Homeobox B2 promotes malignant behavior and contributes to the radioresistance of nasopharyngeal carcinoma by regulating forkhead box protein O1.

Background: Nasopharyngeal carcinoma (NPC) is an epithelial tumor of the head and neck with heterogeneous racial and geographical distributions. Homeobox B2 (HOXB2) is a tumor promoter in many cancers. However, the biological role of HOXB2 in NPC has not been elucidated. Methods: Bioinformatics analysis was performed to identify the differentially expressed genes (DEGs) between samples of patients with radiosensitive and radioresistant NPC. qRT-PCR, western blotting and immunohistochemistry were used to detect the expression levels of the corresponding mRNA and proteins. Cell viability was detected by CCK-8 assay and colony-forming capability was evaluated using colony formation assays. Further, migration and invasion abilities were examined using wound-healing and transwell chamber assays, respectively. Cellular apoptosis after irradiation was assessed using flow cytometry and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. Results: HOXB2 was identified as a potential regulator of radioresistance in NPC. Our in vitro results indicate that HOXB2 overexpression (HOXB2-OE) promoted malignant behaviors including invasion, migration, proliferation, and inhibited the irradiation-induced apoptosis of NPC cells. Consistent with these results, HOXB2 knockdown (HOXB2-sh) exhibited the opposite trends in these biological activities. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the DEGs were enriched in the FOXO signaling pathway. Mechanistically, western blotting showed that HOXB2-OE inhibited forkhead box protein O1 (FOXO1) expression in NPC cells. Thereafter, we transferred the FOXO1-OE plasmid to HOXB2-OE NPC cells and found that overexpression of FOXO1 reversed cell proliferation, migration, invasion, and radioresistance profiles promoted by HOXB2 overexpression. Conclusion: Our findings showed that HOXB2 acts as a tumor promoter in NPC, activating malignant behaviors and radioresistance of tumors via FOXO1 regulation. Moreover, the inactivation of HOXB2 or activation of FOXO1 are potential strategies to inhibit tumor progression and overcome radioresistance in NPC.

Nephrotic syndrome of minimal change disease following exposure to mercury-containing skin lightening cream: A case report and literature review.

Long-term exposure to mercury-containing skin lightening cream can cause mercury-related nephropathy, among which, membranous nephropathy (MN) and minimal change disease (MCD) are the main pathological types. In contrast to these two conditions, MCD with IgA deposition is not a common disease. In the present study, we report a 65-year-old Asian woman who developed nephrotic syndrome following long-term use of mercury-containing skin lightening cream. The urine mercury level of the patient was significantly increased, and the results of the renal biopsy indicated diagnosis of MCD with IgA deposition. Following three courses of treatment with sodium dimercaptopropane sulfonate (DMPS) alone and discontinuation of the skin cream, the symptoms of the patient were relieved without use of glucocorticoids, with proteinuria turning negative and a significant reduction in urine mercury levels. During the 6-month follow-up period, routine urinalysis remained normal. By reviewing relevant published literature, we summarized the pathological characteristics, possible mechanism of action, and treatment strategies of mercury poisoning-related MCD. The possibility of mercury poisoning should be considered for patients with nephropathy and history of use of skin lightening cosmetics. In these patients, the urine mercury levels should be measured in time so that mercury removal therapy can be implemented early.

A Formal and Visual Data-Mining Model for Complex Ship Behaviors and Patterns.

The successful emergence of real-time positioning systems in the maritime domain has favored the development of data infrastructures that provide valuable monitoring and decision-aided systems. However, there is still a need for the development of data mining approaches oriented to the detection of specific patterns such as unusual ship behaviors and collision risks. This research introduces a CSBP (complex ship behavioral pattern) mining model aiming at the detection of ship patterns. The modeling approach first integrates ship trajectories from automatic identification system (AIS) historical data, then categorizes different vessels' navigation behaviors, and introduces a visual-oriented framework to characterize and highlight such patterns. The potential of the model is illustrated by a case study applied to the Jiangsu and Zhejiang waters in China. The results show that the CSBP mining model can highlight complex ships' behavioral patterns over long periods, thus providing a valuable environment for supporting ship traffic management and preventing maritime accidents.

Risk factors of peritonitis during early peritoneal dialysis in patients with ANCA-associated systemic vasculitis
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This study investigated the risk factors of peritonitis during early peritoneal dialysis for renal failure in patients with antineutrophil cytoplasmic antibody (ANCA)-associated systemic vasculitis (AASV). This study enrolled hospitalized AASV patients with renal failure who underwent peritoneal dialysis at the Department of Nephrology of our hospital between 2008 and 2015. The primary aim of this study was to perform a retrospective analysis to characterize peritonitis during the early period (≤ 8 weeks) of dialysis, and to compare the differences in initial clinical manifestations, vasculitis activity, immunosuppressive therapies prior to the renal replacement therapy, and prognosis between patients with or without peritonitis. The secondary aim of this study was to conduct a literature review of peritoneal dialysis in patients with vasculitis. All 14 enrolled AASV patients had myeloperoxidase (MPO)-positive microscopic polyangiitis (MPA). Six patients (of whom 2 died) withdrew from peritoneal dialysis due to peritonitis caused by enteric bacteria during the early period of dialysis. Their mean Birmingham vasculitis activity score (BVAS) during the early AASV onset was 31.67 ± 3.98, with significant symptoms of gastrointestinal involvement. Also, their BVAS score, anti-MPO antibody titer, erythrocyte sedimentation rate, C-reactive protein level, serum ANCA level, and glucocorticoid dose were higher than the AASV patients without peritonitis (all p < 0.05). AASV patients with a higher level of vasculitis (BVAS score > 30) during onset as well as gastrointestinal symptoms had a higher risk for intestinal peritonitis. Therefore, peritoneal dialysis is not recommended as a first-choice renal replacement therapy for such patients.
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Critical assessment of the emission spectra of various photosystem II core complexes.

We evaluate low-temperature (low-T) emission spectra of photosystem II core complexes (PSII-cc) previously reported in the literature, which are compared with emission spectra of PSII-cc obtained in this work from spinach and for dissolved PSII crystals from Thermosynechococcus (T.) elongatus. This new spectral dataset is used to interpret data published on membrane PSII (PSII-m) fragments from spinach and Chlamydomonas reinhardtii, as well as PSII-cc from T. vulcanus and intentionally damaged PSII-cc from spinach. This study offers new insight into the assignment of emission spectra reported on PSII-cc from different organisms. Previously reported spectra are also compared with data obtained at different saturation levels of the lowest energy state(s) of spinach and T. elongatus PSII-cc via hole burning in order to provide more insight into emission from bleached and/or photodamaged complexes. We show that typical low-T emission spectra of PSII-cc (with closed RCs), in addition to the 695 nm fluorescence band assigned to the intact CP47 complex (Reppert et al. J Phys Chem B 114:11884-11898, 2010), can be contributed to by several emission bands, depending on sample quality. Possible contributions include (i) a band near 690-691 nm that is largely reversible upon temperature annealing, proving that the band originates from CP47 with a bleached low-energy state near 693 nm (Neupane et al. J Am Chem Soc 132:4214-4229, 2010; Reppert et al. J Phys Chem B 114:11884-11898, 2010); (ii) CP43 emission at 683.3 nm (not at 685 nm, i.e., the F685 band, as reported in the literature) (Dang et al. J Phys Chem B 112:9921-9933, 2008; Reppert et al. J Phys Chem B 112:9934-9947, 2008); (iii) trap emission from destabilized CP47 complexes near 691 nm (FT1) and 685 nm (FT2) (Neupane et al. J Am Chem Soc 132:4214-4229, 2010); and (iv) emission from the RC pigments near 686-687 nm. We suggest that recently reported emission of single PSII-cc complexes from T. elongatus may not represent intact complexes, while those obtained for T. elongatus presented in this work most likely represent intact PSII-cc, since they are nearly indistinguishable from emission spectra obtained for various PSII-m fragments.

Gastric schwannoma: A retrospective analysis of clinical characteristics, treatments, and outcomes.

BACKGROUND: This study aimed to investigate the clinical characteristics, treatment options, and prognosis of patients with gastric schwannoma (GS). METHODS: Patients who were pathologically diagnosed with GS between April 2011 and October 2022 were enrolled. The data of clinical characteristics, pathological features, treatment options, and clinical outcomes were collected and compared between GS patients who underwent endoscopic resection (ER) and surgical resection (SR). RESULTS: Of the 32 cases, 23 underwent SR and nine underwent ER. The median tumor size was significantly smaller in ER group than in SR group (12.0 vs. 40.0 mm, P < 0.001), while patients in SR group were older than those in ER group (54.5 ± 10.6 vs. 45.3 ± 10.9 years, P = 0.036). Moreover, tumors in ER group were more likely to exhibit an intraluminal pattern (100% vs. 26.1%, P < 0.001). Patients in ER group had significantly lower hospitalization cost (25859.2 ± 8623.9 vs. 44953.0 ± 13083.8 RMB, P = 0.011) than those in SR group. No differences were found between the two groups in terms of R0 resection rate, operative time, estimated blood loss, adverse events, and recurrence rate. All patients were followed up for 4-96 months (mean: 35 months; median: 23 months), during which no evidence of recurrence or metastasis was observed. CONCLUSIONS: Both ER and SR are safe and effective treatment modalities for the management of GS, with ER being associated with lower medical costs compared to SR. The majority of GS are benign and do not recur, with little possibility of malignant transformation.

Improvement strategy of citrate and biochar assisted nano-palladium/iron composite for effective dechlorination of 2,4-dichlorophenol.

Rapid passivation and aggregation of nanoscale zero-valent iron (nZVI) seriously limit its performance in the remediation of different contaminants from wastewater. To overcome such issues, in the present study, nano-palladium/iron (nPd/Fe) was simultaneously improved by biochar (BC) prepared from discarded peanut shells and green complexing agent sodium citrate (SC). For this purpose, a composite (SC-nPd/Fe@BC) was successfully synthesized to remove 2,4-dichlorophenol (2,4-DCP) from wastewater. In the SC-nPd/Fe@BC, BC acts as a carrier with dispersed nPd/Fe particles to effectively prevent its agglomeration, and increased the specific surface area of the composite, thereby improving the reactivity and stability of nPd/Fe. Characterization results demonstrated that the SC-nPd/Fe@BC composites were well dispersed, and the agglomeration was weakened. The formation of the passivation layer on the surface of the particles was inhibited, and the mechanism of SC and BC improving the reactivity of nPd/Fe was clarified. Different factors were found to influence the reductive dichlorination of 2,4-DCP, including Pd loading, Fe:C, SC addition, temperature, initial pH, and initial pollutant concentration. The dechlorination results revealed that the synergistic effect of the BC and SC made the removal efficiency and dechlorination rate of 2,4-DCP by SC-nPd/Fe@BC reached to 96.0 and 95.6%, respectively, which was better than that of nPd/Fe (removal: 46.2%, dechlorination: 45.3%). Kinetic studies explained that the dechlorination reaction of 2,4-DCP and the data were better represented by the pseudo-first-order kinetic model. The reaction rate constants followed the order of SC-nPd/Fe@BC (0.0264 min-1) > nPd/Fe@BC (0.0089 min-1) > SC-nPd/Fe (0.0081 min-1) > nPd/Fe (0.0043 min-1). Thus, SC-nPd/Fe@BC was capable of efficiently reducing 2,4-DCP and the dechlorination efficiency of BC and SC synergistically assisted composite on 2,4-DCP was much better than that of SC-nPd/Fe, nPd/Fe@BC and nPd/Fe. Findings suggested that SC-nPd/Fe@BC can be promising for efficient treatment of chlorinated pollutants.

Variability of soil organic carbon reservation capability between coastal salt marsh and riverside freshwater wetland in Chongming Dongtan and its microbial mechanism.

Two representative zones in Chongming Dongtan which faced the Yangtze River and East China Sea respectively were selected to study the variability of soil organic carbon (SOC) reservation capability between coastal wetland and riverside wetland in the Chongming Dongtan wetland as well as its mechanism by analyzing soil characteristics and plant biomass. The results showed the SOC content of riverside wetland was only 48.61% (P = 0.000 < 0.05) that of coastal wetland. As the organic matter inputs from plant litter of the coastal wetland and riverside wetland were approximately the same, the higher soil microbial respiration (SMR) of riverside wetland led to its lower SOC reservation capability. In the riverside wetland, the high soil microbial biomass, higher proportion of beta-Proteobacteria, which have strong carbon metabolism activity and the existence of some specific aerobic heterotrophic bacteria such as Bacilli and uncultured Lactococcus, were the important reasons for the higher SMR compared to the coastal wetland. There were additional differences in soil physical and chemical characteristics between the coastal wetland and riverside wetlands. Path analysis of predominant bacteria and microbial biomass showed that soil salinity influenced beta-Proteobacteria and microbial biomass most negatively among these physical and chemical factors. Therefore the low salinity of the riverside area was suitable for the growth of microorganisms, especially beta-Proteobacteria and some specific bacteria, which led to the high SMR and low SOC reservation capability when compared to the coastal area.

Stage cT3 low rectal cancer: analysis of prognostic factors.

Background: Whether all cT3 low rectal cancer patients should receive neoadjuvant chemoradiotherapy (nCRT) remains controversial. The depth of invasion beyond the muscularis propria of the cT3 rectal cancer is of great significance to the selection of a treatment plan and the evaluation of prognosis. Methods: A retrospective analysis was conducted of 187 patients with stage cT3 low rectal cancer, who had been treated at the Department of Colorectal Surgery, The First Affiliated Hospital of Xiamen University from June 2010 to December 2012. The patients were divided into the nCRT group (88 cases) and no-nCRT group (99 cases). Possible significant prognostic factors [i.e., primary tumor volume (PTV), cell differentiation, circumferential resection margin (CRM), nCRT, age, sex, carcinoembryonic antigen (CEA), lymph node status, surgical procedure, etc.] were collected for estimation of disease-free survival (DFS), distant metastases rate (DM), local recurrence rate (LR). Independent predictive factors or survival were determined using Cox proportional hazards model. Results: The mean PTV was 16.2±11.1 (2.07-72.68) cm3. In the univariate and multivariate analyses: nCRT hazards ratio (HR) =4.258, 95% confidence interval (CI): 1.912-9.483 (P<0.001); PTV HR =0.381, 95% CI: 0.181-0.804 (P=0.011); CRM HR =0.227, 95% CI: 0.097-0.532 (P=0.001). For the PTV ≤15 cm3 group, there were no significant differences between the nCRT and no-nCRT group in 3-year follow-up (P>0.05). For the PTV >15 cm3 group, there were significant differences between the nCRT and no-nCRT group in 3-year DFS (84.2% vs. 51.1%; P=0.001), DM (13.1% vs. 31.2%; P=0.017) and LR (2.9% vs. 26.6%; P=0.009). For the CRM negative group, there were significant differences between the nCRT and no-nCRT group in 3-year DFS (94.0% vs. 79.0%; P=0.008), LR (1.5% vs. 10.7%; P=0.028) and DM (4.5% vs. 13.5%; P=0.039). Conclusions: For stage cT3 low rectal cancer patients, nCRT, PTV, and CRM were independent prognostic factors. NCRT may improve the survival of PTV >15 cm3 patients, but may not have a significant effect on patient with PTV ≤15 cm3 and CRM negative. Direct surgery is recommended for this group of patients.

Metastatic Patterns and Prognosis of de novo Metastatic Nasopharyngeal Carcinoma in the United States.

OBJECTIVE: To evaluate the distant metastatic patterns and prognostic factors for overall survival (OS) and cancer-specific survival (CSS) in de novo metastatic nasopharyngeal carcinoma (mNPC) using the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: Patients with de novo mNPC who had been diagnosed between 2004 and 2016 were identified from the SEER database. Kaplan-Meier analysis was used to calculate OS and CSS. Log-rank tests were employed to measure survival variation among subgroups. Individual predictors of CSS and OS were examined using Cox proportional-hazards regression models in patients with de novo mNPC. RESULTS: We evaluated 224 patients with de novo mNPC who matched our inclusion criteria. Three-year CSS and OS for the whole cohort was 29.8% and 27.9%, respectively. Univariate analysis indicated that CSS and OS were influenced by age, histology, radiotherapy, chemotherapy, and liver metastasis. Neither the number of metastatic sites nor their specific location in bone, lungs, distant lymph nodes or brain significantly affected CSS or OS. The aforementioned independent prognosticators continued to significantly influence survival following multivariate analysis. Taking distant metastasis without liver involvement as a reference, liver metastasis was associated significantly with shorter OS at a hazard ratio (HR) of 1.581 (P = .021) and CSS at a HR of 1.643 (P = .016). Older age, keratinizing squamous cell carcinoma, no chemotherapy, and no radiotherapy were also prognosticators for poor OS (P < .05). Similar results were documented for CSS (P < .05). CONCLUSION: For patients with de novo mNPC, liver metastasis is an independent prognosticator for inferior CSS and OS. LEVEL OF EVIDENCE: 3a Laryngoscope, 131:E1130-E1138, 2021.

Dioscin-loaded zein nanoparticles alleviate lipopolysaccharide-induced acute kidney injury via the microRNA-let 7i signalling pathways.

The present study investigates the potential role of dioscin (DIO) in the lipopolysaccharide (LPS)-induced kidney injury. For this purpose, DIO-loaded zein nanoparticles (DIO-ZNPs) were formulated and evaluated for physicochemical parameters. The DIO-ZNPs exhibited a controlled release of drug compared with that of the free drug suspension. Results showed that the cell viability of NRK-52E consistently decreased with the increase in LPS from 0.01 µg/ml to 2 µg/ml. When compared with LPS, DIO-induced NPs showed 1.10-, 1.32-, 1.57- and 1.92-fold increase in the cell viability for concentrations of 20 µg/ml, 50 µg/ml, 100 µg/ml and 200 µg/ml, respectively. DIO-ZNPs exhibited the most remarkable recovery in the cell proliferation compared with free DIO as shown by the cellular morphology analysis. Furthermore, Annexin-V staining analysis showed that the LPS-treated cells possess the lowest green fluorescence indicating fewer viable cells, whereas DIO-ZNPs exhibited the maximum green fluorescence comparable with that of the non-treated cells indicating maximum cell viability. Furthermore, the results show that DIO-ZNPs significantly increased the expression of miR-let-7i in the epithelial kidney cells, whereas the expression levels of TLR4 were significantly downregulated compared with that of the LPS-treated cells. In conclusion, miR-let-7i could be an interesting therapeutic target and nanoparticle-based DIO could be a potential candidate in the management of acute kidney injury.

Permanent electric dipole moment of cerium monoxide.

Stark spectra of the [16.5]2-X(1)2 and [16.5]2-X(2)3 transitions of cerium monoxide (CeO) have been obtained at a resolution of approximately 50 MHz. Analysis of the Stark spectra yielded permanent electric dipole moments, mu(el), of 3.119(8), 3.115(7), and 2.119(8) D for the X(1)2, X(2)3, and [16.5]2 states, respectively. The ground X(1)2 state dipole moment is shown to follow the trend shown by other lanthanide oxides. While most ab initio calculations tend to overestimate the ground state dipole moment, the value calculated by using pseudopotentials in which the 4f orbital participates in the chemical bonding (Dolg,M.; Stoll, H.; Preuss, H. THEOCHEM 1991, 231, 243] is in very good agreement with our experimental value.

Ropivacaine vs. levobupivacaine: Analgesic effect of combined spinal-epidural anesthesia during childbirth and effects on neonatal Apgar scores, as well as maternal vital signs.

The present study aimed to investigate and compare the analgesic effect and safety of ropivacaine or levobupivacaine in combined spinal-epidural anesthesia during childbirth and their effects on neonatal Apgar scores, as well as maternal and neonatal vital signs. A total of 615 maternal patients undergoing labor between April 2016 and March 2017 were divided into two groups according to the analgesic used for combined spinal-epidural anesthesia during childbirth: The ropivacaine group (n=318) and the levobupivacaine group (n=297). The onset time of analgesia in the two groups was determined and the pain score on the visual analog scale was assessed at the time of delivery (T3). At pre-analgesia, 30 min after analgesia (T2), at T3 and during maternal wound suturing (T4), the systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were assessed. The cesarean section rate, neonatal 1- and 5-min Apgar scores and neonatal asphyxia at T4 were also determined. The onset time of analgesia in the ropivacaine group was significantly reduced compared with that in the levobupivacaine group (P<0.05). At T2 and T4, the SBP was significantly higher in the levobupivacaine group than that in the ropivacaine group (P<0.05). At T2, T3 and T4, the DBP was significantly lower in the levobupivacaine group compared with those in the ropivacaine group (P<0.05). At T2, the HR was significantly lower in the levobupivacaine group than that in the ropivacaine group (P<0.05). The cesarean section rate was significantly lower in the ropivacaine group compared with that in the levobupivacaine group [4.09% (n=13) vs. 22.89% (n=68); P<0.01]. In conclusion, the use of combined spinal-epidural anesthesia with ropivacaine or levobupivacaine has an excellent analgesic effect during childbirth. However, compared with levobupivacaine, ropivacaine for labor analgesia had a faster onset and a lesser impact on maternal vital signs, and was associated with a reduced maternal cesarean section rate among patients who did not opt for cesarean section in the beginning; therefore, it is useful in clinical practice.

Patterns and Prognostic Value of Lymph Node Metastasis on Distant Metastasis and Survival in Nasopharyngeal Carcinoma: A Surveillance, Epidemiology, and End Results Study, 2006-2015.

This study was conducted to identify factors associated with lymph node (LN) metastasis in nasopharyngeal carcinoma (NPC) patients, analyze node distribution patterns, and explore the prognostic value of the LN metastasis level for survival. We included 2994 patients with primary NPC diagnosed between 2006 and 2015 with information in the Surveillance, Epidemiology, and End Results (SEER) database. Patients' demographic and clinicopathologic features were compared according to LN status using chi-squared tests. The 5-year overall survival (OS) and cancer-specific survival (CSS) rates were calculated by the Kaplan-Meier method, and the differences were estimated by log-rank tests. Multivariate Cox proportional hazard models were used to evaluate independent risk factors for OS and CSS. Logistic regression was used to evaluate the risk of each LN metastasis category for distant metastasis. There were 695 patients in the N0 stage and 2299 with LN metastasis (classified as stage N1, N2, or N3). The overall incidence of LN metastasis was 76.8%. Sex and T stage were not associated with LN metastasis. Older patients had a significantly worse 5-year OS and CSS than younger patients. In terms of histologic type, keratinizing squamous cell carcinoma had the lowest 5-year OS and CSS at 48.2% and 53.8%, respectively. The most common nodal involvement level was II (65.9%), followed by III (29.1%), V (25.6%), I (17.6%), IV (15.7%), and retropharynx (13.5%). The skip metastasis rate was 5.7% (130/2299). Patients with only level II metastasis (classified as level 2) was the most common category, accounting for 30%. Compared to level 2, patients with only level I (classified as level 1) had an OR of 2.101 (95% CI: 1.090-4.047, P=0.027) for distant metastasis, patients with simultaneous levels II, III, IV, and V (classified as levels 2345) had the highest OR of 4.064 (95% CI: 2.155-7.666, P < 0.001) for distant metastasis, and level 24 had an OR of 3.003 (95% CI: 1.074-8.395, P=0.036) for distant metastasis. In survival analysis, levels 235 had a significant HR of 1.708 (95% CI: 1.089-2.678, P=0.020) for CSS compared to level 2 after adjustment for age, sex, race, histology, TNM (tumor, node, and metastasis) stage, and treatment.

Structure-Based Exciton Hamiltonian and Dynamics for the Reconstituted Wild-type CP29 Protein Antenna Complex of the Photosystem II.

We provide an analysis of the pigment composition of reconstituted wild type CP29 complexes. The obtained stoichiometry of 9 ± 0.6 Chls a and 3 ± 0.6 Chls b per complex, with some possible heterogeneity in the carotenoid binding, is in agreement with 9 Chls a and 3.5 Chls b revealed by the modeling of low-temperature optical spectra. We find that ∼50% of Chl b614 is lost during the reconstitution/purification procedure, whereas Chls a are almost fully retained. The excitonic structure and the nature of the low-energy (low-E) state(s) are addressed via simulations (using Redfield theory) of 5 K absorption and fluorescence/nonresonant hole-burned (NRHB) spectra obtained at different excitation/burning conditions. We show that, depending on laser excitation frequency, reconstituted complexes display two (independent) low-E states (i.e., the A and B traps) with different NRHB and emission spectra. The red-shifted state A near 682.4 nm is assigned to a minor (∼10%) subpopulation (sub. II) that most likely originates from an imperfect local folding occurring during protein reconstitution. Its lowest energy state A (localized on Chl a604) is easily burned with λB = 488.0 nm and has a red-shifted fluorescence origin band near 683.7 nm that is not observed in native (isolated) complexes. Prolonged burning by 488.0 nm light reveals a second low-E trap at 680.2 nm (state B) with a fluorescence origin band at ∼681 nm, which is also observed when using a direct low-fluence excitation near 650 nm. The latter state is mostly delocalized over the a611, a612, a615 Chl trimer and corresponds to the lowest energy state of the major (∼90%) subpopulation (sub. I) that exhibits a lower hole-burning quantum yield. Thus, we suggest that major sub. I correspond to the native folding of CP29, whereas the red shift of the Chl a604 site energy observed in the minor sub. II occurs only in reconstituted complexes.

New Insight into the Water-Soluble Chlorophyll-Binding Protein from Lepidium virginicum.

This study describes new recombinant water-soluble chlorophyll (Chl)-binding proteins (WSCP) from Lepidium virginicum (LvWSCP). This complex binds four Chls (i.e. two dimers of Chls) per protein tetramer. We show that absorption, emission, hole-burned (HB) spectra and the shape of the zero-phonon hole (ZPH) action spectrum are consistent with the presence of uncorrelated excitation energy transfer between two Chl dimers. Thus, there is no need to include slow protein relaxation within the lowest excited state (as suggested in a previous analysis of cauliflower WSCP [Schmitt, F.-J. et al. (2008) J. Phys. Chem. B, 112, 13951; Pieper, J. et al. (2011) J. Phys. Chem. B, 115, 4053]) in order to explain the large shift observed between the maxima of the ZPH action and emission spectra. Experimental evidence is provided which shows that electron exchange between lowest energy Chls and the protein may occur, i.e. electrons can be trapped at low temperature by nearby aromatic amino acids. The latter explains the shape of nonresonant HB spectra (i.e. the absence of antihole), demonstrating that the hole-burning process in LvWSCP is largely photochemical in nature, though a small contribution from nonphotochemical hole burning (in resonant holes) is also observed.

On the Conflicting Estimations of Pigment Site Energies in Photosynthetic Complexes: A Case Study of the CP47 Complex.

We focus on problems with elucidation of site energies [Formula: see text] for photosynthetic complexes (PSCs) in order to raise some genuine concern regarding the conflicting estimations propagating in the literature. As an example, we provide a stern assessment of the site energies extracted from fits to optical spectra of the widely studied CP47 antenna complex of photosystem II from spinach, though many general comments apply to other PSCs as well. Correct values of [Formula: see text] for chlorophyll (Chl) a in CP47 are essential for understanding its excitonic structure, population dynamics, and excitation energy pathway(s). To demonstrate this, we present a case study where simultaneous fits of multiple spectra (absorption, emission, circular dichroism, and nonresonant hole-burned spectra) show that several sets of parameters can fit the spectra very well. Importantly, we show that variable emission maxima (690-695 nm) and sample-dependent bleaching in nonresonant hole-burning spectra reported in literature could be explained, assuming that many previously studied CP47 samples were a mixture of intact and destabilized proteins. It appears that the destabilized subpopulation of CP47 complexes could feature a weakened hydrogen bond between the 13(1)-keto group of Chl29 and the PsbH protein subunit, though other possibilities cannot be entirely excluded, as discussed in this work. Possible implications of our findings are briefly discussed.

Mutation-Induced Changes in the Protein Environment and Site Energies in the (M)L214G Mutant of the Rhodobacter sphaeroides Bacterial Reaction Center.

This work focuses on the low-temperature (5 K) photochemical (transient) hole-burned (HB) spectra within the P870 absorption band, and their theoretical analysis, for the (M)L214G mutant of the photosynthetic Rhodobacter sphaeroides bacterial reaction center (bRC). To provide insight into system-bath interactions of the bacteriochlorophyll a (BChl a) special pair, i.e., P870, in the mutated bRC, the optical line shape function for the P870 band is calculated numerically. On the basis of the modeling studies, we demonstrate that (M)L214G mutation leads to a heterogeneous population of bRCs with modified (increased) total electron-phonon coupling strength of the special pair BChl a and larger inhomogeneous broadening. Specifically, we show that after mutation in the (M)L214G bRC a large fraction (∼50%) of the bacteriopheophytin (HA) chromophores shifts red and the 800 nm absorption band broadens, while the remaining fraction of HA cofactors retains nearly the same site energy as HA in the wild-type bRC. Modeling using these two subpopulations allowed for fits of the absorption and nonresonant (transient) HB spectra of the mutant bRC in the charge neutral, oxidized, and charge-separated states using the Frenkel exciton Hamiltonian, providing new insight into the mutant's complex electronic structure. Although the average (M)L214G mutant quantum efficiency of P(+)QA(-) state formation seems to be altered in comparison with the wild-type bRC, the average electron transfer time (measured via resonant transient HB spectra within the P870 band) was not affected. Thus, mutation in the vicinity of the electron acceptor (HA) does not tune the charge separation dynamics. Finally, quenching of the (M)L214G mutant excited states by P(+) is addressed by persistent HB spectra burned within the B band in chemically oxidized samples.

Alternative Excitonic Structure in the Baseplate (BChl a-CsmA Complex) of the Chlorosome from Chlorobaculum tepidum.

In the photosynthetic green sulfur bacterium Chlorobaculum tepidum, the baseplate mediates excitation energy transfer from the light-harvesting chlorosome to the Fenna-Matthews-Olson (FMO) complex and subsequently toward the reaction center (RC). Literature data suggest that the baseplate is a 2D lattice of BChl a-CsmA dimers. However, recently, it has been proposed, using 2D electronic spectroscopy (2DES) at 77 K, that at least four excitonically coupled BChl a are in close contact within the baseplate structure [ Dostál , J. ; et al., J. Phys. Chem. Lett. 2014 , 5 , 1743 ]. This finding is tested via hole burning (HB) spectroscopy (5 K). Our results indicate that the four excitonic states identified by 2DES likely correspond to contamination of the baseplate with the FMO antenna and possibly the RC. In contrast, HB reveals a different excitonic structure of the baseplate chromophores, where excitation is transferred to a localized trap state near 818 nm via exciton hopping, which leads to emission near 826 nm.

Water organic pollution and eutrophication influence soil microbial processes, increasing soil respiration of estuarine wetlands: site study in jiuduansha wetland.

Undisturbed natural wetlands are important carbon sinks due to their low soil respiration. When compared with inland alpine wetlands, estuarine wetlands in densely populated areas are subjected to great pressure associated with environmental pollution. However, the effects of water pollution and eutrophication on soil respiration of estuarine and their mechanism have still not been thoroughly investigated. In this study, two representative zones of a tidal wetland located in the upstream and downstream were investigated to determine the effects of water organic pollution and eutrophication on soil respiration of estuarine wetlands and its mechanism. The results showed that eutrophication, which is a result of there being an excess of nutrients including nitrogen and phosphorus, and organic pollutants in the water near Shang shoal located upstream were higher than in downstream Xia shoal. Due to the absorption and interception function of shoals, there to be more nitrogen, phosphorus and organic matter in Shang shoal soil than in Xia shoal. Abundant nitrogen, phosphorus and organic carbon input to soil of Shang shoal promoted reproduction and growth of some highly heterotrophic metabolic microorganisms such as ß-Proteobacteria, γ-Proteobacteria and Acidobacteria which is not conducive to carbon sequestration. These results imply that the performance of pollutant interception and purification function of estuarine wetlands may weaken their carbon sequestration function to some extent.