University of Hohenheim

About: University of Hohenheim is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Population & Soil water. The organization has 8585 authors who have published 16406 publications receiving 567377 citations.

Lipofuscin: formation, distribution, and metabolic consequences

Abstract: One of the highlights of postmitotic aging is the intracellular accumulation of highly oxidized and cross-linked proteins, known as lipofuscin Lipofuscin is insoluble and not degradable by lysosomal enzymes or the proteasomal system, which is responsible for the recognition and degradation of misfolded and oxidatively damaged proteins These aggregates have been found in various cell types, including heart, liver, kidney, neuronal tissue, and dermal tissue, and are associated with the life span of a single postmitotic cell and, consequently, of the whole organism Lipofuscin formation appears to depend on the rate of oxidative damage to proteins, the functionality of mitochondrial repair systems, the proteasomal system, and the functionality and effectiveness of the lysosomes This review highlights the current knowledge of the formation, distribution, and effects of lipofuscin in mammalian cells

Ground-based facilities for simulation of microgravity: organism-specific recommendations for their use, and recommended terminology.

Abstract: Research in microgravity is indispensable to disclose the impact of gravity on biological processes and organisms. However, research in the near-Earth orbit is severely constrained by the limited number of flight opportunities. Ground-based simulators of microgravity are valuable tools for preparing spaceflight experiments, but they also facilitate stand-alone studies and thus provide additional and cost-efficient platforms for gravitational research. The various microgravity simulators that are frequently used by gravitational biologists are based on different physical principles. This comparative study gives an overview of the most frequently used microgravity simulators and demonstrates their individual capacities and limitations. The range of applicability of the various ground-based microgravity simulators for biological specimens was carefully evaluated by using organisms that have been studied extensively under the conditions of real microgravity in space. In addition, current heterogeneous terminology is discussed critically, and recommendations are given for appropriate selection of adequate simulators and consistent use of nomenclature.

Varroacides and their residues in bee products

Abstract: dus dans les produits du rucher. Les traitements contre l'acarien Varroa jacobsoni pesent actuellement sur la qualite des produits du rucher dans de nombreux pays. La discussion sur le caractere dangereux des residus porte atteinte a l'image positive qu'a le public de ces produits. Les desaccords entre pays concernant la reglementation des produits de traitement autorises et les limites maximales admissibles (tableau III) ne contribuent pas a depassionner le debat. La nature chimique du varroacide et la quantite de substance appliquee peuvent enormement varier (tableaux I et II). Les substances hydrosolubles (acides formique, lactique, oxalique) sont dangereuses pour la qualite du miel, puisqu'elles peuvent etre diluees dans le miel. La cire accumule et stabilise les substances liposolubles qui peuvent ensuite migrer des rayons de cire dans le miel entrepose ou le polluer sous forme de particules de cire. A quelques rares exceptions les varroacides lipophiles utilises ont pu etre retrouves dans le miel egalement (limite de detection < 10 ppb). Des donnees existent actuellement pour les matieres actives (m.a.) suivantes: bromopropylate, coumaphos, fluvalinate, malathion, diazinon, chlordimeform et cymiazole. A l'heure actuelle des residus de trois m.a. non volatiles et liposolubles sont principalement presents daans les miels allemands. Dans pres de 11 % des miels allemands on trouve des residus de bromopropylate (Folbex VA Neu) dans les limites de 2-10 ppb; ils provenaient tous sans exception de la m.a. qui s'etait fixee dans les rayons a la suite de traitements effectues les annees passees. Le coumaphos (Perizin) fournit les residus les plus souvent detectes dans le miel. Environ 28 % de tous les miels allemands en contenaient des residus, de l'ordre de 2-15 ppb. On trouve des valeurs semblables dans les miels etrangers. En comparaison le fluvalinate (Klartan, Mavrik, Apistan) apparait rarement dans le miel. Environ 1 % des miels allemands presentent des residus de fluvalinate et ce dans des limites plus basses (2-7 ppb). Des quantites de m.a. allant jusqu'a 40 ppb ont ete retrouvees dans des echantillons provenant d'Europe de l'Est. Les residus d'amitraz sont instables dans le miel. L'amitraz se decompose presque totalement en trois a quatre semaines en produits de degradation. Dans la cire non plus la m.a. presente a l'origine n'est pas stable (figure 1). Dans aucun autre pays a l'exception des Etats-Unis (fluvalinate: 6 ppm), il n'existe de limites superieures fixees pour les residus de varroacides dans la cire. Si l'on compare la situation de l'apiculture en 1997 en Allemagne et dans les pays etrangers, il est evident que l'on trouve des pourcentages plus eleves de bromopropylate (54,9 %) et de coumaphos (61,0 %) dans les miels allemands. La majorite des echantillons renferme des quantites de m.a. comprises entre 1 et 5 ppm. En revanche plus de la moitie des echantillons etrangers (55,0 %) sont pollues par le fluvalinate. La tendance a retrouver cette m.a. dans les miells allemands augmente: en 1996, 23,6 % des echantillons etaient positifs contre seulement 13,2 % en 1995 (tableau IV). Le commerce international de la cire fait apparaitre d'autres m.a. inconnnues en Allemagne comme varroacides (par exemple, le tetradifon).

Sucrose, sucrosyl oligosaccharides, and oxidative stress: scavenging and salvaging?

Abstract: In nature, no single plant completes its life cycle without encountering environmental stress. When plant cells surpass stress threshold stimuli, chemically reactive oxygen species (ROS) are generated that can cause oxidative damage or act as signals. Plants have developed numerous ROS-scavenging systems to minimize the cytotoxic effects of ROS. The role of sucrosyl oligosaccharides (SOS), including fructans and the raffinose family oligosaccharides (RFOs), is well established during stress physiology. They are believed to act as important membrane protectors in planta. So far a putative role for sucrose and SOS during oxidative stress has largely been neglected, as has the contribution of the vacuolar compartment. Recent studies suggest a link between SOS and oxidative defence and/or scavenging. SOS might be involved in stabilizing membrane-associated peroxidases and NADPH oxidases, and SOS-derived radicals might fulfil an intermediate role in oxido-reduction reactions taking place in the vicinity of membranes. Here, these emerging features are discussed and perspectives for future research are provided.