light inhibition
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The aim was to determine which specific regions of the visible light spectrum were responsible for the induction or inhibition of laccase in Pycnoporus sanguineus. Cultures were exposed to various bandwidth lights: blue (460 nm), green (525 nm), white (a combination of 460 and 560 nm), red (660 nm), and darkness. The results indicate that short wavelengths strongly inhibit the production of laccase: green (3.76 ± 1.12 U/L), blue (1.94 ± 0.36 U/L), and white (1.05 ± 0.21 U/L) in proportions of 85.8, 92.6, and 96.0%, respectively; whereas long wavelengths inhibit laccase production only partially i.e., red light (14.05 ± 4.79 U/L) in a proportion of 46.8%. Maximum activity was induced in absence of visible light (30 °C, darkness), i.e., 30.76 ± 4.0 U/L. It is concluded that the production of laccase in P. sanguineus responds to light stimuli [measured as wavelengths and lx] and that it does so inversely. This can be explained as an ecological mechanism of environmental recognition, given that P. sanguineus develops inside lignocellulose structures in conditions of darkness. The presence of short wavelength light (460-510 nm) would indicate that the organism finds itself in an external environment, unprovided of lignin, and that it is therefore unnecessary to secrete laccase. This possible new regulation in the laccase production in P. sanguineus has important biotechnological implications, for it would be possible to control the production of laccase using light stimuli.
Exposure of rats to continuous light attenuates melatonin production and results in hypertension development. This study investigated whether hypertension induced by continuous light (24 hours/day) exposure induces heart and aorta remodelling and if these alterations are prevented by melatonin or angiotensin converting enzyme inhibitor captopril. Four groups of 3-month-old male Wistar rats (10 per group) were treated as follows for six weeks: untreated controls, exposed to continuous light, light-exposed, and treated with either captopril (100 mg/kg/day) or melatonin (10 mg/kg/day). Exposure to continuous light led to hypertension, left ventricular (LV) hypertrophy and fibrosis, and enhancement of the oxidative load in the LV and aorta. Increase in systolic blood pressure by continuous light exposure was prevented completely by captopril and partially by melatonin. Both captopril and melatonin reduced the wall thickness and cross-sectional area of the aorta and reduced the level of oxidative stress. However, only captopril reduced LV hypertrophy development and only melatonin reduced LV hydroxyproline concentration in insoluble and total collagen in rats exposed to continuous light. In conclusion, captopril prevented LV hypertrophy development in the continuous light-induced hypertension model, while only melatonin significantly reduced fibrosis. This antifibrotic action of melatonin may be protective in hypertensive heart disease.
- MeSH
- antihypertenziva terapeutické užití MeSH
- hypertenze farmakoterapie MeSH
- inhibitory ACE terapeutické užití MeSH
- kaptopril terapeutické užití MeSH
- krevní tlak účinky léků MeSH
- krysa rodu rattus MeSH
- melatonin terapeutické užití MeSH
- oxidační stres účinky léků MeSH
- potkani Wistar MeSH
- světlo * MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Non-photochemical quenching (NPQ) is a photoprotective mechanism in light-harvesting antennae. NPQ is triggered by chloroplast thylakoid lumen acidification and is accompanied by violaxanthin de-epoxidation to zeaxanthin, which further stimulates NPQ. In the present study, we show that violaxanthin can act in the opposite direction to zeaxanthin because an increase in the concentration of violaxanthin reduced NPQ in the light-harvesting antennae of Chromera velia. The correlation overlapped with a similar relationship between violaxanthin and NPQ as observed in isolated higher plant light-harvesting complex II. The data suggest that violaxanthin in C. velia can act as an inhibitor of NPQ, indicating that violaxanthin has to be removed from the vicinity of the protein to reach maximal NPQ.
The aims of our study were to investigate into the effect of lithium on smooth muscle contraction and phosphorylation of myosin light chain (MLC20) by MLCK and to find out the clue of its mechanism. Isolated rabbit duodenum smooth muscle strips were used to study the effects of lithium on their contractile activity under the condition of Krebs' solution by means of HW- 400S constant temperature smooth muscle trough. Myosin and MLCK were purified from the chicken gizzard smooth muscle. Myosin phosphorylation was determined by Glycerol-PAGE, myosin Mg2+-ATPase activity was measured by Pi liberation method. Lithium (10-40 mM) inhibited the contraction in duodenum in a dose-related and time-dependent manner. Lithium could also inhibit the extent of myosin phosphorylation in a dose-related and time-dependent manner, whereas it inhibited Mg2+-ATPase activity in a dose-related manner. Lithium inhibited smooth muscle contraction by inhibition of myosin phosphorylation and Mg2+-ATPase activity.
- MeSH
- financování organizované MeSH
- fosforylace MeSH
- hladké svalstvo metabolismus účinky léků MeSH
- kinasa lehkého řetězce myosinu metabolismus MeSH
- králíci MeSH
- lehké řetězce myosinu metabolismus MeSH
- lithium farmakologie MeSH
- svalová kontrakce účinky léků MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- zvířata MeSH
Aerobic anoxygenic phototrophs contain photosynthetic reaction centers composed of bacteriochlorophyll. These organisms are photoheterotrophs, as they require organic carbon substrates for their growth whereas light-derived energy has only an auxiliary function. To establish the contribution of light energy to their metabolism, we grew the phototrophic strain Erythrobacter sp. NAP1 in a carbon-limited chemostat regimen on defined carbon sources (glutamate, pyruvate, acetate, and glucose) under conditions of different light intensities. When grown in a light-dark cycle, these bacteria accumulated 25% to 110% more biomass in terms of carbon than cultures grown in the dark. Cultures grown on glutamate accumulated the most biomass at moderate light intensities of 50 to 150 μmol m(-2) s(-1) but were inhibited at higher light intensities. In the case of pyruvate, we did not find any inhibition of growth by high irradiance. The extent of anaplerotic carbon fixation was detemined by radioactive bicarbonate incorporation assays. While the carboxylation activity provided 4% to 11% of the cellular carbon in the pyruvate-grown culture, in the glutamate-grown cells it provided only approximately 1% of the carbon. Additionally, we tested the effect of light on respiration and photosynthetic electron flow. With increasing light intensity, respiration decreased to approximately 25% of its dark value and was replaced by photophosphorylation. The additional energy from light allows the aerobic anoxygenic phototrophs to accumulate the supplied organic carbon which would otherwise be respired. The higher efficiency of organic carbon utilization may provide an important competitive advantage during growth under carbon-limited conditions.
- MeSH
- aerobióza MeSH
- biomasa MeSH
- fototrofní procesy * MeSH
- hydrogenuhličitany metabolismus MeSH
- izotopové značení MeSH
- izotopy uhlíku metabolismus MeSH
- koloběh uhlíku MeSH
- kultivační média chemie MeSH
- pyruváty metabolismus MeSH
- Sphingomonadaceae metabolismus účinky záření MeSH
- světlo * MeSH
- tma MeSH
- transport elektronů MeSH
- uhlík metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Východiska: V průběhu téměř celých lidských dějin se lidé zabývali otázkou-jakým způso- bem (ne zdraví škodlivým) zabránit nechtěnému těhotenství. Příspěvek zahrnuje přehled historických přístupů k rozličným druhům antikoncepce. U vybraných druhů jsou uváděny názory dobových autorů (odborníků, a to zpravidla lékařů), na účinnost dané metody. Zvláštní pozornost je věnována prostředku bariérové antikoncepce, a to kondomu.Cíl: Cílem publikace je podat přehled historických přístupů k rozličným druhům antikon- cepce.Metodika: Pro sběr dat byla zvolena analýza dokumentů v tuzemských i zahraničních databázích a pomocí klíčových slov a booleovských operátorů. Informace byly čerpány z tuzemských i zahraničních referenčních zdrojů, které jsou uvedeny v sekci Literatura na konci příspěvku. Řadu materiálů (např. názory odborníků) čerpali autoři z vlastních archívních sbírek a dokumentů, které docent Janiš shromažďoval více než čtvrt století.Výsledky: Zjištěné výsledky byly analyzovány a zpracovány do přehledu historických pří- stupů k rozličným druhům antikoncepce.Závěr: Otázka antikoncepce a zabránění nechtěnému těhotenství je stará snad jako lid- stvo samo. V jednotlivých vývojových obdobích můžeme zaznamenat různé trendy a pří- stupy s ohledem na danou historickou etapu. Od přírodních prostředků po bizarní zavá- dění do pochvy kuliček uhnětených např. z mandlí, medu, granátových jablek, až ke kon- domům a chemické antikoncepci. Věda musela urazit velký kus cesty, aby dnešní moderní ženy mohly svobodně volit pro sebe tu nejvhodnější antikoncepci, která jim bude vy- hovovat.
Introduction: Throughout almost all of human history, people have been concerned with the question of how (not harmful to health) to prevent unwanted pregnancies. The paper includes an overview of historical approaches to various types of contraception. For se- lected species, the opinions of contemporary authors (experts, usually doctors) on the ef- fectiveness of the method are given. Special attention is paid to the means of barrier contraception, namely the condom.Aims: The aim of the publication is to provide an overview of historical approaches to va- rious types of contraception.Methodology: The analysis of documents in domestic and foreign databases and using keywords and Boolean operators was chosen for data collection. The information was drawn from domestic and foreign reference sources, which are listed in the Literature section at the end of the paper. A number of materials (e.g. expert opinions) were drawn by the authors from their own archive collections and documents that Associate Profes- sor Janiš had been collecting for more than a quarter of a century.Results: The obtained results were analyzed and processed into an overview of historical approaches to various types of contraception.Conclusion: The question of contraception and the prevention of unwanted pregnancy is perhaps as old as humanity itself. In individual development periods, we can notice various trends and approaches with regard to a given historical stage. From natural re- medies to the bizarre introduction into the vagina of balls kneaded, for example, from almonds, honey, pomegranates, to condoms and chemical contraception. Science has come a long way so that today's modern women can freely choose the most appropriate contraceptive that suits them.
Suprachiasmatic nucleus (SCN) of the hypothalamus is the master clock that drives circadian rhythms in physiology and behavior and adjusts their timing to external cues. Neurotransmitter glutamate and glutamatergic receptors sensitive to N-methyl-d-aspartate (NMDA) play a dual role in the SCN by coupling astrocytic and neuronal single cell oscillators and by resetting their phase in response to light. Recent reports suggested that signaling by endogenous cannabinoids (ECs) participates in both of these functions. We have previously shown that ECs, such as 2-arachidonoylglycerol (2-AG), act via CB1 receptors to affect the SCN response to light-mimicking NMDA stimulus in a time-dependent manner. We hypothesized that this ability is linked to the circadian regulation of EC signaling. We demonstrate that circadian clock in the rat SCN regulates expression of 2-AG transport, synthesis and degradation enzymes as well as its receptors. Inhibition of the major 2-AG synthesis enzyme, diacylglycerol lipase, enhanced the phase delay and lowered the amplitude of explanted SCN rhythm in response to NMDAR activation. Using microscopic PER2 bioluminescence imaging, we visualized how individual single cell oscillators in different parts of the SCN respond to the DAGL inhibition/NMDAR activation and shape response of the whole pacemaker. Additionally, we present strong evidence that the zero amplitude behavior of the SCN in response to single NMDA stimulus in the middle of subjective night is the result of a loss of rhythm in individual SCN cells. The paper provides new insights into the modulatory role of endocannabinoid signaling during the light entrainment of the SCN.
- MeSH
- agonisté excitačních aminokyselin farmakologie MeSH
- cirkadiánní rytmus účinky léků fyziologie MeSH
- endokanabinoidy fyziologie MeSH
- krysa rodu rattus MeSH
- lipoproteinlipasa antagonisté a inhibitory metabolismus MeSH
- myši transgenní MeSH
- myši MeSH
- N-methylaspartát farmakologie MeSH
- nucleus suprachiasmaticus cytologie účinky léků fyziologie MeSH
- potkani Wistar MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
