Extreme Physiological Conditions Research Articles

Malignant Hyperthermia: A Life-Threatening Condition in Patients Undergoing Surgical Intervention

Malignant hyperthermia (MH) is a rare, potentially fatal genetic disorder characterized by an unexplained elevation of expired carbon dioxide despite increased minute ventilation, muscle rigidity, and rhabdomyolysis, hyperthermia, tachycardia, acidosis, and hyperkalemia. It can be triggered by many pharmacological agents such as potent inhalation agents (halothane/ isoflurane/ sevoflurane/ desflurane), the depolarizing muscle relaxant (succinylcholine), and extreme physiological conditions such as vigorous exercise and working excessively in a hot and dry environment. Prompt and early recognition of the condition and rapid initiation of treatment measures are necessary to salvage the patient. Since MH is commonly encountered in the operating room or early postoperative period, anesthetists and surgeons need to keep themselves updated regarding the same. This review article aims to summarize our understanding of MH's pathophysiology, current diagnostics, management, and treatment strategies, along with a brief review of literature of published cases in Indian Subcontinent.

Extremophiles and their expanding biotechnological applications.

Microbial life is not restricted to any particular setting. Over the past several decades, it has been evident that microbial populations can exist in a wide range of environments, including those with extremes in temperature, pressure, salinity, and pH. Bacteria and Archaea are the two most reported types of microbes that can sustain in extreme environments, such as hot springs, ice caves, acid drainage, and salt marshes. Some can even grow in toxic waste, organic solvents, and heavy metals. These microbes are called extremophiles. There exist certain microorganisms that are found capable of thriving in two or more extreme physiological conditions simultaneously, and are regarded as polyextremophiles. Extremophiles possess several physiological and molecular adaptations including production of extremolytes, ice nucleating proteins, pigments, extremozymes and exopolysaccharides. These metabolites are used in many biotechnological industries for making biofuels, developing new medicines, food additives, cryoprotective agents etc. Further, the study of extremophiles holds great significance in astrobiology. The current review summarizes the diversity of microorganisms inhabiting challenging environments and the biotechnological and therapeutic applications of the active metabolites obtained as a response to stress conditions. Bioprospection of extremophiles provides a progressive direction with significant enhancement in economy. Moreover, the introduction to omics approach including whole genome sequencing, single cell genomics, proteomics, metagenomics etc., has made it possible to find many unique microbial communities that could be otherwise difficult to cultivate using traditional methods. These findings might be capable enough to state that discovery of extremophiles can bring evolution to biotechnology.

Blood Rheology and Hemodynamics.

Seminars in Thrombosis and Hemostasis (STH) celebrates 50 years of publishing in 2024. To celebrate this landmark event, STH is republishing some archival material. This article represents the most highly cited paper ever published in STH. The original abstract follows.Blood is a two-phase suspension of formed elements (i.e., red blood cells [RBCs], white blood cells [WBCs], platelets) suspended in an aqueous solution of organic molecules, proteins, and salts called plasma. The apparent viscosity of blood depends on the existing shear forces (i.e., blood behaves as a non-Newtonian fluid) and is determined by hematocrit, plasma viscosity, RBC aggregation, and the mechanical properties of RBCs. RBCs are highly deformable, and this physical property significantly contributes to aiding blood flow both under bulk flow conditions and in the microcirculation. The tendency of RBCs to undergo reversible aggregation is an important determinant of apparent viscosity because the size of RBC aggregates is inversely proportional to the magnitude of shear forces; the aggregates are dispersed with increasing shear forces, then reform under low-flow or static conditions. RBC aggregation also affects the in vivo fluidity of blood, especially in the low-shear regions of the circulatory system. Blood rheology has been reported to be altered in various physiopathological processes: (1) Alterations of hematocrit significantly contribute to hemorheological variations in diseases and in certain extreme physiological conditions; (2) RBC deformability is sensitive to local and general homeostasis, with RBC deformability affected by alterations of the properties and associations of membrane skeletal proteins, the ratio of RBC membrane surface area to cell volume, cell morphology, and cytoplasmic viscosity. Such alterations may result from genetic disorders or may be induced by such factors as abnormal local tissue metabolism, oxidant stress, and activated leukocytes; and (3) RBC aggregation is mainly determined by plasma protein composition and surface properties of RBCs, with increased plasma concentrations of acute phase reactants in inflammatory disorders a common cause of increased RBC aggregation. In addition, RBC aggregation tendency can be modified by alterations of RBC surface properties because of RBC in vivo aging, oxygen-free radicals, or proteolytic enzymes. Impairment of blood fluidity may significantly affect tissue perfusion and result in functional deteriorations, especially if disease processes also disturb vascular properties.

Extremotolerant Gelatinase Enzyme Production by UCM4 Bacterial Strain Isolated from the Rhizospheric Soil of Rhizophora mangle

Gelatinases are important metalloproteases which specifically act on gelatin. Gelatinase hydrolyze gelatin into polypeptides, peptides and amino acids which can cross the cell membrane to get utilized by the organisms. Gelatinase and collagenase are not only used in chemical and medical field but also in food and basic biological sciences. Since gelatinase has potential applications and high demands, the search for new isolates producing gelatinase with extremotolerant property is significant. In the present study we focus on potential extremotolerant gelatinase production from Cellulosimicrobium funkei strain UCM4 isolated from the rhizospheric soil of Rhizophora mangle from coastal regions of Dakshina Kannada, Karnataka, India. The isolate was tested for extremotolerant property with potential gelatinase production in extreme physiological conditions such as pH, salinity and temperature. The isolate showed 56,500 μg/ml of gelatinase production at its optimum growth conditions. The gelatinase production was increased with increase in pH from 7 to 11 which was between 56,500 μg/ml to 58,888.3 μg/ml. Gelatinase production was observed at temperature ranges from 30°C to 40°C which was between 57,777.2 μg/ml to 55,555 μg/ml, and salinity ranges from 0% to 5% NaCl (w/v) which was between 56,500 μg/ml to 49,999.5 μg/ml. The study revealed that the Cellulosimicrobium funkei strain UCM4 has ability to produce extremotolerant gelatinase and hence UCM4 has its potentiality for industrial scale production of gelatinase enzyme and the results will stand as a base line data for the production and application of gelatinase in future.

Assessment of bacterial biosurfactant production and application in Enhanced Oil Recovery (EOR)—A green approach

The present work attempts to investigate production of biosurfactant, in a modified synthetic media, by less explored bacterial strain isolated from iron factory waste effluent from West Bengal, India and its application in enhanced oil recovery operations. The screened isolate was identified to be Pseudomonas mendocina by 16s rDNA gene homology (NCBI-Genebank accession no. MH091331). It showed a high emulsification of 68.3 ± 2.86%, lowering surface tension of water to 31 mN/ m and CMC of 125 mg l −1 and found to be alkalophillic (pH 6 to 12) and halophilic (up to 6% NaCl) in nature. Batch study in optimized media led to maximum yield of 3.09 ± 0.12 g l −1 . Production kinetic analysis by Luedeking Piret model successfully predicted mixed growth associated biosurfactant production with α and β values of 0.73 and 1.60 respectively and a yield coefficient of 0.82. Cost estimation for production of biosurfactant was calculated under lab scale conditions. Characterization of the extracted biosurfactant by anthrone test and Lowry’s protein estimation, TLC, FTIR, H 1 NMR and FESEM revealed the presence of sugar, peptides and lipid moieties. The biosurfactant obtained is extremely robust with high stability, sustaining wide range of pH (4 to 12), salinity (0.5 to 10% NaCl) and temperature (up to 100 °C). Toxicity assessment by Vigna radiata seed bioassay and MTT assay using and HEK293 cell line showed the non-toxic nature of the biosurfactant. Crude biosurfactant could play effective role in oil recovery with 44.3 ± 0.5 % enhanced oil recovery using sand packed column. • Biosurfactant (BS) from newly isolated halo-alkalophillic bacterial strain. • BS production in economically suitable optimized media. • Notably stable BS, tolerating extreme physiological conditions. • BS exhibiting presence of both glycolipids and lipopeptides: blend nature. • Potential use of crude biosurfactant for enhanced oil recovery.

Some Conceptual and Empirical Shortcomings of IIT

The Integrated Information Theory of consciousness (IIT) has generated much excitement inside and outside the scientific community, and seems to many the leading contender for a satisfactory theory grounded in systems neuroscience. It is a bold theory, one that provides plausible explanations for various recognized neuroscientific facts, makes surprising predictions that go beyond current scientific orthodoxy but are potentially testable, and has inspired development of what appears to be an effective technique for detecting the presence of consciousness in organisms incapable of verbal report, such as non-human animals, neonates, and severely brain-damaged adults. Despite these virtues, IIT appears fundamentally flawed: This paper first revisits some key conceptual and technical issues that have been raised previously but remain unresolved—in particular, issues concerning IIT’s concept of “information” and its approach to the “hard problem”—and then focuses on several empirical phenomena that IIT seems unable to handle satisfactorily. These include: 1. cases of multiple personality or dissociative identity disorder in which complex and overlapping centers of consciousness co-occur in single human organisms; 2. the failure of the intense phenomenology of psychedelic states to be straightforwardly reflected in accompanying neuroelectric activity; and, most critically; 3. the occurrence of profound and personally transformative near-death experiences (NDEs) under extreme physiological conditions such as cardiac arrest, in which IIT predicts that no conscious experience whatsoever should be possible. These empirical arguments show that IIT itself is untenable, and they apply also to its physicalist competitors. Scientifically and philosophically respectable alternatives, however, are available.

Rhizobia inhabiting <em>Clitoria ternatea</em> L. in Anuradhapura District, Sri Lanka: An assessment of stress tolerance and genetic diversity

Legume-Rhizobial symbiosis plays a greater agronomical and ecological significance as it provides fixed nitrogen through Biological Nitrogen Fixation. <em>Clitoria ternatea </em>is a leguminous plant that hosts a wide range of rhizobial strains. Even though it is a widely distributed plant, comprehensive information and studies conducted on the rhizobial - <em>C.</em> <em>ternatea </em>symbiosis is lacking in Sri Lanka. This study aimed to identify different stress-tolerant rhizobial strains inhabiting root nodules of <em>C.</em> <em>ternatea </em>growing in seven selected locations of Anuradhapura district of Sri Lanka<em>. </em>Twenty-eight pure rhizobial colonies were isolated and they were separately grown in ½ Lupin broths and were subjected to four different physiological conditions, pH, temperature, salinity, and drought. Most of the isolates were well-grown within the pH range of 5.0-8.0, the temperature range of 30-35°C and at 0.2% Polyethylene glycol-8000 (PEG) concentration. There was no observable pattern in the growth of rhizobial strains in different physiological conditions. The twelve rhizobial strains which showed high tolerance to extreme physiological conditions were subjected to a combination of physiological stress conditions of pH 8.0, temperature 36°C, 3.0 % NaCl and 0.4 % PEG. The maximum growth in combination physiological study was observed in a strain collected at the Palugaswewa site. According to the dendrogram prepared by the Enterobacterial Repetitive Intergenic Consensus (ERIC) profile, twelve strains are genetically diverse, as they belonged to11 clusters at 69.89 % of similarity level. These stress-tolerant rhizobial strains could be used for further studies on cross-inoculation of crop legumes as an alternative to the nitrogenous fertilizers.

Repeated stimulation of the HPA axis alters white blood cell count without increasing oxidative stress or inflammatory cytokines in fasting elephant seal pups.

The hypothalamic-pituitary-adrenal (HPA) axis controls the release of glucocorticoids, which regulate immune and inflammatory function by modulating cytokines, white blood cells and oxidative stress via glucocorticoid receptor (GR) signaling. Although the response to HPA activation is well characterized in many species, little is known about the impacts of HPA activation during extreme physiological conditions. Hence, we challenged 18 simultaneously fasting and developing elephant seal pups with daily intramuscular injections of adrenocorticotropin (ACTH), a GR antagonist (RU486), or a combination of the two (ACTH+RU486) for 4days. We collected blood at baseline, 2 h and 4days after the beginning of treatment. ACTH and ACTH+RU486 elevated serum aldosterone and cortisol at 2 h, with effects diminishing at 4days. RU486 alone induced a compensatory increase in aldosterone, but not cortisol, at 4 days. ACTH decreased neutrophils at 2 h, while decreasing lymphocytes and increasing the neutrophil:lymphocyte ratio at 4days. These effects were abolished by RU486. Despite alterations in white blood cells, there was no effect of ACTH or RU486 on transforming growth factor-β or interleukin-6 levels; however, both cytokines decreased with the 4day fasting progression. Similarly, ACTH did not impact protein oxidation, lipid peroxidation or antioxidant enzymes, but plasma isoprostanes and catalase activity decreased while glutathione peroxidase increased with fasting progression. These data demonstrate differential acute (2 h) and chronic (4 days) modulatory effects of HPA activation on white blood cells and that the chronic effect is mediated, at least in part, by GR. These results also underscore elephant seals' extraordinary resistance to oxidative stress derived from repeated HPA activation.

Acute and Chronic HPA Axis Stimulation Alters White Blood Cell Ratios but Not Inflammatory Markers or Oxidative Stress in Elephant Seals

Activation of the hypothalamic-pituitary-adrenal (HPA) axis regulates immune and inflammatory responses through modulation of cytokines, white blood cells (WBCs), and oxidative stress. However, little is known about the impact of HPA axis activation during extreme physiological conditions in marine mammals. We challenged 18 post-weaning (simultaneously fasting and developing) northern elephant seal pups with daily intra-muscular injections of slow-release adrenocorticotropin (ACTH), a glucocorticoid receptor (GR) antagonist (RU486), or a combination (ACTH+RU486) for four days. Animals were blood sampled at baseline, 2 hours (2h), and 4 days (4d) after the beginning of the treatment. ACTH and ACTH+RU486 elevated aldosterone and cortisol at 2h, with the effect diminishing at 4d. RU486 alone induced a compensatory increase in aldosterone, but not cortisol, at 4d. ACTH decreased neutrophils (N) at 2h while decreasing lymphocytes (L) and increasing N:L ratio at 4d. These effects were abolished by RU486. Despite alterations in WBCs, there was no effect of ACTH on TGF-b or IL6; however, both cytokines decreased across the fast (4d). Similarly, ACTH did not impact protein oxidation, lipid peroxidation, or antioxidant enzyme activities, but lipid peroxidation and catalase decreased while glutathione peroxidase increased with fasting progression. ACTH did not alter triglycerides or NEFA, although triglycerides did decrease with fasting progression. These data show that HPA axis activation has differential acute (2h) and chronic (4d) modulatory effects on WBCs and that the chronic effect is mediated, at least in part, by GR signaling. These results also underscore the robustness and tolerance of these elephant seals to repeated HPA activation.

A custom-made functionalization method to control the biological identity of nanomaterials

Here we propose a one-step strategy to endow nanomaterials with a custom-designed bio-identity. This study designs a universal ‘nanomaterial binding domain’ that can be genetically attached to any protein ensuring precise and spontaneous protein orientation. We demonstrate how, despite the simplicity of the method, the bioconjugation achieved: (i) is highly efficient, even in the presence of competing proteins, (ii) is stable at extreme physiological conditions (pH ranges 5.2-9.0; NaCl concentrations 0-1 M); (iii) prevents unwanted protein biofouling days after incubation in biologically-relevant conditions; and finally, (iv) avoids nanoparticle interaction with promiscuous unspecific receptors. In summary, this protein biocoating technique, applicable to a wide array of nano-designs, integrates material science and molecular biology procedures to create hybrid nanodevices with well-defined surfaces and predictable biological behaviors, opening a chapter in precision nanodiagnostics, nanosensing or nanotherapeutic applications.

Bioinspired Scaffold Action Under the Extreme Physiological Conditions of Simulated Space Flights: Osteogenesis Enhancing Under Microgravity.

Prolonged exposure to microgravity (MG) during long-duration space flights is known to induce severe dysregulation of osteoblast functions connected to a significant bone loss, similar to the condition induced by osteoporosis. Hence, we here present MG as a promising model to challenge the effectiveness of new scaffolds designed for bone regeneration in counteracting bone loss. To this end, we carried out an integrative study aimed to evaluate, in the extreme condition of Random Positioning Machine-simulated MG, the osteoinductive potential of nanocrystalline magnesium-doped hydroxyapatite/type I collagen composite scaffold (MHA/Coll), that we previously demonstrated to be an excellent tool for bone tissue engineering. Initially, to test the osteoinductive properties of our bioinspired-scaffold, MHA/Coll structure was fully characterized under MG condition and compared to its static counterpart. Human bone marrow-derived mesenchymal stem cells were used to investigate the scaffold biocompatibility and ability to promote osteogenic differentiation after long-duration exposure to MG (up to 21 days). The results demonstrate that the nanostructure of MHA/Coll scaffold can alleviate MG-induced osteoblast dysfunction, promoting cell differentiation along the osteogenic lineage, with a consequent reduction in the expression of the surface markers CD29, CD44, and CD90. Moreover, these findings were corroborated by the ability of MHA/Coll to induce the expression of genes linked to osteogenesis, including alkaline phosphatase and osteocalcin. This study confirmed MHA/Coll capabilities in promoting osteogenesis even in extreme long-term condition of MG, suggesting MG as an effective challenging model to apply in future studies to validate the ability of advanced scaffolds to counteract bone loss, facilitating their application in translational Regenerative Medicine and Tissue Engineering.

Stress tolerant rhizobia inhabiting the root nodules of Gliricidia sepium from selected locations of Anuradhapura district, Sri Lanka

The symbiotic association between Rhizobium and leguminous species plays a significant role in sustainable agricultural systems as it contributes higher amounts of fixed nitrogen to soil through biological nitrogen fixation. Gliricidia sepium is one of the most commonly cultivated agro forestry trees in the world. This leguminous tree is widely distributed throughout Sri Lanka. A very limited number of studies are available on G. sepium–Rhizobium symbiosis in Sri Lanka. The main objective of this study is to isolate and identify the stress tolerant Rhizobium sp. in G. sepium as a preliminary approach to use rhizobial strains for cross inoculation of crop legumes in order to minimize the heavy use of chemical nitrogen fertilizers. The root nodules of G. sepium were collected from seven sites in Anuradhapura district which is located in the dry zone of Sri Lanka. A total of 34 strains were tested for their tolerance to different physiological conditions namely pH, salinity, drought and temperature. Fifteen strains showed a higher tolerance among the isolated 34 strains when grown under a wide range of physiological conditions. When these 15 stress tolerant rhizobial strains were grown under extreme physiological conditions, 12 strains could survive well as they often experience adverse environmental conditions in their natural habitat. DNA fingerprinting analysis with ERIC 1R and ERIC 2R showed that the 15 strains are genetically diverse and they belong to 9 clusters at 71% similarity level

Induced pluripotent stem cells as a tool for comparative physiology: lessons from the thirteen-lined ground squirrel.

Comparative physiologists are often interested in adaptive physiological phenomena found in unconventional model organisms; however, research on these species is frequently constrained by the limited availability of investigative tools. Here, we propose that induced pluripotent stem cells (iPSCs) from unconventional model organisms may retain certain species-specific features that can consequently be investigated in depth in vitro; we use hibernating mammals as an example. Many species (including ground squirrels, bats and bears) can enter a prolonged state of physiological dormancy known as hibernation to survive unfavorable seasonal conditions. Our understanding of the mechanisms underpinning the rapid transition and adaptation to a hypothermic, metabolically suppressed winter torpor state remains limited partially because of the lack of an easily accessible model. To address the fascinating unanswered questions underlying hibernation biology, we have developed a powerful model system: iPSCs from a hibernating species, the thirteen-lined ground squirrel (Ictidomys tridecemlineatus). These stem cells can potentially be differentiated into any cell type, and can be used for the analysis of cell-autonomous mechanisms that facilitate adaptation to hibernation and for comparisons with non-hibernators. Furthermore, we can manipulate candidate molecular and cellular pathways underlying relevant physiological phenomena by pharmacological or RNAi-based methods, and CRISPR/Cas9 gene editing. Moreover, iPSC strategies can be applied to other species (e.g. seals, naked mole rats, humming birds) for in vitro studies on adaptation to extreme physiological conditions. In this Commentary, we discuss factors to consider when attempting to generate iPSCs from unconventional model organisms, based on our experience with the thirteen-lined ground squirrel.

Environmental filtering of bacterial functional diversity along an aridity gradient

Studying how metagenome composition and diversity varies along environmental gradients may improve understanding of the general principles of community and ecosystem structuring. We studied soil bacterial metagenomes along a precipitation gradient on the eastern Tibetan Plateau, varying between 500 mm and 60 mm mean annual precipitation (MAP). We found that lower MAP was strongly associated with reduced functional diversity of bacterial genes. It appears that extreme environmental conditions associated with aridity constrain the diversity of functional strategies present in soil biota – analogous to broad scale patterns found in plant functional diversity along environmental gradients. In terms of specific functions, more extreme arid conditions were also associated with increased relative abundance of genes related to dormancy and osmoprotectants. Decreased relative abundance of genes related to antibiotic resistance and virulence in more arid conditions suggests reduced intensity of biotic interaction under extreme physiological conditions. These trends parallel those seen in earlier, more preliminary comparisons of metagenomes across biomes.

Stabilization of hypoxia-inducible factor 1α by cobalt chloride impairs podocyte morphology and slit-diaphragm function.

Glomerular podocytes are the major components of the renal filtration barrier, and altered podocyte permselectivity is a key event in the pathogenesis of proteinuric conditions. Clinical conditions such as ischemia and sleep apnea and extreme physiological conditions such as high-altitude sickness are presented with renal hypoxia and are associated with significant proteinuria. Hypoxia is considered as an etiological factor in the progression of acute renal injury. A sustained increase in hypoxia-inducible factor 1α (HIF1α) is a major adaptive stimulus to the hypoxic conditions. Although the temporal association between hypoxia and proteinuria is known, the mechanism by which hypoxia elicits proteinuria remains to be investigated. Furthermore, stabilization of HIF1α is being considered as a therapeutic option to treat anemia in patients with chronic kidney disease. Therefore, in this study, we induced stabilization of HIF1α in glomerular regions in vivo and in podocytes in vitro upon exposure to cobalt chloride. The elevated HIF1α expression is concurrence with diminished expression of nephrin and podocin, podocyte foot-processes effacement, and significant proteinuria. Podocytes exposed to cobalt chloride lost their arborized morphology and cell-cell connections and also displayed cytoskeletal derangements. Elevation in expression of HIF1α is in concomitance with loss of nephrin and podocin in patients with diabetic nephropathy and chronic kidney disease. In summary, the current study suggests that HIF1α stabilization impairs podocyte function vis-à-vis glomerular permselectivity.

Soil pH rather than elevation determines bacterial phylogenetic community assembly on Mt. Norikura

There is considerable interest in the factors which may explain variation in microbial community assembly processes. In this study, we investigated bacterial community assembly, phylogenetic diversity and the relative role of deterministic and stochastic processes along environmental gradients on Mt. Norikura, Japan. DNA extracted from soil samples collected at a range of elevations was PCR-amplified targeting the V3 and V4 regions of the bacterial 16S rRNA gene, and sequenced using Illumina MiSeq. We hypothesized that elevation would be a strong predictor of phylogenetic community assembly, with communities being more phylogenetically clustered towards higher elevations, due to more extreme physiological conditions. We also hypothesized a greater role of stochasticity at the highest elevations, due to more frequent soil disturbance. Contrary to our hypotheses, we found that the strength of phylogenetic clustering and the role of stochasticity were strongly related to soil pH, with phylogenetic clustering and deterministic processes being strongest at lower soil pH values. Moreover, there was no trend towards stronger influence of phylogenetic clustering and stochasticity in the upper elevations of Mt. Norikura. These results reveal an overwhelming influence of soil pH on phylogenetic community assembly of soil bacteria, even when a range of other environmental gradients are present.

Hemostasis and Thrombosis in Extreme Physiological and Pathological Conditions

Hemostasis and Thrombosis in Extreme Physiological and Pathological Conditions

Hypoxia induces ZEB2 in podocytes: Implications in the pathogenesis of proteinuria.

The glomerular filtration barrier (GFB) plays a critical role in ensuing protein free urine. The integrity of the GFB is compromised during hypoxia that prevails during extreme physiological conditions. However, the mechanism by which glomerular permselectivity is compromised during hypoxia remains enigmatic. Rats exposed to hypoxia showed a decreased glomerular filtration rate, podocyte foot-processes effacement, and proteinuria. Accumulation of hypoxia-inducible factor-1α (HIF1α) in podocytes resulted in elevated expression of zinc finger E-box binding homeobox 2 (ZEB2) and decreased expression of E- and P-cadherin. We also demonstrated that HIF1α binds to hypoxia response element localized in the ZEB2 promoter. Furthermore, HIF1α also induced the expression of ZEB2-natural antisense transcript, which is known to increase the efficiency of ZEB2 translation. Ectopic expression of ZEB2 induced loss of E- and P-cadherin and is associated with enhanced motility of podocytes during hypoxic conditions. ZEB2 knockdown abrogated hypoxia-induced decrease in podocyte permselectivity. This study suggests that hypoxia leads to activation of HIF1α-ZEB2 axis, resulting in podocyte injury and poor renal outcome.

Adaptations in energy metabolism and gene family expansions revealed by comparative transcriptomics of three Chagas disease triatomine vectors

BackgroundChagas disease is a parasitic infection caused by Trypanosoma cruzi. It is an important public health problem affecting around seven to eight million people in the Americas. A large number of hematophagous triatomine insect species, occupying diverse natural and human-modified ecological niches transmit this disease. Triatomines are long-living hemipterans that have evolved to explode different habitats to associate with their vertebrate hosts. Understanding the molecular basis of the extreme physiological conditions including starvation tolerance and longevity could provide insights for developing novel control strategies. We describe the normalized cDNA, full body transcriptome analysis of three main vectors in North, Central and South America, Triatoma pallidipennis, T. dimidiata and T. infestans.ResultsTwo-thirds of the de novo assembled transcriptomes map to the Rhodnius prolixus genome and proteome. A Triatoma expansion of the calycin family and two types of protease inhibitors, pacifastins and cystatins were identified. A high number of transcriptionally active class I transposable elements was documented in T. infestans, compared with T. dimidiata and T. pallidipennis. Sequence identity in Triatoma-R. prolixus 1:1 orthologs revealed high sequence divergence in four enzymes participating in gluconeogenesis, glycogen synthesis and the pentose phosphate pathway, indicating high evolutionary rates of these genes. Also, molecular evidence suggesting positive selection was found for several genes of the oxidative phosphorylation I, III and V complexes.ConclusionsProtease inhibitors and calycin-coding gene expansions provide insights into rapidly evolving processes of protease regulation and haematophagy. Higher evolutionary rates in enzymes that exert metabolic flux control towards anabolism and evidence for positive selection in oxidative phosphorylation complexes might represent genetic adaptations, possibly related to prolonged starvation, oxidative stress tolerance, longevity, and hematophagy and flight reduction. Overall, this work generated novel hypothesis related to biological adaptations to extreme physiological conditions and diverse ecological niches that sustain Chagas disease transmission.

Revised Ion/Substrate Coupling Stoichiometry of GABA Transporters.

The purpose of this review is to highlight recent evidence in support of a 3 Na+: 1 Cl-: 1 GABA coupling stoichiometry for plasma membrane GABA transporters (SLC6A1 , SLC6A11 , SLC6A12 , SLC6A13 ) and how the revised stoichiometry impacts our understanding of the contribution of GABA transporters to GABA homeostasis in synaptic and extrasynaptic regions in the brain under physiological and pathophysiological states. Recently, our laboratory probed the GABA transporter stoichiometry by analyzing the results of six independent measurements, which included the shifts in the thermodynamic transporter reversal potential caused by changes in the extracellular Na+, Cl-, and GABA concentrations, as well as the ratio of charge flux to substrate flux for Na+, Cl-, and GABA under voltage-clamp conditions. The shifts in the transporter reversal potential for a tenfold change in the external concentration of Na+, Cl-, and GABA were 84 ± 4, 30 ± 1, and 29 ± 1 mV, respectively. Charge flux to substrate flux ratios were 0.7 ± 0.1 charges/Na+, 2.0 ± 0.2 charges/Cl-, and 2.1 ± 0.1 charges/GABA. We then compared these experimental results with the predictions of 150 different transporter stoichiometry models, which included 1-5 Na+, 0-5 Cl-, and 1-5 GABA per transport cycle. Only the 3 Na+: 1 Cl-: 1 GABA stoichiometry model correctly predicts the results of all six experimental measurements. Using the revised 3 Na+: 1 Cl-: 1 GABA stoichiometry, we propose that the GABA transporters mediate GABA uptake under most physiological conditions. Transporter-mediated GABA release likely takes place under pathophysiological or extreme physiological conditions.