Application of solvent extraction to ethanol fermentation

Summary The basic problems of applying solvent extraction to ethanol fermentation were investigated. The selection of solvents was based on the selectivity ratio, which was expressed as the ratio of the ethanol distribution coefficient to the water distribution coefficient. Solvents with high selectivity ratios of more than 50 were found mainly among the alcohols and esters. However, most of these solvents were toxic to ethanol-producing microorganisms. We tried to make a barrier to solvent molecules beneath the surface of gel beads immobilizing the cells as a protection against solvent toxicity. Porapack Q was found to be an effective barrier, and the ethanol production rate of immobilized cells protected with Porapack Q did not change event after the production of eight batches in medium saturated with sec-octanol, which was the most toxic solvent used in our experiments.     

Persistence of Common Alleles in Two Related Populations or Species

Mathematical studies are conducted on three problems that arise in molecular population genetics. (1) The time required for a particular allele to become extinct in a population under the effects of mutation, selection, and random genetic drift is studied. In the absence of selection, the mean extinction time of an allele with an initial frequency close to 1 is of the order of the reciprocal of the mutation rate when 4Nv << 1, where N is the effective population size and v is the mutation rate per generation. Advantageous mutations reduce the extinction time considerably, whereas deleterious mutations increase it tremendously even if the effect on fitness is very slight. (2) Mathematical formulae are derived for the distribution and the moments of extinction time of a particular allele from one or both of two related populations or species under the assumption of no selection. When 4Nv << 1, the mean extinction time is about half that for a single population, if the two populations are descended from a common original stock. (3) The expected number as well as the proportion of common neutral alleles shared by two related species at the tth generation after their separation are studied. It is shown that if 4Nv is small, the two species are expected to share a high proportion of common alleles even 4N generations after separation. In addition to the above mathematical studies, the implications of our results for the common alleles at protein loci in related Drosophila species and for the degeneration of unused characters in cave animals are discussed.     

An X-ray study on the interaction between indole ring and pyridine coenzymes: Crystal structure of 1-methyl-3-carbamoylpyridinium: Indole-3-acetic acid (1:1) monohydrate charge-transfer complex

The crystal and molecular structures of the title complex has been determined by X-ray diffraction methods, as a model for tryptophan residues in protein-pyridine coenzyme interactions. The structure was solved by direct methods and was refined by standard methods (final R = 0.073). The light-green crystals consist of alternate layers of indole-3-acetic acid and 1-methyl-3-carbamoylpyridinium molecules piled up to the c-direction, and are stabilized by the crystal water participating in hydrogen bonds in the a- and b-directions. The parallel stackings and interplanar spacing distances between indole and pyridinium rings strongly suggest a II–II¹ charge transfer from the indole ring to the lowest unoccupied orbital of the pyridinium ring in the ground state. Furthermore, this crystal structure provides evidence that quaternization of the N1 position enhances electron-acceptor properties of pyridine. On the other hand, the proton magnetic resonance spectra suggest that the stacking mode between both rings in solution is very similar to the one observed in the crystal structure.     

Mean and variance of FST in a finite number of incompletely isolated populations

In the presence of migration F_ST in a finite number of incompletely isolated populations first increases, but after reaching a certain maximum value, it starts to decline and eventually becomes 0. The mean and variance of F_ST in this process are studied by using the recurrence formulas for the moments of gene frequencies in the island model of finite size as well as by using Monte Carlo simulation. The mean and variance in the early generations can be predicted by the approximate formulas developed. On the other hand, if we exclude the cases of an allele being fixed in all subpopulations, the mean of F_ST eventually reaches a steady-state value. This value is given by 1 − 2N_T(1 − λ) approximately, where N_T is the total population size and λ is the rate of decay of heterozygosity at steady state. It is shown that the mean and variance of F_ST depend on the initial gene frequency and when this is close to 0 or 1, Lewontin and Krakauer's test of the neutrality of polymorphic genes is not valid.     

Metabolism of lipid and carbohydrate in sea urchin spermatozoa

When the dry sperm of the sea urchin, Hemicentrotus pulcherrimus, were diluted 100 times in artificial sea water at 0°C and at 20°C, they became motile and the levels of ATP and creatine phosphate decreased rapidly. The level of ADP hardly changed, and the AMP level increased after the dilution. After the dilution, the respiratory rate at 2°C was almost one fifth that of 20°C. Both phospholipid and glycogen were used for the energy sources in sea urchin sperm. The level of phospholipid was 10-fold higher than that of glycogen in the dry sperm. The phospholipid level decreased after dilution at 20°C, though the level hardly changed at 0°C, suggesting that phospholipid was hardly metabolized the lower temperature. The level of α -glycerophosphate increased at 20°C after the dilution but did not change at 0°C. The level of glycogen decreased after the dilution, regardless of the temperature. The glycolysis was also activated after the dilution. Of the intermediates of the tricarboxylic acid cycle, the citrate concentration increased at 0°C and the malate concentration also increased at 0°C and especially strongly at 20°C.     

Utility and efficiency of linked marker genes for genetic counseling. II. Identification of linkage phase by offspring phenotypes

For a linked marker locus to be useful for genetic counseling, the counselee must be heterozygous for both disease and marker loci and his or her linkage phase must be known. It is shown that when the phenotypes of the counselee's previous children for the disease and marker loci are known, the linkage phase can often be inferred with a high probability, and thus it is possible to conduct genetic counseling. To evaluate the utility of linked marker genes for genetic counseling, the accuracy of prediction of the risk for a prospective child with a given marker gene to develop the genetic disease and the proportion of families in which a particular marker locus can be used for genetic counseling are studied for X-linked recessive, autosomal dominant, and autosomal recessive diseases. In the case of X-linked genetic diseases, information from children is very useful for determining the linkage phase of the counselee and predicting the genetic disease. In the case of autosomal dominant diseases, not all children are informative, but if the number of children is large, the phenotypes of children are often more informative than the information from grandparents. In the case of autosomal recessive diseases, information from grandparents is usually useless, since they show a normal phenotype for the disease locus. If we use information on the phenotypes of children, however, the linkage phase of the counselee and the risk of a prospective child can be inferred with a high probability. The proportion of informative families depends on the dominance relationship and frequencies of marker alleles, and the number of children. In general, codominant markers are more useful than are dominant markers, and a locus with high heterozygosity is more useful than is a locus with low heterozygosity.     

The selective inhibition of hippocampal glutamic acid decarboxylase in zinc-induced epileptic seizures

The intracerebroventricular administration of Zn²⁺ (0.3 mol/10 l) causes epileptic seizures characterized by running fits, jumping, vocalization, fasiculation of facial muscles, myoclonic movements of the limbs and tonic-clonic convulsions. These episodes are blocked or reversed by -aminobutyric acid (0.4 mol/10 l). When assayed under conditions where pyridoxal phosphate was not added, the activity of glutamic acid decarboxylase decreased significantly in hippocampus from 18.9 to 15.3 and 9.7 mol¹⁴CO₂ formed/gram proteins/20 min, 15 and 30 min following administration of Zn²⁺. The inhibition of glutamic acid decarboxylase by Zn²⁺ was selective occurring only in hippocampus and not in the hypothalamus, amygdala, caudate or thalamus. The inhibition of glutamic acid decarboxylase was not due to a reduction in the concentration of endogenous pyridoxal phosphate which remained unaltered in hippocampus following Zn²⁺ administration.     

Selective adhesion of embryonal carcinoma cells and differentiated cells by Ca2+-dependent sites

The specificity of adhesion between embryonal carcinoma cells and fibroblastic cells of various origins was studied. Embryonal carcinoma cells have intercellular adhesion sites requiring Ca²⁺ (CDS). These sites were found to be sensitive to proteases but resistant to them in the presence of Ca²⁺. CDS with a similar protease sensitivity is present in fibroblastic cells. When embryonal carcinoma cells of different lines were mixed, they adhered to each other nonselectively by CDS. Nonselective adhesion by CDS occurred also between fibroblastic cells of various lines. When embryonal carcinoma and fibroblastic cells were mixed, they preferentially adhered to homotypic cells. Fab fragments of antibodies raised against F9 cells (a nullipotent line of embryonal carcinoma) inhibited the adhesion between embryonal carcinoma cells but not between fibroblastic cells. This inhibitory activity of Fab was absorbed with embryonal carcinoma cells with CDS, but not with fibroblastic cells with CDS or embryonal carcinoma cells from which CDS was experimentally removed. SDS-polyacrylamide gel electrophoresis of radioiodinated cell surface proteins showed that the presence of a 140K-dalton component correlated with the presence of CDS in embryonal carcinoma cells, while the presence of a 150K-dalton component correlated with the presence of CDS in fibroblastic cells. These results suggest that CDS in embryonal carcinoma and fibroblastic cells comprise distinct molecules.