Browsing by Issue Date, starting with "2011-05"
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- Proliferative and mineralogenic effects of insulin, IGF-1, and vanadate in fish osteoblast-like cellsPublication . Tiago, Daniel; Cancela, Leonor; Laizé, VincentFish have recently been recognized as a suitable model and a promising alternative to mammalian systems to study skeletogenesis. In this regard, several fish bone-derived cell lines have been developed and are being used to investigate mechanisms associated with insulin-like action of vanadium on extracellular matrix (ECM) mineralization. Although proliferative and mineralogenic effects of vanadate, insulin-like growth factor 1 (IGF-1), and insulin have recently been evaluated in a fish prechondrocyte cell line, no data are available in fish bone-forming cells, the osteoblasts. Using fish preosteoblast cells, we showed that IGF-1, but not insulin or vanadate, stimulated cell proliferation through the mitogen-activated protein kinase (MAPK) pathway, while both IGF-1 and vanadate inhibited cell differentiation/ECM mineralization through the same mechanism. Our data also indicated that the phosphatidyl inositol-3 kinase (PI-3K) pathway stimulates differentiation/ECM mineralization in osteoblasts and could represent a way to balance MAPK pathway action. The comparison of these new data obtained in fish with those available in mammals clearly evidenced a conservation of regulatory mechanisms among vertebrate bone-derived systems, although different players are involved.
- Phylogeography of the Atlanto-Mediterranean sea cucumber Holothuria (Holothuria) mammata: the combined effects of historical processes and current oceanographical patternPublication . Borrero-Perez, G. H.; Gonzalez-Wanguemert, Mercedes; Marcos, C.; Perez-Ruzafa, A.We assessed the genetic structure of populations of the widely distributed sea cucumber Holothuria (Holothuria) mammata Grube, 1840, and investigated the effects of marine barriers to gene flow and historical processes. Several potential genetic breaks were considered, which would separate the Atlantic and Mediterranean basins, the isolated Macaronesian Islands from the other locations analysed, and the Western Mediterranean and Aegean Sea (Eastern Mediterranean). We analysed mitochondrial 16S and COI gene sequences from 177 individuals from four Atlantic locations and four Mediterranean locations. Haplotype diversity was high (H = 0.9307 for 16S and 0.9203 for COI), and the haplotypes were closely related (p = 0.0058 for 16S and 0.0071 for COI). The lowest genetic diversities were found in the Aegean Sea population. Our results showed that the COI gene was more variable and more useful for the detection of population structure than the 16S gene. The distribution of mtDNA haplotypes, the pairwise FST values and the results of exact tests and AMOVA revealed: (i) a significant genetic break between the population in the Aegean Sea and those in the other locations, as supported by both mitochondrial genes, and (ii) weak differentiation of the Canary and Azores Islands from the other populations; however, the populations from the Macaronesian Islands, Algarve and West Mediterranean could be considered to be a panmictic metapopulation. Isolation by distance was not identified in H. (H.) mammata. Historical events behind the observed findings, together with the current oceanographic patterns, were proposed and discussed as the main factors that determine the population structure and genetic signature of H. (H.) mammata
- Weighted Hardy and potential operators in the generalized Morrey spacesPublication . Persson, Lars-Erik; Samko, NatashaWe study the weighted p -> q-boundedness of the multi-dimensional Hardy type operators in the generalized Morrey spaces L-p.phi(R-n, w) defined by an almost increasing function phi(r) and radial type weight w(vertical bar x vertical bar). We obtain sufficient conditions, in terms of some integral inequalities imposed on phi and w, for such a p -> q-boundedness. In some cases the obtained conditions are also necessary. These results are applied to derive a similar weighted p -> q-boundedness of the Riesz potential operator. (c) 2010 Elsevier Inc. All rights reserved.
- Left-right asymmetry in the level of active Nodal protein produced in the node is translated into left-right asymmetry in the lateral plate of mouse embryosPublication . Kawasumi, Aiko; Nakamura, Tetsuya; Iwai, Naomi; Yashiro, Kenta; Saijoh, Yukio; Belo, Jose Antonio; Shiratori, Hidetaka; Hamada, HiroshiLeft-right (L-R) asymmetry in the mouse embryo is generated in the node and is dependent on cilia-driven fluid flow, but how the initial asymmetry is transmitted from the node to the lateral plate has remained unknown. We have now identified a transcriptional enhancer (ANE) in the human LEFTY1 gene that exhibits marked L>R asymmetric activity in perinodal cells of the mouse embryo. Dissection of ANE revealed that it is activated in the perinodal cells on the left side by Nodal signaling, suggesting that Nodal activity in the node is asymmetric at a time when Nodal expression is symmetric. Phosphorylated Smad2/3 (pSmad2) indeed manifested an L-R asymmetric distribution at the node, being detected in perinodal cells preferentially on the left side. This asymmetry in pSmad2 distribution was found to be generated not by unidirectional transport of Nodal but rather as a result of LR distribution of active Nodal in the node is translated into the asymmetry in LPM. (C) 2011 Elsevier Inc. All rights reserved.
- Novel polymorphisms in plasmodium falciparum ABC transporter genes are associated with major ACT antimalarial drug resistancePublication . Veiga, Maria Isabel; Pousão-Ferreira, Pedro; Jornhagen, Louise; Malmberg, Maja; Kone, Aminatou; Schmidt, Berit Aydin; Petzold, Max; Bjorkman, Anders; Nosten, Francois; Gil, José PedroChemotherapy is a critical component of malaria control. However, the most deadly malaria pathogen, Plasmodium falciparum, has repeatedly mounted resistance against a series of antimalarial drugs used in the last decades. Southeast Asia is an epicenter of emerging antimalarial drug resistance, including recent resistance to the artemisinins, the core component of all recommended antimalarial combination therapies. Alterations in the parasitic membrane proteins Pgh-1, PfCRT and PfMRP1 are believed to be major contributors to resistance through decreasing intracellular drug accumulation. The pfcrt, pfmdr1 and pfmrp1 genes were sequenced from a set of P. falciparum field isolates from the Thai-Myanmar border. In vitro drug susceptibility to artemisinin, dihydroartemisinin, mefloquine and lumefantrine were assessed. Positive correlations were seen between the in vitro susceptibility responses to artemisinin and dihydroartemisinin and the responses to the arylamino-alcohol quinolines lumefantrine and mefloquine. The previously unstudied pfmdr1 F1226Y and pfmrp1 F1390I SNPs were associated significantly with artemisinin, mefloquine and lumefantrine in vitro susceptibility. A variation in pfmdr1 gene copy number was also associated with parasite drug susceptibility of artemisinin, mefloquine and lumefantrine. Our work unveils new candidate markers of P. falciparum multidrug resistance in vitro, while contributing to the understanding of subjacent genetic complexity, essential for future evidence-based drug policy decisions.
- The effect of stress on egg quality in farmed Atlantic Cod (Gadus morhua L.)Publication . Natário, Silvestre Ramos; Canario, Adelino V. M.The Atlantic cod (Gadus morhua), is a prestigious species of fish that belongs to the Gadidae family, and is considered a promising species for future aquaculture in the northern hemisphere. Cod production has grown exponentially since the beginning of the millennium. The but development of cod farming has been hampered by bottlenecks in the production such as deformities, diseases as francisellosis, slow growth and early maturation, and in addition relatively low market prices compared to present production costs. Farming of cod relies on a stable supply of high quality eggs. Egg quality and production is dependent not only upon the female condition and hence broodstock diet, but can be negatively affected by stress. In addition, farmed females often fail to release their eggs, become eggbound and die. The project “Why do Atlantic cod females become eggbound? Studies on possible causes and mechanisms” (Research Council of Norway, grant no 190187/E40) investigates the physiological events during normal and abnormal (eggbound) spawning, with the aim to determine factors that may cause the problems. Two factors that may affect these are investigated in this project; The first is dietary lipid content as this correlates to gonadosomatic index (GSI, gonad weight as % of total weight). The fecundity of farmed cod is about 50% higher than wild cod, and one could suspect that abnormally large gonads would increase the problems with eggbound females. The second variable is stress, either directly due to distorted spawning behaviour or indirectly through the eicosanoid cascade. Eggs of poor quality can have a negative impact on production resulting in slow growth, high mortality rate and deformities. In this master it has been focused on the egg production from farmed cod fed either a high (20%) or a low (13%) fat diet, and either physically stressed or not. The stress treatment, imposed randomly once a week, consisted of reducing the water level to a height of 15 cm from the bottom, and for 1 minute the fish were chased with a landing’s nets. The low-stress treatment was nothing more than keeping fish in tanks. The amount of eggs spawned in the tanks was measured through the spawning season and used to calculate fecundity, and egg quality assessed by egg diameter, fertilization, deformities, and hatching rate. The dietary treatment affected final weight; cod fed the low fat diet, had a lower final weight after spawning compared with fish that were fed a high fat diet. The fecundity, expressed as total production of eggs spawned, was affected by diet. The fishes that were fed with the low fat diet had a lower fecundity than the fish fed with a high fat diet. The duration of the spawning season as like the fecundity was also influenced by the stress; the cod in the high stress treatment prolonged their spawning period compared to the low stress group. Egg diameter decreased during the spawning season in all treatments, The fertilisation rate was directly influenced by the type of treatment during the spawning season, but no significant differences were found when assessed 1 or 2 days after stress. Hatching rate was different between diets, but when combined with stress, only fish fed the low fat diet exhibited different rates of hatching. Finally, the rate of deformities did not differ between treatments. In a general assessment, good egg quality is obtained by finding a balance between diet and type of management. Furthermore, fish fed with high fat levels appear more tolerant to stressful activities. Consequently, egg quality, has to be defined by a combination of several parameters. It is also important not to set aside the inclusion of new parameters that may be decisive in order to minimize misclassification.
- Transcriptome sequencing and microarray development for the Manila clam, Ruditapes philippinarum: genomic tools for environmental monitoringPublication . Milan, Massimo; Coppe, Alessandro; Reinhardt, Richard; Cancela, Leonor; Leite, Ricardo; Saavedra, Carlos; Ciofi, Claudio; Chelazzi, Guido; Patarnello, T.; Bortoluzzi, Stefania; Bargelloni, LucaAbstract Background The Manila clam, Ruditapes philippinarum, is one of the major aquaculture species in the world and a potential sentinel organism for monitoring the status of marine ecosystems. However, genomic resources for R. philippinarum are still extremely limited. Global analysis of gene expression profiles is increasingly used to evaluate the biological effects of various environmental stressors on aquatic animals under either artificial conditions or in the wild. Here, we report on the development of a transcriptomic platform for global gene expression profiling in the Manila clam. Results A normalized cDNA library representing a mixture of adult tissues was sequenced using a ultra high-throughput sequencing technology (Roche 454). A database consisting of 32,606 unique transcripts was constructed, 9,747 (30%) of which could be annotated by similarity. An oligo-DNA microarray platform was designed and applied to profile gene expression of digestive gland and gills. Functional annotation of differentially expressed genes between different tissues was performed by enrichment analysis. Expression of Natural Antisense Transcripts (NAT) analysis was also performed and bi-directional transcription appears a common phenomenon in the R. philippinarum transcriptome. A preliminary study on clam samples collected in a highly polluted area of the Venice Lagoon demonstrated the applicability of genomic tools to environmental monitoring. Conclusions The transcriptomic platform developed for the Manila clam confirmed the high level of reproducibility of current microarray technology. Next-generation sequencing provided a good representation of the clam transcriptome. Despite the known limitations in transcript annotation and sequence coverage for non model species, sufficient information was obtained to identify a large set of genes potentially involved in cellular response to environmental stress.