保幼激素类似物苯氧威对异色瓢虫不同发育阶段的影响

【目的】本研究旨在明确保幼激素类似物苯氧威对天敌异色瓢虫Harmonia axyridis的影响, 并探讨其作用机理, 以便进行安全性评价并为科学使用提供理论依据。【方法】应用连叶浸渍法、浸渍法、点滴法和药膜法分别处理异色瓢虫卵、2龄幼虫、蛹和成虫, 观察苯氧威对4个虫态的影响。【结果】用浓度为0.0001 μg/mL的药液处理初产卵, 能抑制胚胎的发育; 但用高达20 000 μg/mL的药液处理发育2 d的卵, 幼虫仍可正常孵化; 用浓度高达4 000 μg/mL的药液浸渍2龄幼虫, 对幼虫的致死作用极小; 用浓度为0.0001 μg/头的药液处理当天蛹, 形成蛹 成虫中间体, 羽化的成虫畸形; 用浓度为0.0125 μg/mL的药液处理成虫, 24 h后成虫的生命力受到明显影响。【结论】苯氧威对异色瓢虫初产卵有明显的毒杀作用, 严重阻碍蛹到成虫的变态和影响成虫的存活。在田间使用该杀虫剂时, 要避开异色瓢虫的敏感期。     

Individual and Joint Toxicity Effects of Cu,Cr(III), and Cr(VI) on Pakchoi: A Comparison Between Solution and Soil Cultures

The single and joint toxicity effects of Cu, Cr(III), and Cr(VI) on the root elongation of pakchoi in solution and soil were investigated. The median effective concentration (EC₅₀) was determined to examine the toxic thresholds of the test elements. The results showed that individual contamination by Cu, Cr(III), or Cr(VI) can inhibit the root elongation of pakchoi. The EC₅₀ values of the test elements were 2.02 mg/L and 195.8 mg/kg, 62.2 mg/L and 1,773 mg/kg, and 6.88 mg/L and 8.08 mg/kg in solution and soil, respectively. Toxic unit (TU) was introduced to determine the outcome in combined tests, and different behaviors were observed in both solution and soil. The coexistence of Cu and Cr(III) in solution exhibited an antagonistic effect (EC_50mix = 1.76 TU_mix), whereas a synergistic effect was observed in soil (EC_50mix = 0.76 TU_mix). In contrast, combined Cu–Cr(VI) showed a less than additive toxicity both in solution and soil, with EC_50mix values of 3.31 and 1.24 TU_mix. In conclusion, the coexistence of toxicity in Cu–Cr(III) and Cu–Cr(VI) differs from the toxicity exhibited individually by Cu, Cr(III), and Cr(VI). Heavy metal interaction also changes depending on the medium.     

苯醚威作用于印鼠客蚤的组织学研究

【目的】通过研究苯醚威对印鼠客蚤 Xenopsylla cheopis (Rothschild,1903)的早 3 龄幼虫和未吸血新羽化成虫的组织学变化,探讨其灭蚤机理,为鼠疫媒介蚤种的防治提供基础资料。【方法】以微量点滴法将苯醚威施药于印鼠客蚤早3龄幼虫和未吸血新羽化成虫,采用组织学、显微摄影及统计学方法观察组织变化。【结果】经苯醚威作用后,印鼠客蚤的早 3 龄幼虫的表皮增厚、卵巢芽生殖细胞萎缩、睾丸芽精原细胞间质减少;未吸血新羽化成虫的睾丸塞消失快、唾液腺细胞破坏严重、中肠上皮细胞萎缩。【结论】(1)苯醚威通过干扰印鼠客蚤幼虫的变态,引起幼虫表皮、生殖芽异常改变,不能发育为成虫而死亡;(2)苯醚威可加速印鼠客蚤新羽化雄性成虫的睾丸塞吸收;(3)苯醚威可破坏印鼠客蚤新羽化成虫的唾液腺细胞,并引起中肠上皮细胞萎缩。     

Effects of ultralow doses of fenoxycarb on juvenile hormone–regulated physiological parameters in the silkworm,Bombyx mori L.

Effects of fenoxycarb at ultralow doses were investigated on juvenile hormone (JH)–regulated parameters in the silkworm, B. mori. Like JH, this non-terpenoid carbamate is able to induce permanent larvae in the last larval instar. However, whereas micrograms of JH are needed to produce this effect, only a few picograms of fenoxycarb are necessary to induce the same effect. The effects of fenoxycarb observed in this study were only visible from day 4 of the last larval instar—that is, when the JH titer has dropped to undetectable levels and JH-repressed physiological parameters would naturally be expressed. We observed that the permanent larvae induced with low doses of fenoxycarb (100 pg/larva) had no 20-hydroxyecdysone (20E) peak. Their prothoracic glands (Pgs) were completely inactive and very weakly sensitive to prothoracicotropic hormone (PTTH). Fenoxycarb at doses of 1 ng/larva also significantly inhibited silk gland growth and coloration, whereas carotenoid content of the hemolymph was maintained at high levels, which could reflect an inhibition of its uptake by the silk glands. Total hemolymph protein levels in last instar larvae were also depressed at these doses. So, it seems that low doses of fenoxycarb are sufficient to maintain in a juvenilized status the physiological parameters that are normally expressed when JH titer has declined. Moreover, from an endocrinological viewpoint, we demonstrated that the corpora allata (CA) are not necessary for fenoxycarb to induce those effects and discussed its possible mode of action. Arch. Insect Biochem. Physiol. 37:178–189, 1998. © 1998 Wiley-Liss, Inc.     

Suppression of JH biosynthesis by JH analog treatment: Mechanism of suppression and roles of allatostatins and nervous connections in the cockroach Diploptera punctata

Juvenile hormone analogs are known to inhibit the production of juvenile hormone (JH) by the corpora allata (CA). However, the mechanism of this inhibition remains undefined. We have used two JH mimics, fenoxycarb and pyriproxyfen, to examine the mechanism of suppression in the cockroach, Diploptera punctata. Denervation experiments demonstrated the importance of nervous connections between the brain and CA for the inhibition of JH biosynthesis by fenoxycarb. Fenoxycarb treatment alters the sensitivity of CA to allatostatin treatment in vitro. Suppression of JH biosynthesis by fenoxycarb following denervation of the CA showed that innervation was in part responsible for the inhibition. Similarly, maximal inhibition by Dippu-AST7 requires intact nervous connections between the brain and CA, particularly during rapid vitellogenesis. qPCR analysis of brain, CA, ovary and midgut extracts revealed that both allatostatin and its receptor Dippu-ASTR2 show increased levels of expression following topical fenoxycarb treatment, particularly in brain tissue on days 4 and 5 of the first gonadotrophic cycle and in CA on day 4. The correlation between inhibition of JH biosynthesis and increased expression of AST and ASTR2 in brains and CA, together with increased sensitivity of CA to allatostatin in vitro, suggests that allatostatin may be one of the effectors by which fenoxycarb inhibits JH biosynthesis.     

Effects of fenoxycarb on ovarian development, spring fecundity and longevity in winterform pear psylla

The insect growth regulator fenoxycarb prompts ovarian development in diapausing winterform pear psylla, Cacopsylla pyricola (Förster) (Homoptera: Psyllidae). We applied fenoxycarb to caged psylla in September, November, and December to test whether premature ovarian development reduced overwintering survival, spring fecundity, or spring longevity. Fenoxycarb prompted ovarian development in all treated psylla, with the largest effects occurring in the September-treated insects. Recovery of live psylla in spring was 46–95% in treated insects and 72–92% in controls; overwintered insects from the fenoxycarb treatment survived field temperatures below –20°C despite having had mature ovaries. Fecundity and longevity of psylla were the same in treated and untreated insects, indicating that overwintering with mature ovaries did not cause reduced spring egglaying capacity. Several treated insects each deposited over 1900 eggs and survived more than 120 days. Due to their more advanced development, treated insects had higher oviposition rates than controls during the first 5 days after removal from the field. The largest impact on spring fitness was due to the effects of fenoxycarb on egg hatch. Eggs deposited on clean foliage by September-treated females were less likely to hatch than eggs deposited by controls, suggesting that fenoxycarb affected developing eggs within the female. Prospects for using fenoxycarb in fall to control pear psylla appear to be limited.     

Stimulation of egg production in the grain miteAcarus siro by the juvenile-hormone analogue fenoxycarb

The insect juvenile-hormone analogue fenoxycarb (ethyl [2-(phenoxyphenoxy) ethyl] carbamate) has been shown to stimulate egg production in the flour miteAcarus siro L. Incorporation of fenoxycarb into mite food at 10 mg kg^–1 and 100 mg kg^–1 increased egg production by 43% and 99%, respectively. In addition, total mite populations were significantly higher in fenoxycarb-treated media than in controls. These results are discussed in relation to the possible gonadotropic role of juvenilehormone-like molecules in mites, and to the use of fenoxycarb as a grain protectant.     

Acute and chronic nitrite toxicity in juvenile pike-perch (Sander lucioperca) and its compensation by chloride

Pike-perch Sander lucioperca is currently considered as one of the most promising candidates for production in freshwater recirculation aquaculture systems (RAS). Here, due to the lack of studies on nitrite (NO₂^?) toxicity in pike-perch, a flow-through exposure at 0, 0.44, 0.88, 1.75, 3.5, 7, 14 and 28 mg/L NO₂^?–N was carried out to determine the acute and chronic toxicity over a period of 32 days. In juvenile pike-perch, 120 h LC₅₀ was 6.1 mg/L NO₂^?–N and at ≥ 14 mg/L NO₂^?–N all fish had died within 24 h. Chronic exposure revealed a significant build up of NO₂^? in the plasma as well as in the muscles at ≥ 0.44 mg/L NO₂^?–N peaking in fish exposed to the highest concentration of 3.5 mg/L NO₂^?–N after 32 days. Still, due to high individual variation methemoglobin (MetHb) was only significantly increased (p < 0.01) at 3.5 mg/L NO₂^?–N. No adverse effects on red blood cells (RBC) and hematocrit were observed in any of the treatments. In a second experiment, compensation of NO₂^? toxicity at increasing chloride concentrations (40 (freshwater), 65, 90, 140, 240, 440 mg/L Cl^?) was observed at a constant exposure of 10 mg/L NO₂^?–N for 42 days. At ≥ 240 mg/L Cl^?, NO₂^? build-up in blood plasma and muscle was completely inhibited. At lower Cl^? concentrations (≤ 140 mg/L), NO₂^? was significantly increased in plasma, but only insignificantly elevated in muscle due to high individual variation. MetHb was increased significantly difference only at 40 mg/L Cl^? (freshwater control) compared to the control. Again, high individual variations were observed. As a conclusion, S. lucioperca is moderately sensitive towards NO₂^? and acceptable levels in RAS should hence not exceed 1.75 mg/L NO₂^?–N to avoid MetHb formation. However, based on the 120 h LC₅₀ and a factor of 0.01 according to Sprague (1971), a NO₂^? concentration of ≤ 0.061 mg/L NO₂^?–N is considered as “safe.” Thereby, no NO₂^? should accumulate in the plasma or muscle tissue during chronic exposure. For 10 mg/L NO₂^?–N, ≥ 240 mg/L chloride compensates for NO₂^? uptake in plasma and muscle.     

Effects of fenoxycarb on development and reproduction of the Oriental cockroach, Blatta orientalis

Abstract. In a laboratory study, groups of third-instar Blatta orientalis nymphs were reared to adulthood in arenas containing fenoxycarb (48 mg a.i./m²) treated ceramic or plywood tiles. The reproductive capacity of the emergent adults was assessed by pairing each individual with two untreated individuals of the opposite sex. Oothecal production, oothecal hatch and the numbers of nymphs emergent from each hatched ootheca were monitored. Exposure to 1-day-old deposits of fenoxycarb reduced adult emergence by 45–75% in comparison with an untreated control treatment. Substantial (>40%) mortality also resulted when nymphs were exposed to deposits up to 3 months old on plywood and up to 6 months old on ceramic. Exposure to fenoxycarb significantly extended the time taken to reach adulthood of males contacting 6-month-old deposits on both surfaces, and of females contacting 1-year-old deposits on ceramic. Adult females exposed as nymphs to fenoxycarb were unable to produce oothecae, except one female laid a non-viable ootheca. Untreated females paired with treated males produced large numbers of oothecae of normal appearance but very low viability, with only 0–7.1% hatching. With marked effects on both development and reproduction in B. orientalis , fenoxycarb is a promising agent for control of this species.     

Effects of the IGRs compounds,lufenuron and fenoxycarb on Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae)

In this research work, the susceptibility of egg and four larval instars of Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae) to Insect Growth Regulators (IGRs) compounds (lufenuron 25% EC and fenoxycarb 25% WP) was determined. Different larval instar groups were separated by measuring the head capsule width and were used in all bioassays. The data were analysed with log-probit transformation using the SPSS software. The LC₅₀ for egg was determined by dipping egg masses in different concentration of either compound for 10 s, and LC₅₀ values for each group of larvae was estimated by using treated potato plants. The LC₅₀ values of lufenuron on egg, first, second and third instars of larvae were 682.65, 40.58, 47.83 and 261.38 ppm, respectively, and for fenoxycarb, these were estimated as 897.50, 35.60, 57.91 and 355.23 ppm, respectively. The LD₅₀ values of lufenuron and fenoxycarb on second instar larvae were 139.56 and 228.42 ppm, respectively.     

Effect of Soil Organic Matter Content and pH on Toxicity of Cadmium to Paronychiurus kimi (Lee) (Collembola)

The heterogeneous physico-chemical properties of soil make it difficult to normalize the toxicological effects of metals in the Collembolan species Paronychiurus kimi (Lee). Furthermore, the physico-chemical properties of soil themselves can function as limiting factors that affect population fitness. In this study, the effects of soil organic matter (OM) and pH on the biological performance of P. kimi were assessed, and the influence of these properties on cadmium toxicity to P. kimi was also assessed at the individual and population levels. The OM and pH were found to significantly influence offspring production. All toxicological values of cadmium to P. kimi showed consistent patterns of increase with increasing OM and pH values, implying a decreased toxicity. The 28-d LC₅₀ values varied from 34.9 to 115.9 mg/kg, and the 28-d EC₅₀ and 28-d r_i=0 also varied depending on the OM and pH values. These findings indicate that the OM and pH values themselves are important factors in determining not only the biological performance of P. kimi but also the toxicity of cadmium to P. kimi on the individual and population levels. Therefore, when ecological risk assessments are conducted for a certain soil, pre-examinations of the effects of abiotic factors and the selection of an appropriate endpoint must be accomplished before establishing levels of chemicals of concern (COC) for a certain species.     

Ailanthus altissima leaf extract mediated green production of zinc oxide (ZnO) nanoparticles for antibacterial and antioxidant activity

BackgroundFabricating zinc oxide nanoparticles (ZnO-NPs) from plant extracts is a cost-effective, safe, and environmentally friendly alternative to established chemical procedures. This study was aimed at the environmentally friendly fabrication of ZnO-NPs from plant extract. An additional objective was to investigate the antibacterial and antioxidant activity of these biosynthesized ZnO-NPs.MethodsZnO-NPs were fabricated using the leaf extract of Ailanthus altissima, as an eco-friendly approach. The physicochemical properties of ZnO-NPs were explored using UV–visible spectroscopy, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry. The bio-fabricated ZnO-NPs were examined for bactericidal activity against pathogenic bacteria (gram-negative and gram-positive) using the agar well diffusion technique. The antioxidant efficiency of ZnO-NPs was assessed using a DPPH assay.ResultsA surface Plasmon peak was recorded at 327 nm, showing the existence of ZnO-NPs in the reaction solution of plant extract and zinc sulfate hexahydrate salt. These nanoparticles were predominantly spherical and capped by different functional groups of biomolecules. Furthermore, ZnO-NPs showed a dose-dependent antibacterial and antioxidant activity. At 20 mg/mL ZnO-NPs, the maximum bactericidal potential of ZnO-NPs was reported against Staphylococcus aureus (201.2 mm). ZnO-NPs have an IC₅₀ value of 78.23 µg/mL, indicating that they are an effective antioxidant.ConclusionThis research presents an environmentally acceptable method for producing spherical ZnO-NPs with high antibacterial and antioxidant activities. These bio-fabricated ZnO-NPs could be a good option for applications in medicine and the healthcare industry.     

Safety of Prunus africana and Warburgia ugandensis in asthma treatment

The aim of the study was to determine the possible cytotoxicity of the aqueous stem bark extracts of Prunus africana and Warburgia ugandensis to Vero E6 cells and acute toxicity in BALB/c mice. Despite being some of the most popular medicinal plants used in Africa, little is known about the safety. In-vitro cytotoxicity tests on Vero E6 cells were investigated using MTT assay to assess the safety of the two plant extracts. Vero E6 cells on growing to confluence were incubated with different drug concentrations for 48 h for the drug to take effect. Viability of the cells was measured by a scanning multiwell spectrophotometer, color intensity being equivalent to viable cells which reduce MTT to soluble formazan crystals. This was done by determining the CC₅₀ of the extracts, CC₅₀ being the concentration of the dose of the compound/extract that kills 50% of the cells. In acute toxicity a total of 55 mice were used. Mice were divided into eleven groups of 5 mice, one group served as negative control and ten groups received oral gavage doses at 500, 889.56, 1581.6, 2812.15 or 5000 mg/kg body weight once. Mortality and other signs of toxicity were recorded within 24 h and the weights of the surviving mice taken for 14 days thereafter. P. africana had CC₅₀ of 104.08 μg/ml while W. ugandensis had CC₅₀ > 250 μg/ml and both were classified as not cytotoxic. There was no mortality observed in groups of mice that received P. africana extracts at 500 and 889.56 mg/kg body weight. There was 20%, 60% and 100% mortality observed within 24 h for mice that received P. africana extracts at 1581.64, 2812.15 and 5000 mg/kg body weight respectively. Lethal dose (LD₅₀) for P. africana was 2201.207 mg/kg body weight. W. ugandensis extracts had no mortality recorded in all dose levels and the LD₅₀ was > 5000 mg/kg body weight. The weights of mice that survived the entire 14 days in all groups increased and were not significantly different from that of controls p > 0.05. From the in vitro and in vivo studies, the two extracts were safe to use. Though with their customary value among many Kenyan communities in management of asthma among other ailments there is a need for further validation of any anti-asthmatic properties and responsible chemical compounds to augment the findings.     

Application of micro-emulsion formulation in improving the antiproliferative performance of Salix mucronata (Thunb) leaves with chemical investigation of the active extract.

This study aims to obtain micro-emulsion delivery system of safe cytotoxic drug from Salix mucronata Thunb, (Salicaceae). Dried powdered leaves were extracted with 70% ethanol (crude) and successively extracted using petroleum ether, chloroform and 80% ethanol. Acute toxicity proved its safety (LD₅₀ = 2.583 g/kg). Moreover, mutagenicity tests revealed that there is no significant difference between treated and control groups. Antioxidant potential of crude extract evaluated by DPPH, ABTS, and FRAP assays, revealed 101.19, 114.74 and 100.97 mg, respectively, calculated as Trolox equivelant (TE/g). Successive extracts showed cytotoxic activity against liver (HEPG2) and breast (MCF7) carcinoma cell lines. Different extracts were incorporated in micro-emulsion formulations (MEF) and characterized for physicochemical and drug release properties. (MEFs) were reinvestigated for improvement in cytotoxic performance to reveal enhancement in all extracts. Most promising fraction was the polar one; ethanol extract with IC₅₀ (18.2 μg/mL) against (HEPG2) dropped to (13.8 μg/mL) after formulation with better drug release action. Total phenolics and flavonoids contents were estimated as gallic acid and catechin equivalents, respectively. HPLC was performed to get insight on active fraction secondary metabolites that revealed 21 phenolic acids, catechol (16.07 mg/g) was the major and 16 flavonoids, hisperidin was the major (81.50 mg/g).     

Effects of Two Carbamates on Infective Juveniles of Stemernema carpocapsae All Strain and Steinernema feltiae Ume? Strain

Laboratory bioassays were conducted to determine the effects of two carbamates, carbofuran (an acetylcholinesterase inhibitor) and fenoxycarb (a juvenile hormone analog), on survival and infectivity of the infective juveniles (IJ) of Steinernema feltiae Umeå strain and Steinernema carpocapsae All strain. Both insecticides caused mortality of IJ in a dose-related fashion. The two nematode species were equally sensitive to fenoxycarb (LD₅₀ ca. 0.03mg/ml). Whereas IJ of S. feltiae were several orders of magnitude more sensitive to carbofuran (LD₅₀ ≤ 0.2 μg/ml) than to fenoxycarb, S. carpocapsae IJ displayed approximately the same degree of sensitivity to carbofuran (LD₅₀ 0.01-0.03 mg/ml) as they did toward fenoxycarb. Toxicity of the carbamates was the same at all exposure periods from 24 to 168 hours'' duration. Determinations of infective doses of nematodes required to cause 50% mortality of Galleria mellonella larvae showed that the infectivity of IJ that survived exposure to either of the two carbamates was not compromised by treatment.     

Responses of Corpuscles of Stannius to intra-peritoneal vitamin-D3 administration in teleost Labeo rohita (Hamilton, 1822) reared in water with two different levels of calcium concentration

This study assessed the responses of vitamin-D₃ intraperitoneally injected to Rohu, Labeo rohita @ of 0 IU/kg bw (only solvent), 100 IU/kg bw and 500 IU/kg bw reared in 20 and 40 ppm of calcium (Ca) enriched water. The cellular changes in Corpuscles of Stannius (CS) gland, serum Ca, and inorganic phosphate (P_i) level were analysed up to the 60th day. Rohu administered with 100 IU/kg bw D₃ and exposed to 40 ppm Ca-rich water exhibited notable hyperplasia of CS compared with their control groups. Notable changes with high serum Ca level (13.87 ± 0.3 mg/dl) was detected on the 5th day in fish exposed to 40 ppm Ca-rich water, while related values attained (13.74 ± 0.1 mg/dl) only after 7 days in 20 ppm Ca-rich water of 500 IU/kg bw vitamin D₃ injection. Similarly, high serum P_i level (7.66 ± 0.2 mg/dl) in 40 ppm Ca injected with D₃ at 500 IU/kg bw. The results demonstrated that the Ca homeostasis of Labeo rohita is influenced by intra-peritoneal vitamin D₃. Progressive studies should be conducted by increasing the dose of vitamin D₃ to investigate optimum dose/supplement in feed for commercially important aquaculture teleost Labeo rohita for maximum and sustainable absorption of Ca from the variable water Calcium levels to maintain Ca²⁺ homeostasis.     

Celecoxib analogs possessing a N-(4-nitrooxybutyl)piperidin-4-yl or N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridin-4-yl nitric oxide donor moiety: Synthesis,biological evaluation and nitric oxide release studies

A new group of hybrid nitric oxide (NO) releasing anti-inflammatory (AI) coxib prodrugs (NO-coxibs) wherein the para-tolyl moiety present in celecoxib was replaced by a N-(4-nitrooxybutyl)piperidyl 15a–b, or N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridyl 17a–b, NO-donor moiety was synthesized. All compounds released a low amount of NO upon incubation with phosphate buffered saline (PBS) at pH 7.4 (2.4–5.8% range). In comparison, the percentage NO released was higher (3.1–8.4% range) when these nitrate prodrugs were incubated in the presence of l-cysteine. In vitro COX-1/COX-2 isozyme inhibition studies showed this group of compounds are moderately more potent, and hence selective, inhibitors of the COX-2 relative to the COX-1 enzyme. AI structure–activity relationship data acquired showed that compounds having a MeSO₂ COX-2 pharmacophore exhibited superior AI activity compared to analogs having a H₂NSO₂ substituent. Compounds having a MeSO₂ COX-2 pharmacophore in conjunction with a N-(4-nitrooxybutyl)piperidyl (ED₅₀ = 132.4 mg/kg po), or a N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridyl (ED₅₀ = 118.4 mg/kg po), moiety exhibited an AI potency profile that is similar to aspirin (ED₅₀ = 128.7 mg/kg po) but lower than ibuprofen (ED₅₀ = 67.4 mg/kg po).     

Toxicity of seventeen insecticides to Camponotus sericeus (Hymenoptera: Formicidae)

The success of chemical control depends on toxicity of insecticides against insect pests. Camponotus sericeus is an important urban pest with the ability to cause substantial damage to wooden structures, but there is a lack of information on toxicity of insecticides against C. sericeus. To determine the insecticide toxicity, workers of C. sericeus were exposed to 17 insecticides from different classes: carbamate (methomyl, bendiocarb), organophosphate (chlorpyrifos, profenofos, temephos), pyrethroid (bifenthrin, deltamethrin, permethrin), neonicotinoid (acetamiprid, imidacloprid, thiamethoxam), avermectin (abamectin, emamectin), pyrrole (chlorfenapyr), phenylpyrazole (fipronil), and spinosyn (spinosad and spinetoram), via residual bioassay method. The LC₅₀ ranged from: 0.15 to 0.20 µg/vial for carbamates, 0.09 to 0.27 µg/vial for organophosphates, 0.09 to 0.44 µg/vial for pyrethroids, 0.02 to 0.67 µg/vial for neonicotinoids, 0.54 to 0.82 µg/vial for avermectins, 0.78 µg/vial for pyrrole, 0.62 µg/vial for phenylpyrazole, and 1.96 to 2.05 µg/vial for spinosyns. Overall, acetamiprid was the most toxic one among the tested insecticides followed by permethrin, temephos, profenofos, bendiocarb and methomyl, while spinosad and spinetoram were the least toxic insecticides. Considering the potential toxicity of different insecticides against C. sericeus, future studies could investigate the practical application of these insecticides in order to design an effective management plan.     

Design,synthesis and anticonvulsant activity of new hybrid compounds derived from N-phenyl-2-(2,5-dioxopyrrolidin-1-yl)-propanamides and -butanamides

The focused library of 21 new N-phenyl-2-(2,5-dioxopyrrolidin-1-yl)propanamide, 2-(3-methyl-2,5-dioxopyrrolidin-1-yl)propanamide, and 2-(2,5-dioxopyrrolidin-1-yl)butanamide derivatives as potential new hybrid anticonvulsant agents was synthesized. These hybrid molecules were obtained as close analogs of previously described N-benzyl derivatives and fuse the chemical fragments of clinically relevant antiepileptic drugs such as ethosuximide, levetiracetam, and lacosamide. The initial anticonvulsant screening was performed in mice (ip) using the ‘classical’ maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) tests, as well as in the six-Hertz (6 Hz) model of pharmacoresistant limbic seizures. Applying the rotarod test, the acute neurological toxicity was determined. The broad spectra of activity across the preclinical seizure models in mice (ip) displayed compounds 4, 5, 11, and 19. The most favorable anticonvulsant properties demonstrated 4 (ED₅₀ MES = 96.9 mg/kg, ED₅₀ scPTZ = 75.4 mg/kg, ED₅₀ 6 Hz = 44.3 mg/kg) which showed TD₅₀ = 335.8 mg/kg in the rotarod test that yielded satisfying protective indexes (PI MES = 3.5, PI scPTZ = 4.4, PI 6 Hz = 7.6). Consequently, compound 4 revealed comparable or better safety profile than model antiepileptic drugs (AEDs): ethosuximide, lacosamide, and valproic acid. In the in vitro assays, compound 4 was observed as relatively effective binder to the neuronal voltage-sensitive sodium and diltiazem site of L-type calcium channels.     

Growth performance and starch utilization in common carp (Cyprinus carpio L.) in response to dietary chromium chloride supplementation

A nutrition trial was conducted on juvenile common carp (Cyprinus carpio), initial mean body weight 15 ± 0.4 g within a controlled facility at 25 ± 0.5 °C. Six diets containing various levels of supplementary Cr (0, 0.2, 0.5, 1.0, 1.5, and 2.0) mg Cr/kg of diet as Cr chloride hexahydrate were fed to carp for a period of 10 weeks. Lower growth performance was observed in fish fed on the control diet and the diet supplemented with the highest level of Cr (2.0 mg Cr/kg). Although fish fed 0.5 mg Cr/kg showed the best growth performance, this was not significantly different (P > 0.05) from fish fed 1.0 mg Cr/kg. The regression of plasma glucose concentration was linear (R² = 0.97 and P value = 0.001) as the Cr content of the diet increased (up to 1.5 mg Cr/kg).Cr carcass content was elevated with an increasing level of dietary Cr supplementation up to 1.5 mg Cr/kg; but fish fed on the diet supplemented with the highest level of Cr (2.0 mg Cr/kg) showed a decrease in Cr carcass content.Histological examination to evaluate the impact of different Cr supplementation on liver and gut tissues showed notable changes. The higher level of Cr (2.0 mg Cr/kg) in the diet gave rise to elevated hepatocyte vacuolization and changes in gut tissue morphology.It appeared that Cr chloride significantly improved growth within a defined range (0.2–1.5) mg Cr/kg without any negative impact, while 2.0 mg Cr/kg in carp diet seems to be the threshold for the initiation of toxicity.