Nematode homologs of the sour taste receptor Otopetrin1 are evolutionarily conserved acid-sensitive proton channels

Numerous taste receptors and related molecules have been identified in vertebrates and invertebrates. Otopetrin1 has recently been identified as mammalian sour taste receptor which is essential for acid sensation. However, whether other Otopetrin proteins are involved in PH-sensing remains unknown. In C. elegans, there are eight otopetrin homologous genes but their expression patterns and functions have not been reported so far. Through heterologous expression in HEK293T cells, we found that ceOTOP1a can be activated by acid in NMDG⁺ solution without conventional cations, which generated inward currents and can be blocked by zinc ions. Moreover, we found that Otopetrin channels are widely expressed in numerous tissues, especially in sensory neurons in the nematode. These results suggest that the biophysical characteristics of the Otopetrin channels in nematodes are generally conserved. However, a series of single gene mutations of otopetrins, which were constructed by CRISPR-Cas9 method, did not affect either calcium responses in ASH polymodal sensory neurons to acid stimulation or acid avoidance behaviors, suggesting that Otopetrin channels might have diverse functions among species. This study reveals that nematode Otopetrins are evolutionarily conserved acid-sensitive proton channels, and provides a framework for further revealing the function and mechanisms of Otopetrin channels in both invertebrates and vertebrates.

Localization of TRPV3/4 and PIEZO1/2 sensory receptors in murine and human larynges

Objective

The primary aim of this study was to identify expression of TRPV3 and TRPV4 chemoreceptors across perinatal and adult stages using a murine model with direct comparisons to human laryngeal mucosa. Our secondary aim was to establish novel cell expression patterns of mechanoreceptors PIEZO1 and PIEZO2 in human tissue samples.

Study design

In vivo.

Methods

We harvested murine laryngeal tissue to localize and describe TRPV3/4 endogenous protein expression patterns via immunofluorescence analyses across two developmental (E16.5, P0) and adult (6 weeks) timepoints. Additionally, we obtained a 60-year-old female larynx including the proximal trachea and esophagus to investigate TRPV3/4 and PIEZO1/2 protein expression patterns via immunofluorescence analyses for comparison to murine adult tissue.

Results

Murine TRPV3/4 expression was noted at E16.5 with epithelial cell colocalization to supraglottic regions of the arytenoids, aryepiglottic folds and epiglottis through to birth (P0), extending to the adult timepoint. Human TRPV3/4 protein expression was most evident to epithelium of the arytenoid region, with additional expression of TRPV3 and TRPV4 to proximal esophageal and tracheal epithelium, respectively. Human PIEZO1 expression was selective to differentiated, stratified squamous epithelia of the true vocal fold and esophagus, while PIEZO2 expression exhibited selectivity for intermediate and respiratory epithelia of the false vocal fold, ventricles, subglottis, arytenoid, and trachea.

Conclusion

Results exhibited expression of TRPV3/4 chemoreceptors in utero, suggesting their importance during fetal/neonatal stages. TRPV3/4 and PIEZO1/2 were noted to adult murine and human laryngeal epithelium. Data indicates conservation of chemosensory receptors across species given similar regional expression in both the murine and human larynx.

Microbiome First Approaches to Rescue Public Health and Reduce Human Suffering

The is a sequential article to an initial review suggesting that Microbiome First medical approaches to human health and wellness could both aid the fight against noncommunicable diseases and conditions (NCDs) and help to usher in sustainable healthcare. This current review article specifically focuses on public health programs and initiatives and what has been termed by medical journals as a catastrophic record of recent failures. Included in the review is a discussion of the four priority behavioral modifications (food choices, cessation of two drugs of abuse, and exercise) advocated by the World Health Organization as the way to stop the ongoing NCD epidemic. The lack of public health focus on the majority of cells and genes in the human superorganism, the microbiome, is highlighted as is the "regulatory gap" failure to protect humans, particularly the young, from a series of mass population toxic exposures (e.g., asbestos, trichloroethylene, dioxin, polychlorinated biphenyls, triclosan, bisphenol A and other plasticizers, polyfluorinated compounds, herbicides, food emulsifiers, high fructose corn syrup, certain nanoparticles, endocrine disruptors, and obesogens). The combination of early life toxicity for the microbiome and connected human physiological systems (e.g., immune, neurological), plus a lack of attention to the importance of microbial rebiosis has facilitated rather than suppressed, the NCD epidemic. This review article concludes with a call to place the microbiome first and foremost in public health initiatives as a way to both rescue public health effectiveness and reduce the human suffering connected to comorbid NCDs.

Phytochrome B links the environment to transcription

Phytochrome B (phyB) senses the difference between darkness and light, the level of irradiance, the red/far-red ratio, and temperature. Thanks to these sensory capacities, phyB perceives whether plant organs are buried in the soil, exposed to full sunlight, in the presence of nearby vegetation, and/or under risk of heat stress. In some species, phyB perceives seasonal daylength cues. phyB affects the activity of several transcriptional regulators either by direct physical interaction or indirectly by physical interaction with proteins involved in the turnover of transcriptional regulators. Typically, interaction of a protein with phyB has either negative or positive effects on the interaction of the latter with a third party, this being another protein or DNA. Thus, phyB mediates the context-dependent modulation of the transcriptome underlying changes in plant morphology, physiology, and susceptibility to biotic and abiotic stress. phyB operates as a dynamic switch that improves carbon balance, prioritizing light interception and photosynthetic capacity in open places and the projection of the shoot towards light in the soil, under shade and in warm conditions.

Topography of sensory receptors within the human glenohumeral joint capsule

BACKGROUND AND HYPOTHESES

Sensory receptors in the joint capsule are critical for maintaining joint stability. However, the distribution of sensory receptors in the glenohumeral joint of the shoulder, including mechanoreceptors and free nerve endings, has not been described yet. This study aimed to describe the distributions of different sensory receptor subtypes in the glenohumeral joint capsule. Our hypotheses were as follows: (1) Sensory receptor subtypes would differ in density but follow a similar distribution pattern, and (2) the anterior capsule would have the highest density of sensory receptors.

METHODS

Six glenohumeral joint capsules were harvested from the glenoid to the humeral attachment. The capsule was divided into 4 regions of interest (anterior, posterior, superior, and inferior) and analyzed using modified gold chloride stain. Sensory receptors as well as free nerve endings were identified and counted under a light microscope from sections of each region of interest. The density of each sensory receptor subtype was calculated relative to capsule volume.

RESULTS

Sensory receptors were distributed in the glenohumeral joint capsule with free nerve endings. The anterior capsule exhibited the highest median density of all 4 sensory receptors examined, followed by the superior, inferior, and posterior capsules. The median densities of these sensory receptor subtypes also significantly differed (P = .007), with type I (Ruffini corpuscles) receptors having the highest density (2.97 U/cm³), followed by type IV (free nerve endings, 2.25 U/cm³), type II (Pacinian corpuscles, 1.40 U/cm³), and type III (Golgi corpuscles, 0.24 U/cm³) receptors.

CONCLUSION

Sensory receptor subtypes are differentially expressed in the glenohumeral joint capsule, primarily type I and IV sensory receptors. The expression of sensory receptors was dominant in the anterior capsule, stressing the important role of proprioception feedback for joint stability. The surgical procedure for shoulder instability should consider the topography of sensory receptors to preserve or restore the proprioception of the shoulder joint.

Ultrastructure of the rhyncheal apparatus and other structures of the scolex of Grillotia (Christianella) carvajalregorum (Cestoda: Trypanorhyncha)

The scolex ultrastructure was studied in Grillotia (Christianella) carvajalregorum (Cestoda: Trypanorhyncha) using histochemistry and transmission electron microscopy. We show for the first time the presence of scolex glands arranged in two longitudinal acini at the pars vaginalis parenchyma. These glands, along with those scattered in bothrial parenchyma, produce potentially adhesive glycoprotein secretions that are discharged via ducts to the bothrial grooves and apex. A particular type of sensory receptor was found around frontal gland pores, with a possible function in regulating their secretion activity. The internal structure of microtriches varies according to their morphotype and distribution on the scolex, this study providing the first description of the ultrastructure of serrate lanceolate spinitriches. The projections that form serrate margins are an extension of the medulla, differing from similar projections of other spinitriches. The large caps observed in serrate lanceolate spinitriches may reflect their specialization in attachment to and abrasion of intestinal mucosa, while the short caps and large bases of acicular filitriches may reflect their involvement in nutrient absorption. We also describe the rhyncheal apparatus ultrastructure, showing a similar basic structure of tentacular walls than that of other trypanorhynchs. Some differences among species in the number of fibrous layers, composition of the apical cytoplasm and presence of microvilli-like projections were discussed. Finally, our study describes in detail the internal ultrastructure of hollow hooks, evidencing the presence of cytoplasm, mitochondria and fibrils. The location of these fibrils may increase the area of contact surface of hooks on tentacles, possibly allowing for a higher tensile strength than that of solid hooks. We consider that gland location and shape, composition of tentacular wall layers, and hook internal structure may serve as useful characters for the taxonomy and phylogeny of Trypanorhyncha. RESEARCH HIGHLIGHTS: This is the first description of scolex internal ultrastructure in Grillotia carvajalregorum, showing the presence of glands arranged in two longitudinal acini at the pars vaginalis parenchyma, with potentially adhesive functions. The internal ultrastructure of serrate lanceolate spinitriches and acicular filitriches may reflect their specialization in attachment to the host intestinal mucosa and their involvement in nutrient absorption, respectively. Internally, hollow hooks have cytoplasm with mitochondria and fibrils, which are more widely distributed than in solid hooks, possibly increasing their tensile strength.

A Comparison of the Primary Sensory Neurons Used in Olfaction and Vision

Vision, hearing, smell, taste, and touch are the tools used to perceive and navigate the world. They enable us to obtain essential resources such as food and highly desired resources such as mates. Thanks to the investments in biomedical research the molecular unpinning’s of human sensation are rivaled only by our knowledge of sensation in the laboratory mouse. Humans rely heavily on vision whereas mice use smell as their dominant sense. Both modalities have many features in common, starting with signal detection by highly specialized primary sensory neurons—rod and cone photoreceptors (PR) for vision, and olfactory sensory neurons (OSN) for the smell. In this chapter, we provide an overview of how these two types of primary sensory neurons operate while highlighting the similarities and distinctions.

The Roles of Autoimmunity and Biotoxicosis in Sick Building Syndrome as a "Starting Point" for Irreversible Dampness and Mold Hypersensitivity Syndrome

BACKGROUND

The terminology of "sick building syndrome" (SBS), meaning that a person may feel sick in a certain building, but when leaving the building, the symptoms will reverse, is imprecise. Many different environmental hazards may cause the feeling of sickness, such as high indoor air velocity, elevated noise, low or high humidity, vapors or dust. The Aim: To describe SBS in connection with exposure to indoor air dampness microbiota (DM). Methods: A search through Medline/Pubmed. Results and Conclusions: Chronic course of SBS may be avoided. By contrast, persistent or cumulative exposure to DM may make SBS potentially life-threatening and lead to irreversible dampness and mold hypersensitivity syndrome (DMHS). The corner feature of DMHS is acquired by dysregulation of the immune system in the direction of hypersensitivities (types I-IV) and simultaneous deprivation of immunity that manifests as increased susceptibility to infections. DMHS is a systemic low-grade inflammation and a biotoxicosis. There is already some evidence that DMHS may be linked to autoimmunity. Autoantibodies towards, e.g., myelin basic protein, myelin-associated glycoprotein, ganglioside GM1, smooth muscle cells and antinuclear autoantibodies were reported in mold-related illness. DMHS is also a mitochondropathy and endocrinopathy. The association of autoimmunity with DMHS should be confirmed through cohort studies preferably using chip-based technology.

Neuroanatomical distribution of sensory receptors in the human elbow joint capsule

BACKGROUND

The topographic arrangement of sensory receptors in the human elbow joint capsule is pertinent to their role in the transmission of neural signals. The signals from stimuli in the joint are concisely delivered via afferent pathways to allow recognition of pain and proprioception. Sensory receptors in the elbow joint include mechanoreceptors and free nerve endings acting as nociceptors, although the distribution of each of the structures has not been determined, despite their importance for the integrity of the joint. We therefore aimed to investigate the neuroanatomical distribution and densities of mechanoreceptors and free nerve endings in the capsule of the elbow, at the same time as considering surgical approaches that would result in the minimum insult to them.

METHODS

Four elbow joint capsules were harvested from fresh cadavers. The specimens were carefully separated from adjacent osteoligamentous attachments and the capsular complex was stained with a modified gold chloride method. Evaluations of free nerve endings, and Golgi, Ruffini and Pacinian corpuscles were performed under an inverted light microscope. The number and density of each structure were recorded.

RESULTS

Ruffini corpuscles observed to be the dominant mechanoreceptor type. No Golgi corpuscle was observed. Free nerve endings were found at the highest density at posterodistal sites, whereas mechanoreceptors were most frequent at bony attachment sites.

CONCLUSIONS

A consistent distribution pattern of articular sensory receptors was observed, which allows further understanding of elbow pathology. An awareness of the neuroanatomical distribution of sensory receptors in the elbow joint capsule may allow their preservation during surgical procedures for elbow joint pathology.

The ins and outs of the Arf4-based ciliary membrane-targeting complex

The small GTPase Arf4-based ciliary membrane-targeting complex recognizes specific targeting signals within sensory receptors and regulates their directed movement to primary cilia. Activated Arf4 directly binds the VxPx ciliary-targeting signal (CTS) of the light-sensing receptor rhodopsin. Recent findings revealed that at the trans-Golgi, marked by the small GTPase Rab6, activated Arf4 forms a functional complex with rhodopsin and the Arf guanine nucleotide exchange factor (GEF) GBF1, providing positive feedback that drives further Arf4 activation in ciliary trafficking. Arf4 function is conserved across diverse cell types; however, it appears that not all its aspects are conserved across species, as mouse Arf4 is a natural mutant in the conserved α3 helix, which is essential for its interaction with rhodopsin. Generally, activated Arf4 regulates the assembly of the targeting nexus containing the Arf GAP ASAP1 and the Rab11a-FIP3-Rabin8 dual effector complex, which controls the assembly of the highly conserved Rab11a-Rabin8-Rab8 ciliary-targeting module. It was recently found that this module interacts with the R-SNARE VAMP7, likely in its activated, c-Src-phosphorylated form. Rab11 and Rab8 bind VAMP7 regulatory longin domain (LD), whereas Rabin8 interacts with the SNARE domain, capturing VAMP7 for delivery to the ciliary base and subsequent pairing with the cognate SNAREs syntaxin 3 and SNAP-25. This review will focus on the implications of these novel findings that further illuminate the role of well-ordered Arf and Rab interaction networks in targeting of sensory receptors to primary cilia. Abbreviations: CTS: Ciliary-Targeting Signal; GAP: GTPase Activating Protein; GEF: Guanine Nucleotide Exchange Factor; RTC(s), Rhodopsin Transport Carrier(s); SNARE: Soluble N-ethylmaleimide-sensitive Factor Attachment Protein Receptor; TGN: Trans-Golgi Network.

New data on the nervous system of Cercaria parvicaudata Stunkard & Shaw, 1931 (Trematoda: Renicolidae): revisiting old hypotheses

Data on the interposition of the immunoreactive nerve cords in Cercaria parvicaudata Stunkard & Shaw, 1931 (Trematoda: Renicolidae) and its chaetotaxy were obtained. The nervous system of C. parvicaudata was described using immunostaining of 5-hydroxytryptamine and FMRFamide immunoreactive nerve elements. The morphology and distribution of sensory receptors were analysed using scanning electron microscopy and the silver nitrate impregnation technique. Our integrated approach to the study of the nervous system revealed a clear colocalization of surface papillae with nerve cords and commissures in C. parvicaudata. The structure of the nervous system in C. parvicaudata differs partly from the classical model that defines the entire nomenclature of chaetotaxy.

Role of TRPV1 in acupuncture modulation of reflex excitatory cardiovascular responses

We have shown that acupuncture, including manual and electroacupuncture (MA and EA), at the P5-6 acupoints stimulates afferent fibers in the median nerve (MN) to modulate sympathoexcitatory cardiovascular reflexes through central regulation of autonomic function. However, the mechanisms underlying acupuncture activation of these sensory afferent nerves and their cell bodies in the dorsal root ganglia (DRG) are unclear. Transient receptor potential vanilloid type 1 (TRPV1) is present in sensory nerve fibers distributed in the general region of acupoints like ST36 and BL 40 located in the hindlimb. However, the contribution of TRPV1 to activation of sensory nerves by acupuncture, leading to modulation of pressor responses, has not been studied. We hypothesized that TRPV1 participates in acupuncture's activation of sensory afferents and their associated cell bodies in the DRG to modulate pressor reflexes. Local injection of iodoresiniferatoxin (Iodo-RTX; a selective TRPV1 antagonist), but not 5% DMSO (vehicle), into the P6 acupoint on the forelimb reversed the MA's inhibition of pressor reflexes induced by gastric distension (GD). Conversely, inhibition of GD-induced sympathoexcitatory responses by EA at P5-6 was unchanged after administration of Iodo-RTX into P5-6. Single-unit activity of Group III or IV bimodal afferents sensitive to both mechanical and capsaicin stimuli responded to MA stimulation at P6. MA-evoked activity was attenuated significantly ( P < 0.05) by local administration of Iodo-RTX ( n = 12) but not by 5% DMSO ( n = 12) into the region of the P6 acupoint in rats. Administration of Iodo-RTX into P5-6 did not reduce bimodal afferent activity evoked by EA stimulation ( n = 8). Finally, MA at P6 and EA at P5-6 induced phosphorylation of extracellular signal-regulated kinases (ERK; an intracellular signaling messenger involved in cellular excitation) in DRG neurons located at C7-8 spinal levels receiving MN inputs. After TRPV1 was knocked down in the DRG at these spinal levels with intrathecal injection of TRPV1-siRNA, expression of phosphorylated ERK in the DRG neuron was reduced in MA-treated, but not EA-treated animals. These data suggest that TRPV1 in Group III and IV bimodal sensory afferent nerves contributes to acupuncture inhibition of reflex increases in blood pressure and specifically plays an important role during MA but not EA.

Short-term effect of kinesiology taping on temperature distribution at the site of application

The aim of the study was to assess skin temperature after short-term kinesiology tape application. Seventy-four healthy volunteers with no history of lower back pain participated in the study. Kinesiology tape was applied in the experimental group, and Matopat Classic adhesive tape was applied in the placebo group. Study participants wore the tape for four consecutive days and were then thermographically analyzed for changes in skin temperature. Examination of skin surface temperature distribution revealed a significantly lower temperature (mean decrease, 1.3°C P = .001 area1, 1.5°C P = .001 area2, 1.6 P = .008 area3) immediately after kinesiology tape the removal. One hour after removal of the tape, a statistically significant increase in temperature was observed over all three areas (mean increase, 0.9°C P = .025 area1, 1.0°C P = .0008 area2, 1.0 P = .011 area3). In group 2, there were no statistically significant temperature changes. Based on the findings, we determined that kinesiology taping may affect skin temperature at the site of application.

Gustatory Processing in Drosophila melanogaster

The ability to identify nutrient-rich food and avoid toxic substances is essential for an animal's survival. Although olfaction and vision contribute to food detection, the gustatory system acts as a final checkpoint control for food acceptance or rejection. The vinegar fly Drosophila melanogaster tastes many of the same stimuli as mammals and provides an excellent model system for comparative studies of taste detection. The relative simplicity of the fly brain and behaviors, along with the molecular genetic and functional approaches available in this system, allow the examination of gustatory neural circuits from sensory input to motor output. This review discusses the molecules and cells that detect taste compounds in the periphery and the circuits that process taste information in the brain. These studies are providing insight into how the detection of taste compounds regulates feeding decisions.

Innervation of the cerebral dura mater

The trigemino-cardiac reflex during Onyx embolization for dural arteriovenous fistula may be caused by mechanical or chemical stimulus to the terminals of the unencapsulated Ruffini-like receptors stemming from A-axons in the dural connective tissue at sites of dural arteries and sinuses. Slow A (Aδ) and fast A (Aβ) neurons may play a role in the stimulus afferent pathway due to their higher mechanosensitivity and chemosensitivity. These afferent pathway nerves are cholinergic innervations of the dura mater, which also contains vasoactive neuropeptides such as calcitonin gene-related peptide, substance P, and neurokinin A. Stimulation of meningeal sensory fibres can evoke cerebral vasodilation through the peripheral release of neuropeptides, which play a role in headache pathogenesis. These myelinated A-fibers terminate in the deep part (laminae III-V) of the spinal dorsal horn. Its efferent pathway has been defined as the acetylcholinergic vagus nerve. The A11 nucleus, located in the posterior hypothalamus, providing the only known source of descending dopaminergic innervation for the spinal grey matter, can inhibit the neurons in the spinal dorsal horn.

Spectrum of myelinated pulmonary afferents (II)

Recently, it has been recognized that a single airway sensory unit may contain multiple receptive fields and that each field houses at least one encoder. Since some units respond to both lung inflation and deflation, we hypothesized that these units contain heterogeneous encoders for sensing inflation and deflation, respectively. Single unit activities were recorded from the cervical vagus nerve in anesthetized, open chest, and mechanically ventilated rabbits. Fifty-two airway sensory units with multiple receptive fields that responded to both lung inflation and deflation were identified. Among them, 13 units had separate receptive fields for inflation and deflation, where one of the fields could be blocked by local injection of 2% lidocaine (10 μl). In 8 of the 13 units, the deflation response was blocked without affecting the unit's response to inflation, whereas in the remaining five units, the inflation response was blocked without affecting the deflation response. Our results support the hypothesis that a single mechanosensory unit may contain heterogeneous encoders that can respond to either inflation or deflation.

Developmental assembly of transduction apparatus in chick basilar papilla

Hair cells, the sensory receptors of auditory and vestibular systems, use a transducer apparatus that renders them remarkably sensitive to mechanical displacement as minute as 1 nm. To study the embryonic development of the transducer apparatus in hair cells of the chick auditory papilla, we examined hair cells that have been labeled with N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl) pyridiniumdibromide, which has been shown to permeate the transducer channels. In addition, mechanotransduction currents were recorded directly using whole-cell patch-clamp techniques. The structure of the hair bundle was examined using scanning electron microscopy, and immunofluorescence labeling for myosin 1c, myosin 7a, and plasma membrane Ca2+ ATPase 2 was studied to determine the developmental expression of these proteins in embryonic chick papillas. We demonstrate that the transducer apparatus is assembled jointly at embryonic day 11 (E11) of the developing chick basilar papilla. The resting open probability of the transducer channels was high at E12 (approximately 0.5) and remained substantially elevated at E14-16; it then declined to the mature value of approximately 0.15 at E21. The displacement sensitivity of the transduction apparatus, the gating force, increased from E12 to E21. Although the expression of different components of the transducer apparatus and the transduction current peaked at approximately E14-16, marked refinement occurred beyond E16. For example, myosin 1c appeared diffusely localized in hair bundles from E12 to E16, but subsequently consolidated into punctate pattern. The fine temporal and precise spatial assembly of the transducer apparatus likely contributes toward the exquisite sensitivity of the transduction ensemble.

Capsaicin and menthol in the treatment of itch and pain: recently cloned receptors provide the key

Topical capsaicin is reported to be an effective treatment for idiopathic intractable pruritus ani. While both capsaicin and menthol application produce a transient perianal burning sensation, only capsaicin relieves itching. Classical observations on functional desensitisation of nociceptors by capsaicin may explain the beneficial effects but the recent discovery of a range of receptors which respond to capsaicin, menthol, and temperature, and their expression in subsets of sensory nerve fibres, provides an exciting prospect towards advancing our understanding and treatment of sensory dysfunction.