Internal Homeostasis Research Articles

Taste triggers a homeostatic temperature control in hungry flies.

Hungry animals consistently show a desire to obtain food. Even a brief sensory detection of food can trigger bursts of physiological and behavioral changes. However, the underlying mechanisms by which the sensation of food triggers the acute behavioral response remain elusive. We have previously shown in Drosophila that hunger drives a preference for low temperature. Because Drosophila is a small ectotherm, a preference for low temperature implies a low body temperature and a low metabolic rate. Here, we show that taste-sensing triggers a switch from a low to a high temperature preference in hungry flies. We show that taste stimulation by artificial sweeteners or optogenetics triggers an acute warm preference, but is not sufficient to reach the fed state. Instead, nutrient intake is required to reach the fed state. The data suggest that starvation recovery is controlled by two components: taste-evoked and nutrient-induced warm preferences, and that taste and nutrient quality play distinct roles in starvation recovery. Animals are motivated to eat based on time of day or hunger. We found that clock genes and hunger signals profoundly control the taste-evoked warm preferences. Thus, our data suggest that the taste-evoked response is one of the critical layers of regulatory mechanisms representing internal energy homeostasis and metabolism.

Taste triggers a homeostatic temperature control in hungry flies

Hungry animals consistently show a desire to obtain food. Even a brief sensory detection of food can trigger bursts of physiological and behavioral changes. However, the underlying mechanisms by which the sensation of food triggers the acute behavioral response remain elusive. We have previously shown in Drosophila that hunger drives a preference for low temperature. Because Drosophila is a small ectotherm, a preference for low temperature implies a low body temperature and a low metabolic rate. Here, we show that taste-sensing triggers a switch from a low to a high temperature preference in hungry flies. We show that taste stimulation by artificial sweeteners or optogenetics triggers an acute warm preference, but is not sufficient to reach the fed state. Instead, nutrient intake is required to reach the fed state. The data suggest that starvation recovery is controlled by two components: taste-evoked and nutrient-induced warm preferences, and that taste and nutrient quality play distinct roles in starvation recovery. Animals are motivated to eat based on time of day or hunger. We found that clock genes and hunger signals profoundly control the taste-evoked warm preferences. Thus, our data suggest that the taste-evoked response is one of the critical layers of regulatory mechanisms representing internal energy homeostasis and metabolism.

Effect of Oat Hay as a Substitute for Alfalfa Hay on the Gut Microbiome and Metabolites of Yak Calves.

To evaluate the impact of different roughages on the intestinal microbiota of yak calves, we fed them oat hay in substitution of alfalfa hay, in addition to milk replacer and starter powder. Twenty-one 45-day-old male yak calves were selected and randomly assigned to three groups: the milk replacer + starter + alfalfa hay group (AH), the milk replacer + starter + oat hay group (OH), and the milk replacer + starter + mixed hay group (AO), in which the alfalfa hay and oat hay were administered in a 1:1 ratio. All calves in the three groups were fed the same milk replacer and an equivalent amount of dry matter. The formal experiment commenced after a 21-day pre-test period and lasted for 120 days. Following the experiment, the contents of the jejunum and colon were collected to investigate the intestinal microbiota and metabolites using 16S rRNA sequencing and LC-MS metabolomics. The result showed that the AO group had greater final body weights overall than the AH group and OH group (p < 0.05). The AH group and OH group had considerably greater feed-to-gain ratios than the AO group (p < 0.05). At the phylum level, the OH group exhibited an increased relative abundance of Bacteroidota and Spirochaetota in the jejunum (p < 0.05). The relative abundance of Actinobacteriota in the colon was increased in the AO group (p < 0.05). At the genus level, the AO group exhibited a decreased abundance of Clostridium sensu_stricto_1 (p < 0.05), and the OH group showed an increased abundance UCG-005 and Alistipes in the jejunum. There were many differential metabolites in the OH group and AO group compared to the AH group, and the different metabolites of the OH group were associated with the metabolic pathways of the nervous system, sensory system, amino acid metabolism, and lipid metabolism in the jejunum and with lipid metabolism, amino acid metabolism, and the nervous system in the colon. In the AO group, these metabolites were associated with the digestive system and the translation and metabolism of cofactors in the jejunum and with the metabolism of cofactors and vitamins in the colon. In summary, it is feasible to replace alfalfa hay with oat hay based on milk replacer and starter. The combination of the two forages enhanced nutrient absorption, improved immune function, maintained the internal homeostasis of yak calves, and was more beneficial to their growth and development.

Association of Stress Defense System With Fine Particulate Matter Exposure: Mechanism Analysis and Application Prospects.

The association between the stress defense system and exposure to fine particulate matter (PM2.5) is a hot topic in the field of environmental health. PM2.5 pollution is an increasingly serious issue, and its impact on health cannot be ignored. The stress defense system is an important biological mechanism for maintaining cell and internal environment homeostasis, playing a crucial role in PM2.5-induced damage and diseases. The association between PM2.5 exposure and activation of the stress defense system has been reported. Moderate PM2.5 exposure rapidly mobilizes the stress defense system, while excessive PM2.5 exposure may exceed its compensatory and coping abilities, resulting in system imbalance and dysfunction that triggers pathological changes in cells and tissues, thereby increasing the risk of chronic diseases, such as respiratory diseases, cardiovascular diseases, and cancer. This detailed review focuses on the composition, function, and regulatory mechanisms of the antioxidant defense system, autophagy system, ubiquitin-proteasome system, and inflammatory response system, which are all components of the stress defiance system. In particular, the influence of PM2.5 exposure on each of these defense systems and their roles in responding to PM2.5-induced damage was investigated to provide an in-depth understanding of the pathogenesis of PM2.5 exposure, accurately assess potential hazards, and formulate prevention and intervention strategies for health damage caused by PM2.5 exposure.

Integration of mRNA and miRNA Analysis Sheds New Light on the Muscle Response to Heat Stress in Spotted Sea Bass (Lateolabrax maculatus).

Temperature is a crucial environmental factor for fish. Elevated temperatures trigger various physiological and molecular responses designed to maintain internal environmental homeostasis and ensure the proper functioning of the organism. In this study, we measured biochemical parameters and performed mRNA-miRNA integrated transcriptomic analysis to characterize changes in gene expression profiles in the muscle tissue of spotted sea bass (Lateolabrax maculatus) under heat stress. The measurement of biochemical parameters revealed that the activities of nine biochemical enzymes (ALP, γ-GT, AST, GLU, CK, ALT, TG, LDH and TC) were significantly affected to varying degrees by elevated temperatures. A total of 1940 overlapping differentially expressed genes (DEGs) were identified among the five comparisons in the muscle tissue after heat stress. Protein-protein interaction (PPI) analysis of DEGs indicated that heat shock protein genes (HSPs) were deeply involved in the response to heat stress. In addition, we detected 462 differential alternative splicing (DAS) events and 618 DAS genes, which are closely associated with sarcomere assembly in muscle, highlighting the role of alternative splicing in thermal response regulation. Moreover, 32 differentially expressed miRNAs (DEMs) were identified in response to heat stress, and 599 DEGs were predicted as potential target genes of those DEMs, generating 846 DEG-DEM negative regulatory pairs potentially associated with thermal response. Function enrichment analysis of the target genes suggested that lipid metabolism-related pathways and genes were regulated by miRNAs. By analyzing PPIs of target genes, we identified 28 key negative regulatory pairs, including 13 miRNAs (such as lma-miR-122, lma-miR-200b-5p and novel-miR-444) and 15 target genes (such as hspa13, dnaja1, and dnajb1a). This study elucidates the molecular mechanisms of response to high-temperature stress and offers valuable information for the selection and breeding of heat-tolerant strains of spotted sea bass.

Biomimetics through bioconjugation of 16-methylheptadecanoic acid to damaged hair for hair barrier recovery

The primary component of the lipid barrier on human hair, which is essential for defense against aging and environmental stresses, is 18-methyleicosanoic acid (18-MEA), which provides hydrophobic properties and protective benefits. Since 18-MEA cannot be regenerated once damaged, developing technology that can permanently bind alternative materials to hair is critical. Once 18-MEA was removed from hair via X-ray photoelectron spectroscopy (XPS), pentaerythritol tetraisoosterate (PTIS) was hydrolyzed and observed via gas chromatography/mass spectrometry (GC/MS) to confirm that it mimicked 18-MEA, and 16-methylheptadecanoic acid (16-MHA) was obtained at pH 4 or lower. 16-MHA was bioconjugated to damaged hair from which 18-MEA was removed via a carbodiimide reaction using polycarbodiimide. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed that 16-MHA remained on the surface of the bioconjugated hair even after washing. Observation of the endothermic reaction of moisture in hair via a differential scanning calorimetry (DSC) and evaluation of the moisture content confirmed that the physical properties of hair enriched with 16-MHA were similar to those of virgin hair. This biomimetic approach has been shown to restore both external structural integrity and internal moisture homeostasis.

Growth and biochemical composition of green seaweed Chaetomorpha linum (O.F. Müller) Kützing (1845) cultured in a range of ionic profiles

Seaweed aquaculture in Inland Saline Water (ISW) can utilise degraded land to produce valuable products. ISW is characterized by its different ionic profile to ocean water (OW), particularly the ratios of sodium (Na+) to potassium (K+) ions, and magnesium (Mg2+) to calcium (Ca2+) ions. The feasibility of seaweed cultivation in varying ionic profiles is not yet well understood. This study investigates the growth of Chaetomorpha linum by length (SL) and biomass (TB), cultured in several ionic profiles by mixture of ISW with OW over two 15 day experiments. The first experiment (EXP 1) investigated growth across a broad range of ionic profiles. C. linum was then cultivated across a more specific range of profiles in the second experiment (EXP 2), based on EXP 1 results. Tanks (50 L) were randomly organised outdoors and salinity was maintained at approximately 25 ppt. SL and TB of seaweed was recorded every 3 days. The proximate and mineral composition of harvested seaweed on Day 15 was also analysed. A significant negative correlation (p < 0.001, r = −0.835, n = 13) was observed between non-discrete TB specific growth rate (SGR) and increasing K+ of media in EXP 1. A significant positive correlation (p < 0.001, r = 0.769, n = 28, EXP 1) was observed between potassium (K) in dry matter (mg.g−1) and K+ in media, suggesting lower K+ in media causes increased TB due to higher water flow rate into cells. Calcium (Ca) content (% d.b.) was much higher in K+ deficient media, indicating Ca accumulation occurs in cells during ion homeostasis when K is not available. Positive SL SGR's across ionic profiles also indicate this species is capable of a high level of internal ion regulation. This study provides context for commercial cultivation of C. linum in varying water types, and presents an avenue for salinity-affected dryland farmers to diversify their income through ISW aquaculture.

The ovarian cancer-associated microbiome contributes to the tumor's inflammatory microenvironment.

A growing body of research has established a correlation between tumors and persistent chronic inflammatory infiltration. As a primary instigator of inflammation, the majority of microbiomes naturally residing within our bodies engage in a mutually beneficial symbiotic relationship. Nevertheless, alterations in the microbiome's composition or breaches in the normal barrier function can disrupt the internal environment's homeostasis, potentially leading to the development and progression of various diseases, including tumors. The investigation of tumor-related microbiomes has contributed to a deeper understanding of their role in tumorigenesis. This review offers a comprehensive overview of the microbiome alterations and the associated inflammatory changes in ovarian cancer. It may aid in advancing research to elucidate the mechanisms underlying the ovarian cancer-associated microbiome, providing potential theoretical support for the future development of microbiome-targeted antitumor therapies and early screening through convenient methods.

Homeostatic regulation of brain activity: from endogenous mechanisms to homeostatic nanomachines.

After the initial concepts of the constancy of the internal milieu or homeostasis, put forward by Claude Bernard and Walter Cannon, homeostasis emerged as a mechanism to control oscillations of biologically meaningful variables within narrow physiological ranges. This is a primary need in the central nervous system that is continuously subjected to a multitude of stimuli from the internal and external environments that affect its function and structure, allowing to adapt the individual to the ever-changing daily conditions. Preserving physiological levels of activity despite disturbances that could either depress neural computation or excessively stimulate neural activity is fundamental, and failure of these homeostatic mechanisms can lead to brain diseases. In this review, we cover the role and main mechanisms of homeostatic plasticity involving the regulation of excitability and synaptic strength from the single neuron to the network level. We analyze the relationships between homeostatic and Hebbian plasticity and the conditions under which the preservation of the excitatory/inhibitory balance fails, triggering epileptogenesis and eventually epilepsy. Several therapeutic strategies to cure epilepsy have been designed to strengthen homeostasis when endogenous homeostatic plasticity mechanisms have become insufficient or ineffective to contrast hyperactivity. We describe "on demand" gene therapy strategies, including optogenetics, chemogenetics, and chemo-optogenetics, and particularly focus on new closed loop sensor-actuator strategies mimicking homeostatic plasticity that can be endogenously expressed to strengthen the homeostatic defenses against brain diseases.

Modulatory Effects of Regulated Cell Death: An Innovative Preventive Approach for the Control of Mastitis.

Mastitis is a common disease worldwide that affects the development of the dairy industry due to its high incidence and complex etiology. Precise regulation of cell death and survival plays a critical role in maintaining internal homeostasis, organ development, and immune function in organisms, and regulatory abnormalities are a common mechanism of various pathological changes. Recent research has shown that regulated cell death (RCD) plays a crucial role in mastitis. The development of drugs to treat cell death and survival abnormalities that can be widely used in mastitis treatment has important clinical significance. This paper will review the molecular mechanisms of apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis and their regulatory roles in mastitis to provide a new perspective for the targeted treatment of mastitis.

Another fly diuretic hormone: tachykinins increase fluid and ion transport by adult Drosophila melanogaster Malpighian 'renal' tubules.

Insects such as the model organism Drosophila melanogaster must modulate their internal physiology to withstand changes in temperature and availability of water and food. Regulation of the excretory system by peptidergic hormones is one mechanism by which insects maintain their internal homeostasis. Tachykinins are a family of neuropeptides that have been shown to stimulate fluid secretion from the Malpighian 'renal' tubules (MTs) in some insect species, but it is unclear if that is the case in the fruit fly, D. melanogaster. A central objective of the current study was to examine the physiological role of tachykinin signaling in the MTs of adult D. melanogaster. Using the genetic toolbox available in this model organism along with in vitro and whole-animal bioassays, our results indicate that Drosophila tachykinins (DTKs) function as diuretic hormones by binding to the DTK receptor (DTKR) localized in stellate cells of the MTs. Specifically, DTK activates cation and anion transport across the stimulated MTs, which impairs their survival in response to desiccation because of their inability to conserve water. Thus, besides their previously described roles in neuromodulation of pathways controlling locomotion and food search, olfactory processing, aggression, lipid metabolism and metabolic stress, processing of noxious stimuli and hormone release, DTKs also appear to function as bona fide endocrine factors regulating the excretory system and appear essential for the maintenance of hydromineral balance.

Adipose Tissue Plasticity: A Comprehensive Definition and Multidimensional Insight.

Adipose tissue is composed of adipocytes, stromal vascular fraction, nerves, surrounding immune cells, and the extracellular matrix. Under various physiological or pathological conditions, adipose tissue shifts cellular composition, lipid storage, and organelle dynamics to respond to the stress; this remodeling is called "adipose tissue plasticity". Adipose tissue plasticity includes changes in the size, species, number, lipid storage capacity, and differentiation function of adipocytes, as well as alterations in the distribution and cellular composition of adipose tissue. This plasticity has a major role in growth, obesity, organismal protection, and internal environmental homeostasis. Moreover, certain thresholds exist for this plasticity with significant individualized differences. Here, we comprehensively elaborate on the specific connotation of adipose tissue plasticity and the relationship between this plasticity and the development of many diseases. Meanwhile, we summarize possible strategies for treating obesity in response to adipose tissue plasticity, intending to provide new insights into the dynamic changes in adipose tissue and contribute new ideas to relevant clinical problems.

Activation of adenosine A2a and A2b receptors augments the skin wound healing in juvenile grass carp

Wounded fish skin leads to the impairment of internal tissue homeostasis and provides an opportunity for pathogens to invade, resulting in the occurrence of fish diseases. Accordingly, skin wound healing has been investigated in many fishes. In the present study, we found that the concentration of adenosine increased in grass carp skin wounds and antagonization of adenosine receptors aggravated the skin wound closure, implying that adenosine receptor activation played a role in fish skin wound repair. After the expression of adenosine A2a receptor (A2aR) and A2bR in grass carp skin was verified, the effects of two adenosine analogs, ZM241385 and CGS 21680, on grass carp A2aR and A2bR activation were examined by a dual-luciferase assay. The results showed that 500 nM of ZM241385 could antagonize the activation of both receptors by adenosine and 5–5000 nM of CGS 21680 could stimulate both receptors. In this scenario, these two compounds were administrated to the skin wounds of juvenile grass carp weighting about 8.0 g each, showing that 0.5, 2.5, 12.5 μg/tail of ZM241385 dose-dependently delayed while 0.8 and 2.4 μg/tail of CGS 21680 accelerated closure of the wounds when compared to the control group treated with the solvent. The thickness and cell proliferation of the epithelial layer in the wounds were decreased by 2.5 μg/tail of ZM241385 but increased by 0.8 μg/tail of CGS 21680 at 3 days post wounding compared to the control group. To our knowledge, this is the first report demonstrating the effects of adenosine receptor activation on skin re-epithelization in vertebrates. Moreover, the effects of ZM241385 and CGS 21680 on granulation formation including fibroblast migration and collagen deposition in grass carp skin wounds were also investigated in the present study. The results revealed that these two compounds oppositely regulated fibroblast migration and collagen deposition in grass carp skin wounds. These results implied that activation of grass carp A2aR and A2bR improved granulation formation in the wound, leading to enhancement of skin wound repair in juvenile grass carp. These results provide the new clues and mechanisms on the skin wound healing in fish species.

Long-term arsenic exposure decreases mice body weight and liver lipid droplets

Arsenic (As) is a widespread global pollutant, and there is significant controversy surrounding its complex relationship with obesity, primarily focused on short-term exposure. Recognizing the prolonged nature of dietary arsenic exposure, this study involved feeding mice with arsenic-contained food for 14 months. The results showed that mice exposed to arsenic developed a non-alcoholic fatty liver condition, characterized by a light-yellow hue on the liver surface and various pathological alterations in the liver cells, including enlarged nuclei, cellular necrosis, inflammatory infiltration, dysfunctional mitochondria, and endoplasmic reticulum disorganization. There were also disruptions in biochemistry indices, with a significant increase in total cholesterol (TC) level and a decrease in high-density lipoprotein (HDL) level. However, some contradictory observations occurred, such as a significant decrease in body weight, triglyceride (TG) level, and the numbers of lipid droplets. Several genes related to lipid metabolism were tested, and a model was used to explain these discrepancies. Besides, examinations of the colon revealed compromised intestinal barrier function and signs of inflammation. Fecal 16S rRNA sequencing and pseudo-targeted metabolomics revealed disruptions in internal homeostasis, such as modules, nodes, connections, and lipid-related KEGG pathways. Fecal targeted metabolomics analyses of short-chain fatty acids (SCFAs) and bile acids (BAs) demonstrated a significant upregulation in three primary bile acids (CA, CDCA, TCDCA), four secondary bile acids (TUDCA, DCA, LCA, GUDCA), and total SCFAs level. Oxidative stress and inflammation were also evident. Additionally, based on correlation analysis and mediation analysis, it was assumed that changes in the microbiota (e.g., Dubosiella) can impact the liver metabolites (e.g., TGs) through alterations in fecal metabolites (e.g., LPCs). These findings provide a theoretical reference for the long-term effect of arsenic exposure on liver lipid metabolism.

Insights from Traditional Chinese Medicine for Restoring Skin Barrier Functions.

The skin barrier is essential for maintaining the body's internal homeostasis, protecting against harmful external substances, and regulating water and electrolyte balance. Traditional Chinese Medicine (TCM) offers notable advantages in restoring skin barrier function due to its diverse components, targets, and pathways. Recent studies have demonstrated that active ingredients in TCM can safely and effectively repair damaged skin barriers, reinstating their proper functions. This review article provides a comprehensive overview of the mechanisms underlying skin barrier damage and explores how the bioactive constituents of TCM contribute to skin barrier repair, thereby offering a theoretical framework to inform clinical practices.

Soluble Guanylate Cyclase α1 Gene Influences Egg-Laying Amount and Hatching Rate in Bombyx mori.

Soluble guanylate cyclase (sGC) serves as a receptor of nitric oxide (NO) and is the core metalloenzyme in the NO signal transduction pathway. sGC plays a key role in the NO-cGMP signal transduction pathway and participates in various physiological processes, including cell differentiation, neuron transmission, and internal environment homeostasis. sGC consists of two subunits, α and β, each subunit containing multiple isoforms. In this study, we cloned and analyzed the sGC-α1 gene in the silkworm Bombyx mori (BmsGC-α1). The BmsGC-α1 gene was expressed highest at the pupal stages. The highest BmsGC-α1 mRNA expression was observed in the head of fifth instar larvae and in fat body during the wandering stage of B. mori. Furthermore, we observed that feeding fifth instar larvae with thyroid hormone and nitroglycerin induced the expression of the BmsGC-α1 gene. Injection of BmsGC-α1 siRNA into silkworms at the prepupal stage resulted in a significant decrease in BmsGC-α1 expression levels at 48 and 72 h postinjection. After silencing BmsGC-α1, both the egg-laying amount and hatching rate of silkworm eggs were significantly reduced compared to the control group. These results suggest that BmsGC-α1 plays an important role in regulating the reproductive system of silkworms. This finding enhances our understanding of the functional diversity of sGC in insects.

Cosmeceuticals: A Review of Clinical Studies Claiming to Contain Specific, Well-Characterized Strains of Probiotics or Postbiotics.

The skin serves as a critical barrier against external threats-dehydration, ultraviolet exposure, and infections-playing a significant role in internal homeostasis and moisture retention. Additionally, and equally importantly, it interacts dynamically with the complex microbiome resident in it, which is essential for maintaining skin health. Recent interest has focused on the use of probiotics and postbiotics, besides their ability to modulate the skin microbiome, to enhance barrier function, and exhibit anti-inflammatory properties, to be involved in skincare, by having the potential to improve skin hydration, elasticity, and overall appearance, as well as in reducing signs of aging, such as wrinkles and fine lines. The products-being a combination of a cosmetic regime plus probiotic[s] or postbiotic[s]-are named cosmeceuticals. However, to comply with the regulations for the characterization of a microorganism as a specific probiotic strain, the pro- or postbiotics incorporated into the cosmetic regime should be both genetically and phenotypically defined. Thus, in this review, we present 14 published clinical trials using such cosmetic products with specific, well-characterized strains of probiotics or postbiotics applied to volunteers with healthy skin. Looking at the results of these studies collectively, we can say that these genetically and phenotypically defined strains of either live or inanimate bacteria and/or their components seem to keep the treated skin at least fully hydrated, with intact epithelial tone, increased radiance, and with decreased wrinkle depth, while normalizing the commensal skin microbiota. Future advancements in personalized skin care may lead to genomic sequencing and metabolomics to tailor probiotic and postbiotic treatments to individual skin microbiomes, promising a new frontier in cosmeceuticals.

Mitigating of Paracetamol-induced Hepatotoxicity in Albino Mice Using Boerhaavia diffusa Extracts

Boerhaavia diffusa, renowned for its therapeutic efficacy in chronic liver diseases, operates through multifaceted mechanisms to uphold internal homeostasis. Its pivotal roles encompass modulation of intermediary metabolism of macromolecules, synthesis of crucial plasma proteins, enzymatic activities, and bile excretion.In this investigation, we aimed to evaluate the hepatoprotective potential of Boerhaavia diffusa against paracetamol-induced hepatotoxicity in rats. Our study revealed promising outcomes as the extracts obtained from Boerhaavia diffusa demonstrated a significant hepatoprotective role in albino rats subjected to hepatotoxicity induced by paracetamol administration. During the study, the animals were administered doses of 1g/kg b.wt and 2 g/kg b.wt of the plant extracts. Following paracetamol administration, conspicuous changes were observed in hepatocyte biochemical markers, indicative of hepatotoxicity. However, treatment with Boerhaavia diffusa extracts ameliorated these alterations, underscoring their potential to mitigate paracetamol-induced liver injury. These findings underscore the significant hepatoprotective properties inherent in the plant extracts derived from Boerhaavia diffusa. which can be utilized as a potential therapeutic avenue for the management of paracetamol-induced liver damage. These findings hold promise for the development of novel therapeutic interventions aimed at safeguarding liver health and mitigating the adverse effects of hepatotoxic insults.

Breathomics Detect the Cardiovascular Disease: Delusion or Dilution of the Metabolomic Signature.

Volatile organic compounds (VOCs) can be subdivided into exogenous and endogenous categories based on their origin. Analyzing the endogenous VOCs can provide insights into maintaining the internal organs' homeostasis. Despite the ongoing development and the current understanding, studies have suggested a link between cardiovascular metabolic alterations in patients with ischemic heart disease and elevated levels of ethane and isoprene detectable through exhaled breath analysis. Conversely, patients with chronic heart failure exhibit elevated acetone and pentane in their exhaled air. These substances originate from disturbances in the heart tissue, including cellular and subcellular modulations. Hypothetically, ethane levels in the exhaled breath analysis can demonstrate the severity of ischemic heart disease and, consequently, the risk of death in the next 10 years due to cardiovascular disease (CVD). Real-time direct mass spectrometry is the preferred method for assessing VOCs in exhaled breath analysis. The accuracy of this analysis depends on several factors, including the selection of the relevant breath fraction, the type of breath collection container (if used), and the pre-concentration technique.

Drosophila immune cells transport oxygen through PPO2 protein phase transition

Insect respiration has long been thought to be solely dependent on an elaborate tracheal system without assistance from the circulatory system or immune cells1,2. Here we describe that Drosophila crystal cells—myeloid-like immune cells called haemocytes—control respiration by oxygenating Prophenoloxidase 2 (PPO2) proteins. Crystal cells direct the movement of haemocytes between the trachea of the larval body wall and the circulation to collect oxygen. Aided by copper and a neutral pH, oxygen is trapped in the crystalline structures of PPO2 in crystal cells. Conversely, PPO2 crystals can be dissolved when carbonic anhydrase lowers the intracellular pH and then reassembled into crystals in cellulo by adhering to the trachea. Physiologically, larvae lacking crystal cells or PPO2, or those expressing a copper-binding mutant of PPO2, display hypoxic responses under normoxic conditions and are susceptible to hypoxia. These hypoxic phenotypes can be rescued by hyperoxia, expression of arthropod haemocyanin or prevention of larval burrowing activity to expose their respiratory organs. Thus, we propose that insect immune cells collaborate with the tracheal system to reserve and transport oxygen through the phase transition of PPO2 crystals, facilitating internal oxygen homeostasis in a process that is comparable to vertebrate respiration.