Arbuscular mycorrhizal (AM) fungi establish symbiotic associations with many plant species, transferring significant amounts of soil nutrients such as phosphorus to plants and receiving photosynthetically fixed carbon in return. Functioning of AM symbiosis is thus based on interaction between two living partners. The importance of dead AM fungal biomass (necromass) in ecosystem processes remains unclear. Here, we applied either living biomass or necromass (0.0004 potting substrate weight percent) of monoxenically produced AM fungus (Rhizophagus irregularis) into previously sterilized potting substrate planted with Andropogon gerardii. Plant biomass production significantly improved in both treatments as compared to non-amended controls. Living AM fungus, in contrast to the necromass, specifically improved plant acquisition of nutrients normally supplied to the plants by AM fungal networks, such as phosphorus and zinc. There was, however, no difference between the two amendment treatments with respect to plant uptake of other nutrients such as nitrogen and/or magnesium, indicating that the effect on plants of the AM fungal necromass was not primarily nutritional. Plant growth stimulation by the necromass could thus be either due to AM fungal metabolites directly affecting the plants, indirectly due to changes in soil/root microbiomes or due to physicochemical modifications of the potting substrate. In the necromass, we identified several potentially bioactive molecules. We also provide experimental evidence for significant differences in underground microbiomes depending on the amendment with living or dead AM fungal biomass. This research thus provides the first glimpse into possible mechanisms responsible for observed plant growth stimulation by the AM fungal necromass.
- Klíčová slova
- Arbuscular mycorrhiza (AM), Mass spectrometry (MS), Metabolites, Microbiome, Necromass, Signal,
- MeSH
- Andropogon * MeSH
- biomasa MeSH
- Glomeromycota * MeSH
- kořeny rostlin MeSH
- mykorhiza * MeSH
- symbióza MeSH
- Publikační typ
- časopisecké články MeSH
Mice are nocturnal animals. Surprisingly, the majority of physiological/pharmacological studies are performed in the morning, i.e., in the non-active phase of their diurnal cycle. We have shown recently that female (not male) mice lacking the M4 muscarinic receptors (MR, M4KO) did not differ substantially in locomotor activity from their wild-type counterparts (C57Bl/6Tac) during the inactive period. Increased locomotion has been shown in the active phase of their diurnal cycle. We compared the effects of scopolamine, oxotremorine, and cocaine on locomotor response, hypothermia and spontaneous behavior in the open field arena in the morning (9:00 AM) and in the evening (9:00 PM) in WT and in C57Bl/6NTac mice lacking the M4 MR. Furthermore, we also studied morning vs. evening densities of muscarinic, GABAA, D1-like, D2-like, NMDA and kainate receptors using autoradiography in the motor, somatosensory and visual cortex and in the striatum, thalamus, hippocampus, pons, and medulla oblongata. At 9:00 AM, scopolamine induced an increase in motor activity in WT and in M4KO, yet no significant increase was observed at 9:00 PM. Oxotremorine induced hypothermic effects in both WT and M4KO. Hypothermic effects were more evident in WT than in M4KO. Hypothermia in both cases was more pronounced at 9:00 AM than at 9:00 PM. Cocaine increased motor activity when compared to saline. There was no difference in behavior in the open field between WT and M4KO when tested at 9:00 AM; however, at 9:00 PM, activity of M4KO was doubled in comparison to that of WT. Both WT and KO animals spent less time climbing in their active phase. Autoradiography revealed no significant morning vs. evening difference. Altogether, our results indicate the necessity of comparing morning vs. evening drug effects.
- Klíčová slova
- M4 muscarinic receptor, biorhythm, cocaine, motor activity, open field, oxotremorine, scopolamine, temperature,
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: M4 muscarinic receptors (MR) presumably play a role in motor coordination. Previous studies have shown different results depending on genetic background and number of backcrosses. However, no attention has been given to biorhythms. MATERIAL AND METHODS: We therefore analyzed biorhythms under a light/dark cycle obtained telemetrically in intact animals (activity, body temperature) in M4 KO mice growth on the C57Bl6 background using ChronosFit software. Studying pure effects of gene knockout in daily rhythms is especially important knowledge for pharmacological/behavioral studies in which drugs are usually tested in the morning. RESULTS: We show that M4 KO mice motor activity does not differ substantially from wild-type mice during light period while in the dark phase (mice active part of the day), the M4 KO mice reveal biorhythm changes in many parameters. Moreover, these differences are sex-dependent and are evident in females only. Mesor, night-day difference, and night value were doubled or tripled when comparing female KO versus male KO. Our in vitro autoradiography demonstrates that M4 MR proportion represents 24% in the motor cortex (MOCx), 30% in the somatosensory cortex, 50% in the striatum, 69% in the thalamus, and 48% in the intergeniculate leaflet (IGL). The M4 MR densities were negligible in the subparaventricular zone, the posterior hypothalamic area, and in the suprachiasmatic nuclei. CONCLUSIONS: We conclude that cholinergic signaling at M4 MR in brain structures such as striatum, MOCx, and probably with the important participation of IGL significantly control motor activity biorhythm. Animal activity differs in the light and dark phases, which should be taken into consideration when interpreting the results.
- Klíčová slova
- M4 muscarinic receptor, biorhythm, intergeniculate leaflet, motor activity, motor cortex, sex differences, striatum, suprachiasmatic nuclei, temperature, thalamus,
- MeSH
- chování zvířat fyziologie MeSH
- modely u zvířat MeSH
- mozek fyziologie MeSH
- myši inbrední C57BL MeSH
- myši knockoutované MeSH
- myši MeSH
- periodicita * MeSH
- pohybová aktivita genetika fyziologie MeSH
- receptor muskarinový M4 nedostatek genetika MeSH
- sexuální faktory MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- receptor muskarinový M4 MeSH
Chlorine cycle in natural ecosystems involves formation of low and high molecular weight organic compounds of living organisms, soil organic matter and atmospherically deposited chloride. Chloroform (CHCl3) and adsorbable organohalogens (AOX) are part of the chlorine cycle. We attempted to characterize the dynamical changes in the levels of total organic carbon (TOC), AOX, chlorine and CHCl3 in a drinking water reservoir and in its tributaries, mainly at its spring, and attempt to relate the presence of AOX and CHCl3 with meteorological, chemical or biological factors. Water temperature and pH influence the formation and accumulation of CHCl3 and affect the conditions for biological processes, which are demonstrated by the correlation between CHCl3 and ΣAOX/Cl(-) ratio, and also by CHCl3/ΣAOX, CHCl3/AOXLMW, CHCl3/ΣTOC, CHCl3/TOCLMW and CHCl3/Cl(-) ratios in different microecosystems (e.g. old spruce forest, stagnant acidic water, humid and warm conditions with high biological activity). These processes start with the biotransformation of AOX from TOC, continue via degradation of AOX to smaller molecules and further chlorination, and finish with the formation of small chlorinated molecules, and their subsequent volatilization and mineralization. The determined concentrations of chloroform result from a dynamic equilibrium between its formation and degradation in the water; in the Hamry water reservoir, this results in a total amount of 0.1-0.7 kg chloroform and 5.2-15.4 t chloride. The formation of chloroform is affected by Cl(-) concentration, by concentrations and ratios of biogenic substrates (TOC and AOX), and by the ratios of the substrates and the product (feedback control by chloroform itself).
- Klíčová slova
- Adsorbable organohalogens, Chloride, Chlorine cycle, Climate relevant compounds, Physicochemical parameters of water, Trichloromethane,
- MeSH
- chemické látky znečišťující vodu analýza MeSH
- chlor analýza MeSH
- chloroform analýza MeSH
- halogenované uhlovodíky analýza MeSH
- jezera analýza chemie MeSH
- karcinogeny analýza MeSH
- látky znečišťující vzduch analýza MeSH
- pitná voda analýza chemie MeSH
- plyny analýza MeSH
- řeky chemie MeSH
- skleníkový efekt MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
- Názvy látek
- chemické látky znečišťující vodu MeSH
- chlor MeSH
- chloroform MeSH
- halogenované uhlovodíky MeSH
- karcinogeny MeSH
- látky znečišťující vzduch MeSH
- pitná voda MeSH
- plyny MeSH
Radioisotopes carbon 14 and chlorine 36 were used to elucidate the environmental role of trichloroacetic acid (TCA) formerly taken to be a herbicide and a secondary air pollutant with phytotoxic effects. However, use of 14C-labeling posed again known analytical problems, especially in TCA extraction from the sample matrix. Therefore--after evaluation of available methods--a new procedure using decarboxylation of [1,2-14C]TCA combined with extraction of the resultant 14C-chloroform with a non-polar solvent and its subsequent radiometric measurement was developed. The method solves previous difficulties and permits an easy determination of amounts between 0.4 and 20 kBq (10 - 500 ng g(-1)) of carrier-less [1,2-14C]TCA in samples from environmental investigations. The procedure is, however, not suitable for direct [36Cl]TCA determination in chlorination studies with 36Cl. Because TCA might be microbially degraded in soil during extraction and sample storage and its extraction from soil or needles is never complete, the decarboxylation method--i.e. 2 h TCA decomposition to chloroform and CO2 in aqueous solution or suspension in closed vial at 90 degrees C and pH 4.6 with subsequent CHCl3 extraction-is recommended here, estimated V < 7%. Moreover, the influence of pH and temperature on the decarboxylation of TCA in aqueous solution was studied in a broad range and its environmental relevance is shown in the case of TCA decarboxylation in spruce needles which takes place also at ambient temperatures and might amount more than 10-20% after a growing season. A study of TCA distribution in spruce needles after below-ground uptake shows the highest uptake rate into current needles which have, however, a lower TCA content than older needle-year classes, TCA biodegradation in forest soil leads predominatingly to CO2.
- MeSH
- chlor chemie MeSH
- chloroform chemie MeSH
- dekarboxylace MeSH
- ekosystém MeSH
- koncentrace vodíkových iontů MeSH
- kyselina trichloroctová analýza chemie metabolismus MeSH
- látky znečišťující půdu analýza MeSH
- monitorování životního prostředí metody MeSH
- nadzemní části rostlin chemie MeSH
- půda MeSH
- radioizotopy uhlíku chemie MeSH
- stromy MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chlor MeSH
- chloroform MeSH
- kyselina trichloroctová MeSH
- látky znečišťující půdu MeSH
- půda MeSH
- radioizotopy uhlíku MeSH
