Paul Kugrens

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This revision of the classification of unicellular eukaryotes updates that of Levine et al. (1980) for the protozoa and expands it to include other protists. Whereas the previous revision was primarily to incorporate the results of ultrastructural studies, this revision incorporates results from both ultrastructural research since 1980 and molecular(More)
The ultrastructural features, biogenesis and functions of several selected protist extrusive organelles are discussed. Most of the review focuses on some common extrusive organelles that were not considered by Hausmann and several types which have been described since that review of 16 years ago. For convenience, extrusomes are categorized as projectile or(More)
The colorless flagellate Kathablepharis has consisted of five species based on light microscopic studies, and the ultrastructure of the type species, Kathablepharis phoenikoston, is described for the first time. The heterotrophic, marine flagellate Leucocryptos consisted of two species, but additional ultrastructural details for one of these, Kathablepharis(More)
An acid pH in the lumen of chloroplast thylakoids is necessary in order to derive the required amount of CO2 to account for the observed rates of carbon fixation. We point out that the endosymbiotic derivation of the chloroplast from a cyanobacterium would have resulted in the lumen of the thylakoid having an acid pH. The thylakoids of cyanobacteria are(More)
The flagellates and the ciliates have long been considered to be closely related because of their unicellular nature and the similarity in the structures of the axoneme of the flagella and cilia in both groups. Most protozoologists believe that the ciliates arose from a flagellate. The flagellates that are most similar in structure to the ciliates are the(More)
Plants have evolved elegant mechanisms to continuously sense and respond to their environment, suggesting that these properties can be adapted to make inexpensive and widely used biological monitors, or sentinels, for human threats. For a plant to be a sentinel, a reporting system is needed for large areas and widespread monitoring. The reporter or readout(More)
The morphology and ultrastructure of a new freshwater blue-green cryptomonad, Hemiselmis amylosa sp. nov., is described. In addition, a marine blue-green cryptomonad isolate was confirmed as Falcomonas daucoides by electron microscopy and phycobilin analysis so that it could be included in molecular sequence studies, since the original isolate is no longer(More)
A unique type of cytokinesis is described in tetrasporocytes of the alloparasitic red alga,Harveyella sp. Cytokinesis takes place immediately after four post-meiotic nuclei are formed and may result from coalescence of endoplasmic reticulum cisternae. As a result of this cisternal fusion, a double-membraned cleavage channel is formed. This channel lacks(More)
NifS-like proteins provide the sulfur (S) for the formation of iron-sulfur (Fe-S) clusters, an ancient and essential type of cofactor found in all three domains of life. Plants are known to contain two distinct NifS-like proteins, localized in the mitochondria (MtNifS) and the chloroplast (CpNifS). In the chloroplast, five different Fe-S cluster types are(More)