On-line prediction of fermentation variables using neural networks

This article presents an introduction to the use of neural network computational algorithms for the dynamic modeling of bioprocesses. The dynamic neural model is used for the prediction of key fermentation variables. This relatively hew method is compared with a more traditional prediction technique to judge its performance for prediction. Illustrative simulation results of a continuous stirred tank fermentor are used for this comparison. It is shown that neural network models are accurate with a certain degree of noise immunity. They offer the distinctive ability over more traditional methods to learn very naturally complex relationships without requiring the knowledge of the model structure.     

The effect of heterogeneous structural diffusion on ligand binding to heme proteins

The kinetics of ligand binding to heme proteins studied by flash photolysis display an algebraic time dependence at low temperatures in contrast exponential recombination observed under physiological conditions. This result shows that protein structures should be viewed as a time average of interconverting microstates which are frozen in at low temperatures. We propose a quasi-one-dimensional model of heterogeneous structural diffusion coupled to ligand binding which describes freezing transition as an inherent property of protein fluctuations. The structural hopping rates are derived from a temperature invariant spectrum of activation energies. The model predicts power law kinetics of the form t ^- at long times. The exponent is constant (0.5) at high temperatures but decreases below a critical temperature in the frozen regime. These results are compared to experiments performed with myoglobin and -chains of hemoglobin.     

Comparative effects of caffeine, its analogues and calcium deficiency on cytokinesis

The effects of caffeine, aminophylline, caffeic acid, and calcium deficiency on cytokinesis were studied by light and electron microscopy. All these treatments blocked cell plate formation, resulting in the formation of binucleate cells. The aggregation and organization of membranous vesicles at the ‘presumptive cell plate’ during these treatments appears similar to that of normal cells, but fusion of the vesicles is insufficient to form a complete cell plate. It is suggested that some aspect of membrane recognition and fusion is the process actually interfered with by these treatments. Greater numbers of binucleate cells and fewer partial cell plates were observed in cells treated with caffeine and aminophylline as compared with those exposed to caffeic acid or calcium deficiency, indicating that the latter treatments do not block cell plate formation as efficiently as the former.     

On the locus of action of Na+ at site I of oxidative phosphorylation

The effect of octylguanidine on the Na⁺ stimulated oxygen uptake of rat liver mitochondria and bovine heart submitochondrial particles and on the Na⁺ induced efflux of K from the mitochondria has been examined. The results indicate that the action of Na⁺ is inhibited by octylguanidine, but that the degree of inhibition depends on the concentration of the cation. Apparently, a competition exists between Na⁺ and octylguanidine for a common site. Octylguanidine, but not oligomycin, at certain concentrations restores in mitochondria incubated with Na⁺ the capacity to respond to uncouplers. A competitive effect between monovalent cations and octylguanidine has been observed in submitochondrial particles oxidizing NADH.     

Photochemistry and dark equilibrium of retinal isomers and bacteriorhodopsin isomers

European Biophysics Journal -     

Intramodal and interaural specificity of the human slow auditory evoked potential

Parameters of slow auditory evoked potentials (SAEPs) recorded during monotonic monaural stimulation and a programmed change in the frequency of successive tonal stimuli were compared. In one variant of polytonic stimulation, besides the frequency, the side of stimulation also was changed (alternation). During polytonic stimulation the amplitude of the SAEPs was greater than during monotonic. Maximal amplitudes were found during alternating polytonic stimulation. A decrease in the variability of amplitude of the SAEPs and an increase in their peak latencies were observed during polytonic stimulation. It is concluded that SAEPs are characterized by intramodal and interaural specificity. The tonotopic and bilaterally symmetrical organizations of the system of SAEP generation can be demonstrated more satisfactorily at low sound intensities. Data indicating that neuron populations of the system of SAEP generation, perceiving tonal stimuli which differ very little from each other "overlap" to a greater degree than populations perceiving more different sounds, are given, The data on intramodal and interaural specificity of the SAEP are discussed from the standpoint of its extralemniscal origin.State Postgraduate Medical Institute, Tbilisi. Translated from Neirofiziologiya, Vol. 9, No. 5, pp. 460–468, September–October, 1977.     

Characterization of a gibberellin sensitive dwarf mutant of barley (Hordeum vulgare L.,Mut. Dornburg 576)

The radiation (³²P) induced dwarf mutant of spring barley,Hordeum vulgare L., Mut. Dornburg 576, was genetically studied by crosses with the mother variety and characterized by seedling assays and investigations on development and yield formation. In comparison to the normal mother variety (Hordeum vulgare L., cv. Saale) mutant plants exhibit drastically reduced culm length, intensive tillering, a prolonged life cycle and a smaller biomass and grain yield formation. These characters are controlled by one gene in a pleiotropic way. The mutant responds with normal growth and development to the application of gibberellins.     

Formation of exopolysaccharides by Rhodococcus erythropolis and partial characterization of a heteropolysaccharide of high molecular weight

Summary Polysaccharide formation by Rhodococcus erythropolis was studied using lower mono-, di-and trihydric alcohols, sugars and n-alkanes as carbon sources. Cultural conditions of the organism were examined with regard to polysaccharide production. It was demonstrated that a glycerol substrate, an 30°C incubation temperature and a pH of 7.5 were optimal cultural conditions for polysaccharide formation. Addition of penicillin G in the decelerating growth phase increased the polysaccharide concentration in the culture filtrate to 3.1 g/l. One of the main extracellular heteropolysaccharides formed by Rhodococcus erythropolis consisted of glucose and mannose in the molar ratio 11, a small portion of protein and a trace of glucosamine. The molecular weight was to be 1·14×10⁶.