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The COVID-19 pandemic is a major shock to society in terms of health and economy that is affecting both UK and global food and nutrition security. It is adding to the 'perfect storm' of threats to society from climate change, biodiversity loss and ecosystem degradation, at a time of considerable change, rising nationalism and breakdown in international collaboration. In the UK, the situation is further complicated due to Brexit. The UK COVID-19 F ood and N utrition S ecurity project, lasting one year, is funded by the Economic and Social Research Council and is assessing the ongoing impact of COVID-19 on the four pillars of food and nutrition security: access, availability, utilisation and stability. It examines the food system, how it is responding, and potential knock on effects on the UK's food and nutrition security, both in terms of the cascading risks from the pandemic and other threats. The study provides an opportunity to place the initial lessons being learnt from the on-going responses to the pandemic in respect of food and nutrition security in the context of other long-term challenges such as climate change and biodiversity loss.

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Mosaic trisomy 22 is rare, but can be compatible with prolonged life. Patients with mosaic trisomy 22 usually present with intrauterine growth retardation, mental retardation, failure to thrive, and craniofacial asymmetry. We report the case of a five-year-old boy who had a birth weight of 3.8 kg and normal developmental milestones. He presented with unilateral ocular manifestations of ptosis, double elevator palsy, high myopia, and choroidal coloboma involving the macula. Cytogenetic evaluation showed a low level of trisomy 22 in peripheral blood lymphocytes (1 in 100) and in cultured fibroblasts from a conjunctival biopsy of the affected eye (1 in 60). Our case demonstrates the value of chromosomal analysis of the tissues involved rather than just karyotyping of the blood lymphocytes to detect mosaicism in patients with localised and unilateral congenital malformations.

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INTRODUCTION: Aneuploidy remains a common cause of fetal loss after the first trimester. Conventional karyotyping from fetal solid tissues post-delivery unfortunately has a poor success rate particularly where the fetus is macerated. To overcome this we obtained amniocentesis and/or chorionic villus samples from mid-trimester intrauterine fetal deaths (IUFDs) prior to medical termination of pregnancy. SUBJECTS: Ten women with diagnosed IUFD between 12 and 24 weeks' gestation underwent amniocentesis and/or CVS performed after counselling. RESULTS: Successful karyotypes were obtained in all pregnancies. Five of the ten pregnancies were complicated by aneuploidy (two with trisomy 21, two with trisomy 18, and one with trisomy 13). CONCLUSION: The high rate of aneuploidy (50%) in this small cohort emphasises the need for karyotyping. A successful karyotype in all ten pregnancies demonstrates the value of offering these procedures before a termination of pregnancy. We would recommend the adoption of this approach in the management of IUFD occurring after the first trimester.

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The equipment and method for studying transient bubble dynamics are described in simple sonochemical reactors and presented using still frames from high-speed video microscopy (500 fps). Effects on aeration bubbles (mean size 1-3 mm diameter) and the cavitation induced species (< 0.5 mm diameter) are studied. The images are computer enhanced to improve interpretation of such features as the maximum ellipsoidal distortion at the nodal sound plane and spherical shape regain with due consideration of energy involved and expansion effects at the nodal sound plane. Also immersion depth/pressure effects, as the bubbles transcend the sound field column, in the cylindrical reactor, are recorded for evaluation of nodal and antinodal sound wave effects. Positions of the nodal and antinodal regions are marked using a novel tungsten halogen bulb technique and verified using the sonoelectroluminescent approach with the classical luminol/hydrogen peroxide chemistry which is enhanced under the sound field conditions.

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The effects of domestic violence are revealed in shelters for battered women, but with more emphasis on prevention, cues to violence may first be detected in home settings. The most common injury sites involve the upper body. Based on a 2-year record (N = 153) review at a shelter for battered women, prevalence of injuries, health conditions and substance use were examined. Most women (82%) reported injuries, and most had past injuries severe enough to require surgery or hospitalization. This article educates home care providers about the types of abuse they are likely to find in women from violent homes and their health implications.

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Amniocentesis remains the most common prenatal diagnostic invasive procedure for fetal karyotyping. During counselling prior to this procedure miscarriage rates are often quoted as a single figure. In this review of 2924 amniocenteses, we report that miscarriage rates vary with the gestational age at which the procedure is performed. The total miscarriage rate was 1.0 per cent after early amniocenteses (11 + 0-14 + 6 weeks) and 1.2 per cent after traditional mid-trimester amniocenteses (15 + 0-18 + 6 weeks). The rate was greatest (3.1 per cent) for amniocenteses performed after 18 + 6 weeks' gestation. The cumulative miscarriage risk increased from 0.03 per cent one week after the procedure to plateau at 1.1 per cent five weeks after the procedure. The preterm and still-birth rates following amniocenteses were similar in early and traditional mid-trimester amniocenteses but were significantly higher when amniocenteses were performed after 19 weeks' gestation. Although the incidence of talipes equinovarus was higher after early amniocentesis compared with traditional mid-trimester amniocenteses (1.4 per cent versus 0.2 per cent), none of the affected infants required corrective surgery. We conclude that counselling for this procedure should be tailored to each unit's unintended fetal loss rate based on cumulative rates. Such figures should be available to parents to assist them in their decision-making.

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hMSH2.hMSH6 heterodimer (hMutSalpha) and hMLH1.hPMS2 complex (hMutLalpha) have been implicated in the cytotoxic response of mammalian cells to a number of DNA-damaging compounds, including methylating agents that produce O(6)-methylguanine (O(6)MeG) adducts. This study demonstrates that O(6)MeG lesions, in which the damaged base is paired with either T or C, are subject to excision repair in a reaction that depends on a functional mismatch repair system. Furthermore, treatment of human cells with the S(N)1 DNA methylators N-methyl-N-nitrosourea or N-methyl-N'-nitro-N-nitrosoguanidine results in p53 phosphorylation on serine residues 15 and 392, and these phosphorylation events depend on the presence of functional hMutSalpha and hMutLalpha. Coupled with the previous demonstration that O(6)MeG.T and O(6)MeG.C pairs are recognized by hMutSalpha, these results implicate action of the mismatch repair system in the initial step of a damage-signaling cascade that can lead to cell-cycle checkpoint activation or cell death in response to DNA methylator damage.

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A 4 year old female referred with developmental delay was found to have two de novo abnormal derivatives of chromosome 15, a supernumerary inverted duplicated marker chromosome (inv dup(15)) and an interstitial triplication of proximal 15q11-q13 or 14 in one of the two 15 homologues (trip(15)). Fluorescence in situ hybridisation (FISH) using probes within and flanking the Prader-Willi/Angelman syndrome critical region (PWASCR) confirmed the triplication in the abnormal 15 homologue. The inv dup(15) was dicentric, positive for IR39d which maps proximal to the PWASCR, but was negative for all the PWASCR FISH probes used. Results using polymorphic microsatellite repeats confirmed that the additional material in the trip(15) was maternal in origin and included several PWASCR loci. The presence of two de novo abnormalities involving the proximal region of 15q suggests a linked mechanism of origin.

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Four-way helical junctions are found widely in natural RNA species. In this study, we have studied the conformation of two junctions by fluorescence resonance energy transfer. We show that the junctions are folded by pairwise coaxial helical stacking, forming one predominant stacking conformer in both examples studied. At low magnesium ion concentrations, the helical axes of both junctions are approximately perpendicular. One junction undergoes a rotation into a distorted antiparallel structure induced by the binding of a single magnesium ion. By contrast, the axes of the four-way junction of the U1 snRNA remain approximately perpendicular under all conditions examined, and we have determined the stacking conformer adopted.

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Nucleotide excision repair and the long-patch mismatch repair systems correct abnormal DNA structures arising from DNA damage and replication errors, respectively. DNA synthesis past a damaged base (translesion replication) often causes misincorporation at the lesion site. In addition, mismatches are hot spots for DNA damage because of increased susceptibility of unpaired bases to chemical modification. We call such a DNA lesion, that is, a base damage superimposed on a mismatch, a compound lesion. To learn about the processing of compound lesions by human cells, synthetic compound lesions containing UV photoproducts or cisplatin 1,2-d(GpG) intrastrand cross-link and mismatch were tested for binding to the human mismatch recognition complex hMutS alpha and for excision by the human excision nuclease. No functional overlap between excision repair and mismatch repair was observed. The presence of a thymine dimer or a cisplatin diadduct in the context of a G-T mismatch reduced the affinity of hMutS alpha for the mismatch. In contrast, the damaged bases in these compound lesions were excised three- to fourfold faster than simple lesions by the human excision nuclease, regardless of the presence of hMutS alpha in the reaction. These results provide a new perspective on how excision repair, a cellular defense system for maintaining genomic integrity, can fix mutations under certain circumstances.

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We review the global structures adopted by branched nucleic acids, including three- and four-way helical junctions in DNA and RNA. We find that some general folding principles emerge. First, all the structures exhibit a tendency to undergo pairwise coaxial helical stacking when permitted by the local stereochemistry of strand exchange. Second, metal ions generally play an important role in facilitating folding of branched nucleic acids. These principles can be applied to functionally important branched nucleic acids, such as the Holliday DNA junction of genetic recombination, and the hammerhead ribozyme in RNA.

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Bacterial and mammalian mismatch repair systems have been implicated in the cellular response to certain types of DNA damage, and genetic defects in this pathway are known to confer resistance to the cytotoxic effects of DNA-methylating agents. Such observations suggest that in addition to their ability to recognize DNA base-pairing errors, members of the MutS family may also respond to genetic lesions produced by DNA damage. We show that the human mismatch recognition activity MutSalpha recognizes several types of DNA lesion including the 1,2-intrastrand d(GpG) crosslink produced by cis-diamminedichloroplatinum(II), as well as base pairs between O6-methylguanine and thymine or cytosine, or between O4-methylthymine and adenine. However, the protein fails to recognize 1,3-intrastrand adduct produced by trans-diamminedichloroplatinum(II) at a d(GpTpG) sequence. These observations imply direct involvement of the mismatch repair system in the cytotoxic effects of DNA-methylating agents and suggest that recognition of 1,2-intrastrand cis-diamminedichloroplatinum(II) adducts by MutSalpha may be involved in the cytotoxic action of this chemotherapeutic agent.

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Helical junctions are important elements in the architecture of folded RNA molecules. The global geometry of fully base-paired four-way junctions between RNA helices has been analyzed by comparative gel electrophoresis. Junctions appear to fold by pairwise coaxial helical stacking in one of two possible stereochemically equivalent isomers based upon alternative selections of stacking partners. In the presence of 1 mM Mg2+, the two continuous helical axes are approximately at right angles to each other for all junctions studied, but the RNA junctions exhibit significant sequence-dependent differences in their structures as a function of ionic conditions. The four-way junction found in the U1 snRNA folded by coaxial helical stacking. It retained the 90 degrees crossed stacked structure under all ionic conditions tested, despite the presence of a G.A mismatch at the point of strand exchange.

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Bacteriophage T4 endonuclease VII is one of a class of structure-selective enzymes that resolve helical branchpoints in DNA molecules. The sequence of this protein suggests a modular organisation. We have expressed a synthetic gene encoding endonuclease VII, which has been used in a directed mutagenesis exercise, with the aim of understanding the role of different sections of the protein sequence. Towards the N-terminal end of the protein lies a section of polypeptide in which four cysteine residues distributed in a CxxC--CxxC pattern co-ordinate one atom of zinc. The N-terminal section composed of amino acid residues 1 to 65 isolated from the remaining C-terminal section also binds one mole of zinc, suggesting that this region folds autonomously. Mutation shows that the outer cysteine residues are essential for zinc binding, while the inner cysteine residues are partially degenerate in that either one of the two (but not both) can be replaced while retaining some zinc. The activity as a junction-resolving enzyme correlated qualitatively with the presence of the zinc. In the C-terminal part of the protein lies a section that is 48% identical with a sequence found in the DNA repair protein T4 endonuclease V. We can replace the section of T4 endonuclease VII with the corresponding sequence from T4 endonuclease V with no change in the pattern of cleavage on four-way junctions. The evidence supports a modular construction for T4 endonuclease VII.

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We report five patients with a combination of brachymetaphalangia and mental retardation, similar to that observed in Albright hereditary osteodystrophy (AHO). Four patients had cytogenetically visible de novo deletions of chromosome 2q37. The fifth patient was cytogenetically normal and had normal bioactivity of the alpha subunit of Gs (Gs alpha), the protein that is defective in AHO. In this patient, we have used a combination of highly polymorphic molecular markers and FISH to demonstrate a microdeletion at 2q37. The common region of deletion overlap involves the most telomeric 2q marker, D2S125, and extends proximally for a maximum distance of 17.6 cM. We suggest this represents a consistent phenotype associated with some deletions at 2q37 and that genes important for skeletal and neurodevelopment lie within this region. Screening for deletions at this locus should be considered in individuals with brachymetaphalangia and mental retardation. Furthermore, 2q37 represents a candidate region for type E brachydactyly.

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Bacteriophage T7 endonuclease I is a resolving enzyme that selectively cleaves four-way DNA junctions, and related branched species. We have isolated mutants of this protein that retain full structural selectivity of binding to four-way junctions, but which are completely inactive as nucleases. This is consistent with a divisibility of structure-selective binding and catalysis. The mutations that inactivate endonuclease I as a nuclease are clustered into the second quarter of the primary sequence, a region that displays some sequence similarity with the related junction-resolving enzyme endonuclease VII from bacteriophage T4. This suggests that these residues may form the active site of these enzymes. The configuration of the helical arms of the junction bound by mutant endonuclease I has been investigated by gel electrophoretic methods. We find that the junction is bound in the presence or absence of magnesium ions, and that the global structure of the bound form is apparently identical with or without cations. The patterns of mobilities suggest that the structure of the junction becomes perturbed by the binding of the protein.

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The four-way DNA junction is an important intermediate in recombination processes; it is, the substrate for different enzyme activities. In solution, the junction adopts a right-handed, antiparallel-stacked X-structure formed by the pairwise coaxial-stacking of helical arms. The stereochemistry is determined by the juxtaposition of grooves and backbones, which is optimal when the smaller included angle is 60 degrees. The antiparallel structure has two distinct sides with major and minor groove-characteristics, respectively. The folding process requires the binding of metal cations, in the absence of which, the junction remains extended without helix-helix stacking. The geometry of the junction can be perturbed by the presence of certain base-base mispairs or phosphodiester discontinuities located at the point of strand exchange. The four-way DNA junction is selectively cleaved by a number of resolving enzymes. In a number of cases, these appear to recognize the minor groove face of the junction and are functionally divisible into activities that recognize and bind the junction, and a catalytic activity. Some possible mechanisms for the recognition of branched DNA structure are discussed.

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We have investigated the structure of the four-way helical DNA junction containing a single covalent discontinuity (nick) in one strand. These could result from either unitary strand exchange processes, or the action of nucleases upon a complete junction. We have employed gel electrophoresis methods to study the global configuration of arms in these junctions. We find that the junction carrying a nick in one strand undergoes a folding process in the presence of magnesium ion concentrations greater than 200 microM. Comparison of the electrophoretic mobilities of the six possible derivative junctions with two long and two shortened arms suggests that the folding occurs by coaxial stacking of pairs of helical arms, which is supported by the suppression of reactivity to osmium tetroxide of thymine bases at the centre of the junction. However, unlike the complete junction (i.e. the junction without nicked strands), the two stacked pairs of helices lie at a mutual angle of approximately 90 degrees. The folding process generates two kinds of strands; two continuous strands and two exchanging strands. Two isomers of the right-angled stacked structure are possible, depending on the selection of stacking partners; it appears that the critical factor determining the relative stabilities of these isomers is the location of the nick. Thus the nicked junctions fold into the isomer that locates the nick on the exchanging strand. However, if the nick is not located at the point of strand exchange, the junction reverts to the stacked X-structure of the complete junction, even if the nick is moved by a single base-pair. These results suggest that the exchanging strands may be significantly strained in the structure of the complete four-way junction, such that an interruption to the continuity at this position allows the two stacked helices to disengage, and rotate to an angle where the overall electrostatic repulsion may be lower.

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We have studied a series of three-way DNA junctions containing unpaired bases on one strand at the branch-point of the junctions. The global conformation of the arms of the junctions has been analysed by means of polyacrylamide gel electrophoresis, as a function of conditions. We find that in the absence of added metal ions, all the results for all the junctions can be accounted for by extended structures, with the largest angle being that between the arms defined by the strand containing the extra bases. Upon addition of magnesium (II) or hexamine cobalt (III) ions, the electrophoretic patterns change markedly, indicative of ion-dependent folding transitions for some of the junctions. For the junction lacking the unpaired bases, the three inter-arm angles appear to be quite similar, suggesting an extended structure. However, the addition of unpaired bases permits the three-way junction to adopt a significantly different structure, in which one angle becomes smaller than the other two. These species also exhibit marked protection against osmium addition to thymine bases at the point of strand exchange. These results are consistent with a model in which two of the helical arms undergo coaxial stacking in the presence of magnesium ions, with the third arm defining an angle that depends upon the number of unpaired bases.

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