Characterization of Engineered Actin Binding Proteins That Control Filament Assembly and Structure

Eukaryotic cells strictly regulate the structure and assembly of their actin filament networks in response to various stimuli. The actin binding proteins that control filament assembly are therefore attractive targets for those who wish to reorganize actin filaments and reengineer the cytoskeleton. Unfortunately, the naturally occurring actin binding proteins include only a limited set of pointed-end cappers, or proteins that will block polymerization from the slow-growing end of actin filaments. Of the few that are known, most are part of large multimeric complexes that are challenging to manipulate.We describe here the use of phage display mutagenesis to generate of a new class of binding protein that can be targeted to the pointed-end of actin. These proteins, called synthetic antigen binders (sABs), are based on an antibody-like scaffold where sequence diversity is introduced into the binding loops using a novel "reduced genetic code" phage display library. We describe effective strategies to select and screen for sABs that ensure the generated sABs bind to the pointed-end surface of actin exclusively.From our set of pointed-end binders, we identify three sABs with particularly useful properties to systematically probe actin dynamics: one protein that caps the pointed end, a second that crosslinks actin filaments, and a third that severs actin filaments and promotes disassembly

The Role of Actin Turnover in Retrograde Actin Network Flow in Neuronal Growth Cones

The balance of actin filament polymerization and depolymerization maintains a steady state network treadmill in neuronal growth cones essential for motility and guidance. Here we have investigated the connection between depolymerization and treadmilling dynamics. We show that polymerization-competent barbed ends are concentrated at the leading edge and depolymerization is distributed throughout the peripheral domain. We found a high-to-low G-actin gradient between peripheral and central domains. Inhibiting turnover with jasplakinolide collapsed this gradient and lowered leading edge barbed end density. Ultrastructural analysis showed dramatic reduction of leading edge actin filament density and filament accumulation in central regions. Live cell imaging revealed that the leading edge retracted even as retrograde actin flow rate decreased exponentially. Inhibition of myosin II activity before jasplakinolide treatment lowered baseline retrograde flow rates and prevented leading edge retraction. Myosin II activity preferentially affected filopodial bundle disassembly distinct from the global effects of jasplakinolide on network turnover. We propose that growth cone retraction following turnover inhibition resulted from the persistence of myosin II contractility even as leading edge assembly rates decreased. The buildup of actin filaments in central regions combined with monomer depletion and reduced polymerization from barbed ends suggests a mechanism for the observed exponential decay in actin retrograde flow. Our results show that growth cone motility is critically dependent on continuous disassembly of the peripheral actin network

Analysis of causes of a fault in a reinforced concrete multi-chamber tank at a waste water treatment plant, and the reinforcement measures applied

Przedstawiono przypadek awarii wielokomorowego, żelbetowego zbiornika oczyszczalni ścieków podczas próby szczelności. Przeprowadzona analiza wykazała błędy konstrukcyjne zbiornika, które podczas eksploatacji stwarzałyby poważne zagrożenie bezpieczeństwa. Zaproponowano sposób wzmocnienia zbiornika, który został z powodzeniem zrealizowany.A description is given of a case in which a fault was found in a multi-chamber reinforced concrete tank at a waste water treatment plant during a leakage test. Analysis revealed structural design errors which would have led to a serious safety risk while the tank was in use. A method of reinforcing the tank was proposed and successfully implemented

Dynamics of development of road gullies on loess areas

The paper presents the development of road gullies in the area covered with loess deposits. The study showed a substantial rate of the development of loess road gullies which averaged 4.5 cm⋅year–1, the minimum rate being 3 cm⋅year–1, and the maximum of 9 cm⋅year–1. The deepening of the gullies increased with exploitation time, drainage area and with longitudinal slope

Plonowanie zbóż ozimych w strefie oddziaływania zadrzewień śródpolnych na terenach urzeźbionych

W pracy omówiono wpływ zadrzewienia śródpolnego na plonowanie zbóż ozimych na polach z glebami lessowymi, o 10% spadku, podlegającym erozji wodnej powierzchniowej. Badania wykazały, że plon zbóż ozimych i jego komponenty w bezpośrednim sąsiedztwie zadrzewienia ulegają dużej redukcji i zależą od gatunku zboża i odległości strefy pola od drzew. Zadrzewienie ograniczało plon pszenicy w strefie pola do 1-krotnej wysokości drzew (drzewa niskie) i 1,5-krotnej wysokości drzew (drzewa wysokie), natomiast żyta do 1-krotnej wysokości drzew (niskie) i 2-krotnej wysokości drzew (wysokie). Żyto bardziej krzewiące się od pszenicy lepiej chroni glebę przed erozją wodną. Zadrzewienie chroni strefę pola do 0,25 wysokości drzew przed zmywaniem gleby po opadach atmosferycznych.The paper presents the influence of afforestation on winter cereals yield on fields on loess soil of about 10% slope, with the presence of water surface erosion. Research showed that yield of winter cereals and its components in direct neighbourhood of afforestation undergos large reduction and depends on species of cereals and distances from field zone to trees. Afforestation limits yield of wheat in field zone up to 1.0 height of trees (low trees) and 1.5 height of trees of (high trees), however in case of rye up to 1.0 height of trees (low) and 2.0 trees height (high). Rye is more spreading than wheat and it protects soil better against water erosion. Afforestation protects field zone up to 0.25 trees height against soil losses after atmospheric falls

Badania ilościowe podatności różnych gatunków gleb na erozję wodną w warunkach symulowanego deszczu

W pracy omówiono wyniki badań dotyczące występowania erozji wodnej gleb w warunkach symulowanego deszczu, wykonane na obiekcie modelowym (10 gatunków gleb w czarnym ugorze przy spadku terenu 10%). Badania ilościowe przeprowadzone w warunkach symulowanego deszczu potwierdziły znaczne zróżnicowanie ilości zmytego materiału glebowego uzyskanego w wyniku opadów naturalnych. W warunkach symulowanego opadu największy zmyw (398,2 g·m⁻²) wystąpił na glebie brunatnej właściwej wytworzonej z lessu, następnie na glebie płowej wytworzonej z pyłu zwykłego (256,7 g·m⁻²), madzie właściwej wytworzonej z piasku gliniastego mocnego pylastego (249,6 g·m⁻²) i na czarnoziemie zdegradowanym wytworzonym z gliny lekkiej (158,5 g·m⁻²). Najmniejsze straty wystąpiły na glebie rdzawej o składzie granulometrycznym piasku luźnego (4,7 g·m⁻²).The work presents research results of occurrence of water erosion in conditions of simulated rain, executed on model object (10 kinds of soils in black fallow at fall of terrain 10%). Quantitative investigations in conditions of simulated rain confirmed considerable differentiation of soil material washed out as a result of natural precipitation. In conditions of simulated fall largest soil loss (398.2 g·m⁻²) occured on brown soil from loess, then on lessive soil from oridinary dust (256.7), alluvial soil g·m⁻²) from strong clay dusty sand (249.6 g·m⁻²) and on degraded chernozem from light clay (158.5 g·m⁻²). Smallest soil losses occured on rusty soil from loose sand (4.7 g·m⁻²)

Estimating water erosion of the Bystra catchment using spatial modelling

The work included the production of an actual water erosion risk map for the area of Bystra watershed, basing on vector layers: potential water erosion risk and CORINE Land Cover 2000 as a source of land use information. The results show relative high share of actual erosion in avegare to highest intensities – 32.5% of Bystra catchment. Compared to potential water erosion, where the same grades cover 41.0% of watershed’s area, the erosion risk at high grades decreased only by 8.5%. Actually, according to the land use structure derived from CLC2000, around 9694 hectares undergo high water erosion intensity grades and needs erosion control measures

Characteristic of soils in Zwolenka River watershed

Characteristic of soils in Zwoleńka River watershed. The paper presents soil conditions for agricultural production in Zwoleńka River watershed. The soil cover consists mainly of podsolic and brown soils. They are counted among light and very light textured soils. Among arable soils dominate strongly acid one with low content of organic matter and very low content of macronutrients available for plants. The suitability of soils for agriculture production is generally week.W pracy opisano warunki glebowe w zlewni rzeki Zwoleński. Analizy dokonano w oparciu o zasoby informacji o glebach zgromadzone w IUNG-PIB w Puławach oraz badania agrochemiczne gleb reprezentatywnych dla danego obszaru. W zlewni Zwoleńki dominują gleby bielicowe i płowe o składzie granulometrycznym gleb lekkich. Zawartość próchnicy najczęściej waha się w przedziale 1,0-2,0%. Gleby wykazują w większości odczyn bardzo kwaśny lub kwaśny oraz niską i bardzo niską zawartość fosforu i potasu.Warunki glebowe dla produkcji rolniczej w badanej zlewni są słabe, pomimo tego dominują tu grunty orne. Na najsłabszych glebach powinna nastąpić zmiana sposobu użytkowania

Agricultural value of soils in upper part of Zagozdzonka River watershed

Agricultural value of soils in upper part of Zagożdżonka River watershed. The paper presents soil conditions for agricultural production in Zagożdżonka River watershed. They are counted among light and very light textured soils. The content of organic matter and the content of macronutrients available for plants is low or very low. Soil suitability for agriculture production is generally week. The weakest soils should be designated to afforestation