Entobia exogyrarum (Frič, 1883) from the Upper Cretaceous of the Bohemian Cretaceous Basin

The validity of the little-known ichnospecies Entobia exogyrarum (Fri?) is verified. Shells of an oyster, Rhynchostreon suborbiculatum (Lam.), represent the substrate for the sponge borings. The borings occur in many Upper Cenomanian to Middle Turonian localities of the Bohemian Cretaceous Basin. This study revealed that the sponges attacked shells of living oysters. Entobia exogyrarum (Fri?) also represents one of the shallowest occurrences of Entobia borings in the Upper Cretaceous rocks.     

Combination of ellipsometry, laser scanning microscopy and Z-scan fluorescence correlation spectroscopy elucidating interaction of cryptdin-4 with supported phospholipid bilayers.

The present study has two main objectives. The first is to characterize antimicrobial peptide (AMP) cryptdin-4 (Crp-4) interactions with biological membranes and to compare those interactions with those of magainin 2. The second is to combine the complementary experimental approaches of laser scanning microscopy (LSM), ellipsometry, and Z-scan fluorescence correlation spectroscopy (FCS) to acquire comprehensive information on mechanisms of AMP interactions with supported phospholipid bilayers (SPBs)-a popular model of biological membranes. LSM shows appearance of inhomogeneities in spatial distribution of lipids in the bilayer after treatment with Crp-4. Ellipsometric measurements show that binding of Crp-4 does not significantly change the lipid structure of the bilayer (increase in adsorbed mass without a change in thickness of adsorbed layer). Furthermore, Crp-4 slows the lateral diffusion of lipids within the membrane as shown by Z-scan FCS. All changes of the bilayer induced by Crp-4 can be partially reversed by flushing the sample with excess of buffer. Bilayer interactions of magainin 2 are significantly different, causing large loss of lipids and extensive damage to the bilayer. It seems likely that differences in peptide mode of action, readily distinguished using these combined experimental methods, are related to the distinctive beta-sheet and alpha-helical structures of the respective peptides.     

Isolation and characterization of CAC antenna proteins and photosystem I supercomplex from the cryptophytic alga Rhodomonas salina

In the present paper, we report an improved method combining sucrose density gradient with ion‐exchange chromatography for the isolation of pure chlorophyll a/c antenna proteins from the model cryptophytic alga Rhodomonas salina. Antennas were used for in vitro quenching experiments in the absence of xanthophylls, showing that protein aggregation is a plausible mechanism behind non‐photochemical quenching in R. salina. From sucrose gradient, it was also possible to purify a functional photosystem I supercomplex, which was in turn characterized by steady‐state and time‐resolved fluorescence spectroscopy. R. salina photosystem I showed a remarkably fast photochemical trapping rate, similar to what recently reported for other red clade algae such as Chromera velia and Phaeodactylum tricornutum. The method reported therefore may also be suitable for other still partially unexplored algae, such as cryptophytes.     

Ilja Pek (1945–1998)

The Fossil Record of Predation, edited by Michal Kowalewski and Patricia H. Kelley, 2002, The Paleontological Society Papers, Volume 8, 398 p., US$20.00, ISSN 1089-3326. Reviewed by Paul D. Taylor, Department of Palaeontology, The Natural History Museum, London SW7 5BD, United Kingdom