Human embryonic stem cells (hESCs) have a great potential in treating incurable diseases such as cancers and type 1 diabetes mellitus, as well as repairing physical injury because of their innate pluripotency and ability for self-renewal in different environments. However, hESCs are hard to maintain in vitro, because they are fragile and prone to apoptosis following routine passaging procedures. This limitation heavily affects the consistency of cell culture and experimental results even in the parallel hESC differentiation cultures. Several research groups tried to overcome this issue by isolating new hESC-based cell lines tolerant to single-cell dissociation, which, however, were deemed unusable due to their gross genomic instability and tendency for neoplastic transformation.
In a recent issue of Biotechnology and Bioengineering, researchers from University of British Columbia, University of Western Sidney and British Columbia Cancer Agency describe the isolation and properties of a subline CA1 hESCs (CA1S) that is tolerant to enzymatic dissociation and survives in culture for a large number of generations. CA1S cells possess nearly all the same characteristics as conventional hESCs despite an aberration on chromosome 20. The study demonstrates that they are capable of generating pancreatic endoderm in an HTS assay format, and they are generally useful in a microwell proliferation assay. These findings make them a promising candidate to study fundamental mechanisms of pancreatic and other cell line differentiation by high-throughput screening. The CA1S cell line may eventually find its way in the future stem cell therapies after additional studies and modifications.
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Caron, N. J. et al. A human embryonic stem cell line adapted for high throughput screening. Biotechnol. Bioeng. 2013, 110 2706–2716.
Fluorescence labelling has become a fundamental tool in biological imaging, allowing species of interest – from single molecules to entire organisms – to be identified and tracked. Similarly, magnetism has been harnessed to reveal internal body structures in magnetic resonance imaging (MRI). In a recent issue of Biotechnology Journal, researchers from Ohio State University and Nanjing University review the coupling of fluorescence and magnetism in magnetic quantum dots (QD). QD, semiconductor nanocrystals with optical properties superior to standard fluorescent dyes, can be amalgamated with magnetic materials to form nanocomposites possessing both fluorescent and magnetic properties. The review details common synthesis methods for forming magnetic QD and other fluorescent-magnetic nanomaterials. The application of these materials extends applications beyond advanced imaging contrast agents to lab-on-chip diagnostics. The nanoscale size of the fluorescent magnetic particles describes results in highly specific and accurate detection and quantification of biomolecules. A particularly intriguing application of magnetic QD is the creation of “theranostics” – materials able to both diagnose and treat illness. QD composites have the capacity to act as both imaging agents and drug delivery vehicles, thus their accumulation at tumour sites can be used to detect and treat solid tumours simultaneously.
Streptococcus agalactiae, also referred to as Group B Streptococcus (GBS), is a Gram-positive, β-hemolytic, chain-forming coccus that causes serious disease in a number of different hosts: meningoencephalitis in fish; mastitis in cows; and pneumonia, septicemia, and meningitis in human neonates. Piscine S. agalactiae affects a variety of wild and cultured fish species worldwide and causes high rates of mortality resulting in large economic losses to the fish-farming industry. Each summer since 2009, very serious S. agalactiae infections broke out in tilapia farms in China.
Despite its potential economic and ecological impacts on aquaculture and fisheries, to date, there have been few proteomic studies of piscine S. agalactiae for screening of virulence factors, diagnostic markers, or subunit vaccine candidates. Proteomics, which combines two-dimensional electrophoresis (2-DE) with mass spectrometry, is a powerful approach ideally suited to the recognition and identification of proteins from pathogenic micro-organisms for the identification of pathogenicity factors. Immunoproteomics is an extension of this technique, which allows specific identification of antigens based on immunoreactivity. Three Chinese scientists Guangjin Liu, Wei Zhang & Chengping Lu of Nanjing Agricultural University have conducted an immunoproteomics study of piscine S. agalactiae cellular proteins and successfully identified 13 novel immunoreactive proteins. Four of these novel proteins were implicated as vaccine candidates and virulence factors suitable for further investigation. These findings represent the basis of the rational development of vaccines and diagnostic antigens in piscine S. agalactiae infections. /Gillian van Beest
Liu, G., Zhang, W. and Lu, C. (2013), Identification of immunoreactive proteins of Streptococcus agalactiae isolated from cultured tilapia in China. Pathogens and Disease in press