Two modes of bicarbonate utilization in the marine green macroalga Ulva lactuca

The green marine macroalga Ulva lactuca L. was found to be able to utilize HCO₃^? from sea water in two ways. When grown in flowing natural sea water at 16°C under constant dim irradiance, photosynthesis at pH8.4 was suppressed by acetazolamide but unaffected by 4,4′-diisothiocyanostilbene-2,2′-disulphonate. These responses indicate that photosynthetic HCO₃^? utilization was via extracellular carbonic anhydrase (CA) -mediated dehydration followed by CO₂ uptake. The algae were therefore described as being in a ‘CA state’. If treated for more than 10 h in a sea water flow-through system at pH9.8, these thalli became insensitive to acetazolamide but sensitive to 4,4′-diisothiocyanostilbene-2,2′-disulphonate. This suggests the involvement of an anion exchanger (AE) in the direct uptake of HCO₃^?, and these plants were accordingly described as being in an ‘AE state’. Such thalli showed an approximately 10-fold higher apparent affinity for HCO₃^? (at pH9.4) than those in the ‘CA state’, while thalli of both states showed a very high apparent affinity for CO₂. These results suggest that the two modes of HCO₃^? utilization constitute two ways in which inorganic carbon may enter the Ulva lactuca cells, with the direct entry of HCO₃^?, characterizing the ‘AE state’, being inducible and possibly functioning as a complementary uptake system at high external pH values (e.g. under conditions conducive to high photosynthetic rates). Both mechanisms of entry appear to be connected to concentrating CO₂ inside the cell, probably via a separate mechanism operating intracellularly.     

A study of the relative efficiency of mustard oil cake and urea and the effect of salinity in plankton production in indian fishponds

Augmentation of plankton production in Indian fishponds by application of manure and inorganic fertilisers was studied in laboratory experiments. The effects of the salinity of the medium were also examined.Laboratory trials were made with mustard oil cake and urea on equivalent nutrient bases in media with varying degrees of salinity (0–30 ppt at 2 ppt. intervals). It was observed that Closterium, Fragilaria, Pinnularia and Gyrosigma grew well in the higher salinity range between 24 to 30 ppt. whereas lower salinities ranging from a trace to 8 ppt. are suitable for improved production of Anabaena, Synedra, Navicula, Amphipleura, Amphora and Nitzschia. Comparatively better production of plankton was recorded with urea than with mustard oil cake.     

Salt tolerance of pigeon pea (Cajanus cajan (L.) Millsp.) at three growth stages

Salt tolerance of pigeon pea (Cajanus cajan (L.) Millsp.) was determined at three growth stages following observations by a number of workers that degree of salt tolerance of different crops varies with their ontogeny. The salt tolerance of three accessions, Local arhar, ICPL-151 and ICPL-850014 of pigeon pea was assessed at the germination, seedling and adult stages. There was no positive correlation between tolerance at the early growth stages and at the adult stage since no clear difference in salt tolerance of the three accessions was observed at the germination and the seedling stages, whereas accessions differed considerably at the adult stage. Although increasing salt concentrations adversely affected the growth of all three accessions, ICPL-151 was superior to the other two accessions in fresh and dry biomass, yield and yield components when tested at the adult stage. The tolerant accession, ICPL 151, accumulated significantly lower Na⁺and CI in shoots. By contrast it was higher in shoot and root K⁺, K/Na ratios, K vs Na selectivity, soluble sugars, free amino acids and proline compared with the other two accessions.     

Chirospecific synthesis of D and Lp-chlorohomophenylalanine N-t-BOC DCHA salts

Summary The chirospecific conversions of D-glucosamine hydrochloride and D-mannosamine hydrochloride to the configurationally stable L and D isomers of N-t-butyloxycarbonylserinal were carried out byt-butylcarbonylation followed by sodium borohydride reduction and sodium meta-periodate oxidation. Reaction of the L and D aldehydes with the Wittig reagent prepared from 4-chlorobenzyltriphenylphosphonium chloride and butyl lithium followed by catalytic hydrogenation, Jones oxidation and salt formation with dicyclohexylamine gave the DCHA salts of the D and L isomers ofp-chlorohomophenylalanine N-t-Boc in high enatiomeric excess. The optical purity of the title compounds was established by hydrolysis to the respective free amino acids, followed by chiral derivatization and HPLC analysis.This was presented at the Fifth International Kyoto Conference on new Aspects of Organic Chemistry, Kyoto, Japan, November 11–15, 1991. Abstract #GO-13.     

嗜盐耐盐微生物抗盐胁迫相关离子转运蛋白研究进展

离子转运蛋白在维持细胞内pH稳态、离子动态平衡等方面发挥着重要作用。钠离子转运体和钾离子转运体在嗜盐耐盐微生物中广泛存在,其"保钾排钠"机制是微生物抗盐胁迫的两大策略之一。近年来,嗜盐耐盐微生物中许多新型钠、钾离子转运体被陆续发现,如RDD蛋白、UPF0118蛋白、DUF蛋白和KimA蛋白等;Fe³⁺、Mg²⁺等其他金属离子的转运蛋白也被证实可通过影响微生物胞内相容性溶质的合成起到渗透调节的作用。本文综述了嗜盐耐盐微生物中抗盐胁迫相关的各类离子转运蛋白,分析其分子结构和工作机理,并对这些蛋白在农业方面的应用进行了展望。继续发现新的离子转运蛋白,探究抗盐胁迫相关离子转运蛋白的结构和机理,解析各转运系统的协同作用及分子调控机制,将进一步加深对嗜盐耐盐微生物抗盐胁迫调控的认识,并为盐碱地农作物的改良等提供新的思路。     

Evaluation of coupling conditions for the incorporation of Nα-Fmoc-Tyr(PO3H2)-OH in solid-phase peptide synthesis

Summary In order to minimise the formation of the pyrophosphate derivative of the target peptide when side-chain-unprotected phopshotyrosine is used in solid-phase peptide synthesis, this building block can be incorporated using benzotriazolyloxy-tris-(dimethylamino)phosphonium hexafluorophosphate/1-hydroxybenzotriazole/N-methylmorpholine (1:1:2.3) in the presence of a chaotropic salt (0.4 M LiCl in N-methyl-2-pyrrolidinone).Abbreviations BOP benzotriazolyloxy-tris-(dimethylamino)phosphonium hexafluorophosphate - DIEA diisopropylethylamine - Fmoc 9-fluorenylmethoxycarbony - HATU N-[(dimethylamino)1H-1,2,3-triazolo[4,5-b]pyridin-1-ylmethylene]-N-methylmethan-aminium hexafluorophosphate N-oxide - HOBt 1-hydroxybenzotriazole - HPLC high-performance liquid chromatography - MALDI-TOF matrix-assisted laser-desorption ionization time-of-flight mass spectrometry - NMM N-methylmorpholine - NMP N-methyl-2-pyrrolidinone - Pmc 2,2,5,7,8-pentamethyl-chroman-6-sulfonyl - ® solid support - TFA trifluoroacetic acid - TPTU 2-(2-pyridon-1-yl)-1,1,3,3-tetramethyluroniumfluoroborate. Abbreviations used for amino acids follow the recommendations of the IUPAC-IUB Commission of Biochemical Nomenclature [Eur. J. Biochem., 138 (1984) 9]     

Chemical speciation of arsenic in urine of patients with blackfoot disease

Blackfoot disease is a peripheral vascular disease resulting in gangrene of the lower extremities. Although extensive epidemiological study has implicated high arsenic content in artesian well water of the endemic area bears some important connection with the disease, the etiology of the disease is still not clarified. In this study, attention is paid to chemical speciation of arsenic in order to find out whether the concentrations of arsenic species in urine of Blackfoot disease patients are different from those of controls. Experimental results indicate that the total arsenic, inorganic arsenic, monomethylarsonic acid, and other forms of arsenic in the urine of patients are significantly higher than those of the contols. The possible connection of those arsenic species with the etiology of the disease is discussed.     

Three-step preparation and purification of phosphorus-33-labeled creatine phosphate of high specific activity

Rabbit heart mitochondria were used as a source of enzymes for the synthesis of phosphoruslabeled creatine phosphate. This method is based on the coupled reaction between mitochondrial oxidative phosphorylation and mitochondrial-bound creatine kinase. It is possible to convert more than 90% of the inorganic phosphate (P_i) to creatine phosphate. The method used only small amounts of adenine nucleotides which led to a product with only slight nucleotide contamination. This could be removed by activated charcoal extraction. For further purification, a method for the removal of residual P_i is described.