Properties of peroxisomes and their induction by clofibrate in normal adult rat hepatocytes in primary culture

Alterations in peroxisomes and catalase activity and their responsiveness to clofibrate in adult rat hepatocytes in primary culture were investigated. The numbers of peroxisomes with and without crystalloid nucleotids per unit cytoplasmic area were preserved in cultured hepatocytes for 2 d after seeding at a level comparable to that of freshly isolated hepatocytes. At Day 3 in culture, the number of anucleoid peroxisomes was reduced in untreated hepatocytes, accompanied by more significant reduction in the number of nucleoid-containing peroxisomes, which decreased until Day 5. Peroxisome diameters were reduced in untreated hepatocytes at Day 2 and this decrease in the diameter was continued until Day 7. Catalase activity in untreated hepatocytes decreased markedly with culture age. The number of anucleoid peroxisomes was significantly greater in hepatocytes treated with 2 mM clofibrate in culture than in freshly isolated hepatocytes for 2 d or in untreated hepatocytes of the same culture age through 7 d. The number of nucleoid-containing peroxisomes in the treated cells began to decrease in 3 d, but was greater than that of untreated cells at Days 3 and 5. Peroxisomes with well-developed nucleoids were observed frequently in the treated cells even at Day 7. Peroxisome diameters were greater in the treated cells than in untreated cells at Days 3, 5, and 7. Catalase activity was always higher in the treated cells than in untreated cells. These results suggest that clofibrate is effective in inducing peroxisome proliferation as well as in maintaining the organelles in cultured hepatocytes.     

On the antisymmetry of the amino acid code table

Antisymmetry of the amino acid code table in terms of codon degeneracy is pointed out, and it is related to a physico-chemical problem of codon-anticodon interaction energy. A strong negative correlation between molecular weight of an amino acid and its codon degeneracy is pointed out, and its implication to the origin of the amino acid code table is discussed. Finally, an earlier form of the amino acid code table is proposed.     

Synthetic gibberellin synergists in elongation of shoot growth ofOryza sativa L.

Previous studies showed that 2-ethyl-3-methoxycarbonyl-1-(p-tolylcarbamoyl) isourea acts as a potent GA₃-synergist in stimulating shoot growth of rice seedlings. Studies with several structurally related compounds show that the alkoxycarbonylcarbamoyl-isourea or -isothiourea skeleton is required for biological activity. Any chemical deletion from this skeleton causes complete loss of activity. From present and previous data it seems that alkoxycarbonylcarbamoyl-isourea or -isothiourea is converted by intramolecular cyclization in the rice seedlings into the corresponding triazinone that serves as the active form.Part 9 in the series Plant Growth-regulating Activities of Isourea Derivatives and Related Compounds; for Part 8 seeReferences, Ogawa et al. (1980b)     

Characterization of a plant SINE, p-SINE1, in rice genomes.

We have previously found that a short interspersed element (SINE), named p-SINE1, is present in the Waxy gene of Oryza sativa in two copies. Here, we cloned five members of p-SINE1 located at other loci in O. sativa and determined their nucleotide sequences. These sequences had a T-rich pyrimidine tract at their defined 3' end and were flanked by direct repeats of a sequence of mostly 14-15 bp long like p-SINE1s in the Waxy gene. The consensus sequence derived from total seven members of p-SINE1 was 123 bp in length and had an internal promoter region for RNA polymerase III. The 5'-half region of the sequence was partially homologous to the tRNA-related block of rabbit C family, one of SINEs in the animal system. Two of the seven p-SINE1 members were not present in the corresponding loci in African rice, Oryza glaberrima, and may thus be available for classification of some rice strains. Comparison of the nucleotide sequences of the Waxy gene between O. sativa and O. glaberrima showed that base substitutions have frequently occurred in a p-SINE1 member (p-SINE1-r1) and a transposable element Tnr1 also present in the Waxy gene, suggesting that these elements, which appear as repetitive sequences in the rice chromosome, tend to acquire base substitutions at a higher frequency than do unique sequences.     

Gas chromatographic method for the determination of urinary acetylpolyamines

A gas chromatographic method was developed for the determination of monoacetylputrescine, monoacetylcadaverine, N¹-acetylspermidine and N⁵-acetylspermidine in human urine. The amines were isolated from urine by silica gel column chromatography. 1, 10-Diaminodecane was used as internal standard. The amines were reacted with ethyl chloroformate in aqueous medium to four ethyloxycarbonyl derivatives prior to application to gas chromatography using a flame ionization detector. Separation and determination of the derivatives were carried out on a Uniport HP column (1.0 m) impregnated with 0.5% SP-1000 under temperature-programmed conditions. The monoacetylpolyamines could be measured accurately at the nanomole level. The method was used for the determination of the monoacetylpolyamines in urine of healthy volunteers. The values obtained were in the range of the published data.     

Performance of fluidized-bed reactors utilizing magnetic fields

The performance of fluidized-bed reactors utilizing a magnetic field was determined by the use of magnetite-containing beads of immobilized unease. The reactors showed similar or higher conversions in comparison with fixed-bed reactors, although some aggregation of the beads in the magnetic field was observed. No effusion of the beads occurred up to a flow rate of 24 cm/min.     

Blood oxygen dissociation curve of the frogsRana catesbeiana andRana brevipoda

Summary The blood O₂ dissociation curve was determined with a microphotometric reaction apparatus in two frog species,Rana catesbeiana andRana brevipoda, and formulated in terms of a modified Hill equation. The O₂ dissociation curve was in reasonable agreement with determinations of O₂ content, O₂ capacity, and pH (or ) in blood samples taken from various blood vessels and heart cavities. The blood O₂ affinity inRana catesbeiana (mean body weight 230 g, kept at 25°C) was low:P ₅₀=42 Torr (at 25°C and at ventricular blood pH=7.79). The blood of the smaller frog,Rana brevipoda (mean body weight 16 g), had even lower O₂ affinity,P ₅₀ being 52 Torr (at 25°C, pH=7.72). The decrease ofP ₅₀ with increasing body mass, resulting from comparison of these two frog species, is in accordance with literature data on mammals and birds.     

Entropy of the genetic information and evolution

The entropy of the amino acid sequences coded by DNA is considered as a measure of diversity or variety of proteins, and is taken as a measure of evolution. The DNA or m-RNA sequence is corsidered as a stationary second-order Markov chain composed of four kinds of bases. Because of the biased nature of the genetic code table, increase of entropy of amino acid sequences is possible with biased nucleotide sequence. Thus the biased DNA base composition and the extreme rarity of the base doubletC _p G of higher organisms are explained. It is expected that the amino acid composition was highly biased at the days of the origin of the genetic code table, and the more frequent amino acids have tended to get rarer, and the rarer ones more frequent. This tendency is observed in the evolution of hemoglobin, cytochrome C, fibrinopeptide, immunoglobulin and lysozyme, and protein as a whole.     

A Basic Study on the Biological Monitoring for Vanadium—Effects of Vanadium on Vero Cells and the Evaluation of Intracellular Vanadium Contents

A high concentration of vanadium (V) has toxic effects on human and animals and is one of environmental pollutants. In the present study, we have conducted a fundamental study using cultured Vero cells from monkey kidney for the future environmental monitoring. Orthovanadate (VAN), one of V compounds, of 10⁻¹⁰ and 10⁻⁸ M did not affect the cell growth although the higher concentration of above 10⁻⁶ M VAN inhibited the cell growth accompanied with the decrease in cell numbers and morphological changes. Given that the washing method with ice-cold Li is also effective for determination of the cellular Na content, we used this method for the determination of the V content of the Vero cells. The V distributions in Vero cell; in the 10⁻³ M VAN solution, extracellular and intracellular were obtained as 1:0.564:0.036 and 1:0.662:0.098 at 60 and 120 min after the treatment of VAN. The intracellular V content was 10% of the applied concentration of VAN. Consequently, it was suggested that V concentration of 10⁻⁷ and 10⁻⁶ M in the tissue and environment, respectively, might become the threshold concentration; a criterion of the environmental contamination when we carry out environmental monitoring.     

Identification of a gene, Desiccate, contributing to desiccation resistance in Drosophila melanogaster

Suitable alterations in gene expression are believed to allow animals to survive drastic changes in environmental conditions. Drosophila melanogaster larvae cease eating and exit moist food to search for dry pupation sites after the foraging stage in what is known as the wandering stage. Although the behavioral change from foraging to wandering causes desiccation stress, the mechanism by which Drosophila larvae protect themselves from desiccation remains obscure. Here, we identified a gene, CG14686 (designated as Desiccate (Desi)), whose expression was elevated during the wandering stage. The Desi expression level was reversibly decreased by transferring wandering larvae to wet conditions and increased again by transferring them to dry conditions. Elevation of Desi expression was also observed in foraging larvae when they were placed in dry conditions. Desi encoded a 261-amino acid single-pass transmembrane protein with notable motifs, such as SH2 and PDZ domain-binding motifs and a cAMP-dependent protein kinase phosphorylation motif, in the cytoplasmic region, and its expression was observed mainly in the epidermal cells of the larval integuments. Overexpression of Desi slightly increased the larval resistance to desiccation stress during the second instar. Furthermore, Desi RNAi larvae lost more weight under dry conditions, and subsequently, their mortalities significantly increased compared with control larvae. Under dry conditions, consumption of carbohydrate was much higher in Desi RNAi larvae than control larvae. Based on these results, it is reasonable to conclude that Desi contributes to the resistance of Drosophila larvae to desiccation stress.