Identification of cellular changes associated with increased production of human growth hormone in a recombinant Chinese hamster ovary cell line

A proteomics approach was used to identify the proteins potentially implicated in the cellular response concomitant with elevated production levels of human growth hormone in a recombinant Chinese hamster ovary (CHO) cell line following exposure to 0.5 mM butyrate and 80 muM zinc sulphate in the production media. This involved incorporation of two-dimensional (2-D) gel electrophoresis and protein identification by a combination of N-terminal sequencing, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry, amino acid analysis and cross species database matching. From these identifications a CHO 2-D reference,map and annotated database have been established. Metabolic labelling and subsequent autoradiography showed the induction of a number of cellular proteins in response to the media additives butyrate and zinc sulphate. These were identified as GRP75, enolase and thioredoxin. The chaperone proteins GRP78, HSP90, GRP94 and HSP70 were not up-regulated under these conditions.

Angiotensin-converting enzyme inhibition attenuates the progression of rat hepatic fibrosis

Background & Aims: There is a significant relationship between inheritance of high transforming growth factor (TGF)-beta1 and angiotensinogen-producing genotypes and the development of progressive hepatic fibrosis in patients with chronic hepatitis C. In cardiac and renal fibrosis, TGF-beta1 production may be enhanced by angiotensin II, the principal effector molecule of the renin-angiotensin system. The aim of the present study was to determine the effects of the angiotensin converting enzyme inhibitor, captopril, on the progression of hepatic fibrosis in the rat bile duct ligation model. Methods: Rats were treated with captopril (100 mg kg(-1) day(-1)) commencing 1 or 2 weeks after bile duct ligation. Animals with bile duct ligation only and sham-operated animals sewed as controls. Four weeks after bile duct ligation, indices of fibrosis were assessed. Results: Cap topril treatment significantly reduced hepatic hydroxyproline levels, mean fibrosis score, steady state messenger RNA levels of TGF-beta1 and procollagen alpha1(I), and matrix metalloproteinase 2 and 9 activity. Conclusions: Captopril significantly attenuates the progression of hepatic fibrosis in the vat bile duct ligation model, and its effectiveness should be studied in human chronic liver diseases associated with progressive fibrosis.

Mechanisms of Thermal Adaptation Revealed From the Genomes of the Antarctic Archaea Methanogenium frigidum and Methanococcoides burtonii

We generated draft genome sequences for two cold-adapted Archaea, Methanogenium frigidum and Methanococcoides burtonii, to identify genotypic characteristics that distinguish them from Archaea with a higher optimal growth temperature (OGT). Comparative genomics revealed trends in amino acid and tRNA composition, and structural features of proteins. Proteins from the cold-adapted Archaea are characterized by a higher content of noncharged polar amino acids, particularly Gin and Thr and a lower content of hydrophobic amino acids, particularly Leu. Sequence data from nine methanogen genomes (OGT 15degrees-98degreesC) were used to generate IIII modeled protein structures. Analysis of the models from the cold-adapted Archaea showed a strong tendency in the solvent-accessible area for more Gin, Thr, and hydrophobic residues and fewer charged residues. A cold shock domain (CSD) protein (CspA homolog) was identified in M. frigidum, two hypothetical proteins with CSD-folds in M. burtonii, and a unique winged helix DNA-binding domain protein in M. burtonii. This suggests that these types of nucleic acid binding proteins have a critical role in cold-adapted Archaea. Structural analysis of tRNA sequences from the Archaea indicated that GC content is the major factor influencing tRNA stability in hyperthermophiles, but not in the psychrophiles, mesophiles or moderate thermophiles. Below an OGT of 60degreesC, the GC content in tRNA was largely unchanged, indicating that any requirement for flexibility of tRNA in psychrophiles is mediated by other means. This is the first time that comparisons have been performed with genome data from Archaea spanning the growth temperature extremes. from psychrophiles to hyperthermophiles

Modelling predicts positive and negative interactions between three Australian tropical tree species in monoculture and binary mixture

Computer modelling promises to. be an important tool for analysing and predicting interactions between trees within mixed species forest plantations. This study explored the use of an individual-based mechanistic model as a predictive tool for designing mixed species plantations of Australian tropical trees. The 'spatially explicit individually based-forest simulator' (SeXI-FS) modelling system was used to describe the spatial interaction of individual tree crowns within a binary mixed-species experiment. The three-dimensional model was developed and verified with field data from three forest tree species grown in tropical Australia. The model predicted the interactions within monocultures and binary mixtures of Flindersia brayleyana, Eucalyptus pellita and Elaeocarpus grandis, accounting for an average of 42% of the growth variation exhibited by species in different treatments. The model requires only structural dimensions and shade tolerance as species parameters. By modelling interactions in existing tree mixtures, the model predicted both increases and reductions in the growth of mixtures (up to +/- 50% of stem volume at 7 years) compared to monocultures. This modelling approach may be useful for designing mixed tree plantations. (c) 2006 Published by Elsevier B.V.

Rehabilitating degraded forest land in central Vietnam with mixed native species plantings

This paper examines the use of Acacia as a nurse crop to overcome some of the ecological and economic impediments to reforestation of degraded areas dominated by grasses including Imperata cylindrica. The study site at Hai Van Pass in central Vietnam was initially reforested using Acacia auriculiformis. After 8 years these stands were thinned and under-planted with Hopea odorata, Dipterocarpus alatus, Parashorea chinensis, Tarrietia javanica, Parashorea stellata, Scaphium lychnophorum, Peltophorum dasyrhachis var. tonkinensis and other high-value native species. At the time of field assessment (early 2004), the Acacia trees were aged between 16 and 18 years and basal area ranged from 9 to 13 m(2) ha(-1) after several thinnings. Acacias facilitated the establishment of native species, but after 6-7 years of growth, further thinning is needed to maintain growth rates. In addition to assisting the establishment of native species, the Acacia nurse crop should provide a revenue stream (NPV about US$ 180, or IRR 19%) sufficient to cover the establishment costs of the underplanted native species (about US$ 100). (c) 2006 Published by Elsevier B.V.

Trade-offs between timber production and biodiversity in rainforest plantations: Emerging issues and an ecological perspective

During the past two centuries there have been three major paradigm shifts in the management of Australian rainforests and the use of their timbers: from felling native forests towards growing plantations; from viewing forests and plantations as mainly providers of timber to viewing them as sources of multiple benefits (e.g. timber, biodiversity, carbon sequestration, catchment protection, recreation, regional economic development); and from timber plantations being developed mainly by government on public land towards those established by private citizens, companies, or joint venture arrangements, on previously-cleared freehold land. Rainforest timber plantations are increasingly established for varied reasons, and with multiple objectives. Landholders are increasingly interested in the biodiversity values of their plantations. However, there are few guidelines on the changes to plantation design and management that would augment biodiversity outcomes, or on the extent to which this might require a sacrifice of production. [Abstract extract]

Biodiversity values of timber plantations and restoration plantings for rainforest fauna in tropical and subtropical Australia

It has been suggested that timber plantations could play an important role in the conservation of biodiversity in cleared rainforest landscapes, not only because of their potential to cost-effectively reforest large areas of land, but also because they may provide habitat for rainforest plants and animals. However, this last claim is largely untested. In this study, we surveyed the occurrence of a range of animal taxa in monoculture and mixed species timber plantations and restoration plantings in tropical and subtropical Australia. We used the richness of ‘rainforest-dependent’ taxa (i.e., birds, lizards and mites associated with rainforest habitats) in reforested sites as our measure of their ‘biodiversity value’. We also examined whether the biodiversity value of reforested sites was correlated with habitat attributes, including plant species richness and vegetation structure and, further, whether biodiversity value was affected by the proximity of reforested sites to intact rainforest.

Species performance and site relationships for rainforest timber species in plantations in the humid tropics of Queensland

The performance of 32 tropical rainforest and eucalypt tree species grown in private, mixed species plantations was examined. There were two objectives: 1) to summarise the growth of species by soil and rainfall classes, 2) to investigate the degree of variability in growth rates with respect to environmental variables. Data were collected from 112 plots established in the Community Rainforest Reforestation Program (CRRP) plantations across sites in the humid tropics of central and north Queensland. Sites ranged from sea level to 1160 m above sea level, with annual rainfall from 800 mm to 4300 mm, on soils derived from basalt, metamorphic and granite parent material. Species performance was significantly related to climatic and edaphic variables but the strength of these relationships differed among taxa.

Stand density management in rainforest plantations

Trees in plantations established for timber production are usually grown at a sufficiently high density that canopy closure occurs within a relatively short time after planting. The trees then shade and outcompete most herbs, shrubs or grasses growing at the site. The closer the spacing (i.e. the greater the density) the faster this will occur. Subsequently, as the trees grow larger, this between-species competition is replaced by within-species competition. If unmanaged, this competition can reduce the commercial productivity of the plantation. Thus, there are two management dilemmas. One is knowing the best initial planting density. The second is knowing how to management the subsequent between-tree competition in order to optimize overall plantation timber productivity. In this chapter we consider initial spacing and thinning for high value timber trees grown in single and mixed species plantations. From growth studies in stands of different ages recommendations are proposed for managing both types of plantations where the primary objective is timber production. It seems that many rainforest species will require more space to achieve optimal growth than most eucalypts and conifers. On the other hand many rainforest species do not have strong apical dominance. Care will be needed to balance these two attributes.