Compatible intracellular ion composition of the host improves carbon assimilation by zooxanthellae in mutualistic symbioses.

Cytosymbiotic algae within the host's plasma are exposed to completely different ionic conditions than microalgae living in the sea. The altered ionic gradients, in particular, could be the reason for higher in hospite carbon assimilation levels. To study the effect of varying extracellular ionic conditions on isolated zooxanthellae, their photosynthetic capacity in pure seawater was compared to that in a test medium in which the concentrations of the major inorganic ions, the pH and the osmolality were adjusted to the conditions measured in the host cytoplasm.

Improvement of photosynthesis in zooxanthellate corals by autofluorescent chromatophores.

Autofluorescent chromatophores were detected in 17 out of 71 zooxanthellate coral species studied. Chromatophores are localized either in the oral gastrodermic (endoderm) or oral epidermis (ectoderm). The pigment granules within the chromatophores (0.

Characterization of rat liver nuclear proteins which recognize the cAMP responsive element.

1. The data herein reveal the existence of cAMP-responsive element (CRE)-binding factors (CRF) in the nuclear extracts from cAMP-treated rat liver. 2.

Interaction of a nuclear factor 1-like protein with a cAMP response element-binding protein in rat liver.

1. The existence of both cAMP-responsive element binding factor and a nuclear factor 1-like (NF-1-like) protein in nuclear extracts from liver of cAMP-treated rat has been revealed. 2.

Functional recognition of the neuronal tyrosine hydroxylase cAMP regulatory element in different cell types.

Transient transfection of pLB2CAT constructs bearing short synthetic oligonucleotides derived either from the tyrosine hydroxylase (TH) promoter or other sources was used to examine functional cAMP regulatory element (CRE) activity in a variety of cell lines. The region containing only the putative TH CRE was found to be as or more effective in conferring cAMP responsiveness onto pLB2CAT (which employs the TK promoter) than the immediate 272 bp region of the TH promoter. Increases in CAT activity of 10- to 20-fold were observed in JEG-3 cells with a single insert of the TH CRE region (-31 to -54) in pLB2CAT, and the presence of a second insert generated only a modest further increase.

Evidence for a cAMP-dependent nuclear factor capable of interacting with a specific region of a eukaryotic gene.

Nuclear extracts prepared from the livers of rats treated with or without 8-bromo-cAMP were tested for their ability to bind to various fragments from the flanking region of the gene encoding phosphoenolpyruvate carboxykinase (GTP) [GTP: oxaloacetate carboxy-lyase (transphosphorylating), EC 4.1.1.

Cyclic adenonosine monophosphate does not affect the stability of the messenger ribonucleic acid for tyrosine aminotransferase in cultured hepatoma cells.

Cyclic AMP has been shown to stimulate synthesis of tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.

Progesterone decreases DNA binding factor activity and the expression in Xenopus oocytes of a cAMP responsive gene from rat liver.

Stage VI Xenopus oocytes were injected with a plasmid (pBB0.6-CAT) which contains the cAMP regulatory element (CRE) from the rat liver phosphoenolpyruvate carboxykinase (PEPCK) gene fused upstream from a reporter gene [chloramphenicol acetyltransferase (CAT)]. Inhibition of the expression of the reporter gene (average = 51%) was observed in the presence of 10 microM progesterone, which is known to lead to inactivation of the oocyte cAMP dependent protein kinase (A kinase).

Photoecology of the coral Leptoseris fragilis in the Red Sea twilight zone (an experimental study by submersible).

Depth-dependent photoadaptational responses of the Red Sea zooxanthellate coral (Leptoseris fragilis) were studied down to 160 m from the research submersible GEO. Light saturation curves for photosynthesis revealed, with I =1-2, I =10.9 and I =20 μE·cm·sec, the lowest values of photokinetic parameters ever reported for a symbiotic coral.

In vitro phosphorylation of 4-aminobutyrate aminotransferase by cAMP dependent protein kinase.

Highly purified 4-aminobutyrate aminotransferase from pig brain is susceptible to phosphorylation by the purified cAMP-dependent protein kinase catalytic subunit. Up to 0.7 moles of phosphate from ATP-(gamma)-32P can be incorporated per mole of dimeric holoenzyme.

On the role of protein kinase subunits in the control of eukaryotic gene expression.

Transcriptional regulation by cAMP has been demonstrated for several eukaryotic genes; however, the identity of the protein kinase subunit involved has been a source of debate. Based on homologies with the procaryotic cAMP-binding catabolite activator protein, a recent hypothesis has invoked the regulatory protein RII as the mediator. The evidence currently available on the effects of microinjected kinase subunits suggests, however, that the catalytic subunit is the active factor.

Is cyclic AMP dependent protein kinase responsible for the in vivo phosphorylation of tyrosine aminotransferase?

Undegraded tyrosine aminotransferase was purified to near homogeneity from rat liver and was confirmed to be a substrate for the beef heart cyclic AMP dependent protein kinase catalytic subunit. Specific antibody was used to quantitate the amount of phosphate incorporated into the enzyme. Phosphate incorporation was maximal at a catalytic subunit to tyrosine aminotransferase molar ratio of 7:1 using 200 microM ATP for 30 to 60 min at 30 degrees C.

Direct evidence that the protein kinase catalytic subunit mediates the effects of cAMP on tyrosine aminotransferase synthesis.

The effect of purified beef heart cAMP-dependent protein kinase catalytic subunit on tyrosine aminotransferase activity in intact cultured rat H35 hepatoma cells was directly tested by micro-injection using human red blood cell ghosts as vehicles. Although the micro-injection procedure itself produced temporary fluctuations in protein synthesis and in tyrosine aminotransferase activity in H35 cells, after a recovery period of 8-12 h, these parameters returned to normal in parallel with restoration of full inducibility of the aminotransferase by both 8-Br-cAMP and dexamethasone. Eight to sixteen hours after fusion of H35 cells with unloaded ghosts, ghosts loaded with bovine serum albumin or mock-loaded with the partially purified protein kinase catalytic subunit, no significant change in the activity of the aminotransferase was detected.

Cyclic nucleotide-dependent protein kinases and some major substrates in the rat cerebellum after neonatal X-irradiation.

The levels of cAMP-dependent protein kinase (type I), or cGMP-dependent protein kinase, or protein I, and of a 23,000 MW substrate for the cGMP-dependent protein kinase were measured in cerebella from normal rats and in the cerebella from rats in which a selective loss of interneurons in the cerebellar cortex had been produced by X-irradiation. A decrease was observed in the concentrations of cAMP-dependent protein kinase and of protein I, whereas an increase was observed in the concentrations of cGMP-dependent protein kinase and of the 23,000 MW substrate. The data, taken together with the results of other studies, support the interpretation that cAMP-dependent protein kinase and protein I are distributed throughout the cerebellum, but that cGMP-dependent protein kinase and the 23,000 MW substrate are highly concentrated in Purkinje cells.

Epidermal nutrition of the alcyonarian Heteroxenia fuscescens (Ehrb.): absorption of dissolved organic material and lost endogenous photosynthates.

The trophic strategies were studied of Heteroxenia fuscescens living in shallow tropical waters. Structural and physiological adaptations show that particulate food is of less nutritional importance than the uptake of organic material dissolved in the sea, the utilization of assimilates of cytosymbiotic algae (zooxanthellae) and even the symbionts themselves. The external and internal surfaces of the tentacles are enlarged by featherlike pinnules, on the one hand facilitating the epidermal uptake of dissolved organic compounds and on the other offering wellilluminated spaces in which large numbers of zooxanthellae can be 'cultivated'.

Localization of cyclic GMP-dependent protein kinase and substrate in mammalian cerebellum.

The regional and cellular distribution of guanosine 3',5'-cyclic monophosphate (cGMP)-dependent protein kinase (ATP:protein phosphotransferase,EC 2.7.1.

Interference of inhibitors of dopamine-beta-hydroxylase with uptake of monoamines by chromaffin granular membranes.

Disulfiram and bis-(4-methyl-1-homopiperazinylthiocarbonyl)-disulphide (FLA 63) markedly inhibited the Mg2+/ATP-dependent uptake of various monoamines, e.g. dopamine (DA), by isolated membranes of bovine adrenal chromaffin granules.

[Nutritional and ecological aspects of the uptake of dissolved amino acids by Anemonia sulcata (Coelenterata, Anthozoa)].

Anemonia sulcata resorbs and accumulates tritiated L-amino acids dissolved in sea water in their natural concentrations (70-700 nmol/l).Resorption takes place mainly through the apical membrane of the ectoderm. Even after quite long periods of exposure autoradiography reveals that the amino acids resorbed are located in the ectoderm; this is attributable to its cytological structure.