Dickinsonia: mobile and adhered

2021 ◽  
pp. 1-16
Author(s):  
Andrey Ivantsov ◽  
Maria Zakrevskaya
Keyword(s):  
Motor Activity ◽  
Shallow Water ◽  
Microbial Mats ◽  
The Body ◽  
Microbial Mat ◽  
Mineral Particles ◽  
Joint Plane ◽  
Plane Passing ◽  
Lift Off ◽  
Marine Community

AbstractThe classical genus of Ediacaran macroorganisms,Dickinsonia, was part of an extensive benthic marine community inhabiting the fields of microbial mats. The remains ofDickinsoniaare commonly preserved in the position of adhesion to the habitat substrate. However, these were mobile organisms. In addition to the already known feeding traces ofDickinsonia, structures described as traces of motor activity are reported. Long parallel furrows, extending from the posterior end of the body imprint, are interpreted as imprints of ridges left by an organism moving along the surface of the substrate. Groups of differently shaped grooves laying in the depression that enhalo theDickinsoniabody imprints or accompany their individual areas are interpreted as imprints of ridges and cords of mucous material. They are considered to represent structures of self-determined stretching and lift-off of the body margins from the substrate. The rings and arcs of silt- and sand-sized mineral particles bordering the body imprints are composed of material that was supposedly brushed off from the surface of the microbial mat byDickinsonia. They are considered traces of the adhesion of these organisms to the substrate. Accumulations of multidirectional pulling and tear-off structures, lacking the body imprint but accompanied by the joint plane passing into the overlying sediment and cutting through the bedding, are interpreted as escape traces. The dual modality of the behaviour (attachment and mobility) could indicate the adaptability ofDickinsoniato life in extremely shallow-water environments.

Effect of vagotomy on the acid response to gastric distension

1970 ◽  
Vol 48 (10) ◽  
pp. 670-674 ◽  
Author(s):  
R. M. Preshaw
Keyword(s):  
Motor Activity ◽  
Gastric Acid ◽  
Motor Response ◽  
Acid Output ◽  
The Body ◽  
Conscious Dogs ◽  
Truncal Vagotomy ◽  
Gastric Distension ◽  
Gastric Acid Output

Distension of the body of the stomach, in conscious dogs with vagally innervated antral pouches, caused an increase in gastric acid output, and an increase in antral motor activity. Truncal vagotomy inhibited the acid response to distension, but had no effect on the antral motor response. Denervation of the antral pouch by separating it from the main stomach caused little further diminution in the response.

scholarly journals DYNAMICS OF CHANGES IN THE PSYCHOPHYSIOLOGICAL STATE OF TECHNICAL UNIVERSITY STUDENTS

2021 ◽  
Vol 5 ◽  
pp. 91-95
Author(s):  
Elena V. Klimova ◽  
Olga V. Mukhametova ◽  
Nail Sh. Mukhametov
Keyword(s):  
Physical Education ◽  
Motor Activity ◽  
Goal Orientation ◽  
The Body ◽  
State University ◽  
First Year Students ◽  
Motor Abilities ◽  
Functional Capabilities ◽  
Functional Development ◽  
Psychophysiological State

This paper examines the dynamics of changes in the indicators of the psychophysiological state of students of the Siberian State University of Railway Transport. The indicators of motor activity, vital index (ZHI) and respiratory system were considered. The purpose of the study is to identify the physical and functional capabilities of the body of first-year students, as well as to analyze the level of health. The objectives of the study are to determine the level of psychophysiological state of students in dynamics. Research hypothesis: the source of physical education should be on motor activity that is appropriate for development, in order to promote self-efficacy and pleasure, as well as encourage continuous participation in physical activity; through the acquisition of motivational experience by students in physical education and sports, physical and functional development is achieved, as well as self-esteem, goal orientation and tasks; the effectiveness of physical development can be achieved by changing the approaches to the implementation of FC programs, sports facilities, recruitment, as well as the organization of school-university continuity. Research methods: analysis, systematization, generalization. The results of the research showed a decrease in physical fitness and activity in general, as well as the need to develop motor abilities and improve the level of physical health of students.

Two new species of Styela (Tunicata: Ascidiacea) from the tropical West Atlantic Ocean

Zootaxa ◽  
2021 ◽  
Vol 4948 (2) ◽  
pp. 275-286
Author(s):  
RODOLFO CORRÊA DE BARROS ◽  
ROSANA MOREIRA DA ROCHA
Keyword(s):  
New Species ◽  
Atlantic Ocean ◽  
Shallow Water ◽  
Atlantic Coast ◽  
The Body ◽  
The South ◽  
Bocas Del Toro ◽  
Espírito Santo ◽  
Two New Species ◽  
Espirito Santo

Two new species of the genus Styela are described, with very rare characteristics in this genus: both are shallow-water and tropical, with more than two gonads in each side of the body. Styela panamensis sp. nov. is described from specimens collected in Bocas del Toro, Atlantic coast of Panama, and Styela multicarpa sp. nov. from specimens collected in Espírito Santo, Brazil and Margarita Island, Venezuela. They are probably native to the south Caribbean and S. multicarpa sp. nov. is introduced in Brazil. 

Nonlinear Aspects of Subcritical Shallow-Water Flow Past Two-Dimensional Obstructions

1978 ◽  
Vol 22 (04) ◽  
pp. 203-211
Author(s):  
Nils Salvesen ◽  
C. von Kerczek
Keyword(s):  
Free Surface ◽  
Shallow Water ◽  
Flow Problem ◽  
Free Stream ◽  
The Body ◽  
Two Dimensional ◽  
Third Order ◽  
Submerged Body ◽  
The Mean ◽  
The Waves

Some nonlinear aspects of the two-dimensional problem of a submerged body moving with constant speed in otherwise undisturbed water of uniform depth are considered. It is shown that a theory of Benjamin which predicts a uniform rise of the free surface ahead of the body and the lowering of the mean level of the waves behind it agrees well with experimental data. The local steady-flow problem is solved by a numerical method which satisfies the exact free-surface conditions. Third-order perturbation formulas for the downstream free waves are also presented. It is found that in sufficiently shallow water, the wavelength increases with increasing disturbance strength for fixed values of the free-stream-Froude number. This is opposite to the deepwater case where the wavelength decreases with increasing disturbance strength.

scholarly journals Sterol preservation in hypersaline microbial mats

2020 ◽  
Vol 17 (3) ◽  
pp. 649-666
Author(s):  
Yan Shen ◽  
Volker Thiel ◽  
Pablo Suarez-Gonzalez ◽  
Sebastiaan W. Rampen ◽  
Joachim Reitner
Keyword(s):  
Microbial Mats ◽  
Abiotic Factors ◽  
Total Sterol ◽  
Microbial Transformation ◽  
Microbial Mat ◽  
Hypersaline Lake ◽  
Central Pacific ◽  
Significant Drop ◽  
Subaerial Exposure ◽  
Benthic Ecosystems

Abstract. Microbial mats are self-sustaining benthic ecosystems composed of highly diverse microbial communities. It has been proposed that microbial mats were widespread in Proterozoic marine environments, prior to the emergence of bioturbating organisms at the Precambrian–Cambrian transition. One characteristic feature of Precambrian biomarker records is that steranes are typically absent or occur in very low concentrations. This has been explained by low eukaryotic source inputs, or degradation of primary produced sterols in benthic microbial mats (“mat-seal effect”). To better understand the preservational pathways of sterols in microbial mats, we analyzed freely extractable and carbonate-bound lipid fractions as well as decalcified extraction residues in different layers of a recent calcifying mat (∼1500 years) from the hypersaline Lake 2 on the island of Kiritimati, central Pacific. A variety of C27–C29 sterols and distinctive C31 4α-methylsterols (4α-methylgorgosterol and 4α-methylgorgostanol, biomarkers for dinoflagellates) were detected in freely extractable and carbonate-bound lipid pools. These sterols most likely originated from organisms living in the water column and the upper mat layers. This autochthonous biomass experienced progressive microbial transformation and degradation in the microbial mat, as reflected by a significant drop in total sterol concentrations, up to 98 %, in the deeper layers, and a concomitant decrease in total organic carbon. Carbonate-bound sterols were generally low in abundance compared to the freely extractable portion, suggesting that incorporation into the mineral matrix does not play a major role in the preservation of eukaryotic sterols in this mat. Likewise, pyrolysis of extraction residues suggested that sequestration of steroid carbon skeletons into insoluble organic matter was low compared to hopanoids. Taken together, our findings argue for a major mat-seal effect affecting the distribution and preservation of steroids in the mat studied. This result markedly differs from recent findings made for another microbial mat growing in the nearby hypersaline Lake 22 on the same island, where sterols showed no systematic decrease with depth. The observed discrepancies in the taphonomic pathways of sterols in microbial mats from Kiritimati may be linked to multiple biotic and abiotic factors including salinity and periods of subaerial exposure, implying that caution has to be exercised in the interpretation of sterol distributions in modern and ancient microbial mat settings.

Canine gallbladder cyclic motor activity

1988 ◽  
Vol 255 (4) ◽  
pp. G409-G416 ◽  
Author(s):  
T. Matsumoto ◽  
S. K. Sarna ◽  
R. E. Condon ◽  
W. J. Dodds ◽  
N. Mochinaga
Keyword(s):  
Motor Activity ◽  
Short Duration ◽  
Sphincter Of Oddi ◽  
The Body ◽  
Phase Iii ◽  
Fasted State ◽  
Long Duration ◽  
The Mean ◽  
Esophageal Sphincter

We investigated whether the gallbladder has cyclic motor activity similar to that of the stomach, lower esophageal sphincter, and sphincter of Oddi in the fasted state. We found that the canine gallbladder infundibulum exhibited a cyclic burst of short duration (69 +/- 3 s) contractions that were closely associated with phase III activity of the antrum. The cyclic motor activity was sometimes less prominent or absent in the body and the fundus of the gallbladder. The mean period of gallbladder cyclic motor activity was not significantly different from the mean period of phase III activity in the stomach and the duodenum. The cyclic bursts of gallbladder contractions lasted for 21 +/- 2 min. The gallbladder cyclic motor activity started at about the same time as the antral phase III activity, and both of these activities started approximately 12 min earlier than the duodenal phase III activity. In addition to the aforementioned cyclic bursts of contractions, the gallbladder sometimes exhibited long duration (6.4 +/- 0.6 min) contractions that occurred irregularly and unpredictably during the duodenal migrating motor complex cycle. We conclude that during fasting the canine gallbladder has a cyclic motor activity that is temporally related to phase III activity of the stomach and the duodenum. The role of short duration phasic contractions during cyclic motor activity may be to periodically stir gallbladder contents, whereas the long duration contractions may partially empty the gallbladder in the fasted state.

scholarly journals Responses of a Thermophilic Synechococcus Isolate from the Microbial Mat of Octopus Spring to Light

2007 ◽  
Vol 73 (13) ◽  
pp. 4268-4278 ◽  
Author(s):  
Oliver Kilian ◽  
Anne-Soisig Steunou ◽  
Fariba Fazeli ◽  
Shaun Bailey ◽  
Devaki Bhaya ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Microbial Mats ◽  
Carbon Fixation ◽  
Fluorescence Emission ◽  
Transcript Abundance ◽  
High Light ◽  
Microbial Mat ◽  
Fluorescence Emission Spectra ◽  
Thermophilic Cyanobacteria ◽  
Genes Encoding

ABSTRACT Thermophilic cyanobacteria of the genus Synechococcus are major contributors to photosynthetic carbon fixation in the photic zone of microbial mats in Octopus Spring, Yellowstone National Park. Synechococcus OS-B′ was characterized with regard to the ability to acclimate to a range of different light irradiances; it grows well at 25 to 200 μmol photons m−2 s−1 but dies when the irradiance is increased to 400 μmol photons m−2 s−1. At 200 μmol photons m−2 s−1 (high light [HL]), we noted several responses that had previously been associated with HL acclimation of cyanobacteria, including cell bleaching, reduced levels of phycobilisomes and chlorophyll, and elevated levels of a specific carotenoid. Synechococcus OS-B′ synthesizes the carotenoids zeaxanthin and β,β-carotene and a novel myxol-anhydrohexoside. Interestingly, 77-K fluorescence emission spectra suggest that Synechococcus OS-B′ accumulates very small amounts of photosystem II relative to that of photosystem I. This ratio further decreased at higher growth irradiances, which may reflect potential photodamage following exposure to HL. We also noted that HL caused reduced levels of transcripts encoding phycobilisome components, particularly that for CpcH, a 20.5-kDa rod linker polypeptide. There was enhanced transcript abundance of genes encoding terminal oxidases, superoxide dismutase, tocopherol cyclase, and phytoene desaturase. Genes encoding the photosystem II D1:1 and D1:2 isoforms (psbAI and psbAII/psbAIII, respectively) were also regulated according to the light regimen. The results are discussed in the context of how Synechococcus OS-B′ may cope with high light irradiances in the high-temperature environment of the microbial mat.

Abnormal Esophageal Manometry in Globus Hystericus

1981 ◽  
Vol 90 (4) ◽  
pp. 383-386 ◽  
Author(s):  
Toribio C. Flores ◽  
Frederick S. Cross ◽  
Richard D. Jones
Keyword(s):  
Motor Activity ◽  
Physical Examination ◽  
Esophageal Motility ◽  
Esophageal Manometry ◽  
The Body ◽  
Globus Sensation ◽  
Different Levels ◽  
Stimulation Of

Globus hystericus means the “hysterical ball or lump in the throat,” and is generally assumed to be of psychic origin. True dysphagia is usually absent. Twelve patients with the globus syndrome were studied at the Esophageal Motility Laboratory of the Saint Luke's Hospital of Cleveland. An organic cause for their symptomatology was ruled out by physical examination, laryngoscopy, esophagoscopy and cineesophagograms. Ten patients showed significant elevations in esophageal resting pressures and nine had evidence of disordered motor activity in the body of the esophagus. Knowing from previous investigations that a suprasternal discomfort may be elicited from stimulation of the esophagus at different levels, we propose that the globus sensation is a referred one coming from the hypertonic and frequently incoordinated body of the esophagus.

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