Six new species and some nomenclatural changes in neotropical Lycopodiaceae

Palhinhaea divaricata B. Øllg., Palhinhaea lugubris B. Øllg., Palhinhaea pseudocurvata B. Øllg., Palhinhaea reflexifolia B. Øllg., Phlegmariurus ciliatospiculatus B. Øllg. and Phlegmariurus luteynii B. Øllg. are described as new to science. Diphasium lawessonianum (B. Øllg.) B. Øllg. is a new combination, based on Lycopodium lawessonianum B. Øllg. Three subfamilies of the Lycopodiaceae: Huperzioideae, Lycopodielloideae and Lycopodioideae, first used by Wagner and Beitel (1992), are validated.     

HIV-1 p6 — a structured to flexible multifunctional membrane-interacting protein

The human immunodeficiency virus type 1 (HIV-1) p6 protein has recently been recognized as a docking site for several cellular and viral binding partners and is important for the formation of infectious viruses. Most of its known functions are suggested to occur under hydrophobic conditions near the cytoplasmic membrane, where the protein is presumed to exist in its most structured state. Although p6 is involved in manifold specific interactions, the protein has previously been considered to possess a random structure in aqueous solution. We show that p6 exhibits a defined structure with N- and C-terminal helical domains, connected by a flexible hinge region in 100 mM dodecylphosphocholine micelle solution at pH 7 devoid of any organic co-solvents, indicating that this is a genuine limiting structural feature of the molecule in a hydrophobic environment. Furthermore, we show that p6 directly interacts with a cytoplasmic model membrane through both N-terminal and C-terminal regions by use of surface plasmon resonance (SPR) spectroscopy. Phosphorylation of Ser-40 located in the center of the C-terminal α-helix does not alter the secondary structure of the protein but amplifies the interaction with membranes significantly, indicating that p6 binds to the polar head groups at the surface of the cytoplasmic membrane. The increased hydrophobic membrane interaction of p6^23-52 S40F correlated with the observed increased amount of the polyprotein Gag in the RIPA insoluble fraction when Ser40 of p6 was mutated with Phe indicating that p6 modulates the membrane interactions of HIV-1 Gag.     

Temporal variation in density dependent body growth of a large herbivore

Temporal variation both due to density dependent and density independent processes affect performance and vital rates in large herbivores. Annual fluctuations in climate affect foraging conditions and thus body growth of large herbivores during the short growing season in alpine habitats. Also, high animal densities on summer ranges may increase competition for food and reduce body mass gain. Yet, little is known about interactive effects of density and climate on alpine summer ranges, and the time scales these processes operate on. In this fully replicated landscape‐scale experiment, we kept domestic sheep at high and low densities over nine grazing seasons in an alpine habitat, and tested the relative role of density and annual variation for lamb body mass gain during summer and whether effects of density and annual variation interacted. We found that lambs at high density gained less mass over the summer season than lambs at low density. At short time scales the density effect interacted with annual fluctuations in body growth. We documented a long‐term temporal trend in body mass, consistent with the hypothesis that grazing effects affect habitat differentially at high and low density over years. At high density lamb autumn body mass declined during the first three grazing seasons and then stabilized, whereas body mass slightly increased over years at low density. This long‐term trend suggests accumulative density dependent effects from a biomass or quality reduction, and hence delayed food competition at high density and possibly facilitation at low density. Our experiment provides new insight into how density dependent effects on performance of a large herbivore depend on temporal scale of observation.     

Impact of individual mutations on increased fitness in adaptively evolved strains of Escherichia coli

We measured the relative fitness among a set of experimentally evolved Escherichia coli strains differing by a small number of adaptive mutations by directly measuring allelic frequencies in head-to-head competitions using a mass spectrometry-based method. We compared the relative effects of mutations to the same or similar genes acquired in multiple strains when expressed in allele replacement strains. We found that the strongest determinant of fitness among the evolved strains was the impact of beneficial mutations to the RNA polymerase beta and beta' subunit genes. We also identified several examples of epistatic interactions between rpoB/C and glpK mutations and identified two other mutations that are beneficial only in the presence of previously acquired mutations but that have little or no adaptive benefit to the wild-type strain. Allele frequency estimation is shown to be a highly sensitive method for measuring selection rates during competitions between strains differing by as little as a single-nucleotide polymorphism and may be of great use for investigating epistatic interactions.     

Biodegradation of amine waste generated from post-combustion CO2 capture in a moving bed biofilm treatment system

Nitrogen and organic matter removal from reclaimer waste of a monoethanolamine (MEA) based CO₂-capture plant was demonstrated in a pre-denitrification biofilm system. The reclaimer waste was generated from a 30 % (w/w) MEA solvent used for capturing CO₂ from flue gas from a coal-fired power plant. MEA, N-(2-hydroxylethyl)glycine (HEGly) and 2-hydroxyethylformamide (HEF) were the major contaminants treated. Hydrolysis of MEA to ammonia and further oxidation of organic intermediates readily occurred in the pre-denitrification system with a hydraulic retention time of 7 h. The biofilm system achieved 98 ± 1 % removal of MEA and 72 ± 16 % removal of total nitrogen. This is the first demonstration of efficient biodegradation of real amine waste from a post-combustion CO₂ capture facility by pre-denitrification without external electron donor.     

The development of ammonoid septa: An epithelial invagination process controlled by morphogens?

Suture lines are important in ammonoid taxonomy. Their complex morphologies, caused by iterated invaginations of the posterior body wall, can be explained using a mechano‐chemical model inspired by modem developmental models for epithelial folding in kidneys, lungs, teeth, mammary glands and other organs. A morphogen, organized to form a regular spacing pattern by reaction‐diffusion dynamics or similar processes, induces changes in cell shape and/or rate of proliferation, causing invagination and the formation of lobes. Interactions between mechanical and chemical effects, combined with expanding size due to overall growth, produce a “fractal”; pattern of smaller (secondary) invaginations superimposed on larger (primary) ones. The pattern of increasing sutural complexity that is observed in ammonoid evolution may be a simple heterochronic effect, that allowed iterated invagination to be extended to higher and higher levels of folding. In contrast with some earlier theories, the present model is based on the view that the development of ammonoid septa must have been under relatively strict genetic control.     

Stress-Induced Reversion to Virulence of Infectious Pancreatic Necrosis Virus in Na?ve Fry of Atlantic Salmon (Salmo salar L.)

We have studied stress-induced reversion to virulence of infectious pancreatic necrosis virus (IPNV) in persistently infected Atlantic salmon (Salmo salar L.) fry. Naïve fry were persistently infected with a virulent strain (T₂₁₇A₂₂₁ of major structural virus protein 2, VP2) or a low virulent (T₂₁₇T₂₂₁) variant of IPNV. The fry were infected prior to immunocompetence as documented by lack of recombination activating gene-1, T-cell receptor and B-cell receptor mRNA expression at time of challenge. The fish were followed over 6 months and monitored monthly for presence of virus and viral genome mutations. No mutation was identified in the TA or TT group over the 6 months period post infection. Six months post infection TA and TT infected groups were subject to daily stress for 7 days and then sampled weekly for an additional period of 28 days post stress. Stress-responses were documented by down-regulation of mRNA expression of IFN-α1 and concomitant increase of replication levels of T₂₁₇T₂₂₁ infected fish at day 1 post stress. By 28 days post stress a T221A reversion was found in 3 of 6 fish in the T₂₁₇T₂₂₁ infected group. Sequencing of reverted isolates showed single nucleotide peaks on chromatograms for residue 221 for all three isolates and no mix of TA and TT strains. Replication fitness of reverted (TA) and non-reverted (TT) variants was studied in vitro under an antiviral state induced by recombinant IFN-α1. The T₂₁₇A₂₂₁ reverted variant replicated to levels 23-fold higher than the T₂₁₇T₂₂₁ strain in IFN-α1 treated cells. Finally, reverted TA strains were virulent when tested in an in vivo trial in susceptible salmon fry. In conclusion, these results indicate that stress plays a key role in viral replication in vivo and can facilitate conditions that will allow reversion from attenuated virus variants of IPNV.     

Challenges in End-of-Life Decisions in the Intensive Care Unit: An Ethical Perspective

When making end-of-life decisions in intensive care units (ICUs), different staff groups have different roles in the decision-making process and may not always assess the situation in the same way. The aim of this study was to examine the challenges Danish nurses, intensivists, and primary physicians experience with end-of-life decisions in ICUs and how these challenges affect the decision-making process. Interviews with nurses, intensivists, and primary physicians were conducted, and data is discussed from an ethical perspective. All three groups found that the main challenges were associated with interdisciplinary collaboration and future perspectives for the patient. Most of these challenges were connected with ethical issues. The challenges included different assessments of treatment potential, changes and postponements of withholding and withdrawing therapy orders, how and when to identify patients’ wishes, and suffering caused by the treatment. To improve end-of-life decision-making in the ICU, these challenges need to be addressed by interdisciplinary teams.     

The viability of cryopreserved PBPC depends on the DMSO concentration and the concentration of nucleated cells in the graft

BACKGROUND: DMSO is widely used as a cryoprotectant for PBPC. It is desirable to reduce the amount of DMSO without jeopardizing the quality of the stem cell product. The present study was undertaken to investigate whether recovery and survival of CD34+ cells would be significantly altered when PBPC used for autologous transplantations were cryopreserved with four different DMSO concentrations. METHODS: Apheresis samples of PBPC from 20 consecutive patients were mixed in parallel with 2%, 4%, 5% and 10% DMSO, frozen with identical cell concentrations at a controlled rate, and stored in liquid nitrogen for 6-8 weeks. PBPC samples from 11 consecutive patients were also cryopreserved with two different cell concentrations (150 and 300 x 10(6) nucleated cells/mL) to investigate the effect of increasing the cell concentrations while decreasing the DMSO concentration. The flow cytometric absolute count method, based on ISHAGE guidelines, was used to measure the absolute count of total and viable CD34+ cells in the post-thaw samples. RESULTS: PBPC cryopreserved at 150 x 10(6) cells/mL with 2% DMSO yielded significantly inferior CD34+ cell recovery (P < 0.001) and survival (P < 0.001) compared with cryopreservation with 4% and 5% DMSO. This was also observed when comparing higher cell concentrations. However, a reduced cell survival (P = 0.02) was observed when the nucleated cell concentration was increased from 150 to 300 x 10(6) cells/mL in samples cryopreserved with 5% DMSO. DISCUSSION: We conclude that 5% DMSO may be the optimal dose for cryopreserving PBPC as long as the cells have not been concentrated at much more than 200 x 10(6) nucleated cells/mL.