The pig pangenome provides insights into the roles of coding structural variations in genetic diversity and adaptation.

Structural variations have emerged as an important driving force for genome evolution and phenotypic variation in various organisms, yet their contributions to genetic diversity and adaptation in domesticated animals remain largely unknown. Here we constructed a pangenome based on 250 sequenced individuals from 32 pig breeds in Eurasia and systematically characterized coding sequence presence/absence variations (PAVs) within pigs. We identified 308.3-Mb nonreference sequences and 3438 novel genes absent from the current reference genome. Gene PAV analysis showed that 16.8% of the genes in the pangene catalog undergo PAV. A number of newly identified dispensable genes showed close associations with adaptation. For instance, several novel swine leukocyte antigen (SLA) genes discovered in nonreference sequences potentially participate in immune responses to productive and respiratory syndrome virus (PRRSV) infection. We delineated previously unidentified features of the pig mobilome that contained 490,480 transposable element insertion polymorphisms (TIPs) resulting from recent mobilization of 970 TE families, and investigated their population dynamics along with influences on population differentiation and gene expression. In addition, several candidate adaptive TE insertions were detected to be co-opted into genes responsible for responses to hypoxia, skeletal development, regulation of heart contraction, and neuronal cell development, likely contributing to local adaptation of Tibetan wild boars. These findings enhance our understanding on hidden layers of the genetic diversity in pigs and provide novel insights into the role of SVs in the evolutionary adaptation of mammals.

FLOWERING LOCUS T1 and TERMINAL FLOWER1 regulatory networks mediate flowering initiation in apple.

Flower bud formation is a critical process that directly determines yield and fruit quality in fruit crops. Floral induction is modulated by the balance between 2 flowering-related proteins, FLOWERING LOCUS T (FT) and TERMINAL FLOWER1 (TFL1); however, the mechanisms underlying the establishment and maintenance of this dynamic balance remain largely elusive. Here, we showed that in apple (Malus × domestica Borkh.), MdFT1 is predominantly expressed in spur buds and exhibits an increase in expression coinciding with flower induction; in contrast, MdTFL1 exhibited downregulation in apices during flower induction, suggesting that MdTFL1 has a role in floral repression. Interestingly, both the MdFT1 and MdTFL1 transcripts are directly regulated by transcription factor basic HELIX-LOOP-HELIX48 (MdbHLH48), and overexpression of MdbHLH48 in Arabidopsis (Arabidopsis thaliana) and tomato (Solanum lycopersicum) results in accelerated flowering. Binding and activation analyses revealed that MdbHLH48 functions as a positive regulator of MdFT1 and a negative regulator of MdTFL1. Further studies established that both MdFT1 and MdTFL1 interact competitively with MdWRKY6 protein to facilitate and inhibit, respectively, MdWRKY6-mediated transcriptional activation of target gene APPLE FLORICAULA/LFY (AFL1, an apple LEAFY-like gene), ultimately regulating apple flower bud formation. These findings illustrate the fine-tuned regulation of flowering by the MdbHLH48-MdFT1/MdTFL1-MdWRKY6 module and provide insights into flower bud formation in apples.

Dissection of the Pearl of Csaba pedigree identifies key genomic segments related to early ripening in grape.

Pearl of Csaba (PC) is a valuable backbone parent for early-ripening grapevine (Vitis vinifera) breeding, from which many excellent early ripening varieties have been bred. However, the genetic basis of the stable inheritance of its early ripening trait remains largely unknown. Here, the pedigree, consisting of 40 varieties derived from PC, was re-sequenced for an average depth of ∼30×. Combined with the resequencing data of 24 other late-ripening varieties, 5,795,881 high-quality single nucleotide polymorphisms (SNPs) were identified following a strict filtering pipeline. The population genetic analysis showed that these varieties could be distinguished clearly, and the pedigree was characterized by lower nucleotide diversity and stronger linkage disequilibrium than the non-pedigree varieties. The conserved haplotypes (CHs) transmitted in the pedigree were obtained via identity-by-descent analysis. Subsequently, the key genomic segments were identified based on the combination analysis of haplotypes, selective signatures, known ripening-related quantitative trait loci (QTLs), and transcriptomic data. The results demonstrated that varieties with a superior haplotype, H1, significantly (one-way ANOVA, P < 0.001) exhibited early grapevine berry development. Further analyses indicated that H1 encompassed VIT_16s0039g00720 encoding a folate/biopterin transporter protein (VvFBT) with a missense mutation. VvFBT was specifically and highly expressed during grapevine berry development, particularly at veraison. Exogenous folate treatment advanced the veraison of "Kyoho". This work uncovered core haplotypes and genomic segments related to the early ripening trait of PC and provided an important reference for the molecular breeding of early-ripening grapevine varieties.

Rice responds to Spodoptera frugiperda infestation via epigenetic regulation of H3K9ac in the jasmonic acid signaling and phenylpropanoid biosynthesis pathways.

KEY MESSAGE: This study provided important insights into the complex epigenetic regulatory of H3K9ac-modified genes involved in the jasmonic acid signaling and phenylpropanoid biosynthesis pathways of rice in response to Spodoptera frugiperda infestation. Physiological and molecular mechanisms underlying plant responses to insect herbivores have been well studied, while epigenetic modifications such as histone acetylation and their potential regulation at the genomic level of hidden genes remain largely unknown. Histone 3 lysine 9 acetylation (H3K9ac) is an epigenetic marker widely distributed in plants that can activate gene transcription. In this study, we provided the genome-wide profiles of H3K9ac in rice (Oryza sativa) infested by fall armyworm (Spodoptera frugiperda, FAW) using CUT&Tag-seq and RNA-seq. There were 3269 and 4609 up-regulated genes identified in plants infested by FAW larvae for 3 h and 12 h, respectively, which were mainly enriched in alpha-linolenic acid and phenylpropanoid pathways according to transcriptomic analysis. In addition, CUT&Tag-seq analysis revealed increased H3K9ac in FAW-infested plants, and there were 422 and 543 up-regulated genes enriched with H3K9ac observed at 3 h and 12 h after FAW feeding, respectively. Genes with increased H3K9ac were mainly enriched in the transcription start site (TSS), suggesting that H3K9ac is related to gene transcription. Integrative analysis of both RNA-seq and CUT&Tag-seq data showed that up-expressed genes with H3K9ac enrichment were mainly involved in the jasmonic acid (JA) and phenylpropanoid pathways. Particularly, two spermidine hydroxycinnamoyl transferase genes SHT1 and SHT2 involved in phenolamide biosynthesis were highly modified by H3K9ac in FAW-infested plants. Furthermore, the Ossht1 and Ossht2 transgenic lines exhibited decreased resistance against FAW larvae. Our findings suggest that rice responds to insect herbivory via H3K9ac epigenetic regulation in the JA signaling and phenolamide biosynthesis pathways.

Genome-wide characterization of long terminal repeat retrotransposons provides insights into trait evolution of four cucurbit species.

Cucurbits are a diverse plant family that includes economically important crops, such as cucumber, watermelon, melon, and pumpkin. Knowledge of the roles that long terminal repeat retrotransposons (LTR-RTs) have played in diversification of cucurbit species is limited; to add to understanding of the roles of LTR-RTs, we assessed their distributions in four cucurbit species. We identified 381, 578, 1086, and 623 intact LTR-RTs in cucumber (Cucumis sativus L. var. sativus cv. Chinese Long), watermelon (Citrullus lanatus subsp. vulgaris cv. 97103), melon (Cucumis melo cv. DHL92), and Cucurbita (Cucurbita moschata var. Rifu), respectively. Among these LTR-RTs, the Ale clade of the Copia superfamily was the most abundant in all the four cucurbit species. Insertion time and copy number analysis revealed that an LTR-RT burst occurred approximately 2 million years ago in cucumber, watermelon, melon, and Cucurbita, and may have contributed to their genome size variation. Phylogenetic and nucleotide polymorphism analyses suggested that most LTR-RTs were formed after species diversification. Analysis of gene insertions by LTR-RTs revealed that the most frequent insertions were of Ale and Tekay and that genes related to dietary fiber synthesis were the most commonly affected by LTR-RTs in Cucurbita. These results increase our understanding of LTR-RTs and their roles in genome evolution and trait characterization in cucurbits.

Gold-Silver Alloy Nanoparticle-Incorporated Pitaya-Type Silica Nanohybrids for Sensitive Competitive Lateral Flow Immunoassay.

Although the competitive lateral flow immunoassay (CLFIA) using gold nanoparticles (AuNPs) as labels has been widely adopted for the rapid detection of small molecules, its sensitivity is often constrained by the insufficient colorimetric signal produced by conventional AuNPs labels. Herein, we introduce a new type of intensified colorimetric label, denoted as SAAS, which is engineered by integrating gold-silver alloy nanoparticles (Au-Ag NPs) within a dendritic silica scaffold. These pitaya-type silica nanohybrids combine the advantages of the amplified molar extinction coefficient of alloy units with the signal collective effect of numerous Au-Ag NPs in a singular label. The SAAS-based CLFIA strips not only achieve qualitative screening of aflatoxin B1 (AFB1) at an extraordinarily low concentration of 0.2 ng/mL by the naked eye but also enable precise AFB1 quantification through a smartphone, with a remarkable limit of detection of 0.00314 ng/mL. Moreover, by leveraging SAAS as a quencher, we have delved into transforming the conventional signal-off mode of competitive immunoassay into a signal-on configuration. This innovation led to the development of a fluorescent LFIA that augments interpretative precision and sensitivity. Our study demonstrates the substantial potential of the proposed nanohybrid labels in enhancing the sensitivity of CLFIA for detecting small molecules.

Genome-wide identification of the NAC gene family and its functional analysis in Liriodendron.

As one of the largest plant specific transcription factor families, NAC family members play an important role in plant growth, development and stress resistance. To investigate the function of NAC transcription factors during abiotic stress, as well as during somatic embryogenesis, we identified and characterized the NAC gene family in Liriodendron chinense. We found that most LcNAC members contain more than three exons, with a relatively conserved gene and motif structure, especially at the N-terminus. Interspecies collinearity analysis revealed a closer relationship between the L. chinense NACs and the P. trichocarpa NACs. We analyzed the expression of LcNAC in different tissues and under three abiotic stresses. We found that 12 genes were highly expressed during the ES3 and ES4 stages of somatic embryos, suggesting that they are involved in the development of somatic embryos. 6 LcNAC genes are highly expressed in flower organs. The expression pattern analysis of LcNACs based on transcriptome data and RT-qPCR obtained from L. chinense leaves indicated differential expression responses to drought, cold, and heat stress. Genes in the NAM subfamily expressed differently during abiotic stress, and LcNAC6/18/41/65 might be the key genes in response to abiotic stress. LcNAC6/18/41/65 were cloned and transiently transformed into Liriodendron protoplasts, where LcNAC18/65 was localized in cytoplasm and nucleus, and LcNAC6/41 was localized only in nucleus. Overall, our findings suggest a role of the NAC gene family during environmental stresses in L. chinense. This research provides a basis for further study of NAC genes in Liriodendron chinense.

Alternative Splicing Landscape of Small Brown Planthopper and Different Response of JNK2 Isoforms to Rice Stripe Virus Infection.

Alternative splicing (AS) is a frequent posttranscriptional regulatory event occurring in response to various endogenous and exogenous stimuli in most eukaryotic organisms. However, little is known about the effects of insect-transmitted viruses on AS events in insect vectors. The present study used third-generation sequencing technology and RNA sequencing (RNA-Seq) to evaluate the AS response in the small brown planthopper Laodelphax striatellus to rice stripe virus (RSV). The full-length transcriptome of L. striatellus was obtained using single-molecule real-time sequencing technology (SMRT). Posttranscriptional regulatory events, including AS, alternative polyadenylation, and fusion transcripts, were analyzed. A total of 28,175 nonredundant transcript isoforms included 24,950 transcripts assigned to 8,500 annotated genes of L. striatellus, and 5,000 of these genes (58.8%) had AS events. RNA-Seq of the gut samples of insects infected by RSV for 8 d identified 3,458 differentially expressed transcripts (DETs); 2,185 of these DETs were transcribed from 1,568 genes that had AS events, indicating that 31.4% of alternatively spliced genes responded to RSV infection of the gut. One of the c-Jun N-terminal kinase (JNK) genes, JNK2, experienced exon skipping, resulting in three transcript isoforms. These three isoforms differentially responded to RSV infection during development and in various organs. Injection of double-stranded RNAs targeting all or two isoforms indicated that three or at least two JNK2 isoforms facilitated RSV accumulation in planthoppers. These results implied that AS events could participate in the regulation of complex relationships between viruses and insect vectors. IMPORTANCE Alternative splicing (AS) is a regulatory mechanism that occurs after gene transcription. AS events can enrich protein diversity to promote the reactions of the organisms to various endogenous and exogenous stimulations. It is not known how insect vectors exploit AS events to cope with transmitted viruses. The present study used third-generation sequencing technology to obtain the profile of AS events in the small brown planthopper Laodelphax striatellus, which is an efficient vector for rice stripe virus (RSV). The results indicated that 31.4% of alternatively spliced genes responded to RSV infection in the gut of planthoppers. One of the c-Jun N-terminal kinase (JNK) genes, JNK2, produced three transcript isoforms by AS. These three isoforms showed different responses to RSV infection, and at least two isoforms facilitated viral accumulation in planthoppers. These results implied that AS events could participate in the regulation of complex relationships between viruses and insect vectors.

Identification of watermelon H3K4 and H3K27 genes and their expression profiles during watermelon fruit development.

BACKGROUND: The ClaH3K4s and ClaH3K27s gene families are subfamilies of the SET family, each with a highly conserved SET structure domain and a PHD structural domain. Both participate in histone protein methylation, which affects the chromosome structure and gene expression, and is essential for fruit growth and development. METHODS AND RESULTS: In order to demonstrate the structure and expression characteristics of ClaH3K4s and ClaH3K27s in watermelon, members of the watermelon H3K4 and H3K27 gene families were identified, and their chromosomal localization, gene structure, and protein structural domains were analyzed. The phylogeny and covariance of the gene families with other species were subsequently determined, and the expression profiles were obtained by performing RNA-Seq and qRT-PCR. The watermelon genome had five H3K4 genes with 3207-8043 bp nucleotide sequence lengths and four H3K27 genes with a 1107-5499 bp nucleotide sequence. Synteny analysis revealed the close relationship between watermelon and cucumber, with the majority of members displaying a one-to-one covariance. Approximately half of the 'Hua-Jing 13 watermelon' ClaH3K4s and ClaH3K27s genes were expressed more in the late fruit development stages, while the changes were minimal for the remaining half. H3K4-2 expression was observed to be slightly greater on day 21 compared to other periods. Moreover, ClaH3K27-1 and ClaH3K27-2 were hardly expressed throughout the developing period, and ClaH3K27-4 exhibited the highest expression. CONCLUSION: These results serve as a basis for further functional characterization of the H3K4 and H3K27 genes in the fruit development of watermelon.

Hue Recognition Competitive Fluorescent Lateral Flow Immunoassay for Aflatoxin M1 Detection with Improved Visual and Quantitative Performance.

Immunological detection of small molecules in a point-of-care (POC) format is of great significance yet remains challenging for accurate visual discrimination and quantitative analysis. Here, we report a novel hue recognition competitive fluorescent lateral flow immunoassay (HCLFIA) strip that allows both visual and quantitative detection of aflatoxin M1 (AFM1). The HCLFIA strip works on the basis of the ratiometric change of emission, arising from the overlap of fluorescence signals of two nanocomposites tagged with probe antibodies and coated antigens. A visually discernible orange-red-to-green fluorescence color change allows the naked eye semiquantitative readout of AFM1 around the threshold concentration (0.05 ng mL-1), yielding a visible detection limit of 0.02 ng mL-1. Moreover, using a custom smartphone-based device and color chart analysis, ultrasensitive quantitative detection of AFM1 can be achieved with a low limit of detection at 0.0012 ng mL-1, which is considerably better than those of the previously reported colorimetric and fluorescent strips. The accuracy performed in spiked milk samples ranged from 97.91 to 113.12% with a coefficient of variation below 7.8%, showing good consistency with the results from isotope dilution liquid chromatography-tandem mass spectrometry. Thanks to the unique hue recognition scheme, the HCLFIA strip holds great potential for POC detection of small molecules.

Insights into the complicated networks contribute to adventitious rooting in transgenic MdWOX11 apple microshoots under nitrate treatments.

Adventitious root formation is a bottleneck for the mass propagation of microshoots, and nitrate is an essential nutrient regulating adventitious roots. WOX11 is involved in adventitious rooting. But the crosstalk between nitrate and WOX11 is completely unknown. In this study, MdWOX11 transgenic apple microshoots were grown on different nitrate treatments. Low nitrate promotes adventitious rooting in overexpressed microshoots more than wild type and RNA interference microshoots. In contrast, medium nitrate significantly inhibits it in overexpressed and RNA interference microshoots compared with wild type microshoots. Stem anatomy indicated that medium nitrate delays root primordia formation compared with low nitrate. Methyl jasmonate and zeatin riboside played positive and negative roles in adventitious rooting, respectively. Transcriptomic analysis was conducted to understand the molecular mechanisms behind the phenotypes better. Hormone signalling, sugar metabolism, nitrogen metabolism, cell cycle and root development pathway-related genes were selected for their potential involvement in adventitious rooting. Results suggest that nitrogen signaling and MdWOX11 expression affect cytokinin accumulation and response to cytokinin through regulating the expression of genes related to cytokinin synthesis and transduction pathways, which ultimately affect adventitious rooting. This study provided important insights into the complicated networks involved in adventitious rooting in transgenic microshoots under nitrate treatments.

PTH2R is related to cell proliferation and migration in ovarian cancer: a multi-omics analysis of bioinformatics and experiments.

BACKGROUND: Ovarian cancer is a common gynecological disease and seriously endangers women's health. Currently, there is still a lack of effective molecular markers for the diagnosis and treatment of ovarian cancer. The present study aimed to investigate the molecular markers associated with ovarian cancer. METHODS: The molecular and gene related to ovarian cancer were extracted from GEO database and TCGA database by bioinformatics, and the related genes and functions were further analyzed. The results were verified by qPCR, WB, CCK-8 and Transwell experiments. RESULTS: Data analysis showed that PTH2R gene was highly expressed in tumors, and 51 HUB genes were obtained. Finally, experimental verification showed that PTH2R gene was highly expressed in ovarian cancer, and PTH2R gene was involved in the proliferation, invasion and metastasis of ovarian cancer cells. CONCLUSIONS: After experimental verification, we found that knocking down the expression of PTH2R can inhibit the proliferation, invasion and migration of tumor cells.PTH2R is expected to become a new molecular marker for ovarian cancer.

Stabilization of Dynamic Covalent Architectures by Multivalence.

The formation of imine bond is reversible. This feature has been taken advantage of by chemists for accomplishing high yielding self-assembly. On the other hand, it also jeopardizes the intrinsic stability of these self-assembled products. However, some recent discoveries demonstrate that some of these imine bond containing molecules could be rather stable or kinetically inert. A deep investigation indicated that such enhanced stability results from, at least partially, multivalence. Such results also inspire chemists to use imine condensation for self-assembly in water, a solvent that is considered not compatible with imine bond for a long time.

The importance of CYP2C19 genotype in tacrolimus dose optimization when concomitant with voriconazole in heart transplant recipients.

AIMS: Voriconazole remains the mainstay for the treatment of invasive fungal infections in heart transplant patients and can significantly increase tacrolimus exposure because of drug-drug interaction (DDI). However, the magnitude of this DDI is highly variable and difficult to predict. The purpose of this study was to present the characteristics of the DDI between tacrolimus and voriconazole, and further identify the various predictors of tacrolimus dose modification. METHODS: We retrospectively enrolled 69 heart transplant recipients who did not use voriconazole as the control and 68 patients received voriconazole treatment in voriconazole group. CYP3A4*1G, CYP3A5*3 and CYP2C19*2 or *3 were thereafter genotyped by Sanger sequencing. The dose of tacrolimus required to achieve the therapeutic concentrations and tacrolimus dose-corrected trough concentration (C0 /D) before and after VRC administration was evaluated. RESULTS: The DDI between tacrolimus and voriconazole displayed a large interindividual variability with more than 10-fold changes in tacrolimus dose (range 1.28-13.00) and C0 /D (range 1.43-13.75). In addition, the fold changes for the tacrolimus dose were associated with CYP2C19 genotype, which was found to be significantly lower in CYP2C19 extensive metabolizers than in CYP2C19 intermediate metabolizers or poor metabolizers (4.06 ± 1.85 vs 5.49 ± 2.47, P = .0031). However, no significant difference was found in both CYP3A4 and CYP3A5 genotypes. Moreover, CYP2C19 genotype and hematocrit acted as independent predicting factors for tacrolimus dose modification after voriconazole co-therapy. CONCLUSIONS: The findings of this study have identified the various important factors to adjust tacrolimus dosage when co-administrated with voriconazole in individual patients. CYP2C19 genotype and haematocrit should be considered when tailoring tacrolimus dose.

An orbital principle to design P2-NaxMO2 cathode materials for sodium-ion batteries.

Layered oxide materials are regarded to be the most promising high-performance cathode materials for sodium-ion batteries owing to their high working voltage and facile synthesis. Here, we study the influences of 3d transition metals on the cohesive energies, structural changes and operating voltages of P2-NaxMO2 during discharge based on first-principles calculations. Our results confirm that the performances of P2-NaxMO2 are associated with the chemical properties of the transition metals. In addition to this, we disclose that the involved orbitals of the 3d transition metal also greatly impact the electrochemical performance of the P2-NaxMO2 material during discharge according to the analysis of electronic structures. The jumps in the working voltage and volume during discharge are closely related to the occupation of the eg and t2g orbitals. Therefore, it is necessary to ensure that the discharge or charge process is carried out in one degenerate orbital to avoid jumps in the voltage and volume of the material. Our results could shed a light on the subsequent design of layered oxide cathodes with high cycle stability and a smooth voltage curve.

Triptolide: reflections on two decades of research and prospects for the future.

Covering: 2000 to 2020 Triptolide is a bioactive diterpene triepoxide isolated from Tripterygium wilfordii Hook F, a traditional Chinese medicinal plant whose extracts have been used as anti-inflammatory and immunosuppressive remedies for centuries. Although triptolide and its analogs exhibit potent bioactivities against various cancers, and inflammatory and autoimmune diseases, none of them has been approved to be used in the clinic. This review highlights advances in material sourcing, molecular mechanisms, clinical progress and new drug design strategies for triptolide over the past two decades, along with some prospects for the future course of development of triptolide.

Successful Surgical Treatment of a Giant Left Coronary Artery Aneurysm with Fistula.

Coronary artery aneurysm (CAA) is an aortic catastrophe with low prevalence. Giant CAA is even more uncommon, requiring surgical intervention. Giant CAA usually originates from the proximal segments of the right coronary and the anterior descending arteries. Here we report a rare case of giant left CAA with fistula formation treated with successful surgery.

Dynamic activity chain pattern estimation under mobility demand changes during COVID-19.

During the coronavirus disease 2019 pandemic, the activity engagement and travel behavior of city residents have been impacted by government restrictions, such as temporary city-wide lockdowns, the closure of public areas and public transport suspension. Based on multiple heterogeneous data sources, which include aggregated mobility change reports and household survey data, this paper proposes a machine learning approach for dynamic activity chain pattern estimation with improved interpretability for examining behavioral pattern adjustments. Based on historical household survey samples, we first establish a computational graph-based discrete choice model to estimate the baseline travel tour parameters before the pandemic. To further capture structural deviations of activity chain patterns from day-by-day time series, we define the activity-oriented deviation parameters within an interpretable utility-based nested logit model framework, which are further estimated through a constrained optimization problem. By incorporating the long short-term memory method as the explainable module to capture the complex periodic and trend information before and after interventions, we predict day-to-day activity chain patterns with more accuracy. The performance of our model is examined based on publicly available datasets such as the 2017 National Household Travel Survey in the United States and the Google Global Mobility Dataset throughout the epidemic period. Our model could shed more light on transportation planning, policy adaptation and management decisions during the pandemic and post-pandemic phases.

A Self-Assembled Homochiral Radical Cage with Paramagnetic Behaviors.

Condensation of an inherently C3 -symmetric polychlorotriphenylmethyl (PTM) radical trisaldehyde with tris(2-aminoethyl)amine (TREN) yields a [4+4] tetrahedral radical cage as a racemic pair of homochiral enantiomers in 75 % isolated yield. The structure was characterized by X-ray crystallography, confirming the homochirality of each cage framework. The homochirality results from intramolecular [CH⋅⋅⋅π] and hydrogen-bonding interactions within the cage framework. The four PTM radicals in a cage undergo weak through-space coupling. Magnetic measurements demonstrated that each cage bears 3.58 spins.

A Self-Assembled Cage for Wide-Scope Chiral Recognition in Water.

Herein, we report the self-assembly of an anionic homochiral octahedral cage by condensing six Ga3+ cations and four trisacylhydrazone ligands. The robust nature of the hydrazone bond renders the cage stable in water, where it can take advantage of the hydrophobic effect for host-guest recognition. In addition to the internal binding site, namely, the inner cavity, the octahedral cage possesses four "windows", each of which represents an external binding site allowing peripheral complexation. These internal and external binding sites endow the cage with the capability to bind a broad range of guests whose sizes could either be smaller than or exceed the volume of the cage's inner cavity. Upon accommodation of a chiral guest, one of the two cage enantiomers becomes more favored than the other, producing circular-dichroism (CD) signals. The CD signal intensity of the cage is observed to be proportional to the ee value of the chiral guest, allowing a quantitative determination of the latter.