External Sensory Organs Research Articles

Minding the gut: extending embodied cognition and perception to the gut complex.

Scientific and philosophical accounts of cognition and perception have traditionally focused on the brain and external sense organs. The extended view of embodied cognition suggests including other parts of the body in these processes. However, one organ has often been overlooked: the gut. Frequently conceptualized as merely a tube for digesting food, there is much more to the gut than meets the eye. Having its own enteric nervous system, sometimes referred to as the "second brain," the gut is also an immune organ and has a large surface area interacting with gut microbiota. The gut has been shown to play an important role in many physiological processes, and may arguably do so as well in perception and cognition. We argue that proposals of embodied perception and cognition should take into account the role of the "gut complex," which considers the enteric nervous, endocrine, immune, and microbiota systems as well as gut tissue and mucosal structures. The gut complex is an interface between bodily tissues and the "internalized external environment" of the gut lumen, involved in many aspects of organismic activity beyond food intake. We thus extend current embodiment theories and suggest a more inclusive account of how to "mind the gut" in studying cognitive processes.

The central regulatory circuit in the gene network controlling the morphogenesis of Drosophila mechanoreceptors: an <i>in silico</i> analysis

The central regulatory circuit in the gene network controlling the morphogenesis of Drosophila mechanoreceptors: an <i>in silico</i> analysis

The retrograde IFT dynein is required for normal function of diverse mechanosensory cilia in Drosophila.

Cilia biogenesis relies on intraflagellar transport (IFT), a conserved transport mechanism which functions bi-directionally to bring protein complexes to the growing ciliary tip and recycle signaling and transport proteins between the cilium and cell body. In Drosophila, anterograde IFT is critical for assembly of sensory cilia in the neurons of both chordotonal (ch) organs, which have relatively long ciliary axonemes, and external sensory (es) organs, which have short axonemal segments with microtubules in distal sensory segments forming non-axonemal bundles. We previously isolated the beethoven (btv) mutant in a mutagenesis screen for auditory mutants. Although many btv mutant flies are deaf, some retain a small residual auditory function as determined both by behavior and by auditory electrophysiology. Here we molecularly characterize the btv gene and demonstrate that it encodes the IFT-associated dynein-2 heavy chain Dync2h1. We also describe morphological changes in Johnston's organ as flies age to 30 days, and we find that morphological and electrophysiological phenotypes in this ch organ of btv mutants become more severe with age. We show that NompB protein, encoding the conserved IFT88 protein, an IFT complex B component, fails to be cleared from chordotonal cilia in btv mutants, instead accumulating in the distorted cilia. In macrochaete bristles, a class of es organ, btv mutants show a 50% reduction in mechanoreceptor potentials. Thus, the btv-encoded Dync2h1 functions as the retrograde IFT motor in the assembly of long ciliary axonemes in ch organs and is also important for normal function of the short ciliary axonemes in es organs.

Crustacean leg regeneration restores complex microanatomy and cell diversity.

Animals can regenerate complex organs, yet this process frequently results in imprecise replicas of the original structure. In the crustacean Parhyale, embryonic and regenerating legs differ in gene expression dynamics but produce apparently similar mature structures. We examine the fidelity of Parhyale leg regeneration using complementary approaches to investigate microanatomy, sensory function, cellular composition, and cell molecular profiles. We find that regeneration precisely replicates the complex microanatomy and spatial distribution of external sensory organs and restores their sensory function. Single-nuclei sequencing shows that regenerated and uninjured legs are indistinguishable in terms of cell-type composition and transcriptional profiles. This remarkable fidelity highlights the ability of organisms to achieve identical outcomes via distinct processes.

It takes Two: Discovery of Spider Pax2 Duplicates Indicates Prominent Role in Chelicerate Central Nervous System, Eye, as Well as External Sense Organ Precursor Formation and Diversification After Neo- and Subfunctionalization

Paired box genes are conserved across animals and encode transcription factors playing key roles in development, especially neurogenesis.Pax6is a chief example for functional conservation required for eye development in most bilaterian lineages except chelicerates.Pax6is ancestrally linked and was shown to have interchangeable functions withPax2.Drosophila melanogaster Pax2plays an important role in the development of sensory hairs across the whole body. In addition, it is required for the differentiation of compound eyes, making it a prime candidate to study the genetic basis of arthropod sense organ development and diversification, as well as the role of Pax genes in eye development. Interestingly, in previous studies identification of cheliceratePax2was either neglected or failed. Here we report the expression of twoPax2orthologs in the common house spiderParasteatoda tepidariorum, a model organism for chelicerate development. The twoPax2orthologs most likely arose as a consequence of a whole genome duplication in the last common ancestor of spiders and scorpions.Pax2.1is expressed in the peripheral nervous system, including developing lateral eyes and external sensilla, as well as the ventral neuroectoderm ofP. tepidariorumembryos. This not only hints at a conserved dual role ofPax2/5/8orthologs in arthropod sense organ development but suggests that in chelicerates,Pax2could have acquired the role usually played byPax6. For the other paralog,Pt-Pax2.2, expression was detected in the brain, but not in the lateral eyes and the expression pattern associated with sensory hairs differs in timing, pattern, and strength. To achieve a broader phylogenetic sampling, we also studied the expression of bothPax2genes in the haplogyne cellar spiderPholcus phalangioides. We found that the expression difference between paralogs is even more extreme in this species, sincePp-Pax2.2shows an interesting expression pattern in the ventral neuroectoderm while the expression in the prosomal appendages is strictly mesodermal. This expression divergence indicates both sub- and neofunctionalization afterPax2duplication in spiders and thus presents an opportunity to study the evolution of functional divergence after gene duplication and its impact on sense organ diversification.

SIGNIFICANCE OF ULTRASONOGRAPHY IN EVALUATION OF VITREORETINAL PATHOLOGY

INTRODUCTION:Vitreoretinal pathologies include vitreal haemmorhage and vitreal detachment, retinal detachment, retinoblastoma, diabetic retinopathy, leukocoria, trauma over eye. The eye being an external sense organ lends itself to an easy and rapid examination of anterior segment but structure posterior to the papillary plane i.e lens, vitreous cavity and humor, retina, choroid in an opaque media could not be evaluated by just fundus examination. OBJECTIVES OF RESEARCH: Demographic prole of patient with vitreoretinal pathologies. Diagnose the patient with vitreoretinal pathologies by ultrasonography. Detect and characterize the vitreoretinal pathologies by ultrasonography, clinical ndings and post management conrmatory ndings to establish the diagnostic accuracy of ultrasonography in vitreoretinal pathologies. MATERIALAND METHOD: Study design:Institution based prospective, descriptive study Study setting: USG section at Dept. of Radiodiagnosis, Medical College, Kolkata Place of study: Dept. of Radiodiagnosis, Medical College, Kolkata Period of study:January 2018 to august 2019 Study population:Referred patient from regional institute of opthalmology Sample size: 50 patients. RESULT AND ANALYSIS: We showed that 29(48.3%0 patients had vitreous haemorrhage. 19(31.7%) patients had retinal detachment. 10(16.7%) patients had posterior vitreous detachment. 7(11.7%) patients had endophthalmitis. 9(15.0%) patients had retinoblastoma. 1(1.7%) patients had PHPV. 1(1.7%) patients had asteroid hyalosis. 1(1.7%) patients had retinoschisis. 5(8.3%) patients had normal. SUMMARYAND CONCLUSION: From, the present study it was noted that Ultrasonography is very efcient tool in diagnosing various ocular abnormalities. Ultrasonography can categorize the lesions in the posterior chamber well, depending on the echotexture and anatomy. Even the exact location of the lesion and surrounding structures can be well made out. Ultrasonography can detect structural changes that were missed or could not be detected by clinical examination especially with opaque media as well. Ultrasonography is proved to be very useful diagnostic tool in detection and evaluation of vitreo-retinal pathologies in patients with opacities in the vitreous cavity.

Identification, Characterization and Expression Analysis of TRP Channel Genes in the Vegetable Pest, Pieris rapae.

Transient receptor potential (TRP) channels are critical for insects to detect environmental stimuli and regulate homeostasis. Moreover, this superfamily has become potential molecular targets for insecticides or repellents. Pieris rapae is one of the most common and widely spread pests of Brassicaceae plants. Therefore, it is necessary to study TRP channels (TRPs) in P. rapae. In this study, we identified 14 TRPs in P. rapae, including two Water witch (Wtrw) genes. By contrast, only one Wtrw gene exists in Drosophila and functions in hygrosensation. We also found splice isoforms of Pyrexia (Pyx), TRPgamma (TRPγ) and TRP-Melastatin (TRPM). These three genes are related to temperature and gravity sensation, fine motor control, homeostasis regulation of Mg2+ and Zn2+ in Drosophila, respectively. Evolutionary analysis showed that the TRPs of P. rapae were well clustered into their own subfamilies. Real-time quantitative PCR (qPCR) showed that PrTRPs were widely distributed in the external sensory organs, including antennae, mouthparts, legs, wings and in the internal physiological organs, including brains, fat bodies, guts, Malpighian tubules, ovaries, as well as testis. Our study established a solid foundation for functional studies of TRP channels in P. rapae, and would be benefit to developing new approaches to control P. rapae targeting these important ion channels.

Distribution and development of the external sense organ pattern on the appendages of postembryonic and adult stages of the spider Parasteatoda tepidariorum

Spiders are equipped with a large number of innervated cuticular specializations, which respond to various sensory stimuli. The physiological function of mechanosensory organs has been analysed in great detail in some model spider species (e.g. Cupiennius salei); however, much less is known about the distribution and function of chemosensory organs. Furthermore, our knowledge on how the sense organ pattern develops on the spider appendages is limited. Here we analyse the development of the pattern and distribution of six different external mechano- and chemosensory organs in all postembryonic stages and in adult male and female spiders of the species Parasteatoda tepidariorum. We show that except for small mechanosensory setae, external sense organs appear in fixed positions on the pedipalps and first walking legs, arranged in longitudinal rows along the proximal-distal axis or in invariable positions relative to morphological landmarks (joints, distal tarsal tip). A comparison to other Entelegynae spiders shows that these features are conserved. We hope that this study lays the foundation for future molecular analysis to address the question how this conserved pattern is generated.

Expression of a human variant of CHMP2B linked to neurodegeneration in Drosophila external sensory organs leads to cell fate transformations associated with increased Notch activity.

Proper function of cell signaling pathways is dependent upon regulated membrane trafficking events that lead to the endocytosis, recycling, and degradation of cell surface receptors. The endosomal complexes required for transport (ESCRT) genes play a critical role in the sorting of ubiquitinated cell surface proteins. CHMP2BIntron5 , a truncated form of a human ESCRT-III protein, was discovered in a Danish family afflicted by a hereditary form of frontotemporal dementia (FTD). Although the mechanism by which the CHMP2B mutation in this family causes FTD is unknown, the resulting protein has been shown to disrupt normal endosomal-lysosomal pathway function and leads to aberrant regulation of signaling pathways. Here we have misexpressed CHMP2BIntron5 in the developing Drosophila external sensory (ES) organ lineage and demonstrate that it is capable of altering cell fates. Each of the cell fate transformations seen is compatible with an increase in Notch signaling. Furthermore, this interpretation is supported by evidence that expression of CHMP2BIntron5 in the notum environment is capable of raising the levels of Notch signaling. As such, these results add to a growing body of evidence that CHMP2BIntron5 can act rapidly to disrupt normal cellular function via the misregulation of critical cell surface receptor function.

Shaping of Drosophila Neural Cell Lineages Through Coordination of Cell Proliferation and Cell Fate by the BTB-ZF Transcription Factor Tramtrack-69.

Cell diversity in multicellular organisms relies on coordination between cell proliferation and the acquisition of cell identity. The equilibrium between these two processes is essential to assure the correct number of determined cells at a given time at a given place. Using genetic approaches and correlative microscopy, we show that Tramtrack-69 (Ttk69, a Broad-complex, Tramtrack and Bric-à-brac - Zinc Finger (BTB-ZF) transcription factor ortholog of the human promyelocytic leukemia zinc finger factor) plays an essential role in controlling this balance. In the Drosophila bristle cell lineage, which produces the external sensory organs composed by a neuron and accessory cells, we show that ttk69 loss-of-function leads to supplementary neural-type cells at the expense of accessory cells. Our data indicate that Ttk69 (1) promotes cell cycle exit of newborn terminal cells by downregulating CycE, the principal cyclin involved in S-phase entry, and (2) regulates cell-fate acquisition and terminal differentiation, by downregulating the expression of hamlet and upregulating that of Suppressor of Hairless, two transcription factors involved in neural-fate acquisition and accessory cell differentiation, respectively. Thus, Ttk69 plays a central role in shaping neural cell lineages by integrating molecular mechanisms that regulate progenitor cell cycle exit and cell-fate commitment.

Convergence of monosynaptic and polysynaptic sensory paths onto common motor outputs in a Drosophila feeding connectome.

We reconstructed, from a whole CNS EM volume, the synaptic map of input and output neurons that underlie food intake behavior of Drosophila larvae. Input neurons originate from enteric, pharyngeal and external sensory organs and converge onto seven distinct sensory synaptic compartments within the CNS. Output neurons consist of feeding motor, serotonergic modulatory and neuroendocrine neurons. Monosynaptic connections from a set of sensory synaptic compartments cover the motor, modulatory and neuroendocrine targets in overlapping domains. Polysynaptic routes are superimposed on top of monosynaptic connections, resulting in divergent sensory paths that converge on common outputs. A completely different set of sensory compartments is connected to the mushroom body calyx. The mushroom body output neurons are connected to interneurons that directly target the feeding output neurons. Our results illustrate a circuit architecture in which monosynaptic and multisynaptic connections from sensory inputs traverse onto output neurons via a series of converging paths.

Using Pox-Neuro (Poxn) Mutants in Drosophila Gustation Research: A Double-Edged Sword.

In Drosophila, Pox-neuro (Poxn) is a member of the Paired box (Pax) gene family that encodes transcription factors with characteristic paired DNA-binding domains. During embryonic development, Poxn is expressed in sensory organ precursor (SOP) cells of poly-innervated external sensory (p-es) organs and is important for specifying p-es organ identity (chemosensory) as opposed to mono-innervated external sensory (m-es) organs (mechanosensory). In Poxn mutants, there is a transformation of chemosensory bristles into mechanosensory bristles. As a result, these mutants have often been considered to be entirely taste-blind, and researchers have used them in this capacity to investigate physiological and behavioral functions that act in a taste-independent manner. However, recent studies show that only external taste bristles are transformed in Poxn mutants whereas all internal pharyngeal taste neurons remain intact, raising concerns about interpretations of experimental results using Poxn mutants as taste-blind flies. In this review, we summarize the value of Poxn mutants in advancing our knowledge of taste-enriched genes and feeding behaviors, and encourage revisiting some of the conclusions about taste-independent nutrient-sensing mechanisms derived from these mutants. Lastly, we highlight that Poxn mutant flies remain a valuable tool for probing the function of the relatively understudied pharyngeal taste neurons in sensing meal properties and regulating feeding behaviors.

Comparative analysis of diagnostic and phylogenetic chaetotaxic characters of Berosus Leach and their implications on the relationships of the tribe Berosini (Coleoptera: Hydrophilidae)

Larvae of water scavenger beetles are found in all types of aquatic and semi-aquatic environments and play an important role in the structure of these communities. Despite their diversity, morphological characters that allow the identification of larvae at species level are usually inconspicuous. In this paper we analyze the head capsule and mouthparts chaetotaxy of hydrophilid larvae belonging to the tribe Berosini, with the purpose of identifying variations on the external sensory organs that may be used for species delimitations. We focus on two species of Berosus Leach (Berosus festivus Berg, 1885 and Berosus patruelis Berg, 1885) and compare larval structures within Berosus and among other genera of Berosini. We include morphometric characters together with detailed illustrations of all characters, SEM images of selected structures and micrographs of a sensory organ present on the inner margin of the first antennomere which is a novelty within larval Coleoptera. Our analysis shows that the number, shape, relative position and organization of sensilla, especially those of labroclypeus and mouthparts, provide diagnostic characters for the separation of Berosus species. Also, we found a new set of characters derived from chaetotaxy that supports current phylogenetic relationships within the tribe Berosini. Most of these chaetic characters are associated with structures that have undergone strong modifications as adaptation to a benthic lifestyle in the clade Berosus + Hemiosus.

Redescription of immature stages of central European fireflies, Part 3: Phosphaenus hemipterus (Goeze, 1777) larva, and notes on its life cycle and behaviour, with a key to three central European lampyrid larvae (Coleoptera: Lampyridae).

The mature larva of the elusive firefly Phosphaenus hemipterus (Goeze, 1777) is thoroughly redescribed and illustrated with detailed images, including scanning electron microscope figures. The external sense organs and their significance is discussed, as well as the predatory behaviour and specific lifestyle of the larva. A key to the central European lampyrid larvae (viz. P. hemipterus, Lamprohiza splendidula (Linnaeus, 1767) and Lampyris noctiluca (Linnaeus, 1758)) is provided as well as a comparative table of their morphological features.

Redescription of immature stages of central European fireflies, Part 2: Lamprohiza splendidula (Linnaeus, 1767) larva, pupa and notes on its life cycle and behaviour (Coleoptera: Lampyridae).

The mature larva of the firefly Lamprohiza splendidula (Linnaeus, 1767) is thoroughly redescribed and illustrated with detailed images, including scanning electron microscope figures. External sense organs, structure of tergal plates and their significance are discussed, as well as photic manifestation of the larvae and pupae and prey hunting in larvae. Male and female pupae are briefly described, with notes on their developmental changes and behaviour, and the life cycle outlined.

The causa sine qua non of Human Cognition for Durand f St. Pourçain

This article aims to analyze the notion of sine qua non cause of the cognitive theory of Durand’ of St. Pourçain Commentary on the Sentences of Peter Lombard [A] and [C]. For Durand, when the intellect acts by a cognitive act, no absolute entity is added to it. The cognition, or thought, is treated by the author as a relative entity, not as something that belongs to the intellect, or as something that is added to it. The sensible species of the material object, spread in the medium, affects the external sensory organs. Therefore, the sensory faculty notices the changes that occurred in the body and is capable of producing a sensation and the cognitive faculty, on its turn, can produce a conception due to the intuition of the changes that happened in the body to which it is associated. Consequently, there is no need to affirm that a cognitive act is the result of an abstractive process. The culmination of his cognitive theory is the rejection of the existence of an agent intellect responsible for abstracting.

Analysis of the Neurogenesis: Prepattern gene network сontrolling the first stage in Drosophila melanogaster bristle pattern development

The external insect chitinous skeleton is unable to respond to stimuli; the external signals are received by specialized receptors. Drosophila perceives the tactile stimuli by its external sensory organs, the microchaetes and macrochaetes residing on the head and back (notum). The microchaetes (hairs) are numerous and arranged in perfect rows along the body. The macrochaetes (bristles) are rather few and are strictly positioned on the head and notum, being referred to as bristle pattern. Bristles act as mechanoreceptors, providing balance for flying drosophila. The proper bristle pattern of an adult fly develops through several stages. Its basic stage is formation of prepattern for the future bristles, represented by proneural clusters. The proneural clusters separate from the ectodermal cells in imaginal discs in the third instar larvae and early prepupae. They are induced by prepattern factors, identified with the transcription factors driving expression of their target genes in certain disc regions. Reconstruction of the gene network controlling prepattern development and its analysis are for the first time described as well as the principles underlying arrangement and function of this network. The hierarchical structure of the network, its key components, and regulatory circuits are identified. The network comprises 80 entities interconnected via 109 regulatory interactions. The key objects of the network, displaying the greatest connectivity with its other components, are the ASC proneural proteins encoded by the achaete and scute genes, and the proteins Decapentaplegic (Dpp) and Wingless (Wg). The structure of the network is hierarchical and has at least three control levels. The network acts as a gene ensemble owing to coordinated functioning of the regulatory circuits controlling activities of the corresponding genes both within and between the levels. The resulting effect of the network operation consists in activation of the AS-C, proneural genes, the expression of which distinguishes the cells of proneural cluster from the surrounding ectodermal cells.

A Behavioral Assay for Mechanosensation of MARCM-based Clones in <em>Drosophila melanogaster</em>

Because of the structural and functional homology to the hair cells of the mammalian inner ear, the neurons that innervate the Drosophila external sense organs provide an excellent model system for the study of mechanosensation. This protocol describes a simple touch behavior in fruit flies which can be used to identify mutations that interfere with mechanosensation. The tactile stimulation of a macrochaete bristle on the thorax of flies elicits a grooming reflex from either the first or third leg. Mutations that interfere with mechanotransduction (such as NOMPC), or with other aspects of the reflex arc, can inhibit the grooming response. A traditional screen of adult behaviors would have missed mutants that have essential roles during development. Instead, this protocol combines the touch screen with mosaic analysis with a repressible cell marker (MARCM) to allow for only limited regions of homozygous mutant cells to be generated and marked by the expression of green fluorescent protein (GFP). By testing MARCM clones for abnormal behavioral responses, it is possible to screen a collection of lethal p-element mutations to search for new genes involved in mechanosensation that would have been missed by more traditional methods.

A Behavioral Assay for Mechanosensation of MARCM-based Clones in Drosophila melanogaster.

Because of the structural and functional homology to the hair cells of the mammalian inner ear, the neurons that innervate the Drosophila external sense organs provide an excellent model system for the study of mechanosensation. This protocol describes a simple touch behavior in fruit flies which can be used to identify mutations that interfere with mechanosensation. The tactile stimulation of a macrochaete bristle on the thorax of flies elicits a grooming reflex from either the first or third leg. Mutations that interfere with mechanotransduction (such as NOMPC), or with other aspects of the reflex arc, can inhibit the grooming response. A traditional screen of adult behaviors would have missed mutants that have essential roles during development. Instead, this protocol combines the touch screen with mosaic analysis with a repressible cell marker (MARCM) to allow for only limited regions of homozygous mutant cells to be generated and marked by the expression of green fluorescent protein (GFP). By testing MARCM clones for abnormal behavioral responses, it is possible to screen a collection of lethal p-element mutations to search for new genes involved in mechanosensation that would have been missed by more traditional methods.

Drosophila Hook-Related Protein (Girdin) Is Essential for Sensory Dendrite Formation.

The dendrite of the sensory neuron is surrounded by support cells and is composed of two specialized compartments: the inner segment and the sensory cilium. How the sensory dendrite is formed and maintained is not well understood. Hook-related proteins (HkRP) like Girdin, DAPLE, and Gipie are actin-binding proteins, implicated in actin organization and in cell motility. Here, we show that the Drosophila melanogaster single member of the Hook-related protein family, Girdin, is essential for sensory dendrite formation and function. Mutations in girdin were identified during a screen for fly mutants with no mechanosensory function. Physiological, morphological, and ultrastructural studies of girdin mutant flies indicate that the mechanosensory neurons innervating external sensory organs (bristles) initially form a ciliated dendrite that degenerates shortly after, followed by the clustering of their cell bodies. Importantly, we observed that Girdin is expressed transiently during dendrite morphogenesis in three previously unidentified actin-based structures surrounding the inner segment tip and the sensory cilium. These actin structures are largely missing in girdin mutant. Defects in cilia are observed in other sensory organs such as those mediating olfaction and taste, suggesting that Girdin has a general role in forming sensory dendrites in Drosophila. These suggest that Girdin functions temporarily within the sensory organ and that this function is essential for the formation of the sensory dendrites via actin structures.