Adherence to the Eatwell Guide and population and planetary health: A Rank Prize Forum report

This report summarises a Forum conducted in June 2023 to explore the current state of the knowledge around the Eatwell Guide, which is the UK government's healthy eating tool, in relation to population and planetary health. The 1.5-day Forum highlighted the limited, albeit promising evidence linking higher adherence to the Eatwell Guide with favourable health outcomes, including reduced overall mortality risk, lower abdominal obesity in post-menopausal women and improved cardiometabolic health markers. Similarly, evidence was presented to suggest that higher adherence to the Eatwell Guide is associated with reduced greenhouse gas emissions. Presentations were given around cultural adaptations of the Eatwell Guide, including African Heritage and South Asian versions, which are designed to increase the acceptability and uptake of the Eatwell Guide in these communities in the United Kingdom. Presentations highlighted ongoing work relevant to the applications of the Eatwell Guide in randomised controlled trials and public health settings, including the development of a screening tool to quantify Eatwell Guide adherence. The Forum ended with a World Café-style event, in which the strengths and limitations of the Eatwell Guide were discussed, and directions for future research were identified. This Forum report serves as a primer on the current state of the knowledge on the Eatwell Guide and population and planetary health and will be of interest to researchers, healthcare professionals and public health officials.

Antiviral RNA interference in mammalian cells

In antiviral RNA interference (RNAi), the DICER enzyme processes virus-derived double-stranded RNA (dsRNA) into small interfering RNAs (siRNAs) that guide ARGONAUTE proteins to silence complementary viral RNA. As a counterdefense, viruses deploy viral suppressors of RNAi (VSRs). Well-established in plants and invertebrates, the existence of antiviral RNAi remains unknown in mammals. Here, we show that undifferentiated mouse cells infected with encephalomyocarditis virus (EMCV) or Nodamura virus (NoV) accumulate ~22-nucleotide RNAs with all the signature features of siRNAs. These derive from viral dsRNA replication intermediates, incorporate into AGO2, are eliminated in Dicer knockout cells, and decrease in abundance upon cell differentiation. Furthermore, genetically ablating a NoV-encoded VSR that antagonizes DICER during authentic infections reduces NoV accumulation, which is rescued in RNAi-deficient mouse cells. We conclude that antiviral RNAi operates in mammalian cells.

Modulation of the tumorigenicity of human adenovirus-12-transformed cells by interferon

Human adenovirus-12-transformed cells express greatly reduced levels of the major histocompatibility complex class I antigens and are highly tumorigenic in syngeneic hosts. The finding that expression of a transfected class I gene is sufficient to abrogate their tumorigenicity underscores the importance of defining the conditions that will lead to derepression of endogenous class I genes in these cells. Brief treatment of Ad12-transformed cells with interferon results in the rapid but transient expression of class I antigens, and these interferon-treated cells have significantly reduced tumorigenicity in immunocompetent hosts. We have further demonstrated that subcutaneous administration of interferon, subsequent to the introduction of a tumorigenic dose of Ad12-transformed cells, results in complete protection against this tumor. The ability of interferon to "induce" class I gene expression may be an important modality in the treatment of a variety of spontaneous tumors that exhibit greatly reduced levels of class I antigens on their cell surface.

The light-harvesting polypeptides of Rhodopseudomonas viridis. The complete amino-acid sequences of B1015-alpha, B1015-beta and B1015-gamma

Three low molecular mass polypeptides have been isolated by using the technique of organic solvent extraction of thylakoid membranes or whole cells from Rhodopseudomonas viridis. Their primary structures were determined by long liquid phase sequencer runs, combined with the isolation and sequence analysis of the C-terminal o-iodosobenzoic acid fragment and carboxypeptidase degradation. The polypeptide which consists of 58 amino-acids and is 46% homologous to the antenna polypeptide B880-alpha from Rhodospirillum rubrum was designated as B1015-alpha (1 His residue). The sequence homology between the second polypeptide, named B1015-beta (55 amino acids, 2 His residues) and B880-beta from Rs. rubrum is 52%. For the third polypeptide consisting of 36 amino acids and exhibiting a high hydrophobicity, no equivalent polypeptide has so far been found in other purple bacteria. The molar ratio of these three organic solvent soluble polypeptides from Rp. viridis was estimated to be 1:1:1. Accordingly, the 36 amino-acid polypeptide is likely to be an additional constituent of the light-harvesting complex B1015, consequently termed as B1015-gamma. According to hydrophathy profiles, the transmembrane arrangement of B1015-alpha and B1015-beta within the thylakoid membrane is supposed to be similar. B1015-gamma, however, shows a somewhat different hydropathy profile. A particular feature of this polypeptide is its high amount of aromatic amino acids. It is postulated that B1015-gamma is involved in the formation of regular arrays of light-harvesting complexes.

Immunogenic properties of lipid A

Lipid A, the endotoxic principle of gram-negative bacterial lipopolysaccharides, when suitably exposed on the surface of bacterial cells, becomes immunogenic, eliciting the formation of antibodies specific to lipid A. Antibodies to lipid A occur naturally in the serum of normal humans and many animal species; the two exceptions found so far are mice (all strains tested) and guinea pigs. Antibodies to lipid A occur more frequently in patients with infections caused by gram-negative bacteria, such as urinary tract infections. Antibodies to lipid A interacted with free lipid A but not with lipid A as present in the intact lipopolysaccharide molecule. Antibodies to lipid A were induced in rabbits, but not in mice, following a single injection of immunogenic lipid A. Because of similarities between the lipid A of many gram-negative bacteria, antibodies to lipid A showed wide cross-reactions. With regard to biologic activity, antibodies to lipid A have been variously shown to be protective, damaging, or without effect.

The preparation and characterisation of native photoreceptor units from the thylakoids of Rhodopseudomonas viridis

The photosynthetic membranes of Rhodopseudomonas viridis consist of a regular array of structural units. Each unit is composed of a central core (thought to contain the reaction centre complex) surrounded by a subdivided ring of protein (of likely antennae function). These individual units can be dissociated from the membrances using a variety of detergent treatments. The absorption spectrum, used as a criterion of a native state, is retained. All of the seven major polypeptides, the four reaction centre polypeptides (cytochrome, H, M and L chain) as well as the three light-harvesting polypeptides (B1015-alpha, beta and xi) are shown to be present. Electron microscopy of the units shows a similar structure to the units within the membrane. surface-specific iodination of both membranes and units labels predominantly polypeptides H, B1015-alpha, and xi. M and L are weakly labelled. In addition, B1015-beta is labelled in the isolated units. This, with other evidence, supports an allocation of light-harvesting polypeptides to the outer ring. Further solubilisation of these units separates the reaction centre (as a native complex containing all four polypeptides) from the light-harvesting polypeptides. The light-harvesting polypeptides are obtained in a form containing all three polypeptides and bound pigment, however the peak at 1015 nm corresponding to native bacteriochlorophyll b is lost.

Localisation of Rhodopseudomonas viridis reaction centre and light harvesting proteins using ferritin-antibody labelling

Rhodopseudomonas viridis thylakoid membrane polypeptides were characterised by SDS gels, 2 D gels and surface-specific iodination. Four polypeptides with apparent molecular weights of 38 000, 33 000, 27 000, and 24 000 (reaction centre) and three low molecular weight polypeptides 11 000, 8000 and 6000 (probably light harvesting polypeptides) were identified. Antibodies were produced against the polypeptides eluted from SDS gels and tested for specificity by an immunoblotting assay. The antibodies were bound to the membranes and viewed by electron microscopy using a modification of the ferritin labelling technique. It is suggested that antigenic determinants for the 38 000, 33 000, and 27 000 reaction centre polypeptides and the 11 000 and 8000 low molecular weight polypeptides are present on the cytoplasmic membrane surface. The 33 000, 27 000, 11 000 and 6000 polypeptides appear to have surface-located residues which can be iodinated. The photosynthetic membrane of Rps. viridis appears to be a highly asymmetrical membrane.