GPMeta: a GPU-accelerated method for ultrarapid pathogen identification from metagenomic sequences.

Metagenomic sequencing (mNGS) is a powerful diagnostic tool to detect causative pathogens in clinical microbiological testing owing to its unbiasedness and substantially reduced costs. Rapid and accurate classification of metagenomic sequences is a critical procedure for pathogen identification in dry-lab step of mNGS test. However, clinical practices of the testing technology are hampered by the challenge of classifying sequences within a clinically relevant timeframe. Here, we present GPMeta, a novel GPU-accelerated approach to ultrarapid pathogen identification from complex mNGS data, allowing users to bypass this limitation. Using mock microbial community datasets and public real metagenomic sequencing datasets from clinical samples, we show that GPMeta has not only higher accuracy but also significantly higher speed than existing state-of-the-art tools such as Bowtie2, Bwa, Kraken2 and Centrifuge. Furthermore, GPMeta offers GPMetaC clustering algorithm, a statistical model for clustering and rescoring ambiguous alignments to improve the discrimination of highly homologous sequences from microbial genomes with average nucleotide identity >95%. GPMetaC exhibits higher precision and recall rate than others. GPMeta underlines its key role in the development of the mNGS test in infectious diseases that require rapid turnaround times. Further study will discern how to best and easily integrate GPMeta into routine clinical practices. GPMeta is freely accessible to non-commercial users at https://github.com/Bgi-LUSH/GPMeta.

Exosomes regulate SIRT3-related autophagy by delivering miR-421 to regulate macrophage polarization and participate in OSA-related NAFLD.

PURPOSE: To analyze the role of and mechanism underlying obstructive sleep apnea (OSA)-derived exosomes in inducing non-alcoholic fatty liver (NAFLD). METHODS: The role of OSA-derived exosomes was analyzed in inducing hepatocyte fat accumulation in mice models both in vivo and in vitro. RESULTS: OSA-derived exosomes caused fat accumulation and macrophage activation in the liver tissue. These exosomes promoted fat accumulation; steatosis was more noticeable in the presence of macrophages. Macrophages could internalize OSA-derived exosomes, which promoted macrophage polarization to the M1 type. Moreover, it inhibited sirtuin-3 (SIRT3)/AMP-activated protein kinase (AMPK) and autophagy and promoted the activation of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasomes. The use of 3-methyladenine (3-MA) to inhibit autophagy blocked NLRP3 inflammasome activation and inhibited the M1 polarization of macrophages. miR-421 targeting inhibited SIRT3 protein expression in the macrophages. miR-421 was significantly increased in OSA-derived exosomes. Additionally, miR-421 levels were increased in OSA + NAFLD mice- and patient-derived exosomes. In the liver tissues of OSA and OSA + NAFLD mice, miR-421 displayed similar co-localization with the macrophages. Intermittent hypoxia-induced hepatocytes deliver miR-421 to the macrophages via exosomes to inhibit SIRT3, thereby participating in macrophage M1 polarization. After OSA and NAFLD modeling in miR-421-/- mice, liver steatosis and M1 polarization were significantly reduced. Additionally, in the case of miR-421 knockout, the inhibitory effects of OSA-derived exosomes on SIRT3 and autophagy were significantly alleviated. Furthermore, their effects on liver steatosis and macrophage M1 polarization were significantly reduced. CONCLUSIONS: OSA promotes the delivery of miR-421 from the hepatocytes to macrophages. Additionally, it promotes M1 polarization by regulating the SIRT3/AMPK-autophagy pathway, thereby causing NAFLD.

Risk factors of electrical status epilepticus during sleep in children with benign childhood epilepsy with centro-temporal spikes.

Objective: To explore risk factors of electrical status epilepticus during sleep in children with benign childhood epilepsy with centro-temporal spikes (BECT). Methods: This is a clinical comparative study. The subjects of study were 67 children with BECT from the Outpatient Department of Pediatric Neurology in Xingtai People's Hospital from January 2019 to January 2022. According to the occurrence of ESES, the enrolled children were divided into control group which included BECT children without ESES and the observation group which included BECT children with ESES. Compared differences of the two groups in the age of first seizure, the frequency of seizures before treatment, the classification of treatment drugs, cranial MRI, and discharge side of electroencephalogram (EEG). Results: There was no statistical difference between the two groups in the frequency of seizures before treatment, the classification of treatment drugs, cranial MRI, and the distribution of EEG discharges in the left and right cerebral areas(P>0.05). Statistical differences were observed in the age of the first seizure, whether the seizures occurred after treatment, and EEG discharges in unilateral/bilateral cerebral areas (P<0.05). Furthermore, the collinearity test and Logistic regression analysis showed that the age of the first seizure, the frequency of seizures before treatment, and whether the seizures occurred after treatment were independent risk factors for the occurrence of ESES in BECT (P<0.05). Conclusion: Clinically, the occurrence of ESES in children with BECT may be related to the younger age of the first seizure, higher frequency of seizures before treatment, and the occurrence of seizures after treatment.

Mixed-Linker Strategy for the Construction of Sulfone-Containing D-A-A Covalent Organic Frameworks for Efficient Photocatalytic Hydrogen Peroxide Production.

The solar-driven photocatalytic production of hydrogen peroxide (H2O2) from water and oxygen using semiconductor catalysts offers a promising approach for converting solar energy into storable chemical energy. However, the efficiency of photocatalytic H2O2 production is often restricted by the low photo-generated charge separation, slow surface reactions and inadequate stability. Here, we developed a mixed-linker strategy to build a donor-acceptor-acceptor (D-A-A) type covalent organic framework (COF) photocatalyst, FS-OHOMe-COF. The FS-OHOMe-COF structure features extended π-π conjugation that improves charge mobility, while the introduction of sulfone units not only as active sites facilitates surface reactions with water but also bolsters stability through increased interlayer forces. The resulting FS-OHOMe-COF has a low exciton binding energy, long excited-state lifetime and high photo-stability that leads to high performance for photocatalytic H2O2 production (up to 1.0 mM h-1) with an H2O2 output of 19 mM after 72 hours of irradiation. Furthermore, the catalyst demonstrates high stability, which sustained activity over 192 hours of photocatalytic experiment.

Covalent Organic Framework Nanohydrogels.

Nanohydrogelation of covalent organic frameworks (COFs) will undoubtedly open up new applications for them in water, such as aqueous catalysis and biomedicine. It is currently a great challenge to achieve water dispersion of COFs through either bottom-up construction strategies or top-down exfoliating technologies. Herein, poly(N-isopropylacrylamide) (PNIPAM)-postmodified COF nanohydrogels (COF-NHGs) are successfully designed and synthesized via in situ atom-transfer radical polymerization (ATRP) on a scaffold of COFs. During the polymer growth process, the bulk COFs are exfoliated into nanosheets with a lateral size of ∼500 nm and a thickness of ∼6.5 nm. Moreover, their size can be precisely controlled by the degree of polymerization of PNIPAMs. In aqueous solution, the obtained COF-NHGs are assembled into nanohydrogels retaining intra-plane crystallinity and exhibit a temperature-sensitive sol-gel phase transition. With excellent solubility in organic solvents, the COF-NHGs' intrinsic physical properties in the solution state can be characterized through their solution nuclear magnetic resonance and ultraviolet absorption spectra. These results put forward new opportunities for regulating the solution processability of COFs and building an intelligent, stimuli-response platform of COF-polymer composite nanohydrogels for device applications.

Arabidopsis NPF2.13 functions as a critical transporter of bacterial natural compound tunicamycin in plant-microbe interaction.

Metabolites including antibiotics, enzymes, and volatiles produced by plant-associated bacteria are key factors in plant-microbiota interaction that regulates various plant biological processes. There should be crucial mediators responsible for their entry into host plants. However, less is known about the identities of these plant transporters. We report that the Arabidopsis Nitrate Transporter1 (NRT1)/NPF protein NPF2.13 functions in plant uptake of tunicamycin (TM), a natural antibiotic produced by several Streptomyces spp., which inhibits protein N-glycosylation. Loss of NPF2.13 function resulted in enhanced TM tolerance, whereas NPF2.13 overexpression led to TM hypersensitivity. Transport assays confirmed that NPF2.13 is a H+ /TM symporter and the transport is not affected by other substrates like nitrate. NPF2.13 exclusively showed TM transport activity among tested NPFs. Tunicamycin uptake from TM-producing Streptomyces upregulated the expression of nitrate-related genes including NPF2.13. Moreover, nitrate allocation to younger leaves was promoted by TM in host plants. Tunicamycin could also benefit plant defense against the pathogen. Notably, the TM effects were significantly repressed in npf2.13 mutant. Overall, this study identifies NPF2.13 protein as an important TM transporter in plant-microbe interaction and provides insights into multiple facets of NPF proteins in modulating plant nutrition and defense by transporting exterior bacterial metabolites.

Covalent Triazine Frameworks (CTFs): Synthesis, Crystallization, and Photocatalytic Water Splitting.

Covalent Triazine Frameworks (CTFs) have received great attention from academia owing to their unique structure characteristics such as nitrogen-rich structure, chemical stability, fully conjugated skeleton and high surface area; all these unique properties make CTFs attractive for widespread applications, especially for photocatalytic applications. In this review, we aim to provide recent advances in the CTFs preparation, and mainly focus on their photocatalytic applications. This review provides a comprehensive and systematic overview of the CTFs' synthetic methods, crystallinity lifting strategies, and their applications for photocatalytic water splitting. Firstly, a brief background including the photocatalytic water splitting and crystallinity are provided. Then, synthetic methods related to CTFs and the strategies for enhancing the crystallinity are summarized and compared. After that, the general photocatalytic mechanism and the strategies to improve the photocatalytic performance of CTFs are discussed. Finally, the perspectives and challenges of fabricating high crystalline CTFs and designing CTFs with excellent photocatalytic performance are discussed, inspiring the development of CTF materials in photocatalytic applications.

Light Triggered Pore Size Tuning in Photoswitching Covalent Triazine Frameworks for Low Energy CO2 Capture.

Recently, photo switching porous materials have been widely reported for low energy costed CO2 capture and release via simply remoted light controlling method. However, most reported photo responsive CO2 adsorbents relied on metal organic framework (MOFs) functionalisation with photochromic moieties, and MOF adsorbents still suffered from chemically and thermally unstable issues. Thus, further metal free and highly stable organic photoresponsive adsorbents are necessary to be developed. CTFs, because of their high porosity and stability, have attracted great attention for CO2 capture. Considering the high CO2 uptake capacity and structural tunability of CTFs, it suggests high potential to fabricate the photoswitching CTF materials by the same functionalisation method as MOFs. Herein, the first series of photo switching CTFs were developed for low energy CO2 capture and release. Apart from that, the CO2 switching efficiency could be doubled either through the azobenzene numbers adjusting method or through the previously reported structural alleviation strategy. Furthermore, the pore size distribution of azobenzene functionalised PCTFs also could be tuned under UV exposure, which may contribute to the UV light induced decrease of CO2 uptake capacity. These photoswitching CTFs represented a new kind of porous polymers for low energy costed CO2 capture.

Prognostic factors and clinical efficacy of second-line treatments of Pneumocystis jirovecii pneumonia for non-HIV patients after first-line treatment failure.

BACKGROUND: Pneumocystis jirovecii pneumonia (PCP) is a life-threatening opportunistic infection. In non-HIV immunocompromised patients with PCP, a standard second-line treatment has not been established up to now. METHODS: Non-HIV immunocompromised patients with confirmed PCP between April 2013 and December 2020 were included. Their PCP treatment history was tracked. Factors related to first-line trimethoprim/sulfamethoxazole (TMP/SMX) and second-line treatment failure were identified. Different second-line treatment strategies were compared. RESULTS: Among the 220 patients, 127 (57.73%) did not respond to first-line TMP/SMX treatment. Risk factors related to treatment failure included symptom triad with breathlessness at rest, persistent fever and cough (85% in the treatment failure group versus 74% in the treatment success group, P = 0.034), treatment with invasive mechanical ventilation (67 vs. 19%, P < 0.001), coinfection with CMV (69 vs. 47%, P = 0.035), and bacteremia (59 vs. 10%, P < 0.001). A total of 49 patients received second-line treatment on the basis of TMP/SMX, and 28 (57.1%) of them responded to the treatment. No clinical parameter, including selection of different therapies, was found to be significantly associated with second-line treatment failure. Further, the prognosis of different second-line therapies showed no drug or drug combination strategy superior to others. The primaquine group had lower 90-day mortality rate (45.9%) but showed no statistically significant difference compared with the non-primaquine group (64.6%). The patients in the clindamycin plus primaquine group had the lowest in-hospital mortality rate (22.2%, P = 0.042) among different second-line therapies, although the in-hospital mortality of the primaquine group was not significantly different from that of the non-primaquine group. The differences in 28 day mortality and overall mortality rates were not statistically significant, too. CONCLUSION: CMV infection and bacteremia were risk factors significantly associated with treatment failure of TMP/SMX. The response and survival rates of second-line treatment, including clindamycin, primaquine, and caspofungin, were poor, maybe clindamycin plus primaquine as second line treatment was better than other treatment strategies. These results suggest that clinicians should carefully evaluate whether the treatment of TMP/SMX has failed due to a coinfection rather than hastily changing to a second-line drug when the patient worsens.

Metabolomic and regular analysis reveal phytotoxic mechanisms of sterigmatocystin in Amaranthus retroflexus L.

Sterigmatocystin (STE) is a common hepatotoxic and nephrotoxic contaminant in cereals, however, its phytotoxicity and mechanisms are poorly understood. Here, the phytotoxic mechanisms of STE were investigated via the metabolomics of Amaranthus retroflexus L. A total of 140 and 113 differential metabolites were detected in the leaves and stems, respectively, among which amino acids, lipids, and phenolic compounds were significantly perturbed. Valine, leucine, isoleucine, and lysine biosynthesis were affected by STE. These metabolic responses revealed that STE might be toxic to plants by altering the plasma membrane and inducing oxidative damage, which was verified by measuring the relative electrical conductivity and quantification of reactive oxygen species. The elevated amino acids, as well as the decreased of D-sedoheptuiose-7-phosphate indicated increased proteolysis and carbohydrate metabolism restriction. Furthermore, the IAA level also decreased. This study provides a better understanding of the impacts of STE on the public health, environment and food security.

Three-Dimensional Crystalline Covalent Triazine Frameworks via a Polycondensation Approach.

The growth of crystalline covalent triazine frameworks (CTFs) is still considered as a great challenge due to the less reversible covalent bonds of triazine linkages. The research studies of crystalline CTFs to date have been limited to two-dimensional (2D) structures, and the three-dimensional (3D) crystalline CTFs have never been reported before. Herein we report the design and synthesis of two 3D crystalline CTFs, termed 3D CTF-TPM and 3D CTF-TPA through a reversible/irreversible polycondensation approach. The targeted 3D CTFs adopt ctn topology, and show moderate crystallinity, relatively large surface area (ca. 2000 m2 g-1 ), and high CO2 uptake capacity (23.61 wt.%). Moreover, these 3D CTFs exhibit ultrastability in the presence of boiling water, strong acid (1 M HCl) and strong base (1 M NaOH). This contribution represents the first report of 3D crystalline CTFs, which not only extends their structural diversity but also offers a synthetic strategy and structural basis for expanding practical applications of CTF materials.

Neoxanthin affects the stability of the C2 S2 M2 -type photosystem II supercomplexes and the kinetics of state transition in Arabidopsis.

Neoxanthin (Neo), which is only bound to the peripheral antenna proteins of photosystem (PS) II, is a conserved carotenoid in all green plants. It has been demonstrated that Neo plays an important role in photoprotection and its deficiency fails to impact LHCII stability in vitro and indoor plant growth in vivo. Whether Neo is involved in maintaining the PSII complex structure or adaptive mechanisms for the everchanging environment has not yet been elucidated. In this study, the role of Neo in maintaining the structure and function of the PSII-LHCII supercomplexes was studied using Neo deficient Arabidopsis mutants. Our results show that Neo deficiency had little effect on the electron transport capacity and the plant fitness, but the PSII-LHCII supercomplexes were significantly impacted by the lack of Neo. In the absence of Neo, the M-type LHCII trimer cannot effectively associate with the C2 S2 -type PSII-LHCII supercomplexes even in moderate light conditions. Interestingly, Neo deficiency also leads to decreased PSII protein phosphorylation but rapid transition from state 1 to state 2. We suggest that Neo might enforce the interactions between LHCII and the minor antennas and that the absence of Neo makes M-type LHCII disassociate from the PSII complex, leading to the disassembly of the PSII-LHCII C2 S2 M2 supercomplexes, which results in alterations in the phosphorylation patterns of the thylakoid photosynthetic proteins and the kinetics of state transition.

Klebsiella pneumoniae-related invasive liver abscess syndrome complicated by purulent meningitis: a review of the literature and description of three cases.

BACKGROUND: Klebsiella pneumoniae (K. pneumoniae) invasive liver abscess syndrome (ILAS) with purulent meningitis was rarely identified the mainland of China. Last winter, we received 3 cases of K. pneumoniae meningitis and all of them died in a short time. We report these cases in order to find the reason of high mortality and discuss effective effort to improve these patients' prognosis. CASE PRESENTATION: Three patients with uncontrolled diabetes developed live abscess and purulent meningitis. Upon admission, the clinical manifestations, laboratory result of blood and cerebrospinal fluid (CSF) and imaging examinations were compatible with K. pneumoniae ILAS which had metastasis infection of meningitis. Even with timely adequate antibiotic therapy and strict glycemic control, all of the patients' condition deteriorated rapidly and died in a short time. CONCLUSION: The reason of patients' poor prognosis might be the absence of liver abscess drainage, high level of CSF protein which indicates severe inflammation and unknown special but stronger virulence factors of K. pneumoniae the patients' living place Zhangjiakou. Strict glycemic control, early drainage of liver abscess and appropriate antibiotic application are recommended for treating this condition, further progress on the pathogenesis and treatment of K. pneumoniae meningitis may help patients gain a better prognosis.

A Super-Amphiphilic 3D Silicone Sponge with High Porosity for the Efficient Adsorption of Various Pollutants.

Silicone sponge, which is nontoxic, highly flexible, insulated, and chemically inert, has great promise in the aerospace, electronics, and health care industries. However, the inherent surface properties and the harsh synthesis method limit its application. A super-amphiphilic 3D silicone sponge is designed by a thiol-ene click reaction for the first time. The sponge possesses high porosity, low density, excellent adsorption ability, and reusability for water, oil, emulsions, and Hg2+ or dyes or suspended solids in them. The sponge can selectively adsorb a very high amount (941.3 mg g-1 ) of Hg2+ from solutions (water, oil, emulsions) containing various ions at a nearly 100% removal efficiency. Cation dyes can also be selectively captured by the sponge. Furthermore, the sponge is designed as a filter element for a filtration system, and the content of the pollutants in the filtrate reaches drinkable levels after the Hg2+ and dye solutions are processed. The filter can be reused with almost unchanged filtration efficiency after a simple washing process. The successful treatment of actual/artificial polluted water proves its practical value.

Physiological responses of Arthrobacter sp. JQ-1 cell interfaces to co-existed di-(2-ethylhexyl) phthalate (DEHP) and copper.

Arthrobacter sp. JQ-1 can completely degrade 500 mg/L of DEHP within 3 days. The minimum inhibitory concentrations (MICs) of Cu2+ could reach 1.56 mM, however, 5.0 mg/L Cu2+ apparently inhibited DEHP degradation and bacterial growth. Consequently, JQ-1 was exposed to the DEHP-copper environment to verify the toxicity mechanism based on the physiological responses of cellular multiple interfaces (cellular surface, membrane and intracellular characteristics). The results showed the combination of 500 mg/L DEHP and 5.0 mg/L Cu2+ significantly decreased cell surface hydrophobicity (CSH) and the absolute value of zeta potential, which implied the bioavailability of DEHP was decreased. The cellular surface changes were mainly due to the interaction between Cu2+ and some functional groups (CH2, CH3, aromatic rings, and amide). The weakened proton-motive force (PMF) across the plasma membrane may interfere the formation and utilization of energy, which is not conducive to the repair process of cellular damages. In this study, Non-invasive micro-test technology (NMT) was applied to the research of combined toxicity of DEHP and heavy metal ions for the first time. DEHP-copper intensified K+ efflux and Ca2+ influx across the plasma membrane, which disturbed ion homeostasis of K+ and Ca2+ and might induce apoptosis and further inhibit DEHP degradation. The decline of intracellular esterase activity indicated that the metabolic capacity is apparently restrained. This study enhances our understanding of cellular different interface processes responding to combined pollutants.

Rapid Classification and Quantification of Camellia (Camellia oleifera Abel.) Oil Blended with Rapeseed Oil Using FTIR-ATR Spectroscopy.

Currently, the authentication of camellia oil (CAO) has become very important due to the possible adulteration of CAO with cheaper vegetable oils such as rapeseed oil (RSO). Therefore, we report a Fourier transform infrared (FTIR) spectroscopic method for detecting the authenticity of CAO and quantifying the blended levels of RSO. In this study, two characteristic spectral bands (1119 cm-1 and 1096 cm-1) were selected and used for monitoring the purity of CAO. In combination with principal component analysis (PCA), linear discriminant analysis (LDA), and partial least squares regression (PLSR) analysis, qualitative and quantitative methods for the detection of camellia oil adulteration were proposed. The results showed that the calculated I1119/I1096 intensity ratio facilitated an initial check for pure CAO and six other edible oils. PCA was used on the optimized spectral region of 1800-650 cm-1. We observed the classification of CAO and RSO as well as discrimination of CAO with RSO adulterants. LDA was utilized to classify CAO from RSO. We could differentiate and classify RSO adulterants up to 1% v/v. In the quantitative PLSR models, the plots of actual values versus predicted values exhibited high linearity. Root mean square error of calibration (RMSEC) and root mean square error of cross validation (RMSECV) values of the PLSR models were 1.4518%-3.3164% v/v and 1.7196%-3.8136% v/v, respectively. This method was successfully applied in the classification and quantification of CAO adulteration with RSO.

The effect of spleen tyrosine kinase inhibitor R406 on diabetic retinopathy in experimental diabetic rats.

PURPOSE: To investigate the effect of spleen tyrosine kinase (Syk) inhibitor R406 on diabetic retinopathy (DR) in diabetic mellitus (DM) rats. METHODS: Rats were randomized into Normal, DM, DM + 5 mg/kg R406 and DM + 10 mg/kg R406 groups. DM rats were established via injection of streptozotocin (STZ). One week after model establishment, rats in treatment groups received 5 mg/kg or 10 mg/kg R406 by gavage administration for 12 weeks consecutively, followed by the detection with hematoxylin-eosin (HE) staining, Evans blue angiography, retinal trypsin digestion assay, Western blotting, immunohistochemistry, TUNEL assay, immunofluorescence assay and quantitative reverse transcriptase real-time polymerase chain reaction (qRT-PCR). RESULTS: The retina of DM rats presented different degree of edema, disordered and loose structure, swollen cells with enlarged intercellular space, and dilated and congested capillaries. Besides, the retinal vessels of DM rats showed high fluorescence leakage. However, R406 alleviated the above-mentioned conditions, which was much better with high concentration of R406 (10 mg/kg). R406 also reversed the down-regulations of occludin, claudin-5, ZO-1 and the up-regulation of and VEGF in retinal tissues of DM rats; inhibited retinal cell apoptosis; strengthened retinal cell proliferation; and reduced expressions of IL-1ß, IL-6, TNF-α and nuclear p65 NF-κB in retinal tissues. The improvement in all these indexes was much more significant in rats of DM + 10 mg/kg R406 group than in rats of DM + 5 mg/kg R406 group. CONCLUSION: Syk inhibitor R406 could attenuate retinal inflammation in DR rats via the repression of NF-κB activation.

The drivers of bacterial community underlying biogeographical pattern in Mollisol area of China.

In order to better understand the composition and driving factors of the bacterial community in Mollisols, we selected 9 representative facility agricultural lands in Mollisol area of China for sampling, and described it on a larger spatial scale. Soil bacterial community structure in these 9 regions (determined by high-throughput sequencing analysis) showed significant differences at the genus level. The correlation between bacterial community composition and soil properties, contaminants and geographical latitude showed that the diversity of bacterial community was still strongly correlated with pH and SOM under the influence of phthalates (P < 0.05). Principal component Analysis (PCA) showed that soil properties (i.e. pH, organic matter, stacking density, the content of nitrogen, potassium, phosphorus) and PAEs level rather than geographic latitude were main drivers of differences in bacterial community structure. These factors account for 73.04% of the total variation of the bacterial community. Among them, PAEs act as a typical pollutant is the main factor driving the composition of bacterial community in facility agriculture Mollisols. This shows that PAEs is a potential pollution risk factor, which has important guiding significance for the sustainable and healthy development of agriculture in Mollisol area.

The N-terminal domain of Lhcb proteins is critical for recognition of the LHCII kinase.

The light-harvesting chlorophyll (Chl) a/b complex of photosystem (PS) II (LHCII) plays important roles in the distribution of the excitation energy between the two PSs in the thylakoid membrane during state transitions. In this process, LHCII, homo- or heterotrimers composed of Lhcb1-3, migrate between PSII and PSI depending on the phosphorylation status of Lhcb1 and Lhcb2. We have studied the mechanisms of the substrate recognition of a thylakoid threonine kinase using reconstituted site-directed trimeric Lhcb protein-pigment complex mutants. Mutants lacking the positively charged residues R/K upstream of phosphorylation site (Thr) in the N-terminal domain of Lhcb1 were no longer phosphorylated. Besides, the length of the peptide upstream of the phosphorylated site (Thr) is also crucial for Lhcb phosphorylation in vitro. Furthermore, the two N-terminal residues of Lhcb appear to play a key role in the phosphorylation kinetics because Lhcb with N-terminal RR was phosphorylated much faster than with RK. Therefore, we conclude that the substrate recognition of the LHCII kinase is determined to a large extent by the N-terminal sequence of the Lhcb proteins. The study provides new insights into the interactions of the Lhcb proteins with the LHCII kinase.

Direct energy transfer from the major antenna to the photosystem II core complexes in the absence of minor antennae in liposomes.

Minor antennae of photosystem (PS) II, located between the PSII core complex and the major antenna (LHCII), are important components for the structural and functional integrity of PSII supercomplexes. In order to study the functional significance of minor antennae in the energetic coupling between LHCII and the PSII core, characteristics of PSII-LHCII proteoliposomes, with or without minor antennae, were investigated. Two types of PSII preparations containing different antenna compositions were isolated from pea: 1) the PSII preparation composed of the PSII core complex, all of the minor antennae, and a small amount of major antennae (MCC); and 2) the purified PSII dimeric core complexes without periphery antenna (CC). They were incorporated, together with LHCII, into liposomes composed of thylakoid membrane lipids. The spectroscopic and functional characteristics were measured. 77K fluorescence emission spectra revealed an increased spectral weight of fluorescence from PSII reaction center in the CC-LHCII proteoliposomes, implying energetic coupling between LHCII and CC in the proteoliposomes lacking minor antennae. This result was further confirmed by chlorophyll a fluorescence induction kinetics. The incorporation of LHCII together with CC markedly increased the antenna cross-section of the PSII core complex. The 2,6-dichlorophenolindophenol photoreduction measurement implied that the lack of minor antennae in PSII supercomplexes did not block the energy transfer from LHCII to the PSII core complex. In conclusion, it is possible, in liposomes, that LHCII transfer energy directly to the PSII core complex, in the absence of minor antennae.