Self-collection of samples for group B streptococcus testing during pregnancy: a systematic review and meta-analysis.

BACKGROUND: Sample self-collection for reproductive tract infection diagnosis has been found to offer greater convenience, privacy, autonomy, and expanded access to testing in non-pregnant adults. This review aimed to determine whether sample self-collection is as accurate as provider-collection for detection of group B streptococcus colonisation in pregnancy and whether a strategy of self-collection compared to provider-collection might improve maternal and neonatal health outcomes. METHODS: We searched CINAHL Plus, Medline, EMBASE, Maternity and Infant Care Database, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews in June 2022. Eligible studies compared self-collected and provider-collected samples taken from the same participants or participants randomised to either self-collection or provider-collection for reproductive tract infection testing using the same test and testing method in pregnant individuals. We included trials and observational studies. Reviewers assessed risk of bias using the QUADAS-2 checklist and independently extracted data. Sensitivity and specificity for group B streptococcus colonisation of self-collected compared to provider-collected samples were pooled using a bivariate, random-effects, meta-analytic model. This review was registered with PROSPERO (CRD42023396573). RESULTS: The search identified 5909 references, of which eleven diagnostic accuracy group B streptococcus studies were included (n = 3269 participants). No studies assessed the effects of self-collection in pregnancy on health outcomes. All studies had high or unclear risk of bias. Pooled sensitivities of self-collected samples for group B streptococcus detection were 82% (95% CI: 66-91%; I2 = 68.85%) in four trials (n = 1226) and 91% (95% CI: 83-96%; I2 = 37.38%) in seven non-randomised studies (n = 2043). Pooled specificities were 99% (95% CI: 98-99%; I2 = 12.08%) and 97% (95% CI: 94-99%; I2 = 72.50%), respectively. CONCLUSIONS: Self-collected samples for group B streptococcus detection in pregnancy had high specificity compared to provider-collection, but lower sensitivity, particularly for included trials. Studies investigating the effect of self-collection on health outcomes, and further higher quality trials comparing accuracy of self-collection to provider-collection, are required.

The Reemergence of Syphilis Among Females of Reproductive Age and Congenital Syphilis in Victoria, Australia, 2010 to 2020: A Public Health Priority.

BACKGROUND: Syphilis notifications in Victoria, Australia, have been increasing over the past decade, with an increase in infectious syphilis (syphilis of less than 2 years in duration) cases in females of reproductive age and an associated reemergence of congenital syphilis (CS). Before 2017, there had been 2 CS cases in the preceding 26 years. This study describes the epidemiology of infectious syphilis among females of reproductive age and CS in Victoria. METHODS: Routine surveillance data provided by mandatory Victorian syphilis case notifications were extracted and grouped into a descriptive analysis of infectious syphilis and CS incidence data from 2010 to 2020. RESULTS: In 2020, infectious syphilis notifications in Victoria were approximately 5 times more than 2010 (n = 289 in 2010 to n = 1440 in 2020), with a more than 7-fold rise among females (n = 25 in 2010 to n = 186 in 2020). Females made up 29% (n = 60 of 209) of Aboriginal and Torres Strait Islander notifications occurring between 2010 and 2020. Between 2017 and 2020, 67% of notifications in females (n = 456 of 678) were diagnosed in low-caseload clinics, at least 13% (n = 87 of 678) of all female notifications were known to be pregnant at diagnosis, and there were 9 CS notifications. CONCLUSIONS: Cases of infectious syphilis in females of reproductive age and CS are on the rise in Victoria, necessitating sustained public health action. Increasing awareness among individuals and clinicians, and health system strengthening, particularly targeting primary care where most females are diagnosed before pregnancy, are required. Treating infections before or promptly during pregnancy and undertaking partner notification and treatment to reduce risk of reinfection are critical to reducing CS cases.

How do national contraception laws and policies address the contraceptive needs of adolescents in Paraguay?

BACKGROUND: The main objective is to examine how the Paraguayan laws, policies and regulations (hereafter referred to as normative guidance) specifically address adolescents and their contraceptive information and service needs using a human rights analytic framework. It must be noted that this paper examines the adolescent content of national laws, policies and regulations on contraception, not how they were applied. METHODS: The recommendations on "Ensuring human rights in the provision of contraceptive information and services" from the World Health Organization (WHO) were used as an analytic framework to assess current Paraguayan laws, policies and regulations. Three questions were explored: 1) whether the Paraguayan normative guidance relating to each WHO recommendation was present and specifically addressed adolescents 2) whether the normative guidance for each WHO recommendation was present but did not specifically address adolescents, or 3) whether Paraguayan normative guidance relating to each WHO recommendation was absent. This assessment led to the development of an analytic table which was used by the co-authors to generate conclusions and recommendations. RESULTS: The analysis found specific normative guidance for adolescents relating to six out of nine WHO summary recommendations and nine out of the 24 sub-recommendations. The guidance included strategies to overcome contraceptive service barriers and to improve access for displaced populations. Further, it supported gender-sensitive counselling, quality assurance processes, competency-based training, and monitoring and evaluation of programmes. CONCLUSIONS: Paraguay's contraception laws and policies are grounded in human rights principles. However, there are a number of aspects that need to be addressed in order to improve the quality of contraceptive provision and access for adolescents. Our recommendations include improving accessibility of contraceptive information and services, ensuring acceptability, quality, and accountability of contraceptive information and services, and promoting community and adolescent participation in contraceptive programmes and service delivery.

Overproduction of Magnetosomes by Genomic Amplification of Biosynthesis-Related Gene Clusters in a Magnetotactic Bacterium.

UNLABELLED: Magnetotactic bacteria biosynthesize specific organelles, the magnetosomes, which are membrane-enclosed crystals of a magnetic iron mineral that are aligned in a linear chain. The number and size of magnetosome particles have to be critically controlled to build a sensor sufficiently strong to ensure the efficient alignment of cells within Earth's weak magnetic field while at the same time minimizing the metabolic costs imposed by excessive magnetosome biosynthesis. Apart from their biological function, bacterial magnetosomes have gained considerable interest since they provide a highly useful model for prokaryotic organelle formation and represent biogenic magnetic nanoparticles with exceptional properties. However, potential applications have been hampered by the difficult cultivation of these fastidious bacteria and their poor yields of magnetosomes. In this study, we found that the size and number of magnetosomes within the cell are controlled by many different Mam and Mms proteins. We present a strategy for the overexpression of magnetosome biosynthesis genes in the alphaproteobacterium Magnetospirillum gryphiswaldense by chromosomal multiplication of individual and multiple magnetosome gene clusters via transposition. While stepwise amplification of the mms6 operon resulted in the formation of increasingly larger crystals (increase of ∼35%), the duplication of all major magnetosome operons (mamGFDC, mamAB, mms6, and mamXY, comprising 29 genes in total) yielded an overproducing strain in which magnetosome numbers were 2.2-fold increased. We demonstrate that the tuned expression of the mam and mms clusters provides a powerful strategy for the control of magnetosome size and number, thereby setting the stage for high-yield production of tailored magnetic nanoparticles by synthetic biology approaches. IMPORTANCE: Before our study, it had remained unknown how the upper sizes and numbers of magnetosomes are genetically regulated, and overproduction of magnetosome biosynthesis had not been achieved, owing to the difficulties of large-scale genome engineering in the recalcitrant magnetotactic bacteria. In this study, we established and systematically explored a strategy for the overexpression of magnetosome biosynthesis genes by genomic amplification of single and multiple magnetosome gene clusters via sequential chromosomal insertion by transposition. Our findings also indicate that the expression levels of magnetosome proteins together limit the upper size and number of magnetosomes within the cell. We demonstrate that tuned overexpression of magnetosome gene clusters provides a powerful strategy for the precise control of magnetosome size and number.

Cognitive Control Over Immediate Reward in Binge Alcohol Drinkers.

BACKGROUND: Cognitive control deficits, as captured by inhibitory control measures, are indicative of increased impulsivity and are considered a marker for substance use disorder vulnerability. While individuals with alcohol use disorder (AUD) typically exhibit inhibitory control dysfunction, evidence of impaired inhibitory control among harmful drinkers, who are at increased risk of developing an AUD, is mixed. This study examined the response inhibition of binge drinkers using a task that employed neutral, as well as both immediate and delayed reward contingencies, to determine whether reward induced heightened impulsivity in this population. METHODS: Binge alcohol users (n = 42) and controls (n = 42) were administered a Monetary Incentive Control Task that required participants to successfully inhibit a prepotent motor response to both neutral and immediately rewarding stimuli in order to secure a large delayed reward. RESULTS: Binge drinkers had significantly worse response inhibition than controls irrespective of trial condition and even after controlling for differences in weekly intake. Although both binge and control participants exhibited significantly worse inhibitory control in the presence of immediate reward, the control group showed a greater reduction in inhibition accuracy compared to the binge group in reward relative to neutral conditions. Both groups demonstrated significantly enhanced control when forewarned there was an increased chance response inhibition would be required. Control participants secured the delayed reward more often than binge participants. CONCLUSIONS: Despite the variability in the literature, this study demonstrated consistent generalized impulse control deficits among binge-drinking individuals that were unrelated to reward manipulations. These findings point to mechanisms that may confer vulnerability for transition from binge drinking to AUD.

Generation of Multishell Magnetic Hybrid Nanoparticles by Encapsulation of Genetically Engineered and Fluorescent Bacterial Magnetosomes with ZnO and SiO2.

Magnetic nanoparticles (MNPs) have great potential in biomedical applications, but the chemical synthesis of size-controlled and functionalized core-shell MNPs remain challenging. Magnetosomes produced by the magnetotactic bacterium Magnetospirillum gryphiswaldense are naturally uniform and chemically pure magnetite MNPs with superior magnetic characteristics. Here, additional functionalities are made possible by the incorporation of biomolecules on the magnetosome surface; the magnetosome system is then chemically encapsulated with an inorganic coating. The novel multishell nanoparticles consist of the magnetosome core-which includes the magnetite crystal, the magnetosome membrane, and additional moieties, such as the enhanced green fluorescent protein (EGFP) and peptides-and an outer shell, comprising either silica or zinc oxide. Coating the functionalized magnetosomes with silica improves their colloidal stability and preserves the EGFP fluorescence in the presence of proteases and detergents. In addition, the surface charge of magnetosomes can be adjusted by varying the coating. This method will be useful for the versatile generation of new, multifunctional, multishell, and magnetic hybrid nanomaterials with potential applications in various biotechnological fields.

Genetic dissection of the mamAB and mms6 operons reveals a gene set essential for magnetosome biogenesis in Magnetospirillum gryphiswaldense.

Biosynthesis of bacterial magnetosomes, which are intracellular membrane-enclosed, nanosized magnetic crystals, is controlled by a set of >30 specific genes. In Magnetospirillum gryphiswaldense, these are clustered mostly within a large conserved genomic magnetosome island (MAI) comprising the mms6, mamGFDC, mamAB, and mamXY operons. Here, we demonstrate that the five previously uncharacterized genes of the mms6 operon have crucial functions in the regulation of magnetosome biomineralization that partially overlap MamF and other proteins encoded by the adjacent mamGFDC operon. While all other deletions resulted in size reduction, elimination of either mms36 or mms48 caused the synthesis of magnetite crystals larger than those in the wild type (WT). Whereas the mms6 operon encodes accessory factors for crystal maturation, the large mamAB operon contains several essential and nonessential genes involved in various other steps of magnetosome biosynthesis, as shown by single deletions of all mamAB genes. While single deletions of mamL, -P, -Q, -R, -B, -S, -T, and -U showed phenotypes similar to those of their orthologs in a previous study in the related M. magneticum, we found mamI and mamN to be not required for at least rudimentary iron biomineralization in M. gryphiswaldense. Thus, only mamE, -L, -M, -O, -Q, and -B were essential for formation of magnetite, whereas a mamI mutant still biomineralized tiny particles which, however, consisted of the nonmagnetic iron oxide hematite, as shown by high-resolution transmission electron microscopy (HRTEM) and the X-ray absorption near-edge structure (XANES). Based on this and previous studies, we propose an extended model for magnetosome biosynthesis in M. gryphiswaldense.

New vectors for chromosomal integration enable high-level constitutive or inducible magnetosome expression of fusion proteins in Magnetospirillum gryphiswaldense.

The alphaproteobacterium Magnetospirillum gryphiswaldense biomineralizes magnetosomes, which consist of monocrystalline magnetite cores enveloped by a phospholipid bilayer containing specific proteins. Magnetosomes represent magnetic nanoparticles with unprecedented magnetic and physicochemical characteristics. These make them potentially useful in a number of biotechnological and biomedical applications. Further functionalization can be achieved by expression of foreign proteins via genetic fusion to magnetosome anchor peptides. However, the available genetic tool set for strong and controlled protein expression in magnetotactic bacteria is very limited. Here, we describe versatile vectors for either inducible or high-level constitutive expression of proteins in M. gryphiswaldense. The combination of an engineered native PmamDC promoter with a codon-optimized egfp gene (Mag-egfp) resulted in an 8-fold increase in constitutive expression and in brighter fluorescence. We further demonstrate that the widely used Ptet promoter is functional and tunable in M. gryphiswaldense. Stable and uniform expression of the EGFP and ß-glucuronidase (GusA) reporters was achieved by single-copy chromosomal insertion via Tn5-mediated transposition. In addition, gene duplication by Mag-EGFP-EGFP fusions to MamC resulted in further increased magnetosome expression and fluorescence. Between 80 and 210 (for single MamC-Mag-EGFP) and 200 and 520 (for MamC-Mag-EGFP-EGFP) GFP copies were estimated to be expressed per individual magnetosome particle.

The oxygen sensor MgFnr controls magnetite biomineralization by regulation of denitrification in Magnetospirillum gryphiswaldense.

BACKGROUND: Magnetotactic bacteria are capable of synthesizing magnetosomes only under oxygen-limited conditions. However, the mechanism of the aerobic repression on magnetite biomineralization has remained unknown. In Escherichia coli and other bacteria, Fnr (fumarate and nitrate reduction regulator) proteins are known to be involved in controlling the switch between microaerobic and aerobic metabolism. Here, we report on an Fnr-like protein (MgFnr) and its role in growth metabolism and magnetite biomineralization in the alphaproteobacterium Magnetospirillum gryphiswaldense. RESULTS: Deletion of Mgfnr not only resulted in decreased N2 production due to reduced N2O reductase activity, but also impaired magnetite biomineralization under microaerobic conditions in the presence of nitrate. Overexpression of MgFnr in the WT also caused the synthesis of smaller magnetite particles under anaerobic and microaerobic conditions in the presence of nitrate. These data suggest that proper expression of MgFnr is required for WT-like magnetosome synthesis, which is regulated by oxygen. Analyses of transcriptional gusA reporter fusions revealed that besides showing similar properties to Fnr proteins reported in other bacteria, MgFnr is involved in the repression of the expression of denitrification genes nor and nosZ under aerobic conditions, possibly owing to several unique amino acid residues specific to MTB-Fnr. CONCLUSIONS: We have identified and thoroughly characterized the first regulatory protein mediating denitrification growth and magnetite biomineralization in response to different oxygen conditions in a magnetotactic bacterium. Our findings reveal that the global oxygen regulator MgFnr is a genuine O2 sensor. It is involved in controlling expression of denitrification genes and thereby plays an indirect role in maintaining proper redox conditions required for magnetite biomineralization.

An account of loneliness while living with an eating disorder.

WHAT IS KNOWN ON THE SUBJECT?: Severe and prolonged loneliness is known to be detrimental to mental well-being. Eating disorders and loneliness are linked to each other with loneliness often acting as a barrier during the recovery journey. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: This paper explores the experience of loneliness while recovering from an eating disorder, as framed within the context of childrearing and challenging family dynamics. While loneliness has negative connotations, it may act as a 'companion' to the person experiencing it. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: The first visible need is that for public figures to raise awareness of loneliness and mental well-being. Another emerging issue is the need to re-think automatic negative assumptions associated with loneliness. Importantly, professionals and caregivers have to consider the co-morbidity of loneliness and mental illness. Links between loneliness and unhealthy family dynamics also need to be assessed when providing support.

Cytochrome cd1 nitrite reductase NirS is involved in anaerobic magnetite biomineralization in Magnetospirillum gryphiswaldense and requires NirN for proper d1 heme assembly.

The alphaproteobacterium Magnetospirillum gryphiswaldense synthesizes magnetosomes, which are membrane-enveloped crystals of magnetite. Here we show that nitrite reduction is involved in redox control during anaerobic biomineralization of the mixed-valence iron oxide magnetite. The cytochrome cd1-type nitrite reductase NirS shares conspicuous sequence similarity with NirN, which is also encoded within a larger nir cluster. Deletion of any one of these two nir genes resulted in impaired growth and smaller, fewer, and aberrantly shaped magnetite crystals during nitrate reduction. However, whereas nitrite reduction was completely abolished in the ΔnirS mutant, attenuated but significant nitrite reduction occurred in the ΔnirN mutant, indicating that only NirS is a nitrite reductase in M. gryphiswaldense. However, the ΔnirN mutant produced a different form of periplasmic d(1) heme that was not noncovalently bound to NirS, indicating that NirN is required for full reductase activity by maintaining a proper form of d1 heme for holo-cytochrome cd(1) assembly. In conclusion, we assign for the first time a physiological function to NirN and demonstrate that effective nitrite reduction is required for biomineralization of wild-type crystals, probably by contributing to oxidation of ferrous iron under oxygen-limited conditions.

Emergency nursing nurse sensitive indicators: An integrative review.

BACKGROUND: Nurse sensitive indicators (NSIs) capture the outcomes of each nursing function impacted by nursing care. NSIs are critical in clarifying foci for emergency nurses when providing care in the emergency department (ED). OBJECTIVE: To establish NSIs key to emergency nursing from existing published literature. METHODS: Ten databases were searched as well as grey literature and Google Scholar in the development of data for this integrative review. Articles underwent a title and abstract review to establish inclusion/exclusion suitability followed by a full text critical appraisal. Data were extracted, synthesized, and analyzed using a structured process. RESULTS: Twenty-eight emergency nursing NSIs were identified from three included studies, with little consensus across the literature. The NSIs established in the literature reflected a broad range of non-specific technical skills. Overall, the quality of the included articles was low due to factors including study design and high risk of bias. CONCLUSIONS: The constrained range of NSIs and the limited literature exploring the outcomes of emergency nursing care perhaps reflects a wide ranging and seemingly evolving scope of emergency nurses. Further research is needed to delineate emergency nursing NSI, perhaps underpinned by a clear definition of an emergency nurse in terms of capability statements, core skills and defining attributes.

The association between menstrual hygiene, workplace sanitation practices and self-reported urogenital symptoms in a cross-sectional survey of women working in Mukono District, Uganda.

BACKGROUND: Women worldwide experience challenges managing their periods. Menstrual and genital hygiene behaviours have been linked to negative health outcomes, including urogenital symptoms and confirmed infections. However, evidence testing this association has been limited and mixed. This study aimed to (1) describe the menstrual care practices and prevalence of self-reported urogenital symptoms among working women in Mukono District, Uganda, and (2) test the associations between menstrual and genital care practices, and urogenital symptoms. METHODOLOGY: We undertook a cross-sectional survey of women aged 18-45 working in markets, schools, and healthcare facilities in Mukono District, with 499 participants who had menstruated in the past two months included in this analysis. We developed an aggregated measure of menstrual material cleanliness, incorporating material type and laundering practices. Associations with urogenital symptoms were tested using the aggregated material cleanliness measure alongside the frequency of changing materials, handwashing before menstrual tasks, and sanitation practices. RESULTS: Among our sample, 41% experienced urogenital symptoms in the past month. Compared to women exclusively using disposable pads, using appropriately cleaned or non-reused improvised materials (PR = 1.33, 95%CI 1.04-1.71), or inadequately cleaned materials (improvised or commercially produced reusable pads) (PR = 1.84, 95%CI 1.46-3.42) was associated with an increased prevalence of self-reported urogenital symptoms in the last month. There was no difference between those using disposable pads and those using clean reusable pads (PR = 0.98; 95%CI 0.66-1.57). Infrequent handwashing before changing materials (PR 1.18, 95%CI: 0.96-1.47), and delaying urination at work (PR = 1.37, 95%CI: 1.08-1.73) were associated with an increased prevalence of self-reported symptoms. CONCLUSION: Prevalence of self-reported urogenital symptoms was associated with the type and cleanliness of menstrual material used as well as infrequent handwashing and urinary restriction. There is a need for interventions to enable women to maintain cleanliness of their menstrual materials and meet their menstruation, urination and hand washing needs at home and work.

The periplasmic nitrate reductase nap is required for anaerobic growth and involved in redox control of magnetite biomineralization in Magnetospirillum gryphiswaldense.

The magnetosomes of many magnetotactic bacteria consist of membrane-enveloped magnetite crystals, whose synthesis is favored by a low redox potential. However, the cellular redox processes governing the biomineralization of the mixed-valence iron oxide have remained unknown. Here, we show that in the alphaproteobacterium Magnetospirillum gryphiswaldense, magnetite biomineralization is linked to dissimilatory nitrate reduction. A complete denitrification pathway, including gene functions for nitrate (nap), nitrite (nir), nitric oxide (nor), and nitrous oxide reduction (nos), was identified. Transcriptional gusA fusions as reporters revealed that except for nap, the highest expression of the denitrification genes coincided with conditions permitting maximum magnetite synthesis. Whereas microaerobic denitrification overlapped with oxygen respiration, nitrate was the only electron acceptor supporting growth in the entire absence of oxygen, and only the deletion of nap genes, encoding a periplasmic nitrate reductase, and not deletion of nor or nos genes, abolished anaerobic growth and also delayed aerobic growth in both nitrate and ammonium media. While loss of nosZ or norCB had no or relatively weak effects on magnetosome synthesis, deletion of nap severely impaired magnetite biomineralization and resulted in fewer, smaller, and irregular crystals during denitrification and also microaerobic respiration, probably by disturbing the proper redox balance required for magnetite synthesis. In contrast to the case for the wild type, biomineralization in Δnap cells was independent of the oxidation state of carbon substrates. Altogether, our data demonstrate that in addition to its essential role in anaerobic respiration, the periplasmic nitrate reductase Nap has a further key function by participating in redox reactions required for magnetite biomineralization.

MamY is a membrane-bound protein that aligns magnetosomes and the motility axis of helical magnetotactic bacteria.

To navigate within the geomagnetic field, magnetotactic bacteria synthesize magnetosomes, which are unique organelles consisting of membrane-enveloped magnetite nanocrystals. In magnetotactic spirilla, magnetosomes become actively organized into chains by the filament-forming actin-like MamK and the adaptor protein MamJ, thereby assembling a magnetic dipole much like a compass needle. However, in Magnetospirillum gryphiswaldense, discontinuous chains are still formed in the absence of MamK. Moreover, these fragmented chains persist in a straight conformation indicating undiscovered structural determinants able to accommodate a bar magnet-like magnetoreceptor in a helical bacterium. Here, we identify MamY, a membrane-bound protein that generates a sophisticated mechanical scaffold for magnetosomes. MamY localizes linearly along the positive inner cell curvature (the geodetic cell axis), probably by self-interaction and curvature sensing. In a mamY deletion mutant, magnetosome chains detach from the geodetic axis and fail to accommodate a straight conformation coinciding with reduced cellular magnetic orientation. Codeletion of mamKY completely abolishes chain formation, whereas on synthetic tethering of magnetosomes to MamY, the chain configuration is regained, emphasizing the structural properties of the protein. Our results suggest MamY is membrane-anchored mechanical scaffold that is essential to align the motility axis of magnetotactic spirilla with their magnetic moment vector and to perfectly reconcile magnetoreception with swimming direction.

An intracellular nanotrap redirects proteins and organelles in live bacteria.

UNLABELLED: Owing to their small size and enhanced stability, nanobodies derived from camelids have previously been used for the construction of intracellular "nanotraps," which enable redirection and manipulation of green fluorescent protein (GFP)-tagged targets within living plant and animal cells. By taking advantage of intracellular compartmentalization in the magnetic bacterium Magnetospirillum gryphiswaldense, we demonstrate that proteins and even entire organelles can be retargeted also within prokaryotic cells by versatile nanotrap technology. Expression of multivalent GFP-binding nanobodies on magnetosomes ectopically recruited the chemotaxis protein CheW1-GFP from polar chemoreceptor clusters to the midcell, resulting in a gradual knockdown of aerotaxis. Conversely, entire magnetosome chains could be redirected from the midcell and tethered to one of the cell poles. Similar approaches could potentially be used for building synthetic cellular structures and targeted protein knockdowns in other bacteria. IMPORTANCE: Intrabodies are commonly used in eukaryotic systems for intracellular analysis and manipulation of proteins within distinct subcellular compartments. In particular, so-called nanobodies have great potential for synthetic biology approaches because they can be expressed easily in heterologous hosts and actively interact with intracellular targets, for instance, by the construction of intracellular "nanotraps" in living animal and plant cells. Although prokaryotic cells also exhibit a considerable degree of intracellular organization, there are few tools available equivalent to the well-established methods used in eukaryotes. Here, we demonstrate the ectopic retargeting and depletion of polar membrane proteins and entire organelles to distinct compartments in a magnetotactic bacterium, resulting in a gradual knockdown of magneto-aerotaxis. This intracellular nanotrap approach has the potential to be applied in other bacteria for building synthetic cellular structures, manipulating protein function, and creating gradual targeted knockdowns. Our findings provide a proof of principle for the universal use of fluorescently tagged proteins as targets for nanotraps to fulfill these tasks.

Biosynthesis of magnetic nanostructures in a foreign organism by transfer of bacterial magnetosome gene clusters.

The synthetic production of monodisperse single magnetic domain nanoparticles at ambient temperature is challenging. In nature, magnetosomes--membrane-bound magnetic nanocrystals with unprecedented magnetic properties--can be biomineralized by magnetotactic bacteria. However, these microbes are difficult to handle. Expression of the underlying biosynthetic pathway from these fastidious microorganisms within other organisms could therefore greatly expand their nanotechnological and biomedical applications. So far, this has been hindered by the structural and genetic complexity of the magnetosome organelle and insufficient knowledge of the biosynthetic functions involved. Here, we show that the ability to biomineralize highly ordered magnetic nanostructures can be transferred to a foreign recipient. Expression of a minimal set of genes from the magnetotactic bacterium Magnetospirillum gryphiswaldense resulted in magnetosome biosynthesis within the photosynthetic model organism Rhodospirillum rubrum. Our findings will enable the sustainable production of tailored magnetic nanostructures in biotechnologically relevant hosts and represent a step towards the endogenous magnetization of various organisms by synthetic biology.

Bioengineered bioluminescent magnetotactic bacteria as a powerful tool for chip-based whole-cell biosensors.

This paper describes the generation of genetically engineered bioluminescent magnetotactic bacteria (BL-MTB) and their integration into a microfluidic analytical device to create a portable toxicity detection system. Magnetospirillum gryphiswaldense strain MSR-1 was bioengineered to constitutively express a red-emitting click beetle luciferase whose bioluminescent signal is directly proportional to bacterial viability. The magnetic properties of these bacteria have been exploited as "natural actuators" to transfer the cells in the chip from the reaction to the detection area, optimizing the chip's analytical performance. A robust and cost-effective biosensor for the evaluation of sample toxicity, named MAGNETOX, based on lens-free contact imaging detection, has been developed. A microfluidic chip has been fabricated using multilayered black and transparent polydimethyl siloxane (PDMS) in which BL-MTB are incubated for 30 min with the sample, then moved by microfluidics, trapped, and concentrated in detection chambers by an array of neodymium-iron-boron magnets. The chip is placed in contact with a cooled CCD via a fiber optic taper to perform quantitative bioluminescence imaging after addition of luciferin substrate. A model toxic compound (dimethyl sulfoxide, DMSO) and a bile acid (taurochenodeoxycholic acid, TCDCA) were used to investigate the analytical performance of the MAGNETOX. Incubation with DMSO and TCDCA drastically reduces the bioluminescent signal in a dose-related manner. The generation of bacteria that are both magnetic and bioluminescent combines the advantages of easy 2D cell handling with ultra sensitive detection, offering undoubted potential to develop cell-based biosensors integrated into microfluidic chips.