Sesamol Alleviates Sarcopenia via Activating AKT/mTOR/FoxO1 Signal Pathway in Aged Obese Mice.

Sesamol is a major bioactive component extracted from sesame seeds and has various medicinal properties. However, the effects of sesamol on sarcopenia associated with aging and obesity remains unclear. Therefore, the protective effects and underlying mechanisms of sesamol on sarcopenia was evaluated in aged and obese C57BL/6 J male mouse models fed a high fat diet and C2C12 myotubes co-treated with D-gal and PA in this study. Our in vivo data showed that sesamol activated AKT/mTOR/FoxO1 signal pathway, and then upregulated p-p70S6K and p-4EBP1 to promote myoprotein synthesis, and downregulated Atrogin-1 and MuRF1 to inhibit myoprotein degradation, thus ameliorating sarcopenia related to aging and obesity. Furthermore, our in vitro results confirmed the protective effect and aforementioned mechanisms of sesamol on sarcopenia. Collectively, sesamol could alleviate sarcopenia associated with aging and obesity via activating the AKT/mTOR/FoxO1 signal pathway. Our findings highlight the therapeutic potentials of sesamol for aging and obesity-related metabolic muscular complications.

Examining the Pathogenesis of MAFLD and the Medicinal Properties of Natural Products from a Metabolic Perspective.

Metabolic-associated fatty liver disease (MAFLD), characterized primarily by hepatic steatosis, has become the most prevalent liver disease worldwide, affecting approximately two-fifths of the global population. The pathogenesis of MAFLD is extremely complex, and to date, there are no approved therapeutic drugs for clinical use. Considerable evidence indicates that various metabolic disorders play a pivotal role in the progression of MAFLD, including lipids, carbohydrates, amino acids, and micronutrients. In recent years, the medicinal properties of natural products have attracted widespread attention, and numerous studies have reported their efficacy in ameliorating metabolic disorders and subsequently alleviating MAFLD. This review aims to summarize the metabolic-associated pathological mechanisms of MAFLD, as well as the natural products that regulate metabolic pathways to alleviate MAFLD.

The beneficial rhizobacterium Bacillus velezensis SQR9 regulates plant nitrogen uptake via an endogenous signaling pathway.

Nitrogen fertilizer is widely used in agriculture to boost crop yields. Plant growth-promoting rhizobacteria (PGPRs) can increase plant nitrogen use efficiency through nitrogen fixation and organic nitrogen mineralization. However, it is not known whether they can activate plant nitrogen uptake. In this study, we investigated the effects of volatile compounds (VCs) emitted by the PGPR strain Bacillus velezensis SQR9 on plant nitrogen uptake. Strain SQR9 VCs promoted nitrogen accumulation in both rice and Arabidopsis. In addition, isotope labeling experiments showed that strain SQR9 VCs promoted the absorption of nitrate and ammonium. Several key nitrogen-uptake genes were up-regulated by strain SQR9 VCs, such as AtNRT2.1 in Arabidopsis and OsNAR2.1, OsNRT2.3a, and OsAMT1 family members in rice, and the deletion of these genes compromised the promoting effect of strain SQR9 VCs on plant nitrogen absorption. Furthermore, calcium and the transcription factor NIN-LIKE PROTEIN 7 play an important role in nitrate uptake promoted by strain SQR9 VCs. Taken together, our results indicate that PGPRs can promote nitrogen uptake through regulating plant endogenous signaling and nitrogen transport pathways.

Trichoderma-secreted anthranilic acid promotes lateral root development via auxin signaling and RBOHF-induced endodermal cell wall remodeling.

Trichoderma spp. have evolved the capacity to communicate with plants by producing various secondary metabolites (SMs). Nonhormonal SMs play important roles in plant root development, while specific SMs from rhizosphere microbes and their underlying mechanisms to control plant root branching are still largely unknown. In this study, a compound, anthranilic acid (2-AA), is identified from T. guizhouense NJAU4742 to promote lateral root development. Further studies demonstrate that 2-AA positively regulates auxin signaling and transport in the canonical auxin pathway. 2-AA also partly rescues the lateral root numbers of CASP1pro:shy2-2, which regulates endodermal cell wall remodeling via an RBOHF-induced reactive oxygen species burst. In addition, our work reports another role for microbial 2-AA in the regulation of lateral root development, which is different from its better-known role in plant indole-3-acetic acid biosynthesis. In summary, this study identifies 2-AA from T. guizhouense NJAU4742, which plays versatile roles in regulating plant root development.

Signal communication during microbial modulation of root system architecture.

Every living organism on Earth depends on its interactions with other organisms. In the rhizosphere, plants and microorganisms constantly exchange signals and influence each other's behavior. Recent studies have shown that many beneficial rhizosphere microbes can produce specific signaling molecules that affect plant root architecture and therefore could have substantial effects on above-ground growth. This review examines these chemical signals and summarizes their mechanisms of action, with the aim of enhancing our understanding of plant-microbe interactions and providing references for the comprehensive development and utilization of these active components in agricultural production. In addition, we highlight future research directions and challenges, such as searching for microbial signals to induce primary root development.

Multi-omics analysis dissects the genetic architecture of seed coat content in Brassica napus.

BACKGROUND: Brassica napus is an important vegetable oil source worldwide. Seed coat content is a complex quantitative trait that negatively correlates with the seed oil content in B. napus. RESULTS: Here we provide insights into the genetic basis of natural variation of seed coat content by transcriptome-wide association studies (TWAS) and genome-wide association studies (GWAS) using 382 B. napus accessions. By population transcriptomic analysis, we identify more than 700 genes and four gene modules that are significantly associated with seed coat content. We also characterize three reliable quantitative trait loci (QTLs) controlling seed coat content by GWAS. Combining TWAS and correlation networks of seed coat content-related gene modules, we find that BnaC07.CCR-LIKE (CCRL) and BnaTT8s play key roles in the determination of the trait by modulating lignin biosynthesis. By expression GWAS analysis, we identify a regulatory hotspot on chromosome A09, which is involved in controlling seed coat content through BnaC07.CCRL and BnaTT8s. We then predict the downstream genes regulated by BnaTT8s using multi-omics datasets. We further experimentally validate that BnaCCRL and BnaTT8 positively regulate seed coat content and lignin content. BnaCCRL represents a novel identified gene involved in seed coat development. Furthermore, we also predict the key genes regulating carbon allocation between phenylpropane compounds and oil during seed development in B. napus. CONCLUSIONS: This study helps us to better understand the complex machinery of seed coat development and provides a genetic resource for genetic improvement of seed coat content in B. napus breeding.

The volatile cedrene from Trichoderma guizhouense modulates Arabidopsis root development through auxin transport and signalling.

Rhizosphere microorganisms interact with plant roots by producing chemical signals that regulate root development. However, the distinct bioactive compounds and signal transduction pathways remain to be identified. Here, we showed that sesquiterpenes are the main volatile compounds produced by plant-beneficial Trichoderma guizhouense NJAU4742. Inhibition of sesquiterpene biosynthesis eliminated the promoting effect of this strain on root growth, indicating its involvement in plant-fungus cross-kingdom signalling. Sesquiterpene component analysis identified cedrene, a highly abundant sesquiterpene in strain NJAU4742, to stimulate plant growth and root development. Genetic analysis and auxin transport inhibition showed that the TIR1 and AFB2 auxin receptors, IAA14 auxin-responsive protein, and ARF7 and ARF19 transcription factors affected the response of lateral roots to cedrene. Moreover, the AUX1 auxin influx carrier and PIN2 efflux carrier were also found to be indispensable for cedrene-induced lateral root formation. Confocal imaging showed that cedrene affected the expression of pPIN2:PIN2:GFP and pPIN3:PIN3:GFP, which might be related to the effect of cedrene on root morphology. These results suggested that a novel sesquiterpene molecule from plant-beneficial T. guizhouense regulates plant root development through the transport and signalling of auxin.

Population Genetic Polymorphism of Skeletal Muscle Strength Related Genes in Five Ethnic Minorities in North China.

Musculoskeletal performance is a complex trait influenced by environmental and genetic factors, and it has different manifestations in different populations. Heilongjiang province, located in northern China, is a multi-ethnic region with human cultures dating back to the Paleolithic Age. The Daur, Hezhen, Ewenki, Mongolian and Manchu ethnic groups in Heilongjiang province may have strong physical fitness to a certain extent. Based on the genetic characteristics of significant correlation between some important genes and skeletal muscle function, this study selected 23 SNPs of skeletal muscle strength-related genes and analyzed the distribution of these loci and genetic diversity in the five ethnic groups. Use Haploview (version 4.1) software to calculate the chi-square and the Hardy-Weinberg equilibrium to assess the difference between the two ethnic groups. Use R (version 4.0.2) software to perform principal component analysis of different ethnic groups. Use MEGA (version 7.0) software to construct the phylogenetic tree of different ethnic groups. Use POPGENE (version 1.32) software to calculate the heterozygosity and the FST values of 23 SNPs. Use Arlequin (version 3.5.2.2) software to analyze molecular variance (AMOVA) among 31 populations. The results showed that there was haplotype diversity of VDR, angiotensin-converting enzyme, ACTN3, EPO and IGF1 genes in the five ethnic groups, and there were genetic differences in the distribution of these genes in the five ethnic groups. Among them, the average gene heterozygosity (AVE_HET) of the 23 SNPs in the five populations was 0.398. The FST values of the 23 SNPs among the five ethnic groups varied from 0.0011 to 0.0137. According to the principal component analysis, the genetic distance of Daur, Mongolian and Ewenki is relatively close. According to the phylogenetic tree, the five ethnic groups are clustered together with the Asian population. These data will enrich existing genetic information of ethnic minorities.

Volatile compounds from beneficial rhizobacteria Bacillus spp. promote periodic lateral root development in Arabidopsis.

Lateral root formation is coordinated by both endogenous and external factors. As biotic factors, plant growth-promoting rhizobacteria can affect lateral root formation, while the regulation mechanism is unclear. In this study, by applying various marker lines, we found that volatile compounds (VCs) from Bacillus amyloliquefaciens SQR9 induced higher frequency of DR5 oscillation and prebranch site formation, accelerated the development and emergence of the lateral root primordia and thus promoted lateral root development in Arabidopsis. We demonstrated a critical role of auxin on B. amyloliquefaciens VCs-induced lateral root formation via respective mutants and pharmacological experiments. Our results showed that auxin biosynthesis, polar transport and signalling pathway are involved in B. amyloliquefaciens VCs-induced lateral roots formation. We further showed that acetoin, a major component of B. amyloliquefaciens VCs, is less active in promoting root development compared to VC blends from B. amyloliquefaciens, indicating the presence of yet uncharacterized/unknown VCs might contribute to B. amyloliquefaciens effect on lateral root formation. In summary, our study revealed an auxin-dependent mechanism of B. amyloliquefaciens VCs in regulating lateral root branching in a non-contact manner, and further efforts will explore useful VCs to promote plant root development.

Antifungal, Plant Growth-Promoting, and Genomic Properties of an Endophytic Actinobacterium Streptomyces sp. NEAU-S7GS2.

Diseases caused by Sclerotinia sclerotiorum have caused severe losses of many economically important crops worldwide. Due to the long-term persistence of sclerotia in soil and the production of air-borne ascospores, synthetic fungicides play limited roles in controlling the diseases. The application of antagonistic microorganisms can effectively reduce the number of sclerotia and eventually eradicate S. sclerotiorum from soil, and therefore considerable interest has been focused on biological control. Streptomyces sp. NEAU-S7GS2 was isolated from the root of Glycine max and its rhizosphere soil. It showed significant inhibitory activity against the mycelial growth of S. sclerotiorum (99.1%) and completely inhibited sclerotia germination. Compared to the control, in the pot experiment the application of NEAU-S7GS2 not only demonstrated excellent potential to control sclerotinia stem rot of soybean with 77 and 38% decrease in disease incidence and disease index, respectively, but could promote the growth of soybean. The light microscopy and scanning electron microscopy showed that co-culture of NEAU-S7GS2 with S. sclerotiorum on potato dextrose agar could lead to contorted and fragmented mycelia of S. sclerotiorum, which was associated with the secretion of hydrolytic glucanase and cellulase and the production of active secondary metabolites by NEAU-S7GS2. The plant growth promoting activity of NEAU-S7GS2 was related to the solubilization of inorganic phosphate, and production of 1-aminocyclopropane-1-carboxylate (ACC) deaminase and indole acetic acid (IAA). To further explore the plant growth promoting and antifungal mechanisms, the complete genome of strain NEAU-S7GS2 was sequenced. Several genes associated with ammonia assimilation, phosphate solubilization and IAA synthesis, together with genes encoding ACC deaminase, glucanase and α-amylase, were identified. AntiSMASH analysis led to the identification of four gene clusters responsible for the biosynthesis of siderophores including desferrioxamine B and enterobactin. Moreover, the biosynthetic gene clusters of lydicamycins, phenazines, and a glycosylated polyol macrolide showing 88% gene similarity to PM100117/PM100118 were identified. These results suggested that strain NEAU-S7GS2 may be a potential biocontrol agent and biofertilizer used in agriculture.

Arthrobacter celericrescens sp. nov., isolated from forest soil.

A novel bacterial strain, designated NEAU-SA2T, was isolated from forest soil collected from the Zhangjiajie city, Hunan Province, PR China and characterised using a polyphasic approach. The cells were aerobic, Gram-stain-positive, non-flagellated and rod-coccus-shaped. The strain grew optimally at 28 °C, pH 7.0 and with 0 % NaCl (w/v). Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the organism should be assigned to the genus Arthrobacter and was closely related to Arthrobacter cupressi DSM 24664T (98.89 %) and Arthrobacter silvisoli CCTCC AB 2017271T (98.41 %), which was further confirmed by multilocus sequence analysis. The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and C16 : 0; MK-9(H2) was the predominant respiratory quinone. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unidentified glycolipid. The peptidoglycan type was A3α, and the cell-wall sugars were glucose and galactose. The genomic G+C content of strain NEAU-SA2T was 67.04 mol%. The average nucleotide identity values between NEAU-SA2T and A. cupressi DSM 24664T and A. silvisoli CCTCC AB 2017271T were 88.57-90.94 %. The digital DNA-DNA hybridisation values between strain NEAU-SA2T and its most closely related species were 37.00 and 41.10 %, respectively, again indicating that they belong to different taxa. Therefore, strain NEAU-SA2T represents a novel species of the genus Arthrobacter, for which the name Arthrobacter celericrescens sp. nov. is proposed. The type strain is NEAU-SA2T (=DSM 106718T=CCTCC AB 2017272T).

Characterization of Sinomonas gamaensis sp. nov., a Novel Soil Bacterium with Antifungal Activity against Exserohilum turcicum.

A novel Gram staining positive, aerobic bacterium NEAU-HV1T that exhibits antifungal activity against Exserohilum turcicum was isolated from a soil collected from Gama, Hadjer lamis, Chad. It was grown at 10-45 °C (optimum 30 °C), pH 5-10 (optimum pH 8), and 0-4% (w/v) NaCl (optimum 1%). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain NEAU-HV1T was closely related to Sinomonas susongensis A31T (99.24% sequence similarity), Sinomonas humi MUSC 117T (98.76%), and Sinomonas albida LC13T (98.68%). The average nucleotide identity values between NEAU-HV1T and its most closely related species were 79.34-85.49%. The digital DNA-DNA hybridization values between NEAU-HV1T and S. susongensis A31T, S. albida LC13T, and S. humi MUSC 117T were 23.20, 23.50, and 22.80%, respectively, again indicating that they belonged to different taxa. The genomic DNA G+C content was 67.64 mol%. The whole cell sugars contained galactose, mannose, and rhamnose. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, and four glycolipids. The respiratory quinone system comprised MK-9(H2), MK-10(H2), and MK-8(H2). The major cellular fatty acids (>5%) were anteiso-C15:0, anteiso-C17:0, C16:0, and iso-C15:0. Based on the polyphasic analysis, it is suggested that the strain NEAU-HV1T represents a novel species of the genus Sinomonas, for which the name Sinomonas gamaensis sp. nov. is proposed. The type strain is NEAU-HV1T (= DSM 104514T = CCTCC M 2017246T).

Trinickia diaoshuihuensis sp. nov., a plant growth promoting bacterium isolated from soil.

A novel Gram-stain-negative, aerobic, rod-shaped plant growth promoting bacterium, NEAU-SY24T, was isolated from soil in Diaoshuihu, Heilongjiang, China. The isolate grew at temperatures 10-40 °C (optimum, 30 °C), pH 5-8 (optimum, pH 6) and in the presence of up to 1 % (w/v) NaCl, although NaCl was not required for growth. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain NEAU-SY24T belonged to the genus Trinickia and was closely related to Trinickia dabaoshanensis NRRL B-59553T (99.16 % similarity) and Trinickia soli DSM 18235T (99.11 %). The average nucleotide identity values between NEAU-SY24T and its most closely related species were 79.30-87.09 %. The in silico DNA-DNA hybridization values between NEAU-SY24T and T. dabaoshanensis NRRL B-59553T and T. soli DSM 18235T were 29.30 and 24.00 %, respectively, again indicating they belong to different taxa. The genomic DNA G+C content was 63.3 mol%. The major cellular fatty acids were C17 : 0cyclo, C18 : 1ω7c, C16 : 0, summed feature 2 (comprising C14 : 0 3-OH and/or C16 : 1iso I) and C16 : 0 3-OH. The predominant respiratory quinone was Q-8 and the whole-cell sugars contained ribose, glucose and galactose. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine and two unidentified aminolipids. On the basis of morphological, physiological, biochemical and chemotaxonomic analysis, strain NEAU-SY24T was classified as a novel species in the genus Trinickia, for which the name Trinickiadiaoshuihuensis sp. nov. is proposed. The type strain is NEAU-SY24T (=DSM 106065T=CCTCC AA 2018003T).

Streptomyces durbertensis sp. nov., isolated from saline-alkali soil.

A novel strain of actinobacteria, designated NEAU-S1GS20T, was isolated from a saline-alkali soil collected from Heilongjiang Province, north-east China, and characterized using a polyphasic approach. Strain NEAU-S1GS20T exhibited morphological, cultural and chemotaxonomic features consistent with its classification as representing a member of the genus Streptomyces. Growth occurred at 18‒45 °C, at pH 6.0‒10.0 and in the presence of 10 % (w/v) NaCl. Whole-cell hydrolysates mainly contained glucose and ribose. The predominant menaquinones were MK-9(H4) and MK-9(H6). The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and two unidentified phospholipids. The major cellular fatty acids (>10 %) were iso-C16 : 0, iso-C17 : 0, anteiso-C17 : 0 and C16 : 0. The G+C content of the DNA was 72.8 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain NEAU-S1GS20T formed a distinct clade within the genus Streptomyces and was closely related to Streptomyces xinghaiensis CCTCC AA 208049T (98.4 % similarity), Streptomyces chumphonensis JCM 18522T (98.1 %) and Streptomyces palmae JCM 31289T (98.1 %). Multilocus sequence analysis (MLSA) using five housekeeping genes (atpD, gyrB, recA, rpoB and trpB) showed that the MLSA distance of strain NEAU-S1GS20T to the most closely related species was greater than the 0.007 threshold. A combination of DNA-DNA hybridization results and differences in certain phenotypic characteristics demonstrated that strain NEAU-S1GS20T could be distinguished from its closest phylogenetic relatives. Therefore, strain NEAU-S1GS20T represents a novel species of the genus Streptomyces, for which the name Streptomyces durbertensis sp. nov. is proposed. The type strain is NEAU-S1GS20T (=CCTCC AA 2017006T=DSM 104538T).

Arthrobacter silvisoli sp. nov., isolated from forest soil.

A novel Gram-stain-positive, strictly aerobic strain, NEAU-SA1T, which showed a rod-coccus growth life cycle, was isolated from forest soil from Zhangjiajie, Hunan Province, China. The isolate grew at 10-40 °C (optimum 28 °C), at pH 5.0-10.0 (optimum pH 7.0) and in the presence of up to 5 % (w/v) NaCl, although NaCl was not required for growth. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-SA1T belonged to the genus Arthrobacter and was closely related to Arthrobacter cupressi DSM 24664T (98.1 % similarity). Average nucleotide identity values between NEAU-SA1T and A. cupressi DSM 24664T were 88.91 and 87.41 % by ANIm and ANIb analysis, respectively. The in silico DNA-DNA hybridization value between strain NEAU-SA1T and A. cupressi DSM 24664T was 34.20 %, again indicating they belong to different taxa. The genomic DNA G+C content was 66.74 mol%. The major cellular fatty acids (>10 %) were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and two unidentified glycolipids. The predominant menaquinone was MK-9(H2). The peptidoglycan type was A3α with an interpeptide bridge comprising l-Lys and l-Ala. Glucose, ribose and galactose were the whole-cell sugars. On the basis of morphological, physiological, biochemical and chemotaxonomic analysis, strain NEAU-SA1T was classified as representing a novel species in the genus Arthrobacter, for which the name Arthrobacter silvisoli sp. nov. is proposed. The type strain is NEAU-SA1T (=DSM 106716T=CCTCC AB 2017271T).

Psychrobacillus lasiicapitis sp. nov., isolated from the head of an ant (Lasius fuliginosus).

A novel Gram-stain-positive, motile, endospore-forming, rod-shaped bacterium, designated strain NEAU-3TGS17T, was isolated from the head of an ant (Lasius fuliginosus). The isolate grew at 0-35 °C (optimum 28-30 °C), at pH 6.0-11.0 (optimum pH 7.0-8.0) and with 0-6 % (w/v) NaCl (optimum 0 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-3TGS17T belonged to the genus Psychrobacillus. Sequence similarities between strain NEAU-3TGS17T and members of the genus Psychrobacillus with validly published names (Psychrobacillus psychrotolerans DSM 11706T, Psychrobacillus insolitus DSM 5T, Psychrobacillus psychrodurans DSM 11713T and Psychrobacillus soli NBRC 110600T) were 98.4-99.1 %. DNA-DNA relatedness values between strain NEAU-3TGS17T and its closest relatives were below 70 %. The major cellular fatty acids (>5 %) were iso-C14 : 0, anteiso-C15 : 0, C16 : 0 and iso-C15 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The cell-wall peptidoglycan type was A4ß with ornithine as the diamino acid and the predominant menaquinones were MK-8 and some MK-7. The DNA G+C content was 35.8 mol%. On the basis of phenotypic data and phylogenetic inference, strain NEAU-3TGS17T was classified as representing a novel species in the genus Psychrobacillus, for which the name Psychrobacillus lasiicapitis sp. nov. is proposed. The type strain is NEAU-3TGS17T (=DSM 100484T=CGMCC 1.15308T).

Electrochemical Kinetics of Cyanometalate Complexes in Aqueous Solution at High Pressures.

For the aqueous couples Os(CN)(6)(3-/4-), Mo(CN)(8)(3-/4-), and W(CN)(8)(3-/4-), volumes of reaction DeltaV(Ag/AgCl) relative to Ag/AgCl/4.0 mol L(-)(1) KCl and volumes of activation DeltaV(el)() for the electrode reactions are reported. Values of DeltaV(Ag/AgCl) are consistent with a very small increase in the metal-carbon bond length on reduction in each case, the main component of DeltaV(Ag/AgCl) (other than that of the reference electrode) being electrostrictive solvation change. For media in which the cation is 0.5 mol L(-)(1) K(+) or (for Mo) Na(+), DeltaV(el)() is strongly positive (+9.4 +/- 0.7, +7.3 +/- 0.7, and +10.8 +/- 0.4 cm(3) mol(-)(1) for Os(CN)(6)(3-/4-), Mo(CN)(8)(3-/4-), and W(CN)(8)(3-/4-), respectively, at 25 degrees C), whereas the theoretical expectation for a mechanism involving only the cyanometalate anions is -3 +/- 1 cm(3) mol(-1). For Mo(CN)(8)(3-/4-) in Et(4)NCl, however, DeltaV(el)() is -4.2 +/- 0.2 cm(3) mol(-)(1). In all cases, DeltaV(el)() is just one-half of the corresponding parameter DeltaV(ex)() for the homogeneous (bimolecular) self-exchange reaction of the same couple, giving strong confirmation of the "fifty-percent rule" (Fu, Y.; Swaddle, T. W. J. Am. Chem. Soc. 1997, 119, 7137). These and related results are interpreted in terms of a mechanism for both electrode and homogeneous electron-transfer reactions of cyanometalates in which the counterion mediates the electron-transfer process. For alkali metal cations, partial deaquation to permit this mediation results in positive DeltaV(el)() values, whereas for tetraalkylammonium counterions, there are no aqua ligands to be removed and DeltaV(el)() is "normal".