Enhanced growth of the red algaPorphyra yezoensis Ueda in high CO2 concentrations

Leafy thalli of the red algaPorphyra yezoensis Ueda, initiated from conchospores released from free-living conchocelis, were cultured using aeration with high CO₂. It was found that the higher the CO₂ concentration, the faster the growth of the thalli. Aeration with elevated CO₂ lowered pH in dark, but raised pH remarkably in light with the thalli, because the photosynthetic conversion of HCO ₃ ^? to OH^? and CO₂ proceeded much faster than the dissociation of hydrated CO₂ releasing H⁺. Photosynthesis of the alga was found to be enhanced in the seawater of elevated dissolved inorganic carbon (DIC, CO₂ + HCO ₃ ^? + CO ₃ ^? ). It is concluded that the increased pH in the light resulted in the increase of DIC in the culture media, thus enhancing photosynthesis and growth. The relevance of the results to removal of atmospheric CO₂ by marine algae is discussed.     

Effect of dehydration on thirst and drinking during immersion in men.

The mechanism for reduced voluntary water intake during water immersion was studied in eight men (19-25 yr of age) immersed to the neck while sitting for 3 h at 34.5 degrees C or in air at 28 degrees C when euhydrated (Eu-H2O and Eu-air, respectively) and hypohydrated (Hypo-H2O and Hypo-air) by 3.6% body weight loss. Thirst sensations (degree of thirst, mouth dryness and taste, drinking desirability, and stomach fullness) were similar at the beginning of Hypo-air and Hypo-H2O test periods. Initial drinking of tap water (15 degrees C) was 216 +/- 30 ml/7 min (P less than 0.05) with Hypo-air, decreased to 108 +/- 28 ml/7 min (P less than 0.05) with Hypo-H2O, and was 10-50 ml/10-30 min thereafter. Intake was less than 10 ml/10-30 min in Eu-air, and there was no drinking in Eu-H2O. Within the first 10 min of immersion, compared with Hypo-air findings, the significant reduction in drinking in the Hypo-H2O experiment was associated with unchanged plasma Na+, plasma osmolality, heart rates, and mean arterial pressures; the different responses were increased cardiac output, plasma volume, and atrial natriuretic peptides and decreased plasma renin activity and arginine vasopressin. Thus the extracellular pathway, as opposed to the osmotic pathway, appears to be the major mechanism for immersion-induced suppression of drinking.     

Structural studies of rat cathepsin E: amino-terminal structure and carbohydrate units of mature enzyme

The amino-terminal structure of rat gastric cathepsin E was identified and compared with the corresponding regions of human procathepsin E and other aspartic proteinases. The alignment revealed that cathepsin E has the most extended amino-terminal structure in aspartic proteinases, thus suggesting that the activation peptide (propeptide) of the human enzyme is 39-residues long. Analysis of oligosaccharide units suggested that rat cathepsin E possesses one N-linked carbohydrate unit, probably of the high mannose type. No evidence was obtained for the presence of O-linked sugars in rat cathepsin E.     

Suppression mutations in the defective beta subunit of F1-ATPase from Escherichia coli

The Escherichia coli mutant of the proton-translocating ATPase KF11 (Kanazawa, H., Horiuchi, Y., Takagi, M., Ishino, Y., and Futai, M. (1980) J. Biochem. (Tokyo) 88, 695-703) has a defective beta subunit with serine being replaced by phenylalanine at codon 174. Four suppression mutants (RE10, RE17, RE18, and RE20) from this strain capable of growth on minimal plate agar supplemented by succinate were isolated. The original point mutation at codon 174 was intact in these strains. Additional point mutations, Ala-295 to Thr, Gly-149 to Ser, Leu-400 to Gln, Ala-295 to Pro, for RE10, RE17, RE18, and RE20, respectively, were identified by the polymerase chain reaction and sequencing. These mutations, except for RE10, were confirmed as a single mutation conferring a suppressive phenotype by genetic suppression assay using KF11 as the host cells. The results indicated that Ser-174 has functional interaction with Gly-149, Ala-295, and Leu-400. The residues are located within the previously estimated catalytic domain of the beta subunit, indicating that this domain is indeed folded for the active site of catalytic function. Growth rates of the revertants in the minimal medium with succinate increased compared with that of KF11, showing that ATP synthesis recovered to some extent. The ATP hydrolytic activity in the revertant membranes increased in RE17 and RE20 but did not in RE10 and RE18, suggesting that synthesis and hydrolysis are not necessarily reversible in the proton-translocating ATPase (F1F0).     

A case of first trimester prenatal diagnosis of 21-hydroxylase deficiency with human complement C4 cDNA probe

Early prenatal diagnosis of 21-hydroxylase (21-OHase) deficiency would enable treatment to be done to protect the fetus from masculinization and/or life-threatening adrenal crisis at birth. We report here the prenatal diagnosis of 21-OHase deficiency with human complement component C4 cDNA to probe DNA from chorionic villi at 10 weeks of gestation. Southern analysis with human C4 cDNA identified TaqI restriction fragment length polymorphisms (RFLPs) in the family. Family analysis with these RELPs showed that the fetus was not affected at greater than 99% probability, because the frequency of recombination between the 21-OHase B gene and the C4 gene would be extremely low.     

Translocation of colicin E1 through cytoplasmic membrane of Escherichia coli

The product of the malE—lacZ gene fusion was reported to compete with some proteins including outer membrane lipoprotein in the protein translocation across the Echerichia coli membrane. The fusion product also inhibited colicin E1 export. Furthermore, globomycin, which accumulated prolipoprotein in the membrane, inhibited the translocation of colicin E1 in the wild-type cells, but not in lipoprotein-negative mutant cells. Since colicin E1 contains the internal signal-like sequence [Proc. Natl. Acad. Sci. USA (1982) 79, 2827–2831], these results suggest that colicin E1 is exported by the aid of this sequence at a common site for maltose-binding protein and lipoprotein translocation.     

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.     

A fluorescence probe study of the phosphorylation reaction of the calcium ATPase of sarcoplasmic reticulum

The fluorescent thiol reagent N-(1-anilinonaphthyl-4)maleimide (ANM) reacts covalently with the Ca2+ ATPase moiety of fragmented sarcoplasmic reticulum in two phases as determined by the increase of fluorescence intensity and optical density at 350 nm. In the rapid phase, 5.5 nmol of ANM reacts with 1 mg of fragmented sarcoplasmic reticulum protein. Assuming that 55% of the total membrane protein is the Ca2+ ATPase, this is equivalent to 1 mol of SH/10(5) g of ATPase, designated as SH1-ANM. ANM reacts with the second SH (SH2-ANM) at a much slower rate. Reaction of ANM with both SH1-ANM and SH2-ANM produces no inhibition of phosphoenzyme (EP) formation. Upon addition of Mg . ATP in the micromolar range, at [Ca2+] = 1 microM there is an increase in the fluorescence intensity of ANM attached to SH2-ANM, while the ANM attached to SH1-ANM does not respond to Mg . ATP. Under conditions in which there is no EP formation, there is no fluorescence change. Furthermore, the enhancement of ANM fluorescence produced by Mg . ATP is reversed by ADP as it reacts with EP to form ATP. Thus, it appears that the Mg . ATP-induced fluorescence increase reflects changes of enzyme conformation produced by EP formation.