scholarly journals A single neuron subset governs a single coactive neuron circuit in Hydra vulgaris, representing a possible ancestral feature of neural evolution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yukihiko Noro ◽  
Hiroshi Shimizu ◽  
Katsuhiko Mineta ◽  
Takashi Gojobori
Keyword(s):  
Nervous System ◽  
Common Ancestor ◽  
Model Organism ◽  
The Body ◽  
Neural Function ◽  
Last Common Ancestor ◽  
Longitudinal Contraction ◽  
Hydra Vulgaris ◽  
Motor Circuits ◽  
Neural Evolution

AbstractThe last common ancestor of Bilateria and Cnidaria is believed to be one of the first animals to develop a nervous system over 500 million years ago. Many of the genes involved in the neural function of the advanced nervous system in Bilateria are well conserved in Cnidaria. Thus, the cnidarian Hydra vulgaris is a good model organism for the study of the putative primitive nervous system in its last common ancestor. The diffuse nervous system of Hydra consists of several peptidergic neuron subsets. However, the specific functions of these subsets remain unclear. Using calcium imaging, here we show that the neuron subsets that express neuropeptide, Hym-176, function as motor circuits to evoke longitudinal contraction. We found that all neurons in a subset defined by the Hym-176 gene (Hym-176A) or its paralogs (Hym-176B) expression are excited simultaneously, followed by longitudinal contraction. This indicates not only that these neuron subsets have a motor function but also that a single molecularly defined neuron subset forms a single coactive circuit. This is in contrast with the bilaterian nervous system, where a single molecularly defined neuron subset harbors multiple coactive circuits, showing a mixture of neurons firing with different timings. Furthermore, we found that the two motor circuits, one expressing Hym-176B in the body column and the other expressing Hym-176A in the foot, are coordinately regulated to exert region-specific contraction. Our results demonstrate that one neuron subset is likely to form a monofunctional circuit as a minimum functional unit to build a more complex behavior in Hydra. This simple feature (one subset, one circuit, one function) found in Hydra may represent the simple ancestral condition of neural evolution.

scholarly journals A single neuron subset governs a single coactive neuron circuit in Hydra vulgaris, representing a prototypic feature of neural evolution

2020 ◽  
Author(s):  
Yukihiko Noro ◽  
Hiroshi Shimizu ◽  
Katsuhiko Mineta ◽  
Takashi Gojobori
Keyword(s):  
Nervous System ◽  
Motor Neurons ◽  
Common Ancestor ◽  
Model Organism ◽  
The Body ◽  
Neural Function ◽  
Last Common Ancestor ◽  
Longitudinal Contraction ◽  
Living Fossil ◽  
Motor Circuits

AbstractThe last common ancestor of Bilateria and Cnidaria is believed to be one of the first animals to develop a nervous system over 500 million years ago. Many of the genes involved in the neural function of the advanced nervous system in Bilateria are well conserved in Cnidaria1. Thus, Cnidarian representative species, Hydra, is considered to be a living fossil and a good model organism for the study of the putative primitive nervous system in its last common ancestor. The diffuse nervous system of Hydra consists of several peptidergic neuron subsets. However, the specific functions of these subsets remain unclear. Using calcium imaging, here we show that the neuron subsets that express neuropeptide, Hym-1762,3 function as motor neurons to evoke longitudinal contraction. We found that all neurons in a subset defined by the Hym-176 gene (Hym-176A) or its paralogs (Hym-176B) expression4 are excited simultaneously, which is then followed by longitudinal contraction. This indicates not only that these neuron subsets are motor neurons but also that a single molecularly defined neuron subset forms a single coactive motor circuit. This is in contrast with the Bilaterian nervous system, where a single molecularly defined neuron subset harbors multiple coactive circuits, showing a mixture of neurons firing with different timings5. Furthermore, we found that the two motor circuits, one expressing Hym-176B in the body column and the other expressing Hym-176A in the foot, are coordinately regulated to exert region-specific contraction. Our results demonstrate that one neuron subset is likely to form a monofunctional circuit as a minimum functional unit to build a more complex behavior in Hydra. We propose that this simple feature (one subset, one circuit, one function) found in Hydra is a fundamental trait of the primitive nervous system.

Discovering Human Nature Through Cross-Species Analysis

2018 ◽  
Author(s):  
Jonathan H. Turner
Keyword(s):  
Human Nature ◽  
Common Ancestor ◽  
Cladistic Analysis ◽  
Great Apes ◽  
The Body ◽  
Last Common Ancestor ◽  
Species Analysis ◽  
Organizational Patterns ◽  
Genetic Closeness ◽  
Source Of Information

Cladistic analysis is employed on behavioral and organizational patterns among present-day great apes that, because of their genetic closeness to humans, can be used as a surrogate for making inferences about the behavior and organizational propensities of the last common ancestor to great apes, hominins, and humans. A series of preadaptations among great apes for language, emotionality, mother–infant bonding, life history characteristics, propensities for play, and nonharem/promiscuous mating represents one source of information on the nature of the last common ancestor. Moreover, a set of behavioral propensities among all great apes adds to the body of information that can be used to make inferences about the nature of the last common ancestors, hominins, and humans. Thus, it is now possible to make inferences about the biological nature of human behavior and organizational tendencies that are less speculative than earlier analyses of human nature.

scholarly journals The Quest for Orthologs benchmark service and consensus calls in 2020

2020 ◽  
Vol 48 (W1) ◽  
pp. W538-W545 ◽  
Author(s):  
Adrian M Altenhoff ◽  
Javier Garrayo-Ventas ◽  
Salvatore Cosentino ◽  
David Emms ◽  
Natasha M Glover ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Common Ancestor ◽  
Computational Cost ◽  
Model Organism ◽  
Ground Truth ◽  
Last Common Ancestor ◽  
Common Input ◽  
Reference Set ◽  
Input Dataset ◽  
Model Organism Databases

Abstract The identification of orthologs—genes in different species which descended from the same gene in their last common ancestor—is a prerequisite for many analyses in comparative genomics and molecular evolution. Numerous algorithms and resources have been conceived to address this problem, but benchmarking and interpreting them is fraught with difficulties (need to compare them on a common input dataset, absence of ground truth, computational cost of calling orthologs). To address this, the Quest for Orthologs consortium maintains a reference set of proteomes and provides a web server for continuous orthology benchmarking (http://orthology.benchmarkservice.org). Furthermore, consensus ortholog calls derived from public benchmark submissions are provided on the Alliance of Genome Resources website, the joint portal of NIH-funded model organism databases.

scholarly journals The evolution of nervous system centralization

2008 ◽  
Vol 363 (1496) ◽  
pp. 1523-1528 ◽  
Author(s):  
Detlev Arendt ◽  
Alexandru S Denes ◽  
Gáspár Jékely ◽  
Kristin Tessmar-Raible
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Common Ancestor ◽  
Last Common Ancestor ◽  
Molecular Architecture ◽  
Molecular Studies ◽  
The Central Nervous System ◽  
Molecular Anatomy ◽  
Set Up ◽  
Insight Into

It is yet unknown when and in what form the central nervous system in Bilateria first came into place and how it further evolved in the different bilaterian phyla. To find out, a series of recent molecular studies have compared neurodevelopment in slow-evolving deuterostome and protostome invertebrates, such as the enteropneust hemichordate Saccoglossus and the polychaete annelid Platynereis . These studies focus on the spatially different activation and, when accessible, function of genes that set up the molecular anatomy of the neuroectoderm and specify neuron types that emerge from distinct molecular coordinates. Complex similarities are detected, which reveal aspects of neurodevelopment that most likely occurred already in a similar manner in the last common ancestor of the bilaterians, Urbilateria. This way, different aspects of the molecular architecture of the urbilaterian nervous system are reconstructed and yield insight into the degree of centralization that was in place in the bilaterian ancestors.

scholarly journals Characterisation of Geometric Variance in the Epithelial Nerve Net of the Ctenophore Pleurobrachia pileus

2020 ◽  
Author(s):  
Amy Courtney ◽  
Jérémy Liegey ◽  
Niamh Burke ◽  
Madeleine Lowey ◽  
Mark Pickering
Keyword(s):  
Body Surface ◽  
Structural Characteristics ◽  
Model Organism ◽  
Morphological Features ◽  
The Body ◽  
Model Organisms ◽  
Neural Function ◽  
Structural Description ◽  
Nerve Net ◽  
Pleurobrachia Pileus

AbstractNeuroscience currently lacks a diverse repertoire of model organisms, resulting in an incomplete understanding of what principles of neural function generalise and what are species-specific. Ctenophores display many neurobiological and experimental features which make them a promising candidate to fill this gap. They possess a nerve net distributed across their outer body surface, just beneath the epithelial layer. There is a long-held assumption that nerve nets are ‘simple’ and random while lacking distinct organisational principles. We want to challenge this assumption and determine how stereotyped the structure of this network really is. We validated an approach to estimate body surface area in Pleurobrachia pileus using custom Optical Projection Tomography and Light Sheet Morphometry imaging systems. We used an antibody against tyrosylated α-tubulin to visualise the nerve net in situ. We used an automated segmentation approach to extract the morphological features of the nerve net. We characterised organisational rules of the epithelial nerve net in P. pileus in animals of different sizes and at different regions of the body. We found that specific morphological features within the nerve net are largely un-changed during growth. These properties must be essential to the functionality of the nervous system and therefore are maintained during a change in body size. We have also established the principles of organisation of the network and showed that some of the geometric properties are variable across different parts of the body. This suggests that there may be different functions occurring in regions with different structural characteristics. This is the most comprehensive structural description of a nerve net to date. This study also demonstrates the amenability of the ctenophore P. pileus for whole organism network analysis and shows their promise as a model organism for neuroscience, which may provide insights into the foundational principles of nervous systems.

scholarly journals Stable behavioral and neural responses to thermal stimulation despite large changes in the Hydra vulgaris nervous system

2019 ◽  
Author(s):  
Constantine N. Tzouanas ◽  
Soonyoung Kim ◽  
Krishna N. Badhiwala ◽  
Benjamin W. Avants ◽  
Jacob T. Robinson
Keyword(s):  
Nervous System ◽  
Neural Plasticity ◽  
Large Scale ◽  
Neural Circuit ◽  
Rapid Change ◽  
Model Organism ◽  
Thermal Stimulation ◽  
Model Organisms ◽  
Hydra Vulgaris ◽  
Sensory Motor

AbstractMany animals that lose neural tissue due to injury or disease have the ability to maintain their behavioral abilities by regenerating new neurons or reorganizing existing neural circuits. However, most small model organisms used for neuroscience like nematodes and flies lack this high degree of neural plasticity. These animals often show significant behavioral deficits if they lose even a single neuron. Here we show that the small freshwater cnidarian Hydra vulgaris can maintain stable sensory motor behaviors even after losing half of the neurons in its body. Specifically, we find that both the behavioral and neural response to a rapid change in temperature is maintained if we make their nervous system roughly 50% smaller by caloric restriction or surgery. These observations suggest that Hydra provides a rich model for studying how animals maintain stable sensory-motor responses within dynamic neural circuit architectures, and may lead to general principles for neural circuit plasticity and stability.Significance StatementThe ability of the nervous system to restore its function following injury is key to survival for many animals. Understanding this neural plasticity in animals across the phylogenetic tree would help reveal fundamental principles of this important ability. To our knowledge, the discovery of a set of neurons in the jellyfish polyp Hydra vulgaris that stably support a response to thermal stimulation is the first demonstration of large-scale neural plasticity in a genetically tractable invertebrate model organism. The small size and transparency of Hydra suggests that it will be possible to study large-scale neural circuit plasticity in an animal where one can simultaneously image the activity of every neuron.

scholarly journals Neuronal patterning of the tubular collar cord is highly conserved among enteropneusts but dissimilar to the chordate neural tube

2017 ◽  
Author(s):  
Sabrina Kaul-Strehlow ◽  
Makoto Urata ◽  
Daniela Praher ◽  
Andreas Wanninger
Keyword(s):  
Nervous System ◽  
Neural Tube ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Common Ancestor ◽  
Last Common Ancestor ◽  
Comparative Analyses ◽  
Dorsal Neural Tube ◽  
Saccoglossus Kowalevskii ◽  
Patterning Genes

AbstractThe dorsal neural tube of chordates and the ventral nerve cord of annelids exhibit a similar molecular mediolateral architecture. Accordingly, the presence of such a complex nervous system (CNS) has been proposed for their last common ancestor. Members of Enteropneusta, a group of non-chordate deuterostomes, possess a less complex CNS including a hollow neural tube, whereby homology to its chordate counterpart remains elusive. Since the majority of data on enteropneusts stem from Saccoglossus kowalevskii, a derived direct-developer, we investigated expression of key neuronal patterning genes in the indirect-developer Balanoglossus misakiensis.The collar cord of B. misakiensis shows anterior Six3/6 and posterior Otx + engrailed expression, in a region corresponding to the chordate brain. Neuronal Nk2.1/Nk2.2 expression is absent. Interestingly, we found median Dlx and lateral Pax6 expression domains, i.e., a condition that is reversed compared to chordates.Comparative analyses reveal that CNS patterning is highly conserved among enteropneusts. BmiDlx and BmiPax6 have no corresponding expression domains in the chordate brain, which may be indicative of independent acquisition of a tubular CNS in Enteropneusta and Chordata. Moreover, mediolateral architecture varies considerably among chordates and enteropneusts, questioning the presence of a vertebrate-like patterned nervous system in the last common deuterostome ancestor.

scholarly journals Multiple neuronal networks coordinate Hydra mechanosensory behavior

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Krishna N Badhiwala ◽  
Abby S Primack ◽  
Celina Juliano ◽  
Jacob T Robinson
Keyword(s):  
Nervous System ◽  
Calcium Imaging ◽  
Activity Patterns ◽  
Sensory Information ◽  
Model Organism ◽  
Model Organisms ◽  
Mechanical Stimuli ◽  
Hydra Vulgaris ◽  
Fundamental Properties ◽  
Neural Architecture

Hydra vulgaris is an emerging model organism for neuroscience due to its small size, transparency, genetic tractability, and regenerative nervous system; however, fundamental properties of its sensorimotor behaviors remain unknown. Here, we use microfluidic devices combined with fluorescent calcium imaging and surgical resectioning to study how the diffuse nervous system coordinates Hydra's mechanosensory response. Mechanical stimuli cause animals to contract, and we find this response relies on at least two distinct networks of neurons in the oral and aboral regions of the animal. Different activity patterns arise in these networks depending on whether the animal is contracting spontaneously or contracting in response to mechanical stimulation. Together, these findings improve our understanding of how Hydra’s diffuse nervous system coordinates sensorimotor behaviors. These insights help reveal how sensory information is processed in an animal with a diffuse, radially symmetric neural architecture unlike the dense, bilaterally symmetric nervous systems found in most model organisms.

Neuron-glia relationship during the early postembryonic development of the nervous system in some oligochaetes

1978 ◽  
Vol 36 (2) ◽  
pp. 600-601
Author(s):  
Wiktor Djaczenko ◽  
Carmen Calenda Cimmino
Keyword(s):  
Nervous System ◽  
Glial Cells ◽  
Early Period ◽  
Postembryonic Development ◽  
Ruthenium Red ◽  
The Body ◽  
Tubifex Tubifex ◽  
Growth Stages ◽  
Cell Processes ◽  
Cytoplasmic Processes

The simplicity of the developing nervous system of oligochaetes makes of it an excellent model for the study of the relationships between glia and neurons. In the present communication we describe the relationships between glia and neurons in the early periods of post-embryonic development in some species of oligochaetes.Tubifex tubifex (Mull. ) and Octolasium complanatum (Dugès) specimens starting from 0. 3 mm of body length were collected from laboratory cultures divided into three groups each group fixed separately by one of the following methods: (a) 4% glutaraldehyde and 1% acrolein fixation followed by osmium tetroxide, (b) TAPO technique, (c) ruthenium red method.Our observations concern the early period of the postembryonic development of the nervous system in oligochaetes. During this period neurons occupy fixed positions in the body the only observable change being the increase in volume of their perikaryons. Perikaryons of glial cells were located at some distance from neurons. Long cytoplasmic processes of glial cells tended to approach the neurons. The superimposed contours of glial cell processes designed from electron micrographs, taken at the same magnification, typical for five successive growth stages of the nervous system of Octolasium complanatum are shown in Fig. 1. Neuron is designed symbolically to facilitate the understanding of the kinetics of the growth process.

Characteristics of the dynamics of the central nervous system and att ention function in workers of shoe production

2020 ◽  
pp. 64-68
Author(s):  
F. L. Azizova ◽  
U. A. Boltaboev
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Women Workers ◽  
Functional State ◽  
The Body ◽  
Conflict Of Interests ◽  
Professional Groups ◽  
Universal Device ◽  
The Central Nervous System ◽  
Working Day

The features of production factors established at the main workplaces of shoe production are considered. The materials on the results of the study of the functional state of the central nervous system of women workers of shoe production in the dynamics of the working day are presented. The level of functional state of the central nervous system was determined by the speed of visual and auditory-motor reactions, installed using the universal device chronoreflexometer. It was revealed that in the body of workers of shoe production there is an early development of inhibitory processes in the central nervous system, which is expressed in an increase in the number of errors when performing tasks on proofreading tables. It was found that the most pronounced shift s in auditory-motor responses were observed in professional groups, where higher levels of noise were registered in the workplace. The correlation analysis showed a close direct relationship between the growth of mistakes made in the market and the decrease in production. An increase in the time spent on the task indicates the occurrence and growth of production fatigue.Funding. The study had no funding.Conflict of interests. The authors declare no conflict of interests.

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