An overexpressed cytochrome P450 CYP439A1v3 confers deltamethrin resistance in Laodelphax striatellus Fallén (Hemiptera: Delphacidae)

Deltamethrin resistance in Laodelphax striatellus had been associated with its oxidative detoxification by overexpression of four cytochrome P450 monooxygenases like CYP353D1v2, CYP6FU1, CYP6AY3v2, and CYP439A1v3. The first three P450s have been validated for insecticide-metabolizing capability and only CYP6FU1 was found to degrade deltamethrin. In this study, an investigation was conducted to confirm the capability of CYP439A1v3 to degrade deltamethrin. The CYP439A1v3 was first expressed in Sf9 cell line and its recombinant enzyme was tested for metabolic activity against different insecticides using substrate depletion assay combined with metabolite identification. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and carbon monoxide (CO)-difference spectra analysis showed that the intact cytochrome P450 protein was successfully expressed. Tests with probe substrates proved its enzyme activity, as p-nitroanisole, ethoxycoumarin, and ethoxyresorufin were preferentially metabolized (specific activity 7.767 ± 1.22, 1.325 ± 0.37, and 0.355 ± 0.37 nmol/min per mg of protein, respectively) while only luciferin-HEGE was not. In vitro incubation of the recombinant CYP439A1v3 protein with deltamethrin revealed hydroxylation by producing hydroxydeltamethrin. On the contrary, no metabolite/metabolism was seen with nonpyrethroid insecticide, including imidacloprid, buprofezin, chlorpyrifos, and fipronil. To the best of our knowledge, this is the first study to link a CYP450 from family 439 to confer pyrethroid resistance to L. striatellus. This finding should help in the design of appropriate insecticide resistance management for control of this strain of L. striatellus.

Deltamethrin is metabolized by CYP6FU1, a cytochrome P450 associated with pyrethroid resistance, in Laodelphax striatellus

BACKGROUND

Cytochrome P450s (CYPs) are known to play a major role in metabolizing a wide range compounds. CYP6FU1 has been found to be over-expressed in a deltamethrin-resistant strain of Laodelphax striatellus. This study was conducted to express CYP6FU1 in Sf9 cells as a recombinant protein, to confirm its ability to degrade deltamethrin, chlorpyrifos, imidacloprid and traditional P450 probing substrates.

RESULTS

Carbon monoxide difference spectrum analysis indicated that the intact CYP6FU1 protein was expressed in insect Sf9 cells. Catalytic activity tests with four traditional P450 probing substrates revealed that the expressed CYP6FU1 preferentially metabolized p-nitroanisole and ethoxyresorufin, but not ethoxycoumarin and luciferin-HEGE. The enzyme kinetic parameters were tested using p-nitroanisole. The michaelis constant (K_m ) and catalytic constant (K_cat ) values were 17.51 ± 4.29 µm and 0.218 ± 0.001 pmol min^-1 mg^-1 protein, respectively. Furthermore, CYP6FU1 activity for degradation of insecticides was tested by measuring substrate depletion and metabolite formation. The chromatogram analysis showed obvious nicotinamide-adenine dinucleotide phosphate (NADPH)-dependent depletion of deltamethrin, and formation of the unknown metabolite. Mass spectra and the molecular docking model showed that the metabolite was 4-hydroxy-deltamethrin. However, the recombinant CYP6FU1 could not metabolize imidacloprid and chlorpyrifos.

CONCLUSION

These results confirmed that the over-expressed CYP6FU1 contributes to deltamethrin resistance in L. striatellus, and p-nitroanisole might be a potential diagnostic probe for deltamethrin metabolic resistance detection and monitoring. © 2017 Society of Chemical Industry.

Buprofezin Is Metabolized by CYP353D1v2, a Cytochrome P450 Associated with Imidacloprid Resistance in Laodelphax striatellus

CYP353D1v2 is a cytochrome P450 related to imidacloprid resistance in Laodelphax striatellus. This work was conducted to examine the ability of CYP353D1v2 to metabolize other insecticides. Carbon monoxide difference spectra analysis indicates that CYP353D1v2 was successfully expressed in insect cell Sf9. The catalytic activity of CYP353D1v2 relating to degrading buprofezin, chlorpyrifos, and deltamethrin was tested by measuring substrate depletion and analyzing the formation of metabolites. The results showed the nicotinamide-adenine dinucleotide phosphate (NADPH)-dependent depletion of buprofezin (eluting at 8.7 min) and parallel formation of an unknown metabolite (eluting 9.5 min). However, CYP353D1v2 is unable to metabolize deltamethrin and chlorpyrifos. The recombinant CYP353D1v2 protein efficiently catalyzed the model substrate p-nitroanisole with a maximum velocity of 9.24 nmol/min/mg of protein and a Michaelis constant of Km = 6.21 µM. In addition, imidacloprid was metabolized in vitro by the recombinant CYP353D1v2 microsomes (catalytic constant Kcat) 0.064 pmol/min/pmol P450, Km = 6.41 µM. The mass spectrum of UPLC-MS analysis shows that the metabolite was a product of buprofezin, which was buprofezin sulfone. This result provided direct evidence that L. striatellus cytochrome P450 CYP353D1v2 is capable of metabolizing imidacloprid and buprofezin.

Imidacloprid is degraded by CYP353D1v2, a cytochrome P450 overexpressed in a resistant strain of Laodelphax striatellus

BACKGROUND

Cytochrome P450s are associated with the metabolising of a wide range of compounds, including insecticides. CYP353D1v2 has been found to be overexpressed in an imidacloprid-resistant strain of Laodelphax striatellus. Thus, this study was conducted to express CYP353D1v2 in Sf9 cells as a recombinant protein, to assess its ability to metabolise imidacloprid.

RESULTS

Western blot and carbon monoxide difference spectrum analysis indicated that the intact CYP353D1v2 protein had been successfully expressed in Sf9 insect cells. Catalytic activity tests with four traditional P450-activity-probing substrates found that the expressed CYP353D1v2 preferentially metabolised p-nitroanisole, ethoxycoumarin and ethoxyresorufin with specific activities of 32.70, 0.317 and 1.22 pmol min^-1 pmol^-1 protein respectively, but no activity to luciferin-H EGE. The enzyme activity for degrading imidacloprid was tested by measuring substrate depletion and formation of the metabolite. Kinetic parameters for imidacloprid were K_m 5.99 ± 0.95 µm and k_cat 0.03 ± 0.0004 min^-1 . The chromatogram analysis showed clearly the NADPH-dependent depletion of imidacloprid and the formation of an unknown metabolite. The UPLC-MS mass spectrum demonstrated that the metabolite was an oxidative product of imidacloprid, 5-hydroxy-imidacloprid.

CONCLUSION

These results suggest that CYP353D1v2 in L. striatellus is capable of degrading imidacloprid, and that enzyme activity can be evaluated well only by some traditional probing substrates. © 2017 Society of Chemical Industry.

Resistance irrelevant CYP417A2v2 was found degrading insecticide in Laodelphax striatellus

Cytochrome P450 monooxygenases (CYPs) usually overexpressed in resistant strain were found involved in oxidative detoxification of insecticides. In this study, an investigation was conducted to confirm if resistance irrelevant CYPs which were not overexpressed in resistant strain before, were capable of degrading insecticides. Three resistance irrelevant CYPs viz. CYP417A2v2, CYP425A1v2, and CYP4DJ1 from CYP4 family of Laodelphax striatellus were randomly selected for experiments. CYP417A2v2 and CYP425A1v2 were found expressed successfully in Sf9 cell line while CYP4DJ1 was not expressed successfully and out of two expressed CYPs, only CYP417A2v2 showed its efficient catalytic activity. For catalytic activity, three traditional model probe substrates and five insecticides were assayed. For the probe substrates screened, p-nitroanisole and ethoxycoumarin were preferentially metabolized by CYP417A2v2 (specific activity 3.76 ± 1.22 and 1.63 ± 0.37 nmol min-1 mg protein-1, respectively) and they may be potential diagnostic probes for this enzyme. Among insecticides, only imidacloprid was efficiently degraded by CYP417A2v2. Incubation of imidacloprid with CYP417A2v2 of L. striatellus and subsequent HPLC, LC-MS, and MS/MS analysis revealed the formation of imidacloprid metabolites, that is, 4' or 5'hydroxy-imidacloprid by hydroxylation. This result implies the exemption of CYPs character that it is not always, all the CYPs degrading insecticides being selected and overexpressed in resistant strains and the degrading CYPs without mutations to upregulate could be candidates during insecticide resistance evolution. This characterization of individual insect CYPs in insecticide degradation can provide insight for better understand of insecticide resistance development.

Effects of probiotics on haematology and biochemical parameters in mice

Probiotic organisms are live microorganisms thought to be beneficial to the host. To know the effect of probiotic supplemented food on haemato-biochemical parameters in mice, a total of 20 two-month-old Swiss Albino mice were randomly divided into four equal groups. Group A was control, fed commercial mouse pellets, and others were treated with 5 g (group B), 10 g (group C) and 20 g (group D) probiotics (curd), respectively, in mouse pellets for 45 days. Total erythrocyte count and haemoglobin concentration were significantly (P<0.01) higher in treated group than in controls. Total serum cholesterol, triglyceride, high density lipoprotein and low density lipoprotein values decreased significantly (P<0.01) in treated groups. Serum uric acid value was significantly higher (P<0.01) in treated groups. It is suggested that probiotics help improve haematology and lipid profile but not kidney function. DOI: http://dx.doi.org/10.3329/bvet.v30i1.16281 Bangl. vet. 2013. Vol. 30, No. 1, 20-24

Prenatal nutrition among rural Bangladeshi pregnant women

The expected outcome of pregnancy is a healthy mother with a healthy child. The single most important care which could prevent the negative outcomes of pregnancy is Antenatal Care (ANC). Proper and timely antenatal care can significantly reduce the risks of maternal mortality. In pregnancy, total cost is about 80,000 Kcal, and above normal energy requirements. To find out prenatal nutrition an exploratory study was carried out in seven villages of the Ward-2 of Jamtoil Union of Kamarkhand Upazila under Sirajganj District. Thirty pregnant women of different trimesters, gravida and parity had been studied employing the methods and techniques of "Ethnographic Field Work." Mean daily calorie consumption of the Key Informants (KIs) was 1480.49 Kcal without reference to their religious affiliation, family resource base, education, occupation, gravidity, parity and duration of pregnancy. This is indicated that the mean calorie intake of the Key Informants did not meet not only their prenatal nutritional need but also their requirement during pre-pregnancy period. It was observed that food intake was in no way different from that of the non-pregnant status. Antenatal care of rural inhabitants analyzed almost exclusively from biomedical perspectives, its cultural, socio-economic, gender, ecological and other relevant perspectives are mostly ignored. In order to have safe motherhood up through compliance of prenatal advice, nutritional one in particular, these factors should be taken into consideration.

Association between morphological changes of nail and nail arsenic level in patients with arsenicosis

This case-control type of analytical study was conducted in the Department of Dermatology and Venereology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh to find out the association between morphological changes of nail and nail arsenic level in arsenicosis patients. Majority of arsenicosis patients were male (56.67%). The mean age of the cases was 43.07+/-13.73 years. Nail changes were found in 26.67% of cases, most were nail dystrophy (23.33%) and rest were Mee's line (3.34%). There was significant difference between cases with or without nail changes and nail arsenic level. But cases with or with out nail changes had a significant difference between duration of intake of arsenic contaminated water. There was no correlation between nail changes and nail arsenic level for nail dystrophy and Mee's line. The study result failed to establish association between the morphological changes of nail and nail arsenic level.

Unusual presentation of progressive systemic sclerosis

A female 38 years old, housewife, presented to the Department of Dermatology and Venereology, Mymensingh Medical College Hospital (MMCH) on 08.04.07 with the complaints of i) pain and reduced movement of hand, knee, shoulder and neck joints for 1 year and 9 months ii) tightness of skin over face, neck, limbs and trunk for 1 year and 6 months iii) patchy depigmentation over same areas for 1 year and 3 months iv) deformity of hands with flexion contractures for 6 months and v) dysphagia to solid food for 3 months. She had no complaints of Raynaud's phenomenon. On general examination, she was ill looking, anemic and nutritionally poor. Examination of integumentary system showed smooth, shiny, thick, hard and hidebound skin with pigmentary alteration of 'salt and pepper' appearance over fingers, hands, limbs, face, neck and trunk. Hands appear claw like but more on the right side than the left and there were no other obvious changes suggestive of digital ischaemia (atrophy, ulceration, scarring, gangrene etc). Face has got suggestive features of scleroderma. Examination of the respiratory system showed restriction of chest movement and reduced expansibility of chest wall. No other abnormality was found on examination of other systems. Laboratory investigations showed histopathology typical of scleroderma. X-ray of hands and feet showed suggestive changes, lung function test-showed restrictive lung disease. Barium swallow x-ray of esophagus in supine position showed mild dilation of lower oesophagus. But serology was non-reactive (negative ANA, Negative RA test, Negative VDRL). So, she was diagnosed as a case of progressive systemic sclerosis (PSS) with some atypicality.

Fixed drug eruptions due to cotrimoxazole

This prospective study on Fixed Drug Eruption (FDE) was carried out between January 2003 to December 2006 in Dermatology department of Mymensingh Medical College Hospital & private chambers. This study was carried out with an objective to see the specific site of involvement and other clinical parameters in FDE due to cotrimoxazole. In each case, a detailed history was taken and a thorough physical examination was done by at least one dermatologist. Patients with suspected FDE, who had consented, were included in the study. Oral re-challenge test was done in each case after written or verbal consent of the patient or legal guardian. For oral re-challenge, usually half of the usual therapeutic dose of the suspected drug (s) was given first and reactions were observed and if no reaction, then full therapeutic dose was given and then again reactions were observed. In case of no reaction to one drug, the next drug was tested after 2 to 7 days. Age & sex distribution, number of attacks of FDE, number of lesions, distribution of sites of involvement were determined in each case of FDE. All informations were recorded in pre-tested data sheet. Among 93 patients of suspected FDE, 61 patients were confirmed as FDE with identified causes, of which 36 cases were due to cotrimoxazole (59.02%). Age range of patients was from 5 years to 65 years with mean of 24.92 years. Male was predominantly affected (M:F=6.2:1). In 50% cases presenting attack was the 2nd attack. Rest 50% had 3 to more than 10 attacks. Number of lesions was: 2-5 lesions in 50%, solitary lesion in 16.67%, 6-10 lesions in 13.89% and more than 10 lesions in 19.44% cases. Sites of involvement in cases of FDE due to cotrimoxazole (n=36) were as follows: lips 58.33%, genitalia 33.33%, oral 13.89%, trunk 38.89%, limbs 55.56%, hands 16.67%, feet 19.44%, face 19.44% and conjunctiva 2.78%.

Simultaneous occurrence of multiple types of cutaneous tuberculosis (TVC and PNT) with internal organ tuberculosis (PTB)

A 40 years old male patient of poor socioeconomic condition presented with a well circumscribed rough surfaced and fissured, verrucous plaque on left axilla and a similar lesion on right foot- which were clinically diagnosed as tuberculosis verrucosa cutis. He also had necrotic papular eruption with varioliform scarring in some lesions on upper back clinically diagnosed as papulonecrotic tuberculid. He had fever and cough and mild weight loss suspicious of pulmonary tuberculosis. On investigation ESR was raised, mild anaemia was present, MT was strongly positive, chest x-ray was suggestive of tuberculosis. So, he was diagnosed as a case of simultaneous occurrence of tuberculosis verrucosa cutis (TVC) with papulonecrotic tuberculid (PNT) with pulmonary tuberculosis (PTB). Standard anti tuberculosis chemotherapy already started to offer cure of all lesions.

Seroprevalence of Helicobacter pylori among the diabetic population in Bangladesh: a comparative serological study on the newly diagnosed and older diabetics

This prospective study was designed to find out the prevalence of H. pylori infection among the diabetic population in Bangladesh with a comparison between the newly diagnosed and older diabetics. For this study 520 diabetic patients: 152 (29%) newly diagnosed and 368 (71%) older diabetics of both sexes (250 male, 270 female) with a mean age of 58.5 +/- 12.04 years (range 10-70 years), were selected randomly from out and in-patient departments of BIRDEM, Dhaka. Mean fasting and 2 hours post load blood glucose level of the studied population was 10.53 +/- 4.08 mmol/L and 18.35 +/- 9.44 mmol/L respectively. The mean duration of the newly diagnosed diabetics was 0.44 +/- 0.35 years (range 2 days-1 year) and 6.78 +/- 5.45 (range 1-30) years for the older diabetics. H. pylori infection was defined as a true positive ELISA test result of > 1.5 standard deviation above the cut-off values of 15 AU/ml for adults and 10 AU/ml for children for anti H. pylori IgG. Of the studied population 441 (84.8%)--132 newly diagnosed and 309 (83.96%) older diabetics were seropositive for H. pylori infection. No significant differences were observed between the newly diagnosed and older diabetics (86.84% Vs 83.96%; p > 0.05).

Incidence of spontaneous echocontrast in left atrium in mitral stenosis detected by transoesophageal echo cardiography and related factors

The incidence of left atrial (LA) spontaneous echo contrast (SEC) and the clinical and echocardiographic variables related to it were prospectively evaluated in a series of 60 patients with mitral stenosis (MS) undergoing transoesophageal echocardiography (TEE) with a 5 MHz multiplane transducer. LA-SEC was found in 39 patients (65%) employing TEE. Statistical analysis showed a significant relationship between the presence of SEC and MS without mitral regurgitation (MR) (P < 0.05), MS with < or = MR grade II (P < 0.05), atrial fibrillation (P < 0.001) and increased left atrial dimension (P < 0.05). Age, sex, mitral valve area and ejection fraction did not show any positive association (P > 0.05). Thus, it is concluded that LA-SEC is a common finding observed in approximately 65% of MS patients undergoing TEE and associated with conditions favouring stasis of left atrial blood.

Isolation of Vibrio cholerae O139 synonym Bengal from the aquatic environment in Bangladesh: implications for disease transmission

Currently, Bangladesh is experiencing an epidemic of acute watery diarrhea caused by Vibrio cholerae O139. Surface waters were collected and cultured for vibrious following enrichment. Twelve percent (11 of 92) of samples yielded V. cholerae O139, and all of them were positive for cholera toxin. The data suggest that V. cholerae O139 is easily culturable from surface water samples.

Use of the polymerase chain reaction and fluorescent-antibody methods for detecting viable but nonculturable Shigella dysenteriae type 1 in laboratory microcosms

Epidemiological studies of shigellosis in Bangladesh have demonstrated that surface-water sources can act as foci of infection. Studies of laboratory microcosms have shown that shigellae become nonculturable but remain viable when exposed to environmental samples of water. The present study was carried out to detect viable but nonculturable Shigella dysenteriae 1 from laboratory microcosms by the polymerase chain reaction and the fluorescent-antibody techniques. S. dysenteriae 1 was inoculated into laboratory microcosms consisting of water samples collected from ponds, lakes, rivers, and drains in Bangladesh. The survival of S. dysenteriae in microcosms was assessed by viable counting on MacConkey agar. After 2 to 3 weeks, S. dysenteriae 1 became nonculturable but remained viable. After 6 weeks, this nonculturable but viable S. dysenteriae 1 was detected by both the polymerase chain reaction and the fluorescent-antibody methods. The viable but nonculturable state of S. dysenteriae 1 demonstrated in this study may be important for understanding the epidemiology of shigellosis.

Inheritance of callus formation ability in anther cultures of rice, Oryza sativa L

Inheritance of ability to form callus in rice anther culture was studied using the diallel technique. Anthers containing uninucleate microspores from two japonica cultivais ('Minehikari' and 'Taipei 309'), two indica cultivars ('Mingolo' and 'Suweon 290'), and 12 F1's of the diallel crosses involving these four parents were cultured on Chaleffs R2 medium and evaluated for callus induction. The parents showed significant differences in anther callus formation, from 41.9% ('Taipei 309') to 0% ('Suweon 290'). Callus induction ability was inherited as a recessive character conditioned by a single block of genes. Additive gene effects were predominant. The japonica types seemed to be good combiners for callus induction. The order of dominance among the four parents was 'Suweon 290', 'Mingolo', 'Minehikari' and 'Taipei 309'.