Author Correction: A new antibiotic selectively kills Gram-negative pathogens.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A new antibiotic selectively kills Gram-negative pathogens.

The current need for novel antibiotics is especially acute for drug-resistant Gram-negative pathogens1,2. These microorganisms have a highly restrictive permeability barrier, which limits the penetration of most compounds3,4. As a result, the last class of antibiotics that acted against Gram-negative bacteria was developed in the 1960s2. We reason that useful compounds can be found in bacteria that share similar requirements for antibiotics with humans, and focus on Photorhabdus symbionts of entomopathogenic nematode microbiomes. Here we report a new antibiotic that we name darobactin, which was obtained using a screen of Photorhabdus isolates. Darobactin is coded by a silent operon with little production under laboratory conditions, and is ribosomally synthesized. Darobactin has an unusual structure with two fused rings that form post-translationally. The compound is active against important Gram-negative pathogens both in vitro and in animal models of infection. Mutants that are resistant to darobactin map to BamA, an essential chaperone and translocator that folds outer membrane proteins. Our study suggests that bacterial symbionts of animals contain antibiotics that are particularly suitable for development into therapeutics.

Primary cilia in satellite cells are the mechanical sensors for muscle hypertrophy.

Skeletal muscle atrophy is commonly associated with aging, immobilization, muscle unloading, and congenital myopathies. Generation of mature muscle cells from skeletal muscle satellite cells (SCs) is pivotal in repairing muscle tissue. Exercise therapy promotes muscle hypertrophy and strength. Primary cilium is implicated as the mechanical sensor in some mammalian cells, but its role in skeletal muscle cells remains vague. To determine mechanical sensors for exercise-induced muscle hypertrophy, we established three SC-specific cilium dysfunctional mouse models-Myogenic factor 5 (Myf5)-Arf-like Protein 3 (Arl3)-/-, Paired box protein Pax-7 (Pax7)-Intraflagellar transport protein 88 homolog (Ift88)-/-, and Pax7-Arl3-/--by specifically deleting a ciliary protein ARL3 in MYF5-expressing SCs, or IFT88 in PAX7-expressing SCs, or ARL3 in PAX7-expressing SCs, respectively. We show that the Myf5-Arl3-/- mice develop grossly the same as WT mice. Intriguingly, mechanical stimulation-induced muscle hypertrophy or myoblast differentiation is abrogated in Myf5-Arl3-/- and Pax7-Arl3-/- mice or primary isolated Myf5-Arl3-/- and Pax7-Ift88-/- myoblasts, likely due to defective cilia-mediated Hedgehog (Hh) signaling. Collectively, we demonstrate SC cilia serve as mechanical sensors and promote exercise-induced muscle hypertrophy via Hh signaling pathway.

Unconventional Superconducting Diode Effects via Antisymmetry and Antisymmetry Breaking.

Symmetry breaking plays a pivotal role in unlocking intriguing properties and functionalities in material systems. For example, the breaking of spatial and temporal symmetries leads to a fascinating phenomenon: the superconducting diode effect. However, generating and precisely controlling the superconducting diode effect pose significant challenges. Here, we take a novel route with the deliberate manipulation of magnetic charge potentials to realize unconventional superconducting flux-quantum diode effects. We achieve this through suitably tailored nanoengineered arrays of nanobar magnets on top of a superconducting thin film. We demonstrate the vital roles of inversion antisymmetry and its breaking in evoking unconventional superconducting effects, namely a magnetically symmetric diode effect and an odd-parity magnetotransport effect. These effects are nonvolatilely controllable through in situ magnetization switching of the nanobar magnets. Our findings promote the use of antisymmetry (breaking) for initiating unconventional superconducting properties, paving the way for exciting prospects and innovative functionalities in superconducting electronics.

Proteomic Profiling of Unannotated Microproteins in Human Placenta Reveals XRCC6P1 as a Potential Negative Regulator of Translation.

Ribosome profiling and mass spectrometry have revealed thousands of previously unannotated small and alternative open reading frames (sm/alt-ORFs) that are translated into micro/alt-proteins in mammalian cells. However, their prevalence across human tissues and biological roles remains largely undefined. The placenta is an ideal model for identifying unannotated microproteins and alt-proteins due to its considerable protein diversity that is required to sustain fetal development during pregnancy. Here, we profiled unannotated microproteins and alt-proteins in human placental tissues from preeclampsia patients or healthy individuals by proteomics, identified 52 unannotated microproteins or alt-proteins, and demonstrated that five microproteins can be translated from overexpression constructs in a heterologous cell line, although several are unstable. We further demonstrated that one microprotein, XRCC6P1, associates with translation initiation factor eIF3 and negatively regulates translation when exogenously overexpressed. Thus, we revealed a hidden sm/alt-ORF-encoded proteome in the human placenta, which may advance the mechanism studies for placenta development as well as placental disorders such as preeclampsia.

Highly Active CoNi-CoN3 Composite Sites Synergistically Accelerate Oxygen Electrode Reactions in Rechargeable Zinc-Air Batteries.

Reaching rapid reaction kinetics of oxygen reduction (ORR) and oxygen evolution reactions (OER) is critical for realizing efficient rechargeable zinc-air batteries (ZABs). Herein, a novel CoNi-CoN3 composite site containing CoNi alloyed nanoparticles and CoN3 moieties is first constructed in N-doped carbon nanosheet matrix (CoNi-CoN3/C). Benefiting from the high electroactivity of CoNi-CoN3 composite sites and large surface area, CoNi-CoN3/C shows a superior half-wave potential (0.88 V versus RHE) for ORR and a small overpotential (360 mV) for OER at 10 mA cm-2. Theoretical calculations have demonstrated that the introduction of CoNi alloys has modulated the electronic distributions near the CoN3 moiety, inducing the d-band center of CoNi-CoN3 composite site to shift down, thus stabilizing the valence state of Co active sites and balancing the adsorption of OER/ORR intermediates. Accordingly, the reaction energy trends exhibit optimized overpotentials for OER/ORR, leading to superior battery performances. For aqueous and flexible quasi-solid-state rechargeable ZABs with CoNi-CoN3/C as catalyst, a large power density (250 mW cm-2) and high specific capacity (804 mAh g-1) are achieved. The in-depth understanding of the electroactivity enhancement mechanism of interactive metal nanoparticles and metal coordinated with nitrogen (MNx) moieties is crucial for designing novel high-performance metal/nitrogen-doped carbon (M─N─C) catalysts.

High-power 940†nm DFB laser diode with large optical cavity.

High-power laser diodes with a stable wavelength and narrow linewidth are crucial for many applications. In this study, we introduce a first-order distributed feedback (DFB) grating into an asymmetric large-cavity laser diode operating around 940 nm. This design maintains high output power and offers a wide temperature locking range. The nearly sinusoidal shape first-order grating is fabricated by ultraviolet (UV) nanoimprint lithography, inductively coupled plasma (ICP) dry etching, and wet polishing. At a heat sink temperature of 25°C, the DFB laser diode, with a 200 µm stripe width and 4 mm cavity length, achieves a maximum output power of 24.8 W and a full width at half maximum (FWHM) of 0.4 nm under continuous-wave (CW) conditions. The maximum slope efficiency is calculated to be 1.04 W/A. At an output power of 10.7 W, the device reaches a peak wall-plug efficiency of 56%. Under quasi-continuous operation at 20 A, the laser output spectrum remains locked to the DFB grating over a temperature range from -10°C to 110°C, with a temperature coefficient of 0.062 nm/°C.

High-power distributed feedback laser diode arrays with narrow spectral width over a wide temperature range.

High-power semiconductor lasers with stabilized wavelengths are recognized as exemplary pumping sources for solid-state lasers. This study introduces distributed feedback (DFB) laser diode arrays designed to maintain an extensive temperature locking range. We report experimentally on high-power 808 nm DFB laser diode arrays. The first-order sinusoidal grating was fabricated using nanoimprint lithography, succeeded by inductively coupled plasma (ICP) dry etching and subsequent wet polishing. These 808 nm DFB laser diode arrays have demonstrated a measured output power of 134 W under a pulsed current of 150 A, with the heat sink temperature maintained at 25°C. The slope efficiency was determined to be 1.1 W/A. At a current of 150 A, the laser operated with a narrow spectral width over a wide temperature range, extending from -30 to 90°C, with a temperature drift coefficient of 0.0595 nm/K.

Evybactin is a DNA gyrase inhibitor that selectively kills Mycobacterium tuberculosis.

The antimicrobial resistance crisis requires the introduction of novel antibiotics. The use of conventional broad-spectrum compounds selects for resistance in off-target pathogens and harms the microbiome. This is especially true for Mycobacterium tuberculosis, where treatment requires a 6-month course of antibiotics. Here we show that a novel antimicrobial from Photorhabdus noenieputensis, which we named evybactin, is a potent and selective antibiotic acting against M. tuberculosis. Evybactin targets DNA gyrase and binds to a site overlapping with synthetic thiophene poisons. Given the conserved nature of DNA gyrase, the observed selectivity against M. tuberculosis is puzzling. We found that evybactin is smuggled into the cell by a promiscuous transporter of hydrophilic compounds, BacA. Evybactin is the first, but likely not the only, antimicrobial compound found to employ this unusual mechanism of selectivity.

The functional study of a novel MKRN3 missense mutation associated with familial central precocious puberty.

Central precocious puberty (CPP) refers to a syndrome of early puberty initiation with a characteristic increase in the release of gonadotropin-releasing hormone (GnRH); therefore, it is also called GnRH-related precocious puberty. About a quarter of idiopathic central precocious puberty (ICPP) may be familial. Studies suggest that mutations of makorin ring finger protein 3 (MKRN3) can cause familial central precocious puberty (FCPP). In this report, we describe a Chinese female patient carrying a novel MKRN3 variant (c.980G>A/p.Arg327His) and presenting the CPP phenotype. This novel variant attenuated its own ubiquitination, degradation, and inhibition on the transcriptional and translational activity of GNRH1, which was verified through functional tests. We can consider this variant as a loss-of-function mutation, which subsides the inhibition of GnRH1-related signaling and gives rise to GnRH-related precocious puberty.

Advances of Photothermal Agents with Fluorescence Imaging/Enhancement Ability in the Field of Photothermal Therapy and Diagnosis.

Photothermal therapy (PTT) is an effective cancer treatment method. Due to its easy focusing and tunability of the irradiation light, direct and accurate local treatment can be performed in a noninvasive manner by PTT. This treatment strategy requires the use of photothermal agents to convert light energy into heat energy, thereby achieving local heating and triggering biochemical processes to kill tumor cells. As a key factor in PTT, the photothermal conversion ability of photothermal agents directly determines the efficacy of PTT. In addition, photothermal agents generally have photothermal imaging (PTI) and photoacoustic imaging (PAI) functions, which can not only guide the optimization of irradiation conditions but also achieve the integration of disease diagnosis. If the photothermal agents have function of fluorescence imaging (FLI) or fluorescence enhancement, they can not only further improve the accuracy in disease diagnosis but also accurately determine the tumor location through multimodal imaging for corresponding treatment. In this paper, we summarize recent advances in photothermal agents with FLI or fluorescence enhancement functions for PTT and tumor diagnosis. According to the different recognition sites, the application of specific targeting photothermal agents is introduced. Finally, limitations and challenges of photothermal agents with fluorescence imaging/enhancement in the field of PTT and tumor diagnosis are prospected.

Self-Delivery Nanoplatform Based on Amphiphilic Apoptosis Peptide for Precise Mitochondria-Targeting Photothermal Therapy.

Mitochondria-targeting photothermal therapy could significantly enhance the tumor cell killing effect. However, since therapeutic reagents need to overcome a series of physiological obstacles to arrive at mitochondria accurately, precise mitochondria-targeting photothermal therapy still faces great challenges. In this study, we developed a self-delivery nanoplatform that specifically targeted the mitochondria of tumor cells for precise photothermal therapy. Photothermal agent IR780 was encapsulated by amphiphilic apoptotic peptide KLA with mitochondria-targeting ability to form nanomicelle KI by self-assembly through hydrophilic and hydrophobic interactions. Subsequently, negatively charged tumor-targeting polymer HA was coated on the surface of KI through electrostatic interactions, to obtain tumor mitochondria-targeting self-delivery nanoplatform HKI. Through CD44 receptor-mediated recognition, HKI was internalizated by tumor cells and then disassembled in an acidic environment with hyaluronidase in endosomes, resulting in the release of apoptotic peptide KLA and photothermal agent IR780 with mitochondria anchoring capacity, which achieved precise mitochondria guidance and destruction. This tumor mitochondria-targeting self-delivery nanoplatform was able to effectively deliver photothermal agents and apoptotic peptides to tumor cell mitochondria, resulting in precise destruction to mitochondria and enhancing tumor cell inhibition at the subcellular organelle level.

Carbon dots@noble metal nanoparticle composites: research progress report.

Carbon dots@noble metal nanoparticle composites are formed by combining carbon dots and metal nanoparticles using various strategies. Carbon dots exhibit a reducing ability and function as stabilisers; consequently, metal-ion solutions can be directly reduced by them to synthesise gold, silver, and gold-silver alloy particles. Carbon dots@gold/silver/gold-silver particle composites have demonstrated the potential for several practical applications owing to their superior properties and simple preparation process. Until now, several review articles have been published to summarise fluorescent carbon dots or noble metal nanomaterials. Compared with metal-free carbon dots, carbon dots@noble metal nanoparticles have a unique morphology and structure, resulting in new physicochemical properties, which allow for sensing, bioimaging, and bacteriostasis applications. Therefore, to promote the effective development of carbon dots@noble metal nanoparticle composites, this paper primarily reviews carbon dots@gold/silver/gold-silver alloy nanoparticle composites for the first time in terms of the following aspects. (1) The synthesis strategies of carbon dots@noble metal nanoparticle composites are outlined. The principle and function of carbon dots in the synthesis strategies are examined. The advantages and disadvantages of these methods and composites are analysed. (2) The characteristics and properties of such composites are described. (3) The applications of these composite materials are summarised. Finally, the potentials and limitations of carbon dots@noble metal nanoparticle composites are discussed, thus laying the foundation for their further development.

Damage of polyethylene microplastics on the intestine multilayer barrier, blood cell immune function and the repair effect of Leuconostoc mesenteroides DH in the large-scale loach (Paramisgurnus dabryanus).

Polyethylene microplastics (PE-MPs) has become a global concern due to their widespread distribution and hazardous properties in aquatic habitats. In this study, the accumulation effect of PE-MPs in the intestine of large-scale loach (Paramisgurnus dabryanus) was explored by adding different concentrations of PE-MPs to the water, the destination of PE-MPs after breaking the intestinal barrier and the effects caused. The collected data showed that PE-MPs accumulation for 21d altered the histomorphology and antioxidant enzyme activity of the intestine, induced dysbiosis of the intestinal flora. 10 mg/L of PE-MPs induced a significant increase in the transcript levels of intestinal immunity factors in loach after 21d of exposure. Moreover, the levels of diamine oxidase (DAO) and d-lactic acid (D-Lac) in the gut and serum of loach were significantly increased after exposure to PE-MPs at all concentrations (1, 5, 10 mg/L). Subsequently, the presence of PE-MPs was detected in the blood, suggesting that the disruption of the intestinal multilayer barrier allowed PE-MPs to spill into the circulation. The accumulation of PE-MPs (1,5,10 mg/L) in the blood led to massive apoptosis and necrosis of blood cells and activated phagocytosis in response to PE-MPs invasion. To alleviate the damage, this study further exposure the effect of probiotics on PE-MPs treated loach by adding Leuconostoc mesenteroides DH (109 CFU/g) to the feed. The results showed that DH significantly increased the intestinal index and reduced the levels of DAO and D-Lac. To investigate the reason, we followed the PE-MPs in the intestine and blood of the loach and found that the number of PE-MPs particles was significantly reduced in the probiotic group, while the PE-MPs content in the feces was elevated. Thus, we concluded that DH reducing the accumulation of PE-MPs in the intestinal by increases fecal PE-MPs, which in turn mitigates the damage to the intestinal barrier caused by PE-MPs, and reduces the amount of PE-MPs in the blood. This work offers a robust analysis to understand the mechanisms of damage to the intestinal barrier by MPs and the fate of MPs after escaping the intestinal barrier and provide a new perspective on the application of probiotics in mitigating PE-MPs toxicity.

Functional identification of two HMGB1 paralogues provides insights into autophagic machinery in teleost.

High mobility group box 1 (HMGB1) is a multifunctional regulator that plays different roles in various physiological and pathological processes including cell development, autophagy, inflammation, tumor metastasis, and cell death based on its cellular localization. Unlike mammalian HMGB1, two HMGB1 paralogues (HMGB1a and HMGB1b) have been found in fathead minnow and other fish species and its function as an inflammatory cytokine has been well investigated. However, the role of fish HMGB1 in autophagy regulation has not been well clarified. In the present study, we generated HMGB1 paralogues single (HMGB1a-/- and HMGB1b-/-) and double knockout (DKO) epithelioma papulosum cyprini (EPC) cells from fathead minnow by CRISPR/Cas9 system, and the knockout efficiency of these genes was verified at both gene and protein levels. In this context, the effects of HMGB1 gene knockout on the protein expression of microtubule-associated protein 1 light chain 3 II (LC3-II), an autophagy marker, were determined, showing that single knockout of two HMGB1 paralogues significantly decreased the expression of LC3-II, and these inhibitory effects were further amplified in HMGB1 DKO cells under both basal and rapamycin treatment conditions, indicating the role of two HMGB1 paralogues in fish autophagy. In agreement with this notion, overexpression of HMGB1a or HMGB1b with Flag-tag markedly upregulated LC3-II protein expression. Interestingly, overexpressing two paralogues distributed in both cytoplasm and nucleus. Finally, the role of HMGB1-mediated autophagy was further explored, finding that HMGB1 could interact with Beclin1, a key initiation factor of autophagy. Taken together, these findings highlighted the role of HMGB1 paralogues as the autophagy regulator and increased our understanding of autophagic machinery in teleost.

Edwardsiella piscicida causes iron storage disorders by an autophagy pathway in fish monocytes/macrophages.

Edwardsiella piscicida (E. piscicida) is a gram-negative pathogen that survives in intracellular environment. Currently, the interplay between E. piscicida and host cells has not been completely explored. In this study, we found that E. piscicida disturbed iron homeostasis in grass carp monocytes/macrophages to maintain its own growth. Further investigation revealed the bacteria induced an increase of intracellular iron, which was subjected to the degradation of ferritin. Moreover, the autophagy inhibitor impeded the degradation of ferritin and increase of intracellular iron in E. piscicida-infected monocytes/macrophages, implying possible involvement of autophagy response in the process of E. piscicida-broken iron homeostasis. Along this line, confocal microscopy observed that E. piscicida elicited the colocalization of ferritin with LC3-positive autophagosome in the monocytes/macrophages, indicating that E. piscicida mediated the degradation of ferritin possibly through the autophagic pathway. These results deepened our understanding of the interaction between E. piscicida and fish cells, hinting that the disruption of iron homeostasis was an important factor for pathogenicity of E. piscicida. They also indicated that autophagy was a possible mechanism governing intracellular iron metabolism in response to E. piscicida infection and might offer a new avenue for anti-E. piscicida strategies in the future.

Rapid and sensitive visual detection of avian leukosis virus by reverse transcription loop-mediated isothermal amplification combined with a lateral flow immunochromatographic strip assay.

Considering that avian leukosis virus (ALV) infection has inflicted massive economic losses on the poultry breeding industry in most countries, its early diagnosis remains an important measure for timely treatment and control of the disease, for which a rapid and sensitive point-of-care test is required. We established a user-friendly, economical, and rapid visualization method for ALV amplification products based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) combined with an immunochromatographic strip in a lateral flow device (LFD). Using the ALVp27 gene as the target, five RT-LAMP primers and one fluorescein-isothiocyanate-labeled probe were designed. After 60 min of RT-LAMP amplification at 64 °C, the products could be visualized directly using the LFD. The detection limit of this assay for ALV detection was 102 RNA copies/µL, and the sensitivity was 100 times that of reverse transcription polymerase chain reaction (RT-PCR), showing high specificity and sensitivity. To verify the clinical practicality of this assay for detecting ALV, the gold standard RT-PCR method was used for comparison, and consistent results were obtained with both assays. Thus, the assay described here can be used for rapid detection of ALV in resource-limited environments.

Mechanisms of HIF1A-mediated immune evasion in gastric cancer and the impact on therapy resistance.

BACKGROUND: The high prevalence and detrimental effects on patient outcomes make gastric cancer (GC) a significant health issue that persists internationally. Existing treatment modalities exhibit limited efficacy, prompting the exploration of immune checkpoint inhibitors as a novel therapeutic approach. However, resistance to immunotherapy poses a significant challenge in GC management, necessitating a profound grasp of the intrinsic molecular pathways. METHODS: This study focuses on investigating the immunosuppressive mechanisms of quiescent cancer cells (QCCs) in GC, particularly their resistance to T-cell-mediated immune responses. Utilizing mouse models, gene editing techniques, and transcriptome sequencing, we aim to elucidate the interactions between QCCs, immune cells, and key regulatory factors like HIF1A. Functional enrichment analysis will further underscore the role of glycolysis-related genes in mediating immunosuppression by QCCs. RESULTS: The cancer cells that survived GC treated with T-cell therapy lost their proliferative ability. QCCs, as the main resistance force to immunotherapy, exhibit stronger resistance to CD8+ T-cell attack and possess higher cancer-initiating potential. Single-cell sequencing analysis revealed that the microenvironment in the QCCs region harbors more M2-type tumor-associated macrophages and fewer T cells. This microenvironment in the QCCs region leads to the downregulation of T-cell immune activation and alters macrophage metabolic function. Transcriptome sequencing of QCCs identified upregulated genes related to chemo-resistance, hypoxia, and glycolysis. In vitro cell experiments illustrated that HIF1A promotes the transcription of glycolysis-related genes, and silencing HIF1A in QCCs enhances T-cell proliferation and activation in co-culture systems, induces apoptosis in QCCs, and increases QCCs' sensitivity to immune checkpoint inhibitors. In vivo, animal experiments showed that silencing HIF1A in QCCs can inhibit GC growth and metastasis. CONCLUSION: Unraveling the molecular mechanisms by which QCCs resist T-cell-mediated immune responses through immunosuppression holds promising implications for refining treatment strategies and enhancing patient outcomes in GC. By delineating these intricate interactions, this study contributes crucial insights into precision medicine and improved therapeutic outcomes in GC management.

Second messenger 2'3'-cyclic GMP-AMP (2'3'-cGAMP): the cell autonomous and non-autonomous roles in cancer progression.

Cytosolic double-stranded DNA (dsDNA) is frequently accumulated in cancer cells due to chromosomal instability or exogenous stimulation. Cyclic GMP-AMP synthase (cGAS) acts as a cytosolic DNA sensor, which is activated upon binding to dsDNA to synthesize the crucial second messenger 2'3'-cyclic GMP-AMP (2'3'-cGAMP) that in turn triggers stimulator of interferon genes (STING) signaling. The canonical role of cGAS-cGAMP-STING pathway is essential for innate immunity and viral defense. Recent emerging evidence indicates that 2'3'-cGAMP plays an important role in cancer progression via cell autonomous and non-autonomous mechanisms. Beyond its role as an intracellular messenger to activate STING signaling in tumor cells, 2'3'-cGAMP also serves as an immunotransmitter produced by cancer cells to modulate the functions of non-tumor cells especially immune cells in the tumor microenvironment by activating STING signaling. In this review, we summarize the synthesis, transmission, and degradation of 2'3'-cGAMP as well as the dual functions of 2'3'-cGAMP in a STING-dependent manner. Additionally, we discuss the potential therapeutic strategies that harness the cGAMP-mediated antitumor response for cancer therapy.

Working memory and reward increase the accuracy of animal location encoding in the medial prefrontal cortex.

The ability to perceive spatial environments and locate oneself during navigation is crucial for the survival of animals. Mounting evidence suggests a role of the medial prefrontal cortex (mPFC) in spatially related behaviors. However, the properties of mPFC spatial encoding and how it is influenced by animal behavior are poorly defined. Here, we train the mice to perform 3 tasks differing in working memory and reward-seeking: a delayed non-match to place (DNMTP) task, a passive alternation (PA) task, and a free-running task. Single-unit recording in the mPFC shows that although individual mPFC neurons exhibit spatially selective firing, they do not reliably represent the animal location. The population activity of mPFC neurons predicts the animal location. Notably, the population coding of animal locations by the mPFC is modulated by animal behavior in that the coding accuracy is higher in tasks involved in working memory and reward-seeking. This study reveals an approach whereby the mPFC encodes spatial positions and the behavioral variables affecting it.