Expression analysis and functional characterization of a cold-responsive gene COR15A from Arabidopsis thaliana

The cold-responsive (COR) genes play an important role in cold acclimation of higher plants. Here, a tight correlation between chloroplast functionality and COR15A expression, and the functional characterization of Arabidopsis COR15A involved in salt/osmotic stress, were revealed. COR15A gene is light inducible and expressed in light-grown seedlings. The expression level of COR15A was reduced when chloroplasts were damaged by norflurazon treatment. By using several albino mutants, seca1, secy1, and tic20, all of which exhibited severe defects in both structure and function of chloroplast, it was shown that the accumulation of COR15A mRNA depends on chloroplast functionality. Real-time RT-PCR and GUS-staining assays demonstrated that COR15A was induced by salt/osmotic stress partially via ABA. Overexpression of COR15A in Arabidopsis resulted in the seedlings displaying hypersensitivity to salt/osmotic stress. All these results suggest that plant acquire the ability to fully express COR15A only after the development of functional chloroplasts, COR15A may be involved in response to salt/osmotic stress during early stages of plant development.     

Developmental changes in chromatin of skeletal muscle of rats: acetylation of chromosomal proteins and transcription

In vivo acetylation of chromosomal proteins and RNA synthesis were studied in the skeletal muscle of 3–30 day old developing rats. The levels of acetylated histones and nonhistone chromosomal (NHC) proteins are high at day 3 and decrease as development progresses. Spermine has no significant effect on acetylation. Incorporation of³H-Uridine into RNA of both nuclear and cytoplasmic fractions is also maximum at day 3 and plateaus by day 14. Nuclear RNA synthesis following acetylation of chromosomal proteins is greatly stimulated in all the ages studied, whereas that in cytoplasmic RNA occurs only in 3 day old rats. Such modifications during early development may bring about conformational and functional changes in the chromatin and contribute significantly to the process of terminal differentiation of skeletal muscle cells.     

Role of spermidine and spermine in alleviation of drought-induced oxidative stress and photosynthetic inhibition in Chinese dwarf cherry (Cerasus humilis) seedlings

To investigate the effect of exogenous Spermidine (Spd) and Spermine (Spm) on drought-induced damage to seedlings of Cerasus humili, relative water content (RWC), malondialdehyde content, relative electrolyte leakage, superoxide (O₂ ^?, SOD) generation rate, hydrogen peroxide (H₂O₂), endogenous polyamines (PAs), antioxidant enzymes [SOD and peroxidase (POD)] activities, PA-biosynthetic enzymes [arginine decarboxylase (ADC), ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC)] activities, as well as photosynthetic parameters, were measured in greenhouse cultured seedlings of C. humili. The results showed that either exogenous Spd or Spm (0.2 mM) significantly enhanced the level of RWC and prevented drought-induced lipid peroxidation. They also significantly enhanced photosynthetic capability and decreased O₂ ^? generation rate and H₂O₂ content. In addition, Spd and Spm helped to maintain SOD and POD activities in C. humili seedlings subjected to water stress, suggesting that they exerted a positive effect on antioxidant systems. The contents of endogenous free putrescine, Spd and Spm were increased to different extents in water-stressed C. humili seedlings. By the end of drought treatment (21 days) with exogenous Spd or Spm, the contents of free Spd increased by 30 and 38 %, respectively, and endogenous Spm increased by 41 and 26 %, respectively, compared with water-stressed plants. Furthermore, exogenous Spd or Spm enhanced the activities of ADC, ODC, and SAMDC. The pretreatment with Spd or Spm prevents oxidative damage induced by drought, and the protective effect of Spd was found to be greater than that of Spm.     

The HPLC profile of proteins of thermoprotection-acquired wheat (Triticum aestivum L.) seedlings

A pre-treatment of 40 °Cprovided thermoprotection to wheat seedlings against 43 °C, which was otherwise a lethal temperature. Due to temperature pretreatment, the rate of protein synthesis at 45 °C increased in both plumules and radicles. The HPLC profile of plumule and radicle proteins of thermoprotection-acquired seedlings was different from the plumules and radicles of non-treated seedlings.     

Relationships between circadian rhythm of chilling resistance and acclimation to chilling in cotton seedlings

Cotton (Gossypium hirsutum L. cv. Deltapine 50) seedlings grown under light-dark cycles of 12:12h at 35°C showed rhythmic daily changes in chilling resistance. Chilling treatment (5°C, 48h) started at the beginning or middle of the daily light period resulted in a substantial growth inhibition of the seedlings upon return to 35°C whereas when chilling was started at the beginning or middle of the dark period the subsequent growth of the seedlings was much less inhibited. This rhythm in chilling resistance persisted under continuous light for three 24-h periods, indicating that it is of an endogenous nature. Seedlings grown under continuous light from germination showed no daily changes in resistance, but a rhythm was initiated by introduction of a dark period of 6h or longer. In 24-h cycles with different light and dark periods, maximal resistance was reached just before the start of dark period. Seedlings grown at 35°C could be acclimated to chilling by exposure to low, non-damaging temperatures (25–15°C). A short-term (6h) exposure to 25°C started at the resistant phase resulted in a large increase in resistance during the following otherwise sensitive phase. The resistance induced by the low temperature matched or slightly exceeded the maximal resistance reached during the resistant phase of the daily rhythm of chilling. The low-temperature-induced resistance and the daily rhythmic increase in resistance were not additive, indicating a common mechanism for the two kinds of resistances. An adaptive advantage of a combination of a rapid temperature-induced acclimation and the daily rhythmic increase in resistance is suggested.     

Combined Effects of Lead and Acid Rain on Photosynthesis in Soybean Seedlings

To explore how lead (Pb) and acid rain simultaneously affect plants, the combined effects of Pb and acid rain on the chlorophyll content, chlorophyll fluorescence reaction, Hill reaction rate, and Mg²⁺-ATPase activity in soybean seedlings were investigated. The results indicated that, when soybean seedlings were treated with Pb or acid rain alone, the chlorophyll content, Hill reaction rate, Mg²⁺-ATPase activity, and maximal photochemical efficiency (F _v/F _m) were decreased, while the initial fluorescence (F ₀) and maximum quantum yield (Y) were increased, compared with those of the control. The combined treatment with Pb and acid rain decreased the chlorophyll content, Hill reaction rate, Mg²⁺-ATPase activity, F _v/F _m, and Y and increased F ₀ in soybean seedlings. Under the combined treatment with Pb and acid rain, the two factors showed additive effects on the chlorophyll content in soybean seedlings and exhibited antagonistic effects on the Hill reaction rate. Under the combined treatment with high-concentration Pb and acid rain, the two factors exhibited synergistic effects on the Mg²⁺-ATPase activity, F ₀, F _v/F _m, as well as Y. In summary, the inhibition of the photosynthetic process is an important physiological basis for the simultaneous actions of Pb and acid rain in soybean seedlings.     

Whole-body vibration improves cognitive functions of an adult with ADHD

Adult attention deficit hyperactivity disorder (ADHD) is associated with a variety of cognitive impairments, which were shown to affect academic achievement and quality of life. Current treatment strategies, such as stimulant drug treatment, were demonstrated to effectively improve cognitive functions of patients with ADHD. However, most treatment strategies are associated with a number of disadvantages in a considerable proportion of patients, such as unsatisfactory effects, adverse clinical side effects or high financial costs. In order to address limitations of current treatment strategies, whole-body vibration (WBV) might represent a novel approach to treat cognitive dysfunctions of patients with ADHD. WBV refers to the exposure of the whole body of an individual to vibration and was found to affect physiology and cognition. In the present study, WBV was applied on 10 consecutive days to an adult diagnosed with ADHD. Neuropsychological assessments were performed repeatedly at three different times, i.e., the day before the start of the treatment, on the day following completion of treatment and 14 days after the treatment have been completed (follow-up). An improved neuropsychological test performance following WBV treatment points to the high clinical value of WBV in treating patients with neuropsychological impairments such as ADHD.     

IL-2 Inhibited the Generation of CD4+ Memory T Cells

The survival of T cells at different stages of development is dependent on extrinsic signals. IL-7 is necessary for the development of memory T cells. IL-7 could induce and maintain the differentiation, survival, and proliferation of CD4⁺ memory T cells, and the roles of IL-2 and IL-15 in the generation of CD4⁺ memory T cells were still unclear. A CD4⁺ memory T cells in vitro generated system by adding IL-7. The phenotype of CD4⁺ memory T cells was identified by FACS. The cells proliferation was analyzed by CFSE staining. The involved signal pathways were analyzed by Western blot. We found that IL-2, not IL-15, could inhibit CD4⁺ memory T cells generation. Western blot showed that IL-7 up-regulated the P-STAT5A expression and down-regulated Bax expression, IL-2 reduced the effect of IL-7. Besides, IL-2-combined IL-7 up-regulated the P-AKT and Foxo3a expression a little. In conclusion, our data revealed the inhibitory role of IL-2 in CD4⁺ memory T cells generation and indicated that PI3K/AKT signal pathway was involved.     

Hydraulic adjustments in aspen (Populus tremuloides) seedlings following defoliation involve root and leaf aquaporins

Main conclusion

Changes in root and leaf hydraulic properties and stimulation of transpiration rates that were initially triggered by defoliation were accompanied by corresponding changes in leaf and root aquaporin expression. Aspen (Populus tremuloides) seedlings were subjected to defoliation treatments by removing 50, 75 % or all of the leaves. Root hydraulic conductivity (L_pr) was sharply reduced in plants defoliated for 1 day and 1 week. The decrease in L _pr could not be prevented by stem girdling and it was accompanied in one-day-defoliated plants by a large decrease in the root expression of PIP1,2 aquaporin and an over twofold decrease in hydraulic conductivity of root cortical cells (L _pc). Contrary to L _pr and L _pc, 50 and 75 % defoliation treatments profoundly increased leaf lamina conductance (K _lam) after 1 day and this increase was similar in magnitude for both defoliation treatments. Transpiration rates (E) rapidly declined after the removal of 75 % of leaves. However, E increased by over twofold in defoliated plants after 1 day and the increases in E and K _lam were accompanied by five- and tenfold increases in the leaf expression of PIP2;4 in 50 and 75 % defoliation treatments, respectively. Defoliation treatments also stimulated net photosynthesis after 1 day and 3 weeks, although the increase was not as high as E. Leaf water potentials remained relatively stable following defoliation with the exception of a small decrease 1 day after defoliation which suggests that root water transport did not initially keep pace with the increased transpirational water loss. The results demonstrate the importance of root and leaf hydraulic properties in plant responses to defoliation and point to the involvement of PIP aquaporins in the early events following the loss of leaves.     

Different vasoactive effects of chronic endothelial and neuronal NO-synthase inhibition in young Wistar rats

While the unequivocal pattern of endothelial nitric oxide synthase (eNOS) inhibition in cardiovascular control is recognized, the role of NO produced by neuronal NOS (nNOS) remains unclear. The aim of this study was to compare the effects of chronic treatment with 7-nitroindazole (7-NI, nNOS inhibitor) and N^G-nitro-l-arginine methylester (l-NAME, general and predominantly eNOS inhibitor) on cardiovascular system of young normotensive rats. Wistar rats (4 weeks old) were used: controls and rats administered either 7-NI (10 mg/kg bw/day) or l-NAME (50 mg/kg bw/day) in drinking water for 6 weeks. The systolic blood pressure (sBP) was measured by plethysmographic method, and the vasoactivity of isolated arteries was recorded. 7-NI-treatment did not affect sBP; however, the sBP was increased after l-NAME-treatment. l-NAME inhibited acetylcholine-induced relaxation of thoracic aorta (TA), whereas it remained unchanged after 7-NI-treatment. The response of TA to sodium nitroprusside was increased in both experimental groups. The expression of eNOS and nNOS in TA was unchanged in both experimental groups, whereas the activity of NOS was decreased in l-NAME-treated group. Noradrenaline- and angiotensin II-induced contractions of TA were reduced in l-NAME-treated group; however, the contractions remained unchanged in 7-NI-treated group. In all groups, the endogenous angiotensin II participated in adrenergic contraction of TA; this contribution was significantly increased in l-NAME-treated group. Neurogenic contractions in mesenteric artery (MA) remained unchanged after 7-NI-treatment, but increased after l-NAME-treatment. Results show that NO deficiency induced by administration of 7-NI and l-NAME had different cardiovascular effects: eNOS and nNOS triggered distinct signaling pathways in young normotensive rats.     

Ouabain elicits human glioblastoma cells apoptosis by generating reactive oxygen species in ERK-p66SHC-dependent pathway

Excessive reactive oxygen species (ROS) generation has been implicated as one of main agents in ouabain-induced anticancer effect. Unfortunately, the signaling pathways under it are not very clarified. In the present study, we investigated the molecular mechanism involved in ouabain-induced ROS generation and cell apoptosis on human U373MG and U87MG glioma cells. Ouabain-induced glioblastoma cells apoptosis and increased ROS generation. Clearance ROS by three different ROS scavenger partly, but not totally, reversed ouabain’s effect on cell apoptosis. Ouabain-induced ROS generation was not regulated by calcium overload, reduced nicotinamide adenine dinucleotide phosphate oxidation, but by p66Shc phosphorylation. Ouabain treatment increased p66Shc Ser36 phosphorylation. Knockdown of p66Shc by siRNA significantly inhibited ROS generations in response to ouabain. Ouabain-induced p66Shc phosphorylation through Src/Ras/extracellular signal-regulated kinase signal pathway. Our results uncovered a novel signaling pathway with p66Shc, ouabain-induced ROS generation, and glioblastoma cell apoptosis.     

Ethylene-enhanced ethylene oxidation inVicia faba

The alkene oxygenase (AO) of fababean (Vicia faba L.) converts ethylene to ethylene oxide. Treatment of fababeans with 10μl/liter ethylene increases the activity of this enzyme within 2 hours of ethylene treatment. Though other alkenes were taken up by fababean seedlings, ethylene was the most active in inducing AO activity. The ability of ethylene to increase AO was blocked 60% by cycloheximide, an inhibitor of protein synthesis, and 35% by AgNO₃, an inhibitor of ethylene action.     

Sequence diversity of polysomal mRNAs in roots and shoots of etiolated and greened pea seedlings

The sequence complexity and abundance of polysomal mRNA populations of pea seedlings were measured using RNA excess hybridization to both single-copy DNA and complementary DNA. The estimated sequence complexity of the polysomal mRNA populations was 2.5·10⁷ nucleotides or 19,400 different mRNAs of average size. Since the haploid genome size of pea was found to be 4.0·10⁹ nucleotide pairs, only 0.62% of the total haploid genome of pea was transcribed into polysomal mRNA. The roots and shoots of 4-d etiolated and light-grown seedlings contained similar numbers of diverse mRNAs. The RNA excess hybridizations, using single-copy DNA enriched for sequences transcribed in either light-grown shoots or etiolated roots and single-copy DNA depleted of such sequences, indicated that at least 92% of the sequence complexity of polysomal mRNAs was identical in roots and shoots irrespective of the presence of a functional photosynthetic system. In contrast, RNA excess hybridization to complementary DNA revealed that 21% of the polysomal polyadenylated mRNA mass found in light-grown shoots was absent in etiolated roots. The kinetics of these hybridizations indicated that this was due to the appearance of a limited number of abundant mRNAs under conditions of illumination.     

Mepiquat chloride seed treatment and germination temperature effects on cotton growth,nutrient partitioning,and water use efficiency

Cotton seed (Gossypium hirsutum L. cv. “Stoneville 825”), treated with 0, 0.2, 1.0, and 2.0 g active ingredient (a.i.) mepiquat chloride (MC) kg^?1, was evaluated for the effect of MC on early plant growth. Emergence rate and total emergence of MC-treated seed and control were similar regardless of germination temperature. However, the number of leaves and squares and the dry weight of leaves, stems, and roots for hydroponically grown cotton plants were significantly lower at lower germination temperatures (15°C for 3 day/30°C for 1 day and 15°C for 4 days) than at higher germination temperatures (30°C for 4 days and 30°C for 3 days/15°C for 1 day). All MC treatments significantly decreased the number of nodes, leaves, and squares, as well as dry weight of leaves, stems, and roots, as compared to control plants at 28 days after emergence. MC seed treatments also significantly reduced plant height and total leaf area compared to controls. Water-use efficiency (WUE) was significantly lower for the 1.0 g a.i. MC treatment than for control plants. In general, the highest rate of MC seed treatment resulted in greater concentrations of calcium, phosphorus, and nitrogen in plant leaves and stems and also in greater concentrations of magnesium, phosphorus, and nitrogen in roots than in controls.     

Fatty acid β-oxidation and glyoxylate cycle enzyme activities of induced glyoxysomes from anise suspension cultures

Homogenates of dedifferentiated anise (Pimpinella anisum L.) suspension cultures grown in B-5 medium with sucrose as source of carbon show all but 3 glyoxysomal enzyme activities: NAD-dependent oxidation of palmitoyl-CoA, isocitrate lyase, and malate synthase are lacking. Substitution of 20 mmol/l acetate for sucrose leads to the appearance of these enzyme activities. Only then glyoxysomes with a buoyant density of 1.23 kg/l in sucrose gradients are formed showing the enzyme activities for both ß-oxidation of fatty acids and glyoxylate cycle. Quantitatively and qualitatively they resemble glyoxysomes isolated from endosperm of 4 d old anise seedlings. Therefore, the suspension cultures constitute a valuable system for the study of both mechanisms and regulation of glyoxysome formation in anise.