Effect of Cytochrome P450 3A4 on Tissue Distribution of Humantenmine, Koumine, and Gelsemine, three Alkaloids from the Toxic Plant Gelsemium.

Humantenmine, koumine, and gelsemine are three indole alkaloids found in the highly toxic plant Gelsemium. Humantenmine was the most toxic, followed by gelsemine and koumine. The aim of this study was to investigate and analyze the effects of these three substances on tissue distribution and toxicity in mice pretreated with the Cytochrome P450 3A4 (CYP3A4) inducer ketoconazole and the inhibitor rifampicin. The in vivo test results showed that the three alkaloids were absorbed rapidly and had the ability to penetrate the blood-brain barrier. At 5minutes after intraperitoneal injection, the three alkaloids were widely distributed in various tissues and organs, the spleen and pancreas were the most distributed, and the content of all tissues decreased significantly at 20minutes. Induction or inhibition of CYP3A4 in vivo can regulate the distribution and elimination effects of the three alkaloids in various tissues and organs. Additionally, induction of CYP3A4 can reduce the toxicity of humantenmine, and vice versa. Changes in CYP3A4 levels may account for the difference in toxicity of humantenmine. These findings provide a reliable and detailed dataset for drug interactions, tissue distribution, and toxicity studies of Gelsemium alkaloids.

Buffer Chain Model for Understanding Crystallization Competition in Conjugated Polymers.

It remains challenging to comprehensively understand the packing models of conjugated polymers, in which side chains play extremely critical roles. The side chains are typically flexible and non-conductive and are widely used to improve the polymer solubility in organic solutions. Herein, a buffer chain model is proposed to describe link between conjugated backbone and side chains for understanding the relationship of crystallization competition of conductive conjugated backbones and non-conductive side chains. A longer buffer chain is beneficial for alleviating such crystallization competition and further promoting the spontaneous packing of conjugated backbones, resulting in enhanced charge transport properties. Our results provide a novel concept for designing conjugated polymers towards ordered organization and enhanced electronic properties and highlight the importance of balancing the competitive interactions between different parts of conjugated polymers.

Grid-plainification enables medium-temperature PbSe thermoelectrics to cool better than Bi2Te3.

Thermoelectric cooling technology has important applications for processes such as precise temperature control in intelligent electronics. The bismuth telluride (Bi2Te3)-based coolers currently in use are limited by the scarcity of Te and less-than-ideal cooling capability. We demonstrate how removing lattice vacancies through a grid-design strategy switched PbSe from being useful as a medium-temperature power generator to a thermoelectric cooler. At room temperature, the seven-pair device based on n-type PbSe and p-type SnSe produced a maximum cooling temperature difference of ~73 kelvin, with a single-leg power generation efficiency approaching 11.2%. We attribute our results to a power factor of >52 microwatts per centimeter per square kelvin, which was achieved by boosting carrier mobility. Our demonstration suggests a path for commercial applications of thermoelectric cooling based on Earth-abundant Te-free selenide-based compounds.

Synergistically optimized electron and phonon transport in high-performance copper sulfides thermoelectric materials via one-pot modulation.

Optimizing thermoelectric conversion efficiency requires the compromise of electrical and thermal properties of materials, which are hard to simultaneously improve due to the strong coupling of carrier and phonon transport. Herein, a one-pot approach realizing simultaneous second phase and Cu vacancies modulation is proposed, which is effective in synergistically optimizing thermoelectric performance in copper sulfides. Multiple lattice defects, including nanoprecipitates, dislocations, and nanopores are produced by adding a refined ratio of Sn and Se. Phonon transport is significantly suppressed by multiple mechanisms. An ultralow lattice thermal conductivity is therefore obtained. Furthermore, extra Se is added in the copper sulfide for optimizing electrical transport properties by inducing generating Cu vacancies. Ultimately, an excellent figure of merit of ~1.6 at 873 K is realized in the Cu1.992SSe0.016(Cu2SnSe4)0.004 bulk sample. The simple strategy of inducing compositional and structural modulation for improving thermoelectric parameters promotes low-cost high-performance copper sulfides as alternatives in thermoelectric applications.

Network Pharmacology and Experimental Validation Explore the Pharmacological Mechanisms of Herb Pair for Treating Rheumatoid Arthritis.

OBJECTIVE: This study aimed to elucidate the multitarget mechanism of the Mori Ramulus - Taxilli Herba (MT) herb pair in treating rheumatoid arthritis (RA). METHODS: The targets of the herb pair and RA were predicted from databases and screened through cross-analysis. The core targets were obtained using protein-protein interaction (PPI) network analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed. Finally, animal experiments were conducted to validate the anti-RA effect and mechanism of this herb pair. RESULTS: This approach successfully identified 9 active compounds of MT that interacted with 6 core targets (AKT1, TNF, IL6, TP53, VEGFA, and IL1ß). Pathway and functional enrichment analyses revealed that MT had significant effects on the TNF and IL-17 signaling pathways. The consistency of interactions between active components and targets in these pathways was confirmed through molecular docking. Moreover, the potential therapeutic effect of MT was verified in vivo, demonstrating its ability to effectively relieve inflammation by regulating these targeted genes and pathways. CONCLUSION: The present work suggests that the therapeutic effect of MT herb pair on RA may be attributed to its ability to regulate the TNF signaling pathway and IL-17 signaling pathway.

Realizing High Thermoelectric Properties in Bi2 S3 Bulk via Band Engineering and Nanorods Compositing.

Bismuth sulfide is a promising thermoelectric material because of its low cost and toxicity; however, its low electrical conductivity limits its thermoelectric properties. In this study, Bi2 S3 +x wt% HfCl4 (x = 0, 0.25, 0.5, 0.75, and 1.0) bulk samples are fabricated using a combination of melting and spark plasma sintering. The microstructures, electronic structures, and thermoelectric properties of the composites are characterized. The results of electronic structure calculations show that doping with HfCl4 produces an impurity energy level that narrows the bandgap and allows the Fermi energy level to enter the conduction band, leading to a favorable increase in carrier concentration. By regulating the HfCl4 doping concentration, the electrical conductivity of the 0.75 wt% doped sample reaches 253 Scm-1 at 423 K and its maximum ZT value is 0.47 at 673 K. Moreover, the sample is compounded with Bi2 S3 nanorods prepared by the hydrothermal method, reducing thermal conductivity by 30% due to the introduction of additional interfaces and pores. This resulted in a final ZT value of 0.61 at 673 K, which is approximately eight times higher than that of pure Bi2 S3 . This step-by-step optimization approach provides a valuable methodology for enhancing the performance of other thermoelectric material systems.

Large Mobility Enables Higher Thermoelectric Cooling and Power Generation Performance in n-type AgPb18+xSbTe20 Crystals.

The room-temperature thermoelectric performance of materials underpins their thermoelectric cooling ability. Carrier mobility plays a significant role in the electronic transport property of materials, especially near room temperature, which can be optimized by proper composition control and growing crystals. Here, we grow Pb-compensated AgPb18+xSbTe20 crystals using a vertical Bridgman method. A large weighted mobility of ∼410 cm2 V-1 s-1 is achieved in the AgPb18.4SbTe20 crystal, which is almost 4 times higher than that of the polycrystalline counterpart due to the elimination of grain boundaries and Ag-rich dislocations verified by atom probe tomography, highlighting the significant benefit of growing crystals for low-temperature thermoelectrics. Due to the largely promoted weighted mobility, we achieve a high power factor of ∼37.8 µW cm-1 K-2 and a large figure of merit ZT of ∼0.6 in AgPb18.4SbTe20 crystal at 303 K. We further designed a 7-pair thermoelectric module using this n-type crystal and a commercial p-type (Bi, Sb)2Te3-based material. As a result, a high cooling temperature difference (ΔT) of ∼42.7 K and a power generation efficiency of ∼3.7% are achieved, revealing promising thermoelectric applications for PbTe-based materials near room temperature.

Conjugated [5]Cumulene Polymers Enabled by Condensation Polymerization of Propargylic Electrophiles.

Cumulenes, sp-hybridized carbon motifs featuring consecutive double bonds, have rarely been explored as π-elements for conjugated polymers. Long cumulenic conjugated polymers can serve as models for approaching carbyne, an intriguing yet elusive carbon allotrope. However, their synthesis is notoriously difficult due to intrinsic instability. To date, only few [3]cumulene-based polymers have been synthesized, mostly relying on surface chemistry. Higher cumulene-based polymers remain unknown. Here, we present a "meet in the middle" strategy to overcome this challenge and synthesize high-molecular-weight, stable, and solution-processable conjugated [5]cumulene polymers (Mw up to 67.9 kg/mol). Our approach involves a new polymerization method called step-growth condensation polymerization of propargylic electrophiles (step-growth CPPE). The structures and molecular weights of the cumulenic polymers are established by various spectroscopic methods, including a comparative analysis of a discrete oligomer series. By introducing ortho-substituents on the aryl side groups, we successfully address the stability-conjugation dilemma. Electronic communication between cumulene units is found to be contingent upon the aromaticity of the π-spacers, enabling flexible energy-level adjustment and new narrow band gap polymers. The synthetic methodology and structure-property relationship established in this work serve as the starting points for the exploration of this fascinating family of sp-carbon-rich materials.

Protocol to characterize target components of Gelsemium using an in-house herb database and high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.

Currently, the identification of herb metabolites is challenging due to a lack of clear standards. Here, using Gelsemium as an example, we present a protocol for characterizing target components of herbs. This approach utilizes high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry guided by an in-house herb metabolite database based on reported studies and mass spectrometry. We describe steps for creating an in-house database, preparing and detecting samples, processing data, and characterizing compounds. This approach offers a reference for future research on the identification of herb metabolites. For complete details on the use and execution of this protocol, please refer to Liu et al. (2017).1.

Identifying therapeutic biomarkers of zoledronic acid by metabolomics.

Zoledronic acid (ZOL) is a potent antiresorptive agent that increases bone mineral density (BMD) and reduces fracture risk in postmenopausal osteoporosis (PMOP). The anti-osteoporotic effect of ZOL is determined by annual BMD measurement. In most cases, bone turnover markers function as early indicators of therapeutic response, but they fail to reflect long-term effects. We used untargeted metabolomics to characterize time-dependent metabolic shifts in response to ZOL and to screen potential therapeutic markers. In addition, bone marrow RNA-seq was performed to support plasma metabolic profiling. Sixty rats were assigned to sham-operated group (SHAM, n = 21) and ovariectomy group (OVX, n = 39) and received sham operation or bilateral ovariectomy, respectively. After modeling and verification, rats in the OVX group were further divided into normal saline group (NS, n = 15) and ZOL group (ZA, n = 18). Three doses of 100 µg/kg ZOL were administrated to the ZA group every 2 weeks to simulate 3-year ZOL therapy in PMOP. An equal volume of saline was administered to the SHAM and NS groups. Plasma samples were collected at five time points for metabolic profiling. At the end of the study, selected rats were euthanatized for bone marrow RNA-seq. A total number of 163 compound were identified as differential metabolites between the ZA and NS groups, including mevalonate, a critical molecule in target pathway of ZOL. In addition, prolyl hydroxyproline (PHP), leucyl hydroxyproline (LHP), 4-vinylphenol sulfate (4-VPS) were identified as differential metabolites throughout the study. Moreover, 4-VPS negatively correlated with increased vertebral BMD after ZOL administration as time-series analysis revealed. Bone marrow RNA-seq showed that the PI3K-AKT signaling pathway was significantly associated with ZOL-mediated changes in expression (adjusted-p = 0.018). In conclusion, mevalonate, PHP, LHP, and 4-VPS are candidate therapeutic markers of ZOL. The pharmacological effect of ZOL likely occurs through inhibition of the PI3K-AKT signaling pathway.

Density of States Engineering of n-Doped Conjugated Polymers for High Charge Transport Performances.

Charge transport of conjugated polymers in functional devices closely relates to their density of states (DOS) distributions. However, systemic DOS engineering for conjugated polymers is challenging due to the lack of modulated methods and the unclear relationship between DOS and electrical properties. Here, the DOS distribution of conjugated polymers is engineered to enhance their electrical performances. The DOS distributions of polymer films are tailored using three processing solvents with different Hansen solubility parameters. The highest n-type electrical conductivity (39 ± 3 S cm-1 ), the highest power factor (63 ± 11 µW m-1 K-2 ), and the highest Hall mobility (0.14 ± 0.02 cm2 V-1 s-1 ) of the polymer (FBDPPV-OEG) are obtained in three films with three various DOS distributions, respectively. Through theoretical and experimental exploration, it is revealed that the carrier concentration and transport property of conjugated polymers can be efficiently controlled by DOS engineering, paving the way for rationally fabricating organic semiconductors.

5-epi-ent-Kaurane diterpenoids from the aerial parts of Isodon eriocalyx and their anti-atherosclerotic potential.

The phytochemical investigation of the EtOAc extract from the aerial parts of Isodon eriocalyx afforded seventeen diterpenoids, including eight undescribed compounds. Eriocalyxins H-L have unique structural characteristics featuring a 5-epi-ent-kaurane diterpenoid scaffold with eriocalyxins H-K also possess an unusual 6,11-epoxyspiro-lactone ring while eriocalyxin L, a 1,7:3,20-diepoxy-ent kaurene, features an 1,7-oxygen linkage. The structures of these compounds were elucidated by spectroscopic data interpretation, and the absolute configurations of eriocalyxins H, I, L, and M were confirmed by single-crystal X-ray diffraction. The isolates were screened for their inhibitory activities against VCAM-1 and ICAM-1 at 5 µM. While eriocalyxin O, coetsoidin A and laxiflorin P were found to significantly inhibit both VCAM-1 and ICAM-1, 8 (17),13-ent-labdadien-15 â†’ 16-lactone-19-oic acid displayed evidently inhibitory effect against ICAM-1.

High n-type and p-type conductivities and power factors achieved in a single conjugated polymer.

The charge transport properties of conjugated polymers are commonly limited by the energetic disorder. Recently, several amorphous conjugated polymers with planar backbone conformations and low energetic disorder have been investigated for applications in field-effect transistors and thermoelectrics. However, there is a lack of strategy to finely tune the interchain π-π contacts of these polymers that severely restricts the energetic disorder of interchain charge transport. Here, we demonstrate that it is feasible to achieve excellent conductivity and thermoelectric performance in polymers based on thiophene-fused benzodifurandione oligo(p-phenylenevinylene) through reducing the crystallization rate of side chains and, in this way, carefully controlling the degree of interchain π-π contacts. N-type (p-type) conductivities of more than 100 S cm-1 (400 S cm-1) and power factors of more than 200 µW m-1 K-2 (100 µW m-1 K-2) were achieved within a single polymer doped by different dopants. It further demonstrated the state-of-the-art power output of the first flexible single-polymer thermoelectric generator.

[Moxibustion for rheumatoid arthritis and its effect on related negative emotions].

OBJECTIVE: To observe the clinical efficacy of moxibustion on rheumatoid arthritis (RA) and its effect on related negative emotions, and to explore the possible mechanism. METHODS: A total of 70 patients with RA were randomized into an observation group (35 cases, 1 case dropped off) and a control group (35 cases, 2 cases dropped off). Conventional western medication therapy was adopted in the control group. On the basis of the treatment in the control group, moxibustion at Zusanli (ST 36), Shenshu (BL 23) and ashi points was adopted in the observation group, once every other day, 3 times a week, and totally 5-week treatment was required in the two groups. Before and after treatment, the scores of visual analogue scale (VAS), morning stiffness, 28-joint disease activity score (DAS28), self-rating anxiety scale (SAS) and self-rating depression scale (SDS) were observed and levels of serum 5-hydroxytryptamine (5-HT), glucocorticoid receptor (GR) and interleukin (IL)-1ß were detected by ELISA method in the two groups respectively. RESULTS: Compared before treatment, the scores of VAS and DAS28 were decreased after treatment in both groups (P<0.01, P<0.05), and the scores of morning stiffness, SAS, SDS and the serum levels of 5-HT, GR, IL-1ß were decreased after treatment in the observation group (P<0.01). After treatment, the scores of VAS, morning stiffness, DAS28, SAS, SDS and the serum levels of GR, IL-1ß in the observation group were lower than those in the control group (P<0.05, P<0.01). The clinical symptoms of RA (scores of VAS, morning stiffness and DAS28) were positively correlated with negative emotions (scores of SAS and SDS, r=0.439, P<0.01), the VAS score was positively correlated with serum levels of 5-HT (r=0.189, P<0.05) and IL-1ß (r=0.189, P<0.05). CONCLUSION: Moxibustion can improve the clinical symptoms and negative emotions in patients with RA by regulating the inflammatory reactions.

Bacillus amyloliquefaciens GB03 augmented tall fescue growth by regulating phytohormone and nutrient homeostasis under nitrogen deficiency.

Nitrogen is an important nutrient for plant growth and development. Soil microorganisms have been used to curb the imbalance between the limited content of natural environmental nitrogen and the pollution caused by increasing nitrogen fertilizer use in ecologically fragile areas. Bacillus amyloliquefaciens GB03 has been shown to confer growth promotion and abiotic stress tolerance in Arabidopsis thaliana. This study provided a new insight into the role of the plant growth-promoting rhizobacterium B. amyloliquefaciens GB03 as an initiator of defense against nitrogen deficiency in non-leguminous grass tall fescue (Festuca arundinacea). Two-week-old seedlings of tall fescue were grown with or without GB03 for 4 weeks under total nitrogen (3.75 mM NO3 -) or low nitrogen (0.25 mM NO3 -) treatment. Growth parameters, chlorophyll content, endogenous total nitrogen, total phosphorus content, and phytohormone content, including those of auxin indole-3-acetic acid, cytokinin, gibberellic acid, and abscisic acid, were determined at the time of harvest. Tall fescue grown in GB03-inoculated soil was more robust than the non-inoculated controls with respect to plant height, root length, plant biomass, chlorophyll concentration, and nutrient (total nitrogen and total phosphorus) contents under total nitrogen treatment. GB03 increased indole acetic acid content by 24.7%, whereas decreased cytokinin and abscisic acid contents by 28.4% and 26.9%, respectively, under a total nitrogen level. Remarkably, GB03 increased indole acetic acid content by more than 80% and inhibited abscisic acid production by nearly 70% under a low nitrogen level. These results showed, for the first time, that GB03 played a crucial role in mediating NO3 -dependent regulation of tall fescue growth and development, especially revealing the mechanism of soil bacteria improve resistance to nitrogen deficiency stress in non-nitrogen-fixing species.

Two-Dimensional Liquid Chromatography Method for the Determination of Gelsemium Alkaloids in Honey.

Toxic Chinese medicine residues in honey pose a serious threat to consumer health. Gelsemium is one of the nine ancient poisons, making the whole plant virulent. The residue of Gelsemium alkaloid in honey causes poisoning from time to time. Therefore, it is very important to establish a method for the detection of Gelsemium alkaloids in honey. In this study, a method of solid phase extraction (SPE) with two-dimensional liquid chromatography (2D-LC) was developed for the first time for the simultaneous determination of Gelsemium alkaloids in honey, including gelsemine, koumine and humantenmine. First, the honey samples were purified by a PRS cation exchange column and extracted with 5% ammoniated methanol. Then, we verified the methodological indicators, which were in line with the Codex Guideline requirements. The verification results are as follows: matrix-matched calibrations indicated that the correlation coefficients were higher than 0.998. The recovery was in the range of 81%-94.2% with an intraday precision (RSD) of ≤5.0% and interday RSD of ≤3.8%. The limit of detection for the three alkaloids was 2 ng/g. The limits of quantification for gelsemine and koumine were 5 ng/g, and humantenmine was 20 ng/g. This method can be applied to the monitoring of Gelsemium alkaloids in honey.

Bi0.33(Bi6S9)Br compositing in Bi2S3 bulk materials forwards high thermoelectric properties.

The hexagonal Bi0.33(Bi6S9)Br intermediate was incorporated to enhance the thermoelectric properties of Bi2S3 by a facile synthesis process. As a result of the increase of carrier concentration caused by Br diffusion doping and the enhancement of phonon scattering caused by pores, point defects, and secondary phase interfaces, a maximum ZT value of 0.64 was achieved at 773 K in Bi2S3 + 5% Bi0.33(Bi6S9)Br. This study provides a strategy for achieving Br doping in the Bi2S3 system by adding the Bi0.33(Bi6S9)Br intermediate alloy, while the nanostructure was maintained in the matrix, which may be also suitable for other thermoelectric materials to obtain higher performance.

New 4',5'-methylenedioxyflavone derivatives from the whole plant of sarcandra glabra.

Two new natural products named 5,7-dihydroxy-3,3',6,8-tetramethoxy-4',5'-methylenedioxyflavone (1) and 3,3',5,7-tetramethoxy-4',5'-methylenedioxyflavone (2), along with thirteen known compounds, ß-sitosterol (3), desmethoxyyangonin (4), hexadecane (5), 3,9-bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane 3,9-dioxide (6), 2'6'-dihydroxy-4'-methoxydihydrochalcone (7), cardamonin (8), 3,3',5,6,7,8-hexamethoxy-4',5'-methylenedioxyflavone (9), isofraxidin (10), aniba dimer A (11), 3,3',4',5,5',8-hexamethoxy-6,7-methylenedioxyflavone (12), quercetin (13), quercitrin (14) and isoquercitrin (15) were isolated from Sarcandra glabra (Thunb.) Nakai by various chromatographic methods. Compounds 1, 2, 4, 6, 11, and 12 were isolated from S. glabra for the first time. Their chemical structures were identified through the analysis of NMR and HR-MS spectra. The anti-inflammatory and cytotoxic activities of compounds 1-15 were evaluated in cell assays. The results indicated that compounds 1, 7, 8, 10, 14, and 15 significantly inhibited the NO production in LPS-induced RAW 264.7 murine macrophage cells. Moreover, compounds 1, 3, 4, 7, 8, 9, 10 and 12 exhibited a cytotoxic effect on the human HepG2 cell line.

AtNusG, a chloroplast nucleoid protein of bacterial origin linking chloroplast transcriptional and translational machineries, is required for proper chloroplast gene expression in Arabidopsis thaliana.

In Escherichia coli, transcription-translation coupling is mediated by NusG. Although chloroplasts are descendants of endosymbiotic prokaryotes, the mechanism underlying this coupling in chloroplasts remains unclear. Here, we report transcription-translation coupling through AtNusG in chloroplasts. AtNusG is localized in chloroplast nucleoids and is closely associated with the chloroplast PEP complex by interacting with its essential component PAP9. It also comigrates with chloroplast ribosomes and interacts with their two components PRPS5 (uS5c) and PRPS10 (uS10c). These data suggest that the transcription and translation machineries are coupled in chloroplasts. In the atnusg mutant, the accumulation of chloroplast-encoded photosynthetic gene transcripts, such as psbA, psbB, psbC and psbD, was not obviously changed, but that of their proteins was clearly decreased. Chloroplast polysomic analysis indicated that the decrease in these proteins was due to the reduced efficiency of their translation in this mutant, leading to reduced photosynthetic efficiency and enhanced sensitivity to cold stress. These data indicate that AtNusG-mediated coupling between transcription and translation in chloroplasts ensures the rapid establishment of photosynthetic capacity for plant growth and the response to environmental changes. Therefore, our study reveals a conserved mechanism of transcription-translation coupling between chloroplasts and E. coli, which perhaps represents a regulatory mechanism of chloroplast gene expression. This study provides insights into the underlying mechanisms of chloroplast gene expression in higher plants.

AtRsmD Is Required for Chloroplast Development and Chloroplast Function in Arabidopsis thaliana.

AtRsmD was recently demonstrated to be a chloroplast 16S rRNA methyltransferase (MTase) for the m2G915 modification in Arabidopsis. Here, its function of AtRsmD for chloroplast development and photosynthesis was further analyzed. The AtRsmD gene is highly expressed in green photosynthetic tissues. AtRsmD is associated with the thylakoid in chloroplasts. The atrsmd-2 mutant exhibited impaired photosynthetic efficiency in emerging leaves under normal growth conditions. A few thylakoid lamellas could be observed in the chloroplast from the atrsmd-2 mutant, and these thylakoids were loosely organized. Knockout of the AtRsmD gene had minor effects on chloroplast ribosome biogenesis and RNA loading on chloroplast ribosomes, but it reduced the amounts of chloroplast-encoded photosynthesis-related proteins in the emerging leaves, for example, D1, D2, CP43, and CP47, which reduced the accumulation of the photosynthetic complex. Nevertheless, knockout of the AtRsmD gene did not cause a general reduction in chloroplast-encoded proteins in Arabidopsis grown under normal growth conditions. Additionally, the atrsmd-2 mutant exhibited more sensitivity to lincomycin, which specifically inhibits the elongation of nascent polypeptide chains. Cold stress exacerbated the effect on chloroplast ribosome biogenesis in the atrsmd-2 mutant. All these data suggest that the AtRsmD protein plays distinct regulatory roles in chloroplast translation, which is required for chloroplast development and chloroplast function.