A highly specific and ultrasensitive approach to detect Prymnesium parvum based on RPA-CRISPR-LbaCas12a-LFD system.

BACKGROUND: Harmful algal blooms (HABs), caused by the rapid proliferation or aggregation of microorganisms, are catastrophic for the environment. The Prymnesium parvum is a haptophyte algal species that is found worldwide and is responsible for extensive blooms and death of larval amphibians and bivalves, causing serious negative impacts on the ecological environment. For the prevention and management of environmental pollution, it is crucial to explore and develop early detection strategies for HABs on-site using simple methods. The major challenge related to early detection is the accurate and sensitive detection of algae present in low abundance. RESULTS: Herein, recombinase polymerase amplification (RPA) was combined with clustered regularly interspaced short palindromic repeats and Cas12a protein (CRISPR-LbaCas12a) systems, and the lateral flow dipstick (LFD) was used for the first time for early detection of P. parvum. The internal transcribed spacer (ITS) of P. parvum was selected as the target sequence, and the concentration of single-strand DNA reporters, buffer liquid system, reaction time, and amount of gold particles were optimized. The RPA-CRISPR-LbaCas12a-LFD approach demonstrated highly specificity during experimental testing, with no cross-reaction against different microalgae used as controls. In addition, the lowest detection limit was 10,000 times better than the lowest detection limit of the standalone RPA approach. The feasibility and robustness of this approach were further verified by using the different environmental samples. It also observed that P. parvum are widely distributed in Chinese Sea, but the cell density of P. parvum is relatively low (<0.1 cells/mL). SIGNIFICANCE: The developed approach has an excellent specificity and offers 10,000 times better sensitivity than the standalone RPA approach. These advantages make this approach suitable for early warning detection and prevention of HAB events in environmental water. Also, the outcomes of this study could promote a shift from traditional laboratory-based detection to on-site monitoring, facilitating early warning against HABs.

[Retracted] Downregulation of CKS1B restrains the proliferation, migration, invasion and angiogenesis of retinoblastoma cells through the MEK/ERK signaling pathway.

Following the publication of the above paper, it has been drawn to the Editors' attention by a concerned reader that certain of the lumen formation assay data shown in Fig. 5A on p. 112 were strikingly similar to data appearing in different form in another article written by different authors at different research institute, which had already been published in the journal Biomedicine & Pharmacotherapy prior to the submission of this paper to International Journal of Molecular Medicine, and which has also subsequently been retracted. In view of the fact that the contentious data had already apparently been published previously, the Editor of International Journal of Molecular Medicine has decided that this paper should be retracted from the Journal. After having been in contact with the authors, they agreed with the decision to retract the paper. The Editor apologizes to the readership for any inconvenience caused. [International Journal of Molecular Medicine 44: 103­114, 2019; DOI: 10.3892/ijmm.2019.4183].

Toxicity of common biocides used in aquaculture to embryos and larvae of Brachymystax tsinlingensis Li.

Brachymystax tsinlingensis Li is a threatened fish species endemic to China. With the problems of environmental factors and seeding breeding diseases, it is important to further improve the efficiency of seeding breeding and the basis of resource protection. This study investigated the acute toxicity of copper, zinc and methylene blue (MB) on hatching, survival, morphology, heart rate (HR) and stress behaviour of B. tsinlingensis. Eggs (diameter: 3.86 ± 0.07 mm, weight: 0.032 ± 0.004 g) of B. tsinlingensis were selected randomly from artificial propagation and developed from eye-pigmentation-stage embryos to yolk-sac stage larvae (length: 12.40 ± 0.02 mm, weight: 0.03 ± 0.001 g) and exposed to different concentrations of Cu, Zn and MB for 144 h in a series of semi-static toxicity tests. The acute toxicity tests indicated that the 96-h median lethal concentration (LC50 ) values of the embryos and larvae were 1.71 and 0.22 mg l-1 for copper and 2.57 and 2.72 mg l-1 for zinc, respectively, whereas the MB LC50 after 144-h exposure for embryos and larvae were 67.88 and 17.81 mg l-1 , respectively. The safe concentrations of copper, zinc and MB were 0.17, 0.77 and 6.79 mg l-1 for embryos and 0.03, 0.03 and 1.78 mg l-1 for larvae, respectively. Copper, zinc and MB treatments with concentrations greater than 1.60, 2.00 and 60.00 mg l-1 , respectively, led to a significantly low hatching rate and significantly high embryo mortality (P < 0.05), and copper and MB treatments with concentrations greater than 0.2 and 20 mg l-1 led to significantly high larvae mortality (P < 0.05). Exposure to copper, zinc and MB resulted in developmental defects, including spinal curvature, tail deformity, vascular system anomalies and discolouration. Moreover, copper exposure significantly reduced the HR of larvae (P < 0.05). The embryos exhibited an obvious change in behaviour, converting from the normal behaviour of emerging from the membrane head first to emerging tail first, with probabilities of 34.82%, 14.81% and 49.07% under copper, zinc and MB treatments, respectively. The results demonstrated that the sensitivity of yolk-sac larvae to copper and MB was significantly higher than that of embryos (P < 0.05) and that B. tsinlingensis embryos or larvae might be more resistant to copper, zinc and MB than other members of the Salmonidae family, which benefits their resource protection and restoration.

Natural ocean iron fertilization and climate variability over geological periods.

Marine primary producers are largely dependent on and shape the Earth's climate, although their relationship with climate varies over space and time. The growth of phytoplankton and associated marine primary productivity in most of the modern global ocean is limited by the supply of nutrients, including the micronutrient iron. The addition of iron via episodic and frequent events drives the biological carbon pump and promotes the sequestration of atmospheric carbon dioxide (CO2 ) into the ocean. However, the dependence between iron and marine primary producers adaptively changes over different geological periods due to the variation in global climate and environment. In this review, we examined the role and importance of iron in modulating marine primary production during some specific geological periods, that is, the Great Oxidation Event (GOE) during the Huronian glaciation, the Snowball Earth Event during the Cryogenian, the glacial-interglacial cycles during the Pleistocene, and the period from the last glacial maximum to the late Holocene. Only the change trend of iron bioavailability and climate in the glacial-interglacial cycles is consistent with the Iron Hypothesis. During the GOE and the Snowball Earth periods, although the bioavailability of iron in the ocean and the climate changed dramatically, the changing trend of many factors contradicted the Iron Hypothesis. By detangling the relationship among marine primary productivity, iron availability and oceanic environments in different geological periods, this review can offer some new insights for evaluating the impact of ocean iron fertilization on removing CO2 from the atmosphere and regulating the climate.

[Effects of Combined Application of Different Nitrogen Fertilizers and Biochar on Cadmium Uptake by Pakchoi (Brassica chinensis L.) in Cadmium Contaminated Soil].

Nitrogen is an essential nutrient element for crop growth, and biochar is a good material for soil remediation. In this study, a pakchoi (Brassica chinensis L.) pot experiment was conducted to investigate the effects of the combined application of three nitrogen fertilizers, including urea, ammonium sulfate, calcium nitrate, and biochar on pakchoi growth and cadmium (Cd) uptake from cropland soil contaminated by Cd. The results showed that the application of nitrogen fertilizers and biochar prompted pakchoi growth, and the biomass of pakchoi in the treatments of single applications of urea, ammonium sulfate, calcium nitrate, and biochar were significantly increased by 5.02%-32.9%, as compared with that in the control treatment without nitrogen fertilizer application. The biomass of pakchoi in the treatments of the combined application of nitrogen fertilizers and biochar were significantly increased by 8.84%-50.8%, as compared with that in the treatment of the single application of nitrogen fertilizer. Compared with that under the control treatment without nitrogen fertilizer application, the single application of urea significantly reduced soil pH by 0.27 and significantly increased the content of soil available Cd by 30.0%. The single application of ammonium sulfate significantly reduced soil pH by 0.33 and significantly increased Cd content in pakchoi by 29.2%, as compared with that in the control treatment. The single application of calcium nitrate had no significant effect on soil pH or Cd content in pakchoi, whereas the single application of biochar significantly increased soil pH by 0.35 and significantly decreased the content of soil available Cd and content of Cd in pakchoi by 57.4% and 53.7%, respectively, as compared with that in the control treatment. Soil pH in the treatments of the combined application of nitrogen fertilizers and biochar was significantly increased by 0.14-0.28, the contents of soil available Cd were decreased by 16.5%-30.1%, and the contents of Cd in pakchoi were reduced by 15.3%-28.6%, as compared with that in the treatment of single application of nitrogen fertilizers. In general, the application of biochar could adjust the effects of different nitrogen fertilizers on Cd availability in the contaminated soil. During the remediation process of heavy metal-contaminated cropland, nitrogen fertilizer should be selected and applied reasonably to obtain the maximum economic and environmental benefits.

Combination of non-sterilized wastewater purification and high-level CO2 bio-capture with substantial biomass yield of an indigenous Chlorella strain.

The indigenous microalga Chlorella sorokiniana NBU-3 grown under air, 5 %, 15 %, and 25 % CO2 supply was evaluated to determine its potential for flue gas bio-capture, nutrient removal capacity and biomass yield using non-sterilized wastewater as growth medium. The results indicated that C. sorokiniana NBU-3 exhibited high nutrient removal efficiency (>95 % for NH4+-N, TN and TP) with either air or CO2 aeration. 5 %-15 % CO2 supplies promote biomass yield, nutrient utilization and CO2 biofixation of C. sorokiniana NBU-3. In particular, 15 % CO2 promotes C. sorokiniana NBU-3 growth in non-sterilized MW, but inhibits its growth in BG11 medium, indicating the importance of non-sterilized MW and high CO2 aeration concurrence for C. sorokiniana NBU-3 economically practical cultivation. Moreover, the highest values of lipid (27.84 ± 2.12 %) and protein (32.65 ± 4.11 %) contents were obtained in MW with 15 % CO2 aeration. Conceivably, microalgal-bacterial symbiosis may help C. sorokiniana NBU-3 tolerate high concentration of CO2 and promote microalga growth. The succession of the community diversity toward the specific functional bacterial species such as Methylobacillus and Methylophilus (Proteobacteria) which were predicted to possess the function of methylotroph, methanol oxidation and ureolysis would help facilitate the microalgal-bacterial symbiosis and promote the microalgae biomass accumulation with high dosage of CO2 aeration. Overall, these findings clearly highlight the potential of this indigenous microalga C. sorokiniana NBU-3 for industrial-emission level CO2 mitigation and commercial microalga biomass production in MW.

Diversity and Evolution of Iron Uptake Pathways in Marine Cyanobacteria from the Perspective of the Coastal Strain Synechococcus sp. Strain PCC 7002.

Marine cyanobacteria contribute to approximately half of the ocean primary production, and their biomass is limited by low iron (Fe) bioavailability in many regions of the open seas. The mechanisms by which marine cyanobacteria overcome Fe limitation remain unclear. In this study, multiple Fe uptake pathways have been identified in a coastal strain of Synechococcus sp. strain PCC 7002. A total of 49 mutants were obtained by gene knockout methods, and 10 mutants were found to have significantly decreased growth rates compared to the wild type (WT). The genes related to active Fe transport pathways such as TonB-dependent transporters and the synthesis and secretion of siderophores are found to be essential for the adaptation of Fe limitation in Synechococcus sp. PCC 7002. By comparing the Fe uptake pathways of this coastal strain with other open-ocean cyanobacterial strains, it can be concluded that the Fe uptake strategies from different cyanobacteria have a strong relationship with the Fe bioavailability in their habitats. The evolution and adaptation of cyanobacterial iron acquisition strategies with the change of iron environments from ancient oceans to modern oceans are discussed. This study provides new insights into the diversified strategies of marine cyanobacteria in different habitats from temporal and spatial scales. IMPORTANCE Iron (Fe) is an important limiting factor of marine primary productivity. Cyanobacteria, the oldest photosynthetic oxygen-evolving organisms on the earth, play crucial roles in marine primary productivity, especially in the oligotrophic ocean. How they overcome Fe limitation during the long-term evolution process has not been fully revealed. Fe uptake mechanisms of cyanobacteria have been partially studied in freshwater cyanobacteria but are largely unknown in marine cyanobacterial species. In this paper, the characteristics of Fe uptake mechanisms in a coastal model cyanobacterium, Synechococcus sp. PCC 7002, were studied. Furthermore, the relationship between Fe uptake strategies and Fe environments of cyanobacterial habitats has been revealed from temporal and spatial scales, which provides a good case for marine microorganisms adapting to changes in the marine environment.

Special roles for efflux systems in iron homeostasis of non-siderophore-producing cyanobacteria.

In oligotrophic oceans, low bioavailability of Fe is a key factor limiting primary productivity. However, excessive Fe in cells leads to the Fenton reaction, which is toxic to cells. Cyanobacteria must strictly maintain intracellular Fe homeostasis. Here, we knocked out a series of genes encoding efflux systems in Synechocystis sp. PCC 6803, and found eight genes that are required for high Fe detoxification. Unexpectedly, the HlyBD-TolC efflux system plays an important role in the adaptation of Synechocystis under Fe-deficient conditions. Mutants of HlyD and TolC grew worse than the wild-type strain under low-Fe conditions and showed significantly lower intracellular Fe contents than the wild-type strain. We excluded the possibility that the low Fe sensitivity of the HlyBD-TolC mutants was caused by a loss of the S-layer, the main extracellular protein secreted via this efflux system. Inactivation of the HlyD protein influenced type IV pili formation and direct inactivation of type IV pili related genes affected the adaptation to low-Fe conditions. HlyBD-TolC system is likely involved in the formation of type IV pili and indirectly influenced Fe acquisition. Our findings suggest that efflux system in non-siderophore-producing cyanobacteria can facilitate Fe uptake and help cells adapt to Fe-deficient conditions via novel pathways.

[Effects of reduced solar radiation on photosynthetic physiological characteristics and accumulation of secondary and micro elements in paddy rice.] / å¤ªé˜³è¾å°„å‡å¼±å¯¹æ°´ç¨»å ‰åˆç”Ÿç†ç‰¹æ€§å’Œä¸­å¾®é‡å ƒç´ ç§¯ç´¯çš„å½±å“.

Atmospheric haze pollution is a popular environmental issue in recent years. The aerosols reduce solar radiation reaching land surface, with consequences on the growth of crops. In order to examine the effects of low solar radiation intensity on the physiological characteristics and mineral nutrition of grain crops, the random designed field experiment of rice cultivar 'Nanjing 5055' planted under different shading degrees (CK, natural sunlight control; Y1 and Y2 were treatments with shading rates of 19% and 45%, respectively) were conducted. The response of chlorophyll content (SPAD), leaf area index (LAI), net photosynthetic rate of leaves, grain yields and secondary/micro element contents (Ca, Mg, Fe, Zn, Mn, Cu) in rice were measured during key growth stages (jointing, heading, and grain filling stages). Results showed that, shading treatments inhibited the synthesis of photosynthetic products and reduced the LAI during the whole growing period, but at the early stage it did not affect the chlorophyll content, which was significantly increased at the late growth stage. Compared with CK, the 1000-grain weight of rice was decreased by 14.4% and 18.4%, and seed setting rate was decreased by 4.3% and 12.9%, which resulted in rice yield reduction. With the increases of shading rates, rice yield was decreased by 58.5% and 66.4%, respectively. The nutrient concentrations, especially for the micro-elements, in brown rice and glume were increased. Shading had a negative effect on rice growth, which would eventually reduce the crop production. The higher contents of heavy metals such as Cu and Mn would be a pollution risk for human health. Therefore, the impacts of weakened solar radiation on quantity and quality of crops need comprehensive evaluation.

Prevalence and associated factors of HIV self-testing among men who have sex with men in Ningbo, China: a cross-sectional study.

BACKGROUND: HIV testing and early linkage to care are critical for reducing the risk of HIV transmission. HIV self-testing (HIVST) is a useful tool for increasing HIV testing frequency.This study aimed to investigate HIVST rates among men who have sex with men (MSM), the characteristics of MSM who had HIVST, and factors associated with HIVST uptake among MSM in Ningbo, China. METHODS: A cross-sectional study was conducted from April to October 2019 in Ningbo,China. Participants were aged at least 18 years and having had sexual contact with men in the past year. Proportions were used for categorical variables. Adjusted Odds Ratio (AOR) and 95% Confidence Interval (CI) for characteristics associated with HIVST uptake was processed by multivariable logistic regression models. RESULTS: Among a sample of 699 MSM recruited, 38.2% had reported previous use of an HIV self-test kit. A greater proportion of HIVST users had a higher frequency of HIV testing (≥ 2 times: 70.0% versus 41.2%, p < 0.001) in the past 1 year. The odds of older age (30-39 years: AOR = 0.49, CI 0.32-0.76; more than 40 years: AOR = 0.07, CI 0.04-0.14, compared to 18-29 years), bisexual (AOR = 0.49, CI 0.29-0.84) were lower among HIVST users,and were higher among MSM who were higher education level (high school: AOR = 2.82, CI 1.70-4.69, compared to middle school or less), gay apps use (AOR = 1.86, CI 1.13-3.05), multiple male sex partners (AOR = 1.90, CI 1.29-2.80), frequency of male-male sexual contact ≥ 1 times per week (AOR = 1.86, CI 1.30-2.66), syphilis infection (AOR = 5.48, CI 2.53-11.88). CONCLUSIONS: Further HIVST education should be strengthened for school-aged children and teenagers, and free HIVST kits may be provided to high-risk MSM through gay apps and CBO to achieve the increased HIV testing frequency.

A unique porin meditates iron-selective transport through cyanobacterial outer membranes.

Cyanobacteria are globally important primary producers and nitrogen fixers with high iron demands. Low ambient dissolved iron concentrations in many aquatic environments mean that these organisms must maintain sufficient and selective transport of iron into the cell. However, the nature of iron transport pathways through the cyanobacterial outer membrane remains obscure. Here we present multiple lines of experimental evidence that collectively support the existence of a novel class of substrate-selective iron porin, Slr1908, in the outer membrane of the cyanobacterium Synechocystis sp. PCC 6803. Elemental composition analysis and short-term iron uptake assays with mutants in Slr1908 reveal that this protein is primarily involved in inorganic iron uptake and contributes less to the accumulation of other metals. Homologues of Slr1908 are widely distributed in both freshwater and marine cyanobacteria, most notably in unicellular marine diazotrophs. Complementary experiments with a homologue of Slr1908 in Synechococcus sp. PCC 7002 restored the phenotype of Synechocystis knockdown mutants, showing that this siderophore producing species also possesses a porin with a similar function in Fe transport. The involvement of a substrate-selective porins in iron uptake may allow cyanobacteria to tightly control iron flux into the cell, particularly in environments where iron concentrations fluctuate.

Acclimation to low ultraviolet-B radiation increases photosystem I abundance and cyclic electron transfer with enhanced photosynthesis and growth in the cyanobacterium Nostoc sphaeroides.

Ultraviolet-B radiation is known to harm most photosynthetic organisms with the exception of several studies of photosynthetic eukaryotes in which UV-B showed positive effects. In this study, we investigated the effect of acclimation to low UV-B radiation on growth and photosynthesis of the cyanobacterium Nostoc sphaeroides. Exposure to 0.08 W m-2 UV-B plus low visible light for 14 d significantly increased the growth rate and biomass production by 16% and 30%, respectively, compared with those under visible light alone. The UV-B acclimated cells showed an approximately 50% increase in photosynthetic efficiency (α) and photosynthetic capacity (Pmax ), a higher PSI/PSII fluorescence ratio, an increase in PSI content and consequently enhanced cyclic electron flow, relative to those of non-acclimated cells. Both the primary quinone-type acceptor and plastoquinone pool re-oxidation were up-regulated in the UV-B acclimated cells. In parallel, the UV-B acclimated colonies maintained a higher rate of D1 protein synthesis following exposure to elevated intensity of UV-B or visible light, thus functionally mitigating photoinhibition. The present data provide novel insight into photosynthetic acclimation to low UV-B radiation and suggest that UV-B may act as a positive ecological factor for the productivity of some photosynthetic prokaryotes, especially during twilight periods or in shaded environments.

Downregulation of CKS1B restrains the proliferation, migration, invasion and angiogenesis of retinoblastoma cells through the MEK/ERK signaling pathway.

Retinoblastoma (RB) is a common neoplasm that is exhibited in individuals globally. Increasing evidence demonstrated that cyclin­dependent kinase regulatory subunit 1B (CKS1B) may be involved in the pathogenesis of various tumor types, including multiple myeloma and breast cancer. In the present study, the hypothesis that CKS1B downregulation would effectively inhibit the proliferation, invasion and angiogenesis of RB cells through the mitogen­activated protein kinase kinase (MEK)/extracellular signal­regulated kinase (ERK) signaling pathway was examined. Initial investigation of the expression profile of CKS1B in RB and adjacent retina tissues was performed using reverse transcription­quantitative polymerase chain reaction and western blot analysis. A total of three RB cell lines, SO­RB50, Y79 and HXO­RB44, were examined for selection of the cell line with the highest expression of CKS1B, and human normal retinal vascular endothelial cells (ACBRI­181) were also evaluated. CKS1B short hairpin RNA (shRNA) sequences (shRNA CKS1B­1, shRNA CKS1B­2 and shRNA CKS1B­3) and negative control shRNA sequences were constructed and transfected into cells at the third generation to evaluate the role of shCKS1B and the MEK/ERK signaling pathway in RB. Furthermore, the effect of shCKS1B on cell proliferation, migration, invasion, apoptosis and angiogenesis was investigated. CKS1B was determined to be highly expressed in RB tissue, compared with adjacent retina tissue. SO­RB50 and HXO­RB44 cells treated with shRNA CKS1B­1 and shRNA CKS1B­2 were selected for the present experiments. Activation of the MEK/ERK signaling pathway increases the expression of MEK, ERK, B­cell lymphoma 2, proliferating cell nuclear antigen, cyclin D1, vascular endothelia growth factor and basic fibroblast growth factor, enhances cell proliferation, migration, invasion and lumen formation, and decreases apoptosis. Following silencing CKS1B, the aforementioned conditions were reversed. The key observations of the present study demonstrated that shCKS1B can inhibit the proliferation, invasion and angiogenesis of RB cells by suppressing the MEK/ERK signaling pathway. Thus, CKS1B represents a potential research target in the development of therapeutics for RB.

Numerical analysis on the shear behavior of single-keyed dry joints in precast high-strength concrete segmental bridges.

The structural behavior of precast concrete segmental bridges (PCSBs) is affected by the joints between the concrete segments. In this study, a numerical model was established to investigate the direct shear behavior of single-keyed dry joints in PCSBs. The numerical model was validated by the full-scale test results published by the authors. It was found that the numerical results of the joints, such as the ultimate shear load, cracking pattern, and load-displacement curves, matched the test results well. The validated numerical model was further used for extending parametric studies. The factors affecting the shear behavior of single-keyed dry joints include the confining pressure, concrete strength, and key depth. It was found that the ultimate shear capacity increased about 121% when the confining pressure increased from 0.1 to 3.0 MPa, it was very low under confining pressure of 0.1 MPa; it increased about 44% when the concrete strength increased from C40 to C100; it increased about 203% when the key depth increased from 15 to 40 mm. However, the ultimate shear capacity decreased about 20% when the key depth increased from 40 to 60 mm, hence 40 mm was recommended for the design depth of the single-keyed dry joints in PCSBs. Finally, the parametric analysis results were compared with the AASHTO specification. When the key depth was 35, 40 and 45 mm, the AASHTO specification conservatively predict the shear strength capacity of single-keyed dry joints.

Genomic and transcriptomic insights into the survival of the subaerial cyanobacterium Nostoc flagelliforme in arid and exposed habitats.

The cyanobacterium Nostoc flagelliforme is an extremophile that thrives under extraordinary desiccation and ultraviolet (UV) radiation conditions. To investigate its survival strategies, we performed whole-genome sequencing of N. flagelliforme CCNUN1 and transcriptional profiling of its field populations upon rehydration in BG11 medium. The genome of N. flagelliforme is 10.23 Mb in size and contains 10 825 predicted protein-encoding genes, making it one of the largest complete genomes of cyanobacteria reported to date. Comparative genomics analysis among 20 cyanobacterial strains revealed that genes related to DNA replication, recombination and repair had disproportionately high contributions to the genome expansion. The ability of N. flagelliforme to thrive under extreme abiotic stresses is supported by the acquisition of genes involved in the protection of photosynthetic apparatus, the formation of monounsaturated fatty acids, responses to UV radiation, and a peculiar role of ornithine metabolism. Transcriptome analysis revealed a distinct acclimation strategy to rehydration, including the strong constitutive expression of genes encoding photosystem I assembly factors and the involvement of post-transcriptional control mechanisms of photosynthetic resuscitation. Our results provide insights into the adaptive mechanisms of subaerial cyanobacteria in their harsh habitats and have important implications to understand the evolutionary transition of cyanobacteria from aquatic environments to terrestrial ecosystems.

Mechanical thrombectomy using a Solitaire stent retriever in the treatment of pediatric acute ischemic stroke.

OBJECTIVE Mechanical thrombectomy using a Solitaire stent retriever has been widely applied as a safe and effective method in adult acute ischemic stroke (AIS). However, due to the lack of data, the safety and effectiveness of mechanical thrombectomy using a Solitaire stent in pediatric AIS has not yet been verified. The purpose of this study was to explore the safety and effectiveness of mechanical thrombectomy using a Solitaire stent retriever for pediatric AIS. METHODS Between January 2012 and December 2017, 7 cases of pediatric AIS were treated via mechanical thrombectomy using a Solitaire stent retriever. The clinical practice, imaging, and follow-up results were reviewed, and the data were summarized and analyzed. RESULTS The ages of the 7 patients ranged from 7 to 14 years with an average age of 11.1 years. The preoperative National Institutes of Health Stroke Scale (NIHSS) scores ranged from 9 to 22 with an average of 15.4 points. A Solitaire stent retriever was used in all patients, averaging 1.7 applications of thrombectomy and combined balloon dilation in 2 cases. Grade 3 on the modified Thrombolysis In Cerebral Infarction scale of recanalization was achieved in 5 cases and grade 2b in 2 cases. Six patients improved and 1 patient died after thrombectomy. The average NIHSS score of the 6 cases was 3.67 at discharge. The average modified Rankin Scale score was 1 at the 3-month follow-up. Subarachnoid hemorrhage after thrombectomy occurred in 1 case and that patient died 3 days postoperatively. CONCLUSIONS This study shows that mechanical thrombectomy using a Solitaire stent retriever has a high recanalization rate and excellent clinical prognosis in pediatric AIS. The safety of mechanical thrombectomy in pediatric AIS requires more clinical trials for confirmation. ABBREVIATIONS ACA = anterior cerebral artery; AIS = acute ischemic stroke; CTA = CT angiography; ICA = internal carotid artery; MCA = middle cerebral artery; mRS = modified Rankin Scale; mTICI = modified Thrombolysis In Cerebral Infarction; NIHSS = National Institutes of Health Stroke Scale; rt-PA = recombinant tissue plasminogen activator.

Outer Membrane Iron Uptake Pathways in the Model Cyanobacterium Synechocystis sp. Strain PCC 6803.

Cyanobacteria are foundational drivers of global nutrient cycling, with high intracellular iron (Fe) requirements. Fe is found at extremely low concentrations in aquatic systems, however, and the ways in which cyanobacteria take up Fe are largely unknown, especially the initial step in Fe transport across the outer membrane. Here, we identified one TonB protein and four TonB-dependent transporters (TBDTs) of the energy-requiring Fe acquisition system and six porins of the passive diffusion Fe uptake system in the model cyanobacterium Synechocystis sp. strain PCC 6803. The results experimentally demonstrated that TBDTs not only participated in organic ferri-siderophore uptake but also in inorganic free Fe (Fe') acquisition. 55Fe uptake rate measurements showed that a TBDT quadruple mutant acquired Fe at a lower rate than the wild type and lost nearly all ability to take up ferri-siderophores, indicating that TBDTs are critical for siderophore uptake. However, the mutant retained the ability to take up Fe' at 42% of the wild-type Fe' uptake rate, suggesting additional pathways of Fe' acquisition besides TBDTs, likely by porins. Mutations in four of the six porin-encoding genes produced a low-Fe-sensitive phenotype, while a mutation in all six genes was lethal to cell survival. These diverse outer membrane Fe uptake pathways reflect cyanobacterial evolution and adaptation under a range of Fe regimes across aquatic systems.IMPORTANCE Cyanobacteria are globally important primary producers and contribute about 25% of global CO2 fixation. Low Fe bioavailability in surface waters is thought to limit the primary productivity in as much as 40% of the global ocean. The Fe acquisition strategies that cyanobacteria have evolved to overcome Fe deficiency remain poorly characterized. We experimentally characterized the key players and the cooperative work mode of two Fe uptake pathways, including an active uptake pathway and a passive diffusion pathway in the model cyanobacterium Synechocystis sp. PCC 6803. Our finding proved that cyanobacteria use ferri-siderophore transporters to take up Fe', and they shed light on the adaptive mechanisms of cyanobacteria to cope with widespread Fe deficiency across aquatic environments.

Characterization of the sulfur-formation (suf) genes in Synechocystis sp. PCC 6803 under photoautotrophic and heterotrophic growth conditions.

MAIN CONCLUSION: The sulfur-formation ( suf ) genes play important roles in both photosynthesis and respiration of cyanobacteria, but the organism prioritizes Fe-S clusters for respiration at the expense of photosynthesis. Iron-sulfur (Fe-S) clusters are important to all living organisms, but their assembly mechanism is poorly understood in photosynthetic organisms. Unlike non-photosynthetic bacteria that rely on the iron-sulfur cluster system, Synechocystis sp. PCC 6803 uses the Sulfur-Formation (SUF) system as its major Fe-S cluster assembly pathway. The co-expression of suf genes and the direct interactions among SUF subunits indicate that Fe-S assembly is a complex process in which no suf genes can be knocked out completely. In this study, we developed a condition-controlled SUF Knockdown mutant by inserting the petE promoter, which is regulated by Cu2+ concentration, in front of the suf operon. Limited amount of the SUF system resulted in decreased chlorophyll contents and photosystem activities, and a lower PSI/PSII ratio. Unexpectedly, increased cyclic electron transport and a decreased dark respiration rate were only observed under photoautotrophic growth conditions. No visible effects on the phenotype of SUF Knockdown mutant were observed under heterotrophic culture conditions. The phylogenetic distribution of the SUF system indicates that it has a co-evolutionary relationship with photosynthetic energy storing pathways.

Effect of pyridone agent on blood-retinal barrier in diabetic mice.

AIM: To evaluate the therapeutic effect of fluorofenidone on disrupted blood-retinal barrier in the diabetic mice and uncover its underlying mechanism. METHODS: db/db mice were randomly chosen for treatment with daily doses of fluorofenidone or placebo at 5-week-old, treatment continued until mice reach 24-week-old. Then, expression of transcriptiona factor insulin gene enhancer binding protein-1 (Islet-1) and vascular endothelial growth factor (VEGF) in murine retinas were evaluated. Retinal vascular permeability was assessed by examining the level of albumin in db/db murine retinas. Furthermore, the retinal vessel tight junction was estimated by checking the level of occludin in the murine retinal tissues. RESULTS: After occurrence of diabetic retinopthy in db/db mice, expressions of transcritpional factor Islet-1 was found to be upregulated in db/db murine retinas compared with non-diabetic controls. Similar to expression pattern of Islet-1, VEGF were also demonstrated to be increased in retinas of db/db mice, which was accompanied by increased retinal vascular leakage and decreased tight junction protein level. Systemetic administration of fluorofenidone repaired broken retinal vascular tight junction by restoring occludin expression in db/db retinal tissue. Consequently, retinal vascular premeability were indicated to be reduced by examining the transudative albumin level in diabetic retinal tissues. Both Islet-1 and VEGF expression were inhibited in the retinas of db/db mice after treatment with fluorofenidone. CONCLUSION: Fluorofenidone significantly protectes retinal tight junction and reduces retinal vascular leakage. The phenomenon can be partially attributed to reducing overexpression of Islet-1 and VEGF in diabetic retinal tissues.

Comparison of Implantable Collamer Lens Visian ICL V4 and ICL V4c for high myopia: A cohort study.

The aim of this study was to investigate the visual quality of the 2 kinds of intraocular lens: Visian implantable collamer lens (ICL) V4 and Visian ICL V4c implantations for high myopia.Twenty cases (20 eyes) with high myopia who received Visian ICL V4 implantation and 18 cases (18 eyes) with high myopia who received Visian ICL V4c implantation in our hospital from April 1, 2014 to November 31, 2016 were enrolled. In 1-month follow-up, near vision, best corrected distant visual acuity (BCVA), uncorrected distant visual acuity (UDVA), and wavefront aberrations were measured, and compensation factor was calculated.Near vision, UDVA, and BCVA showed no significant difference between ICL V4 implantation and ICL V4c implantation (P >.05). However, high-order aberrations and spherical aberrations were higher in ICL V4c implantation than in ICL V4 implantation (P <.05). Low-order aberrations (defocus and astigmatism), coma, and subjective visual quality had no significant difference between ICL V4 implantation and ICL V4c implantation (P >.05).The 2 kinds of ICL Visian ICL V4 and Visian ICL V4c had similar efficacy of visual quality for high myopia. The presence of the central hole of Visian ICL V4c has no significant effect on visual quality.