The role of corals on the abundance of a fish ectoparasite in the Great Barrier Reef

Coral Reefs - Gnathiid isopods, common fish ectoparasites, can affect fish physiology, behaviour and survival. Gnathiid juveniles emerge from the benthos to feed on fish blood. In the Caribbean,...     

The Crown Pearl: a draft genome assembly of the European freshwater pearl mussel Margaritifera margaritifera (Linnaeus, 1758)

Since historical times, the inherent human fascination with pearls turned the freshwater pearl mussel Margaritifera margaritifera (Linnaeus, 1758) into a highly valuable cultural and economic resource. Although pearl harvesting in M. margaritifera is nowadays residual, other human threats have aggravated the species conservation status, especially in Europe. This mussel presents a myriad of rare biological features, e.g. high longevity coupled with low senescence and Doubly Uniparental Inheritance of mitochondrial DNA, for which the underlying molecular mechanisms are poorly known. Here, the first draft genome assembly of M. margaritifera was produced using a combination of Illumina Paired-end and Mate-pair approaches. The genome assembly was 2.4 Gb long, possessing 105,185 scaffolds and a scaffold N50 length of 288,726 bp. The ab initio gene prediction allowed the identification of 35,119 protein-coding genes. This genome represents an essential resource for studying this species’ unique biological and evolutionary features and ultimately will help to develop new tools to promote its conservation.     

pH dependence of lipid peroxidation and albumin oxidative modification: possible implications to the pH paradox

The hydrogen ion concentration may have an important influence in biological free radical reactions. We studied the effect of an acidic pH on two models of free radical-mediated damage: copper-induced lipid peroxidation in plasma and copper/hydrogen peroxide-induced oxidative modification of albumin. A reduction of pH from 7·4 to 6·6 decreased diene conjugation by 32%, thiobarbituric acid-reactive substances formation by 25% and fluorescence generation by 53% in plasma exposed to cupric chloride. At pH values lower than 6·6 an even greater inhibition of lipid peroxidation in plasma was obtained. Visible fluorescence development in albumin by exposure to site-specific generation of free radicals was also increasingly reduced by decreasing pH values. From pH 7·4 to 6·6 there was a 50% fluorescence generation inhibition. The observed partial protection of lipids and proteins against oxidative damage by an acidic pH alerts to the need for rigorously controlling the pH values when assaying compounds for antioxidant properties in vitro. It may also contribute to the explanation for the protective effect of an acidic pH against anoxic cell injury and for cell death that is precipitated by a rapid return to a normal pH following reperfusion (the ‘pH paradox’).     

Detection of DNA strand breakage in a marine amphipod by agarose gel electrophoresis: exposure to X-rays and copper

This article describes the leading steps to develop an assay of DNA damage for the marine amphipod Gammarus locusta, using agarose gel electrophoresis (AGE). To test the sensitivity and feasibility of the AGE technique, X-ray assays were performed with naked DNA and with live amphipods. These positive controls demonstrated the effectiveness of the AGE technique to not only discriminate distinct levels of DNA strand breakage in a dose-dependent manner, but also to identify and quantify the type of strand breakage induced. It was also shown that it is possible to detect DNA damage using whole-body DNA extracts from amphipods. To explore the potential of this technique for use in ecotoxicological studies with amphipods, a 96-h waterborne-copper toxicity test was performed. Copper-induced DNA strand breakage was first observed after 24 h of exposure, and was recorded again at 96 h, at a copper concentration of 20 μg l -1 . The absence of strand breakage after 48 h of exposure is discussed in the light of the underlying mechanisms of copper toxicity and DNA repair. These studies demonstrated the feasibility of including DNA damage as a biomarker in ecotoxicological studies with amphipods. Information gained from the use of this biomarker would help with the interpretation of chronic toxicity tests and would contribute to our understanding of the impact of genotoxic insult in marine invertebrates, particularly crustaceans.     

Effects of surrounding landscape on parasitism of alfalfa aphids in an IPM crop system in northern Catalonia

The parasitism (Hymenoptera, Braconidae, Aphidiinae) of alfalfa aphids (Hemiptera, Aphididae) was determined during three crop growing seasons. The highest rates of parasitism of Acyrthosiphon pisum Harris and of Therioaphis trifolii Monell occurred during the first-second and the fourth alfalfa intercuts, respectively. The landscape surrounding the fields affected only parasitism rates of A. pisum. During the second intercut the forest area had a negative influence on parasitism rates, whereas the bordering surfaces of alfalfa and winter cereals had a positive influence. Positive correlations were found between the rates of parasitism of A. pisum and the rate of aphid population increase in the first intercut. By contrast, negative correlations were found in the second intercut, when the aphid population peaked, suggesting that parasitoids contribute to the regulation of the aphid. This study stresses that regulation of alfalfa aphids cannot be explained solely on the basis of one functional group of natural enemies.     

High and Distinct Range-Edge Genetic Diversity despite Local Bottlenecks

The genetic consequences of living on the edge of distributional ranges have been the subject of a largely unresolved debate. Populations occurring along persistent low latitude ranges (rear-edge) are expected to retain high and unique genetic diversity. In contrast, currently less favourable environmental conditions limiting population size at such range-edges may have caused genetic erosion that prevails over past historical effects, with potential consequences on reducing future adaptive capacity. The present study provides an empirical test of whether population declines towards a peripheral range might be reflected on decreasing diversity and increasing population isolation and differentiation. We compare population genetic differentiation and diversity with trends in abundance along a latitudinal gradient towards the peripheral distribution range of Saccorhiza polyschides , a large brown seaweed that is the main structural species of kelp forests in SW Europe. Signatures of recent bottleneck events were also evaluated to determine whether the recently recorded distributional shifts had a negative influence on effective population size. Our findings show decreasing population density and increasing spatial fragmentation and local extinctions towards the southern edge. Genetic data revealed two well supported groups with a central contact zone. As predicted, higher differentiation and signs of bottlenecks were found at the southern edge region. However, a decrease in genetic diversity associated with this pattern was not verified. Surprisingly, genetic diversity increased towards the edge despite bottlenecks and much lower densities, suggesting that extinctions and recolonizations have not strongly reduced diversity or that diversity might have been even higher there in the past, a process of shifting genetic baselines.     

RKIP Inhibition in Cervical Cancer Is Associated with Higher Tumor Aggressive Behavior and Resistance to Cisplatin Therapy

Cervical cancer is one of the most common cancers in women worldwide, being high-risk group the HPV infected, the leading etiological factor. The raf kinase inhibitory protein (RKIP) has been associated with tumor progression and metastasis in several human neoplasms, however its role on cervical cancer is unclear. In the present study, 259 uterine cervix tissues, including cervicitis, cervical intraepithelial lesions and carcinomas, were analyzed for RKIP expression by immunohistochemistry. We found that RKIP expression was significantly decreased during malignant progression, being highly expressed in non-neoplastic tissues (54% of the samples; 73/135), and expressed at low levels in the cervix invasive carcinomas (∼15% (19/124). Following in vitro downregulation of RKIP, we observed a viability and proliferative advantage of RKIP-inhibited cells over time, which was associated with an altered cell cycle distribution and higher colony number in a colony formation assay. An in vitro wound healing assay showed that RKIP abrogation is associated with increased migratory capability. RKIP downregulation was also associated with an increased vascularization of the tumors in vivo using a CAM assay. Furthermore, RKIP inhibition induced cervical cancer cells apoptotic resistance to cisplatin treatment. In conclusion, we described that RKIP protein is significantly depleted during the malignant progression of cervical tumors. Despite the lack of association with patient clinical outcome, we demonstrate, in vitro and in vivo, that loss of RKIP expression can be one of the factors that are behind the aggressiveness, malignant progression and chemotherapy resistance of cervical cancer.     

Industrial Scale Isolation,Structural and Spectroscopic Characterization of Epiisopiloturine from Pilocarpus microphyllus Stapf Leaves: A Promising Alkaloid against Schistosomiasis

This paper presents an industrial scale process for extraction, purification, and isolation of epiisopiloturine (EPI) (2(3H)-Furanone,dihydro-3-(hydroxyphenylmethyl)-4-[(1-methyl-1H-imidazol-4-yl)methyl]-, [3S-[3a(R*),4b]]), which is an alkaloid from jaborandi leaves (Pilocarpus microphyllus Stapf). Additionally for the first time a set of structural and spectroscopic techniques were used to characterize this alkaloid. EPI has shown schistomicidal activity against adults and young forms, as well as the reduction of the egg laying adult worms and low toxicity to mammalian cells (in vitro). At first, the extraction of EPI was done with toluene and methylene chloride to obtain a solution that was alkalinized with ammonium carbonate. The remaining solution was treated in sequence by acidification, filtration and alkalinization. These industrial procedures are necessary in order to remove impurities and subsequent application of the high performance liquid chromatography (HPLC). The HPLC was employed also to remove other alkaloids, to obtain EPI purity higher than 98%. The viability of the method was confirmed through HPLC and electrospray mass spectrometry, that yielded a pseudo molecular ion of m/z equal to 287.1 Da. EPI structure was characterized by single crystal X-ray diffraction (XRD), ¹H and ¹³C nuclear magnetic resonance (NMR) in deuterated methanol/chloroform solution, vibrational spectroscopy and mass coupled thermal analyses. EPI molecule presents a parallel alignment of the benzene and the methyl imidazol ring separated by an interplanar spacing of 3.758 Å indicating a π-π bond interaction. The imidazole alkaloid melts at 225°C and decomposes above 230°C under air. EPI structure was used in theoretical Density Functional Theory calculations, considering the single crystal XRD data in order to simulate the NMR, infrared and Raman spectra of the molecule, and performs the signals attribution.