Chromosomal instability in Streptomyces avermitilis: major deletion in the central region and stable circularized chromosome

<p>Abstract</p> <p>Background</p> <p>The chromosome of <it>Streptomyces </it>has been shown to be unstable, frequently undergoing gross chromosomal rearrangements. However, the mechanisms underlying this phenomenon remain unclear, with previous studies focused on two chromosomal ends as targets for rearrangements. Here we investigated chromosomal instability of <it>Streptomyces avermitilis</it>, an important producer of avermectins, and characterized four gross chromosomal rearrangement events, including a major deletion in the central region. The present findings provide a valuable contribution to the mechanistic study of genetic instability in <it>Streptomyces</it>.</p> <p>Results</p> <p>Thirty randomly-selected "bald" mutants derived from the wild-type strain all contained gross chromosomal rearrangements of various types. One of the bald mutants, SA1-8, had the same linear chromosomal structure as the high avermectin-producing mutant 76-9. Chromosomes of both strains displayed at least three independent chromosomal rearrangements, including chromosomal arm replacement to form new 88-kb terminal inverted repeats (TIRs), and two major deletions. One of the deletions eliminated the 36-kb central region of the chromosome, but surprisingly did not affect viability of the cells. The other deletion (74-kb) was internal to the right chromosomal arm. The chromosome of another bald mutant, SA1-6, was circularized with deletions at both ends. No obvious homology was found in all fusion sequences. Generational stability analysis showed that the chromosomal structure of SA1-8 and SA1-6 was stable.</p> <p>Conclusions</p> <p>Various chromosomal rearrangements, including chromosomal arm replacement, interstitial deletions and chromosomal circularization, occurred in <it>S. avermitilis </it>by non-homologous recombination. The finding of an inner deletion involving in the central region of <it>S. avermitilis </it>chromosome suggests that the entire <it>Streptomyces </it>chromosome may be the target for rearrangements, which are not limited, as previously reported, to the two chromosomal ends.</p

α-Lys424 Participates in Insertion of FeMoco to MoFe Protein and Maintains Nitrogenase Activity in Klebsiella oxytoca M5al

Our previous investigation of substrates reduction catalyzed by nitrogenase suggested that α-Ile423 of MoFe protein possibly functions as an electron transfer gate to Mo site of active center-“FeMoco”. Amino acid residue α-Lys424 connects directly to α-Ile423, and they are located in the same α-helix (α423-431). In the present study, function of α-Lys424 was investigated by replacing it with Arg (alkaline, like Lys), Gln (neutral), Glu (acidic), and Ala (neutral) through site-directed mutagenesis and homologous recombination. The mutants were, respectively, termed 424R, 424Q, 424E, and 424A. Studies of diazotrophic cell growth, cytological, and enzymatic properties indicated that none of the substitutions altered the secondary structure of MoFe protein, or normal expression of nifA, nifL, and nifD. Substitution of alkaline amino acid (i.e., 424R) maintained acetylene (C2H2) and proton (H+) reduction activities at normal levels similar to that of wild-type (WT), because its FeMoco content did not reduce. In contrast, substitution of acidic or neutral amino acid (i.e., 424Q, 424E, 424A) impaired the catalytic activity of nitrogenase to varying degrees. Combination of MoFe protein structural simulation and the results of a series of experiments, the function of α-Lys424 in ensuring insertion of FeMoco to MoFe protein was further confirmed, and the contribution of α-Lys424 in maintaining low potential of the microenvironment causing efficient catalytic activity of nitrogenase was demonstrated

Графический дизайн как визуальный язык межкультурного взаимодействия

This article describes how visual graphics language as a sign system can be in contact with the audience, overcoming the language barrier. In terms of graphic design it can be available to transfer information, and even affect the viewer, causing artistic and emotional reflection.Эта статья о том, как визуальный язык графики в виде знаковой символики может входить в контакт со зрителем, преодолевая языковый барьер. На языке графического дизайна можно доступно передать информацию и даже воздействовать на зрителя, вызывая при этом художественно-эмоциональные образы

Population response of intestinal microbiota to acute Vibrio alginolyticus infection in half-smooth tongue sole (Cynoglossus semilaevis)

IntroductionVibriosis causes enormous economic losses of marine fish. The present study investigated the intestinal microbial response to acute infection of half-smooth tongue sole with different-dose Vibrio alginolyticus within 72 h by metagenomic sequencing.MethodsThe inoculation amount of V. alginolyticus for the control, low-dose, moderate-dose, and high-dose groups were 0, 8.5 × 101, 8.5 × 104, and 8.5 × 107 cells/g respectively, the infected fish were farmed in an automatic seawater circulation system under a relatively stable temperature, dissolved oxygen and photoperiod, and 3 ~ 6 intestinal samples per group with high-quality DNA assay were used for metagenomics analysis.ResultsThe acute infections with V. alginolyticus at high, medium, and low doses caused the change of different-type leukocytes at 24 h, whereas the joint action of monocytes and neutrophils to cope with the pathogen infection only occurred in the high-dose group at 72 h. The metagenomic results suggest that a high-dose V. alginolyticus infection can significantly alter the intestinal microbiota, decrease the microbial α-diversity, and increase the bacteria from Vibrio and Shewanella, including various potential pathogens at 24 h. High-abundance species of potential pathogens such as V. harveyii, V. parahaemolyticus, V. cholerae, V. vulnificus, and V. scophthalmi exhibited significant positive correlations with V. alginolyticus. The function analysis revealed that the high-dose inflection group could increase the genes closely related to pathogen infection, involved in cell motility, cell wall/ membrane/envelope biogenesis, material transport and metabolism, and the pathways of quorum sensing, biofilm formation, flagellar assembly, bacterial chemotaxis, virulence factors and antibiotic resistances mainly from Vibrios within 72 h.DiscussionIt indicates that the half-smooth tongue sole is highly likely to be a secondary infection with intestinal potential pathogens, especially species from Vibrio and that the disease could become even more complicated because of the accumulation and transfer of antibiotic-resistance genes in intestinal bacteria during the process of V. alginolyticus intensified infection

Analysis of signal-to-noise ratio retrieved from multi-GNSS satellite data of land surface reflections

The reflection of Global Navigation Satellite System (GNSS) signals, known as GNSS reflectometry (GNSS-R), has made significant progress in monitoring ocean and land surface geophysical parameters. The main purpose of this investigation is to analyze the impact of antenna gain, land surface properties, and coherent integration time on the signal-to-noise ratio (SNR) of multi-GNSS reflected signals using complex waveform (CW) products generated by the Cyclone Global Navigation Satellite System (CYGNSS) constellation recording multi-GNSS raw intermediate frequency (IF) data. For different GNSS constellations, CYGNSS antenna gain of 6–9 dB can achieve an SNR of 0 dB or more over most pan-tropical regions. The normalized SNR (NSNR) calculated by the calibration procedure is used for such analysis. The results show that the coherent reflection caused the largest NSNR by the inland water body, and NSNR from the GPS reflected signal is about 2 dB and 4 dB larger than Galileo and BDS, respectively, whereas the dense vegetation caused a strong attenuation of the reflected signal and resulted in the smallest NSNR. Different GNSS systems have similar sensitivity to roughness coefficient (RC). In contrast, different GNSS constellations exhibit different sensitivities for moderate soil moisture (SM), the NSNR increases for GPS, BDS, and Galileo are estimated by linear fitting to be 4.85 dB, 7.67 dB, and 8.73 dB, respectively. NSNR gradually increases with above-ground biomass (AGB) when AGB is less than 100 Mg/ha, which seems to be the threshold for signals to penetrate the sparse vegetation and sense SM under the vegetation. However, when AGB is greater than 100 Mg/ha, the opposite is true. Furthermore, NSNR can be improved by longer coherent integration time, the average improvement in NSNR is about 1.5 dB with 2 ms coherent integration time and approximately 3 dB with 4 ms coherent integration time.This work was funded by the National Natural Science Foundation of China (No. 42074041); Shaanxi Province Science and Technology Innovation Team (Ref. 2021TD-51) and the Shaanxi Province Geoscience Big Data and Geohazard Prevention Innovation Team (2022); National Key Research and Development Program of China (No. 2020YFC1512000); and Fundamental Research Funds for the Central Universities, Chang’an University (No. 300102262401). This work of Weiqiang LI is partially supported by Grant RYC2019-027000-I funded by MCIN/AEI/http://dx.doi.org/10.13039/501100011033 and by “European Union Next Generation EU/PRTR,” as is also supported by Grant 20215AT007 funded by Spanish National Research Council. Qi Liu's work was partly supported by the China Scholarship Council (CSC) through a State Scholarship Fund (No. 202106560048).Peer reviewe

MOESM1 of A new method for noninvasive venous blood oxygen detection

Additional file 1: Raw Data

Degradation of Tetracycline in Water by Fe-Modified Sterculia Foetida Biochar Activated Peroxodisulfate

Tetracycline (TC) is a broad-spectrum antibiotic commonly, made use of in aquaculture and animal husbandry. After entering water bodies, it will represent a major threat to human health. In this study, sterculia foetida biochar (SFC) was readied by the combined hydrothermal pyrolysis (co-HTP) method with sterculia foetida as raw materials. Fen-SFC (Fe2-SFC, Fe3-SFC, and Fe4-SFC) was obtained by doping SFH with different concentrations of FeCl3. Finally, activation of peroxodisulfate (PDS) was achieved, using Fe3-SFC to degrade TC. The degradation of TC obeyed pseudo-second-order kinetics, and the constant of the reaction rate was 0.491 L mg&minus;1 min&minus;1. Radical trapping experiments, EPR test and electrochemical tests evidenced that the high catalytic performance of the Fe3-SFC/PDS system was ascribed to free radical pathway (&bull;OH and SO4&bull;&minus;) and non-radical pathway (1O2 and electron transfer), in which the latter plays a dominant role. This research not only demonstrates a new kind of biochar as an effective catalyst for PS activation, but also offers an avenue for the value-added reuse of sterculia foetida

Using Robust Regression to Retrieve Soil Moisture from CyGNSS Data

Accurate global soil moisture (SM) data are crucial for modeling land surface hydrological cycles and monitoring climate change. Spaceborne global navigation satellite system reflectometry (GNSS-R) has attracted extensive attention due to its unique advantages, such as faster revisit time, lower payload costs, and all-weather operation. GNSS signal reflected at L-band also has significant advantages for SM estimation. Usually, SM is estimated based on the sensitivity of GNSS-R reflectivity to SM, but the noise in observations can significantly impact SM estimation results. A new SM retrieval method based on robust regression is proposed to address this issue in this work, and the effects of roughness and vegetation on the effective reflectivity of the Cyclone Global Navigation Satellite System (CyGNSS) are reconsidered. Ancillary data are provided by the SM Active Passive (SMAP) mission. The retrieved results from the training sets and test sets agree well with the referenced SMAP SM data. The correlation coefficient R is 0.93, the root mean square error (RMSE) is 0.058 cm3cm&minus;3, the unbiased RMSE (ubRMSE) is 0.042 cm3cm&minus;3, and the mean absolute error (MAE) is 0.040 cm3cm&minus;3 in the training sets. For the test, the correlation coefficient is 0.91, the RMSE is 0.067 cm3cm&minus;3, the ubRMSE is 0.051 cm3cm&minus;3, and the MAE is 0.044 cm3cm&minus;3. The proposed method has been evaluated using in situ measurements from the SMAP/in situ core validation site; in situ measurements and retrieval results exhibit good consistency with the ubRMSE value below 0.35 cm3cm&minus;3. Moreover, the SM retrieval results using robust regression methods show better performance than CyGNSS official SM products that use linear regression. In addition, the land cover types significantly affect the accuracy of SM retrieval, and the incoherent scattering in densely vegetated areas (tropical forests) usually leads to more errors