Evacuation of Refugees from Afghanistan: Health Control at the Spanish Border in the Context of the COVID-19 Pandemic

Following the announcement of the retreat of troops from Afghanistan, the Spanish Government organised the so-called "Antigone Operation" for the evacuation of Afghan collaborators. The most relevant ministries were involved in the response. The Ministry of Health, through the Foreign Health Department, performed the health control on arrival. The whole operation was conducted at an air base. It included the health control of refugees composed of temperature measurement, a basic visual control and a coronavirus disease (COVID-19) rapid antigen test for those over 12 years of age; the assessment of their basic needs (food and hygiene); identification and security procedures; and the initial administrative processing. The refugees were accommodated in a temporary facility at the base, where they waited to be transferred to their final destinations. Between 19 and 27 August 2021, 2168 refugees arrived on 17 flights; 680 of them were children under 12 years of age. One thousand four hundred and ninety-nine rapid antigen tests were performed, with one positive result. "Antigone Operation" is unprecedented in Spain and is one of the most complex operations carried out in recent years. The COVID-19 pandemic required the establishment of a health control system on arrival, performed by Foreign Health, which contributed significantly to the overall success of the operation.

Identification and sequence of gene dicB: translation of the division inhibitor from an in-phase internal start

The dicA1 mutation, located in the replication termination region of Escherichia coli at 34.9 min, confers a temperature-sensitive, division defective phenotype to its hosts. Previous analysis had suggested that dicA codes for a repressor of a nearby division inhibition gene dicB. We show now that gene dicB is part of a complex operon. Five open reading frames (ORFs 1 to 5) preceeded by a promoter sensitive to dicA repression are found within a 1500 bp segment, and are organized into two clusters separated by a long untranslated region. Evidence for expression of these ORFs was obtained from in vitro or in vivo translation of plasmid-coded genes. IPTG-dependent cell filamentation was obtained when either the entire or the C-terminal part of the fourth ORF was placed under control of the lac promoter. In both cases, a 7 KD protein corresponding to translation from an in-frame ATG of ORF4 (dicB) was made. We propose that this C-terminal protein is the division inhibitor synthesized in dicA1 mutants.

Cell division inhibition gene dicB is regulated by a locus similar to lambdoid bacteriophage immunity loci

A mutation (dicA1) of a repressor gene located in the terminus region of the Escherichia coli chromosome has previously been shown to lead to temperature-dependent inhibition of division, and to be complemented by plasmids carrying either dicA or an adjacent gene dicC. In this study, operon fusions in the region coding for the division inhibition gene dicB have been used to show that temperature sensitivity does not result from high temperature inactivation of the dicA repressor. Sequence comparisons indicate that dicA and dicC are similar to genes c2 and cro respectively of bacteriophage P22, and carry similarly organized tandem operators, indicating a common evolutionary origin for dicAC and P22 immC. Nevertheless, the consensus half-operator sequence of dicAC, TGTTA-GYYA, differs significantly from that of P22 immC (ATT-TAAGAN). An analysis of the in vivo control of promoters dicAp, dicBp and dicCp placed upstream of malQ shows that the dicAC system is functionally similar to that of an immunity region, with the possible exception of an absence of pairwise cooperative binding. Our results also indicate that the dicA1 mutation causes a switch to permanent control by dicC at all temperatures.

Inhibition of replication forks exiting the terminus region of the Escherichia coli chromosome occurs at two loci separated by 5 min

The replication cycle of Escherichia coli strains duplicating their chromosome from the same plasmid origin placed at various locations or of strains having undergone a major inversion event along the origin-to-terminus axis was studied by marker-frequency analysis. It was observed that replication forks are unidirectionally inhibited at two loci of the termination region: counterclockwise-moving forks are inhibited at terminator T1 (28.5 min), and forks moving in the opposite direction are inhibited at terminator T2 (33.5 min). By determining the strand preference of Okazaki fragments that are specific for markers from the T1-T2 interval, it was shown that this interval is replicated in either direction, depending upon the strain analyzed. In addition, we also observed that forks moving in the "unnatural" direction along each oriC-T1 or -T2 arm are very slow, especially in the one-third portion of the chromosome around the terminators. We propose that this phenomenon is a consequence of nucleoid organization, which is proposed to be symmetrical on the two oriC-T1 or -T2 arms and polarized with respect to the direction of replication. We also propose that T1 and T2 are the terminal limits of these two polarized half-nucleoid bodies.

Control of cell division in Escherichia coli. DNA sequence of dicA and of a second gene complementing mutation dicA1, dicC

A mutation in a gene dicA of Escherichia coli leads to temperature-sensitive cell division, by allowing expression of a nearby division inhibition gene dicB (1). We have now established the sequence of the DicA region and identified DicA as a 15.5 KD protein. A second gene dicC transcribed divergently from dicA and coding for an 8.5 KD protein can also complement mutation dicA1 when provided on a multicopy plasmid.

A new dispensable genetic locus of the terminus region involved in control of cell division in Escherichia coli

Temperature-sensitive mutants defective in cell division were isolated after localised mutagenesis of the terminus region of the Escherichia coli chromosome. The defective gene in one of these mutants, dicA, was mapped at 34.9 min by linkage with manA and with three physically characterized Tn10 insertions. Temperature-sensitivity conferred by mutation dicA1 in a recA background [corrected] was suppressed by the presence of hybrid plasmids carrying the wild-type gene. In addition, the mutation was suppressed either by tranposon inactivation of a nearby gene, dicB, or by deletion of the entire dicA-dicB interval. These results define the dicA-dicB locus as a new dispensable genetic cluster involved in the control of cell division.

The spacing of Escherichia coli DNA gyrase sites cleaved in vivo by treatment with oxolinic acid and sodium dodecyl sulfate

In an attempt to locate gyrase binding sites in a specific region of the chromosome of E. coli, we have reinvestigated gyrase-promoted cleavage of chromosomal DNA by oxolinic acid and sodium dodecyl sulfate. Contrary to a previous report suggesting the presence of one site every 100 kb of DNA (Snyder and Drlica, J. Mol. Biol. 131, 287-302), we found frequencies of one cleavage every 25 or 12 kb depending on the growth medium. A search for cleavage sites by Southern blot hybridization failed to reveal any binding site cleaved at a high frequency. These results suggest that the actual spacing of sites is much closer than that determined from the frequency of cleavage. Measurement of the average size of fragments containing defined DNA sequences indicated that the frequency of sites varies along the chromosome. The region located opposite to oriC carries relatively few sites.

Origin of Escherichia coli K-12 Hfr B7

Several F' plasmids encoding resistance to tetracycline have been derived from a trg::Tn10 Hfr B7 strain of Escherichia coli K-12. One of these plasmids, JGF312, was analyzed by restriction endonuclease digestion and Southern blot hybridization to cloned chromosomal fragments. This analysis revealed that JGF312 was formed by Tn10-promoted deletion from the Tn10 insertion (31.4 min) to within the prophage rac at 30.1 min. Hfr B7 was shown to result from recombination between IS2 of F delta (33-43) and a chromosomal IS2 located within the rac-man region at 30.9 min on the genetic map.

Molecular cloning of the region of the terminus of Escherichia coli K-12 DNA replication

A series of plasmids have been isolated either by ligation of defined restriction fragments to plasmid pBR325 or by screening of a cosmid bank by in situ colony hybridization. Together with one previously isolated plasmid, they spanned 86% of the 30.5- to 34-min region of the genetic map of Escherichia coli K-12. Physical analysis of these plasmids and hybridizations to Southern blots confirmed the endonuclease map of this region, with the exception of a 9.3-kilobase pair inversion.