scholarly journals Muscle systems and motility of early animals highlighted by cnidarians from the basal Cambrian

2021 ◽  
Author(s):  
Xing Wang ◽  
Jean Vannier ◽  
Xiaoguang Yang ◽  
Lucas Leclère ◽  
Qiang Ou ◽  
...  
Keyword(s):  
Water Column ◽  
Critical Time ◽  
Early Cambrian ◽  
Basic System ◽  
Muscle System ◽  
Direct Information ◽  
Fossil Evidence ◽  
Wide Range ◽  
Evolutionary Radiation ◽  
Rapid Diversification

Although fossil evidence suggest that various animal groups were able to move actively through their environment in the early stages of their evolution, virtually no direct information is available on the nature of their muscle systems. The origin of jellyfish swimming, for example, is of great concern to biologists. Exceptionally preserved muscles are described here in benthic peridermal olivooid medusozoans from the basal Cambrian of China (Kuanchuanpu Formation, ca. 535 Ma) that have direct equivalent in modern medusozoans. They consist of circular fibers distributed over the bell surface (subumbrella) and most probably have a myoepithelial origin. This is the oldest record of a muscle system in cnidarians and more generally in animals. This basic system was probably co-opted by younger early Cambrian jellyfish to develop capacities for the jet-propelled swimming within the water column. Additional lines of fossil evidence obtained from ecdysozoans (worms and panarthropods) show that the muscle systems of early animals underwent a rapid diversification through the early Cambrian and increased their capacity to colonize a wide range of habitats both within the water column and sediment at a critical time of their evolutionary radiation.

scholarly journals Scaffold Hopping of α-Rubromycin Enables Direct Access to FDA-Approved Cromoglicic Acid as a SARS-CoV-2 MPro Inhibitor

2021 ◽  
Vol 14 (6) ◽  
pp. 541
Author(s):  
Hani A. Alhadrami ◽  
Ahmed M. Sayed ◽  
Heba Al-Khatabi ◽  
Nabil A. Alhakamy ◽  
Mostafa E. Rateb
Keyword(s):  
Binding Free Energy ◽  
Human Fibroblasts ◽  
Critical Time ◽  
Dynamics Simulation ◽  
Direct Access ◽  
Energy Calculation ◽  
Wide Range ◽  
Normal Human ◽  
Novel Scaffold

The COVID-19 pandemic is still active around the globe despite the newly introduced vaccines. Hence, finding effective medications or repurposing available ones could offer great help during this serious situation. During our anti-COVID-19 investigation of microbial natural products (MNPs), we came across α-rubromycin, an antibiotic derived from Streptomyces collinus ATCC19743, which was able to suppress the catalytic activity (IC50 = 5.4 µM and Ki = 3.22 µM) of one of the viral key enzymes (i.e., MPro). However, it showed high cytotoxicity toward normal human fibroblasts (CC50 = 16.7 µM). To reduce the cytotoxicity of this microbial metabolite, we utilized a number of in silico tools (ensemble docking, molecular dynamics simulation, binding free energy calculation) to propose a novel scaffold having the main pharmacophoric features to inhibit MPro with better drug-like properties and reduced/minimal toxicity. Nevertheless, reaching this novel scaffold synthetically is a time-consuming process, particularly at this critical time. Instead, this scaffold was used as a template to explore similar molecules among the FDA-approved medications that share its main pharmacophoric features with the aid of pharmacophore-based virtual screening software. As a result, cromoglicic acid (aka cromolyn) was found to be the best hit, which, upon in vitro MPro testing, was 4.5 times more potent (IC50 = 1.1 µM and Ki = 0.68 µM) than α-rubromycin, with minimal cytotoxicity toward normal human fibroblasts (CC50 > 100 µM). This report highlights the potential of MNPs in providing unprecedented scaffolds with a wide range of therapeutic efficacy. It also revealed the importance of cheminformatics tools in speeding up the drug discovery process, which is extremely important in such a critical situation.

On the lack of widespread bottom simulating reflectors in the Mediterranean Basin

2021 ◽  
Author(s):  
Cristina Corradin ◽  
Angelo Camerlenghi ◽  
Michela Giustiniani ◽  
Umberta Tinivella ◽  
Claudia Bertoni
Keyword(s):  
Water Column ◽  
Pore Water ◽  
Mediterranean Basin ◽  
Stability Field ◽  
Hydrocarbon Gases ◽  
Wide Range ◽  
Bottom Simulating Reflectors ◽  
Messinian Evaporites ◽  
The Mediterranean ◽  
The Mediterranean Basin

<p>In the Mediterranean Basin, gas hydrate bottom simulating reflectors (BSR) are absent, with very few and spatially limited exceptions occurring in Eastern Mediterranean mud volcanoes and in the Nile deep sea fan. This is in spite of widespread occurrence of hydrocarbon gases in the subsurface, mainly biogenic methane, from a wide range of stratigraphic intervals.<br>In this study we model the methane hydrate stability field using all available information on DSDP and ODP boreholes in the Western Mediterranean and in the Levant Basin, including the downhole changes of pore water salinity. The models take into account the consequent pore water density changes and use known estimates of geothermal gradient. None of the drilled sites were located on seismic profiles in which a BSR is present.<br>The modelled base of the stability field of methane hydrates is located variably within, below, or even above the drilled sedimentary section (the latter case implies that it is located in the water column). We discuss the results in terms of geodynamic environments, areal distribution of Messinian evaporites, upward ion diffusion from Messinian evaporites, organic carbon content, and the peculiar thermal structure of the Mediterranean water column. <br>We conclude that the cumulative effects of geological and geochemical environments make the Mediterranean Basin a region that is unfavorable to the existence of BSRs in the seismic record, and most likely to the existence of natural gas hydrates below the seabed.<br><br></p>

Beyond the Glittering Eye

2020 ◽  
pp. 117-183
Author(s):  
Shibani Bose
Keyword(s):  
Ancient India ◽  
Human Interactions ◽  
The Past ◽  
Fossil Evidence ◽  
Wide Range

Notwithstanding the cultural fascination evoked by the tiger, wildlife histories have done little to salvage it from the shadows of the past, particularly in the context of ancient India. This chapter endeavours to fill in this gap by marshalling evidence testifying to human interactions with this mega carnivore in early India. It underlines the dearth of fossil evidence, notes the patchy evidence offered by the archaeozoological record, and details the images which can be garnered from visual depictions of the animal on seals, copper tablets, and terracottas. It also explores at length the ways in which it is perceived in a wide range of Sanskrit, Pali, Prakrit, and classical Western accounts. Typically an animal of the forest and jungle, charting the journey of the tiger provides valuable glimpses into India’s ancient ecological past.

Expected Values of Wave Power Absorption Around the Japanese Islands Using OWC Types With Projecting Walls

2011 ◽  
Author(s):  
Tomoki Ikoma ◽  
Hiroyuki Osawa ◽  
Koichi Masuda ◽  
Hiisaaki Maeda
Keyword(s):  
Resonance Frequency ◽  
Performance Improvement ◽  
Standing Waves ◽  
Wave Power ◽  
Basic System ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Wide Range ◽  
Expected Values ◽  
Japanese Islands

This paper describes performance improvement of wave power absorption by using a new concept. Basic system proposed is an oscillating water column (OWC) type. An artificial harbor surrounded by projecting walls is installed. The type is called as PW-OWC in this paper. Standing waves occur in the artificial harbor, the absorbing device consequently has a resonance frequency differing from that of OWC. From the effect, the system is able to absorb wave power in very wide range of the wave frequency. From the experimental results, PW-OWC types are very good performance of wave power absorption comparing with conventional OWC types. In addition, the performance of the PW-OWC type is insensibility to the nozzle ratio of an orifice. The performance can be easily improved by installing the harbor part even if the performance of a base OWC device is not good. Finally, we investigate the expected values of acquirable wave power in not only a year but also every season. The expected values of PW-OWC types are greater than that of conventional OWC ones in seas around the Japanese islands.

scholarly journals Large-Eddy Simulation of a Coastal Ocean under the Combined Effects of Surface Heat Fluxes and Full-Depth Langmuir Circulation

2016 ◽  
Vol 46 (8) ◽  
pp. 2411-2436 ◽  
Author(s):  
Rachel Walker ◽  
Andrés E. Tejada-Martínez ◽  
Chester E. Grosch
Keyword(s):  
Water Column ◽  
Stable Stratification ◽  
Coastal Ocean ◽  
Surface Heat ◽  
Heat Fluxes ◽  
Surface Heating ◽  
Surface Cooling ◽  
Surface Heat Fluxes ◽  
Wide Range ◽  
Large Eddy

AbstractResults are presented from the large-eddy simulations (LES) of a wind-driven flow representative of the shallow coastal ocean under the influences of Langmuir forcing and surface heating and cooling fluxes. Langmuir (wind and surface gravity wave) forcing leads to the generation of Langmuir turbulence consisting of a wide range of Langmuir circulations (LCs) or parallel, counterrotating vortices that are aligned roughly in the direction of the wind. In unstratified, shallow coastal regions, the largest of the LCs reach the bottom of the water column. Full-depth LCs are investigated under surface waves with a significant wave height of 1.2 m and a dominant wavelength of 90 m and wave period of 8 s, for a wind speed of 7.8 m s−1 in a 15-m-deep coastal shelf region. Both unstable and stable stratification are imposed by constant surface heat fluxes and an adiabatic bottom wall. Simulations are characterized by Rayleigh and Richardson numbers representative of surface buoyancy forcing relative to wind forcing. For the particular combination of Langmuir forcing parameters studied, although surface cooling is able to augment the strength of LC, a significantly high cooling flux of 560 W m−2 (such that the Rayleigh number is Raτ = 1000) is required in order for turbulence kinetic energy generation by convection to exceed Langmuir production. Such a transition is expected at a lower heat flux for weaker wind and wave conditions and thus weaker LCs than those studied. Furthermore, a surface heating flux of approximately 281 W m−2 (such that the Richardson number is Riτ = 500) is able to inhibit vertical mixing of LC, particularly in the bottom half of the water column, allowing stable stratification to develop.

A New Method for Deriving Soliton Design Criteria

2019 ◽  
Author(s):  
Gus Jeans ◽  
Oliver Jones ◽  
Michael Zhang ◽  
Christopher R. Jackson ◽  
Nataliya Stashchuk ◽  
...  
Keyword(s):  
Water Column ◽  
Seawater Temperature ◽  
New Method ◽  
Primary Data ◽  
Density Structure ◽  
Fourier Techniques ◽  
Wide Range ◽  
New Development ◽  
Sophisticated Model ◽  
Soliton Amplitude

Abstract A new method for deriving extreme soliton current criteria for offshore engineering applications is described. The primary data source was site specific measurement close to the continental shelf break where metocean criteria were required. A dedicated oceanographic mooring was designed to quantify solitons, with rapidly sampled measurement of seawater temperature and velocities through the vertical. As described in two previous OMAE papers, quantification of soliton velocity profiles was achieved via temperature measurement and theory, with measured velocities playing a secondary role in critical validation. The previous methodology was extended in the present study, with separate contributions quantified from variations in soliton amplitude and water column density structure. The nonlinear Fourier techniques first described in OMAE 2017 were again used to reduce uncertainty in estimates of extreme soliton amplitude. In a new development, the long-term distribution of the density structure contribution was quantified using a calibrated hindcast of seawater temperature. Extreme conditions were defined at the boundary of a MITgcm model domain. This sophisticated model was then used to estimate extreme soliton velocities, through the water column and a few metres above the seabed, at a wide range of shallower target locations.

Asynchronous trilobite extinctions at the early to middle Cambrian transition

Geology ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 441-445 ◽  
Author(s):  
F.A. Sundberg ◽  
K.E. Karlstrom ◽  
G. Geyer ◽  
J.R. Foster ◽  
J.W. Hagadorn ◽  
...  
Keyword(s):  
Critical Time ◽  
Data Sets ◽  
Early Cambrian ◽  
Earth System ◽  
Middle Cambrian ◽  
West Gondwana ◽  
Paleoclimatic Data ◽  
First Time ◽  
Age Constraints ◽  
Prior Models

Abstract Trilobites appeared and diversified rapidly in the Cambrian, but it is debated as to whether their radiations and extinctions were globally synchronous or geographically restricted and diachronous. The end of the early Cambrian is a classic example—it has traditionally been defined by the extinction of olenellid and redlichiid trilobites and the appearance of paradoxidid trilobites. Here we integrate the global biostratigraphy of these three trilobite groups with high-precision tuff and tandem detrital zircon U-Pb age constraints to falsify prior models for global synchronicity of these events. For the first time, we demonstrate that olenellid trilobites in Laurentia went extinct at least 3 Ma after the first appearance of paradoxidids in Avalonia and West Gondwana (ca. 509 Ma). They also disappeared before the extinction of redlichiids and prior to the base of the Miaolingian at ca. 506 Ma in South China. This indicates that these three trilobite groups (paradoxidids, olenellids, and redlichiids) and their associated biotas overlapped in time for nearly 40% of Cambrian Epoch 2, Age 4. Implications of this chronological overlap are: (1) trilobite transitions were progressive and geographically mediated rather than globally synchronous; and (2) paleontological databases underestimate the diversity of the early Cambrian. This ∼3 Ma diachroneity, at a critical time in the early evolution of animals, also impacts chemostratigraphic and paleoclimatic data sets that are tied to trilobite biostratigraphy and that collectively underpin our understanding of the Cambrian Earth system.

scholarly journals Concept Tests for a New Wire Flying Vehicle Designed to Achieve High Horizontal Resolution Profiling in Deep Water

2011 ◽  
Vol 28 (12) ◽  
pp. 1657-1671 ◽  
Author(s):  
Chris Roman ◽  
Dave Hebert
Keyword(s):  
Water Column ◽  
Deep Water ◽  
Free Stream ◽  
Horizontal Resolution ◽  
Vehicle Body ◽  
Scale Model ◽  
Stream Velocity ◽  
Wide Range ◽  
High Horizontal Resolution ◽  
Ship Speed

Abstract Efficiently profiling the water column to achieve both high vertical and horizontal resolution from a moving vessel in deep water is difficult. Current solutions, such as CTD tow-yos, moving vessel profilers, and undulating tow bodies, are limited by ship speed or water depth. As a consequence, it is difficult to obtain oceanographic sections with sufficient resolution to identify many relevant scales over the deeper sections of the water column. This paper presents a new concept for a profiling vehicle that slides up and down a towed wire in a controlled manner using the lift created by wing foils. The wings provide a novel low-power method of propulsion along the cable by using the free stream velocity of the wire moving through the water in similar fashion to a sailboat sailing up wind. Scale model tests show a wide range of achievable profiling glide slopes for tow cable angles between vertical and 45°, and effective isolation of cable strum vibration from the towed vehicle body. The concept is not depth limited and will offer two-dimensional resolution that meets or exceeds current undulating tow bodies over the full water column. Additionally, this system could be used simultaneously with many other deep towed instrument packages to produce complementary datasets.

The early Mesozoic radiation of dinoflagellates

Paleobiology ◽  
1996 ◽  
Vol 22 (3) ◽  
pp. 329-338 ◽  
Author(s):  
R. A. Fensome ◽  
R. A. MacRae ◽  
J. M. Moldowan ◽  
F. J. R. Taylor ◽  
G. L. Williams
Keyword(s):  
Detailed Analysis ◽  
Fossil Record ◽  
The Past ◽  
Early Mesozoic ◽  
Fossil Evidence ◽  
Evolutionary Radiation ◽  
Molecular Phylogenetic ◽  
Sudden Appearance ◽  
New Evidence

Dinoflagellates are a major component of the marine microplankton and, from fossil evidence, appear to have been so for the past 200 million years. In contrast, the pre-Triassic record contains only equivocal occurrences of dinoflagellates, despite the fact that comparative ultrastructural and molecular phylogenetic evidence indicates a Precambrian origin for the lineage. Thus, it has often been assumed that the dearth of Paleozoic fossil dinoflagellates was due to a lack of preservation or recognition and that the relatively sudden appearance of dinoflagellates in the Mesozoic is an artifact of the record. However, new evidence from a detailed analysis of the fossil record and from the biogeochemical record indicates that dinoflagellates did indeed undergo a major evolutionary radiation in the early Mesozoic.

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