A prion fehérje konformációs átalakulásának vizsgálata = Studies on the conformational transition of the prion protein to protease-resistant forms.

Sajnos a 2006.-évi NF OTKA pályázatok keretét drasztikusan csökkentették. Ennek eredményeképpen az én pályázatom is csak az eredeti költségvetés majdnem 20%-t kapta, (ez egy fiatal OTKA PD ösztöndíj nélküli támogatásnak felel meg), ami természetesen az eredeti kutatási terv töredékes megvalósítására sem volt alkalmas. Sikerként könyvelhető el, hogy ennek ellenére sikerült a kutató csoportot elindítani, kulcs technikákat módszereket beállítani a laborban és kritikus kutatási modellrendszereket létrehozni. Sikerült olyan, az endogén prion fehérjére (PrP) knock-out sejtvonalakat kialakítani, amelyek mutáns PrP-ket, illetve különböző tag-gel megjelölt PrP variánsokat fejeznek ki; illetve nemzetközi együttműködés keretében olyan módszereket sikerült kifejleszteni, ami fehérjék poszt-translációs módosítását képesek detektálni. Másik eljárás, amit kidolgoztunk, nem csak a mutáns prion fehérjék feltekeredését tudja követni, de nagy áteresztő képességű fehérje feltekeredési kísérletekben is hasznosan alkalmazható. Ez utóbbi eljárást a Nature Biotechnology tudományos folyóirat is közlésre érdemesnek találta. | Since the budget of 2006 for NF OTKA proposals was drastically reduced, my NF proposal received support of about just 20% of that was planned (that is close to an F type proposal without PD grant). This support was not sufficient to keep any of the aims of the original proposal. Despite all these, we, I think, managed to use effectively the support we gained. The research group as well as key techniques and critical model systems were successfully established. Particularly, cell lines that are knock-out for the endogenous prion protein were developed expressing various mutant PrP-s. Moreover, in an international collaboration, methods were developed for the detection of post translation modifications of proteins. Most importantly, a technique was developed for monitoring the folding of the mutant PrP variants. This method that is also very useful for High Throughput applications was published in Nature Biotechnology

An optically activated cantilever using photomechanical effects in dye-doped polymer fibers

We report on what we believe is the first demonstration of an optically activated cantilever due to photomechanical effects in a dye-doped polymer optical fiber. The fiber is observed to bend when light is launched off-axis. The displacement angle monotonically increases as a function of the distance between the illumination point and the fiber axis, and is consistent with differential light-induced length changes. The photothermal and photo-reorientation mechanisms, each with its own distinct response time, are proposed to explain the observed time dependence. The measured degree of bending is consistent with a model that we have proposed which includes coupling between photoisomerization and heating. Most importantly, we have discovered that at high light intensity, a cooperative release of stress results in cis-to-trans isomerization that yields a large and abrupt length change.Comment: 13 pages, 16 figure

Soil temperature extrema recovery rates after precipitation cooling

From a one dimensional view of temperature alone variations at the Earth's surface manifest themselves in two cyclic patterns of diurnal and annual periods, due principally to the effects of diurnal and seasonal changes in solar heating as well as gains and losses of available moisture. Beside these two well known cyclic patterns, a third cycle has been identified which occurs in values of diurnal maxima and minima soil temperature extrema at 10 cm depth usually over a mesoscale period of roughly 3 to 14 days. This mesoscale period cycle starts with precipitation cooling of soil and is followed by a power curve temperature recovery. The temperature recovery clearly depends on solar heating of the soil with an increased soil moisture content from precipitation combined with evaporation cooling at soil temperatures lowered by precipitation cooling, but is quite regular and universal for vastly different geographical locations, and soil types and structures. The regularity of the power curve recovery allows a predictive model approach over the recovery period. Multivariable linear regression models alloy predictions of both the power of the temperature recovery curve as well as the total temperature recovery amplitude of the mesoscale temperature recovery, from data available one day after the temperature recovery begins

Winter Ecosystem Respiration and Sources of CO2 From the High Arctic Tundra of Svalbard: Response to a Deeper Snow Experiment

Currently, there is a lack of understanding on how the magnitude and sources of carbon (C) emissions from High Arctic tundra are impacted by changing snow cover duration and depth during winter. Here we investigated this issue in a graminoid tundra snow fence experiment on shale-derived gelisols in Svalbard from the end of the growing season and throughout the winter. To characterize emissions, we measured ecosystem respiration (Reco) along with its radiocarbon (14C) content. We assessed the composition of soil organic matter (SOM) by measuring its bulk-C and nitrogen (N), 14C content, and n-alkane composition. Our findings reveal that greater snow depth increased soil temperatures and winter Reco (25 mg C m−2 d−1 under deeper snow compared to 13 mg C m−2 d−1 in ambient conditions). At the end of the growing season, Reco was dominated by plant respiration and microbial decomposition of C fixed within the past 60 years (Δ14C = 62 ± 8‰). During winter, emissions were significantly older (Δ14C = −64 ± 14‰), and likely sourced from microorganisms decomposing aged SOM formed during the Holocene mixed with biotic or abiotic mineralization of the carbonaceous, fossil parent material. Our findings imply that snow cover duration and depth is a key control on soil temperatures and thus the magnitude of Reco in winter. We also show that in shallow Arctic soils, mineralization of carbonaceous parent materials can contribute significant proportions of fossil C to Reco. Therefore, permafrost-C inventories informing C emission projections must carefully distinguish between more vulnerable SOM from recently fixed biomass and more recalcitrant ancient sedimentary C sources