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81.
Adelle Roux Helet Lambrechts Rouvay Roodt-Wilding 《Invertebrate reproduction & development.》2014,58(1):42-48
In this study, effective gamete concentrations, egg viability, and fertilization volumes were evaluated for Haliotis midae (L.). Sperm concentrations between 5?×?103 and 5?×?104?mL?1 (p?>?0.05) consistently resulted in high hatch-out rates (96?±?1%). At concentrations higher than 5?×?105?mL?1, hatch-out rates decreased to 69?±?7% (p?0.05). Egg concentrations between 10 and 125?eggs?mL?1 resulted in high fertilization rates, with 50?eggs?mL?1 being the ideal concentration for fertilization in H. midae. Egg viability was consistently high up to 100?min post-spawning, with a decrease in hatch-out success, when eggs were fertilized 120?min post-spawning. Fertilization volumes did not affect successful hatch-out. The results from this study can be implemented by South African abalone farms to increase hatch-out rates and subsequent culture. It can also be used as basis for the development of fertilization protocols in other marine invertebrate species. 相似文献
82.
Adèle Mennerat Pascal Mirleau Jacques Blondel Philippe Perret Marcel M. Lambrechts Philipp Heeb 《Oecologia》2009,161(4):849-855
Several bird species add fresh fragments of plants which are rich in volatile secondary compounds to their nests. It has been
suggested, although never tested, that birds use fresh plants to limit the growth of nest microorganisms. On Corsica, blue
tits (Cyanistes caeruleus) incorporate fresh fragments of aromatic plants into their nests. These plants do not reduce infestation by nest ectoparasites,
but have been shown to improve growth and condition of chicks at fledging. To understand the mechanisms underlying such benefits,
we experimentally tested the effects of these plants on the bacteria living on blue tits. Aromatic plants significantly affected
the structure of bacterial communities, in particular reducing bacterial richness on nestlings. In addition, in this population
where there is a strong association between bacterial density and infestation by blood-sucking Protocalliphora blow fly larvae, these plants reduced bacterial density on the most infested chicks. Aromatic plants had no significant effect
on the bacteria living on adult blue tits. This study provides the first evidence that fresh plants brought to the nests by
adult birds limit bacterial richness and density on their chicks. 相似文献
83.
84.
Lauren B. Carrington M. Veronica Armijos Louis Lambrechts Thomas W. Scott 《PLoS neglected tropical diseases》2013,7(4)
Background
Environmental factors such as temperature can alter mosquito vector competence for arboviruses. Results from recent studies indicate that daily fluctuations around an intermediate mean temperature (26°C) reduce vector competence of Aedes aeygpti for dengue viruses (DENV). Theoretical predictions suggest that the mean temperature in combination with the magnitude of the diurnal temperature range (DTR) mediate the direction of these effects.Methodology/Principal Findings
We tested the effect of temperature fluctuations on Ae. aegypti vector competence for DENV serotype-1 at high and low mean temperatures, and confirmed this theoretical prediction. A small DTR had no effect on vector competence around a high (30°C) mean, but a large DTR at low temperature (20°C) increased the proportion of infected mosquitoes with a disseminated infection by 60% at 21 and 28 days post-exposure compared to a constant 20°C. This effect resulted from a marked shortening of DENV extrinsic incubation period (EIP) in its mosquito vector; i.e., a decrease from 29.6 to 18.9 days under the fluctuating vs. constant temperature treatment.Conclusions
Our results indicate that Ae. aegypti exposed to large fluctuations at low temperatures have a significantly shorter virus EIP than under constant temperature conditions at the same mean, leading to a considerably greater potential for DENV transmission. These results emphasize the value of accounting for daily temperature variation in an effort to more accurately understand and predict the risk of mosquito-borne pathogen transmission, provide a mechanism for sustained DENV transmission in endemic areas during cooler times of the year, and indicate that DENV transmission could be more efficient in temperate regions than previously anticipated. 相似文献85.
Reina JA de Kinderen Danielle AJE Lambrechts Debby Postulart Alfons GH Kessels Jos GM Hendriksen Albert P Aldenkamp Marian HJM Majoie 《BMC neurology》2011,11(1):10
Background
Epilepsy is a neurological disorder, characterized by recurrent unprovoked seizures which have a high impact on the individual as well as on society as a whole. In addition to the economic burden, epilepsy imposes a substantial burden on the patients and their surroundings. Patients with uncontrolled epilepsy depend heavily on informal care and on health care professionals. About 30% of patients suffer from drug-resistant epilepsy. The ketogenic diet can be a treatment of last resort, especially for children. The beneficial effect of the ketogenic diet has been proven, but information is lacking about its cost-effectiveness. In the current study we will evaluate the (cost-) effectiveness of the ketogenic diet in children and adolescents with intractable epilepsy. 相似文献86.
Gonzalez G DaFonseca S Errazuriz E Coric P Souquet F Turcaud S Boulanger P Bouaziz S Hong SS 《PloS one》2011,6(11):e27234
The HIV-1 auxiliary protein Vpr and Vpr-fusion proteins can be copackaged with Gag precursor (Pr55Gag) into virions or membrane-enveloped virus-like particles (VLP). Taking advantage of this property, we developed a simple and sensitive method to evaluate potential inhibitors of HIV-1 assembly in a living cell system. Two proteins were coexpressed in recombinant baculovirus-infected Sf9 cells, Pr55Gag, which formed the VLP backbone, and luciferase fused to the N-terminus of Vpr (LucVpr). VLP-encapsidated LucVpr retained the enzymatic activity of free luciferase. The levels of luciferase activity present in the pelletable fraction recovered from the culture medium correlated with the amounts of extracellular VLP released by Sf9 cells assayed by conventional immunological methods. Our luciferase-based assay was then applied to the characterization of betulinic acid (BA) derivatives that differed from the leader compound PA-457 (or DSB) by their substituant on carbon-28. The beta-alanine-conjugated and lysine-conjugated DSB could not be evaluated for their antiviral potentials due to their high cytotoxicity, whereas two other compounds with a lesser cytotoxicity, glycine-conjugated and ε-NH-Boc-lysine-conjugated DSB, exerted a dose-dependent negative effect on VLP assembly and budding. A fifth compound with a low cytotoxicity, EP-39 (ethylene diamine-conjugated DSB), showed a novel type of antiviral effect. EP-39 provoked an aberrant assembly of VLP, resulting in nonenveloped, morula-like particles of 100-nm in diameter. Each morula was composed of nanoparticle subunits of 20-nm in diameter, which possibly mimicked transient intermediates of the HIV-1 Gag assembly process. Chemical cross-linking in situ suggested that EP-39 favored the formation or/and persistence of Pr55Gag trimers over other oligomeric species. EP-39 showed a novel type of negative effect on HIV-1 assembly, targeting the Pr55Gag oligomerisation. The biological effect of EP-39 underlined the critical role of the nature of the side chain at position 28 of BA derivatives in their anti-HIV-1 activity. 相似文献
87.
QJ Voorham B Carvalho AJ Spiertz B Claes S Mongera NC van Grieken H Grabsch M Kliment B Rembacken MA van de Wiel P Quirke CJ Mulder D Lambrechts M van Engeland GA Meijer 《PloS one》2012,7(7):e41963
Background
Flat adenomas are a subgroup of colorectal adenomas that have been associated with a distinct biology and a more aggressive clinical behavior compared to their polypoid counterparts. In the present study, we aimed to compare the mutation spectrum of 14 cancer genes, between these two phenotypes.Methods
A consecutive series of 106 flat and 93 polypoid adenomas was analyzed retrospectively for frequently occurring mutations in “hot spot” regions of KRAS, BRAF, PIK3CA and NRAS, as well as selected mutations in CTNNB1 (β-catenin), EGFR, FBXW7 (CDC4), PTEN, STK11, MAP2K4, SMAD4, PIK3R1 and PDGFRA using a high-throughput genotyping technique. Additionally, APC was analyzed using direct sequencing.Results
APC mutations were more frequent in polypoid adenomas compared to flat adenomas (48.5% versus 30.3%, respectively, p = 0.02). Mutations in KRAS, BRAF, NRAS, FBXW7 and CTNNB1 showed similar frequencies in both phenotypes. Between the different subtypes of flat adenomas (0-IIa, LST-F and LST-G) no differences were observed for any of the investigated genes.Conclusion
The lower APC mutation rate in flat adenomas compared to polypoid adenomas suggests that disruption of the Wnt-pathway may occur via different mechanisms in these two phenotypes. Furthermore, in contrast to previous observations our results in this large well-defined sample set indicate that there is no significant association between the different morphological phenotypes and mutations in key genes of the RAS-RAF-MAPK pathway. 相似文献88.
J P Verbelen D Lambrechts D Stickens W Tao 《The International journal of developmental biology》1992,36(1):67-72
Cells regenerated from freshly isolated leaf mesophyll protoplasts can be induced to develop along very different pathways. Depending on the hormone content and the mechanical characteristics of the environment, cells choose between division and expansion. In the former case they form microcolonies of isodiametric cells, while in the latter they exhibit a typical tubular growth or increase their volume considerably by bulging and budding. A culture method was developed which allows a careful control of the experimental environment and non-destructive high resolution monitoring of development of individual cells. 相似文献
89.
The effect of nest ectoparasites on parental provisioning in a north-African population of the Blue Tit Parus caeruleus 总被引:1,自引:1,他引:0
Zihad Bouslama Marcel M. Lambrechts Nadia Ziane Rédha Djenidi & Yassine Chabi 《Ibis》2002,144(2):E73-E78
Bird nests are often heavily infested with several haematophagous ectoparasite species that drain energy and other essential resources needed for the development of the rapidly growing chicks. The nutritional requirements of altricial chicks can only be satisfied by the parents frequently bringing prey to the nest. In a 3-year study, we tested experimentally whether a parasite-induced change in the nutritional budgets of the chicks in an Algerian population of the Blue Tit, could be compensated by a response in parental food provisioning behaviour. We found that nestling body mass and size did not differ between heat-treated 'parasite-free' nests and heavily infested control nests. However, after controlling for potential confounding variables (laydate, clutch size, chick age, year), we found that broods of heavily infested control nests were more frequently visited and fed than broods that received antiparasite treatment. The results are discussed in the framework of theory related to behavioural responses of hosts to parasites. 相似文献
90.
Climate change and coral reef connectivity 总被引:3,自引:3,他引:0
P. L. Munday J. M. Leis J. M. Lough C. B. Paris M. J. Kingsford M. L. Berumen J. Lambrechts 《Coral reefs (Online)》2009,28(2):379-395
This review assesses and predicts the impacts that rapid climate change will have on population connectivity in coral reef
ecosystems, using fishes as a model group. Increased ocean temperatures are expected to accelerate larval development, potentially
leading to reduced pelagic durations and earlier reef-seeking behaviour. Depending on the spatial arrangement of reefs, the
expectation would be a reduction in dispersal distances and the spatial scale of connectivity. Small increase in temperature
might enhance the number of larvae surviving the pelagic phase, but larger increases are likely to reduce reproductive output
and increase larval mortality. Changes to ocean currents could alter the dynamics of larval supply and changes to planktonic
productivity could affect how many larvae survive the pelagic stage and their condition at settlement; however, these patterns
are likely to vary greatly from place-to-place and projections of how oceanographic features will change in the future lack
sufficient certainty and resolution to make robust predictions. Connectivity could also be compromised by the increased fragmentation
of reef habitat due to the effects of coral bleaching and ocean acidification. Changes to the spatial and temporal scales
of connectivity have implications for the management of coral reef ecosystems, especially the design and placement of marine-protected
areas. The size and spacing of protected areas may need to be strategically adjusted if reserve networks are to retain their
efficacy in the future. 相似文献