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There is insufficient understanding of the spatio-temporal evolution of surface water-groundwater quality and hydraulic connection under both natural and human influences in urban river basins. To this end, this paper investigated the spatio-seasonal pattern of hydrochemical evolution and surface water-groundwater interaction in a typical urban river basin (Dahei River basin) based on isotopic and hydrochemical data of 132 water samples collected during three seasons (normal, wet and dry seasons). From the normal season to the wet season, surface water in the Dahei River basin was dominated by the impacts of evaporation and groundwater discharge processes. During this period, the precipitation and agricultural activities (canal irrigation) were frequent. Thus, groundwater was affected by irrigation infiltration of surface water and precipitation from high-altitude areas. From the wet season to the dry season, precipitation decreased and irrigation methods changed (canal irrigation â well irrigation). In this case, groundwater discharge had a stronger impact on surface water, and shallow groundwater was recharged by deep groundwater through the well irrigation. Under this hydrological pattern, the hydrochemical characteristics of surface water were mainly influenced by evaporation, human activities (agricultural irrigation and sewage treatment) and groundwater discharge. In contrast, the hydrochemical characteristics of groundwater were main influenced by water-rock interactions (dissolution of evaporites and silicates, and cation exchange) and human activities. This study contributed to a better understanding of the hydrochemical and hydrological processes in urban river basins and provided a theoretical basis for the sustainable management of water resources.
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[This retracts the article DOI: 10.1016/j.isci.2023.106216.].
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Introduction: The clinical utility of glutamine in patients undergoing colorectal cancer (CRC) surgery remains unclear. Therefore, we aimed to investigate the impact of postoperative treatment with glutamine on postoperative outcomes in patients undergoing CRC surgery. Methods: We included patients with CRC undergoing elective surgery between January 2014 and January 2021. Patients were divided into the glutamine and control groups. We retrospectively analyzed postoperative infections complications within 30 days and other outcomes using propensity score matching and performed between-group comparisons. Results: We included 1,004 patients who underwent CRC surgeries; among them, 660 received parenteral glutamine supplementation. After matching, there were 342 patients in each group. The overall incidence of postoperative complications was 14.9 and 36.8% in the glutamine and control groups, respectively, indicating that glutamine significantly reduced the incidence of postoperative complications [p < 0.001; risk ratio (RR) 0.41 [95% CI 0.30-0.54]]. Compared with the control group, the glutamine group had a significantly lower postoperative infection complications rate (10.5 vs. 28.9%; p < 0.001; RR 0.36 [95% CI 0.26-0.52]). Although there was no significant between-group difference in the time to first fluid diet (p = 0.052), the time to first defecation (p < 0.001), first exhaust (p < 0.001), and first solid diet (p < 0.001), as well as hospital stay (p < 0.001) were significantly shorter in the glutamine group than in the control group. Furthermore, glutamine supplementation significantly reduced the incidence of postoperative intestinal obstruction (p = 0.046). Moreover, glutamine supplementation alleviated the decrease in albumin (p < 0.001), total protein (p < 0.001), and prealbumin levels (p < 0.001). Conclusions: Taken together, postoperative parenteral glutamine supplementation can effectively reduce the incidence of postoperative complications, promote the recovery of intestinal function, and improve albumin levels in patients undergoing CRC surgery.
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Background: The incidence of rectal cancer is increasing each year. Robotic surgery is being used more frequently in the surgical treatment of rectal cancer; however, several problems associated with robotic surgery persist, such as docking the robot repeatedly to perform auxiliary incisions and difficulty exposing the operative field of obese patients. Herein we introduce a new technology that effectively improves the operability and convenience of robotic rectal surgery. Objectives: To simplify the surgical procedure, enhance operability, and improve healing of the surgical incision, we developed an advance incision (AI) technique for robotic-assisted laparoscopic rectal anterior resection, and compared its safety and feasibility with those of intraoperative incision. Methods: Between January 2016 and October 2021, 102 patients with rectal cancer underwent robotic-assisted laparoscopic rectal anterior resection with an AI or intraoperative incision (iOI) incisions. We compared the perioperative, incisional, and oncologic outcomes between groups. Results: No significant differences in the operating time, blood loss, time to first passage of flatus, time to first passage of stool, duration of hospitalization, and rate of overall postoperative complications were observed between groups. The mean time to perform auxiliary incisions was shorter in the AI group than in the iOI group (14.14 vs. 19.77â min; p < 0.05). The average incision length was shorter in the AI group than in the iOI group (6.12 vs. 7.29â cm; p < 0.05). Postoperative incision pain (visual analogue scale) was lower in the AI group than in the iOI group (2.5 vs. 2.9 p = 0.048). No significant differences in incision infection, incision hematoma, incision healing time, and long-term incision complications, including incision hernia and intestinal obstruction, were observed between groups. The recurrence (AI group vs. iOI group = 4.0% vs. 5.77%) and metastasis rates (AI group vs. iOI group = 6.0% vs. 5.77%) of cancer were similar between groups. Conclusion: The advance incision is a safe and effective technique for robotic-assisted laparoscopic rectal anterior resection, which simplifies the surgical procedure, enhances operability, and improves healing of the surgical incision.
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The translocation of proteins between various compartments of cells is the simplest and most direct way of an/retrograde communication. However, the mechanism of protein trafficking is far understood. In this study, we showed that the alteration of WHY2 protein abundance in various compartments of cells was dependent on a HECT-type ubiquitin E3 ligase UPL5 interacting with WHY2 in the cytoplasm, plastid, and nucleus, as well as mitochondrion to selectively ubiquitinate various Kub-sites (Kub 45 and Kub 227) of WHY2. Plastid genome stability can be maintained by the UPL5-WHY2 module, accompany by the alteration of photosystem activity and senescence-associated gene expression. In addition, the specificity of UPL5 ubiquitinating various Kub-sites of WHY2 was responded to cold or CaCl2 stress, in a dose [Ca2+]cyt-dependent manner. This demonstrates the integration of the UPL5 ubiquitination with the regulation of WHY2 distribution and retrograde communication between organelle and nuclear events of leaf senescence.
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Hypoperfusion is the main cause of anastomotic leakage (AL) following colorectal surgery. The conventional method for evaluating anastomotic perfusion is to observe color change and active bleeding of the resection margin of the intestine and the pulsation of mesenteric vessels. However, the accuracy of this method is low, which may be due to insufficient observation time. A novel surgical procedure that separates the mesentery in advance at the intended transection site can delay the observation of anastomotic perfusion, and can potentially detect more anastomotic sites with insufficient vascular supply and reduce the rate of AL. This study aimed to investigate the effects of a novel surgical procedure on AL following sigmoid colon and rectal cancer surgeries. A total of 343 patients who underwent rectal and sigmoid colon cancer surgeries were included in the study. From August 2021 to June 2022, patients with sigmoid colon or rectal cancer underwent a new surgical procedure of pre-division of the mesentery (PDM) at the intended transection site (PDM group). Patients with colorectal cancer who underwent conventional surgical procedures from August 2018 to July 2021 were categorized as the non-PDM group. Symptomatic AL (SAL) within 30 days and other outcomes were retrospectively analyzed using propensity score matching and compared between the two groups. The incidences of SAL were 1.3% and 11.3% in the PDM and non-PDM groups, respectively. PDM significantly reduced the SAL rate in sigmoid colon and rectal cancer surgeries (P = 0.009). The incidence of total postoperative complications (P < 0.05) was significantly lower in the PDM group than that in the non-PDM group. There were no significant differences between the two groups for operative time (P = 0.662), intraoperative blood loss (P = 0.651), intraoperative blood transfusion (P = 0.316), and intensive care rate (P = 1). The length of postoperative hospital stay (P = 0.010) and first exhaust (P = 0.001) and defecation time (P < 0.05) were shorter in the PDM group than in the non-PDM group. PDM can effectively prevent AL, and this procedure can be safely performed in sigmoid colon and rectal cancer surgeries.
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Optogenetic genome engineering is a powerful technology for high-resolution spatiotemporal genetic manipulation, especially for in vivo studies. It is difficult to generate stable transgenic animals carrying a tightly regulated optogenetic system, as its long-term expression induces high background activity. Here, the generation of an enhanced photoactivatable Cre recombinase (ePA-Cre) transgenic mouse strain with stringent light responsiveness and high recombination efficiency is reported. Through serial optimization, ePA-Cre is developed to generate a transgenic mouse line that exhibits 175-fold induction upon illumination. Efficient light-dependent recombination is detected in embryos and various adult tissues of ePA-Cre mice crossed with the Ai14 tdTomato reporter. Importantly, no significant background Cre activity is detected in the tested tissues except the skin. Moreover, efficient light-inducible cell ablation is achieved in ePA-Cre mice crossed with Rosa26-LSL-DTA mice. In conclusion, ePA-Cre mice offer a tightly inducible, highly efficient, and spatiotemporal-specific genome engineering tool for multiple applications.
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Ratones Transgénicos , Ratones , AnimalesRESUMEN
Overexpression is one of the classical approaches to study pleiotropic functions of genes of interest. To achieve overexpression, we often increase the transcription by introducing genes on exogenous vectors or by using the CRISPR/dCas9-based transcriptional activation system. To date, the most efficient CRISPR/dCas9-based transcriptional activator is the Synergistic Activation Mediator (SAM) system whereby three different transcriptional activation domains are directly fused to dCas9 and MS2 phage Coat Protein (MCP), respectively, and the system in Drosophila is named flySAM. Here we describe the effective and convenient transcriptional activation system, flySAM, starting from vector construction, microinjection, and transgenic fly selection to the phenotypic analysis.
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Sistemas CRISPR-Cas , Drosophila , Animales , Animales Modificados Genéticamente , Sistemas CRISPR-Cas/genética , Drosophila/genética , Drosophila/metabolismo , Factores de Transcripción/metabolismo , Activación TranscripcionalRESUMEN
The HECT-type UPL3 ligase plays critical roles in plant development and stress protection, but understanding of its regulation remains limited. Here, the multi-omics analyses of ubiquitinated proteins in <i>upl3</i> mutants were performed. A landscape of UPL3-dependent ubiquitinated proteins is constructed: Preferential ubiquitination of proteins related to carbon fixation represented the largest set of proteins with increased ubiquitination in the <i>upl3</i> plant, including most of carbohydrate metabolic enzymes, BRM, and variant histone, whereas a small set of proteins with reduced ubiquitination caused by the <i>upl3</i> mutation were linked to cysteine/methionine synthesis, as well as hexokinase 1 (HXK1) and phosphoenolpyruvate carboxylase 2 (PPC2). Notably, ubiquitin hydrolase 12 (UBP12), BRM, HXK1, and PPC2 were identified as the UPL3-interacting partners in vivo and in vitro. Characterization of <i>brm</i>, <i>upl3</i>, <i>ppc2</i>, <i>gin2</i>, and <i>ubp12</i> mutant plants and proteomic and transcriptomic analysis suggested that UPL3 fine-tunes carbohydrate metabolism, mediating cellular senescence by interacting with UBP12, BRM, HXK1, and PPC2. Our results highlight a regulatory pattern of UPL3 with UBP12 as a hub of regulator on proteolysis-independent regulation and proteolysis-dependent degradation.
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Proteínas de Arabidopsis , Arabidopsis , Adenosina Trifosfatasas/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Endopeptidasas/metabolismo , Ligasas/genética , Ligasas/metabolismo , Senescencia de la Planta , Proteómica , Proteínas Ubiquitinadas/metabolismoRESUMEN
Alternative splicing (AS) is a common post-transcriptional regulatory process in eukaryotes. AS has an irreplaceable role during plant development and in response to environmental stress as it evokes differential expression of downstream genes or splicing factors (e.g., serine/arginine-rich proteins). Numerous studies have reported that loss of AS capacity leads to defects in plant growth and development, and induction of stress-sensitive phenotypes. A role for post-translational modification (PTM) of AS components has emerged in recent years. These modifications are capable of regulating the activity, stability, localization, interaction, and folding of spliceosomal proteins in human cells and yeast, indicating that PTMs represent another layer of AS regulation. In this review, we summarize the recent reports concerning ubiquitin and ubiquitin-like modification of spliceosome components and analyze the relationship between spliceosome and the ubiquitin/26S proteasome pathway in plants. Based on the totality of the evidence presented, we further speculate on the roles of protein ubiquitination mediated AS in plant development and environmental response.
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PURPOSE: We introduced a novel colorectal anastomotic technique, double-angle anastomosis combined with the double stapling technique (DAA-DST), to simplify the anastomosis step during natural orifice specimen extraction surgery (NOSES) and compared its safety and effectiveness with purse string anastomosis combined with the double stapling technique (PSA-DST). METHODS: Between January 2018 and March 2021, 63 patients with colorectal cancer underwent NOSES with DAA-DST or PSA-DST. We compared the perioperative and oncological outcomes between the groups. RESULTS: There were no significant differences in the operation time, blood loss, time to first passage of flatus and excrement or hospital stay duration between PSA-DST and DAA-DST groups. The overall postoperative complication rates were similar (DAA-DST vs PSA-DST, 21.2% vs 26.7%, p = 0.78), including the rate of anastomotic leakage (6.1% vs 10%, p = 0.91). The rate of successful DAA-DST was higher than that of PSA-DST (100% vs 93.3%). The DAA-DST group had a lower rate of positive drain fluid culture than the PSA-DST group (18.2% vs 26.7% p = 0.61). Recurrence (3.01% vs 6.67%, p = 0.93) and metastasis rates (6.06% vs 6.67%, p = 0.98) were similar between the groups. CONCLUSION: DAA-DST is a safe and effective procedure and can simplify the procedure of NOSES.
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Anastomosis Quirúrgica , Neoplasias Colorrectales , Laparoscopía , Anastomosis Quirúrgica/métodos , Fuga Anastomótica/epidemiología , Fuga Anastomótica/etiología , Fuga Anastomótica/prevención & control , Neoplasias Colorrectales/complicaciones , Neoplasias Colorrectales/cirugía , Humanos , Laparoscopía/métodos , Cirugía Endoscópica por Orificios Naturales , Recto/cirugía , Estudios RetrospectivosRESUMEN
Catabolism of macromolecules is a major event in senescent cells, especially involving proteolysis of organelles and abnormally aggregated proteins, circulation of nutrients, and precise control of intracellular environmental balance. Proteasomes are distributed in the nucleus and cytoplasm; however, proteasomes in organelles are limited. In this study, multi-omics proteomic analyses of ubiquitinated proteins enriched by using antibody against "di-Gly-Lys" via a free labeling were used to investigate the global changes of protein levels and ubiquitination modification levels of upl5 mutant relative to wild-type plant; subcellular localization analysis of UPL5 was found to be located in the nucleus, cytoplasm, and plastid within the cell; and the direct lysine site patterns of UPL5 were screened by the H89R substitution in the tagged ubiquitinated assay. It suggests that UPL5 acting as a candidate of organelle E3 ligase either in the nucleus or cytoplasm or plastid modifies numerous targets related to nuclear transcription and plastid photosynthesis involving in Ca2+ and hormone signaling pathway in plant senescence and in response to (a)biotic stress protection.
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Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Senescencia de la Planta , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteómica , Ubiquitina/metabolismoRESUMEN
Background: For laparoscopic right hemicolectomy, the intermediate approach is commonly employed. However, this approach possesses several disadvantages. In this study, we compare priority access to the small bowel mesentery and the intermediate approach. Methods: The clinical data of 196 patients admitted to the First Hospital of Chongqing Medical University for laparoscopic right hemicolectomy from January 2019 to January 2022 were retrospectively collected and divided into the small bowel mesenteric priority access and traditional intermediate access groups. The operative time, intraoperative bleeding, number of lymph node dissection, postoperative anal venting time, toleration of solid and liquid intake, and postoperative hospital stay and complications were compared between the two different approaches. Results: In total, 81 cases of small bowel mesenteric priority access and 115 cases of intermediate approach for right hemi-colonic radical resection were compared. The operative time was 191.98 ± 46.05 and 209.48 ± 46.08â min in the small bowel mesenteric priority access and intermediate access groups, respectively; the difference was statistically significant. There were no significant differences in the intraoperative bleeding and lymph node clearance. However, the scatter plot analysis showed that severe intraoperative bleeding was relatively less frequent in the small mesenteric priority access group, compared with that in the intermediate approach group. Additionally, there were no statistically significant differences in the first exhaust and defecation times, hospital stay after operation, toleration of solid and liquid intake, and postoperative complication between the two groups. Conclusion: In laparoscopic right hemicolectomy, the small bowel mesenteric priority approach can significantly shorten the operation time compared with the intermediate approach. It can reduce intraoperative bleeding and the operation is simple and safe to perform, making it suitable for less experienced surgeons. Therefore, the small bowel mesenteric priority approach has the potential to be a suitable alternative and deserves further clinical promotion and application.
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Background: In two facilities in Chongqing, this research sought to retrospectively evaluate the effects of perineal wound infection on survival after laparoscopic abdominoperineal resection (LAPR) of rectal cancer. Methods: To obtain clinical information on patients who underwent LAPR between January 2013 and December 2021, we performed a multicenter cohort study. A total of 473 patients were enrolled: 314 in the non-infection group and 159 in the group with perineal infection. The general data, perioperative conditions, and tumor outcomes between groups were analyzed. The infection rates, recurrence rates, and survival rates of the two centers were compared. Results: The age, height, weight, body mass index (BMI), preoperative complications, preoperative treatment, and intraoperative conditions of patients in the LAPR infection group were not statistically different from those in the non-infection group. The percentage of men, typical postoperative hospital stay, length of initial postoperative therapy, and recurrence and metastasis rates were all considerably higher in the infection group than those in the non-infection group. Wound infection was an independent factor affecting tumor recurrence and metastasis after LAPR as well as an independent factor shortening patient survival time according to multivariate analysis. The incidence of wound infection, the rate of recurrence, and the rate of mortality did not vary significantly across sites. Conclusion: Wound infection after LAPR increases the mean postoperative hospital stay, prolongs the time to first postoperative treatment, and decreases the disease-free survival (DFS) and overall survival (OS). Therefore, decreasing the rate of LAPR wound infection is expected to shorten the postoperative hospital stay and prolong the patient DFS and OS. Patients with postoperative infection may require intensive adjuvant therapy.
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INTRODUCTION: ß-thalassemia is a severe hereditary hemolytic anemia. Due to the diversity of mutations spectrum, ß-thalassemia manifests a highly heterogeneous clinical severity. We noted that a previous report characterized HBB:c.313delA, at the end of exon 2, as a ß-thalassemia trait rather than dominant ß-thalassemia, the classification given to similar mutations. We further explored the impact of this functional variant on globin structure through larger pedigree analysis and in vitro studies. METHODS: Hematological analysis and molecular genotyping were conducted on the proband and his family members. We evaluated functional effects of the variant on ß-globin gene in the proband's nucleated erythrocytes and transfected HEK-293T cells. Three-dimensional construction of protein structure was carried out in silico to demonstrate amino acid changes. RESULTS: The thalassemia major proband was identified as a compound heterozygote of HBB:c.313delA and HBB:c.126_129delCTTT. Three family members with heterozygotes of HBB:c.313delA displayed microcytic hypochromic anemia. Molecular characterization demonstrated that the frameshift mutation could give rise to retro-positioning of the termination codon, resulting in an elongated ß-globin chain with an extension of 10 amino acids. Clinical phenotype and functional experiments indicated that HBB:c.313delA led to ß0 -thalassemia phenotype. CONCLUSION: We concluded that the phenotype of HBB:c.313delA was mainly related to the stability of mutant mRNA, the degradation of mutant proteins, and production of inclusion bodies according to a systematic description of clinical phenotype and a series of molecular experiments.
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Alelos , Fenotipo , Eliminación de Secuencia , Globinas beta/genética , Talasemia beta/sangre , Talasemia beta/genética , Sustitución de Aminoácidos , Índices de Eritrocitos , Eritrocitos/metabolismo , Eritrocitos/patología , Exones , Mutación del Sistema de Lectura , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Genotipo , Heterocigoto , Humanos , Cuerpos de Inclusión , Talasemia beta/diagnósticoRESUMEN
Notch signaling and epigenetic factors are known to play critical roles in regulating tissue homeostasis in most multicellular organisms, but how Notch signaling coordinates with epigenetic modulators to control differentiation remains poorly understood. Here, we identify heterochromatin protein 1c (HP1c) as an essential epigenetic regulator of gut homeostasis in Drosophila. Specifically, we observe that HP1c loss-of-function phenotypes resemble those observed after Notch signaling perturbation and that HP1c interacts genetically with components of the Notch pathway. HP1c represses the transcription of Notch target genes by directly interacting with Suppressor of Hairless (Su(H)), the key transcription factor of Notch signaling. Moreover, phenotypes caused by depletion of HP1c in Drosophila can be rescued by expressing human HP1γ, suggesting that HP1γ functions similar to HP1c in Drosophila. Taken together, our findings reveal an essential role of HP1c in normal development and gut homeostasis by suppressing Notch signaling.
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Proteínas de Drosophila , Animales , Proteínas Cromosómicas no Histona/genética , Drosophila/genética , Proteínas de Drosophila/genética , Heterocromatina , Homeostasis , Humanos , Receptores Notch/genéticaRESUMEN
The flySAM/CRISPRa system has recently emerged as a powerful tool for gain-of-function studies in Drosophila melanogaster This system includes Gal4/UAS-driven dCas9 activators and U6 promoter-controlled sgRNA. Having established dCas9 activators superior to other combinations, to further enhance the efficiency of the targeting activators we systematically optimized the parameters of the sgRNA. Interestingly, the most efficient sgRNAs were found to accumulate in the region from -150bp to -450bp upstream of the transcription start site (TSS), and the activation efficiency showed a strong positive correlation with the GC content of the sgRNA targeting sequence. In addition, the target region is dominant to the GC content, as sgRNAs targeting areas beyond -600bp from the TSS lose efficiency even when containing 75% GC. Surprisingly, when comparing the activities of sgRNAs targeting to either DNA strand, sgRNAs targeting to the non-template strand outperform those complementary to the template strand, both in cells and in vivo In summary, we define criteria for sgRNA design which will greatly facilitate the application of CRISPRa in gain-of-function studies.
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Drosophila melanogaster , Drosophila , Animales , Composición de Base , Sistemas CRISPR-Cas , Drosophila/genética , Drosophila melanogaster/genética , Regiones Promotoras Genéticas , ARN Guía de Kinetoplastida/genética , Sitio de Iniciación de la TranscripciónRESUMEN
The Transgenic RNAi Project (TRiP), a Drosophila melanogaster functional genomics platform at Harvard Medical School, was initiated in 2008 to generate and distribute a genome-scale collection of RNA interference (RNAi) fly stocks. To date, it has generated >15,000 RNAi fly stocks. As this covers most Drosophila genes, we have largely transitioned to development of new resources based on CRISPR technology. Here, we present an update on our libraries of publicly available RNAi and CRISPR fly stocks, and focus on the TRiP-CRISPR overexpression (TRiP-OE) and TRiP-CRISPR knockout (TRiP-KO) collections. TRiP-OE stocks express single guide RNAs targeting upstream of a gene transcription start site. Gene activation is triggered by coexpression of catalytically dead Cas9 fused to an activator domain, either VP64-p65-Rta or Synergistic Activation Mediator. TRiP-KO stocks express one or two single guide RNAs targeting the coding sequence of a gene or genes. Cutting is triggered by coexpression of Cas9, allowing for generation of indels in both germline and somatic tissue. To date, we have generated >5000 TRiP-OE or TRiP-KO stocks for the community. These resources provide versatile, transformative tools for gene activation, gene repression, and genome engineering.
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Animales Modificados Genéticamente/genética , Bases de Datos Genéticas , Drosophila melanogaster/genética , Animales , Sistemas CRISPR-Cas , Mutación con Ganancia de Función , Ingeniería Genética/métodos , Mutación con Pérdida de FunciónRESUMEN
Controllable chemo- and regiodivergent amination reactions of anilines and chlorins are accomplished by employing different oxidants and substrates, constructing aminated chlorin monomers and dimers with high structural diversity. Importantly, besides preferential 20-meso-position, the oxidative amination was also realized at the inactive 10-meso-position by using phenyliodine bis(trifluoroacetate) (PIFA) and gold(III)-based reagents.
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The activity of electrocatalysts exhibits a strongly dependence on their electronic structures. Specifically, for perovskite oxides, Shao-Horn and co-workers have reported a correlation between the oxygen evolution reaction activity and the eg orbital occupation of transition-metal ions, which provides guidelines for the design of highly active catalysts. Here we demonstrate a facile method to engineer the eg filling of perovskite cobaltite LaCoO3 for improving the oxygen evolution reaction activity. By reducing the particle size to â¼80 nm, the eg filling of cobalt ions is successfully increased from unity to near the optimal configuration of 1.2 expected by Shao-Horn's principle. Consequently, the activity is significantly enhanced, comparable to those of recently reported cobalt oxides with eg(â¼1.2) configurations. This enhancement is ascribed to the emergence of spin-state transition from low-spin to high-spin states for cobalt ions at the surface of the nanoparticles, leading to more active sites with increased reactivity.