scholarly journals Asexual Reproduction in Holothurians

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Igor Yu. Dolmatov
Keyword(s):  
Asexual Reproduction ◽  
Body Wall ◽  
Molecular Mechanisms ◽  
Basic Mechanism ◽  
The Body ◽  
Cross Link ◽  
Additional Species ◽  
Reproduction Mode ◽  
History Of ◽  
Anterior Posterior

Aspects of asexual reproduction in holothurians are discussed. Holothurians are significant as fishery and aquaculture items and have high commercial value. The last review on holothurian asexual reproduction was published 18 years ago and included only 8 species. An analysis of the available literature shows that asexual reproduction has now been confirmed in 16 holothurian species. Five additional species are also most likely capable of fission. The recent discovery of new fissiparous holothurian species indicates that this reproduction mode is more widespread in Holothuroidea than previously believed. New data about the history of the discovery of asexual reproduction in holothurians, features of fission, and regeneration of anterior and posterior fragments are described here. Asexual reproduction is obviously controlled by the integrated systems of the organism, primarily the nervous system. Special molecular mechanisms appear to determine the location where fission occurs along the anterior-posterior axis of the body. Alteration of the connective tissue strength of the body wall may play an important role during fission of holothurians. The basic mechanism of fission is the interaction of matrix metalloproteinases, their inhibitors, and enzymes forming cross-link complexes between fibrils of collagen. The population dynamics of fissiparous holothurians are discussed.

Electrophysiology of Acanthocephalan Body Wall Muscles

1979 ◽  
Vol 82 (1) ◽  
pp. 273-280
Author(s):  
B. S. WONG ◽  
DONALD M. MILLER ◽  
T. T. DUNAGAN
Keyword(s):  
Light Microscopy ◽  
Intracellular Recording ◽  
Body Wall ◽  
Membrane Potentials ◽  
The Body ◽  
Spontaneous Potential ◽  
Body Wall Muscles ◽  
Macracanthorhynchus Hirudinaceus ◽  
Anterior Posterior

Body wall muscles of an acanthocephalan Macracanthorhynchus hirudinaceus were studied by means of scanning and light microscopy and intracellular recording of potentials. Three types of spontaneous potential changes were found: larger (L) potentials which usually exhibited overshoot and were as large as 65 mV; smaller symmetric (A) potentials approximately 15 mV in amplitude; and even smaller asymmetric (S) potentials which sometimes reached 10 mV. The potentials recorded depended upon the position of the electrode in the anterior-posterior, as well as the medialateral, axis. Tetrodotoxin eliminated L but not S potentials. Ouabain lengthened the time for depolarization of L potentials and depolarized the membrane potentials. It is suggested that the rete system activates the body wall muscles in Acanthocephala.

scholarly journals An illustrated key to the species of the genus Narella (Cnidaria, Octocorallia, Primnoidae)

ZooKeys ◽  
2019 ◽  
Vol 822 ◽  
pp. 1-15 ◽  
Author(s):  
Stephen D. Cairns ◽  
Michelle L. Taylor
Keyword(s):  
Outer Surface ◽  
Body Wall ◽  
Species Level ◽  
The Body ◽  
Valid Species ◽  
History Of ◽  
Surface Ornamentation

A history of the description of the 50 valid species of Narella is given, beginning with the first species described in 1860. To help differentiate the various species, a tabular and a polychotomous key are provided. The species in the keys are arranged using nine characters or character sets that are believed to be of value at the species level. New characters or new significance given to previously described characters used in our keys include: 1) the nature of the dorsolateral edge of the basal scale, being ridged or not, 2) the thickness of the body wall scales, and 3) the arrangement of the coenenchymal scales (imbricate or mosaic), their thickness (thin or massive), and their outer surface ornamentation (ridged or not). All characters used in the keys are illustrated.

scholarly journals Enduring evolutionary embellishment of cloudinids in the Cambrian

2021 ◽  
Vol 8 (12) ◽  
Author(s):  
Tae-Yoon S. Park ◽  
Jikhan Jung ◽  
Mirinae Lee ◽  
Sangmin Lee ◽  
Yong Yi Zhen ◽  
...  
Keyword(s):  
Asexual Reproduction ◽  
Fossil Record ◽  
Evolutionary History ◽  
Structural Complexity ◽  
Cambrian Explosion ◽  
Animal Group ◽  
Reproduction Mode ◽  
First Case ◽  
History Of ◽  
Mode Tracking

The Ediacaran–Cambrian transition and the following Cambrian Explosion are among the most fundamental events in the evolutionary history of animals. Understanding these events is enhanced when phylogenetic linkages can be established among animal fossils across this interval and their trait evolution monitored. Doing this is challenging because the fossil record of animal lineages that span this transition is sparse, preserved morphologies generally simple and lifestyles in the Ediacaran and Cambrian commonly quite different. Here, we identify derived characters linking some members of an enigmatic animal group, the cloudinids, which first appeared in the Late Ediacaran, to animals with cnidarian affinity from the Cambrian Series 2 and the Miaolingian. Accordingly, we present the first case of an animal lineage represented in the Ediacaran that endured and diversified successfully throughout the Cambrian Explosion by embellishing its overall robustness and structural complexity. Among other features, dichotomous branching, present in some early cloudinids, compares closely with a cnidarian asexual reproduction mode. Tracking this morphological change from Late Ediacaran to the Miaolingian provides a unique glimpse into how a primeval animal group responded during the Cambrian Explosion.

Triggering by ATP of product release by mucous granules of the land slug Ariolimax columbianus

1992 ◽  
Vol 262 (3) ◽  
pp. C760-C765 ◽  
Author(s):  
I. Deyrup-Olsen ◽  
H. Louie ◽  
A. W. Martin ◽  
D. L. Luchtel
Keyword(s):  
Body Wall ◽  
Electrical Potential ◽  
Basic Mechanism ◽  
The Body ◽  
Stress Exposure ◽  
Pharmacological Agents ◽  
Product Release ◽  
High K ◽  
Saline Solutions ◽  
Low K

The body wall of the pulmonate land slug Ariolimax columbianus secretes mucus packaged in granules bounded by two closely adjacent membranes. Newly secreted granules rupture in the presence of ATP (approximately 1 microM). This response is apparently mediated by an ATP receptor and is lost by granules held in osmotically balanced saline solutions with relatively low [K+] or [Cl-], but is retained for long periods in solutions with high [K+] and [Cl-]. Rupture by ATP is blocked by indomethacin, furosemide, nigericin, or verapamil, implicating in the ATP-rupturing process a cyclooxygenase product of arachidonic acid as well as activation of K(+)-Cl- transport and efflux of Ca2+ through activated channels according to a proposed electrical potential (proton) gradient. Mechanical stress, exposure to cold (e.g., 1 h at 0 degree C), and pertussis toxin also cause rupture that is blocked by the pharmacological agents that block ATP action. The results suggest that a single basic mechanism causes rupture of the granules, releasing mucins that form the mucous layer protecting the body wall.

The Post-embryonic Development of Phaenoserphus viator Hal. (Proctotrypoidea), a Parasite of the Larva of Pterostichus niger (Carabidae), with Notes on the Anatomy of the Larva

Parasitology ◽  
1929 ◽  
Vol 21 (1-2) ◽  
pp. 1-21 ◽  
Author(s):  
L. E. S. Eastham
Keyword(s):  
Body Wall ◽  
Larval Instar ◽  
Circulatory System ◽  
The Body ◽  
Suboesophageal Ganglion ◽  
Tracheal System ◽  
Single Host ◽  
History Of ◽  
Cerebral Commissures ◽  
Frontal Ganglion

1. The life-history of Phaenoserphus viator is described.Four larval instars are found, endoparasitic in the larvae of Pterostichus niger. At thee nd of the last larval instar the parasites, which may number as many as 45 in a single host, emerge, and while still attached, pupate without spinning a cocoon.Adults may appear in August or September.The effect of the parasite in inhibiting metamorphosis of the host is discussed.2. The first observed larva is atracheate and incompletely segmented at first and is of the polypod type bearing paired prolegs on the body segments.Subsequent instars are apodate.The tracheal system develops progressively in the several instars, but only becomes functional in the final stage.3. The anatomy of the larva is briefly described with the exception of the musculature.Tracheal development is described. Gas only appears in the tracheae after the development of the tracheole cells puts the tracheae into communication with the body wall and other organs.In the circulatory system an important accessory organ is the neural sinus, formed by the enclosure of the ventral nerve cord beneath a connective tissue curtain.The imaginal discs of the hypodermis are briefly described, these being clearly defined in the head, thorax, and posterior abdominal segments.The nervous system consists of a brain, suboesophageal ganglion and 11 ventral ganglia, the most posterior being tripartite. This system is connected with the sympathetic, by nerves passing from the cerebral commissures to a frontal ganglion which lies above the oesophagus and behind the labrum.

Life history, morphology and distribution of Dipolydora armata (Polychaeta: Spionidae)

2003 ◽  
Vol 83 (2) ◽  
pp. 375-384 ◽  
Author(s):  
Vasily I. Radashevsky ◽  
João M. Nogueira
Keyword(s):  
Life History ◽  
Asexual Reproduction ◽  
Morphological Variability ◽  
Extended Period ◽  
The Body ◽  
Mutualistic Symbiosis ◽  
Egg Capsules ◽  
History Of ◽  
Original Interpretation ◽  
First Time

The spionid polychaete Dipolydora armata, a borer in calcareous substrata, is recorded for the first time from Belize, Brazil, Taiwan, and Vietnam. Specimens from these and other localities, as well as the type material of Polydora armata from Madeira Island and Polydora rogeri from the Mediterranean were examined and all the specimens were considered to be conspecific. Dipolydora armata is up to 8 mm long (usually 2–3 mm), with up to 45 segments (usually 25–35 segments), an incised prostomium, caruncle until the end of segment 2, up to 10 pairs of branchiae from segment 7, up to 20 awl-like modified spines per notopodium in up to 15 posterior segments, bilobed or cup-shaped pygidium, hooded hooks from segment 7 accompanied by capillaries throughout the body, major falcate spines of segment 5 with a large lateral tooth and an apical structure covered by fine bristles and appearing as a cowling or third tooth on the convex side of the main fang.  The life history of the species includes a period of asexual reproduction by architomy beginning soon after settlement, then sexual maturation and continuous breeding within an extended period with production of lecithotrophic larvae developing entirely inside egg capsules. Once mature, individuals probably reproduce only sexually and do not undergo additional architomic divisions.  Asexual reproduction results in high morphological variability of adult individuals, particularly in number, size, and arrangement of awl-like spines in notopodia. Polydora rogeri is placed into synonymy of D. armata. The original interpretation of the relationship between the polychaetes and the excavating sponge Cliona viridis as mutualistic symbiosis is discussed. Dipolydora armata is considered to be a widespread non-specialized borer perforating various calcareous substrata.

The structure and formation of growth-ridges in scleractinian coral skeletons

1972 ◽  
Vol 182 (1068) ◽  
pp. 331-350 ◽  
Keyword(s):  
Body Wall ◽  
External Surface ◽  
The Body ◽  
Daily Cycle ◽  
Daily Growth ◽  
Coral Skeletons ◽  
Growth Increments ◽  
Fossil Corals ◽  
History Of ◽  
Daily Changes

The external surface of the epitheca in modern and fossil corals is marked by tiny ridges lying parallel to the epithecal rim. These ridges have been assumed to be daily growth increments, and have been linked with supposed lunar and seasonal events recorded in the skeleton, to compute aspects of the history of the Earth’s rotation. This communication presents struc­tural and experimental evidence to show that the growth-ridges in the epithecae of modern hermatypic scleractinian corals, particularly Manicina areolata (Linnaeus), are formed as a result of daily changes in the shape of the tissues secreting the epithecae. The changes in shape of the tissues are an integral part of the mechanism by which the body wall of these corals is adjusted in position to accommodate for epithecal growth. This adjustment takes place in concert with a daily cycle of expansion and contraction of the animals. Because the epitheca is formed at the perimeter of the skeleton-secreting layer, its growth involves certain fundamental requirements. The presence of growth-ridges in all coral epi­thecae suggests that all corals meet, or met, these requirements with a similar mechanism to that which operates in the hermatypic species studied. However, the mechanism is not necessarily linked to a daily cycle of expansion and contraction.

Leg development in flies versus grasshoppers: differences in dpp expression do not lead to differences in the expression of downstream components of the leg patterning pathway

Development ◽  
2000 ◽  
Vol 127 (8) ◽  
pp. 1617-1626 ◽  
Author(s):  
E.L. Jockusch ◽  
C. Nulsen ◽  
S.J. Newfeld ◽  
L.M. Nagy
Keyword(s):  
Imaginal Disc ◽  
Body Wall ◽  
Molecular Mechanisms ◽  
Current Model ◽  
The Body ◽  
Genetic Interactions ◽  
Leg Development ◽  
Evolutionarily Conserved ◽  
Early Expression ◽  
Two Phases

All insect legs are structurally similar, characterized by five primary segments. However, this final form is achieved in different ways. Primitively, the legs developed as direct outgrowths of the body wall, a condition retained in most insect species. In some groups, including the lineage containing the genus Drosophila, legs develop indirectly from imaginal discs. Our understanding of the molecular mechanisms regulating leg development is based largely on analysis of this derived mode of leg development in the species D. melanogaster. The current model for Drosophila leg development is divided into two phases, embryonic allocation and imaginal disc patterning, which are distinguished by interactions among the genes wingless (wg), decapentaplegic (dpp) and distalless (dll). In the allocation phase, dll is activated by wg but repressed by dpp. During imaginal disc patterning, dpp and wg cooperatively activate dll and also indirectly inhibit the nuclear localization of Extradenticle (Exd), which divide the leg into distal and proximal domains. In the grasshopper Schistocerca americana, the early expression pattern of dpp differs radically from the Drosophila pattern, suggesting that the genetic interactions that allocate the leg differ between the two species. Despite early differences in dpp expression, wg, Dll and Exd are expressed in similar patterns throughout the development of grasshopper and fly legs, suggesting that some aspects of proximodistal (P/D) patterning are evolutionarily conserved. We also detect differences in later dpp expression, which suggests that dpp likely plays a role in limb segmentation in Schistocerca, but not in Drosophila. The divergence in dpp expression is surprising given that all other comparative data on gene expression during insect leg development indicate that the molecular pathways regulating this process are conserved. However, it is consistent with the early divergence in developmental mode between fly and grasshopper limbs.

scholarly journals TRP Channels in Visceral Pain

2013 ◽  
Vol 6 (1) ◽  
pp. 23-30 ◽  
Author(s):  
L. Ashley Blackshaw ◽  
Stuart M. Brierley ◽  
Andrea M. Harrington ◽  
Patrick A. Hughes
Keyword(s):  
Body Wall ◽  
Molecular Mechanisms ◽  
Trp Channels ◽  
Visceral Pain ◽  
Low Ph ◽  
The Body ◽  
Visceral Afferents ◽  
Somatic Pain ◽  
Oesophageal Mucosa ◽  
Chemosensory Function

Visceral pain is both different and similar to somatic pain - different in being poorly localized and usually referred elsewhere to the body wall, but similar in many of the molecular mechanisms it employs (like TRP channels) and the specialization of afferent endings to detect painful stimuli. TRPV1 is sensitive to low pH. pH is lowest in gastric juice, which may cause severe pain when exposed to the oesophageal mucosa, and probably works via TRPV1. TRPV1 is found in afferent fibres throughout the viscera, and the TRPV1 agonist capsaicin can recapitulate symptoms experienced in disease. TRPV1 is also involved in normal mechanosensory function in the gut. Roles for TRPV4 and TRPA1 have also been described in visceral afferents, and TRPV4 is highly enriched in them, where it plays a major role in both mechanonociception and chemonociception. It may provide a visceral-specific nociceptor target for drug development. TRPA1 is also involved in mechano-and chemosensory function, but not as selectively as TRPV4. TRPA1 is colocalized with TRPV1 in visceral afferents, where they influence each other's function. Another modulator of TRPV1 is the cool/mint receptor TRPM8, which, when activated can abrogate responses mediated via TRPV1, suggesting that TRPM8 agonists may provide analgesia via this pathway. In all, the viscera are rich in TRP channel targets on nociceptive neurones which we hope will provide opportunities for therapeutic analgesia.

scholarly journals A revision of <i>Ophidiaster davidsoni</i> de Loriol and Pellat 1874 from the Tithonian of Boulogne (France) and its transfer from the Valvatacea to the new forcipulatacean genus <i>Psammaster</i> gen. nov.

Fossil Record ◽  
2020 ◽  
Vol 23 (2) ◽  
pp. 141-149
Author(s):  
Marine Fau ◽  
Loïc Villier ◽  
Timothy A. M. Ewin ◽  
Andrew S. Gale
Keyword(s):  
Evolutionary History ◽  
Upper Cretaceous ◽  
Body Wall ◽  
The Body ◽  
Sea Stars ◽  
Fossil Species ◽  
Sister Clade ◽  
Extant Species ◽  
History Of ◽  
The Subject

Abstract. Forcipulatacea is one of the three major groups of extant sea stars (Asteroidea: Echinodermata), composed of 400 extant species, but only known from fewer than 25 fossil species. Despite unequivocal members being recognized in the early Jurassic, the evolutionary history of this group is still the subject of debate. Thus, the identification of any new fossil representatives is significant. We here reappraise Ophidiaster davidsoni de Loriol and Pellat 1874 from the Tithonian of Boulogne, France, which was assigned to another major extant group, the Valvatacea, and reassign it within a new forcipulatacean genus, Psammaster gen. nov. Psammaster davidsoni gen. nov. possess key Forcipulatacea synapomorphies including compressed ambulacrals and adambulacrals and typical organization of the body wall and arm ossicles. A phylogenetic analysis including Psammaster davidsoni gen. nov. does not place it within any existing forcipulatacean family. Instead, Psammaster davidsoni gen. nov. exhibits a mix of plesiomorphic and derived characters and is resolved as a sister clade to a large group including the Asteriidae, Stichasteridae, and Heliasteridae. Removal of this species from the Ophidiasteridae means their oldest fossil representative now dates from the Santonian, Upper Cretaceous.

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