Serum 5'-Nucleotidase as a Novel Predictor of Adverse Clinical Outcomes after Percutaneous Coronary Intervention in Patients with Coronary Artery Disease.

Background: The correlation between 5 ' -Nucleotidase ( 5 ' -NT) and the clinical outcomes in coronary artery disease (CAD) patients following percutaneous coronary intervention (PCI) is not clear. This study aims to clarify this relationship. Methods: The PRACTICE study enrolled 15,250 patients between December 2016 and October 2021. After filtering out those without 5 ' -NT data, a total of 6555 patients were analyzed with a median follow-up of 24 months. Based on the receiver operating characteristic (ROC) curve analysis, a 5 ' -NT level of 5.57 U/L was selected as the optimal cutoff value. All research samples were divided into high-value ( ≥ 5.57 U/L, n = 2346) and low-value groups ( < 5.57 U/L, n = 4209). Key clinical outcomes included all-cause death (ACD), cardiovascular death (CD), major adverse cardiovascular events (MACE), and major adverse cardiovascular and cerebrovascular events (MACCE). After separating patients into high and low value groups, multivariate Cox regression analysis was used to correct for potential confounding variables. Finally, risk ratios and their 95% confidence intervals (CIs) were calculated. Results: During the follow-up period, 129 instances of ACD were recorded-49 cases (1.2%) in the low-value group and 80 cases (3.4%) in the high-value group. Similarly, 102 CDs occurred, including 42 low-value group cases (1.0%) and 60 high-value group cases (2.6%). A total of 363 MACE occurred, including 198 low-value group cases (4.7%) and 165 high-value group cases (7%). A total of 397 cases of MACCE occurred, including 227 low-value group cases (5.4%) and 170 high-value group cases (7.2%). As serum 5 ' -NT increased, the incidence of ACD, CD, MACE and MACCE increased. After multivariate Cox regression, high 5 ' -NT levels were linked with a 1.63-fold increase in ACD risk (hazard ratio [HR] = 2.630, 95% CI: [1.770-3.908], p < 0.001) when compared to low 5 ' -NT patients. Similarly, the risk of CD, MACE, and MACCE increased by 1.298-fold (HR = 2.298, 95% CI: [1.477-3.573], p < 0.001), 41% (HR = 1.410, 95% CI: [1.124-1.768], p = 0.003) and 30.5% (HR = 1.305, 95% CI: [1.049-1.623], p = 0.017), respectively. Conclusions: high serum 5 ' -NT levels were independently correlated with adverse clinical outcomes in CAD patients following PCI, affirming its potential as a prognostic indicator.

Association between the C-Reactive Protein-Albumin-Lymphocyte (CALLY) Index and Adverse Clinical Outcomes in CAD Patients after PCI: Findings of a Real-World Study.

Background: The C-reactive protein-albumin-lymphocyte (CALLY) index is a novel inflammatory biomarker, and its association with the prognosis of coronary artery disease (CAD) after percutaneous coronary intervention (PCI) has not previously been studied. Therefore, this study aimed to investigate the effect of using the CALLY index on adverse outcomes in CAD patients undergoing PCI. Methods: From December 2016 to October 2021, we consecutively enrolled 15,250 CAD patients and performed follow-ups for primary endpoints consisting of all-cause mortality (ACM) and cardiac mortality (CM). The CALLY index was computed using the following formula: (albumin × lymphocyte)/(C-reactive protein (CRP) × 10 4 ). The average duration of the follow-up was 24 months. Results: A total of 3799 CAD patients who had undergone PCI were ultimately enrolled in the present study. The patients were divided into four groups according to the CALLY index quartiles: Q1 ( ≤ 0.69, n = 950), Q2 (0.69-2.44, n = 950), Q3 (2.44-9.52, n = 950), and Q4 ( > 9.52, n = 949). The low-Q1 group had a significantly higher prevalence of ACM (p < 0.001), CM (p < 0.001), major adverse cardiac events (MACEs) (p = 0.002), and major adverse cardiac and cerebrovascular events (MACCEs) (p = 0.002). Kaplan-Meier analysis revealed that a low CALLY index was significantly linked with adverse outcomes. After univariate and multivariate Cox regression analysis, the risk of ACM, CM, MACEs, and MACCEs decreased by 73.7% (adjust hazard risk [HR] = 0.263, 95% CI: 0.147-0.468, p < 0.001), 70.6% (adjust HR = 0.294, 95% CI: 0.150-0.579, p < 0. 001), 37.4% (adjust HR = 0.626, 95% CI: 0.422-0.929, p = 0.010), and 41.5% (adjust HR = 0.585, 95% CI: 0.401-0.856, p = 0.006), respectively, in the Q4 quartiles compared with the Q1 quartiles. Conclusions: This study revealed that a decreased CALLY index was associated with worse prognoses for CAD patients after PCI. The categorization of patients with a decreased CALLY index could provide valuable evidence for the risk stratification of adverse outcomes in CAD patients after PCI. Clinical Trial Registration: The details are available at http://www.chictr.org.cn (Identifier: NCT05174143).

Base excision repair system targeting DNA adducts of trioxacarcin/LL-D49194 antibiotics for self-resistance.

Two families of DNA glycosylases (YtkR2/AlkD, AlkZ/YcaQ) have been found to remove bulky and crosslinking DNA adducts produced by bacterial natural products. Whether DNA glycosylases eliminate other types of damage formed by structurally diverse antibiotics is unknown. Here, we identify four DNA glycosylases-TxnU2, TxnU4, LldU1 and LldU5-important for biosynthesis of the aromatic polyketide antibiotics trioxacarcin A (TXNA) and LL-D49194 (LLD), and show that the enzymes provide self-resistance to the producing strains by excising the intercalated guanine adducts of TXNA and LLD. These enzymes are highly specific for TXNA/LLD-DNA lesions and have no activity toward other, less stable alkylguanines as previously described for YtkR2/AlkD and AlkZ/YcaQ. Similarly, TXNA-DNA adducts are not excised by other alkylpurine DNA glycosylases. TxnU4 and LldU1 possess unique active site motifs that provide an explanation for their tight substrate specificity. Moreover, we show that abasic (AP) sites generated from TxnU4 excision of intercalated TXNA-DNA adducts are incised by AP endonuclease less efficiently than those formed by 7mG excision. This work characterizes a distinct class of DNA glycosylase acting on intercalated DNA adducts and furthers our understanding of specific DNA repair self-resistance activities within antibiotic producers of structurally diverse, highly functionalized DNA damaging agents.

Cystatin C to Left Ventricular Ejection Fraction Ratio as a Novel Predictor of Adverse Outcomes in Patients with Coronary Artery Disease: A Prospective Cohort Study.

Background: While both cystatin C and left ventricular ejection fraction (LVEF) revealed established prognostic efficacy in coronary artery disease (CAD), the relationship between cystatin C/left ventricular ejection fraction ratio (CLR) and adverse clinical outcomes among patients with CAD following percutaneous coronary intervention (PCI) remains obscure, to date. Therefore, we sought to assess the predictive efficacy of CLR among CAD patients who underwent PCI in current study. Methods: A total of 14,733 participants, including 8622 patients with acute coronary syndrome (ACS) and 6111 patients with stable coronary artery disease (SCAD), were enrolled from a prospective cohort of 15,250 CAD patients who underwent PCI and were admitted to the First Affiliated Hospital of Xinjiang Medical University from 2016 to 2021. The primary outcome of this study was mortality, including all-cause mortality (ACM) and cardiac mortality (CM). The secondary outcomes were major adverse cardiovascular events (MACEs), major adverse cardiac and cerebrovascular events (MACCEs) and nonfatal myocardial infarction (NFMI). For CLR, the optimal cut-off value was determined by utilizing receiver operating characteristic curve analysis (ROC). Subsequently, patients were assigned into two groups: a high-CLR group (CLR ≥ 0.019, n = 3877) and a low-CLR group (CLR < 0.019, n = 10,856), based on optimal cut-off value of 0.019. Lastly, the incidence of outcomes between the two groups was compared. Results: The high-CLR group had a higher incidence of ACM (8.8% vs. 0.9%), CM (6.7% vs. 0.6%), MACEs (12.7% vs. 5.9%), MACCEs (13.3% vs. 6.7%), and NFMIs (3.3% vs. 0.9%). After adjusting for confounders, multivariate Cox regression analyses revealed that patients with high-CLR had an 8.163-fold increased risk of ACM (HR = 10.643, 95% CI: 5.525~20.501, p < 0.001), a 10.643-fold increased risk of CM (HR = 10.643, 95% CI: 5.525~20.501, p < 0.001), a 2.352-fold increased risk of MACE (HR = 2.352, 95% CI: 1.754~3.154, p < 0.001), a 2.137-fold increased risk of MACCEs (HR = 2.137, 95% CI: 1.611~2.834, p < 0.001), and a 1.580-fold increased risk of NFMI (HR = 1.580, 95% CI: 1.273~1.960, p < 0.001) compared to patients with low-CLR. Conclusions: The current study indicated that a high CLR is a novel and powerful predictor of adverse long-term outcomes in CAD patients who underwent PCI, and that, it is a better predictor for patients wtih SCAD and ACS. Clinical Trial Registration: NCT05174143, http://Clinicaltrials.gov.

Serum Globulin to Albumin Ratio as a Novel Predictor of Adverse Clinical Outcomes in Coronary Artery Disease Patients Who Underwent PCI.

Background: Coronary heart disease is one of the main causes of Mortality. Many biological indicators have been used to predict the prognosis of patients with coronary heart disease. The ratio of serum globulin to albumin (GAR) has been used to predict the prognosis of patients with various cancers. It has been proven that GAR is related to the prognosis of patients with stroke. However, GAR's role in cardiovascular disease remains unclear. Our purpose was to investigate the predictive value of GAR on clinical outcomes in post-percutaneous coronary intervention (PCI) patients with coronary artery disease (CAD). Methods: From Dec. 2016 to Oct. 2021, a total of 14,994 patients undergoing PCI patients admitted to the First Affiliated Hospital of Xinjiang Medical University were divided into high GAR group (GAR ≥ 0.76, n = 4087) and low GAR group (GAR < 0.76, n = 10,907). The incidence of adverse outcomes including all-cause mortality (ACM), cardiovascular mortality (CM), major adverse cardiovascular events (MACE) and major adverse cardiovascular and cerebrovascular events (MACCE) was compared between the two groups. Multivariate Cox regression was used to adjust for the effects of confounding factors, while hazard ratios (HRs) and 95% confidence intervals (95% CI) were calculated. Median follow-up time was 24 months. Results: Compared with the low GAR group, the high GAR group had significantly higher incidence of ACM (6.5% vs. 1.7%, p < 0.001); CM (4.9% vs. 1.2%, p < 0.001), MACE (10.5% vs. 6.7%, p < 0.001), and MACCE (11.3% vs. 7.5%, p < 0.001). Cox regression analysis showed the patients in the high GAR group had a 1.62-fold increased risk for ACM (HR = 2.622, 95% CI: 2.130-3.228, p < 0.01), a 1.782-fold increased risk for CM (HR = 2.782, 95% CI: 2.180-3.550, p < 0.01). There was a 37.2% increased risk for MACE (HR = 1.372, 95% CI: 1.204-1.564, p < 0.01), and 32.4% increased risk for MACCE (HR = 1.324, 95% CI: 1.169-1.500, p < 0.01), compared to the patients in the low GAR group. Conclusions: The present study suggested that post-PCI CAD patients with higher GAR presented significantly increased mortality and adverse events GAR level at admission may 296 be considered as part of risk stratification when PCI is possible in patients with coronary heart disease. Clinical Trial Registration: The detailed information of the PRACTICE study has been registered on http://Clinicaltrials.gov (Identifier: NCT05174143).

Mutated CYP17A1 promotes atherosclerosis and early-onset coronary artery disease.

BACKGROUND: Coronary artery disease (CAD) is a multi-factor complex trait and is heritable, especially in early-onset families. However, the genetic factors affecting the susceptibility of early-onset CAD are not fully characterized. METHODS: In the present study, we identified a rare nonsense variant in the CYP17A1 gene from a Chinese Han family with CAD. To validate the effect of this variation on atherosclerosis and early-onset coronary artery disease, we conducted studies on population, cells, and mice. RESULTS: The mutation precisely congregated with the clinical syndrome in all the affected family members and was absent in unaffected family members and unrelated controls. Similar to the human phenotype, the CYP17A1-deficient mice present the phenotype of metabolic syndrome with hypertension, increased serum glucose concentration, and presentation of central obesity and fatty liver. Furthermore, CYP17A1 knockout mice or CYP17A1 + ApoE double knockout mice developed more atherosclerotic lesions than wild type (WT) with high fat diary. In cell models, CYP17A1 was found to be involved in glucose metabolism by increasing glucose intake and utilization, through activating IGF1/mTOR/HIF1-α signaling way, which was consistent in CYP17A1 knockout mice with impaired glucose tolerance and insulin resistance. CONCLUSIONS: Through our study of cells, mice and humans, we identified CYP17A1 as a key protein participating in the pathophysiology of the atherosclerotic process and the possible mechanism of CYP17A1 C987X mutation induced atherosclerosis and early-onset CAD involving glucose homeostasis regulation was revealed. Video Abstract.

Age and outcomes following personalized antiplatelet therapy in chronic coronary syndrome patients: a post hoc analysis of the randomized PATH-PCI trial.

It is particularly important to establish more effective and safer antiplatelet treatment strategies according to age. The present subanalysis of the PATH-PCI trial was to determine the safety and efficacy of any dual-antiplatelet therapy (DAPT) strategy in different age groups. We randomized 2285 chronic coronary syndrome (CCS) patients undergoing percutaneous coronary intervention (PCI) into a standard group or a personalized group from December 2016 to February 2018. The personalized group received personalized antiplatelet therapy (PAT) based on a novel platelet function test (PFT). The standard group received standard antiplatelet therapy (SAT). Then, all patients were divided according to age (under the age of 65 years and aged 65 years or over) to investigate the association and interaction of age on clinical outcomes at 180 days. In the patients under the age of 65 years, the incidence of NACEs was decreased in the personalized group compared to the standard group (5.1% vs. 8.8%, HR: 0.603, 95% CI: 0.409-0.888, P = .010). The rates of MACCEs (3.3% vs. 7.7%, HR: 0.450, 95% CI: 0.285-0.712, P = .001), MACEs (2.2% vs. 5.4%, HR: 0.423, 95% CI: 0.243-0.738, P = .002) also decreased. We did not find a significant difference in bleeding between the groups. In the patients aged 65 years or over, no difference in the primary endpoint was found (4.9% vs. 4.2%, P = .702), and comparable rates of survival were observed with the two strategies (all Ps > 0.05). The present study shows that PAT according to PFT was comparable to SAT at the 180-day follow-up for both ischemic and bleeding endpoints in CCS patients aged 65 years or over who underwent PCI. In patients under the age of 65 years, PAT can reduce ischemic events but does not increase bleeding, and it is an effective and safe treatment strategy. It may be necessary for young CCS patients after PCI to undergo PAT early after PCI.

What is the context? The PATH-PCI trial reported that personalized antiplatelet therapy (PAT) based on a novel platelet function test (PFT) can greatly reduce the incidence of ischemic events.Antiplatelet strategies may have very different effects on clinical outcomes in patients in China who are undergoing PCI at different ages.What is new? PL-12 is a new point-of-care platelet function analyzer that is used to test the platelet maximum aggregation rate (MAR).We explored the efficacy and safety of different antiplatelet strategies in chronic coronary syndrome (CCS) patients in different age groups.What is the impact? PAT according to PFT was comparable to standard antiplatelet therapy (SAT) at the 180-day follow-up for both ischemic and bleeding endpoints in CCS patients aged 65 years or over who underwent PCI.In patients under the age of 65 years, PAT can reduce ischemic events but not increase bleeding.PAT may be an effective and safe treatment strategy in CCS patients under the age of 65 years who underwent PCI.Abbreviation: PCI: percutaneous coronary intervention; CCS: chronic coronary syndrome; DAPT: dual antiplatelet therapy; PAT: personalized antiplatelet therapy; SAT: standard antiplatelet therapy; PFT: platelet function test; NACEs: net adverse clinical events; MACCEs: major adverse cardiac and cerebrovascular events; MACEs: major adverse cardiovascular events.

Biosynthesis of DNA-Alkylating Antitumor Natural Products.

DNA-alkylating natural products play an important role in drug development due to their significant antitumor activities. They usually show high affinity with DNA through different mechanisms with the aid of their unique scaffold and highly active functional groups. Therefore, the biosynthesis of these natural products has been extensively studied, especially the construction of their pharmacophores. Meanwhile, their producing strains have evolved corresponding self-resistance strategies to protect themselves. To further promote the functional characterization of their biosynthetic pathways and lay the foundation for the discovery and rational design of DNA alkylating agents, we summarize herein the progress of research into DNA-alkylating antitumor natural products, including their biosynthesis, modes of action, and auto-resistance mechanisms.

Gamma-glutamyl transferase to albumin ratio as a novel predictor of bleeding events and mortality in patients after percutaneous coronary intervention: A retrospective cohort study.

OBJECTIVES: To determine whether gamma-glutamyl transferase (GGT) to albumin ratio (GAR) independently predicts mortality and bleeding events in coronary artery disease (CAD) patients who undergo percutaneous coronary intervention (PCI). BACKGROUND: Serum GGT and albumin levels have been associated with CAD risk and mortality. However, more analysis is needed to determine their predictive relationship with adverse outcomes. METHODS: In total, 5,638 patients from a large retrospective cohort study were enrolled from January 2008 to December 2016 and divided into two groups (GAR <0.62, n = 2,712 and GAR ≥0.62, n = 2,926). The average follow-up time was 35.9 ± 22.6 months. Multivariate Cox regression analyses were performed to determine the risk of all-cause mortality and bleeding events associated with GAR. RESULTS: The low-GAR group had a significantly higher number of all-cause mortality (p = .016) and bleeding events (p = .010) than the high-GAR group. Multivariate Cox regression analyses showed that the risk of all-cause death and bleeding events decreased by 23.8% (hazard risk [HR] = 0.762 95% confidence interval [CI]: 0.601-0.966, p = .025) and 39.4% (HR = 00.616, 95% CI: 0.446-0.852, p = .003), respectively, in the high-GAR group. In patients with acute coronary syndrome, the risk of bleeding events decreased by 57.3% in the high-GAR group (HR = 0.427, 95% CI: 0.234-0.781, p = .006). In patients with stable coronary heart disease, the risk of all-cause death decreased 28.6% (HR = 0.714, 95% CI: 0.540-0.944, p = .018) in the high-GAR group. CONCLUSION: GAR was an independent and novel predictor of mortality and bleeding events in CAD patients who underwent PCI.

Baseline white blood cell count-to-apolipoprotein A1 ratio as a novel predictor of long-term adverse outcomes in patients who underwent percutaneous coronary intervention: a retrospective cohort study.

BACKGROUND: Previous studies suggested that baseline white blood cell count and apolipoprotein A1 levels were associated with clinical outcomes in patients with coronary heart disease (CAD) who underwent percutaneous coronary intervention (PCI). However, the ratio of baseline white blood cell count-to-apolipoprotein A1 level (WAR) and CAD after PCI have not been investigated. The present study investigated the effects of baseline WAR on long-term outcomes after PCI in patients with CAD. METHODS: A total of 6050 patients with CAD who underwent PCI were included in the study. Of these, 372 patients were excluded because no baseline white blood cell counts or apolipoprotein A1 (ApoA1) data was available or because of malignancies or other diseases. Finally, 5678 patients were enrolled in the present study and were divided into 3 groups according to WAR value: lower group - WAR< 5.25 (n = 1889); median group - 5.25 ≤ WAR≤7.15 (n = 1892); and higher group - WAR≥7.15 (n = 1897). The primary endpoint was long-term mortality, including all-cause mortality (ACM) and cardiac mortality (CM), after PCI. The average follow-up time was 35.9 ± 22.6 months. RESULTS: A total of 293 patients developed ACM, including 85 (4.5%) patients in the lower group, 90 (4.8%) patients in the median group, and 118 (6.2%) patients in the higher group. The risk of ACM, cardiac mortality (CM), major adverse cardiovascular and cerebrovascular events (MACCEs), and major adverse cardiovascular events (MACEs) increased 62.6% (hazard risk [HR] =1.626, 95%CI: 1.214-2.179, P = 0.001), 45.5% (HR = 1.455, 95%CI: 1.051-2.014, P = 0.024), 21.2% (HR = 1.212, 95%CI: 1.011-1.454, P = 0.038), and 23.8% (HR = 1.238, 95%CI: 1.025-1.495, P = 0.027), respectively, as determined by multivariate Cox regression analyses comparing the patients in the higher group to patients in the lower group. Patients with a WAR≥4.635 had 92.3, 81.3, 58.1 and 58.2% increased risks of ACM, CM, MACCEs and MACEs, respectively, compared to the patients with WAR< 4.635. Every 1 unit increase in WAR was associated with 3.4, 3.2, 2.0 and 2.2% increased risks of ACM, CM, MACCEs and MACEs, respectively, at the 10-year follow-up. CONCLUSION: The present study indicated that baseline WAR is a novel and an independent predictor of adverse long-term outcomes in CAD patients who underwent PCI.

Transcription-Associated Mutation Promotes RNA Complexity in Highly Expressed Genes-A Major New Source of Selectable Variation.

Alternatively spliced transcript isoforms are thought to play a critical role for functional diversity. However, the mechanism generating the enormous diversity of spliced transcript isoforms remains unknown, and its biological significance remains unclear. We analyzed transcriptomes in saker falcons, chickens, and mice to show that alternative splicing occurs more frequently, yielding more isoforms, in highly expressed genes. We focused on hemoglobin in the falcon, the most abundantly expressed genes in blood, finding that alternative splicing produces 10-fold more isoforms than expected from the number of splice junctions in the genome. These isoforms were produced mainly by alternative use of de novo splice sites generated by transcription-associated mutation (TAM), not by the RNA editing mechanism normally invoked. We found that high expression of globin genes increases mutation frequencies during transcription, especially on nontranscribed DNA strands. After DNA replication, transcribed strands inherit these somatic mutations, creating de novo splice sites, and generating multiple distinct isoforms in the cell clone. Bisulfate sequencing revealed that DNA methylation may counteract this process by suppressing TAM, suggesting DNA methylation can spatially regulate RNA complexity. RNA profiling showed that falcons living on the high Qinghai-Tibetan Plateau possess greater global gene expression levels and higher diversity of mean to high abundance isoforms (reads per kilobases per million mapped reads ≥18) than their low-altitude counterparts, and we speculate that this may enhance their oxygen transport capacity under low-oxygen environments. Thus, TAM-induced RNA diversity may be physiologically significant, providing an alternative strategy in lifestyle evolution.

Red blood cell distribution width as long-term prognostic markers in patients with coronary artery disease undergoing percutaneous coronary intervention.

BACKGROUND: The aim of this study was to assess the prognostic value of red blood cell distribution width (RDW) in patients with coronary artery disease undergoing percutaneous coronary intervention (PCI). METHODS: A retrospective cohort study (CORFCHD-PCI, [Identifier: ChiCTR-INR-16010153]) of 6050 patients who were hospitalized with a diagnosis of coronary artery disease (CAD) and treated with PCI from January 2008 to December 2016 were enrolled in the study. The primary outcome was long-term mortality after PCI. Clinical follow-up data of participating patients were obtained during an outpatient examination 35.9 ± 22.6 months after PCI. Demographic and clinical data and admission laboratory parameters were recorded, and patients were categorized into two groups according to RDW level (high group ≥13.1%; low group < 13.1%). RESULTS: Multivariate Cox regression analysis revealed RDW as an independent prognosis factor for cardiac death. The incidence of cardiac death increased 1.33 times in patients in the high RDW group (HR, 1.331; 95% CI, 1.009-1.755, P = 0.043). Kaplan-Meier survival analysis suggested that patients with high RDW tended to have an increased accumulated risk of cardiac death. However, we did not found significant differences in the incidence of long-term mortality (adjusted HR = 1.203[0.941-1.537], P = 0.140), MACCE (adjusted HR = 1.128[0.979-1.301], P = 0.096), MACE (adjusted HR = 1.155[0.994-1.341], P = 0.059), stroke, bleeding events or readmission between the two groups. CONCLUSION: The baseline level of RDW is an independent predictor for cardiac death in post-PCI CAD patients.

Three-dimensionally preserved minute larva of a great-appendage arthropod from the early Cambrian Chengjiang biota.

A three-dimensionally preserved 2-mm-long larva of the arthropod Leanchoilia illecebrosa from the 520-million-year-old early Cambrian Chengjiang biota of China represents the first evidence, to our knowledge, of such an early developmental stage in a short-great-appendage (SGA) arthropod. The larva possesses a pair of three-fingered great appendages, a hypostome, and four pairs of well-developed biramous appendages. More posteriorly, a series of rudimentary limb Anlagen revealed by X-ray microcomputed tomography shows a gradient of decreasing differentiation toward the rear. This, and postembryonic segment addition at the putative growth zone, are features of late-stage metanauplii of eucrustaceans. L. illecebrosa and other SGA arthropods, however, are considered representative of early chelicerates or part of the stem lineage of all euarthropods. The larva of an early Cambrian SGA arthropod with a small number of anterior segments and their respective appendages suggests that posthatching segment addition occurred in the ancestor of Euarthropoda.

Activation and Characterization of Cryptic Gene Cluster: Two Series of Aromatic Polyketides Biosynthesized by Divergent Pathways.

One biosynthetic gene cluster (BGC) usually governs the biosynthesis of a series of compounds exhibiting either the same or similar molecular scaffolds. Reported here is a multiplex activation strategy to awaken a cryptic BGC associated with tetracycline polyketides, resulting in the discovery of compounds having different core structures. By constitutively expressing a positive regulator gene in tandem mode, a single BGC directed the biosynthesis of eight aromatic polyketides with two types of frameworks, two pentacyclic isomers and six glycosylated tetracyclines. The proposed biosynthetic pathway, based on systematic gene inactivation and identification of intermediates, employs two sets of tailoring enzymes with a branching point from the same intermediate. These findings not only provide new insights into the role of tailoring enzymes in the diversification of polyketides, but also highlight a reliable strategy for genome mining of natural products.

Naked chancelloriids from the lower Cambrian of China show evidence for sponge-type growth.

Chancelloriids are an extinct group of spiny Cambrian animals of uncertain phylogenetic position. Despite their sponge-like body plan, their spines are unlike modern sponge spicules, but share several features with the sclerites of certain Cambrian bilaterians, notably halkieriids. However, a proposed homology of these 'coelosclerites' implies complex transitions in body plan evolution. A new species of chancelloriid, Allonnia nuda, from the lower Cambrian (Stage 3) Chengjiang Lagerstätte is distinguished by its large size and sparse spination, with modified apical sclerites surrounding an opening into the body cavity. The sclerite arrangement in A. nuda and certain other chancelloriids indicates that growth involved sclerite addition in a subapical region, thus maintaining distinct zones of body sclerites and apical sclerites. This pattern is not seen in halkieriids, but occurs in some modern calcarean sponges. With scleritome assembly consistent with a sponge affinity, and in the absence of cnidarian- or bilaterian-grade features, it is possible to interpret chancelloriids as sponges with an unusually robust outer epithelium, strict developmental control of body axis formation, distinctive spicule-like structures and, by implication, minute ostia too small to be resolved in fossils. In this light, chancelloriids may contribute to the emerging picture of high disparity among early sponges.

Enzymology of Anthraquinone-γ-Pyrone Ring Formation in Complex Aromatic Polyketide Biosynthesis.

Aromatic-fused γ-pyrones are structural features of many bioactive natural products and valid scaffolds for medicinal chemistry. However, the enzymology of their formation has not been completely established. Now it is demonstrated that TxnO9, a CalC-like protein belonging to a START family, functions as an unexpected anthraquinone-γ-pyrone synthase involved in the biosynthesis of antitumor antibiotic trioxacarcin A (TXN-A). Structural analysis by NMR identified a likely substrate/product-binding mode and putative key active sites of TxnO9, which allowed an enzymatic mechanism to be proposed. Moreover, a subset of uncharacterized homologous proteins bearing an unexamined Lys-Thr dyad exhibit the same function. Therefore, the functional assignment and mechanistic investigation of this γ-pyrone synthase elucidated an undescribed step in TXN-A biosynthesis, and the discovery of this new branch of polyketide heterocyclases expands the functions of the START superfamily.

[Sesquiterpenes from stems of Schisandra henryi var. henryi].

The dried stems of Schisandra henryi var. henryi were extracted with 95% ethanol and the extracts were further subjected to partition, affording the ethyl acetate extracts(EtOAc Extrs.).The EtOAc Extrs.were separated and purified with silica gel and octadecyl-silylated silica gel column chromatography, preparative HPLC and preparative TLC. Thirteen known compounds were obtained and identified by spectral methods including MS and NMR, all of which were elucidated as t-cadinol(1), cadinane-4ß,5α,10ß-triol(2), cadinane-5α, 10α-diol-2-ene(3), oxyphyllenodiols A(4), 1ß, 4ß-dihydroxyeudesman-11-ene(5), cyperusol C(6), (7R)-opposit-4(15)-ene-1ß,7-diol(7), dysodensiol E(8), epi-guaidiol A(9), aromadendrane-4ß,10ß-diol(10), tricyclohumuladiol(11), caryolane-1,9ß-diol(12), and guaidiol A(13). Compounds 3, 5-10, and 13 were separated from the genus for the first time, while compounds 1-13 were separated from this species for the first time.

The SARP Family Regulator Txn9 and Two-Component Response Regulator Txn11 are Key Activators for Trioxacarcin Biosynthesis in Streptomyces bottropensis.

Trioxacarcin A is a polyoxygenated, structurally complex antibiotic produced by Streptomyces spp., which possesses high anti-bacterial, anti-malaria, and anti-tumor activities. The trioxacarcin biosynthetic pathway involves type II polyketide synthases (PKSs) with L-isoleucine as a unique starter unit, as well as many complex post-PKS tailoring enzymes and resistance and regulatory proteins. In this work, two regulatory genes, txn9 coding for a Streptomyces antibiotic regulatory protein family regulator and txn11 for a two-component response regulator, were revealed to be absolutely required for trioxacarcin production by individually inactivating all the six annotated regulatory genes in the txn cluster. Complementation assay suggested that these two activators do not have a regulatory cascade relationship. Moreover, transcriptional analysis showed that they activate 15 of the 28 txn operons, indicating that a complicated regulatory network is involved in the trioxacarcin production. Information gained from this study may be useful for improving the production of the highly potent trioxacarcin A.

[Simultaneous Determination of Sn and S in Methyltin Mercaptide by Microwave-Assisted Acid Digestion and ICP-OES].

Methyltin mercaptide is widely used as one of the best heat stabilizer in the polyvinylchloride (PVC) thermal processing due to its excellent stability, good transparency, high compatibility and weather resistance. The content of sulfur and tin significantly affects its quality and performance, so it is of great significance to develop an analytical method for the simultaneous determination of sulfur and tin. Inductively coupled plasma atomic emission spectrometry (ICP-OES) has been a powerful analytical tool for a myriad of complex samples owing to its advantages of the low detection limits, rapid and precise determinations over wide dynamic ranges, freedom from chemical inter-element interferences, the high sample throughput and above all, simultaneous multi-elements analysis. Microwave technique as a well-developed method for sample preparation can dramatically reduce the digestion time and the loss of volatile elements compared with the traditional open digestion. Hereby, a microwave-assisted acid digestion (MW-AAD) procedure followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis was developed for the simultaneous determination of Sn and S in methyltin mercaptide. This method has the advantages of simplicity, rapidness, good accuracy, green and less use of samples. Parameters affecting the MW-AAD such as the digestion solution and digestion time were optimized by using a chemical analyzed reference sample (DX-181) to attain tin and sulfur quantitative recoveries. HNO3-HCl-HClO4 (v/v/v=9:3:1) and 10 min were the optimum digestion solution and digestion time, respectively. Under optimum conditions, the standard addition method and the standard calibration curve method were both been used to detect Sn and S in DX-181. There was no significant difference between two methods and the relative deviations to the chemical analysis values were both less than 2%. Additionally, the accuracy of the MW-AAD method was examined by analyzing three methyltin mercaptide samples (DX-181, DX-990, DX-960). The results were satisfactory with the relative deviations (<3%) and the recoveries of standard addition (99%~102%).

Simultaneous Determination of Se and Te in Ores by HG-AFS After Online Preconcentration with Nano-TiO2 Immobilized on Silica Gel.

A simple, sensitive and interference-free method was established for simultaneous determination of trace selenium and tellurium in ore samples by HG-AFS, by using nano-TiO2 immobilized on a silica gel packed microcolumn for online preconcentration. Selenium and tellurium were selectively adsorbed to the microcolumn in acidic condition and then completely eluted with 2% (m/v) NaOH solution. The experimental conditions for hydride generation, adsorption, elution and potential interference were investigated in detail. Under the optimum conditions, the detection limits of selenium and tellurium by the proposed method with 180 s sampling time were 4.0 and 3.6 ng · L(-1), with sensitivity enhancement of 20- and 13-fold compared to conventional hydride generation method, respectively. The relative standard deviation (RSD, n=5) of this method for 1 µg · L(-1) Se(IV) and Te(IV) were 0.7% and 2.3%, respectively. This method was applied to determination of selenium and tellurium in several ore samples.