Spatial variation in vegetation and abiotic factors related to the occurrence of a ring‐forming sedge

Abstract. The clonal sedge Carex humilis forms rings of densely aggregated ramets in a dry grassland community in Central Europe. We describe the small‐scale spatial variation, both in abiotic factors and vegetation, in relation to these rings. Compared to the surrounding vegetation the cover of plants, other than C. humilis, was significantly lower both in the central area of rings and within the rings themselves. The vegetation structure was also different. The soil was more fertile in the central area and within the ring than in the surroundings, measured both directly and by the abiotic response values of the vascular plants. We conclude that neither resource depletion nor competition from other plants were likely to be responsible for the low ramet density in the central area of C. humilis rings. Instead, we suggest that the ring form is caused either by the deposition of growth inhibiting substances or by intrinsic morphological rules.     

Vegetation on anthropogenic metalliferous soils in the Eastern Alps

A syntaxonomic revision of vegetation of anthropogenic metalliferous habitats (mine spoils of lead, zinc and copper mining) in the Eastern Alps (Austria, Germany, Italy and Slovenia) was made. The communities studied belong to theThlaspietea rotundifolii (Linaria alpina-Cerastium uniflorum comm.,Papaveri kerneri-Thlaspietum kerneri, Violetum dubyanae, Thlaspietum cepaeifolii, Thlaspietum rotundifolii, Scrophulario juratensis-Erysimetum sylvestris, Minuartia gerardii-Silene glareosa comm.,Epipactido atrorubentis-Silenetum glareosae andSileno alpestris-Moehringietum muscosae) and to theAsplenietea trichomanis (Sileno rupestris-Asplenietum). There is neither floristic support nor syntaxonomic justification for the concepts of theGalio anisophylli-Minuartion vernae, theVioletalia calaminariae and theVioletea calaminariae in the Eastern Alps. These units should be included within theThlaspion rotundifolii, Thlaspietalia rotundifolii andThlaspietea rotundifolii, respectively.     

The high-rank syntaxa of the rock-cliff and scree vegetation of the mainland Greece and Crete

A revision was undertaken of the high-rank syntaxa of the vegetation occurring in rock fissures, ledges and screes of mainland Greece and Crete. All published phytosociological relevés available were collected and subjected to numerical classification and ordination. Four orders (Androsacetalia vandelii, Onosmetalia frutescentis, Potentilletalia speciosae andPetromaruletalia pinnatae) comprising 8 alliances (one of them new) were distinguished within theAsplenietea trichomanis (rock fissures, clefts, and ledges). The scree vegetation was classified partly within theThlaspietea rotundifolii (Drypidetalia spinosae with 2 alliances) and partly within theDaphno-Festucetea (Saturejo-Scutellarietalia—a new order, with 2 alliances). Ordination revealed clear differences in floristic composition of the alliances distinguished. The studied chasmophytic vegetation of Greece contains a very high proportion of endemics which serve as diagnostic species of the syntaxa. Further, an analysis of chorological species spectra suggested that the chorological homogeneity of a syntaxon should be considered an important diagnostic feature at high-syntaxon levels.     

Structure-approximating inverse protein folding problem in the 2D HP model.

The inverse protein folding problem is that of designing an amino acid sequence which has a particular native protein fold. This problem arises in drug design where a particular structure is necessary to ensure proper protein-protein interactions. In this paper, we show that in the 2D HP model of Dill it is possible to solve this problem for a broad class of structures. These structures can be used to closely approximate any given structure. One of the most important properties of a good protein (in drug design) is its stability--the aptitude not to fold simultaneously into other structures. We show that for a number of basic structures, our sequences have a unique fold.     

Different binding sites for glucose and sorbose at the erythrocyte membrane,studied by gel filtration and infrared spectroscopy

Summary Human red blood cell membranes were solubilized with sodium dodecylsulfate and incubated with various concentrations of¹⁴C-glucose and¹⁴C-sorbose. After gel filtration on Sephadex G-100, which separated lipoproteins of differing lipid content, it was observed that the radioactivity of the bound glucose coincided with the protein peak. Radioactivity of bound sorbose was found mainly before and after the protein peak. This distribution of bound sugars was confirmed by double labeling experiments in which³H-glucose and¹⁴C-sorbose were applied simultaneously. Infrared spectroscopy revealed differences between the membranes loaded with sorbose and glucose. Particularly, the band in the C–O–C and P=O region at 1,225 cm^–1 was intensified in the sorbose-loaded membranes. Compared to serum albumin, the erythrocyte membranes were found to bind 4 times as much¹⁴C-glucose per mg of protein. It is concluded from the results obtained by gel filtration that glucose and sorbose preferentially bind at different sites of the erythrocyte membrane. The results obtained by infrared spectroscopy correspond with this conclusion.     

Reversible binding interactions between the tryptophan enantiomers and albumins of different animal species as determined by novel high performance liquid chromatographic methods: an attempt to localize the D- and L-tryptophan binding sites on the human serum albumin polypeptide chain by using protein fragments

The stereoselectivity of the reversible binding interactions between the D- and L-tryptophan enantiomers and serum albumins of different animal species and fragments of human serum albumin (HSA) was investigated by applying three novel high performance liquid chromatographic (HPLC) arrangements. The separations were performed by means of (1) an achiral (diol-bond), (2) a chiral (bovine serum albumin-bond) silica gel sorbent, and (3) a column switching technique which uses both the diol- and HSA-bond HPLC stationary phases. A polarimetric detector and/or an ultraviolet (UV) spectrophotometer were used to monitor the separation process. HPLC arrangement 3 allowed the evaluation of enantioselective binding for D- and L-tryptophan to different albumins and albumin fragments. At present, column switching can be considered the technique of the broadest applicability for investigating the reversible binding interactions between a protein and drug enantiomers. Chirality 9:373–379, 1997. © 1997 Wiley-Liss, Inc.