Category: 7. Science

Published on July 25 in Matter, Santiago Correa, assistant professor of biomedical engineering at Columbia Engineering, and his collaborators describe an injectable hydrogel platform that uses EVs from milk to address longstanding barriers in the development of biomaterials for regenerative medicine. EVs are particles naturally secreted by cells and carry hundreds of biological signals, like proteins and genetic material, enabling sophisticated cellular communication that synthetic materials cannot easily replicate.

In this study, Correa and colleagues designed a hydrogel system where EVs play a dual role: they act as bioactive cargo but also serve as essential structural building blocks, by crosslinking biocompatible polymers to form an injectable material. Using an unconventional approach that leveraged milk EVs from yogurt, the team was able to overcome yield constraints that hinder the development of EV-based biomaterials. The yogurt EVs enabled the hydrogel to both mimic the mechanics of living tissue and actively engage surrounding cells, promoting healing and tissue regeneration without the need for additional chemical additives.

“This project started as a basic question about how to build EV-based hydrogels. Yogurt EVs gave us a practical tool for that, but they turned out to be more than a model,” said Correa who led the study with Artemis Margaronis, an NSF graduate research fellow in the Correa lab. “We found that they have inherent regenerative potential, which opens the door to new, accessible therapeutic materials.”

Correa directs the Nanoscale Immunoengineering Lab at Columbia University, where his research focuses on drug delivery and immunoengineering. He is also a member of the Herbert Irving Comprehensive Cancer Center and collaborated on this project with Kam Leong, a fellow Columbia Engineering faculty member. The study was further strengthened through international collaboration with researchers from the University of Padova, including Elisa Cimetta (Department of Industrial Engineering) and graduate student Caterina Piunti. By combining Padova team’s expertise in agricultural EV sourcing with the Correa lab’s experience in nanomaterials and polymer-based hydrogels, the team demonstrated the power of cross-disciplinary, global partnerships in advancing biomaterials innovation.

By using yogurt-derived EVs, the team defined a design space for generating hydrogels that incorporate EVs as both structural and biological elements. They further validated the approach using EVs derived from mammalian cells and bacteria, demonstrating that the platform is modular and compatible with diverse vesicle sources. This could open the door to advanced applications in wound healing and regenerative medicine, where current treatments often fall short in promoting long-term tissue repair. By integrating EVs directly into the hydrogel structure, the material enables sustained delivery of their bioactive signals. Because the hydrogel is injectable, it can also be delivered locally to damaged tissue.

Early experiments show that yogurt EV hydrogels are biocompatible and drive potent angiogenic activity within one week in immunocompetent mice, demonstrating that agricultural EVs not only enable fundamental biomaterials research but also hold therapeutic potential as a next-generation biotechnology. In mice, the material showed no signs of adverse reaction and instead promoted the formation of new blood vessels, a key step in effective tissue regeneration. Correa’s team also observed that the hydrogel creates a unique immune environment enriched in anti-inflammatory cell types, which may contribute to the observed tissue repair processes. The team is now exploring how this immune response could help guide tissue regeneration.

“Being able to design a material that closely mimics the body’s natural environment while also speed up the healing process opens a new world of possibilities for regenerative medicine,” said Margaronis. “Moments like these remind me why the research field in biomedical engineering is always on the cusp of something exciting.”

SINGAPORE – Temperatures are rising due to climate change, and the need to help people – especially those from vulnerable communities – cope with the heat is becoming more urgent.

But with warm temperatures being something that many people living in tropical Singapore are already accustomed to, at what point does the heat become a public health risk?

And how is Singapore taking steps to protect people with high exposure to heat, such as outdoor workers?

Join us for a timely dialogue with experts on the issue at the fourth ST Podcasts Live event on Aug 12, which will be held at local swopping boutique The Fashion Pulpit in Jalan Besar.

Titled “Heat Stress & Us”, the dialogue is part of The Straits Times’ Green Pulse podcast, which provides a South-east Asian perspective on climate change and environmental issues.

New episodes are aired every first and third Tuesday of the month.

ST deputy foreign editor David Fogarty and assistant news editor Audrey Tan, who co-host Green Pulse, will be speaking with Associate Professor Jason Lee, director of the Heat Resilience and Performance Centre at the NUS Yong Loo Lin School of Medicine.

Prof Lee is also the lead principal investigator of Project HeatSafe, a research initiative that studies the threat that heat poses to human health, wellbeing, and productivity in South-east Asia.

The dialogue will also involve Ms Jaime Lim, director of the major hazards and the occupational safety and health specialist departments at the Ministry of Manpower.

The Manpower Ministry had in 2023 rolled out new measures that required employers to take steps to protect outdoor workers from heat. Employers, for example, had to provide hourly rest breaks for workers when it gets too hot.

Following the discussion on heat, a second podcast recording will take place.

The second dialogue will touch on the reasons behind the increasing encounters between humans and wildlife in urban Singapore, and how such interactions should be managed to reduce conflict.

One of the recent cases of human-wildlife encounters involve long-tailed macaques spotted within a once-forested area in Punggol that is now a residential area.

The Straits Times earlier reported that the authorities had received over 200 reports of these monkeys over a seven-month period. The animals were spotted rummaging through bins and breaking into homes in search of food.

As Singapore embarks on greening initiatives to infuse the urban landscape with more vegetation, experts have warned that encounters between humans and wildlife will only increase.

A key point of the discussions will be how Singapore can achieve better co-existence between humans and the native wildlife that call the country home.

ST correspondents Shabana Begum and Ang Qing, who were the co-hosts of ST’s award-winning experiential podcast series Green Trails, will helm the second discussion.

They will host Mr Kalaivanan Balakrishnan, the co-chief executive of wildlife rescue group Animal Concerns Research & Education Society (Acres), and Ms Jasvic Lye, the campaign manager of Our Wild Neighbours, an initiative to educate the public on wildlife etiquette.

Passionate about animal welfare, Mr Balakrishnan carried out Acres’ first reptile repatriation in 2017 and was instrumental in ensuring that the wildlife rescue group continued to help animals during the Covid-19 pandemic.  Ms Lye, a fine arts graduate, started her ongoing “Death By Man” photo series in 2017 to shed light on the devastating effects of urbanisation on wildlife.

Guests who sign up will be able to experience a live podcast recording session, and engage in a Q&A segment with panellists. Those interested can sign up at https://str.sg/podcastlive

ST Podcasts Live is a series launched this year to commemorate The Straits Times’ 180th anniversary.

The first ST Podcasts Live, on the topic of historic buildings, took place on Feb 12 at The Foundry. This was followed by the second event on April 15 at The Projector, which discussed diverse definitions of success.

In the third event on June 3 at Raffles Place Rasa, panellists spoke on how to build a fulfilling career. The live podcast on 12 Aug on environmental issues is the fourth in the series.

ST Podcast Live at The Fashion Pulpit

Where:  #04-00 Allenby House, 298 Jln Besar When: August 12, 2025, 7pm to 9pm Topics: [Green Pulse Podcast] Heat Stress & Us [Green Pulse Podcast] Human-wildlife conflict How to sign up: str.sg/podcastlive

Source: The Straits Times © SPH Media Limited. Permission required for reproduction

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Introduction

Corynebacterium striatum has been historically regarded as a component of the normal human skin and nasopharyngeal microbiota, with isolates frequently dismissed as contaminants in laboratory settings.^1,2 However, there has been a notable increase in the incidence of infections attributed to C. striatum in recent years, encompassing a spectrum of clinical presentations including endocarditis, meningitis, wound infections, urinary tract infections, bacteremia, and respiratory tract infections, with instances of hospital outbreaks.^2–8 Moreover, C. striatum is often associated with multidrug resistance, which poses a significant challenge to therapeutic management. Investigating the mechanisms of drug resistance in C. striatum is thus crucial for mitigating the spread of its resistance.

In the course of our clinical practice, we observed the rapid acquisition of resistance to erythromycin by a strain of C. striatum within a period of three days following the initiation of treatment. The objective of the present study is to elucidate the underlying resistance mechanisms of this strain through comparative whole-genome sequencing analysis conducted before and after the emergence of resistance. This will provide a theoretical framework to inform strategies for the prevention and control of drug resistance dissemination in C. striatum. We report the first documentation of plasmid-mediated ermX acquisition conferring erythromycin resistance in C. striatum within 72 hours, elucidating its molecular mechanism.

Materials and Methods

Source of Bacterial Strains

Four C. striatum strains (C1-C4) were consecutively isolated from urine samples of an ICU patient over a 7-day period (September 7–14, 2020). The patient presented with a complicated urinary tract infection (UTI) complicated by co-infections with Candida albicans and Corynebacterium striatum. Antimicrobial therapy was administered sequentially, beginning with micafungin (for fungal coverage), followed by cefoperazone-sulbactam and meropenem (for broad-spectrum bacterial coverage). Four additional strains (C5-C8) from non-ICU patients during the same period served as phylogenetic controls. All isolates were preserved in 40% glycerol at −80°C prior to analysis. All samples were residual specimens obtained during routine hospital diagnostic procedures, not prospectively isolated for this specific research.

Methods

Strain Identification and Antimicrobial Susceptibility Testing

The isolated strains were identified using a MALDI-TOF mass spectrometer from Bruker, Germany, achieving a confidence score greater than 2.0. The minimum inhibitory concentration (MIC) of these strains to commonly used antibiotics was ascertained through the micro-broth dilution method, employing the Corynebacterium detection kit TDR CB-96 by Hunan Mindray Medical Technology Co., Ltd., in strict accordance with the manufacturer’s protocols. Antimicrobial susceptibility testing followed CLSI M45-A3 (2020)⁹ guidelines using cation-adjusted Mueller-Hinton broth microdilution. Quality control included Streptococcus pneumoniae ATCC 49619 and Enterococcus faecalis ATCC 29212.

Whole Genome Sequencing

Our study implemented a de novo assembly approach using Corynebacterium striatum ATCC 6940 as the reference strain. The isolated strain was whole-genome sequenced on Illumina NovaSeq 6000 (2×150 bp, average coverage 100×; effective sequencing depth ≥40× with 95% coverage at 20×) after DNA extraction and library preparation (NEBNext Ultra II FS kit). Raw reads were filtered (Q30≥85%) to remove low-quality bases (Phred≤20 over 40 bp), ambiguous bases (≥10 bp Ns), adapter sequences (≥10 bp overlap), host-derived reads (aligned to hg38), and PCR duplicates, retaining >90% of original data. De novo assembly was performed with SPAdes v3.15.4 (k-mer 21,33,55,77), yielding contigs (N50>100 kb) with 99% mapping rate.

Phylogenetic Tree Analysis Based on Housekeeping Genes

The genomes of the isolated strains were submitted to the Meiji Cloud tool (https://cloud.majorbio.com/page/tools.html) for housekeeping gene annotation, predicting the presence of genes including nusA, infC, rpsJ, rplC, rplB, rpsS, rpsC, rplP, rplN, rplE, rpoB, rplL, rpsB, frr, pgk, smpB, rplA, rplK, rpmA, pyrG, rplF, rpsE, rpsM, rpsK, rplM, rpsI, and rplS. The concatenated housekeeping gene sequences were subsequently analysed using MEGA11 software to deduce the phylogenetic relationships among the isolated strains.

Resistance Gene, Insertion Sequence, and Plasmid Analysis

Annotation of resistance genes was performed using the Comprehensive Antibiotic Resistance Database (CARD) in both strict and perfect modes (identity ≥90%, coverage ≥80%, E-value ≤1e-10). Insertion sequence analysis was performed using the ISfinder database (http://www-is.biotoul.fr/blast.php, 2023 update, E-value ≤0.001). Screening and analysis of plasmids and their components in the genomes of drug-resistant strains was facilitated by the Plasmids in Pathogens database (PIPdb).

Results

Erythromycin Resistance Correlates with ermX Acquisition

Phenotypic Analysis

The four clinical C. striatum strains (C1-C4) exhibited multidrug resistance to β-lactams (penicillin, ceftriaxone, meropenem), fluoroquinolones (ciprofloxacin), and clindamycin, while remaining susceptible to glycopeptides (vancomycin) and lipopeptides (daptomycin). Critically, a 512-fold increase in erythromycin MIC was observed in strains C2-C4 (MIC = 4 μg/mL) compared to the susceptible strain C1 (MIC ≤ 0.25 μg/mL) (Table 1). This abrupt resistance emergence coincided with ermX gene acquisition in C2-C4 (Table 2).

Table 1 Key Antimicrobial Susceptibility Profiles

Table 2 Resistance Gene and Plasmid Features

Genomic Basis of Erythromycin Resistance

Resistance Gene Profiling

Whole-genome sequencing revealed that ermX, a 23S rRNA methyltransferase gene conferring macrolide resistance, was exclusively present in resistant strains C2–C4 (Table 2). No alternative resistance mechanisms—including 23S rRNA mutations, efflux pumps (mefA, msrD), or other methyltransferase genes (ermA, ermB)—were detected (identity ≥90%, coverage ≥80%; CARD v3.2.1).

Mobile Genetic Elements

The ermX gene was located on a conserved 10–11 kb plasmid scaffold flanked by ISL3 family transposases (Table 2). These plasmids shared 99% sequence identity across C2-C4, suggesting clonal dissemination. In contrast, the susceptible strain C1 lacked both ermX and ISL3 elements, further supporting horizontal acquisition of ermX during ICU hospitalization.

Phylogenetic Analysis Confirms Clonal Spread

The housekeeping genes were analyzed on the online tool of Majorbio Cloud Platform (https://cloud.majorbio.com/page/tools/). The resultant phylogenetic tree analysis revealed that, among the strains under investigation, strains C1, C2, C3, and C4 shared the closest phylogenetic ties, suggesting a common ancestral origin. This finding indicates that the observed shifts in strain resistance are attributable to the acquisition of specific resistance mechanisms rather than being a consequence of recurrent infections by strains harbouring disparate resistance profiles (see Figure 1).

Figure 1 The phylogenetic tree constructed based on the sequences of 27 housekeeping genes. The tree was generated using the Neighbour-Joining (1,000 bootstraps) method as implemented in MEGA 11.0. Strains C5-C8 serve as background reference strains and are not included in the drug resistance analysis.

Discussion

In recent years, Corynebacterium striatum has emerged as a novel clinical pathogen that has garnered significant attention.^7,8,10–13 This interest is not only attributable to the diverse infections it can cause but also to its propensity for multidrug resistance, which presents a considerable challenge to clinical therapeutics.^8,14 Our study adds critical insights into this trend by documenting rapid in-host resistance evolution: a urinary isolate (C1) initially erythromycin-susceptible (MIC ≤ 0.25 μg/mL) acquired high-level resistance (MIC≥ 4 μg/mL) within 72 hours, sustained across subsequent isolations (C2-C4). Core genome phylogeny confirmed clonal origin, excluding exogenous reinfection and implicating horizontal gene transfer (HGT) as the resistance driver.

The existing literature indicates that the primary mechanism of erythromycin resistance in Corynebacterium striatum is the presence of the ermX gene.^15–17 This gene mediates the methylation of ribosomal RNA, leading to alterations in the ribosomal structure, which in turn impedes the effective binding of MLS antibiotics (macrolides, lincomycin, and streptogramin) to the ribosomes, thereby diminishing their antibacterial efficacy.^15,18 A study to predict antimicrobial resistance using genomic sequences of 107 isolates of Corynebacterium striatum showed that the majority (97/107) of Corynebacterium striatum carry the ermX gene and ermX gave good agreement (83.33%) values with AST,¹⁶ which is consistent with what we observed. The results of the CARD database analysis showed that the erythromycin-susceptible strains among our isolates carried the vanT and vanW genes, whereas the drug-resistant strains possessed additional ermX genes, confirming that the emergence of drug resistance is associated with the presence of ermX genes.

As is well known, the rapid dissemination of the ermX gene may be associated with a range of mobile genetic elements, encompassing insertion sequences, plasmids, and transposons.^19,20 In particular, the transposon Tn5432, which carries the ermX gene at the interspecies level, is essential for the mechanism of acquired resistance to erythromycin and clindamycin.^17,21,22 The results of plasmid annotation showed that the genomes of the erythromycin-resistant strains among our isolates contained a plasmid carrying the ermX gene, which was absent in the susceptible strains. Similarly, insertion sequence analysis showed that the ermX gene of the erythromycin-resistant strain annotated with four insertion sequences—ISC×1, IS1386, IS31831 and IS1207—which were not detected in the whole genome of the erythromycin-sensitive strain. Tn5432 is a composite transposon that carries a short insertion sequence, ISCx1, referred to as a “genome scar”.^19,23 Several studies have confirmed that the erm (X) gene often appears together with the ISCx1 element in the Tn5432 transposon.^22,24 We can therefore speculate that the plasmid carrying the ermX gene is the reason why our strain has acquired erythromycin resistance.

It is widely recognised that bacterial resistance to certain antimicrobial agents is often associated with their overuse. In this study, the strains under investigation were isolated from patients with urinary tract infections who had concomitant Candida albicans infections. The antimicrobials administered in these cases were micafungin and cefoperazone-sulbactam rather than macrolides. Although no macrolides were administered, β-lactam-induced SOS responses may have upregulated the plasmid conjugation machinery, as reported in Enterococcus.²⁵

While our data robustly link ermX-bearing plasmids to resistance emergence, two paradoxes warrant attention: Accelerated HGT without selective pressure: Unlike Bifidobacterium, where DMSO/vorinostat enhance ermX transfer,²⁶ our patient received no such agents. This implies ICU-specific factors (eg, biofilm-rich catheters or phage-mediated transduction) may drive plasmid spread. Vancomycin susceptibility despite vanT/vanW: The vancomycin-susceptible phenotype (MIC ≤0.5 μg/mL) contrasts with vanT/vanW detection, suggesting non-functional alleles or regulatory suppression—a phenomenon needing transcriptomic validation.

The 72-hour emergence of ermX-mediated resistance necessitates a reevaluation of AST protocols for C. striatum infections. Our findings align with Wang et al showing ICU transmission clusters,²² and Urrutia et al demonstrating ISL3-mediated plasmid transfer.¹⁷ For patients infected with C. striatum, we recommend enhanced antimicrobial susceptibility test through more frequent AST intervals and preemptive ermX screening prior to macrolide therapy initiation.

This study has several important limitations that should be considered when interpreting the results. First, the single-patient case design limits the generalizability of the observed C. striatum resistance dynamics to broader clinical populations. Second, while genomic evidence strongly supports plasmid-mediated ermX transfer, the lack of experimental validation through conjugation assays or transcriptomic analysis of ermX expression represents a key methodological constraint. Future studies should address these limitations through: (1) prospective, multicenter surveillance of ermX acquisition rates in C. striatum, stratified by ICU antibiotic usage patterns and patient comorbidities; (2) functional characterization of ISL3-mediated plasmid transfer using in vitro biofilm models and murine infection assays.

Conclusions

In conclusion, our study documents the rapid emergence of erythromycin resistance in Corynebacterium striatum within a period of only three days. Genomic sequencing analysis revealed that this resistance shift was due to the acquisition of a plasmid containing the ermX gene. This discovery highlights the ability of Corynebacterium striatum to rapidly evolve resistance to erythromycin. However, the underlying cause remains elusive and requires further in-depth investigation. At the same time, it is vital to remain vigilant on the issue of bacterial resistance. Understanding the mechanisms of resistance is essential to inform strategies aimed at reducing the spread of antimicrobial resistance.

Ethical Statement

This study was reviewed and approved by the Ethics Committee of Deyang People’s Hospital. The specimens used were anonymous residual samples collected during routine hospital procedures, with all identifiers permanently removed. This research posed no additional risks to patients and qualified for exemption from informed consent under retrospective study criteria.

Data Availability

The assembled genome files have been archived in the National Microbiology Data Center (NMDC) under the accession numbers NMDC60200991, NMDC60200992, NMDC60200993, and NMDC60200994.

Author Contributions

All authors made a significant contribution to the work reported, whether in conception, study design, execution, data acquisition, analysis and interpretation, or all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Funding

This work was supported by Sichuan Nursing Vocational College Natural Science Project (Grant Number 2023ZRY26).

Disclosure

The authors declare that they have no conflicts of interest in this work.

References

1. Abe M, Kimura M, Maruyama H, et al. Clinical characteristics and drug susceptibility patterns of Corynebacterium species in bacteremic patients with hematological disorders. Eur J Clin Microbiol Infect Dis. 2021;40(10):2095–2104. doi:10.1007/s10096-021-04257-8

2. Milosavljevic MN, Milosavljevic JZ, Kocovic AG, et al. Antimicrobial treatment of Corynebacterium striatum invasive infections: a systematic review. Rev Inst Med Trop São Paulo. 2021;63. doi:10.1590/s1678-9946202163049

3. Melo N, Correia C, Gonçalves J, et al. Corynebacterium striatum cardiac device-related endocarditis: a case report. IDCases. 2022;27. doi:10.1016/j.idcr.2021.e01371

4. Zhang M-J, Cao X-J, Fan J, Yin Z-G, Yu K. Corynebacterium striatum meningitis combined with suspected brain and lung abscesses: a case report and review. BMC Infect Dis. 2020;20(1). doi:10.1186/s12879-020-05114-3

5. Asgin N, Otlu B. Antimicrobial resistance and molecular epidemiology of Corynebacterium striatum isolated in a tertiary hospital in Turkey. Pathogens. 2020;9(2). doi:10.3390/pathogens9020136

6. Lee YW, Huh JW, Hong S-B, et al. Severe pneumonia caused by Corynebacterium striatum in Adults, Seoul, South Korea, 2014–2019. Emerging Infectious Diseases. 2022;28(11):2147–2154. doi:10.3201/eid2811.220273

7. Pannu TS, Villa JM, Ozery M, Piuzzi NS, Higuera CA, Riesgo AM. the fate of periprosthetic joint infection with Corynebacterium striatum: a rare but catastrophic causative organism. J Arthroplasty. 2022;37(1):142–149. doi:10.1016/j.arth.2021.09.023

8. He S-H, Chen Y, Sun H-L, et al. Comparison of bloodstream infections due to Corynebacterium striatum, MRSA, and MRSE. BMC Infect Dis. 2024;24(1). doi:10.1186/s12879-024-09883-z

9. Institute(CLSI) CaLS. Methods for Antimicrobial Dilution and Disk Susceptibility Testing of Infrequently Isolated or Fastidious Bacteria. 3rd ed. Clinical and Laboratory Standards Institute; 2016.

10. Shariff M, Aditi A, Beri K. Corynebacterium striatum: an emerging respiratory pathogen. J Infect Developing Countries. 2018;12(07):581–586. doi:10.3855/jidc.10406

11. Souza C, Simpson-Louredo L, Mota HF, et al. Virulence potential of Corynebacterium striatum towards Caenorhabditis elegans. Antonie van Leeuwenhoek. 2019;112(9):1331–1340. doi:10.1007/s10482-019-01265-9

12. Silva-Santana G, Silva CMF, Olivella JGB, et al. Worldwide survey of Corynebacterium striatum increasingly associated with human invasive infections, nosocomial outbreak, and antimicrobial multidrug-resistance, 1976–2020. Arch Microbiol. 2021;203(5):1863–1880. doi:10.1007/s00203-021-02246-1

13. Streifel AC, Varley CD, Ham Y, Sikka MK, Lewis JS. The challenge of antibiotic selection in prosthetic joint infections due to Corynebacterium striatum: a case report. BMC Infect Dis. 2022;22(1). doi:10.1186/s12879-022-07270-0

14. Camara-Rodriguez M, Jover-Diaz F, Delgado-Sánchez E, Infante-Urríos A, Peris-García J. Dalbavancin as long-term treatment in Corynebacterium striatum Infections: a literature review. Revista Española de Quimioterapia. 2024;37(3):276–278. doi:10.37201/req/149.2023

15. Ortiz-Pérez A, Martín-De-Hijas NZ, Esteban J, Fernández-Natal MI, García-Cía JI, Fernández-Roblas R. High Frequency of macrolide resistance mechanisms in clinical isolates ofCorynebacteriumSpecies. Microb Drug Resist. 2010;16(4):273–277. doi:10.1089/mdr.2010.0032

16. Rocha DJPG, Silva CS, Jesus HNR, et al. Suboptimal bioinformatic predictions of antimicrobial resistance from whole-genome sequences in multidrug-resistant Corynebacterium isolates. J Global Antimicrob Resist. 2024;38:181–186. doi:10.1016/j.jgar.2024.06.006

17. Urrutia C, Leyton-Carcaman B, Abanto Marin M. Contribution of the Mobilome to the Configuration of the Resistome of Corynebacterium striatum. Int J Mol Sci. 2024;25(19). doi:10.3390/ijms251910499

18. Hays C, Lienhard R, Auzou M, et al. Erm(X)-mediated resistance to macrolides, lincosamides and streptogramins in Actinobaculum schaalii. J Antimicrob Chemother. 2014;69(8):2056–2060. doi:10.1093/jac/dku099

19. Leyton B, Ramos JN, Baio PVP, et al. Treat me well or will resist: uptake of mobile genetic elements determine the resistome of Corynebacterium striatum. Int J Mol Sci. 2021;22(14). doi:10.3390/ijms22147499

20. Hennart M, Panunzi L, Rodrigues C, et al. Population genomics and antimicrobial resistance in Corynebacterium diphtheriae. Genome Med. 2020;12(1):107. doi:10.1186/s13073-020-00805-7

21. Tauch A, Krieft S, Kalinowski J, Pühler A. The 51,409-bp R-plasmid pTP10 from the multiresistant clinical isolate Corynebacterium striatum M82B is composed of DNA segments initially identified in soil bacteria and in plant, animal, and human pathogens. Mol Gen Genet. 2000;263(1). doi:10.1007/pl00008668

22. Wang X, Zhou H, Chen D, et al. Whole-genome sequencing reveals a prolonged and persistent intrahospital transmission of Corynebacterium striatum, an emerging multidrug-resistant pathogen. J Clin Microbiol. 2019;57(9). doi:10.1128/jcm.00683-19

23. Sally RP, Stephen MK, Neville F, Slade OJ. Mobile Genetic Elements Associated with Antimicrobial Resistance. Clin Microbiol Rev. 2018;31(4). doi:10.1128/cmr.00088-17

24. Nudel K, Zhao X, Basu S, et al. Genomics of Corynebacterium striatum, an emerging multidrug-resistant pathogen of immunocompromised patients. Clin Microbiol Infect. 2018;24(9):1016.e7–1016.e13. doi:10.1016/j.cmi.2017.12.024

25. Jesús B, Jerónimo R-B, Ivan M. Antibiotic-induced genetic variation: how it arises and how it can be prevented. Annu Rev Microbiol. 2018;72. doi:10.1146/annurev-micro-090817-062139

26. Li B, Chen D, Lin F, et al. Genomic Island-mediated horizontal transfer of the erythromycin resistance gene ermx among bifidobacteria. Appl Environ Microbiol. 2022;88(10):e0041022. doi:10.1128/aem.00410-22

Find the main facts in our quick 1-minute read:

• Official discovery: Astronomers using the Gemini North telescope’s ‘Alopeke speckle imager have likely detected a stellar companion to Betelgeuse for the first time, solving a century‑old hypothesis
• Hypothesis confirmed? The companion aligns with predictions from two 2024 modeling studies that linked Betelgeuse’s roughly 6‑year brightness cycle to a hidden orbiting star
• Imaging technique: By taking thousands of ultra‑short exposures, the team avoided Betelgeuse’s glare and captured the faint signal of the close companion
• Companion properties: The star appears to be about 1.5 times the mass of the Sun, an early-stage pre-main-sequence star (likely A‑ or B‑type), and six magnitudes fainter than Betelgeuse
• Tight orbit: It orbits at roughly four times the Earth–Sun distance, placing it within Betelgeuse’s enormous outer atmosphere
• Mystery solved? This companion offers a natural explanation for Betelgeuse’s Long Secondary Period (LSP) brightness variations, linked to periodic dust distribution changes
• Fate uncertain: Gravitational drag and tidal forces suggest the companion may spiral into and be consumed by Betelgeuse within the next 10,000 years
• Next opportunity: Another observation window in November 2027 should place the companion at its maximum apparent separation—ideal for follow-up study

A striking series of satellite photos shows the brief lifespan of a “ghost island” that emerged and quickly disappeared in the Caspian Sea after an underwater mud volcano blew its top.

The fleeting landmass emerged at the end of January 2023 above Kumani Bank, an underwater volcano about 15 miles (24 kilometers) off the east coast of Azerbaijan. By the time it was fully formed, on Feb. 4, the island measured around 1,300 feet (400 meters) across, according to NASA’s Earth Observatory.

The publisher Frontiers has begun retracting a batch of 122 articles across five journals after an investigation found a network of authors and editors engaged in “unethical actions” such as manipulating citations and reviewing papers without disclosing conflicts of interest. 

The publisher’s research integrity team has identified more than 4,000 articles linked to the network in journals owned by seven other companies, according to a company statement. The team said it is willing to share details and the methodology of their investigation with other publishers upon request. The company is a member of the STM Hub, a platform publishers use to share such information. 

As the publishing industry comes to grips with its paper mill problem, many firms have issued retractions in bulk. Frontiers retracted a batch of 40 in 2023, and a dozen the year before.  

The latest tranche of retractions began to appear July 28. By our count, at least 25 were posted that day. According to one of the notices, which are identical for each paper, the publisher’s investigation “identified this article as one for which the integrity of the peer review process has been undermined, resulting in the loss of confidence in the article’s findings.” 

The investigation “was not able to determine whether all authors, editors, or reviewers were aware of or involved in the misconduct, but this misconduct was significant enough to determine that the scientific integrity of the article cannot be guaranteed,” the notices state. 

A list of the forthcoming retractions Frontiers provided us names one paper from Frontiers in Ecology in Evolution, six from Frontiers in Public Health, 29 from Frontiers in Energy Research, 33 from Frontiers in Environmental Science, and 53 from Frontiers in Psychology. Most were published in 2022. 

The investigation began after a reader noted undisclosed conflicts of interest in the peer review of a single paper, according to the statement. PubPeer user “Desmococcus antarctica” has posted comments on some of the papers to be retracted, identifying instances in which an author and reviewer had previously coauthored a paper together. 

After the first tip, the research integrity team began investigating all the authors’ previous submissions, publications, and coauthor networks, the publisher’s statement said. 

“As the investigation proceeded, it became clear that a broad and sophisticated network of about 35 authors were potentially colluding over a very large number of journals and published papers, a fraction of which were published by Frontiers,” according to the statement. 

Frontiers has an artificial intelligence review system for submitted manuscripts, which now includes verification of the reviewers’ and handling editors’ conflict of interest statements, the company said. 

One of Desmococcus antarctica’s comments on PubPeer pertains to “Households’ Perception and Environmentally Friendly Technology Adoption: Implications for Energy Efficiency,” published in 2022 in Frontiers in Energy Research. The user pointed out that reviewer Muhammad Mohsin, an associate professor in the school of finance and economics at Jiangsu University in China, had previously coauthored a paper with one of the authors. 

Mohsin also served as an editor for the collection in which the paper appeared. Many papers from the collection, which Frontiers calls a “Research Topic,” have been retracted, and Mohsin is listed as the handling editor on several. He did not immediately respond to our request for comment. 

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As human space travel moves closer to long-duration missions to Mars and beyond, an intriguing and complex question emerges: could a baby be conceived, carried, and delivered in space? While it may sound like science fiction, researchers are beginning to seriously investigate what pregnancy and birth would look like in the extreme environment of outer space. According to Science Alert, the biological and technological hurdles are enormous—from the effects of microgravity on fetal development to the invisible threat of cosmic radiation. Arun Vivian Holden, emeritus professor of computational biology at the University of Leeds, explains that while space birth is theoretically possible, nearly every stage of reproduction would be impacted in unpredictable ways.

Birth in space: pregnancy and childbirth challenges in microgravity

In space, microgravity affects the body in countless ways, and pregnancy is no exception. While conception might still be physically possible, carrying a pregnancy in zero gravity introduces major complications. Although an embryo floating in the amniotic sac may resemble a microgravity environment, the absence of gravity during childbirth poses logistical challenges.Fluids, the baby, and even medical tools don’t stay in place, making delivery much more difficult than on Earth. Additionally, caring for a newborn—feeding, cleaning, and simply holding—would be far more complex without the stabilizing effect of gravity.

Space birth and the danger of cosmic radiation

Space birth faces an even more critical hazard: cosmic radiation. Outside Earth’s protective atmosphere and magnetic field, high-energy particles travel through space at nearly the speed of light. These cosmic rays can damage human DNA, destroy cellular structures, and increase the risk of cancer and miscarriage.During the earliest stages of pregnancy, when cells are rapidly dividing and forming key organs, a direct hit from a cosmic ray could cause fatal developmental errors. Though such hits are rare, their consequences could be severe. As the fetus grows larger, the risk increases. A more developed fetus and uterine environment offer a bigger target for radiation, which could trigger preterm labor or developmental abnormalities. Without advanced shielding, space remains an inherently dangerous environment for gestation. Once a baby is born in space, the challenges continue. Microgravity may interfere with the infant’s physical development, including posture, balance, and coordination. These early milestones depend on gravity cues, and their absence could lead to delayed or altered motor skills. At the same time, a newborn’s brain continues to grow rapidly after birth, leaving it vulnerable to radiation damage. This could affect cognition, learning ability, and long-term health.Although the idea of space birth is gaining traction, scientists emphasize that we are far from prepared. Before attempting reproduction in orbit or on another planet, humanity must solve the complex issues of radiation protection, fetal viability, and early development in weightless environments. Until then, space pregnancy remains a frontier of science best explored with caution, simulation, and ethical scrutiny—not premature real-world trials.

“For decades it was assumed that bipedalism arose because we came down from the trees and needed to walk across an open savannah,” said Dr Rhianna Drummond-Clarke of the Max Planck Institute for Evolutionary Anthropology, lead author of the article in Frontiers in Ecology and Evolution. “Here we show that safely and effectively navigating the canopy can remain very important for a large, semi-arboreal ape, even in open habitat. Adaptations to arboreal, rather than terrestrial, living may have been key in shaping the early evolution of the human lineage.”

Habitats and hunger

Issa Valley is divided between a small amount of thick forest surrounding riverbanks and open woodland. The chimpanzees forage more in the woodland during the dry season, when it offers more food. Their habitat and diet are comparable to those of some early hominins, which means their behavior might offer insights into those extinct hominins’ lives.

“Our previous research found that, compared to chimpanzees living in forests, Issa Valley chimpanzees spent just as much time moving in the trees,” said Drummond-Clarke. “We wanted to test if something about how they foraged could explain their unexpectedly high arboreality. Savannah-mosaics are characterized by more sparsely distributed trees, so we hypothesized that adapting behavior to forage efficiently in a tree would be especially beneficial when the next tree is further away.”

Researchers monitored the adults of the Issa community during the dry season, watching how they foraged in trees and what they ate there. The size, height, and shape of the trees were recorded, as well as the number and size of branches.

Issa chimpanzees mostly ate fruit, followed by leaves and flowers — foods found at the ends of branches, so the chimpanzees needed to be capable climbers to reach them safely. They spent longer foraging in trees that were larger and offered more food. The longest foraging sessions, and the most specialized behaviors to navigate thinner terminal branches, were seen in trees with large open crowns offering lots of food: perhaps abundant food justified the extra time and effort. A similar trade-off between the nutritional benefits of specific foods and the effort of acquiring them could also explain why chimpanzees spent longer in trees while eating nutritionally-rich, hard-to-access seeds.

Fast food

Because they are relatively large, chimpanzees move within trees not by climbing on thin branches but by hanging under them, or standing upright and holding on to nearby branches with their hands. Although these ‘safe’ behaviors are traditionally associated with foraging in dense forest, these findings show they’re also important for chimpanzees foraging in a savannah-mosaic.

“We suggest our bipedal gait continued to evolve in the trees even after the shift to an open habitat,” said Drummond-Clarke. “Observational studies of great apes demonstrate they can walk on the ground for a few steps, but most often use bipedalism in the trees. It’s logical that our early hominin relatives also engaged in this kind of bipedalism, where they can hold onto branches for extra balance. If Issa Valley chimpanzees can be considered suitable models, suspensory and bipedal behaviors were likely vital for a large-bodied, fruit-eating, semi-terrestrial hominin to survive in an open habitat.”

However, the researchers say that we need more fossil evidence and more studies on different aspects of chimpanzee foraging to test this idea.

“This study only looked at foraging behavior during the dry season,” cautioned Drummond-Clarke. “It would be interesting to investigate if these patterns remain during the wet season. Analyses of the nutritional value of foods and overall food availability are also needed to test our hypothesis that a strategy of foraging for longer in large trees on certain foods is energy-efficient in an open habitat.

“Importantly, this is also only one community of chimpanzees. Future studies of other chimpanzees living in such dry, open habitats will be vital to see if these patterns are truly a savannah-mosaic signal or unique to Issa.”

The main skeletal fossils preserved of Wudingloong wui gen. et sp. nov. Photo: Courtesy of Chinese Academy of Sciences’ Institute of Vertebrate Paleontology and Paleoanthropology

A new type of sauropod dinosaur species has recently been discovered by Chinese scientists in Chuxiong Yi Autonomous Prefecture, Southwest China’s Yunnan Province. The sauropod species existed around 200 million years ago during the Early Jurassic period, making it the earliest known dinosaur of its kind discovered in East Asia.

Wudingloong wui gen. et sp. nov., or “Wushi Wuding long,” is the name of the newly discovered species. It has slender scapula, long fingers and smooth teeth enamel. According to the forelimb morphology documented in the discovered fossil, the project’s lead You Hailu, a research fellow from the Chinese Academy of Sciences’ Institute of Vertebrate Paleontology and Paleoanthropology, told the Global Times that the species was “likely a bipedal dinosaur.”

The fossil of the dinosaur was perfectly preserved, revealing the species’ cranial and forelimb bones as well as cervical vertebrae. Through phylogenetic analysis, researchers found that the species represents the earliest-diverging sauropod dinosaur currently known in East Asia. 

“This discovery pushes back the origin of dinosaur fauna for us [in China] to the earliest phase of the Jurassic period,” You noted, adding that previously, the oldest known early-diverging sauropod dinosaurs in East Asia were mainly in the mid-Early Jurassic Lufeng dinosaur Formation, in Yunnan. 

“Discovered in Lufeng county, the Lufeng dinosaurs are a sort of ancestors of sauropod dinosaurs,” paleontologist Ma Miao, told the Global Times. The Lufeng dinosaur formation is also a major sedimentary unit for understanding the evolution of the Early Jurassic sauropodomorph dinosaurs. Prior to the current discovery, another type of sauropod dinosaur species had been unearthed in the Lufeng, and was named Xingxiulong yueorum, sp. nov. In 2024, Lishulong wangi, also unearthed in the Lufeng, was identified by researchers as an early-diverging sauropod dinosaur belonging to the “Lufeng” family. 

You told the Global Times that by combining the current discovery of the Wudingloong wui gen. et sp. nov. with those previous finds, the research team is able to establish a “phylogenetic character matrix” that may provide a deeper understanding of the diversity and evolution patterns of dinosaurs discovered in Yunnan. 

The fossil of the Wudingloong wui gen. et sp. nov. was first discovered in 2020 within the Chuxiong’s Wande township in Wuding county. After years of research, the latest discovery was recently published on the international journal Scientific Reports. 

“I hope our research will provide new evidence for understanding the origin and adaptive radiation of sauropod dinosaurs to the international research community,” You noted.