Leibniz Association

About: Leibniz Association is a government organization based out in Berlin, Germany. It is known for research contribution in the topics: Population & Gene. The organization has 16586 authors who have published 35691 publications receiving 1095107 citations. The organization is also known as: Leibniz-Gemeinschaft & Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz.

Effects of cyanobacterial toxins and aqueous crude extracts of cyanobacteria on the development of fish and amphibians

Abstract: The effects of cyanobacterial hepatotoxins microcystin-LR, -RR, and -YR, of the neurotoxins saxitoxin and anatoxin-a, and of crude aqueous extracts of cyanobacteria were determined on the embryos of fish and amphibians from cleavage up to advanced stages of embryonic development. No acute toxic effects were observed after exposure to microcystins at 0.5, 5, and 50 μg/L, but the timing of hatching was altered in rainbow trout: earlier hatching occurred with 0.5, 5, and 50 μg/L microcystin-RR, 5 and 50 μg/L microcystin-YR, and 50 μg/L microcystin-LR; a minor delay in hatching was observed at 0.5 and 5 μg/L microcystin-LR. In axolotl, a delay in feeding was observed (microcystin-LR at 5 and 50 μg/L; microcystin-YR at 50 μg/L). After termination of exposure and rearing in toxin-free tanks, survival rate and growth were adversely affected in zebrafish larvae preexposed to microcystin-LR at 5 and 50 μg/L. At the highest applied concentration of microcystin-LR (10 mg/L), morphological effects were detected. Saxitoxin at 10 μg/L and above delayed hatching in zebrafish and led to malformations and mortalities at 500 μg/L. Hatching was also delayed in axolotl at 500 μg/L saxitoxin. Anatoxin-a (400 μg/L) altered the heart rate in zebrafish, but no chronic effects were observed. Far more pronounced effects, compared to those obtained with pure toxins, were observed following exposure to various aqueous crude extracts of cyanobacteria from field samples and batch cultures: similar malformations combined with high mortalities and adverse effects on outer egg structures were observed concomitantly in all species. HPLC data showed that these effects cannot be attributed to microcystin content alone. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 77–88, 1999

What's in a name? Why these proteins are intrinsically disordered: Why these proteins are intrinsically disordered.

Abstract: "What's in a name? That which we call a rose By any other name would smell as sweet." From "Romeo and Juliet", William Shakespeare (1594) This article opens a series of publications on disambiguation of the basic terms used in the field of intrinsically disordered proteins. We start from the beginning, namely from the explanation of what the expression "intrinsically disordered protein" actually means and why this particular term has been chosen as the common denominator for this class of proteins characterized by broad structural, dynamic and functional characteristics.

Molecular-scale evidence of aerosol particle formation via sequential addition of HIO3.

Abstract: Homogeneous nucleation and subsequent cluster growth leads to the formation of new aerosol particles in the atmosphere. The nucleation of sulfuric acid and organic vapours is thought to be responsible for the formation of new particles over continents, whereas iodine oxide vapours have been implicated in particle formation over coastal regions. The molecular clustering pathways that are involved in atmospheric particle formation have been elucidated in controlled laboratory studies of chemically simple systems, but direct molecular-level observations of nucleation in atmospheric field conditions that involve sulfuric acid, organic or iodine oxide vapours have yet to be reported. Here we present field data from Mace Head, Ireland, and supporting data from northern Greenland and Queen Maud Land, Antarctica, that enable us to identify the molecular steps involved in new particle formation in an iodine-rich, coastal atmospheric environment. We find that the formation and initial growth process is almost exclusively driven by iodine oxoacids and iodine oxide vapours, with average oxygen-to-iodine ratios of 2.4 found in the clusters. On the basis of this high ratio, together with the high concentrations of iodic acid (HIO3) observed, we suggest that cluster formation primarily proceeds by sequential addition of HIO3, followed by intracluster restructuring to I2O5 and recycling of water either in the atmosphere or on dehydration. Our study provides ambient atmospheric molecular-level observations of nucleation, supporting the previously suggested role of iodine-containing species in the formation of new aerosol particles, and identifies the key nucleating compound.