scholarly journals Revisiting the sedimentary record of the rise of diatoms

2021 ◽  
Vol 118 (27) ◽  
pp. e2103517118
Author(s):  
Sophie Westacott ◽  
Noah J. Planavsky ◽  
Ming-Yu Zhao ◽  
Pincelli M. Hull
Keyword(s):  
Sedimentation Rate ◽  
Null Hypothesis ◽  
Critical Role ◽  
Causal Link ◽  
Late Cenozoic ◽  
Sedimentary Record ◽  
Baleen Whales ◽  
Preservation Potential ◽  
Primary Producer ◽  
Silica Cycle

Diatoms are a major primary producer in the modern oceans and play a critical role in the marine silica cycle. Their rise to dominance is recognized as one of the largest shifts in Cenozoic marine ecosystems, but the timing of this transition is debated. Here, we use a diagenetic model to examine the effect of sedimentation rate and temperature on the burial efficiency of biogenic silica over the past 66 million years (i.e., the Cenozoic). We find that the changing preservation potential of siliceous microfossils during that time would have overprinted the primary signal of diatom and radiolarian abundance. We generate a taphonomic null hypothesis of the diatom fossil record by assuming a constant flux of diatoms to the sea floor and having diagenetic conditions driven by observed shifts in temperature and sedimentation rate. This null hypothesis produces a late Cenozoic (∼5 Ma to 20 Ma) increase in the relative abundance of fossilized diatoms that is comparable to current empirical records. This suggests that the observed increase in diatom abundance in the sedimentary record may be driven by changing preservation potential. A late Cenozoic rise in diatoms has been causally tied to the rise of grasslands and baleen whales and to declining atmospheric CO2 levels. Here we suggest that the similarity among these records primarily arises from a common driver—the cooling climate system—that drove enhanced diatom preservation as well as the rise of grasslands and whales, rather than a causal link among them.

scholarly journals Guide snoRNAs: Drivers or Passengers in Human Disease?

Biology ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 1 ◽  
Author(s):  
Manisha Deogharia ◽  
Mrinmoyee Majumder
Keyword(s):  
Protein Interactions ◽  
Human Disease ◽  
Critical Role ◽  
Mrna Translation ◽  
Causal Link ◽  
Rna Modification ◽  
Disease Manifestation ◽  
The Stability ◽  
Nucleoside Modification ◽  
Host Genes

In every domain of life, RNA-protein interactions play a significant role in co- and post-transcriptional modifications and mRNA translation. RNA performs diverse roles inside the cell, and therefore any aberrancy in their function can cause various diseases. During maturation from its primary transcript, RNA undergoes several functionally important post-transcriptional modifications including pseudouridylation and ribose 2′-O-methylation. These modifications play a critical role in the stability of the RNA. In the last few decades, small nucleolar RNAs (snoRNAs) were revealed to be one of the main components to guide these modifications. Due to their active links to the nucleoside modification, deregulation in the snoRNA expressions can cause multiple disorders in humans. Additionally, host genes carrying snoRNA-encoding sequences in their introns also show differential expression in disease. Although few reports support a causal link between snoRNA expression and disease manifestation, this emerging field will have an impact on the way we think about biomarkers or identify novel targets for therapy. This review focuses on the intriguing aspect of snoRNAs that function as a guide in post-transcriptional RNA modification, and regulation of their host genes in human disease.

scholarly journals Prenatal Malnutrition-Induced Epigenetic Dysregulation as a Risk Factor for Type 2 Diabetes

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Alexander Vaiserman ◽  
Oleh Lushchak
Keyword(s):  
Type 2 Diabetes ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Epidemiological Data ◽  
Later Life ◽  
Causal Link ◽  
Related Factors ◽  
Insulin Metabolism ◽  
Prenatal Malnutrition

Type 2 diabetes (T2D) is commonly regarded as a disease originating from lifestyle-related factors and typically occurring after the age of 40. There is, however, consistent experimental and epidemiological data evidencing that the risk for developing T2D may largely depend on conditions early in life. In particular, intrauterine growth restriction (IUGR) induced by poor or unbalanced nutrient intake can impair fetal growth and also cause fetal adipose tissue and pancreatic β-cell dysfunction. On account of these processes, persisting adaptive changes can occur in the glucose-insulin metabolism. These changes can include reduced ability for insulin secretion and insulin resistance, and they may result in an improved capacity to store fat, thereby predisposing to the development of T2D and obesity in adulthood. Accumulating research findings indicate that epigenetic regulation of gene expression plays a critical role in linking prenatal malnutrition to the risk of later-life metabolic disorders including T2D. In animal models of IUGR, changes in both DNA methylation and expression levels of key metabolic genes were repeatedly found which persisted until adulthood. The causal link between epigenetic disturbances during development and the risk for T2D was also confirmed in several human studies. In this review, the conceptual models and empirical data are summarized and discussed regarding the contribution of epigenetic mechanisms in developmental nutritional programming of T2D.

scholarly journals The structure and global distribution of the endoplasmic reticulum network are actively regulated by lysosomes

2020 ◽  
Vol 6 (51) ◽  
pp. eabc7209
Author(s):  
Meng Lu ◽  
Francesca W. van Tartwijk ◽  
Julie Qiaojin Lin ◽  
Wilco Nijenhuis ◽  
Pierre Parutto ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Nutritional Status ◽  
Neuronal Development ◽  
Critical Role ◽  
Causal Link ◽  
Global Distribution ◽  
Growth Defects ◽  
Cellular Environment ◽  
Axonal Extension

The endoplasmic reticulum (ER) comprises morphologically and functionally distinct domains: sheets and interconnected tubules. These domains undergo dynamic reshaping in response to changes in the cellular environment. However, the mechanisms behind this rapid remodeling are largely unknown. Here, we report that ER remodeling is actively driven by lysosomes, following lysosome repositioning in response to changes in nutritional status: The anchorage of lysosomes to ER growth tips is critical for ER tubule elongation and connection. We validate this causal link via the chemo- and optogenetically driven repositioning of lysosomes, which leads to both a redistribution of the ER tubules and a change of its global morphology. Therefore, lysosomes sense metabolic change in the cell and regulate ER tubule distribution accordingly. Dysfunction in this mechanism during axonal extension may lead to axonal growth defects. Our results demonstrate a critical role of lysosome-regulated ER dynamics and reshaping in nutrient responses and neuronal development.

scholarly journals Tropical nighttime warming as a dominant driver of variability in the terrestrial carbon sink

2015 ◽  
Vol 112 (51) ◽  
pp. 15591-15596 ◽  
Author(s):  
William R. L. Anderegg ◽  
Ashley P. Ballantyne ◽  
W. Kolby Smith ◽  
Joseph Majkut ◽  
Sam Rabin ◽  
...  
Keyword(s):  
Carbon Sink ◽  
Critical Role ◽  
Causal Link ◽  
Temperature And Precipitation ◽  
Interannual Climate Variability ◽  
Future Warming ◽  
Nighttime Temperatures ◽  
Terrestrial Carbon Sink ◽  
Atmospheric Mass ◽  
Nighttime Warming

The terrestrial biosphere is currently a strong carbon (C) sink but may switch to a source in the 21st century as climate-driven losses exceed CO2-driven C gains, thereby accelerating global warming. Although it has long been recognized that tropical climate plays a critical role in regulating interannual climate variability, the causal link between changes in temperature and precipitation and terrestrial processes remains uncertain. Here, we combine atmospheric mass balance, remote sensing-modeled datasets of vegetation C uptake, and climate datasets to characterize the temporal variability of the terrestrial C sink and determine the dominant climate drivers of this variability. We show that the interannual variability of global land C sink has grown by 50–100% over the past 50 y. We further find that interannual land C sink variability is most strongly linked to tropical nighttime warming, likely through respiration. This apparent sensitivity of respiration to nighttime temperatures, which are projected to increase faster than global average temperatures, suggests that C stored in tropical forests may be vulnerable to future warming.

Magnetostratigraphy of the Yili Basin indicates Late Cenozonic activity of the Tianshan Mountain, northwestern China

2021 ◽  
Author(s):  
Liu Xiaoyan ◽  
Yuan Sihua ◽  
Jin Chunsheng ◽  
Bai Xiangdong ◽  
Jiang Jiyi ◽  
...  
Keyword(s):  
Sedimentation Rate ◽  
Time Scale ◽  
Qaidam Basin ◽  
Middle Pleistocene ◽  
Tectonic Deformation ◽  
Tianshan Mountain ◽  
Late Cenozoic ◽  
Tectonic Event ◽  
The Core ◽  
Drilling Core

<div> <p>The Yili basin, sandwiched in the Northern and Southern Tianshan Mountain, is an ideal area to study the eroded histories at the Northern Tianshan Mountain during the late Cenozoic. Massive works have been done on tectonic deformation and uplift in this region. However, due to the lack of biostratigraphic data and effective dating marks, the uplifting time limit of the Tianshan Mountain are still argued by many researchers. In order to constrain the uplift history in the west Tianshan Mountain and provid the late Cenozoic time scale, we carried out a series of studies in the Chinese Yili Basin, fortunately, we acquired a drilling core with a depth of 500 m in the Quarternary depocenter in this basin, which provides the basis for the relevant studies. These results offered basic geological data for protecting against and mitigating earthquake disasters. </p> <p>A magnetic stratigraphic study was carried out on the drilling core, combined with three OSL dating data from a natural section adjacent to the drilling hole, an effective time scale was established. There are three main results as follows: (1)The polarity sequences shows 5 normal and 5 reverse polarity zones which can be readily correlated with the Geomagnetic Polarity Time Scale (GPTS2012), dating the core from 3.11Ma to 12Ka. (2) The B/M boundary of magnetic strata in the 500m core in western Yili basin is located in the core 80m and M/G line is located in the core 400m. (3) The sedimentation rate in the western Yili Basin increased rapidly at two periods, ~1.17 to 1.07Ma and ~2.13 to 1.77Ma. </p> <p>According to the regional reference data, the peak deposition rate in the range of ~ 2.13 to 1.77Ma is closely related to the Xiyu movement in Northwest China, as a corollary, the sedimentation rate should decrease with the end of Xiyu Movement after ~1.77Ma. Another obvious lithofacies change from ~1.17 to 1.07Ma illustrates there should be a tectonic event in the Tian shan region. This Middle Pleistocene uplift can also be evidenced by the age of volcanism in the Qaidam Basin (northeastern Tibetan Plateau), the existence of thick conglomerate deposits surrounding the uplifted plateau, and the increased sedimentation rate of lacustrine deposits in the between ~1.1 and ~0.9Ma ago, followed by the loess and marine records.</p> </div>

scholarly journals Entrainment of local synchrony reveals a causal role for high-beta right frontal oscillations in human visual consciousness

2019 ◽  
Author(s):  
Marine Vernet ◽  
Chloé Stengel ◽  
Romain Quentin ◽  
Julià L. Amengual ◽  
Antoni Valero-Cabré
Keyword(s):  
Visual Detection ◽  
Critical Role ◽  
Causal Link ◽  
Oscillatory Activity ◽  
Frontal Eye Field ◽  
Phase Alignment ◽  
Visual Behaviors ◽  
Eye Field ◽  
The Right ◽  
High Beta

AbstractPrior evidence supports the critical role of oscillatory activity in cognitive function, but are cerebral oscillations simply correlated or causally linked to specific aspects of visual cognition? Here, EEG signals were recorded on humans performing a conscious visual detection task, while they received briefrhythmicorrandomnoninvasive stimulation patterns delivered to the right Frontal Eye Field prior to the onset of a lateralized target. Compared torandompatterns,rhythmichigh-beta patterns led to greater entrainment of local oscillations (i.e., increased power and phase alignment at the stimulation frequency), and to higher conscious detection of contralateral targets. When stimulation succeeded in enhancing visual detection, the magnitude of oscillation entrainment correlated with visual performance increases. Our study demonstrates a causal link between high-beta oscillatory activity in the Frontal Eye Field and conscious visual perception. Furthermore, it supports future applications of brain stimulation to manipulate local synchrony and improve or restore impaired visual behaviors.

scholarly journals Mitochondrial Redox Signaling Is Critical to the Normal Functioning of the Neuronal System

2021 ◽  
Vol 9 ◽  
Author(s):  
Olena Odnokoz ◽  
Kyle Nakatsuka ◽  
Corbin Wright ◽  
Jovelyn Castellanos ◽  
Vladimir I. Klichko ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dysfunction ◽  
Neurological Disorders ◽  
Critical Role ◽  
Redox Balance ◽  
Causal Link ◽  
Temperature Sensitive ◽  
Neural Function ◽  
Neuronal System ◽  
Age Related

Mitochondrial dysfunction often leads to neurodegeneration and is considered one of the main causes of neurological disorders, such as Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and other age-related diseases. Mitochondrial dysfunction is tightly linked to oxidative stress and accumulating evidence suggests the association between oxidative stress and neurological disorders. However, there is insufficient knowledge about the role of pro-oxidative shift in cellular redox and impairment of redox-sensitive signaling in the development of neurodegenerative pathological conditions. To gain a more complete understanding of the relationship between mitochondria, redox status, and neurodegenerative disorders, we investigated the effect of mitochondrial thiol-dependent peroxidases, peroxiredoxins (Prxs), on the physiological characteristics of flies, which change with pathologies such as PD, ALS and during aging. We previously found that through their ability to sense changes in redox and regulate redox-sensitive signaling, Prxs play a critical role in maintaining global thiol homeostasis, preventing age-related apoptosis and chronic activation of the immune response. We also found that the phenotype of flies under-expressing Prxs in mitochondria shares many characteristics with the phenotype of Drosophila models of neurological disorders such as ALS, including impaired locomotor activity and compromised redox balance. Here, we expanded the study and found that under-expression of mitochondrial Prxs leads to behavioral changes associated with neural function, including locomotor ability, sleep-wake behavior, and temperature-sensitive paralysis. We also found that under-expression of mitochondrial Prxs with a motor-neuron-specific driver, D42-GAL4, was a determining factor in the development of the phenotype of shortened lifespan and impaired motor activity in flies. The results of the study suggest a causal link between mitochondrial Prx activity and the development of neurological disorders and pre-mature aging.

The Role of Diagenesis in the Apparent Rise of Diatoms

2021 ◽  
Author(s):  
Sophie Westacott ◽  
Noah Planavsky ◽  
Ming-Yu Zhao ◽  
Pincelli Hull
Keyword(s):  
Silicon Isotope ◽  
Sedimentation Rates ◽  
Bottom Water Temperature ◽  
Baleen Whales ◽  
The Past ◽  
Isotope Evidence ◽  
Silica Cycle ◽  
Fossil Data ◽  
Burial Efficiency

<p><span>Diatoms are one of the most dominant primary producers in the ocean today and largely control the modern marine silica cycle. Their ecological expansion in the Cenozoic is thought to have lowered silica concentrations by two orders of magnitude and has been linked to the rise of grasslands and baleen whales. According to the fossil record much of diatoms' rise to dominance occurred in the past 20 m.y.; however, silicon isotope evidence suggests an earlier expansion. Using a diagenetic model and collated deep sea drill core data, we examine how changes in bottom-water temperature and sedimentation rates over the past 65 m.y. affected the burial efficiency of biogenic silica. We find that once taphonomic potential is taken into account there is no support for the traditionally recognized ~5-20 Ma increase in diatom abundance. These results help reconcile interpretations based on geochemical and fossil data, and add to mounting evidence pushing back the evolution of the modern silica cycle to before 20 Ma and possibly earlier than 40 Ma.</span></p>

The independent association of preoperative serum albumin on the functional maturation of radiocephalic arteriovenous fistulae

2017 ◽  
Vol 18 (2) ◽  
pp. 148-152 ◽  
Author(s):  
Ali Kordzadeh ◽  
Evripidis Tokidis ◽  
Alan Askari ◽  
Mekhola Hoff ◽  
Yiannis Panayiotopoulos
Keyword(s):  
Null Hypothesis ◽  
Causal Link ◽  
Multivariate Logistic Regression Model ◽  
Arteriovenous Fistulae ◽  
Functional Maturation ◽  
Preoperative Serum ◽  
Chi Squared ◽  
Independent Association ◽  
Independent Marker ◽  
Preoperative Albumin

Purpose The aim of this study is to test the null hypothesis that preoperative albumin along with other preoperative confounders have no impact on the functional maturation of radiocephalic arteriovenous fistulae (RCAVF). Methods A retrospective cohort study of n = 195 individuals undergoing RCAVF formation from July 2013 to December 2015 was conducted. The null hypothesis was assessed through chi squared test. Independent association of each variable was evaluated through univariate and multivariate logistic regression model. Pearson's correlation test was also performed between scale variables to establish their causal link. Results Preoperative hypoalbuminaemic group of individuals demonstrated significant failure of maturation (49.3% vs. 27.2%, p = 0.002). At multivariate analysis, hypoalbuminemia remained an independent marker of fistula failure (OR 0.40, 95% CI 0.21-0.76, p = 0.004) and demonstrated a weak but a positive correlation at the endpoint of maturation (R = 0.223, p = 0.002). Conclusions Preoperative hypoalbuminemia (<35 mg/dL) is independently associated with 40% reduction in the functional maturation of RCAVF. Stratification of this readily available biomarker prior to RCAVF formation may require consideration subjected to further research.

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