Host cell protein adsorption characteristics during protein a chromatography

Protein A chromatography is a critical and ‘gold‐standard’ step in the purification of monoclonal antibody (mAb) products. Its ability to remove >98% of impurities in a single step alleviates the burden on subsequent process steps and facilitates the implementation of platform processes, with a minimal number of chromatographic steps. Here, we have evaluated four commercially available protein A chromatography matrices in terms of their ability to remove host cell proteins (HCPs), a complex group of process related impurities that must be removed to minimal levels. SELDI‐TOF MS was used as a screening tool to generate an impurity profile fingerprint for each resin and indicated a number of residual impurities present following protein A chromatography, agreeing with HCP ELISA. Although many of these were observed for all matrices there was a significantly elevated level of impurity binding associated with the resin based on controlled pore glass under standard conditions. Use of null cell line supernatant with and without spiked purified mAb demonstrated the interaction of HCPs to be not only with the resin back‐bone but also with the bound mAb. A null cell line column overload and sample enrichment method before 2D‐PAGE was then used to determine individual components associated with resin back‐bone adsorption. The methods shown allow for a critical analysis of HCP removal during protein A chromatography. Taken together they provide the necessary process understanding to allow process engineers to identify rational approaches for the removal of prominent HCPs. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 1037–1044, 2012     

Adaptive governance of synthetic biology

As resistance to synthetic biology slowly coalesces, governments and scientists need to be proactive to avoid a repetition of the near moratorium on genetically modified crops in Europe.Synthetic biology has the potential to revolutionize the development of drugs, vaccines, biofuels and food crops, and to clean up environmental pollution, but the field is relatively young. It is too early to tell how it will deliver new fundamental understandings in the life sciences, how this understanding will create opportunities for innovation to satisfy human needs and the extent to which its applications might generate hazards to people or the environment.Synthetic biology is now being linked by NGOs to genetically modified (GM)crop development with potentially similar results for its future development [1]. An NGO advocacy coalition has published a report on synthetic biology that echoes the arguments made against GM crops in the late 1990s [2] with the intention to “… reign [sic] in these new technologies”, with an ideologically based framing of the technology as inherently hazardous, based on negative conjectures with little relationship to actual evidence.The prospect of another polarized public debate had already convinced policy-makers and scientists to pay early attention to the governance of synthetic biology.Reports from the US Presidential Commission for the Study of Bioethical Issues (PCSBI) and from the International Risk Governance Council (IRGC) [3,4] have attempted to develop principles of good governance that could be applied to synthetic biology, given the uncertainty about the nature of future developments. The reports recommend that policy-makers should aim for a governance approach that can adapt to changing innovation opportunities emerging from new scientific discoveries; encourage and promote innovation; minimize risk to humans and the environment; and balance the interests and values of all relevant stakeholders. The reports reject calls for a moratorium on synthetic biology until all risks are identified and mitigated, but also reject unfettered freedom for scientific investigation. The governance of synthetic biology should achieve an equitable balance between promoting innovation and imposing constraints to ensure safety. Dialogue with stakeholders should be conducted in a manner that welcomes the respectful exchange of opposing views and encourages mutual accommodation of differing opinions. Dialogues should contribute to decisions being taken on the basis of the best available evidence. Considering potential dual-use risks of synthetic biology, both reports note that undue restriction might be counterproductive to safety and security, by preventing the development of effective safeguards against, for example, terrorist threats.These principles of good governance are part of a long-term political and policy experiment that claims to use a lighter touch and be less top-down [5], but in effect has extended the regulatory process into areas that used to be left to market forces. It claims to be more democratic by involving a wider range of stakeholders in the decision-making process, but in effect has merely led to a shift in power away from industry and commerce towards advocacy groups with equally limited claims to represent ‘society''. The impact of implementing this governance agenda on innovation has so far been more marked and damaging in Europe than in the USA, but the recent criticism by Friends of the Earth and other advocacy groups might signal a change of emphasis and put the balanced approach to the governance of synthetic biology, that has so far been achieved, at risk.Indeed, the availability and quality of the scientific evidence used to support policy advice and decision-making, has been a major casualty of the new governance approach as applied in the EU to GM crops—as evidenced by the destruction of GM crop trials designed to evaluate the safety and efficacy of these crops. The role of neutral, impartial evidence in political decision-making has been diminished in favour of evidence that suits the agendas of particular advocacy groups. Politicians themselves helped to create this situation by shying away from making difficult, unpopular decisions on the basis of hard evidence, in favour of trying to accommodate all opinions, including ideologically driven agendas. Arthur Miller describes the sense of liberation experienced when eschewing the role of evidence in decision-making: “It was as though the absence of real evidence was a release from the burdens of this world; [….] Evidence, in contrast, is effort; leaping to conclusions is a wonderful pleasure…” [6].There is a need to reappraise both the role of scientific evidence in informing policy and political decision-making on new biotechnologies, and the legitimate context in which to accomodate value-based opinions as represented by NGOs.     

Growth and carbon stock change in eucalypt woodlands in northeast Australia: ecological and greenhouse sink implications

Data from 57 permanent monitoring sites are used to document the growth in woody vegetation and estimate the carbon sink in 27 M ha of eucalypt woodlands (savannas), contained within c. 60 M ha of grazed woodlands in Queensland (northeast Australia). The study sites are shown to be representative of the environment and structure of the eucalypt woodlands in the defined study area. Mean basal area increment for all live woody plants in 30 long‐term sites, with an average initial basal area of 11.86 ± 1.38 (SE) m² ha^?1, was 1.06 m² ha^?1 over a mean 14 years timeframe. The majority of the measurement period, commencing between 1982 and 1988, was characterized by below‐average rainfall. The increase in live tree basal area was due primarily to growth of existing trees (3.12 m² ha^?1) rather than establishment of new plants (0.25 m² ha^?1) and was partly offset by death (2.31 m² ha^?1). A simple but robust relationship between stand basal area and stand biomass of all woody species was developed for the eucalypt dominant woodlands. Analysis of above‐ground carbon stocks in live and standing dead woody plants gave a mean net above‐ground annual carbon increment for all 57 sites of 0.53 t C ha^?1 y^?1, similar to values estimated elsewhere in world savannas. Published root : shoot ratios were used to infer C flux in woody root systems on these sites. This results in an estimated sink in above‐ and below‐ground biomass of 18 Mt C y^?1 over the eucalypt woodlands studied, and potentially up to 35 Mt C y^?1 if extended to all grazed woodlands in Queensland. It is suggested that introduction of livestock grazing and altered fire regimes have triggered the change in tree‐grass dominance in these woodlands. Thus, change in carbon stocks in the grazed woodlands of Queensland is identified as an important component of human‐induced greenhouse gas flux in Australia, equivalent in magnitude to c. 25% of the most recently published (1999) total estimated national net emissions. The latter inventory takes into account emissions from land clearing, but does not include the sink identified in the present study. This sequestration also represents a small but significant contribution to the global terrestrial carbon sink.