Temperature tolerance of young sporophytes from two populations of Laminaria japonica revealed by chlorophyll fluorescence measurements and short-term growth and survival performances in tank culture

The cold-water subtidal brown alga Laminaria japonica has been commercially fanned in the Far East and has been on top of all marine-fanned species in terms of farming area and annual output worldwide. The successful trials of transplantation of young sporophytes from the north to the south in winter along the Chinese coast in the 1950s led to the spreading of cultivation activities down to a latitude of 25-26 degrees N. Up to today, nearly 50% of the annual output of this farmed alga, as a cold-water species, comes from the sub-tropical south in China. The demand to have high-temperature-tolerant strains/ecotypes in farming area calls for a practical method to judge and select the desired parental plants for breeding programs and for seedling production. In this paper, we report our results on using chlorophyll fluorescence measurement and short-term growth performance in tank culture to estimate the temperature tolerance of offspring from two populations, Fujian Farmed Population (FFP) sampled from Fujian province (latitude: 25-26 degrees N) in subtropical area and Qingdao Wild Population (QWP) sampled from Qingdao (latitude: 36 degrees N). Contrary to what has been usually thought, the results revealed that offspring from Qingdao wild population in the north showed better performance both in short-term growth and survival rates and in optimal quantum efficiency (F-v/F-m) when exposed to higher temperature (20-25 degrees C). This result was further confirmed by fluorescence quenching analysis. QWP distributed along the southern distribution limit at a latitude of 36 degrees N in the Pacific west coast is thus taken as a more ideal one than the fanned population in subtropical region as a source of parental plants for breeding high-temperature-tolerant varieties. (c) 2006 Elsevier B.V. All rights reserved.

Temperature and light tolerance of representative brown, green and red algae in tumble culture revealed by chlorophyll fluorescence measurements

Laminaria japonica, Undaria pinnatifida, Ulva lactuca, Grateloupia turuturu and Palmaria palmata are Suitable species that fit the requirements of a seaweed-animal integrated aquaculture system in terms of their viable biomass, rapid growth and promising nutrient uptake rates. fit this investigation, the responses of the optimal chlorophyll fluorescence yield of the five algal species in tumble Culture were assessed at a temperature range of 10 similar to 30 degrees C. The results revealed that Ulva lactuca was the most resistant species to high temperature, withstanding 30 degrees C for 4 h without apparent decline in the optimal chlorophyll fluorescence yield. While the arctic alga Palmaria palmata was the most vulnerable one, showing significant decline in the optimal chlorophyll fluorescence yield at 25 degrees C for 2 h. The cold-water species Laminaria japonica, however, demonstrated strong ability to cope with higher temperature (24 similar to 26 degrees C) for shorter time (within 24 h) without significant decline in the optimal chlorophyll fluorescence yield. Grateloupia turuturu showed a general decrease in the optimal chlorophyll fluorescence yield with the rising temperature from 23 to 30 degrees C, similar to the temperate kelp Undaria pinnatifida. Changes of chlorophyll fluorescence yields of these algae were characterized differently indicating the existence of species-unique strategy to cope with high light. Measurements of the optimal chlorophyll fluorescence yield after short exposure to direct solar irradiance revealed how long these exposures could be without significant photoinhibition or with promising recovery in photosynthetic activities. Seasonal pattern of alternation of algal species in tank culture in the Northern Hemisphere at the latitude of 36 degrees N was proposed according to these basic measurements.

水稻OsMYB3R-2 基因对逆境响应的功能研究

低温威胁水稻的生产，其中苗期和生殖阶段对寒害是最敏感的时期。在苗期，阶段性冷害使水稻幼苗生长延迟，甚至造成烂秧现象；在生殖阶段，无法预测的突然降温会导致水稻花粉不育，并致使水稻大幅减产。因此，对水稻逆境胁迫调控的分子机制的深入研究在理论和实践上具有重要的意义。本研究从东乡野生稻、栽培稻及其杂交后代的低温芯片中筛选对低温响应基因的分析着手，对其中一个受低温诱导上调的基因OsMYB3R-2 作进一步研究。生物信息学的分析表明OsMYB3R-2 编码一个R1R2R3 MYB 蛋白，利用基因枪瞬时转化法、酵母GAL4 系统和电泳迁移率变动分析发现OsMYB3R-2 蛋白能够定位在细胞核中、具有转录激活和DNA 结合特性，表现为MYB 转录因子的典型特征。 超表达OsMYB3R-2 的转基因水稻呈现幼苗的矮化和生长相对滞后的表型，对低温胁迫具有耐受性。盐抑制水稻种子的萌发，与野生型和反义的株系相比，OsMYB3R-2 超表达株系的萌发对盐敏感，表现为萌发过程及萌发之后幼苗的生长更加滞后。而OsMYB3R-2 转基因株系对干旱处理敏感。为了进一步寻找OsMYB3R-2 蛋白的靶序列及其调控的靶基因，我们利用电泳迁移率变动分析发现OsMYB3R-2 能够与有丝分裂特异的激活子（mitosis-specific activator）元件特异结合。在低温条件下，OsMYB3R-2 超表达能够激活水稻G2/M 期特异基因的表达，主要包括OsCycB1;1、OsCycB2;1、OsCycB2;2 和OsCDC20.1 等。另一方面，OsMYB3R-2 超表达能够增加根尖细胞的有丝分裂指数，这进一步说明OsMYB3R-2 参与了水稻细胞周期调控。EMSA、RT-PCR 和流式细胞仪分析的结果表明OsMYB3R-2 通过激活其靶基因OsCycB1;1 的表达参与水稻对低温胁迫的调控，该过程由细胞周期介导。 为了研究OsMYB3R-2 与水稻DREB/CBF 途径的关系，我们分析了转基因水稻中DREB/CBF 类基因及其可能调控的下游基因与OsMYB3R-2 的关系，RT-PCR 的结果表明超表达转基因植物中DREB 表达未见明显变化，而其下游基因OsCPT1 在低温条件下被激活表达。同时，转基因植物在低温条件下脯氨酸水平显著提高。这说明OsMYB3R-2 可能在水稻DREB/CBF 途径的下游参与调控。 总之，OsMYB3R-2 基因的超表达赋予转基因水稻在苗期对低温胁迫具有耐受性，并呈现矮化和生长滞后的表型。OsMYB3R-2 蛋白行使R1R2R3 MYB 转录因子的功能，在体外能够结合OsCycB1;1 和OsKNOLLE2 基因启动子中有丝分裂特异的激活子元件，在低温条件下激活了G2/M 期特异基因的表达，这些基因包括OsCycB1;1、OsCycB2;1、OsCycB2;2 和OsCDC20.1。低温条件下，在OsMYB3R-2 转基因超表达株系中OsCPT1 基因的转录被激活，细胞的游离脯氨酸的含量也显著增高。这些结果都表明OsMYB3R-2 基因在水稻的冷胁迫信号途径中起重要的作用，该过程受细胞周期及DREB/CBF 途径介导。 我们的实验结果暗示水稻对低温的耐受是通过分生组织细胞周期调控完成的，这个过程由OsMYB3R-2 等关键基因控制。

西藏齿突蟾蝌蚪冷适应策略研究

本文通过对高海拔两栖类西藏齿突蟾(Scutiger boulengeri)蝌蚪在实验室特定低温条件下的冷适应微空间行为分布的动态变化分析、温度耐受性实验及在不同适应温度的乳酸脱氢酶(LDH)同工酶的酶量与活性比较分析, 探讨了高海拔两栖类蝌蚪的部分冷适应策略。 西藏齿突蟾蝌蚪在不同温度的行为分布是一连续、动态过程，需用多种检验方法综合利用才能进行判断；在15℃, 除低海拔分布的西藏齿突蟾种群外所有实验物种蝌蚪均符合负二项分布、NeymanⅡ型分布；在10℃, 高海拔两栖类蝌蚪均符合负二项分布、NeymanⅡ型分布；在5℃、0℃低温时，高海拔两栖类不同分组的西藏齿突蟾蝌蚪的负二项分布、NeymanⅡ型分布均呈现明显差异, 这可能与高海拔两栖类蝌蚪在低温条件下通过不断地改变其行为分布方式来避免自身被冻伤有关。野外观察表明：高海拔两栖类蝌蚪常选择与流动河水相连的静水水体这种微生境中生存, 蝌蚪应对环境温度极端变化会不断改变其行为分布方式来选择最佳生存温度以避免极端高、低温对自身身体的伤害, 这种对微生境的利用能力对高海拔两栖类蝌蚪耐受极端环境温度的变化极其重要。 两栖类蝌蚪的温度耐受性实验表明不同的驯化温度可以改变西藏齿突蟾蝌蚪、两栖类仙琴水蛙蝌蚪的最适温度、逃避温度，并具有显著影响。 随着驯化温度5℃、10℃逐渐升高, 其最适温度、逃避温度也在一定范围内升高，但驯化温度对低海拔的仙琴水蛙蝌蚪的最适温度、逃避温度的改变效应大于高海拔的西藏齿突蟾蝌蚪的改变效应, 仙琴水蛙蝌蚪对温度的耐受范围、最适温度和逃避温度的ARRS值都大于西藏齿突蟾蝌蚪, 这说明仙琴水蛙蝌蚪对环境温度变化的适应能力大于西藏齿突蟾蝌蚪。 高海拔地区不同分组的两栖类蝌蚪, 在0℃适应温度时, LDH5条带的酶相对含量最高，而在5℃、10℃、15℃适应温度时，LDH5条带的酶相对含量明显都降低, 这表明酵解作用是高海拔两栖类蝌蚪的一些组织在低温﹑缺氧环境中的重要供能方式。高海拔两栖类蝌蚪同一分组的LDH总酶活性总是表现为10℃适应温度的总酶活性最高，而对低海拔的两栖类蝌蚪则是0℃适应温度的总酶活性最高, 这说明高海拔两栖类蝌蚪的LDH同工酶A、B两亚基基因活性在10℃时最高, 而低海拔两栖类蝌蚪的LDH同工酶A、B两亚基基因活性在0℃时最高。同时发现在15℃适应温度组的高海拔两栖类蝌蚪的LDH电泳图谱都有第6条带,有可能由LDH - C亚基组成, 对高海拔两栖类蝌蚪的LDH - C亚基只在15℃适应温度下才表达的机理还有待进一步的研究。 高海拔两栖类西藏齿突蟾蝌蚪通过行为分布方式的改变来选择最佳的生存温度, 这种温度选择过程与野外特定的微生境的存在密切相关, 现在由于人类对河道的不合理利用正在导致高海拔两栖类蝌蚪赖以生存的这种微生境逐渐消失, 这种微生境的消失将加速高海拔的两栖类种群数量衰退的进程。高海拔两栖类物种蝌蚪在低温（0℃）上表现出的同工酶多谱带说明，其A、B两亚基都有所表达，及其参与代谢的方式也是正常的，而低海拔两栖类物种蝌蚪只有A亚基表达的LDH5存在，因此其主要参与酵解过程，这种通过动物自身生理代谢方式的改变来适应极端环境温度条件的变化是高海拔两栖类蝌蚪能适应低温环境的重要策略。但高海拔物种的适应温度变化范围显著小于低海拔物种，对环境温度的变化适应能力有限，特别是对高温区域，因此全球气候变化可能对高海拔物种影响更为显著。 The partly cold-adaptation stratagem of the high altitude amphibian tadpole were researched in the laboratory by analyzing the high altitude amphibian tadpole of Scutiger boulengeri mainly on endpoints related to the dynamic variation of the micro-spatial behavior distribution patterns, the experiment of the temperature tolerance, and the enzyme content and activity of the lactic acid dehydrogenase(LDH) isozyme in special temperature condition. The behavior distribution of the Scutiger boulengeri tadpole is continuous and variable, but it can be figured out by multple testing ways. At 15℃, all of the experiment amphibian tadpoles behavior distribution fit both for the negative binomial distribution and NeymanⅡtype distribution except for the low altitude Scutiger boulengeri tadpoles. At 10℃, all of the high altitude amphibian tadpoles behavior distribution fit both for the negative binomial distribution and NeymanⅡtype distribution. At lower temperature, 5℃ and 0℃, the high altitude amphibian tadpoles of the Scutiger boulengeri at different groups behavior distribution fit for or don’t fit for behavior distribution respectively. It is denoted that the high altitude amphibian tadpoles probably avoid frostbiting by varying the behavior distribution patterns at low temperature condition. The high altitude amphibian tadpoles often actively select the special microhabitat which has the connected still water body and the flowing water body in the wild. It is important that tadpoles can endure the extreme temperature variety in this kind of microhabitat, because tadpoles can be better survival through select temperature condition through migrating in these kinds of microhabitats by varying their own behavior distribution patterns. Different acclimation temperature causes the significant change of preferred temperature(PT)、 avoiding temperature(AT) both in high altitude amphibian Scutiger boulengeri tadpoles and in low altitude amphibian Rana daunchina tadpoles in the temperature endurance experiment. With the acclimation temperature growing from 5℃ to 10℃. the PT and the AT of them would be uprise to some extent, but the effect of acclimation temperature on the PT and the AT of the tadpoles of Rana daunchina is more significant than the ones on the tadpoles of Scutiger boulengeri, at the same, the effects on the temperature endurance range, the ARRs of the tadpoles of Rana daunchina would be stronger than the ones on the tadpoles of Scutiger boulengeri. It is implied that the adaptation ability of tadpoles of Rana daunchina to the surroundings temperature alternation preferred to tadpoles of Scutiger boulengeri. At 0℃ acclimation temperature, the LDH5 enzyme comparative content of the high altitude amphibian tadpoles at different groups was highest, but it becomes lower at 5℃、10℃、15℃ acclimation temperature. It indicated that the alcoholysis role was the important ways of applying energy for special tissue of the high altitude amphibian tadpoles in low-temperature and low-oxygen condition. The total enzyme activity of the LDH of the high altitude amphibian tadpoles in the same group always keeps the highest at 10℃ acclimation temperature, but the low altitude amphibian tadpoles’ was maximum at 0℃. It was denoted that the gene activity of LDH -A and LDH – B submit was highest at 10℃ acclimation temperature for the high altitude amphibian tadpoles, but the low altitude amphibian tadpoles’ was maximum at 0℃. Meanwhile, the LDH electrophoretogram of the high altitude amphibian tadpoles always composed of 6 stripes at 15℃ acclimation temperature，the extra stripe probably was composed by LDH-C submit。It is unknown why LDH-C expresses only under high temperature。. The high altitude amphibian tadpoles can select the most optimal temperature by changing their behavior distribution patterns ceaselessly, but this course of selecting the most suitable temperature correlated with the special microhabitat in the wild closely. Nowadays, this kind of microhabitat which the high altitude amphibian tadpoles rely on are lossing gradually for human being exploit the riverway unreasonably. The disappearing of the microhabitat would accelerate the decline of the high altitude amphibian population. Compare to one band of LDH5, which only composed by the LDH-A submit, presents in the low altitude amphibian at 0℃, the five bands which composed by the LDH-A and LDH-B are checked out, this means the species which occurred in the highland is more adaptable to the low temperature. It is an important stratagem for the high altitude amphibian tadpoles adapt to the limited low temperature depends on the animal energy metabolism change.However, this kind of adaption is restricted, the adaption range to the temperature is much norrow in the high altitude amphibian than in the low one, especially for the high temperature side. The global climate change will be more serious for the high altitude species.

RESPONSES OF Elodea nuttallii AND Ceratophyllum demersum TO HIGH TEMPERATURE

There were large losses of exotic species Elodea nuttallii during summer in eutrophic lakes of the middle and lower reaches of the Yanatze River, China. To investigate the main causes, the heat tolerance of E. nuttallii was studied and compared with that of native species Ceratopkyllum demersum by using an aquaria system in the laboratory. Under 4500 lx light intensity and 12-h L/12-h D cycle, E. nuttallii cultured in 1/5 Hoaglands solution at 39 degrees C showed a positive growth rate during the first 15 days, and the growth rate was higher than that at 35 degrees C. But after 15 days, the growth rates became negative for those cultured both at 39 and 35 degrees C. However, the growth rate was positive for more than 20 days for those cultured at 25 degrees C. Under the same conditions, the growth rate, productivity and chlorophyll content of E. nuttallii were significantly higher than that of C. demersum. Heat tolerance of E. nuttallii was also stronger than that of C. demersum. The optimal temperature for the growth of the two plants depended on the experimental period: both plants grew at an optimal rate at higher temperature if the experimental period was short; nevertheless the plants achieved optimal growth at a lower temperature if the experiment was conducted for a longer period. At the same light intensity, the heat tolerance of C. demersum in tap water with sediment was markedly stronger than that of E. nuttallii at 39 degrees C. Average growth rate of C. demersum was 4.5 times higher than that of E. nuttallii within 25 days. The positive growth period lasted for less than 25 days for E. nuttallii and for more than 25 days for C. demersum. When they were cultured in 1/5 Hoaglands solution and in tap water with sediment, the growth rate of C. demersum increased from 0.4 to 79.4 mg/d.g fresh weight (FW) within 20 days. E. nuttallii increased from 8.3 to 24.4 mg/d-g FW within 20 days. Both grew better in tap water with sediment than in 1/5 Hoaglands solution. The results demonstrated that the nutritional status of the water other than the high temperature affected the heat tolerance of E. nuttallii during summer. E. nuttallii has great ecological safe risk in China.

alpha-tocopherol is essential for acquired chill-light tolerance in the cyanobacterium Synechocystis sp strain PCC 6803

Unlike Escherichia coli, the cyanobacterium Synechocystis sp. strain PCC 6803 is insensitive to chill (5 degrees C) in the dark but rapidly losses viability when exposed to chill in the light (100 mu mol photons m(-2) s(-1)). Preconditioning at a low temperature (15 degrees C) greatly enhances the chill-light tolerance of Synechocystis sp. strain PCC 6803. This phenomenon is called acquired chill-light tolerance (ACLT). Preconditioned wild-type cells maintained a substantially higher level of alpha-tocopherol after exposure to chill-light stress. Mutants unable to synthesize alpha-tocopherol, such as slr1736, slr1737, slr0089, and slr0090 mutants, almost completely lost ACLT. When exposed to chill without light, these mutants showed no or a slight difference from the wild type. When complemented, the slr0089 mutant regained its ACLT. Copper-regulated expression of slr0090 from P-petE controlled the level of et-tocopherol and ACLT. We conclude that alpha-tocopherol is essential for ACLT of Synechocystis sp. strain PCC 6803. The role of a-tocopherol in ACLT may be based largely on a nonantioxidant activity that is not possessed by other tocopherols or pathway intermediates.

Different tolerances and responses to low temperature and darkness between waterbloom forming cyanobacterium Microcystis and a green alga Scenedesmus

The dynamics of planktonic cyanobacteria in eutrophicated freshwaters play an important role in formation of annual summer blooms, yet overwintering mechanisms of these water bloom forming cyanobacteria remain unknown. The responses to darkness and low temperature of three strains (unicellular Microcystis aeruginosa FACHB-905, colonial M. aeruginosa FACHB-938, and a green alga Scenedesmus quadricauda FACHB-45) were investigated in the present study. After a 30-day incubation under darkness and low temperature, cell morphology, cell numbers, chlorophyll a, photosynthetic activity (ETRmax and I-k), and malodialdehyde (MDA) content exhibited significant changes in Scenedesmus. In contrast, Microcystis aeruginosa cells did not change markedly in morphology, chlorophyll a, photosynthetic activity, and MDA content. The stress caused by low temperature and darkness resulted in an increase of the antioxidative enzyme-catalase (CAT) in all three strains. When the three strains re-grew under routine cultivated condition subjected to darkness and low temperature, specific growth rate of Scenedesmus was lower than that of Microcystis. Flow cytometry (FCM) examination indicated that two distinct types of metabolic response to darkness and low temperature existed in the three strains. The results from the present study reveal that the cyanobacterium Microcystis, especially colonial Microcystis, has greater endurance and adaptation ability to the stress of darkness and low temperature than the green alga Scenedesmus.

Identification of a gene, ccr-1 (sll1242), required for chill-light tolerance and growth at 15 degrees C in Synechocystis sp PCC 6803

Synechocystis sp. PCC 6803 exposed to chill (5 degrees C)-light (100 mu mol photons m(-2) s(-1)) stress loses its ability to reinitiate growth. From a random insertion mutant library of Synechocystis sp. PCC 6803, a sll1242 mutant showing increased sensitivity to chill plus light was isolated. Mutant reconstruction and complementation with the wild-type gene confirmed the role of sll1242 in maintaining chill-light tolerance. At 15 degrees C, the autotrophic and mixotrophic growth of the mutant were both inhibited, paralleled by decreased photosynthetic activity. The expression of sll1242 was upregulated in Synechocystis sp. PCC 6803 after transfer from 30 to 15 degrees C at a photosynthetic photon flux density of 30 mu mol photons m(-2) S-1. sll1242, named ccr (cyanobacterial cold resistance gene)- 1, may be required for cold acclimation of cyanobacteria in light.

A low-cost CMOS programmable temperature

A novel uncalibrated CMOS programmable temperature switch with high temperature accuracy is presented. Its threshold temperature T-th can be programmed by adjusting the ratios of width and length of the transistors. The operating principles of the temperature switch circuit is theoretically explained. A floating gate neural MOS circuit is designed to compensate automatically the threshold temperature T-th variation that results form the process tolerance. The switch circuit is implemented in a standard 0.35 mu m CMOS process. The temperature switch can be programmed to perform the switch operation at 16 different threshold temperature T(th)s from 45-120 degrees C with a 5 degrees C increment. The measurement shows a good consistency in the threshold temperatures. The chip core area is 0.04 mm(2) and power consumption is 3.1 mu A at 3.3V power supply. The advantages of the temperature switch are low power consumption, the programmable threshold temperature and the controllable hysteresis.

Effects of temperature and delayed initial feeding on the survival and growth of Japanese flounder larvae

The effects of the timing of initial feeding (0, 1, 2 3 and 4 days after yolk exhaustion) and temperature (15, 18 and 21degrees C) on the point-of-no-return (PNR), survival and growth of laboratory-reared Japanese flounder Paralichthys olivaceus larvae were studied under controlled conditions. The larvae reached PNR on 7(.)7, 5(.)2 and 4(.)2 days-post-hatching (dph) at 15, 18 and 2 V C, respectively. At each temperature, larval growth did not differ significantly among the delayed initial feedings 1 day before PNR but decreased significantly in larvae first fed after that. In the treatments where initial feeding was equally delayed, larvae grew significantly faster at 18 and 21degrees C than at 15degrees C. The larvae survived apparently better at 15 and 18degrees C than at 21degrees C when initial feeding was equally delayed. At each temperature, survival of the larvae first fed before PNR did not differ noticeably, while delayed initial feeding after that apparently reduced their survival. These results indicated that there existed a negatively temperature-dependent PNR in the Japanese flounder larvae. Survival and growth of the larvae strongly depended on temperature as well as the timing of initial feeding. High temperature accelerated the yolk exhaustion and growth of the larvae and thus reduced their starvation tolerance and survival. To avoid potential starvation mortality and obtain good growth, the Japanese flounder larvae must establish successful initial feeding within 2 days after yolk exhaustion at 15degrees C and within 1 day at both 18 and 21degrees C. (C) 2005 The Fisheries Society of the British Isles.

Immune condition of Chlamys farreri in response to acute temperature challenge

The effects of acute temperature challenge on some immune parameters of haemocyte in Zhikong scallop, Chlamys farreri, recognised as a temperature sensitive bivalve species, were evaluated over a short period of time. Scallops were suddenly transferred from 17 degrees C to 11 degrees C, 23 degrees C and 28 degrees C for a period of 72 h. Total haemocyte count (THC), percentage of phagocytic haemocytes, reactive oxygen species (ROS) production, acid phosphatase (ACP) and superoxide dismutase (SOD) activities (in both haemocyte lysate and cell-free haemolymph) were chosen as biomarkers of temperature stress. Results demonstrated that the percentage of phagocytic haemocytes and ACP activity in cell-free haemolymph of scallops challenged at 28 degrees C for 72 h significantly decreased. By contrast, reactive oxygen species production by haemocytes increased when compared to the initial values. It is concluded that haemocyte activities of C. farreri appear to be compromised when scallops were transferred from 17 degrees C to 28 degrees C. Meanwhile, no obvious negative effect of acute temperature stress was detected on haemocyte activities of C. farreri challenged at 11 degrees C, which highlighted the high tolerance of scallops to acute decrease of seawater temperatures. (C) 2007 Elsevier B.V. All rights reserved.