Dose-response Tests Research Articles

Mutation at the 197 site and P450-mediated metabolic resistance are involved in bensulfuron-methyl resistance in Sagittaria trifolia

Sagittaria trifolia control is threatened by the emergence of resistance to acetolactate synthase (ALS)-inhibiting herbicides. Hence, we systematically uncovered the molecular mechanism of resistance to the main herbicide (bensulfuron-methyl) in Liaoning Province from target-site and non-target-site resistance perspectives. The suspected resistant population (TR-1) exhibited high-level resistance. A new amino acid substitution (Pro-197-Ala) in resistant Sagittaria trifolia for ALS was detected, and the molecular docking results showed that the spatial structure of ALS changed significantly after the substitution, manifested by an increase in the number of contacted amino acid residues and the disappearance of hydrogen bonds. Dose-response test of transgenic Arabidopsis thaliana further demonstrated that the Pro-197-Ala substitution conferred bensulfuron-methyl resistance. The assays found that the sensitivity of the ALS enzyme in TR-1 to this herbicide was decreased in vitro; and this population had developed resistance to other types of ALS-inhibiting herbicides. Furthermore, the resistance of TR-1 to bensulfuron-methyl was significantly alleviated after co-treatment with a P450-inhibitor (malathion). TR-1 metabolized bensulfuron-methyl significantly faster than sensitive population (TS-1) did, but this gap was narrowed after malathion treatment. Overall, the resistance of Sagittaria trifolia to bensulfuron-methyl was derived from the mutation of the target-site gene and the enhancement of the P450s-mediated detoxification metabolism.

Ethyl Formate Fumigation for Control of the Scale Insect Asiacornococcus kaki, a Quarantine Pest on Sweet Persimmon, Diospyros kaki: Efficacy, Phytotoxicity and Safety

Sweet persimmons are a valuable export commodity. However, the presence of live insects such as Asiacornococcus kaki limits their access to many export markets. Methyl bromide, traditionally used for pest control, is damaging to human health and the environment. Ethyl formate (EF) is a viable alternative; however, its effectiveness against A. kaki on sweet persimmon fruit is unknown. We evaluated the effectiveness of EF fumigation in controlling A. kaki present under the calyx of persimmon fruit. The hatching rate of eggs and the survival rates of nymphs and adults of A. kaki at low temperatures, its LCt50 and LCt99 after EF exposure, and phytotoxic damage caused by EF were evaluated in laboratory-scale and commercial-scale tests. The dose-response tests showed that the EF LCt99 at 5 °C was 9.69, 42.13, and 126.13 g h m-3 for adults, nymphs, and eggs, respectively. Commercial-scale tests demonstrated EF efficacy against all A. kaki stages without causing phytotoxic effects on persimmons, though the eggs of A. kaki were not completely controlled in linear low-density polyethylene (LLDPE)-packaged fruit. This study demonstrated that EF is a potential fumigant for quarantine pretreatment, especially before persimmon fruit is packed with LLDPE film, to control A. kaki infesting sweet persimmon fruit.

Chronic inflammatory pain promotes place preference for fentanyl in male rats but does not change fentanyl self-administration in male and female rats

The current opioid epidemic is a national health crisis marked by skyrocketing reports of opioid misuse and overdose deaths. Despite the risks involved, prescription opioid analgesics are the most powerful and effective medications for treating pain. There is a clear need to investigate the risk of opioid misuse liability in male and female adults experiencing chronic pain. In the present study, we tested the hypothesis that chronic inflammatory pain would increase fentanyl intake, motivation to acquire fentanyl, and drug seeking in the absence of fentanyl in rats. Fentanyl intake, motivation for fentanyl, and drug seeking were tested under limited and extended access conditions using intravenous fentanyl self-administration. Fos activity in ventral tegmental area (VTA) dopamine neurons following intravenous fentanyl challenge (35 μg/kg) was examined using immunohistochemistry. Finally, we tested whether low-dose fentanyl supports development of conditioned place preference under an inflammatory pain state in rats. Contrary to our hypothesis, fentanyl self-administration and VTA Fos activity were unaffected by inflammatory pain status. During acquisition, males exhibited increased fentanyl intake compared to females. Animals given extended access to fentanyl escalated fentanyl intake over time, while animals given limited access did not. Males given extended access to fentanyl demonstrated a greater increase in fentanyl intake over time compared to females. During the dose-response test, females given limited access to fentanyl demonstrated increased motivation to acquire fentanyl compared to males. Both sexes displayed significant increases in responding for fentanyl as unit fentanyl doses were lowered. Following fentanyl challenge, females exhibited higher numbers of Fos-positive non-dopaminergic VTA neurons compared to males. Using conditioned place preference, we found that chronic inflammatory pain promotes fentanyl preference in males, but not females. These findings suggest that established fentanyl self-administration is resistant to change by inflammatory pain manipulation in both sexes, but chronic inflammatory pain increases the rewarding properties of low-dose fentanyl in males.

Combination Interactive Effects of Gongronema latifolium Leaves and Picralima nitida Seeds Extracts on Glucose Tolerance

This study evaluated the combination interactive effects of G. latifolium leaves and P. nitida seed extracts using a metabolic glucose tolerance test. The plant samples were extracted separately using cold maceration and their acute toxicities were determined. Dose-response glucose tolerant tests of both plants were done using a 2 g/kg glucose load monitored over 0 – 1h. A 41% effect isobologram was used to determine the needed dose combinations according to the principle of Loewe’s additivity model. The glucose tolerant tests of dose pairs of the combined extracts were evaluated and their combination indices were calculated to determine the nature of their interaction. The ED41 of G. latifolium (GL) and P. nitida (PN) were 180 mg/kg and 254 mg/kg respectively. The percentage reductions of GL:PN (50:160); GL:PN (100:90); and GL:PN (150:30) dose pairs were 48.23, 50.76 and 42.99 % respectively. Their combination index were calculated to be 0.91, 0.91 and 0.95 respectively - an indication of synergistic interaction. Findings from this study validate the combined use of G. latifolium leaves and P. nitida seeds in folkloric medicine. However, combining the extracts of G. latifolium: P. nitida in the dose ratios of 50:160, 100:90 and 150:30 mg/kg gave the best dose pairs with synergistic outcome.

Investigation of the regulatory effects of synthesized antisense oligonucleotides on androgen receptor (AR) exon 3 splicing in prostate cancer cells

The Androgen Receptor (AR) gene plays a key role in castration-resistant prostate cancer (CRPC). Controlling the progression of CRPC by inhibiting AR gene expression is one of the core directions for prostate cancer (Pca) drug development. A 23-amino acids retention, named exon 3a, into the DNA binding domain of the splice variant AR23 has been shown to prevent AR from entering the nucleus and restore the sensitivity of cancer cells to related therapies. In this study, we conducted a preliminary investigation of the splicing modulation of the AR gene in order to develop a splice-switching therapy for Pca by promoting exon 3a inclusion. Using mutagenesis-coupled RT-PCR with AR minigene and over-expression of certain splicing factors, we found that serine/arginine-rich (SR) proteins are key factors facilitating the recognition of the 3′ splice site of exon 3a (L-3′ SS), while the deletion or blocking of the polypyrimidine tract (PPT) region of the original 3′ splice site of exon 3 (S-3′ SS) could strongly enhance exon 3a splicing without affecting the function of any SR protein. Furthermore, we designed a series of antisense oligonucleotides (ASOs) to screen drug candidates, and ASOs targeting S-3′ SS and its PPT region or the exonic region of exon 3 turned out to be most effective in rescuing exon 3a splicing. A dose–response test indicated ASO12 as the lead candidate drug significantly promoting the inclusion of exon 3a to more than 85%. MTT assay confirmed that the cell proliferation was significantly inhibited after ASO treatment. Our results provide the first glance to AR splicing regulation. With several promising therapeutic ASO candidates obtained here, further development of ASO drugs to treat CRPC is strongly encouraged.

Seasonal Vitamin A Depletion in Grazing Horses Is Assessed Better by the Relative Dose Response Test than by Serum Retinol Concentration

Vitamin A influences growth and reproduction in horses. A retinol dose response (RDR) test for retinol has been shown to be better than serum retinol concentration for assessing vitamin A status in other species, so we have compared these two methods in the horse. Forty-five Thoroughbred broodmares were assigned randomly to three groups fed pasture and hay (PH), pasture, hay and vitamin A-free concentrate (PHC), or hay and concentrate (HC) in early summer (May 1991). Mares in pasture groups produced 23 foals (March through June) that had access to their dam's diets and were also studied. In the mares, significant vitamin A depletion developed in 2 mo in the nonpasture group (HC) and in 8 mo in the two pasture groups (PH and PHC) according to the RDR test, and in all three groups at 8 mo as shown by a decrease in serum retinol concentration. In the weanlings (PH and PHC only), no differences between groups were found for serum retinol, but the RDR was significantly higher in the PH group, which had suffered a respiratory infection, than in the PHC group. These findings indicated that vitamin A depletion was detected more readily by the RDR test than by serum retinol concentration, that consumption of pasture delayed depletion in the late fall, and that infection was associated with lower vitamin A status.

Widespread Occurrence of Glyphosate-Resistant Hairy Fleabane (Erigeron bonariensis L.) in Colombia and Weed Control Alternatives

Glyphosate, the most applied herbicide globally, offers effective non-selective and post-emergent weed control. Evolution of herbicide-resistant weeds is commonly associated with the recurrent application of herbicides with the same mode of action. Native to South America, hairy fleabane (Erigeron bonariensis L.) is the most problematic weed in this sub-continent and has previously been confirmed glyphosate resistant. This research aimed at characterizing glyphosate-resistant populations, thus estimating the frequency of resistance, resistance levels and identifying effective herbicide alternatives to control glyphosate-resistant populations. Glyphosate resistance characterization was initially conducted on ten suspected populations collected in plantain, banana, cassava, passionfruit, papaya, and drybean crops. Two resistant populations were selected and further characterized through dose-response tests; in addition, response to alternative herbicides (paraquat, glufosinate, 2,4-D, pyraflufen-ethyl, and mesotrione) was determined. All surveyed hairy fleabane populations survived (≥80% of individuals) the recommended glyphosate rate of 1080 g ae ha−1; conversely, five populations collected from non-cropping areas were effectively controlled at this same rate. Dose-response tests estimated resistance factors of 3.15- to 22.3-fold versus the most susceptible population. Interestingly, resistance profile and dose-response tests detected hormesis responses at field-recommended rates. The most effective herbicide alternatives to control glyphosate-resistant hairy fleabane were pyraflufen-ethyl and mesotrione.

The Antibiotic Kitasamycin-A Potential Agent for Specific Fibrosis Preventing Therapy after Fistulating Glaucoma Surgery?

One major complication after fistulating glaucoma surgeries are fibroblast-mediated scarring processes and their specific prevention is key in the development of novel pharmaceutical concepts. Within this study a possible antifibrotic potential of kitasamycin (KM) in a transforming growth factor (TGF)-β1-mediated fibroblast model was evaluated in vitro. Primary ocular fibroblasts were isolated, cultivated and a dose-response test including determination of the half maximal effective concentration (EC50) for KM was conducted. Transformation of fibroblasts into myofibroblasts was induced by TGF-β1and immunofluorescence (IF), and Western blot (WB) analyses were performed with fibroblasts and myofibroblasts. IF analyses were carried out using antibodies against α-smooth muscle actin (α-SMA) and fibronectin, and protein detection of intracellular and extracellular proteins was performed by WB. Using the dose-response test, the viability, cytotoxicity and EC50 of KM after 24 and 48 h were determined. Fibroblasts exposed to various KM concentrations showed no increase in α-SMA and extracellular matrix expression. In TGF-ß1-stimulated myofibroblasts, KM inhibited the expression of α-SMA and fibronectin in a concentration-dependent manner. These findings demonstrate that KM could impair the transformation of fibroblasts into myofibroblasts and the expression of proteins involved in fibrotic processes, representing a potential agent for specific fibrosis prevention in future therapeutic concepts.

Comparative analysis of fungal communities between herbicide-resistant and -susceptible Alopecurus aequalis.

Alopecurus aequalis is a grass species invading Chinese canola and wheat fields. An A. aequalis KMN-R population surviving mesosulfuron-methyl treatment with recommended rates was acquired from wheatland. Here, we aimed to confirm the resistance profiles of KMN-R to acetolactate synthetase (ALS) inhibiting herbicides and explore the possible resistance mechanisms to mesosulfuron-methyl in this weed population. The dose-response tests performed in our study were used to test the toxicity of A. aequalis to ALS-inhibiting herbicides. Sanger sequencing was used to analyze the ALS gene of mesosulfuron-methyl -resistant and -susceptible A. aequalis. RNA sequencing analysis was used to find candidate genes that may confer metabolic resistance to the mesosulfuron-methyl in resistant A. aequalis population. Mesosulfuron-methyl -resistant and -susceptible A. aequalis populations fungal composition was measured via Illumina MiSeq Sequencing. Dose-response results indicated that KMN-R population evolved resistance to mesosulfuron-methyl and other tested ALS-inhibiting herbicides. Known resistance-conferring Trp-574-Leu gene mutation in A. aequalis ALS was detected in the KMN-R population. Pretreatment with 4-chloro-7-nitrobenzoxadiazole reversed mesosulfuron-methyl resistance in KMN-R. Glutathione S-transferases (GST) gene GSTZ2 and GSTT3 were highly expressed in KMN-R population. In addition, we evaluated the alpha diversity in A. aequalis, centering on OTU abundance, equality, and multiplicity, and found that the fungal community composition had more unexplained variance between KMN-R and KMN-S A. aequalis. We also observed higher abundances of specific fungi in KMN-R A. aequalis. The results proved that resistance to mesosulfuron-methyl in A. aequalis KMN-R population is probably caused by target site- and non-target site-based relating GST and provided the basis for further research between fungal interaction and herbicide resistance.

Gamma and X-ray irradiation as a phytosanitary treatment against various stages of Planococcus lilacinus (Hemiptera: Pseudococcidae)

• Late-aged adult female of cacao mealybug is most tolerant to gamma and X-ray irradiation. • None F 1 generation 2nd instar nymphs emerged from 97,384 adult females irradiated at 126.1-163.0 Gy in confirmatory tests. • The treatment efficacy is not less than 99.9969% at the 95% confidence level. • A minimum of 163 Gy is suggested for phytosanitary irradiation treatment of cacao mealybug. The cacao mealybug, Planococcus lilacinus Cock, is an important quarantine pest. Infested commodity should be subject to appropriate phytosanitary treatment, while irradiation is recommended for the cacao mealybug. Radio-tolerance comparison tests were conducted on the crawler, nymphs, and adult females of P . lilacinus at the X-ray radiation doses of 40, 80, and 120 Gy, respectively. The results showed that irradiation had a strong effect on preventing of development and reproduction; the adult female stage was identified as the most tolerant. During the following dose-response tests, among young and late females X-ray-irradiation (20–100 Gy), the late females were most tolerant when preventing F 1 generation 2nd instars emergence was used as the evaluation criterion. Minimum absorbed dose and its 95% fiducial limits to provide probit 9 efficacy at 95% confidence level (100% mortality/inhibition in an estimated population of 93,616 individuals) were 131.5 Gy (122.5, 142.6 Gy) and 144.4 Gy (132.7, 159.4 Gy), estimating from the probit analysis on dose-mortality data of 1–30 and 1–10-day-old neonates laid by late females, respectively. In the large-scale confirmatory tests, a total of estimating 97,384 late females of P. lilacinus rearing on the pumpkins fruits were irradiated with gamma-ray at the target dose of 135 or 145 Gy (measured doses 126.1–163.0 Gy), which resulted in no F 1 generation 2nd nymphs developing during a 6-week post-treatment period. The treatment efficacy calculated is 99.9969% at the 95% confidence level. Therefore, a minimum absorbed dose of 163.0 Gy is recommended for phytosanitary treatment of P. lilacinus in infested commodity.

Thermoluminescence properties and identification of irradiated cocoa beans during long-term storage

This work reports on the thermoluminescence (TL) properties and detection of contaminating minerals isolated from Mexican cocoa beans irradiated with gamma radiation and stored for 4 years. Contaminating minerals isolated from cocoa beans consisting of quartz, diopside, plagioclase, albite, and iron oxide with irregular and rectangular grains and average length of 135 μm. Cocoa beans are detected as irradiated even after 4 years of storage using the shape and maximum temperature of the TL glow curve of contaminating minerals. The TL properties of dose-response, and fading of minerals were also analysed. The TL dose-response is linear from 5 to 100 Gy, supra-linear between 250 and 1000 Gy, and sub-linear above 1500 Gy. Based on the TL1/TL2 ratio the minerals are identified as irradiated from 250 Gy to 4500 Gy in the dose-response test and after different storage times in the darkness at room temperature. A continuum trap distribution can be associated with the TL glow curve of minerals using the Tm-Tstop method. First order kinetic peaks were used in the Glow Curve Deconvolution of natural and irradiated (1 and 10 kGy) TL curves.

The Efficacy, Phytotoxicity, and Safety of Liquid Ethyl Formate Used to Control the Grape (Campbell Early) Quarantine Pest Pseudococcus comstocki

Mealybugs found on grapes during quarantine in Korea are fumigated with methyl bromide (MB). However, MB is an ozone-depleting, highly toxic pesticide; therefore, the International Plant Protection Convention, a representative organization involved in quarantine, recommends using MB alternatives. We evaluated the feasibility of using liquid ethyl formate (EF), a new EF formulation, to control mealybugs (Pseudococcus comstocki) on grapes (Campbell Early). Large-scale tests and the comparative evaluation of EF and MB desorption from grapes were conducted during the simulated 72-h post-fumigation period. Dose–response tests showed that the EF concentration and time product causing 99% mortality (LCt99) at 5 °C was 47.36 and 145.85 g h/m3 for adults and eggs, respectively. EF treatment at 70 g/m3 for 4 h at 5 °C with a loading ratio of 10% achieved an LCt99 of 145.85 g h/m3 on P. comstocki, confirming EF efficacy on mealybugs without phytotoxic effects on grapes. EF fumigation may also be safer because EF concentrations were maintained at less than 100 ppm, the specified exposure limit of EF; meanwhile, those of MB were higher than the exposure limit (1 ppm). Therefore, liquid EF can be used as a safer alternative to MB in phytosanitary treatments of grapes to control P. comstocki.

Butyrate Glycerides Protect against Intestinal Inflammation and Barrier Dysfunction in Mice.

This study investigates the attenuating effects of butyrate glycerides (BG) on intestinal inflammatory responses and barrier dysfunction induced by LPS stimulation. An initial dose-response test was carried out to identify the optimal dose of BG for further testing. The mice were given intragastric administration of BG at different doses followed by lipopolysaccharide (LPS) intraperitoneal injection. The small intestinal morphology and cytokine mRNA expression were measured. With 1.5 g/kg BW BG administration, it was possible to alleviate the injury of duodenal morphology, attenuate ileum villus height reduction and promote IL-10 mRNA expression. Therefore, the optimal dosage of 1.5 g/kg BW BG was selected for the main experiment. The ultrastructure image of jejunum and ileum epithelial cells, mRNA expression, the level of cytokine and immunofluorescence in the ileum were analyzed. The results showed that BG maintain the ileac brush border, tight junction structures and protein expression. BG attenuated the increased inflammatory cytokines, TLR4 and JNK mRNA expression. Taken together, 1.5 g/kg BW BG administration maintained intestinal barrier function and reduced intestinal and body inflammation responses induced by LPS in mice. The mechanism by which BG alleviated intestinal inflammatory response and maintained intestinal barrier function may be related to the JNK signaling pathway.

Analysis of sex pheromone production and field trapping of the Asian corn borer (Ostrinia furnacalis Guenée) in Xinjiang, China

Identifying the sex pheromone systems of local pest populations facilitates their management, especially for moth species that show significant geographic variation in sex pheromone communication. We investigated the pheromone production and behavioral responses of the Asian corn borer (Ostrinia furnacalis Guenée; ACB) in Xinjiang, China. The ACB produces three compounds: (Z)-12-tetradecenyl acetate (Z12-14:Ac) and (E)-12-tetradecenyl acetate (E12-14:Ac) which are two sex pheromone compounds, and n-tetradecyl acetate (14:Ac) which has variable roles in mediating behavioral responses. The ratios of these three compounds produced in female gland are geographically distinct among different populations. Quantitative analysis of pheromone production showed that the proportions of Z12-14:Ac in the E/Z isomers (i.e., Z and E12-14:Ac) and the proportions of 14:Ac in the ternary blend respectively averaged 60.46% (SD=5.26) and 25.00% (SD=7.37), with their probabilities normally or near-normally distributed. Trapping experiments in a cornfield indicated that deploying the E/Z isomers and the three compounds in rubber septa close to their gland ratios yielded the most captured males, while other ratios that deviated from the gland ratios showed reduced field captures. The ternary blend was significantly more attractive to males than the E/Z isomers in the field, indicating a functional role of 14:Ac as the third pheromone component used by the local population. Additionally, the dose-response test demonstrated that the application of the three compounds at dosages between 200 and 350 μg attracted significantly more males compared to other dosages. Therefore, the characterization of this local ACB pheromone system provides additional information about its geographic variation and serves as a basis for optimizing the pheromone-mediated control of this pest in Xinjiang.

Sustainable Design of New Ionic Forms of Vitamin B3 and Their Utilization as Plant Protection Agents.

This study demonstrates the utilization of naturally occurring nicotinamide (vitamin B3) in the sustainable synthesis of organic salts with application potential as environmentally friendly agrochemicals. The designed ionic pairs, obtained with high yields, consisted of N-alkylnicotinamide cation and commercially available herbicidal anions: 2,4-dichlorophenoxyacetate (2,4-D) and 4-chloro-2-methylphenoxyacetate (MCPA). The study confirmed the strong influence of the length of alkyl chain in products on the physicochemical properties as well as the development of cornflower and oil-seed rape. The majority of tested salts showed significantly better herbicidal activity (by approx. 30–50%) compared to the reference herbicide. Furthermore, N-hexadecylnicotinamide 4-chloro-2-methylphenoxyacetate was significantly more effective than the commercial formulation in the dose–response test. Their negligible vaporization, multiple times lower than that of commonly used dimethylammonium salts, eliminates one of the greatest threats of currently applied plant protection agents. Additionally, the risk of product migration or bioaccumulation in the environment was assessed as extremely low.

Safety and Immunogenicity of Inactivated and Recombinant Protein SARS-CoV-2 Vaccines in Patients With Thyroid Cancer.

BackgroundThis study aimed at assessing the safety and immunogenicity of SARS-CoV-2 vaccines in patients with thyroid cancer.MethodsThis observational study included thyroid cancer patients between April 1, 2021, and November 31, 2021, in the Second Affiliated Hospital of Chongqing Medical University. All participants received at least one dose of the SARS-CoV-2 vaccine. SARS-CoV-2 IgG was tested, and the interval time between the last dose and humoral response test ranged from <1 to 8 months. The complications after SARS-CoV-2 vaccines were recorded.ResultsA total of 115 participants at least received one dose of SARS-CoV-2 vaccines with a 67.0% IgG-positive rate. Among them, 98 cases had completed vaccination, and the positivity of SARS-CoV-2 IgG antibodies was 96% (24/25) with three doses of ZF2001. SARS-CoV-2 IgG antibodies’ positivity was 63.0% (46/73) of two doses of CoronaVac or BBIBP-CorV vaccine. Additionally, after 4 months of the last-dose vaccination, the IgG-positive rate (31.6%, 6/19) significantly decreased in thyroid cancer patients. The IgG-positive rate (81.0%, 64/79) was satisfactory within 3 months of the last-dose vaccination. Ten (10.2%) patients had side effects after SARS-CoV-2 vaccination. Among them, two (2.0%) patients had a fever, five (5.1%) patients had injection site pain, one (1.0%) patient felt dizzy, and one patient felt dizzy and had injection site pain at the same time.ConclusionSARS-CoV-2 vaccines (CoronaVac, BBIBP-CorV, and ZF2001) are safe in thyroid cancer patients. The regression time of SARS-CoV-2 IgG is significantly shorter in thyroid cancer patients than in healthy adults. Therefore, a booster vaccination dose may be earlier than the systematic strategy for thyroid cancer patients.

Bacillus velezensis supernatant mitigates tomato Fusarium wilt and affects the functional microbial structure in the rhizosphere in a concentration-dependent manner

This study aimed to test the hypothesis whether the soil-application of Bacillus velezensis Bs006 and its supernatant affect the rhizospheric microbial community of tomato-Fusarium oxysporum f. sp. lycopersici pathosystem. The relationship between the functional response of the microorganisms measured through use of carbon sources and the disease development was determined under a dose-response test between Fusarium wilt development and Bs006-based treatments (spores at 1 × 107 and 1 × 109 cfu ml−1 and supernatant at 1 and 10%). Use of carbon sources by the microbial community in the rhizosphere at 3 and 30 days after treatment were determined through the Ecoplate Biolog® microplate assays. The efficacy against disease development was dependent on the concentrations of biocontrol treatments, with low concentrations (Supernatant-1% and Bs006-107 cfu ml−1) significantly reducing the incidence of tomato vascular wilt compared to the effect of the highest concentrations (Supernatant-10% and Bs006-109 cfu ml−1). The use of carbon sources expressed as the average metabolic response (AMR), by the rhizosphere microbial community was higher in the less effective treatments of biocontrol than the absolute control and the plants treated with low concentration of biocontrol treatments. The high AMR was related with low functional microbial diversity, expressed as the number of carbon sources consumed, which was also low in the rhizosphere of the negative control. On the contrary, the AMR was lower, and the functional microbial diversity was higher in the most effective treatments against Fusarium wilt. Functional microbial groups consuming carbohydrates, polymers and amines were associated with the less effective treatments, while the use of amino acids and carboxylic acids was associated with the most effective treatments. We conclude that treatments containing Supernatant-10% changed the rhizosphere microbial behavior for carbon sources consumption and it was stablished as a factor that promotes the tomato Fusarium-wilt development. This study contributes to the aspects to be considered in the generation of use directions of fungicides based on Bacillus spp.

Herbicide resistance in Avena sterilis subsp ludoviciana populations from the wheat fields of Turkey

Avena sterilis L. subsp ludoviciana (Durieu) Gillet and Magne (AVELU) is among the most common and economically important grass weed species, especially in wheat fields of Turkey; therefore, the herbicides with the same mode of action (ACCase and ALS/AHAS inhibitors) are used to control have been successively applied without incessant by farmers. A study was conducted to find out the extent of wild oat problems throughout Turkey including herbicide resistance. This paper includes results of determining the herbicide resistance status of AVELU populations to ACCase and ALS inhibitors that are fenoxaprop (Fen), pinoxaden (Pin), tralkoxydim (Tra), mesosulfuron+iodosulfuron (MeI), and proxycarbazone+mesosulfuron (PrM). AVELU seeds were collected from 213 wheat fields throughout Turkey in 2014?2015 and the response to selected five herbicides was tested under screen-house. Dose-response tests showed that only 42 populations were controlled by all five herbicides. The number of populations that were not controlled varied by herbicides, which were 150, 48, 25, 100, and 100 populations for Fen, Pin, Tra, MeI, and PrM, respectively. Nine populations were resistant to all herbicides and 72 to four of herbicides out of 155 multiple resistance populations. The high number of multiple resistances and higher resistance indexes show the seriousness of the problem. Although resistance to MeI and Tra herbicides are still developing, Fen resistance seems completed and reached moderate and high resistance levels. Integrated weed management is an inevitable challenge to sustain wheat production, a staple crop for Turkey.

Determination of Median Lethal Concentration (LC50) for Endosulfan, Heptachlor and Dieldrin Pesticides to African Catfish, Clarias gariepinus and Their Impact on Its Behavioral Patterns and Histopathological Responses.

Pesticides such as endosulfan, heptachlor and dieldrin persist in aquatic environments as a result of their resistance to biodegradation. However, there is no adequate information about the toxicity of endosulfan, heptachlor and dieldrin to the aquatic organism, African catfish (Clarias gariepinus)—a high valued widely distributed commercially interesting species. The current experiment was performed with the aim to determine the median lethal concentration (LC50) of endosulfan, heptachlor and dieldrin to African catfish (Clarias gariepinus); their behavioral abnormalities and histopathological alterations in several vital organs. A total of 324 juvenile fish were exposed for 96 h to six concentrations of endosulfan and dieldrin at 0, 0.001, 0.002, 0.004, 0.008 and 0.016 ppm, and to heptachlor at concentrations of 0, 0.02, 0.04, 0.08, 0.16 and 0.32 ppm for dose-response tests. The study demonstrated that the species is highly susceptible to those contaminants showing a number of behavioral abnormalities and histopathological changes in gill, liver and muscle. The 96-h LC50 value of endosulfan, dieldrin and heptachlor for the African catfish was found as 0.004 (0.001−0.01) mg/L, 0.006 mg/L and 0.056 (0.006−0.144) mg/L, respectively. Abnormal behaviors such as erratic jerky swimming, frequent surfacing movement with gulping of air, secretion of mucus on the body and gills were observed in response to the increasing exposure concentrations. Histopathological alterations of liver, gill and muscle tissues were demonstrated as vacuolization in hepatocytes, congestion of red blood cells (RBCs) in hepatic portal vein; deformed secondary lamellae and disintegrated myotomes with disintegrated epidermis, respectively. These findings are important to monitor and responsibly manage pesticide use in and around C. gariepinus aquacultural areas.

Negative food dilution and positive biofilm carrier effects of microplastic ingestion by D. magna cause tipping points at the population level

Ingestion of microplastics by aquatic organisms is often harmful due to the dilution of their regular food with low-calorie microplastic particles, but can also be beneficial if nutritious biofilms are present on the microplastic surface. This begs the question: is ingestion of microplastic harmful or beneficial and can the net effect of the two mechanisms be quantified? Here, we quantified these harmful and beneficial effects on Daphnia magna, using dose-response tests with clean and biofouled microplastic respectively, and determined the trade-off between these counteracting effects. A population model was developed to calculate the isoclines for zero population growth, separating the regime where adverse food dilution dominated from that where the beneficial biofilm vector mechanism dominated. Our results show that the organisms grew better when exposed to biofouled microplastic compared to pristine microplastic. Very good model predictions (R2 = 0.868–0.991) of the effects of biofouled microplastic were obtained based on literature parameter values, with optimization required only for the two sub-model parameters driving the dose-effect relationships for pristine microplastic. These results contradict previous sudies were only pristine microplastic were used and demonstrate that the ruling paradigm of unambiguously adverse microplastic effects is not ecologically justifiable.