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961.
Csilla Stenger-Kovács Lívia Tóth Franciska Tóth Éva Hajnal Judit Padisák 《Hydrobiologia》2014,721(1):67-75
Diatoms are considered as an appropriate indicator group for ecological status assessment of surface waters. These organisms can be indicative not only of the waterchemical but also of the hydro-morphological characteristics (e.g., stream size, physical habitat diversity) of running waters. In this study, diatom diversity metrics (species number, Shannon diversity, and evenness) from 506 sites in Pannon ecoregion (Hungary) were compared to the Strahler stream order system established with ArcView GIS 3.2. SOM analyses were performed to exclude the effect of nutrients on diversity metrics along the stream orders. Mixed-effects linear models and Tukey’s post hoc test revealed a linear relationships between species number, diversity and stream orders on ecoregion level from first- to eighth-order streams. The species number increases with an average of 8%, and the diversity by 10% per unit increase of the stream order. However, we could not find relationships with evenness. Autotrophic diversity metrics based on diatom species data appear to increase parallel with the stream order while those of heterotrophic metrics (published in the literature) maximize at medium stream orders. We argue that stream order is a relevant typological parameter which can basically determine the diatom diversity metrics, and it is well applicable in biomonitoring. 相似文献
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964.
Astrid V. Stronen Barbara Molnar Paolo Ciucci Chris T. Darimont Lorenza Grottoli Paul C. Paquet Tim Sallows Judit E. G. Smits Heather M. Bryan 《Ecology and evolution》2021,11(15):10338
- Parasites are integral to ecosystem functioning yet often overlooked. Improved understanding of host–parasite associations is important, particularly for wide‐ranging species for which host range shifts and climate change could alter host–parasite interactions and their effects on ecosystem function.
- Among the most widely distributed mammals with diverse diets, gray wolves (Canis lupus) host parasites that are transmitted among canids and via prey species. Wolf–parasite associations may therefore influence the population dynamics and ecological functions of both wolves and their prey. Our goal was to identify large‐scale processes that shape host–parasite interactions across populations, with the wolf as a model organism.
- By compiling data from various studies, we examined the fecal prevalence of gastrointestinal parasites in six wolf populations from two continents in relation to wolf density, diet diversity, and other ecological conditions.
- As expected, we found that the fecal prevalence of parasites transmitted directly to wolves via contact with other canids or their excreta was positively associated with wolf density. Contrary to our expectations, the fecal prevalence of parasites transmitted via prey was negatively associated with prey diversity. We also found that parasite communities reflected landscape characteristics and specific prey items available to wolves.
- Several parasite taxa identified in this study, including hookworms and coccidian protozoans, can cause morbidity and mortality in canids, especially in pups, or in combination with other stressors. The density–prevalence relationship for parasites with simple life cycles may reflect a regulatory role of gastrointestinal parasites on wolf populations. Our result that fecal prevalence of parasites was lower in wolves with more diverse diets could provide insight into the mechanisms by which biodiversity may regulate disease. A diverse suite of predator–prey interactions could regulate the effects of parasitism on prey populations and mitigate the transmission of infectious agents, including zoonoses, spread via trophic interactions.
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966.
Krisztián?Kvell Tamás?Cz?mp?ly László?Hiripi Péter?Balogh József?Kóbor Lilla?Bodrogi Judit?E.?Pongrácz William?A.?Ritchie Zsuzsanna?B?szeEmail author 《Transgenic research》2010,19(1):105-112
Lentiviral technology is a powerful tool for the creation of stable transgenic animals. However, uncertainties have remained
whether constitutive promoters resist long-term silencing. We used concentrated HIV-1 based lentiviral vectors to create stable
transgenic BALB/c mice by perivitelline injection. In our vectors eGFP expression was driven by the human EF1α promoter. The
established transgenic animals were analyzed for eGFP expression by in vivo fluorescence imaging, PCR, histology and flow-cytometry.
eGFP expression showed even distribution without mosaicism; however, tissue-dependent differences of eGFP expression were
observed. Up to the sixth generation only one newborn showed eGFP inactivation. eGFP + transgenic bone marrow cells efficiently
provided long-term haemopoietic repopulation in radiation chimeras, regenerating all bone marrow-derived lineages with eGFP + cells
with distinct eGFP expression profiles. The established eGFP + BALB/c mouse strain is expected to be extremely useful in various
immunological experiments. 相似文献
967.
Judit Bassols Francisco J. Ortega José M. Moreno‐Navarrete Belén Peral Wifredo Ricart Jose‐Manuel Fernández‐Real 《Journal of cellular biochemistry》2009,107(6):1107-1117
Infiltration of monocyte‐derived macrophages into adipose tissue has been associated with tissue and systemic inflammation. It has been suggested that macrophage infiltration affects fat expansion through a paracrine action on adipocyte differentiation. Our working hypothesis is that factors released by monocytes/macrophages may also affect mature adipocyte biology. Human differentiated omental adipocytes were incubated with LPS and conditioned media obtained from human macrophage‐like cell line THP‐1, previously activated or not with LPS. We show that LPS greatly increased the secretion levels of pro‐inflammatory adipokines including IL‐6, IL‐8, GRO, and MCP‐1. Macrophage‐conditioned medium also upregulated IL‐6, IL‐8, GRO, and MCP‐1 mRNA expression and protein levels and led to the novo secretion of ICAM‐1, IL‐1β, IP‐10, MIP‐1α, MIP‐1β, VEGF, and TNFα. Human differentiated adipocytes treated by macrophage‐conditioned medium displayed marked reduction of adipocyte function as assessed by decreased phosphorylation levels of ERK1, ERK2, and p38α and reduced gene expression of lipogenic markers including PPAR‐γ and fatty acid synthase. These data show that macrophage‐secreted factors not only inhibit the formation of mature adipocytes but alter their function, suggesting that human differentiated omental adipocytes might also contribute to systemic chronic low‐grade inflammation associated with human obesity. J. Cell. Biochem. 107: 1107–1117, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
968.
Grenczer M Zsuga J Majoros L Pinter A Kemeny-Beke A Juhasz B Tosaki A Gesztelyi R 《Canadian journal of physiology and pharmacology》2010,88(11):1074-1083
The receptorial responsiveness method (RRM) was proposed to estimate changes in the concentration of an agonist in the microenvironment of its receptor. Usually, this is done by providing the equieffective concentration of another agonist for the same receptor or for a largely overlapping postreceptorial signaling ("test agonist"). The RRM is a special nonlinear regression algorithm to analyze a concentration-response (E/c) curve that represents the simultaneous actions of a single agonist concentration to be estimated and of increasing concentrations of the test agonist. The aim of this study was to explore whether asymmetry of the E/c curve to be analyzed influences the reliability of the RRM. For this purpose, computer simulation was performed by constructing symmetric and asymmetric E/c curves using the operational model of agonism, and then these curves were analyzed with the RRM. To perform the RRM, 2 types of equations were used: one involving the Hill equation, the simplest model of the E/c relationship, and one containing the Richards equation, an advanced model properly handling E/c curve asymmetry. Results of this study indicate that E/c curve asymmetry does not significantly influence the accuracy of the estimates provided by the RRM. Thus, when using the RRM, it is not necessary to replace the Hill equation with the Richards equation to obtain useful estimates. Furthermore, it was found that estimation of a high concentration of a high-efficacy agonist can fail when the RRM is performed with a low-efficacy test agonist in a system characterized by a small operational slope factor. 相似文献
969.
Phytoplankton in the physical environment: beyond nutrients, at the end, there is some light 总被引:1,自引:0,他引:1
This article summarizes the outcomes of the 15th Workshop of the International Association for Phytoplankton Taxonomy and
Ecology. Four major issues dealing with the role of physical factors in phytoplankton ecology were addressed in the articles
of this special volume: global change and its likely impacts on phytoplankton, the role of physical factors in the autecology
of particular species, impacts on the inocula for the following years, and the role of light in shaping phytoplankton dynamics.
Case studies from different types of aquatic environments (rivers, deep and shallow lakes, floodplain lakes, wetlands, oxbows,
and even the deep ocean) and from diverse geographical locations (not only from the Mediterranean and temperate regions, but
also from subtropical and tropical ones) have shown that physical forcing exerts a variety of selective pressures with impacts
ranging from molding shape and size of organisms to modifying, through cascade effects, the structure of whole ecosystems. 相似文献
970.
Eszter Nemeskéri Éva Sárdi Judit Remenyik Béla Kőszegi Pál Nagy 《Acta Physiologiae Plantarum》2010,32(6):1125-1134
The response to drought of six green- and yellow-podded varieties of green bean was investigated in a phytotron. These varieties
were also grown without irrigation in field experiments and analysis of leaf samples was carried out three times; before and
under flowering and pod ripening, respectively. At first, the carotene and raffinose contents of leaves increase during mild
drought (30/15°C). High temperature (35/25°C) combined with water deficiency resulted in a considerable decrease in leaf weight,
chlorophyll b, maltose content, as well as the level of water-soluble antioxidants of the leaves, while the content of lipid-soluble antioxidants
and raffinose content increased when compared with the control. The yellow-podded varieties of green beans responded to drought
much more sensitively than the green-podded ones. The results suggested that a selection method based on the activity of antioxidants
in the leaves can be used for testing the adaptability of numerous bean genotypes to drought. 相似文献