Dental microwear textural analyses to track feeding ecology of reindeer: a comparison of two contrasting populations in Norway

Using dental microwear textural analysis, we aim to explore variations in feeding habits within and between wild reindeer populations (Rangifer tarandus) in Norway. Specimens from the two wild reindeer areas of Knutshø and Hardangervidda were hunted between late August and the end of September 2014, and found to share very similar topological and ecological characteristics (continental alpine tundra). Despite the homogenisation of plant resources at the end of the snow-free period, dental microwear textural analysis on cheek teeth indicates differences in feeding behaviors between the two populations, in that reindeer from Knutshø might display a more “grazing” signal than the ones from Hardangervidda. Such differences in dental microwear textures reflect the differences in feeding habits that could be linked with differences in population density of reindeer. The Knutshø reindeer density is lower than at Hardangervidda, where primary food resources like grasses, sedges, and lichens are less abundant. Analyses also show the differences in gender for the population of Knutshø, but more studies are necessary for the clearest interpretation of data. Our results emphasize the need to explore local variations at a monthly time frame in order to better assess the versatility of dental microwear textures before applying this kind of analysis to either extant or extinct multi-population scales.     

Characterization of Multiple-Substrate Utilization by Anthracene-Degrading Mycobacterium frederiksbergense LB501T

Stable carbon isotope analysis of biomass and analyses of phospholipid fatty acids (PLFA), glycolipid fatty acids (GLFA), and mycolic acids were used to characterize mixed-substrate utilization by Mycobacterium frederiksbergense LB501T under various substrate regimens. The distinct ¹³C contents of anthracene and glucose as representatives of typical hydrophobic pollutants and naturally occurring organic compounds, respectively, were monitored during formation into biomass and used to quantify the relative contributions of the two carbon sources to biomass formation. Moreover, the influence of mixed-substrate utilization on PLFA, GLFA, and mycolic acid profiles and cell surface hydrophobicity was investigated. Results revealed that M. frederiksbergense LB501T degrades anthracene and forms biomass from it even in the presence of more readily available dissolved glucose. The relative ratios of straight-chain saturated PLFA to the corresponding unsaturated PLFA and the total fraction of saturated cyclopropyl-branched PLFA of M. frederiksbergense LB501T depended on the carbon source and the various rates of addition of mixed substrates, whereas no such trend was observed with GLFA. Higher proportions of anthracene in the carbon source mixture led to higher cell surface hydrophobicities and more-hydrophobic mycolic acids, which in turn appeared to be valuable indicators for substrate utilization by M. frederiksbergense LB501T. The capability of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria to utilize readily available substrates besides the poorly available PAHs favors the buildup of PAH-degrading biomass. Feeding of supplementary carbon substrates may therefore promote bioremediation, provided that it sustains the pollutant-degrading population rather than other members of the microbial community.     

Quantitative analysis of human cerebrospinal fluid proteins using a combination of cysteine tagging and amine-reactive isobaric labeling

Highly complex and dynamic protein mixtures are hardly comprehensively resolved by direct shotgun proteomic analysis. As many proteins of biological interest are of low abundance, numerous analytical methodologies have been developed to reduce sample complexity and go deeper into proteomes. The present work describes an analytical strategy to perform cysteinyl-peptide subset enrichment and relative quantification through successive cysteine and amine-isobaric tagging. A cysteine-reactive covalent capture tag (C3T) allowed derivatization of cysteines and specific isolation on a covalent capture (CC) resin. The 6-plex amine-reactive tandem mass tags (TMT) served for relative quantification of the targeted peptides. The strategy was first evaluated on a model protein mixture with increasing concentrations to assess the specificity of the enrichment and the quantitative performances of the workflow. It was then applied to human cerebrospinal fluid (CSF) from post-mortem and ante-mortem samples. These studies confirmed the specificity of the C3T and the CC technique to cysteine-containing peptides. The model protein mixture analysis showed high precision and accuracy of the quantification with coefficients of variation and mean absolute errors of less than 10% on average. The CSF experiments demonstrated the potential of the strategy to study complex biological samples and identify differential brain-related proteins. In addition, the quantification data were highly correlated with a classical TMT experiment (i.e., without C3T cysteine-tagging and enrichment steps). Altogether, these results legitimate the use of this quantitative C3T strategy to enrich and relatively quantify cysteine-containing peptides in complex mixtures.     

Stability of pollination services decreases with isolation from natural areas despite honey bee visits

Sustainable agricultural landscapes by definition provide high magnitude and stability of ecosystem services, biodiversity and crop productivity. However, few studies have considered landscape effects on the stability of ecosystem services. We tested whether isolation from florally diverse natural and semi-natural areas reduces the spatial and temporal stability of flower-visitor richness and pollination services in crop fields. We synthesised data from 29 studies with contrasting biomes, crop species and pollinator communities. Stability of flower-visitor richness, visitation rate (all insects except honey bees) and fruit set all decreased with distance from natural areas. At 1 km from adjacent natural areas, spatial stability decreased by 25, 16 and 9% for richness, visitation and fruit set, respectively, while temporal stability decreased by 39% for richness and 13% for visitation. Mean richness, visitation and fruit set also decreased with isolation, by 34, 27 and 16% at 1 km respectively. In contrast, honey bee visitation did not change with isolation and represented > 25% of crop visits in 21 studies. Therefore, wild pollinators are relevant for crop productivity and stability even when honey bees are abundant. Policies to preserve and restore natural areas in agricultural landscapes should enhance levels and reliability of pollination services.     

Correlation between the expression of the histone H4 mRNA variant H4-v.1 and the levels of histone H4-(86-100) and H4-(89-102) (OGP) in various rat tissues and alveolar macrophages

We studied the expression of the osteogenic and antinociceptive C-terminal histone H4-related peptide fragments, H4-(89-102) (OGP) and H4-(86-100), respectively, within various rat tissues and isolated alveolar macrophages (AM) by radioimmunoassay (RIA). OGP was located mainly within the bone marrow, spleen, thymus, and lungs whereas H4-(86-100) was more concentrated within the bone marrow, lymph nodes, spinal cord, pituitaries and thymus. The expression pattern of the two peptides showed similarities with the tissue expression pattern of the histone H4 mRNA variant H4-v.1. In rat AM, OGP and H4-(86-100) levels were significantly stimulated (2.6- and 1.9-fold, respectively) by LPS (1 microg/ml), along with H4-v.1 mRNA (4.1-fold), but not whole histone H4 (1.1-fold) nor total histone H4 mRNA (1.1-fold). The results suggest that H4-v.1 mRNA may play a role in the synthesis of the naturally occurring peptides H4-(86-100) and OGP via the alternative translation product H4-(84-102), but not whole histone H4.     

2-Phenyl-beta-lapachone can affect mitochondrial function by redox cycling mediated oxidation

2-Phenyl-beta-lapachone (3,4-dihydro-2-methyl-2-phenyl-2H-naphtho[1,2b]pyran-5,6-dione) (2PBL) is a o-naphthoquinone synthesized as a possible antitumoral agent. The addition of micromolar concentrations of 2PBL to rat liver mitochondria (in the presence of malate-glutamate or succinate, as respiratory substrates): (1) stimulated O(2) consumption in state 4 and inhibited O(2) consumption in state 3, thus decreasing respiratory control index (RCI); and (2) collapsed the mitochondrial membrane potential. The addition of 2PBL to rat liver submitochondrial particles: (1) stimulated NADH oxidation in the presence of rotenone, antimycin, myxothiazol or cyanide; (2) stimulated (.-)O(2)(-) production in the presence of NADH and antimycin; and (3) led to 2PBL semiquinone radical production. Control studies carried out with two p-naphthoquinones, menadione and atovaquone, did not produced equivalent effects. These findings support the hypothesis that 2PBL, undergoes redox cycling and affects mitochondrial function. The 2PBL effect is complex, involving inhibition of electron transfer, uncoupling of oxidative phosphorylation, collapse of mitochondrial membrane potential and (.-)O(2)(-) production by redox cycling. The mitochondrion could be a target organelle for 2PBL cytotoxicity.     

The North Sea: source or sink for nitrogen and phosphorus to the Atlantic Ocean?

Annual nitrogen and phosphorus budgets for the whole North Sea taking into account the most recent data available were established. The area considered has a total surface of approximately 700,000km² and corresponds to the definition by OSPARCOM (Oslo and Paris Commission) with the exclusion of the Skagerrak and Kattegat areas. Input and output fluxes were determined at the marine, atmospheric, sediment and continental boundaries, and riverine inputs based on river flows and nutrient concentrations at the river–estuary interface were corrected for possible estuarine retention. The results showed that the North Sea is an extremely complex system subjected to large inter-annual variability of marine water circulation and freshwater land run-off. Consequently, resulting total N (TN) and P (TP) fluxes are extremely variable from 1 year to another and this has an important influence on the budget of these elements. Total inputs to the North Sea are 8870±4860kTNyear^–1 and 494±279kTPyear^–1. Denitrification is responsible for the loss of 23±7% of the TN inputs while sediment burial is responsible for the retention of only of 2±2% of the TP input. For TN, due to the large variability on marine and estuarine fluxes, and to the uncertainty related to the denitrification rate, it was concluded that the North Sea could either be a source (1930kTNyear^–1) or a sink (1700kTNyear^–1) for the waters of the North Atlantic Ocean. For TP it was concluded that the North Sea is mostly a source (–4 to 52kTPyear^–1) for the waters of the North Atlantic Ocean.     

Design, synthesis, and biological evaluation of folic acid targeted tetraphenylporphyrin as novel photosensitizers for selective photodynamic therapy

Photodynamic therapy (PDT) is a cancer treatment involving systemic administration of a tumor-localizing photosensitizer; this, when activated by the appropriate light wavelength, interacts with molecular oxygen to form a toxic, short-lived species known as singlet oxygen, which is thought to mediate cellular death. Targeted PDT offers the opportunity of enhancing photodynamic efficiency by directly targeting diseased cells and tissues. Two new conjugates of three components, folic acid/hexane-1,6-diamine/4-carboxyphenylporphyrine 1 and folic acid/2,2'-(ethylenedioxy)-bis-ethylamine/4-carboxyphenylporphyrine 2 were synthesized. The conjugates were characterized by 1H NMR, MALDI, UV-visible spectroscopy, and fluorescence quantum yield. The targeted delivery of these photoactive compounds to KB nasopharyngeal cell line, which is one of the numerous tumor cell types that overexpress folate receptors was studied. It was found that after 24 h incubation, conjugates 1 and 2 cellular uptake was on average 7-fold higher than tetraphenylporphyrin (TPP) used as reference and that 1 and 2 cellular uptake kinetics increased steadily over the 24 h period, suggesting an active transport via receptor-mediated endocytosis. In corresponding results, conjugates 1 and 2 accumulation displayed a reduction of 70% in the presence of a competitive concentration of folic acid. Survival measurements demonstrated that KB cells were significantly more sensitive to conjugated porphyrins-mediated PDT. Under the same experimental conditions and the same photosensitizer concentration, TPP displayed no photocytotoxicity while conjugates 1 and 2 showed photodynamic activity with light dose values yielding 50% growth inhibition of 22.6 and 6.7 J/cm2, respectively.     

Stable isotope measurements confirm consumption of submerged macrophytes by macroinvertebrate and fish taxa

Many macrophyte species in lowland streams exhibit signs of grazing and herbivore damage, even though herbivory by aquatic macroinvertebrates and fish is generally considered to be of little importance. In this study, we collected evidence for the hypothesis that herbivory on macrophytes by macroinvertebrates and fish is more widespread than assumed. We measured the dual stable isotope signatures (δ¹³C and δ¹⁵N) of organic matter, epiphyton, submerged macrophytes, macroinvertebrates and fish in a Belgian lowland stream. There was a clear distinction in isotopic signatures of the different basal resources, allowing the use of the SIAR mixing model. These calculations revealed the consumption of macrophyte tissue not only by the phytophagous larvae of Nymphula nitidulata Hufnagel (Lepidoptera: Crambidae), but also by Baetidae nymphs (Ephemeroptera), Orthocladiinae larvae (Diptera: Chironomidae), the crayfish Orconectus limosus Rafinesque (Decapoda: Cambaridae) and the fish Gobio gobio L. (Cypriniformes: Cyprinidae) which are classified as feeding on other resources. Although the potential share of macrophyte biomass in the diet of macroinvertebrates and fish was demonstrated to be up to 49%, this amount is only a small percentage of the total standing macrophyte biomass in a lowland stream. However, the impact of this herbivory may still be substantial because consumption may comprise a significant fraction of the daily primary production. Additionally, small-scale herbivory may still have a negative impact on macrophyte growth and survival, for example through consumption of apical meristems and the increased susceptibility to diseases and toxins if the macrophyte’s epidermis is damaged.