scholarly journals Cadherin Protein Is Involved in the Action of Bacillus thuringiensis Cry1Ac Toxin in Ostrinia furnacalis

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 658
Author(s):  
Wenzhong Jin ◽  
Yuqian Zhai ◽  
Yihua Yang ◽  
Yidong Wu ◽  
Xingliang Wang
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Pest ◽  
Management Strategies ◽  
Ostrinia Furnacalis ◽  
Corn Borer ◽  
Cry1ac Toxin ◽  
Mortality Effect ◽  
Level Resistance

Transgenic crops expressing Bacillus thuringiensis (Bt) insecticidal proteins have been extensively planted for insect pest control, but the evolution of Bt resistance in target pests threatens the sustainability of this approach. Mutations of cadherin in the midgut brush border membrane was associated with Cry1Ac resistance in several lepidoptera species, including the Asian corn borer, Ostrinia furnacalis, a major pest of maize in Asian–Western Pacific countries. However, the causality of O. furnacalis cadherin (OfCad) with Cry1Ac resistance remains to be clarified. In this study, in vitro and in vivo approaches were employed to examine the involvement of OfCad in mediating Cry1Ac toxicity. Sf9 cells transfected with OfCad showed significant immunofluorescent binding with Cry1Ac toxin and exhibited a concentration-dependent mortality effect when exposed to Cry1Ac. The OfCad knockout strain OfCad-KO, bearing homozygous 15.4 kb deletion of the OfCad gene generated by CRISPR/Cas9 mutagenesis, exhibited moderate-level resistance to Cry1Ac (14-fold) and low-level resistance to Cry1Aa (4.6-fold), but no significant changes in susceptibility to Cry1Ab and Cry1Fa, compared with the original NJ-S strain. The Cry1Ac resistance phenotype was inherited as autosomal, recessive mode, and significantly linked with the OfCad knockout in the OfCad-KO strain. These results demonstrate that the OfCad protein is a functional receptor for Cry1Ac, and disruption of OfCad confers a moderate Cry1Ac resistance in O. furnacalis. This study provides new insights into the mode of action of the Cry1Ac toxin and useful information for designing resistance monitoring and management strategies for O. furnacalis.

scholarly journals CRISPR-Mediated Knockout of the ABCC2 Gene in Ostrinia furnacalis Confers High-Level Resistance to the Bacillus thuringiensis Cry1Fa Toxin

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 246 ◽  
Author(s):  
Xingliang Wang ◽  
Yanjun Xu ◽  
Jianlei Huang ◽  
Wenzhong Jin ◽  
Yihua Yang ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Deletion Mutation ◽  
Ostrinia Furnacalis ◽  
Corn Borer ◽  
Resistance Evolution ◽  
Loop Region ◽  
Truncating Mutation ◽  
High Level ◽  
Level Resistance

The adoption of transgenic crops expressing Bacillus thuringiensis (Bt) insecticidal crystalline (Cry) proteins has reduced insecticide application, increased yields, and contributed to food safety worldwide. However, the efficacy of transgenic Bt crops is put at risk by the adaptive resistance evolution of target pests. Previous studies indicate that resistance to Bacillus thuringiensis Cry1A and Cry1F toxins was genetically linked with mutations of ATP-binding cassette (ABC) transporter subfamily C gene ABCC2 in at least seven lepidopteran insects. Several strains selected in the laboratory of the Asian corn borer, Ostrinia furnacalis, a destructive pest of corn in Asian Western Pacific countries, developed high levels of resistance to Cry1A and Cry1F toxins. The causality between the O. furnacalis ABCC2 (OfABCC2) gene and resistance to Cry1A and Cry1F toxins remains unknown. Here, we successfully generated a homozygous strain (OfC2-KO) of O. furnacalis with an 8-bp deletion mutation of ABCC2 by the CRISPR/Cas9 approach. The 8-bp deletion mutation results in a frame shift in the open reading frame of transcripts, which produced a predicted protein truncated in the TM4-TM5 loop region. The knockout strain OfC2-KO showed much more than a 300-fold resistance to Cry1Fa, and low levels of resistance to Cry1Ab and Cry1Ac (<10-fold), but no significant effects on the toxicities of Cry1Aa and two chemical insecticides (abamectin and chlorantraniliprole), compared to the background NJ-S strain. Furthermore, we found that the Cry1Fa resistance was autosomal, recessive, and significantly linked with the 8-bp deletion mutation of OfABCC2 in the OfC2-KO strain. In conclusion, in vivo functional investigation demonstrates the causality of the OfABCC2 truncating mutation with high-level resistance to the Cry1Fa toxin in O. furnacalis. Our results suggest that the OfABCC2 protein might be a functional receptor for Cry1Fa and reinforces the association of this gene to the mode of action of the Cry1Fa toxin.

scholarly journals A Bacillus thuringiensis Chitin-Binding Protein is Involved in Insect Peritrophic Matrix Adhesion and Takes Part in the Infection Process

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 252
Author(s):  
Jiaxin Qin ◽  
Zongxing Tong ◽  
Yiling Zhan ◽  
Christophe Buisson ◽  
Fuping Song ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Galleria Mellonella ◽  
Binding Protein ◽  
Insect Pest ◽  
Infection Process ◽  
Peritrophic Matrix ◽  
Limited Information ◽  
Chitin Binding Protein

Bacillus thuringiensis (Bt) is used for insect pest control, and its larvicidal activity is primarily attributed to Cry toxins. Other factors participate in infection, and limited information is available regarding factors acting on the peritrophic matrix (PM). This study aimed to investigate the role of a Bt chitin-binding protein (CBPA) that had been previously shown to be expressed at pH 9 in vitro and could therefore be expressed in the alkaline gut of lepidopteron larvae. A ∆cbpA mutant was generated that was 10-fold less virulent than wild-type Bt HD73 towards Ostrinia furnacalis neonate larvae, indicating its important role in infection. Purified recombinant Escherichia coli CBPA was shown to have a chitin affinity, thus indicating a possible interaction with the chitin-rich PM. A translational GFP–CBPA fusion elucidated the localization of CBPA on the bacterial surface, and the transcriptional activity of the promoter PcbpA was immediately induced and confirmed at pH 9. Next, in order to connect surface expression and possible in vivo gut activity, last instar Galleria mellonella (Gm) larvae (not susceptible to Bt HD-73) were used as a model to follow CBPA in gut expression, bacterial transit, and PM adhesion. CBPA-GFP was quickly expressed in the Gm gut lumen, and more Bt HD73 strain bacteria adhered to the PM than those of the ∆cbpA mutant strain. Therefore, CBPA may help to retain the bacteria, via the PM binding, close to the gut surface and thus takes part in the early steps of Bt gut interactions.

scholarly journals New Resistance Mechanism in Helicoverpa armigera Threatens Transgenic Crops Expressing Bacillus thuringiensis Cry1Ac Toxin

2005 ◽  
Vol 71 (5) ◽  
pp. 2558-2563 ◽  
Author(s):  
Robin V. Gunning ◽  
Ho T. Dang ◽  
Fred C. Kemp ◽  
Ian C. Nicholson ◽  
Graham D. Moores
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Armigera ◽  
Resistance Mechanism ◽  
Transgenic Cotton ◽  
In Vivo Studies ◽  
Cry1ac Toxin ◽  
Helicoverpa Armígera ◽  
History Of

ABSTRACT In Australia, the cotton bollworm, Helicoverpa armigera, has a long history of resistance to conventional insecticides. Transgenic cotton (expressing the Bacillus thuringiensis toxin Cry1Ac) has been grown for H. armigera control since 1996. It is demonstrated here that a population of Australian H. armigera has developed resistance to Cry1Ac toxin (275-fold). Some 70% of resistant H. armigera larvae were able to survive on Cry1Ac transgenic cotton (Ingard) The resistance phenotype is inherited as an autosomal semidominant trait. Resistance was associated with elevated esterase levels, which cosegregated with resistance. In vitro studies employing surface plasmon resonance technology and other biochemical techniques demonstrated that resistant strain esterase could bind to Cry1Ac protoxin and activated toxin. In vivo studies showed that Cry1Ac-resistant larvae fed Cy1Ac transgenic cotton or Cry1Ac-treated artificial diet had lower esterase activity than non-Cry1Ac-fed larvae. A resistance mechanism in which esterase sequesters Cry1Ac is proposed.

scholarly journals THE EFFECT OF Bacillus thuringiensis TOXIN Cry1A.105 AND Cry2Ab2 ON THE SURVIVAL OF THE NON-TARGET PEST, Spodoptera litura (PENGARUH TOKSIN Bacillus thuringiensis Cry1A.105 DAN Cry2Ab2 TERHADAP KELANGSUNGAN HIDUP HAMA BUKAN SASARAN, Spodoptera litura)

2017 ◽  
Vol 20 (1) ◽  
pp. 7
Author(s):  
Kurnia Pratiwi ◽  
Y. Andi Trisyono ◽  
Edhi Martono
Keyword(s):  
Bacillus Thuringiensis ◽  
Larval Stage ◽  
Spodoptera Litura ◽  
Insect Pest ◽  
Survival Rates ◽  
Pupal Weight ◽  
Ostrinia Furnacalis ◽  
Corn Borer ◽  
Bt Toxin ◽  
And Control

ABSTRACTSpodoptera litura is one of the important insect pest of maize besides the notoriously damaging corn borer, Ostrinia furnacalis. S. litura has been the target of various controls including the use of Bacillus thuringiensis (Bt) toxin Cry1A.105 and Cry2Ab2. This study was conducted to evaluate the acute effect of Bt toxin Cry1A.105 and Cry2Ab2 on the growth and development of S. litura from larval to adult stages. Two sublethal concentrations were used; 0.1875 and 0.0469 ppm for Cry1A.105, and 0.0008 and 0.0003 ppm for Cry2Ab2. The bioassay using diet dipping was carried out on a CRD with three experiments and five repetitions. The observation was carried out on the mortality and survival rates of S. litura. The mortality reached 28% when the larvae were treated with 0.1875 ppm and 20% with 0.0469 ppm of Cry 1A.105. The exposed larvae and pupae were smaller than control. Larval and pupal weight were 117.0 and 165.6 g with 0.1875 ppm, while control were 212.9 and 211.2 g. Cry1A.105 also longer the larval stage, larval stage with higher and lower concentration were 24.5 and 22.3 day, while control was 20.5 day. The resulted pupae from larve which exposed by Cry1A.105 were less than control; there were 40% at concentration 0.1875 ppm and control 61%. The two concentration of Cry2Ab2 produced similar mortality of 20%. Similarly, Cry2Ab2 affected pupal to adult stages development. The longevity of pupal stage with concentration 0.0003 ppm was 9.5 days, followed by 0.0008 ppm (9.1 days) and control (10.1 days). The adult emerge on the highest concentration was 47.4% while control only 34.6%. There results showed that both Cry1A.105 and Cry2Ab2 were detrimental to the survival of S. litura which is the non-target insect of transgenic Bt maize.Keywords: Cry1A.105, Cry2Ab2, maize, non-target pest, Spodoptera litura, survival INTISARISpodoptera litura merupakan salah satu hama penting yang menyerang tanaman jagung, selain Ostrinia furnacalis. Belakangan ini O. furnacalis diketahui telah menjadi target dari berbagai macam cara pengendalian termasuk penggunaan toksin Bacillus thuringiensis (Bt) Cry1A.105 dan Cry2Ab2. Penelitian ini dilakukan untuk mengetahui efek akut toksin Bt Cry1A.105 dan Cry2Ab2 terhadap pertumbuhan dan perkembangan S. litura dari larva sampai imago. Dua konsentrasi subletal yang akan digunakan adalah; 0,1875 dan 0,0469 ppm untuk Cry1A.105, dan 0,0008 dan 0,0003 ppm untuk Cry2Ab2. Pengujian dilakukan dengan menggunakan metode celup pakan dan Rancangan Acak Legkap dengan tiga perlakuan dan lima ulangan. Pengamatan dilakukan terhadap mortalitas dan kelangsungan hidup S. litura. Mortalitas mencapai 28% pada larva yang dipaparkan dengan 0,1875 ppm dan 20% dengan 0,0469 ppm Cry 1A.105. Larva dan pupa yang terkena toksin berukuran lebih kecil. Berat larva dan pupa yang terpapar toksin dengan konsentrasi 0,1875 ppm, masing – masing 117,0 dan 165,6 g, sedangkan kontrol masing – masing 212,9 dan 211,2 g. Cry1A.105 juga dapat memperpanjang stadia larva. Lama stadia larva dengan konsentrasi tertinggi dan terendah adalah 24,5 dan 22,3 hari, sedangkan kontrol 20,5 hari. Jumlah pupa yang berhasil terbentuk dari larva yang terpapar toxin Cry1A.105 lebih sedikit dibandingkan dengan kontrol; pada konsentrasi 0,1875 ppm sebesar 40%, sedangkan kontrol sebesar 61%. Kedua konsentrasi dari toksin Bt Cry2Ab2 menyebabkan mortalitas yang sama yaitu 20%. Cry2Ab2 juga berpengaruh terhadap lama stadia pupa dan tingkat keberhasilan pembentukan imago. Lama stadia pupa dengan konsentrasi 0,0003 ppm adalah 9,5 hari, diikuti dengan konsentrasi 0,0008 ppm (9,1 hari) dan kontrol (10,1 hari). Jumlah imago terbanyak terdapat pada perlakuan dengan konsentrasi 0,0008 ppm sebesar 47,4% sedangkan pada kontrol hanya 34,6%. Hal ini menunjukkan bahwa toksin Bt Cry1A. 105 dan Cry2Ab2 juga berpengaruh terhadap kelangsungan hidup S. litura yang merupakan serangga bukan sasaran dari tanaman jagung transgenik Bt.Kata kunci: Cry1A.105, Cry2Ab2, hama bukan sasaran, jagung, kelangsungan hidup, Spodoptera litura

Rapid Emergence of Daptomycin Resistance in Nonstriatum Corynebacterium Species: A Multicenter Study

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S32-S33
Author(s):  
Kaitlin Mitchell ◽  
Erin McElvania ◽  
Meghan Wallace ◽  
Amy Robertson ◽  
Lars Westblade ◽  
...  
Keyword(s):  
Multicenter Study ◽  
Tertiary Care ◽  
Total N ◽  
Gradient Diffusion ◽  
Corynebacterium Species ◽  
Short Period ◽  
High Level ◽  
Level Resistance

Abstract Members of the genus Corynebacterium are increasingly recognized as causes of opportunistic infection; some species can be multidrug resistant, posing a treatment challenge. Daptomycin is frequently used as therapy of last resort in this setting, but previous work from our group demonstrated the ability of C striatum clinical isolates to rapidly develop high-level resistance to daptomycin, both in vivo and in vitro. Here, our objective was to expand this investigation into a multicenter study evaluating multiple Corynebacterium species. Corynebacterium strains from three tertiary-care academic medical centers (total, n = 76; site 1, n = 44; site 2, n = 15; site 3, n = 17) were evaluated, representing 16 species. Isolates were identified during routine clinical testing and reported to species level in accordance with each laboratory’s standard operating procedures. Identification of each species was confirmed using both VITEK MS and Bruker BioTyper MALDI-TOF MS. MICs to daptomycin (Etest), vancomycin (Etest), and telavancin (Liofilchem) at baseline were determined using gradient diffusion methods on Mueller-Hinton agar with blood (Hardy Diagnostics). Each isolate was then inoculated in duplicate to 5 mL Tryptic Soy Broth. A daptomycin Etest was submerged in one tube from each pair, and growth was observed after 24-hour incubation. If turbidity was observed in the tube with daptomycin, MICs for each of the 3 antimicrobials were reassessed. High-level daptomycin resistance emerged in 24 strains: C aurimucosum (1/1 isolate tested), C bovis (1/2), C jeikeium (2/11), C macginleyi (3/3), C resistens (1/1), C simulans (1/1), C striatum (14/14 isolates), and C ulcerans (1/1). The majority of these isolates had MIC values >256 µg/mL following exposure to daptomycin. Forty-eight other isolates remained susceptible to daptomycin: C afermentans (1/1), C amycolatum (19/20), C diphtheriae (1/1), C jeikeium (7/11), C kroppenstedtii (2/2), C propinquum (3/3), C pseudodiphtheriticum (6/6), C tuberculostearicum (0/6), and C urealyticum (0/3). Many of these isolates did not undergo MIC testing postdaptomycin exposure in broth due to complete lack of growth. Among those that did (n = 19), the median daptomycin MIC was 0.38 µg/mL (mean 0.42 µg/mL; range 0.023-1.0 µg/mL). One isolate of C bovis and two isolates of C jeikeium yielded variable susceptibility to daptomycin; a subset of resistant colonies grew adjacent to the gradient diffusion strip. Upon isolation and further MIC testing, these colonies maintained high-level resistance. In addition, one isolate of C amycolatum exhibited high-level daptomycin resistance (MIC >256 µg/mL) prior to in vitro exposure. All isolates in the cohort were susceptible to vancomycin and telavancin, both before and after daptomycin exposure. Our findings suggest that multiple Corynebacterium species can rapidly develop high-level daptomycin resistance after a short period of exposure to this antimicrobial. This finding has important clinical implications, especially in the treatment of invasive infections or infections of indwelling medical devices.

In vitro analysis of DIMBOA catabolism in the Asian corn borer Ostrinia furnacalis (Lepidoptera: Crambidae)

2018 ◽  
Vol 53 (2) ◽  
pp. 223-227 ◽  
Author(s):  
Tran Thi Thu Phuong ◽  
Masanobu Yamamoto ◽  
Takashi Matsuo ◽  
Takeshi Fujii ◽  
Yukio Ishikawa
Keyword(s):  
Ostrinia Furnacalis ◽  
Corn Borer ◽  
Asian Corn Borer ◽  
Vitro Analysis ◽  
In Vitro Analysis

scholarly journals Efficacy of Ampicillin plus Ceftriaxone in Treatment of Experimental Endocarditis Due to Enterococcus faecalis Strains Highly Resistant to Aminoglycosides

1999 ◽  
Vol 43 (3) ◽  
pp. 639-646 ◽  
Author(s):  
Joan Gavaldà ◽  
Carmen Torres ◽  
Carmen Tenorio ◽  
Pedro López ◽  
Myriam Zaragoza ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Enterococcus Faecalis ◽  
Pharmacokinetic Parameters ◽  
Initial Inoculum ◽  
High Level ◽  
Time Kill ◽  
Disk Method ◽  
Level Resistance

The purpose of this work was to evaluate the in vitro possibilities of ampicillin-ceftriaxone combinations for 10 Enterococcus faecalis strains with high-level resistance to aminoglycosides (HLRAg) and to assess the efficacy of ampicillin plus ceftriaxone, both administered with humanlike pharmacokinetics, for the treatment of experimental endocarditis due to HLRAg E. faecalis. A reduction of 1 to 4 dilutions in MICs of ampicillin was obtained when ampicillin was combined with a fixed subinhibitory ceftriaxone concentration of 4 μg/ml. This potentiating effect was also observed by the double disk method with all 10 strains. Time-kill studies performed with 1 and 2 μg of ampicillin alone per ml or in combination with 5, 10, 20, 40, and 60 μg of ceftriaxone per ml showed a ≥2 log10 reduction in CFU per milliliter with respect to ampicillin alone and to the initial inoculum for all 10E. faecalis strains studied. This effect was obtained for seven strains with the combination of 2 μg of ampicillin per ml plus 10 μg of ceftriaxone per ml and for six strains with 5 μg of ceftriaxone per ml. Animals with catheter-induced endocarditis were infected intravenously with 108 CFU of E. faecalis V48 or 105 CFU of E. faecalisV45 and were treated for 3 days with humanlike pharmacokinetics of 2 g of ampicillin every 4 h, alone or combined with 2 g of ceftriaxone every 12 h. The levels in serum and the pharmacokinetic parameters of the humanlike pharmacokinetics of ampicillin or ceftriaxone in rabbits were similar to those found in humans treated with 2 g of ampicillin or ceftriaxone intravenously. Results of the therapy for experimental endocarditis caused by E. faecalis V48 or V45 showed that the residual bacterial titers in aortic valve vegetations were significantly lower in the animals treated with the combinations of ampicillin plus ceftriaxone than in those treated with ampicillin alone (P < 0.001). The combination of ampicillin and ceftriaxone showed in vitro and in vivo synergism against HLRAgE. faecalis.

scholarly journals Current Insights and Latest Updates in Sperm Motility and Associated Applications in Assisted Reproduction

2020 ◽  
Author(s):  
Reyon Dcunha ◽  
Reda S. Hussein ◽  
Hanumappa Ananda ◽  
Sandhya Kumari ◽  
Satish Kumar Adiga ◽  
...  
Keyword(s):  
Sperm Motility ◽  
Reproductive Tract ◽  
Management Strategies ◽  
Human Sperm ◽  
Pharmacological Agents ◽  
Factors Affecting ◽  
Global Trend ◽  
Increased Risk

AbstractSpermatozoon is a motile cell with a special ability to travel through the woman’s reproductive tract and fertilize an oocyte. To reach and penetrate the oocyte, spermatozoa should possess progressive motility. Therefore, motility is an important parameter during both natural and assisted conception. The global trend of progressive reduction in the number and motility of healthy spermatozoa in the ejaculate is associated with increased risk of infertility. Therefore, developing approaches for maintaining or enhancing human sperm motility has been an important area of investigation. In this review we discuss the physiology of sperm, molecular pathways regulating sperm motility, risk factors affecting sperm motility, and the role of sperm motility in fertility outcomes. In addition, we discuss various pharmacological agents and biomolecules that can enhance sperm motility in vitro and in vivo conditions to improve assisted reproductive technology (ART) outcomes. This article opens dialogs to help toxicologists, clinicians, andrologists, and embryologists in understanding the mechanism of factors influencing sperm motility and various management strategies to improve treatment outcomes.

THE PRODUCTION BY BACILLUS THURINGIENSIS BERLINER OF A HEAT-STABLE SUBSTANCE TOXIC FOR INSECTS

1959 ◽  
Vol 5 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Ellicott McConnell ◽  
A. Glenn Richards
Keyword(s):  
Bacillus Thuringiensis ◽  
Inclusion Bodies ◽  
Galleria Mellonella ◽  
Culture Media ◽  
Water Soluble ◽  
Broth Culture ◽  
Toxic Principle ◽  
Heat Stable

Bacillus thuringiensis Berliner produces in vitro a heat-stable, dialyzable substance which is toxic for insects when injected. The same or a similar substance is produced in vivo. The toxic principle is of unknown composition. It is heat-stable, water-soluble, dialyzable, and resistant to low temperatures. It is probably neither a protein nor a lipid. Clearly it is distinct from the heat-labile inclusion bodies and from lecithinase. Growth-curve studies showed that the heat-stable toxin appeared in liver broth cultures during the active growth phase, prior to the formation of spores or inclusion bodies. An attempt to produce the toxic principle from culture media in the absence of bacteria was unsuccessful from sterile inocula both from in vivo and in vitro sources. The LD50 for larvae of Galleria mellonella injected with autoclaved supernatant from a 10-day-old liver broth culture of B. thuringiensis was determined to be 0.00036 ml per larva or 0.002 ml per gram of larvae. Approximately the same level of toxicity was found for another caterpillar, a fly larva, and cockroaches. After larvae of Galleria or Pyrausla have been dead for more than 2 days from infection with B. thuringiensis the bacillus could no longer be recovered. A sublethal amount of the heat-stable toxin injected into old larvae of Galleria delayed emergence of the adults by 30 to 40%. The non-pathogenic Bacillus cereus was found to produce a similar-acting, heat-stable toxin under the same conditions that one is produced by B. thuringiensis.

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