Aerobic Metabolism Research Articles

Influence of Dissolved Oxygen and Temperature on Nitrogen Transport and Reaction in Point Bars of River

Point bars are crucial elements of river systems, significantly enhancing the nitrogen cycle in riparian zones by facilitating hyporheic exchange between surface water and riparian zones. This study investigated the impact of dissolved oxygen (DO) concentration and temperature on nitrogen transport and reactions in river point bars. A two-dimensional coupled surface water–groundwater model was developed to analyze nitrogen distribution, variations, and reaction rates in rivers with point bars. The model considered three chemical reactions controlling nitrogen transformation: aerobic respiration, nitrification, and denitrification, with DO and temperature as independent variables. The results indicated that DO variations have a limited effect on solute migration depth, whereas increased temperature reduces solute migration depth. At surface water DO concentrations of 0.1, 0.2, and 0.4 mol/m3, nitrate removal in the riparian zone was 0.022, 0.0064, and 0.0019 mol/m, respectively. At riparian temperatures of 5 °C, 15 °C, and 25 °C, nitrate removal was 0.012, 0.041, and 0.16 mol/m, respectively. Nitrogen removal is more sensitive to temperature variations than to changes in DO concentration. In this research, the decrease in DO concentrations and the temperature increase greatly enhanced the riparian zone’s denitrification effect. This study improves our understanding of how riparian zones impact nitrogen cycling under various environmental conditions.

Differences in the physiology of Pichia pastoris grown on glycerol/glucose using polyurethane foam slabs as solid support

AbstractBACKGROUNDGrowth physiology and metabolic flux of Pichia pastoris were analyzed using glass columns containing slabs of polyurethane foam as a solid support and culture medium with glycerol or glucose as a carbon source.RESULTSMedia with glycerol produced an average of 30.91% more biomass than media where glucose was used. However, the specific growth rate registered higher values for media with glucose than those with glycerol at low substrate concentrations: 0.46 versus 0.22 h−1. Media with glycerol produced a large amount of d‐arabitol, whereas ethanol and citrate were the predominant metabolites in media with glucose. Both types of culture systems generated biphasic curves in terms of the respiratory quotient value, whose inflection point coincided with the transition from aerobic metabolism to a mixed one.CONCLUSIONAdequate oxygen transfer occurred in both culture systems; therefore, the differences found in growth physiology can be explained by the transport mechanism that internalizes glycerol, the access point to primary metabolism, and the degree of glycerol oxidation. The arrangement of cells in the polyurethane matrix allowed an attenuation of the repression phenomenon due to excess substrate for both carbon sources. This is the first work to study metabolic flux comparisons using this system. © 2024 Society of Chemical Industry (SCI).

Insights into the Role of VPS39 and Its Interaction with CP204L and A137R in ASFV Infection.

The African swine fever virus (ASFV) is a large and complex DNA virus that causes a highly lethal disease in swine, for which no antiviral drugs or vaccines are currently available. Studying viral-host protein-protein interactions advances our understanding of the molecular mechanisms underlying viral replication and pathogenesis and can facilitate the discovery of antiviral therapeutics. In this study, we employed affinity tagging and purification mass spectrometry to characterize the interactome of VPS39, an important cellular factor during the early phase of ASFV replication. The interaction network of VPS39 revealed associations with mitochondrial proteins involved in membrane contact sites formation and cellular respiration. We show that the ASFV proteins CP204L and A137R target VPS39 by interacting with its clathrin heavy-chain functional domain. Furthermore, we elaborate on the potential mechanisms by which VPS39 may contribute to ASFV replication and prioritize interactions for further investigation into mitochondrial protein function in the context of ASFV infection.

Dysfunctional cardiac energy transduction, mitochondrial oxidative stress, oncogenic and apoptotic signaling in DiNP-induced asthma in murine model.

Diisononyl phthalate (DiNP) has been associated with the development of allergies, asthma, and allergic airway inflammation. Through a complex interplay of signals and feedback mechanisms, the lungs communicate with the heart to ensure maintenance of homeostasis and supporting the body's metabolic demands. In the current study, we assessed the crosstalk between DiNP-induced asthma and cardiac cellular respiration, oxidative stress, apoptotic potential, and induction of oncogenic factors. Ten male BALB/c mice with a weight range of 20-30g were divided into two groups, each comprising five mice. Group 1 (control), was administered saline orally for a duration of 30days. In contrast, group 2 (DiNP group), received 50mg/kg of DiNP to induce asthma. After the final administration and asthma induction, the mice were euthanized, and their hearts were excised, processed, and subjected to biochemical analyses. The DiNP group had downregulated (P < 0.05) activities of the enzymes of glycolysis, tricyclic acid cycle, and electron transport chain except the hexokinase and succinate dehydrogenase activity which were upregulate relative to control. Also, oxidative distress markers (GSH, CAT, and MDA and SOD) were also perturbed. Biomarkers of inflammation (MPO and NO) were considerably higher (P < 0.05) in the heart of DiNP-induced asthma mice as compared with the control group. Furthermore, DiNP-induced asthma group has an increased cardiac caspase-3, Bax, c-Myc and K-ras, and p53 while the Bcl2 decreased when compared with control. Overall, the findings indicate that DiNP-induced asthma impairs cardiac functions by induction of key cardiac oncogenes, downregulation of cardiac energy, transduction of enzymes, and promotion of oxidative stress and cellular death.

There is no limitation for CO2 excretion across the lung in exercising American alligators (Alligator mississippiensis).

Vertebrates utilize various respiratory organs like gills, lungs, and skin in combination with diverse cardiovascular structures, including single, three, and four-chambered hearts, to enable oxygen delivery and carbon dioxide removal. They also exhibit differences in aerobic and anaerobic metabolism during exertion, but the cardiorespiratory gas transport of all vertebrates follow is a similar a four-step process governed by Fick's Principle and Fick's Law of Diffusion over the entire range of metabolic rates. Hillman et al. (2013) suggested that previous exercise studies have focused too narrowly on mammals and proposed that the cardiorespiratory system's excess capacity serves an evolutionary role in enhancing CO2 excretion in non-mammalian vertebrates. In contrast, an analysis by Hicks and Wang (2021) concluded that vertebrates maintain effective gas exchange even at peak activity, finding no evidence of arterial hypercapnia at maximal oxygen consumption and thus challenging the proposal of significant limitations to pulmonary or branchial CO2 efflux. In the present study, we investigate the limits for CO2 exchange in exercising American alligators (Alligator mississippiensis) and provide evidence that the cardiorespiratory system is adequately built to sustain CO2 excretion during strenuous exercise and maintain arterial PCO2 , with no evidence of diffusion limitation for pulmonary CO2 excretion.

Biochemical Pathways Delivering Distinct Glycosphingolipid Patterns in MDA-MB-231 and MCF-7 Breast Cancer Cells.

The complex structure of glycosphingolipids (GSLs) supports their important role in cell function as modulators of growth factor receptors and glutamine transporters in plasma membranes. The aberrant composition of clustered GSLs within signaling platforms, so-called lipid rafts, inevitably leads to tumorigenesis due to disturbed growth factor signal transduction and excessive uptake of glutamine and other molecules needed for increased energy and structural molecule cell supply. GSLs are also involved in plasma membrane processes such as cell adhesion, and their transition converts cells from epithelial to mesenchymal with features required for cell migration and metastasis. Glutamine activates the mechanistic target of rapamycin complex 1 (mTORC1), resulting in nucleotide synthesis and proliferation. In addition, glutamine contributes to the cancer stem cell GD2 ganglioside-positive phenotype in the triple-negative breast cancer cell line MDA-MB-231. Thieno[2,3-b]pyridine derivative possesses higher cytotoxicity against MDA-MB-231 than against MCF-7 cells and induces a shift to aerobic metabolism and a decrease in S(6)nLc4Cer GSL-positive cancer stem cells in the MDA-MB-231 cell line. In this review, we discuss findings in MDA-MB-231, MCF-7, and other breast cancer cell lines concerning their differences in growth factor receptors and recent knowledge of the main biochemical pathways delivering distinct glycosphingolipid patterns during tumorigenesis and therapy.

Gallium: a decisive "Trojan Horse" against microorganisms.

Controlling multidrug-resistant microorganisms (MRM) has a long history with the extensive and inappropriate use of antibiotics. At the cost of these drugs being scarce, new possibilities have to be explored to inhibit the growth of microorganisms. Thus, metallic compounds have shown to be promising as a viable alternative to contain pathogens resistant to conventional antimicrobials. Gallium (Ga3+) can be highlighted, which is an antimicrobial agent capable of disrupting the essential activities of microorganisms, such as metabolism, cellular respiration and DNA synthesis. It was observed that this occurs due to the similar properties between Ga3+ and iron (Fe3+), which is a fundamental ion for the correct functioning of bacterial activities. The mimetic effect performed by Ga3+ prevents iron transporters from distinguishing both ions and results in the substitution of Fe3+ for Ga3+ and in adverse metabolic disturbances in rapidly growing cells. This review focuses on analyzing the development of research involving Ga3+, elucidating the intracellular incorporation of the "Trojan Horse", summarizing the mechanism of interaction between gallium and iron and comparing the most recent and broad-spectrum studies using gallium-based compounds with antimicrobial scope.

Analysis of the Current State of Research on Bio-Healing Concrete (Bioconcrete).

The relatively small tensile strength of concrete makes this material particularly vulnerable to cracking. However, the reality is that it is not always possible and practically useful to conduct studies on high-quality sealing cracks due to their inaccessibility or small opening width. Despite the fact that currently there are many technologies for creating self-healing cement composites, one of the most popular is the technology for creating a biologically active self-healing mechanism for concrete. It is based on the process of carbonate ion production by cellular respiration or urease enzymes by bacteria, which results in the precipitation of calcium carbonate in concrete. This technology is environmentally friendly and promising from a scientific and practical point of view. This research focuses on the technology of creating autonomous self-healing concrete using a biological crack-healing mechanism. The research methodology consisted of four main stages, including an analysis of the already conducted global studies, ecological and economic analysis, the prospects and advantages of further studies, as well as a discussion and the conclusions. A total of 257 works from about 10 global databases were analyzed. An overview of the physical, mechanical and operational properties of bioconcrete and their changes is presented, depending on the type of active bacteria and the method of their introduction into the concrete mixture. An analysis of the influence of the automatic addition of various types of bacteria on various properties of self-healing bioconcrete is carried out, and an assessment of the influence of the method of adding bacteria to concrete on the process of crack healing is also given. A comparative analysis of various techniques for creating self-healing bioconcrete was performed from the point of view of technical progress, scientific potential, the methods of application of this technology, and their resulting advantages, considered as the factor impacting on strength and life cycle. The main conditions for a quantitative assessment of the sustainability and the possibility of the industrial implementation of the technology of self-healing bioconcrete are identified and presented. Various techniques aimed at improving the recovery process of such materials are considered. An assessment of the influence of the strength of cement mortar after adding bacteria to it is also given. Images obtained using electron microscopy methods are analyzed in relation to the life cycle of bacteria in mineral deposits of microbiological origin. Current gaps and future research prospects are discussed.

CALHM2 is a mitochondrial protein import channel that regulates fatty acid metabolism.

For mitochondrial metabolism to occur in the matrix, multiple proteins must be imported across the two (inner and outer) mitochondrial membranes. Classically, two protein import channels, TIM/TOM, are known to perform this function, but whether other protein import channels exist is not known. Here, using super-resolution microscopy, proteomics, and electrophysiological techniques, we identify CALHM2 as the import channel for the ECHA subunit of the mitochondrial trifunctional protein (mTFP), which catalyzes β-oxidation of fatty acids in the mitochondrial matrix. We find that CALHM2 sits specifically at the inner mitochondrial and cristae membranes and is critical for membrane morphology. Depletion of CALHM2 leads to a mislocalization of ECHA outside of the mitochondria leading to severe cellular metabolic defects. These defects include cytosolic accumulation of fatty acids, depletion of tricarboxylic acid cycle enzymes and intermediates, and reduced cellular respiration. Our data identify CALHM2 as an essential protein import channel that is critical for fatty acid- and glucose-dependent aerobic metabolism.

222 Validation of Brix for predicting sugar concentration of alfalfa and orchardgrass

Abstract The objective of this study was to evaluate the accuracy of Brix in predicting sugar concentrations in fresh alfalfa (Medicago sativa L.; ALF) and orchardgrass (Dactylis glomerata L.; OG) forages to be used as an inexpensive and rapid field-level assessment of relative energy in forages. In a 2-yr study, fresh forages samples from ALF and OG monoculture pastures in central Pennsylvania, U.S. were collected once monthly from May to September. Samples were immediately evaluated for Brix values with a hand-held digital refractometer, and the remaining biomass was frozen immediately with liquid N to halt cellular respiration. Samples were lyophilized and analyzed for individual sugars and wet chemistry nutritive analyses. Brix values were correlated with wet chemistry analyses using the PROC CORR procedure in SAS, with significance established at P &amp;lt; 0.05. Brix was positively correlated (P &amp;lt; 0.05) with total and individual sugars in ALF during late spring and late summer (0.49 to 0.93), but correlations were non-existent (P &amp;gt; 0.05) or negative (-0.55 to -0.73; P &amp;lt; 0.05) in mid-summer. Brix values had moderate to strong negative correlations (P &amp;lt; 0.05) to NDF and ADF in ALF (-0.57 to -0.71). Conversely, Brix values did not correlate (P &amp;gt; 0.05) to any notable sugar parameters in OG beyond the first sampling date (0.60 to 0.74; P &amp;lt; 0.05). Brix was not correlated (P &amp;gt; 0.05) to NDF and ADF in OG. In summary, Brix values did not consistently predict sugar concentrations in fresh ALF and OG forages. Because Brix measures dissolved solids in solution (not just sugars), Brix readings collected from crushed ALF or OG samples may be confounded by fibrous fractions found in the solution as well as decreased sugar concentrations compared with fruit crops. Brix accuracy may also be dependent on seasonal temperature patterns, plant growth stage, and daily weather patterns. Other solutions should be investigated that rapidly assess sugar profiles and nutritive values of fresh forages.

Recent Progress of Electrospun Nanofiber Dressing in the Promotion of Wound Healing.

The nanofiber materials of three-dimensional spatial structure synthesized by electrospun have the characteristics of high porosity, high specific surface area, and high similarity to the natural extracellular matrix (ECM) of the human body. These are beneficial for absorbing wound exudate, effectively blocking the invasion of external bacteria, and promoting cell respiration and proliferation, which provides an ideal microenvironment for wound healing. Moreover, electrospun nanofiber dressings can flexibly load drugs according to the condition of the wound, further promoting wound healing. Recently, electrospun nanofiber materials have shown promising application prospects as medical dressings in clinical. Based on current research, this article reviewed the development history of wound dressings and the principles of electrospun technology. Subsequently, based on the types of base material, polymer-based electrospun nanofiber dressing and electrospun nanofiber dressing containing drug-releasing factors were discussed. Furthermore, the application of electrospun nanofiber dressing on skin tissue is highlighted. This review aims to provide a detailed overview of the current research on electrospun nanomaterials for wound healing, addressing challenges and suggesting future research directions to advance the field of electrospun dressings in wound healing.

Identification of the organic peroxide scavenging system of Yersinia pseudotuberculosis and its regulation by OxyR.

Oxidative stress caused by reactive oxygen species (ROS) is inevitable for all aerobic microorganisms as ROS are the byproducts of aerobic respiration. For gut pathogens, ROS are an integrated part of colonization resistance which protects the host against bacteria invasion. Alkyl hydroperoxide reductase (AhpR) and organic hydroperoxide resistance (Ohr) proteins are considered as the main enzymes responsible for the degradation of organic peroxides (OPs) in most bacteria. To elucidate how enteric pathogen Yersinia pseudotuberculosis YPIII deals with oxidative stress induced by OPs, we performed transcriptomic analysis and identified the OP scavenging system, which is composed of glutathione peroxidase (Gpx), thiol peroxidase (Tpx), and AhpR. Gpx serves as the main scavenger of OPs, and Tpx assists in the degradation of OPs. Transcriptional factor OxyR regulates Gpx expression, suggesting that OxyR is the regulator mediating the cellular response to OPs. Although AhpR has little influence on OP degradation, its deletion would greatly impair the scavenging ability of OPs in the absence of gpx or tpx. In addition, we found that catalase KatG and KatE are responsive to OPs but do not participate in the removal of OPs.IMPORTANCEIn bacteria, oxidative stress caused by ROS is a continuously occurring cellular response and requires multiple genes to participate in this process. The elimination of OPs is mainly dependent on AhpR and Ohr protein. Here, we carried out transcriptomic analysis to search for enzymes responsible for the removal of organic peroxides in Yersinia pseudotuberculosis. We found that Gpx was the primary OP scavenger in bacteria, which was positively regulated by the oxidative stress regulator OxyR. The OP scavenging system in Y. pseudotuberculosis was composedof Gpx, Tpx, and AhpR. OxyR is the critical global regulator mediating gene expression involved in OPs and H2O2 stress. These findings suggest that Y. pseudotuberculosis has a unique defense system in response to oxidative stress.

JR-AB2-011 induces fast metabolic changes independent of mTOR complex 2 inhibition in human leukemia cells.

The mechanistic target of rapamycin (mTOR) is a crucial regulator of cell metabolic activity. It forms part of several distinct protein complexes, particularly mTORC1 and mTORC2. The lack of specific inhibitors still hampers the attribution of mTOR functions to these complexes. JR-AB2-011 has been reported as a specific mTORC2 inhibitor preventing mTOR binding to RICTOR, a unique component of mTORC2. We aimed to describe the effects of JR-AB2-011 in leukemia/lymphoma cells, where the mTOR pathway is often aberrantly activated. The impact of JR-AB2-011 on leukemia/lymphoma cell metabolism was analyzed using the Seahorse platform. AKT phosphorylation at Ser473 was used as a marker of mTORC2 activity. mTOR binding to RICTOR was assessed by co-immunoprecipitation. RICTOR-null cells were derived from the Karpas-299 cell line using CRISPR/Cas9 gene editing. In leukemia/lymphoma cell lines, JR-AB2-011 induced a rapid drop in the cell respiration rate, which was variably compensated by an increased glycolytic rate. In contrast, an increase in the respiration rate due to JR-AB2-011 treatment was observed in primary leukemia cells. Unexpectedly, JR-AB2-011 did not affect AKT Ser473 phosphorylation. In addition, mTOR did not dissociate from RICTOR in cells treated with JR-AB2-011 under the experimental conditions used in this study. The effect of JR-AB2-011 on cell respiration was retained in RICTOR-null cells. JR-AB2-011 affects leukemia/lymphoma cell metabolism via a mechanism independent of mTORC2.

Life in the margins: the effect of immersion/emersion and tidal cycle on the North Atlantic limpet Patella vulgata protein synthesis rates.

Biological processes in intertidal species follow tidal rhythms that enhance survival and fitness. Whereas tidal effects on behaviour and metabolic rates have been widely studied, impacts on other key process such as protein synthesis are still poorly understood. To date, no studies have examined the effect of immersion/emersion and tidal cycles on protein synthesis rates (ks). Patella vulgata is an intertidal limpet present in North-Eastern Atlantic rocky shores from high to low shore. Previously reported P. vulgata respiration and heart rate measurements suggest aerobic metabolism is maintained during emersion and growth rates increase from high to low shore, but whether these patterns are reflected in ks is currently unclear. Here, we measured for the first time in any intertidal organism, ks, RNA to protein ratios and RNA translational efficiency (kRNA) in P. vulgata over a full tidal cycle, at three different shore heights. ks increased during emersion (p < 0.001) and was significantly higher in low shore animals compared to the other shore heights (p < 0.001), additionally ks was negatively correlated to body mass (p = 0.002). RNA to protein ratios remained unchanged over the tidal cycle (p = 0.659) and did not vary with shore height (p = 0.591). kRNA was significantly higher during emersion and was also higher in low shore limpets (p < 0.001). This study demonstrates that P. vulgata increases ks during emersion, an important adaptation in a species that spends a considerable amount of its lifecycle emersed. Intertidal species are highly exposed to increasing air temperatures, making knowledge of physiological responses during emersion critical in understanding and forecasting climate warming impacts.

Potential Signal Pathways and Therapeutic Effects of Mesenchymal Stem Cell on Oxidative Stress in Diseases.

Oxidative stress is a biological stress response produced by the destruction of redox equilibrium in aerobic metabolism in organisms, which is closely related to the occurrence of many diseases. Mesenchymal stem cells (MSCs) have been found to improve oxidative stress injury in a variety of diseases, including arthritis, chronic obstructive pulmonary disease, asthma, multiple sclerosis, focal segmental glomerulosclerosis, diabetic nephropathy, ischemia-reperfusion injury, hepatic fibrosis, myocardial infarction, diabetes, inflammatory bowel disease, etc. The antioxidant stress capacity of MSCs may be a breakthrough in the treatment of these diseases. This review found that MSCs have the ability to resist oxidative stress, which may be achieved through MSCs involvement in mediating the Nrf2, MAPK, NF-κB, AMPK, PI3K/AKT and Wnt/b-catenin signaling pathways.

Cardioprotective effect of Vitamin D on cardiac hypertrophy through improvement of mitophagy and apoptosis in an experimental rat model of levothyroxine -induced hyperthyroidism.

Mitochondria are known to be involved in mediating the calorigenic effects of thyroid hormones. With an abundance of these hormones, alterations in energy metabolism and cellular respiration take place, leading to the development of cardiac hypertrophy. Vitamin D has recently gained attention due to its involvement in the regulation of mitochondrial function, demonstrating promising potential in preserving the integrity and functionality of the mitochondrial network. The present study aimed to investigate the therapeutic potential of Vitamin D on cardiac hypertrophy induced by hyperthyroidism, with a focus on the contributions of mitophagy and apoptosis as possible underlying molecular mechanisms. The rats were divided into three groups: control; hyperthyroid; hyperthyroid + Vitamin D. Hyperthyroidism was induced by Levothyroxine administration for four weeks. Serum thyroid hormones levels, myocardial damage markers, cardiac hypertrophy indices, and histological examination were assessed. The assessment of Malondialdehyde (MDA) levels and the expression of the related genes were conducted using heart tissue samples. Vitamin D pretreatment exhibited a significant improvement in the hyperthyroidism-induced decline in markers indicative of myocardial damage, oxidative stress, and indices of cardiac hypertrophy. Vitamin D pretreatment also improved the downregulation observed in myocardial expression levels of genes involved in the regulation of mitophagy and apoptosis, including PTEN putative kinase 1 (PINK1), Mitofusin-2 (MFN2), Dynamin-related Protein 1 (DRP1), and B cell lymphoma-2 (Bcl-2), induced by hyperthyroidism. These results suggest that supplementation with Vitamin D could be advantageous in preventing the progression of cardiac hypertrophy and myocardial damage.

The Effects of L-Citrulline and Malic Acid on Substrate Utilisation and Lactate Elimination

Endurance athletes often aim to improve their aerobic metabolism. The aim of this pilot study was to examine if malic acid and L-citrulline supplementation can improve aerobic metabolism and lactate elimination. Nine young (23.9 ± 1.9 years) recreational male athletes participated in this study. Following a standardised breakfast and a body composition analysis (InBody720), 6000 mg of citrulline and 3000 mg of malic acid or a placebo of 300 mL of water were consumed on three separate days in a cross-over design using a double-blind method. Sixty minutes after the supplementation, participants completed a ramp bicycle spiroergometer protocol (35 W/3 min) until reaching a respiratory exchange ratio (RER) of 1.1, followed by a 9 min active recovery. Cadence, heart rate (HR), rate of perceived exertion (RPE), respiratory parameters and lactate levels were registered. The RPExHR value was calculated to accurately characterise exhaustion. During the exercise protocol, citrulline supplementation induced significantly lower RER values at 70-105-140 W compared to malic acid and the placebo, respectively. There was no difference in lactate levels neither during rest nor at RER 1.1. RPExHR rate values were significantly lower after malic acid supplementation compared to placebo at 175 and 210 W. Power at RER 1.1 was higher after malic acid (+4 W) and citrulline (+5 W) supplementation. Although the supplementation failed to decrease lactate levels, lower RER and RPE values may indicate a performance-enhancing benefit.

The Archetypal Gamma-Core Motif of Antimicrobial Cys-Rich Peptides Inhibits H+-ATPases in Target Pathogens.

Human lactoferrin (hLf) is an innate host defense protein that inhibits microbial H+-ATPases. This protein includes an ancestral structural motif (i.e., γ-core motif) intimately associated with the antimicrobial activity of many natural Cys-rich peptides. Peptides containing a complete γ-core motif from hLf or other phylogenetically diverse antimicrobial peptides (i.e., afnA, SolyC, PA1b, PvD1, thanatin) showed microbicidal activity with similar features to those previously reported for hLf and defensins. Common mechanistic characteristics included (1) cell death independent of plasma membrane (PM) lysis, (2) loss of intracellular K+ (mediated by Tok1p K+ channels in yeast), (3) inhibition of microbicidal activity by high extracellular K+, (4) influence of cellular respiration on microbicidal activity, (5) involvement of mitochondrial ATP synthase in yeast cell death processes, and (6) increment of intracellular ATP. Similar features were also observed with the BM2 peptide, a fungal PM H+-ATPase inhibitor. Collectively, these findings suggest host defense peptides containing a homologous γ-core motif inhibit PM H+-ATPases. Based on this discovery, we propose that the γ-core motif is an archetypal effector involved in the inhibition of PM H+-ATPases across kingdoms of life and contributes to the in vitro microbicidal activity of Cys-rich antimicrobial peptides.

AMPK-mediated regulation of cardiac energy metabolism: Implications for thermotolerance in Argopecten irradians irradians

AMPK is a key regulator of metabolism in eukaryotes across various pathways related to energy regulation. Although extensive investigations of AMPK have been conducted in mammals and some model organisms, research on AMPK in scallops is comparatively limited. In this study, three AMPK family genes (AiAMPKα, AiAMPKβ and AiAMPKγ) in scallop Argopecten irradians irradians were identified through genome scanning. Structure prediction and phylogenetic analyses of AiAMPKs were performed to determine their structural features and evolutionary relationships. Spatiotemporal expression patterns of AiAMPKs at different developmental stages and in healthy adult tissues were analyzed to elucidate the function of AiAMPKs in bay scallops’ growth and development. The spatiotemporally specific expression of AiAMPKs implied their important roles in growth and development of bay scallops. Heat stress experiment was performed to determine the regulations of AiAMPKs in four kinds of thermosensitive tissues. Expression profiles revealed distinct molecular mechanisms of AiAMPKs in different tissues in response to heat stress: significant down-regulations in mobile hemocytes, but dominant up-regulations occurring in stationary gills, mantles and hearts. Functional verification including knock-down of AiAMPKα and inhibition of AiAMPK was separately conducted in the thermotolerant tissue heart at the post-transcription and translation levels. The thermotolerant index Arrhenius break temperature (ABT) showed a significant decrease and the rate-amplitude product (RAP) peaked earlier in the individuals after RNAi targeting AiAMPKα, displaying an earlier transition to anaerobic metabolism under heat stress, indicating an impairing ability of aerobic metabolism. After AiAMPK inhibition, widespread down-regulations of genes in key energy metabolism pathways, RNA polymerase II-mediated transcription, and aminoacyl-tRNA synthesis pathways were obviously observed, revealing the post-translational inhibition of AiAMPK hindered cardiac energy metabolism, basal transcription and translation. Overall, our findings provide evidences for exploring the molecular mechanisms of energy regulation in thermotolerant traits in bay scallops under ongoing global warming.

Recent progress of methods for cuproptosis detection.

Varying from other identified cell death pathways, cuproptosis is a new type of regulated cell death characterized by excess Cu ions, abnormal aggregation of lipoylated proteins in TCA cycle, loss of Fe-S cluster proteins, upregulation of HSP70, leading to proteotoxic and oxidative stress. Cuproptosis is highly concerned by scientific community and as the field of cuproptosis further develops, remarkable progress has been made in the verification and mechanism of cuproptosis, and methods used to detect cuproptosis have been continuously improved. According to the characteristic changes of cuproptosis, techniques based on cell death verification, Cu content, morphology, molecular biology of protein levels of cuproptosis-related molecules and biochemical pathways of cuproptosis-related enzyme activity and metabolites of oxidative stress, lipoic acid, TCA cycle, Fe-S cluster proteins, oxidative phosphorylation, cell respiration intensity have been subject to cuproptosis verification and research. In order to further deepen the understanding of detecting cuproptosis, the principle and application of common cuproptosis detection methods are reviewed and categorized in cellular phenomena and molecular mechanism in terms of cell death, Cu content, morphology, molecular biology, biochemical pathways with a flow chart. All the indicating results have been displayed in response to the markers of cuproptosis, their advantages and limitations are summaried, and comparison of cuproptosis and ferroptosis detection is performed in this study. Our collection of methods for cuproptosis detection will provide a great basis for cuproptosis verification and research in the future.