Reduced Growth Rate Research Articles

Bacteria can compensate the fitness costs of amplified resistance genes via a bypass mechanism

Antibiotic heteroresistance is a phenotype in which a susceptible bacterial population includes a small subpopulation of cells that are more resistant than the main population. Such resistance can arise by tandem amplification of DNA regions containing resistance genes that in single copy are not sufficient to confer resistance. However, tandem amplifications often carry fitness costs, manifested as reduced growth rates. Here, we investigated if and how these fitness costs can be genetically ameliorated. We evolved four clinical isolates of three bacterial species that show heteroresistance to tobramycin, gentamicin and tetracyclines at increasing antibiotic concentrations above the minimal inhibitory concentration (MIC) of the main susceptible population. This led to a rapid enrichment of resistant cells with up to an 80-fold increase in the resistance gene copy number, an increased MIC, and severely reduced growth rates. When further evolved in the presence of antibiotic, these strains acquired compensatory resistance mutations and showed a reduction in copy number while maintaining high-level resistance. A deterministic model indicated that the loss of amplified units was driven mainly by their fitness costs and that the compensatory mutations did not affect the loss rate of the gene amplifications. Our findings suggest that heteroresistance mediated by copy number changes can facilitate and precede the evolution towards stable resistance.

Analyzing sustainable development in Chinese cities: A focus on land use efficiency in production-living-ecological aspects

Efficient utilization of land resources is fundamental for achieving sustainable urban development. Utilizing the urban land use efficiency (ULUE) framework for production-living-ecological (PLE) functions, this study establishes three key indicators to evaluate the sustainable development status of each dimension. The indicator system was applied to 433 Chinese cities to analyze the temporal and spatial changes in urban sustainable development from 2000 to 2020. Research findings reveal significant disparities in sustainable urban development levels across Chinese regions from 2000 to 2020, following a consistent trend: Eastern > Western > Central > Northeast. The ULUE for living and production functions in Chinese cities experienced an obvious decline from 2015 to 2020. This indicates that urban land expansion in most Chinese cities surpassed population growth, accompanied by a noticeable reduction in economic growth rates. Since 2010, the ULUE for ecological function has improved significantly in Eastern region, reflecting a shift in development priorities towards a green approach rooted in ecological conservation principles. However, the ULUE in Northeastern cities has declined, placing this region at a competitive disadvantage due to the dual challenges of declining population and economic recession. Since 2015, urban land expansion in Central Chinese cities has significantly outpaced other regions, resulting in extensive land use, posing challenges to resource planning and management. Smaller cities, in contrast to their larger counterparts, face a lower overall sustainability level and encounter more acute challenges related to population migration and economic transition. The analysis offers valuable insights and policy recommendations to enhance sustainability in developing regions.

Effects of Face Mask Mandates on COVID-19 Transmission in 51 Countries: Retrospective Event Study.

The question of the utility of face masks in preventing acute respiratory infections has received renewed attention during the COVID-19 pandemic. However, given the inconclusive evidence from existing randomized controlled trials, evidence based on real-world data with high external validity is missing. To add real-world evidence, this study aims to examine whether mask mandates in 51 countries and mask recommendations in 10 countries increased self-reported face mask use and reduced SARS-CoV-2 reproduction numbers and COVID-19 case growth rates. We applied an event study approach to data pooled from four sources: (1) country-level information on self-reported mask use was obtained from the COVID-19 Trends and Impact Survey, (2) data from the Oxford COVID-19 Government Response Tracker provided information on face mask mandates and recommendations and any other nonpharmacological interventions implemented, (3) mobility indicators from Google's Community Mobility Reports were also included, and (4) SARS-CoV-2 reproduction numbers and COVID-19 case growth rates were retrieved from the Our World in Data-COVID-19 data set. Mandates increased mask use by 8.81 percentage points (P=.006) on average, and SARS-CoV-2 reproduction numbers declined on average by -0.31 units (P=.008). Although no significant average effect of mask mandates was observed for growth rates of COVID-19 cases (-0.98 percentage points; P=.56), the results indicate incremental effects on days 26 (-1.76 percentage points; P=.04), 27 (-1.89 percentage points; P=.05), 29 (-1.78 percentage points; P=.04), and 30 (-2.14 percentage points; P=.02) after mandate implementation. For self-reported face mask use and reproduction numbers, incremental effects are seen 6 and 13 days after mandate implementation. Both incremental effects persist for >30 days. Furthermore, mask recommendations increased self-reported mask use on average (5.84 percentage points; P<.001). However, there were no effects of recommendations on SARS-CoV-2 reproduction numbers or COVID-19 case growth rates (-0.06 units; P=.70 and -2.45 percentage points; P=.59). Single incremental effects on self-reported mask use were observed on days 11 (3.96 percentage points; P=.04), 13 (3.77 percentage points; P=.04) and 25 to 27 (4.20 percentage points; P=.048 and 5.91 percentage points; P=.01) after recommendation. Recommendations also affected reproduction numbers on days 0 (-0.07 units; P=.03) and 1 (-0.07 units; P=.03) and between days 21 (-0.09 units; P=.04) and 28 (-0.11 units; P=.05) and case growth rates between days 1 and 4 (-1.60 percentage points; P=.03 and -2.19 percentage points; P=.03) and on day 23 (-2.83 percentage points; P=.05) after publication. Contrary to recommendations, mask mandates can be used as an effective measure to reduce SARS-CoV-2 reproduction numbers. However, mandates alone are not sufficient to reduce growth rates of COVID-19 cases. Our study adds external validity to the existing randomized controlled trials on the effectiveness of face masks to reduce the spread of SARS-CoV-2.

Restricted glycolysis is a primary cause of the reduced growth rate of zinc-deficient yeast cells

Zinc is required for many critical processes, including intermediary metabolism. In Saccharomyces cerevisiae, the Zap1 activator regulates the transcription of ∼80 genes in response to Zn supply. Some Zap1-regulated genes are Zn transporters that maintain Zn homeostasis, while others mediate adaptive responses that enhance fitness. One adaptive response gene encodes the 2-cysteine peroxiredoxin Tsa1, which is critical to Zn-deficient (ZnD) growth. Depending on its redox state, Tsa1 can function as a peroxidase, a protein chaperone, or a regulatory redox sensor. In a screen for possible Tsa1 regulatory targets, we identified a mutation (cdc19S492A) that partially suppressed the tsa1Δ growth defect. The cdc19S492A mutation reduced activity of its protein product, pyruvate kinase isozyme 1 (Pyk1), implicating Tsa1 in adapting glycolysis to ZnD conditions. Glycolysis requires activity of the Zn-dependent enzyme fructose-bisphosphate aldolase 1, which was substantially decreased in ZnD cells. We hypothesized that in ZnD tsa1Δ cells, the loss of a compensatory Tsa1 regulatory function causes depletion of glycolytic intermediates and restricts dependent amino acid synthesis pathways, and that the decreased activity of Pyk1S492A counteracted this depletion by slowing the irreversible conversion of phosphoenolpyruvate to pyruvate. In support of this model, supplementing ZnD tsa1Δ cells with aromatic amino acids improved their growth. Phosphoenolpyruvate supplementation, in contrast, had a much greater effect on growth rate of WT and tsa1Δ ZnD cells, indicating that inefficient glycolysis is a major factor limiting yeast growth. Surprisingly however, this restriction was not primarily due to low fructose-bisphosphate aldolase 1 activity, but instead occurs earlier in glycolysis.

Sesquiterpenes of the ectomycorrhizal fungus Pisolithus microcarpus alter root growth and promote host colonization

Trees form symbioses with ectomycorrhizal (ECM) fungi, maintained in part through mutual benefit to both organisms. Our understanding of the signaling events leading to the successful interaction between the two partners requires further study. This is especially true for understanding the role of volatile signals produced by ECM fungi. Terpenoids are a predominant class of volatiles produced by ECM fungi. While several ECM genomes are enriched in the enzymes responsible for the production of these volatiles (i.e., terpene synthases (TPSs)) when compared to other fungi, we have limited understanding of the biochemical products associated with each enzyme and the physiological impact of specific terpenes on plant growth. Using a combination of phylogenetic analyses, RNA sequencing, and functional characterization of five TPSs from two distantly related ECM fungi (Laccaria bicolor and Pisolithus microcarpus), we investigated the role of these secondary metabolites during the establishment of symbiosis. We found that despite phylogenetic divergence, these TPSs produced very similar terpene profiles. We focused on the role of P. microcarpus terpenes and found that the fungus expressed a diverse array of mono-, di-, and sesquiterpenes prior to contact with the host. However, these metabolites were repressed following physical contact with the host Eucalyptus grandis. Exposure of E. grandis to heterologously produced terpenes (enriched primarily in γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma$$\\end{document}-cadinene) led to a reduction in the root growth rate and an increase in P. microcarpus–colonized root tips. These results support a very early putative role of fungal-produced terpenes in the establishment of symbiosis between mycorrhizal fungi and their hosts.

Performance of seedlings and yield of soybean genotypes under soil compaction

AbstractThe identification of soybean genotypes tolerant to soil compaction makes it possible to reduce productivity loss under stress conditions. Added to this, the prior selection of these genotypes will result in greater assertiveness in the positioning of cultivars in the field. Thus, the objective was to evaluate the susceptibility of soybean genotypes to compaction in greenhouse and field conditions; verify which characteristics of seedlings under high resistance to root penetration are correlated with crop production in compacted soil; and to validate the substrate mechanical impedance method for evaluating the susceptibility of plant genotypes to soil compaction. Seeds of 20 genotypes were sown in a substrate mechanical impedance system under controlled conditions. The characteristics evaluated were total root length, total root surface area, mean root diameter, total root volume, taproot length, shoot length, root dry matter and seedling shoot dry matter. In the field experiment, half of the planting area was compacted, constituting two treatments, soil with and without compaction. The percentage of seedling emergence, initial plant height, stem diameter, number of nodes, internode length, number of lateral branches, shoot dry matter, final plant height, absolute and relative growth rate, number of pods, weight of 100 seeds and grain yield. In addition, the number of days between soybean sowing until plant flowering and grain harvest was recorded according to genotype and soil compaction level. In a controlled environment, genotypes tolerant to soil compaction show greater plasticity of root characteristics and smaller alterations in the shoot of seedlings. In the field, these genotypes show smaller reductions in growth rate, height, number of pods and grain yield. The shoot dry matter and the root dry matter of soybean seedlings in a mechanical impedance system present a positive and negative correlation, respectively, with soybean yield in compacted soil, indicating that the genetically determined susceptibility to soil compaction stress was similar throughout ontogenesis. The substrate mechanical impedance system used to evaluate the performance of soybean seedlings under stress, facilitates the decision‐making in breeding programs focused on identifying genotypes expressing soil compaction tolerance.

Improved shear property of Sn-3.0Ag-0.5Cu/Ni micro solder joints under thermal shock between 77 K and 423 K by adding TiO2 nanoparticles

The rapid development of space exploration technology was intensifying the desire for lead-free solders with high performance and reliability under extreme temperature environments. In this study, the influence of TiO2 nanoparticle addition on the microstructure, growth behavior of interfacial intermetallic compounds (IMCs) and shear property of Sn-3.0Ag-0.5Cu (SAC305)/Ni micro solder joints under thermal shock from 77 K to 423 K was systematically investigated. The results indicated that the grain size of β-Sn, IMC (Ag3Sn and (Cu,Ni)6Sn5) particles inside the solder was refined by adding 0.05 and 0.1 wt% TiO2 nanoparticles. Due to the spalling of interfacial IMCs into the solder occurring in all micro joints during thermal shock, the thickness of interfacial IMCs did not show a monotony increasing trend with increasing thermal cycles. However, the micro composite solder joint added with 0.05 and 0.1 wt% TiO2 nanoparticles always exhibited thinner interfacial IMC thickness and higher shear force compared with the plain micro joints during thermal shock. The inhibiting effect of TiO2 nanoparticles on the interfacial IMC growth could be explained by the adsorption theory and grain boundary pinning theory. The improvement in shear property of micro composite solder joints was primarily induced by the refinement of IMC particles in the solder and the reduced growth rate of interfacial IMCs by adding TiO2 nanoparticles.

Herbicide leakage into seawater impacts primary productivity and zooplankton globally.

Predicting the magnitude of herbicide impacts on marine primary productivity remains challenging because the extent of worldwide herbicide pollution in coastal waters and the concentration-response relationships of phytoplankton communities to multiple herbicides are unclear. By analyzing the spatiotemporal distribution of herbicides at 661 bay and gulf stations worldwide from 1990 to 2022, we determined median, third quartile and maximum concentrations of 12 triazine herbicides of 0.18 nmol L-1, 1.27 nmol L-1 and 29.50 nmol L-1 (95%Confidence Interval: CI 1.06, 1.47), respectively. Under current herbicide stress, phytoplankton primary productivity was inhibited by more than 5% at 25% of the sites and by more than 10% at 10% of the sites (95%CI 3.67, 4.34), due to the inhibition of highly abundant sensitive species, community structure/particle size succession (from Bacillariophyta to Dinophyceae and from nano-phytoplankton to micro-phytoplankton), and resulting growth rate reduction. Concurrently, due to food chain cascade effects, the dominant micro-zooplankton population shifted from larger copepod larvae to smaller unicellular ciliates, which might prolong the transmission process in marine food chain and reduce the primary productivity transmission efficiency. As herbicide application rates on farmlands worldwide are correlated with residues in their adjacent seas, a continued future increase in herbicide input may seriously affect the stability of coastal waters.

Engineering Saccharomyces cerevisiae for fast vitamin-independent aerobic growth

Chemically defined media for cultivation of Saccharomyces cerevisiae strains are commonly supplemented with a mixture of multiple Class-B vitamins, whose omission leads to strongly reduced growth rates. Fast growth without vitamin supplementation is interesting for industrial applications, as it reduces costs and complexity of medium preparation and may decrease susceptibility to contamination by auxotrophic microbes. In this study, suboptimal growth rates of S. cerevisiae CEN.PK113-7D in the absence of pantothenic acid, para-aminobenzoic acid (pABA), pyridoxine, inositol and/or biotin were corrected by single or combined overexpression of ScFMS1, ScABZ1/ScABZ2, ScSNZ1/ScSNO1, ScINO1 and Cyberlindnera fabianii BIO1, respectively. Several strategies were explored to improve growth of S. cerevisiae CEN.PK113-7D in thiamine-free medium. Overexpression of ScTHI4 and/or ScTHI5 enabled thiamine-independent growth at 83% of the maximum specific growth rate of the reference strain in vitamin-supplemented medium. Combined overexpression of seven native S. cerevisiae genes and CfBIO1 enabled a maximum specific growth rate of 0.33 ± 0.01 h−1 in vitamin-free synthetic medium. This growth rate was only 17 % lower than that of a congenic reference strain in vitamin-supplemented medium. Physiological parameters of the engineered vitamin-independent strain in aerobic glucose-limited chemostat cultures (dilution rate 0.10 h−1) grown on vitamin-free synthetic medium were similar to those of similar cultures of the parental strain grown on vitamin-supplemented medium. Transcriptome analysis revealed only few differences in gene expression between these cultures, which primarily involved genes with roles in Class-B vitamin metabolism. These results pave the way for development of fast-growing vitamin-independent industrial strains of S. cerevisiae.

Scoliosis and kyphosis in blue-spotted and marbled flathead fish associated with a Myxobolus acanthogobii-like parasite.

Spinal deformities in finfish have the potential to impact aquaculture industries and wild populations by increasing morbidity, mortality, and reducing growth rates. Myxobolus acanthogobii has been implicated in causing scoliosis and lordosis in various aquatic species in Japan. We investigated 4 cases of spinal deformity in 2 flathead (Platycephalus) species that were submitted to the Elizabeth Macarthur Agricultural Institute (EMAI) in New South Wales (NSW), Australia, between 2015 and 2021. Flathead are commercially significant species that are popular among Australian consumers, and are also sought-after species targeted by recreational fishers. Gross deformities are concerning to the community and may impact the quality and quantity of specimens available for consumption. Three blue-spotted flathead (P. caeruleopunctatus) and one marbled flathead (P. marmoratus) were submitted, all with marked scoliosis and kyphosis; 1-2-mm cysts were present on the dorsum of the brain, most often over the optic lobe or cerebellum. Cytology and differential interference microscopy of cyst material revealed numerous oval spores, x̄ 14 ± SD 0.75 µm × x̄ 11.5 ± SD 0.70 µm, with 2 pyriform polar capsules, the morphology of which is consistent with a Myxobolus sp. PCR assay and 18S rDNA sequencing of the cyst material identified a Myxobolus sp. with 96% identity to M. acanthogobii. The identification of this Myxobolus sp. confirms the presence of parasites with the potential to cause spinal deformity in significant aquatic species in NSW waterways.

Dietary supplementation of Capsicum powder affects the growth, immunoglobulins, pro-inflammatory cytokines, adipokines, meat, and liver histology of aflatoxin B1 exposed broiler chickens

The effects of dietary supplementation with Capsicum annuum fruit pericarp powder (CPP) and Capsicum annuum fruit seed powder (CSP) on the health and performance of broiler chickens exposed to aflatoxin B1 (AFB1) was investigated. Four dietary groups were established: CON (control), AFT (0.5 mg/kg AFB1), CPAF (0.5 g/kg CPP and 0.5 mg/kg AFB1), and CSAF (0.5 g/kg CSP and 0.5 mg/kg AFB1). The AFT group shows a significant (P < 0.05) reduction in the relative growth rate compared to CON, CPAF, and CSAF. In contrast, the latter two groups exhibit growth rates similar (P > 0.05) to CON. Additionally, immunoglobulin levels (IgG, IgM, and IgA) in the AFT group are significantly (P < 0.05) lower compared to the other treatment groups. Serum interleukin-6 levels in the CPAF and CSAF groups were similar (P > 0.05) to CON but higher (P < 0.05) than in AFT. Tumor necrosis factor-alpha levels were elevated (P < 0.05) in AFT compared to the other treatment groups. Interferon-gamma concentrations in AFT were significantly (P < 0.05) lower than in the other treatment groups. The liver histology reveals that the AFT treatment group has periportal hepatic inflammation. In contrast, the CPAF and CSAF treatment groups exhibit normal hepatic microanatomy. In conclusion, 0.5 g/kg CPAF dietary supplementation may help to ameliorate the adverse effects of AFB1 exposure on broiler chicken health, specifically the growth, immune parameters and liver histology.

Influence of oxygen functional groups on the crack growth behavior of graphene with edge and middle crack: A molecular dynamics study

In the last decade, graphene has found a wide role and application in nanocomposites and nanodevices for its extraordinary properties. However, due to its low fracture toughness and brittleness, graphene is brittle, and crack growth occurs rapidly. As a result, crack growth behavior and control of its progression are important. In this study, molecular dynamics modeling was used to investigate the crack growth behavior and mechanical properties in functionalized graphene (with middle and edge crack) with different oxide groups (hydroxyl, epoxide, and carboxyl) at different percentages of graphene oxide (0–3 wt. %). The results show that functionalized graphene with oxide groups changes the properties of graphene, effectively reducing the crack growth in crack length (4.9 Å), crack opening displacement (1.4 Å), tensile strength for edge crack (74 to 54 Gpa), and middle crack (128 to 63 Gpa). Also, carboxyl and epoxide groups have a greater reduction in crack growth rate, opening displacement growth rate, and stress concentration. In addition, increase in the number of atoms in oxide groups around the initial crack (with radius 13 Å) reduces crack growth rate, opening displacement growth rate, and stress concentration. This study provides a broader insight into crack growth behavior in functionalized graphene with oxide groups.

Monitoring using artificial intelligence reveals critical links between housing conditions and respiratory health in pigs

Respiratory disease is the most significant issue in the pig industry and leads to high mortality and reduced growth rates. Housing conditions are crucial for maintaining the health and welfare of animals to optimize growth rates. This study aimed to evaluate the respiratory health status of pigs raised in different housing conditions using artificial intelligence (AI) technology and to determine the relationships between respiratory health and environmental factors. Eighty growing pigs (Largewhite × Landrace) × Duroc) were randomly distributed into two housing conditions: the control group, which had normal housing conditions, and the treatment group, which had poor housing conditions. A two-sample t test was performed to compare the groups, and a cross-correlation analysis was conducted to determine associations between respiratory health and days of exposure to environmental factors. The results show significant (p &lt; 0.001) lower incidence of respiratory health status along with a significant (p &lt; 0.001) greater frequency of coughing in pigs raised under poor housing conditions. Respiratory health is negatively associated with high exposure to temperature, relative humidity, and CO2 at lags 0 (R = -0.873, -0.887, and -0.869, respectively), -1 (R = -0.708, -0.742, and -0.705, respectively), and -2 (R = -0.545, -0.590, and -0.599, respectively). Furthermore, respiratory health was negatively associated with high exposure to NH3 (R = -0.420) at lag 0. In conclusion, AI technology is an effective tool for monitoring respiratory health. However, further evaluation and calibration of the alarm system threshold are recommended. These findings suggest that maintaining proper control of environmental factors can help prevent respiratory diseases in pigs.

Does size-selective harvesting erode adaptive potential to thermal stress?

Overharvesting is a serious threat to many fish populations. High mortality and directional selection on body size can cause evolutionary change in exploited populations via selection for a specific phenotype and a potential reduction in phenotypic diversity. Whether the loss of phenotypic diversity that accompanies directional selection impairs response to environmental stress is not known. To address this question, we exposed three zebrafish selection lines to thermal stress. Two lines had experienced directional selection for (1) large and (2) small body size, and one was (3) subject to random removal of individuals with respect to body size (i.e. line with no directional selection). Selection lines were exposed to three temperatures (elevated, 34°C; ambient, 28°C; low, 22°C) to determine the response to an environmental stressor (thermal stress). We assessed differences among selection lines in their life history (growth and reproduction), physiological traits (metabolic rate and critical thermal max) and behaviour (activity and feeding behaviour) when reared at different temperatures. Lines experiencing directional selection (i.e. size selected) showed reduced growth rate and a shift in average phenotype in response to lower or elevated thermal stress compared with fish from the random-selected line. Our data indicate that populations exposed to directional selection can have a more limited capacity to respond to thermal stress compared with fish that experience a comparable reduction in population size (but without directional selection). Future studies should aim to understand the impacts of environmental stressors on natural fish stocks.

The Oxidation Behaviors of NiCoCrAlY Coatings After Pre-Oxidation Treatment During High-Temperature Oxidation at 800 ℃ and 900 ℃

Thermal barrier coatings (TBCs) are essential for protecting the high-temperature components in gas turbines. However, the durability of TBCs is limited, and new technologies to improve their lifetime are necessary. This study focuses on the pre-oxidation treatment of the NiCoCrAlY bond coat in TBCs to reduce the growth rate of the thermally grown oxide (TGO) and improve the TBC lifetime. The mechanism of the TGO growth rate reduction by the pre-oxidation treatment of NiCoCrAlY was investigated. Oxidation behaviors of the surface of NiCoCrAlY coating samples with or without pre-oxidation treatment were evaluated in air at 800 °C and 900 °C. In-situ X-ray diffraction (XRD) measurements and isothermal oxidation tests were performed. The obtained results revealed that the growth rate of TGO is significantly suppressed by α-Al2O3 layer formed by the pre-oxidation treatment. The generation of γ-Al2O3 and θ-Al2O3, which are typically formed below 900 °C, was significantly reduced by pre-oxidation. It is suggested that this reduction suppresses of the TGO growth.

The interplay of low H2O2 doses, lytic cyanophage, and Microcystis aeruginosa: Implications for cyanobacterial bloom control and microcystin production/release

Low H2O2 doses can suppress cyanobacterial blooms without damaging non-target species but enable undesirable regrowth. Besides, the role of cyanophage in preventing regrowth after low H2O2 exposure remains unclear. Applying phages to cyanobacteria pre-exposed to low H2O2 in early growth stages may improve host removal and reduce microcystin (MC) production/release. Lytic cyanophage MDM-1 with a 172 PFU/cell burst size, 2-day short latent period against MCs-producing Microcystis, shows high H2O2 stability. Low H2O2 (1 to 2.5 mg/L) doses significantly (p < 0.05) inhibited Microcystis aeruginosa growth rate, biofilm and MCs concentration reduction in a dose-dependent manner but regrowth occurred at all concentrations. Phage treatment eliminated cells without H2O2 pretreatment within 3 days and reduced MC production. H2O2-pretreated M. aeruginosa cells altered the phage dynamics, affecting adsorption, latency, production, and cell lysis in response to H2O2-induced oxidative stress. At 1.5 mg H2O2/L pretreatment, cells were eliminated with reduced MC production, like untreated cells. H2O2 pretreatment with 2.0 and 2.5 mg/L resulted in an extension of the phage absorption phase and the latent period. This was accompanied by a reduction in lysis efficacy, attributed to the increased ROS production. At 2.5 mg H2O2/L, 17.10 % of phages remain un-adsorbed, with cell lysis rate dropped from 0.89 d−1 to 0.26 d−1 compared to the untreated control. The highest phage titer (70 %) was obtained with 1.5 mg/H2O2 pretreated cells. This study emphasizes that low-dose H2O2 eliminates Microcystis but severely affects phage lysis and MCs release depending on H2O2-induced ROS levels. It is a crucial consideration when using phages to control cyanobacterial blooms with H2O2-induced stress.

Agronomic evaluation of some progenies resulting from crosses between double self-fertilised genitors of &lt;i&gt;Deli&lt;/i&gt; and &lt;i&gt;La Mé&lt;/i&gt; origins used in oil palm (&lt;i&gt;Elaeis guineensis&lt;/i&gt; Jacq.) seed production in Côte d'Ivoire

Progeny tests carried out between self-fertilised double genitors (DA 115 D AF AF and LM 2 T AF AF) used in seed production in the C 1001 F category were set up in Côte d'Ivoire in 2005, in order to identify crosses producing good oil yields and capable of adapting to current climatic conditions. The aim of this study was to assess the agronomic values and growth rate of palm height of these progenies compared with two first-cycle controls, LM 2 T x DA 10 D and LM 2 T x DA 115. Their susceptibility to Fusarium wilt figurewas also assessed. The results of these tests showed a low bunch yield of around 99% on the one hand, and a 115% increase in oil yield compared with the first cycle on the other. In addition, two progenies, LM 25759 and LM 25753, performed exceptionally well, with oil yields of 125% and 127% respectively and a 97% reduction in palm height growth rate compared with the first cycle. These two progenies were also tolerant to Fusarium wilt with Fusarium index of 40 and 79 respectively.

Zonal variability of methane trends derived from satellite data

Abstract. The Tropospheric Monitoring Instrument (TROPOMI) on board the Sentinel-5 Precursor (S5P) satellite is part of the latest generation of trace gas monitoring satellites and provides a new level of spatio-temporal information with daily global coverage, which enables the calculation of daily globally averaged CH4 concentrations. To investigate changes in atmospheric methane, the background CH4 level (i.e. the CH4 concentration without seasonal and short-term variations) has to be determined. CH4 growth rates vary in a complex manner and high-latitude zonal averages may have gaps in the time series, and thus simple fitting methods do not produce reliable results. In this paper we present an approach based on fitting an ensemble of dynamic linear models (DLMs) to TROPOMI data, from which the best model is chosen with the help of cross-validation to prevent overfitting. This method is computationally fast and is not dependent on additional inputs, allowing for fast and continuous analysis of the most recent time series data. We present results of global annual methane increases (AMIs) for the first 4.5 years of S5P/TROPOMI data, which show good agreement with AMIs from other sources. Additionally, we investigated what information can be derived from zonal bands. Due to the fast meridional mixing within hemispheres, we use zonal growth rates instead of AMIs, since they provide a higher temporal resolution. Clear differences can be observed between Northern Hemisphere and Southern Hemisphere growth rates, especially during 2019 and 2022. The growth rates show similar patterns within the hemispheres and show no short-term variations during the years, indicating that air masses within a hemisphere are well-mixed during a year. Additionally, the growth rates derived from S5P/TROPOMI data are largely consistent with growth rates derived from Copernicus Atmospheric Monitoring Service (CAMS) global-inversion-optimized (CAMS/INV) data, which use surface observations. In 2019 a reduction in growth rates can be observed for the Southern Hemisphere, while growth rates in the Northern Hemisphere stay stable or increase. During 2020 a strong increase in Southern Hemisphere growth rates can be observed, which is in accordance with recently reported increases in Southern Hemisphere wetland emissions. In 2022 the reduction in the global AMI can be attributed to decreased growth rates in the Northern Hemisphere, while growth rates in the Southern Hemisphere remain high. Investigations of fluxes from CAMS/INV data support these observations and suggest that the Northern Hemisphere decrease is mainly due to the decrease in anthropogenic fluxes, while in the Southern Hemisphere, wetland fluxes continued to rise. While the continued increase in Southern Hemisphere wetland fluxes agrees with existing studies about the causes of observed methane trends, the difference between Northern Hemisphere and Southern Hemisphere methane increases in 2022 has not been discussed before and calls for further research.

Large scale sequence-based screen for recessive variants allows for identification and monitoring of rare deleterious variants in pigs.

Most deleterious variants are recessive and segregate at relatively low frequency. Therefore, high sample sizes are required to identify these variants. In this study we report a large-scale sequence based genome-wide association study (GWAS) in pigs, with a total of 120,000 Large White and 80,000 Synthetic breed animals imputed to sequence using a reference population of approximately 1,100 whole genome sequenced pigs. We imputed over 20 million variants with high accuracies (R2>0.9) even for low frequency variants (1-5% minor allele frequency). This sequence-based analysis revealed a total of 14 additive and 9 non-additive significant quantitative trait loci (QTLs) for growth rate and backfat thickness. With the non-additive (recessive) model, we identified a deleterious missense SNP in the CDHR2 gene reducing growth rate and backfat in homozygous Large White animals. For the Synthetic breed, we revealed a QTL on chromosome 15 with a frameshift variant in the OBSL1 gene. This QTL has a major impact on both growth rate and backfat, resembling human 3M-syndrome 2 which is related to the same gene. With the additive model, we confirmed known QTLs on chromosomes 1 and 5 for both breeds, including variants in the MC4R and CCND2 genes. On chromosome 1, we disentangled a complex QTL region with multiple variants affecting both traits, harboring 4 independent QTLs in the span of 5 Mb. Together we present a large scale sequence-based association study that provides a key resource to scan for novel variants at high resolution for breeding and to further reduce the frequency of deleterious alleles at an early stage in the breeding program.

The physiological role of Acinetobacter baumannii DacC is exerted through influencing cell shape, biofilm formation, the fitness of survival, and manifesting DD-carboxypeptidase and beta-lactamase dual-enzyme activities.

With the growing threat of drug-resistant Acinetobacter baumannii, there is an urgent need to comprehensively understand the physiology of this nosocomial pathogen. As penicillin-binding proteins are attractive targets for antibacterial therapy, we have tried to explore the physiological roles of two putative DD-carboxypeptidases, viz., DacC and DacD, in A. baumannii. Surprisingly, the deletion of dacC resulted in a reduced growth rate, loss of rod-shaped morphology, reduction in biofilm-forming ability, and enhanced susceptibility towards beta-lactams. In contrast, the deletion of dacD had no such effect. Interestingly, ectopic expression of dacC restored the lost phenotypes. The ∆dacCD mutant showed properties similar to the ∆dacC mutant. Conversely, in vitro enzyme kinetics assessments reveal that DacD is a stronger DD-CPase than DacC. Finally, we conclude that DacC might have DD-CPase and beta-lactamase activities, whereas DacD is a strong DD-CPase.