Diversity patterns of trait-based phytoplankton functional groups in two basins of a large, shallow lake (Lake Balaton, Hungary) with different trophic state

The application of functional approaches in understanding phytoplankton community-level responses to changes in the environment has become increasingly widespread in recent years. Eutrophication is known to cause profound modifications in ecosystem processes, however, the underlying relationships between environmental drivers and phytoplankton diversity and functioning are complex and largely unknown. Therefore, in the present study we investigated and compared the temporal diversity patterns of phytoplankton functional groups in the mesotrophic eastern and eutrophic western basin of the shallow Lake Balaton situated in Hungary. Diversity data were derived from taxonomic composition and biomass data corresponding to the years 2005-2006 and 2008-2009. With the use of cluster analysis phytoplankton species were classified into eight distinct groups representing different combinations of functionally relevant traits including greatest axial linear dimension, surface to volume ratio, photosynthetic pigment composition, N2-fixation, phagotrophic potential, growth form/complexity (unicell, filamentous, colony- or coenobiumforming) and motility. Our results have revealed that there is a significant inverse relationship between the functional group diversity used in our study and trophic state (total phytoplankton biomass) as opposed to species diversity, where no correlation was observed. In addition, group evenness showed an even stronger negative correlation with trophic state, while species evenness yielded only a weak relationship. The observed variability in functional group diversity suggests that such an approach could provide an efficient means of revealing structural changes in phytoplankton communities, establishing new hypotheses and highlighting fundamental points in ecosystem functioning

Phytoplankton functional composition shows higher seasonal variability in a large shallow lake after a eutrophic past

Abstract Eutrophication is a well‐known problem of global proportions with some easily recognizable and potentially harmful effects on aquatic habitats, but our knowledge on the underlying associated changes in ecosystem functioning is rather limited. Relevant studies suggest that seasonal variability in the functional composition of phytoplankton shows an increase as eutrophication progresses. The aim of the present study was to test this hypothesis through the assessment of long‐term changes in the functional diversity and composition of phytoplankton in a large shallow lake situated in Central Europe with a history of dramatic changes in trophic state. Contrary to our expectations, results have shown that the maximum range of compositional variability had a significant negative correlation with the summer biomass maxima. On the other hand, average seasonal variability measured as annual beta diversity exhibited an increasing trend throughout the years from the period of early eutrophication to the recent period of reoligotrophication, seemingly following a decline in functional richness and a long‐term rise in annual mean water temperature. The enhanced variability in phytoplankton succession implies that all the ecosystem processes connected to the phytoplankton follow more complex seasonal dynamics. Besides changing community structure, trophic state also seems to be an important factor in setting the limits to compositional changes during the annual cycle, whereas long‐term warming is likely to enhance instability in the phytoplankton. The trajectories of these two factors and the changes in seasonal succession indicate a lake in transition, urging more in‐depth research efforts to understand the impact of climate change on this specific ecosystem, and raise the question of whether the observed changes can also occur in other similar aquatic systems

A terápierezisztencia vizsgálata kutyák daganatos, immunológiai és szívelégtelenséggel járó kórképeiben = Examination of multidrug resistance in canine neoplastic immune mediated and cardiac disorders

Daganatszövetben, azokból és vérből elkülönített sejtekben mutattuk ki az multidrog rezisztencia- (MDR-) fehérjéket immunhisztokémiai (IHC), western blot, ill. a kódoló mRNS-ek mennyiségét, és rt-PCR-es módszerekkel. Az MDR funkciót áramlási (flow) citométeres (FC) és szcintigráfiás (SC) módszerrel is elemeztük. Megállapítottuk, hogy kutyák lymphomájában, a „b” alstádiumú, és T-sejtes immunfenotípusú, nem teljes remissziót mutató, nőstény ivarú esetekben, és a tubulopapillaris ED-kben a Pgp (MDR1) IHC expresszió mértéke szignifikánsan nagyobb a többi esethez képest, ennek mértéke korrelál a rövidebb recidívamentes túléléssel, és a rövidebb élettartammal. Hasonlóan prognosztikus információra jutottunk az in vitro FC (Calcein-teszt), és az in vivo SC (99mTc-MIBI) funkcionális tesztekkel. Az FC vizsgálatok alkalmasok voltak a vérben keringő lymphocytákban a kemoterápia során indukálódó fokozott MDR- transzporter funkció vizsgálatára is. Kutyák nyirokcsomójából izolált „short-term” túlélő sejtek kemoterápiás kezelésének apoptosis vizsgálata alapján megállapítottuk, hogy a doxorubicin a ciklofoszfamiddal, a vinkrisztin a metilprednizolonnal keresztrezisztenciát mutat. Kutyák lymphomájában vizsgáltuk az MDR1, mrp1, mrp2, BCRP membrántranszporterek mRNS-szintjét, azt találtuk, hogy az MDR1, ill. BCRP expressziók mennyiségei prognosztikusnak minősülnek. Szívbeteg, és immun-betegségben szenvedő kutyák lymphocytáinak MDR1, mrp1, mrp2, BCRP mRNS-expresszió szintjeit is vizsgáltuk nem kellő elemszámban. | Multidrug resistance (MDR) proteins were detected by immunohistochemical (IHC), western-blot, techniques and mRNA levels were determined by rt-PCR method in tumour tissues, separated tumour cells, and lymphocytes of peripheral blood. MDR functional tests were performed by flow cytometric (FC) and scyntigraphic (SC) methods. We’ve found that Pgp (MDR1) IHC expression levels were significantly higher in canine lymphoma with “b” substage, T-cell tpye, non complete remission, female and in MGTs in tubulopapillary forms compared to other cases. Higher expression levels were correlating with the shorter relapse free periods (RFP), and overall survival times (OST). Similar prognostic information could be gained by the in vitro FC (Calcein) test, and the in vivo SC (99mTc-MIBI) method. Calcein test was useful for the determination of increased MDR function which is induced in small lymphocytes of peripheral blood during cytostatic treatment. Isolated cells derived from lymph nodes of dogs with lymphoma were examined in “short term” cell cultures treated in vitro by chemotherapy drugs showed similarity in apoptosis between doxorubicin-cyclophosphamide and vincristine-methylprednisolone. Rt-PCR examinations were performed in canine lymphoma for the determination of mRNA expression levels of MDR1, mrp1, mrp2, BCRP. We’ve found that MDR1 and BCRP levels revealed to be prognostic in respect of RFP, and OST. MDR1, mrp1, mrp2, BCRP mRNA levels were determined in dogs with cardiac and immune- disease, the number of cases was not sufficient

Unique picoeukaryotic algal community under multiple environmental stress conditions in a shallow, alkaline pan

Winter phytoplankton communities in the shallow alkaline pans of Hungary are frequently dominated by picoeukaryotes, sometimes in particularly high abundance. In winter 2012, the ice-covered alkaline Zab-sze´k pan was found to be extraordinarily rich in picoeukaryotic green algae (42–82 9 106 cells ml-1) despite the simultaneous presence of multiple stressors (low temperature and light intensity with high pH and salinity). The maximum photosynthetic rate of the picoeukaryote community was 1.4 lg C lg chlorophyll a-1 h-1 at 125 lmol m-2 s-1. The assimilation rates compared with the available light intensity measured on the field show that the community was considerably light-limited. Estimated areal primary production was 180 mg C m-2 d-1. On the basis of the 18S rRNA gene analysis (cloning and DGGE), the community was phylogenetically heterogeneous with several previously undescribed chlorophyte lineages, which indicates the ability of picoeukaryotic communities to maintain high genetic diversity under extreme conditions

Unusual behaviour of phototrophic picoplankton in turbid waters

Autotrophic picoplankton (APP) abundance and contribution to phytoplankton biomass was studied in Hungarian shallow lakes to test the effect of inorganic turbidity determining the size distribution of the phytoplankton. The studied lakes displayed wide turbidity (TSS: 4–2250 mg l-1) and phytoplankton biomass (chlorophyll a: 1–460 μg l-1) range, as well as APP abundance (0 and 100 million cells ml-1) and contribution (0–100%) to total phytoplankton biomass. Inorganic turbidity had a significant effect on the abundance and contribution of APP, resulting in higher values compared to other freshwater lakes with the same phytoplankton biomass. Our analysis has provided empirical evidence for a switching point (50 mg l-1 inorganic turbidity), above which turbidity is the key factor causing APP predominance regardless of phytoplankton biomass in shallow turbid lakes. Our results have shown that turbid shallow lakes are unique waters, where the formerly and widely accepted model (decreasing APP contribution with increasing phytoplankton biomass) is not applicable. We hypothesize that this unusual behaviour of APP in turbid waters is a result of either diminished underwater light intensity or a reduced grazing pressure due to high inorganic turbidity

Association of PPAR Alpha Intron 7 G/C, PPAR Gamma 2 Pro12Ala, and C161T Polymorphisms with Serum Fetuin-A Concentrations

BACKGROUND: Both peroxisome activator proteins (PPARs) and fetuin-A play a role in lipid and glucose metabolism. AIMS: We investigated whether PPARalpha intron 7 G2468/C and PPARgamma2 Pro12Ala and PPARgamma exon 6 C161T polymorphisms are associated with serum fetuin-A concentrations. PATIENTS AND METHODS: The PPARalpha intron 7 G/C polymorphism was studied in cohort 1 (79 reference individuals, 165 postinfarction patients). The two PPARgamma polymorphisms were investigated in cohort 2 (162 reference individuals, 165 postinfarction patients). Fetuin-A levels and PPAR polymorphisms were determined by radial immunodiffusion and polymerase chain reaction-restriction fragment length polymorphism techniques. RESULTS: The C allele variant of PPARalpha intron 7 G2467C was associated with higher fetuin-A levels (p = 0.018). Postinfarction status (p = 0.001), PPARalpha intron 7 GG/GC/CC genotypes (p = 0.032), and the C allele (p = 0.021) were the strongest determinants of fetuin-A concentration in a multiple regression model. Higher fetuin-A levels were associated with the Pro variant of PPARgamma2 (p = 0.047). Postinfarction status (p = 0.041) and BMI (p < 0.001) but not PPARgamma2 Pro were the strongest determinants of fetuin-A concentrations. PPARgamma exon 6 C161T genotypes were not associated with fetuin-A levels. CONCLUSIONS: Fetuin-A was determined mainly by the PPARalpha intron 7C allele and postinfarction status in cohort 1 and the BMI and postinfarction in cohort 2. The PPARalpha intron 7C and PPARgamma2 Pro variants are associated with fetuin-A levels

Picophytoplankton predominance in hypersaline lakes (Transylvanian Basin, Romania)

The occurrence and importance of photoautotrophic picoplankton (PPP, cells with a diameter <2μm) was studied a long a trophic and salinity gradient in hypersaline lakes of the Transylvanian Basin (Romania. The studied lakes were found to be rich in PPP, with abundances (maximum:7.6 x 106 cells mL - ) higher than in freshwater and marine environments of similar trophic conditions. The contribution of PPP to the total phytoplankton bio volume did not decrease with in creasing trophic state as it was generally found in other aquatic environments. Regardless of the trophic conditions, the contribution of PPP could reach 90-100% in these hypersaline lakes. We hypothesized that the PPP predominance might be the result of the low grazing pressure, since heterotrophic nanoflagellates (the main grazers of PPP) were absent in the studied samples. There were significant differences in community composition among the lakes a long the salinity gradient. CyPPP predominated in less saline waters (mainly below 5%), while EuPPP were present along the entire salinity range (up to 18.7%), dominating the phytoplankton between 3 and 13% salin ity . Above 13% salinity, the phytoplankton was composed mainly of Dunaliella species