Nonspecific Esterase Activity Research Articles

Biochemical and molecular analyses of insecticide resistance in greenhouse populations of Bemisia tabaci (Hemiptera: Aleyrodidae) in Türkiye

The sweet potato/cotton whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the most destructive vegetable pests in greenhouses in Türkiye. While the preferred method of control primarily relies on insecticides such as neonicotinoids, organophosphates and pyrethroids, their intensive use has caused whiteflies to rapidly become resistant. Samples were collected from 13 Turkish B. tabaci greenhouse populations. Bioassays from the Marmara Region identified as high as a 53-fold increase in resistance to chlorpyrifos-ethyl, a 303-fold increase to imidacloprid and a 282-fold increase to acetamiprid. Bioassays in the Central Anatolia Region reported a 76-fold increase in resistance to deltamethrin and—15-fold increase to thiamethoxam. Most of the populations showed cross-resistance for neonicotinoids. All collected B. tabaci populations were determined to be MEAM 1 (also referred to as biotype B) for diagnostic band E0.14. The E0.14 esterase variant that helps to diagnose biotype B insects was found in all individuals from field populations. Almost all populations showed higher non-specific esterase, glutathione-S-transferase (GST) and monooxygenase activity when compared to susceptible SUD-S population. AChE insensitivity assays for individual B. tabaci suggest a target-site modification as a mechanism of resistance to chlorpyrifos-ethyl. This is the first report of AChE variants identified based on their sensitivities to chlorpyrifos ethyl-oxon and pirimicarb in Turkish B. tabaci populations. Fixed ace mutations in the target-site of organophosphates and pyrethroids were identified in six populations. Resistance to organophosphates and neonicotinoids were at least partially related to both ace mutations and insensitive AChE and monooxygenase activities, respectively. The results will help develop effective resistance management programs of B. tabaci in Türkiye.Graphical

Opioid infusions at different times of the day produce varying degrees of opioid-induced hyperalgesia

BackgroundOpioids are metabolised by enzymes the activities of which vary with the circadian rhythm. We examined whether opioid infusions administered at different times of the day produce varying degrees of opioid-induced hyperalgesia (OIH) in animal experiments and clinical studies. MethodsMale Sprague–Dawley rats received remifentanil infusions (1 μg kg−1·min−1 for 1 h) at Zeitgeber times (ZT) 0, 4, 8, 12, 16, or 20 h. Rhythmicity of mechanical hypersensitivity was assayed after the infusion. Mechanical hypersensitivity, drug concentration, and metabolic enzyme activity of Wistar rats that received sufentanil (10 μg kg−1; four consecutive i.p. injections at 15-min intervals) or remifentanil infusion at ZT0 or ZT8 were assayed. Sixty patients who underwent abdominal laparoscopic surgery under general anaesthesia received remifentanil infusion (0.15 μg kg−1 min−1) and sufentanil injection (0.2 μg kg−1) at induction and skin incision, respectively. Postoperative pressure pain sensitivity, pain Numeric Rating Scale (NRS), drug concentrations, and nonspecific esterase activity were assessed. ResultsSprague–Dawley rats that received remifentanil infusion exhibited a robust rhythmic paw withdrawal threshold (JTK_CYCLE: P=0.001, Q=0.001, Phase=26). Wistar rats infused with remifentanil or sufentanil at ZT8 exhibited greater OIH (P<0.001) than those infused at ZT0, with higher blood concentrations (P<0.001) and lower metabolic enzyme activities (P=0.026 and P=0.028, respectively). Patients in the afternoon group exhibited higher pressure pain sensitivity at forearm (P=0.002), higher NRS (P<0.05), higher drug concentrations (sufentanil: P=0.037, remifentanil: P=0.005), and lower nonspecific esterase activity (P=0.024) than the morning group. ConclusionsOpioid infusions administered at different times of day produced varying degrees of OIH, possibly related to circadian rhythms of metabolic enzyme activities. Clinical trial registrationNCT 05234697.

Insecticide Resistance and Metabolic Mechanisms in Aedes aegypti from Two Agrosystems (Vegetable and Cotton Crops) in Côte d'Ivoire.

Background: The emergence of insecticide resistance in Aedes vectors mosquitoes poses a real challenge for arboviral-borne disease control. In Côte d'Ivoire, data are available on phenotypic resistance and the presence of kdr mutations in Aedes aegypti. Therefore, information on metabolic resistance in Aedes populations is very scarce. Here, we assessed the insecticide resistance status of Ae. aegypti in periurban and rural areas of Côte d'Ivoire, and we investigated the role of detoxification enzymes as possible resistance mechanisms. Materials and Methods: Aedes mosquito eggs were collected between June 2019 to April 2021 in two agricultural sites. Adults of Ae. aegypti were tested using World Health Organization tube assays, with seven insecticides belonging to pyrethroids, organochlorines, carbamates, and organophosphates classes. We determined the knockdown times (KdT50, KdT95) and resistance ratios of pyrethroids in natural populations. The synergist piperonyl butoxide (PBO) was used to investigate the role of enzymes in resistance. Biochemical assays were performed to detect potential increased activities in mixed-function oxidase levels, nonspecific esterases (NSEs), and glutathione S-transferases. Results: The results showed that Ae. aegypti populations were resistant to five insecticides with mortality of 46% and 89% for 0.75% permethrin, 68% and 92% for 0.05% deltamethrin, 57% and 89% for lambda-cyhalothrin, 41% and 47% for dichlorodiphenyltrichloroethane (DDT), 82% and 91% for chlorpyrifos-methyl in Songon-Agban and Kaforo, respectively. Susceptibility to carbamates was observed in our study sites. After exposure to PBO, the susceptibility of Ae. aegypti to pyrethroids and DDT was partially restored in Songon-Agban. Whereas in Kaforo, none increase of the mortality rates of Ae. aegypti for these four insecticides was observed after exposure to PBO. Increased activity of NSE (α-esterases) was found in Songon-Agban compared with the reference susceptible strain. Conclusion: These findings provide valuable information to support decisions for vector control strategies in Cote d'Ivoire. Also, we highlight the need for the monitoring of insecticide resistance management in Aedes vectors.

Effect of Microplastics on the Activity of Digestive and Oxidative-Stress-Related Enzymes in Peled Whitefish (Coregonus peled Gmelin) Larvae.

Microplastics (MPs) are emergent pollutants in freshwater environments and may impact aquatic organisms, including those of nutritional value. The specific activities of digestive and antioxidant enzymes can be used as good bioindicators of the potential effects of MPs on fish in case of waterborne MP contamination. In this study, we used fluorescent polystyrene microplastics (PS-MPs) to analyze the alterations in enzyme activities in larvae of Coregonus peled Gmelin (peled or Northern whitefish), one of the most valuable commercial fish species of Siberia. Our results indicate that peled larvae can ingest 2 µm PS microspheres in a waterborne exposure model. A positive correlation (rs = 0.956; p < 0.01) was found between MP concentration in water and the number of PS microspheres in fish guts, with no significant differences between 24 h and 6-day exposure groups. The ingestion of MPs caused alterations in digestive enzyme activity and antioxidant responses at the whole-body level. The presence of PS-MPs significantly stimulated (p < 0.05) the specific activity of α-Amylase and non-specific esterases in peled larvae after 24 h. However, a pronounced positive effect (p < 0.05) of MPs on the activity of pancreatic trypsine and bile salt-activated lipase was only found after 6 days of exposure compared to after 24 h. Intestinal membrane enzyme aminopeptidase N was also stimulated in the presence of PS-MPs after 6-day exposure. We also observed a significant increase in the specific activity of catalase in peled larvae after 6 days of exposure, which indicates the MP-induced modulation of oxidative stress. Taken together, these results highlight the potential impact of environmental MPs on northern commercial fish, their importance for estimating fish stocks, and the sustainability of freshwater ecosystems.

Histochemical research of enzymes involved in cellular digestion in the digestive tract of tub gurnard, Chelidonichthys lucerna.

The tub gurnard Chelidonichthys lucerna (Linnaeus, 1758), Triglidae, is an opportunistic, demersal carnivorous fish. Data on the digestive enzymes of tub gurnard have not been reported in the literature. Therefore, the aim of this research was to investigate the distribution and intensity of alkaline phosphatase, acid phosphatase, non-specific esterase, and aminopeptidase in the digestive tract of tub gurnard. To investigate data about those enzymes tissue samples of the esophagus, anterior and posterior part of the stomach, pyloric caeca, anterior, middle and posterior part of the intestine proper, and rectum were taken. Azo-coupling methods were used to detect the enzymatic reactions. The intensities of the reactions were measured using ImageJ software. Alkaline phosphatase, acid phosphatase, and non-specific esterase activities were found in all parts of the digestive tract. The brush border of the pyloric caeca and intestine proper were the main sites of alkaline phosphatase reaction, with intensity decreasing toward the posterior parts of the digestive tract. The high intensities of acid phosphatase were found in the epithelium of the anterior part of the stomach, pyloric caeca, anterior part of the intestine proper, and in the rectum. The intensity of non-specific esterase was mainly increased from the anterior to the posterior parts of the digestive tract. Aminopeptidase activity was found in the esophagus, pyloric caeca, and intestine proper. Our results suggest that the entire digestive tract of the tub gurnard is involved in the digestion and absorption of dietary components.

Lymphocyte enzymes as an indicator of immune response activity in ixodid tick-borne borreliosis

BACKGROUND: Acute ixodid tick-borne borreliosis tends to turn into a protracted and chronic course. This suggests studying the causes of the violation of the immune status of a sick person. The central structural unit of immunity is the lymphocyte. It is known that the formation of specific T-lymphocyte subpopulations is based on the central role of IL-2, leading to the restructuring of cellular metabolic pathways. The regulation of signaling pathways and lymphocyte metabolism primarily determines disease outcomes.&#x0D; AIM: This study determines the pathogenetic mechanisms of the infectious and inflammatory processes in the erythemal form of acute ixodid tick-borne borreliosis based on the study of the lymphocytic lysosomal enzyme activity, the level of IL-2, and the clinical disease manifestations.&#x0D; MATERIALS AND METHODS: The main group is represented by 609 patients hospitalized at the Krasnodar City Clinical Hospital from 2010 to 2019. The study group comprised 45 patients with an erythemal form of acute ixodid tick-borne borreliosis. In the dynamics of the disease, the level of IL-2 and the cytochemical activity of acid phosphatase and non-specific alpha naphthyl esterase of lymphocytes were determined.&#x0D; RESULTS: During the height of ixodid tick-borne borreliosis, a decrease in the cytochemical activity of hydrolytic enzymes of lymphocytes was noted compared with the control group. IL-2 levels had a high dispersion and were associated with clinical disease manifestations. A low level of IL-2 correlated with a decrease in the activity of alpha-naphthyl esterase lymphocytes. During the period of convalescence, there was a restoration of lymphocytic enzymatic activity and an increase in the number of cells with a pronounced activity of alpha-naphthyl esterase, typical of T-lymphocytes with killer activity.&#x0D; CONCLUSION: The hydrolytic enzymes of the lysosomes of acid phosphatase and alpha-naphthyl esterase lymphocytes enable judging the intensity of intracellular metabolic processes and, combined with clinical disease symptoms and IL-2 activity, are indicators of the state of the immune process, supplementing the results of traditional immunological studies in patients with the erythema form of acute ixodid tick-borne borreliosis. The predominance of enzymatically inactive forms of T-lymphocytes in the acute period of the disease reflects a specific deficiency of T-cell immunity.

A comparison of amphibian (Xenopus laevis) tadpole and adult frog macrophages

The amphibian declines are compounded by emerging pathogens that often preferentially target distinct amphibian developmental stages. While amphibian immune responses remain relatively unexplored, macrophage (Mφ)-lineage cells are believed to be important to both amphibian host defenses and to their pathogen infection strategies. As such, a greater understanding of tadpole and adult amphibian Mφ functionality is warranted. Mφ biology is interdependent of interleukin-34 (IL-34) and colony-stimulating factor-1 (CSF-1) cytokines and we previously showed that CSF-1- and IL-34-derived Mφs of the Xenopus laevis frog are morphologically, transcriptionally, and functionally distinct. Presently, we directly compared the cytology and transcriptomes of X. laevis tadpole and frog CSF-1- and IL-34-Mφs. Our results indicate that tadpole and frog CSF-1-Mφs possess greater non-specific esterase activity, typically associated with Mφ-lineage cells. By contrast, both tadpole and frog IL-34-Mφs have greater specific esterase activity, which is typically attributed to granulocyte-lineage cells. Our comparisons of tadpole CSF-1-Mφ transcriptomes with those of tadpole IL-34-Mφs indicate that the two tadpole populations possess significantly different transcriptional profiles of immune and non-immune genes. The frog CSF-1-Mφ gene expression profiles are likewise significantly disparate from those of frog IL-34-Mφs. Compared to their respective tadpole Mφ subtypes, frog CSF-1- and IL-34-Mφs exhibited greater expression of genes associated with antigen presentation. Conversely, compared to their frog Mφ counterparts, tadpole CSF-1- and IL-34-Mφs possessed greater levels of select Fc-like receptor genes. Presumably, these cytological and transcriptional differences manifest in distinct biological roles for these respective tadpole and frog Mφ subtypes.

Influence of Food Density on Digestive Enzyme Activities in Newly Hatched Larvae of the Spiny Lobster, Panulirus ornatus

There is considerable interest in developing hatchery techniques for the tropical spiny lobster, Panulirus ornatus. Although some progress has been made toward identifying effective foods and feeding protocols for this species, the density at which food is first provided to larvae varies greatly in practice. This study examined relationships between food density and the activities of major digestive enzymes in P. ornatus to evaluate larval feeding protocols from a nutrient utilization perspective. Specifically, activities of α-amylase, nonspecific esterase, and trypsin-like protease were quantified to determine the response of newly hatched larvae of P. ornatus to provision of Artemia nauplii at three different densities. Results showed that food density significantly (P < 0.01) influenced α-amylase and nonspecific esterase activities during the first 24 h of feeding, but had minimal effect (P ≥ 0.09) on trypsin-like protease activities. Based on enzyme activities, there is no advantage to increasing food densities above 2.5 Artemia mL–1, but when food density decreased to 0.5 Artemia mL–1, the availability of dietary nutrients became limiting. An optimal density at which to provide Artemia nauplii to newly hatched larvae of P. ornatus is likely between 0.5 and 2.5 Artemia mL–1. The comparative analyses of enzyme activities presented in this study represents an innovative approach to identify potentially excessive or insufficient food densities quickly (within 24 h) for larval crustaceans.

Antibacterial Efficacy and Mechanisms of Curcumin-Based Photodynamic Treatment against Staphylococcus aureus and Its Application in Juices.

Antimicrobial Photodynamic Treatment (aPDT) is a non-thermal sterilization technology, which can inactivate common foodborne pathogens. In the present study, photodynamic inactivation on Staphylococcus aureus (S. aureus) with different concentrations of curcumin and light dose was evaluated and the mechanisms were also investigated. The results showed that curcumin-based aPDT could inactivate S. aureus cells by 6.9 log CFU/mL in phosphate buffered saline (PBS). Moreover, the modified Gompertz model presented a good fit at the inactivation data of S. aureus. Photodynamic treatment caused cell membrane damage as revealed by analyzing scanning electron microscopy (SEM) images. Leakage of intracellular constituents further indicated that cell membrane permeability was changed. Flow cytometry with double staining demonstrated that cell membrane integrity and the activity of nonspecific esterase were destroyed. Compared with the control group, intracellular reactive oxygen species (ROS) levels caused by photodynamic treatment significantly increased. Furthermore, curcumin-based aPDT reduced S. aureus by 5 log CFU/mL in juices. The color of the juices was also tested using a Chromatic meter, and it was found that b* values were the most markedly influenced by photodynamic treatment. Overall, curcumin-based aPDT had strong antibacterial activity against S. aureus. This approach has the potential to remove foodborne pathogens from liquid food.

Histochemical Study of the Harderian Gland of Pati Duck of Assam

Background: Pati duck population constitutes a major indigenous non-descript economically important duck variety in Assam. Harderian gland acts as a part of the head associated lymphoid tissue (HALT) and provides local innate immunity to the upper respiratory system, to the eye and oral cavity. Since literature on histoenzymic or histochemical study of harderian gland of Pati duck was scant, hence the present study was designed to establish the basic histoenzymic details on harderian gland of Pati duck of Assam. Methods: The present study was conducted on total forty five (45) Pati duck of Assam. Ducks were divided into five groups: 0, 4, 16, 24, and 42 weeks. For histochemical parameters, tissue samples were preserved in deep freeze maintained at -80oC (except for PAS-alcian blue, where paraffin sections were utilized) immediately after collection. The preserved tissue samples were shifted directly to cryostat microtome maintained at -22oC. The frozen sections were cut at 7 µm thickness and were collected on clean slides and were treated as per the method of Singh and Sulochana (1978). Result: Histochemical studies revealed that the reaction of Alkaline phosphatase enzyme was mildin Harderian land of Pati duck. The reaction of the acid phosphatase was absent. The Adenosine triphosphatase (ATPase) activity was observed moderate in all the age groups. The activity of non specific esterase was observed strong in all the age groups. The periodic acid-Schiff (PAS-Alcian Blue 2.5 pH) stain revealed positive reaction in all the age groups which indicated the presence of acid sulfated mucosubtances in the cells.

Review of remimazolam and sedatives in the intensive care unit.

Remimazolam is a novel intravenous ultra-short acting benzodiazepine that has the potential of being a safe and effective new sedative for use in intensive care unit (ICU) settings. Because remimazolam metabolizes rapidly by being hydrolyzed to an inactive metabolite (CNS 7054) through non-specific tissue esterase activity, specific dosing adjustment for older adults and for patients with renal or hepatic impairment patients (except for those with severe hepatic impairment) is not required. In addition, research has shown that remimazolam may be reversed by administration of flumazenil, as its half time was sufficiently short compared to flumazenil. It shows a lower incidence of cardiorespiratory depression, less injection pain, and no fatal complications such as propofol infusion syndrome and malignant hyperthermia of inhalational anesthetics. Future studies to study the suitability of remimazolam for managing the sedation of ICU patients who need sedation for a long time over several days is required.

Responses of digestive enzyme profiles to various scenarios of food availability in newly-hatched Stage I phyllosoma larvae of the tropical spiny lobster Panulirus ornatus

Stage I phyllosoma larvae of the spiny lobster Panulirus ornatus hatch in tropical oceanic waters with limited and variable food resources. To better understand how these larvae cope with food deprivation, this study examined specific (mU mg−1 protein) and total (mU larva−1) activities of major digestive enzymes (i.e., α-amylase, non-specific esterase, trypsin-like protease) during a series of ex situ experiments. Specifically, temporal changes in enzyme profiles were examined in three experiments simulating scenarios in which phyllosoma hatch and begin development in an environment where (1) prey is either continuously present or absent; (2) prey is initially present, but subsequently absent; (3) prey is initially absent, but subsequently present. Results indicated that the accessibility of suitable prey provides an overarching influence on digestive enzyme activities and substrate utilisation in Stage I phyllosoma of P. ornatus, with enzymatic responses to both intermittent prey availability and food deprivation being influenced by their nutritional history. In the absence of prey, larval digestive enzyme activities (mU larva−1) initially remained static from hatch but eventually declined with extended food deprivation. When prey became available, enzyme activities increased, with delayed access to prey having minimal impact on this enzymatic response. Furthermore, phyllosoma were able to adjust α-amylase and non-specific esterase activities (within 8 h) in response to the disappearance of prey, demonstrating adaptive changes to endure periods of food deprivation that were based on their nutritional history. The ability of phyllosoma to regulate enzyme activities from hatch is an important physiological strategy allowing them to survive in an environment characterised by highly variable zooplankton biomass and abundance, and explains why diets that differ greatly in nutrient composition have consistently been found effective for rearing phyllosoma in captivity.

Response mechanism of Chlamydomonas reinhardtii to nanoscale bismuth oxyiodide (nano-BiOI): Integrating analysis of mineral nutrient metabolism and metabolomics

Nanoscale bismuth oxyiodide (nano-BiOI) is widely studied and applied in environmental applications and biomedical fields, with the consequence that it may be deposited into aquatic environments. However, the impact of nano-BiOI on aquatic ecosystems, especially freshwater microalga, remains limited. Herein, the nano-BiOI was synthesized and its response mechanism towards microalga Chlamydomonas reinhardtii was evaluated. Results showed that a low concentration of nano-BiOI (5 mg/L) could stimulate algal growth at the early stage of stress. With the increase in concentration, the growth rate of algal cells was inhibited and showed a dose effect. Intracellular reactive oxygen species (ROS) were significantly induced and accompanied by enhanced lipid peroxidation, decreased nonspecific esterase activity, and significantly upregulated glutathione S-transferase activity (GST) activity. Mineral nutrient metabolism analysis showed that nano-BiOI significantly interfered with the mineral nutrients of the algae. Non-targeted metabolomics identified 35 different metabolites (DEMs, 22 upregulated, and 13 downregulated) under 100 mg/L BiOI stress. Metabolic pathway analysis demonstrated that a high concentration of nano-BiOI significantly induced metabolic pathways related to amino acid biosynthesis, lipid biosynthesis, and glutathione biosynthesis, and significantly inhibited the sterol biosynthesis pathway. This finding will contribute to understanding the toxicological mechanisms of nano-BiOI on C. reinhardtii.

Ontogenetic variation in digestive enzyme activities within embryos and newly-hatched larvae of the tropical spiny lobster, Panulirus ornatus

While there is considerable interest in aquaculture of spiny lobsters (Palinuridae), limited knowledge of nutritional requirements during early life stages remains a major impediment to successful hatchery culture. To better determine endogenous nutrient utilisation during the early life stages of the tropical spiny lobster, Panulirus ornatus, we examined ontogenetic variation in digestive enzyme activities within developing embryos and newly-hatched phyllosoma in the absence of an exogenous food source. Specifically, α-amylase, non-specific esterase, and trypsin-like protease activities were quantified to indicate the relative importance of macronutrients (i.e., carbohydrate, lipid, and protein) and gauge the digestive potential of newly-hatched phyllosoma during transition from endogenous to exogenous nutrient sources. Ontogenetic variation in digestive enzyme activities indicated that lipid, protein, and carbohydrate were sequentially utilised by embryos. Early increase in non-specific esterase activity suggests that lipid is the most critical macronutrient for early embryonic development, with protein and carbohydrate becoming increasingly utilised shortly before and after hatching. The observed peak in trypsin-like protease activity during the first day post-hatch presumably allows phyllosoma to make best use of dietary items that are high in protein at first-feeding. In the absence of an exogenous food source after hatching, changes in digestive enzyme activities suggest that a metabolic shift from protein to lipid occurred, coinciding with the timing of the ‘point-of-no-return’ for Stage I phyllosoma of P. ornatus. Our results highlight the importance of providing an exogenous protein-rich food source to phyllosoma soon after hatch and provide a foundation for further study into broodstock nutrition and egg quality of this species.

Histochemical Studies on Post Natal Development of Gut Associated Lymphoid Tissue (GALT) of Intestine of Pati Duck (Anas platyrhynchos domesticus) of Assam

Background: The Pati duck constitutes a major indigenous duck variety in the state of Assam. The study of the gut associated lymphoid tissue (GALT) of Pati duck of Assam is of great value in regard to normal academic and bio-medical research aspects. It is also pre-requisite for correct diagnosis and evaluating the treatment of certain diseases like duck virus enteritis, duck cholera, aflatoxicosis, botulism etc, caused by different types of pathogens, food poisoning and food allergy. Methods: The study was conducted on Pati duck of Assam in where 45 numbers of ducks were selected by irrespective of sex at different stages of development. The birds were divided into five groups depending on its age viz., 1st week, 4th week, 16th week, 24th week and 42nd weeks old. The pieces of gut having lymphoid tissue or Peyer’s patches were collected immediately after slaughter. Samples were made cryosections (-20oC) at 10µm in thickness and were temporally stored at (-22oC). The histochemical staining was done after that. Result: The acid phosphatase activity was weak in the lymphoid follicles of 1st and 4th week of age of Pati duck, while its activity was moderate in 16th, 24th and 42th week of age.The alkaline phosphatase activity was moderate reaction in the lymphoid follicles of 1st and 4th week of age of Pati duck, while its activity was intense in 16th, 24th and 42th week of age of duck. The lymphoid follicles of both Peyer’s patches and solitary lymphoid nodules were showed moderate activity for adenosine tri-phosphatase activity in 1st and 4th week old Pati duck and strong activity in 16th, 24th and 42th week of age of Pati duck, respectively. The lymphoid nodules of intestine showed strong reaction for non-specific esterase activity in all the age groups of Pati duck.

Neuroprotective Effect of 1,4-Naphthoquinones in an In Vitro Model of Paraquat and 6-OHDA-Induced Neurotoxicity.

Targeted screening using the MTT cell viability test with a mini-library of natural and synthetic 1,4-naphthoquinones and their derivatives was performed in order to increase the survival of Neuro-2a neuroblastoma cells in in vitro paraquat and 6-hydroxydopamine models of Parkinson’s disease. As a result, 10 compounds were selected that could protect neuronal cells from the cytotoxic effects of both paraquat and 6-hydroxydopamine. The five most active compounds at low concentrations were found to significantly protect the activity of nonspecific esterase from the inhibitory effects of neurotoxins, defend cell biomembranes from lytic destruction in the presence of paraquat and 6-hydroxydopamine, and normalize the cell cycle. The protective effects of these compounds are associated with the suppression of oxidative stress, decreased expression of reactive oxygen species and nitric oxide formation in cells and normalization of mitochondrial function, and restoration of the mitochondrial membrane potential altered by neurotoxins. It was suggested that the neuroprotective activity of the studied 1,4-NQs is attributable to their pronounced antioxidant and free radical scavenging activity and their ability to reduce the amount of reactive oxygen species formed by paraquat and 6-hydroxydopamine action on neuronal cells. The significant correlation between the neuroprotective properties of 1,4-naphthoquinones and Quantitative Structure–Activity Relationship descriptors describing the physicochemical properties of these compounds means that the hydrophobicity, polarity, charge, and shape of the molecules can be of decisive importance in determining the biological activity of studied substances.

Antibacterial activity and mechanism of high voltage electrostatic field (HVEF) against Staphylococcus aureus in medium plates and food systems

Inhibitory effects of three kinds of electric fields, high voltage electrostatic field (HVEF), alternating electric field (HVAEF) and prick electrostatic field (HVPEF) against Staphylococcus aureus (S. aureus) were investigated in medium plates and food systems. The results showed that S. aureas was more sensitive to HVPEF than to HVEF and HVAEF, especially when growing on the surface of solid culture medium, and the mortality rate was over 99.9% when the voltage was higher than 10 kV. The kinetics study showed that with the increase of processing time, the mortality rate increased linearly and then plateaued. The change of cell morphology and leakage of intracellular materials indicated that HVPEF damaged cell membrane and increased the membrane permeability. Flow cytometry with double staining demonstrated cell membrane integrity was destroyed, and nonspecific esterase activity was reduced by HVPEF. The intracelluar reactive oxygen species (ROS) generated by HVPEF increased significantly compared with the control as voltage rose. And the effect of HVPEF on S. aureus incubated on food surface was further studied, the mortality rate increased with the increase of electric voltage and treatment time, the rates attained 98.3 ± 0.2% (Salmon), 98.6 ± 0.3% (Griskin), 99.8 ± 0.1% (Cheese) and 99.6 ± 0.1% (Sausage) at 13 kV for 30 min, respectively. HVPEF had great antibacterial effects against S. aureus on solid surfaces, and the results provided a theoretical guidance for the possible application of HVPEF technology in non-thermal food sterilization.

Exploring the relationships between amphibian (Xenopus laevis) myeloid cell subsets

The differentiation of distinct leukocyte subsets is governed by lineage-specific growth factors that elicit disparate expression of transcription factors and markers by the developing cell populations. For example, macrophages (Mφs) and granulocytes (Grns) arise from common granulocyte-macrophage progenitors in response to distinct myeloid growth factors. In turn, myelopoiesis of the Xenopus laevis anuran amphibian appears to be unique to other studied vertebrates in several respects while the functional differentiation of amphibian Mφs and Grns from their progenitor cells remains poorly understood. Notably, the expression of colony stimulating factor-1 receptor (CSF-1R) or CSF-3R on granulocyte-macrophage progenitors marks their commitment to Mφ- or Grn-lineages, respectively. CSF-1R is activated by the colony stimulating factor-1 (CSF-1) and interleukin (IL-34) cytokines, resulting in morphologically and functionally distinct Mφ cell types. Conversely, CSF-3R is ligated by CSF-3 in a process indispensable for granulopoiesis. Presently, we explore the relationships between X. laevis CSF-1-Mφs, IL-34-Mφs and CSF-3-Grns by examining their expression of key lineage-specific transcription factor and myeloid marker genes as well as their enzymology. Our findings suggest that while the CSF-1- and IL-34-Mφs share some commonalities, the IL-34-Mφs possess transcriptional patterns more akin to the CSF-3-Grns. IL-34-Mφs also possess robust expression of dendritic cell-associated transcription factors and surface marker genes, further underlining the difference between this cell type and the CSF-1-derived frog Mφ subset. Moreover, the three myeloid populations differ in their respective tartrate-resistant acid phosphatase, specific- and non-specific esterase activity. Together, this work grants new insights into the developmental relatedness of these three frog myeloid subsets.

Monitoring Insecticide Susceptibility in Aedes Aegypti Populations from the Two Biggest Cities, Ouagadougou and Bobo-Dioulasso, in Burkina Faso: Implication of Metabolic Resistance.

In West Africa, Aedes aegypti remains the major vector of dengue virus. Since 2013, dengue fever has been reemerging in Burkina Faso with annual outbreaks, thus becoming a major public health problem. Its control relies on vector control, which is unfortunately facing the problem of insecticide resistance. At the time of this study, although data on phenotypic resistance were available, information related to the metabolic resistance in Aedes populations from Burkina Faso remained very scarce. Here, we assessed the phenotypic and the metabolic resistance of Ae. aegypti populations sampled from the two main urban areas (Ouagadougou and Bobo-Dioulasso) of Burkina Faso. Insecticide susceptibility bioassays to chlorpyriphos-methyl 0.4%, bendiocarb 0.1% and deltamethrin 0.05% were performed on natural populations of Ae. aegypti using the WHO protocol. The activity of enzymes involved in the rapid detoxification of insecticides, especially non-specific esterases, oxidases (cytochrome P450) and glutathione-S-transferases, was measured on individual mosquitos. The mortality rates for deltamethrin 0.05% were low and ranged from 20.72% to 89.62% in the Bobo-Dioulasso and Ouagadougou sites, respectively. When bendiocarb 0.1% was tested, the mortality rates ranged from 7.73% to 71.23%. Interestingly, in the two urban areas, mosquitoes were found to be fully susceptible to chlorpyriphos-methyl 0.4%. Elevated activity of non-specific esterases and glutathione-S-transferases was reported, suggesting multiple resistance mechanisms involved in Ae. aegypti populations from Bobo-Dioulasso and Ouagadougou (including cytochrome P450). This update to the insecticide resistance status within Ae. aegypti populations in the two biggest cities is important to better plan dengue vectors control in the country and provides valuable information for improving vector control strategies in Burkina Faso, West Africa.

Sublethal Doses of Essential Oils Impact Growth and Esterase Levels in German Cockroach (Blattodea: Ectobiidae) with and without Symbiotic Bacteria

The inhibition by three essential oils of the growth and esterase production of German cockroaches, Blattella germanica (L.) (Blattodea: Ectobiidae), with and without symbiotic bacteria, was determined in laboratory assays. Essential oils extracted from Lilium brownii var. viridulum Baker, Croton tiglium L., and Lonicera japonica Thunberg were mixed with a powdered rat food at a 10% concentration and fed to cockroach nymphs. Body mass and body length were measured in adults in all three treatments. Acetylcholinesterase and nonspecific esterase activities were compared between the Lilium and Croton essential oil treatments. The nonlethal doses of these essential oils reduced cockroach growth, while the growth of the females lacking symbiotic bacteria was significantly reduced when fed the diet containing Lilium essential oil. Lilium and Croton essential oils significantly inhibited esterase activity. Our results indicate that symbiotic gut bacteria might be involved in mediating detoxification in the German cockroach.