The rabbit alpha-like globin gene cluster is polymorphic both in the sizes of BamHI fragments and in the numbers of duplicated sets of genes

The alpha-like globin gene cluster in rabbits contains embryonic zeta- globin genes, an adult alpha-globin gene, and theta-globin genes of undetermined function. The basic arrangement of genes, deduced from analysis of cloned DNA fragments, is 5'-zeta 0-zeta 1-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3'. However, the pattern of restriction fragments containing zeta- and theta-globin genes varies among individual rabbits. Analysis of BamHI fragments of genomic DNA from 24 New Zealand white rabbits revealed eight different patterns of fragments containing zeta-globin genes. The large BamHI fragments containing genes zeta 0 and zeta 1 are polymorphic in length, whereas a 1.9-kb fragment containing the zeta 2 gene and the 3.5-kb fragment containing the zeta 3 gene do not vary in size. In contrast to this constancy in the size of the restriction fragments, the copy number of the zeta 2 and zeta 3 genes does vary among different rabbits. No length polymorphism was detected in the BamHI fragments containing the theta-globin genes, but again the copy number varies for restriction fragments containing the theta 2 gene. The alpha 1- and theta 1-globin genes are located in a nonpolymorphic 7.2-kb BamHI fragment. The combined data from hybridization with both zeta and theta probes shows that the BamHI cleavage pattern does not vary within the region 5'-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3', but the pattern genomic blot-hybridization patterns for the progeny of parental rabbits with different zeta-globin gene patterns shows that the polymorphic patterns are inherited in a Mendelian fashion. Two different haplotypes have been mapped based on the genomic blot-hybridization data. The variation in the alpha-like globin gene cluster in the rabbit population results both from differences in the copy number of the duplication block containing the zeta-zeta-theta gene set and from the presence or absence of polymorphic BamHI sites.      

Optimization of Banana Juice Fermentation for the Production of Microbial Oil

Apiotrichum curvatum ATCC 20509 (formerly Candida curvata D), a lipid-accumulating yeast, was grown in banana juice. The optimum conditions for biomass production in shake flasks were 30°C growth temperature, efficient aeration, a juice concentration of 25%, and preliminary heat treatment at less than sterilization conditions. Under controlled conditions in a fermentor, 20% banana juice was optimum. High concentrations of yeast extract (0.3%) increased biomass production by 40% but decreased oil production by 30%. A lower yeast extract concentration (0.05%) increased biomass production by 2% and oil production by 25%. The best growth and oil production were observed when asparagine (1.4 g/liter) and mineral salts were added to the banana juice. The addition of minerals seemed to improve the utilization of carbon. Growth inhibition was observed when the fermentor was aerated with pure oxygen, even when additional nutrients were present. A fed-batch process permitted the juice concentration to be increased from 15 to 82%; biomass accumulation was three times higher than in batch fermentations. However, the cellular lipid content was only 30% of dry weight, and chemical oxygen demand reduction was slow and inefficient.     

Polyelectrolyte precipitation of proteins: II. Models of the particle size distributions

A population-balance model has been used to characterize continuous polyelectrolyte precipitation of egg white proteins. We have modeled the particle size distributions of aggregates formed under a range of mixing conditions. The models, accounting for aggregate growth (by both shear-driven and Brownian-like collisions), breakage (by hydrodynamic shear or aggregate-aggregate collisions), and birth (by the breakage of large aggregates), fit the data well. The kinetic constants show dependencies on shear rate and residence time that have not been previously theoretically predicted; these dependencies are due in part to aging effects on the aggregate. The model constants show a dominance of growth over breakage, supporting qualitative interpretations of the particle size distributions. A mechanism for growth-rate enhancement, caused by polymer extensions from the particle surfaces, produced improved model performance. A collisional breakage mechanism is supported.     

Polyelectrolyte precipitation of proteins: I. The effect of reactor conditions

Lysozyme was recovered from egg white by continuous precipitation with polyacrylic acid (molecular weight of 4 x 10(6)). Precipitator residence time and shear rate had significant effects on the size distribution of the precipitate, but no clear effects on the compositions. Precipitate mean size increased with higher shear, indicating growth phenomena predominating over breakage. Also, an enhancement of growth rate at small sizes was noted. The Camp number successfully characterized the interaction of shear rate and residence time on the particle size.     

Trimethyloxonium modification of single batrachotoxin-activated sodium channels in planar bilayers. Changes in unit conductance and in block by saxitoxin and calcium

Single batrachotoxin-activated sodium channels from rat brain were modified by trimethyloxonium (TMO) after incorporation in planar lipid bilayers. TMO modification eliminated saxitoxin (STX) sensitivity, reduced the single channel conductance by 37%, and reduced calcium block of inward sodium currents. These effects always occurred concomitantly, in an all-or-none fashion. Calcium and STX protected sodium channels from TMO modification with potencies similar to their affinities for block. Calcium inhibited STX binding to rat brain membrane vesicles and relieved toxin block of channels in bilayers, apparently by competing with STX for the toxin binding site. These results suggest that toxins, permeant cations, and blocking cations can interact with a common site on the sodium channel near the extracellular surface. It is likely that permeant cations transiently bind to this superficial site, as the first of several steps in passing inward through the channel.     

Purification and characterization of fatty-acid-binding proteins from rat heart and liver

Fatty-acid-binding proteins were purified from delipidated cytosols of rat heart and liver by gel filtration and anion-exchange chromatography at pH 8.0 and by repeated gel filtration, respectively. Homogeneity of both proteins was demonstrated by a single band on polyacrylamide gels; each had a molecular weight of about 14 000. Liver fatty-acid-binding protein is more basic (pI, 8.1) than that of heart (pI, 7.0) and contains more basic amino acids. Examination of fatty acid binding by the binding proteins from heart and liver revealed the presence of a single class of fatty-acid-binding sites in both cases with an apparent dissociation constant for palmitate of about 1 microM. Liver fatty- acid-binding protein shows similar binding characteristics for palmitate, oleate and arachidonate. Palmitate bound to heart fatty- acid-binding protein was a good substrate for oxidation by rat heart mitochondria. The results show that the fatty-acid-binding proteins from rat heart and liver are closely related, but that they are distinct proteins.     

Incomplete palmitate oxidation in cell-free systems of rat and human muscles

The palmitate oxidation capacity was determined in whole homogenates, postnuclear fractions and mitochondrial fractions of various rat and human muscles and in rat liver, kidney, brain and lung. The oxidation rate (production of 14CO2 and 14C-labeled acid-soluble intermediates) was [1-14C]palmitate greater than [U-14C]palmitate greater than [16-14C]palmitate in all cell-free systems. Oxidation rates were highest in rat heart and liver, intermediate in kidney, diaphragm and m. quadriceps, and low in brain and lung. The capacity of human heart was much lower than that of rat heart and about twice that of human skeletal muscles. Omission of L-carnitine and addition of malonyl-CoA, KCN or antimycin A decreased the oxidation rates in whole homogenates and mitochondrial fractions. Antimycin or KCN increased and malonyl-CoA decreased the ratio of the oxidation rates with [1-14C]- and [16-14C]palmitate. The carnitine concentration had no significant effect on the ratio. 14C-labeled dodecanoic and tetradecanoic acids were identified in homogenates and mitochondrial fractions of m. quadriceps and liver of rat as acid-insoluble intermediates of [16-14C]palmitate oxidation in the presence and absence of antimycin A. Their amounts recovered can account for the differences in oxidation rates found with [1-14C]- and [16-14C]palmitate. The incomplete palmitate oxidation in cell-free systems appears to be mainly caused by an inadequate mitochondrial degradation of peroxisomal oxidation products.     

Der spinnapparat haplogyner spinnen (Arachnida,Araneae)

The spinning apparatus of the Haplogynae was studied in cribellate and ecribellate families of this group. Profound differences were encountered between the species investigated. It is concluded that the group of the Haplogynae is polyphyletic and can not be maintained in a phylogenetic system of the Araneae.

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Sonderdruckanforderungen an: Prof. Dr. Peter Ax II. Zoologisches Institut und Museum der Universität D-3400 Göttingen Berliner Str. 28 Deutschland     

Water reuse in the L-lysine fermentation process

L-Lysine is produced commercially by fermentation. As is typical for fermentation processes, a large amount of liquid waste is generated. To minimize the waste, which is mostly the broth effluent from the cation exchange column used for l-lysine recovery, we investigated a strategy of recycling a large fraction of this broth effluent to the subsequent fermentation. This was done on a labscale process with Corynebacterium glutamicum ATCC 21253 as the l-lysine-producing organism. Broth effluent from a fermentation in a defined medium was able to replace 75% of the water for the subsequent batch; this recycle ratio was maintained for three sequential batches without affecting cell mass and l-lysine production. Broth effluent was recycled at 50% recycle ratio in a fermentation in a complex medium containing beet molasses. The first recycle batch had an 8% lower final l-lysine level, but 8% higher maximum cell mass. In addition to reducing the volume of liquid waste, this recycle strategy has the additional advantage of utilizing the ammonium desorbed from the ion-exchange column as a nitrogen source in the recycle fermentation. The major problem of recycling the effluent from the complex medium was in the cation-exchange operation, where column capacity was 17% lower for the recycle batch. The loss of column capacity probably results from the buildup of cations competing with l-lysine for binding. (c) 1996 John Wiley & Sons, Inc.