Males of many bumblebee species exhibit a conspicuous pre-mating behavior with two distinct behavioral components: scent marking and patrol flying. The marking pheromone is produced by the cephalic part of the labial gland (CLG). As far as is known, the CLG secretion is species specific, and it usually consists of two types of compounds: (i) straight-chain aliphatic alcohols, aldehydes or esters, and (ii) acyclic mono-, sesqui- and diterpenes (alcohols or acetates). Here, we summarize data from the literature reporting chemical composition of the CLG secretions of more than 80 bumblebee species. Similarities and differences within and between subgenera are discussed in the context of biosynthetic pathways and evolution.
The queens of advanced social insects maintain their reproductive monopoly by using exocrine chemicals. The chemistry of these "queen pheromones" in termites is poorly known. We show that primary queens of four higher termites from the subfamily Syntermitinae (Embiratermes neotenicus, Silvestritermes heyeri, Labiotermes labralis, and Cyrilliotermes angulariceps) emit significant amounts of the sesquiterpene alcohol (E)-nerolidol. It is the dominant analyte in queen body washes; it is present on the surface of eggs, but absent in kings, workers, and soldiers. In E. neotenicus, it is also produced by replacement neotenic queens, in quantities correlated with their fertility. Using newly synthesised (3R,6E)-nerolidol, we demonstrate that the queens of this species produce only the (R) enantiomer. It is distributed over the surface of their abdomen, in internal tissues, and in the haemolymph, as well as in the headspace of the queens. Both (R) and (S) enantiomers are perceived by the antennae of E. neotenicus workers. The naturally occurring (R) enantiomer elicited a significantly larger antennal response, but it did not show any behavioural effect. In spite of technical difficulties encountered in long-term experiments with the studied species, (3R,6E)-nerolidol remains among eventual candidates for the role in queen fertility signalling.
- MeSH
- acetylcholin metabolismus MeSH
- acetylcholinesterasa metabolismus MeSH
- acetylthiocholin metabolismus MeSH
- Electrophorus metabolismus MeSH
- hydrolýza MeSH
- katalýza MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- rybí proteiny metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The metabolic form of vitamin A, retinol, has a pivotal role in the nervous system development and neuronal differentiation, both during embryogenesis through maternal-fetal support and in the early postnatal life. Retinoic acid was administered orally at a dose of 10 mg/kg body weight to pregnant female rats through days 8-10 of gestation. Spinal cord sections were processed for histochemical visualization one day after birth and on day 21, when weaning is expected. NADPH-diaphorase (NADPH-d)-positive neurons were found in the dorsal horn, around the central canal, and at the intermediolateral cell column on postnatal days 1 and 21 in both control and experimental groups. There were no NADPHd-positive structures in the ventral horn. The results suggest that prenatal administration of high doses of retinoic acid is not associated with postnatal morphological changes in NADPH-d-positive neurons in the rat spinal cord. Levels of antioxidants and related enzymes in retinoid storage organs were measured to estimate possible side effects. The activities of enzymes detoxifying superoxide radicals and peroxides were supressed after birth. A decrease in the level of reduced glutathione was observed on postnatal day 21, indicating an unbalanced redox environment.
- MeSH
- játra účinky léků růst a vývoj metabolismus MeSH
- krysa rodu rattus MeSH
- mícha účinky léků růst a vývoj metabolismus MeSH
- NADP metabolismus MeSH
- potkani Wistar MeSH
- těhotenství MeSH
- vitamin A aplikace a dávkování farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A new and simple analytical method is described for the determination of the IC50 values of the inhibitors of the hydrolysis of acetylcholine (ACh) or acetylthiocholine (ATCh) by cholinesterases. The method is based on monitoring the time course of the pH value during the uninhibited and inhibited reaction. It requires only a pH meter with a suitable pH measuring cell and a small thermostated stirred batch reactor. The method has been validated for twelve different types of cholinesterase inhibitors. The determined IC50 values are comparable to those obtained by independent, more complicated, and expensive methods (Ellman's and pH-stat).
Kinetics and mechanism of in vitro hydrolyses of acetylcholine and acetylthiocholine by carbamates were studied in a batch reactor at 25 degrees C, pH 8, and ionic strength of 0.11 M. Every hydrolysis was monitored by 3-4 independent methods. All studied hydrolyses can be described by the model of competitive inhibition with an irreversible step (k3). A table of obtained average values of rate constants and discussion of the resultes are given.
The pI50 index and separation coefficients of chosen 3-N,N-diethylaminophenyl-N',N'-dialkylcarbamates were determined. Index pL50 (pI50 = negative logarithm of molar concentration of inhibitor inhibiting the enzyme activity by 50%) describes the effectiveness of the inhibitor. The rate of ability of the inhibitor to pass the blood-brain barrier is usually described by the separation coefficient in a system n-octanol/water (K(ow)). Obtained results were compared with pL50 and K(ow) of Exelon, the commercially used drug against the Alzheimer's disease.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- acetylthiocholin metabolismus MeSH
- alkylace MeSH
- cholinesterasové inhibitory farmakologie MeSH
- dioxany farmakologie MeSH
- Electrophorus MeSH
- financování organizované MeSH
- karbamáty farmakologie chemie MeSH
- kinetika MeSH
- molekulární modely MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
The original Ellman's spectrophotometrical method for cholinesterase activity determination uses 5,5'-dithiobis-2-nitrobenzoic acid (DTNB, Ellman's reagent) as a chromogen and records the level of cholinesterase activity as an increase of absorbance at 412 nm. Although this procedure usually poses no problem, exceptions arise when the concentration of DTNB is far higher than the concentration of acetylthiocholine (ATCH). It was found that the ratio of concentrations of DTNB/ATCH is an important parameter for the ATCH hydrolysis course: high excess of DTNB decreases the hydrolysis rate resulting in a lower measured enzyme activity. Our experiments indicate that this influence of DTNB concentration can be explained by the inhibition of ATCH hydrolysis by DTNB.
Kinetics of hydrolysis of acetylcholine and acetylthiocholine by two types of acetylcholinesterase and butyrylcholinesterase inhibited by 13 new inhibitors (5 carbamates and 8 carbazates--hydrazinium derivatives) was measured in vitro in a batch reactor at 25 degrees C, pH 8, ionic strength 0.11 M and enzyme activity 3.5 U by four nondependent analytical methods. Sevin, rivastigmin (Exelon) and galantamin (Reminyl) served as comparative inhibiting standards. Kinetics of hydrolyses inhibited by all studied carbamates, sevin, carbazates (with exceptions) and rivastigmin (with exceptions) can be simulated by the competitive inhibition model with irreversible reaction between enzyme and inhibitor. Galantamin does not fulfil this model. In positive simulations, the value of inhibition (carbamoylation) rate constant k3 was calculated, describing the reaction velocity between the given enzyme and inhibitor. Physiologically important hydrolyses of acetylcholine catalyzed by acetylcholinesterase from electric eel or bovine erythrocytes and butyrylcholinesterase from horse plasma can be most quickly inhibited by carbamoylation of the mentioned enzymes by the 3-N,N-diethylaminophenyl-N'-(1-alkyl) carbamates 4 and 5. Probably this is due to a long enough hydrocarbon aliphatic substituent (hexyl and octyl) on the amidic nitrogen atom. The tested carbazates failed as inhibitors of cholinesterases. The regeneration ability of the inhibited enzymes was not measured.
Kinetics and the mechanism of total in vitro hydrolyses (i.e. up to the exhaustion of substrate) of acetylcholine and acetylthiocholine by acetylcholinesterase and butyrylcholinesterase were studied in vitro in a batch reactor at 25 degrees C, pH 8 and ionic strength of 0.11 M. Every hydrolysis was monitored by 2-3 independent analytical methods. All studied types of enzymatic hydrolyses fulfilled the Michaelis-Menten reaction scheme with the irreversible second step. A table of obtained average values of rate constants and estimations of initial molar enzyme concentrations, and discussion of the results are presented.
- MeSH
- acetylcholin metabolismus MeSH
- acetylcholinesterasa krev metabolismus MeSH
- acetylthiocholin metabolismus MeSH
- butyrylcholinesterasa metabolismus MeSH
- erytrocyty enzymologie MeSH
- financování organizované MeSH
- hydrolýza MeSH
- kinetika MeSH
- skot MeSH
- spektrofotometrie MeSH
- substrátová specifita MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
