Distribution and Ecophysiology of Calanoid Copepods in Relation to the Oxygen Minimum Zone in the Eastern Tropical Atlantic

Oxygen minimum zones (OMZs) affect distribution patterns, community structure and metabolic processes of marine organisms. Due to the prominent role of zooplankton, especially copepods, in the marine carbon cycle and the predicted intensification and expansion of OMZs, it is essential to understand the effects of hypoxia on zooplankton distribution and ecophysiology. For this study, calanoid copepods were sampled from different depths (0–1800 m) at eight stations in the eastern tropical Atlantic (3°47′N to 18°S) during three expeditions in 2010 and 2011. Their horizontal and vertical distribution was determined and related to the extent and intensity of the OMZ, which increased from north to south with minimum O₂ concentrations (12.7 µmol kg⁻¹) in the southern Angola Gyre. Calanoid copepod abundance was highest in the northeastern Angola Basin and decreased towards equatorial regions as well as with increasing depth. Maximum copepod biodiversity was observed in the deep waters of the central Angola Basin. Respiration rates and enzyme activities were measured to reveal species-specific physiological adaptations. Enzyme activities of the electron transport system (ETS) and lactate dehydrogenase (LDH) served as proxies for aerobic and anaerobic metabolic activity, respectively. Mass-specific respiration rates and ETS activities decreased with depth of occurrence, consistent with vertical changes in copepod body mass and ambient temperature. Copepods of the families Eucalanidae and Metridinidae dominated within the OMZ. Several of these species showed adaptive characteristics such as lower metabolic rates, additional anaerobic activity and diel vertical migration that enable them to successfully inhabit hypoxic zones.     

The DNA translocase RAD5A acts independently of the other main DNA repair pathways,and requires both its ATPase and RING domain for activity in Arabidopsis thaliana

Multiple pathways exist to repair DNA damage induced by methylating and crosslinking agents in Arabidopsis thaliana. The SWI2/SNF2 translocase RAD5A, the functional homolog of budding yeast Rad5 that is required for the error‐free branch of post‐replicative repair, plays a surprisingly prominent role in the repair of both kinds of lesions in Arabidopsis. Here we show that both the ATPase domain and the ubiquitination function of the RING domain of the Arabidopsis protein are essential for the cellular response to different forms of DNA damage. To define the exact role of RAD5A within the complex network of DNA repair pathways, we crossed the rad5a mutant line with mutants of different known repair factors of Arabidopsis. We had previously shown that RAD5A acts independently of two main pathways of replication‐associated DNA repair defined by the helicase RECQ4A and the endonuclease MUS81. The enhanced sensitivity of all double mutants tested in this study indicates that the repair of damaged DNA by RAD5A also occurs independently of nucleotide excision repair (AtRAD1), single‐strand break repair (AtPARP1), as well as microhomology‐mediated double‐strand break repair (AtTEB). Moreover, RAD5A can partially complement for a deficient AtATM‐mediated DNA damage response in plants, as the double mutant shows phenotypic growth defects.     

Oxidative stress and lipid mediators induced in alveolar macrophages by ultrafine particles

In ambient aerosols, ultrafine particles (UFP) and their agglomerates are considered to be major factors contributing to adverse health effects. Reactivity of agglomerated UFP of elemental carbon (EC), Printex 90, Printex G, and diesel exhaust particles (DEP) was evaluated by the capacity of particles to oxidize methionine in a cell-free in vitro system for determination of their innate oxidative potential and by alveolar macrophages (AMs) to determine production of arachidonic acid (AA), including formation of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), reactive oxygen species (ROS), and oxidative stress marker 8-isoprostane. EC exhibiting high oxidative potential induced generation of AA, PGE2, LTB4, and 8-isoprostane in canine and human AMs. Printex 90, Printex G, and DEP, showing low oxidative capacity, still induced formation of AA and PGE2, but not that of LTB4 or 8-isoprostane. Aging of EC lowered oxidative potential while still inducing production of AA and PGE2 but not that of LTB4 and 8-isoprostane. Cellular ROS production was stimulated by all particles independent of oxidative potential. Particle-induced formation of AA metabolites and ROS was dependent on mitogen-activated protein kinase kinase 1 activation of cytosolic phospholipase A2 (cPLA2) as shown by inhibitor studies. In conclusion, cPLA2, PGE2, and ROS formation was activated by all particle types, whereas LTB4 production and 8-isoprostane were strongly dependent on particles' oxidative potential. Physical and chemical parameters of particle surface correlated with oxidative potential and stimulation of AM PGE2 and 8-isoprostane production.     

Interaction of hypohalous acids and heme peroxidases with unsaturated phosphatidylcholines

The formation of chlorohydrins, bromohydrins, and iodohydrins from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) by the myeloperoxidase-hydrogen peroxide-halide system was evaluated by means of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry. This approach allows to detect different kinds of the halogenation reaction even in one mass spectrum. Using a mixture of Cl-, Br-, I-, and SCN- at physiological concentrations, a bromination of POPC dominates by the MPO-hydrogen peroxide-halide system. Hypothiocyanite does apparently not react with the double bond of POPC, but increasing amounts of SCN- cause a decrease of the bromohydrin peaks. An interconversion between different hypohalous acids produced by the myeloperoxidase-hydrogen peroxide-halide system determines the pattern of halogenohydrins in POPC. Especially, hypochlorous acid is able to oxidise Br- to hypobromous acid.     

Regulation of Harvest-induced Senescence in Broccoli (Brassica oleracea var. italica) by Cytokinin, Ethylene, and Sucrose

Broccoli (Brassica oleracea var. italica) deteriorates rapidly following harvest. The two plant hormones ethylene and cytokinin are known to act antagonistically on harvest-induced senescence in broccoli: ethylene by accelerating the process, and cytokinin by delaying it. To determine the level at which these hormones influenced senescence, we isolated and monitored the expression of genes normally associated with senescence in broccoli florets treated with exogenous 6-benzyl aminopurine (6-BAP), 1-aminocyclopropane-1-carboxylic acid (ACC), a combination of 6-BAP and ACC, and sucrose, in the five days following harvest. Exogenous 6-BAP caused both a reduction (BoACO) and an increase (BoACS) in ethylene biosynthetic gene expression. The expression of genes used as senescence markers, BoCP5 and BoMT1, was reduced, whereas BoCAB1 levels were maintained after harvest in response to exogenous 6-BAP. In addition, the expression of genes encoding sucrose transporters (BoSUC1 and BoSUC2) and carbohydrate metabolizing enzymes (BoINV1 and BoHK1) was also reduced upon 6-BAP feeding. Interestingly, the addition of ACC prevented the 6-BAP-induced increase in expression of BoACS, but 6-BAP negated the ACC-induced increase in expression of BoACO. The culmination of these results indicates a significant role for cytokinin in the delay of senescence. The implication that cytokinin regulates postharvest senescence in broccoli by inhibiting ethylene perception and/or biosynthesis, thus regulating carbohydrate transport and metabolism, as well as senescence-associated gene expression, is discussed and a model presented.     

PhyloChip hybridization uncovered an enormous bacterial diversity in the rhizosphere of different potato cultivars: many common and few cultivar-dependent taxa

The phylogenetic composition of bacterial communities in the rhizosphere of three potato cultivars grown at two distant field sites was analysed. Ribosomal gene fragments amplified from total community DNA were hybridized to PhyloChips. A total of 2432 operational taxonomic units (OTUs) were detected by the PhyloChips, of which 65% were found in the rhizosphere of all cultivars at both field sites. From all detected OTUs, 9% revealed a cultivar-dependent abundance at the one or the other field site and 4% at both sites. Differential abundance on the three cultivars was mainly observed for OTUs belonging to the Pseudomonadales, Actinomycetales and Enterobacteriales. More than 40% of OTUs belonging to Bradyrhizobiales, Sphingomonadales, Burkholderiales, Rhodocyclales, Xanthomonadales and Actinomycetales differed significantly in their abundance between the sites. A sequence analysis of six 16S rRNA gene clone libraries corresponded well with the taxonomic community structure evidenced by the PhyloChip hybridization. Most ribotypes matched OTUs detected by the PhyloChip. Those OTUs that responded to the potato cultivar at both field sites might be of interest in view of cultivar-specific effects on bacterial biocontrol strains and pathogens.     

Confirmation of right whales near a nineteenth-century whaling ground east of southern Greenland

North Atlantic right whales (Eubalaena glacialis) were found in an important nineteenth century whaling area east of southern Greenland, from which they were once thought to have been extirpated. In 2007-2008, a 1-year passive acoustic survey was conducted at five sites in and near the 'Cape Farewell Ground', the former whaling ground. Over 2000 right whale calls were recorded at these sites, primarily during July-November. Most calls were northwest of the historic ground, suggesting a broader range in this region than previously known. Geographical and temporal separation of calls confirms use of this area by multiple animals.     

mRNA expression of genes involved in fatty acid utilization in skeletal muscle and white adipose tissues of sows during lactation

Rodents are able to lower fatty acid utilization in liver and muscle during lactation in order to spare fatty acids for the production of milk triacylglycerols, an effect which is mediated by a down-regulation of peroxisome proliferator-activated receptor α (PPARα). The present study was performed to investigate whether similar fatty acid sparing effects are developing in lactating sows. We considered PPARα and its target genes involved in fatty acid utilization in biopsy samples from muscle and adipose tissue of lactating compared to non-lactating sows. In muscle, PPARα target genes involved in fatty acid utilization were up-regulated during lactation indicating that the fatty acid utilization in muscle was increased. Activation of PPARα was probably due to increased concentrations of non-esterified fatty acids in plasma observed in the lactating sows. In contrast to muscle, PPARα and its target genes involved in β-oxidation in white adipose tissue were down-regulated in early lactation. Overall, the present study shows that sows, unlike rats, are not able to reduce the fatty acid utilization in muscle in order to spare fatty acids for milk production. However, fatty acid oxidation in adipose tissue is lowered during early lactation, an effect that might be helpful to conserve fatty acids released from adipose tissue for the delivery into other tissues, including mammary gland, via the blood.     

Heterogeneity in ess transcriptional organization and variable contribution of the Ess/Type VII protein secretion system to virulence across closely related Staphylocccus aureus strains

The Type VII protein secretion system, found in Gram‐positive bacteria, secretes small proteins, containing a conserved W‐x‐G amino acid sequence motif, to the growth medium. Staphylococcus aureus has a conserved Type VII secretion system, termed Ess, which is dispensable for laboratory growth but required for virulence. In this study we show that there are unexpected differences in the organization of the ess gene cluster between closely related strains of S. aureus. We further show that in laboratory growth medium different strains of S. aureus secrete the EsxA and EsxC substrate proteins at different growth points, and that the Ess system in strain Newman is inactive under these conditions. Systematic deletion analysis in S. aureus RN6390 is consistent with the EsaA, EsaB, EssA, EssB, EssC and EsxA proteins comprising core components of the secretion machinery in this strain. Finally we demonstrate that the Ess secretion machinery of two S. aureus strains, RN6390 and COL, is important for nasal colonization and virulence in the murine lung pneumonia model. Surprisingly, however, the secretion system plays no role in the virulence of strain SA113 under the same conditions.     

MR Angiography Follow-Up 10 Years after Cryptogenic Nonperimesencephalic Subarachnoid Hemorrhage

ObjectivesLong-term magnetic resonance angiography (MRA) follow-up studies regarding cryptogenic nonperimesencephalic subarachnoid hemorrhage (nSAH) are scarce. This single-centre study identified all patients with angiographically verified cryptogenic nSAH from 1998 to 2007: The two main objectives were to prospectively assess the incidence of de novo aneurysm with 3.0-MRI years after cryptogenic nSAH in patients without evidence for further hemorrhage, and retrospectively assess patient demographics and outcome.MethodsFrom prospectively maintained report databases all patients with angiographically verified cryptogenic nSAH were identified. 21 of 29 patients received high-resolution 3T-MRI including time-of-flight and contrast-enhanced angiography, 10.2 ± 2.8 years after cryptogenic nSAH. MRA follow-up imaging was compared with initial digital subtraction angiography (DSA) and CT/MRA. Post-hemorrhage images were related to current MRI with reference to persistent lesions resulting from delayed cerebral ischemia (DCI) and post-hemorrhagic siderosis. Patient-based objectives were retrospectively abstracted from clinical databases.Results29 patients were identified with cryptogenic nSAH, 17 (59%) were male. Mean age at time of hemorrhage was 52.9 ± 14.4 years (range 4 – 74 years). 21 persons were available for long-term follow-up. In these, there were 213.5 person years of MRI-follow-up. No de novo aneurysm was detected. Mean modified Rankin Scale (mRS) during discharge was 1.28. Post-hemorrhage radiographic vasospasm was found in three patients (10.3%); DCI-related lesions occurred in one patient (3.4%). Five patients (17.2%) needed temporary external ventricular drainage; long-term CSF shunt dependency was necessary only in one patient (3.4%). Initial DSA retrospectively showed a 2 x 2 mm aneurysm of the right distal ICA in one patient, which remained stable. Post-hemorrhage siderosis was detected 8.1 years after the initial bleeding in one patient (4.8%).ConclusionPatients with cryptogenic nSAH have favourable outcomes and do not exhibit higher risks for de novo aneurysms. Therefore the need for long-term follow up after cryptogenic nSAH is questionable.