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972. Pharmacological inhibition of eIF2α phosphorylation by integrated stress response inhibitor (ISRIB) ameliorates vascular calcification in rats

Creator:
Dong, Jianlong, Jin, Sheng, Guo, Jingjing, Yang, Rui, Tian, Danyang, Xue, Hongmei, Xiao, Lin, Guo, Qi, Wang, Ru, Xu, Meng, Teng, Xu, and Wu, Yuming
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
vascular calcification, endoplasmic reticulum stress, eIF2, aorta, and ISRIB
Language:
English
Description:
Vascular calcification (VC) is an independent risk factor for cardiovascular events and all-cause mortality with the absence of current treatment. This study aimed to investigate whether eIF2α phosphorylation inhibition could ameliorate VC. VC in rats was induced by administration of vitamin D3 (3×105 IU/kg, intramuscularly) plus nicotine (25 mg/kg, intragastrically). ISRIB (0.25 mg/kg·week), an inhibitor of eIF2α phosphorylation, ameliorated the elevation of calcium deposition and ALP activity in calcified rat aortas, accompanied by amelioration of increased SBP, PP, and PWV. The decreased protein levels of calponin and SM22α, and the increased levels of RUNX2 and BMP2 in calcified aorta were all rescued by ISRIB, while the increased levels of the GRP78, GRP94, and C/EBP homologous proteins in rats with VC were also attenuated. Moreover, ISRIB could prevent the elevation of eIF2α phosphorylation and ATF4, and partially inhibit PERK phosphorylation in the calcified aorta. These results suggested that an eIF2α phosphorylation inhibitor could ameliorate VC pathogenesis by blocking eIF2α/ATF4 signaling, which may provide a new target for VC prevention and treatment.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

973. Pharmacological stimulation of Wnt/beta-catenin signaling pathway attenuates the course of thioacetamide-induced acute liver failure

Creator:
Koblihová, Eva, Mrázová, Iveta, Vaňourková, Zdenka, Maxová, Hana, Kikerlová, Soňa, Husková, Zuzana, Ryska, Miroslav, Froněk, Jiří, and Vernerová, Zdenka
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
acute liver failure, thioacetamide, and Wnt/β-catenin signaling pathway
Language:
English
Description:
Acute liver failure (ALF) is known for extremely high mortality rate, the result of widespread damage of hepatocytes. Orthotopic liver transplantation is the only effective therapy but its application is limited by the scarcity of donor organs. Given the importance in the liver biology of Wnt/β-catenin signaling pathway, we hypothesized that its stimulation could enhance hepatocyte regeneration and attenuate the course of thioacetamide (TAA)-induced ALF in Lewis rats. Chronic treatment with Wnt agonist was started either immediately after hepatotoxic insult (“early treatment”) or when signs of ALF had developed (“late treatment”). Only 23 % of untreated Lewis rats survived till the end of experiment. They showed marked increases in plasma alanine aminotransferase (ALT) activity and bilirubin and ammonia (NH3) levels; plasma albumin decreased significantly. “Early” and “late” Wnt agonist treatment raised the final survival rate to 69 % and 63 %, respectively, and normalized ALT, NH3, bilirubin and albumin levels. In conclusion, the results show that treatment with Wnt agonist attenuates the course of TAA-induced ALF in Lewis rats, both with treatment initiated immediately after hepatotoxic insult and in the phase when ALF has already developed. Thus, the pharmacological stimulation of Wnt/β-catenin signaling pathway can present a new approach to ALF treatment.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

974. Pharmacological suppression of endogenous glucocorticoid synthesis attenuated blood pressure and heart rate response to acute restraint in Wistar rats

Creator:
Bencze, Michal, Vavřínová, Anna, Zicha, Josef, and Behuliak, Michal
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
stress, adrenalectomy, metyrapone, aminoglutethimide, corticosterone, blood pressure, and heart rate
Language:
English
Description:
Glucocorticoids (GCS) are known to modulate cardiovascular response during stress conditions. The present study was aimed to test the hypothesis that permissive and/or stimulating effect of GCs is essential for the maintenance of peripheral vascular resistance and for the adequate response of cardiovascular system to stressor exposure. The effects of acute pharmacological adrenalectomy (PhADX) on humoral and cardiovascular parameters were studied in adult Wistar rats under the basal conditions and during the acute restraint stress. Acute PhADX was performed by the administration of metyrapone and aminoglutethimide (100 mg/kg s.c. of each drug) resulting in a suppression of endogenous glucocorticoid synthesis. Blood pressure (BP), heart rate (HR) and core body temperature were measured using radiotelemetry. BP responses to administration of vasoactive agents were determined in pentobarbital-anesthetized animals. PhADX considerably attenuated stress-induced increase of BP, HR and core body temperature. PhADX did not abolish BP and HR lowering effects of ganglionic blocker pentolinium indicating preserved sympathetic function in PhADX rats. BP response to exogenous norepinephrine administration was attenuated in PhADX rats, suggesting reduced sensitivity of cardiovascular system. Suppression of corticosterone synthesis by PhADX increased basal plasma levels of ACTH, aldosterone and plasma renin activity in unstressed animals but there was no further increase of these hormones following stressor exposure. In conclusion, PhADX attenuated stress-induced rise of blood pressure, heart rate and core body temperature indicating an important permissive and/or stimulating role of glucocorticoids in the maintenance of the adequate response of cardiovascular system and thermoregulation to several stimuli including acute exposure to stressor.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

975. Phenotypic pattern over centric fusion clinal variation in the water-hyacinth grasshopper, Cornops aquaticum (Orthoptera: Acrididae)

Creator:
Colombo, Pablo C and Remis, María I
Format:
print, počítač, and online zdroj
Type:
model:article and TEXT
Subject:
rovnokřídlí, Orthoptera, Acrididae, Cornops aquaticum, centric fusions, grasshoppers, chromosomal clines, morphometric effects, 2, and 59
Language:
English
Description:
The water-hyacinth grasshopper, Cornops aquaticum, occurs in freshwater environments in the New World between latitudes 23°N and 35°S. At the southernmost margin of this distribution the populations are polymorphic for three centric fusions (Robertsonian translocations). The frequencies of these chromosome rearrangements increase southwards and the recombination in structural homozygotes and heterozygotes diminishes both along the middle and lower courses of the Paraná River. In the present paper we report a similar cline along the southward flowing Uruguay River. In addition, we report the morphological effects of two of these centric fusion polymorphisms, namely the fusions between chromosomes 2 and 5 of the standard complement (fusion 2/5) and chromosomes 3 and 4 (fusion 3/4) and extend this study to the Uruguay River. There is a strong inverse correlation of fusion frequency with temperature, which indicates that these polymorphisms may be related to increased tolerance of colder climates in this originally tropical species, or some other correlated variable. This study is a further example of chromosomal clines correlated with latitude and is one of a few examples of chromosome polymorphisms associated with phenotypic effects. Finally, it indicates ways of using this species for controlling pests., Pablo C. Colombo, María I. Remis., and Obsahuje bibliografii
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

976. Phosphate fertilizers increase CO2 assimilation and yield of soybean in a shaded environment

Creator:
Zhao, W., Zheng, B., Ren, T. H., Zhang, X. H., Ning, T. Y., and Li, G.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
phosphate fertilizer, photosynthesis, shading, soybean, and yield
Language:
Multiple languages
Description:
Two light treatments [ambient sunlight (L1) during the entire growth period and 40% shade (L2) from 40 d after sowing until 24 d after flowering] and two phosphate fertilizer treatments [no phosphate fertilizer application (P0) and a conventional phosphate fertilizer application (P1)] were used to determine how phosphate fertilizer regulates soybean [Glycine max (L.) Merr.] photosynthesis under shading. We showed that phosphorus significantly increased chlorophyll content and grain yield under shading. The light-saturated net photosynthetic rate, apparent quantum yield, maximum electron transport rate, and maximum Rubisco carboxylation rate in P1 under L2 significantly increased. Moreover, phosphate fertilizer significantly improved the electron transfer and PSII reaction center performance under shading. Therefore, phosphate fertilizer increases low light-utilization efficiency by improving PSII performance, promoting ribulose-1,5-bisphosphate regeneration, ensuring a source of carboxylate substrates, and coordinating the balance between photochemical reaction and Calvin cycle under shading.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

977. Phosphene attributes depend on frequency and intensity of retinal tACS

Creator:
Kvašňák, Eugen, Orendáčová, Mária, and Vránová, Jana
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
transcranial alternating current stimulation (tACS), phosphene, electrical stimulation, tACS frequency, and tACS intensity
Language:
English
Description:
Phosphene is the experience of light without natural visual stimulation. It can be induced by electrical stimulation of the retina, optic nerve or cortex. Induction of phosphenes can be potentially used in assistive devices for the blind. Analysis of phosphene might be beneficial for practical reasons such as adjustment of transcranial alternating current stimulation (tACS) frequency and intensity to eliminate phosphene perception (e.g., tACS studies using verum tACS group and sham group) or, on the contrary, to maximize perception of phosphenes in order to be more able to study their dynamics. In this study, subjective reports of 50 healthy subjects exposed to different intensities of retinal tACS at 4 different frequencies (6, 10, 20 and 40 Hz) were analyzed. The effectiveness of different tACS frequencies in inducing phosphenes was at least 92 %. Subject reported 41 different phosphene types; the most common were light flashes and light circles. Changing the intensity of stimulation often induced a change in phosphene attributes. Up to nine phosphene attributes changed when the tACS intensity was changed. Significant positive correlation was observed between number of a different phosphene types and tACS frequency. Based on these findings, it can be concluded that tACS is effective in eliciting phosphenes whose type and attributes change depending on the frequency and intensity of tACS. The presented results open new questions for future research.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

978. Photoprotective roles of ascorbate and PSII cyclic electron flow in the response of the seagrass Zostera marina to oxygen-evolving complex photoinactivation

Creator:
Zhao, W., Zhang, Q.S., Tan, Y., Liu, Z., Ma, M.Y., Wang, M.X., and Luo, C.Y.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
alternative electron donor, ascorbate, cstylePSII cyclic electron flow, and cstyle
Language:
Multiple languages
Description:
The oxygen-evolving complex (OEC) of Zostera marina is prone to deactivation under visible light, which results in a formation of the long-lived radical P680+. The mechanism to prevent damage caused by P680+ remains unclear. In this study, following light exposure, the upregulation in ascorbate (AsA) content and the presence of PSII cyclic electron flow (PSII-CEF) provide evidence that AsA and PSII-CEF donate electrons to PSII. Furthermore, a factorial design experiment with different combinations of inhibition of AsA and PSII-CEF demonstrates that both inhibition treatments lead to decreases in maximal photochemical yield of PSII, increases in relative variable fluorescence at the K-step, as well as the net loss of PSII reaction center proteins and further degradation of OEC peripheral proteins. These results suggest that AsA and PSII-CEF play photoprotective roles by providing electrons to efficiently prevent damage to PSII from the highly oxidizing radical P680+ in Z. marina.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

979. Photosynthetic apparatus performance and anatomical modulations of Alcantarea imperialis (Bromeliaceae) exposed to selenium during in vitro growth

Creator:
Martins, J.P.R., Moreira, S.W., Braga, P.C.S., Conde, L.T., Cipriano, R., Falqueto, A.R., and Gontijo, A.B.P.L.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
bromeliad, chlorophyll a fluorescence, electron transport, plant anatomy, and plant tissue culture
Language:
Multiple languages
Description:
Elements not usually included in culture medium formulations, such as selenium (Se), may have beneficial effects on micropropagated plants. We evaluated the effects of Se on the physiological and anatomical responses of Alcantarea imperialis during in vitro culture. Plants were cultured in a medium containing a gradient of Se concentrations (0, 4, 8, 16, or 32 µM Se). After 56 d, the growth traits, chlorophyll a fluorescence, and root and leaf anatomy were analyzed. The fresh mass declined at the highest Se concentration. Higher Se concentrations induced bigger stomata, while the stomatal density decreased. Plants cultured with Se had improved PSII and PSI electron transport. This led to higher values of the total performance index. Thus, Se-induced plants showed a higher electron transport dynamics and energy conservation from water to PSI and developed anatomical traits that can favor tolerance to water deficit.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

980. Photosynthetic response of lutein-deficient mutant lut2 of Arabidopsis thaliana to low temperature at high light

Creator:
Popova, A. V., Vladkova, R., Borisova, P., Georgieva, K., Mihailova, G., Velikova, V., Tsonev, T., and Ivanov, A. G.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
abiotic stress, carotenoid mutant, energy partitioning, photoprotection, and photosynthetic performance
Language:
Multiple languages
Description:
Alterations in photosynthetic performance of lutein-deficient mutant lut2 and wild type (wt) of Arabidopsis thaliana were followed after treatment with low temperature and high light for 6 d. The obtained results indicated lower electrolyte leakage, lower excitation pressure, and higher actual photochemical efficiency of PSII in lut2 plants exposed to combined stress compared to wt plants. This implies that lut2 is less susceptible to the applied stress conditions. The observed lower values of quantum efficiency of nonphotochemical quenching and energy-dependent component of nonphotochemical quenching in lut2 suggest that nonphotochemical quenching mechanism(s) localized within LHCII could not be involved in the acquisition of higher stress tolerance of lut2 and alternatives to nonphotochemical quenching mechanisms are involved for dissipation of excess absorbed light. We suggest that the observed enhanced capacity for cyclic electron flow and the higher oxidation state of P700 (P700+), which suggests PSI-dependent energy quenching in lut2 plants may serve as efficient photoprotective mechanisms, thus explaining the lower susceptibility of lut2 to the combined stress treatments.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public