48 research outputs found
Frequency of sublethal injury in a deepwater ophiuroid, Ophiacantha bidentata, an important component of western Atlantic Lophelia reef communities
The occurrence and relative abundance of tissue (arm) regeneration in the ophiuroid, Ophiacantha bidentata (Retzius), was examined in individuals collected primarily among colonies of the deep-water coral Lophelia pertusa off the southeastern United States. Seven deep-water coral sites (384–756 m), located between Cape Lookout, NC, and Cape Canaveral, FL, were sampled in June 2004 using a manned submersible. The presence of regenerative tissue was evaluated by visual inspection of each individual ophiuroid, and the proportion of regenerating arms per individual was examined relative to size of individual, geographic location, and depth of collection. Ophiacantha bidentata, the dominant brittle star collected, commonly displayed signs of sublethal injury with over 60% of individuals displaying some evidence of regeneration. These levels of regeneration rival those reported for shallow-water ophiuroids. Larger individuals (\u3e6.5 mm disc size) had a higher incidence of regeneration than smaller individuals. Size of individual and percent of regeneration were negatively correlated with depth. Although O. bidentata was significantly less abundant in southern versus northern sites, ophiuroid abundance did not appear to be influenced by amount or density of coral substratum. Presence of dense aggregations of O. bidentata indicates that they are an important component of the invertebrate assemblage associated with deep-water coral habitat especially in the northern part of the study area. Assuming that observed frequencies of injury and subsequent regeneration represent predation events then dense ophiuroid aggregations in deepwater coral habitats represent an important renewable trophic resource within these communities
Structure-function-dynamics relationships in the peculiar Planktothrix PCC7805 OCP1: impact of his-tagging and carotenoid type
The orange carotenoid protein (OCP) is a photoactive protein involved in cyanobacterial photoprotection. Here, we report on the functional, spectral and structural characteristics of the peculiar Planktothrix PCC7805 OCP (Plankto-OCP). We show that this OCP variant is characterized by higher photoactivation and recovery rates, and a stronger energy-quenching activity, compared to other OCPs studied thus far. We characterize the effect of the functionalizing carotenoid and of his-tagging on these reactions, and the time scales on which these modifications affect photoactivation. The presence of a His-tag at the C-terminus has a large influence on photoactivation, thermal recovery and PBS-fluorescence quenching, and likewise for the nature of the carotenoid that additionally affects the yield and characteristics of excited states and the ns-s dynamics of photoactivated OCP. By solving the structures of Plankto-OCP in the ECN- and CAN-functionalized states, each in two closely-related crystal forms, we further unveil the molecular breathing motions that animate Plankto-OCP at the monomer and dimer levels. We finally discuss the structural changes that could explain the peculiar properties of Plankto-OCP. - Complete functional characterization of Synechocystis and Planktothrix OCPs - Hitherto unknown structures of ECN- and CAN-functionalized Planktothrix OC
Caribbean Spiny Lobster Fishery Is Underpinned by Trophic Subsidies from Chemosynthetic Primary Production
Data files are deposited with Figshare and are available at: https://dx.doi.org/10.6084/ m9.figshare.4225334
Morphology of the megalopa of the mud crab, Rhithropanopeus harrisii (Gould, 1841) (Decapoda, Brachyura, Panopeidae), identified by DNA barcode.
The morphology of the megalopa stage of the
panopeid Rhithropanopeus harrisii is redescribed and
illustrated in detail from plankton specimens identified by
DNA barcode (16S mtDNA) as previous descriptions do
not meet the current standard of brachyuran larval
description. Several morphological characters vary widely
from those of other panopeid species which could cast
some doubt on the species’ placement in the same family.
Besides, some anomalous megalopae of R. harrisii were
found among specimens reared at the laboratory from
zoeae collected in the plankton. These anomalous morphological
features are discussed in terms of problems
associated with laboratory rearing conditions
Mithracinae (Decapoda: Brachyura) from the Brazilian coast: review of the geographical distribution and comments on the biogeography of the group
Dynamique de l'eau dans une chĂŞnaie (Quercus petraea (Matt.) Liebl.) en forĂŞt de Fontainebleau
International audienc
Variation of stomatal resistance with leaf age in Quercus petraea: effect on the soil-water balance of an oak forest
International audienc
Variation of stomatal resistance with leaf age in Quercus petraea: effect on the soil-water balance of an oak forest
Site management and productivity in tropical plantations : impact on soils and options for management over successive rotations : atelier
L’intérêt de l’utilisation
Le micropsychromètre de Dixon-Tyree jusqu’alors essentiellement utilisé en conditions contrôlées en est encore au stade expérimental sur des peuplements ligneux in situ. Il a été ici utilisé pour la mesure du potentiel hydrique du xylème du tronc et des racines avec une chambre à pression pour la mesure du potentiel foliaire, dans le but de mesurer et comparer les potentiels hydriques des feuilles, du tronc et des racines d’individus d’hévéas dans une plantation en Côte d’Ivoire (mai et septembre 2004). Les mesures de potentiel hydrique du xylème avec le micropsychromètre de Dixon-Tyree ont été jugées fiables, à condition de respecter des contraintes techniques. Ce travail débouche sur un éventuel recalage des mesures et sur une redéfinition du potentiel de base. Les mesures par micropsychromètre, comparées à celles obtenues par chambre à pression ont l’avantage de ne pas être destructives si le capteur est bien installé. Ce dernier peut être laissé sur le tronc deux à trois semaines, sans intervention. Les valeurs issues des premières journées de mesure sont parfois erronées en raison d’un manque d’équilibrage et il est préférable d’attendre le lendemain pour commencer les séries de mesures