不同光照条件下外源水杨酸对浒苔响应紫外辐射胁迫的影响

为研究不同光照条件下,外源水杨酸(SA)和紫外辐射(UV)对海洋绿藻浒苔的复合效应,在两个光照强度(高光:160 μmol·m^-2·s^-1;低光:70 μmol·m^-2·s^-1)条件下,设置对照(CK)、SA、UV及UV+SA处理(UV=3.2 W·m^-2、SA=10 μg·mL^-1),处理3 d后测定浒苔生长、叶绿素荧光参数、光合放氧速率、超氧化物歧化酶活性、可溶性糖和可溶性蛋白含量等的变化,探讨光照强度、UV及SA的复合效应.结果表明: 低光无UV条件下,SA会促进浒苔生长,降低浒苔叶绿素a(Chl a)和可溶性蛋白含量;高光无UV条件下, SA会抑制其生长,但显著提高了Chl a含量、呼吸速率、光合放氧速率、可溶性糖和可溶性蛋白含量;高光和UV条件下, UV+SA显著促进浒苔生长,提高Chl a和可溶性糖含量;低光和UV条件下,与UV相比,UV+SA提高了浒苔最大光化学效率(F_v/F_m)和可溶性蛋白含量,涨幅分别为139.8%和32.2%.外源SA的加入在一定程度上缓解了UV对浒苔的胁迫作用,且在高光条件下的效果更为显著.     

Mitochondrial genomes of the green macroalga Ulva pertusa (Ulvophyceae,Chlorophyta): novel insights into the evolution of mitogenomes in the Ulvophyceae

To further understand the trends in the evolution of mitochondrial genomes (mitogenomes or mtDNAs) in the Ulvophyceae, the mitogenomes of two separate thalli of Ulva pertusa were sequenced. Two U. pertusa mitogenomes (Up1 and Up2) were 69,333 bp and 64,602 bp in length. These mitogenomes shared two ribosomal RNAs (rRNAs), 28 transfer RNAs (tRNAs), 29 protein‐coding genes, and 12 open reading frames. The 4.7 kb difference in size was attributed to variation in intron content and tandem repeat regions. A total of six introns were present in the smaller U. pertusa mtDNA (Up2), while the larger mtDNA (Up1) had eight. The larger mtDNA had two additional group II introns in two genes (cox1 and cox2) and tandem duplication mutations in noncoding regions. Our results showed the first case of intraspecific variation in chlorophytan mitogenomes and provided further genomic data for the undersampled Ulvophyceae.     

在水生与气生状态下石莼光合作用对无机碳的响应

潮间带海藻光合作用总是处于水生 (高潮时 )与气生 (低潮时 )两种连续变化的环境状态下进行。对汕头沿岸常见的潮间带海藻石莼 (UlvalactucaL .)在水生和气生不同状态下光合作用对无机碳的响应特性进行了比较研究。在水生状态下 ,现有海水中溶解性无机碳浓度能充分饱和 (10℃和 2 0℃时 )或接近饱和 (30℃时 )石莼的光合作用 ;而在气生状态下 ,石莼光合作用受大气CO2 浓度的限制 ,且这种限制作用在较高温度 (2 0 - 30℃ )下比在低温(10℃ )下更严重。在 10℃和 2 0℃时 ,石莼在气生状态下比在水生状态下具有更高的碳饱和最大光合速率 ;而在30℃时 ,石莼在这两种状态下的碳饱和光合速率相似。石莼光合作用的Km(CO2 )值在气生状态下比在水生状态下高 ;而在气生状态下石莼对CO2 的表观光合导度远小于其在水生状态下的值。认为大气CO2 浓度升高将通过促进石莼在气生状态下的光合作用而增加其初级生产力。     

Identification by SDS PAGE of green seaweeds ( Ulva and Enteromorpha) used in the food industry

SDS PAGE was tested as an analytical tool for the identification of fourgreen algae (Ulva rigida, U. rotundata, Enteromorphaintestinalis, E. compressa) used as food ingredients. A referencepattern composed of the bands present all year long was performed foreach species. The pattern for Ulva rotundata consists of 7 bandslocated between 69.9 and 15.5 kDa with the presence of triplicate bandsat 29.5, 26.3 and 22.9 kDa. The pattern for Ulva rigida is consistsof three bands with apparent molecular weights of 68.5, 56.4 and 44.7kDa. The Enteromorpha compressa pattern is characterised by sixbands located between 65.8 and 19.8 kDa. A double band withmolecular weights of 23.1 and 23.9 distinguished this pattern from theothers. Six bands situated between 66.4 and 19.4 kDa with a specifictriplicate band of 25.9, 23.9 and 22.5 kDa constituted the specific patternof Enteromorpha intestinalis. SDS PAGE appears to be suitable forthe identification of green seaweed foods.     

5种藻类金属硫蛋白的初步研究

用镉／血红蛋白饱和法测定海带、裙带菜、石莼、甘紫菜和石花菜等5种藻类MT的含量,结果表明：5种藻每g湿藻分别含2．5mg、5mg、4．8mg、2．6mg、2．4mg类MT;经CdCl2诱导后,类MT含量有不同程度的增加,分别变成5．2mg、8．8mg、10．0mg、4．0mg、3．2mg,其中石莼的诱导效果最显著,类MT的含量为每g湿藻含10．0mg类MT,是未经诱导的2．1倍。石莼、裙带莱和海带都是生产类MT的廉价材料。     

Waterborne compounds from the green seaweed Ulva reticulata as inhibitive cues for larval attachment and metamorphosis in the Polychaete Hydroides elegans

Field observations in Hong Kong waters have shown the marine macroalga Ulva reticulata Forsskal (Chlorophyta) to be free of fouling. In this study, the presumptive antifouling mechanism in this alga was investigated and attempts were made to distinguish between possible mechanisms. Waterborne algal compounds were analyzed in larval behavioral bioassays with the marine polychaete Hydroides elegans, a major fouling organism in tropical waters around the world. Larval attachment and metamorphosis in this sessile species is induced by specific bacterial strains in natural bio‐organic films. In bioassays with alga‐conditioned seawater, levels of larval metamorphosis were significantly reduced in comparison to controls. The results demonstrate that the inhibitive effect was caused by direct larval deterrence. Following a bio‐assay‐guided isolation procedure, an inhibitive fraction for larval metamorphosis was purified from U. reticulata‐conditioned seawater. Preliminary chemical analysis of the biologically active fraction pointed to polysaccharides, proteins or glycoconjugates with a molecular weight > 100 kD.     

Engineered antifouling microtopographies – correlating wettability with cell attachment

Abstract

Bioadhesion and surface wettability are influenced by microscale topography. In the present study, engineered pillars, ridges and biomimetic topography inspired by the skin of fast moving sharks (Sharklet AF?) were replicated in polydimethylsiloxane elastomer. Sessile drop contact angle changes on the surfaces correlated well (R² = 0.89) with Wenzel and Cassie and Baxter's relationships for wettability. Two separate biological responses, i.e. settlement of Ulva linza zoospores and alignment of porcine cardiovascular endothelial cells, were inversely proportional to the width (between 5 and 20 μm) of the engineered channels. Zoospore settlement was reduced by ～85% on the finer (ca 2 μm) and more complex Sharklet AF? topographies. The response of both cell types suggests their responses are governed by the same underlying thermodynamic principles as wettability.     

DAY AND NIGHT KINETICS OF GROWTH RATE IN GREEN,BROWN, AND RED SEAWEEDS1

Growth rates in terms of area increase per 30 min were measured in flat thalli of several seaweed, species by means of computer-assisted image analysis, at 12 h light per day and a photon fluence rate of 20 μmol · m^-2· s^?1. Light fields included white fluorescent, imitated underwater, blue, green, and red light. In the green alga Ulva pseudocurvata Koeman et Hoek, blue light caused an immediate reduction of thallus area and growth rate after the onset of light, whereas green light and red light resulted in an initial peak in growth rate followed by inhibition 60 min after the onset of light. More growth was observed in darkness than in blue light in U. pseudocurvata. All brown and red algae tested, with Laminaria saccharina (L.) Lamour. and Palmaria palmata Stackh. as the main investigated species, grew faster during the day than during the night, irrespective of light quality during the main light phase. The upper intertidal red alga Porphyra umbilicalis (L.) J. Ag. achieved most of its thallus expansion per 24 h during the first 3 h of the light phase, with maximum growth rates of 2–3% increase in area per hour. Maximal growth rates were 0.7% for juvenile laminarian sporophytes and were lower than this in Palmaria palmata and other perennial red algae. The temporary growth inhibition by light in Ulva pseudocurvata suggests photomorphogenetic events, similar to the kinetics of stem elongation in higher plant seedlings after blue or red light pulses in darkness.     

Analysis of Volatile Constituent by Hydrodistillation and Solid-Phase Microextraction Techniques and Antimicrobial and Scolicidal Activities of Essential Oil and Soxhlet Extracts of Ulva rigida grown in Turkey

In the present study, the volatile composition of Ulva rigida (U. rigida) was elucidated by two different methods. As a result of the identification process of volatile components using the GC/MS-FID instrument, 31 compounds were identified by hydrodistillation (HD) method, and 15 compounds were identified by solid-phase microextraction (SPME) method, elucidating the structure of 99.86 % and 92.65 %, respectively. The most abundant compounds in the essential oil of U. rigida were n-hexadecanoic acid and pentadecanal, while the most abundant compound according to the SPME analysis was heptadecyne, a hydrocarbon compound. In the next step, hexane, dichloromethane, chloroform and methanol solvent extracts of U. rigida were prepared and the antimicrobial activities of the extracts and the essential oil obtained by hydro-distillation as well as the scolicidal activities of the solvent extracts were determined. The results of the antimicrobial activity test of the essential oil showed a high level of activity against Bacillus cereus ATCC 10876 and MRSA. The highest activity was found on the microorganism of Pseudomonas aeruginosa ATCC 9027 in chloroform and methanol extracts of U. rigida. Furthermore, viability detection was performed and the scolicidal effects of the extracts on protoscoleces were assessed. The values of lethal concentration doses (LD₅₀, LD₇₅ and LD₉₀) were calculated using probit analysis.     

Chemical and physical-chemical characteristics of dietary fibres from Ulva lactuca (L.) Thuret and Enteromorpha compressa (L.) Grev.

Dietary fibres from Ulva lactuca (L.) Thuret (sea lettuce) and Enteromorpha compressa (L.) Grev. (A.O. nori) were measured according to a ‘standard’ method and a ‘physiological’ protocol simulating the gastric and intestinal environments. U. lactuca contained 15.8–8.0% soluble and 24.2–32.6% insoluble fibres according to the ‘standard’ and ‘physiological’ methods, respectively. For E. compressa, these values were 14.9–15.9 and 21.6–28.7%, respectively. For both algae, the composition suggests that the soluble fibres were xylorhamnoglycuronans sulphates and insoluble fibres were essentially composed of glucans. No marked chemical compositional variation was observed between soluble fractions extracted under the simulated gastric and intestinal conditions. Fibres in both algae are hydrophilic but the water holding capacities were higher after extraction of soluble fibres (5.5–9.5 g g⁻¹ for the dry algae; 14.0–16.0 g g⁻¹ for the standard insoluble fibres). Water soluble fibres demonstrated low intrinsic viscosities at 37 °C in buffers, particularly those from E. compressa (36.0–36.5 ml g⁻¹), and was affected by pH for those of U. lactuca (147.5 ml g⁻¹ at pH 3.0 and 175.0 ml g⁻¹ at pH 7.3).