Differences in variation of human immunodeficiency virus type 1 sequences from Henan and Shanghai regions of China

Illegally paid blood donation was a risk factor for HIV acquisition exclusively in Henan and Hubei Provinces of China, and not in Shanghai. Nucleotide sequences in the gag and env genes of HIV-1 were compared between isolates from Henan and Shanghai regions of China to test whether an expected higher degree of a common source of infections from this unique blood donation transmission risk would be evident as decreased variation among Henan isolates in an exploratory cross-sectional analysis. Among 38 isolates studied, 23 of 23 (100%) from Henan and 8 of 15 (54%) from Shanghai were subtype B. In addition, fewer sequence differences were found in gp41 of subtype B isolates from Henan than from Shanghai isolates. Further studies with additional controls are therefore warranted to confirm the role of the degree of a common source of infections in differences in HIV variation across populations. Fundation items: The Vanderbilt-Meharry Center for AIDS Research (P30 AI 54999); R.T.D (R01 AI 29193); Start Fund of Ministry of Education of China (for Hong-zhou LU, 2004BA719A10).     

Offshore platforms as novel ecosystems: A case study from Australia’s Northwest Shelf

The decommissioning of offshore oil and gas platforms typically involves removing some or all of the associated infrastructure and the consequent destruction of the associated marine ecosystem that has developed over decades. There is increasing evidence of the important ecological role played by offshore platforms. Concepts such as novel ecosystems allow stakeholders to consider the ecological role played by each platform in the decommissioning process. This study focused on the Wandoo field in Northwest Australia as a case study for the application of the novel ecosystem concept to the decommissioning of offshore platforms. Stereo‐baited remote underwater video systems were used to assess the habitat composition and fish communities at Wandoo, as well as two control sites: a sandy one that resembled the Wandoo site pre‐installation, and one characterized by a natural reef as a control for natural hard substrate and vertical relief. We found denser macrobenthos habitat at the Wandoo site than at either of the control sites, which we attributed to the exclusion of seabed trawling around the Wandoo infrastructure. We also found that the demersal and pelagic taxonomic assemblages at Wandoo more closely resemble those at a natural reef than those which would likely have been present pre‐installation, but these assemblages are still unique in a regional context. The demersal assemblage is characterized by reef‐associated species with higher diversity than those at the sand control and natural reef control sites, with the pelagic community characterized by species associated with oil platforms in other regions. These findings suggest that a novel ecosystem has emerged in the Wandoo field. It is likely that many of the novel qualities of this ecosystem would be lost under decommissioning scenarios that involve partial or complete removal. This study provides an example for classifying offshore platforms as novel ecosystems.     

Gas exchange in the filamentous cyanobacterium Nostoc punctiforme strain ATCC 29133 and Its hydrogenase-deficient mutant strain NHM5

Nostoc punctiforme ATCC 29133 is a nitrogen-fixing, heterocystous cyanobacterium of symbiotic origin. During nitrogen fixation, it produces molecular hydrogen (H(2)), which is recaptured by an uptake hydrogenase. Gas exchange in cultures of N. punctiforme ATCC 29133 and its hydrogenase-free mutant strain NHM5 was studied. Exchange of O(2), CO(2), N(2), and H(2) was followed simultaneously with a mass spectrometer in cultures grown under nitrogen-fixing conditions. Isotopic tracing was used to separate evolution and uptake of CO(2) and O(2). The amount of H(2) produced per molecule of N(2) fixed was found to vary with light conditions, high light giving a greater increase in H(2) production than N(2) fixation. The ratio under low light and high light was approximately 1.4 and 6.1 molecules of H(2) produced per molecule of N(2) fixed, respectively. Incubation under high light for a longer time, until the culture was depleted of CO(2), caused a decrease in the nitrogen fixation rate. At the same time, hydrogen production in the hydrogenase-deficient strain was increased from an initial rate of approximately 6 micro mol (mg of chlorophyll a)(-1) h(-1) to 9 micro mol (mg of chlorophyll a)(-1) h(-1) after about 50 min. A light-stimulated hydrogen-deuterium exchange activity stemming from the nitrogenase was observed in the two strains. The present findings are important for understanding this nitrogenase-based system, aiming at photobiological hydrogen production, as we have identified the conditions under which the energy flow through the nitrogenase can be directed towards hydrogen production rather than nitrogen fixation.     

Gold complexes inhibit mitochondrial thioredoxin reductase: consequences on mitochondrial functions

The effects of gold(I) complexes (auranofin, triethylphosphine gold and aurothiomalate), gold(III) complexes ([Au(2,2'-diethylendiamine)Cl]Cl(2), [(Au(2-(1,1-dimethylbenzyl)-pyridine) (CH(3)COO)(2)], [Au(6-(1,1-dimethylbenzyl)-2,2'-bipyridine)(OH)](PF(6)), [Au(bipy(dmb)-H)(2,6-xylidine)](PF(6))), metal ions (zinc and cadmium acetate) and metal complexes (cisplatin, zinc pyrithione and tributyltin) on mitochondrial thioredoxin reductase and mitochondrial functions have been examined. Both gold(I) and gold(III) complexes are extremely efficient inhibitors of thioredoxin reductase showing IC(50) ranging from 0.020 to 1.42 microM while metal ions and complexes not containing gold are less effective, exhibiting IC(50) going from 11.8 to 76.0 microM. At variance with thioredoxin reductase, auranofin is completely ineffective in inhibiting glutathione peroxidase and glutathione reductase, while gold(III) compounds show some effect on glutathione peroxidase. The mitochondrial respiratory chain is scarcely affected by gold compounds while the other metal complexes and metal ions, in particular zinc ion and zinc pyrithione, show a more marked inhibitory effect that is reflected on a rapid induction of membrane potential decrease that precedes swelling. Therefore, differently from gold compounds, the various metal ions and metal complexes exert their effect on different targets indicating a lower specificity. It is concluded that gold compounds are highly specific inhibitors of mitochondrial thioredoxin reductase and this action influences other functions such as membrane permeability properties. Metal ions and metal complexes markedly inhibit the activity of thioredoxin reductase although to an extent lower than that of gold compounds. They also inhibit mitochondrial respiration, decrease membrane potential and, finally, induce swelling.     

A possible transport mechanism for aluminum in biological membranes

The transport mechanism of aluminum in lysosomes extracted from rat liver has been investigated in this paper. The experimental evidence supports the hypothesis that aluminum is transported inside lysosomes in the form of an Al(OH)(3) electroneutral compound, the driving force being the internal acidic pH. This mechanism could help to explain the presence of aluminum in cells in many illnesses.     

Miniaturisation and validation of a cell-based assay for screening of Ca2+ channel modulators

Voltage-operated calcium channels (VOCCs) play a significant role in the regulation of intracellular calcium concentrations in cardiovascular, neuronal and skeletal tissues. Therefore, physiologically relevant screening methods for calcium channel modulators are required. A 45Ca2+ uptake assay based on clonal rat pituitary cell line GH4C1, possessing L-type VOCCs, was miniaturised into a 96-well plate format. The assay was validated by known Ca2+ channel blockers, verapamil and nimodipine (IC50 values 3.4 and 0.007 microM, respectively) and by a set of natural compounds and their synthetic derivatives. The results were consistent with our previous data and demonstrated the reliability of the assay. The signal-to-background ratio was 3.9 +/- 0.4, signal-to-noise ratio 10.3 +/- 2.3, Z' factor 0.59 +/- 0.10, and day-to-day variability in positive control values 5%. Furthermore, experiments were also made on a Biomek FX workstation to evaluate the suitability of the assay for automation. With minor modifications the assay is applicable, e.g. for studying possible Ca2+ channel activators in detail. The established 96-well plate assay modification for screening of calcium channel modulators reduces considerably the time, labour and resources needed for cell culture and experiments, and has significant advantages in terms of automation suitability and overall cost-efficiency.     

Sex allocation of females and hermaphrodites in the gynodioecious Geranium sylvaticum

Seed production and patterns of sex allocation were studied in female and hermaphroditic plants in two gynodioecious populations of Geranium sylvaticum (Geraniaceae). Females produced more flower buds and seeds than hermaphrodites in one of the two study populations. The other female traits measured (pistil biomass, seed number per fruit, individual seed mass) did not differ between the gender morphs. The relative seed fitness of hermaphrodites differed between the study populations, with hermaphrodites gaining less of their fitness through female function in the population with a high frequency of females. However, the amount and size of pollen produced by hermaphrodites did not differ between populations. The number of flower buds was positively correlated with seed production in females, whereas in hermaphrodites a positive correlation between number of buds and seed production was found in only one of the two study populations. These results suggest that fitness gain through female function is labile in hermaphrodites of this species, and is probably affected by environmental factors such as the sex ratio of the population.     

Prolyl hydroxylation of collagen type I is required for efficient binding to integrin alpha 1 beta 1 and platelet glycoprotein VI but not to alpha 2 beta 1

Collagen is a potent adhesive substrate for cells, an event essentially mediated by the integrins alpha 1 beta 1 and alpha 2 beta 1. Collagen fibrils also bind to the integrin alpha 2 beta 1 and the platelet receptor glycoprotein VI to activate and aggregate platelets. The distinct triple helical recognition motifs for these receptors, GXOGER and (GPO)n, respectively, all contain hydroxyproline. Using unhydroxylated collagen I produced in transgenic plants, we investigated the role of hydroxyproline in the receptor-binding properties of collagen. We show that alpha 2 beta 1 but not alpha 1 beta 1 mediates cell adhesion to unhydroxylated collagen. Soluble recombinant alpha 1 beta 1 binding to unhydroxylated collagen is considerably reduced compared with bovine collagens, but binding can be restored by prolyl hydroxylation of recombinant collagen. We also show that platelets use alpha 2 beta 1 to adhere to the unhydroxylated recombinant molecules, but the adhesion is weaker than on fully hydroxylated collagen, and the unhydroxylated collagen fibrils fail to aggregate platelets. Prolyl hydroxylation is thus required for binding of collagen to platelet glycoprotein VI and to cells by alpha 1 beta 1. These observations give new insights into the molecular basis of collagen-receptor interactions and offer new selective applications for the recombinant unhydroxylated collagen I.