Protein diffusion in crowded electrolyte solutions

We report on a combined cold neutron backscattering and spin-echo study of the short-range and long-range nanosecond diffusion of the model globular protein bovine serum albumin (BSA) in aqueous solution as a function of protein concentration and NaCl salt concentration. Complementary small angle X-ray scattering data are used to obtain information on the correlations of the proteins in solution. Particular emphasis is put on the effect of crowding, i.e. conditions under which the proteins cannot be considered as objects independent of each other. We thus address the question at which concentration this crowding starts to influence the static and in particular also the dynamical behaviour. We also briefly discuss qualitatively which charge effects, i.e. effects due to the interplay of charged molecules in an electrolyte solution, may be anticipated. Both the issue of crowding as well as that of charge effects are particularly relevant for proteins and their function under physiological conditions, where the protein volume fraction can be up to approximately 40% and salt ions are ubiquitous. The interpretation of the data is put in the context of existing studies on related systems and of existing theoretical models.     

Wolinella succinogenes fumarate reductase contains a dihaem cytochrome b

The fumarate reductase operon of Wolinella succinogenes is made up of three structural genes (frd-CAB). The frdC gene was located next to the promoter region and identified as the cytochrome b structural gene encoding 256 amino acid residues. The N-terminal amino acid sequences of seven fragments derived from the cytochrome b moiety of the enzyme all mapped within the frdC gene. This suggested that the enzyme contained only one species of cytochrome b. Re-evaluation of earlier measurements of subunit composition, haem B content and molecular weight led to the conclusion that the enzyme contained one molecule of cytochrome b with two haem B groups. The hydropathy plot of the amino acid sequence predicted five membrane-spanning hydrophobic segments, the first four of which contained a single histidine residue each. These residues could form the axial ligands to the two haem B groups. FrdC was found to be homologous with the cytochrome b (SdhC) of the Bacillus subtilis succinate dehydrogenase, but not with the hydrophobic subunits of the fumarate reductase or succinate dehydrogenase of Escherichia coli.     

Die submikroskopische Struktur der Assimilatleitbahnen von Polytrichum commune

Summary In the young part of the stem of Polytrichum commune the protoplasts of the two types of conducting cells, the leptoids and parenchyma cells, are nearly identically equipped with cell organelles and cytoplasmic structures. Both types contain a nucleus, chloroplasts, mitochondria, and dictyosomes. The endoplasmic reticulum builds characteristic cisterns in form of hollow cylinders extending from one end wall to the other. The cisterns are connected with many plasmodesmata, which occur only in the end walls. Leptoids have oblique end walls with 16 to 20 plasmodesmata per m², and parenchyma cells show cross walls perpendicular to the axis with 9 to 12 plasmodesmata per m².Since the leptoids are supposed to be the pathways for the longitudinal transport of assimilates (Eschrich and Steiner, 1967, 1968), it is of interest that early in their development these elements undergo a change in their protoplasmatic structure. Two to 3 cm below the apical cell the protoplasts degenerate and show lysosome-like structures. The endoplasmic reticulum and other structures are deformed or dissolved; the plasmodesmata are constricted by callose deposits. At the same level the parenchyma cells still retain the original structure of their protoplasts.Thus, assimilates moving upward in one row of leptoids may penetrate the whole lumen of the leptoids at lower levels, but they are restricted to the cisterns of the endoplasmic reticulum at higher levels of the stem.     

Distal deletion of the long arm of chromosome number 1 (q43-->qter) associated with severe mental retardation and a nonspecific dysmorphic syndrome.

A 6 8/12-year-old girl with severe mental retardation, multiple congenital malformations and a de novo distal deletion of the long arm of chromosome 1 [del 1 (q43-->qter)] is here described. A review of the reported patients does not allow to distinguish different phenotypes related to distal deletion 1q42 and/or 1q43.     

Molecular analysis of theArabidopsis pattern formation geneGNOM: gene structure and intragenic complementation

TheGNOM gene is required for pattern formation along the main body axis of the embryo in the flowering plantArabidopsis thaliana. Mutations in theGNOM gene alter the asymmetric division of the zygote and interfere with the formation of distinct apical-basal regions in the developing embryo. We have isolated theGNOM gene by positional cloning, characterised its structure and determined the molecular lesions in mutant alleles. Although the predicted 163 kDa GNOM protein has a conserved domain in common with the yeast secretory protein Sec7p, it is most closely related in size and overall similarity to the product of the yeastYEC2 gene, which is not essential for cell viability. Four fully complementinggnom alleles carry missense mutations in conserved regions, seven partially complementing alleles have premature stop codon mutations and two non-complementing alleles have splice-site lesions. Our results suggest that the GNOM protein acts as a complex of identical subunits and that partial complementation may involve low levels of full-length protein generated by inefficient translational read-through.Communicated by H. Saedler     

Ern?hrungsphysiologie des Blaunackenmausvogels (Urocolius macrourus pulcher)

Zusammenfassung Beim Blaunackenmausvogel (Urocolius macrourus pulcher) wurde die Ausnutzung der verschiedenen Nährstoffe (Fette, Eiweiße, Kohlenhydrate) und die Assimilationseffizienz des Gesamtfutters untersucht. Mausvögel sind Vegetarier und hauptsächlich frugivor. Im Versuch erhielten die Vögel vier Diäten: I. Mischfutter (Bananen, Salat, gekochtes Ei, gekochter Reis, Apfel); II. Bananen; III. Fruchtfutter (Pfirsiche und Birnen); IV. Eiweißfutter (Quark und gekochtes Weißei). Die minimalen Darmpassagezeiten betrugen für alle vier Diäten zusammengefaßt zwischen 6 und 18 min. Damit kommen die Mausvögel an die Werte für Nektarfresser heran (unter 15 min). Der Darmtrakt ist mit 19,0 ±2,4 cm (n = 16) für einen Vogel dieser Körpermasse ( 56,4 ±2,7 g; 49,2 ±2,9 g) extrem kurz und zeigt den für Fruchtfresser typischen einfachen Bau. Blinddärme fehlen. Die mittlere Gesamteffizienz für die vier Diäten liegt bei 71,0 %. Die Werte variieren in einem relativ engen Bereich zwischen 65,9 % (Banane) und 74,0 % (Mischfutter). Damit sind Blaunackenmausvögel innerhalb der Vögel als relativ schlechte Nahrungsverwerter zu bezeichnen. Für Fruchtfresser allgemein werden allerdings noch niedrigere Werte zwischen 30 % und 70 % angegeben. Die Assimilationsrate der einzelnen Nährstoffe hängt in starkem Maße vom Angebot im Futter ab. Die Zusammensetzung der assimilierten Nahrung zeigt, daß Kohlenhydrate mit 89,0–91,1 % den weitaus größten Anteil am Energiestoffwechsel haben. Vermutlich werden nur gelöste oder leicht verdauliche Einfachzucker bzw. Stärken verwertet. Zellulose wird praktisch ungenutzt ausgeschieden. Fette und Proteine spielen unter Normalbedingungen nur eine untergeordnete Rolle. Der Energieumsatz ist nahrungsabhängig und beträgt 62,5 J/g·h bei der Bananendiät, 69,2 J/g·h bei der Fruchtdiät, 87,3 J/g·h bei der Eiweißdiät und 99,6 J/g·h beim Mischfutter.

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Nutrient physiology of the Blue-naped Mousebird (Urocolius macrourus pulcher)

Blue-naped Mousebirds were fed with four different diets: I. mixed food (bananas, salad, boiled eggs, boiled rice, apples); II. bananas only; III. soft fruits (pears and peaches); and IV. food enriched with protein (curd cheese and egg-white). The minimal times for food passage through the digestive tract were 6–18 min altogether. This is similar to the data known from nectarivorous birds (<15 min). The intestines are extremely short (19,0 ±2,4 cm; n = 16) and simple-structured, without specialization and without any caeca. The overall efficiency for the diets with 71,0 %, ranging between 65,9 % (bananas) and 74,0 % (mixed food), is relatively low. However, for frugivorous birds in general, far lower efficiencies are recorded (30–70 %). The assimilation efficiencies of nutrients depend on their amount in food and the physiological and seasonal requirements. The composition of the assimilated food shows that carbohydrates, having the largest part with 89,0–91,1 %, are most important for energy supply. Presumably, the birds utilize only sugars being easy to digest, because cellulose is removed. Fat and protein are playing a subordinate role in metabolism. The metabolic turnover differs with the diet and ranges between 62,5 J/g·h (bananas), 69,2 J/g·h (fruits), 87,3 J/g·h (protein food) and 99,6 J/g·h (mixed food).

     

Evolution of 28S Ribosomal DNA in Chaetognaths: Duplicate Genes and Molecular Phylogeny

The chaetognaths are an extraordinarily homogeneous phylum of animals at the morphological level, with a bauplan that can be traced back to the Cambrian. Despite the attention of zoologists for over two centuries, there is little agreement on classification within the phylum. We have used a molecular biological approach to investigate the phylogeny of extant chaetognaths. A rapidly evolving expansion segment toward the 5′ end of 28S ribosomal DNA (rDNA) was amplified using the polymerase chain reaction (PCR), cloned, and sequenced from 26 chaetognath samples representing 18 species. An unusual finding was the presence of two distinct classes of 28S rDNA gene in chaetognaths; our analyses suggest these arose by a gene (or gene cluster) duplication in a common ancestor of extant chaetognaths. The two classes of chaetognath 28S rDNA have been subject to different rates of molecular evolution; we present evidence that both are expressed and functional. In phylogenetic reconstructions, the two classes of 28S rDNA yield trees that root each other; these clearly demonstrate that the Aphragmophora and Phragmophora are natural groups. Within the Aphragmophora, we find good support for the groupings denoted Solidosagitta, Parasagitta, and Pseudosagitta. The relationships between several well-supported groups within the Aphragmophora are uncertain; we suggest this reflects rapid, recent radiation during chaetognath evolution. Received: 19 March 1996 / Accepted: 5 August 1996     

Interstitial deletion (2)(p13p15)

Summary A dysmorphic 5-year-old girl with severe growth and mental deficiency was studied. She presented a de novo interstitial 2p deletion. Karyotype: 46,XX,del(2)(p13p15).     

Madelung deformity as a pathognomonic feature of the onycho-osteodysplasia syndrome.

On the occasion of the observation of the Onycho-osteo-dysplasia syndrome (HOOD syndrome--Nail-Patella syndrome) in a 4-generation family we were impressed by the presence of a Madelung deformity in the four examined family members. A critical review of the literature showed that a true Madelung deformity was present in a great number of previously reported patients but that no specific attention was given to this apparently important symptom.