A turbulencia hatásai a balatoni zooplankton szerkezetére és funkciójára = The effects of turbulence on the structure and function of the zooplankton in Lake Balaton

A kutatás rávilágított a Balaton vízszint ingadozásának és turbulens kinetikai energia tartalma változásainak nagy hatására a tó biológiai anyagforgalmában kulcs szerepet játszó zooplankton életére. Intenzív terepvizsgálatokkal, a szélsebesség, a vízszint, az RMS-turbulencia és a zooplankton monitorozásával bemutattuk és leírtuk a zooplankton szerkezetének és mennyiségének szoros összefüggését a víztömeg turbulencia intenzitsával, amely a szélsebesség mellett a mindenkori vízállástól függ. Meghatároztuk a szélsebesség, a vízszint és a víz turbulencia intenzitásának összefüggéseit a Balatonban. A terepvizsgálatok, és laboratóriumi kísérletek során meghatároztuk azokat a turbulencia intenzitás küszöbértékeket, amelyek felett (i) szétzilálódik a tavi zooplankton vertikális struktúrája, (ii) a fellépő turbulens nyíróerők fizikailag sértik az érzékeny zooplankton fajok egyedeit, és (iii) a különféle taxonómiai- és életforma csoportok populációi tömegesen pusztulnak és funkciójuk kiesik a planktonrendszerből. E küszöbértékek ismeretében olyan módon optimalizálható a tavi vízszint (legyen az legalább 75 cm-es) és a vízmérleg, hogy ne csökkenjen zooplankton funkciója, amely az magas lebegőanyag tartalom miatt általában is alacsony szintű. Az eredményeket alkalmasnak tartjuk a balatoni vízmérleg tervezés, a medermélyítések, a biomanipulációs beavatkozások és halgazdálkodás területén közvetett és közvetlen haszon elérésére. | According to the four years long intensive monitoring of the RMS-turbulence, the wind velocity, water level and the zooplankton we revealed strong evidences of the negative effect of the increased turbukence coupled with water level decrease on the species composition, structure, abundance and function of the zooplankton in Lake Balaton, We experimentally determined those thresholds of the wind velocity and turbulence intensity above which (i) vertical structure of the zooplankton assemblages disintergrate, (ii) individuals of the different zooplankton taxa suffer severe injuries from the increased turbukent shear forces and (iii) their populations break down. Based on the obtained hydrodinamical information the water level could be adjusted (in an aforded 75 cm as minimal) and the water ballance optimalized so that fend the disturbance effect of the increased turbulence on the zooplankton funcion off. The obtained results are suitable and warmely offered for endusing by the lake management, in the fileds of the planning of the water ballance, lake bad excavation and biomanipulation

Membrane protein dynamics: limited lipid control

Correlation of lipid disorder with membrane protein dynamics has been studied with infrared spectroscopy, by combining data characterizing lipid phase, protein structure and, via hydrogen-deuterium (H/D) exchange, protein dynamics. The key element was a new measuring scheme, by which the combined effects of time and temperature on the H/D exchange could be separated. Cyanobacterial and plant thylakoid membranes, mammalian mitochondria membranes, and for comparison, lysozyme were investigated. In dissolved lysozyme, as a function of temperature, H/D exchange involved only reversible movements (the secondary structure did not change considerably); heat-denaturing was a separate event at much higher temperature. Around the low-temperature functioning limit of the biomembranes, lipids affected protein dynamics since changes in fatty acyl chain disorders and H/D exchange exhibited certain correlation. H/D exchange remained low in all membranes over physiological temperatures. Around the high-temperature functioning limit of the membranes, the exchange rates became higher. When temperature was further increased, H/D exchange rates went over a maximum and afterwards decreased (due to full H/D exchange and/or protein denaturing). Maximal H/D exchange rate temperatures correlated neither with the disorder nor with the unsaturation of lipids. In membrane proteins, in contrast to lysozyme, the onsets of sizable H/D exchange rates were the onsets of irreversible denaturing as well. Seemingly, at temperatures where protein self-dynamics allows large-scale H/D exchange, lipid-protein coupling is so weak that proteins prefer aggregating to limit the exposure of their hydrophobic surface regions to water. In all membranes studied, dynamics seemed to be governed by lipids around the low-temperature limit, and by proteins around the high-temperature limit of membrane functionality

Infrared spectroscopy of phytochrome and model pigments

Fourier-transform infrared difference spectra between the red-absorbing and far-red-absorbing forms of oat phytochrome have been measured in H2O and 2H2O. The difference spectra are compared with infrared spectra of model compounds, i.e. the (5Z,10Z,15Z)- and (5Z,10Z,15E)-isomers of 2,3,7,8,12,13,17,18-octaethyl-bilindion (Et8-bilindion), 2,3-dihydro-2,3,7,8,12,13,17,18-octaethyl-bilindion (H2Et8-bilindion), and protonated H2Et8-bilindion in various solvents. The spectra of the model compounds show that only for the protonated forms can clear differences between the two isomers be detected. Since considerable differences are present between the spectra of Et8-bilindion and H2Et8-bilindion, it is concluded that only the latter compound can serve as a model system of phytochrome. The 2H2O effect on the difference spectrum of phytochrome supports the view that the chromophore in red-absorbing phytochrome is protonated and suggests, in addition, that it is also protonated in far-red-absorbing phytochrome. The spectra show that protonated carboxyl groups are influenced. The small amplitudes in the difference spectra exclude major changes of protein secondary structure

Silencing Agrobacterium oncogenes in transgenic grapevine results in strain-specific crown gall resistance

Crown gall disease of grapevine induced by Agrobacterium vitis or Agrobacterium tumefaciens causes serious economic losses in viticulture. To establish crown gall-resistant lines, somatic proembryos of Vitis berlandieri × V. rupestris cv. 'Richter 110' rootstock were transformed with an oncogene-silencing transgene based on iaaM and ipt oncogene sequences from octopine-type, tumor-inducing (Ti) plasmid pTiA6. Twentyone transgenic lines were selected, and their transgenic nature was confirmed by polymerase chain reaction (PCR). These lines were inoculated with two A. tumefaciens and three A. vitis strains. Eight lines showed resistance to octopine-type A. tumefaciens A348. Resistance correlated with the expression of the silencing genes. However, oncogene silencing was mostly sequence specific because these lines did not abolish tumorigenesis by A. vitis strains or nopaline-type A. tumefaciens C58

Ecological divergence of Chaetopteryx rugulosa species complex (Insecta, Trichoptera) linked to climatic niche diversification

Climate is often considered to be an important, but indirect driver of speciation. Indeed, environmental factors may contribute to the formation of biodiversity, but to date this crucial relationship remains largely unexplored. Here we investigate the possible role of climate, geological factors, and biogeographical processes in the formation of a freshwater insect species group, the Chaetopteryx rugulosa species complex (Trichoptera) in the Western Balkans. We used multi-locus DNA sequence data to establish a dated phylogenetic hypothesis for the group. The comparison of the dated phylogeny with the geological history of the Western Balkans shows that lineage formation coincided with major past Earth surface and climatic events in the region. By reconstructing present-day habitat conditions (climate, bedrock geology), we show that the lineages of C. rugulosa species complex have distinct climatic but not bedrock geological niches. Without exception, all splits associated with Pliocene/Pleistocene transition led to independent, parallel split into ‘warm’ and ‘cold’ sister lineages. This indicates a non-random diversification on the C. rugulosa species complex associated with late Pliocene climate in the region. We interpreted the results as the diversification of the species complex were mainly driven by ecological diversification linked to past climate change, along with geographical isolation

Differential expression of PRLIPs, a pathogenesis-related gene family encoding class 3 lipase-like proteins in Arabidopsis

In plants plenty of inducible defense-related proteins classified into 17 pathogenesis-related (PR) families have been described. Expression of homologous PR genes from the same family can be induced by the different defense hormones, like salicylic acid (SA), jasmonic acid (JA) or ethylene (ET), and are also regulated in a organ- or tissue-specific manner. A recently identified pathogenesis-related gene family, the PRLIP (pathogenesis-related lipase) has 9 members in Arabidopsis and their organization and expression pattern — as it is summarized in this study — is similar to the one of genes coding for other PR proteins. PRLIP3, PRLIP8 and PRLIP9 showed a relatively high expression in all tissues tested with a maximum in root (PRLIP3), stem (PRLIP8) or siliques (PRLIP9). The activity of PRLIP3 gene was further induced by SA and JA treatment. Other members (PRLIP1, PRLIP2, PRLIP4 and PRLIP6), however, were detected only in some of the tested organs. High levels of PRLIP1 mRNA occurred in all green tissues and in siliques, while in the latter PRLIP2 also displayed high expression. PRLIP6 and PRLIP4 exhibited root specific transcription while no mRNAs of PRLIP5 and PRLIP7 were detected in any plant tissues examined. In leaves SA treatment enhanced PRLIP1 and PRLIP2 expression, JA treatment induced PRLIP6 and ET treatment upregulated both PRLIP1 and PRLIP6. This organization and expression diversity of the PRLIP gene family is typical to plant PR genes suggesting the encoded proteins might serve essential functions in plant defense or priming