Localizing Protein Expression of Transporters in Epithelial Cell Membranes of Mosquitoes

Identifying and localizing ion transport proteins in epithelia is important for understanding how these tissues can regulate salt and water balance in animals. Mosquitoes face distinct challenges regarding salt and water balance as larvae live in water of varying ionic composition while adult female mosquitoes must deal with periodic large blood meals. This protocol will explain how to localize ion transporters in epithelia of mosquitoes. Antibodies raised against specific proteins can be used to carry out immunohistochemistry to tag and visualize native proteins in tissues and cells. This technique may be used for whole tissues and organs or can also be used on histological thin sections of fixed tissue. This protocol will detail the use of immunohistochemistry to localize membrane proteins in mosquito organs.

Osmoregulatory Challenges Faced by Mosquitoes and Techniques for Studying the Transporters Involved in Their Adaptations

Mosquitoes are the most important disease vector in the world, and gaining knowledge of their physiology to develop novel population control strategies has been a focus of research for some time. Both aquatic larvae and terrestrial adults face harsh environmental factors that severely challenge their salt and water balance, which are regulated by the function of epithelia of various organs. The regulated passage of water and solutes across epithelia occurs, in part, through transporters expressed in epithelial cell membranes. Identifying these transporters and their localization is necessary to understand how mosquitoes regulate salt and water balance. Here, we review environmental challenges faced by mosquitoes and how they cope with them, in addition to introducing techniques used to identify organ epithelial transporters.

Ammonia transport in the excretory system of mosquito larvae (Aedes aegypti): Rh protein expression and the transcriptome of the rectum

The role of the mosquito excretory organs (Malpighian tubules, MT and hindgut, HG) in ammonia transport as well as expression and function of the Rhesus (Rh protein) ammonia transporters within these organs was examined in Aedes aegypti larvae and adult females. Immunohistological examination revealed that the Rh proteins are co-localized with V-type H+-ATPase (VA) to the apical membranes of MT and HG epithelia of both larvae and adult females. Of the two Rh transporter genes present in A. aegypti, AeRh50-1 and AeRh50-2, we show using quantitative real-time PCR (qPCR) and an RNA in-situ hybridization (ISH) assay that AeRh50-1 is the predominant Rh protein expressed in the excretory organs of larvae and adult females. Further assessment of AeRh50-1 function in larvae and adults using RNAi (i.e. dsRNA-mediated knockdown) revealed significantly decreased [NH4+] (mmol l-1) levels in the secreted fluid of larval MT which does not affect overall NH4+ transport rates, as well as significantly decreased NH4+ flux rates across the HG (haemolymph to lumen) of adult females. We also used RNA sequencing to identify the expression of ion transporters and enzymes within the rectum of larvae, of which limited information currently exists for this important osmoregulatory organ. Of the ammonia transporters in A. aegypti, AeRh50-1 transcript is most abundant in the rectum thus validating our immunohistochemical and RNA ISH findings. In addition to enriched VA transcript (subunits A and d1) in the rectum, we also identified high Na+-K+-ATPase transcript (α subunit) expression which becomes significantly elevated in response to HEA, and we also found enriched carbonic anhydrase 9, inwardly rectifying K+ channel Kir2a, and Na+-coupled cation-chloride (Cl-) co-transporter CCC2 transcripts. Finally, the modulation in excretory organ function and/or Rh protein expression was examined in relation to high ammonia challenge, specifically high environmental ammonia (HEA) rearing of larvae. NH4+ flux measurements using the scanning-ion selective electrode (SIET) technique revealed no significant differences in NH4+ transport across organs comprising the alimentary canal of larvae reared in HEA vs freshwater. Further, significantly increased VA activity, but not NKA, was observed in the MT of HEA-reared larvae. Relatively high Rh protein immunostaining persists within the hindgut epithelium, as well as the ovary, of females at 24-48 h post blood meal corresponding with previously demonstrated peak levels of ammonia formation. These data provide new insight into the role of the excretory organs in ammonia transport physiology and the contribution of Rh proteins in mediating ammonia movement across the epithelia of the MT and HG, and the first comprehensive examination of ion transporter and channel expression in the mosquito rectum.

Protein localization of aquaporins in the adult female disease vector mosquito, Aedes aegypti

The female Aedes aegypti mosquito is a vector for several arboviral diseases, due to their blood feeding behavior and their association with urban communities. While ion transport in Ae. aegypti has been studied, much less is known about mechanisms of water transport. Rapid water and ion excretion occurs in the adult female mosquito post blood meal and involves a set of organs including the midgut, Malpighian tubules (MTs), and hindgut. The MTs are responsible for the formation of primary urine and are considered the most important site for active transport of ions. Within the cells of the MTs, along with various ion transporters, there are aquaporin water channels that aid in the transport of water across the tubule cell membrane. Six aquaporin genes have been molecularly identified in Ae. aegypti (AQP1-6) and found to be responsible for the transport of water and in some cases, small solutes such as glycerol. In this study, we used immunohistochemistry to localize AaAQP1, 2, 4, 5, and 6 in the adult female Ae. aegypti, in non-blood fed and post blood feeding (0.5 and 24hr) conditions. We further examined the main water transporting aquaporin, AaAQP1, using western blotting to determine protein abundance changes in isolated MTs pre- and post-blood feeding. Using fluorescence in situ hybridization, aqp1 mRNA was found exclusively in the principal cells of female MTs. Finally, we used immunogold staining with transmission electron microscopy to determine subcellular localization of AaAQP1 in the Malpighian tubules under non-blood fed conditions. Interestingly, AaAQP1 was found to be predominantly in the principal cells of the MTs, dispersed throughout the brush border; however, there was also evidence of some AaAQP1 localization in the stellate cells of the MTs.

Prognostic value of specific KRAS mutations in patients with colorectal peritoneal metastases

BACKGROUND

There is little evidence on KRAS mutational profiles in colorectal cancer (CRC) peritoneal metastases (PM). This study aims to determine the prevalence of specific KRAS mutations and their prognostic value in a homogeneous cohort of patients with isolated CRC PM treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

MATERIALS AND METHODS

Data were collected from 13 Italian centers, gathered in a collaborative group of the Italian Society of Surgical Oncology. KRAS mutation subtypes have been correlated with clinical and pathological characteristics and survival [overall survival (OS), local (peritoneal) disease-free survival (LDFS) and disease-free survival (DFS)].

RESULTS

KRAS mutations occurred in 172 patients (47.5%) out of the 362 analyzed. Two different prognostic groups of KRAS mutation subtypes were identified: KRASMUT1 (G12R, G13A, G13C, G13V, Q61H, K117N, A146V), median OS > 120 months and KRASMUT2 (G12A, G12C, G12D, G12S, G12V, G13D, A59E, A59V, A146T), OS: 31.2 months. KRASMUT2 mutations mainly occurred in the P-loop region (P < 0.001) with decreased guanosine triphosphate (GTP) hydrolysis activity (P < 0.001) and were more frequently related to size (P < 0.001) and polarity change (P < 0.001) of the substituted amino acid (AA). When KRASMUT1 and KRASMUT2 were combined with other known prognostic factors (peritoneal cancer index, completeness of cytoreduction score, grading, signet ring cell, N status) in multivariate analysis, KRASMUT1 showed a similar survival rate to KRASWT patients, whereas KRASMUT2 was independently associated with poorer prognosis (hazard ratios: OS 2.1, P < 0.001; DFS 1.9, P < 0.001; LDFS 2.5, P < 0.0001).

CONCLUSIONS

In patients with CRC PM, different KRAS mutation subgroups can be determined according to specific codon substitution, with some mutations (KRASMUT1) that could have a similar prognosis to wild-type patients. These findings should be further investigated in larger series.

Hiat1 as a new transporter involved in ammonia regulation

The orphan transporter hippocampus-abundant transcript 1 (Hiat1) was first identified in the mammalian brain. Its specific substrate specificity, however, has not been investigated to date. Here, we identified and analyzed Hiat1 in a crustacean, the green crab Carcinus maenas. Our phylogenetic analysis showed that Hiat1 protein is conserved at a considerable level between mammals and this invertebrate (ca. 78% identical and conserved amino acids). Functional expression of Carcinus maenas Hiat1 in Xenopus laevis oocytes demonstrated the capability to transport ammonia (likely NH₄⁺) in a sodium-dependent manner. Furthermore, applying quantitative polymerase chain reaction, our results indicated a physiological role for Carcinus maenas Hiat1 in ammonia homeostasis, as mRNA abundance increased in posterior gills in response to elevated circulating hemolymph ammonia upon exposure to high environmental ammonia. Its ubiquitous mRNA expression pattern also suggests an essential role in general cellular detoxification of ammonia. Overall, our results introduce a new ubiquitously expressed ammonia transporter, consequently demanding revision of our understanding of ammonia handling in key model systems from mammalian kidneys to crustacean and fish gills.

Search for Gamma-Ray Spectral Lines from Dark Matter Annihilation up to 100 TeV toward the Galactic Center with MAGIC

Linelike features in TeV γ rays constitute a "smoking gun" for TeV-scale particle dark matter and new physics. Probing the Galactic Center region with ground-based Cherenkov telescopes enables the search for TeV spectral features in immediate association with a dense dark matter reservoir at a sensitivity out of reach for satellite γ-ray detectors, and direct detection and collider experiments. We report on 223 hours of observations of the Galactic Center region with the MAGIC stereoscopic telescope system reaching γ-ray energies up to 100 TeV. We improved the sensitivity to spectral lines at high energies using large-zenith-angle observations and a novel background modeling method within a maximum-likelihood analysis in the energy domain. No linelike spectral feature is found in our analysis. Therefore, we constrain the cross section for dark matter annihilation into two photons to ⟨σv⟩≲5×10^{-28}  cm^{3} s^{-1} at 1 TeV and ⟨σv⟩≲1×10^{-25}  cm^{3} s^{-1} at 100 TeV, achieving the best limits to date for a dark matter mass above 20 TeV and a cuspy dark matter profile at the Galactic Center. Finally, we use the derived limits for both cuspy and cored dark matter profiles to constrain supersymmetric wino models.

Physiological responses of freshwater insects to salinity: molecular-, cellular- and organ-level studies

Salinization of freshwater is occurring throughout the world, affecting freshwater biota that inhabit rivers, streams, ponds, marshes and lakes. There are many freshwater insects, and these animals are important for ecosystem health. These insects have evolved physiological mechanisms to maintain their internal salt and water balance based on a freshwater environment that has comparatively little salt. In these habitats, insects must counter the loss of salts and dilution of their internal body fluids by sequestering salts and excreting water. Most of these insects can tolerate salinization of their habitats to a certain level; however, when exposed to salinization they often exhibit markers of stress and impaired development. An understanding of the physiological mechanisms for controlling salt and water balance in freshwater insects, and how these are affected by salinization, is needed to predict the consequences of salinization for freshwater ecosystems. Recent research in this area has addressed the whole-organism response, but the purpose of this Review is to summarize the effects of salinization on the osmoregulatory physiology of freshwater insects at the molecular to organ level. Research of this type is limited, and pursuing such lines of inquiry will improve our understanding of the effects of salinization on freshwater insects and the ecosystems they inhabit.

Studying the Activity of Neuropeptides and Other Regulators of the Excretory System in the Adult Mosquito

Studies of insect physiology, particularly in those species that are vectors of pathogens causing disease in humans and other vertebrates, provide the foundation to develop novel strategies for pest control. Here, a series of methods are described that are routinely utilized to determine the functional roles of neuropeptides and other neuronal factors (i.e., biogenic amines) on the excretory system of the mosquito, Aedes aegypti. The Malpighian tubules (MTs), responsible for primary urine formation, can continue functioning for hours when removed from the mosquito, allowing for fluid secretion measurements following hormone treatments. As such, the Ramsay assay is a useful technique to measure secretion rates from isolated MTs. Ion-selective microelectrodes (ISME) can sequentially be used to measure ion concentrations (i.e., Na⁺ and K⁺) in the secreted fluid. This assay allows for the measurement of several MTs at a given time, determining the effects of various hormones and drugs. The Scanning Ion-selective Electrode Technique uses ISME to measure voltage representative of ionic activity in the unstirred layer adjacent to the surface of ion transporting organs to determine transepithelial transport of ions in near real time. This method can be used to understand the role of hormones and other regulators on ion absorption or secretion across epithelia. Hindgut contraction assays are also a useful tool to characterize myoactive neuropeptides, that may enhance or reduce the ability of this organ to remove excess fluid and waste. Collectively, these methods provide insight into how the excretory system is regulated in adult mosquitoes. This is important because functional coordination of the excretory organs is crucial in overcoming challenges such as desiccation stress after eclosion and before finding a suitable vertebrate host to obtain a bloodmeal.

The transcriptome of anal papillae of Aedes aegypti reveals their importance in xenobiotic detoxification and adds significant knowledge on ion, water and ammonia transport mechanisms

The anal papillae of mosquito larvae are osmoregulatory organs in direct contact with the external aquatic environment that actively sequester ions and take up water in dilute freshwater. In the disease vector Aedes aegypti mechanisms of ion, water and ammonia transport have only been partially resolved. Furthermore, A. aegypti larvae are known to reside in high ammonia sewage and high salt brackish waters, and understanding of anal papillae function in these conditions is in its infancy. The objective of this study was to identify the complement of ion and water transport genes expressed by the anal papillae of freshwater larvae by sequencing their transcriptome, and comparing their expression in anal papillae of larvae abruptly transferred to brackish water for 24 h. Results identified a number of ion and water transport proteins, ammonia detoxifying enzymes, a full suite of xenobiotic detoxifying enzymes and transporters, and G-protein coupled receptors of specific hormones. We identified a marked increase in transcript and protein abundance of aquaporin AaAQP2 in the anal papillae with abrupt transfer to brackish water. We present an updated and more comprehensive model for ion and water transport with additional putative transporters for Na⁺ and Cl^- uptake in the anal papillae. These are organs which are actively engaged in Na⁺, Cl^- and water uptake and regulation when the aquatic larvae encounter fluctuating salinities over the course of their development. Furthermore the transcriptome of the anal papillae includes a full set of xenobiotic detoxification genes suggesting that these are important detoxification organs which is particularly important when larvae reside in polluted water.

A comparison of aquaporin expression in mosquito larvae (Aedes aegypti) that develop in hypo-osmotic freshwater and iso-osmotic brackish water

The mosquito Aedes aegypti vectors the arboviral diseases yellow fever, dengue, Zika and chikungunya. Larvae are usually found developing in freshwater; however, more recently they have been increasingly found in brackish water, potential habitats which are traditionally ignored by mosquito control programs. Aedes aegypti larvae are osmo-regulators maintaining their hemolymph osmolarity in a range of ~ 250 to 300 mOsmol l-1. In freshwater, the larvae must excrete excess water while conserving ions while in brackish water, they must alleviate an accumulation of salts. The compensatory physiological mechanisms must involve the transport of ions and water but little is known about the water transport mechanisms in the osmoregulatory organs of these larvae. Water traverses cellular membranes predominantly through transmembrane proteins named aquaporins (AQPs) and Aedes aegypti possesses 6 AQP homologues (AaAQP1 to 6). The objective of this study was to determine if larvae that develop in freshwater or brackish water have differential aquaporin expression in osmoregulatory organs, which could inform us about the relative importance and function of aquaporins to mosquito survival under these different osmotic conditions. We found that AaAQP transcript abundance was similar in organs of freshwater and brackish water mosquito larvae. Furthermore, in the Malpighian tubules and hindgut AaAQP protein abundance was unaffected by the rearing conditions, but in the gastric caeca the protein level of one aquaporin, AaAQP1 was elevated in brackish water. We found that AaAQP1 was expressed apically while AaAQP4 and AaAQP5 were found to be apical and/or basal in the epithelia of osmoregulatory organs. Overall, the results suggest that aquaporin expression in the osmoregulatory organs is mostly consistent between larvae that are developing in freshwater and brackish water. This suggests that aquaporins may not have major roles in adapting to longterm survival in brackish water or that aquaporin function may be regulated by other mechanisms like post-translational modifications.

Bounds on Lorentz Invariance Violation from MAGIC Observation of GRB 190114C

On January 14, 2019, the Major Atmospheric Gamma Imaging Cherenkov telescopes detected GRB 190114C above 0.2 TeV, recording the most energetic photons ever observed from a gamma-ray burst. We use this unique observation to probe an energy dependence of the speed of light in vacuo for photons as predicted by several quantum gravity models. Based on a set of assumptions on the possible intrinsic spectral and temporal evolution, we obtain competitive lower limits on the quadratic leading order of speed of light modification.

Mid-transverse colon cancer and extended versus transverse colectomy: Results of the Italian society of surgical oncology colorectal cancer network (SICO CCN) multicenter collaborative study

INTRODUCTION

Transverse colon cancer (TCC) is poorly studied, and TCC cases are often excluded from large prospective randomized trials because of their complexity and their potentially high complication rate. The best surgical approach for TCC has yet to be established. The aim of this large retrospective multicenter Italian series is to investigate the advantages and disadvantages of both hemicolectomy and transverse colectomy in order to identify the best surgical approach.

MATERIALS AND METHODS

This was a retrospective cohort study of patients with mid-transverse colon cancer treated with a segmental colon resection or an extended hemicolectomy (right or left) between 2006 and 2016 in 28 high-volume (more than 70 procedures/year) Italian referral centers for colorectal surgery.

RESULTS

The study included 1529 patients, 388 of whom underwent a segmental resection while 1141 underwent an extended resection. A higher number of complications has been reported in the segmental group than in the extended group (30.1% versus 23.6%; p 0.010). In 42 cases the main complication was the anastomotic leak (4.4% versus 2.2%; p 0.020). Recovery outcomes also showed statistical differences: time to first flatus (p 0.014), time to first mobilization (p 0.040), and overall hospital stay (p < 0.001) were significantly shorter in the extended group. Even if overall survival were similar between the groups (95.1% versus 97%; p 0.384), 3-year disease-free survival worsened after segmental resection (78.1% versus 86.2%; p 0.001).

CONCLUSIONS

According to our results, an extended right colon resection for TCC seems to be surgically safer and more oncologically valid.

An impressive capacity for cold tolerance plasticity protects against ionoregulatory collapse in the disease vector Aedes aegypti

The mosquito Aedes aegypti is largely confined to tropical and subtropical regions, but its range has recently been spreading to colder climates. As insect biogeography is tied to environmental temperature, understanding the limits of A. aegypti thermal tolerance and their capacity for phenotypic plasticity is important in predicting the spread of this species. In this study, we report on the chill coma onset (CCO) and recovery time (CCRT), as well as low-temperature survival phenotypes of larvae and adults of A. aegypti that developed or were acclimated to 15°C (cold) or 25°C (warm). Cold acclimation did not affect CCO temperatures of larvae but substantially reduced CCO in adults. Temperature and the duration of exposure both affected CCRT, and cold acclimation strongly mitigated these effects and increased rates of survival following prolonged chilling. Female adults were far less likely to take a blood meal when cold acclimated, and exposing females to blood (without feeding) attenuated some of the beneficial effects of cold acclimation on CCRT. Lastly, larvae suffered from haemolymph hyperkalaemia when chilled, but cold acclimation attenuated the imbalance. Our results demonstrate that A. aegypti larvae and adults have the capacity to acclimate to low temperatures, and do so at least in part by better maintaining ion balance in the cold. This ability for cold acclimation may facilitate the spread of this species to higher latitudes, particularly in an era of climate change.

Development of Aedes aegypti (Diptera: Culicidae) mosquito larvae in high ammonia sewage in septic tanks causes alterations in ammonia excretion, ammonia transporter expression, and osmoregulation

Larvae of the disease vector mosquito, Aedes aegypti (L.) readily develop in ammonia rich sewage in the British Virgin Islands. To understand how the larvae survive in ammonia levels that are lethal to most animals, an examination of ammonia excretory physiology in larvae collected from septic-water and freshwater was carried out. A. aegypti larvae were found to be remarkably plastic in dealing with high external ammonia through the modulation of NH₄⁺ excretion at the anal papillae, measured using the scanning ion-selective electrode technique (SIET), and NH₄⁺ secretion in the primary urine by the Malpighian tubules when developing in septicwater. Ammonia transporters, Amt and Rh proteins, are expressed in ionoregulatory and excretory organs, with increases in Rh protein, Na⁺-K⁺-ATPase, and V-type-H⁺-ATPase expression observed in the Malpighian tubules, hindgut, and anal papillae in septic-water larvae. A comparative approach using laboratory A. aegypti larvae reared in high ammonia septic-water revealed similar responses to collected A. aegypti with regard to altered ammonia secretion and hemolymph ion composition. Results suggest that the observed alterations in excretory physiology of larvae developing in septic-water is a consequence of the high ammonia levels and that A. aegypti larvae may rely on ammonia transporting proteins coupled to active transport to survive in septic-water.

Impact of salt-contaminated freshwater on osmoregulation and tracheal gill function in nymphs of the mayfly Hexagenia rigida

The impact of freshwater (FW) salinization on osmoregulation as well as tracheal gill morphology and function was examined in nymphs of the mayfly Hexagenia rigida following exposure to salt contaminated water (SCW, 7.25 g/l NaCl) for a 7-day period. Ionoregulatory homeostasis was perturbed in SCW exposed H. rigida nymphs as indicated by increased hemolymph Na⁺, K⁺ and Cl^- levels as well as hemolymph pH and water content. Despite this, SCW did not alter gill Na⁺-K⁺-ATPase (NKA) or V-type H⁺-ATPase (VA) activity. In addition, NKA and VA immunolocalization in gill ionocytes did not show alterations in enzyme location or changes in ionocyte abundance. The latter observation was confirmed using scanning electron microscopy (SEM) to examine exposed tracheal gill ionocyte numbers. Ionocyte surface morphometrics also revealed that SCW did not change individual ionocyte surface area or ionocyte fractional surface area. Nevertheless, analysis of Na⁺ movement across the tracheal gill of mayfly nymphs using scanning ion-selective electrode technique indicated that FW nymphs acquired Na⁺ from surrounding water, while tracheal gills of SCW nymphs had the capacity to secrete Na⁺. Because Na⁺ secretion across the gill of SCW-exposed animals occurred in the absence of any change in (1) NKA and VA activity or (2) ionocyte numbers/surface exposure, it was reasoned that Na⁺ movement across the gill of SCW animals may be occurring, at least in part, through the paracellular pathway. The ultrastructure of tracheal gill septate junctions (SJs) supported this idea as they exhibited morphological alterations indicative of a leakier pathway. Data provide a first look at alterations in osmoregulatory mechanisms that allow H. rigida nymphs to tolerate sub-lethal salinization of their surroundings.

Septate junction in the distal ileac plexus of larval lepidopteran Trichoplusia ni: alterations in paracellular permeability during ion transport reversal

The Malpighian tubules (MTs) and hindgut together act as the functional kidney in insects. MTs of caterpillars are notably complex and consist of several regions that display prominent differences in ion transport. The distal ileac plexus (DIP) is a region of Malpighian tubule that is of particular interest because it switches from ion secretion to ion reabsorption in larvae fed on ion-rich diets. The pathways of solute transport in the DIP are not well understood, but one potential route is the paracellular pathway between epithelial cells. This pathway is regulated by the septate junctions (SJs) in invertebrates, and in this study, we found regional and cellular heterogeneity in expression of several integral SJ proteins. DIP of larvae fed ion-rich diets demonstrated a reduction in paracellular permeability, coupled with alterations in both SJ morphology and the abundance of its molecular components. Similarly, treatment in vitro with helicokinin (HK), an antidiuretic hormone identified by previous studies, altered mRNA abundance of many SJ proteins and reduced paracellular permeability. HK was also shown to target a secondary cell-specific SJ protein Tsp2A. Taken together, our data suggest that dietary ion loading, known to cause ion transport reversal in the DIP of larval T. ni, leads to alterations in the paracellular permeability, SJ morphology and its molecular component abundance. The results suggest that HK is an important endocrine factor that co-regulates ion transport, water transport and paracellular permeability in MTs of larval lepidopterans. We propose that co-regulation of all three components of the MT function in larval lepidopterans allows for safe toggling between ion secretion and reabsorption in the DIP in response to variations in dietary ion availability.

Survival comparison in gastric cancer patients between 7th and 8th edition of the AJCC TNM staging system: The first western single center experience

BACKGROUND

The objective of this study was to compare the 7th and the 8th edition of American Joint Committee on Cancer staging system (AJCC TNM) in terms of better stratification in our gastric cancer resected patients.

METHODS AND MATERIALS

A retrospective analysis of a single western center series was made. Patients who underwent surgery from January 2004 to December 2016 were enrolled in the study. We compared survival rates across patients classified according to the 7th and the 8th AJCC TNM staging system.

RESULTS

Among 295 patients we observed 9.8% stage migration according the 8th edition. Of these 2.1% and 7.9% of patients showed respectively a higher and a lower stage. 5 years Overall Survival (5Y-OS) according to the 8th edition for stage IIIB and IIIC were 32% versus 9% showing a better stratification compared to the 7th edition in which 5Y-OS were respectively 26% versus 22%.

CONCLUSION

Restaging system seems to improve survival rate discrimination in particular comparing stage IIIB and stage IIIC; whereas in stage IIIA this is not so clear. More studies are necessary to confirm these data.

Evidence that Rh proteins in the anal papillae of the freshwater mosquito Aedes aegypti are involved in the regulation of acid-base balance in elevated salt and ammonia environments

Aedes aegypti commonly inhabit ammonia-rich sewage effluents in tropical regions of the world where the adults are responsible for the spread of disease. Studies have shown the importance of the anal papillae of A. aegypti in ion uptake and ammonia excretion. The anal papillae express ammonia transporters and Rhesus (Rh) proteins which are involved in ammonia excretion and studies have primarily focused on understanding these mechanisms in freshwater. In this study, effects of rearing larvae in salt (5 mmol l^-1 NaCl) or ammonia (5 mmol l^-1 NH₄Cl) on physiological endpoints of ammonia and ion regulation were assessed. In anal papillae of NaCl-reared larvae, Rh protein expression increased, NHE3 transcript abundance decreased and NH₄ ⁺ excretion increased, and this coincided with decreased hemolymph [NH₄ ⁺] and pH. We propose that under these conditions, larvae excrete more NH₄ ⁺ through Rh proteins as a means of eliminating acid from the hemolymph. In anal papillae of NH₄Cl-reared larvae, expression of an apical ammonia transporter and the Rh proteins decreased, the activities of NKA and VA decreased and increased, respectively, and this coincided with hemolymph acidification. The results present evidence for a role of Rh proteins in acid-base balance in response to elevated levels of salt, whereby ammonia is excreted as an acid equivalent.

Anti-diuretic activity of a CAPA neuropeptide can compromise Drosophila chill tolerance

For insects, chilling injuries that occur in the absence of freezing are often related to a systemic loss of ion and water balance that leads to extracellular hyperkalemia, cell depolarization and the triggering of apoptotic signalling cascades. The ability of insect ionoregulatory organs (e.g. the Malpighian tubules) to maintain ion balance in the cold has been linked to improved chill tolerance, and many neuroendocrine factors are known to influence ion transport rates of these organs. Injection of micromolar doses of CAPA (an insect neuropeptide) have been previously demonstrated to improve Drosophila cold tolerance, but the mechanisms through which it impacts chill tolerance are unclear, and low doses of CAPA have been previously demonstrated to cause anti-diuresis in insects, including dipterans. Here, we provide evidence that low (femtomolar) and high (micromolar) doses of CAPA impair and improve chill tolerance, respectively, via two different effects on Malpighian tubule ion and water transport. While low doses of CAPA are anti-diuretic, reduce tubule K⁺ clearance rates and reduce chill tolerance, high doses facilitate K⁺ clearance from the haemolymph and increase chill tolerance. By quantifying CAPA peptide levels in the central nervous system, we estimated the maximum achievable hormonal titres of CAPA and found further evidence that CAPA may function as an anti-diuretic hormone in Drosophila melanogaster We provide the first evidence of a neuropeptide that can negatively affect cold tolerance in an insect and further evidence of CAPA functioning as an anti-diuretic peptide in this ubiquitous insect model.

Molecular mechanisms of bi-directional ion transport in the Malpighian tubules of a lepidopteran crop pest, Trichoplusia ni

Classical studies have described in detail the complex and regionalized morphology of the Malpighian tubule (MT) in larval Lepidoptera. Recent studies revealed unusual aspects of ion transport in the Malpighian tubules of the larva of the cabbage looper, Trichoplusia ni. These included: cation reabsorption via secondary cells (SC); coupling of SCs to neighbouring PCs via gap junctions to enable reabsorption; and a reversal from cation secretion to reabsorption by the principal cells in the distal ileac plexus region of the in situ tubule in response to dietary ion loading. The current paper aimed to identify molecular components of ion transport in the MTs of T. ni and to describe their role in the recently reported reversal of ion transport in ion-loaded animals. Using a combination of molecular, immunohistochemical and electrophysiological techniques, we assigned roles to Na⁺/K⁺-ATPase (NKA), V-type H⁺-ATPase (VA), Na⁺/K⁺/Cl^- co-transporter (NKCC), K⁺/Cl^- co-transporter (KCC), inward-rectifying K⁺ channel (Kir), and Na⁺/H⁺ exchangers (NHE)-7 and -8 in the transport of Na⁺ and K⁺ by the distal ileac plexus of T. ni. The yellow region of the tubule lacked all of the above except VA, and the white region lacked all of the above transporters but expressed an amiloride-sensitive Na⁺ channel (NaC). Overall, the ion transport machinery in the distal ileac plexus of the T. ni tubule shows remarkable similarity to that in tubules of other groups of insects, yet this region transports ions very differently. Shutdown of secretory ATPases and utilisation of the same molecular machinery in the face of changing ion gradients may enable ion transport reversal in lepidopteran MTs. We propose that gap junction-based coupling of the two cell types likely aids in toggling between ion secretion and ion reabsorption in this segment.

Galanin decreases spontaneous resting contractions and potentiates acetyl choline-induced contractions of goldfish gut

Galanin (GAL) is a 29 amino acid peptide, first identified from the porcine intestine and widely distributed within the brain and peripheral tissues. Among GAL biological functions, its role as a potent appetite-stimulating peptide is probably the most studied. With galanin's established role in the modulation of food intake in fish, this study aims to evaluate the effects of GAL on the intestinal motility of the goldfish, Carassius auratus, using an organ bath system. Our results found that application of GAL to the organ bath causes a significant concentration-dependent decrease in the amplitude of spontaneous contractions of goldfish gut. Preincubations of intestinal strips with acetylcholine (ACh) and GAL showed that GAL increases the force of ACh-induced contractions of the goldfish gut. These results provide the first evidence for a role of GAL in gut motility in goldfish. This also suggests a crosstalk between the effects of GAL and ACh in such functions, thus pointing to a putative joint role between the two molecules. These findings offer novel information that strengthens the role of the galaninergic system in fish feeding.

Ammonia Excretion in an Osmoregulatory Syncytium Is Facilitated by AeAmt2, a Novel Ammonia Transporter in Aedes aegypti Larvae

The larvae of the mosquito Aedes aegypti inhabit ammonia rich septic tanks in tropical regions of the world that make extensive use of these systems, explaining the prevalence of disease during dry seasons. Since ammonia (NH₃/NH4+) is toxic to animals, an understanding of the physiological mechanisms of ammonia excretion permitting the survival of A. aegypti larvae in high ammonia environments is important. We have characterized a novel ammonia transporter, AeAmt2, belonging to the Amt/MEP/Rh family of ammonia transporters. Based on the amino acid sequence, the predicted topology of AeAmt2 consists of 11 transmembrane helices with an extracellular N-terminus and a cytoplasmic C-terminus region. Alignment of the predicted AeAmt2 amino acid sequence with other Amt/MEP proteins from plants, bacteria, and yeast highlights the presence of conserved residues characteristic of ammonia conducting channels in this protein. AeAmt2 is expressed in the ionoregulatory anal papillae of A. aegypti larvae where it is localized to the apical membrane of the epithelium. dsRNA-mediated knockdown of AeAmt2 results in a significant decrease in NH4+ efflux from the anal papillae, suggesting a key role in facilitating ammonia excretion. The effect of high environmental ammonia (HEA) on expression of AeAmt2, along with previously characterized AeAmt1, AeRh50-1, and AeRh50-2 in the anal papillae was investigated. We show that changes in expression of ammonia transporters occur in response to acute and chronic exposure to HEA, which reflects the importance of these transporters in the physiology of life in high ammonia habitats.

Ca2+ levels in Daphnia hemolymph may explain occurrences of daphniid species along recent Ca gradients in Canadian soft-water lakes

Calcium levels are declining in eastern North American and western European lakes. This widespread issue is affecting the composition of crustacean zooplankton communities, as the presence and abundance of several calcium-rich daphniid species are declining, while two other daphniids, D. catawba and D. ambigua, that apparently tolerate low calcium environments, are prospering. The physiological basis for low calcium tolerance of these daphniids is unknown. In this study the presence of one Ca-rich (D. pulicaria) and one Ca-poor (D. ambigua) daphniid species in Canadian Shield lakes is assessed in relation to lake water Ca levels. The occurrence of D. ambigua was independent of Ca levels in Ontario lakes, whereas D. pulicaria was more likely to occur in lakes with relatively more Ca. In the laboratory, D. ambigua maintained lower levels of hemolymph Ca²⁺ across a range of low Ca levels (0.7 to 7 mg l^-1) compared with D. pulicaria. The hemolymph pH remained steady across this Ca gradient in D. ambigua while it was significantly more acidic in D. pulicaria in the two lowest Ca treatments. While Ca²⁺ uptake was observed adjacent to the surface of D. ambigua individuals, Ca²⁺ loss was observed for D. pulicaria assayed under moderately high Ca levels. Based on these observations we propose that D. ambigua is able to survive in low Ca lakes by maintaining low free ionic Ca²⁺ levels in the hemolymph which minimizes the Ca gradient across the body wall in low Ca water thus limiting overall Ca loss and facilitating Ca²⁺ uptake.

Functional plasticity of the gut and the Malpighian tubules underlies cold acclimation and mitigates cold-induced hyperkalemia in Drosophila melanogaster

At low temperatures, Drosophila, like most insects, lose the ability to regulate ion and water balance across the gut epithelia, which can lead to a lethal increase of [K+] in the hemolymph (hyperkalemia). Cold-acclimation, the physiological response to a prior low temperature exposure, can mitigate or entirely prevent these ion imbalances, but the physiological mechanisms that facilitate this process are not well understood. Here, we test whether plasticity in the ionoregulatory physiology of the gut and Malpighian tubules of Drosophila may aid in preserving ion homeostasis in the cold. Upon adult emergence, D. melanogaster females were subjected to seven days at warm (25°C) or cold (10°C) acclimation conditions. The cold acclimated flies had a lower critical thermal minimum (CTmin), recovered from chill coma more quickly, and better maintained hemolymph K+ balance in the cold. The improvements in chill tolerance coincided with increased Malpighian tubule fluid secretion and better maintenance of K+ secretion rates in the cold, as well as reduced rectal K+ reabsorption in cold-acclimated flies. To test whether modulation of ion-motive ATPases, the main drivers of epithelial transport in the alimentary canal, mediate these changes, we measured the activities of Na+-K+-ATPase and V-type H+-ATPase at the Malpighian tubules, midgut, and hindgut. Na+/K+-ATPase and V-type H+-ATPase activities were lower in the midgut and the Malpighian tubules of cold-acclimated flies, but unchanged in the hindgut of cold acclimated flies, and were not predictive of the observed alterations in K+ transport. Our results suggest that modification of Malpighian tubule and gut ion and water transport likely prevents cold-induced hyperkalemia in cold-acclimated flies and that this process is not directly related to the activities of the main drivers of ion transport in these organs, Na+/K+- and V-type H+-ATPases.

Strategies of ionoregulation in the freshwater nymph of the mayfly Hexagenia rigida

This study investigated ionoregulatory strategies used by freshwater (FW) nymphs of the mayfly Hexagenia rigida Like other FW organisms, H. rigida nymphs maintain hemolymph ion levels (in mmol l^-1: Na⁺ ∼102; Cl^- ∼84; K⁺ ∼6; pH ∼7.35) far in excess of their surroundings. This appears to be accomplished by the combined actions of the alimentary canal, Malpighian tubules (MTs) and tracheal gills. The alimentary canal contributes in a region-specific manner, a view supported by: (1) spatial differences in the activity of basolateral Na⁺/K⁺-ATPase (NKA) and apical V-type H⁺-ATPase (VA) and (2) region-specific Na⁺ and K⁺ flux rates. Both indicate a prominent role for the hindgut (rectum) in K⁺ reabsorption. MTs also exhibit region-specific differences in Na⁺ and K⁺ flux rates that are coupled with an organized but tortuous architecture. NKA and VA activities were highest in MTs versus all other organs examined. Tracheal gills were found to be sites of Na⁺ uptake, but no difference in Na⁺ uptake was found between gills taken from different regions of the abdomen or spatially along individual gills. This is likely because each gill exhibited a dense population of NKA and/or VA immunoreactive cells (putative ionocytes). Data provide new insight into how FW mayfly nymphs regulate salt and water balance using the alimentary canal, MTs and tracheal gills as well as the first direct evidence that tracheal gills acquire ions from FW.

Thermal acclimation mitigates cold-induced paracellular leak from the Drosophila gut

Chill susceptible insects suffer tissue damage and die at low temperatures. The mechanisms that cause chilling injury are not well understood but a growing body of evidence suggests that a cold-induced loss of ion and water homeostasis leads to hemolymph hyperkalemia that depolarizes cells, leading to cell death. The apparent root of this cascade is the net leak of osmolytes down their concentration gradients in the cold. Many insects, however, are capable of adjusting their thermal physiology, and cold-acclimated Drosophila can maintain homeostasis and avoid injury better than warm-acclimated flies. Here, we test whether chilling causes a loss of epithelial barrier function in female adult Drosophila, and provide the first evidence of cold-induced epithelial barrier failure in an invertebrate. Flies had increased rates of paracellular leak through the gut epithelia at 0 °C, but cold acclimation reduced paracellular permeability and improved cold tolerance. Improved barrier function was associated with changes in the abundance of select septate junction proteins and the appearance of a tortuous ultrastructure in subapical intercellular regions of contact between adjacent midgut epithelial cells. Thus, cold causes paracellular leak in a chill susceptible insect and cold acclimation can mitigate this effect through changes in the composition and structure of transepithelial barriers.

Environmental calcium regulates gill remodeling in a euryhaline teleost fish

Some cyprindid and cyprinidontiform fishes undergo gill remodeling via the proliferation or regression of an interlamellar cell mass (ILCM), resulting in the modification of gill surface area in response to environmental hypoxia or ion levels. We hypothesized that ion-related gill remodeling is regulated by water hardness through the interactions of Ca²⁺ with tight junctions, predicting that gills will exhibit a lower ILCM and more surface area in a high Ca²⁺ environment than in a low Ca²⁺ environment. To test this hypothesis, we acclimated euryhaline mangrove rivulus (Kryptolebias marmoratus) to natural hard water ([Ca²⁺] = 2.77 mmol/L), low Ca²⁺ ([Ca²⁺] = 0.13 mmol/L) freshwater, or high Ca²⁺ water (5.88 mmol/L). Fish exposed to hard water had a significantly lower ILCM height than fish exposed to low Ca²⁺ water. The addition of Ca²⁺ to low Ca²⁺ water restored gill surface area. Plasma Ca²⁺ activity was not significantly different between groups. This study provides support for an influence of external Ca²⁺ on gill remodeling and represents the first evidence of an ionic trigger (Ca²⁺) for gill remodeling in teleost fishes.

Identification of the septate junction protein gliotactin in the mosquito Aedes aegypti: evidence for a role in increased paracellular permeability in larvae

Septate junctions (SJs) regulate paracellular permeability across invertebrate epithelia. However, little is known about the function of SJ proteins in aquatic invertebrates. In this study, a role for the transmembrane SJ protein gliotactin (Gli) in the osmoregulatory strategies of larval mosquito (Aedes aegypti) was examined. Differences in gli transcript abundance were observed between the midgut, Malpighian tubules, hindgut and anal papillae of A. aegypti, which are epithelia that participate in larval mosquito osmoregulation. Western blotting of Gli revealed its presence in monomer, putative dimer and alternatively processed protein forms in different larval mosquito organs. Gli localized to the entire SJ domain between midgut epithelial cells and showed a discontinuous localization along the plasma membranes of epithelial cells of the rectum as well as the syncytial anal papillae epithelium. In the Malpighian tubules, Gli immunolocalization was confined to SJs between the stellate and principal cells. Rearing larvae in 30% seawater caused an increase in Gli protein abundance in the anterior midgut, Malpighian tubules and hindgut. Transcriptional knockdown of gli using dsRNA reduced Gli protein abundance in the midgut and increased the flux rate of the paracellular permeability marker, polyethylene glycol (molecular weight 400 Da; PEG-400). Data suggest that in larval A. aegypti, Gli participates in the maintenance of salt and water balance and that one role for Gli is to participate in the regulation of paracellular permeability across the midgut of A. aegypti in response to changes in environmental salinity.

The roles of V-type H+-ATPase and Na+/K+-ATPase in energizing K+ and H+ transport in larval Drosophila gut epithelia

We analyzed V-type H⁺-ATPase (VA) and Na⁺/K⁺-ATPase (NKA) along the caeca and midgut of third instar Drosophila larvae using immunohistochemistry and ATPase activity assays. Corresponding H⁺ and K⁺ fluxes were characterized using the Scanning Ion-Selective Electrode Technique (SIET), and the roles of transport ATPases in energizing ion transport across the larval gut were investigated by basal application of bafilomycin, a VA inhibitor, and ouabain, a NKA inhibitor. Addition of bafilomycin led to a decrease in H⁺ absorption along the caeca and midgut except at the copper cells and large flat cell zone of the middle midgut. H⁺ absorption was decreased by acetazolamide, consistent with carbonic anhydrase activity in all regions except at the large flat cell zone of the middle midgut. Bafilomycin or acetazolamide also led to decreased K⁺ absorption across the caeca and the anterior midgut. Our data show the dependence of K⁺ transport on H⁺ gradients established by the VA in the latter regions, consistent with the presence of a Cation-Proton Antiporter (CPA2) identified in other insect epithelia. Addition of ouabain led to the increase of K⁺ absorption along the anterior midgut and the large flat cell zone of the middle midgut, suggesting a role for the NKA in these regions. This study shows the importance of both ATPases in driving ion transport across the gut of larval Drosophila.

Claudin-31 contributes to corticosteroid-induced alterations in the barrier properties of the gill epithelium

The contribution of Claudin-31 (Cldn-31) to corticosteroid-induced tightening of the trout gill epithelium was examined using a primary cultured model preparation. Cldn-31 is a ∼23 kDa protein that localizes to the periphery of gill epithelial cells and diffusely in select gill cells that are Na⁺-K⁺-ATPase-immunoreactive. Transcriptional knockdown (KD) of cldn-31 reduced Cldn-31 abundance and increased epithelium permeability. Under simulated in vivo conditions (apical freshwater), cldn-31 KD increased net ion flux rates (≡ efflux). Cortisol treatment increased Cldn-31 abundance and decreased epithelium permeability. This tightening effect was diminished, but not eliminated, by cldn-31 KD, most likely due to other cortisol-sensitive TJ proteins that were transcriptionally unperturbed or enhanced in cortisol-treated cldn-31 KD preparations. However, cldn-31 KD abolished a cortisol-induced increase in Cldn-8d abundance, which may contribute to compromised cldn-31 KD epithelium permeability. Data suggest an important barrier function for Cldn-31 and an integral role for Cldn-31 in corticosteroid-induced gill epithelium tightening.

A role for tight junction-associated MARVEL proteins in larval sea lamprey (Petromyzon marinus) osmoregulation

This study reports on tight junction-associated MARVEL proteins of larval sea lamprey (Petromyzon marinus) and their potential role in ammocoete osmoregulation. Two Occludin isoforms (designated Ocln and Ocln-a) and a tricellulin (Tric) were identified. Transcripts encoding ocln, ocln-a, and tric were broadly expressed in larval lamprey, with greatest abundance of ocln in gut, liver and kidney, ocln-a in the gill and skin, and tric in the kidney. Ocln and Ocln-a resolved as ∼63 kDa and ∼35 kDa MW proteins respectively while Tric resolved as a ∼50 kDa protein. Ocln immunolocalized to the gill vasculature and in gill mucous cells while Ocln-a localized to the gill pouch and gill epithelium. Both Ocln and Ocln-a localized in the nephron, the epidermis and the luminal side of the gut. In branchial tissue, Tric exhibited punctate localization, consistent with its presence at regions of tricellular contact. Following ion-poor water (IPW) acclimation of ammocoetes, serum [Na+] and [Cl−] reduced, but not [Ca++], and carcass moisture content increased. In association, Ocln abundance increased in skin and kidney, but reduced in gill of IPW-acclimated ammocoetes while Ocln-a abundance reduced in the kidney only. Tric abundance increased in the gill. Region-specific alterations in ocln, ocln-a and tric mRNA abundance was also observed in the gut. Data support a role for Ocln, Ocln-a and Tric in the osmoregulatory strategies of a basal vertebrate.

A mosquito entomoglyceroporin, Aedes aegypti AQP5 participates in water transport across the Malpighian tubules of larvae

The mosquito, Aedes aegypti, is the primary vector for arboviral diseases such as Zika fever, dengue fever, chikungunya, and yellow fever. The larvae reside in hypo-osmotic freshwater habitats, where they face dilution of their body fluids from osmotic influx of water. The Malpighian tubules help maintain ionic and osmotic homeostasis by removing excess water from the hemolymph, but the transcellular pathway for this movement remains unresolved. Aquaporins are transmembrane channels thought to permit transcellular transport of water from the hemolymph into the Malpighian tubule lumen. Immunolocalization of Aedes aegypti aquaporin 5 (AaAQP5) revealed expression by Malpighian tubule principal cells of the larvae, with localization to both the apical and basolateral membranes. Knockdown of AaAQP5 with double stranded RNA decreased larval survival, reduced rates of fluid, K+, and Na+ secretion by the Malpighian tubules and reduced Cl− concentrations in the hemolymph. These findings indicate that AaAQP5 participates in transcellular water transport across the Malpighian tubules of larval Aedes aegypti where global AaAQP5 expression is important for larval survival.

Cold tolerance of Drosophila species is tightly linked to epithelial K+ transport capacity of the Malpighian tubules and rectal pads

Insect chill tolerance is strongly associated with the ability to maintain ion and water homeostasis during cold exposure. Maintenance of K+ balance is particularly important due to its role in setting the cell membrane potential that is involved in many aspects of cellular function and viability. In most insects, K+ balance is maintained through secretion at the Malpighian tubules balancing reabsorption from the hindgut and passive leak arising from the gut lumen. Here, we used a scanning ion-selective electrode technique (SIET) system at benign (23°C) and low (6°C) temperature to examine K+ flux across the Malpighian tubules and the rectal pads in the hindgut in five Drosophila species that differ in cold tolerance. We found that chill tolerant species were better at maintaining K+ secretion and supressing reabsorption during cold exposure. In contrast, chill susceptible species exhibited large reductions in secretion with no change, or a paradoxical increase, in K+ reabsorption. Using an assay to measure paracellular leak we found that chill susceptible species experience a large increase in leak during cold exposure, which could explain the increased K+ reabsorption found in these species. Our data therefore strongly support the hypothesis that cold tolerant Drosophila species are better at maintaining K+ homeostasis through an increased ability to maintain K+ secretion rates and through reduced leakage of K+ towards the hemolymph. These adaptations are manifested both at the Malpighian tubule and at the rectal pads in the hindgut and ensure that cold tolerant species experience less perturbation of K+ homeostasis during cold stress.

Chronic dietary salt stress mitigates hyperkalemia and facilitates chill coma recovery in Drosophila melanogaster

Chill susceptible insects like Drosophila lose the ability to regulate water and ion homeostasis at low temperatures. This loss of hemolymph ion and water balance drives a hyperkalemic state that depolarizes cells, causing cellular injury and death. The ability to maintain ion homeostasis at low temperatures and/or recover ion homeostasis upon rewarming is closely related to insect cold tolerance. We thus hypothesized that changes to organismal ion balance, which can be achieved in Drosophila through dietary salt loading, could alter whole animal cold tolerance phenotypes. We put Drosophila melanogaster in the presence of diets highly enriched in NaCl, KCl, xylitol (an osmotic control) or sucrose (a dietary supplement known to impact cold tolerance) for 24h and confirmed that they consumed the novel food. Independently of their osmotic effects, NaCl, KCl, and sucrose supplementation all improved the ability of flies to maintain K⁺ balance in the cold, which allowed for faster recovery from chill coma after 6h at 0°C. These supplements, however, also slightly increased the CT_min and had little impact on survival rates following chronic cold stress (24h at 0°C), suggesting that the effect of diet on cold tolerance depends on the measure of cold tolerance assessed. In contrast to prolonged salt stress, brief feeding (1.5h) on diets high in salt slowed coma recovery, suggesting that the long-term effects of NaCl and KCl on chilling tolerance result from phenotypic plasticity, induced in response to a salty diet, rather than simply the presence of the diet in the gut lumen.

Aedes aegypti Rhesus glycoproteins contribute to ammonia excretion by larval anal papillae

In larval Aedes aegypti, transcripts of the Rhesus-like glycoproteins AeRh50-1 and AeRh50-2 have been detected in the anal papillae, sites of ammonia (NH₃/NH₄⁺) excretion; however, these putative ammonia transporters have not been previously localized or functionally characterized. In this study, we show that the AeRh50s co-immunolocalize with apical V-type H⁺-ATPase as well as with basal Na⁺/K⁺-ATPase in the epithelium of anal papillae. The double-stranded RNA-mediated knockdown of AeRh50-1 and AeRh50-2 resulted in a significant reduction in AeRh50 protein abundance in the anal papillae, and this was coupled to decreased ammonia excretion. The knockdown of AeRh50-1 resulted in decreased hemolymph [NH₄⁺] and pH whereas knockdown of AeRh50-2 had no effect on these parameters. We conclude that the AeRh50s are important contributors to ammonia excretion at the anal papillae of larval A. aegypti, which may be the basis for their ability to inhabit areas with high ammonia levels.

Brain and intestinal expression of galanin-like peptide (GALP), galanin receptor R1 and galanin receptor R2, and GALP regulation of food intake in goldfish (Carassius auratus)

Galanin-like peptide (GALP) is a 60 amino acid neuropeptide originally discovered from porcine hypothalamus, and is involved in the regulation of food intake in mammals. Since its discovery, GALP and its receptors (GALR1 and GALR2) have been characterized in mammals, but no publications are available on GALP in fish and other non-mammals. The present study aimed to characterize brain and intestinal GALP and its receptors using immunohistochemistry in a teleost, the goldfish (Carassius auratus), and to study its effects on feeding behavior. Immunostaining of brain sections shows the presence of GALP- and GALR1- and GALR2-like immunoreactive cells in different encephalic areas, including the telencephalon, some hypothalamic nuclei, the optic tectum, the torus longitudinalis and the cerebellum. Signal for GALP was also observed in the fasciculus retroflexus. In the gut, GALP-and GALR1 and GALR2 immunoreactive cells were detected in the mucosa. Results from the feeding study demonstrate that intracerebroventricular administration of GALP (1ng/g bodyweight) increases goldfish food intake at 1h post-injection. These observations form the first report on the presence of GALP in the fish brain and gut, and also on its modulatory role on fish feeding behavior. GALP, as in mammals, appears to be a functional neuropeptide in goldfish.

A 5-D Implementation of FGM for the Large Eddy Simulation of a Stratified Swirled Flame with Heat Loss in a Gas Turbine Combustor

Numerical simulations are foreseen to provide a tremendous increase in gas-turbine burners efficiency in the near future. Modern developments in numerical schemes, turbulence models and the consistent increase of computing power allow Large Eddy Simulation (LES) to be applied to real cold flow industrial applications. However, the detailed simulation of the gas-turbine combustion process remains still prohibited because of its enormous computational cost. Several numerical models have been developed in order to reduce the costs of flame simulations for engineering applications. In this paper, the Flamelet-Generated Manifold (FGM) chemistry reduction technique is implemented and progressively extended for the inclusion of all the combustion features that are typically observed in stationary gas-turbine combustion. These consist of stratification effects, heat loss and turbulence. Three control variables are included for the chemistry representation: the reaction evolution is described by the reaction progress variable, the heat loss is described by the enthalpy and the stratification effect is expressed by the mixture fraction. The interaction between chemistry and turbulence is considered through a presumed beta-shaped probability density function (PDF) approach, which is considered for progress variable and mixture fraction, finally attaining a 5-D manifold. The application of FGM in combination with heat loss, fuel stratification and turbulence has never been studied in literature. To this aim, a highly turbulent and swirling flame in a gas turbine combustor is computed by means of the present 5-D FGM implementation coupled to an LES turbulence model, and the results are compared with experimental data. In general, the model gives a rather good agreement with experimental data. It is shown that the inclusion of heat loss strongly enhances the temperature predictions in the whole burner and leads to greatly improved NO predictions. The use of FGM as a combustion model shows that combustion features at gas turbine conditions can be satisfactorily reproduced with a reasonable computational effort. The implemented combustion model retains most of the physical accuracy of a detailed simulation while drastically reducing its computational time, paving the way for new developments of alternative fuel usage in a cleaner and more efficient combustion.

FLUID AND ION SECRETION BY MALPIGHIAN TUBULES OF LARVAL CHIRONOMIDS, Chironomus riparius: EFFECTS OF REARING SALINITY, TRANSPORT INHIBITORS, AND SEROTONIN

Larvae of Chironomus riparius respond to ion-poor and brackish water (IPW, BW) conditions by activating ion uptake mechanisms in the anal papillae and reducing ion absorption at the rectum, respectively. The role that the Malpighian tubules play in ion and osmoregulation under these conditions is not known in this species. This study examines rates of fluid secretion and major cation composition of secreted fluid from tubules of C. riparius reared in IPW, freshwater (FW) and BW. Fluid secretion of tubules from FW and BW larvae was similar but tubules from IPW larvae secrete fluid at higher rates, are more sensitive to serotonin stimulation, and the secreted fluid contains less Na(+) . Therefore in IPW, tubules work in concert with anal papillae to eliminate excess water while conserving Na(+) in the hemolymph. Tubules do not appear to play a significant role in ion/osmoregulation under BW. Serotonin immunoreactivity in the nervous system and gastrointestinal tract of larval C. riparius was similar to that seen in mosquito larvae with the exception that the hindgut was devoid of staining. Hemolymph serotonin titer was similar in FW and IPW; hence, serotonin is not responsible for the observed high rates of fluid secretion in IPW. Instead, it is suggested that serotonin may work in a synergistic manner with an unidentified hormonal factor in IPW. Ion transport mechanisms in the tubules of C. riparius are pharmacologically similar to those of other insects.

Extended lymphadenectomy in elderly and/or highly co-morbid gastric cancer patients: A retrospective multicenter study

BACKGROUND

Gastrectomy with extended lymphadenectomy is considered the gold standard treatment for advanced gastric cancer, with no age- or comorbidity-related limitations. We evaluated the safety and efficacy of curative gastrectomy with extended nodal dissection, verifying survival in elderly and highly co-morbid patients.

METHODS

In a retrospective multicenter study, we examined 1322 non-metastatic gastric-cancer patients that underwent curative gastrectomy with D2 versus D1 lymphadenectomy from January 2000 to December 2009. Postoperative complications, overall survival (OS), and disease-specific survival (DSS) according to age and the Charlson Comorbidity Score were analyzed in relation to the extent of lymphadenectomy.

RESULTS

Postoperative morbidity was 30.4%. Complications were more frequent in highly co-morbid elderly patients, and, although general morbidity rates after D2 and D1 lymphadenectomy were similar (29.9% and 33.2%, respectively), they increased following D2 in highly co-morbid elderly patients (39.6%). D2-lymphadenectomy significantly improved 5-year OS and DSS (48.0% vs. 37.6% in D1, p < 0.001 and 72.6% vs. 58.1% in D1, p < 0.001, respectively) in all patients. In elderly patients, this benefit was present only in 5-year DSS. D2 nodal dissection induced better 5-year OS and DSS rates in elderly patients with positive nodes (29.7% vs. 21.2% in D1, p = 0.008 and 47.5% vs. 30.6% in D1, p = 0.001, respectively), although it was present only in DSS when highly co-morbid elderly patients were considered.

CONCLUSION

Extended lymphadenectomy confirmed better survival rates in gastric cancer patients. Due to high postoperative complication rate and no significant improvement of the OS, D1 lymphadenectomy should be considered in elderly and/or highly co-morbid gastric cancer patients.

Factors influencing survival after hepatectomy for metastases from gastric cancer

PURPOSE

To investigate clinical factors influencing the prognosis of patients submitted to hepatectomy for metastases from gastric cancer and their clinical role.

METHODS

Retrospective multi-center chart review. We evaluated how survival from surgery was influenced by patient-related, gastric cancer-related, metastasis-related and treatment-related candidate prognostic factors.

RESULTS

One hundred and five patients submitted to hepatectomy for metastases from gastric cancer, in the synchronous and metachronous setting of the disease. In 89 cases a R0 resection was achieved, while in 16 a R+ hepatic resection was performed. Adjuvant chemotherapy was administered to 29 patients. Surgical mortality was 1% and morbidity 13.3%. Median disease-free survival was 10 months, median overall survival was 14.6 months. Overall 1, 3, and 5-year survival rates were 58.2%, 20.3%, and 13.1%, respectively. Survival was influenced independently by the factor T of the gastric primary (p < 0.001), by the curativity of surgical procedure (p = 0.001), by the timing of hepatic involvement (p < 0.001) and by adjuvant chemotherapy (p < 0.001). T4 gastric cancer, R+ resection, synchronous metastases, and abstention from adjuvant chemotherapy were associated with a worse prognosis; T4 gastric cancer and R+ resections displayed a cumulative effect (p < 0.001).

CONCLUSIONS

Our data show that R0 resection must be pursued whenever possible. Furthermore, in the synchronous setting, the coexistence of T4 gastric primaries and R+ resections suggests prudence and probably abstention from hepatectomy. Finally, a multimodal treatment associating surgery and chemotherapy offers the best survival results.