scholarly journals Multiple environmental parameters impact core lipid cyclization in Sulfolobus acidocaldarius

2020 ◽  
Author(s):  
Alec Cobban ◽  
Yujiao Zhang ◽  
Alice Zhou ◽  
Yuki Weber ◽  
Ann Pearson ◽  
...  
Keyword(s):  
Growth Rate ◽  
Membrane Lipids ◽  
Environmental Parameters ◽  
Cellular Level ◽  
Sulfolobus Acidocaldarius ◽  
Energy Availability ◽  
Hydrophobic Core ◽  
Core Lipid ◽  
Different Temperatures ◽  
Experimental Findings

ABSTRACTEnvironmental reconstructions based on microbial lipids require understanding the coupling between environmental conditions and membrane physiology. The paleotemperature proxy TEX86 is built on the observation that archaea alter the number of five- and six-membered rings in the hydrophobic core of their glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids when growing at different temperatures. However, recent work with these archaea also highlights a role for other factors, such as pH or energy availability in determining the degree of core lipid cyclization. To better understand the role of these variables we cultivated a model Crenarchaeon, Sulfolobus acidocaldarius, over a range in temperature, pH, oxygen flux, or agitation speed, and quantified the changes in growth rate, biomass yield, and core lipid compositions. The average degree of cyclization in core lipids correlated with growth rate under most conditions. When considered alongside other experimental findings from both the thermoacidophilic and mesoneutrophilic archaea, the results suggest the cyclization of archaeal lipids records a universal response to energy availability at the cellular level. Although we isolated the effects of individual parameters, there remains a need for multi-factor experiments (e.g., pH + temperature + redox) to establish a robust framework to interpret biomarker records of environmental change.

scholarly journals StalGrowth—A Program to Estimate Speleothem Growth Rates and Seasonal Growth Variations

Geosciences ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 187
Author(s):  
Rolf Vieten ◽  
Francisco Hernandez
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Environmental Parameters ◽  
Ion Concentration ◽  
Radiometric Dating ◽  
Seasonal Growth ◽  
Climate Signal ◽  
Show Evidence ◽  
Cave Monitoring ◽  
Calcium Ion Concentration

Speleothems are one of the few archives which allow us to reconstruct the terrestrial paleoclimate and help us to understand the important climate dynamics in inhabited regions of our planet. Their time of growth can be precisely dated by radiometric techniques, but unfortunately seasonal radiometric dating resolution is so far not feasible. Numerous cave environmental monitoring studies show evidence for significant seasonal variations in parameters influencing carbonate deposition (calcium-ion concentration, cave air pCO2, drip rate and temperature). Variations in speleothem deposition rates need to be known in order to correctly decipher the climate signal stored in the speleothem archive. StalGrowth is the first software to quantify growth rates based on cave monitoring results, detect growth seasonality and estimate the seasonal growth bias. It quickly plots the predicted speleothem growth rate together with the influencing cave environmental parameters to identify which parameter(s) cause changes in speleothem growth rate, and it can also identify periods of no growth. This new program has been applied to multiannual cave monitoring studies in Austria, Gibraltar, Puerto Rico and Texas, and it has identified two cases of seasonal varying speleothem growth.

scholarly journals On the structural connectivity of large-scale models of brain networks at cellular level

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Giuseppe Giacopelli ◽  
Domenico Tegolo ◽  
Emiliano Spera ◽  
Michele Migliore
Keyword(s):  
Large Scale ◽  
Brain Networks ◽  
Structural Connectivity ◽  
Network Models ◽  
Brain Regions ◽  
Cellular Level ◽  
Scale Model ◽  
Mathematical Framework ◽  
Underlying Mechanisms ◽  
Experimental Findings

AbstractThe brain’s structural connectivity plays a fundamental role in determining how neuron networks generate, process, and transfer information within and between brain regions. The underlying mechanisms are extremely difficult to study experimentally and, in many cases, large-scale model networks are of great help. However, the implementation of these models relies on experimental findings that are often sparse and limited. Their predicting power ultimately depends on how closely a model’s connectivity represents the real system. Here we argue that the data-driven probabilistic rules, widely used to build neuronal network models, may not be appropriate to represent the dynamics of the corresponding biological system. To solve this problem, we propose to use a new mathematical framework able to use sparse and limited experimental data to quantitatively reproduce the structural connectivity of biological brain networks at cellular level.

scholarly journals The fate and function of glycosphingolipid glucosylceramide

2003 ◽  
Vol 358 (1433) ◽  
pp. 869-873 ◽  
Author(s):  
Gerrit van Meer ◽  
Jasja Wolthoorn ◽  
Sophie Degroote
Keyword(s):  
Cellular Differentiation ◽  
Membrane Lipids ◽  
Early Stage ◽  
Cellular Level ◽  
Mature Stage ◽  
Storage Diseases ◽  
Head Groups ◽  
Biological Studies ◽  
Intracellular Membrane Transport ◽  
And Function

In higher eukaryotes, glucosylceramide is the simplest member and precursor of a fascinating class of membrane lipids, the glycosphingolipids. These lipids display an astounding variation in their carbohydrate head groups, suggesting that glycosphingolipids serve specialized functions in recognition processes. It is now realized that they are organized in signalling domains on the cell surface. They are of vital importance as, in their absence, embryonal development is inhibited at an early stage. Remarkably, individual cells can live without glycolipids, perhaps because their survival does not depend on glycosphingolipid–mediated signalling mechanisms. Still, these cells suffer from defects in intracellular membrane transport. Various membrane proteins do not reach their intracellular destination, and, indeed, some intracellular organelles do not properly differentiate to their mature stage. The fact that glycosphingolipids are required for cellular differentiation suggests that there are human diseases resulting from defects in glycosphingolipid synthesis. In addition, the same cellular differentiation processes may be affected by defects in the degradation of glycosphingolipids. At the cellular level, the pathology of glycosphingolipid storage diseases is not completely understood. Cell biological studies on the intracellular fate and function of glycosphingolipids may open new ways to understand and defeat not only lipid storage diseases, but perhaps other diseases that have not been connected to glycosphingolipids so far.

scholarly journals Effects of light intensity and temperature on Cylindrospermopsis raciborskii (Cyanobacteria) with straight and coiled trichomes: growth rate and morphology

2012 ◽  
Vol 72 (2) ◽  
pp. 343-351 ◽  
Author(s):  
MC. Bittencourt-Oliveira ◽  
B. Buch ◽  
TC. Hereman ◽  
JDT. Arruda-Neto ◽  
AN. Moura ◽  
...  
Keyword(s):  
Growth Rate ◽  
Light Intensity ◽  
Morphological Changes ◽  
Population Control ◽  
Distinct Species ◽  
Cylindrospermopsis Raciborskii ◽  
Climatic Chamber ◽  
Light Intensities ◽  
Different Temperatures ◽  
Lower Temperature

Cylindrospermopsis raciborskii (Woloszynska) Seenayya et Subba Raju (Ordem Nostocales) is one of the most troublesome bloom-forming species in Brazil. Understanding the population dynamics of the different morphotypes of C. raciborskii (straight and coiled) could assist in the prediction of favourable conditions for the proliferation of this potentially toxin-producing species. The aim of the present study was to assess the effects of two different light intensities and temperatures on the growth rate and morphology of the trichomes of the straight and coiled morphotypes. For such, two non-toxin producing strains of C. raciborskii were used - one with a coiled trichome (ITEP31) and another with a straight trichome (ITEP28). The strains were cultured in BG-11 medium in a climatic chamber under controlled conditions. Two light intensities (30 and 90 µmol.m-2.s-1 ) were combined at temperatures of 21 and 31 °C and the growth rate and morphological changes were analysed. The morphotypes responded differently to the different temperatures and light intensities. Both strains exhibited faster growth velocities when submitted to higher light intensity and temperature. The lower temperature and higher luminosity hampered the development of both strains. Variations in cellular morphology and an absence of akinetes in both strains were related to the lower temperature (21 °C). The coiled morphotype demonstrated considerable phenotype plasticity, changing the morphology of trichome throughout its growth curve. Although molecular analysis does not sustain the separation of the morphotypes as distinct species, their different eco-physiological responses should be considered further knowledge of extreme importance for the population control of these potentially toxic organisms.

scholarly journals Characteristics оf growth and fluorescence оf certain types оf algae under acclimation to different temperatures under conditions оf cultures

2019 ◽  
Vol 59 (3) ◽  
pp. 347-359
Author(s):  
A. I. Akimov ◽  
E. S. Solomonova
Keyword(s):  
Growth Rate ◽  
Positive Temperature ◽  
Tolerance Zone ◽  
Lower Growth ◽  
Culture Collections ◽  
Thermal Growth ◽  
Different Temperatures ◽  
Temperature Rate ◽  
Relative Variable ◽  
Stable Growth

The temperature rate growth dependence and the relative variable fluorescence, (Fv/Fm) of some of marine planktonic algae from the culture collections were investigated. The algae optima temperature growth (Topt), upper and lower limits tolerant zone of species, and in some cases, changes in the dynamics of these parameters outside the tolerance zone were determined. The similarity of species temperature characteristics with vegetation conditions these species in the nature was observed. Prolonged stress exposure to low positive temperature (4–6°C) was reversible; recovery of the growth rate and Fv/Fm was observed immediately after the increase of temperature. At temperatures above Topt on 2–3°C for diatoms was observed gradual degradation of culture, which, depending on the duration of exposure can lead to the death of the algae. Dinoflagellate species of the summer growing season had higher temperature resistance, and remained viable at temperatures above 5–8°C high Topt, due to lower growth rates. Rising part temperature dependence of the rate of growth approximated by a linear relation, the regression coefficient is 0.08–0.13 for diatoms and 0.03–0.11 for dinophyte. The normalized values for this parameter (the relative value of change in the growth rate, %) was 5.3±0.4 for diatoms and 6.4±0.5 for dinophyte at 1°C of temperature change. For dinophyte species were also been observed larger values of the parameter Q10. The value Fv/Fm for most species had high values in the whole temperature range, in which maintained a stable growth of algae. The fall of this parameter was observed in increasing the border of tolerance zone, and was associated with inhibition of thermal growth processes.

scholarly journals Revised fractional abundances and warm-season temperatures substantially improve brGDGT calibrations in lake sediments

2021 ◽  
Author(s):  
Jonathan H. Raberg ◽  
David J. Harning ◽  
Sarah E. Crump ◽  
Greg de Wet ◽  
Aria Blumm ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Lake Sediment ◽  
Membrane Lipids ◽  
Warm Season ◽  
Environmental Parameters ◽  
Structural Diversity ◽  
Temperature Conductivity ◽  
Advantages And Disadvantages ◽  
Natural Logarithm ◽  
Air Temperatures

Abstract. Distributions of branched glycerol dialkyl glycerol tetraethers (brGDGTs) are frequently employed for reconstructing terrestrial paleotemperatures from lake sediment archives. Although brGDGTs are globally ubiquitous, the microbial producers of these membrane lipids remain unknown, precluding a full understanding of the ways in which environmental parameters control their production and distribution. Here, we advance this understanding in three ways. First, we present 43 new high-latitude lake sites characterized by low mean annual air temperatures (MATs) and high seasonality, filling an important gap in the global dataset. Second, we introduce a new approach for analyzing brGDGT data in which compound fractional abundances (FAs) are calculated within structural groups based on methylation number, methylation position, and cyclization number. Finally, we perform linear and nonlinear regressions of the resulting FAs against a suite of environmental parameters in a compiled global lake sediment dataset (n = 182). We find that our approach deconvolves temperature, conductivity, and pH trends in brGDGTs without increasing calibration errors from the standard approach. We also find that it reveals novel patterns in brGDGT distributions and provides a methodology for investigating the biological underpinnings of their structural diversity. Warm-season temperature indices outperformed MAT in our regressions, with Months Above Freezing yielding the highest-performing model (adjusted R2 = 0.91, RMSE = 1.97 °C, n = 182). The natural logarithm of conductivity had the second-strongest relationship to brGDGT distributions (adjusted R2 = 0.83, RMSE = 0.66, n = 143), notably outperforming pH in our dataset (adjusted R2 = 0.73, RMSE = 0.57, n = 154) and providing a potential new proxy for paleohydrology applications. We recommend these calibrations for use in lake sediments globally, including at high latitudes, and detail the advantages and disadvantages of each.

scholarly journals Discovery of the first succulent bamboo (Poaceae, Bambusoideae) in a new genus from Laos’ karst areas, with a unique adaptation to seasonal drought

PhytoKeys ◽  
2020 ◽  
Vol 156 ◽  
pp. 125-137
Author(s):  
Thomas Haevermans ◽  
Dulce Mantuano ◽  
Meng-Yuan Zhou ◽  
Vichith Lamxay ◽  
Agathe Haevermans ◽  
...  
Keyword(s):  
New Genus ◽  
Morphological Characteristics ◽  
Environmental Parameters ◽  
Molecular Data ◽  
Cellular Level ◽  
New Taxon ◽  
Seasonal Drought ◽  
Paper Document ◽  
Woody Bamboos ◽  
Phylogenetic Affinities

Lush jungle flagship species, woody bamboos (Poaceae–Bambusoideae) are famed for their synchronous flowering as well as the extensive “bamboo forests” some species can form in tropical or temperate environments. In portions of their natural distribution, Bambusoideae members developed various adaptations to seasonality in environmental parameters, such as frost or seasonal drought. A new taxon, Laobambos calcareus, described here, is extremely novel in showing the first documented case of succulence in bamboos, with its ability to seasonally vary the volume of its stem depending on the quantity of water stored. Anatomical studies presented in this paper document this specificity at the cellular level. Though no flowers or fruits are known yet, unique morphological characteristics along with an investigation of its phylogenetic affinities using molecular data show that this new taxon should belong to a new genus herein described.

scholarly journals A Temperature Variation of Debye-Waller Factor for Alkali and Noble Metals

1983 ◽  
Vol 38 (5) ◽  
pp. 503-508 ◽  
Author(s):  
A. R. Jani ◽  
V. B. Gohel
Keyword(s):  
Experimental Data ◽  
Temperature Variation ◽  
Phenomenological Model ◽  
Noble Metals ◽  
Experimental Information ◽  
Waller Factor ◽  
Critical Examination ◽  
Debye Waller Factor ◽  
Different Temperatures ◽  
Experimental Findings

Debye-Waller factors at different temperatures of four alkali and three noble metals have been computed on the basis of a screened shell phenomenological model. The theoretical values are compared with existing experimental data. Particularly for lithium and potassium, most recent experimental information has been included. A critical examination of the results reveals a satis­factory agreement between the theoretical and experimental findings.

scholarly journals Performance of fat snook juveniles reared at different temperatures

2018 ◽  
Vol 40 (1) ◽  
pp. 39766
Author(s):  
Daniel Correia ◽  
Luiz Henrique Castro David ◽  
Sara Mello Pinho ◽  
João Costa-Filho ◽  
Maurício Gustavo Coelho Emerenciano ◽  
...  
Keyword(s):  
Growth Rate ◽  
Weight Gain ◽  
Specific Growth ◽  
Survival Rates ◽  
Feeding Rates ◽  
Feed Conversion ◽  
Final Weight ◽  
Different Temperatures ◽  
Water Recirculation ◽  
Fat Snook

We aimed at evaluating the effects of different water temperatures on the zootechnical performance of fat snook. The experiment lasted for 60 days, which was conducted in water recirculation systems, and was randomly designed with three treatments and three replicates each, corresponding to three water temperatures (25, 28 and 31°C). A total of 225 fat snook juveniles with a mean weight of 6.45 ± 0.58 g were used, which were fed daily until apparent satiety. Zootechnical parameters were assessed and feeding rates were registered for each tested temperature. Survival rates varied from 96 to 100% among treatments. Higher values of standard and total length, and weight gain were found in 28 and 31°C (p < 0.05). With regard to final weight, final biomass, feed conversion and specific growth rate, no significant differences were observed (p > 0.05). Feeding rates did not differ among evaluated temperatures. The results show that the used temperatures did not negatively affect zootechnical performance of fat snook juveniles. 

Growth Kinetics of Salmonella Isolates in a Laboratory Medium as Affected by Isolate and Holding Temperature†

1998 ◽  
Vol 61 (8) ◽  
pp. 964-968 ◽  
Author(s):  
THOMAS P. OSCAR
Keyword(s):  
Growth Rate ◽  
Stationary Phase ◽  
Growth Kinetics ◽  
Brain Heart Infusion ◽  
Lag Time ◽  
Culture Collection ◽  
Subsequent Growth ◽  
Laboratory Medium ◽  
Different Temperatures ◽  
Holding Temperature

Salmonella isolates were surveyed for their growth kinetics in a laboratory medium for the purpose of identifying isolates suitable for modeling experiments. In addition, the effect of holding stationary phase Salmonella cultures at different temperatures on their subsequent growth kinetics was evaluated for the purpose of developing a protocol to prevent the need for midnight sampling in modeling experiments. In Experiment 1, 16 isolates of Salmonella, 2 from the American Type Culture Collection (ATCC) and 14 from broiler operations, were surveyed for their growth kinetics in brain heart infusion (BHI) broth at 40°C. Lag time (P = 0.005) and growth rate (P = 0.022) were affected by identity of the isolate. Lag time ranged from 0.73 to 1.38 h, whereas growth rate ranged from 0.78 to 0.94 log10 CFU/ml/h. Overall, isolate S1 (Salmonella infantis from ATCC) was the fastest growing. In Experiment 2, 4 isolates of Salmonella, 1 from ATCC and 3 from broiler operations, were used to determine whether holding temperature influences subsequent growth kinetics. Salmonella isolates were grown to stationary phase at 37°C in BHI and then held for 24 h at 5, 22, or 37°C before dilution and reinitiation of growth in BHI at 37°C. Holding temperature did not alter or interact with identity of the isolate to alter subsequent growth kinetics. From the latter finding, a protocol was devised in which a dual-flask system is used to prevent the need for midnight sampling in modeling experiments. Similar to the results obtained in Experiment 1, identity of the isolate had only minor effects on growth kinetics in Experiment 2 indicating that all isolates examined were suitable for modeling experiments.

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