Scanning electron microscope studies of the surface of the sea urchin egg

Summary The surface of the egg of the two sea urchin species,Strongylocentrotus droebachiensis andS. pallidus, was studied with SEM. Clear differences were observed between the two species, in both the number and form of the microvilli. The changes in the egg surface which follow insemination are described.     

Metabolic gradients as key regulators in zonation of tumor energy metabolism: A tissue-scale model-based study

Characteristics of many tumor types are the reprogramming of metabolism and the occurrence of regional hypoxia. In this work, we investigated the hypothesis that metabolic reprogramming in combination with metabolic zonation of cellular energy metabolism are important factors in promotion of the growth capacity of solid tumors. A tissue-scale model of the two main ATP delivering pathways, glycolysis (GLY) and oxidative phosphorylation (OXP), was used to simulate the energy metabolism within solid tumors under various metabolic strategies. Remarkably, despite the high diversity in the usage of glucose, lactate and oxygen in various spatial regions, the tumor as a whole clearly displays the hallmark of the so-called Warburg effect, i.e. a high rate of glucose consumption and lactate production in the presence of sufficiently high levels of oxygen. Our simulations suggest that an increase in GLY capacity and concomitant decrease in OXP capacity from the periphery towards the center of the tumor improves the availability of oxygen to pericentral tumor cells. The found relationship between the regional oxygen level and the relative share of GLY and OXP capacities supports the view that metabolite availability functions as key regulator of tumor energy metabolism.     

Uromyces vankyorum sp. nov. and Uromyces atriplicis, putative vicariant rust species of Patagonian and Australian semi-desert biomes

Uromyces vankyorum (Basidiomycota, Uredinales) growing on Atriplex lampa in the cool Patagonian dwarf shrub semi-desert is described as a new species and a new member of the Argentinean rust mycota. The fungus is morphologically similar to Uromyces atriplicis on Atriplex vesicaria from halophytic shrublands of South Australia. U. atriplicis seems to be derived from U. vankyorum as indicated by its shortened life cycle lacking the urediniospore stage. The species are interpreted as trans-pacific vicariants and represent one of the rare examples for the austral South American-Australasian element among rust fungi. The disjunct distribution of rust fungi between austral South America, Australia and New Zealand is reviewed and discussed. Available data suggest migration of rust fungi along Gondwanan land bridges rather than long-distance dispersal of spores by air currents. Part 198 of the series “Studies in Heterobasidiomycetous Fungi” of the Botanical Institute, University of Tübingen     

Synthesis of the human proinsulin sequence 71-86, I: Synthesis of sequence 71-86 as a monomeric cyclic biscystine peptide derivative and as its tetra-S-trityl derivative (author's transl)]

The synthesis of sequence 71-86 of human proinsulin (sequence 6-21 of human insulin A-chain) via its monomeric cyclic dicystine peptide derivative (XXII) and the corresponding tetra-S-trityl-peptide derivative (XVIII) is described. The good solubility of the derivatives (XXII, XVIII) in orgranic solvents makes it possible to purify both the derivatives in their protected form. The S-trityl derivative (XVIII) enables the synthesis of the fragment 71-86 in a scale needed for the planned synthesis of human proinsulin.     

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