The effect of spatial scale on interactions between two weevils and their parasitoid

1. The effect of spatial scale on the interactions between three hymenopteran parasitoids and their weevil hosts was investigated. The parasitoid Mesopolobus incultus (Walker) parasitised Gymnetron pascuorum Gyll.; the parasitoids Entodon sparetus (Walker) and Bracon sp. parasitised Mecinus pyraster Herbst. Both of these weevils develop inside the seedhead of Plantago lanceolata L. but occupy different niches. Seedheads were sampled annually from 162 plants at each of two experimental sites consisting of a series of habitat patches of two distinct sizes. Data were analysed from three site-years. 2. Parasitoid densities at each site-year were closely related to the abundance of their respective weevil hosts. The overall proportion of hosts parasitised was more variable for M. incultus than for E. sparetus and Bracon sp. 3. Changes in spatial scale affected the variability of parasitoid densities. For M. incultus, there was generally a greater degree of additional heterogeneity for all increases of scale; for E. sparetus, this was true only at the largest scales; for Bracon sp., all components of variance were negative. 4. The rate of parasitism was related to host density in different ways at different spatial scales. Mesopolobus incultus exhibited inverse density dependence at the finest (seedhead) scale, direct density dependence at the intermediate (plant) scale, and density independence at the large (habitat area 729 m2) scale. Entodon sparetus showed no response to variation in host density at any spatial scale. Bracon sp. showed direct density dependence only at the intermediate and largest scales. 5. Parasitoids E. sparetus and Bracon sp. seemed able to detect more than one M. pyraster individual in seedheads with multiple host occupancy; a greater incidence of conspecific parasitoids than expected emerged from such seedheads.

L'histoire assassinee: Manfredo Tafuri and the present

Italian historian Manfredo Tafuri develops his ‘historical project’ in architecture during the 1960’s and 1970’s in three seminal books, which reach the English speaking specialist audience with a certain delay. Histories and Theories of Architecture (1968), which prepares the ground for the redefinition of a critical and independent history of architecture is first translated in English in 1979. Architecture and Utopia (Progetto e utopia, 1973) is translated in 1976, and becomes a point of reference for architectural histories and for the definition of architectural theories, mainly in the United States. The Sphere and the Labyrinth (1980), translated in 1987, is the text which formally defines and presents the ‘historical project’. Tafuri’s dense and highly politicized prose is often subjected in the English versions to numerous simplifications and reductive interpretations. Yet, the time lag and the space between languages that these translations occupy are inhabited by polemical and fertile reactions to the texts from the world of architectural design. Symptomatic of all, Aldo Rossi’s L’architecture assassinée, a rebuke in drawing to some of Tafuri’s remarks in Architecture and Utopia that seemed to suggest -but the interpretation is arguable– the ‘death’ of architecture as project (progetto). Tafuri’s texts instigate a dialogue between architectural history and practice, particularly relevant at a time in the development of the discipline when history was being redefined in its critical role as a ‘project’ –thus appropriating the active and propositional role traditionally assigned to architectural design–, while architectural design –still coping with the legacy of Modernism and with changed production systems- often found itself relegated to the paper of exhibitions, competitions and theoretical projects. This paper explores the relationship between architectural history and design in Tafuri’s work, focusing on recent reconsideration and interpretations of his work. It argues that, beyond instrumental simplifications, Tafuri’s ‘project’ remains active and essential in architecture’s critical culture today.

The use of fluorescence microscopy to define polymer localisation to the late endocytic compartments in cells that are targets for drug delivery

Macromolecular therapeutics and nano-sized drug delivery systems often require localisation to specific intracellular compartments. In particular, efficient endosomal escape, retrograde trafficking, or late endocytic/lysosomal activation are often prerequisites for pharmacological activity. The aim of this study was to define a fluorescence microscopy technique able to confirm the localisation of water-soluble polymeric carriers to late endocytic intracellular compartments. Three polymeric carriers of different molecular weight and character were studied: dextrin (Mw~50,000 g/mol), a N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer (Mw approximately 35,000 g/mol) and polyethylene glycol (PEG) (Mw 5000 g/mol). They were labelled with Oregon Green (OG) (0.3-3 wt.%; <3% free OG in respect of total). A panel of relevant target cells were used: THP-1, ARPE-19, and MCF-7 cells, and primary bovine chondrocytes (currently being used to evaluate novel polymer therapeutics) as well as NRK and Vero cells as reference controls. Specific intracellular compartments were marked using either endocytosed physiological standards, Marine Blue (MB) or Texas-red (TxR)-Wheat germ agglutinin (WGA), TxR-Bovine Serum Albumin (BSA), TxR-dextran, ricin holotoxin, C6-7-nitro-2,1,3-benzoxadiazol-4-yl (NBD)-labelled ceramide and TxR-shiga toxin B chain, or post-fixation immuno-staining for early endosomal antigen 1 (EEA1), lysosomal-associated membrane proteins (LAMP-1, Lgp-120 or CD63) or the Golgi marker GM130. Co-localisation with polymer-OG conjugates confirmed transfer to discreet, late endocytic (including lysosomal) compartments in all cells types. The technique described here is a particularly powerful tool as it circumvents fixation artefacts ensuring the retention of water-soluble polymers within the vesicles they occupy.