A number of global initiatives in recent years, including ICH and PAT, have encouraged the use of single-use systems in bioprocessing. A major benefit to adapting process systems in this way is the reduced risk of cross-contamination between batches. Traditionally, single-use systems may have been used in early stage development of a new product, but commercial production would be converted to the use of stainless steel, multiple-use systems. Improvements to culturing techniques and optimization of fermentation conditions have made it possible for companies to achieve better titers, and, thus, able to use smaller bioreactors, which has contributed to increased use of disposible equipment. Controversy is beginning to brew, however, over the use of single-use systems, since focus has begun to shift from how to design systems with disposibles to what the environmental impacts may be. If you're curious about who is using single-use systems, and for what purposes, BioProcess International has published the results of a survey on the Impact of Single-Use Technologies, online.

_Source:

McLeod, L. 2009. Advances in Bioprocessing. BioProcess International, May 2009.

The fruit fly, (Drosophila), has been used as a genetic research tool for a very long time, because of it's easily observable phenotypic differences, and adherence of many of these traits to the basic rules of Mendelian inheritance. Because of this, I always assumed, or thought I'd heard somewhere, that it was the first multicelled organism for which the entire DNA sequence was determined. This is wrong, however, and, according to the NCBI Nematode Genome Resources webpage, the nematode was the first multicellular eukaryote to have it's genome completely sequenced.

This information was bought to my attention during a presentation at the SETAC conference I am attending, on the use of genomics and DNA microarray techniques to study nanoparticle toxicity using silver nanoparticles (Ag NP). The soil nematode is a popular test organism for toxicity studies. The Ag NP were found to severely downregulate several genes in this organism, by affecting transcription. This paper provided further support for the use of the nematode as a bioindicator organism for environmental contamination, using proteomic and genomic techniques.

_{Source: Roh, JY. et al. 2009. Ecotoxicity of silver nanoparticles on the soil nematode Caenorhabditis elegans using functional ecotoxicogenomics. Environmental Science and Technology 43:3933-3940.}

While the industrial biotechnology sector is rushing full steam ahead to develop and commercialize new nanotechnology products, scientists working in areas of human and ecological toxicity are scrambling to keep up. Nanoparticle toxicity is a prominent topic at this year's SETAC NA conference, with several dedicated platform and poster sessions. The society is primarily concerned with environmental toxicology, rather than human, but the number of papers, and the variety of different types of nanoparticles and target organisms being investigated, is reassuring. I'm glad to see the potential dangers of nanoparticle toxicity are being taken seriously by industry and regulators alike. Here are some of the presentations I came across:

• Kovacs, T. et al. Ensuring the Environmental Compatibility of Manufactured Nanocrystalline Cellulose (NCC). NCC is being developed for the pulp and paper industry. Four aquatic species were tested to determine possible adverse effects of an accidental release. Both acute and subacute endpoints were measured and conclusions were that NCC is of low risk to the aquatic environment.
• Ahamed, M. et al. Silver Nanoparticles-Induced Heat Shock Protein 70, Oxidative Stress and Apoptosis in Drosophila melanogaster. Silver nanoparticles (Ag NP) are already in commercial use in many different forms. There were a number of presentations on their uptake, accumulation and toxicity. This paper reported the induction of a number of enzymes involved in apoptosis, DNA repair, reactive oxygen species scavenging and a number of other response mechanisms to cellular stressors. In another presentation (Shoults-Wilson, W. et al. The Influence of Particle Size, Concentration and Surface Functionalization on Bioavailability of Ag Nanoparticles in the Earthworm Eisenia fetida), earthworms were found to avoid soil containing Ag NP. Bioaccumulation of Ag NP was observed, and exposure resulted in a dose-dependant reduction in reproduction.
• Roh, J.Y. et al. Toxicological Investigation of Multi-Well Carbon Nanotubes in Caenorhabditis elegans Using Genomics and Proteomics Approach. The soil nematode was exposed to multi-well carbon nanotubes (MW-CNT) and toxicity investigated using endpoints such as mortality, growth and reproduction, in addition to whole genome microarray and proteomics methods. Although mortality was not significantly affected, reproductive potential was reduced after exposure to the MW-CNT. A number of genes were differentially expressed including those for heat-shock proteins, suggesting the organisms were under stress. Work from the same research team also reported for Ag NP, for which toxicity was measured using this organism and an ecotoxicogenomic approach (Park, YJ and Choi, J. A Toxicity Assay Using Stress Responsive Caenorhabditis elegans Mutant Strains).
• Kim, J. et al. Ultraviolet B Light Enhances Toxicity of CdSe/ZnSe Quantum Dots in Daphnia magna. The results of this study suggest that phototoxicity is mediated by both release of Cd from the quantum dot (QD), and production of reactive oxygen species on the QD surface.

Developments in proteomics and genomics make it possible to study the impacts of environmental contaminants on the expression of hundreds, even thousands, of genes. 2-Dimensional Gel Electrophoresis is a protein separation method used in proteomics, for partitioning proteins from a mixture according to two criteria, instead of just one. Traditional gel electrophoresis, usually applied to the separation of DNA, works in just one direction.

In a presentation today, at the SETAC North America conference (New Orleans, LA), Jennifer Cole, of Texas Tech University, described using proteomics to study the effects of benzo(a)pyrene (B(a)P), a potent carcinogen, on protein expression in the blubber of the Bottlenose Dolphin. The work is the first of its kind on a marine mammal. Skin and blubber cultures from freshly stranded dolphins, were treated with B(a)P which is a known contaminant in marine environments. Proteins were extracted, desalted and separated on a 2-D gel. The gels were run in one direction to separate the proteins based on isoelectric point (the pH at which the sum of charges of the amino acids is zero), and in a second direction to separate based on molecular weight. Using the gels, the team could also apply protein purification methods to isolate and identify specific enzymes and determine which ones were up regulated and which were down regulated, as a result of exposure to the PAH compound