Theoretical morphology of hinge and shell form in Bivalvia: geometric constraints derived from space conflict between umbones

Paleobiology ◽  
2000 ◽  
Vol 26 (4) ◽  
pp. 606-624 ◽  
Author(s):  
Takao Ubukata
Keyword(s):  
Computer Simulation ◽  
Anterior Part ◽  
Large Degree ◽  
Ventral Side ◽  
Mutual Interference ◽  
Geometric Constraints ◽  
Geometric Properties ◽  
Shell Form ◽  
Theoretical Morphology

Geometric properties of the shells of 123 species of extant Bivalvia were analyzed from the viewpoint of theoretical morphology. The effects of shell form and the structure of ligament on the interumbonal space and the maximum shell opening received particular attention. The results of computer simulation and morphospace analysis indicate that possessing both prosogyrous shell form and an extended hinge without the parivincular ligament tends to cause space conflict between umbones or dorsal shell margins of right and left valves. To a large degree, a prosogyrous shell form with a long parivincular ligament helps shell opening without umbonal conflict, if the shell is flat enough to avoid the mutual interference between dorsal shell margins of closed valves. Extension of the ligament and plunging of the anterior part of the coiling axis into the ventral side provide enough space along the dorsal shell margins in which a parivincular ligament and its substrata are developed.

scholarly journals A Constraint Solver for Flexible Protein Model

2013 ◽  
Vol 48 ◽  
pp. 953-1000 ◽  
Author(s):  
F. Campeotto ◽  
A. Dal Palù ◽  
A. Dovier ◽  
F. Fioretto ◽  
E. Pontelli
Keyword(s):  
Structure Prediction ◽  
Dimensional Space ◽  
Protein Structures ◽  
Empirical Evaluation ◽  
Geometric Constraints ◽  
Conformational Space ◽  
Loop Modeling ◽  
Geometric Properties ◽  
Constraint Solver ◽  
Multi Body

This paper proposes the formalization and implementation of a novel class of constraints aimed at modeling problems related to placement of multi-body systems in the 3-dimensional space. Each multi-body is a system composed of body elements, connected by joint relationships and constrained by geometric properties. The emphasis of this investigation is the use of multi-body systems to model native conformations of protein structures---where each body represents an entity of the protein (e.g., an amino acid, a small peptide) and the geometric constraints are related to the spatial properties of the composing atoms. The paper explores the use of the proposed class of constraints to support a variety of different structural analysis of proteins, such as loop modeling and structure prediction. The declarative nature of a constraint-based encoding provides elaboration tolerance and the ability to make use of any additional knowledge in the analysis studies. The filtering capabilities of the proposed constraints also allow to control the number of representative solutions that are withdrawn from the conformational space of the protein, by means of criteria driven by uniform distribution sampling principles. In this scenario it is possible to select the desired degree of precision and/or number of solutions. The filtering component automatically excludes configurations that violate the spatial and geometric properties of the composing multi-body system. The paper illustrates the implementation of a constraint solver based on the multi-body perspective and its empirical evaluation on protein structure analysis problems.

Commensalism of a Bivalve, Peregrinamor Ohshimai, With a Thalassinidean Burrowing Shrimp, Upogebia Major

1995 ◽  
Vol 75 (4) ◽  
pp. 941-947 ◽  
Author(s):  
Makoto Kato ◽  
Gyo Itani
Keyword(s):  
Shell Length ◽  
Suspended Matter ◽  
Carapace Length ◽  
Anterior Part ◽  
Living Organism ◽  
Ventral Side ◽  
Filter Feeding ◽  
Water Currents ◽  
Veliger Larva ◽  
The Seto Inland Sea

Ecological, behavioural and anatomical observations of a commensal bivalve, Peregrinamor ohshimai (Mollusca: Galeommatoidea), were carried out in a tidal mudflat in the Seto Inland Sea, Japan. The bivalve attached specifically to the longitudinal groove of the ventral side of the cephalothorax of thalassinidean burrowing shrimps, Upogebia major and Lf. narutensis (Crustacea: Decapoda), singly, dorso-ventrally and longitudinally, using its byssus, with its anterior part towards the head of the host. The mantle of the commensal bivalve has wide anterior (branchio-pedal) and narrow posterior (exhalant) apertures. In the living organism, the extended anterior edges of the mantle protrude from the shell and are inserted into the host's filtering basket, which is formed by the setal rows of the first two pairs of pereiopods and utilized for intercepting suspended matter. By beating its pleopods in a U-shaped burrow, the filter-feeding Upogebia shrimp creates water currents, which are also utilized by the commensal bivalve for filter-feeding. The shell length of the commensal bivalve was in proportion to the host's carapace length. This suggests that the veliger larva attaches to a young host and grows, thus maintaining the host-commensal morphological matching. The bivalve is a hermaphrodite and individuals of >8–5 mm in shell length were already producing eggs. Anatomical observations suggest that P. ohshimai is most closely related to the Montacutidae in Galeommatoidea.

Synthesis and Analysis of 4-DOF Parallel Manipulators of Computer Aided Geometry Approach

2014 ◽  
Vol 912-914 ◽  
pp. 1010-1016
Author(s):  
Yan Hua Zhang ◽  
Xiu Ju Du ◽  
Bai Yong Zhang
Keyword(s):  
Computer Simulation ◽  
Kinematic Analysis ◽  
Geometric Approach ◽  
Parallel Manipulators ◽  
Geometric Constraints ◽  
Type Synthesis ◽  
Moving Platforms ◽  
Kinematic Characteristics ◽  
Computer Aided

A novel computer aided geometry approach for type synthesis and analysis of new spatial 4-DOF parallel manipulators is put forward, and create the computer simulation mechanisms of parallel manipulators using the geometric constraints and dimension driving techniques in CAD software, Based on the computer simulation mechanisms of parallel manipulators, several new spatial 4-DOF parallel manipulators are synthesized, the kinematic characteristics of the moving platforms are analyzed by computer simulation. The results of computer simulation prove that the computer aided geometric approach for solving type synthesis and kinematic analysis is not only fairly quick and straightforward, but also has the advantages of accuracy.

scholarly journals Morphogenesis of the Ciliature During Sexual Process of Conjugation in the Ciliated Protist Euplotes raikovi

2021 ◽  
Vol 7 ◽  
Author(s):  
Usman Asghar ◽  
Yong Chi ◽  
Yunyi Gao ◽  
Borong Lu ◽  
Yaohan Jiang ◽  
...  
Keyword(s):  
De Novo ◽  
Anterior Part ◽  
Posterior Part ◽  
Marine Species ◽  
Ventral Side ◽  
Fragmentation Pattern ◽  
Morphogenetic Process ◽  
Stable Pattern ◽  
Sexual Process ◽  
Euplotes Raikovi

Morphogenesis is an important process that widely occurs in almost all the organisms, including the ciliated protists. Ciliates are a large group of single-celled eukaryotes that can reproduce asexually (e.g., binary fission) and perform sexual process (e.g., conjugation). Morphogenesis happens in both asexual reproduction and sexual process in ciliates and the reorganization during conjugation is more complex. However, studies of morphogenesis focusing on conjugation are very limited. Here we studied the morphogenetic process during conjugation in the marine species Euplotes raikovi Agamaliev, 1966. The results indicate that: (1) the ciliature in the ventral side reorganizes twice during sexual process, i.e., conjugational and postconjugational reorganization; (2) the adoral zone of membranelles (AZM) is generated de novo in a pouch beneath the cortex during both reorganizations, with the anterior part generated during the first reorganization, while the posterior part formed during the second reorganization; (3) the frontoventral-transverse (FVT) cirri anlagen are formed de novo in both processes with the fragmentation pattern of 2:2:3:3:2; (4) one left marginal cirrus is generated de novo during both reorganizations; and (5) the dorsal ciliature remains intact during the whole process, except that the two caudal cirri originate from the end of the right-most two dorsal kineties during both reorganizations. Comparisons of the morphogenetic process during conjugation demonstrate a considerably stable pattern within Euplotes while the patterns vary dramatically among different ciliate groups.

Fasciola gigantica: surface topography of the adult tegument

2001 ◽  
Vol 75 (1) ◽  
pp. 43-50 ◽  
Author(s):  
T. Dangprasert ◽  
W. Khawsuk ◽  
A. Meepool ◽  
C. Wanichanon ◽  
V. Viyanant ◽  
...  
Keyword(s):  
Anterior Part ◽  
Ventral Side ◽  
Ventral Surface ◽  
Dorsal Side ◽  
Fasciola Gigantica ◽  
The Body ◽  
Lateral Aspect ◽  
Tegumental Surface ◽  
Type 3

Adult Fasciola gigantica are leaf-shaped with tapered anterior and posterior ends and measure about 35 mm in length and 15 mm in width across the mid section. Under the scanning electron microscope its surface appears rough due to the presence of numerous spines and surface foldings. Both oral and ventral suckers have thick rims covered with transverse folds and appear spineless. On the anterior part of the ventral surface of the body, the spines are small and closely-spaced. Each spine has a serrated edge with 16 to 20 sharp points, and measures about 20 μm in width and 30 μm in height. In the mid-region the spines increase in size (up to 54 μm in width and 58 μm in height) and number, especially towards the lateral aspect of the body. Towards the posterior end the spines progressively decrease in both size and number. The tegumental surface between the spines appears highly corrugated with transverse folds alternating with grooves. At higher magnifications the surface of each fold is further increased with a meshwork of small ridges separated by variable-sized pits or slits. There are three types of sensory papillae on the surface. Types 1 and 2 are bulbous, measuring 4–6 μm in diameter at the base with nipple-like tips, and the type 2 also have short cilia. Type 3 papillae are also bulbous and of similar size but with a smooth surface. These sensory papillae usually occur in clusters, each having between 2 and 15 units depending on the region of the body. Clusters of papillae on the lateral aspect (usually types 1 and 2) and around the suckers (type 3) tend to be more numerous and larger in size. The dorsal side of the body exhibits similar surface features, but the spines and papillae appear less numerous and are smaller. Corrugation and invaginations of the surface are also less extensive than on the ventral side of the body.

Three new and a known species of Tylencholaimoidea (Nematoda: Dorylaimida) from Singapore

Zootaxa ◽  
2010 ◽  
Vol 2505 (1) ◽  
pp. 51 ◽  
Author(s):  
WASIM AHMAD ◽  
M. BANIYAMUDDIN
Keyword(s):  
Anterior Part ◽  
Ventral Side ◽  
Cylindrical Part ◽  
Genital System ◽  
Muscular Structure ◽  
Female Genital System ◽  
Basal Bulb ◽  
First Time ◽  
Labial Disc ◽  
Female Genital

Three new and a known species of soil-inhabiting nematodes belonging to the superfamily Tylencholaimoidea Filipjev, 1934 are described and illustrated from Singapore. Tantunema enigmatum n. sp. is characterised by having 0.33–0.41 mm long body; angular, distinctly offset lip region; well developed circumoral sclerotization; odontostyle slender with aperture about one-fourth of its length; simple rod-like odontophore; anterior part of pharynx slender, weakly muscular, expanding abruptly into a cylindroid basal bulb, constriction present between two parts of pharynx; expanded portion divisible into a short conical, less muscular anterior part and a posterior muscular cylindrical part with thickened inner lining; lumen of the posterior one-third of expanded portion distinctly widened and thickened; mono-opisthodelphic female genital system and short hemispheroid tail. Dorella shamimi n. sp. is characterised by having 0.58–0.62 mm long body; continuous lip region with indistinct labial papillae; labial disc absent; 10–10.5 µm long odontostyle with a large pad-like muscular structure attached on ventral side of posterior half of its length extending to the anterior part of the odontophore; odontophore asymmetrical with round, transparent, knob-like thickening; pharynx with a short terminal oval bulb; mono-prodelphic female genital system with a short post-uterine sac; short conoid tail, with rounded terminus, and males with 18–18.5 µm long, simple arcuate spicules and a single ventromedian supplement. Tylencholaimus singaporensis n. sp. is characterized by having 0.35–0.47 mm long body; distinctly offset, cap-like lip region, 4.5–5.5 µm long, slender odontostyle, simple rod-like odontophore with small but distinct basal knobs, pharyngeal expansion abrupt, mono-prodelphic genital system with no post-uterine sac, and short hemispheroid tail with distinct terminal caudal pore. Tylencholaimus intermedius Peña-Santiago & Coomans, 1996 is reported for the first time from Singapore.

Fenestrate graptolite theoretical morphology: Geometric constraints on lophophore shape and arrangement in extinct hemichordates

2003 ◽  
Vol 77 (2) ◽  
pp. 360-367 ◽  
Author(s):  
Robert W. Starcher ◽  
George R. McGhee
Keyword(s):  
Geometric Analysis ◽  
Close Packing ◽  
Geometric Constraints ◽  
Theoretical Morphology ◽  
Packing Arrangement

A geometric analysis of lophophore shape and arrangement in the fenestrate dendroid graptolite genus Dictyonema reveals that the shape of the zooid domain in the majority of Dictyonema species colonies is highly elliptical, with the long axis of the ellipse perpendicular to the proximodistal axis of the stipe. A complex lophophore, bilaterally symmetrical and consisting of two tentaculated arms that are laterally directed and perpendicular to the stipe axis, provides the best geometric solution to completely filling the elliptical zooid domain seen in the majority of Dictyonema species.Working under the assumption that fenestrate graptolites, like fenestrate bryozoans, needed to form a continuous filtering surface with contact between adjacent lophophores, two optimum close-parking models exist for lophophores with elliptical zooid domains: either a proximodistal-row arrangement or a lateral-row arrangement of the lophophores. Of the two possible geometries, the most probable close-packing arrangement of hypothetical biplumed lophophores within the fenestrate graptolite meshwork is in proximodistal rows.

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