Comparison of oxygen consumption byTerebratalia transversa(Brachiopoda) and two species of pteriomorph bivalve molluscs: implications for surviving mass extinctions

Paleobiology ◽  
2012 ◽  
Vol 38 (4) ◽  
pp. 525-537 ◽  
Author(s):  
Loren A. Ballanti ◽  
Alexa Tullis ◽  
Peter D. Ward
Keyword(s):  
Oxygen Consumption ◽  
Mass Extinction ◽  
Mass Extinctions ◽  
Bivalve Molluscs ◽  
Tissue Mass ◽  
Metabolic Characteristics ◽  
Significant Difference ◽  
Insight Into ◽  
Selective Extinction ◽  
Lower Tolerance

The Permian/Triassic mass extinction marks a permanent phylogenetic shift in the composition of the sessile benthos, from one largely dominated by articulate brachiopods to one dominated by mollusks. Widespread evidence of oceanic hypoxia and anoxia at this time provides a possible selective kill mechanism that could help explain the large taxonomic losses in brachiopods compared to the morphologically and ecologically similar bivalve molluscs. Our study compared the oxygen consumption of an articulate brachiopod,Terebratalia transversa, with that of two pteriomorph bivalves,Glycymeris septentrionalisandMytilus trossulus, under normoxia and hypoxia, as well as their tolerance to anoxia, to gain insight into the relative metabolic characteristics of each group. We found no significant difference in the oxygen consumption of the three species when normalized to the same dry-tissue mass. However, when calculated for animals of the same external linear dimensions, bivalve oxygen consumption was two to three times greater than that of brachiopods. Our results also showed no significant decrease in the oxygen consumption of the three species until measured at a partial pressure of oxygen ∼10% of normoxic values. Finally,T. transversaandM. trossulusshowed no significant difference in their tolerance to complete anoxia, but both showed a much lower tolerance than another bivalve,Acila castrensis. Findings from this study suggest that oxygen limitation is unlikely to account for the observed selective extinction of brachiopods during the Permian/Triassic mass extinction. Results may provide valuable information for assessing hypotheses put forth to explain why articulate brachiopods continue to remain a relatively minor group in marine environments.

Within- and among-genus components of size evolution during mass extinction, recovery, and background intervals: a case study of Late Permian through Late Triassic foraminifera

Paleobiology ◽  
2012 ◽  
Vol 38 (4) ◽  
pp. 627-643 ◽  
Author(s):  
Brianna L. Rego ◽  
Steve C. Wang ◽  
Demir Altiner ◽  
Jonathan L. Payne
Keyword(s):  
Mass Extinction ◽  
Extinction Risk ◽  
Maximum Size ◽  
Size Reduction ◽  
Late Triassic ◽  
Mass Extinctions ◽  
Late Permian ◽  
Biotic Recovery ◽  
Size Evolution ◽  
Selective Extinction

One of the best-recognized patterns in the evolution of organismal size is the tendency for mean and maximum size within a clade to decrease following a major extinction event and to increase during the subsequent recovery interval. Because larger organisms are typically thought to be at higher extinction risk than their smaller relatives, it has commonly been assumed that size reduction mostly reflects the selective extinction of larger species. However, to our knowledge the relative importance of within- and among-lineage processes in driving overall trends in body size has never been compared quantitatively. In this study, we use a global, specimen-level database of foraminifera to study size evolution from the Late Permian through Late Triassic. We explicitly decompose size evolution into within- and among-genus components. We find that size reduction following the end-Permian mass extinction was driven more by size reduction within surviving species and genera than by the selective extinction of larger taxa. Similarly, we find that increase in mean size across taxa during Early Triassic biotic recovery was a product primarily of size increase within survivors and the extinction of unusually small taxa, rather than the origination of new, larger taxa. During background intervals we find no strong or consistent tendency for extinction, origination, or within-lineage change to move the overall size distribution toward larger or smaller sizes. Thus, size stasis during background intervals appears to result from small and inconsistent effects of within- and among-lineage processes rather than from large but offsetting effects of within- and among-taxon components. These observations are compatible with existing data for other taxa and extinction events, implying that mass extinctions do not influence size evolution by simply selecting against larger organisms. Instead, they appear to create conditions favorable to smaller organisms.

Toward an understanding of cosmopolitanism in deep time: a case study of ammonoids from the middle Permian to the Middle Triassic

Paleobiology ◽  
2020 ◽  
Vol 46 (4) ◽  
pp. 533-549
Author(s):  
Xu Dai ◽  
Haijun Song
Keyword(s):  
Mass Extinction ◽  
Middle Triassic ◽  
Theoretical Models ◽  
Geographic Range ◽  
Middle Permian ◽  
Time Interval ◽  
Mass Extinctions ◽  
Deep Time ◽  
Underlying Mechanisms ◽  
Selective Extinction

AbstractCosmopolitanism occurred recurrently during the geologic past, especially after mass extinctions, but the underlying mechanisms remain poorly known. Three theoretical models, not mutually exclusive, can lead to cosmopolitanism: (1) selective extinction in endemic taxa, (2) endemic taxa becoming cosmopolitan after the extinction and (3) an increase in the number of newly originated cosmopolitan taxa after extinction. We analyzed an updated occurrence dataset including 831 middle Permian to Middle Triassic ammonoid genera and used two network methods to distinguish major episodes of ammonoid cosmopolitanism during this time interval. Then, we tested the three proposed models in these case studies. Our results confirm that at least two remarkable cosmopolitanism events occurred after the Permian–Triassic and late Smithian (Early Triassic) extinctions, respectively. Partitioned analyses of survivors and newcomers revealed that the immediate cosmopolitanism event (Griesbachian) after the Permian–Triassic event can be attributed to endemic genera becoming cosmopolitan (model 2) and an increase in the number of newly originated cosmopolitan genera after the extinction (model 3). Late Smithian cosmopolitanism is caused by selective extinction in endemic taxa (model 1) and an increase in the number of newly originated cosmopolitan genera (model 3). We found that the survivors of the Permian–Triassic mass extinction did not show a wider geographic range, suggesting that this mass extinction is nonselective among the biogeographic ranges, while late Smithian survivors exhibit a wide geographic range, indicating selective survivorship among cosmopolitan genera. These successive cosmopolitanism events during severe extinctions are associated with marked environmental upheavals such as rapid climate changes and oceanic anoxic events, suggesting that environmental fluctuations play a significant role in cosmopolitanism.

scholarly journals Soft tissue masses: distribution of entities and rate of malignancy in small lesions

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Felix G. Gassert ◽  
Florian T. Gassert ◽  
Katja Specht ◽  
Carolin Knebel ◽  
Ulrich Lenze ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Benign Lesion ◽  
Maximum Diameter ◽  
Histopathological Diagnosis ◽  
Tumor Diameter ◽  
Mr Images ◽  
Tissue Mass ◽  
Malignancy Rate ◽  
Significant Difference ◽  
Soft Tissue Masses

Abstract Background Small soft tissue masses are often falsely assumed to be benign and resected with failure to achieve tumor-free margins. Therefore, this study retrospectively investigated the distribution of histopathologic diagnosis to be encountered in small soft tissue tumors (≤ 5 cm) in a large series of a tertiary referral center. Methods Patients with a soft tissue mass (STM) with a maximum diameter of 5 cm presenting at our institution over a period of 10 years, who had undergone preoperative Magnetic resonance imaging and consequent biopsy or/and surgical resection, were included in this study. A final histopathological diagnosis was available in all cases. The maximum tumor diameter was determined on MR images by one radiologist. Moreover, tumor localization (head/neck, trunk, upper extremity, lower extremity, hand, foot) and depth (superficial / deep to fascia) were assessed. Results In total, histopathologic results and MR images of 1753 patients were reviewed. Eight hundred seventy patients (49.63%) showed a STM ≤ 5 cm and were therefore included in this study (46.79 +/− 18.08 years, 464 women). Mean maximum diameter of the assessed STMs was 2.88 cm. Of 870 analyzed lesions ≤ 5 cm, 170 (19.54%) were classified as superficial and 700 (80.46%) as deep. The malignancy rate of all lesions ≤ 5 cm was at 22.41% (superficial: 23.53% / deep: 22.14%). The malignancy rate dropped to 16.49% (20.79% / 15.32%) when assessing lesions ≤ 3 cm (p = 0.007) and to 15.0% (18.18% / 13.79%) when assessing lesions ≤ 2 cm (p = 0.006). Overall, lipoma was the most common benign lesion of superficial STMs (29.41%) and tenosynovial giant cell tumor was the most common benign lesion of deep STMs (23.29%). Undifferentiated pleomorphic sarcoma was the most common malignant diagnosis among both, superficial (5.29%) and deep (3.57%) STMs. Conclusions The rate of malignancy decreased significantly with tumor size in both, superficial and deep STMs. The distribution of entities was different between superficial and deep STMs, yet there was no significant difference found in the malignancy rate.

scholarly journals Walking Cadence during Moderate-Intensity Physical Activity in Pregnant Women

2021 ◽  
Vol 18 (12) ◽  
pp. 6593
Author(s):  
Mallory Marshall ◽  
Beth Birchfield ◽  
Rebecca Rogers ◽  
Joyeuse Senga ◽  
McKenna Persch ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Pregnant Women ◽  
Pearson Correlation ◽  
Current Data ◽  
Moderate Intensity ◽  
Metabolic Alterations ◽  
Moderate Intensity Physical Activity ◽  
Metabolic Equivalents ◽  
Significant Difference ◽  
Three Stages

Evidence has established that a cadence of 100 steps/min is indicative of the moderate intensity threshold of 3 metabolic equivalents (METs), but this has only been described in non-pregnant individuals. As metabolic alterations are well established during pregnancy, the purpose of this study was to determine if the walking cadence equivalent to 3 METs in pregnant women is similar to non-pregnant populations. Pregnant females (n = 29; age = 30.3 ± 3.2 years, gestational age = 23.9 ± 6.6 weeks) in their second or third trimester (>12 weeks gestation) completed three stages of treadmill walking for 5 min at different standardized walking speeds: 2.5, 3.0, and 3.5 miles per hour (mph). Oxygen consumption (VO2) and heart rate (HR) were measured each minute and METs were calculated for each stage. Real-time continuous monitoring of walking cadence was evaluated by an OptoGait gait analysis system. Following the three standardized speed stages, participants completed an additional stage walking at a speed that elicited 100 steps/min; VO2 and HR were also collected. A one-sample t-test was used to compare MET values at each stage to the heuristic 3 MET cutoff, and Pearson correlation coefficient was calculated to evaluate the relationship between cadence and METs. Mean cadence increased linearly across the three stages (2.5 mph = 103.7 ± 4.5, 3.0 mph = 112.5 ± 5.3, and 3.5 mph = 120.4 ± 6.2 steps/min), as did METs (2.5 mph = 2.7 ± 1.7, 3.0 mph = 3.2 ± 0.8, and 3.5 mph = 4.3 ± 1.8 METs) regardless of trimester. The average treadmill speed at which women walked at 100 steps/min was 2.4 ± 0.4 mph which elicited an oxygen consumption of 9.5 mL•kg−1•min−1, or 2.7 ± 0.7 METs. There was no significant difference between METs at 3.0 mph and the conventional 3 MET cut point for moderate-intensity PA (p < 0.05). There was a moderate and significant relationship between METs and cadence (2nd trimester: r = 0.51; 3rd trimester: r = 0.42). Current data indicate for the first time that the traditionally used 3 MET cutoff for moderate-intensity activity is appropriate for pregnant women despite metabolic alterations associated with pregnancy. This may have important implications for exercise prescription in pregnant populations.

Selective extinction of late Neogene bivalves on the temperate Pacific coast of South America

Paleobiology ◽  
2007 ◽  
Vol 33 (3) ◽  
pp. 455-468 ◽  
Author(s):  
Marcelo M. Rivadeneira ◽  
Pablo A. Marquet
Keyword(s):  
Body Size ◽  
South America ◽  
Mass Extinction ◽  
Pacific Coast ◽  
Geographic Range ◽  
Life Habit ◽  
Late Neogene ◽  
Probability Of Extinction ◽  
Phylogenetic Effects ◽  
Selective Extinction

AbstractWe assessed selective extinction patterns in bivalves during a late Neogene mass extinction event observed along the temperate Pacific coast of South America. The analysis of 99 late Neogene and Quaternary fossil sites (recorded from 7°S to 55°S), yielding ∼2800 occurrences and 118 species, revealed an abrupt decline in Lyellian percentages during the late Neogene–Pleistocene, suggesting the existence of a mass extinction that decimated ∼66% of the original assemblage. Using the late Neogene data set (n = 59 species, 1346 occurrences), we tested whether the extinction was nonrandom according to taxonomic structure, life habit, geographic range, and body size. Our results showed that the number of higher taxa that went extinct was not different than expected by random. At first sight, extinction was selective only according to life habit and geographic range. Nevertheless, when phylogenetic effects were accounted for, body size also showed significant selectivity. In general, epifaunal, small-sized (after phylogenetic correction), and short-ranged species tended to have increased probability of extinction. This is verified by strong interactions between the variables herein analyzed, suggesting the existence of nonlinear effects on extinction chances. In the heavily decimated epifaunal forms, survival was not enhanced by widespread ranges or larger body sizes. Conversely, the widespread and large-sized infaunal forms tended to have lower probability of extinction. Overall, the ultimate extinction of late Neogene bivalve species along the Pacific coast of South America seems to have been determined by a complex interplay of ecological and historical (phylogenetic) effects.

Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes

2021 ◽  
Author(s):  
Arbia Jouini
Keyword(s):  
Mass Extinction ◽  
Environmental Changes ◽  
Sea Water ◽  
Sulfur Isotopes ◽  
Deep Understanding ◽  
Sulfur Cycle ◽  
Mass Extinctions ◽  
Deccan Volcanism ◽  
Organic Carbon Burial ◽  
Early Paleocene

&lt;p&gt;&lt;strong&gt;Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Arbia JOUINI&lt;sup&gt;1*&lt;/sup&gt;, Guillaume PARIS&lt;sup&gt;1&lt;/sup&gt;, Guillaume CARO&lt;sup&gt;1&lt;/sup&gt;, Annachiara BARTOLINI&lt;sup&gt;2&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;&lt;sup&gt;1 &lt;/sup&gt;Centre de Recherches P&amp;#233;trographiques et G&amp;#233;ochimiques, CRPG-CNRS, UMR7358, ,15 rue Notre Dame des Pauvres, BP20, 54501Vandoeuvre-l&amp;#232;s-Nancy, France, email:[email protected]&lt;/p&gt;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt; Mus&amp;#233;um National D&amp;#8217;Histoire Naturelle, D&amp;#233;partement Origines &amp; Evolution, CR2P MNHN, CNRS, Sorbonne Universit&amp;#233;, 8 rue Buffon CP38, 75005 Paris, France&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The Cretaceous&amp;#8211;Paleogene (KPg) mass extinction event 66 million years ago witnessed one of the &amp;#8216;Big Five&amp;#8217; mass extinctions of the Phanerozoic. Two major catastrophic events, the Chicxulub asteroid impact and the Deccan trap eruptions, were involved in complex climatic and environmental changes that culminated in the mass extinction including oceanic biogenic carbonate crisis, sea water chemistry and ocean oxygen level changes. Deep understanding of the coeval sulfur biogeochemical cycle may help to better constrain and quantify these parameters.&lt;/p&gt;&lt;p&gt;Here we present the first stratigraphic high resolution isotopic compositions of carbonate associated sulfate (CAS) based on monospecific planktic and benthic foraminifers' samples during the Maastrichtian-Danian transition from IODP pacific site 1209C. Primary &amp;#948;34SCAS data suggests that there was a major perturbation of sulfur cycle around the KPg transition with rapid fluctuations (100-200kyr) of about 2-4&amp;#8240; (&amp;#177;0.54&amp;#8240;, 2SD) during the late Maastrichtian followed by a negative excursion in &amp;#948;34SCAS of 2-3&amp;#8240; during the early Paleocene.&lt;/p&gt;&lt;p&gt;An increase in oxygen levels associated with a decline in organic carbon burial, related to a collapse in primary productivity, may have led to the early Paleocene &amp;#948;34SCAS negative shift via a significant drop in microbial sulfate reduction. Alternatively, Deccan volcanism could also have played a role and impacted the sulfur cycle via direct input of isotopically light sulfur to the ocean. A revised correlation between &amp;#948;34SCAS data reported in this study and a precise dating of the Deccan volcanism phases would allow us to explore this hypothesis.&lt;/p&gt;&lt;p&gt;Keywords : KPg boundary, Sulphur cycle, cycle du calcium, Planktic and benthic foraminifera&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Mass extinctions alter extinction and origination dynamics with respect to body size

2021 ◽  
Vol 288 (1960) ◽  
Author(s):  
Pedro M. Monarrez ◽  
Noel A. Heim ◽  
Jonathan L. Payne
Keyword(s):  
Body Size ◽  
Mass Extinction ◽  
Evolutionary Biology ◽  
Marine Animal ◽  
Mass Extinctions ◽  
Extinction Selectivity ◽  
Extinction Events ◽  
Mass Extinction Events ◽  
Marine Biosphere

Whether mass extinctions and their associated recoveries represent an intensification of background extinction and origination dynamics versus a separate macroevolutionary regime remains a central debate in evolutionary biology. The previous focus has been on extinction, but origination dynamics may be equally or more important for long-term evolutionary outcomes. The evolution of animal body size is an ideal process to test for differences in macroevolutionary regimes, as body size is easily determined, comparable across distantly related taxa and scales with organismal traits. Here, we test for shifts in selectivity between background intervals and the ‘Big Five’ mass extinction events using capture–mark–recapture models. Our body-size data cover 10 203 fossil marine animal genera spanning 10 Linnaean classes with occurrences ranging from Early Ordovician to Late Pleistocene (485–1 Ma). Most classes exhibit differences in both origination and extinction selectivity between background intervals and mass extinctions, with the direction of selectivity varying among classes and overall exhibiting stronger selectivity during origination after mass extinction than extinction during the mass extinction. Thus, not only do mass extinction events shift the marine biosphere into a new macroevolutionary regime, the dynamics of recovery from mass extinction also appear to play an underappreciated role in shaping the biosphere in their aftermath.

scholarly journals Sex-Related Differences in the Maximal Lactate Steady State

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 154 ◽  
Author(s):  
Paul Hafen ◽  
Pat Vehrs
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Steady State ◽  
Respiratory Exchange Ratio ◽  
Time To Exhaustion ◽  
Distance Runners ◽  
Maximal Lactate Steady State ◽  
Training Tool ◽  
Significant Difference ◽  
Males And Females

The maximal lactate steady state (MLSS) is one of the factors that differentiates performance in aerobic events. The purpose of this study was to investigate the sex differences in oxygen consumption (VO2), heart rate (HR), and the respiratory exchange ratio (RER) at the MLSS in well-trained distance runners. Twenty-two (12 female, 10 male) well-trained distance runners (23 ± 5.0 years) performed multiple 30-min steady-state runs to determine their MLSS, during which blood lactate and respiratory gas exchange measures were taken. To interpret the MLSS intensity as a training tool, runners completed a time-to-exhaustion (TTE) run at their MLSS. The relative intensity at which the MLSS occurred was identical between males and females according to both oxygen consumption (83 ± 5 %O2max) and heart rate (89 ± 7 %HRmax). However, female runners displayed a significantly lower RER at MLSS compared to male runners (p < 0.0001; 0.84 ± 0.02 vs. 0.88 ± 0.04, respectively). There was not a significant difference in TTE at MLSS between males (79 ± 17 min) and females (80 ± 25 min). Due to the observed difference in the RER at the MLSS, it is suggested that RER derived estimates of MLSS be sex-specific. While the RER data suggest that the MLSS represents different metabolic intensities for males and females, the relative training load of MLSS appears to be similar in males and female runners.

scholarly journals Using dual-calibrated functional MRI to map brain oxygen supply and consumption in multiple sclerosis

2021 ◽  
Author(s):  
Hannah L Chandler ◽  
Rachael C Stickland ◽  
Michael Germuska ◽  
Eleonora Patitucci ◽  
Catherine Foster ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Oxygen Consumption ◽  
Healthy Volunteers ◽  
Oxygen Supply ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Group Differences ◽  
Lesion Volume ◽  
Brain Physiology ◽  
Significant Difference

Evidence suggests that cerebrovascular function and oxygen consumption are altered in multiple sclerosis (MS). Here, we quantified the vascular and oxygen metabolic MRI burden in patients with MS (PwMS) and assessed the relationship between these MRI measures of and metrics of damage and disability. In PwMS and in matched healthy volunteers, we applied a newly developed dual-calibrated fMRI method of acquisition and analysis to map grey matter (GM) cerebral blood flow (CBF), oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen consumption (CMRO2) and effective oxygen diffusivity of the capillary network (DC). We also quantified physical and cognitive function in PwMS and controls. There was no significant difference in GM volume between 22 PwMS and 20 healthy controls (p=0.302). Significant differences in CBF (PwMS vs. controls: 44.91 +/- 6.10 vs. 48.90 +/- 5.87 ml/100g/min, p=0.010), CMRO2 (117.69 +/- 17.31 vs. 136.49 +/- 14.48 μmol/100g/min p<0.001) and DC (2.70 +/- 0.51 vs. 3.18 +/- 0.41 μmol/100g/mmHg/min, p=0.002) were observed in the PwMS. No significant between-group differences were observed for OEF (PwMS vs. controls: 0.38 +/- 0.09 vs. 0.39 +/- 0.02, p=0.358). Regional analysis showed widespread reductions in CMRO2 and DC for PwMS compared to healthy volunteers. There was a significant correlation between physiological measures and T2 lesion volume, but no association with current clinical disability. Our findings demonstrate concurrent reductions in oxygen supply and consumption in the absence of an alteration in oxygen extraction that may be indicative of a reduced demand for oxygen (O2), an impaired transfer of O2 from capillaries to mitochondria, and/or a reduced ability to utilise O2 that is available at the mitochondria. With no between-group differences in GM volume, our results suggest that changes in brain physiology may precede MRI-detectable GM loss and thus may be one of the pathological drivers of neurodegeneration and disease progression.

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