Predictions of total and total reaction cross sections for nucleon-nucleus scattering up to 300 MeV

Total reaction cross sections are predicted for nucleons scattering from various nuclei. Projectile energies to 300 MeV are considered. So also are mass variations of those cross sections at selected energies. All predictions have been obtained from coordinate space optical potentials formed by full folding effective two-nucleon (NN) interactions with one body density matrix elements (OBDME) of the nuclear ground states. Good comparisons with data result when effective NN interactions defined by medium modification of free NN t matrices are used. Coupled with analyses of differential cross sections, these results are sensitive to details of the model ground states used to describe nuclei

Size Doesn't Matter: Towards a More Inclusive Philosophy of Biology

notes: As the primary author, O’Malley drafted the paper, and gathered and analysed data (scientific papers and talks). Conceptual analysis was conducted by both authors.publication-status: Publishedtypes: ArticlePhilosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. ‘Macrobe’ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes – the dominant life form on the planet, both now and throughout evolutionary history – will transform some of the philosophy of biology’s standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology – including biofilm formation, chemotaxis, quorum sensing and gene transfer – that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations

The structure and function of the vegetative mycelium of ectomycorrhizal plants .4. Qualitative-analysis of carbohydrate contents of mycelium interconnecting host plants

Plants of Pinus spp. were grown in observation chambers with the mycorrhizal fungi Suillus bovinus, Pisolithus tinctorius or Paxillus involutus. After interconnecting mycelial systems had developed between plants, individual hosts in some chambers of each species were fed with 14CO2. Mycelia from radioactively labelled and unlabelled chambers were harvested and their carbohydrates were extracted, separated chromatographically and identified. The major carbohydrates in all of the fungi were trehalose, mannitol and arabitol, their relative proportions differing in the different fungi. The results are discussed in relation both to carbon nutrition of the fungus and to carbon transfer between interconnected plants

Disruption of root carbon transport into forest humus stimulates fungal opportunists at the expense of mycorrhizal fungi

Ectomycorrhizal fungi dominate the humus layers of boreal forests. They depend on carbohydrates that are translocated through roots, via fungal mycelium to microsites in the soil, wherein they forage for nutrients. Mycorrhizal fungi are therefore sensitive to disruptive disturbances that may restrict their carbon supply. By disrupting root connections, we induced a sudden decline in mycorrhizal mycelial abundance and studied the consequent effects on growth and activity of free living, saprotrophic fungi and bacteria in pine forest humus, using molecular community analyses in combination with enzyme activity measurements. Ectomycorrhizal fungi had decreased in abundance 14 days after root severing, but the abundance of certain free-living ascomycetes was three times higher within 5 days of the disturbance compared with undisturbed controls. Root disruption also increased laccase production by an order of magnitude and cellulase production by a factor of 5. In contrast, bacterial populations seemed little affected. The results indicate that access to an external carbon source enables mycorrhizal fungi to monopolise the humus, but disturbances may induce rapid growth of opportunistic saprotrophic fungi that presumably use the dying mycorrhizal mycelium. Studies of such functional shifts in fungal communities, induced by disturbance, may shed light on mechanisms behind nutrient retention and release in boreal forests. The results also highlight the fundamental problems associated with methods that study microbial processes in soil samples that have been isolated from living roots.

Mycelial uptake, translocation and assimilation of N-15-labeled nitrogen by ectomycorrhizal Pinus sylvestris plants

Mycolial uptake, translocation and assimilation of 15N-labelled ammonium was followed in Pinus sylvestris plants infected with the ectomycorrhizal fungus. Paxillus involutus. The distribution of labelled compounds within the systems was examined using gas chromatography / mass spectrometry. Labelled nitrogen was incorporated into a range of free amino acids in the fungal mycelium, the principal sinks being alanine and glutamatelglutamine. Levels of 15 N enrichment declined throughout the transport pathway from 30-45% in the mycelium a~d mycorrhlzal root lips to 3-11% in the plant shoots. A significant proportion of the total assimilated nitrogen (27%) was incorporated into proteinaceous material and the proportion of label present in this fraction increased from 27% in the mycelium to 32% and 58% in the plant roots and needles respectively. The protein-incorporated amino acids showed a wider spectrum of labelling with significant amounts of 15N incorporated into valine, isoleucine, phenylalanine and lysine

Uptake, translocation and assimilation of nitrogen from 15N-labeled ammonium and nitrate sources by intact ectomycorrhizal systems of Fagus sylvatica infected with Paxillus involutus

The uptake and assimilation of nitrogen from 15N-labelled ammonium and nitrate sources was followed in intact ectomycorrhizal systems containing Fagus sylvatica L. plants infected with the fungus Paxillus involutus (Mich. ex Pers.) Cohen & Couch. Plants were grown in flat perspex observation chambers containing non-sterile peat; the fungal mycelium growing from a host plant was allowed to cross a barrier and to colonize an area of peat from which roots had been excluded. Labelled ammonium chloride or sodium nitrate was fed to the mycelium, and the shoot, root and mycelial tissues analysed for total and 15N-labelled amino acid contents after a feeding period of 72 h. Both free and protein-incorporated amino acids were analysed. Labelled nitrogen was incorporated into a range of free amino acids, the principal sinks for assimilation being alanine, aspartate/asparagine and glutamate/glutamine. The spectrum of labelling in protein-incorporated amino acids was wider with significant incorporation into the above compounds but additional assimilation of nitrogen as glycine, valine, serine, leucine, isoleucine and arginine. In total 78% of the nitrogen assimilated was incorporated into proteinaceous material. Label was incorporated from both nitrogen sources but the levels of enrichment in most free and protein-bound amino acids were usually higher in systems supplied with ammonium than in those supplied with nitrate. The mean amount of nitrogen assimilated from nitrate was only 62% of that assimilated from ammonium

Determination of N-15-labeled ammonium and total nitrogen in plant and fungal systems using mass-spectrometry

A selected ion-monitoring method to measure 15N-labelled ammonia in biological samples was improved to simplify sample handling, to obviate interference from ammonia due to the decomposition of glutamine and to allow the determination of total N. Ammonia is derivatized with pentafluorobenzoylchloride to yield pentafluorobenzamide which is analysed by gas chromatography/mass spectrometry after clean-up using disposable silicic acid columns. The sensitivity achieved when operating in the negative ion-chemical ionization mode was somewhat higher than when using electron-impact ionization. Use of methyl amine as an internal standard improved the accuracy and precision of the measurements. The method was applied to samples taken from an intact ectomycorrhizal system fed with ISN-labelled ammonium and used to determine patterns of N assimilation into ammonium, free amino acids and macromolecular compounds