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We develop higher loadings of isolated noble metal atoms and clusters on a metal oxide via redistribution.

Widespread drug resistance has become the key issue in global healthcare. Extensive efforts have been made to reveal not only diverse diseases experiencing drug resistance, but also the six distinct types of molecular mechanisms underlying this resistance. A database that describes a comprehensive list of diseases with drug resistance (not just cancers/infections) and all types of resistance mechanisms is now urgently needed. However, no such database has been available to date. In this study, a comprehensive database describing drug resistance information named ‘DRESIS’ was therefore developed. It was introduced to (i) systematically provide, for the first time, all existing types of molecular mechanisms underlying drug resistance, (ii) extensively cover the widest range of diseases among all existing databases and (iii) explicitly describe the clinically/experimentally verified resistance data for the largest number of drugs. Since drug resistance has become an ever-increasing clinical issue, DRESIS is expected to have great implications for future new drug discovery and clinical treatment optimization. It is now publicly accessible without any login requirement at: https://idrblab.org/dresis/

The direct amination of alcohols with ammonia is a promising route to make primary amines, but a full understanding of various parameters, especially the effect of co-adsorbed nitrogen-containing species on the catalyst surface during amination, has still been lacking. Here, we report that the presence of dissociated ammonia species on Ru nanoparticles substantially enhances its activity in catalyzing the dehydrogenation step that is kinetically-relevant to amination. Kinetic, spectroscopic, and theoretical methods are combined to highlight how ammonia affects this rate-determining step: in the dissociated form the surface NHx species interact with the alcohol reactant and lower the corresponding barrier of O H scission, thus promoting the activity on Ru. In contrast to Pd-based catalysts, the N atom in the generated R-NH2 product binds moderately strongly with Ru sites, thus inhibiting the formation of undesired secondary amine via further C N coupling. This work unveils the overlooked role of ammonia in the amination reaction over Ru-based catalysts.

Synthesis of 2-dodecanoyl furan is a crucial step in the formulation of oleo-furan sulfonates as bio-surfactants from biomass-derived furans and vegetable-oil-derived molecules. Herein, cross-ketonization of 2-furoic acid and lauric acid is proposed to produce the bio-surfactant precursor. Among the commonly reported metal oxide ketonization catalysts, the inexpensive and abundant iron oxides are demonstrated as effective and recyclable catalysts, enabling up to 77% selectivity to 2-dodecanoyl furan at 56% lauric acid conversion. Catalyst characterization by X-ray diffraction, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy indicates that Fe3O4 is the catalytically active and stable phase. 13C isotopic tracing experiments suggest that cross-ketonization on Fe3O4 proceeds via a β-keto acid intermediate.

Tandem repeats are one of the most conserved features in the eukaryote genomes. Dendrobium is the third largest genus in family Orchidaceae compromising over 1,200 species. However, the organization of repetitive sequences in Dendrobium species remains unclear. In this study, we performed the identification and characterization of the tandem repeats in D. officinale genome using graph-based clustering and Fluorescence in situ hybridization (FISH). Six major clusters including five satellite DNAs (DofSat1-5) and one 5S rDNA repeat (Dof5S) were identified as tandem repeats. The tandem organization of DofSat5 was verified by PCR amplification and southern blotting. The chromosomal locations of the repetitive DNAs in D. officinale were investigated by FISH using the tandem repeats and oligos probes. The results showed that each of the DofSat5, 5S and 45S rDNA had one pair of strong signals on D. officinale chromosomes. The distribution of repetitive DNAs along chromosomes was also investigated based on genomic in situ hybridization (GISH) among four Dendrobium species. The results suggested complex chromosomal fusion/segmentation and rearrangements during the evolution of Dendrobium species. In conclusion, the present study provides new landmarks for unequival differentiation of the Dendrobium chromosomes and facilitate the understanding the chromosome evolution in Dendrobium speceis.

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To analyze and evaluate the clinical efficacy of Chinese and Western medical techniques in the treatment of severe diabetic foot ulcers complicated with necrotizing fasciitis of the lower leg and summarize the treatment experience of such patients to identify a new method of limb salvage treatment. A total of 46 patients with severe diabetic foot ulcers and necrotizing fasciitis of the lower leg were treated with such techniques as surgical debridement, bone drilling, open joint fusion, and microskin implantation. Wounds were treated with moisture-exposed burn therapy (a regenerative medical treatment for burns, wounds, and ulcers) and moisture-exposed burn ointment (a traditional Chinese medicine); underlying diseases were also treated effectively. The wound healing time, rate of high amputation, and mortality of these patients were summarized, and the clinical efficacy of such treatments was evaluated. Of the 46 patients enrolled, 38 patients were cured, with a cure rate of 82.61%. The average wound healing time was 130 ± 74.37 days. Two patients underwent high amputations, with an amputation rate of 4.35%, and 4 deaths occurred, with a mortality rate of 8.70%. The combination of Chinese and Western medical techniques in the treatment of severe diabetic foot ulcers complicated with necrotizing fasciitis of the lower leg not only effectively saved patients’ lives and promoted wound healing but also greatly reduced the rates of high amputation and disability.

The clustered regularly interspaced short palindromic repeats (CRISPR)-based genetic screening has been demonstrated as a powerful approach for unbiased functional genomics research. Single-cell CRISPR screening (scCRISPR) techniques, which result from the combination of single-cell toolkits and CRISPR screening, allow dissecting regulatory networks in complex biological systems at unprecedented resolution. These methods allow cells to be perturbed en masse using a pooled CRISPR library, followed by high-content phenotyping. This is technically accomplished by annotating cells with sgRNA-specific barcodes or directly detectable sgRNAs. According to the integration of distinct single-cell technologies, these methods principally fall into four categories: scCRISPR with RNA-seq, scCRISPR with ATAC-seq, scCRISPR with proteome probing, and imaging-based scCRISPR. scCRISPR has deciphered genotype-phenotype relationships, genetic regulations, tumor biological issues, and neuropathological mechanisms. This review provides insight into the technical breakthrough of scCRISPR by systematically summarizing the advancements of various scCRISPR methodologies and analyzing their merits and limitations. In addition, an application-oriented approach guide is offered to meet researchers' individualized demands.

Plant

Organonitrogen chemicals, such as amines, nitriles, amides, amino acids, and N-heterocycles, are ubiquitous building blocks in chemical industry. Conventional methodologies to prepare these chemica...

Background Meiosis of newly formed allopolyploids frequently encounter perturbations induced by the merging of divergent and hybridizable genomes. However, to date, the meiotic properties of allopolyploids with dysploid parental karyotypes have not been studied in detail. The allotetraploid Cucumis ×hytivus (HHCC, 2n = 38) was obtained from interspecific hybridization between C. sativus (CC, 2n = 14) and C. hystrix (HH, 2n = 24) followed by chromosome doubling. The results of this study thus offer an excellent opportunity to explore the meiotic properties of allopolyploids with dysploid parental karyotypes. Results In this report, we describe the meiotic properties of five chromosomes (C5, C7, H1, H9 and H10) and two genomes in interspecific hybrids and C. ×hytivus (the 4th and 14th inbred family) through oligo-painting and genomic in situ hybridization (GISH). We show that 1) only two translocations carrying C5-oligo signals were detected on the chromosomes C2 and C4 of one 14th individual by the karyotyping of eight 4th and 36 14th plants based on C5- and C7-oligo painting, and possible cytological evidence was observed in meiosis of the 4th generation; 2) individual chromosome have biases for homoeologous pairing and univalent formation in F1 hybrids and allotetraploids; 3) extensive H-chromosome autosyndetic pairings (e.g., H-H, 25.5% PMCs) were observed in interspecific F1 hybrid, whereas no C-chromosome autosyndetic pairings were observed (e.g. C-C); 4) the meiotic properties of two subgenomes have significant biases in allotetraploids: H-subgenome exhibits higher univalent and chromosome lagging frequencies than C-subgenome; and 5) increased meiotic stability in the S14 generation compared with the S4 generation, including synchronous meiosis behavior, reduced incidents of univalent and chromosome lagging. Conclusions These results suggest that the meiotic behavior of two subgenomes has dramatic biases in response to interspecific hybridization and allopolyploidization, and the meiotic behavior harmony of subgenomes is a key subject of meiosis evolution in C. ×hytivus. This study helps to elucidate the meiotic properties and evolution of nascent allopolyploids with the dysploid parental karyotypes.

Development of heterogeneous catalysts for alcohol transformation into nitriles under oxidant-free conditions is a challenge. Considering the C–H activation on α-carbon of primary alcohols is the r...

Dendrobium officinale is a traditional medicinal herb with a variety of bioactive components. Alkaloid is one of the major active ingredients of Dendrobium plants, and its immune regulatory effects have been well-studied. Although a number of genes involved in the biosynthetic pathway of alkaloids have been elucidated, the regulation mechanism underlying the methyl-jasmonate (MeJA)-induced accumulation of alkaloids in D. officinale is largely unknown. In our study, a total of 4,857 DEGs, including 2,943 up- and 1,932 down-regulated genes, were identified between the control and MeJA-treated groups. Kyoto Encyclopedia of Genes and Genomes annotation showed that a number of DEGs were associated with the putative alkaloid biosynthetic pathway in D. officinale. The main group of Dendrobium alkaloids are sesquiterpene alkaloids, which are the downstream products of mevalonate (MVA) and methylerythritol 4-phosphate (MEP) pathway. Several MVA and MEP pathway genes were significantly up-regulated by the MeJA treatment, suggesting an active precursor supply for the alkaloid biosynthesis under MeJA treatment. A number of MeJA-induced P450 family genes, aminotransferase genes and methyltransferase genes were identified, providing several important candidates to further elucidate the sesquiterpene alkaloid biosynthetic pathway of D. officinale. Furthermore, a large number of MeJA-induced transcript factor encoding genes were identified, suggesting a complex genetic network affecting the sesquiterpene alkaloid metabolism in D. officinale. Our data aids to reveal the regulation mechanism underlying the MeJA-induced accumulation of sesquiterpene alkaloids in D. officinale.

Organic nitriles are significant and versatile industrial feedstocks, but their conventional synthetic protocols require hazardous starting materials and/or harsh reaction conditions posing environmental and health risks. Herein, we established a Ni-based catalytic system to convert primary alcohols to nitriles with ammonia gas as the sole nitrogen source under oxidant-free conditions at merely 190–230 °C. Based on isotope labelling experiments, in situ DRIFTS and control experiments, the reaction pathway was identified to follow a dehydrogenation–imination–dehydrogenation sequence, with α-carbon C–H bond breakage as the rate determining step. Ni is superior to all noble metal catalysts tested, due to its excellent dehydrogenation ability that is not inhibited by NH3. The support plays an auxiliary role, promoting the reaction between aldehyde and ammonia to form imine as a critical intermediate. Ni/Al2O3 catalyst prepared via a deposition–precipitation method, featuring both excellent dispersion of metallic Ni and suitable acid sites, enabled alcohol transformation into nitrile under unprecedented low temperature. Various alcohols were converted into their corresponding nitriles in high conversions and yields (both up to 99%), while the catalyst kept 90% of its original activity after 48 hours in the stability test, highlighting the wide applicability and the robustness of the catalytic system.

Background Per- and polyfluoroalkyl substances (PFAS) and polybrominated diphenyl ethers (PBDEs) are endocrine disrupting chemicals with widespread exposures across the U.S. given their abundance in consumer products. PFAS and PBDEs are associated with reproductive toxicity and adverse health outcomes, including certain cancers. PFAS and PBDEs may affect health through alternations in telomere length. In this study, we examined joint associations between prenatal exposure to PFAS, PBDEs, and maternal and newborn telomere length using mixture analyses, to characterize effects of cumulative environmental chemical exposures. Methods Study participants were enrolled in the Chemicals in Our Bodies (CIOB) study, a demographically diverse cohort of pregnant people and children in San Francisco, CA. Seven PFAS (ng/mL) and four PBDEs (ng/g lipid) were measured in second trimester maternal serum samples. Telomere length (T/S ratio) was measured in delivery cord blood of 292 newborns and 110 second trimester maternal whole blood samples. Quantile g-computation was used to assess the joint associations between groups of PFAS and PBDEs and newborn and maternal telomere length. Groups considered were: (1) all PFAS and PBDEs combined, (2) PFAS, and (3) PBDEs. Maternal and newborn telomere length were modeled as separate outcomes. Results T/S ratios in newborn cord and maternal whole blood were moderately correlated (Spearman ρ = 0.31). In mixtures analyses, a simultaneous one quartile increase in all PFAS and PBDEs was associated with a small increase in newborn (mean change per quartile increase = 0.03, 95% confidence interval [CI] = -0.03, 0.08) and maternal telomere length (mean change per quartile increase = 0.03 (95% CI = -0.03, 0.09). When restricted to maternal–fetal paired samples (N = 76), increasing all PFAS and PBDEs combined was associated with a strong, positive increase in newborn telomere length (mean change per quartile increase = 0.16, 95% CI = 0.03, 0.28). These associations were primarily driven by PFAS (mean change per quartile increase = 0.11 [95% CI = 0.01, 0.22]). No associations were observed with maternal telomere length among paired samples. Conclusions Our findings suggest that PFAS and PBDEs may be positively associated with newborn telomere length.

BackgroundSucrose is the primary form of photosynthetically produced carbohydrates transported long distance in many plant species, which significantly affects plant growth, development and physiology. Sucrose transporters (SUTs or SUCs) are a group of membrane proteins that play vital roles in mediating sucrose allocation within cells and at the whole plant level.ResultsIn this study, we investigated the relationship of SUTs in 24 representative plant species and performed a comprehensive analysis of SUT genes in three sequenced Orchidaceae species, Dendrobium officinale, Phalaenopsis equestris, and Apostasia shenzhenica. All the SUTs from 24 plants were classified into three groups and five subgroups: subgroups A, B1, B2.1, B2.2, and C, based on the evolutionary relationships. A total of 22 SUT genes were identified in Orchidaceae species, among which D. officinale had 8 genes (DenSUT01-08), P. equestris had 8 genes (PeqSUT01-08) and A. shenzhenica had 6 genes (PeqSUT01-06). For the 22 Orchidaceae SUTs, each of the subgroups A, B2.2 and C contains three genes, whereas the SUT genes were significantly expanded in the monocot-specific subgroup B2.1 which contained 12 genes. To shed light into sucrose partitioning and functions of sucrose transporters in Orchidacea species, we analysed water-soluble sugar content and performed RNA sequencing of different tissues of D. officinale, including leaves, stems, flowers and roots. The results showed that although total content of water-soluble polysaccharides was highest in the stems of D. officinale, the sucrose content was highest in flowers. Moreover, gene expression analysis showed that most of the DenSUTs were expressed in flowers, among which DenSUT01, DenSUT07 and DenSUT06 had significantly high expression levels.ConclusionsThese results indicated that stems are used as main storage sinks for photosynthetically produced sugar in D. officinale, and that the DenSUTs mainly take functions in the cellular machinery and development of floral organs. Our findings provide valuable information on sucrose partitioning and the evolution and functions of SUT genes in Orchidaceae and other species.

Background Perfluoroalkyl substances (PFAS) and polybrominated diphenyl ethers (PBDEs) are used in consumer products for their water repellent and flame retardant properties, respectively. However, there is widespread prenatal exposure and concern about their potential harm to the developing fetus. Here, we utilized data from a demographically diverse cohort of women in San Francisco, CA to examine associations between prenatal exposure to PFAS and PBDEs with gestational age and birth weight for gestational age z-scores. Methods Women included in this analysis were enrolled in the Chemicals in our Bodies (CIOB) cohort study (N = 506). PFAS and PBDEs were measured in serum obtained during the second trimester of pregnancy. Linear regression models were used to calculate crude and adjusted β coefficients for the association between PFAS and PBDE concentrations in tertiles and gestational age and birth weight z-scores. Individual PFAS and PBDE concentrations, as well as their sums, were examined in separate models. Results The highest compared to lowest tertile of BDE-47 was associated with shorter gestational age (β = − 0.49, 95% confidence interval [CI] = − 0.95, − 0.02). Additionally, exposure to BDE-47 and BDE-99 in the middle tertile was also associated with a reduction in birth weight z-scores (β = − 0.26, 95% CI = -0.48, − 0.04; β = − 0.25, 95% CI = -0.47, − 0.04, respectively) compared to those in the lowest tertile of exposure. No consistent associations were observed between increasing PFAS concentrations and gestational age or birth weight z-scores. Discussion Among a diverse group of pregnant women in the San Francisco Bay Area, we found non-linear associations between prenatal exposure to PBDEs during the second trimester of pregnancy and birth weight z-scores. However, most PFAS congeners were not associated with adverse birth outcomes. PFAS and PBDE concentrations were lower in our cohort relative to other studies. Future research should assess the effects of emerging and persistent PFAS and PBDEs on birth outcomes, as some congeners are being phased out and replaced by chemically similar structures.

Prenatal polybrominated diphenyl ether (PBDE) exposures are a public health concern due to their persistence and potential for reproductive and developmental harm. However, we have little information about the extent of fetal exposures during critical developmental periods and the variation in exposures for groups that may be more highly exposed, such as communities of color and lower socioeconomic status (SES). To characterize maternal–fetal PBDE exposures among potentially vulnerable groups, PBDE levels were examined in the largest sample of matched maternal serum, placenta, and fetal liver tissues during mid-gestation among a geographically, racially/ethnically, and socially diverse population of pregnant women from Northern California and the Central Valley (n = 180; 2014–16). Maternal–fetal PBDE levels were compared to population characteristics using censored Kendall’s tau correlation and linear regression. PBDEs were commonly detected in all biomatrices. Before lipid adjustment, wet-weight levels of all four PBDE congeners were highest in the fetal liver (p p Latina/Hispanic > Non-Hispanic White > Asian/Pacific Islander/Other; p p = 0.07) higher wet-weight levels of BDE-47 than residents living in the San Francisco Bay Area. PBDEs are widely detected and differentially distributed in maternal–fetal compartments. Non-Hispanic Black pregnant women and women from Southern Central Valley geographical populations may be more highly exposed to PBDEs. Further research is needed to identify sources that may be contributing to differential exposures and associated health risks among these vulnerable populations.

Additional file 1: Table S1. Demographic characteristics of Chemicals in Our Body (CIOB) study population stratified by delivery hospital. Table S2. Crude linear regression coefficients and 95% confidence intervals for the associations between tertiles of PFAS (ng/mL) and PBDE (ng/g lipid) concentrations in maternal serum and gestational age in weeks (N = 506). Table S3. Crude linear regression coefficients and 95% confidence intervals for the associations between tertiles of PFAS (ng/mL) and PBDE (ng/g lipid) concentrations in maternal serum and birth weight z-scores (N = 506). Table S4. Crude odds ratios and 95% confidence intervals for the associations between tertiles of PFAS (ng/mL) and PBDE (ng/g lipid) concentrations in maternal serum and preterm birth (N = 506). Table S5. Linear regression coefficients and 95% confidence intervals for the associations tertiles of wet weight PBDE (ng/mL) concentrations in maternal serum and gestational age in weeks (N = 506). Table S6. Linear regression coefficients and 95% confidence intervals for the associations tertiles of wet weight PBDE (ng/mL) concentrations in maternal serum and birth weight z-scores (N = 506). Table S7. Linear regression coefficients and 95% confidence intervals for the associations between tertiles of PFAS (ng/mL) and PBDE (ng/g lipid) concentrations in maternal serum and birth weight (grams) among full term births (N = 461). Table S8. Linear regression coefficients and 95% confidence intervals for the associations between tertiles of PFAS (ng/mL) and PBDE (ng/g lipid) concentrations in maternal serum and birth weight z-scores stratified by infant sex (N = 506). Table S9. Linear regression coefficients and 95% confidence intervals for the associations between tertiles of PFAS (ng/mL) and PBDE (ng/g lipid) concentrations in maternal serum and gestational age stratified by infant sex (N = 506).

There are little epidemiological data on the impact of persistent organic pollutants (POPs) and endocrine disruptors on mammographic density (MD), a strong predictor of breast cancer. We assessed MD in 116 non-Hispanic white post-menopausal women for whom serum concentrations of 23 commonly detected chemicals including 3 polybrominated diphenyl ethers (PBDEs), 8 per- and polyfluoroalkyl substances (PFASs), and 12 polychlorinated biphenyls (PCBs) had been measured. Linear regression analyses adjusting for potential confounders were used to examine the associations between the levels of the chemical compounds, modeled as continuous and dichotomized (above/below median) variables, and square-root-transformed MD. None of the associations were statistically significant after correcting for multiple testing. Prior to correction for multiple testing, all chemicals with un-corrected p-values < 0.05 had regression coefficients less than zero, suggesting inverse associations between increased levels and MD, if any. The smallest p-value was observed for PCB-153 (regression coefficient for above-median vs. below-median levels: −0.87, un-corrected p = 0.008). Neither parity nor body mass index modified the associations. Our results do not support an association between higher MD and serum levels of PBDEs, PCBs, or PFASs commonly detected in postmenopausal women.

We report the first systematic study of solvent effect on reductive amination of ketones with ammonia and dihydrogen (H2) over Ru/C, Rh/C, Pd/C and Pt/C catalysts. Protic (water, methanol, ethanol and isopropanol), aprotic polar (dioxane and tetrahydrofuran) and aprotic apolar (cyclohexane and toluene) solvents were investigated. Reaction kinetic model was built to reveal solvent-dependent reaction pathway and solvent-related rate constant for individual steps. Primary amine is produced via two distinct routes, i.e., hydrogenation of imine and hydrogenolysis of Schiff base adduct. These two routes co-exist in organic solvents, while the preference of which route to take heavily depends on the nature of the solvent. In contrast, the formation of imine and Schiff base are not favored in water, resulting in high selectivity towards alcohol. Methanol is identified as the best solvent for reductive amination of ketones, attributed to the highest rates for imine and Schiff base formation compared to other solvents, as well as high hydrogenation activity.

Cucumis anguria is a potential genetic resource for improving crops of the genus Cucumis, owing to its broad-spectrum resistance. However, few cytogenetic studies on C. anguria have been reported because of its small metaphase chromosomes and the scarcity of distinguished chromosomal landmarks. In this study, 14 single-copy genes from cucumber and rDNAs were used as probes for FISH to identify the individual chromosomes of C. anguria. The distinctive signal distribution patterns of the probes allowed us to distinguish each chromosome of C. anguria (A01–A12). Further, detailed chromosome characteristics were obtained through pachytene chromosome FISH. The lengths of pachytene chromosomes varied from 54.80 to 143.41 μm. The proportion of heterochromatin regions varied from 13.56% to 63.86%. Finally, the chromosomal homeologous relationship between C. anguria and cucumber (C1–C7) was analyzed. The results showed that A06 + A09, A03 + A12, A02 + A04, and A01 + A11 were homeologs of C1, C2, C3, and C6, respectively. Furthemore, chromosomes A08, A10, and A05 were homeologs of C4, C5, and C7, respectively. Chromosome identification and homeologous relationship analysis between C. anguria and cucumber lay the foundation for further research of genome structure evolution in species of Cucumis.

Significance Today, amino acids are primarily manufactured via microbial cultivation processes, which are costly, are time consuming, and require extensive separations processes. As an alternative, chemocatalytic approaches to produce amino acids from renewable feedstocks such as bio-based sugars could offer a rapid and potentially more efficient means of amino acid synthesis, but efforts to date have been limited by the development of facile chemistry and associated catalyst materials to selectively produce α-amino acids. In this work, various α-amino acids, including alanine, leucine, aspartic acid, and phenylalanine, were obtained from both biomass-derived α-hydroxyl acids and glucose. The route bridges plant-based biomass and proteinogenic α-amino acids, offering a chemical approach that is potentially superior to microbial cultivation processes., Amino acids are the building blocks for protein biosynthesis and find use in myriad industrial applications including in food for humans, in animal feed, and as precursors for bio-based plastics, among others. However, the development of efficient chemical methods to convert abundant and renewable feedstocks into amino acids has been largely unsuccessful to date. To that end, here we report a heterogeneous catalyst that directly transforms lignocellulosic biomass-derived α-hydroxyl acids into α-amino acids, including alanine, leucine, valine, aspartic acid, and phenylalanine in high yields. The reaction follows a dehydrogenation-reductive amination pathway, with dehydrogenation as the rate-determining step. Ruthenium nanoparticles supported on carbon nanotubes (Ru/CNT) exhibit exceptional efficiency compared with catalysts based on other metals, due to the unique, reversible enhancement effect of NH3 on Ru in dehydrogenation. Based on the catalytic system, a two-step chemical process was designed to convert glucose into alanine in 43% yield, comparable with the well-established microbial cultivation process, and therefore, the present strategy enables a route for the production of amino acids from renewable feedstocks. Moreover, a conceptual process design employing membrane distillation to facilitate product purification is proposed and validated. Overall, this study offers a rapid and potentially more efficient chemical method to produce amino acids from woody biomass components.

Prof. Ning Yan obtained his BS and PhD degrees from Peking University in 2004 and 2009, respectively. Thereafter, he worked as a Marie-Curie research fellow at Ecole Polytechnique Federale de Lausanne, Switzerland. He joined the National University of Singapore (NUS) as an assistant professor, established the Lab of Green Catalysis in 2012, and was promoted to the position of associate professor in 2018. Yunzhu Wang received her BE degree from NUS in 2014. She joined Prof. Yan’s group in the same year and is currently pursuing her PhD. Her research interests include nanoscale metal catalysts and their applications in producing renewable nitrogen-containing chemicals.

Allopolyploidy and homoeologous recombination are two important processes in reshaping genomes and generating evolutionary novelties. Newly formed allopolyploids usually display chromosomal perturbations as a result of pairing errors at meiosis. To understand mechanisms of stabilization of allopolyploid species derived from distant chromosome bases, we investigated mitotic stability of a synthetic Cucumis allotetraploid species in relation to meiosis chromosome behavior. The Cucumis × hytivus is an allotetraploid synthesized from interspecific hybridization between cucumber (Cucumis sativus, 2n = 14) and its wild relative Cucumis hystrix (2n = 24) followed by spontaneous chromosome doubling. In the present study, we analyzed the wild parent C. hystrix and the latest generation of C. hytivus using GISH (genomic in situ hybridization) and cross-species FISH (fluorescence in situ hybridization). The karyotype of C. hystrix was constructed with two methods using cucumber fosmid clones and repetitive sequences. Using repeat-element probe mix in two successive hybridizations allowed for routine identification of all 19 homoeologous chromosomes of allotetraploid C. hytivus. No aneuploids were identified in any C. hytivus individuals that were characterized, and no large-scale chromosomal rearrangements were identified in this synthetic allotetraploid. Meiotic irregularities, such as homoeologous pairing, were frequently observed, resulting in univalent and intergenomic multivalent formation. The relatively stable chromosome structure of the synthetic Cucumis allotetraploid may be explained by more deleterious chromosomal viable gametes compared with other allopolyploids. The knowledge of genetic and genomic information of Cucumis allotetraploid species could provide novel insights into the establishment of allopolyploids with different chromosome bases.

In response to health concerns and widespread human exposures, two widely used commercial formulations of polybrominated diphenyl ethers (PBDEs) were banned in the United States in 2005. Initial biomonitoring data have provided early indications of reduced human exposures since these bans took effect. Our objective was to evaluate temporal trends in PBDE serum levels among a population of older California women during a four-year period, beginning approximately five years after these formulations were banned. Automated solid phase extraction and gas chromatography/high resolution mass spectrometry were used to measure PBDE levels in blood collected during 2011–2015 among 1253 women (ages 40–94) participating in the California Teachers Study. Only congeners with detection frequencies (DF) ≥ 75% were included in the present analysis: BDE-47 (DF = 88%); BDE-100 (DF = 78%); and BDE-153 (DF = 80%). Results from age- and race/ethnicity-adjusted linear regression analyses indicated modest, but statistically significant, average annual percent increases in the serum concentrations of all three PBDEs over the four-year study period. While not without limitations, these results, in the context of other biomonitoring data, suggest that earlier reported declines in PBDE levels may have plateaued and may now be starting to increase. Further biomonitoring to ascertain current trends and determinants of population exposures is warranted.

Additional file :1 Figure S1. Comparison of pollen viability of four generations of C. Ă hytivus allotetraploid (S4, S8, S11 and S14). Figure S2. Locations and density of 27,392 oligos along the sequence map of cucumber chromosomes 5 (a) and 7 (b). Figure S3. Two translocations carrying C5-oligo signals were detected in other PMCs from the same individual as Fig. 5. Figure S4. Tracing chromosome pairing at meiotic pachytene of S4 generation. Figure S5. Three representative PMCs with multivalents and one lagged C-bivalent at metaphase I in S4 generation. Figure S6. A heatmap depicting the frequency of different lagged bivalent numbers in the asynchronous meiotic PMCs of the S4 and S14 generation.

As consumer products treated with polybrominated diphenyl ethers (PBDEs) reach the end of their life cycle, they often are discarded into solid-waste facilities, offering a potential reservoir for exposure. The likelihood of exposures to PBDEs by residents living near those sites rarely has been explored. This study collected blood samples from 923 female participants in the California Teachers Study in 2011-2013 and examined the association between participants' residential proximity to solid-waste facilities with potential release of PBDEs and serum levels of three congeners (BDE-47, BDE-100, and BDE-153). General linear regression analysis was used to examine the association, adjusting for age, race, body-mass index, neighborhood socioeconomic status, and urban residency. Compared to participants living10 km from any selected site, those living within 2 km had 45% higher BDE-47 (95% CI: 5-100%) and BDE-100 (95% CI: 0-109%) levels, and those living between 2 and 10 km had 35% higher BDE-47 (95% CI: 0-82%) and 29% higher BDE-100 (95% CI: -9 to 82%) levels. No associations were found for BDE-153. Living close to some solid waste sites may be related to higher serum BDE-47 and BDE-100 levels. Studies with comprehensive exposure assessments are needed to confirm these initial observations.