Dicistroviridae and is known to follow a classic acute-type infection strategy since relatively low loads (103 to 106 viruses per honeybee) can rapidly translate into overt symptoms of paralysis and ultimately death for the honeybee, depending on the mode of transmission (6, 33). ABPV shares >92% sequence homology with other members of the family Dicistroviridae, Kashmir bee virus and Israeli acute paralysis virus, across the eight conserved domains of the RNA-dependent RNA polymerase gene, and it has been proposed that these viruses have recently diverged and are variants of each other (7). Advances in the study of this proposed ABPV complex is revealing the significant impact these viruses may have on honeybee colonies on a global scale. For example, a recent study in the United States has observed a correlation between Israeli acute paralysis virus and colony collapse disorder (17). That said, other agents, including bacteria and microsporidia, have also been proposed as important factors in the onset of colony loss (25, 27).BQCV is similar to ABPV in that it, too, follows a typical acute infection strategy. This virus is known to infect honeybee queen cell larvae, causing the larvae to discolor and die (5). It has been shown to be associated with the microsporidian Nosema apis (4) although whether N. apis has a direct role in the transmission of this virus still needs to be determined. Both ABPV and BQCV have been detected in worker honeybees and pupae (38), and the viruses are transmitted orally, via food and feeding activities (14). BQCV has also been detected in queen honeybees (13), suggesting that vertical transmission is also important for this virus. Both BQCV (12) and ABPV (38) have been detected within the varroa mite; however, only ABPV (9) has been shown to be vectored by varroa mites and has been found associated with dead colonies infested with varroa mites in Germany, Russia, and the United States (1). Later modeling work (33) indicated that very large (10,000+) mite populations are required to kill a colony since it is difficult for ABPV to become established among the bee population due to its high virulence.DWV is currently designated as a member of the unassigned genus Iflavirus within the order Picornavirales. It is generally considered as less virulent than ABPV or Kashmir bee virus, but it is known to cause overt symptoms of wing deformities in developing honeybees, resulting in emerging honeybees that are unable to fly and die shortly (5). It is also speculated that a cloud of DWV sequence variants exists that have evolved from a common ancestor. This is due to the high sequence similarities DWV isolates share with Kakugo virus and Varroa destructor virus within the RNA-dependent RNA polymerase gene, yet differences in virus epidemiology and pathological effects distinguish them from each other (29). DWV has been detected in worker honeybees, pupae, larvae, drones, and queens (15, 18, 20) as well as within the varroa mite (38, 43) and more recently the mite Tropilaelaps mercedesae (21), implying a range of horizontal and vertical transmission routes. Despite their global occurrence, it is generally accepted that DWVs play a secondary role in the causes of honeybee disease compared to their parasitic and bacterial counterparts as the viruses routinely reside at low levels in colonies, with symptomatic infections being rare (5). Moreover, multiple variants with differing infection strategies can account for a lack of discernible symptoms.Whether these viruses follow a persistent, latent, inapparent, or progressive infection strategy still remains unclear. Persistent (often called chronic) infections imply that the rate of infection within a host is in balance with the reproduction rate of the infected cell type or host itself. This is achieved through a combination of changing virus replication and host immune responses. Latent infections occur when the virus lies dormant within the host (replication inactive) until activation by defined stimuli. Progressive infections are caused by viruses that enter the host cell and replicate undetected for many cellular generations over many years before manifesting overt or acute symptoms. These three infection strategies all evade the host immune system, which results in the inability of the host to fully expel the virus, and this inability is often lethal. Inapparent (often referred to as covert) infections are indicative of a highly evolved relationship between the virus and natural host. Moreover, these infections are distinct in that the natural host can eventually clear itself from this short-term infection (19). Infections of DWV are often described as inapparent (15); however, Yue et al. (44) have suggested that a distinction should be made between “true inapparent” and their newly defined “covert infection” based on the long-term nature of DWV infection in honeybee colonies and on the nature of its transmission. This conclusion is congruent with current knowledge that traditional serological screening methods for DWV have limitations in their sensitivity (20). Therefore, the presence and duration of DWV within colonies have often been underestimated using serological assays as the overt symptoms of the deformed wing phenotype (>1011 virions per honeybee) are short-lived. Advances in virus detection methodologies have enabled the development of more sensitive techniques, such as PCR, and this has demonstrated that DWV persists for longer periods within colonies (38). However, based on the current research evidence, a case could be made that DWV actually follows the classic persistent infection strategy.DWV is thought to have an intricate relationship with varroa mites such that immunosuppression of the honeybee pupae by the mites results in increased DWV amplification when the honeybees are exposed to other pathogens (42). It has additionally been shown that the number of mites parasitizing honeybee pupae is positively correlated with the probability of their developing malformed wings (10). Other findings indicate that DWV replication within the mite and subsequent transmission to developing honeybees lead to the increased likelihood of the bees'' emerging with wing deformities (24, 43). Taken together, the expectation is that DWV-associated colony collapse would typically occur in the presence of a large (>2,000) varroa mite infestation carrying high levels of DWV and with a high proportion of deformed honeybees. While the effect of varroa mite-induced DWV disease is well recognized, i.e., wing deformities coupled with downregulation of immunity-related genes and antimicrobial peptides (36, 42) and impaired learning behavior (28), the impact of non-varroa mite-vectored DWV within asymptomatic honeybees still needs to be realized. Moreover, it was recently reported that varroa mite-free bumblebees that tested positive for DWV actually showed symptoms of DWV infection (23). Even though these bumblebees were in close proximity to DWV-infected and varroa mite-infested honeybee colonies, it is evidence that the dependency of DWV on varroa mite vectoring for a symptomatic infection (manifested as classic wing deformities or other symptoms) may not be as critical as previously thought.The purpose of this study was to investigate asymptomatic viral dynamics within husbanded honeybee colonies over an annual cycle. We set out to observe the relationship, if any, between virus infections, varroa mite parasitism and vectoring, honeybee colony health, and colony longevity. For the first time, a quantitative analysis of three picorna-like honeybee viruses over the course of a year was undertaken for DWV, ABPV, and BQCV. 相似文献
183.
Ingrid Bourgeois Emilie Camiade Raja Biswas Pascal Courtin Laure Gibert Friedrich Götz Marie-Pierre Chapot-Chartier Jean-Louis Pons & Martine Pestel-Caron 《FEMS microbiology letters》2009,290(1):105-113
The nucleotide sequence of atlL , a gene encoding a putative Staphylococcus lugdunensis peptidoglycan hydrolase, was determined using degenerate consensus PCR and genome walking. This 3837-bp gene encodes a protein, AtlL, that appears as a putative bifunctional autolysin with a 29-amino acid putative signal peptide and two enzymatic putative centres ( N -acetylmuramoyl- l -alanine amidase and N -acetylglucosaminidase) interconnected with three imperfect repeated sequences displaying glycine–tryptophan motifs. In order to determine whether both lytic domains were functional, and verify their exact enzymatic activities, gene fragments harbouring both putative domains, AM ( N -acetylmuramoyl- l -alanine amidase enzymatic centre plus two repeated sequences) and GL ( N -acetylglucosaminidase enzymatic centre plus one repeated sequence), were isolated, subcloned, and expressed in Escherichia coli . Purified recombinant AM and GL protein truncations exhibited cell wall lytic activity in zymograms performed with cell walls of Micrococcus lysodeikticus, Bacillus subtilis , and S. lugdunensis. AtlL is expressed during the whole growth, with an overexpression in the early-exponential stage. Liquid chromatography-mass spectrometry analysis of muropeptides generated by digestion of B. subtilis cell walls demonstrated the hydrolytic bond specificities and confirmed both of the acetyl domains' activities as predicted by sequence homology data. AtlL is the first autolysin described in S. lugdunensis , with a bifunctional enzymatic activity involved in peptidoglycan hydrolysis. 相似文献
184.
Due to an increasing emphasis for fish population survey and regulation, efficient tools for evaluating the abundance and
diversity of fish from various life stages are needed, especially for coral reef species that present a high taxonomic diversity.
The characteristics of six different techniques used for sampling pelagic larvae (a plankton-net and two light-traps), newly
settled juveniles (one type of artificial reef), and older juveniles (an underwater seine net in seagrass and macroalgal beds,
and rotenone poisoning in coral patches) are described in this study. Larvae belonging to 70 families and juveniles belonging
to 34 families were collected. An analysis of similarity (ANOSIM) showed that the taxonomic composition of assemblages collected
with the plankton-net and the two light-traps were overlapping but clearly different, due to the higher occurrence of Gobiidae
in the plankton-net and of Pomacentridae in both light-traps. Larvae being 2–4 mm standard length (SL) dominated in the plankton-net,
whereas larvae being 9–11 mm SL dominated in both light-traps. Pomacentridae juveniles were more abundant in rotenone samples,
whereas Labridae dominated in the underwater seine. Juvenile fish collected with the artificial reefs, the underwater seine,
and rotenone poisoning largely overlapped in size, with mean sizes of 22, 38, and 33 mm SL, respectively. Seven families were
caught by the six sampling techniques, but with unequal success. This study provides ecologists and managers with a unique
review of six techniques for sampling a wide range of developmental stages of young fish in different habitats of a coral
reef lagoon.
相似文献
Laure CarassouEmail: |
185.
186.
Laure M.-L.J. Noël Steve J. Hawkins Stuart R. Jenkins Richard C. Thompson 《Journal of experimental marine biology and ecology》2009,370(1-2):9-17
Differences between rockpool and emergent rock communities are often attributed to their contrasting physical conditions. However, differences in grazing pressure between rockpools and open rock could also exert an important structuring role. Greater densities and/or the lack of tidal constraints on foraging may allow grazing intensity to be greater in rockpools. Here, wax discs were deployed to compare grazing intensity between rockpool and emergent rock habitats at each of three tidal heights on a moderately exposed shore in SW England. Grazing intensity was then examined in relation to herbivore density. Grazing intensity in pools was twice that on emergent rock, despite a lower density of herbivores in the rockpools. Of these herbivores, patellid limpets are the dominant grazers on rocky shores throughout the NE Atlantic and are recognised to have a major role in structuring intertidal communities. Thus, subsequent experiments focussed on the influence of limpets in determining the differences in consumer pressure between rockpools and emergent rock. Three alternative explanations were considered: (1) the effect of continuous immersion on grazing intensity in rockpools; (2) differences in limpet species abundance between the two habitats; (3) movement of limpets from emergent rock into pools to feed. The level of grazing pressure exerted by Patella ulyssiponensis (Gmelin), the predominant species living constantly immersed in rockpools, was similar to that of P. vulgata (Linnaeus) which is predominantly found on emergent rock. P. vulgata were observed moving from emergent rock into rockpools during high tide. Manipulative experiments confirmed that these foraging excursions resulted in a 2-fold increase in grazing intensity in the pools. Grazing activity of P. vulgata in rockpools was not consistent between sites and may be influenced by differences in wave exposure and/or the abundance of microbial resources. Elevated consumer pressure in rockpools may be an important factor influencing algal assemblages and probably explains the predominance of grazer resistant-species in these pools. 相似文献
187.
A detailed analysis of Bupleurum fruticosum oil was carried out by combination of GC (RI), GC/MS, and 13C‐NMR analyses. After fractionation by column chromatography, 34 components accounting for 97.8% of the oils were identified. The main component was β‐phellandrene (67.7%), followed by sabinene (9.3%), and limonene (5.6%). The evolution of the chemical composition according to the stages of development of the plant was investigated as well as the composition of leaf, twig, and flower oils. A solvent‐free microwave extraction (SFME) of aerial parts was carried out and the composition of the extract compared with that of the essential oil. Finally, 57 oil samples isolated from aerial parts of individual plants, collected all around Corsica, were analyzed, and the data were submitted to statistical analysis. Although the contents of the main components varied, only one group emerged, accompanied with some atypical compositions. 相似文献
188.
Christophe Marguet Marc Lubrano Marie Gueudin Pascal Le Roux Antoine Deschildre Chantal Forget Laure Couderc Daniel Siret Marie-Dominique Donnou Michael Bubenheim Astrid Vabret Fran?ois Freymuth 《PloS one》2009,4(2)
Background
RT amplification reaction has revealed that various single viruses or viral co-infections caused acute bronchiolitis in infants, and RV appeared to have a growing involvement in early respiratory diseases. Because remaining controversial, the objective was to determine prospectively the respective role of RSV, RV, hMPV and co-infections on the severity of acute bronchiolitis in very young infants.Methods and Principal Findings
209 infants (median age: 2.4 months) were enrolled in a prospective study of infants <1 year old, hospitalized for a first episode of bronchiolitis during the winter epidemic season and with no high risk for severe disease. The severity was assessed by recording SaO2% at admission, a daily clinical score (scale 0–18), the duration of oxygen supplementation and the length of hospitalization. Viruses were identified in 94.7% by RT amplification reaction: RSV only (45.8%), RV only (7.2%), hMPV only (3.8%), dual RSV/RV (14.3%), and other virus only (2%) or coinfections (9%). RV compared respectively with RSV and dual RSV/RV infection caused a significant less severe disease with a lower clinical score (5[3.2–6] vs. 6[4–8], p = 0.01 and 5.5[5–7], p = 0.04), a shorter time in oxygen supplementation (0[0–1] days vs. 2[0–3] days, p = 0.02 and 2[0–3] days, p = 0.03) and a shorter hospital stay (3[3–4.7] days vs.6 [5–8] days, p = 0.001 and 5[4–6] days, p = 0.04). Conversely, RSV infants had also longer duration of hospitalization in comparison with RSV/RV (p = 0.01) and hMPV (p = 0.04). The multivariate analyses showed that the type of virus carried was independently associated with the duration of hospitalization.Conclusion
This study underlined the role of RV in early respiratory diseases, as frequently carried by young infants with a first acute bronchiolitis. RSV caused the more severe disease and conversely RV the lesser severity. No additional effect of dual RSV/RV infection was observed on the severity. 相似文献189.
Sabine Pereyre Pascal Sirand-Pugnet Laure Beven Alain Charron Hélène Renaudin Aurélien Barré Philippe Avenaud Daniel Jacob Arnaud Couloux Valérie Barbe Antoine de Daruvar Alain Blanchard Cécile Bébéar 《PLoS genetics》2009,5(10)
Mycoplasma hominis is an opportunistic human mycoplasma. Two other pathogenic human species, M. genitalium and Ureaplasma parvum, reside within the same natural niche as M. hominis: the urogenital tract. These three species have overlapping, but distinct, pathogenic roles. They have minimal genomes and, thus, reduced metabolic capabilities characterized by distinct energy-generating pathways. Analysis of the M. hominis PG21 genome sequence revealed that it is the second smallest genome among self-replicating free living organisms (665,445 bp, 537 coding sequences (CDSs)). Five clusters of genes were predicted to have undergone horizontal gene transfer (HGT) between M. hominis and the phylogenetically distant U. parvum species. We reconstructed M. hominis metabolic pathways from the predicted genes, with particular emphasis on energy-generating pathways. The Embden–Meyerhoff–Parnas pathway was incomplete, with a single enzyme absent. We identified the three proteins constituting the arginine dihydrolase pathway. This pathway was found essential to promote growth in vivo. The predicted presence of dimethylarginine dimethylaminohydrolase suggested that arginine catabolism is more complex than initially described. This enzyme may have been acquired by HGT from non-mollicute bacteria. Comparison of the three minimal mollicute genomes showed that 247 CDSs were common to all three genomes, whereas 220 CDSs were specific to M. hominis, 172 CDSs were specific to M. genitalium, and 280 CDSs were specific to U. parvum. Within these species-specific genes, two major sets of genes could be identified: one including genes involved in various energy-generating pathways, depending on the energy source used (glucose, urea, or arginine) and another involved in cytadherence and virulence. Therefore, a minimal mycoplasma cell, not including cytadherence and virulence-related genes, could be envisaged containing a core genome (247 genes), plus a set of genes required for providing energy. For M. hominis, this set would include 247+9 genes, resulting in a theoretical minimal genome of 256 genes. 相似文献
190.
Churcher I Beher D Best JD Castro JL Clarke EE Gentry A Harrison T Hitzel L Kay E Kerrad S Lewis HD Morentin-Gutierrez P Mortishire-Smith R Oakley PJ Reilly M Shaw DE Shearman MS Teall MR Williams S Wrigley JD 《Bioorganic & medicinal chemistry letters》2006,16(2):280-284
The protease gamma-secretase plays a pivotal role in the synthesis of pathogenic amyloid-beta in Alzheimer's disease (AD). Here, we report a further extension to a series of cyclohexyl sulfone-based gamma-secretase inhibitors which has allowed the preparation of highly potent compounds which also demonstrate robust Abeta(40) lowering in vivo (e.g., compound 32, MED 1mg/kg p.o. in APP-YAC mice). 相似文献