Effects on the ecological integrity of a soft-bottom habitat from a trawling disturbance

The effects of trawling disturbance on a soft-sediment system were investigated with a manipulative field experiment in an area that had been closed to shrimp trawling activities for 20 years. The area was also chosen for its weak natural physical agents i.e. no scouring of sediments by storm events or tidal flow, allowing a quantitative assessment of the effects of trawling on the benthic fauna and geochemical properties of the soft substrate.The study examined the ambient spatial and temporal patterns of sedimentological variables and benthic species abundances over a time interval of 16 months for both the reference and the trawl stations before dragging the trawling gear over the predetermined trawl sites. Shifts in the patterns of the benthic infauna and geochemical variables were identified by the post-trawl samples that were collected at both the reference and trawl stations over the next 6 months. Post-trawl changes in the bottom topography did not translate into changes in the vertical profile of the sedimentological variables. Chlorophyll a content of the trawled surface sediments was significantly elevated immediately after the trawling event in comparison to the reference concentrations.Immediately after the trawling disturbance, numbers of species, species abundance and diversity decreased in the trawled area in comparison to the reference area. Sensitive species were found to be the bivalves; Ennucula annulata, Hampson, Thyasira flexuosa (Montagu), and Yoldia sapotilla (Gould), and polychaetes; Chaetozonecf.setosa Malmgren, Anobothrus gracilis(Malmgren), Euchone incolor Hartman, and Terebellides atlantis Williams. In contrast, the carnivorous nemertea, Cerebratulus lacteus Verrill, was the resistant species to field manipulations on account of its predatory behavior; highly effective in seeking out freshly dead (dying) organisms and its active migration. Multivariate analysis confirmed the changes in the trawled community structure immediately following the trawling event and differences in the recovery patterns 6 months thereafter. Although the trawling disturbance was one of low frequency and intensity compared to commercial operations, the biological variables studied indicated that successional processes in this soft-bottom community were altered, at least for a short period, in response to the trawling disturbance.     

The antiviral response to gamma interferon

A role for alpha/beta interferon (IFN-alpha/beta) in the IFN-gamma antiviral response has long been suggested. Accordingly, possible roles for autocrine or double-stranded-RNA (dsRNA)-induced IFN-alpha/beta in the IFN-gamma response were investigated. Use was made of wild-type and a variety of mutant human fibrosarcoma cell lines, including mutant U5A cells, which lack a functional IFN-alpha/beta receptor and hence an IFN-alpha/beta response. IFN-gamma did not induce detectable levels of IFN-alpha/beta in any of the cell lines, nor was the IFN-gamma response per se dependent on autocrine IFN-alpha/beta. On the other hand, a number of responses to dsRNA [poly(I). poly(C)] and encephalomyocarditis virus were greatly enhanced by IFN-gamma pretreatment (priming) of wild-type cells or of mutant cells lacking an IFN-alpha/beta response; these include the primary induction of dsRNA-inducible mRNAs, including IFN-beta mRNA, and, to a lesser extent, the dsRNA-mediated activation of the p38 mitogen-activated protein (MAP) kinase(s). IFN-gamma priming of mRNA induction by dsRNA is dependent on JAK1 and shows biphasic kinetics, with an initial rapid (<30-min) response being followed by a more substantial effect on overnight incubation. The IFN-gamma-primed dsRNA responses appear to be subject to modulation through the p38, phosphatidylinositol 3-kinase, and ERK1/ERK2 MAP kinase pathways. It can be concluded that despite efficient priming of IFN-beta production, the IFN-alpha/beta pathways play no significant role in the primary IFN-gamma antiviral response in these cell-virus systems. The observed IFN-gamma priming of dsRNA responses, on the other hand, will likely play a significant role in combating virus infection in vivo.     

Ectomycorrhizal fungi of the Philippines: a preliminary survey and notes on the geographic biodiversity of the Sclerodermatales

Basidiomata of putative ectomycorrhizal fungi have been collected from under pine or dipterocarp stands in Central Luzon in the Philippines. Over 100 collections are reported. Among the material, 75 taxa have been recognised and assigned to known genera or at least placed close to already documented European, Japanese or North American taxa. Formal identifications for 46 species are given along with comments on previous collections from South-East Asia. Species collected from under the native Pinus kesiya resemble the communities found under three-needled pines in North America and the West Himalayas, whereas those from dipterocarp forests were similar to communities found in Malaysia and Japan. Members of the Sclerodermatales were particularly common and are probably the pioneer colonizers of young seedlings in these ecosystems.     

Impacts of Infection by Parasitic Angiosperms on Host Photosynthesis

Abstract: Parasitic angiosperms are a taxonomically diverse group of plants that invade host tissues and remove resources via a specialized structure known as the haustorium. Through the haustorium, carbon, water and mineral nutrients are withdrawn, often at the expense of host growth and vigour. In addition to the removal of resources from host plants, many parasitic angiosperms are also able to impact host growth via effects on host photosynthesis. In this paper we review what is known about how parasitic angiosperms affect host photosynthesis and the impact this has on host productivity. Holoparasites, that lack chlorophyll, act as extra sinks for host photosynthates and generally either enhance or have a neutral effect on host photosynthetic productivity. In contrast, hemiparasites, that are capable of some autotrophic carbon fixation, usually have a negative impact on host photosynthesis. Irrespective of the outcome of infection, the mechanisms involved in altering host photosynthesis are diverse and may act at either the leaf or whole-plant level. In some cases, parasites impact directly on host photosynthetic metabolism, while in others the effects are more indirect, for example through changing host architecture.     

Notes on British Boleti: II.

Summary

A key to the species of the genus Boletus sensu stricto based on habitat, microscopic and macroscopic characters is proposed. Three extra-limital species, as yet unrecorded from the British Isles, B. torosus, B. lupinus Krombh. and B. lupinus s. Bres., are included in the key in the hope that they may appear in future. They may have been overlooked previously or confused with far commoner forms, especially B. luridus, to which many quite distinct species have previously been referred. Also included in the key are three boletes not considered taxonomically to belong to this genus in its strict sense, although in some ways they are superficially similar. The only West European species of Tylopilus is keyed out and its taxonomic position considered. Boletus rubellus Krombh. placed by some American authors in Boletus sensu stricto is also discussed.     

Progress towards implementing the Biodiversity Action Plan for stipitate hydnoid fungi in Scotland

Summary

Stipitate hydnoid (‘tooth’) fungi are considered to be threatened throughout much of central and northern Europe. In response to concern about the status of these fungi in the UK, a Biodiversity Action Plan has been developed for 14 species in this group. As a first step towards implementation of this plan, a number of surveys have been initiated, to determine the current status and distribution of hydnoid fungi. An overview of the results of these surveys is described. A series of distribution maps are presented, based on a compilation of early records and the results of a recent field survey in Scottish coniferous forests. The difficulties of interpreting early records are discussed, with particular reference to the taxonomie confusion that has surrounded this group of fungi. Although available data provide little evidence for decline of hydnoid fungi, a number of species display very restricted distributions within Scotland. The recent discovery of several species new to Britain emphasises the need for further field surveys to define the current status of these fungi with greater accuracy.