We describe the use of phage libraries to derive new antibodies against p21Ras to be used for intracellular expression in mammalian cells. A panel of single‐chain antibody fragments, binding to Ras, were analyzed and characterized for their capacity to interfere in vitro with (a) the intrinsic GTPase activity of Ras and (b) the binding of Ras to its effector Raf, and were found not to neutralize its function, according to these biochemical criteria. When expressed intracellularly in mouse 3T3 K‐Ras transformed cells all the anti‐Ras single‐chain variable fragments (scFv) tested inhibited cell proliferation, as assessed by bromodeoxyuridine incorporation. Double immunofluorescence analysis of transfected cells using confocal microscopy confirmed that anti‐Ras antibody fragments colocalize with endogenous Ras, at subcellular locations where the protein Ras is not normally found. These data suggest that the ability of phage‐derived anti‐Ras scFv fragments to inhibit the function of Ras in vivo is a rather general and frequent property and that the range of antibodies that can be successfully used for intracellular inhibition studies is much greater than anticipated, exploiting the mode of action of diverting protein traffic.

An intensely debated question is whether or how a mandatory environmental risk assessment (ERA) should be conducted for plants obtained through novel genomic techniques, including genome editing (GE). Some countries have already exempted certain types of GE applications from their regulations addressing genetically modified organisms (GMOs). In the European Union, the European Court of Justice confirmed in 2018 that plants developed by novel genomic techniques for directed mutagenesis are regulated as GMOs. Thus, they have to undergo an ERA prior to deliberate release or being placed on the market. Recently, the European Food Safety Authority (EFSA) published two opinions on the relevance of the current EU ERA framework for GM plants obtained through novel genomic techniques (NGTs). Regarding GE plants, the opinions confirmed that the existing ERA framework is suitable in general and that the current ERA requirements need to be applied in a case specific manner. Since EFSA did not provide further guidance, this review addresses a couple of issues relevant for the case-specific assessment of GE plants. We discuss the suitability of general denominators of risk/safety and address characteristics of GE plants which require particular assessment approaches. We suggest integrating the following two sets of considerations into the ERA: considerations related to the traits developed by GE and considerations addressing the assessment of method-related unintended effects, e.g., due to off-target modifications. In conclusion, we recommend that further specific guidance for the ERA and monitoring should be developed to facilitate a focused assessment approach for GE plants.

The current initiative of the European Commission (EC) concerning plants produced using certain new genomic techniques, in particular, targeted mutagenesis and cisgenesis, underlines that a high level of protection for human and animal health and the environment needs to be maintained when using such applications. The current EU biosafety regulation framework ensures a high level of protection with a mandatory environmental risk assessment (ERA) of genetically modified (GM) products prior to the authorization of individual GMOs for environmental release or marketing. However, the guidance available from the European Food Safety Authority (EFSA) for conducting such an ERA is not specific enough regarding the techniques under discussion and needs to be further developed to support the policy goals towards ERA, i.e., a case-by-case assessment approach proportionate to the respective risks, currently put forward by the EC. This review identifies important elements for the case-by-case approach for the ERA that need to be taken into account in the framework for a risk-oriented regulatory approach. We also discuss that the comparison of genome-edited plants with plants developed using conventional breeding methods should be conducted at the level of a scientific case-by-case assessment of individual applications rather than at a general, technology-based level. Our considerations aim to support the development of further specific guidance for the ERA of genome-edited plants.

The gene encoding C1 inhibitor, the major control element of activation of the classical pathway of complement and a major inhibitor of several plasma serine proteases, has been studied only in man, where deficiency of C1 inhibitor results in the dominantly transmitted disease hereditary angioedema. Full‐length mouse C1 inhibitor cDNA and genomic clones were isolated and characterized as a first step towards the complete characterization of the pattern of C1 inhibitor expression and the production of an animal model of C1 inhibitor deficiency. Restriction‐enzyme and sequence analyses of a full‐length genomic clone demonstrated that the mouse gene has the same structure as the human homologue, but differs in size (9 kb versus 17 kb), mostly due to the presence of repetitive Alu elements in the human gene. Sequence comparisons in the promoter region indicate important similarities, i.e. the absence of a TATA box, the presence of an initiator sequence encompassing the transcription‐start site and of a γ‐interferon‐activated sequence (GAS) element at position −124 of the human sequence. A stretch of about 100 nucleotides in intron 1 reveals an unusually high degree of conservation for non‐coding sequences and contains non‐canonical but conserved tandemly arranged GAS elements at positions 369 and 388 of the human sequence. This finding supports the conclusions of functional studies on the human C1INH gene indicating a role of this region in modulation of transcription by interferons. The profile of C1 inhibitor expression in mouse liver, lung, heart, kidney, spleen and brain was determined by quantitative northern blot analysis.