Fast molecular outflow from a dusty star-forming galaxy in the early Universe.

Galaxies grow inefficiently, with only a small percentage of the available gas converted into stars each free-fall time. Feedback processes, such as outflowing winds driven by radiation pressure, supernovae, or supermassive black hole accretion, can act to halt star formation if they heat or expel the gas supply. We report a molecular outflow launched from a dust-rich star-forming galaxy at redshift 5.3, 1 billion years after the Big Bang. The outflow reaches velocities up to 800 kilometers per second relative to the galaxy, is resolved into multiple clumps, and carries mass at a rate within a factor of 2 of the star formation rate. Our results show that molecular outflows can remove a large fraction of the gas available for star formation from galaxies at high redshift.

Author Correction: A massive core for a cluster of galaxies at a redshift of 4.3.

Change history: In this Letter, the Acknowledgements section should have included the following sentence: "The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.". This omission has been corrected online.

A massive core for a cluster of galaxies at a redshift of 4.3.

Massive galaxy clusters have been found that date to times as early as three billion years after the Big Bang, containing stars that formed at even earlier epochs1-3. The high-redshift progenitors of these galaxy clusters-termed 'protoclusters'-can be identified in cosmological simulations that have the highest overdensities (greater-than-average densities) of dark matter4-6. Protoclusters are expected to contain extremely massive galaxies that can be observed as luminous starbursts 7 . However, recent detections of possible protoclusters hosting such starbursts8-11 do not support the kind of rapid cluster-core formation expected from simulations 12 : the structures observed contain only a handful of starbursting galaxies spread throughout a broad region, with poor evidence for eventual collapse into a protocluster. Here we report observations of carbon monoxide and ionized carbon emission from the source SPT2349-56. We find that this source consists of at least 14 gas-rich galaxies, all lying at redshifts of 4.31. We demonstrate that each of these galaxies is forming stars between 50 and 1,000 times more quickly than our own Milky Way, and that all are located within a projected region that is only around 130 kiloparsecs in diameter. This galaxy surface density is more than ten times the average blank-field value (integrated over all redshifts), and more than 1,000 times the average field volume density. The velocity dispersion (approximately 410 kilometres per second) of these galaxies and the enormous gas and star-formation densities suggest that this system represents the core of a cluster of galaxies that was already at an advanced stage of formation when the Universe was only 1.4 billion years old. A comparison with other known protoclusters at high redshifts shows that SPT2349-56 could be building one of the most massive structures in the Universe today.

Galaxy growth in a massive halo in the first billion years of cosmic history.

According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field. Observing these structures during their period of active growth and assembly-the first few hundred million years of the Universe-is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.

Wortmannin inhibits insulin-stimulated activation of protein phosphatase 1 in rat cardiomyocytes.

A major function of insulin in target tissues is the activation of glycogen synthase. Phosphatidylinositol 3-kinase (PI3K) has been implicated in the insulin-induced activation of glycogen synthase, although the true function of this enzyme remains unclear. Data presented here demonstrate that the PI3K inhibitors wortmannin and LY-294002 block the insulin-stimulated activation of protein phosphatase 1 (PP1) in rat ventricular cardiomyocytes. This loss of phosphatase activation mimics that seen in diabetic cardiomyocytes, in which insulin stimulation fails to activate both PP1 and glycogen synthase. Interestingly, in diabetic cells, insulin stimulated PI3K activity to 300% of that in untreated controls, whereas this activity was increased by only 77% in normal cells. PI3K protein levels, however, were similar in normal and diabetic cells. Our results indicate that PI3K is involved in the stimulation of glycogen synthase activity by insulin through the regulation of PP1. The inability of insulin to stimulate phosphatase activity in diabetic cells, despite a significant increase in PI3K activity, suggests a defect in the insulin signaling pathway that contributes to the pathology of insulin-dependent diabetes.

Improved hepatocyte culture system for studying the regulation of glycogen synthase and the effects of diabetes.

When 3-4-week-old rats (young rats) are used as a source of hepatocytes, primary culture cells express the adult, differentiated, liver-specific isoform of glycogen synthase. Synthase enzyme protein levels are relatively stable over a 3 day culture period in young but not in adult (> 150 g rat) hepatocyte cultures. Corresponding synthase enzyme activity and mRNA levels decrease over time in culture in adult but not in young hepatocyte cultures. Young rat hepatocytes also have the ability to proliferate in chemically defined medium in the absence of added mitogens. A diabetes-induced increase in total synthase activity has been demonstrated by our lab and others, using cultured hepatocytes, liver homogenates, and perfused livers. In the present study, utilizing synthase-specific antibody and primary cultures of cells from young normal and alloxan diabetic rats, we found that greater total synthase activity in the diabetic cells was associated with higher levels of enzyme protein. Immuneprecipitation of 35S methionine-labeled freshly plated cells demonstrates an increase in the rate of protein synthesis in diabetic as compared with normal cells. Synthase mRNA levels are correspondingly increased in the diabetic relative to normal cells. Chronic exposure of young, normal hepatocytes to increasing levels of glucose induces a dose-dependent increase in total synthase activity, total synthase protein, and synthase message levels. By comparison, cells from diabetic animals do not respond by any of these measures to increased glucose concentrations. We conclude that this defined primary culture system represents a useful model for investigating the regulation of hepatic glycogen synthase and the defects which occur as a result of diabetes.

Identification and characterization of a gene regulating enzymatic glycosylation which is induced by diabetes and hyperglycemia specifically in rat cardiac tissue.

Primary cardiac abnormalities have been frequently reported in patients with diabetes probably due to metabolic consequences of the disease. Approximately 2,000 mRNA species from the heart of streptozotocin-induced diabetic and control rats were compared by the mRNA differential display method, two of eight candidate clones thus isolated (DH1 and 13) were confirmed by Northern blot analysis. The expression of clone 13 was increased in the heart by 3.5-fold (P < 0.05) and decreased in the aorta by twofold (P < 0.05) in diabetes as compared to control. Sequence analysis showed that clone 13 is a rat mitochondrial gene. DH1 was predominantly expressed in the heart with an expression level 6.8-fold higher in the diabetic rats than in control (P < 0.001). Insulin treatment significantly (P < 0.001) normalized the expression of DH1 in the hearts of diabetic rats. DH1 expression was observed in cultured rat cardiomyocytes, but not in aortic smooth muscle cells or in cardiac derived fibroblasts. The expression in cardiomyocytes was regulated by insulin and glucose concentration of culture media. The full length cDNA of DH1 had a single open-reading frame with 85 and 92% amino acid identity to human and mouse UDP-GlcNAc:Gal beta 1-3GalNAc alpha R beta 1-6 N-acetylglucosaminyltransferase (core 2 GlcNAc-T), respectively, a key enzyme determining the structure of O-linked glycosylation. Transient transfection of DH1 cDNA into Cos7 cells conferred core 2 GlcNAc-T enzyme activity. In vivo, core 2 GlcNAc-T activity was increased by 82% (P < 0.05) in diabetic hearts vs controls, while the enzymes GlcNAc-TI and GlcNAc-TV responsible for N-linked glycosylation were unchanged. These results suggest that core 2 GlcNAc-T is specifically induced in the heart by diabetes or hyperglycemia. The induction of this enzyme may be responsible for the increase in the deposition of glycoconjugates and the abnormal functions found in the hearts of diabetic rats.

Cyclic GMP accumulation in normal and diabetic primary culture adult rat ventricular cardiomyocytes: a minor role for nitric oxide in phosphorylase activation.

The potential role of nitric oxide in the diabetes-induced hypersensitive activation of glycogen phosphorylase by epinephrine was investigated in adult rat ventricular cardiomyocytes. Pretreatment of normal and diabetic-derived cells with 1 mM sodium nitroprusside significantly diminished the phosphorylase activation response by nearly 20% in both normal and diabetic myocytes but failed to alter the hypersensitivity of the diabetic cells. Nitroprusside increased cGMP levels in both normal and diabetic myocytes although the effect was more pronounced in the diabetic cells. Epinephrine did not alter cellular cGMP content and cGMP levels were consistently lower in diabetic myocytes when compared with normal myocytes. Preincubation of ventricular myocytes with the nitric oxide synthase inhibitor L-iminoethyl ornithine did not affect phosphorylase activation. These data indicate that nitric oxide plays a minor role in phosphorylase activation by epinephrine in rat cardiomyocytes and suggest that signal transduction via nitric oxide is not affected by the onset of diabetes.

Identification of the molecular basis for phosphorylase hypersensitivity in cultured diabetic cardiomyocytes.

The focus of this study was to identify the molecular basis for the hypersensitive response of glycogen phosphorylase activation to epinephrine stimulation in alloxan diabetic-derived cardiomyocytes. Cyclic AMP levels were found not to be significantly different between normal and diabetic-derived cells while cGMP concentrations were found consistently to be significantly lower in diabetic-derived cells than in normal cells. Treatment with cyclic GMP analogues did not affect phosphorylase activation by epinephrine in normal cardiomyocytes whereas, IBMX, a nonselective phosphodiesterase inhibitor, had a significant effect on basal and agonist-stimulated phosphorylase activity in both normal and diabetic-derived cardiomyocytes. Differences in the time course for the rate of decay of phosphorylase a from agonist-stimulated to basal levels were observed between normal and diabetic cells. After 3 h in primary culture, phosphorylase a activity returned to basal levels more quickly in normal than in diabetic-derived cells while after 24 h in culture, the time for phosphorylase a decay was not significantly different between normal and diabetic myocytes and was longer than the 3 h response. After 3 h response. After 3 h in primary culture, no significant difference in phosphorylase kinase activity was observed between normal and diabetic-derived cells exposed to epinephrine whereas, after 24 h in culture, phosphorylase kinase activity was significantly decreased in diabetic cells under basal and agonist-stimulation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Transformation of adult ventricular myocytes with the temperature sensitive A58 (tsA58) mutant of the SV40 large T antigen.

Freshly isolated ventricular myocytes have been used extensively as an adult cardiac model system. Due to their inability to undergo cytokinesis in vitro and their dedifferentiated properties in long-term culture, they can not be used for extended studies. Recent reports tell of the establishment of fetal and neonatal cardiac cell lines and the development of adult cardiomyocytes from transgenic animals. A recent report by Kirshenbaum [1], is the first to demonstrate insertion of genes in to adult ventricular myocytes using viral infection. This paper discusses the infection of primary adult differentiated cardiomyocytes with the SV40 large T antigen and subsequent proliferation under temperature sensitive control. Upon further characterization, the cells could be used as a model to study muscle differentiation and repair as well as adult cardiac cell physiology.

Bivariate flow cytometric analysis of p53 and DNA content in hepatocellular carcinoma.

Bivariate flow cytometric analysis of p53 protein and DNA content was studied in archival specimens of hepatocellular carcinoma (HCC) from Chinese patients and corresponding benign liver tissues from a series of 51 patients at Sun Yat-sen University of Medical Sciences. Extracted nuclei were stained with the fluoresceinated monoclonal antibody PAb 1801, which recognizes human p53 protein (mutant and wild types). The nuclei were counterstained with the DNA stain propidium iodide. They were measured on an Ortho FC-200 flow cytometer and the data acquired and analyzed with an IBM 386 personal computer using Kusuda's Get Simple and List Simple software. Of the 51 hepatomas studied, 26 (51%) were p53 positive as compared with 4 (16%) of 24 samples of benign liver tissue from the same patients (P < .0257). The S-phase fraction of p53-positive HCC (12.3 +/- 8.8%) (SD) was significantly greater (P < .05) than for p53-negative HCC (7.4 +/- 7.2%). p53 Expression did not correlate with age, sex, alpha-fetoprotein, hepatitis B surface antigen, tumor size, tumor grade or survival rate. List Simple software permitted analysis of each specimen together with its isotype control (IgG1) on the same cytogram so that p53 expression could be determined separately for the diploid and aneuploid populations of aneuploid tumors and for tumor cells of diploid tumors in the various phases of the cell cycle. Since p53 (PAb 1801) expression can withstand formalin fixation and pepsin treatment of paraffin-embedded tissues, flow cytometric analysis of archival specimens is feasible, and clinical correlations such as these may be carried out in retrospective studies of other tumors.

Factors affecting the activation of glycogen synthase in primary culture cardiomyocytes.

The ability of insulin, IGF-1 and IGF-2 to stimulate the activation of glycogen synthase in the heart was compared under completely defined conditions using primary culture cardiomyocytes. Both insulin and IGF-1 produced similar time- and concentration-dependent activation of glycogen synthase with the maximum stimulation observed at 10-15 min following hormone administration and at > or = 10 nM insulin or IGF-1. IGF-2 was largely ineffective at physiological concentrations. When primary culture cardiomyocytes were incubated with 100 microM palmitate for 2 h and then challenged with various concentrations of insulin or IGF-1, there was a significant decrease in the ability of the cells to activate glycogen synthase. In addition, maintaining cardiomyocytes in hormone deficient culture conditions for 24 or 48 h also resulted in a reduced ability to activate glycogen synthase in response to these hormones. These results suggest that (1) both insulin and IGF-1 are potent regulators of glycogen synthesis in the heart, (2) the enzymes involved in the dephosphorylation (activation) of glycogen synthase are closely linked to both insulin and IGF-1, but not IGF-2 receptor signaling pathways, (3) glycogen synthase activation is adversely affected by the maintenance of cardiomyocytes in the presence of palmitate or for > or = 24 h in hormone deficient media which results in insulin and IGF-1 resistance, and (4) this resistance, like that found in cells from diabetic rats, is due at least in part to a decrease in glycogen synthase phosphatase activity.

Post-receptor defect accounts for phosphorylase hypersensitivity in cultured diabetic cardiomyocytes.

The basis for the hypersensitive response of glycogen phosphorylase to epinephrine stimulation was investigated in adult rat cardiomyocytes isolated from normal and alloxan-diabetic animals. To assess potential G-protein involvement in the response, normal and diabetic derived myocytes were incubated with either cholera or pertussis toxin prior to hormonal stimulation. Pretreatment of cardiomyocytes with cholera toxin resulted in a potentiated response to epinephrine stimulation whereas pertussis toxin did not affect the activation of this signaling pathway. To determine if the enhanced response of phosphorylase activation resulted from an alteration in adenylate cyclase activation, the cells were challenged with forskolin. After 3 hr in primary culture, diabetic cardiomyocytes exhibited a hypersensitive response to forskolin stimulation relative to normal cells. However, after 24 hr in culture, both normal and diabetic myocytes responded identically to forskolin challenge. The present data suggest that a cholera toxin sensitive G-protein mediates the hypersensitive response of glycogen phosphorylase to catecholamine stimulation in diabetic cardiomyocytes and this response which is present in alloxan-diabetic cells and is induced in vitro in normal cardiomyocytes is primarily due to a defect at a post-receptor site.

Adrenergic activation of glycogen phosphorylase in primary culture diabetic cardiomyocytes.

The basis of catecholamine-induced activation of glycogen phosphorylase was investigated in adult rat cardiomyocytes isolated from normal and alloxan-diabetic animals. Cells derived from diabetic animals exhibited a hypersensitive response to epinephrine stimulation that was apparent 3 h after cell isolation and was further enhanced on maintenance of the myocytes in culture for 24 h. Normal cells initially lacked the hypersensitive response to epinephrine stimulation, although on maintenance of these cells in culture for 24 h, the hypersensitive response was acquired in vitro. To assess alpha- and beta-adrenergic mediation of the response, normal and diabetic cardiomyocytes were incubated with propranolol, a beta-blocker, before direct alpha 1-receptor stimulation with phenylephrine. Both normal and diabetic myocytes failed to undergo activation of phosphorylase in 3- or 24-h cell cultures. In addition, the effects of epinephrine on phosphorylase activation were completely inhibited by propranolol, whereas prazosin, an alpha-blocker, was unsuccessful. The present data suggest that the hypersensitive response of glycogen phosphorylase in normal and diabetic cardiomyocytes is solely mediated through beta-adrenergic receptor activation.

The third subunit of protein phosphatase 2A (PP2A), a 55-kilodalton protein which is apparently substituted for by T antigens in complexes with the 36- and 63-kilodalton PP2A subunits, bears little resemblance to T antigens.

The small and middle T (tumor) antigens of polyomavirus have been shown previously to associate with the 36-kDa catalytic subunit and the 63-kDa regulatory subunit of protein phosphatase type 2A, apparently substituting for a normal third 55-kDa regulatory subunit (D.C. Pallas, L.K. Shahrik, B.L. Martin, S. Jaspers, T.B. Miller, D.L. Brautigan, and T.M. Roberts, Cell 60:167-176, 1990). To facilitate a comparison of the normal regulatory subunit and T antigens, we isolated a 2.14-kb cDNA clone encoding this 55-kDa subunit from a rat liver library. Using a probe from the coding region of this gene, we detected a major 2.4-kb mRNA transcript in liver and muscle RNAs. The 55-kDa protein phosphatase 2A subunit purified from rat skeletal muscle generates multiple species when analyzed on two-dimensional gels. Transcription and translation of the clone in vitro produced a full-length protein that comigrated precisely on two-dimensional gels with three of these species, indicating that the 55-kDa protein is apparently modified similarly in vivo and in reticulocyte lysates. Additional species in the purified preparation were not found in the translate, suggesting that there are probably two or more isoforms of this protein in rat muscle. Somewhat surprisingly, there was no clear homology with T-antigen amino acid sequences.

Cellular mechanism of stimulation of renin secretion by the mercurial diuretic mersalyl.

The aim of the present study was to elucidate the cellular mechanism by which the mercurial diuretic mersalyl stimulates renin secretion in rabbit renal cortical slices in vitro. The stimulatory effect of mersalyl on renin secretion was rapid, reversible and concentration dependent. The stimulation was not dependent on the presence of ions such as Na+, Cl- and Ca++, and it was unaffected by inhibitors of Na+/K+/2Cl- cotransport, such as bumetanide and furosemide. However, the stimulation was blocked and reversed by thiols, such as L-cysteine and dithiothreitol. Furthermore, the maximal stimulatory effect of mersalyl on renin secretion was not additive to that produced by the non-diuretic mercurial sulfhydryl reagent P-chloromercuriphenylsulfonate nor to that produced by the non-mercurial diuretic sulfhydryl reagent, ethacrynic acid. These results support the hypothesis that mersalyl stimulates renin secretion by forming a reversible mercaptide bond with sulfhydryl groups, located perhaps on the plasma membrane of juxtaglomerular cells. These particular sulfhydryl groups appear to have no functional role in the diuretic action of mersalyl.

Purification and the immunological characterization of rat protein phosphatase 2A: enzyme levels in diabetic liver and heart.

Protein phosphatase 2A1 was purified from rat skeletal muscle and used to produce antisera to the three subunits of the holoenzyme. Affinity purified antibodies specific for the subunits of the phosphatase enzyme were found to recognize the type 2A1 and 2A2 phosphatase from rat skeletal muscle, heart, liver, brain and erythrocytes and were used to investigate the effects of diabetes on the levels of this enzyme in liver and heart. Phosphorylase phosphatase assays coupled with immunoblot analysis of fractionated rat liver and heart cytosol from normal and diabetic animals show no apparent differences in the quantity or activity of these enzymes following the induction of alloxan diabetes. When considering these results and the normal physiological concentrations of known effectors of these enzymes, it is likely that protein phosphatase 2A1 and 2A2 are not responsible for the dephosphorylation of phosphorylase a under physiological conditions.

An insulin-stimulated kemptide kinase purified from rat liver is deactivated by phosphatase 2A.

Insulin action leads to the rapid stimulation of a cytosolic Kemptide (Leu-Arg-Arg-Ala-Ser-Leu-Gly) kinase (KIK) that has been recently purified to near homogeneity (Klarlund, J. K., Bradford, A. P., Milla, M. G., and Czech, M. P. (1990) J. Biol. Chem. 265, 227-234). To examine its activation mechanism, purified KIK was treated with purified protein phosphatases. The catalytic subunit of phosphatase 2A inhibited the activity of control KIK by about 50% and abolished the 5-fold elevation in KIK activity due to insulin action. The catalytic subunit of phosphatase 1 with equivalent activity based on dephosphorylation of 32P-labeled phosphorylase alpha had no effect on either control or insulin-stimulated KIK activity. The deactivation of insulin-stimulated KIK by phosphatase 2A was time- and concentration-dependent and was blocked by phosphatase inhibitors. The purified native complexes of phosphatase 2A, phosphatase 2A1, and phosphatase 2A2 similarly deactivated KIK. Analyis of control or insulin-stimulated KIK with two antiphosphotyrosine antibodies by immunoblotting and immunoprecipitation failed to detect the presence of phosphotyrosine in the kinase. These results indicate that KIK is activated by phosphorylation as part of a kinase cascade emanating from insulin receptor stimulation.

Stimulation of renin secretion by ethacrynic acid is independent of Na(+)-K(+)-2Cl- cotransport.

This study investigated the cellular mechanism of stimulation of renin secretion by the loop diuretic ethacrynic acid (EA) in rabbit renal cortical slices. The diuretic rapidly stimulated renin secretion reversibly and in a concentration-dependent manner. The stimulation was independent of the presence of Na+, Cl-, Ca2+, or other loop diuretics (furosemide and bumetanide) in the incubation media, suggesting that the stimulation in vitro was not dependent on the inhibitory effect of the diuretic on Na(+)-K(+)-2Cl-cotransport. The findings do not support the macula densa hypothesis. The stimulation by the diuretic was prevented and reversed by thiols such as cysteine and dithiothreitol, which also prevented and reversed the stimulation of renin secretion by the nondiuretic sulfhydryl reagent P-chloromercuriphenyl-sulfonate (PCMPS). These results suggest that EA stimulates renin secretion in vitro via reversible chemical reactions with specific membrane sulfhydryl groups that may have no functional role in the Na(+)-K(+)-2Cl- cotransport.