scholarly journals Mechanoreceptors and Minimal Reflex Activity Determining Claw Laterality In Developing Lobsters

1992 ◽  
Vol 171 (1) ◽  
pp. 149-162
Author(s):  
C. K. GOVIND ◽  
JOANNE PEARCE
Keyword(s):  
Critical Period ◽  
Homarus Americanus ◽  
Contralateral Side ◽  
Reflex Activity ◽  
Chordotonal Organ ◽  
Minimal Amount ◽  
Bilateral Asymmetry ◽  
Intact Side ◽  
In The Wild ◽  
Juvenile Stages

Bilateral asymmetry of the paired claws of the lobster Homarus americanus is determined during the fourth and fifth juvenile stages by differential reflex activity; the side with the greater activity becomes the crusher while the contralateral side becomes the cutter. Juvenile lobsters reared during this critical period with a substratum that could not be grasped or with reduced input from predominantly internal mechanoreceptors (proprioceptors) (achieved by cutting the dactyl and its chordotonal organ or by tenotomizing the claw opener or closer muscles) failed to develop a crusher claw and hence remained bilaterally symmetrical: they developed paired cutter claws. Therefore, the proprioceptive component of the reflex activity is implicated in bringing about the initial lateralization of the claw ganglion into a crusher and a cutter side. Moreover, lobsters with a single claw reared without a substratum developed a crusher on the intact side only if the intact claw was exercised. In the unexercised condition, differences in reflex activity between the side with a claw and the side without one were insufficient for the development of a crusher claw on the intact side. A minimal amount of reflex activity is necessary for the development of a crusher. Lobsters reared with this minimal amount of activity in both claws developed asymmetrical claws rather than paired crusher claws. This means that initial lateralization of the claw ganglion into a crusher side, on a random basis, inhibited the opposite side from also becoming a crusher. This would explain why we failed to produce lobsters with paired crusher claws and why they were seldom found in the wild.

Visual Pathways for Postural Control and Negative Phototaxis in Lamprey

1997 ◽  
Vol 78 (2) ◽  
pp. 960-976 ◽  
Author(s):  
Fredrik Ullén ◽  
Tatiana G. Deliagina ◽  
Grigori N. Orlovsky ◽  
Sten Grillner
Keyword(s):  
Spinal Cord ◽  
Postural Control ◽  
Brain Stem ◽  
Light Response ◽  
Contralateral Side ◽  
Visual Pathways ◽  
Negative Phototaxis ◽  
Intact Side ◽  
Roll Control ◽  
The Brain

Ullén, Fredrik, Tatiana G. Deliagina, Grigori N. Orlovsky, and Sten Grillner. Visual pathways for postural control and negative phototaxis in lamprey. J. Neurophysiol. 78: 960–976, 1997. The functional roles of the major visuo-motor pathways were studied in lamprey. Responses to eye illumination were video-recorded in intact and chronically lesioned animals. Postural deficits during spontaneous swimming were analyzed to elucidate the roles of the lesioned structures for steering and postural control. Eye illumination in intact lampreys evoked the dorsal light response, that is, a roll tilt toward the light, and negative phototaxis, that is a lateral turn away from light, and locomotion. Complete tectum-ablation enhanced both responses. During swimming, a tendency for roll tilts and episodes of vertical upward swimming were seen. The neuronal circuitries for dorsal light response and negative phototaxis are thus essentially extratectal. Responses to eye illumination were abolished by contralateral pretectum-ablation but normal after the corresponding lesion on the ipsilateral side. Contralateral pretectum thus plays an important role for dorsal light response and negative phototaxis. To determine the roles of pretectal efferent pathways for the responses, animals with a midmesencephalichemisection were tested. Noncrossed pretecto-reticular fibers from the ipsilateral pretectum and crossed fibers from the contralateral side were transected. Eye illumination on the lesioned side evoked negative phototaxis but no dorsal light response. Eye illumination on the intact side evoked an enhanced dorsal light response, whereas negative phototaxis was replaced with straight locomotion or positive phototaxis. The crossed pretecto-reticular projection is thus most important for the dorsal light response, whereas the noncrossed projection presumably plays the major role for negative phototaxis. Transection of the ventral rhombencephalic commissure enhanced dorsal light response; negative phototaxis was retained with smaller turning angles than normal. Spontaneous locomotion showed episodes of backward swimming and deficient roll control (tilting tendency). Transections of different spinal pathways were performed immediately caudal to the brain stem. All spinal lesions left dorsal light response in attached state unaffected; this response presumably is mediated by the brain stem. Spinal hemisection impaired all ipsiversive yaw turns; the animals spontaneously rolled to the intact side. Bilateral transection of the lateral columns impaired all yaw turns, whereas roll control and dorsal light response were normal. After transection of the medial spinal cord, yaw turns still could be performed whereas dorsal light response was suppressed or abolished, and a roll tilting tendency during spontaneous locomotion was seen. We conclude that the contralateral optic nerve projection to the pretectal region is necessary and sufficient for negative phototaxis and dorsal light response. The crossed descending pretectal projection is most important for dorsal light response, whereas the noncrossed one is most important for negative phototaxis. In the most rostral spinal cord, fibers for lateral yaw turns travel mainly in the lateral columns, whereas fibers for roll turns travel mainly in the medial spinal cord.

scholarly journals Botulinum toxin injection causes hyper-reflexia and increased muscle stiffness of the triceps surae muscle in the rat

2016 ◽  
Vol 116 (6) ◽  
pp. 2615-2623 ◽  
Author(s):  
Jessica Pingel ◽  
Jacob Wienecke ◽  
Jakob Lorentzen ◽  
Jens Bo Nielsen
Keyword(s):  
Botulinum Toxin ◽  
Muscle Force ◽  
Botulinum Toxin Injection ◽  
Contralateral Side ◽  
Relative Increase ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Reflex Activity ◽  
Muscle Properties ◽  
Triceps Surae Muscle

Botulinum toxin is used with the intention of diminishing spasticity and reducing the risk of development of contractures. Here, we investigated changes in muscle stiffness caused by reflex activity or elastic muscle properties following botulinum toxin injection in the triceps surae muscle in rats. Forty-four rats received injection of botulinum toxin in the left triceps surae muscle. Control measurements were performed on the noninjected contralateral side in all rats. Acute experiments were performed, 1, 2, 4, and 8 wk following injection. The triceps surae muscle was dissected free, and the Achilles tendon was cut and attached to a muscle puller. The resistance of the muscle to stretches of different amplitudes and velocities was systematically investigated. Reflex-mediated torque was normalized to the maximal muscle force evoked by supramaximal stimulation of the tibial nerve. Botulinum toxin injection caused severe atrophy of the triceps surae muscle at all time points. The force generated by stretch reflex activity was also strongly diminished but not to the same extent as the maximal muscle force at 2 and 4 wk, signifying a relative reflex hyperexcitability. Passive muscle stiffness was unaltered at 1 wk but increased at 2, 4, and 8 wk ( P < 0.01). These data demonstrate that botulinum toxin causes a relative increase in reflex stiffness, which is likely caused by compensatory neuroplastic changes. The stiffness of elastic elements in the muscles also increased. The data are not consistent with the ideas that botulinum toxin is an efficient antispastic medication or that it may prevent development of contractures.

scholarly journals How to Effectively Collect and Process Network Data for Intrusion Detection?

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1532
Author(s):  
Mikołaj Komisarek ◽  
Marek Pawlicki ◽  
Rafał Kozik ◽  
Witold Hołubowicz ◽  
Michał Choraś
Keyword(s):  
Machine Learning ◽  
Intrusion Detection ◽  
Real World ◽  
Machine Learning Algorithms ◽  
Network Intrusion Detection ◽  
Minimal Amount ◽  
Security Breaches ◽  
Network Intrusion ◽  
Benchmark Datasets ◽  
In The Wild

The number of security breaches in the cyberspace is on the rise. This threat is met with intensive work in the intrusion detection research community. To keep the defensive mechanisms up to date and relevant, realistic network traffic datasets are needed. The use of flow-based data for machine-learning-based network intrusion detection is a promising direction for intrusion detection systems. However, many contemporary benchmark datasets do not contain features that are usable in the wild. The main contribution of this work is to cover the research gap related to identifying and investigating valuable features in the NetFlow schema that allow for effective, machine-learning-based network intrusion detection in the real world. To achieve this goal, several feature selection techniques have been applied on five flow-based network intrusion detection datasets, establishing an informative flow-based feature set. The authors’ experience with the deployment of this kind of system shows that to close the research-to-market gap, and to perform actual real-world application of machine-learning-based intrusion detection, a set of labeled data from the end-user has to be collected. This research aims at establishing the appropriate, minimal amount of data that is sufficient to effectively train machine learning algorithms in intrusion detection. The results show that a set of 10 features and a small amount of data is enough for the final model to perform very well.

scholarly journals Resistance reflex that maintains upright head posture in the flesh fly neobellieria bullata (Sarcophagidae)

1998 ◽  
Vol 201 (19) ◽  
pp. 2735-2744 ◽  
Author(s):  
C Gilbert ◽  
E Bauer
Keyword(s):  
Motor Nerve ◽  
Contralateral Side ◽  
Chordotonal Organ ◽  
Neural Pathways ◽  
Perturbation Amplitude ◽  
Head Posture ◽  
Roll Axis ◽  
Head Roll ◽  
Upright Head ◽  
Neobellieria Bullata

In flesh flies Neobellieria bullata, we investigated a resistance reflex that maintains upright head posture around the roll axis relative to the thorax. The gain of the reflex depends upon the fly's behavioral state: moving flies immediately correct 90 % of the amplitude of experimentally imposed roll perturbations, returning the head almost to the fully upright position; motionless flies allow perturbations to persist for minutes before correcting only 70 % of perturbation amplitude. To investigate the role of various neural pathways, we examined the control of head posture after sectioning relevant propriosensory or motor nerves. Excision of the prosternal chordotonal organ causes no decrements in the control of head posture. Unilateral deafferentation of a cervical propriosensory organ, the prosternal organ, induces roll towards the cut side. Unilateral section of the frontal nerve, a mixed motor nerve that supplies the neck depressors and levators, leads to unilateral deficits in correcting perturbations towards the contralateral side. After bilateral propriosensory or frontal motor nerve section, approximately 40 % of perturbation amplitude is still corrected. To determine the contributions of the passive elastic properties of the neck skeleto-muscular system, flies were tested under reversible nitrogen anesthesia. They immediately corrected 40 % of perturbation amplitude. Taken together, the results demonstrate that passive elasticity plus active prosternal nerve afference to contralateral depressors innervated by the frontal nerve in combination constitute a sufficient and necessary reflex loop to control head roll posture.

Delayed determination of claw laterality in lobsters loss of target

Development ◽  
1989 ◽  
Vol 107 (3) ◽  
pp. 547-551
Author(s):  
C.K. Govind ◽  
J. Pearce
Keyword(s):  
Critical Period ◽  
Early Juvenile ◽  
Juvenile Stages ◽  
Juvenile Development

Lateralization of the paired claws into a major crusher minor cutter type is determined during the 4th and 5th juvenile development of the lobster, Homarus claws during this critical period delays the laterality until the 6th stage when regenerate claws Continued loss into the 6th stage, and beyond, laterality, resulting in lobsters with paired cutter critical period for determining claw laterality may extended for a brief time to cater for claw loss, common in these early juvenile stages.

Innervation Patterns of Fast and Slow Motor Neurones During Development of a Lobster Neuromuscular System

1981 ◽  
Vol 91 (1) ◽  
pp. 271-284
Author(s):  
WALTER J. COSTELLO ◽  
RUSSELL HILL ◽  
FRED LANG
Keyword(s):  
Muscle Fibre ◽  
Fibre Type ◽  
Homarus Americanus ◽  
Neuromuscular System ◽  
Motor Innervation ◽  
Postsynaptic Potentials ◽  
Innervation Patterns ◽  
Motor Neurones ◽  
Juvenile Stages ◽  
To Receive

1. Relationships between motor innervation and muscle fibre type were examined in the closer muscle of the claws of the lobster Homarus americanus. The dimorphic claws of the adult-the cutter and crusher-were compared with the claws of the juvenile (stages 4–6) when differentiation takes place. The muscle is known to receive a fast and a slow motor axon. Previous findings have shown that the crusher contains mostly slow fibres; the cutter and juvenile claws have both fast and slow fibres. 2. In the adult, the majority of fibres in the crusher received fast and slow axons; in the cutter most fibres received the fast axon. Fast fibres in the cutter claw were innervated by the fast axon, alone or with the slow axon. Slow fibres in both claws could receive the slow axon only, or both axons. Some slow fibres in the crusher claw were innervated primarily or solely by the fast axon. 3. In the juvenile, most fibres in each claw were innervated by both axons. The juvenile synapses were immature; postsynaptic potentials fluctuated greatly with frequent failures. The homologous fast axons in these claws formed fatigue-resistant synapses. 4. In both adult and juvenile, regardless of fibre type, fast axon synapses had poor facilitation; slow axon synapses had moderate-to-high facilitation. Note:

Dynamic Rehabilitation of the Paralyzed Face—II. Electronic Control of the Reinnervated Facial Musculature from the Contralateral Side in the Rabbit

1989 ◽  
Vol 101 (3) ◽  
pp. 309-313 ◽  
Author(s):  
Michael Broniatowski ◽  
Laszlo A. Ilyes ◽  
Gordon Jacobs ◽  
Yukihiko Nosé ◽  
Harvey M. Tucker
Keyword(s):  
Muscular Contraction ◽  
Contralateral Side ◽  
Fine Tuning ◽  
Intact Side ◽  
Facial Musculature ◽  
Current Series ◽  
The Face ◽  
Monopolar Electrodes ◽  
Series Of Experiments ◽  
Nerve Muscle

This work is the continuation of a previous pilot study in the rabbit in which motion originating on the face was picked up by miniature strain gages and channeled synchronously to strap muscles reinnervated via crossover nerve-muscle pedicles. In the current series of experiments, we modified the distal limb of the system to reinnervate the previously paralyzed opposite side of the face via an ansa hypoglossi nerve–thyrohyoid muscle pedicle in five animals. Muscular contraction was induced on the intact side by stimulating different branches of the facial nerve, and corresponding information was channeled to the reinnervated side through an upgraded electronic stimulator via monopolar electrodes placed around the nerve pedicle in the neck. In addition to demonstrating perfect synchrony between intact and reinnervated sides, this facial stimulator allowed the reinnervated side of the face to follow the intact side in a graded and sustained fashion, thus demonstrating that fine tuning of reinnervated facial musculature was possible.

Recruitment failure in the Australian lungfish, Neoceratodus forsteri (Osteichthyes:Dipnoi), in south-east Queensland

2019 ◽  
Vol 25 (3) ◽  
pp. 283
Author(s):  
Anne Kemp
Keyword(s):  
Volatile Fatty Acids ◽  
Adult Population ◽  
Young Fish ◽  
Moderate Amount ◽  
Recruitment Failure ◽  
In The Wild ◽  
Advanced Stages ◽  
Juvenile Stages ◽  
Poor Recruitment ◽  
Australian Lungfish

Changes to the environment of the Australian lungfish, Neoceratodus forsteri, are associated with loss of recruitment of young lungfish to the adult population. Eggs laid by poorly fed adults lack volatile fatty acids and fail to develop normally. Problems in young fish first appeared in some specimens collected at Fernvale on the Brisbane River during a drought, when food supplies in the river began to fail. In 2016, after poor recruitment for several years, hatchlings from Lake Samsonvale were able to feed, and reached advanced stages in the laboratory, after a moderate amount of food for parent lungfish appeared in the lake during the summer before the 2016 spawning season. However, all died after 14 months. Lungs, intestines and nervous systems in the juveniles were anomalous, and would have precluded continued development in the wild. Survival of several young to juvenile stages in the laboratory does not mean that survival and recruitment to the adult population in the wild will follow.

scholarly journals Epigenetic Requirements for Triggering Heterochromatinization and Piwi-Interacting RNA Production from Transgenes in the Drosophila Germline

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 922
Author(s):  
Pavel A. Komarov ◽  
Olesya Sokolova ◽  
Natalia Akulenko ◽  
Emilie Brasset ◽  
Silke Jensen ◽  
...  
Keyword(s):  
De Novo ◽  
Threshold Level ◽  
Selective Advantage ◽  
Minimal Amount ◽  
Genomic Context ◽  
Transcription Profiles ◽  
Convergent Transcription ◽  
Pirna Cluster ◽  
In The Wild ◽  
Pirna Pathway

Transgenes containing a fragment of the I retrotransposon represent a powerful model of piRNA cluster de novo formation in the Drosophila germline. We revealed that the same transgenes located at different genomic loci form piRNA clusters with various capacity of small RNA production. Transgenic piRNA clusters are not established in piRNA pathway mutants. However, in the wild-type context, the endogenous ancestral I-related piRNAs heterochromatinize and convert the I-containing transgenes into piRNA-producing loci. Here, we address how the quantitative level of piRNAs influences the heterochromatinization and piRNA production. We show that a minimal amount of maternal piRNAs from ancestral I-elements is sufficient to form the transgenic piRNA clusters. Supplemental piRNAs stemming from active I-element copies do not stimulate additional chromatin changes or piRNA production from transgenes. Therefore, chromatin changes and piRNA production are initiated by a minimum threshold level of complementary piRNAs, suggesting a selective advantage of prompt cell response to the lowest level of piRNAs. It is noteworthy that the weak piRNA clusters do not transform into strong ones after being targeted by abundant I-specific piRNAs, indicating the importance of the genomic context for piRNA cluster establishment. Analysis of ovarian transcription profiles suggests that regions facilitating convergent transcription favor the formation of transgenic piRNA clusters.

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