Mikroskopieren ohne Mikroskop Andreas Korn‐Müller
Physik in unserer Zeit,
01/2024, Letnik:
55, Številka:
1
Journal Article
ZusammenfassungMit einem handelsüblichen, leistungsstarken Laserpointer und einer Kunststoffspritze kann man Mikroorganismen und Zellen ohne ein Mikroskop als Schatten sichtbar machen. Dazu wird der ...Laserstrahl durch einen an der Spritze hängenden Wassertropfen geschickt, der Zellen oder Plankton enthält. Aufgrund der sphärischen Oberfläche des Tropfens kommt es zu einem Vergrößerungseffekt. Mit Hilfe dieser einfachen „Laser‐Tropfen‐Methode“ ist man in der Lage, in jedem verdunkelbaren Raum oder Klassenzimmer Mundschleimhautzellen, Blutzellen und Mikroorganismen, wie Grünalgen oder Ruderfußkrebse, abzubilden.
A subset E of an ideal nano topological space (U,xR(X), J) is called: 1. ag#-nJ-open if G c a-nJ-int(E) whenever G c E and G is nag-closed in U. 2. 7#-nJ-open if G c p-nJ-int(E) whenever G c E and G ...is nag-closed in U. 3. /i#-nJ-open if G c s-nJ-int(E) whenever G c £" and G is nag-closed in //. ...we have, G c a-nO-int(E) whenever G c E and G is nag-closed in U. Now, G c E n nint (ncl* (nint (E))) c £" n nint(ncl(nint(E))) = na-int(E). ...we have, G c p-nO-int(E) whenever G c £" and G is nag-closed in //. ...G c £" n nint (ncl* (Ey) c £" n nint(ncl(E)) = np-int(E). ...we have, G c s-nO-int(E) whenever G c £" and G is nag-closed in U. Now, G c £" n ncl*(nint(E~)~) c £" n ncl(nint(E)) = s-int(E). ...we have, G c int(E) whenever G c £" and G is nag-closed in U. Now, G c nint ((nint (E))*) U nint(E) = nint ((nint (E))*) U nint (nint (Ey) c runt (runt (£"))* U nint^) = nint (ncl* (nint (E))). ...we have, G c a-nO-int(E) whenever G c £" and G is nag-closed in //. ...G c £" n nint (ncl* (nint (E))) c £" n nint (ncl* (E)) = p-nJ-int(E). ...we have, G c a-nO-int(E) whenever G c E and G is nag-closed in U. Now, G c E n nint(ncl*(nint(E))) c £" n ncZ*(nint(E~)~) = s-nJ-int(E). Assume that E is 7#-nJ-open and g\-nJ-set in U. Let G c E and G be nag-closed in U. Since £" is a gf-nJ-set in U, E = P n Q, where P is ng#-open and Q is a t-nJ-set. ...G is nag-closed and P is ng#-open implies G c nint(P). Since £" is 7#-nJ-open, G c p-nJ-nint(E) = E C\ nint(ncl*(E)) = (P r\Q) n nint{ncl\P n (?)) c (P n (?) n nint{ncl\P) n ncl\Q)) = PnQ n nint{ncl\P)) n nint(ncl*(Q)).
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Although it is widely recognized that cyanobacterial blooms have substantial influence on the plankton community in general, their correlations with the whole community of eukaryotic plankton at ...longer time scales remain largely unknown. Here, we investigated the temporal dynamics of eukaryotic plankton communities in two subtropical reservoirs over a 6-year period (2010-2015) following one cyanobacterial biomass cycle-the cyanobacterial bloom (middle 2010), cyanobacteria decrease (late 2010-early 2011), non-bloom (2011-2014), cyanobacteria increase, and second bloom (late 2014-2015). The eukaryotic community succession that strongly correlated with this cyanobacterial biomass cycle was divided into four periods, and each period had distinct characteristics in cyanobacterial biomass and environments in both reservoirs. Integrated co-occurrence networks of eukaryotic plankton based on the whole study period revealed that the cyanobacterial biomass had remarkably high network centralities, and the eukaryotic OTUs that had stronger correlations with the cyanobacterial biomass exhibited higher centralities. The integrated networks were also modularly responded to different eukaryotic succession periods, and therefore correlated with the cyanobacterial biomass cycle. Moreover, sub-networks based on the different eukaryotic succession periods indicated that the eukaryotic co-occurrence patterns were not constant but varied largely associating with the cyanobacterial biomass. Based on these long-term observations, our results reveal that the cyanobacterial biomass cycle created distinct niches between persistent bloom, non-bloom, decrease and increase of cyanobacteria, and therefore associated with distinct eukaryotic plankton patterns. Our results have important implications for understanding how complex aquatic plankton communities respond to cyanobacterial blooms under the changing environments.
The biological carbon pump is the process by which CO2 is transformed to organic carbon via photosynthesis, exported through sinking particles, and finally sequestered in the deep ocean. While the ...intensity of the pump correlates with plankton community composition, the underlying ecosystem structure driving the process remains largely uncharacterized. Here we use environmental and metagenomic data gathered during the Tara Oceans expedition to improve our understanding of carbon export in the oligotrophic ocean. We show that specific plankton communities, from the surface and deep chlorophyll maximum, correlate with carbon export at 150 m and highlight unexpected taxa such as Radiolaria and alveolate parasites, as well as Synechococcus and their phages, as lineages most strongly associated with carbon export in the subtropical, nutrient-depleted, oligotrophic ocean. Additionally, we show that the relative abundance of a few bacterial and viral genes can predict a significant fraction of the variability in carbon export in these regions.
Leben unter Druck
Biologie in Unserer Zeit,
October 2020, 20201001, Letnik:
50, Številka:
5
Journal Article
Recenzirano
Salpa thompsoni ist eine zu den Manteltieren gehörende Salpenart (Stamm Chordatiere, Klasse Thaliacea), die in den Meeresregionen rings um die Antarktis und Neuseeland vorkommt und deren ...ungeschlechtliche Einzeltiere bis zu 12 cm lang werden. Wie die meisten Salpen besitzt S. thompsoni einen tonnenförmigen Körper und filtert mit Hilfe ihres Kiemendarms Plankton aus dem Meerwasser. Die Fortbewegung erfolgt nach dem Rückstoßprinzip: Ein Wasserstrahl tritt durch die Ausströmöffnung (links im Bild) und schiebt den Körper aufgrund der Impulserhaltung nach vorne. In der Nähe der Ausströmöffnung sieht man die rotbraun gefärbten Eingeweide wie das Herz und den Verdauungstrakt. Salpen durchlaufen einen komplizierten Generationswechsel: Bei dem schnurartigen Gebilde auf der Bauchseite handelt es sich um eine Blastozooidenkette aus Geschlechtstieren, die durch Knospung entstehen. Die gallertartige Hülle hilft Salpen, ein Absinken in große Meerestiefen mit den dort herrschenden lebensfeindlichen Drücken zu verhindern. Mehr darüber, wie sich Lebewesen an Hochdruckbedingungen anpassen, lesen Sie auf Seite 331. Foto: Mike Stukel.
The Carpintero Lagoon is a wetland estuary, with 90.4ha of water surface, located in the center of the city of Tampico, Tamaulipas, Mexico, between 22°15'N-22°14'N and 97°52'W-97°52'W. Currently it ...contains several species under protection. The aim of this study was to analyze the composition and variation of phytoplankton communities during an annual cycle, as well as the establishment of microalgal cultures. Samples were taken every two months, using Van Dorn bottles. Samples were fixed with Lugol acetate 4% and cultures were established by serial dilution techniques and micropipettes. The principal groups found were cyanobacteria, dinoflagellates, euglenophyta, chlorophyta and bacillariophyta. Chlorophyta was the predominant group in March and August, while bacillariophyta was the most abundant group.
Abstract
We tracked temporal changes in protist diversity at the Long Term Ecological Research (LTER) station MareChiara in the Gulf of Naples (Mediterranean Sea) on eight dates in 2011 using a ...metabarcoding approach. Illumina analysis of the V4 and V9 fragments of the 18S rDNA produced 869 522 and 1 410 071 sequences resulting in 6517 and 6519 OTUs, respectively. Marked compositional variations were recorded across the year, with less than 2% of OTUs shared among all samples and similar patterns for the two marker tags. Alveolata, Stramenopiles and Rhizaria were the most represented groups. A comparison with light microscopy data indicated an over-representation of Dinophyta in the sequence dataset, whereas Bacillariophyta showed comparable taxonomic patterns between sequence and light microscopy data. Shannon diversity values were stable from February to September, increasing thereafter with a peak in December. Community variance was mainly explained by seasonality (as temperature), trophic status (as chlorophyll a), and influence of coastal waters (as salinity). Overall, the background knowledge of the system provided a sound context for the result interpretation, showing that LTER sites provide an ideal setting for high-throughput sequencing (HTS) metabarcoding characterisation of protist assemblages and their relationships with environmental variations.
Temporal diversity and community structure of the entire protist assemblage from the Gulf of Naples assessed using high throughput sequencing and light microscopy.
Microbial eukaryotes are key components of the ocean plankton. Yet, our understanding of their community composition and activity in different water layers of the ocean is limited, particularly for ...picoeukaryotes (0.2-3 µm cell size). Here, we examined the picoeukaryotic communities inhabiting different vertical zones of the tropical and subtropical global ocean: surface, deep chlorophyll maximum, mesopelagic (including the deep scattering layer and oxygen minimum zones), and bathypelagic. Communities were analysed by high-tthroughput sequencing of the 18S rRNA gene (V4 region) as represented by DNA (community structure) and RNA (metabolism), followed by delineation of Operational Taxonomic Units (OTUs) at 99% similarity. We found a stratification of the picoeukaryotic communities along the water column, with assemblages corresponding to the sunlit and dark ocean. Specific taxonomic groups either increased (e.g., Chrysophyceae or Bicosoecida) or decreased (e.g., Dinoflagellata or MAST-3) in abundance with depth. We used the rRNA:rDNA ratio of each OTU as a proxy of metabolic activity. The highest relative activity was found in the mesopelagic layer for most taxonomic groups, and the lowest in the bathypelagic. Altogether, we characterize the change in community structure and metabolic activity of picoeukaryotes with depth in the global ocean, suggesting a hotspot of activity in the mesopelagic.
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