Redox chemistry of complexes of nickel(II) with some biologically important peptides in the presence of reduced oxygen species: an ESR study.

The reactions between some Ni(II) oligopeptides (Gly-His-Lys, (Gly)4, Asp-Ala-His-Lys, Gly-Gly-His, beta Ala-His, and serum albumin) and reduced oxygen species have been characterized by spin-trapping experiments using DMPO and Me2SO. Most of the peptides possessed superoxide dismutase- and catalase-like activities leading to the formation of either oxene [NiO]2+ or, in the case of beta Ala-His, hydroxyl radicals. Both these species may affect DNA integrity through distinct mechanisms.     

Immunocytochemical localization of rabbit gastric lipase and pepsinogen

Lipase and pepsin activities were determined in rabbit gastric biopsy specimens. Lipase activity was found to be restricted to a small part of the fundic mucosa, near the cardia, whereas pepsin activity spread over about two thirds of the total fundic area, overlapping that of lipase. The cells producing these two enzymes were labeled by immunofluorescence using polyclonal antibodies against rabbit gastric lipase (RGL) or antibodies against rabbit pepsinogen. The immunocytochemical localization showed unequivocally that RGL and pepsinogen, which were both present in the cardial area, were in fact located in different gastric cells. The cells producing pepsinogen were in the lower base of the gastric fundic glands, whereas the cells producing RGL were in the upper base of the same glands. The cells producing pepsinogen and RGL showed no significant morphological differences. In the part of the fundic area, where only pepsin activity was detected, cells producing pepsinogen covered both the lower and the upper base of the gastric glands. No chief cells were observed in the antral mucosa. RGL and pepsinogen could represent useful gastric enzyme markers for cellular differentiation studies.     

The way from medical to physiological chemistry at the University of G?ttingen, 1840-1940

In the nineteenth century chemistry was separated from medicine and reorganized as a "pure" academic science. Those left-over parts of chemistry that were more oriented towards medical application formed the nucleus of modern physiological chemistry, but could usually only exist in connection with other subjects. Especially the combination with physiology proved to be stable. Discipline building was delayed by the fact that a lot of physiologists resented a separation from physiology. Also in G?ttingen physiological chemistry was attributed to the Physiological Institute, but initially still had close connections with the General chemical Laboratory. At the end of the nineteenth century a first attempt to establish itself as a discipline together with hygiene failed. Physiological chemistry stayed a part of physiology until 1939 when the Institute of Physiological Chemistry was finally founded. The G?ttingen way is characteristic for the general establishment of the discipline in Germany.     

Notechis 11'2, a non-toxic phospholipase A2 from the venom of Notechis scutatus scutatus.

Previously, we deduced the amino acid sequence of a novel phospholipase-A2-like protein (PLA2) from the nucleotide sequence of a cDNA isolated from a library prepared from the venom gland of the Australian elapid Notechis scutatus scutatus. The corresponding protein has now been identified, purified from the venom and named Notechis 11'2. Its complete amino acid sequence has been determined by automated Edman degradation of both the whole protein and peptides generated by Staphylococcus aureus protease digestion and chemical cleavage at a tryptophan residue. As predicted from its sequence which contains all the residues putatively required for PLA2 activity, Notechis 11'2 exhibits an esterase activity, preferentially against neutral phospholipids. However, despite its sequence homology with other highly toxic PLA2 present in the venom of Notechis scutatus scutatus, notechis 11'2 has no lethal activity. This observation further supports the view that the lethal activity of PLA2 from Notechis scutatus scutatus is not due to the esterasic activity only.     

Prokaryotes: an overview with respect to biodiversity and environmental importance

A short overview of the biodiversity of prokaryotes (the domains bacteria and archaea) is given, with respect to morpholoy, physiology, and biochemistry. The importance of prokaryotes in food chains, nutrient and biogeochemical cycles, and for the maintenance of a balanced atmosphere is explained and stressed. The involvement of prokaryotes in symbiotic mutualisms and in pathogenicity is discussed.     

Isolation and characterization of the polyphenoloxidase from senescent leaves of black poplar

The polyphenoloxidase (PPO) from black poplar senescent leaves has been purified to almost complete homogeneity by a combination of ammonium sulphate precipitation, Sephadex G75 filtration and DEAE-cellulose chromatography. The purified enzyme has a MW of 60 000 and is probably a Cu⁺ enzyme. Peroxidase (PO) activity co-purifies with PPO and has the same MW as it. The two enzymes differ in pH optimum and in response to the effect of ionic strength. Natural phenols are either substrates, inhibitors or activators of black poplar PPO. This enzyme is an o-diphenoloxidase which binds substrates with K_m in the millimolar range. With caffeic and chlorogenic acids inhibition by excess substrate is observed. Benzoic acid phenols and cinnamic acid phenols are either competitive or non-competitive inhibitors of PPO. Hydroquinone is a highly potent non-competitive inhibitor of the enzyme (K_i  90 μM). Ferulic acid is a potent activator of the PPO-catalysed oxidation of catechol (K_a  0.34 mM, ν_sat/ν_o  7.7).     

Paleoecology of the Miocene fossil mammal fauna from Bełchatów (Poland)

Miocene fauna of land mammals is known from numerous fossil localities in western Europe but its remains are rare in the north-eastern part of this continent. The open brown coal mine at Bełchatów in central Poland revealed numerous remains of small and large mammals representing three Miocene biozones from MN4 to MN8/9. They indicate the presence of relatively stable subtropical conditions during all the time of the Miocene deposition in the Bełchatów basin with only slight cooling before the end of the sedimentation.

     

Impact of river management history on the community structure,species composition and nutrient status in the Rhine alluvial hardwood forest

The present-day Rhine alluvial hardwood forest (Querco-Ulmetum minoris, Issler 24) in the upper Rhine valley (France/Germany) is comprised of three vegetation units, one still flooded by calm waters (F) and the two others unflooded, one for 30 years (UF30) (after the river canalisation) and the other for about 130 years (UF130) (after river straightening and embankment work in the middle nineteenth century). In the three stands, species composition, structure and diversity of vegetation and nutrient content of mature leaf, leaf litter and soil have been studied. Fungi (Macromycetae) were only studied in two stands (F and UF130). The intensity of nutrient recycling was exemplified by comparing the chemical composition of rainwater, flood, throughfall, mature leaf, leaf litter, soil and groundwater in two of these stands (F and UF30).The elimination of floods has caused a change in floristic composition, tree density and plant diversity. Tree density was higher in the two unflooded stands and was related to a large increase in sapling (< 6 cm dbh) density more than to a change of stem (> 6 cm dbh) density. Sapling density increased 2 times and three times in the UF30 and the UF130 respectively, whereas the stem density increased only 12% in the first stand and decreased 29% in the second one. The saprophytic macromycete communities have been supplemented with mycorrhizal species. Leaf litter production was slightly greater in the flooded (4.44 T ha^-1 yr^-1) than in the two unflooded stands ( 3.72 T ha^-1 yr^-1). Foliar N level is twice as high in the flooded stands in spite of an opposite soil status. P level decreased in soil and leaves with the duration of isolation and was at the same level in the groundwater in two stands (F and UF30). K, Mg and Ca contents of green leaf and leaf litter were high due to the geochemistry of the Rhine substrate (calcareous gravels and pebbles) and similar in all the stands studied, even though there are large inputs of these three elements by floods. Moreover we showed that the groundwater chemistry reflected the variations of nutrient inputs and thus could be a good indicator of the functioning of an alluvial ecosystem and of its change as a result of human activities. The restoration of floods in hardwood forest contributes to the preservation of alluvial vegetational structure and composition, the stimulation of biological processes and a better plant mineral nutrition and water supply.