水杨酸对高温胁迫下铁皮石斛幼苗耐热性的影响

为研究不同浓度水杨酸对铁皮石斛幼苗耐热性的诱导效应,以移栽半年的铁皮石斛幼苗为实验材料,对不同浓度水杨酸诱导高温胁迫下铁皮石斛幼苗的耐热性进行外观评价及叶绿素、可溶性蛋白质、可溶性糖、丙二醛(MDA)、游离脯氨酸(Pro)含量以及超氧化物歧化酶(SOD)、过氧化酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性的动态测定,观察其动态变化趋势并筛选最佳施用浓度.结果显示:在高温胁迫环境下,随着胁迫时间的延长,不同浓度SA处理均能有效缓解高温对铁皮石斛植株伤害;1.5～2.0 mmol·L1SA处理使铁皮石斛叶片中SOD、POD活性显著提高,0.5～1.5 mmol·L-1 SA处理叶片中CAT、APX活性显著提高;1.5～2.0 mmol·L-1SA处理可显著促进叶片Pro、可溶性糖和可溶性蛋白的积累,有效抑制MDA含量的增加,且不同浓度处理之间差异显著.研究表明,适宜浓度水杨酸处理能提高铁皮石斛幼苗的耐热性,并以1.5 mmol·L-1浓度处理效果最好.     

低温胁迫下玉米幼苗的几种生理生化指标的变化

胚芽期和三叶期的玉米自交系‘齐319’幼苗经0、2、4、6℃冷处理后,测定过氧化物酶（POD）、过氧化氢酶（CAT）和超氧化物歧化酶（soD）活性以及可溶性蛋白和丙二醛（MDA）含量的结果表明：POD、CAT、SOD活性以及MDA和蛋白质含量均增加,0、2℃下胚芽期幼苗的抗寒性比三叶期的高,4和6℃下三叶期幼苗的抗寒能力更强;无论是胚芽期还是三叶期,温度越低,幼苗受冷伤害越大。     

添加外源锌对大杯香菇子实体细胞保护酶活性的影响

摘要：【目的】本实验研究了添加外源锌（Zn）对大杯香菇子实体保护酶活性的影响。【方法】以硫酸锌为外源锌,添加到培养料中,制成0、10、20、30、40、50 mg/kg 6个浓度。采用分光光度法测定大杯香菇子实体超氧化物岐化酶（SOD）活性、过氧化物酶（POD）活性、多酚氧化酶（PPO）活性、丙二醛（MDA）含量和可溶性蛋白含量,采用高锰酸钾滴定法过氧化氢酶（CAT）活性。【结果】添加外源 Zn浓度为30 mg/kg处理大杯香菇子实体内可溶性蛋白含量、SOD、POD和CAT活性极显著提高（P＜0.01）,PPO活性极显著减少（P＜0.01）,而MDA含量显著下降（P＜0.05）。随着Zn水平进一步升高,可溶性蛋白含量、SOD、POD和CAT活性呈下降趋势,而MDA含量极显著和显著上升（P＜0.01和P＜0.05）。【结论】高用量的Zn浓度能使大杯香菇子实体中的MDA含量上升,SOD、POD、CAT活性均下降,对保护酶系统有破坏作用,促进自由基的积累,从而导致膜脂过氧化作用的加剧。适宜Zn浓度能提高保护酶的活性,从而抑制了大杯香菇子实体中细胞膜脂过氧化水平,减轻膜伤害。     

壳聚糖对蝴蝶兰幼苗耐热性的诱导作用

为了评价壳聚糖对蝴蝶兰幼苗耐热性的诱导效应,分别采用0(以无壳聚糖为对照)、25、50、100、200和400 mg·L~(-1)壳聚糖溶液处理蝴蝶兰幼苗,并置于42℃下胁迫3 d,测定了蝴蝶兰幼苗的生理指标变化。结果表明:当壳聚糖浓度由25 mg·L~(-1)增大到100mg·L~(-1)时,蝴蝶兰幼苗叶片的SOD、POD、CAT活性、脯氨酸、可溶性糖、叶绿素和类胡萝卜素含量不断增加,而质膜透性和丙二醛含量不断下降,但可溶性蛋白含量没有显著变化;特别是在100 mg·L~(-1)时,SOD、POD和CAT活性、脯氨酸、可溶性糖、叶绿素和类胡萝卜素含量增加到最大值且极显著高于对照,而质膜透性和丙二醛含量下降至最小值且极显著低于对照,蝴蝶兰幼苗遭受了轻微的高温伤害;随着壳聚糖浓度由200 mg·L~(-1)增大至400mg·L~(-1),SOD、POD和CAT活性、脯氨酸、可溶性蛋白、可溶性糖、叶绿素和类胡萝卜素含量极显著下降,而质膜透性和丙二醛含量极显著上升,蝴蝶兰幼苗的受害趋于加重;由此可见,100 mg·L~(-1)壳聚糖处理能显著提高蝴蝶兰幼苗的耐热性。     

富营养化水体灌溉对高羊茅生理生态特征的影响

通过采用两处不同浓度富营养化水体对高羊茅进行灌溉,研究了高羊茅生理生态特征响应。结果表明：稀释后的富营养化水体能显著促进高羊茅根系生长,当稀释浓度大于50%时,不利于株高的增长。富营养化水体的各个浓度对高羊茅叶绿素各项指标无显著影响。各富营养化水体稀释后灌溉高羊茅,对其游离脯氨酸、可溶性糖、丙二醛（MDA）含量、超氧化物歧化酶（SOD）活性的影响与对照相比差异不显著,外环水体能显著促进高羊茅过氧化物酶（POD）活性增加,稀释浓度为75%能使高羊茅过氧化氢酶（CAT）活性显著增加。综上分析表明,富营养化水体稀释后灌溉高羊茅是可行的,且生活区污水更适合用于高羊茅的灌溉。     

低温胁迫下棉花幼苗对外源水杨酸的生理响应

以棉花幼苗为试材,通过叶面喷施不同浓度水杨酸的处理方法,研究外源水杨酸对低温胁迫下棉花幼苗的缓解效应。结果表明,0.6~0.8 mmol＆#183;L-1水杨酸预处理可以显著降低棉花幼苗叶片相对电导率（REC）和丙二醛（MDA）的积累量,从而缓解低温对质膜的过氧化伤害,并通过提高超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）的活性和可溶性糖、可溶性蛋白、脯氨酸等渗透调节物质的含量来适应低温环境。     

外源GSH对盐胁迫下番茄幼苗生长及抗逆生理指标的影响

采用营养液栽培法,研究外源谷胱甘肽(GSH)对NaCl胁迫下番茄幼苗生长、根系活力、电解质渗透率和丙二醛(MDA)、脯氨酸(Pro)、可溶性糖含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的影响,为利用外源物质减轻盐胁迫伤害提供理论依据。结果显示:(1)NaCl胁迫显著抑制了番茄幼苗的生长、根系活力和SOD、POD、CAT活性,提高了电解质渗透率及MDA、Pro、可溶性糖含量;(2)外源喷施GSH能够诱导NaCl胁迫下番茄幼苗叶片抗氧化酶SOD、POD、CAT活性上调,电解质渗透率及MDA含量下降,Pro和可溶性糖含量恢复至对照水平;(3)外源喷施还原型谷胱甘肽抑制剂(BSO)使NaCl胁迫下番茄幼苗的根系活力以及抗氧化酶SOD、POD、CAT活性下降,脯氨酸含量提高;(4)喷施GSH可诱导BSO和NaCl共处理番茄植株的根系活力、SOD、POD、CAT活性提高,MDA和Pro含量降低。研究表明,外源GSH可通过提高促进盐胁迫下番茄幼苗植株渗透调节能力及清除活性氧的酶促系统的防御能力、降低细胞膜脂过氧化程度、保护膜结构的完整性,从而有效缓解NaCl胁迫对番茄幼苗生长的抑制,提高其耐盐性。     

水淹对铺地黍部分生理指标的影响

研究了水淹对铺地黍幼苗的丙二醛、可溶性糖和可溶性蛋白质含量,3种抗氧化保护酶(SOD、CAT和POD)活性等生理指标的影响.结果显示:水淹胁迫下,铺地黍幼苗的丙二醛含量缓慢升高,可溶性糖含量先升高后下降,蛋白质含量逐渐下降,超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性先上升后下降,而过氧化物酶(POD)活性则持续...     

骆驼蓬提取物浸种对小麦幼苗生长及抗氧化酶活性的影响

以不同浓度骆驼蓬提取液浸种处理小麦。研究对幼苗生长及抗氧化酶活性的影响。结果表明,骆驼蓬提取液浸种后小麦幼苗的根长、株高和干重增加,根冠比增大;幼苗根系活力增强,根系超氧化物歧化酶（SOD）活性提高,过氧化氢酶（CAT）活性先升后降,过氧化物酶（POD）活性下降,过氧化物酶同工酶表达受抑;叶片叶绿素和可溶性蛋白质含量增加,叶片SOD、POD活性提高,过氧化物酶同工酶表达增强,CAT活性降低。根系和叶片丙二醛（MDA）含量下降。     

离子注入对多伞阿魏幼苗生理生化指标的影响

目的：研究低能氮离子注入对多伞阿魏幼苗生理生化指标的影响。方法：以能量30keV、不同剂量N＋离子注入多伞阿魏种子，研究分析不同剂量组多伞阿魏幼苗超氧化物歧化酶（SoD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性变化，以及游离脯氨酸和可溶性蛋白质含量变化。结果：随离子注入剂量增大SOD活性增加、POD和CAT活性逐渐升高，剂量过大时，SOD、POD和CAT活性下降；游离脯氨酸含量逐渐降低，但在6×10^16N＋／c秆剂量时含量升高；可溶性蛋白质含量先升高再降低，6×10^16N＋，c秆剂量时为最高值。结论：适当剂量N＋离子注入可激活保护酶酶活性并促使脯氨酸和可溶性蛋白含量升高。     

Induced thermotolerance under nonisothermal treatments of a heat sensitive and a resistant strain of Staphylococcus aureus in media of different pH

AIMS: The aim was to assess the induced thermotolerance under nonisothermal treatments of two strains of Staphylococcus aureus in media of different pH. METHODS AND RESULTS: Staphylococcus aureus ATCC 25923 was more heat resistant than S. aureus ATCC 13565 at any pH investigated under isothermal conditions. At pH 7.4, the D58 value of the resistant strain was approx. 30 times greater. Both strains showed a higher heat resistance at pH 4.0 than at pH 7.4. In contrast, under nonisothermal treatments (0.5-2 degrees C min(-1)), both strains were more heat resistant when treated at pH 7.4 than at pH 4.0 due to heat adaptation at the higher pH. At the slowest heating up rate tested at pH 7.4, the initially heat-sensitive strain nearly reached the thermotolerance of the heat-resistant strain. CONCLUSIONS: The induced thermotolerance under nonisothermal treatments depended on the treatment medium pH and the microbial strain tested. The induced thermotolerance in a sensitive strain can be greater than in a heat-resistant strain, showing similar resistance under nonisothermal conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: This work shows data of interest about mechanisms of microbial resistance and adaptation to heat. Moreover, it contributes to the development of more adequate combined processes for food preservation.     

Day-night variation of thermoregulatory responses to intraperitoneal electric heating in rats

1. 1.Hypothalamic temperature (T_hy), nonevaporative heat loss (R + C + K), evaporative heat loss (E), thermal conductance (k), metabolic heat production (M) and heat storage (S) of rats were simultaneously measured by direct and indirect calorimetry during internal heat loading (2 W per rat) with an intraperitoneal electric heater.

2. 2.The tests were made twice a day; once during the day (1000–1200 h) and once at night (2200–2400 h) at an ambient temperature of 24°C.

3. 3.The resting values of T_hy, colonic temperature, (R + C + K), E, M and heart rate, and the T_hy threshold for tail skin vasodilation (T_th) during internal heat load were significantly higher at night than during the day.

4. 4.The slopes showing the relationshiop between (R + C + K), k or M and T_hy were significantly steeper during the day than at night after T_hy exceeded T_th.

5. 5.The slopes showing the relationship between E or S and T_hy were not different during the day and at night.

6. 6.These results indicate that the responses of nonevaporative heat loss and heat production to internal heat load vary with the time of day in rats.

Thermotolerance in Fungi: The Role of Heat Shock Proteins and Trehalose

The parallel synthesis of heat shock proteins and trehalose in response to heat shock did not allow the role of these compounds in the acquisition of thermotolerance by fungal cells to be established for a long time. This review analyses experimental data obtained with the use of mutant fungal strains and shows differences in the thermoprotective functions of trehalose and heat shock proteins in relation to cell membranes and macromolecules. The main emphasis has been placed on data demonstrating the thermoprotective role of trehalose in fungi, the present-day understanding of its biological functions, and mechanisms of trehalose interaction with subcellular structures and cell macromolecules.__________Translated from Mikrobiologiya, Vol. 74, No. 3, 2005, pp. 293–304. p ]Original Russian Text Copyright © 2005 by Tereshina.     

植物耐热性及热激信号转导机制研究进展

随着温室效应的加剧,全球气候变暖已经成为现代农业生产体系所面临的严峻挑战．高温灾害性气候是影响作物产量的一种主要的非生物胁迫．因此,对于农作物生产而言,研究植物耐热信号转导机制不仅有重要的科学意义,而且有现实的紧迫性．最近几年,在阐明植物耐热信号转导机制的研究方面取得了很多重要的进展,这些进展涵盖植物高温胁迫的感受机制、热激转录因子和热激蛋白的表达调控、热激转录因子结合蛋白参与耐热性调控的分子机制等几个主要的方面．热胁迫影响细胞膜系统、RNA、蛋白质的稳定性,同时改变酶的活性和细胞骨架系统．当热胁迫来临时,植物的转录组会发生显著变化,所涉及的基因大约占基因组的2％．这些高温胁迫响应基因构成了热激响应网络,是植物抵御热胁迫的第一道防线．植物的耐热性分为基础耐热性和获得性耐热性．基础耐热性是植物固有的耐热性．获得性耐热性是温和的热驯化诱导的耐热性．获得性耐热性状的形成反映了植物在自然生长环境下适应高温胁迫的生理机制．     

Isolation of yeasts from palm tissues damaged by the red palm weevil and their possible effect on the weevil overwintering

Rhynchophorus ferrugineus is a tropical pest of palms that has recently invaded Japan, where winter temperatures fall below 0°C. Because activities of the weevil at temperatures <13°C are extremely limited, it appears difficult for them to overwinter in Japan. However, the temperature of palm tissues damaged by this weevil has been observed to be higher than air temperature. Here, we looked for the cause of this temperature increase. First, we measured the temperature of damaged palm tissues and showed it to be between 30°C and 40°C, even in winter. Next, we isolated yeasts from the body of weevils and infested palm tissues and obtained 36 yeast strains, mostly Candida tropicalis and C. ethanolica. Then, we analyzed the soluble sugar composition in palm tissues and found that it included glucose, sucrose, and fructose. Because at least C. tropicalis can ferment some of these sugars, the temperature increase may be attributed to fermentation of microbes, including yeasts.     

A Review of Thermotherapy to Free Plant Materials from Pathogens,Especially Seeds from Bacteria

Treating planting materials with heat is a one-century-old method of disease control that has proved to be efficient against various pathogenic microorganisms. Thermotherapy, simple in principle, consists in heat treatment of plant parts at temperature/time regimes that kill the conserved pathogen and that are only slightly injurious to the host. Heat is applied mainly by water, air, or vapor.

A large variety of plant parts can be heat treated: Whole tree, scions, vitroplants, seedlings, stalks, cuttings, sprouts, cut flowers, seeds, bulbs, tubers, corms, or fruit and vegetables in storage. The target pathogenic microorganisms are mainly fungi, viruses, and bacteria. Many studies show the success of reducing diseases by heat. Thermotherapy also is the main means, associated with meristem and tip culture, of producing virus-free explants from infected mother-plants.

Most bacterial diseases of annual plants are seed-borne. Seed-transmission provides numerous foci of primary infection in the field and only a relatively small amount of infested seeds is sufficient to promote serious disease outbreaks. To disinfect seeds, authors mainly use hot water and hot air treatments. Satisfactory control has been obtained for several bacterial diseases (on tomato, tobacco, rice, barley, cucumber, Crucifers, pumpkin, guar, and cotton), mostly caused by the genera Xanthomonas and Pseudomonas. Thermotherapy is more difficult to use with large seeds of legumes, such as pea, bean, or soybean, because a significant decrease of germination is often obtained before the bacteria have been totally killed. The success of thermotherapy may be improved by combination with chemicals at the seed stage, by sprays during plant growth, or by replacing water with nonaqueous fluids.

When no efficient chemicals are known to control a disease, treating seeds by heat may be of great interest. However, the method requires studies to determine the most appropriate kind of heat for a particular plant part, and the optimal combination of time and temperature of exposure to use for the best efficiency with the least damage to the host.     

Small heat shock proteins and adaptation of various Drosophila species to hyperthermia

The dynamics and the level of accumulation of small heat shock proteins (sHSP group 21–27) after a heat exposure were studied in three Drosophila species differing in thermotolerance. The southern species Drosophila virilis, having the highest thermotolerance, surpassed thermosensitive D. lummei and D. melanogaster in the level of sHSPs throughout the temperature range tested. The results suggest an important role of sHSPs in the molecular mechanisms of adaptation to adverse environmental conditions, particularly to hyperthermia.