Immunolocalization of chloride transporters to gill epithelia of euryhaline teleosts with opposite salinity-induced Na+/K+-ATPase responses

Opposite patterns of branchial Na+/K+-ATPase (NKA) responses were found in euryhaline milkfish (Chanos chanos) and pufferfish (Tetraodon nigroviridis) upon salinity challenge. Because the electrochemical gradient established by NKA is thought to be the driving force for transcellular Cl- transport in fish gills, the aim of this study was to explore whether the differential patterns of NKA responses found in milkfish and pufferfish would lead to distinct distribution of Cl- transporters in their gill epithelial cells indicating different Cl- transport mechanisms. In this study, immunolocalization of various Cl- transport proteins, including Na+/K+/2Cl(-) cotransporter (NKCC), cystic fibrosis transmembrane conductance regulator (CFTR), anion exchanger 1 (AE1), and chloride channel 3 (ClC-3), were double stained with NKA, the basolateral marker of branchial mitochondrion-rich cells (MRCs), to reveal the localization of these transporter proteins in gill MRC of FW- or SW-acclimated milkfish and pufferfish. Confocal microscopic observations showed that the localization of these transport proteins in the gill MRCs of the two studied species were similar. However, the number of gill NKA-immunoreactive (IR) cells in milkfish and pufferfish exhibited to vary with environmental salinities. An increase in the number of NKA-IR cells should lead to the elevation of NKA activity in FW milkfish and SW pufferfish. Taken together, the opposite branchial NKA responses observed in milkfish and pufferfish upon salinity challenge could be attributed to alterations in the number of NKA-IR cells. Furthermore, the localization of these Cl- transporters in gill MRCs of the two studied species was identical. It depicted the two studied euryhaline species possess the similar Cl- transport mechanisms in gills

Charmed Exotics in Heavy Ion Collisions

Based on the color-spin interaction in diquarks, we argue that charmed multiquark hadrons are likely to exist. Because of the appreciable number of charm quarks produced in central nucleus-nucleus collisions at ultrarelativistic energies, production of charmed multiquark hadrons is expected to be enhanced in these collisions. Using both the quark coalescence model and the statistical hadronization model, we estimate the yield of charmed tetraquark meson $T_{cc}$ and pentaquark baryon $\Theta_{cs}$ in heavy ion collisions at RHIC and LHC. We further discuss the decay modes of these charmed exotic hadrons in order to facilitate their detections in experiments

Seller’s optimal credit period and replenishment time in a supply chain with up-stream and down-stream trade credits

[[abstract]]In practice, a supplier often offers its retailers a permissible delay period M to settle their unpaid accounts. Likewise, a retailer in turn offers another trade credit period N to its customers. The benefits of trade credit are not only to attract new buyers who consider it a type of price reduction, but also to provide a competitive strategy other than introduce permanent price reductions. On the other hand, the policy of granting credit terms adds an additional cost to the seller as well as an additional dimension of default risk. In this paper, we first incorporate the fact that trade credit has a positive impact on demand but negative impacts on costs and default risks to establish an economic order quantity model for the seller in a supply chain with up-stream and down-stream trade credits. Then we derive the necessary and sufficient conditions to obtain the optimal replenishment time and credit period for the seller. Finally, we use some numerical examples to illustrate the theoretical results.[[incitationindex]]SCI[[booktype]]電子

Genetic insights into resting heart rate and its role in cardiovascular disease.

Resting heart rate is associated with cardiovascular diseases and mortality in observational and Mendelian randomization studies. The aims of this study are to extend the number of resting heart rate associated genetic variants and to obtain further insights in resting heart rate biology and its clinical consequences. A genome-wide meta-analysis of 100 studies in up to 835,465 individuals reveals 493 independent genetic variants in 352 loci, including 68 genetic variants outside previously identified resting heart rate associated loci. We prioritize 670 genes and in silico annotations point to their enrichment in cardiomyocytes and provide insights in their ECG signature. Two-sample Mendelian randomization analyses indicate that higher genetically predicted resting heart rate increases risk of dilated cardiomyopathy, but decreases risk of developing atrial fibrillation, ischemic stroke, and cardio-embolic stroke. We do not find evidence for a linear or non-linear genetic association between resting heart rate and all-cause mortality in contrast to our previous Mendelian randomization study. Systematic alteration of key differences between the current and previous Mendelian randomization study indicates that the most likely cause of the discrepancy between these studies arises from false positive findings in previous one-sample MR analyses caused by weak-instrument bias at lower P-value thresholds. The results extend our understanding of resting heart rate biology and give additional insights in its role in cardiovascular disease development

Ion regulation in fish gills: recent progress in the cellular and molecular mechanisms

Hwang P, Lee T, Lin L. Ion regulation in fish gills: recent progress in the cellular and molecular mechanisms. Am J Physiol Regul Integr Comp Physiol 301: R28-R47, 2011. First published March 30, 2011; doi:10.1152/ajpregu.00047.2011.-Fish encounter harsh ionic/osmotic gradients on their aquatic environments, and the mechanisms through which they maintain internal homeostasis are more challenging compared with those of terrestrial vertebrates. Gills are one of the major organs conducting the internal ionic and acid-base regulation, with specialized ionocytes as the major cells carrying out active transport of ions. Exploring the iono/osmoregulatory mechanisms in fish gills, extensive literature proposed several models, with many conflicting or unsolved issues. Recent studies emerged, shedding light on these issues with new opened windows on other aspects, on account of available advanced molecular/cellular physiological approaches and animal models. Respective types of ionocytes and ion transporters, and the relevant regulators for the mechanisms of NaCl secretion, Na+ uptake/acid secretion/NH4+ excretion, Ca2+ uptake, and Cl uptake/base secretion, were identified and functionally characterized. These new ideas broadened our understanding of the molecular/cellular mechanisms behind the functional modification/regulation of fish gill ion transport during acute and long-term acclimation to environmental challenges. Moreover, a model for the systematic and local carbohydrate energy supply to gill ionocytes during these acclimation processes was also proposed. These provide powerful platforms to precisely study transport pathways and functional regulation of specific ions, transporters, and ionocytes; however, very few model species were established so far, whereas more efforts are needed in other species

Chloride channel ClC-3 in gills of the euryhaline teleost, Tetraodon nigroviridis: expression, localization and the possible role of chloride absorption

Previous studies have reported the mechanisms of ion absorption and secretion by diverse membrane transport proteins in gills of various teleostean species. To date, however, the chloride channel expressed in the basolateral membrane of mitochondrionrich (MR) cells for Cl-uptake in freshwater (FW) fish is still unknown. In this study, the combination of bioinformatics tools [i.e. National Center for Biotechnology Information (NCBI) database, Tetraodon nigroviridis (spotted green pufferfish) genome database (Genoscope), BLAT and BLASTn] were used to identify the gene of ClC-3 (TnClC-3), a member of the CLC chloride channel family in the T. nigroviridis genome. RT-PCR analysis revealed that the gene encoding for the ClC-3 protein was widely expressed in diverse tissues (i.e. gill, kidney, intestine, liver and brain) of FW- and seawater (SW)-acclimated pufferfish. In whole-mount double immunofluorescent staining, branchial ClC-3-like immunoreactive protein was localized to the basolateral membrane of Na(+)/K(+)-ATPase (NKA) immunoreactive cells in both the FW- and SW-acclimated pufferfish. In response to salinity, the levels of transcript of branchial TnClC-3 were similar between FW and SW fish. Moreover, the membrane fraction of ClC-3-like protein in gills was 2.7-fold higher in FW compared with SW pufferfish. To identify whether the expression of branchial ClC-3-like protein specifically responded to lower environmental [Cl(-)], the pufferfish were acclimated to artificial waters either with a normal (control) or lower Cl(-) concentration (low-Cl). Immunoblotting of membrane fractions of gill ClC-3-like protein showed the expression was about 4.3-fold higher in pufferfish acclimated to the low-Cl environment than in the control group. Furthermore, branchial ClC-3-like protein was rapidly elevated in response to acute changes of environmental salinity or [Cl(-)]. Taken together, pufferfish ClC-3-like protein was expressed in the basolateral membrane of gill MR cells, and the protein amounts were stimulated by hyposmotic and low-Cl environments. The enhancement of ClC-3-like protein may trigger the step of basolateral Cl-absorption of the epithelium to carry out iono- and osmoregulatory functions of euryhaline pufferfish gills

Differential responses in gills of euryhaline tilapia, Oreochromis mossambicus, to various hyperosmotic shocks

Euryhaline tilapia (Oreochromis mossambicus) survived in brackish water (BW; 20 parts per thousand) but died in seawater (SW; 35 parts per thousand) within 6 h when transferred directly from fresh water (FW). The purpose of this study was to clarify responses in gills of FW tilapia to various hyperosmotic shocks induced by BW or SW. In FW-acclimated tilapia, scanning electron micrographs of gills revealed three subtypes of MR cell apical surfaces: wavy-convex (subtype I), shallow-basin (subtype II), and deep-hole (subtype III). Density of apical surfaces of mitochondrion-rich (MR) cell in gills of the BW-transfer tilapia decreased significantly within 3 h post-transfer due to disappearance of subtype I cells, but increased from 48 h post-transfer because of increasing density of subtype III cells. SW-transfer individuals, however, showed decreased density of MR cell openings after 1 h post-transfer because subtype I MR cell disappeared. On the other hand, relative branchial Na(+)/K(+)-ATPase (NKA) alpha 1-subunit mRNA levels, protein abundance, and NKA activity of the BW-transfer group increased significantly at 6,12, and 12 h post-transfer, respectively. In the SW-transfer group, relative mRNA and protein abundance of gill NKA alpha 1-subunit did not change while NKA activity declined before dying in 5 h. Upon SW transfer, dramatic increases (nearly 2-fold) of plasma osmolality, [Na(+)], and [Cl(-)] were found prior to death. For the BW-transfer group, plasma osmolality was eventually controlled by 96 h post-transfer by enhancement of NKA expression and subtype III MR cell. The success or failure of NKA activation from gene to functional protein as well as the development of specific SW subtype in gills were crucial for the survival of euryhaline tilapia to various hyperosmotic shocks. (C) 2008 Elsevier Inc. All rights reserved

Constant Muscle Water Content and Renal HSP90 Expression Reflect Osmotic Homeostasis in Euryhaline Teleosts Acclimated to Different Environmental Salinities

Cheng-Hao Tang, Ching-San Tzeng, Lie-Yueh Hwang, and Tsung-Han Lee (2009) Constant muscle water content and renal HSP90 expression reflect osmotic homeostasis in euryhaline teleosts acclimatized to different environmental salinities. Zoological Studies 48(4): 435-441. Changes in environmental salinities trigger osmoregulatory mechanisms of euryhaline teleosts in order to maintain the plasma osmolality and water balance. The kidneys are the osmoregulatory organ inside the body which perform ion re-absorption and water regulation. Heat shock proteins (HSPs) are also known as stress proteins, with HSP90 as one of the major classes of HSPs essential for living eukaryotes because it is responsible for the repair and refolding of damaged proteins. In the present study, euryhaline tilapia (Oreochromis mossambicus), spotted green pufferfish (Tetraodon nigroviridis), and milkfish (Chanos chanos), with respective primary natural habitats of freshwater lakes, estuaries, and the sea, were acclimated to fresh water (FW), brackish water (BW; 15 parts per thousand salinity), and seawater (SW; 35 parts per thousand salinity). The muscle water content (MWC) and relative protein amounts of HSP90 in the kidneys of the 3 studied species acclimated to different salinity environments were analyzed in this study. The MWC of these 3 euryhaline teleosts revealed no significant changes in FW, BW, and SW. Furthermore, relative protein amounts of renal HSP90 were similar among the 3 studied species acclimated to various environments. The physiological (MWC) and stress (HSP90) responses integrated in this study might be indicators of osmoregulatory capacity, illustrating homeostasis of the internal environments of euryhaline teleosts. http://zoolstud.sinica.edu.tw/Journals/48.4/435.pd

Removal of multiple nitrogenous wastes by Aspergillus niger in a continuous fixed-slab reactor

A biofilter reactor, to which is attached a large variety of microorganisms, can be employed to treat circulating water in an intensive aquaculture system. Some nitrogen-containing wastes, such as ammonium and nitrite, are toxic to the aquatic organisms. The removal rates of the nitrogenous wastes are regarded as indices for the efficiency of treatment by biofilters. In this study, a fungus that was characterized as being able to remediate multiple nitrogenous wastes was identified as Aspergillus niger NBG5. In a continuous fixed-slab reactor, the heterotrophic fungus utilized ammonium, nitrite, protein, and glucose simultaneously. The fungus assimilated ammonium, nitrite and protein at rates of 0.247, 0.07 and 0.096 g-N/g-cell/day, respectively, at 22 degreesC. The remediation rates of ammonium nitrogenous wastes decreased by a factor of eight at 35 degreesC, while the specific growth rates slightly increased. For nitrogenous wastes, ammonium was a preferred substrate but its rate of consumption declined significantly as temperature increased. The nitrogen consumption rates were inconsistent with the cell yields at high temperature. Further analysis of consumption ratios of C/N revealed that cells grew predominantly from the carbon at high temperature. The A. niger NBG5 consumed glucose rapidly at specific rates of 2-2.5 g-C/g-cell/day at 35 degreesC in the presence of ammonium and nitrite; while sluggish consumption of glucose was observed in the protein substrate. The protein could serve as an alternative carbon source. Further ANOVA statistical analysis with P < 0.05 revealed no significant effects of temperature on the specific growth rates of A. niger on the SG-NH4 and milk-protein substrates, whereas significant effects on the ON ratio at culture temperatures higher than 25 degreesC were observed. These findings indicated that the carbon utilization rate increased with high temperature, whereas nitrogen utilization increased as temperature declined. A suitable operational temperature was suggested, depending upon the amount of waste contents of C/N. A high temperature stimulates the use of carbon waste, while a low temperature favors remediation of all nitrogenous wastes. (C) 2003 Elsevier Ltd. All rights reserved