Development of Nontargeted Workflow of Occupational Exposure by Infrared Ion Spectroscopy and Silicone Wristbands' Passive Sampling

A new approach using orthogonal analytical techniques is developed for chemical identification. High resolution mass spectrometry and infrared ion spectroscopy are applied through a 5-level confidence paradigm to demonstrate the effectiveness of nontargeted workflow for the identification of hazardous organophosphates. Triphenyl phosphate is used as a surrogate organophosphate for occupational exposure, and silicone wristbands are used to represent personal samplers. Spectral data of a target compound is combined with spectral data of the sodium adduct and quantum chemical calculations to achieve a confirmed identification. Here, we demonstrate a nontargeted workflow that identifies organophosphate exposure and provides a mechanism for selecting validated methods for quantitative analyses.

Space and patchiness affects diversity-function relationships in fungal decay communities

The space in which organisms live determines health and physicality, shaping the way in which they interact with their peers. Space, therefore, is critically important for species diversity and the function performed by individuals within mixed communities. The biotic and abiotic factors defined by the space that organisms occupy are ecologically significant and the difficulty in quantifying space-defined parameters within complex systems limits the study of ecological processes. Here, we overcome this problem using a tractable system whereby spatial heterogeneity in interacting fungal wood decay communities demonstrates that scale and patchiness of territory directly influence coexistence dynamics. Spatial arrangement in 2- and 3-dimensions resulted in measurable metabolic differences that provide evidence of a clear biological response to changing landscape architecture. This is of vital importance to microbial systems in all ecosystems globally, as our results demonstrate that community function is driven by the effects of spatial dynamics.

Activation of type-1 cannabinoid receptor shifts the balance between excitation and inhibition towards excitation in layer II/III pyramidal neurons of the rat prelimbic cortex

Activation of the endocannabinoid (eCB) system by exogenous cannabinoids (drug abuse) can alter the physiology of the brain circuits involved in higher-order cognitive functions such as the medial prefrontal cortex (mPFC). A proper balance between excitation and inhibition (E/I balance) is critical for neuronal network oscillations underlying cognitive functions. Since type-1 cannabinoid receptors (CB1Rs), expressed in many brain areas including the mPFC, can modulate excitatory and inhibitory neurotransmission, we aimed to determine whether CB1R activation results in modifications of the E/I balance. We first confirm the presence of functional presynaptic CB1Rs that can modulate both excitatory and inhibitory inputs to layer II/III pyramidal neurons of the prelimbic (PL) area of the mPFC. By decomposing the synaptic response evoked by layer I stimulation into its excitatory and inhibitory components, we show that in vitro CB1R activation with the cannabinoid receptor agonists WIN55,212-2 (WIN) and CP-55940 (CP) modulates the balance between excitation and inhibition (E/I balance) of layer II/III pyramidal neurons. This treatment caused a significant shift of the E/I balance towards excitation, from 18/82 % to 25/75 % (WIN) and from 17/83 to 30/70 % (CP). Finally, when animals were injected with a cannabinoid receptor agonist, we observed a shift of the E/I balance (measured in vitro) towards excitation 1 h after WIN (24/76 %) or after CP injection (30/70 %) when compared to vehicle-injected animals (18/82 %). This modulation of the E/I balance by CB1Rs may thus be fundamental in the regulation of local PL cortical network excitability and could be the mechanism through which excessive CB1R activation (cannabis abuse) affects cognitive functions.

Endocannabinoids produced upon action potential firing evoke a Cl(-) current via type-2 cannabinoid receptors in the medial prefrontal cortex

The functional presence of type-2 cannabinoid receptors (CB2Rs) in layer II/III pyramidal neurons of the rat medial prefrontal cortex (mPFC) was recently demonstrated. In the present study, we show that the application of the endocannabinoids (eCBs) 2-arachidonoylglycerol (2-AG) and methanandamide [a stable analog of the eCB anandamide (AEA)] can activate CB2Rs of mPFC layer II/III pyramidal neurons, which subsequently induces a Cl(-) current. In addition, we show that action potential (AP) firing evoked by 20-Hz current injections results in an eCB-mediated opening of Cl(-) channels via CB2R activation. This AP-evoked synthesis of eCBs is dependent on the Ca(2+) influx through N-type voltage-gated calcium channels. Our results indicate that 2-AG is the main eCB involved in this process. Finally, we demonstrate that under physiologically relevant intracellular Cl(-) conditions, 20-Hz AP firing leads to a CB2R-dependent reduction in neuronal excitability. Altogether, our data indicate that eCBs released upon action potential firing can modulate, through CB2R activation, neuronal activity in the mPFC. We discuss how this may be a mechanism to prevent excessive neuronal firing.