Objective Magnetoreception, the remarkable ability of diverse animals to sense and utilize the geomagnetic field for orientation and navigation, remains a molecularly unresolved mystery in sensory biology. The putative magnetoreceptor (MagR, previously known as IscA1) is a highly conserved iron-sulfur protein implicated in both magnetoreception and iron metabolism; however, the functional diversity among its cross-species homologs remains poorly understood. Cellular morphology is a key genetically determined trait that can be altered through genetic or environmental modifications—a process known as cell morphology engineering. Constructing engineered cells with specific morphological features and magnetic sensitivity to achieve remote, non-invasive magnetic modulation represents a crucial goal in this field with significant application potential. Therefore, this study aims to systematically investigate the effects of MagR heterologous expression on bacterial morphology and magnetic sensing capabilities, screen for MagR-based magnetically sensitive morphology engineering pathways, and reveal the underlying molecular mechanisms. Methods We systematically screened 28 MagR homologous genes from diverse prokaryotic and animal taxa to evaluate their expression and corresponding phenotypic effects in Escherichia coli (E. coli). To compare the differential magnetic responses among bacteria expressing various recombinant MagR proteins, we utilized high-throughput automated bright-field microscopic imaging and scanning electron microscopy (SEM). Furthermore, comprehensive biochemical and biophysical characterizations of iron and iron-sulfur cluster binding were performed using Ferrozine colorimetric assays, electron paramagnetic resonance (EPR) spectroscopy, ultraviolet-visible (UV-Vis) absorption, and circular dichroism (CD) spectroscopy. Additionally, 100 mT static magnetic field (SMF) exposure experiments were conducted to assess magnetically tunable phenotypes, while the intrinsic magnetic properties of purified MagR proteins were directly measured using a superconducting quantum interference device (SQUID) magnetometer. Results Our results demonstrated that the heterologous expression of MagR homologs induced varying degrees of bacterial filamentation. From this comprehensive screen, two distinct morphological patterns were identified: hydra (Hydra vulgaris) MagR (hyMagR) promoted uniform cell elongation and filamentation, exhibiting robust magnetic sensitivity manifested as significantly enhanced filamentation under the 100 mT SMF. In contrast, pigeon (Columba livia) MagR (clMagR) induced only low-frequency, extreme filamentation (sporadically exceeding 80 μm) with a relatively weaker magnetic morphological response. Mechanistically, our data unambiguously proved that these phenotypic differences are primarily driven by distinct iron redox preferences rather than total cellular iron accumulation. Specifically, hyMagR preferentially binds ferrous iron (Fe²⁺), whereas clMagR favors ferric iron (Fe³⁺) and forms more stable iron-sulfur clusters. Intriguingly, although SQUID magnetometry showed that purified clMagR exhibited approximately five-fold higher mass magnetic susceptibility than hyMagR, its cellular magnetic response was weaker. We hypothesize that the Fe²⁺-preferred intracellular environment associated with hyMagR overexpression primes the cell for enhanced generation of reactive oxygen species (ROS) via the Fenton reaction. Exposure to an SMF synergizes with this primed redox state, triggering the bacterial SOS response and upregulating cell division inhibitors to efficiently induce uniform filamentation. Conclusion Our findings identify the Fe²⁺/Fe³⁺ redox state as a critical determinant of MagR-mediated morphological remodeling and magnetic responsiveness. This discovery suggests a potential strategy for engineering magnetically responsive cellular systems for synthetic biology applications, and provides a plausible framework, which potentially combines intrinsic protein magnetism with redox-state modulation, for further investigating the evolutionary mechanisms of MagR-mediated magnetoreception.

Objective Magnetoreception, the remarkable ability of diverse animals to sense and utilize the geomagnetic field for orientation and navigation, remains a molecularly unresolved mystery in sensory biology. The putative magnetoreceptor (MagR, previously known as IscA1) is a highly conserved iron-sulfur protein implicated in both magnetoreception and iron metabolism; however, the functional diversity among its cross-species homologs remains poorly understood. Cellular morphology is a key genetically determined trait that can be altered through genetic or environmental modifications—a process known as cell morphology engineering. Constructing engineered cells with specific morphological features and magnetic sensitivity to achieve remote, non-invasive magnetic modulation represents a crucial goal in this field with significant application potential. Therefore, this study aims to systematically investigate the effects of MagR heterologous expression on bacterial morphology and magnetic sensing capabilities, screen for MagR-based magnetically sensitive morphology engineering pathways, and reveal the underlying molecular mechanisms. Methods We systematically screened 28 MagR homologous genes from diverse prokaryotic and animal taxa to evaluate their expression and corresponding phenotypic effects in Escherichia coli (E. coli). To compare the differential magnetic responses among bacteria expressing various recombinant MagR proteins, we utilized high-throughput automated bright-field microscopic imaging and scanning electron microscopy (SEM). Furthermore, comprehensive biochemical and biophysical characterizations of iron and iron-sulfur cluster binding were performed using Ferrozine colorimetric assays, electron paramagnetic resonance (EPR) spectroscopy, ultraviolet-visible (UV-Vis) absorption, and circular dichroism (CD) spectroscopy. Additionally, 100 mT static magnetic field (SMF) exposure experiments were conducted to assess magnetically tunable phenotypes, while the intrinsic magnetic properties of purified MagR proteins were directly measured using a superconducting quantum interference device (SQUID) magnetometer. Results Our results demonstrated that the heterologous expression of MagR homologs induced varying degrees of bacterial filamentation. From this comprehensive screen, two distinct morphological patterns were identified: hydra (Hydra vulgaris) MagR (hyMagR) promoted uniform cell elongation and filamentation, exhibiting robust magnetic sensitivity manifested as significantly enhanced filamentation under the 100 mT SMF. In contrast, pigeon (Columba livia) MagR (clMagR) induced only low-frequency, extreme filamentation (sporadically exceeding 80 μm) with a relatively weaker magnetic morphological response. Mechanistically, our data unambiguously proved that these phenotypic differences are primarily driven by distinct iron redox preferences rather than total cellular iron accumulation. Specifically, hyMagR preferentially binds ferrous iron (Fe²⁺), whereas clMagR favors ferric iron (Fe³⁺) and forms more stable iron-sulfur clusters. Intriguingly, although SQUID magnetometry showed that purified clMagR exhibited approximately five-fold higher mass magnetic susceptibility than hyMagR, its cellular magnetic response was weaker. We hypothesize that the Fe²⁺-preferred intracellular environment associated with hyMagR overexpression primes the cell for enhanced generation of reactive oxygen species (ROS) via the Fenton reaction. Exposure to an SMF synergizes with this primed redox state, triggering the bacterial SOS response and upregulating cell division inhibitors to efficiently induce uniform filamentation. Conclusion Our findings identify the Fe²⁺/Fe³⁺ redox state as a critical determinant of MagR-mediated morphological remodeling and magnetic responsiveness. This discovery suggests a potential strategy for engineering magnetically responsive cellular systems for synthetic biology applications, and provides a plausible framework, which potentially combines intrinsic protein magnetism with redox-state modulation, for further investigating the evolutionary mechanisms of MagR-mediated magnetoreception.

This study was aimed at identifying the pathogenic bacteria responsible for the death of a young tiger at the Fujian Meihua Mountain South China Tiger Breeding Research Institute.Tissue samples from the lungs,liver,and intestines of the deceased tiger were collected,and the bacteria were cultured inasterile environment.The bacterial strains were characterized according to their morphological and molecular biological properties,including assessment of virulence genes and antibiotic resistance genes,mouse lethality tests,and antibiotic susceptibility evaluations.A predominant bacterial strain isolated from the liver of the deceased tiger was identified as enterotoxigenic Escherichia coli(ETEC)strain Tiger22513F.Phylogenetic analysis of the 16S rRNA gene revealed that the Tiger22513F strain exhibited close genetic similarity to the reference strain ETEC(MF919609.1),with 99.9%nucleotide similarity,and resided on the same evolutionary branch.The Tiger22513F strain contained 11 antibiotic resistance genes(tetA,sul1,sul3,cmlA,floR,blaTEM,blaSHV,blaCMY-2,qnrA,qnrS,and qnrD)along with five virulence genes(VT1,fyuA,tsh,iucD,and ST).Mouse lethality tests indicated significant pathogenicity toward mice,affecting primarily the lungs,liver,and intestines.Antibiotic susceptibility testing demonstrated that this strain exhibited resistance to various classes of beta-lactam antibiotics,as well as quinolones and aminoglycosides.This investigation successfully isolated a multi-drug resistant enterotoxigenic Escherichia coli strain with pronounced pathogenicity from the liver of a deceased tiger;thus providing valuable scientific insights for clinical diagnosis,as well as prevention and control measures,against ETEC infections in South China tigers.

Objective:To analyze the influencing factors for choice of secondary disciplines in eight-year medical students majoring in clinical medicine based on the self-determination theory.Methods:Fourteen eight-year students majoring in clinical medicine in 2018 and 2019 from an affiliated medical school of Peking University Health Science Center were selected to conduct semi-structured interviews using purposive sampling and descriptive phenomenological study methods. The thematic framework method was used to analyze the interview data and refine the theme.Results:Through the analysis of interview data, a total of 3 dimensions were obtained, including 6 first-level topics and 19 second-level topics: ①autonomy dimension (interest factor and value factor); ②dimension of competence (personal trait factor and subject requirement factor); and ③belonging dimension (department factor and mentor factor).Conclusions:The sense of autonomy based on interests and values, the sense of competence matched with personal ability and the characteristics of the discipline, and the sense of belonging brought by the atmosphere of the department and the mentor are important factors influencing the choice of secondary disciplines in eight-year medical students. Teachers and teaching managers should pay attention to the cultivation of students' interests and value guidance, early contact with secondary disciplines, provision of competency training, and promotion of good interaction between students and department tutors, so as to enhance students' sense of belonging and optimize the training model of eight-year excellent doctors.

Objective To investigate the feasibility,efficacy and safety of cold snare polypectomy(CSP)and endoscopic mucosal resection(EMR)in treatment of colonic adenoma in proximity to the orifice of appendix.Methods Clinical data of 41 cases of colonic adenoma in the orifice of appendix treated with CSP(CSP group)and 15 cases treated with EMR(EMR group)from January 2018 to January 2023 were collected.The clinicopathological features and outcomes were analyzed.The main outcome was postoperative complications,including bleeding,perforation and postoperative appendicitis,while the secondary outcome was the total resection rate,block resection rate and local recurrence rate.Results The operation time and treatment cost of CSP group were shorter than EMR group,and the differences were statistically significant(P<0.05).The diameter of applicable lesions in CSP group was smaller than that in EMR group,and the proportion of lesions with tubular adenoma was significantly higher than that in EMR group.There were no significant differences in the time of admission,intestinal preparation score,length of stay,lesion morphology and lesion type between the two groups(P>0.05).Perforation and postoperative appendicitis were not observed in both groups,and delayed postoperative hemorrhage occurred in 1 case in the CSP group,but it could heal itself after surgery without endoscopic intervention.The complete resection rate was 100.0%in both groups.The total removal rate of CSP group was 100.0%,which was significantly higher than that of EMR group(86.7%),and the difference was statistically significant(P<0.05).The local recurrence rate was 2.4%(1/41)in CSP group,and no local recurrence was observed in EMR group(0/15),with no statistical significance(P>0.05).Conclusion CSP and EMR are safe and effective in the treatment of colonic adenoma in proximity to the orifice of appendix,and they are trustworthy.Compared with EMR,CSP is more applied to small diameter tubular adenomas,which has the characteristics of economy and time saving,but at the same time there is the risk of recurrence.EMR obviously has a wider application range,but there is a disadvantage in price and time,and individual cases need to be segmented resection.

This article reports a first case of combined infection with severe fever with thrombocytopenia syndrome(SFTS)and scrub typhus in Dalian City.The patient was admitted to the hospital due to recurrent fever for 7 days and loss of consciousness for 1 day.Pathogen metagenomic sequencing(mNGS),SFTSV quantitative PCR,and enzyme-linked immunosorbent assay(ELISA)IgM tests were performed,showing positive results for Orientia tsutsugamushi and SFTSV nucleic acids.Based on clinical manifestations and epidemiological history,the patient was diagnosed with combined infections.

Objective To explore the behavioral patterns and hippocampal neurogenesis of CHD8+mice,and to provide behavioral and morphological basis for improving autism like behavior and neurogenesis.Methods Genotype of wild type(WT)and CHD8+/-mice was identified.Weight measurement was conducted on both male and female mice of the WT and CHD8+/-strains.Subsequently,a battery of behavioral tests was administered,which included three-chamber test,self-grooming test,nesting test,Y-maze spontaneous alternation test,food burial test,open-field test and light-dark transition test.Afterwards,the mice were administered 2％pentobarbital sodium(2 ml/kg)to induce anesthesia.Their brains were frozen with 4％paraformaldehyde,removed for photography and analysis to identify any alterations in brain size.Western blotting and immunofluorescent labeling were used to detect changes in the process of hippocampus neurogenesis.Results Western blotting analysis demonstrated a decrease in the amounts of chromodomain helicase DNA binding protein 8(CHD8)protein in both male and female mice with CHD8+genotype,as compared to WT mice.There were no notable disparities in body weight between male and female WT and CHD8+mice,as well as in brain size.The three-chamber social behavior test revealed that both male and female CHD8+/-mice had social deficiencies(P＜0.05).During the open field test,there was no significant difference in the total distance moved by male and female WT and CHD8+/-mice.However,the amount of time spent in the central region was considerably lower in CHD8+/-mice compared to the WT mice(P＜0.01).Furthermore,the light-dark transition test revealed that both male and female CHD8+/-mice spent considerably less time investigating the white box compared to the WT mice(P＜0.05).Nevertheless,there were no notable alterations found in self-grooming,nesting,spontaneous alternation of Y-maze,and food burial experiments.In addition,Western blotting result demonstrated a significant drop in doublecortin(DCX)expression(P＜0.001),and immunofluorescent staining revealed a notable reduction in the number of DCX+cells(P＜0.01)in the hippocampus of CHD8+/-mice.Conclusion CHD8+/-mice exhibit social disorders and anxiety-like behaviors,with a decrease in the number of newly generated neurons in the hippocampus and neurogenesis disorders.

OBJECTIVE: To evaluate the efficacy and safety of Shexiang Tongxin Dropping Pill (STDP) in treating stable angina patients with phlegm-heat and blood-stasis syndrome by exercise duration and metabolic equivalents. METHODS: This multicenter, randomized, double-blind, placebo-controlled clinical trial enrolled stable angina patients with phlegm-heat and blood-stasis syndrome from 22 hospitals. They were randomized 1:1 to STDP (35 mg/pill, 6 pills per day) or placebo for 56 days. The primary outcome was the exercise duration and metabolic equivalents (METs) assessed by the standard Bruce exercise treadmill test after 56 days of treatment. The secondary outcomes included the total angina symptom score, Chinese medicine (CM) symptom scores, Seattle Angina Questionnaire (SAQ) scores, changes in ST-T on electrocardiogram and adverse events (AEs). RESULTS: This trial enrolled 309 patients, including 155 and 154 in the STDP and placebo groups, respectively. STDP significantly prolonged exercise duration with an increase of 51.0 s, compared to a decrease of 12.0 s with placebo (change rate: -11.1% vs. 3.2%, P<0.01). The increase in METs was significantly greater in the STDP group than in the placebo group (change: -0.4 vs. 0.0, change rate: -5.0% vs. 0.0%, P<0.01). The improvement of total angina symptom scores (25.0% vs. 0.0%), CM symptom scores (38.7% vs. 11.8%), reduction of nitroglycerin consumption (100.0% vs. 11.3%), and all domains of SAQ, were significantly greater with STDP than placebo (all P<0.01). The changes in Q-T intervals at 28 and 56 days from baseline were similar between the two groups (both P>0.05). Twenty-five participants (16.3%) with STDP and 16 (10.5%) with placebo experienced AEs (P=0.131), with no serious AEs observed. CONCLUSION STDP could improve exercise tolerance in patients with stable angina and phlegm-heat and blood stasis syndrome, with a favorable safety profile. (Registration No. ChiCTR-IPR-15006020).
Humans ; Double-Blind Method ; Drugs, Chinese Herbal/adverse effects* ; Male ; Female ; Middle Aged ; Angina, Stable/physiopathology* ; Aged ; Syndrome ; Treatment Outcome ; Placebos ; Tablets