Über die Verbindung der Muskulatur mit dem Skelett bei dem Echinodermen Asterias rubens L.

Zusammenfassung Die Skelettmuskeln des Seesterns Asterias rubens L., der hier als Paradigma der Echinodermen untersucht wurde, inserieren mit Hilfe von Sehnenschlaufen, die außen um die Kalkbälkchen einer dünnen Oberflächenschicht der Sklerite herumgelegt sind. Die Sehnen gehen aus der Basalmembran hervor, welche die Muskelzellfortsätze umhüllt, und bestehen aus parallelisierten zarten Filamenten. Kollagene Fasern, von denen sie sich deutlich unterscheiden, dienen der Muskelinsertion ebensowenig wie die spärliche organische Matrix in der Hartsubstanz.

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On the connection between skeletal muscles and skeleton of the echinoderm asterias rubens L.

Summary The skeletal muscles of the starfish Asterias rubens L. — as a paradigm of the echinodermes — are fixed by means of tendinous loops running around the calcareous beamlets of a thin superficial layer of the ossicles. The tendons emerge from a basement membrane which envelops the terminal processes of the muscle cells. They consist of thin parallel filaments. Collagenic fibers which can be clearly distinguished from these filaments, and the sparce organic matrix of the calcareous parts, do not participate in the muscle insertion.

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Herrn Prof. Dr. phil. Dr. med. A. Kiesselbach zum 60. Geburtstag gewidmet.     

Metal accumulation in two contiguous eutrophic peri-urban lakes,Chivero and Manyame,Zimbabwe

Concentrations of aluminium, cadmium, chromium, cobalt, copper, iron, lead, nickel and zinc were determined in surface water, benthic sediments, and the gills, liver and stomach muscle tissues of Oreochromis niloticus and Clarias gariepinus in peri-urban lakes Chivero and Manyame, Zimbabwe. Five sites were sampled in each lake once per month in November 2015, February, May, August and November 2016. Pollution load index detected no metal contamination, whereas the geo-accumulation index reflected heavy to extreme sediment pollution, with Fe, Cd, Zn, Cr, Ni and Cu present in both lakes. Significant spatial temporal variations were detected for Al, Cr, Cu and Pb across sites within and between the two lakes. High Fe, Al and Cr concentrations in water and sediments in lakes Chivero and Manyame derive from geogenic background sources in addition to anthropogenic loads and intensity. Elevated concentrations of Al, Pb, Cu, Cd, Fe and Zn detected in gills, liver and stomach tissue of catfish corroborate concentrations in water and sediments, and pose the highest ecological and health risk for hydrobionts in lakes Chivero and Manyame. Contiguity of peri-urban lakes exposes them to similar threats, necessitating creative water management strategies, which ensure ecological continuity.     

DNA recognition properties of the N-terminal DNA binding domain within the large subunit of replication factor C.

Replication Factor C (RFC) is a five-subunit protein complex required for eukaryotic DNA replication and repair. The large subunit within this complex contains a C-terminal DNA binding domain which provides specificity for PCNA loading at a primer-template and a second, N-terminal DNA binding domain of unknown function. We isolated the N-terminal DNA binding domain from Drosophila melanogaster and defined the region within this polypeptide required for DNA binding. The DNA determinants most efficiently recognized by both the Drosophila minimal DNA binding domain and the N-terminal half of the human large subunit consist of a double-stranded DNA containing a recessed 5' phosphate. DNA containing a recessed 5' phosphate was preferred 5-fold over hairpined DNA containing a recessed 3' hydroxyl. Combined with existing data, these DNA binding properties suggest a role for the N-terminal DNA binding domain in the recognition of phosphorylated DNA ends.     

A matter of choice: the establishment of sister chromatid cohesion

Sister chromatid cohesion is the basis for the recognition of chromosomal DNA replication products for their bipolar segregation in mitosis. Fundamental to sister chromatid cohesion is the ring‐shaped cohesin complex, which is loaded onto chromosomes long before the initiation of DNA replication and is thought to hold replicated sister chromatids together by topological embrace. What happens to cohesin when the replication fork approaches, and how cohesin recognizes newly synthesized sister chromatids, is poorly understood. The characterization of a number of cohesion establishment factors has begun to provide hints as to the reactions involved. Cohesin is a member of the evolutionarily conserved family of Smc subunit‐based protein complexes that contribute to many aspects of chromosome biology by mediating long‐range DNA interactions. I propose that the establishment of cohesion equates to the selective stabilization of those cohesin‐mediated DNA interactions that link sister chromatids in the wake of replication forks.