ResearchPad - bioenergetics https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Atco, a yeast mitochondrial complex of Atp9 and Cox6, is an assembly intermediate of the ATP synthase]]> https://www.researchpad.co/article/elastic_article_14724 Mitochondrial oxidative phosphorylation (oxphos) is the process by which the ATP synthase conserves the energy released during the oxidation of different nutrients as ATP. The yeast ATP synthase consists of three assembly modules, one of which is a ring consisting of 10 copies of the Atp9 subunit. We previously reported the existence in yeast mitochondria of high molecular weight complexes composed of mitochondrially encoded Atp9 and of Cox6, an imported structural subunit of cytochrome oxidase (COX). Pulse-chase experiments indicated a correlation between the loss of newly translated Atp9 complexed to Cox6 and an increase of newly formed Atp9 ring, but did not exclude the possibility of an alternate source of Atp9 for ring formation. Here we have extended studies on the functions and structure of this complex, referred to as Atco. We show that Atco is the exclusive source of Atp9 for the ATP synthase assembly. Pulse-chase experiments show that newly translated Atp9, present in Atco, is converted to a ring, which is incorporated into the ATP synthase with kinetics characteristic of a precursor-product relationship. Even though Atco does not contain the ring form of Atp9, cross-linking experiments indicate that it is oligomeric and that the inter-subunit interactions are similar to those of the bona fide ring. We propose that, by providing Atp9 for biogenesis of ATP synthase, Atco complexes free Cox6 for assembly of COX. This suggests that Atco complexes may play a role in coordinating assembly and maintaining proper stoichiometry of the two oxphos enzymes

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<![CDATA[The effect of TGFβ1 on thermogenic markers is dependent on the degree of adipocyte differentiation]]> https://www.researchpad.co/article/elastic_article_14662 Transforming growth factor β (TGFβ) a multifunctional cytokine is known to regulate cell proliferation, differentiation, migration and survival. Although there is variable expression of modulators of TGFβ action during differentiation, a differential effect on fat cell metabolism at the different stages of adipocyte differentiation was unclear. In the present study, 3T3L1 cells were used as an in vitro model to study the effect of TGFβ on adipogenic and thermogenic markers at various stages of preadipocyte to mature adipocyte differentiation. As in our earlier studies on the effect of TGFβ on CEBP’s, we used a standard differentiation mix, and one with the addition of rosiglitazone. RhTGFβ1 was added to undifferentiated adipocytes (preadipocytes) and to adipocytes at day 0 (commitment stage) as well as day 10 (terminal differentiation). Cellular responses in terms of Pref1, PPARγ, TLE3, PGC1α, PRDM16, UCP1 and UCP2 mRNA levels and selected protein products, were determined. Increases in PPARγ, PRDM16, UCP1 and UCP2 mRNA and decreases in Pref1 are good indicators of successful differentiation. The early addition of rhTGFβ1 during commitment stage decreased PPARγ, PRDM16, TLE3, UCP1 and UCP2 mRNA and decreased PRDM16 protein consistent with our earlier report on the inhibition of CEBP’s by TGFβ and CCN2. The addition of rhTGFβ1 to mature adipocyte at day 10 increased UCP1 mRNA and increased PRDM16 and UCP1 proteins. In the present study, our results suggest that TGFβ1 added late enhances the thermogenic potential of mature cells and causes 3T3L1 cells to differentiate to resemble brown or beige rather than white adipose tissue.

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<![CDATA[Monitoring of cardiovascular physiology augmented by a patient-specific biomechanical model during general anesthesia. A proof of concept study]]> https://www.researchpad.co/article/elastic_article_14629 During general anesthesia (GA), direct analysis of arterial pressure or aortic flow waveforms may be inconclusive in complex situations. Patient-specific biomechanical models, based on data obtained during GA and capable to perform fast simulations of cardiac cycles, have the potential to augment hemodynamic monitoring. Such models allow to simulate Pressure-Volume (PV) loops and estimate functional indicators of cardiovascular (CV) system, e.g. ventricular-arterial coupling (Vva), cardiac efficiency (CE) or myocardial contractility, evolving throughout GA. In this prospective observational study, we created patient-specific biomechanical models of heart and vasculature of a reduced geometric complexity for n = 45 patients undergoing GA, while using transthoracic echocardiography and aortic pressure and flow signals acquired in the beginning of GA (baseline condition). If intraoperative hypotension (IOH) appeared, diluted norepinephrine (NOR) was administered and the model readjusted according to the measured aortic pressure and flow signals. Such patients were a posteriori assigned into a so-called hypotensive group. The accuracy of simulated mean aortic pressure (MAP) and stroke volume (SV) at baseline were in accordance with the guidelines for the validation of new devices or reference measurement methods in all patients. After NOR administration in the hypotensive group, the percentage of concordance with 10% exclusion zone between measurement and simulation was >95% for both MAP and SV. The modeling results showed a decreased Vva (0.64±0.37 vs 0.88±0.43; p = 0.039) and an increased CE (0.8±0.1 vs 0.73±0.11; p = 0.042) in hypotensive vs normotensive patients. Furthermore, Vva increased by 92±101%, CE decreased by 13±11% (p < 0.001 for both) and contractility increased by 14±11% (p = 0.002) in the hypotensive group post-NOR administration. In this work we demonstrated the application of fast-running patient-specific biophysical models to estimate PV loops and functional indicators of CV system using clinical data available during GA. The work paves the way for model-augmented hemodynamic monitoring at operating theatres or intensive care units to enhance the information on patient-specific physiology.

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<![CDATA[Comparative mitochondrial genome analysis of <i>Dendrolimus houi</i> (Lepidoptera: Lasiocampidae) and phylogenetic relationship among Lasiocampidae species]]> https://www.researchpad.co/article/elastic_article_14575 Dendrolimus houi is one of the most common caterpillars infesting Gymnosperm trees, and widely distributed in several countries in Southeast Asia, and exists soley or coexists with several congeners and some Lasiocampidae species in various forest habitats. However, natural hybrids occasionally occur among some closely related species in the same habitat, and host preference, extreme climate stress, and geographic isolation probably lead to their uncertain taxonomic consensus. The mitochondrial DNA (mtDNA) of D. houi was extracted and sequenced by using high-throughput technology, and the mitogenome composition and characteristics were compared and analyzed of these species, then the phylogenetic relationship was constructed using the maximum likelihood method (ML) and the Bayesian method (BI) based on their 13 protein-coding genes (PCGs) dataset, which were combined and made available to download which were combined and made available to download among global Lasiocampidae species data. Mitogenome of D. houi was 15,373 bp in length, with 37 genes, including 13 PCGs, 22 tRNA genes (tRNAs) and 2 rRNA genes (rRNAs). The positions and sequences of genes were consistent with those of most known Lasiocampidae species. The nucleotide composition was highly A+T biased, accounting for ~80% of the whole mitogenome. All start codons of PCGs belonged to typical start codons ATN except for COI which used CGA, and most stop codons ended with standard TAA or TAG, while COI, COII, ND4 ended with incomplete T. Only tRNASer (AGN) lacked DHU arm, while the remainder formed a typical “clover-shaped” secondary structure. For Lasiocampidae species, their complete mitochondrial genomes ranged from 15,281 to 15,570 bp in length, and all first genes started from trnM in the same direction. And base composition was biased toward A and T. Finally, both two methods (ML and BI) separately revealed that the same phylogenetic relationship of D. spp. as ((((D. punctatus + D. tabulaeformis) + D. spectabilis) + D. superans) + (D. kikuchii of Hunan population + D. houi) as in previous research, but results were different in that D. kikuchii from a Yunnan population was included, indicating that different geographical populations of insects have differentiated. And the phylogenetic relationship among Lasiocampidae species was ((((Dendrolimus) + Kunugia) + Euthrix) + Trabala). This provides a better theoretical basis for Lasiocampidae evolution and classification for future research directions.

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<![CDATA[Mitochondrial genome sequence of <i>Phytophthora sansomeana</i> and comparative analysis of <i>Phytophthora</i> mitochondrial genomes]]> https://www.researchpad.co/article/elastic_article_14567 Phytophthora sansomeana infects soybean and causes root rot. It was recently separated from the species complex P. megasperma sensu lato. In this study, we sequenced and annotated its complete mitochondrial genome and compared it to that of nine other Phytophthora species. The genome was assembled into a circular molecule of 39,618 bp with a 22.03% G+C content. Forty-two protein coding genes, 25 tRNA genes and two rRNA genes were annotated in this genome. The protein coding genes include 14 genes in the respiratory complexes, four ATP synthase genes, 16 ribosomal proteins genes, a tatC translocase gene, six conserved ORFs and a unique orf402. The tRNA genes encode tRNAs for 19 amino acids. Comparison among mitochondrial genomes of 10 Phytophthora species revealed three inversions, each covering multiple genes. These genomes were conserved in gene content with few exceptions. A 3' truncated atp9 gene was found in P. nicotianae. All 10 Phytophthora species, as well as other oomycetes and stramenopiles, lacked tRNA genes for threonine in their mitochondria. Phylogenomic analysis using the mitochondrial genomes supported or enhanced previous findings of the phylogeny of Phytophthora spp.

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<![CDATA[The fast and the frugal: Divergent locomotory strategies drive limb lengthening in theropod dinosaurs]]> https://www.researchpad.co/article/elastic_article_14509 Limb length, cursoriality and speed have long been areas of significant interest in theropod paleobiology, since locomotory capacity, especially running ability, is critical in the pursuit of prey and to avoid becoming prey. The impact of allometry on running ability, and the limiting effect of large body size, are aspects that are traditionally overlooked. Since several different non-avian theropod lineages have each independently evolved body sizes greater than any known terrestrial carnivorous mammal, ~1000kg or more, the effect that such large mass has on movement ability and energetics is an area with significant implications for Mesozoic paleoecology. Here, using expansive datasets that incorporate several different metrics to estimate body size, limb length and running speed, we calculate the effects of allometry on running ability. We test traditional metrics used to evaluate cursoriality in non-avian theropods such as distal limb length, relative hindlimb length, and compare the energetic cost savings of relative hindlimb elongation between members of the Tyrannosauridae and more basal megacarnivores such as Allosauroidea or Ceratosauridae. We find that once the limiting effects of body size increase is incorporated there is no significant correlation to top speed between any of the commonly used metrics, including the newly suggested distal limb index (Tibia + Metatarsus/ Femur length). The data also shows a significant split between large and small bodied theropods in terms of maximizing running potential suggesting two distinct strategies for promoting limb elongation based on the organisms’ size. For small and medium sized theropods increased leg length seems to correlate with a desire to increase top speed while amongst larger taxa it corresponds more closely to energetic efficiency and reducing foraging costs. We also find, using 3D volumetric mass estimates, that the Tyrannosauridae show significant cost of transport savings compared to more basal clades, indicating reduced energy expenditures during foraging and likely reduced need for hunting forays. This suggests that amongst theropods, hindlimb evolution was not dictated by one particular strategy. Amongst smaller bodied taxa the competing pressures of being both a predator and a prey item dominant while larger ones, freed from predation pressure, seek to maximize foraging ability. We also discuss the implications both for interactions amongst specific clades and Mesozoic paleobiology and paleoecological reconstructions as a whole.

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<![CDATA[Genetic diversity of <i>Echinococcus multilocularis</i> and <i>Echinococcus granulosus sensu lato</i> in Kyrgyzstan: The A2 haplotype of <i>E</i>. <i>multilocularis</i> is the predominant variant infecting humans]]> https://www.researchpad.co/article/elastic_article_13871 Analysis of the genetic variability in Echinococcus species from different endemic countries have contributed to the knowledge in the taxonomy and phylogeography of these parasites. The most important species of this genus, Echinococcus granulosus sensu lato and Echinococcus multilocularis, co-exist in Kyrgyzstan causing serious public health issues. E. granulosus s.l. causes cystic echinococcosis and E. multilocularis is the causative agent of alveolar echinococcosis. The most relevant finding of our study is the identification of the cob/nad2/cox1 A2 haplotype of E. multilocularis as the most commonly found in humans and dogs. However, it remains unknown if this variant of E. multilocularis, based on genetic differences in mitochondrial genes, presents differences in virulence which could have contributed to the emergence of alveolar echinococcosis in Kyrgyzstan. The results also show a number of non-previously described genetic variants of E. multilocularis and E. granulosus s.s.

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<![CDATA[Betanin purification from red beetroots and evaluation of its anti-oxidant and anti-inflammatory activity on LPS-activated microglial cells]]> https://www.researchpad.co/article/elastic_article_13861 Microglial activation can release free radicals and various pro-inflammatory cytokines, which implicates the progress of a neurodegenerative disease. Therefore suppression of microglial activation can be an appropriate strategy for combating neurodegenerative diseases. Betanin is a red food dye that acts as free radical scavenger and can be a promising candidate for this purpose. In this study, purification of betanin from red beetroots was carried out by normal phase colum chromatography, yielding 500 mg of betanin from 100 g of red beetroot. The purified betanin was evaluated by TLC, UV-visible, HPLC, ESI-MASS, FT-IR spectroscopy. Investigation on the inhibitory effect of betanin on activated microglia was performed using primary microglial culture. The results showed that betanin significantly inhibited lipopolysaccharide induced microglial function including the production of nitric oxide free radicals, reactive oxygen species, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-1 beta (IL-1β). Moreover, betanin modulated mitochondrial membrane potential, lysosomal membrane permeabilization and adenosine triphosphate. We further investigated the interaction of betanin with TNF-α, IL-6 and Nitric oxide synthase (iNOS or NOS2) using in silico molecular docking analysis. The docking results demonstrated that betanin have significant negative binding energy against active sites of TNF-α, IL-6 and iNOS.

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<![CDATA[Inorganic polyphosphate is produced and hydrolyzed in F<sub>0</sub>F<sub>1</sub>-ATP synthase of mammalian mitochondria]]> https://www.researchpad.co/article/elastic_article_9196 Inorganic polyphosphate (polyP) is a polymer present in all living organisms. Although polyP is found to be involved in a variety of functions in cells of higher organisms, the enzyme responsible for polyP production and consumption has not yet been identified. Here, we studied the effect of polyP on mitochondrial respiration, oxidative phosphorylation and activity of F0F1-ATPsynthase. We have found that polyP activates mitochondrial respiration which does not coupled with ATP production (V2) but inhibits ADP-dependent respiration (V3). Moreover, PolyP can stimulate F0F1-ATPase activity in the presence of ATP and, importantly, can be hydrolyzed in this enzyme instead of ATP. Furthermore, PolyP can be produced in mitochondria in the presence of substrates for respiration and phosphate by the F0F1-ATPsynthase. Thus, polyP is an energy molecule in mammalian cells which can be produced and hydrolyzed in the mitochondrial F0F1-ATPsynthase.

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<![CDATA[Proteomic analysis of protein composition of rat hippocampus exposed to morphine for 10 days; comparison with animals after 20 days of morphine withdrawal]]> https://www.researchpad.co/article/N2838fdc6-dc33-429a-ba0d-e2e831e6a950

Opioid addiction is recognized as a chronic relapsing brain disease resulting from repeated exposure to opioid drugs. Cellular and molecular mechanisms underlying the ability of organism to return back to the physiological norm after cessation of drug supply are not fully understood. The aim of this work was to extend our previous studies of morphine-induced alteration of rat forebrain cortex protein composition to the hippocampus. Rats were exposed to morphine for 10 days and sacrificed 24 h (groups +M10 and −M10) or 20 days after the last dose of morphine (groups +M10/−M20 and −M10/−M20). The six altered proteins (≥2-fold) were identified in group (+M10) when compared with group (−M10) by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE). The number of differentially expressed proteins was increased to thirteen after 20 days of the drug withdrawal. Noticeably, the altered level of α-synuclein, β-synuclein, α-enolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was also determined in both (±M10) and (±M10/−M20) samples of hippocampus. Immunoblot analysis of 2D gels by specific antibodies oriented against α/β-synucleins and GAPDH confirmed the data obtained by 2D-DIGE analysis. Label-free quantification identified nineteen differentially expressed proteins in group (+M10) when compared with group (−M10). After 20 days of morphine withdrawal (±M10/−M20), the number of altered proteins was increased to twenty. We conclude that the morphine-induced alteration of protein composition in rat hippocampus after cessation of drug supply proceeds in a different manner when compared with the forebrain cortex. In forebrain cortex, the total number of altered proteins was decreased after 20 days without morphine, whilst in hippocampus, it was increased.

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<![CDATA[The draft mitochondrial genome of Magnolia biondii and mitochondrial phylogenomics of angiosperms]]> https://www.researchpad.co/article/N1f661d3e-d0c0-407e-92c0-bb72cd78029d

The mitochondrial genomes of flowering plants are well known for their large size, variable coding-gene set and fluid genome structure. The available mitochondrial genomes of the early angiosperms show extreme genetic diversity in genome size, structure, and sequences, such as rampant HGTs in Amborella mt genome, numerous repeated sequences in Nymphaea mt genome, and conserved gene evolution in Liriodendron mt genome. However, currently available early angiosperm mt genomes are still limited, hampering us from obtaining an overall picture of the mitogenomic evolution in angiosperms. Here we sequenced and assembled the draft mitochondrial genome of Magnolia biondii Pamp. from Magnoliaceae (magnoliids) using Oxford Nanopore sequencing technology. We recovered a single linear mitochondrial contig of 967,100 bp with an average read coverage of 122 × and a GC content of 46.6%. This draft mitochondrial genome contains a rich 64-gene set, similar to those of Liriodendron and Nymphaea, including 41 protein-coding genes, 20 tRNAs, and 3 rRNAs. Twenty cis-spliced and five trans-spliced introns break ten protein-coding genes in the Magnolia mt genome. Repeated sequences account for 27% of the draft genome, with 17 out of the 1,145 repeats showing recombination evidence. Although partially assembled, the approximately 1-Mb mt genome of Magnolia is still among the largest in angiosperms, which is possibly due to the expansion of repeated sequences, retention of ancestral mtDNAs, and the incorporation of nuclear genome sequences. Mitochondrial phylogenomic analysis of the concatenated datasets of 38 conserved protein-coding genes from 91 representatives of angiosperm species supports the sister relationship of magnoliids with monocots and eudicots, which is congruent with plastid evidence.

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<![CDATA[Crystal structure of a hemerythrin-like protein from Mycobacterium kansasii and homology model of the orthologous Rv2633c protein of M. tuberculosis]]> https://www.researchpad.co/article/N28feca53-fc53-4acd-851b-d8bcca9089ee

Pathogenic and opportunistic mycobacteria have a distinct class of non-heme di-iron hemerythrin-like proteins (HLPs). The first to be isolated was the Rv2633c protein, which plays a role in infection by Mycobacterium tuberculosis (Mtb), but could not be crystallized. This work presents the first crystal structure of an ortholog of Rv2633c, the mycobacterial HLP from Mycobacterium kansasii (Mka). This structure differs from those of hemerythrins and other known HLPs. It consists of five α-helices, whereas all other HLP domains have four. In contrast with other HLPs, the HLP domain is not fused to an additional protein domain. The residues ligating and surrounding the di-iron site are also unique among HLPs. Notably, a tyrosine occupies the position normally held by one of the histidine ligands in hemerythrin. This structure was used to construct a homology model of Rv2633c. The structure of five α-helices is conserved and the di-iron site ligands are identical in Rv2633c. Two residues near the ends of helices in the Mka HLP structure are replaced with prolines in the Rv2633c model. This may account for structural perturbations that decrease the solubility of Rv2633c relative to Mka HLP. Clusters of residues that differ in charge or polarity between Rv2633c and Mka HLP that point outward from the helical core could reflect a specificity for potential differential interactions with other protein partners in vivo, which are related to function. The Mka HLP exhibited weaker catalase activity than Rv2633c. Evidence was obtained for the interaction of Mka HLP irons with nitric oxide.

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<![CDATA[Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men: A secondary analysis of energy expenditure and physical activity]]> https://www.researchpad.co/article/N6924c77f-ef46-47bb-9a2b-08f320f77ea8

Background

A previously published pilot study assessed energy expenditure (EE) of participants with overweight and obesity after they were switched from a baseline high-carbohydrate diet (BD) to an isocaloric low-carbohydrate ketogenic diet (KD). EE measured using metabolic chambers increased transiently by what was considered a relatively small extent after the switch to the KD, whereas EE measured using doubly labeled water (EEDLW) increased to a greater degree after the response in the chambers had waned. Using a publicly available dataset, we examined the effect of housing conditions on the magnitude of the increase in EEDLW after the switch to the KD and the role of physical activity in that response.

Methods

The 14-day EEDLW measurement period included 4 days when subjects were confined to chambers instead of living in wards. To determine the effect on EEDLW only for the days subjects were living in the wards, we calculated non-chamber EE (EEnonchamber). To assess the role of physical activity in the response to the KD, we analyzed chamber and non-chamber accelerometer data for the BD and KD EEDLW measurement periods.

Results

In comparison with the increase in average 14-day EEDLW of 151 kcal/d ± 63 (P = 0.03) after the switch to the KD, EEnonchamber increased by 203 ± 89 kcal/d (P = 0.04) or 283 ± 116 kcal/d (P = 0.03) depending on the analytical approach. Hip accelerometer counts decreased significantly (P = 0.01) after the switch to the KD, whereas wrist and ankle accelerometer counts did not change.

Conclusions

Switching from the BD to the KD substantially increased EEDLW, but apparently only on days subjects were living in the ward outside the metabolic chamber. Increased physical activity as measured by accelerometry did not appear to account for this effect.

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<![CDATA[Mystery or method? Evaluating claims of increased energy expenditure during a ketogenic diet]]> https://www.researchpad.co/article/N1fb27919-9738-4fc6-9f1b-08c7be150010 ]]> <![CDATA[Evaluation of different b-values in DWI and 1H MRS for pancreatic cancer and pancreatitis: a rabbit model]]> https://www.researchpad.co/article/N47a20fb9-1348-40ef-aea0-8fd095b40a22

Abstract

Pancreatic cancer is a common malignant tumor with high incidence of metastasis. Currently, there is no absolute standard for the choice of b-value for diffusion-weighted imaging (DWI) for pancreatic cancer. The b-value is rarely reported in animal model study, especially in pancreatic cancer/mass pancreatitis rabbit models. The authors’ aim was to determine the different b-values to differentiate the diagnosis of pancreatic cancer and mass pancreatitis in rabbit models using DWI. When comparing the effect of different b-values in diagnostic process, the pathological results could be regarded as the gold standard. In this research, 30 healthy New Zealand rabbits were selected and divided into three groups by random number table method: group 1 (pancreatic cancer), group 2 (mass pancreatitis) and the control group (healthy). After DWI (three different b-values 333, 667, 1000 s/mm2, respectively) and MRI examination, the model rabbits were then killed. Afterward, the tumor mass was removed for biopsy, and occupation anatomy and tumor histopathology were examined. Fat-suppressing sequences of T2WI, DWI, ADC, difference of ADC (DADC), and MRS were used. The present study determined that the effective differential diagnosis of pancreatic cancer and pancreatitis was determined at low b-values (333 s/mm2) when performed DWI inspection in rabbit models.

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<![CDATA[Multifunctional neuron-specific enolase: its role in lung diseases]]> https://www.researchpad.co/article/N25ff34de-3419-4d52-8bd8-dfb21fa4f8e3

Abstract

Neuron-specific enolase (NSE), also known as gamma (γ) enolase or enolase-2 (Eno2), is a form of glycolytic enolase isozyme and is considered a multifunctional protein. NSE is mainly expressed in the cytoplasm of neurons and neuroendocrine cells, especially in those of the amine precursor uptake and decarboxylation (APUD) lineage such as pituitary, thyroid, pancreas, intestine and lung. In addition to its well-established glycolysis function in the cytoplasm, changes in cell localization and differential expression of NSE are also associated with several pathologies such as infection, inflammation, autoimmune diseases and cancer. This article mainly discusses the role and diagnostic potential of NSE in some lung diseases.

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<![CDATA[In vitro activity and mode of action of phenolic compounds on Leishmania donovani]]> https://www.researchpad.co/article/5c7d95f4d5eed0c48473501e

Background

Leishmaniasis is a disease caused by the protozoan parasite, Leishmania. The disease remains a global threat to public health requiring effective chemotherapy for control and treatment. In this study, the effect of some selected phenolic compounds on Leishmania donovani was investigated. The compounds were screened for their anti-leishmanial activities against promastigote and intracellular amastigote forms of Leishmania donovani.

Methodology/Principal findings

The dose dependent effect and cytotoxicity of the compounds were determined by the MTT assay. Flow cytometry was used to determine the effect of the compounds on the cell cycle. Parasite morphological analysis was done by microscopy and growth kinetic studies were conducted by culturing cells and counting at 24 hours intervals over 120 hours. The cellular levels of iron in promastigotes treated with compounds was determined by atomic absorption spectroscopy and the effect of compounds on the expression of iron dependent enzymes was investigated using RT-qPCR.

The IC50 of the compounds ranged from 16.34 μM to 198 μM compared to amphotericin B and deferoxamine controls. Rosmarinic acid and apigenin were the most effective against the promastigote and the intracellular amastigote forms. Selectivity indexes (SI) of rosmarinic acid and apigenin were 15.03 and 10.45 respectively for promastigotes while the SI of 12.70 and 5.21 respectively was obtained for intracellular amastigotes. Morphologically, 70% of rosmarinic acid treated promastigotes showed rounded morphology similar to the deferoxamine control. About 30% of cells treated with apigenin showed distorted cell membrane. Rosmarinic acid and apigenin induced cell arrest in the G0/G1 phase in promastigotes. Elevated intracellular iron levels were observed in promastigotes when parasites were treated with rosmarinic acid and this correlated with the level of expression of iron dependent genes.

Conclusions/Significance

The data suggests that rosmarinic acid exerts its anti-leishmanial effect via iron chelation resulting in variable morphological changes and cell cycle arrest.

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<![CDATA[Available energy fluxes drive a transition in the diversity, stability, and functional structure of microbial communities]]> https://www.researchpad.co/article/5c63393dd5eed0c484ae62f0

A fundamental goal of microbial ecology is to understand what determines the diversity, stability, and structure of microbial ecosystems. The microbial context poses special conceptual challenges because of the strong mutual influences between the microbes and their chemical environment through the consumption and production of metabolites. By analyzing a generalized consumer resource model that explicitly includes cross-feeding, stochastic colonization, and thermodynamics, we show that complex microbial communities generically exhibit a transition as a function of available energy fluxes from a “resource-limited” regime where community structure and stability is shaped by energetic and metabolic considerations to a diverse regime where the dominant force shaping microbial communities is the overlap between species’ consumption preferences. These two regimes have distinct species abundance patterns, different functional profiles, and respond differently to environmental perturbations. Our model reproduces large-scale ecological patterns observed across multiple experimental settings such as nestedness and differential beta diversity patterns along energy gradients. We discuss the experimental implications of our results and possible connections with disorder-induced phase transitions in statistical physics.

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<![CDATA[Match-play movement and metabolic power demands of elite youth, sub-elite and elite senior Australian footballers]]> https://www.researchpad.co/article/5c818e8dd5eed0c484cc250f

Aims

Currently minimal research has quantified physical requirement differences in match-play between youth and senior Australian football players. The aim of the current research was to describe and compare the movement profiles and energy cost of youth, sub-elite and elite senior Australian football match-play.

Methods

Fifty-seven Australian footballers playing in an elite senior 20, sub-elite senior 16 and elite youth competition 21 participated in this study. Distance, speed based indices and metabolic power measures recording via Global Positioning System (GPS) devices were compared across three competition tiers. Kicks and handballs were collected via a commercial statistics provider (Champion Data) and compared across the competition tiers.

Results

Youth players recorded less field time (elite: ES = 1.37/sub-elite: ES = 1.68), total distance (elite: ES = 1.64 /sub-elite: ES = 1.55) and high speed running (elite: ES = 0.90/sub-elite: ES = 0.26) compared to the elite and sub-elite players. The average energy cost of elite (ES = 2.19) and sub-elite (ES = 1.58) match-play was significantly higher that youth match-play.

Conclusions

A progressive increase regarding physical demands was evident across AF competition tiers. The findings suggest that sub-elite match-play can provide a viable pathway for youth players to develop physical capacity and technical skills before transitioning to elite senior match-play.

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<![CDATA[Targeted fluorescence lifetime probes reveal responsive organelle viscosity and membrane fluidity]]> https://www.researchpad.co/article/5c6f151fd5eed0c48467ae1c

The only way to visually observe cellular viscosity, which can greatly influence biological reactions and has been linked to several human diseases, is through viscosity imaging. Imaging cellular viscosity has allowed the mapping of viscosity in cells, and the next frontier is targeted viscosity imaging of organelles and their microenvironments. Here we present a fluorescent molecular rotor/FLIM framework to image both organellar viscosity and membrane fluidity, using a combination of chemical targeting and organelle extraction. For demonstration, we image matrix viscosity and membrane fluidity of mitochondria, which have been linked to human diseases, including Alzheimer’s Disease and Leigh’s syndrome. We find that both are highly dynamic and responsive to small environmental and physiological changes, even under non-pathological conditions. This shows that neither viscosity nor fluidity can be assumed to be fixed and underlines the need for single-cell, and now even single-organelle, imaging.

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