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Chemical communication is ubiquitous. The identification of conserved structural elements in visual and acoustic communication is well established, but comparable information on chemical communication displays (CCDs) is lacking. We assessed the phenotypic integration of CCDs in a meta‐analysis to characterize patterns of covariation in CCDs and identified functional or biosynthetically constrained modules. Poorly integrated plant CCDs (i.e. low covariation between scent compounds) support the notion that plants often utilize one or few key compounds to repel antagonists or to attract pollinators and enemies of herbivores. Animal CCDs (mostly insect pheromones) were usually more integrated than those of plants (i.e. stronger covariation), suggesting that animals communicate via fixed proportions among compounds. Both plant and animal CCDs were composed of modules, which are groups of strongly covarying compounds. Biosynthetic similarity of compounds revealed biosynthetic constraints in the covariation patterns of plant CCDs. We provide a novel perspective on chemical communication and a basis for future investigations on structural properties of CCDs. This will facilitate identifying modules and biosynthetic constraints that may affect the outcome of selection and thus provide a predictive framework for evolutionary trajectories of CCDs in plants and animals., The project was supported by the Graduate School ‘Evolutionary Networks: Organisms, Reactions, Molecules’ (E‐Norm) of the Heinrich‐Heine‐University, Düsseldorf, Germany, the Max Planck Society and the Deutsche Forschungsgemeinschaft (DFG JU 2856/1‐1 and DFG JU 2856/2‐2).

Transgenic crops expressing Bacillus thuringiensis (Bt) toxins have been widely and successfully deployed for the control of target pests, while allowing a substantial reduction in insecticide use. The evolution of resistance (a heritable decrease in susceptibility to Bt toxins) can pose a threat to sustained control of target pests, but a high‐dose refuge (HDR) management strategy has been key to delaying countervailing evolution of Bt resistance. The HDR strategy relies on the mating frequency between susceptible and resistant individuals, so either partial dominance of resistant alleles or nonrandom mating in the pest population itself could elevate the pace of resistance evolution. Using classic Wright‐Fisher genetic models, we investigated the impact of deviations from standard refuge model assumptions on resistance evolution in the pest populations. We show that when Bt selection is strong, even deviations from random mating and/or strictly recessive resistance that are below the threshold of detection can yield dramatic increases in the pace of resistance evolution. Resistance evolution is hastened whenever the order of magnitude of model violations exceeds the initial frequency of resistant alleles. We also show that the existence of a fitness cost for resistant individuals on the refuge crop cannot easily overcome the effect of violated HDR assumptions. We propose a parametrically explicit framework that enables both comparison of various field situations and model inference. Using this model, we propose novel empiric estimators of the pace of resistance evolution (and time to loss of control), whose simple calculation relies on the observed change in resistance allele frequency.

Floral scent is a very important trait in plant evolution. Currently, little is known about the inheritance of floral scent in cowpea (Vigna unguiculata L.) or changes that might have occurred during its domestication. Therefore, we analysed scent volatiles and molecular markers in a population of 159 F7 recombinant inbred lines derived from a cross of a domesticated blackeye cowpea cultivar, ‘524B’ and a wild accession ‘219-01’. Using gas chromatography-mass spectrometry (GC–MS) 23 volatile compounds were identified that fall into five general functional categories. Twenty-two of the compounds displayed quantitative variation in the progeny, and a total of 63 QTLs influencing the amounts of these volatiles were mapped onto the cowpea genetic marker map. Although QTLs for volatile compounds putatively involved in cowpea flower scent were found on 9 of the 11 cowpea chromosomes, they were not evenly distributed with QTLs mainly clustered on LGs 1, LGs 2 and LG 4. Our results serve as a starting point for both more detailed analyses of complex scent biosynthetic pathways and the development of markers for marker-assisted breeding of scented rose varieties. (Less)

 Premise of study: The legume genus Vigna and close relatives have highly elaborated fl oral morphologies that involve the coiling, bending, and intricate connection of flparts. Banners, levers, platforms, and pumps have evolved that attract pollinators and then manipulate their movement. Given this three-dimensional fl oral complexity, the taxonomy of Vigna and relatives has been confounded by the study of mostly two-dimensional museum specimens. A molecular phylogenetic analysis was undertaken in the effort to resolve long-standing taxonomic questions centered on flmorphology.  Methods: The phylogenetic analysis included cpDNA trnK and nuclear ribosomal ITS/5.8S (ITS) sequence variation. The American species were comprehensively sampled and outgroups included Old World relatives.  Key results: The trnK and ITS data analyses concurred in resolving six well-supported clades of American Vigna that are most closely related to other American genera: Dolichopsis , Macroptilium , Mysanthus , Oryxis , Oxyrhynchus , Phaseolus , Ramirezella , and Strophostyles . These 14 American clades ranked here as genera are resolved as sister to a clade comprising the mainly Old World species of Vigna .  Conclusions: American Vigna clades were reassigned to the genera Ancistrotropis , Cochliasanthus , Condylostylis , Leptospron , Sigmoidotropis , and the newly described Helicotropis . Vigna sensu stricto in the Americas now includes relatively few and mostly pantropical species. Elaborate fl oral asymmetries are readily used to apomorphically diagnose nearly all of the American genera. The age estimates of the extant diversifi cation of the American and its Old World sister clade are approximately coeval at ca. 6 – 7 million yr, which belies much greater fl oral variation in the Americas.

A saturated solution of tetrazepam in Krebs-Ringer did not affect the contraction force of the isolated diaphragm in vitro significantly during indirect stimulation at frequencies from 10 to 50 Hz. An overdose of crystalline tetrazepam, added to the bath (Krebs-Ringer solution) induced an increase of contraction force of the tetanus at various frequencies, with a maximum at 30 Hz, up to 400% ± 30 (n=4) of the control value. It is suggested that the solubility of tetrazepam in Krebs-Ringer solution is increased by substances released from the muscle. At a concentration of 10–4 M tetrazepam in Tween 80 (final concentration 0.25%), a comparable increase in contraction force occurred at indirect stimulation with 30 Hz. The maxima occurred at about one hour after exposure and were followed by a gradual decrease. At a stimulation frequency of 70 Hz, a gradual decrease in contraction force of 68% (± 3) (n=4) occurred after 2.5 hours, while the control force (in Tween 80, 0.25% - in order to enhance the solubility of tetrazepam) decreased with 18% (± 6). At a concentration of 10–5 M, tetrazepam caused an increase in contraction force to about 150% (± 6) at 30 Hz (first stimulation of each cycle), and significant decrease in contraction force of about 20% at 70 Hz. At direct stimulation with 30 Hz the tetanic contraction force was increased as well by 10–4 M tetrazepam, whereas at 10–3 M of the benzodiazepine the force was depressed. These in vitro results fit with the muscle relaxation mentioned in a case report (two times 100 mg dose) in relation to 50 mg doses resulting in plasma level with a peak of about 2×10–6 M reported earlier (1). The results of the study tentatively suggest that the use of tetrazepam in the appropriate dose is more favourable than using diazepam in treating spasms associated with lumbago.

Diazepam, midazolam and clonazepam were examined at concentrations varying from 3.10–5 to 3.10–4 M. In the isolated rat sciatic nerve preparation all compounds produced significant time- and concentration-dependent inhibition of evoked action potentials. With increasing time intervals the response became increasingly concentration-dependent. Concentrations of 3.10–5 M of midazolam or clonazepam - and diazepam, at the time intervals up to 24 min, to a lesser extent - produced a slight increase of the amplitude. The time-response curves of diazepam tended to flatten between 24 and 60 min. Clonazepam, after eliciting intitial increase at 6.10–5 M, reduced the action potentials only in the range of l.l0–4 to 3.10–4 M. The latter reduction was time-dependent in a significant way at concentrations of 3.10–4 M. The Emax values of the benzodiazepines were increased progressively with the exposure time, i.e. that of diazepam > midazolam > clonazepam. It is concluded that, in the concentrations studied, benzodiazepines have direct time-dependent blocking actions on nerve conduction in isolated motor nerves - involving ion channel currents - those of diazepam being the most potent.

Diazepam, 1×10−4 M, at frequencies of 10–50 Hz, significantly enhanced the tetanic contraction force (maximum effect 226%±30.1 in the 2nd cycle at 40 Hz) in the phrenic nerve-diaphragm preparation, except at 50 Hz. [One experimental cycle is defined as 5 subsequent stimulations at frequencies of 10, 20, 30, 40 and 50 Hz respectively, during 3 sec with intervals of 20 sec.] The enhancement in each cycle proceeded in two steps, i.e. an initial abrupt increase, followed by gradual abatement at higher frequencies. The maximum enforcement gradually decreased to 126%±17.5 in the 6th cycle at 30 Hz. PK 11195 (10−5 M) antagonized the enhancement, which eventually became biphasic in shape, i.e. initial enhancement of tetanic contractions followed by reduction of enhancement and subsequent suppression in the 1st and 2nd cycles. In the 3rd to 6th cycle only suppression of muscle contractions was observed. Diazepam, 2×10−4 M, induced an abrupt initial enhancement of contraction force (maximum 313%±24.0 in the 2nd cycle at 30 Hz), followed by suppression. A two-step response curve was only present in the 1st cycle. In the 5th and 6th cycles, at all frequencies employed, exclusive suppression of tetanic contractions was observed. PK 11195 (10−5 M) significantly antagonized the potentiation of the tetanic contraction force induced by 2×10−4 M diazepam. Only in the 1st cycle a biphasic response was observed. From the 2nd cycle onward the suppression induced by this concentration was intensified by PK 11195. In conclusion, responses to diazepam are dependent on its concentration, the stimulation frequency and the time of exposure. It is feasible that peripheral benzodiazepine receptors are involved in the effects of diazepam at the neuromuscular junction. © 1997 John Wiley & Sons, Ltd.

Doses of 100, 150 and 200 micrograms kg-1 of the cholinesterase inhibitor neostigmine reverse the anaesthetic action of ketamine. The antagonistic effect is increased as the dose is increased. The duration of anaesthesia induced by pentobarbitone is reversed by the cholinesterase inhibitor in doses of 150, 200 and 250 micrograms kg-1. Choline, in a dose of 50 mg kg-1, significantly antagonizes the action of the two anaesthetics, whereas hemicholinium-3, an inhibitor of the uptake of choline and the synthesis of acetylcholine, markedly potentiates their action. Dexamethasone induces a significant reduction of the duration of anaesthesia produced by ketamine and pentobarbitone. The potentiation of the anaesthetic effect caused by hemicholinium-3 is also reversed by dexamethasone. The acetylcholine content in rat cerebral cortex is increased after treatment with ketamine and pentobarbitone. Measurements of the course of the plasma level of pentobarbitone do not reveal alterations in the pharmacokinetic profile by either neostigmine or dexamethasone. These results indicate that central cholinergic systems may somehow be involved in the anaesthesia induced by ketamine and pentobarbitone and that the interactions described in this paper may be the result of modification by neostigmine and dexamethasone of the alterations in cholinergic activity caused by the two anaesthetics.