Phytoplankton composition and spatial distribution of copper and zinc in the Fal Estuary (Cornwall,UK)

In the estuaries near Falmouth (Cornwall, UK) levels of dissolved copper and zinc are high, due to drainage of copper and tin mines. Phytoplankton species composition in the autumn of 1989 deviated in the metal-contaminated Restronguet Creek from that in other estuarine branches,viz. Fal, Tresillian and Percuil. In the riverine part of Restronguet Creek (Carnon River)Euglena mutabilis, known as an acidophilic (pH 3) metal-resistant flagellate, occurred at micromolar Cu and Zn, whereas in the clean riversChlamydomonas sp. andOocystis sp. occurred at nanomolar Cu and Zn. An ordination analysis revealed the following patterns in Cu, Zn and phytoplankton species composition in the poly- and euhaline waters. Seston-bound Zn and dissolved Zn were in equilibrium,Katodinium rotundatum is Zn-tolerant, andSkeletonema costatum occurred in water with high contents of Cu in seston. However, none of the variables in these patterns correlated at a significant level (p>0.05). The results show that algae-metal interactions are complicated, and that statistical correlations foundin situ need experimental verification.Communication no. 542 of the Delta Institute for Hydrobiological Research.     

Circannual Growth Rhythm in a Brown Alga,Pterygophora californica

A circannual rhythm was found in the kelp Pterygophora californica which forms a new blade with a free running period of 7 ? 8 months under constant conditions. Individual plants exposed to cycles of daylength with T = 12, 6, or 3 months performed 1, 2, or 4 growth cycles, respectively, in one calendar year showing the entrainment of the endogenous circannual rhythm. The annual growth cycle also followed a phase shift of the annual cycle of daylength (T = 12 months) by 3 or 6 months.     

Crystals of the complex between human growth hormone and the extracellular domain of its receptor.

Single crystals suitable for high-resolution diffraction studies have been grown of the human growth hormone (hGH) complexed to the extracellular domain of its cloned receptor from the human liver (hGHbp), using the technique of repeat seeding. The crystals are in space group P2(1)2(1)2, with a = 145.8 A, b = 68.6 A, c = 76.0 A, and diffract to at least 2.7 A resolution on a rotating anode X-ray source. Analysis of the composition of these crystals showed the stoichiometry of the complex to be hGH: (hGHbp)2. This finding, coupled with biochemical data on the complex in solution, indicates that the biologically significant dimerization of the growth hormone receptor is mediated through a single hormone molecule. Structure determination of the complex is currently being completed.     

Certain biochemical characteristics of an insulin-like substance from the bivalve mollusk Anodonta cygnea

An insulin-like substance (ILS) was isolated from the visceral organs of the bivalve mollusc Anodonta cygnea by chromatography on a sulfocationite CU-23 and purified by reverse phase liquid chromatography. ILS was shown to be made up to several fractions with Mr ranging from 9 to 20 kDa which have identical amino acid composition but different hydrophobicity and N-terminal amino acids. It was supposed that the heterogeneity of ILS fractions is due to its genetical or posttranslational polymorphism. ILS has a low (0.02%) affinity for the mammalian insulin receptor and a low immune affinity for mammalian insulin and possesses a mitogenic activity which is commensurate with that of the epidermal growth factor. The data obtained suggest that Anodonta cygnea ILS represents a separate branch of a relatively ancient family of insulin-like hormones and growth factors responsible for metabolism and proliferation of invertebrate tissues.     

Effects of amiprilose hydrochloride on the components of human skin equivalents

Summary Amiprilose hydrochloride has been shown to inhibit the proliferation of a number of hyperproliferative cell types including psoriatic skin cells. In the present study, the effects of amiprilose hydrochloride on human tissue equivalents were examined by incubating a) dermal equivalents, b) skin equivalents in the process of epidermalization, and c) mature skin equivalents, with varying concentrations of the drug. In all three models amiprilose hydrochloride concentrations of 0.1% (wt/vol) and lower were not toxic to fibroblasts and keratinocytes and did not interfere with the differentiation of the skin equivalent and the developing skin equivalent. When tested in dermal equivalents, concentrations of amiprilose hydrochloride between 0.1 and 0.5% resulted in changes in fibroblast morphology with development of large intracellular vacuoles, and concentrations greater than 5% were toxic. In mature skin equivalents, in addition to changes in fibroblast morphology, amiprilose hydrochloride in concentrations of 1 to 10% affected the epidermis. When 0.5% amiprilose hydrochloride was present in the developing skin equivalent during differentiation, the epidermal keratinocytes were also affected. Thus the morphology of basal keratinocytes was modified, the differentiation was incomplete, and the dermalepidermal attachment was compromised. These studies suggest the possibility of an extracellular mechanism of action of amiprilose hydrochloride and delineate acceptable dosage ranges for the potential drug. Supported in part by research grant AG01274 from the National Institutes of Health, Bethesda, MD, The R. A. Welch Foundation (B0502), The Texas Advanced Technology and Research Program (Wound Healing and Aging no. 2147), and Greenwich Pharmaceuticals, Inc. R. W. G. is the recipient of a MERIT award from the National Institute on Aging, Bethesda, MD.     

DNA of some anaerobic rumen fungi: G + C content determination

The nuclear DNAs from five species of anaerobic rumen fungi have been isolated and purified by means of two extraction methods (with and without 8 M urea). Their G + C contents have been characterized by the thermal denaturation procedure of Marmur and Doty. As has already been shown in Neocallimastix frontalis, the results obtained by the two techniques demonstrated a very low G + C content (less than 20%) and the constant presence of satellite DNA.     

The function of the microsomal oxidative system of different organs in guinea pigs administered ethanol

The microsomal cytochrome content and enzyme activity has been determined in liver, kidney, lungs and intestinal mucous from guinea pig males which were injected 25% ethanol intraperitoneally at a dose of 2 g per 1 kg of body mass. The changes in cytochrome P-450 and b5 content, amidopyrine-N-demethylase, aniline hydroxylase, p-nitrophenol hydroxylase. NADP.H-cytochrome-c-reductase activities in investigated organs of the animals have been found depending on the ethanol intoxication period (for 3, 6 or 14 days). Changes of the same type in microsomal enzyme activities have been discovered in liver, lungs and intestine, but not in kidney that is accounted for the substrate specificity and inducibility of the cytochrome P-450 some forms in extrahepatic tissues.