The “Bear” Essentials: Actualistic Research on Ursus arctos arctos in the Spanish Pyrenees and Its Implications for Paleontology and Archaeology

Neotaphonomic studies of large carnivores are used to create models in order to explain the formation of terrestrial vertebrate fossil faunas. The research reported here adds to the growing body of knowledge on the taphonomic consequences of large carnivore behavior in temperate habitats and has important implications for paleontology and archaeology. Using photo- and videotrap data, we were able to describe the consumption of 17 ungulate carcasses by wild brown bears (Ursus arctos arctos) ranging the Spanish Pyrenees. Further, we analyzed the taphonomic impact of these feeding bouts on the bones recovered from those carcasses. The general sequence of consumption that we charted starts with separation of a carcass’s trunk; viscera are generally eaten first, followed by musculature of the humerus and femur. Long limb bones are not broken open for marrow extraction. Bears did not transport carcasses or carcass parts from points of feeding and did not disperse bones appreciably (if at all) from their anatomical positions. The general pattern of damage that resulted from bear feeding includes fracturing, peeling, crenulation, tooth pitting and scoring of axial and girdle elements and furrowing of the upper long limb bones. As predicted from observational data, the taphonomic consequences of bear feeding resemble those of other non-durophagus carnivores, such as felids, and are distinct from those of durophagus carnivores, such as hyenids. Our results have paleontological and archaeological relevance. Specifically, they may prove useful in building analogical models for interpreting the formation of fossil faunas for which bears are suspected bone accumulators and/or modifiers. More generally, our comparative statistical analyses draw precise quantitative distinctions between bone damage patterns imparted respectively by durophagus (modelled here primarily by spotted hyenas [Crocuta crocuta] and wolves [Canis lupus]) and non-durophagus (modelled here by brown bears and lions [Panthera leo]) carnivorans.     

Effects of lactose permease of Escherichia coli on the anisotropy and electrostatic surface potential of liposomes

The membrane transport protein lactose permease (LacY), a member of the Major Facilitator Superfamily (MFS) containing twelve membrane-spanning segments connected by hydrophilic loops, was reconstituted in liposomes of: (i) 1,2-dimyristoyl-sn-glycero-3-phosphocoline (DMPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) in equimolar proportions; and (ii) Escherichia coli total lipid extract. The structural order of the lipid membranes, in the presence and absence of LacY, was investigated using steady-state fluorescence anisotropy. The features of the anisotropy curves obtained with 1,6-phenyl-1,3,5-hexatriene (DPH) and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene p-toluene sulfonate (TMA-DPH) evidenced: (i) the insertion of LacY into the bilayer; and (ii) a surface effect on the membranes. The most dramatic effects were observed when LacY was reconstituted in the E. coli lipid matrix. The effect of the protein on the electrostatic surface potential of each bilayer was also examined using a fluorescent pH indicator, 4-Heptadecyl-7-hydroxycoumarin (HHC). Changes in surface potential were enhanced in the presence of the substrate (i.e. lactose) only when the lipid matrices were charged. These results suggest a role for charged phospholipids (i.e. phosphatidylethanolamine or phosphatidylglycerol) in proton transfer to the amino acids involved in substrate translocation.     

Sodium-dependent action potentials induced by brevetoxin-3 trigger both IP3 increase and intracellular Ca2+ release in rat skeletal myotubes

Brevetoxin-3 (PbTx-3), described to increase the open probability of voltage-dependent sodium channels, caused trains of action potentials and fast oscillatory changes in fluorescence intensity of fluo-3-loaded rat skeletal muscle cells in primary culture, indicating that the toxin increased intracellular Ca(2+) levels. PbTx-3 did not elicit calcium transients in dysgenic myotubes (GLT cell line), lacking the alpha1 subunit of the dihydropyridine receptor (DHPR), but after transfection of the alpha1DHPR cDNA to GLT cells, PbTx-3 induced slow calcium transients that were similar to those of normal cells. Ca(2+) signals evoked by PbTx-3 were inhibited by blocking either IP(3) receptors, with 2-aminoethoxydiphenyl borate, or phospholipase C with U73122. PbTx-3 caused a tetrodotoxin-sensitive increase in intracellular IP(3) mass levels, dependent on extra-cellular Na(+). A similar increase in IP(3) mass was induced by high K(+) depolarization but no action potential trains (nor calcium signals) were elicited by prolonged depolarization under current clamp conditions. The increase in IP(3) mass induced by either PbTx-3 or K(+) was also detected in Ca(2+)-free medium. These results establish that the effect of the toxin on both intracellular Ca(2+) and IP(3) levels occurs via a membrane potential sensor instead of directly by Na(+) flux and supports the notion of a train of action potentials being more efficient as a stimulus than sustained depolarization, suggesting that tetanus is the physiological stimulus for the IP(3)-dependent calcium signal involved in regulation of gene expression.     

Recent Dinoflagellate cyst distribution in the North Canary Basin,NW Africa

The North Canary Basin (NW Africa) falls within a major eastern boundary upwelling system. This part of the coastal upwelling system is seasonal and is characterised by the development of large filaments migrating seawards. Hence, 16 samples from this location were selected to identify an “upwelling signal” in the composition of the dinoflagellate cyst assemblages.

Samples closest to the most intense upwelling cells are dominated by L. machaerophorum and G. catenatum and Protoperidinium spp. These make up the “upwelling signal” characteristic for the system. Moreover, the “upwelling signal” can be advected offshore, with filaments that may extend as far as 300 km. Finally, the finding of cysts from G. catenatum, a toxic dinoflagellate, raises the need for a better understanding of the relationship between its presence and distribution in the region, and the coastal upwelling system.     

Nitric oxide and cell death in liver cancer cells

Nitric oxide (NO) is a lipophillic, highly diffusible, and short-lived physiological messenger which regulates a variety of physiopathological responses. NO may exert its cellular action through cGMP-dependent and cGMP-independent pathways which includes different postranslational modifications. The effect of NO in cancer depends on the activity and localization of NOS isoforms, concentration and duration of NO exposure, cellular sensitivity, and hypoxia/re-oxygenation process. NO regulates critical factors such as the hypoxia inducible factor-1 (HIF-1) and p53 generally leading to growth arrest, apoptosis or adaptation. NO sensitizes hepatoma cells to chemotherapeutic compounds probably through increased p53 and cell death receptor expressions.     

Effects of in vitro production on horse embryo morphology,cytoskeletal characteristics,and blastocyst capsule formation

Blastocyst formation rates during horse embryo in vitro production (IVP) are disappointing, and embryos that blastulate in culture fail to produce the characteristic and vital glycoprotein capsule. The aim of this study was to evaluate the impact of IVP on horse embryo development and capsule formation. IVP embryos were produced by intracytoplasmic sperm injection of in vitro matured oocytes and either culture in synthetic oviduct fluid (SOF) or temporary transfer to the oviduct of a ewe. Control embryos were flushed from the uterus of mares 6-9 days after ovulation. Embryo morphology was evaluated with light microscopy, and multiphoton scanning confocal microscopy was used to examine the distribution of microfilaments (AlexaFluor-Phalloidin stained) and the rate of apoptosis (cells with fragmented or terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling-positive nuclei). To examine the influence of culture on capsule formation, conceptuses were stained with a monoclonal antibody specific for capsular glycoproteins (OC-1). The blastocyst rate was higher for zygotes transferred to a sheep's oviduct (16%) than for those cultured in SOF (6.3%). Day 7 IVP embryos were small and compact with relatively few cells, little or no blastocoele, and an indistinct inner cell mass. IVP embryos had high percentages of apoptotic cells (10% versus 0.3% for in vivo embryos) and irregularly distributed microfilaments. Although they secreted capsular glycoproteins, the latter did not form a normal capsule but instead permeated into the zona pellucida or remained in patches on the trophectodermal surface. These results demonstrate that the initial layer of capsule is composed of OC-1-reactive glycoproteins and that embryo development ex vivo is retarded and aberrant, with capsule formation failing as a result of failed glycoprotein aggregation.     

Saccharomyces cerevisiae cells have three Omega class glutathione S-transferases acting as 1-Cys thiol transferases

The Saccharomyces cerevisiae genome encodes three proteins that display similarities with human GSTOs (Omega class glutathione S-transferases) hGSTO1-1 and hGSTO2-2. The three yeast proteins have been named Gto1, Gto2 and Gto3, and their purified recombinant forms are active as thiol transferases (glutaredoxins) against HED (beta-hydroxyethyl disulphide), as dehydroascorbate reductases and as dimethylarsinic acid reductases, while they are not active against the standard GST substrate CDNB (1-chloro-2,4-dinitrobenzene). Their glutaredoxin activity is also detectable in yeast cell extracts. The enzyme activity characteristics of the Gto proteins contrast with those of another yeast GST, Gtt1. The latter is active against CDNB and also displays glutathione peroxidase activity against organic hydroperoxides such as cumene hydroperoxide, but is not active as a thiol transferase. Analysis of point mutants derived from wild-type Gto2 indicates that, among the three cysteine residues of the molecule, only the residue at position 46 is required for the glutaredoxin activity. This indicates that the thiol transferase acts through a monothiol mechanism. Replacing the active site of the yeast monothiol glutaredoxin Grx5 with the proposed Gto2 active site containing Cys46 allows Grx5 to retain some activity against HED. Therefore the residues adjacent to the respective active cysteine residues in Gto2 and Grx5 are important determinants for the thiol transferase activity against small disulphide-containing molecules.     

Oil for Fish: An Energy Return on Investment Analysis of Selected European Union Fishing Fleets

World food production has increased substantially in the past century, thanks mostly to the increase in the use of oil as input in the production processes. This growing use of fossil fuels has negative effects, both on the environment and the production costs. Fishing is a fuel consuming food production activity, and its energy efficiency performance has worsened over time. World‐wide fisheries are also suffering from overexploitation, which contributes to the poor efficiency performance, adding more pressure and criticism on this economic activity. In this paper we analyzed the energy efficiency performance of more than 20,000 European Union (EU) fishing vessels for the period 2002–2008, using the edible energy return on investment (EROI) indicator. The vessels analyzed, grouped in 49 different fleets, represented 25% of the vessels and 33% of the landings of the EU fishing sector. These EU fishing fleets’ average EROI for 2008 was 0.11, which translates to an energy content of the fuel burned that is 9 times greater than the edible energy content of the catch. Hence, the significance of this study arises from the use of time‐series data on a relevant part of the EU fleet that showed stable or even slight improvements on the EROI over time. Moreover, results showed that the energy efficiency of the different fleets varied significantly (from 0.02 to 1.12), mainly depending on the fishing gear and the vessel length. The performance of the most efficient fleets, such as large pelagic trawlers and seiners, was comparable to many agricultural production activities. The plausible drivers behind these trends are further considered.