Feeding in tornaria larvae and the development of gill slits in enteropneust hemichordates

1982 ◽  
Vol 60 (12) ◽  
pp. 3010-3020 ◽  
Author(s):  
T. H. J. Gilmour
Keyword(s):  
Body Wall ◽  
Dorsal Surface ◽  
Structure And Function ◽  
The Body ◽  
Flow Lines ◽  
Water Currents ◽  
Larval Stages ◽  
Excess Water ◽  
Preoral Lobe ◽  
And Function

The food-collecting and waste-rejecting systems of the tornaria larval stages of enteropneust hemichordates are similar to those of larval and adult lophophorates and adult pterobranch hemichordates. Water entering the oral grooves is deflected towards the mouth and the impetus of heavy, potentially inedible particles may take them across the flow lines of the water currents inferred from the movements of suspended particles to impinge on cilia which reject them into the outgoing water currents. Lighter, potentially edible material remaining suspended in the deflected water currents is intercepted by cilia on an oral hood which is similar in structure and function to the preoral lobe of the actinotroch larvae of phoronids. Excess water carried into the mouth by cilia on the dorsal surface of the esophagus is rejected via lateral grooves which develop into pouches prior to metamorphosis. Following metamorphosis the pouches make contact with the body wall to form gill slits which continue to allow water to escape from the pharynx. This finding that the function of allowing excess water to escape is performed by lateral grooves in the esophagus of tornariae supports previous speculations on the evolution of gill slits and provides further evidence for relationships between lophophorates, hemichordates, and chordates.

Ultrastructural morphology of the body wall, stoma, and stomatostyle of the nematode, Tylenchorhynchus dubius (Bütschli, 1873) Filipjev, 1936

1972 ◽  
Vol 50 (4) ◽  
pp. 457-465 ◽  
Author(s):  
J. R. Byers ◽  
R. V. Anderson
Keyword(s):  
Fine Structure ◽  
Body Wall ◽  
Parasitic Nematode ◽  
Structure And Function ◽  
The Body ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Ultrastructural Morphology ◽  
And Function ◽  
Plant Parasitic

The fine structure of the body wall, stoma, and stomatostyle of the plant parasitic nematode, Tylenchorhynchus dubius, is described. The body wall consists of a six-layered cuticle, about 1 μ thick, and a thin interchordal hypodermis. Some details of the labial framework and the cuticular lining of the stoma are described. The shaft of the stomatostyle is composed of five distinct layers. The attachment between the shaft and the stomatal cuticle is characterized by several specializations. One of these is an extensive attachment complex formed at the lateral junction between the stomatal and stylet epithelia. The protractor musculature consists of three main units which are each subdivided anteriorly into smaller elements. Also present are four secondary muscle elements which extend posteriorly beyond the base of the stylet and attach to the cuticular lining of the esophagus above the dorsal duct orifice.The ultrastructural morphology described for T. dubius is compared with that known for other plant parasitic nematodes. Some likely relationships between structure and function are also discussed.

scholarly journals Evidence of Regeneration of Testicular and Epididymal Tissue Structure and Function Following Withdrawal from Sub-chronic Khat Exposure: Studies in the Rabbit Animal Model

2020 ◽  
pp. 10-23
Author(s):  
Albert W. Nyongesaa ◽  
Esther M. Malukib ◽  
Jemimah A. Simbaunib
Keyword(s):  
Body Weight ◽  
Chronic Exposure ◽  
Structure And Function ◽  
The Body ◽  
Endocrine Function ◽  
Eastern Africa ◽  
Blood Samples ◽  
Middle East Countries ◽  
Group I ◽  
And Function

Khat, Catha edulis, use is rampant in Eastern Africa and Middle East countries with associated reports of reproductive function impairment in the body of the user. Reports on recovery post long-term khat exposure are obscure. The present study investigated evidence of restoration of testicular and epididymal structure and function during withdrawal from cytotoxic damage caused by sub-chronic exposure of khat extract. Twenty-eight male rabbits were divided into 7 groups of 4 rabbits each. Group I (control) was administered normal saline while groups II, III and IV were administered 1.0 g/kg, 10 g/kg and 20 g/kg body weight of khat extract, respectively, via oral gavage on alternate days of the week for 12 weeks. Blood samples from animals were collected for hormonal assays followed by euthanasia using 26.4 mg/kg body weight of Sagatal sodium intramuscularly for testicular and epididymal histology. Group V, VI and VII were administered 1.0 g/kg, 10 g/kg and 20 g/kg body weight of khat extract, respectively, orally on alternate days of the week for 12 weeks followed by 1-month withdrawal period, blood samples collected for hormone assays and animals sacrificed for testicular and epididymal histology. High khat dose, 20 g/kg body weight, at sub-chronic exposure caused degeneration in spermatogenic cells with accompanying decrease in plasma FSH and testosterone. Histological output of Sertoli cells, Leydig cells and epididymal epithelium appeared unaffected in treatment groups. Post withdrawal data showed apparent regeneration of seminiferous epithelium and restoration of plasma FSH and testosterone comparable to control. It appears khat extract preferentially affected germ cell spermatogonia and subsequent daughter cells while stem cell spermatogonia were unaffected and contributed to regeneration of germinal epithelium and endocrine function.

Memoirs: The Development of the Serpiilid Pomatoeeros Triqueter L

1941 ◽  
Vol s2-82 (327) ◽  
pp. 467-540 ◽  
Author(s):  
F. SEGROVE
Keyword(s):  
Body Wall ◽  
Feeding Activity ◽  
Dorsal Surface ◽  
The Body ◽  
Single Pair ◽  
Feeding Apparatus ◽  
Food Material ◽  
Locomotor Apparatus ◽  
Adult Feeding ◽  
Branchial Crown

1. The larvae of Pomatoceros triqueter L. were obtained by artificial fertilization and reared through metamorphosis and for several months afterwards. Larval development took three weeks in summer, and about the same time in winter when the temperature was maintained at 65° F. 2. The eggs are small and give rise to typical trochosphere larvae with well-developed prototroch, metatroch, neurotroch, and feeding cilia, a spacious blastocoelic body-cavity and paired protonephridia. A head-vesicle and a conspicuous anal vesicle are also present. The right eye develops before the left. The larva is very active and grows rapidly at the expense of collected food material. 3. Three setigerous segments arise simultaneously; a fourth is added prior to metamorphosis. The lateral collar-folds develop in two capacious pockets which arise by invagination of the body-wall behind the metatroch, the ventral collar-fold by outgrowth of the ventral body-wall. The rudiments of the thoracic membrane appear above the lateral collar-folds. 4. Metamorphosis commences with the shrinkage of the locomotor apparatus, which leads to the exposure of the lateral collar-folds. The larva settles to the bottom and creeps about on its ventral surface by means of the neurotroch. The branchial crown arises as tripartite outgrowths on the sides of the head. The remaining tissues of the head, apart from the cerebral ganglion and eyes, are gradually resorbed. No tissue is thrown off. 5. The neurotroch gradually disappears and is replaced by cilia on the dorsal surface. The worm begins to secrete a calcareous tube. The resorption of the head is completed and the mouth assumes a terminal position surrounded by the branchial crown. 6. A fourth pair of filaments is added to the branchial crown. The dorsal pair of filaments develops into 'palps'. The third filament on the left side is modified as the operculum; the remaining filaments develop pinnules. 7. Further segments are added to the trunk. Those first added are of the thoracic type from the beginning. The eighth and succeeding setigers are of the abdominal type. The thoracic membrane gradually extends backwards to the posterior end of the thorax. 8. The thoracic nephridia arise as a single pair of cells which give rise to the dorsal unpaired duct by outgrowth. 9. The influence of the egg on the course of development is discussed. It is suggested: (a) that the small size of the egg is responsible for the active habits and protracted pelagic life of the larva; (b) that the mode of development of the collar is significant in that interference with the locomotor and feeding apparatus is thereby avoided; (c) that the general shrinkage which occurs at metamorphosis is related to a suspension of feeding activity in the period between the degeneration of the larval and the establishment of the adult feeding apparatus. 10. The development of Pomatoceros is compared with that of the Serpulid Psygmobranchus and the Sabeilid Branchiomma.

mirror, a Drosophila homeobox gene in the Iroquois complex, is required for sensory organ and alula formation

Development ◽  
1998 ◽  
Vol 125 (7) ◽  
pp. 1217-1227 ◽  
Author(s):  
B.T. Kehl ◽  
K.O. Cho ◽  
K.W. Choi
Keyword(s):  
Protein Structure ◽  
Genetic Analysis ◽  
Genetic Map ◽  
Body Wall ◽  
Homeobox Gene ◽  
Structure And Function ◽  
The Other ◽  
Complex Region ◽  
Sensory Bristles ◽  
And Function

The Drosophila notum, the dorsal body wall of the thorax, is subdivided genetically into longitudinal domains (Calleja, M., Moreno, E., Pelaz, S. and Morata, G. (1996) Science 274, 252–255). Two homeobox genes clustered in the iroquois complex, araucan and caupolican, regulate proneural genes and are required for development of sensory bristles in the lateral notum (Gomez-Skarmeta, J. L., del Corral, R. D., de la Calle-Mustienes, E., Ferres-Marco, D. and Modolell, J. (1996) Cell 85, 95–105). An iroquois-related homeobox gene, mirror, was recently isolated and is localized close to the iroquois complex region (McNeil, H., Yang, C.-H., Brodsky, M., Ungos, J. and Simon, M. A. (1997) Genes and Development 11, 1073–1082; this study). We show that mirror is required for the formation of the alula and a subset of sensory bristles in the lateral domain of the notum. Genetic analysis suggests that mirror and the other iroquois genes interact to form the alula as well as the sensory organs. Based on similarities between mirror and the iroquois genes in their genetic map positions, expression, protein structure and function, mirror is considered a new member of the iroquois complex and is involved in prepatterning sensory precursor cells in the lateral notum.

The evolution of air-breathing respiratory faculties in craniotes

2019 ◽  
pp. 177-191
Author(s):  
Steven F. Perry ◽  
Markus Lambertz ◽  
Anke Schmitz
Keyword(s):  
High Performance ◽  
Body Wall ◽  
Structure And Function ◽  
Control Of Breathing ◽  
Body Wall Muscle ◽  
Positive Pressure ◽  
Limiting Factor ◽  
Swim Bladder ◽  
Body Wall Musculature ◽  
And Function

The origin of lungs from a swim bladder, swim bladder from lungs, or both from a relatively undifferentiated respiratory pharynx remains unresolved. Once present, the lungs can be ventilated by a positive-pressure buccal pump, which can be easily derived from the gill ventilation sequence in a lungfish, or by negative-pressure aspiration. Although aspiration breathing is characteristic of amniotes, it has also been observed in a lungfish and body wall muscle contraction in response to respiratory stimuli has even been reported in lamprey larvae. The hypaxial body wall musculature used for aspiration breathing is also necessary for locomotion in most amniotes, just when respiratory demand is greatest. This paradox, called Carrier’s constraint, is a major limiting factor in the evolution of high-performance faculties, and the evolution of anatomical and physiological specializations that circumvent it characterize most major amniote groups. Serendipitous combinations have resulted in evolutionary cascades and high-performance groups such as birds and mammals. Complementing evolution are the capacities for acclimatization and adaptation not only in the structure and function of the gas exchanger, but also in the control of breathing and the composition of the blood.

Cellular structure and function

2021 ◽  
pp. 1-104
Keyword(s):  
Plasma Membrane ◽  
Nucleic Acids ◽  
Cellular Structure ◽  
Structure And Function ◽  
The Body ◽  
Signalling Pathways ◽  
Cellular Functions ◽  
Pharmacological Agents ◽  
Intracellular Organelles ◽  
And Function

‘Cellular structure and function’ covers the roles, structures, and functions of the main four types of macromolecules of the human body, namely proteins, lipids, carbohydrates, and nucleic acids. For these macromolecules, the roles and types of each class are discussed (for proteins this includes their roles as structural proteins and enzymes and their kinetics; for lipids, the roles and types of lipid found in the body are considered; for carbohydrates, their roles including structural and metabolic are discussed; and the structure of nucleic acids is described). Then follows a description of the organization of the cell, including the plasma membrane and its components, and the intracellular organelles. Cell growth, division, and apoptosis are covered, as are the formation of gametes, and finally the principles of how cellular functions can be modulated by pharmacological agents through receptors and signalling pathways are discussed.

scholarly journals Structure and Function of the Body

1969 ◽  
Vol 69 (5) ◽  
pp. 1075
Author(s):  
Faustena Blaisdell ◽  
Catherine Parker Anthony
Keyword(s):  
Structure And Function ◽  
The Body ◽  
And Function

scholarly journals Structural Characterization of Carbonic Anhydrase VIII and Effects of Missense Single Nucleotide Variations to Protein Structure and Function

2020 ◽  
Vol 21 (8) ◽  
pp. 2764
Author(s):  
Taremekedzwa Allan Sanyanga ◽  
Özlem Tastan Bishop
Keyword(s):  
Carbonic Anhydrase ◽  
Binding Site ◽  
Cross Correlation ◽  
Structure And Function ◽  
The Body ◽  
Conformational Sampling ◽  
Nucleotide Polymorphisms ◽  
Ip3 Receptor ◽  
Single Nucleotide ◽  
And Function

Human carbonic anhydrase 8 (CA-VIII) is an acatalytic isoform of the α -CA family. Though the protein cannot hydrate CO2, CA-VIII is essential for calcium (Ca2+) homeostasis within the body, and achieves this by allosterically inhibiting the binding of inositol 1,4,5-triphosphate (IP3) to the IP3 receptor type 1 (ITPR1) protein. However, the mechanism of interaction of CA-VIII to ITPR1 is not well understood. In addition, functional defects to CA-VIII due to non-synonymous single nucleotide polymorphisms (nsSNVs) result in Ca2+ dysregulation and the development of the phenotypes such as cerebellar ataxia, mental retardation and disequilibrium syndrome 3 (CAMRQ3). The pathogenesis of CAMRQ3 is also not well understood. The structure and function of CA-VIII was characterised, and pathogenesis of CAMRQ3 investigated. Structural and functional characterisation of CA-VIII was conducted through SiteMap and CPORT to identify potential binding site residues. The effects of four pathogenic nsSNVs, S100A, S100P, G162R and R237Q, and two benign S100L and E109D variants on CA-VIII structure and function was then investigated using molecular dynamics (MD) simulations, dynamic cross correlation (DCC) and dynamic residue network (DRN) analysis. SiteMap and CPORT analyses identified 38 unique CA-VIII residues that could potentially bind to ITPR1. MD analysis revealed less conformational sampling within the variant proteins and highlighted potential increases to variant protein rigidity. Dynamic cross correlation (DCC) showed that wild-type (WT) protein residue motion is predominately anti-correlated, with variant proteins showing no correlation to greater residue correlation. DRN revealed variant-associated increases to the accessibility of the N-terminal binding site residues, which could have implications for associations with ITPR1, and further highlighted differences to the mechanism of benign and pathogenic variants. SNV presence is associated with a reduction to the usage of Trp37 in all variants, which has implications for CA-VIII stability. The differences to variant mechanisms can be further investigated to understand pathogenesis of CAMRQ3, enhancing precision medicine-related studies into CA-VIII.

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