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- Development and application of a SCAR marker to monitor and quantify populations of the postharvest biocontrol agent Pantoea agglomerans CPA-2Publication . Nunes, Carla; Bajji, Mohammed; Stepien, Valerie; Manso, Teresa; Torres, Rosario; Usall, Josep; Jijakli, M. HaissamPantoea agglomerans CPA-2 is an effective biocontrol agent of postharvest diseases of citrus and pome fruit. A monitoring technique was developed for its identification and to quantify its populations. The methodology used consisted of (i) searching for a semi-selective medium, (ii) identification of molecular markers and (iii) monitoring population dynamics in a commercial trial. As a semi-selective medium, Malonate Broth Agar supplemented with tetracycline hydroxychloricle and incubation at high temperature (max. of 40 degrees C) facilitated the selective recovery of P agglomerans CPA-2 colonies. The RAPD technique was applied to a collection of 13 strains of P. agglomerans, including CPA-2. Among the 12 primers tested, OPL-11 amplified a fragment (about 720 bp) specific to strain CPA-2. On the basis of this fragment, two SCAR markers were amplified using a primer pair derived from OPL-11 elongation. A first SCAR marker of 720 bp was specifically amplified for the strain CPA-2 and a second one of 270bp was obtained for all P. agglomerans strains tested, including CPA-2. Commercial trials demonstrated a significant reduction of decay with the treatment of formulated cells of R agglomerans CPA-2. Population dynamics of CPA-2 in commercial trials were determined on fruit surfaces and in the environment using both the classical plating technique and PCR with SCAR primers. In general, no significant differences were observed between results obtained from the two methods. On fruit surfaces, 1 day after CPA-2 applied its population by classical methods was 4.37 x 10(6) cfu wound(-1) and at the end of the experiment the population increased to 5.8 x 10(5) cfu wound(-1). The percentages of colonies identified as P agglomerans CPA-2 at these sampling times using SCAR primers were 90 and 95%, respectively. Population dynamics in the environment to evaluate the environmental fate of R agglomerans CPA-2 showed that it has a limited persistence and limited capacity for dispersion. (c) 2007 Published by Elsevier B.V.
- Comparative study of shell shape and muscle scar pigmentation in the closely related cupped oysters Crassostrea angulata, C-gigas and their reciprocal hybridsPublication . Batista, Frederico M.; Ben-Hamadou, Radhouan; Vera G Fonseca; Taris, Nicolas; Ruano, Francisco; Reis-Henriques, Maria A.; Boudry, PierreThe taxonomic status of the cupped oysters Crassostrea angulata and C. gigas has received considerable attention in the last decades. Based on larval shell morphology, experimental hybridization, allozymes and nuclear DNA studies several authors have considered these two taxa as being synonymous. However, mitochondrial data showed clear genetic differences between the two taxa. In addition, microsatellite- based studies and cytogenetic studies have also provided evidence that supports their differentiation. Considerable differences have also been observed at the phenotypic level in terms of growth rate and ecophysiological parameters. In the present study, C. angulata from Sado estuary ( Portugal) and C. gigas from Seudre estuary ( France) were collected and factorial crosses were performed. Juveniles of the different progenies were reared in Ria Formosa ( Portugal) under common conditions to determine if they exhibited differences in shell shape and in pigmentation of the adductor muscle scar. Significant morphometric differences between C. angulata and C. gigas progenies were indicated by univariate and multivariate analyses. Univariate analysis of size- adjusted shell measurements revealed significant differences between the two taxa for shell depth, muscle scar height, and length of ligamental area. Both reciprocal hybrids showed intermediate morphometric characters between parental lines. In addition, significant differences were also observed between C. angulata and C. gigas progenies in terms of pigmentation of adductor muscle scar. C. angulata and both reciprocal hybrid progenies showed highly pigmented adductor muscle scars whereas in C. gigas progeny the pigmentation was lighter. The differences in shell shape and muscle scar pigmentation observed in the present study support the distinction of the two taxa.
- Cripto-independent Nodal signaling promotes positioning of the A-P axis in the early mouse embryoPublication . Liguori, Giovanna; Borges, Ana; D'Andrea, Daniela; Liguoro, Annamaria; Gonçalves Dias da Silva, Lisa; Salizueiro, Ana Marisa; Persico, M. Graziella; Belo, José A.During early mouse development, the TGF beta-related protein Nodal specifies the organizing centers that control the formation of the anterior-posterior (A-P) axis. EGF-CFC proteins are important components of the Nodal signaling pathway, most likely by acting as Nodal coreceptors. However, the extent to which Nodal activity depends on EGF-CFC proteins is still debated. Cripto is the earliest EGF-CFC gene expressed during mouse embryogenesis and is involved in both A-P axis orientation and mesoderm formation. To investigate the relation between Cripto and Nodal in the early mouse embryo, we removed the Nodal antagonist Cerberus 1 (Cer1) and simultaneously Cripto, by generating Cer1;Cripto double mouse mutants. We observed that two thirds of the Cer1,Cripto double mutants are rescued in processes that are severely compromised in Cripto(-/-) embryos, namely A-P axis orientation, anterior mesendoderm and posterior neuroectoderin formation. The observed rescue is strongly reduced in Cer1;Cripto;Nodal triple mutants, suggesting that Nodal can signal extensively in the absence of Cripto, if Cer1 is also inhibited. This signaling activity drives A-P axis positioning. Our results provide evidence for the existence. of Cripto-independent signaling mechanisms, by which Nodal controls axis specification in the early mouse embryo. (C) 2007 Elsevier Inc. All rights reserved.
- Ichthyofauna assemblages from two unexplored Atlantic seamounts: Northwest Bank and João Valente Bank (Cape Verde archipelago)Publication . Monteiro, Pedro; Ribeiro, Daniel; Silva, José A.; Bispo, João; Gonçalves, J. M. S.Underwater censuses by divers were used to study the fish assemblages from two unexplored Atlantic seamounts in the Cape Verde archipelago. Fifty three species of 27 families were recorded: 27 in Northwest Bank and 46 in João Valente Bank. Northwest Bank had dense schools, while João Valente Bank had higher species richness and smaller schools. Both seamounts were dominated mainly by coastal species directly depending on seabed habitat (Demersal or benthopelagic). Of the 53 fish species recorded, 22.6% were of continental African origin, while 9.4% and 5.7% were endemic of the Cape Verde Islands and of the Macaronesia province, respectively. Most species (64.2%) had a very wide biogeographic distribution: cosmopolitan (22.6%), amphi-Atlantic (28.3%) and Atlantic-Mediterranean (13.2%). Northwest Bank and João Valente Bank may have a permanent fish community supported by various oceanographic-topographic interactions. João Valente Bank seems more diverse, which is probably associated with algae cover and with a larger area providing additional suitable and more varied habitats. The geographic proximity to the coast and the presence of oceanic and/or oceanodromous species suggests that the upper part of these seamounts may act both as attraction points and as “stepping-stones” for the dispersal of coastal species.
- Estudos sedimentares em dois estuários da costa oeste algarvia: relação cor-ferroPublication . Veiga-Pires, C.; Mariano, J.; Moura, Delminda; Castro, N.; Rogalski, M.; Boski, T.Os sedimentos estuarinos constituem valiosos registos das condições climáticas e ambientais regionais.