Produced by cyanobacteria and some plants, BMAA is considered as an important environmental factor in the occurrence of some neurodegenerative diseases. Neither the underlying mechanism of its ...toxicity, nor its biosynthetic or metabolic pathway in cyanobacteria is understood. Interestingly, BMAA is found to be toxic to some cyanobacteria, making it possible to dissect the mechanism of BMAA metabolism by genetic approaches using these organisms. In this study, we used the cyanobacterium
PCC 7120 to isolate BMAA-resistant mutants. Following genomic sequencing, several mutations were mapped to two genes involved in amino acids transport, suggesting that BMAA was taken up through amino acid transporters. This conclusion was supported by the protective effect of several amino acids against BMAA toxicity. Furthermore, targeted inactivation of genes encoding different amino acid transport pathways conferred various levels of resistance to BMAA. One mutant inactivating all three major amino acid transport systems could no longer take up BMAA and gained full resistance to BMAA toxicity. Therefore, BMAA is a substrate of amino acid transporters, and cyanobacteria are interesting models for genetic analysis of BMAA transport and metabolism.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Paranemachilus genilepis (Zhu 1983) is a small and benthic loach species that mainly distributes in the Guangxi Province, China. To date, little was known about the genetic information of this ...species as no molecular sequence has been published. In this study, the complete mitochondrial genome of P. genilepis was reported using the Illumina MiSeq platform. The genome was 16,563 base pairs (bp) in length and its structure was identical to most genomes of bony fishes. Phylogenetic analyses supported two clades (I and II) among Nemacheilidae species and P. genilepis was sister to Oreonectes furcocaudalis.
β-N-methylamino-L-alanine (BMAA) is an environmental neurotoxin thought to be produced by cyanobacteria. However, the cyanobacterial origin of BMAA remains controversial. The detection method and ...culture conditions of cyanobacteria are often cited as factors behind the discrepancy of published results. We showed previously that BMAA was highly toxic to the cyanobacterium Nostoc PCC 7120, and it is taken up via an amino acid transport system. Using a mutant ΔnatAΔbgtA deficient in amino acid transport as a genetic control, we show here that BMAA taken up from the medium can be detected quantitatively at a threshold similar to, or below those reported, but was undetectable in the mutant. The BMAA isomer, 2,4-diaminobutanoic acids (DAB), but not BMAA, could be detected in cell free extracts of Nostoc PCC 7120. Long-term (20 days) diazotrophic growth or non-limiting supply of phosphate, conditions reported to enhance BMAA synthesis, did not lead to the detection of BMAA. An UPLC-MS/MS signal with a similar retention time to BMAA was found after prolonged diazotrophic incubation, but did not have fragment ions of BMAA after further analysis. When extended to 29 different cyanobacterial strains and 6 natural cyanobacterial bloom samples, none of them was found to produce BMAA. The cytotoxicity of BMAA to cyanobacteria, and the lack of a cellular protective mechanism against such toxicity, contradict the presence of a BMAA synthesis pathway in these organisms. More specific methods for BMAA detection in vivo need to be developed to clarify the cyanobacterial origin of BMAA.
•Contradictory results have been published on β-N-methylamino-L-alanine (BMAA) production by cyanobacteria.•Detection techniques and culture conditions were often cited as reasons for such discrepancy.•Based on a genetic approach, we validated our detection system, but no free BMAA was found in cyanobacteria.•Single ion chromatograms must be shown in order to distinguish BMAA from its isomer DAB for future detection of BMAA.•Our results should help the community to clarify the controversial issue.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background:
Meteorological factors can affect the emergence of scrub typhus for a period lasting days to weeks after their occurrence. Furthermore, the relationship between meteorological factors and ...scrub typhus is complicated because of lagged and non-linear patterns. Investigating the lagged correlation patterns between meteorological variables and scrub typhus may promote an understanding of this association and be beneficial for preventing disease outbreaks.
Methods
We extracted data on scrub typhus cases in rural areas of Panzhihua in Southwest China every week from 2008 to 2017 from the China Information System for Disease Control and Prevention. The distributed lag non-linear model (DLNM) was used to study the temporal lagged correlation between weekly meteorological factors and weekly scrub typhus.
Results
There were obvious lagged associations between some weather factors (rainfall, relative humidity, and air temperature) and scrub typhus with the same overall effect trend, an inverse-U shape; moreover, different meteorological factors had different significant delayed contributions compared with reference values in many cases. In addition, at the same lag time, the relative risk increased with the increase of exposure level for all weather variables when presenting a positive association.
Conclusions
The results found that different meteorological factors have different patterns and magnitudes for the lagged correlation between weather factors and scrub typhus. The lag shape and association for meteorological information is applicable for developing an early warning system for scrub typhus.
To assess the potential cytostatic properties of the thulium(III)-arsenazo III complex as a probe of rare earth complex antitumor drugs, the interaction information of the thulium(III)-arsenazo III ...complex with DNA was obtained by using spectroscopy, viscosity measurements, and voltammetric methods. The thermodynamic functions demonstrated that the binding constants of the thulium(III)-arsenazo III complex with DNA were Kθ298.15K = 4.84 × 106 L·mol−1 and Kθ308.15K = 4.48 × 106 L·mol−1, and the binding process was enthalpy driven. The increase in relative viscosity of DNA with the addition of the thulium(III)-arsenazo III complex and the results from Scatchard and voltammetric methods showed that the interaction mode between the thulium(III)-arsenazo III complex and DNA was groove binding along with weak intercalative binding.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
An ultrasound-assisted convenient method was developed for the synthesis of battery grade potassium ferrate (K
2FeO
4) with high yield (53–59%). The purity of the synthesized salt was determined by ...chromite method to be 95–96.8%. It was found that sample of the solid potassium ferrate has a tetrahedral structure with a space group of
D
2h
(Pnma) from X-ray diffraction (XRD) spectrum. From the scanning electronic microscopy (SEM), the K
2FeO
4 powders were crystallized polyhedron-shaped stick, and the particles had dimensions on the order of 25–200
μm in length and 1–10
μm in width. The electrochemical performance of the K
2FeO
4 electrodes was studied by using cyclic voltammetry and galvanostatic discharge methods in 10
mol/L KOH aqueous electrolyte. The synthesized product possesses a capacity of 302.4
mAh/g and coulombic efficiency of 74.5%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We report measurements of picosecond dynamics of individual nickel nanomagnets as a function of magnet dimension, aspect ratio, and magnetic environment. Spatial sensitivity to nanomagnet diameters ...as small as 125 nm is achieved by use of cavity enhancement of the magneto-optic Kerr effect (CE-MOKE). The importance of single-particle measurements without ensemble effects for extracting the size dependence of the intrinsic nanomagnet material properties is demonstrated.
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IJS, KILJ, NUK, PNG, UL, UM
The stability of potassium ferrate(VI) (K
2FeO
4) electrodes was dramatically improved by using 2,3-Naphthalocyanine (C
48H
26N
8) as coating. The electrode material with the coating was ...characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). K
2FeO
4 electrodes coated with 2,3-Naphthalocyanine provided a superior capacity and stability to uncoated K
2FeO
4 electrodes. Cathodic charge capacity of K
2FeO
4 coated with 2,3-Naphthalocyanine is 42% higher than that of K
2FeO
4 uncoated when discharged at rate of 0.25 C to a cutoff of 0.8
V after storing in the 10
mol/L KOH solution for 3
h.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The detection of miRNA in cells is difficult owing to its substantially low cellular content. Therefore, developing a highly sensitive sensor to detect cellular miRNA remains a significant challenge. ...Herein, we report an enzyme-assisted biosensor with target cycle amplification that can trigger the unlocking of locked hairpin probes for sensitive and robust let-7a gene detection. In the research, three kinds of hairpin probes were skillfully designed. The hairpin probe comprises a complementary sequence of a target, primer, and recognition site of Nt. BbvCI restriction endonucleases. In addition, the alternating synergistic impact of polymerase and the nicking enzyme generates considerable triggers to unlock the locked hairpin probe LH1, consequently triggering a subsequent circulating strand displacement reaction to form a stable H1–H2 double strand to ensure sufficient distance between a fluorophore on H1 and a quenching group on bolt DNA (bDNA), and resulting in the recovery of fluorescence. Furthermore, this process does not require complicated operation procedures and instruments, and the target gene let-7a can be sensitively detected. Specifically, the detection limit of the biosensor is as low as 160 fM, and its linear range is 0.5 pM–250 nM. Moreover, this biosensor can be employed to detect let-7a in human serum with good selectivity.
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•An enzyme-assisted fluorescent sensing system was proposed for the detection of the miRNA Let-7a.•The sensitivity of miRNA Let-7a fluorescence detection was further enhanced by target cyclic amplification.•Ultrasensitive enzyme-assisted fluorescent detection limit of Let-7a was estimated to be as low as 160 fM.•The biosensor has good specificity and excellent detection capabilities in a complex substrate environment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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