SIN3 is a component of a histone deacetylase complex known to be important for transcription repression. While multiple isoforms of SIN3 have been reported, little is known about their relative expression or role in development. Using a combination of techniques, we have determined that SIN3 is expressed throughout the Drosophila life cycle. The pattern of expression for each individual isoform, however, is distinct. Knock down of all SIN3 expression reveals a requirement for this protein in embryonic and larval periods. Taken together, the data suggest that SIN3 is required for multiple developmental events during the Drosophila life cycle. Developmental Dynamics 237:3040 -3050, 2008.

The possible role of Na+-Ca2+ exchange in contributing to depolarization-induced increase in cytosolic Ca2+ concentration ([Ca2+]i) of isolated rat ventricular myocytes was investigated. Measured with the Ca2+-sensitive indicator quin 2, [Ca2+]i increased from 177 +/- 12 (mean +/- SE, n = 11) to 468 +/- 41 nM when cells were depolarized with solutions containing 50 mM KCl [high extracellular K+ concentration ([K+]o)]. Approximately 73% of this high-[K+]o-induced increase in [Ca2+]i was abolished by the Ca2+ channel blocker verapamil (5 microM). For cells pretreated with 10 mM caffeine to deplete the Ca2+ stored in sarcoplasmic reticulum, 50 mM KCl still produced an increase in [Ca2+]i, even in the presence of 5 microM verapamil. However, if extracellular Na+ was replaced by Li+ or tris(hydroxymethyl)aminomethane, this increase was completely abolished. The results suggest that, in addition to voltage-sensitive Ca2+ channels, voltage-sensitive Na+-Ca2+ exchange can also contribute to the increase in [Ca2+]i on depolarization. Therefore both Ca2+ transport systems may play important roles in regulating cardiac excitation and contraction.

Salinity, one of the most deleterious stresses, affects growth and overall yield of crop plants. To identify new "candidate genes" having potential role in salinity tolerance, we have carried out 'functional screening' of a cDNA library (made from a salt tolerant rice-Pokkali). Based on this screening, we identified a cDNA clone that was allowing yeast cells to grow in the presence of 1.2 M NaCl. Sequencing and BLAST search identified it as mannose-1-phosphate guanyl transferase (OsMPG1) gene from rice. Analysis of rice genome sequence database indicated the presence of 3 additional genes for MPG. Out of four, three MPG genes viz. OsMPG1, 3 and 4 were able to functionally complement yeast MPG mutant -YDL055C. We have carried out detailed transcript profiling of all members of MPG family by qRT-PCR using two contrasting rice genotypes (IR64 and Pokkali) under different abiotic stresses (salinity, drought, oxidative stress, heat stress, cold or UV light). These MPG genes showed differential expression under various abiotic stresses with two genes (OsMPG1 and 3) showing high induction in response to multiple stresses. Analysis of rice microarray data indicated higher expression levels for OsMPG1 in specific tissues such as roots, leaves, shoot apical meristem and different stages of panicle and seed development, thereby indicating its developmental regulation. Functional validation of OsMPG1 carried out by overexpression in the transgenic tobacco revealed its involvement in enhancing salinity stress tolerance.

Here we provide the first genome-wide in vivo analysis of the Na + /Ca 2+ exchanger family in the model system Caenorhabditis elegans. We source all members of this family within the Caenorhabditis genus and reconstruct their phylogeny across humans and Drosophila melanogaster. Next, we provide a description of the expression pattern for each exchanger gene in C. elegans, revealing a wide expression in a number of tissues and cell types including sensory neurons, interneurons, motor neurons, muscle cells, and intestinal tissue. Finally, we conduct a series of behavioral and functional analyses through mutant characterization in C. elegans.From these data we demonstrate that, similar to mammalian systems, the expression of Na + /Ca 2+ exchangers in C. elegans is skewed toward excitable cells, and we propose that C. elegans may be an ideal model system for the study of Na + /Ca 2+ exchangers.C ALCIUM functions as a diverse signaling molecule in a variety of cell types through activation and conformational changes of proteins, as well as via modulation of cellular capacitance (Berridge et al. 2000(Berridge et al. , 2003Bootman et al. 2001). Neurotransmitter release, muscular contraction, apoptosis, and lymphocyte activation are some of the many cellular processes mediated by calcium signaling, and accordingly, strict balance of calcium levels must be maintained to prevent cellular dysfunction. Cells accomplish this primarily by extruding calcium through plasma membraneembedded plasma membrane Ca 2+ ATPase (PMCA) pumps and utilizing exchanger ion transporters. PMCA proteins are high-affinity/low-capacity pumps that maintain calcium homeostasis over sustained periods of time by removing one Ca 2+ ion for every ATP hydrolyzed (Tidow et al. 2012). Exchangers such as Na + /Ca 2+ exchangers (NCX), Na + /Ca 2+ /K + exchangers (NCKX), and calcium/cation exchangers (CCX) are low-affinity/high-capacity ion transporters that rapidly expel calcium ions (Philipson and Nicoll 2000;Philipson et al. 2002;Lytton 2007;Nicoll et al. 2013). The NCX, NCKX, and CCX families of exchangers comprise the three branches of the family of Na + /Ca 2+ exchangers in animals (Cai and Lytton 2004a,b;Lytton 2007). Under normal physiological conditions, NCX ion transporters utilize the energy stored in the transmembrane gradient to allow influx of three Na + ions and extrusion of one Ca 2+ ion (Hilge 2012;Ottolia and Philipson 2013). In the case of the NCKX transporter, there is one Ca 2+ and one K + ion exchanged in return for Na + ion influx, and in the case of the CCX exchangers, both Na + /Ca 2+ and Li + /Ca 2+ exchanges have been observed (Lytton. 2007;Visser and Lytton 2007). As of yet, the nematode Caenorhabditis elegans has not been used as an in vivo model organism to study the NCX, NCKX, CCX exchanger family. Here we provide a detailed description of the phylogeny of this family of transporters in C. elegans, examine the expression patterns of each member, and uncover roles for one NCX member and one CCX member in muscle contracti...

Maintenance of calcium homeostasis is necessary for the development and survival of all animals. Calcium ions modulate excitability and bind effectors capable of initiating many processes such as muscular contraction and neurotransmission. However, excessive amounts of calcium in the cytosol or within intracellular calcium stores can trigger apoptotic pathways in cells that have been implicated in cardiac and neuronal pathologies. Accordingly, it is critical for cells to rapidly and effectively regulate calcium levels. The Na(+) /Ca(2+) exchangers (NCX), Na(+) /Ca(2+) /K(+) exchangers (NCKX), and Ca(2+) /Cation exchangers (CCX) are the three classes of sodium calcium antiporters found in animals. These exchanger proteins utilize an electrochemical gradient to extrude calcium. Although they have been studied for decades, much is still unknown about these proteins. In this review, we examine current knowledge about the structure, function, and physiology and also discuss their implication in various developmental disorders. Finally, we highlight recent data characterizing the family of sodium calcium exchangers in the model system, Caenorhabditis elegans, and propose that C. elegans may be an ideal model to complement other systems and help fill gaps in our knowledge of sodium calcium exchange biology.

Survival and growth of tiger shrimp (Penaeus monodon) at three salinity levels, 5, 10 and 15 g/L were investigated in potassium deficient natural inland saline water (PD-ISW) and potassium supplemented inland saline water (PS-ISW). Shrimps reared in PS-ISW survived well, whereas total mortality occurred in PD-ISW. The survival at 45 and 60 days at the salinities of 5, 10 and 15 g/L was assessed in PS-ISW. The supplementation of potassium showed significant effect on the survival rates at different salinities. Length-weight studies at different salinities and periods of time in PS-ISW showed significant differences in the linear component, but there was no significant difference in respect to interaction of salinity and rearing periods in a two-way ANOVA repeated measures. Growth parameters indicated that a salinity of 10 g/L was best for the survival and growth of shrimps in inland saline water of the site with potassium supplementation. Individual cations and ratios between other cations were found to be equally important for survival and growth. The results of the present study will be useful in utilizing degraded ISW sites for the culture of tiger shrimp.

We characterized the Na(+)-sensitive dye benzofuran isophthalate (SBFI) with fluorescence microscopy in isolated, adult rat ventricular myocytes. When cells were loaded with SBFI by incubation with 10 microM of the acetoxymethyl ester, fluorescence excitation spectra were markedly attenuated below 340 nm and the isoemissive point was blue shifted by approximately 25 nm when compared with spectra from SBFI acid in buffered solutions. Fluorescence intensity (49 +/- 3%) was partially released by permeabilization of the sarcolemma with digitonin, suggesting that one-half of the dye molecules are sequestered subcellularly in a compartment shown most likely to be mitochondrial. Intracellular Na+ concentration ([Na+]i) was determined by in situ calibration using cation-selective ionophores and was found to be 14 +/- 2 mM in cells studied at 37 degrees C. The relative importance of Na+ efflux mechanisms in myocytes was investigated. Substitution of Ca2+ and Mg2+ with EGTA in the superfusing medium resulted in a reversible rise of [Na+]i from 13 +/- 2 to 31 +/- 5 mM, which was blocked by 1 microM verapamil. Cellular efflux of Na+ after loading in this manner was found to be insensitive to blockade of Na(+)-Ca2+ exchange but was abolished when Na(+)-K(+)-ATPase was inhibited with zero extracellular K+ concentration. We conclude that SBFI can be used to measure [Na+]i in ventricular cells nondestructively and without impalement. Na+ efflux after loading by Ca2+ and Mg2+ withdrawal is mediated by the Na+ pump with no measurable contribution from Na(+)-Ca2+ exchange.

NCLX is a Na/Ca exchanger that uses energy stored in the transmembrane sodium gradient to facilitate the exchange of sodium ions for ionic calcium. Mammals have a single NCLX, which has been shown to function primarily at the mitochondrion and is an important regulator of neuronal physiology by contributing to neurotransmission and synaptic plasticity. The role of NCLX in developmental cell patterning ( in neural circuits) is largely unknown. Here we describe a novel role for the NCLX-type protein, NCX-9, in neural circuit formation. NCX-9 functions in hypodermal seam cells that secrete the axon guidance cue UNC-129/BMP, and our data revealed that mutant animals exhibit development defects in stereotyped left/right axon guidance choices within the GABAergic motor neuron circuit. Our data also implicate NCX-9 in a LON-2/heparan sulfate and UNC-6/netrin-mediated, RAC-dependent signaling pathway to guide left/right patterning within this circuit. Finally, we also provide physiology data supporting the role for NCX-9 in handling calcium exchange at the mitochondrion. Taken together, our work reveals the specificity by which the handling by NCLX of calcium exchange can map to neural circuit patterning and axon guidance decisions during development.