Discovery of an MIT-like atracotoxin family: Spider venom peptides that share sequence homology but not pharmacological properties with AVIT family proteins

This project identified a novel family of six 66-68 residue peptides from the venom of two Australian funnel-web spiders, Hadronyche sp. 20 and H. infensa: Orchid Beach (Hexathelidae: Atracinae), that appear to undergo N- and/or C-terminal post-translational modifications and conform to an ancestral protein fold. These peptides all show significant amino acid sequence homology to atracotoxin-Hvf17 (ACTX-Hvf17), a non-toxic peptide isolated from the venom of H. versuta, and a variety of AVIT family proteins including mamba intestinal toxin 1 (MIT1) and its mammalian and piscine orthologs prokineticin 1 (PK1) and prokineticin 2 PK2). These AVIT family proteins target prokineticin receptors involved in the sensitization of nociceptors and gastrointestinal smooth muscle activation. Given their sequence homology to MITI, we have named these spider venom peptides the MIT-like atracotoxin (ACTX) family. Using isolated rat stomach fundus or guinea-pia ileum organ bath preparations we have shown that the prototypical ACTX-Hvf17, at concentrations up to 1 mu M, did not stimulate smooth muscle contractility, nor did it inhibit contractions induced by human PK1 (hPK1). The peptide also lacked activity on other isolated smooth muscle preparations including rat aorta. Furthermore, a FLIPR Ca2+ flux assay using HEK293 cells expressing prokineticin receptors showed that ACTX-Hvf17 fails to activate or block hPK1 or hPK2 receptors. Therefore, while the MIT-like ACTX family appears to adopt the ancestral disulfide-directed beta-hairpin protein fold of MIT1, a motif believed to be shared by other AVIT family peptides, variations in the amino acid sequence and surface charge result in a loss of activity on prokineticin receptors. (c) 2005 Elsevier Inc. All rights reserved.

Modulation of insect Cav channels by peptidic spider toxins

Insects have a much smaller repertoire of voltage-gated calcium (Ca-v) channels than vertebrates. Drosophila melanogaster harbors only a single ortholog of each of the vertebrate Ca(v)1, Ca(v)2, and Ca(v)3 subtypes, although its basal inventory is expanded by alternative splicing and editing of Ca-v channel transcripts. Nevertheless, there appears to be little functional plasticity within this limited panel of insect Ca-v channels, since severe loss-of-function mutations in genes encoding the pore-forming a, subunits in Drosophila are embryonic lethal. Since the primary role of spider venom is to paralyze or kill insect prey, it is not surprising that most, if not all, spider venoms contain peptides that potently modify the activity of these functionally critical insect Ca-v channels. Unfortunately, it has proven difficult to determine the precise ion channel subtypes recognized by these peptide toxins since insect Ca-v channels have significantly different pharmacology to their vertebrate counterparts, and cloned insect Ca-v channels are not available for electrophysiological studies. However, biochemical and genetic studies indicate that some of these spider toxins might ultimately become the defining pharmacology for certain subtypes of insect Ca-v channels. This review focuses on peptidic spider toxins that specifically target insect Ca-v channels. In addition to providing novel molecular tools for ion channel characterization, some of these toxins are being used as leads to develop new methods for controlling insect pests. (c) 2006 Elsevier Ltd. All rights reserved.

Stray dogs in Bucharest, and the political economy of Romanian socialism. From hunting the “enemies” of Stalinist economy, to poisoning urban parasites, and the rise of urban anarchy: 1950s-1990s.

My paper discusses three different ways in which stray dogs have been intertwined with ideologies of economic and urban development in Romania. I categorize results from archival and ethnographic research under three major time periods: early socialism, late socialism, and post-socialism. During early socialism stray dogs were seen to be damaging the soviet economy by killing species that humans could also hunt, like rabbits. During late socialism, stray dogs appeared as the enemies of the communist city, and the department of urban sanitation was given orders to poison dogs with strychnine. Finally, the increasing number of stray dogs in Bucharest after the collapse of communism was seen as a direct result of former communist demolitions, and was also taken as a sign of the collapsing state. Through such examples my paper discusses how the state and particular population groups have seen dogs as parts of an unwanted and dangerous nature, rather than a species that needs to be protected. I argue that distinctions of nature and culture have served discourses of civilization and the view of Bucharest as a model socialist, and then European city. Throughout my paper I juxtapose the treatment of stray dogs with other, more “valued” urban natures like the protection of parks, the wide-spread hobby of pigeon breeding during socialist years, the most recent debate on saving the rural area of Rosia Montana from non-environmentally friendly methods of gold extraction, and the current trend of healthy eating and living.

La stampante 3D DELTA WASP 3MT - Verso la fabbricazione personale

La tesi segue il progetto della Delta WASP 3MT, stampante 3D di grandi dimensioni. Il lavoro parte da una analisi del contesto che incontra i temi dell'artigianato digitale e dell'autoproduzione. Successivamente viene fatta una analisi dei requisiti e delle soluzioni tecniche implementabili sulla macchina per soddisfarli. A questa segue una illustrazione degli interventi sulle varie parti della macchina. Infine si espongono brevemente i punti chiave elaborati per la comunicazione della macchina, dal naming alla strategia nei punti vendita.

Impact of ocean acidification and warming on the larval development of the spider crab Hyas araneus from different latitudes (54° vs 79°N), 2010

The combined impacts of future scenarios of ocean acidification and global warming on the larvae of a cold-eurythermal spider crab, Hyas araneus L., were investigated in one of its southernmost populations (living around Helgoland, southern North Sea, 54°N) and one of the northernmost populations (Svalbard, North Atlantic, 79°N). Larvae were exposed at temperatures of 3, 9 and 15°C to present day normocapnia (380 ppm CO2) and to CO2 conditions expected for the near or medium-term future (710 ppm by 2100 and 3000 ppm CO2 by 2300 and beyond). Larval development time and biochemical composition were studied in the larval stages Zoea I, II, and Megalopa. Permanent differences in instar duration between both populations were detected in all stages, likely as a result of evolutionary temperature adaptation. With the exception of Zoea II at 3°C and under all CO2 conditions, development in all instars from Svalbard was delayed compared to those from Helgoland, under all conditions. Most prominently, development was much longer and fewer specimens morphosed to the first crab instar in the Megalopa from Svalbard than from Helgoland. Enhanced CO2 levels (710 and particularly 3000 ppm), caused extended duration of larval development and reduced larval growth (measured as dry mass) and fitness (decreasing C/N ratio, a proxy of the lipid content). Such effects were strongest in the zoeal stages in Svalbard larvae, and during the Megalopa instar in Helgoland larvae.

Seawater carbonate chemistry and biological processes during experiments with spider crab Hyas araneus, 2009

Future scenarios for the oceans project combined developments of CO2 accumulation and global warming and their impact on marine ecosystems. The synergistic impact of both factors was addressed by studying the effect of elevated CO2 concentrations on thermal tolerance of the cold-eurythermal spider crab Hyas araneus from the population around Helgoland. Here ambient temperatures characterize the southernmost distribution limit of this species. Animals were exposed to present day normocapnia (380 ppm CO2), CO2 levels expected towards 2100 (710 ppm) and beyond (3000 ppm). Heart rate and haemolymph PO2 (PeO2) were measured during progressive short term cooling from 10 to 0°C and during warming from 10 to 25°C. An increase of PeO2 occurred during cooling, the highest values being reached at 0°C under all three CO2 levels. Heart rate increased during warming until a critical temperature (Tc) was reached. The putative Tc under normocapnia was presumably >25°C, from where it fell to 23.5°C under 710 ppm and then 21.1°C under 3000 ppm. At the same time, thermal sensitivity, as seen in the Q10 values of heart rate, rose with increasing CO2concentration in the warmth. Our results suggest a narrowing of the thermal window of Hyas araneus under moderate increases in CO2 levels by exacerbation of the heat or cold induced oxygen and capacity limitation of thermal tolerance.

Discovery of WASP-113b and WASP-114b, two inflated hot-Jupiters with contrasting densities

We present the discovery and characterisation of the exoplanets WASP-113b and WASP-114b by the WASP survey, SOPHIE and CORALIE. The planetary nature of the systems was established by performing follow-up photometric and spectroscopic observations. The follow-up data were combined with the WASP-photometry and analysed with an MCMC code to obtain system parameters. The host stars WASP-113 and WASP-114 are very similar. They are both early G-type stars with an effective temperature of ~5900K, [Fe/H] ~0.12 and T_{eff} ~4.1 dex. However, WASP-113 is older than WASP-114. Although the planetary companions have similar radii, WASP-114b is almost 4 times heavier than WASP-113b. WASP-113b has a mass of 0.48 M_{Jup} and an orbital period of ~4.5 days; WASP-114b has a mass of 1.77 M_{Jup} and an orbital period of ~1.5 days. Both planets have inflated radii, in particular WASP-113 with a radius anomaly of Re=0.35. The high scale height of WASP-113b (~950 km ) makes it a good target for follow-up atmospheric observations.

VLT FORS2 comparative transmission spectroscopy: Detection of Na in the atmosphere of WASP-39b from the ground

We present transmission spectroscopy of the warm Saturn-mass exoplanet WASP-39b made with the Very Large Telescope (VLT) FOcal Reducer and Spectrograph (FORS2) across the wavelength range 411-810nm. The transit depth is measured with a typical precision of 240 parts per million (ppm) in wavelength bins of 10nm on a V = 12.1 magnitude star. We detect the sodium absorption feature (3.2-sigma) and find evidence for potassium. The ground-based transmission spectrum is consistent with Hubble Space Telescope (HST) optical spectroscopy, strengthening the interpretation of WASP-39b having a largely clear atmosphere. Our results demonstrate the great potential of the recently upgraded FORS2 spectrograph for optical transmission spectroscopy, obtaining HST-quality light curves from the ground.