Proteinvariation und Taxonomie körnerfressender Singvögel

Protein variations and taxonomy of seed-eating oscines The variability of 21 proteins coded by 24 geneloci has been analysed among 99 oscines, 93 of them seed-eaters, out of a total of 40 species. Based on the ascertained allel-frequencies genetic distances were calculated according to ROGERS (1972) and NEI (1972). Dendrograms have been constructed with the “unweighted pair-group arithmetic average clustering-method” (UPGMA) (SOKAL and SNEATH 1963). A new procedure is proposed in order to verify the reliability of these results. Published argumentations on the taxonomy of seed-eating oscines are collected and evaluated all together. With due regard to all results the following conclusions are drawn: 1. Ploceidae and Viduidae are closely related sistergroups. 2. The Estrildidae stand opposite to Ploceidae, Viduidae, Sporopipidae and Passeridae. 3. Together with Motacillidae and Prunellidae the above mentioned groups probably form the Passerioidea. 4. Carduelidae and Fringillidae are sister-groups as well as Emberizidae and Thraupidae. 5. These four families and other not analysed ones form the Fringil-lioidea and stand opposite to the Passerioidea.     

The Spitzenkörper: a molecular perspective

The Spitzenkörper is a dynamic structure present at the tips of hyphal cells with a single highly polarized growth site. It is closely connected with cell morphogenesis and polar growth, and is only present at actively growing sites. Morphogenesis of such highly polarized cells is complex, and requires the coordinated action of multiple protein complexes. We discuss the relevance of these complexes for the structure and function of the Spitzenkörper.     

Functional stratification of the Spitzenkörper of Neurospora crassa

GS‐1 (ncu04189) is a protein required for the synthesis of β‐1,3‐glucan in Neurospora crassa. As chitin, β‐1,3‐glucan is a morphogenetically relevant component of the fungal cell wall. Previously, we showed that chitin synthases are delivered to the growing hyphal tip of N. crassa by secretory microvesicles that follow an unconventional route and accumulate in the core of the Spitzenkörper (Spk). Tagged with the green fluorescent protein (GFP), GS‐1 accumulated in the hyphal apex forming a dynamic and pleomorphic ring‐like structure (‘Spitzenring’) that corresponded to the Spk outer macrovesicular stratum and surrounded the inner core of chitin synthase‐containing microvesicles. TIRF microscopy revealed that GS‐1‐GFP reached the hyphal apex as a population of heterogeneous‐size particles that moved along defined paths. On sucrose density gradients, GS‐1‐associated particles mainly sedimented in a high density range 1.1272–1.2124 g ml^?1. Clearly, GS‐1 and chitin synthases of N. crassa are contained in two different types of secretory vesicles that accumulate in different strata of the Spk, a differentiation presumably related to the spatial control of cell‐wall synthesis.