Effects of Glyphosate on Isolated Maize Mitochondria

The effects of the herbicide glyphosate (K⁺ salt) on isolatedmaize mitochondria have been investigated. Protein synthesis,oxygen uptake (state 3 and state 4 respiration) and passiveswelling were inhibited at concentrations in the 10^–6–10^–2M range. No decrease of the respiratory control ratio (RCR)or stimulation of ATPase activity by glyphosate (K+ salt) wereobserved. It is concluded that the previously reported decreaseof the RCR and ATPase stimulation by glyphosate (isopropylaminesalt) were probably due to the isopropylamine moiety or to impuritiesof the technical product. Key words: Glyphosate, Herbicide action, Maize, Mitochondria     

Heat Stress in Wheat during Reproductive and Grain-Filling Phases

Ambient temperatures have increased since the beginning of the century and are predicted to continue rising under climate change. Such increases in temperature can cause heat stress: a severe threat to wheat production in many countries, particularly when it occurs during reproductive and grain-filling phases. Heat stress reduces plant photosynthetic capacity through metabolic limitations and oxidative damage to chloroplasts, with concomitant reductions in dry matter accumulation and grain yield. Genotypes expressing heat shock proteins are better able to withstand heat stress as they protect proteins from heat-induced damage. Heat tolerance can be improved by selecting and developing wheat genotypes with heat resistance. Wheat pre-breeding and breeding may be based on secondary traits like membrane stability, photosynthetic rate and grain weight under heat stress. Nonetheless, improvement in grain yield under heat stress implies selecting genotypes for grain size and rate of grain filling. Integrating physiological and biotechnological tools with conventional breeding techniques will help to develop wheat varieties with better grain yield under heat stress during reproductive and grain-filling phases. This review discusses the impact of heat stress during reproductive and grain-filling stages of wheat on grain yield and suggests strategies to improve heat stress tolerance in wheat.     

Influence of Temperature Stress on in Vitro Fertilization and Heat Shock Protein Synthesis in Maize (Zea mays L.) Reproductive Tissues

This study was conducted to investigate the response of maize (Zea mays) male and female mature reproductive tissues to temperature stress. We have tested the fertilization abilities of the stressed spikelets and pollen using in vitro pollination-fertilization to determine their respective tolerance to stress. The synthesis of heat shock proteins (HSPs) was also analyzed in male and female tissues using electrophoresis of ³⁵S-labeled proteins and fluorography, to establish a relationship between the physiological and molecular responses. Pollen, spikelets, and pollinated spikelets were exposed to selected temperatures (4, 28, 32, 36, or 40°C) and tested using an in vitro fertilization system. The fertilization rate is highly reduced when pollinated spikelets are exposed to temperatures over 36°C. When pollen and spikelets are exposed separately to temperature stress, the female tissues appear resistant to 4 hours of cold stress (4°C) or heat stress (40°C). Under heat shock conditions, the synthesis of a typical set of HSPs is induced in the female tissues. In contrast, the mature pollen is sensitive to heat stress and is responsible for the failure of fertilization at high temperatures. At the molecular level, no heat shock response is detected in the mature pollen.     

Dose-Dependent Adverse Effects of Salinomycin on Male Reproductive Organs and Fertility in Mice

Salinomycin is used as an antibiotic in animal husbandry. Its implication in cancer therapy has recently been proposed. Present study evaluated the toxic effects of Salinomycin on male reproductive system of mice. Doses of 1, 3 or 5 mg/kg of Salinomycin were administered daily for 28 days. Half of the mice were sacrificed after 24 h of the last treatment and other half were sacrificed 28 days after withdrawal of treatment. Effects of SAL on body and reproductive organ weights were studied. Histoarchitecture of testis and epididymis was evaluated along with ultrastructural changes in Leydig cells. Serum and testicular testosterone and luteinizing hormones were estimated. Superoxide dismutase, reduced glutathione, lipid peroxidation, catalase and lactate dehydrogenase activities were measured. Spermatozoa count, morphology, motility and fertility were evaluated. Expression patterns of steroidogenic acute regulatory protein (StAR) and cytochrome P450 side chain cleavage proteins (CYP11A1) were assessed by Western blotting. Salinomycin treatment was lethal to few mice and retarded body growth in others with decreased weight of testes and seminal vesicles in a dose dependent manner. Seminiferous tubules in testes were disrupted and the epithelium of epididymis showed frequent occurrence of vacuolization and necrosis. Leydig cells showed hypertrophied cytoplasm with shrunken nuclei, condensed mitochondria, proliferated endoplasmic reticulum and increased number of lipid droplets. Salinomycin decreased motility and spermatozoa count with increased number of abnormal spermatozoa leading to infertility. The testosterone and luteinizing hormone levels were decreased in testis but increased in serum at higher doses. Depletion of superoxide dismutase and reduced glutathione with increased lipid peroxidation in both testis and epididymis indicated generation of oxidative stress. Suppressed expression of StAR and CYP11A1 proteins indicates inhibition of steroidogenesis. Spermatogenesis was however observed in testis 28 days after Salinomycin withdrawal. The results indicate reversible dose-dependent adverse effects of Salinomycin on male reproductive system of mice.     

Protein Synthesis in Maize during Anaerobic and Heat Stress

Protein accumulation and protein synthesis were investigated during anaerobic stress and heat shock in maize seedlings (Zea mays L.). Antibodies against alcohol dehydrogenase (ADH) and cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) were used to investigate the expression of the genes encoding these proteins during stress treatment. ADH1 protein accumulation is shown to increase about 10-fold in the root after 24 hours of anaerobic treatment. The Gpc gene products are separable into two size classes: the slow mobility GAPC1 and GAPC2 (GAPC1/2), and the faster GAPC3 and GAPC4 (GAPC3/4). The GAPC1/2 antigen did not increase at all, whereas the GAPC3/4 antigen increased less than fourfold. The proteins synthesized in the root during aerobic and anaerobic conditions were compared, and GAPC3/4 was identified as an anaerobic polypeptide. In vitro translations were used to estimate the levels of different mRNAs in roots following anaerobiosis, recovery from anaerobiosis, and heat shock. This was compared with the in vivo protein synthesis rates in roots labeled under identical conditions. In vivo labeling indicates that GAPC and ADH are not heat shock proteins. Although both GAPC3/4- and ADH1-translatable mRNA levels increase about 10-fold during anaerobiosis, in vivo labeling of these proteins (relative to total protein synthesis) is further enhanced, leading to a selective translation effect for ADH1 of threefold, and for GAPC3/4 of sixfold. In contrast, anoxia causes no change in GAPC1/2-translatable mRNA levels or in vivo labeling. As an additional comparison, β-glucosidase mRNA levels are found to be constant during anoxia, but in vivo synthesis decreases.     

Effects of Drought Stress on the Photosynthesis in Maize

To clarify how the components of the entire photosynthetic electron transport chain in response to drought stress in maize. The activities of photosystem II (PSII), photosystem I (PSI), and the electron transport chain between PSII and PSI of maize were investigated by prompt fluorescence (PF), delayed fluorescence (DF) and 820 nm modulated reflection (MR). Maize (Zea mays L.) plants were subjected to different levels of soil water availability including control, moderate and severe drought stress. A significant decrease in ?E₀, Ψ₀ and PI_ABS was found in maize treated with moderate drought stress. A significant increase in ABS/RC was observed, but there were no significant change in the fast MR phase and the amplitude of DF under moderate drought stress compared to the control. Under severe drought stress, the exchange capacity between Q_A to Q_B, reoxidation capacity of plastoquinol, and the oxidation and re-reduction rates of PC and P₇₀₀ all decreased. These results demonstrated that moderate drought stress reduced the photochemical activity of PSII from Q_A to PQH₂, while the photochemical activity of PSI was unscathed. However, severe drought stress inhibited the entire electron transport chain from the donor side of PSII to PSI-end electron acceptors. In addition, the photochemical activity of PSII is more sensitive to drought stress than PSI.     

GABA对热应激仔鸡的影响

将一周龄的“882”肉仔鸡 ,随机分为 2组。让对照组仔鸡饮用蒸馏水 ,让试验组饮用 0 0 5 %的氨酪酸 (GABA)蒸馏水。 2组每天置于 32℃的箱中热处理 1 5h ,试验 4周。结果表明GABA对热应激肉仔鸡有一定的影响 :试验组仔鸡的呼吸频率极显著低于对照组 (P <0 0 1) ;红细胞数显著高于对照组 (P <0 0 5 ) ;料重比极显著低于对照组 (P <0 0 1) ,仔鸡增重是对照组鸡的 117 86 % (P <0 0 5 )。     

Partitioning of [14C]sucrose and Acid Invertase Activity in Reproductive Organs of Pepper Plants in Relation to Their Abscission Under Heat Stress

The effect of heat stress on processes related to carbohydratepartitioning was investigated in young bell pepper (Capsicumannum L. cv. Maor) plants in relation to abscission of theirreproductive organs at different stages of development. None of the reproductive organs abscised after 5 d in a normalday/night temperature regime (25/18 °C). With a temperatureregime of 35 °C day, 25 °C night, abscission occurredin only a small portion of the flower buds and none of the flowersand fruitlets. However, when temperatures in the day and nightwere reversed (25/35 °C, day/night) all the buds and someof the flowers abscised during that time period. The young fruitat the first node did not abscise under any temperature regime.The abscission rate of the flower buds was reduced under heatstress if the developing fruit at the first node had been removed. High temperature during either the light or dark periods reducedthe export of [¹⁴C]sucrose from the source leaf (fed for 48h with [¹⁴C]sucrose). Both heat stress and fruit presence reduced the relative amountof [¹⁴C]sucrose which was exported to the flower buds, flowersand roots. Likewise, these treatments reduced the concentrationof reducing sugars in the reproductive organs. Concomitantly,the heat stress and fruit presence on the first node reducedthe activity of soluble acid invertase in the flower buds andthe roots, but not in young leaves. Overall, the results show that heat stress causes alternationin sucrose distribution in the plant, but may also have specificeffects on metabolic activities related to sucrose import andutilization in flower buds and flowers which in turn may enhancetheir abscission. Bell pepper, (Capsicum annuum L. cv. Maor), abscission, acid invertase, heat stress, reproductive organs, sink leaves     

Partitioning of [14C]sucrose and Acid Invertase Activity in Reproductive Organs of Pepper Plants in Relation to Their Abscission Under Heat Stress

The effect of heat stress on processes related to carbohydratepartitioning was investigated in young bell pepper (Capsicumannum L. cv. Maor) plants in relation to abscission of theirreproductive organs at different stages of development. None of the reproductive organs abscised after 5 d in a normalday/night temperature regime (25/18°C). With a temperatureregime of 35°C day, 25°C night, abscission occurredin only a small portion of the flower buds and none of the flowersand fruitlets. However, when temperatures in the day and nightwere reversed (25/35°C, day/night) all the buds and someof the flowers abscised during that time period. The young fruitat the first node did not abscise under any temperature regime.The abscission rate of the flower buds was reduced under heatstress if the developing fruit at the first node had been removed. High temperature during either the light or dark periods reducedthe export of [¹⁴C]sucrose from the source leaf (fed for 48h with [¹⁴C]sucrose). Both heat stress and fruit presence reduced the relative amountof [¹⁴C]sucrose which was exported to the flower buds, flowersand roots. Likewise, these treatments reduced the concentrationof reducing sugars in the reproductive organs. Concomitantly,the heat stress and fruit presence on the first node reducedthe activity of soluble acid invertase in the flower buds andthe roots, but not in young leaves. Overall, the results show that heat stress causes alternationin sucrose distribution in the plant, but may also have specificeffects on metabolic activities related to sucrose import andutilization in flower buds and flowers which in turn may enhancetheir abscission. Bell pepper, (Capsicum annuum L. cv. Maor), abscission, acidinvertase, heat stress, reproductive organs, sink leaves. Bell pepper, (Capsicum annuum L. cv. Maor), abscission, acid invertase, heat stress, reproductive organs, sink leaves.     

Effects of Heat Stress on Gut Microbiome in Rats

Gut microbiome, as the largest and most important micro-ecosystem, plays a critical role in health. The purpose of this study was to evaluate whether heat stress modulates the composition and diversity of the gut microbiome in rats. The heat stress model was prepared in rats with the heating temperature maintained at 35–38°C. Cecum contents were collected after heat stress for 3 h and days 1, 3 and 7. Total DNA was extracted for 16 S rRNA sequencing and analysis of intestinal microbiome composition and diversity. The study showed that the composition of the intestinal microbiome of heat stress group was changed. And the heat stress modulated key phylotypes of gut microbiota at the level of phylum and genus. In particular, the genus of Lactobacillus and Bacteroides were significantly reduced, whereas the Oscillospira and Clostridium were increased by heat stress. Meanwhile, the rats under the heat stress encountered the change in carbohydrate metabolism, amino acid metabolism, and membrane transport to defense against stress. Taken together, the composition and structure of gut microbiome were affected by heat stress and some key phylotypes were also significantly altered. We conclude that the heat stress could impact multiple biological functions, via altering the gut microbiome.     

共生有生殖器官的Anomozamites的新发现

海房沟异羽叶的新联合(Anomozamites haifanggouensis (Kimura et al.) comb. nov.)是辽西和内蒙古东部中侏罗统海房沟组一种特有的本内苏铁类植物.仅发现一块标本(正、反面印痕).标本上保存3枚营养羽叶,它们同几个苞片状的小叶和一些小孢子叶联合在一起,但球果的雌蕊群部分未被保存.标本被收集于内蒙古东部的宁城县山头乡道虎村附近,产于中侏罗统海房沟组.以往在辽西葫芦岛市的南票和白马石乡上三角城等地的同一层位中也曾发现过很多分散保存的苞片状小叶和相似的小孢子叶.它们最初被潘广(1983)认为是一种双子叶的半被子植物(Cycadicotis),并将小孢子叶视为"具皱纹的雌性种囊".后来,又经Kimura等(1994)详细研究,因未找到任何与被子植物有关的证据,将它们归入一个分类位置不明的形态属Pankuangia,并被描述在P. haifanggouensis种名之下.研究结果表明,本文中被研究的标本是同本内苏铁类的Anomozamites异羽叶相连,从而为这些分散保存的生殖器官的确切分类位置的确定提供了有力的证据.     

共生有生殖器官的Anomozamites的新发现

摘要：海房沟异羽叶的新联合(Anomozamites haifanggouensis(Kimura et al.)comb．nov．)是辽西和内蒙古东部中侏罗统海房沟组一种特有的本内苏铁类植物。仅发现一块标本(正、反面印痕)。标本上保存3枚营养羽叶,它们同几个苞片状的小叶和一些小孢子叶联合在一起,但球果的雌蕊群部分未被保存。标本被收集于内蒙古东部的宁城县山头乡道虎村附近,产于中侏罗统海房沟组。以往在辽西葫芦岛市的南票和白马石乡上三角城等地的同一层位中也曾发现过很多分散保存的苞片状小叶和相似的小孢子叶。它们最初被潘广(1983)认为是一种双子叶的半被子植物(Cycadicotis),并将小孢子叶视为“具皱纹的雌性种囊”。后来,又经KJlnura等(1994)详细研究,因未找到任何与被子植物有关的证据,将它们归入一个分类位置不明的形态属Panlatangia,并被描述在P．haifanggouensis种名之下。研究结果表明,本文中被研究的标本是同本内苏铁类的Anomozamites异羽叶相连,从而为这些分散保存的生殖器官的确切分类位置的确定提供了有力的证据。     

Evolution of Reproductive Organs in Land Plants

LEAFY gene is the positive regulator of the MADS-box genes in flower primordia. The number of MADS-box genes presumably increased by gene duplications before the divergence of ferns and seed plants. Most MADS-box genes in ferns are expressed similarly in both vegetative and reproductive organs, while in gymnosperms, some MADS-box genes are specifically expressed in reproductive organs. This suggests that (1) the increase in the number of MADS-box genes and (2) the subsequent recruitment of some MADS-box genes as homeotic selector genes were important for the evolution of complex reproductive organs. The phylogenetic tree including both angiosperm and gymnosperm MADS-box genes indicates the loss of the A-function genes in the gymnosperm lineage, which is presumably related to the absence of perianths in extant gymnosperms. Comparison of expression patterns of orthologous MADS-box genes in angiosperms, Gnetales, and conifers supports the sister relationship of Gnetales and conifers over that of Gnetales and angiosperms predicted by phylogenetic trees based on amino acid and nucleotide sequences. Received 30 July 1999/ Accepted in revised form 9 September 1999     

Endocrine Effects of Heat Stress in Boars

The purpose of this study was to describe the temporal changes in peripheral plasma levels of testosterone and Cortisol in boars during and after heat stress. A total of 8 boars were utilized, 4 of them were exposed to 35°C, for 100 h in a climatic room, and 4 served as controls and were kept at 20 °C for 100 h in the climatic room. Blood samples were obtained via permanent vein catheters 3 times daily from 5 days before heat stress until 20 days after termination of heat stress. Testestorone levels were determined by radioimmunoassay and Cortisol by a competitive protein binding technique. For both hormones the pre-exposure levels were similar in both groups of boars. The control boars had significantly higher testosterone levels, while being in the climatic room, than during any other period. The experimental boars had slightly increased testosterone levels during the first day of heat stress and thereafter continuously decreased levels. In the control boars the testosterone levels returned to pre-exposure levels immediately after removal from the climatic room, whereas in the experimental boars the testosterone levels were dramatically increased during the first 5 days after exposure. The differences in Cortisol levels, between the 2 groups of boars were restricted to the period spent in the climatic room. During this period the experimental boars had significantly higher Cortisol levels.     

Effect of Heat Stress on Photosynthetic Characteristics of Different Green Organs of Winter Wheat During Grain-filling Stage

Four winter wheat ( Triticum aestivum L.) varieties (“JD 8”, “Jing 411”,“Centurk” and “Tam 202”) were used to study the effect of heat stress on photosynthetic characteristics of flag leaf blade, flag leaf sheath, peduncle, glume, lemma and awn during grain-filling stage. The results showed that heat acclimation during grain-filling stage increased thermotolerance of wheat with significant differences among different green organs. During heat stress, the decreases of the efficiency of primary light energy conversion ( Fv/Fm ) of PS and pigment (chlorophyll and carotenoid) content were much slower in peduncle, flag leaf sheath and glume than in flag leaf blade, lemma and awn; and the percentage of decrease in net photosynthetic rate ( Pn ) of ear was lower than that of the flag leaf blade. The measured photosynthetic parameters ( Fv/Fm , Pn and pigment content) of “JD 8”, a relatively heat tolerant variety, declined more slowly than those of the other three varieties during the whole heat stress period.      

Sex Pheromones of C. elegans Males Prime the Female Reproductive System and Ameliorate the Effects of Heat Stress

Pheromones are secreted molecules that mediate animal communications. These olfactory signals can have substantial effects on physiology and likely play important roles in organismal survival in natural habitats. Here we show that a blend of two ascaroside pheromones produced by C. elegans males primes the female reproductive system in part by improving sperm guidance toward oocytes. Worms have different physiological responses to different ratios of the same two molecules, revealing an efficient mechanism for increasing coding potential of a limited repertoire of molecular signals. The endogenous function of the male sex pheromones has an important side benefit. It substantially ameliorates the detrimental effects of prolonged heat stress on hermaphrodite reproduction because it increases the effectiveness with which surviving gametes are used following stress. Hermaphroditic species are expected to lose female-specific traits in the course of evolution. Our results suggest that some of these traits could have serendipitous utility due to their ability to counter the effects of stress. We propose that this is a general mechanism by which some mating-related functions could be retained in hermaphroditic species, despite their expected decay.     

灌浆期热胁迫对小麦不同绿色器官光合性能的影响

以4个冬小麦（Triticum aestivem L.）品种（“JD8”、“Jing411”、“Centurk”和“Tam202”）为材料,研究灌浆期热胁迫对旗叶叶片、旗叶鞘、穗下节间、护颖、外疑和芒的光合性能和籽粒产量的影响。结果表明：灌浆期对泪科进行热锻炼也能增加其耐热性且各绿色器官间耐热性差异显。耐热性较强的器官为穗下节间、旗叶鞘和护颖;热敏感器官为旗叶叶片、外颖和芒。热胁迫条件下,穗下节间1旗叶鞘和护颖的细胞膜热稳定性强,光系统Ⅱ原初光能转换效率（Fv/Fm）下降速率以及叶绿素和类胡萝卜素降解速率均低于旗叶叶片、外颖和瓦,穗的净光合速率下降幅度小于旗叶。热胁迫过程中,相对耐热品种“JD8”各器官上述光合参数的下降速度均显低于其他3个热敏感品种。     

Effects of Heat Stress on Carbon Transport from Tomato Leaves

Export of radioactive carbon from two cultivars of tomato, (Lycopersiconesculentum Mill.) leaves was inhibited in response to heat stress.Increasing temperatures resulted in a marked decrease in leafstarch levels. The depletion of starch concentration in theleaves was primarily due to hydrolysis and an inhibition ofstarch formation. At high temperatures, starch hydrolysis wasinhibited in Roma VF, a heat sensitive cultivar, while Saladette,a heat tolerant cultivar was not similarly affected. Calloseformation was found on phloem sieve tube plates of leaf petiolesexposed to 72 h of high temperatures. More sieve tube plateswere covered with a thicker callose layer in Roma VF than inSaladette. Lycopersicon esculentum (Mill.), tomato, carbon translocation, starch hydrolysis, callose, heat stress