Lack of trnL intron in the thermoacidophilic red alga Galdieria sulphuraria (Galdieri) Merola

Abstract

The plastid trnC‐trnL(UAA)‐ilvH region from Galdieria sulphuraria was cloned and sequenced with the aim of verifying the absence of the trnL intron. The sequence alignment shows both the absence of a trnL intron and the colinearity of the whole region of the plastidial DNA of G. sulphuraria with that of the other thermoacidophilic red algae.     

Chrysochromulina tenuispina sp. nov. from arctic Canada

Chrysochromulina tenuispina sp. nov., has been described with the aid of light microscopy, scanning electron microscopy and transmission electron microscopy on dry preparations set up in situ from very cold water (-1°C) at one locality in arctic Canada. The cells are exceptionally large, with a highly characteristic periplast dominated by circular or oval plate-scales, some carrying a centrally attached stiff, slender, spine, up to 3 µm long and not more than 0·1 µm thick, indistinctly twisted through approximately two and a half turns from base to tip and underlain by larger more oval plates without spines. The patterning on the two faces of both types of plate is described in sufficient detail to demonstrate the presence of two sublayers building up the structure of each scale-face, the four superposed sublayers of a complete scale being interconnected in various ways.     

The effect of nitrogen starvation on the ultrastructure and pigment composition of chloroplasts in the acidothermophilic microalga Galdieria sulphuraria

We studied the effect of nitrogen starvation on growth indices, vitality, ultrastructure, and the photosynthetic apparatus of unique acidothermophilic microalga Galdieria sulphuraria (Galdieri) Merola. Long-term nitrogen starvation ceased G. sulphuraria growth and cell division. During the first days of starvation, phycobiliproteins degraded first, then the content of chlorophyll and carotenoids decreased to trace amounts, chloroplast reduced, cell wall became thinner, and storage compounds accumulated. However, the cells were alive. A comparison with the effects of nitrogen starvation on other photosynthesizing organisms showed that suppression of cell division, reduction of the photosynthetic apparatus to some minimum, and accumulation of storage compounds are a universal response to this stress.     

Characterization of two new thermoacidophilic microalgae: Genome organization and comparison with Galdieria sulphuraria

Abstract Thermoacidophilic algae ( Cyanidiaceae ) constitute a taxonomic group with interesting phylogenetic and ecological implications. In this report, we have classified three thermoacidophilic microalgal isolates from Rio Tinto (Spain) using a combination of classical analysis of phenotypic features and the characterization of their electrophoretically determined karyotypes by means of pulsed-field gel electrophoresis. Using this technique, we have been able to demonstrate that thermoacidophilic algae genomes have the smallest genomes of all photosynthetic eukaryotes studied so far. In addition, we show that two of these Rio Tinto isolates may constitute new species within the genus Galdieria .     

Effects of growing conditions and development of the underlying exodermis on the vitality of the onion root epidermis

Bulbs of Allium cepa L., which had developed short, adventitious roots, were transferred to various conditions, i.e. vermiculite watered to saturation, vermiculite watered to half saturation, immersed in hydroculture, and immersed in hydroculture except for the proximal 20 mm which was continuously exposed to air. The development of the exodermis occurred in a patchy fashion in many roots but was not influenced by the growing conditions. The vitality of the epidermis declined under all conditions, the rate of decline being inversely related to the ambient moisture level. The differences between the treatments were most evident at the oldest region sampled (120 mm from the root tip) where 4% of the epidermal cells were dead in roots grown in hydroponics. This compared with 62% dead cells in saturated vermiculite, 78% in half-saturated vermiculite and 92% in roots exposed to air. Death of the epidermal cells was not accelerated by the maturation of the underlying exodermis. Epidermal cells which did not overlie a short cell of the exodermis (i.e. were only in contact with long cells) died earlier than the others: this trend was evident even prior to the maturation of the exodermis. These results suggest that the epidermal cells are not well connected symplasmically to the long cells or to the neighbouring epidermal cells. The large majority of epidermal cells (98% of the total) were in contact with a short cell of the exodermis. These epidermal cells tended to die off slowly, even under very favourable ambient conditions. Since these cells provide the major site for ion uptake in roots with a mature exodermis. their death may reduce the efficiency of the root for this activity.     

Uridine diphosphogalactose-4 épimérase de fenugrec: essais de purification et quelques propriétés

The presence of a UDP Gal-4 epimerase is reported in fenugreek seedlings. It occurs as a soluble enzyme which loses its activity at pHs lower than 7, with an optimum pH at 8.5. Partial purification was achieved by ammonium sulphate precipitation and hydroxyapatite chromatography. The MW is 70 000 and it is linked to NAD⁺ as in the case of the enzymes of E. coli and yeast.     

Characterization of a non-thermophilic strain of the red algal genus Galdieria isolated from Soos (Czech Republic)

Volcanic areas with highly acidic solfatara soils and temperatures of up to 56?°C are inhabited by the red algal genus Galdieria. We examined three highly acidic but non-volcanic habitats in the western part of the Czech Republic for the occurrence of this red alga. In soil samples from the National Nature Reserve of Soos we found, together with Euglena mutabilis, Pseudococcomyxa simplex and species of Chlorella, a new strain of Galdieria. In contrast to all other Galdieria strains described so far, the strain from Soos exhibited a low temperature optimum for growth of about 30?°C. Other properties, such as the substrate spectrum for heterotrophic growth, ultrastructure, fatty acid composition, thermostability of enzymes and the nitrogen source, showed no obvious differences from other strains of Galdieria. Within a phylogenetic tree based on 18S rRNA sequence data, the strain from Soos occupied a position at the base of the ‘Galdieria’-branch. Our findings indicate that the genus Galdieria is not restricted to volcanic and mining areas and that strains of Galdieria are able to compete successfully with green algae in habitats like Soos.     

UDP-glucose-4-epimerase from Poterioochromonas malhamensis

UDP-glucose-4-epimerase of Poterioochromonas malhamensis, Peterfi has been purified to apparent electrophoretic homogeneity. The enzyme has an apparent MW of 120 000 as determined by gel filtration of the active enzyme. Sodium dodecylsulfate polyacrylamide gel electrophoresis gave a MW of 59 000, thus indicating a dimeric structure. The epimerase does not require external NAD for activity. The apparent K_m values for UDP-glucose and UDP-galactose were calculated to be 1.67 mM and 0.26 mM, respectively. The pH optimum is at pH 8.7 and the isoelectric point is at pH 5.1 ± 0.15.     

Characterization of the Bradyrhizobium japonicum galE gene: its impact on lipopolysaccharide profile and nodulation of soybean

The galE gene from Bradyrhizobium japonicum 61A101C, a soybean endosymbiont, was cloned and characterized. Its deduced amino-acid sequence showed a high similarity with that of other rhizobia. Functional identification of the galE gene was achieved by complementation of a galE mutant strain, PL2, with a series of pKM subclones. Disruption of the B. japonicum galE gene affects the lipopolysaccharide profile compared with that of the wild type, suggesting that galE is responsible for alteration of lipopolysaccharide structure. Examination of nodule formation by the wild-type and galE mutant revealed that the former displayed normal nodule development on soybean roots, whereas the latter showed no nodule formation at all time points examined except for 20 days after inoculation when <10% of soybean formed pseudo-nodules.     

Protease inhibitors of pigeonpea (Cajanus cajan) and its wild relatives

Plant protease inhibitors have been implicated in defense against insect pests. Podborer and pod fly are major pests of developing seeds of pigeonpea ( Cajanus cajan L. Millsp.). Therefore, we studied the presence of protease inhibitors in seeds of pigeonpea and its wild relatives. Seed extracts were analyzed for protease inhibitor activities by caseinolytic assay, and the number of protease inhibitors determined by polyacrylamide gel electrophoresis. Besides trypsin and chymotrypsin inhibitors, seed extracts contained weak papain inhibitor(s) but no bromelain inhibitor. Treatment of seed extract with bromelain generated new active forms of trypsin inhibitors. The relative amounts of different trypsin inhibitors and the total trypsin inhibitor activity varied with different extraction media. Trypsin inhibitors were not detectable in pigeonpea leaves. The profiles of trypsin and chymotrypsin inhibitors in almost all the cultivars of pigeonpea analyzed were similar; however, those in wild relatives were quite variable.     

嗜水气单胞菌J-1株弹性蛋白酶的表达、纯化及特性分析

摘要：【目的】表达、纯化嗜水气单胞菌J-1株弹性蛋白酶,并对弹性蛋白酶的性质进行分析。【方法】以pET-32a为表达载体将弹性蛋白酶基因ahyB转化至大肠杆菌BL21菌株中进行诱导表达,表达重组酶用His TaqNi2+亲和层析柱纯化并用6 mol/L盐酸胍进行复性;利用硫酸铵分级沉淀、阴离子交换层析和分子筛层析对嗜水气单胞菌培养上清液中的弹性蛋白酶进行纯化。将【结果】从嗜水气单胞菌培养上清液中获得的弹性蛋白酶原酶的最适pH 为8.5,而表达重组酶为 10.0;对热的稳定性,原酶高于表达酶。两种形式酶的性     

Uridine 5′-diphosphate glucose 4-epimerase from ehrlich ascites carcinoma cells

Uridine 5′-diphosphate glucose 4-epimerase (EC 5.1.3.2) from Ehrlich ascites carcinoma cells was purified to apparent homogeneity using conventional procedures and NAD-hexane-agarose affinity chromatography. The protein had a molecular weight of 96,000. The ascites enzyme had an absolute requirement for exogenously added NAD (10 ΜM) for stability. This appears to be a unique feature of ascites epimerase since epimerase from other mammalian sources did not exhibit such a dependence. Exogenously added NAD was also needed for catalysis with an apparentK _m value of 2.5 ΜM. NADH was a very potent competitive inhibitor (K _i = 0.11 ΜM with respect to NAD) of the enzyme activity at pH values close to intracellular pH. The dependence of the enzyme on NAD for stability and its inhibition by NADH may have some potential significance in tumor metabolism     

纤维二糖差向异构酶在毕赤酵母中的表达及酶学性质研究

首先将来源于Caldicellulosiruptor saccharolyticus的纤维二糖差向异构酶基因CsCEm进行密码子优化,然后进行全基因合成,再将其引入到载体pPIC9K中,构建重组质粒pPIC9K-CsCEm并转化入毕赤酵母GS115,得到酵母工程菌株.经微孔板筛选、摇瓶筛选得到酶活最高的重组工程茵GS115-4-19.该菌株经甲醇诱导144 h后,摇瓶发酵液上清酶活达到0.42 U/mL.酶学性质研究结果表明:该酶的最适pH为7.5,且在pH 6.0 ～8.0范围内相对酶活都在80％以上;在pH 4～9的缓冲液中放置24 h后仍保持原酶活力的80％以上;最适温度为80℃,在60℃～80℃保温30 min后,相对酶活在80％以上.动力学研究结果表明该酶对底物乳糖的Km和Vmax分别为(120.27±9.96) mmol/L和(1.035±0.05) mmol/L/min.纤维二糖差向异构酶在毕赤酵母中的成功表达为生物酶法合成乳果糖提供了重要参考.