Linkages between seagrass,mangrove and saltmarsh as fish habitat in the Botany Bay estuary,New South Wales

Shallow-water vegetated estuarine habitats, notably seagrass, mangrove and saltmarsh, are known to be important habitats for many species of small or juvenile fish in temperate Australia. However, the movement of fish between these habitats is poorly understood, and yet critical to the management of the estuarine fisheries resource. We installed a series of buoyant pop nets in adjacent stands of seagrass, mangrove and saltmarsh in order to determine how relative abundance of fishes varied through lunar cycles. Nets were released in all habitats at the peak of the monthly spring tide for 12 months, and in the seagrass habitat at the peak of the neap tide also. The assemblage of fish in each habitat differed during the spring tides. The seagrass assemblage differed between spring and neap tide, with the neap tide assemblage showing greater abundances of fish, particularly those species which visited the adjacent habitats when inundated during spring tides. The result supports the hypothesis that fish move from the seagrass to the adjacent mangrove and saltmarsh during spring tides, taking advantage of high abundances of zooplankton, and use seagrass as a refuge during lower tides. The restoration and preservation of mangrove and saltmarsh utility as fish habitat may in some situations be linked to the proximity of available seagrass.     

Fluorescence Lifetime Imaging of Alterations to Cellular Metabolism by Domain 2 of the Hepatitis C Virus Core Protein

Hepatitis C virus (HCV) co-opts hepatic lipid pathways to facilitate its pathogenesis. The virus alters cellular lipid biosynthesis and trafficking, and causes an accumulation of lipid droplets (LDs) that gives rise to hepatic steatosis. Little is known about how these changes are controlled at the molecular level, and how they are related to the underlying metabolic states of the infected cell. The HCV core protein has previously been shown to independently induce alterations in hepatic lipid homeostasis. Herein, we demonstrate, using coherent anti-Stokes Raman scattering (CARS) microscopy, that expression of domain 2 of the HCV core protein (D2) fused to GFP is sufficient to induce an accumulation of larger lipid droplets (LDs) in the perinuclear region. Additionally, we performed fluorescence lifetime imaging of endogenous reduced nicotinamide adenine dinucleotides [NAD(P)H], a key coenzyme in cellular metabolic processes, to monitor changes in the cofactor’s abundance and conformational state in D2-GFP transfected cells. When expressed in Huh-7 human hepatoma cells, we observed that the D2-GFP induced accumulation of LDs correlated with an increase in total NAD(P)H fluorescence and an increase in the ratio of free to bound NAD(P)H. This is consistent with an approximate 10 fold increase in cellular NAD(P)H levels. Furthermore, the lifetimes of bound and free NAD(P)H were both significantly reduced – indicating viral protein-induced alterations in the cofactors’ binding and microenvironment. Interestingly, the D2-expressing cells showed a more diffuse localization of NAD(P)H fluorescence signal, consistent with an accumulation of the co-factor outside the mitochondria. These observations suggest that HCV causes a shift of metabolic control away from the use of the coenzyme in mitochondrial electron transport and towards glycolysis, lipid biosynthesis, and building of new biomass. Overall, our findings demonstrate that HCV induced alterations in hepatic metabolism is tightly linked to alterations in NAD(P)H functional states.     

Influence of Co2+, Ni2+ and Fe2+ on the production of tetrapyrroles by Methanosarcina barkeri

Summary The selective formation of three tetrapyrroles, Co-containing corrinoids, Ni-containing factor F₄₃₀ and Fe-containing cytochromes (haems) by Methanosarcina barkeri Fusaro (DSM 804) was achieved as a function of the concentrations of Co²⁺, Ni²⁺ and Fe²⁺ in a methanol minimmum medium. It was found that about 70% of the total tetrapyrroles synthesized was excreted into the culture supernatant. Hence, the continuous production of tetrapyrroles in a fixed-bed reactor (supporter: porous diatomaceous clay) was carried out at a dilution rate of 10 day^-1 (850 ml medium/85 ml column/day). The effluent discharged from the reactor contained the excreted tetrapyrroles, the concentrations of which were dependent upon the Co²⁺, Ni²⁺ and Fe²⁺ concentrations in the feed medium. The maximum productivities from the reactor (1 l basis) were 52 M corrinoids/day, 24 M F₄₃₀/day and 8 M haems/day, respectively.     

Carbon monoxide conversion to formate byMethanosarcina barkeri

Summary A preliminary study of formate production from CO plus H₂O using the intact cells ofMethanosarcina barkeri was conducted. Formate production from CO gas required the participation of three enzymes, CO dehydrogenase, hydrogenase and formate dehydrogenase. Hypophosphite inhibited formate formation from CO plus H₂O by about 80%. In this system, 9 g/l of formate could be obtained from CO gas after 48 h of incubation at 37°C, pH 8.0.     

Usefulness of nutritional indices and classifications in predicting death of malnourished children.

The usefulness of nutritional indices and classifications in predicting the death of children under 5 years old was evaluated by comparing measurements of 34 children with diarrhoea who died in a Dhaka hospital with those of 318 patients who were discharged in a satisfactory condition. In a logistic regression analysis mid-upper arm circumference was found to be as effective as other nutritional indices in predicting death. Combinations of different indices did not improve the prediction. Arm circumference might be preferable to more complex criteria for predicting the death of malnourished children.     

1,10-Phenanthroline-copper, a footprinting reagent for single-stranded regions of RNAs.

The 1,10-phenanthroline-cuprous complex (OP-Cu) with hydrogen peroxide as a coreactant nicks the single-stranded loops and bulges of RNA stem-loop structures more rapidly than the double-stranded stems. This chemical nuclease is therefore a useful footprinting reagent for these regions and can be used to monitor both intramolecular and intermolecular hybridization of single-stranded domains. The formation of A-form structures characteristic of either RNA-RNA or RNA-DNA duplexes inhibits scission because it blocks the binding site of the coordination complex in single-stranded loops and not because the oxidatively sensitive hydrogens of the ribose moiety are blocked. The C-4' and C-1' hydrogens are accessible to solvent in A-structures.     

Intermolecular disintegration and intramolecular strand transfer activities of wild-type and mutant HIV-1 integrase.

We report the activities of HIV integrase protein on a novel DNA substrate, consisting of a pair of gapped duplex molecules. Integrase catalyzed an intermolecular disintegration reaction that requires positioning of a pair of the gapped duplexes in a configuration that resembles the intgration intermediate. However, the major reaction resulted from an intramolecular reaction involving a single gapped duplex, giving rise to a hairpin. Surprisingly, a deletion mutant of integrase that lacks both the amino and carboxyl terminal regions still catalyzed the intermolecular disintegration reaction, but supported only a very low level of the intramolecular reaction. The central core region of integrase is therefore sufficient to both bind the gapped duplex DNA and juxtapose a pair of such molecules through protein-protein interactions. We suggest that the branched DNA structures of the previously reported disintegration substrate, and the intermolecular disintegration substrate described here, assist in stabilizing protein-protein interactions that otherwise require the amino and carboxy terminal regions of integrase.     

Pre- and Posttranslational Regulation of β-Endorphin Biosynthesis in the CNS: Effects of Chronic Naltrexone Treatment

Abstract: There appear to be two anatomically distinct β-endorphin (βE) pathways in the brain, the major one originating in the arcuate nucleus of the hypothalamus and a smaller one in the area of the nucleus tractus solitarius (NTS) of the caudal medulla. Previous studies have shown that these two proopiomelanocortin (POMC) systems may be differentially regulated by chronic morphine treatment, with arcuate cells down-regulated and NTS cells unaffected. In the present experiments, we examined the effects of chronic opiate antagonist treatment on βE biosynthesis across different CNS regions to assess whether the arcuate POMC system would be regulated in the opposite direction to that seen after opiate agonist treatment and to determine whether different βE-containing areas might be differentially regulated. Male adult rats were administered naltrexone (NTX) by various routes for 8 days (subcutaneous pellets, osmotic minipumps, or repeated intraperitoneal injections). Brain and spinal cord regions were assayed for total βE-ir, different molecular weight immunoreactive β-endorphin (βE-ir) peptides, and POMC mRNA. Chronic NTX treatment, regardless of the route of administration, reduced total βE-ir concentrations by 30–40% in diencephalic areas (the arcuate nucleus, the remaining hypothalamus, and the thalamus) and the midbrain, but had no effect on βE-ir in the NTS or any region of the spinal cord. At the same time, NTX pelleting increased POMC mRNA levels in the arcuate to ～ 140% of control values. These data suggest that arcuate POMC neurons are up-regulated after chronic NTX treatment (whereas NTS and spinal cord systems remain unaffected) and that they appear to be under tonic inhibition by endogenous opioids. Chromatographic analyses demonstrated that, after chronic NTX pelleting, the ratio of full length βE_1–31 to more processed βE-ir peptides (i.e., βE_1–27 and βE_1–26) tended to increase in a dose-dependent manner in diencephalic areas. Because βE_1–31 is the only POMC product that possesses opioid agonist properties, and βE_1–27 has been posited to function as an endogenous anatgonist of βE_1–31, the NTX-induced changes in the relative concentrations of βE_1–31 and βE_1–27/βE_1–26 may represent a novel regulatory mechanism of POMC cells to alter the opioid signal in the synapse.     

Evaluation of anti-inflammatory activity of Vernonia cinerea Less. extract in rats.

The methanol extract of the whole plant of Vernonia cinerea Less. was evaluated for its anti-inflammatory activity in acute (carrageenin, histamine and serotonin induced rat paw edema) and a chronic model (cotton pouch induced granuloma). The methanol extract (250 and 500 mg/kg(-1) p.o.) exhibited significant activity (p < 0.001) against all phlogistic agents used in a dose dependant manner. In the chronic model (cotton pouch granuloma method) the methanol extract exhibited significant anti-inflammatory activity. All these effects were compared with standard drug phenylbutazone (100 mg/kg(-1) p.o.).     

The structures of garcinones a,b and c: Three new xanthones from Garcinia mangostana

Three new tetraoxygenated xanthones (garcinones A, B and C), each disubstituted with C₅-units, have been isolated from the chloroform extract of the fruit-hulls of Garcinia mangostana. Their structures were established by a combination of spectral interpretation and chemical correlation.