Identification of microRNAs and their target genes associated with chasmogamous and cleistogamous flower development in Viola prionantha.

MAIN CONCLUSION: Differentially expressed microRNAs were found associated with the development of chasmogamous and cleistogamous flowers in Viola prionantha, revealing potential roles of microRNAs in the developmental evolution of dimorphic flowers. In Viola prionantha, chasmogamous (CH) flowers are induced by short daylight, while cleistogamous (CL) flowers are triggered by long daylight. How environmental factors and microRNAs (miRNAs) affect dimorphic flower formation remains unknown. In this study, small RNA sequencing was performed on CH and CL floral buds at different developmental stages in V. prionantha, differentially expressed miRNAs (DEmiRNAs) were identified, and their target genes were predicted. In CL flowers, Viola prionantha miR393 (vpr-miR393a/b) and vpr-miRN3366 were highly expressed, while in CH flowers, vpr-miRN2005, vpr-miR172e-2, vpr-miR166m-3, vpr-miR396f-2, and vpr-miR482d-2 were highly expressed. In the auxin-activated signaling pathway, vpr-miR393a/b and vpr-miRN2005 could target Vpr-TIR1/AFB and Vpr-ARF2, respectively, and other DEmiRNAs could target genes involved in the regulation of transcription, e.g., Vpr-AP2-7. Moreover, Vpr-UFO and Vpr-YAB5, the main regulators in petal and stamen development, were co-expressed with Vpr-TIR1/AFB and Vpr-ARF2 and showed lower expression in CL flowers than in CH flowers. Some V. prionantha genes relating to the stress/defense responses were co-expressed with Vpr-TIR1/AFB, Vpr-ARF2, and Vpr-AP2-7 and highly expressed in CL flowers. Therefore, in V. prionantha, CH-CL flower development may be regulated by the identified DEmiRNAs and their target genes, thus providing the first insight into the formation of dimorphic flowers in Viola.

Ultrathin Ni-Fe MOF Nanosheets: Efficient and Durable Water Oxidation at High Current Densities.

Efficient, durable, and economical electrocatalysts are crucial for advancing energy technology by facilitating the oxygen evolution reaction (OER). Here, ultrathin Ni-Fe metal-organic skeleton (MOF) nanosheets were created in situ on nickel foam (NiFe-UMNs/NF). The catalyst exhibited excellent OER catalytical abilities, with only 269 mV overpotentials at 250 mA cm-2. Besides, when integrated with Pt/C/NF, NiFe-UMNs/NF held the potential for application in industrial alkaline water electrolysis with an initial voltage retention of approximately 86% following a continuous operation of 100 h at a current density of 250 mA cm-2. The super performance of the NiFe-UMNs/NF catalyst was attributed to ultrathin morphology, super hydrophilicity, and synergistic effects between Ni and Fe within the MOF. In situ Raman showed that NiFe-UMNs were converted to NiFeOOH as the active species in the OER process. Density functional theory revealed that iron doping accelerated the rate-determining step and reduced the OER reaction energy barrier. This work elucidated a promising electrocatalyst for OER and enriched the practical implementation of MOF materials.

Electrodeposition-Assisted Crystal Growth Regulation of PdBi Clusters on Carbon Cloths for Ethanol Oxidation.

Carbon-supported Pd-based clusters are one of the most promising anodic catalysts for ethanol oxidation reaction (EOR) due to their encouraging activity and practical applications. However, unclear growth mechanism of Pd-based clusters on the carbon-based materials has hindered their extensive applications. Herein, we first introduce multi-void spherical PdBi cluster/carbon cloth (PdBi/CC) composites by an electrodeposition routine. The growth mechanism of PdBi clusters on the CC supports has been systemically investigated by evaluating the selected samples and tuning their compositions, which involve the big difference in standard redox potential between Pd2+/Pd and Bi3+/Bi and easy adsorption of Bi3+ on the surface of Pd-rich seeds. Benefitting from the ensembles of many nanocrystal subunits, multi-void spherical PdBi clusters can present collective properties and novel functionalities. In addition, the outstanding characteristics of CC supports enable PdBi clusters with stable nanostructures. Thanks to the unique structure, Pd20Bi/CC catalysts manifest higher EOR activity and better stability compared to Pd/CC. Systematic characterizations and a series of CO poisoning tests further confirm that the dramatically enhanced EOR activity and stability can be attributed to the incorporation of Bi species and the strong coupling of the structure between PdBi clusters and CC supports.

Transcriptomic comparison sheds new light on regulatory networks for dimorphic flower development in response to photoperiod in Viola prionantha.

BACKGROUND: Chasmogamous (CH)-cleistogamous (CL) dimorphic flowers are developed in Viola prionantha. However, the environmental and genetic factors necessary for the CH-CL transition are unknown. RESULTS: In the present work, short-day (SD) conditions induced CH flowers, whereas long days (LDs) triggered CL flowers in V. prionantha. Compared to fully developed CH flowers, CL flowers had less mature stamens, no nectar glands, and immature petals. Comparative transcriptomics revealed differentially expressed genes (DEGs) during CL and CH development. Core genes in the photoperiod pathway, such as V. prionantha orthologs of GIGANTEA (GI), CONSTANS (CO), and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), which promote floral induction, were highly expressed in CL flowers, whereas UNUSUAL FLORAL ORGANS (UFO) and B-class MADS-box genes for floral organ identity and development showed an opposite alteration. Moreover, genes in the glycolytic process, sucrose metabolic process, and fatty acid biosynthetic process were all highly expressed in CH flowers. Interestingly, V. prionantha orthologs of the B-class MADS-box genes APETALA3 (AP3) and PISTILLATA (PI) might relate to these sugar-fatty acid processes and were co-expressed with GAIP-B-like and YABBY5 (YAB5), which regulate the development of the petal, stamen, and nectary. Compared to CH flowers, DEGs and hub genes in the most significantly correlated modules of the gene co-expression network, which are involved in abiotic and biotic responses, were upregulated in CL flowers. CONCLUSIONS: We proposed an integrative model for transcription regulation of genes in the photoperiod pathway, floral organ development, stress response, and sugar-fatty acid processes to determine CH-CL flower development in V. prionantha. Particularly, under LDs, activated GI may induce genes involved in the stress-response pathways, and then downregulated AP3 and PI or UFO to inhibit the sugar-fatty acid metabolic processes, together forming CL flowers. In contrast, CH flowers were produced under SDs. This work provides novel insights into the developmental evolution of dimorphic flowers in Viola.

Resveratrol protects human luteinised granulosa cells against hydrogen peroxide-induced oxidative injury through the Sirt1.

Granulosa cells (GCs) control follicular development and are important for female reproduction. Resveratrol (Res) was considered as an antioxidant and Sirt1 inducer. Hydrogen peroxide (H2O2) is the classical reagent to study oxidative stress. The study was conducted to investigate the role of Res against H2O2 in human luteinised granulosa cells (LGCs). The LGCs in the H2O2 group were treated with 100µmol/L H2O2 for 24h. The LGCs in the Res group were treated with 50µmol/L Res for 2h, followed by H2O2. The LGCs in the Sirt1 blockage group were treated with 2.5µmol/L EX527+50µmol/L Res for 2h, followed by H2O2. Results showed that Res significantly increased LGCs viability in H2O2-induced LGCs. The apoptotic rate and ROS in the H2O2 group was higher and the antioxidant enzyme activity was lower compared with other groups. Following the Res, the apoptotic rate and ROS level were reduced and the antioxidant enzyme activity were increased. In the Res blockage group, no significant alterations in the cell apoptosis, ROS and antioxidant enzyme activity were observed compared with the H2O2 group. The Res group had a Caspase-3 downregulation and Sirt1 upregulation compared with the other groups. In conclusion, Res had a protective effect against the H2O2-induced LGCs, and the mechanism may be associated with Sirt1.

Molecular cloning, characterization and expression analysis of CbPLDδ gene from Chorispora bungeana in low temperature.

Chorispora bungeana (C. bungeana) is a rare alpine subnival species that is highly tolerant to low temperature stress. Phospholipase D (PLD) is a key enzyme involved in membrane phospholipid catabolism during plant growth and the stress response. In this study, one member of CbPLD gene family, CbPLDδ, was cloned from C. bungeana and was introduced into tobacco. This gene encodes an 864-amino acid protein with two catalytic HxKxxxxD motifs which are essential for phospholipase D activity. After the CbPLDδ gene is fused with the vector containing the GFP tag, subcellular localization showed that CbPLDδ was predominately located in the cell membrane. RT-qPCR and histochemical GUS assays showed that CbPLDδ gene was induced by low temperature and expressed predominantly in leaf and root. Compared with wild-type tobacco, CbPLDδ transgenic tobacco showed higher activities of antioxidant enzymes, and lower levels of malonidiadehyde and electrolyte leakage under low temperature stress. These results reflected that CbPLDδ is involved in the response to low temperature stress, and has the potential to improve the low temperature tolerance of plants.

Alleviation of osmotic stress by H2S is related to regulated PLDα1 and suppressed ROS in Arabidopsis thaliana.

Hydrogen sulfide (H2S) is an important gaseous molecule responding to osmotic stress in plant. Phospholipase Dα1 (PLDα1) and reactive oxygen species (ROS) are involved in many biotic or abiotic stress responses. Using the seedlings of Arabidopsis thaliana ecotype (WT), PLDα1 deficient mutant (pldα1) and the L-cysteine desulfhydrase (L-DEs) deficient mutant (lcd) as materials, the effect of H2S responding to osmotic stress and the functions of PLDα1 and ROS in this response were investigated. The results showed that H2S, PLDα1 and ROS were involved in osmotic stress resistance. Exogenous sodium hydrosulfide (NaHS) promoted the endogenous H2S content and up-regulated the expression of LCD in WT, lcd and plda1. Exogenous phosphatidic acid (PA) enhanced the H2S content and up-regulated the expressions of LCD in WT and plda1 but had no significant effect on the H2S content and LCD expression in lcd under osmotic stress. This suggested that H2S was located downstream of PLDα1 to participate in the osmotic stress signal response. Exogenous NaHS treatment regulated the antioxidant enzymes (SOD, POD, and CAT). The activities and the gene relative expressions of antioxidant enzymes in pldα1 and lcd were higher than those in WT under osmotic stress. This indicated that H2S and PLD regulated the antioxidant enzyme system under osmotic stress. The ROS level, electrolyte leakage (EL), malondialdehyde (MDA) were decreased by NaHS under osmotic stress, demonstrating H2S maintained the membrane integrity. All of these results revealed that H2S alleviated the osmotic stress by elevating PLD and suppressing ROS in A. thaliana.

Nickel Nitride Particles Supported on 2D Activated Graphene-Black Phosphorus Heterostructure: An Efficient Electrocatalyst for the Oxygen Evolution Reaction.

Hydrogen is regarded as the most promising green clean energy in the 21st century. Developing the highly efficient and low-cost electrocatalysts for oxygen evolution reaction (OER) is of great concern for the hydrogen industry. In the water electrolyzed reaction, the overpotential and the kinetics are the main hurdles for OER. Therefore, an efficient and durable oxygen evolution reaction electrocatalyst is required. In this study, an activated graphene (AG)-black phosphorus (BP) nanosheets hybrid is fabricated for supporting Ni3 N particles (Ni3 N/BP-AG) in the application of OER. The Ni3 N particles are combined with the BP-AG heterostructure via facile mechanical ball milling under argon protection. The synthesized Ni3 N/BP-AG shows excellent catalytic performance toward the OER, demanding the overpotential of 233 mV for a current density of 10 mA cm-2 with a Tafel slope of 42 mV dec-1 . The Ni3 N/BP-AG catalysts also show remarkable stability with a retention rate of the current density of about 86.4% after measuring for 10 000 s in potentiostatic mode.

Expression of B-class MADS-box genes in response to variations in photoperiod is associated with chasmogamous and cleistogamous flower development in Viola philippica.

BACKGROUND: Some plants develop a breeding system that produces both chasmogamous (CH) and cleistogamous (CL) flowers. However, the underlying molecular mechanism remains elusive. RESULTS: In the present study, we observed that Viola philippica develops CH flowers with short daylight, whereas an extended photoperiod induces the formation of intermediate CL and CL flowers. In response to long daylight, the respective number and size of petals and stamens was lower and smaller than those of normally developed CH flowers, and a minimum of 14-h light induced complete CL flowers that had no petals but developed two stamens of reduced fertility. The floral ABC model indicates that B-class MADS-box genes largely influence the development of the affected two-whorl floral organs; therefore, we focused on characterizing these genes in V. philippica to understand this particular developmental transition. Three such genes were isolated and respectively designated as VpTM6-1, VpTM6-2, and VpPI. These were differentially expressed during floral development (particularly in petals and stamens) and the highest level of expression was observed in CH flowers; significantly low levels were detected in intermediate CL flowers, and the lowest level in CL flowers. The observed variations in the levels of expression after floral induction and organogenesis apparently occurred in response to variations in photoperiod. CONCLUSIONS: Therefore, inhibition of the development of petals and stamens might be due to the downregulation of B-class MADS-box gene expression by long daylight, thereby inducing the generation of CL flowers. Our work contributes to the understanding of the adaptive evolutionary formation of dimorphic flowers in plants.

Oxygen Vacancy-Enhanced Ni3N-CeO2/NF Nanoparticle Catalysts for Efficient and Stable Electrolytic Water Splitting.

Highly efficient and cost-effective electrocatalysts are of critical significance in the domain of water electrolysis. In this study, a Ni3N-CeO2/NF heterostructure is synthesized through a facile hydrothermal technique followed by a subsequent nitridation process. This catalyst is endowed with an abundance of oxygen vacancies, thereby conferring a richer array of active sites. Therefore, the catalyst demonstrates a markedly low overpotential of 350 mV for the Oxygen Evolution Reaction (OER) at 50 mA cm-2 and a low overpotential of 42 mV for the Hydrogen Evolution Reaction (HER) at 10 mA cm-2. Serving as a dual-function electrode, this electrocatalyst is employed in overall water splitting in alkaline environments, demonstrating impressive efficiency at a cell voltage of 1.52 V of 10 mA cm-2. The in situ Raman spectroscopic analysis demonstrates that cerium dioxide (CeO2) facilitates the rapid reconfiguration of oxygen vacancy-enriched nickel oxyhydroxide (NiOOH), thereby enhancing the OER performance. This investigation elucidates the catalytic role of CeO2 in augmenting the OER efficiency of nickel nitride (Ni3N) for water electrolysis, offering valuable insights for the design of high-performance bifunctional catalysts tailored for water splitting applications.

Oxygen Vacancy and Heterostructure Modulation of Co2P/Fe2P Electrocatalysts for Improving Total Water Splitting.

Designing a stable and highly active catalyst for hydrogen evolution and oxygen evolution reactions (HER/OER) is essential for the industrialization of hydrogen energy but remains a major challenge. This work reports a simple approach to fabricating coupled Co2P/Fe2P nanorod array catalyst for overall water decomposition, demonstrating the source of excellent activity in the catalytic process. Under alkaline conditions, Co2P/Fe2P heterostructures exhibit an overpotential of 96 and 220 mV for HER and OER, respectively, at 10 mA cm-2. For total water splitting, a low voltage of 1.56 V is required to provide a current density of 10 mA cm-2. And the catalyst exhibits long-term durability for 30 h at a high current density of 250 mA cm-2. The analysis of the results revealed that the presence of interfacial oxygen vacancies and the strong interaction between Co2P/Fe2P provided the catalyst with more electrochemically active sites and a faster charge transfer capability, which improved the hydrolysis dissociation process. Electrochemically active metal (oxygen) hydroxide phases were produced after OER stability testing. The results of this study prove its great potential in practical industrial electrolysis and provide a reasonable and feasible strategy for the design of nonprecious metal phosphide electrocatalysts.

Overcoming erlotinib resistance with tailored treatment regimen in patient-derived xenografts from naïve Asian NSCLC patients.

Overall benefits of EGFR-TKIs are limited because these treatments are largely only for adenocarcinoma (ADC) with EGFR activating mutation. The treatments also usually lead to development of resistances. We have established a panel of patient-derived xenografts (PDXs) from treatment naïve Asian NSCLC patients, including those containing "classic" EGFR activating mutations. Some of these EGFR-mutated PDXs do not respond to erlotinib: LU1868 containing L858R/T790M mutations, and LU0858 having L858R mutation as well as c-MET gene amplification, both squamous cell carcinoma (SCC). Treatment of LU0858 with crizotinib, a small molecule inhibitor for ALK and c-MET, inhibited tumor growth and c-MET activity. Combination of erlotinib and crizotinib caused complete response, indicating the activation of both EGFR and c-MET promote its growth/survival. LU2503 and LU1901, both with wild-type EGFR and c-MET gene amplification, showed complete response to crizotinib alone, suggesting that c-MET gene amplification, not EGFR signaling, is the main oncogenic driver. Interestingly, LU1868 with the EGFR L858R/T790M, but without c-met amplification, had a complete response to cetuximab. Our data offer novel practical approaches to overcome the two most common resistances to EGFR-TKIs seen in the clinic using marketed target therapies.

Curved Porous PdCu Metallene as a High-Efficiency Bifunctional Electrocatalyst for Oxygen Reduction and Formic Acid Oxidation.

Designing high-efficiency and newly developed Pd-based bifunctional catalytic materials still faces tremendous challenges for oxygen reduction reaction (ORR) and formic acid oxidation reaction (FAO). Metallene materials with unique structural features are considered strong candidates for enhancing the catalytic performance. In this work, we synthesized copper-doped two-dimensional curved porous Pd metallene nanomaterials via a simplistic one-pot solvothermal method. The updated catalysts served as sturdy bifunctional electrocatalysts for cathodal ORR and anodic FAO. In particular, the developed PdCu metallene exhibits excellent half-wave potential (0.943 V vs RHE) and mass activity (MA) (1.227 A mgPt-1) in alkaline solutions, which are 1.09 and 6.26 times higher than those of commercial Pt/C, respectively, indicating that the nanomaterials have abundant active sites, displaying surpassing catalytic performance for oxygen reduction. Furthermore, in an acidic formic acid electrolyte, PdCu metallene exhibits prominent MA with a value of 0.905 A mgPd-1, which is 2.76 times that of commercial Pd/C. The remarkable bifunctional catalytic performance of metallene materials can be attributed to the special structure and electronic effects. This work shows that metallene materials with curved and porous properties provide a scientific idea for the development and design of efficient and steady electrocatalysts.

Top-down manufacturing of efficient CO2 reduction catalysts from the gasification residue carbon.

Gram scale preparation of carbon-supported single-atom catalysts was achieved via a top-down approach starting from metallic and metalloid constituent-enriched gasification residual carbon, exhibiting superior electrocatalytic performance for CO2-to-CO conversion in both H-type and membrane electrode assembly electrolyzers.

Zinc induced phytotoxicity mechanism involved in root growth of Triticum aestivum L.

This study investigated the inhibition mechanism of root growth in wheat seedlings when exposed to different zinc (Zn) concentrations. All applied Zn concentration did not affect seed germination, but reduced root length; in contrast, only Zn at 3mM inhibited significantly the growth of shoot. The loss of cell viability and the significant increases of lignification as well as the increases of hydrogen peroxide (H(2)O(2)), superoxide radical (O(2)(-)) and malondialdehyde levels were observed in the root tissue exposed to Zn treatment. And also, Zn stress led to the inhibition of cell-wall bound peroxidase. Moreover, NADPH oxidase inhibitor diphenylene iodonium could block greatly the elevation of O(2)(-) generation in Zn-treated roots. Therefore, the increased H(2)O(2) generation was dependent on the extracellular O(2)(-) production derived from plasma membrane NADPH oxidase. In addition, the loss of cell viability and the significant increases of lignification in response to the highest Zn concentration may be associated with the remarkable reduction of root growth in wheat seedlings.

Target-induced silver nanocluster generation for highly sensitive electrochemical aptasensor towards cell-secreted interferon-γ.

Interferon-gamma (IFN-γ) is one kind of crucial inflammatory cytokines, and its expression level is closely associated with various disease progressions. This work addresses the development of a sensitive and specific electrochemical assay for detection of IFN-γ by combing the recognition unit of aptamer with the signal reporter of target-induced silver nanoclusters (AgNCs). For biosensor preparation, the gold nanoparticles (AuNPs) immobilized on the amine-terminated electrode surface provided electrochemical interfaces for the self-assembly of C-rich modified aptamers. Then, the aptamer recognized IFN-γ and the free aptamer hybridized with conjugated DNA sequences. After the nuclease-catalyzed cleavage of DNA duplex, in situ-generated AgNCs in the C-rich template was utilized as the electrochemical indicator for IFN-γ detection. The present method demonstrated a good performance for detection of IFN-γ with a low detection limit of 1.7 pg mL-1. This aptasensor was verified to be applied for the evaluation of IFN-γ secreted by cell.

Cholecystokinin octapeptide significantly suppresses collagen-induced arthritis in mice by inhibiting Th17 polarization primed by dendritic cells.

Cholecystokinin octapeptide (CCK-8) is a neuropeptide, and is shown to be a potent immunomodulator with predominant anti-inflammatory effects. Although the regulatory effect of CCK-8 on macrophages and B cells has been defined, the effect of CCK-8 on dendritic cells (DCs) and T cells is not well understood. In this study, we showed that CCK-8 reduced the expression of CD80, CD86, and MHCII on DCs. Moreover, CCK-8 promoted Th1 and inhibited Th17 polarization by increasing the production of IL-12 and decreasing the production of IL-6 and IL-23 on DCs in vitro and in vivo. In addition, intraperitoneal administration of CCK-8 to mice with collagen-induced arthritis (CIA) was found to effectively reduce the incidence of arthritis, delay its onset and prevent the occurrence of joint damage. Collectively, these results suggest that CCK-8 significantly suppresses the incidence and severity of CIA in mice, through the inhibition of DC mediated Th17 polarization.

Cholecystokinin octapeptide exerts its therapeutic effects on collagen-induced arthritis by suppressing both inflammatory and Th17 responses.

The purpose of this study was to evaluate the potential therapeutic effect of cholecystokinin octapeptide (CCK-8) on collagen-induced arthritis (CIA), an accepted murine experimental disease model with diverse histopathological features similar to human rheumatoid arthritis (RA). CIA was induced in DBA/1J mice by immunization with chicken collagen type II (CII). CCK-8 at different doses was intraperitoneally administered daily for 1 week. Mice treated with CCK-8 at doses of 5 and 10 nmol but not 1 nmol displayed much delayed onset of CIA and significantly lower incidence and decreased severity of arthritis. CCK-8 treatment significantly reduced the production of cytokines (IL-17, IL-23, IL-6 and TNF-α) and chemokines monocyte chemoattractant protein 1 in the joints of arthritic mice or in synovial cell culture supernatant, and increased the levels of IFN-γ and TGF-ß. T cells from CCK-8 treated mice proliferated much less, produced low level of IL-17 and high levels of IFN-γ and TGF-ß. Moreover, CCK-8 treated mice showed lower levels of CII-specific IgG, particularly that of IgG2a, in sera than those from control mice. These results indicate that CCK-8 is effective in suppressing both inflammatory and Th17 responses in CIA. CCK-8 may represent a new therapeutic modality for rheumatoid arthritis.

Cholecystokinin octapeptide regulates lipopolysaccharide-activated B cells co-stimulatory molecule expression and cytokines production in vitro.

Cholecystokinin octapeptide (CCK8) can exert the immunoregulatory roles through activating immune cell surface receptors such as T lymphocytes, macrophages, dendritic cells, and so on. In this study, we discussed the effects of CCK8 on lipopolysaccharide (LPS)-activated B cells in terms of the expression of co-stimulatory molecules, and the capacity to activate CD4(+) T cells and cytokines production in vitro. The results revealed that B cells expressed two types of CCK receptors; CCK8 inhibited the expression of co-stimulatory molecules such as CD80 and CD86 on LPS-activated B cells, suppressed the proliferation of allogeneic T cells in a dose-dependent manner, and also reduced the secretion of Th1-type cytokine IFN-γ, whereas enhanced the secretion of Th2-type cytokine IL-4 by LPS-activated B cells. Both CCK1R and CCK2R participated in these effects. Taken together, CCK8 is capable of exerting immunomodulatory functions through B cells.

Effect of Different Iron Sources on In-Situ Growth of Zeolitic Imidazolate Frameworks-8: For Efficient Oxygen Reduction Electrocatalysts.

Transition metal and nitrogen co-doped carbon-based catalysts (TM-N-C) have become the most promising catalysts for Pt/C due to their wide range of sources, low cost, high catalytic activity, excellent stability and strong resistance to poisoning, especially Fe-N-C metal-organic frameworks (MOFs), which are some of the most promising precursors for the preparation of Fe-N-C catalysts due to their inherent properties, such as their highly ordered three-dimensional framework structure, controlled porosity, and tuneable chemistry. Based on these, in this paper, different iron sources were added to synthesis a sort of zeolitic imidazole frameworks (ZIF-8). Then the imidazole salt in ZIF-8 was rearranged into high N-doped carbon by high-temperature pyrolysis to prepare the Fe-N-C catalyst. We studied the physical characteristics of the catalysts by different iron sources and their effects on the catalytic properties of the oxygen reduction reaction (ORR). From the point of morphology, various iron sources have a positive influence on maintaining the morphology of ZIF-8 polyhedron. Fe-N/C-Fe(NO3)3 has the same anion as zinc nitrate, and can maintain a polyhedral morphology after high-temperature calcination. It had the highest ORR catalytic activity compared to the other four catalyst materials, which proved that there is a certain relationship between morphology and performance. This paper will provide a useful reference and new models for the development of high-performance ORR catalysts without precious metals.