scholarly journals Cellular morphology of leg musculature in the water bear Hypsibius exemplaris (Tardigrada) unravels serial homologies

2019 ◽  
Vol 6 (10) ◽  
pp. 191159 ◽  
Author(s):  
Vladimir Gross ◽  
Georg Mayer
Keyword(s):  
Fine Structure ◽  
Functional Morphology ◽  
Cellular Structure ◽  
Evolutionary History ◽  
Ancestral State ◽  
Leg Muscles ◽  
Open Questions ◽  
Attachment Sites ◽  
Functional Implications ◽  
Water Bears

Tardigrades (water bears) are microscopic, segmented ecdysozoans with four pairs of legs. Lobopodous limbs that are similar to those seen in tardigrades are hypothesized to represent the ancestral state of Panarthropoda (Tardigrada + Onychophora + Arthropoda), and their evolutionary history is important to our understanding of ecdysozoan evolution. Equally important is our understanding of the functional morphology of these legs, which requires knowledge of their musculature. Tardigrade musculature is well documented but open questions remain. For example, while the muscular organization of each trunk segment and its legs is unique, three of the four trunk segments are nevertheless relatively homonomous. To what extent, then, do leg muscles show segmental patterns? Specifically, which leg muscles are serially repeated and which are unique? The present study addresses these questions using a combination of techniques intended to visualize both the overall layout and fine structure of leg muscles in the eutardigrade Hypsibius exemplaris . In doing so, we propose serial homologies for all leg muscles in each of the four legs and reveal new details of their cellular structure and attachment sites. We compare our results to those of previous studies and address the functional implications of specialized muscle cell morphologies.

scholarly journals Constraints on the ecomorphological convergence of zooplanktivorous butterflyfishes

2021 ◽  
Author(s):  
Jennifer R Hodge ◽  
Yutong Song ◽  
Molly A Wightman ◽  
Analisa Milkey ◽  
Binh Tran ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Swimming Performance ◽  
Morphological Evolution ◽  
Distinct Type ◽  
Ancestral State ◽  
Multiple Traits ◽  
Visual Identification ◽  
Form Function ◽  
Morphological Distinction ◽  
Foraging Modes

Abstract Whether distantly related organisms evolve similar strategies to meet the demands of a shared ecological niche depends on their evolutionary history and the nature of form-function relationships. In fishes, the visual identification and consumption of microscopic zooplankters, selective zooplanktivory, is a distinct type of foraging often associated with a suite of morphological specialisations. Previous work has identified inconsistencies in the trajectory and magnitude of morphological change following transitions to selective zooplanktivory, alluding to the diversity and importance of ancestral effects. Here we investigate whether transitions to selective zooplanktivory have influenced the morphological evolution of marine butterflyfishes (family Chaetodontidae), a group of small-prey specialists well known for several types of high-precision benthivory. Using Bayesian ancestral state estimation, we inferred the recent evolution of zooplanktivory among benthivorous ancestors that hunted small invertebrates and browsed by picking or scraping coral polyps. Traits related to the capture of prey appear to be functionally versatile with little morphological distinction between species with benthivorous and planktivorous foraging modes. In contrast, multiple traits related to prey detection or swimming performance are evolving toward novel, zooplanktivore-specific optima. Despite a relatively short evolutionary history, general morphological indistinctiveness, and evidence of constraint on the evolution of body size, convergent evolution has closed a near significant amount of the morphological distance between zooplanktivorous species. Overall, our findings describe the extent to which the functional demands associated with selective zooplanktivory have led to generalisable morphological features among butterflyfishes and highlight the importance of ancestral effects in shaping patterns of morphological convergence.

scholarly journals Glycosylation of matrix metalloproteases and tissue inhibitors: present state, challenges and opportunities

2016 ◽  
Vol 473 (11) ◽  
pp. 1471-1482 ◽  
Author(s):  
Lise Boon ◽  
Estefania Ugarte-Berzal ◽  
Jennifer Vandooren ◽  
Ghislain Opdenakker
Keyword(s):  
Matrix Metalloproteinases ◽  
Present State ◽  
Cellular Localization ◽  
Current Knowledge ◽  
Matrix Metalloproteases ◽  
Inhibitor Binding ◽  
Attachment Sites ◽  
Functional Aspects ◽  
Functional Implications ◽  
Challenges And Opportunities

Current knowledge about the glycosylation of matrix metalloproteinases (MMPs) and the inhibitors of metalloproteinases (TIMPs) is reviewed. Whereas structural and functional aspects of the glycobiology of many MMPs is unknown, research on MMP-9 and MMP-14 glycosylation reveals important functional implications, such as altered inhibitor binding and cellular localization. This, together with the fact that MMPs contain conserved and many potential attachment sites for N-linked and O-linked oligosaccharides, proves the need for further studies on MMP glycobiology.

Fine structure and functional morphology of the mouthparts of a maleVeigaia sp. (Gamasida: Veigaiidae) with remarks on the spermatodactyl and related sensory structures

2006 ◽  
Vol 267 (2) ◽  
pp. 208-220 ◽  
Author(s):  
Antonella Di Palma ◽  
Gerd Alberti ◽  
Giorgio Nuzzaci ◽  
Gerald W. Krantz
Keyword(s):  
Fine Structure ◽  
Functional Morphology ◽  
Sensory Structures

The Biology of Bothrimonus (=Diplocotyle) (Pseudophyllidea: Cestoda): Detailed Morphology and Fine Structure

1974 ◽  
Vol 31 (2) ◽  
pp. 147-153 ◽  
Author(s):  
M. D. B. Burt ◽  
I. M. Sandeman
Keyword(s):  
Electron Microscopy ◽  
Nervous System ◽  
Fine Structure ◽  
Functional Morphology ◽  
Light And Electron Microscopy ◽  
Nerve Fibers ◽  
Fish Host ◽  
Extensive System ◽  
And Function

Light and electron microscopy were used to describe the functional morphology of Bothrimonus sturionis in detail. In particular, the musculature, nervous system, osmoregulatory system, and tegument are dealt with, and the findings compared with those of other workers. The musculature of the scolex consists of several interrelated systems, the structure of each being discussed in relation to its function. Associated with the regular nervous system, considered typical of cestodes, is an extensive system of giant nerve fibers. The osmoregulatory system is unusual in that there are lateral "excretory" pores in many proglottides which open directly to the exterior of the worm. The microtriches of the tegument are long, like those of other primitive cestodes, and are covered by a noncellular sheath while the worm is in its gammarid host. The sheath is lost when the worm becomes established in its fish host; the nature and function of the sheath are discussed.

The jumping mechanism of Xenopsylla cheopis II. The fine structure of the jumping muscle

1975 ◽  
Vol 271 (914) ◽  
pp. 491-497 ◽  
Keyword(s):  
Fine Structure ◽  
Sarcoplasmic Reticulum ◽  
Surface Area ◽  
Large Surface Area ◽  
Muscle Fibres ◽  
Regular Array ◽  
Xenopsylla Cheopis ◽  
Leg Muscles ◽  
Depressor Muscle

The ultrastructure of the trochanteral depressor muscle of the oriental rat flea is described. It is shown to be similar to that of the tubular leg muscles of other insects except in the volume and arrangement of the sarcoplasmic reticulum. The sarcoplasmic reticulum occupies approximately 18% of the volume of the muscle fibres. It is in three configurations: a regular array of parallel tubules opposite the A-band, a collar of sacculi involved in the formation of the dyads at the edge of the A-band and a loosely woven arrangement of tubules around the I-band. This tripartite arrangement of the sarcoplasmic reticulum and its large surface area is discussed in relation to the action of the muscle as the main propulsive muscle in the jump of the flea.

Middle Nineteenth-Century Crinoid Studies Of Thomas Austin, Sr. And Thomas Austin, Jr.: Newly Discovered Unpublished Materials

1999 ◽  
Vol 18 (2) ◽  
pp. 180-197 ◽  
Author(s):  
William Ausich ◽  
George Sevastopulo ◽  
Hugh Torrens
Keyword(s):  
Nineteenth Century ◽  
Functional Morphology ◽  
Evolutionary History ◽  
Evolutionary Trends ◽  
Historical Interpretation ◽  
Medicinal Uses ◽  
History Of ◽  
Broad Outline

Thomas Austin, Sr. (1794-1881) and to a lesser extent his son Thomas Austin, Jr. (1817-before 1881) are recognized as important early students of both Carboniferous and Jurassic crinoids. However, the extent of their understanding of crinoids was not appreciated until the recent discovery of unpublished materials of Austin, Sr., including a manuscript dated 1855, plates indicating the intended continuation of their never finished 1843-1849 systematic monograph, and photographs of fossil crinoids.Within at most three and one-half decades after Johann Samuel Miller (1779-1830) first named the class Crinoidea in 1821, Austin, Sr. accurately summarized the broad outline of crinoid evolutionary history. Furthermore, Austin had a post-natural-historical interpretation of fossil crinoids. Fossil crinoids were not just ancient organisms to be described and classified, but Austin tried to interpret the biology of these fossils. Furthermore, he considered questions of taphonomy, functional morphology, paleoecology, processes controlling evolutionary trends, and crinoid deposits—still topics of interest to paleobiologists 150 years later; and he also discussed crinoid "evolution" and extinction. Other discussion is present on the history of crinoid studies from a middle-1800's perspective and on the superstitious and medicinal uses of crinoid fossils.But fain Saint Hilda's nuns would learn If, on a rock by Lindisfarne, Saint Cuthbert sits, and toils to frame The sea-born beads that bear his name: Such tales had Whitby's fishers told, And said they might his shape behold, And hear his anvil sound; A deaden'd clang,-a huge dim form Seen but, and heard, when gathering storm And night were closing round. But this, as tale of idle fame, The nuns of Lindisfarne disclaim.

scholarly journals Two NLR immune receptors acquired high-affinity binding to a fungal effector through convergent evolution of their integrated domain

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Aleksandra Białas ◽  
Thorsten Langner ◽  
Adeline Harant ◽  
Mauricio P Contreras ◽  
Clare EM Stevenson ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Plant Pathogens ◽  
Phylogenetic Analyses ◽  
Domain Architecture ◽  
Affinity Binding ◽  
Ancestral State ◽  
Evolutionary Mechanisms ◽  
High Affinity Binding ◽  
High Affinity ◽  
Immune Receptors

A subset of plant NLR immune receptors carry unconventional integrated domains in addition to their canonical domain architecture. One example is rice Pik-1 that comprises an integrated heavy metal-associated (HMA) domain. Here, we reconstructed the evolutionary history of Pik-1 and its NLR partner, Pik-2, and tested hypotheses about adaptive evolution of the HMA domain. Phylogenetic analyses revealed that the HMA domain integrated into Pik-1 before Oryzinae speciation over 15 million years ago and has been under diversifying selection. Ancestral sequence reconstruction coupled with functional studies showed that two Pik-1 allelic variants independently evolved from a weakly binding ancestral state to high-affinity binding of the blast fungus effector AVR-PikD. We conclude that for most of its evolutionary history the Pik-1 HMA domain did not sense AVR-PikD, and that different Pik-1 receptors have recently evolved through distinct biochemical paths to produce similar phenotypic outcomes. These findings highlight the dynamic nature of the evolutionary mechanisms underpinning NLR adaptation to plant pathogens.

scholarly journals Directional sensitivity of the retina: 75 years of Stiles–Crawford effect

2008 ◽  
Vol 275 (1653) ◽  
pp. 2777-2786 ◽  
Author(s):  
Gerald Westheimer
Keyword(s):  
Spatial Distribution ◽  
Fine Structure ◽  
Luminous Efficiency ◽  
Visual Performance ◽  
Directional Sensitivity ◽  
Optical Parameters ◽  
Rods And Cones ◽  
Open Questions ◽  
Ocular Aberrations ◽  
Membrane Anchoring

The reduction of the brightness when a light beam's entry into the eye is shifted from the centre to the edge of the pupil has from the outset been shown to be due to a change in luminous efficiency of radiation when it is incident obliquely on the retina. The phenomenon is most prominent in photopic vision and this has concentrated attention on the properties of retinal cones, where responsibility has yet to be assigned to factors such as differences in shape, fine structure and configuration, and membrane anchoring of photopigment molecules. Geometrical optics and waveguide formulations have been applied to the question of how light is guided in receptors, but details of their geometry and optical parameters even if they become available will make calculations complex and of only moderate generality. In practice, the diminution of oblique light helps visual performance by reducing deleterious influence of ocular aberrations and of glare caused by light scattering when the pupil is wide. Receptor orientation can come into play in ocular conditions due to mechanical disturbance and has been shown to have potentiality as a tool for clinical diagnosis. Currently, open questions include microanatomical and molecular differences between rods and cones, the coupling of the optical image of the eye with the transducing apparatus in the photoreceptors, possible phototropism and more convincing methods of estimating the actual spatial distribution of photon events as it affects visual resolution.

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