Bioassay Studies Research Articles

Identification and fine mapping of a new gene, BPH31 conferring resistance to brown planthopper biotype 4 of India to improve rice, Oryza sativa L

BackgroundRice (Oryza sativa L.) is the staple food for more than 3.5 billion people, mainly in Asia. Brown planthopper (BPH) is one of the most destructive insect pests of rice that limits rice production. Host-plant resistance is one of the most efficient ways to overcome BPH damage to the rice crop.ResultsBPH bioassay studies from 2009 to 2015 conducted in India and at the International Rice Research Institute (IRRI), Philippines, revealed that the cultivar CR2711–76 developed at the National Rice Research Institute (NRRI), Cuttack, India, showed stable and broad-spectrum resistance to several BPH populations of the Philippines and BPH biotype 4 of India. Genetic analysis and fine mapping confirmed the presence of a single dominant gene, BPH31, in CR2711–76 conferring BPH resistance. The BPH31 gene was located on the long arm of chromosome 3 within an interval of 475 kb between the markers PA26 and RM2334. Bioassay analysis of the BPH31 gene in CR2711–76 was carried out against BPH populations of the Philippines. The results from bioassay revealed that CR2711–76 possesses three different mechanisms of resistance: antibiosis, antixenosis, and tolerance. The effectiveness of flanking markers was tested in a segregating population and the InDel type markers PA26 and RM2334 showed high co-segregation with the resistance phenotype. Foreground and background analysis by tightly linked markers as well as using the Infinium 6 K SNP chip respectively were applied for transferring the BPH31 gene into an indica variety, Jaya. The improved BPH31-derived Jaya lines showed strong resistance to BPH biotypes of India and the Philippines.ConclusionThe new BPH31 gene can be used in BPH resistance breeding programs on the Indian subcontinent. The tightly linked DNA markers identified in the study have proved their effectiveness and can be utilized in BPH resistance breeding in rice.

Soil bioassay studies with time interval and spore density factors affecting the infection of Meloidogyne javanica by Pasteuria penetrans

Soil bioassay studies with time interval and spore density factors affecting the infection of Meloidogyne javanica by Pasteuria penetrans

Potential of small-molecule fungal metabolites in antiviral chemotherapy.

Various viral diseases, such as acquired immunodeficiency syndrome, influenza, and hepatitis, have emerged as leading causes of human death worldwide. Scientific endeavor since invention of DNA-dependent RNA polymerase of pox virus in 1967 resulted in better understanding of virus replication and development of various novel therapeutic strategies. Despite considerable advancement in every facet of drug discovery process, development of commercially viable, safe, and effective drugs for these viruses still remains a big challenge. Decades of intense research yielded a handful of natural and synthetic therapeutic options. But emergence of new viruses and drug-resistant viral strains had made new drug development process a never-ending battle. Small-molecule fungal metabolites due to their vast diversity, stereochemical complexity, and preapproved biocompatibility always remain an attractive source for new drug discovery. Though, exploration of therapeutic importance of fungal metabolites has started early with discovery of penicillin, recent prediction asserted that only a small percentage (5–10%) of fungal species have been identified and much less have been scientifically investigated. Therefore, exploration of new fungal metabolites, their bioassay, and subsequent mechanistic study bears huge importance in new drug discovery endeavors. Though no fungal metabolites so far approved for antiviral treatment, many of these exhibited high potential against various viral diseases. This review comprehensively discussed about antiviral activities of fungal metabolites of diverse origin against some important viral diseases. This also highlighted the mechanistic details of inhibition of viral replication along with structure–activity relationship of some common and important classes of fungal metabolites.

Characterization and antitumor activity of camptothecin from endophytic fungus Fusarium solani isolated from Camptotheca acuminate.

Camptothecin (CPT) is a potent drug against cancers, originally from plants. The endophytic fungi could produce the secondary metabolite same as the host and is used as medicine. The aim of this paper was to investigate an endophytic fungal CPT with anti-neoplastic activity. Endophytic fungi were isolated from Camptotheca acuminata in China. CPT from strain S-019 was characterized by TLC, HPLC and EI-MS analysis. Anti-tumor activity of fungal CPT was detected by MTT and fluorescent dye methods using Vero and PC-3 cells. A total of 94 endophytic fungi strains were isolated from tissues of C. acuminata and 16 fungi strains displayed cytotoxic activity on Vero or PC3 cells. Of which, the fungal strain S-019, classified as Fusarium solani, displayed impressive cytotoxic activity on cancer cells and was found to produce CPT by analysis of TLC, HPLC and EI-MS methods. Bioassay studies confirmed that the fungi CPT had potent cytotoxicity on Vero cells and induced apoptosis of Vero cells. The endophytic fungi from camptotheca trees are a reliable source for natural anticancer compounds. The endophytic fungi could produce CPT same as plant. The fungal CPT exhibited effective activity at inhibiting cell growth and inducing apoptosis on Vero cells.

Development of a Chlorantraniliprole Microcapsule Formulation with a High Loading Content and Controlled-Release Property

Microcapsule formulations have been widely developed and used in agriculture to improve pesticide utilization and reduce environmental pollution. However, commercial formulations of chlorantraniliprole (CAP) are only traditional formulations due to poor solubility of CAP in organic solvents. Here, adopting a solid in oil in water (S/O/W) double-emulsion method combined with premix membrane emulsion, we successfully constructed CAP microcapsule formulations with a high loading content. The microcapsule formulations with good light and thermal stability showed a significantly sustained release for a long period, which could be optimally regulated by tuning the surface porosity and size of the porous microcapsules. Bioassay studies showed that control efficacy of the porous microcapsule formulations against Plutella xylostella was superior to that of the commercial formulation. These results demonstrated that such a porous microcapsule delivery system should have great potential for further exploration as a commercial CAP formulation.

Bioefficacy of different bioagents against root-knot nematode, Meloidogyne incognita infesting bottle gourd under laboratory conditions

The bioefficacy of different bioagents viz., Paecilomyces lilacinus (2x10 6 cfu/g), Pseudomonas fluorescens (1x10 9 cfu/g), Trichoderma viride (2x10 6 cfu/g), Phule Trichoderma plus (2x10 6 cfu/g) and Pochonia chlamydosporium (2x106 cfu/g) against second stage juveniles of root-knot nematode infesting bottle gourd crop was studied under laboratory conditions. In this bioassay Paecilomyces lilacinus fungus caused higher rate of juvenile mortality at 1.00 per cent concentration was found to be promising in laboratory bioassay studies and recorded 80.00 per cent mortality of second stage juveniles of root-knot nematode. This was followed by 76.67 per cent mortality of second stage juveniles of root-knot nematode by Pseudomonas fluorescens at 1.00 per cent concentration after 72 hrs treatment of respective bioagents. The fungi Phule Trichoderma plus, Trichoderma viride recorded 70.00, 66.67 per cent juvenile mortality, while as in case of fungi Pochonia chlamydosporium 53.33 per cent juvenile mortality was observed after 72 hrs treatment of respective bioagents at 1.00 per cent concentrations.

A maize landrace that emits defense volatiles in response toherbivore eggs possesses a strongly inducible terpene synthase gene.

Maize (Zea mays) emits volatile terpenes in response to insect feeding and egg deposition to defend itself against harmful pests. However, maize cultivars differ strongly in their ability to produce the defense signal. To further understand the agroecological role and underlying genetic mechanisms for variation in terpene emission among maize cultivars, we studied the production of an important signaling component (E)‐caryophyllene in a South American maize landrace Braz1006 possessing stemborer Chilo partellus egg inducible defense trait, in comparison with the European maize line Delprim and North American inbred line B73. The (E) ‐caryophyllene production level and transcript abundance of TPS23, terpene synthase responsible for (E) ‐caryophyllene formation, were compared between Braz1006, Delprim, and B73 after mimicked herbivory. Braz1006–TPS23 was heterologously expressed in E. coli, and amino acid sequences were determined. Furthermore, electrophysiological and behavioral responses of a key parasitic wasp Cotesia sesamiae to C. partellus egg‐induced Braz1006 volatiles were determined using coupled gas chromatography electroantennography and olfactometer bioassay studies. After elicitor treatment, Braz1006 released eightfold higher (E)‐caryophyllene than Delprim, whereas no (E)‐caryophyllene was detected in B73. The superior (E)‐caryophyllene production by Braz1006 was positively correlated with high transcript levels of TPS23 in the landrace compared to Delprim. TPS23 alleles from Braz1006 showed dissimilarities at different sequence positions with Delprim and B73 and encodes an active enzyme. Cotesia sesamiae was attracted to egg‐induced volatiles from Braz1006 and synthetic (E)‐caryophyllene. The variation in (E)‐caryophyllene emission between Braz1006 and Delprim is positively correlated with induced levels of TPS23 transcripts. The enhanced TPS23 activity and corresponding (E)‐caryophyllene production by the maize landrace could be attributed to the differences in amino acid sequence with the other maize lines. This study suggested that the same analogous genes could have contrasting expression patterns in different maize genetic backgrounds. The current findings provide valuable insight not only into genetic mechanisms underlying variation in defense signal production but also the prospect of introgressing the novel defense traits into elite maize varieties for effective and ecologically sound protection of crops against damaging insect pests.

Life-Time Dosimetric Assessment for Mice and Rats Exposed in Reverberation Chambers of the 2-Year NTP Cancer Bioassay Study on Cell Phone Radiation.

In this paper, we present the detailed life-time dosimetry analysis for rodents exposed in the reverberation exposure system designed for the two-year cancer bioassay study conducted by the National Toxicology Program of the National Institute of Environmental Health Sciences. The study required the well-controlled and characterized exposure of individually housed, unrestrained mice at 1900 MHz and rats at 900 MHz, frequencies chosen to give best uniformity exposure of organs and tissues. The wbSAR, the peak spatial SAR and the organ specific SAR as well as the uncertainty and variation due to the exposure environment, differences in the growth rates, and animal posture were assessed. Compared to the wbSAR, the average exposure of the high-water-content tissues (blood, heart, lung) were higher by ~4 dB, while the low-loss tissues (bone and fat) were less by ~9 dB. The maximum uncertainty over the exposure period for the SAR was estimated to be <49% (k=2) for the rodents whereas the relative uncertainty between the group was <14% (k=1). The instantaneous variation (averaged over 1 min) was <13% (k=1), which is small compared to other long term exposure research projects. These detailed dosimetric results empowers comparison with other studies and provides a reference for studies of long-term biological effects of exposure of rodents to RF energy.

A Radio Frequency Radiation Exposure System for Rodents based on Reverberation Chambers.

In this paper we present the novel design features, their technical implementation, and an evaluation of the radio Frequency (RF) exposure systems developed for the National Toxicology Program (NTP) of the National Institute of Environmental Health Sciences (NIEHS) studies on the potential toxicity and carcinogenicity of 2nd and 3rd generation mobile-phone signals. The system requirements for this 2-year NTP cancer bioassay study were the tightly-controlled lifetime exposure of rodents (1568 rats and 1512 mice) to three power levels plus sham simulating typical daily, and higher, exposures of users of GSM and CDMA (IS95) signals. Reverberation chambers and animal housing were designed to allow extended exposure time per day for free-roaming individually-housed animals. The performance of the chamber was characterized in terms of homogeneity, stirred to unstirred energy, efficiency. The achieved homogeneity was 0.59 dB and 0.48 dB at 900 and 1900 MHz respectively. The temporal variation in the electric field strength was optimized to give similar characteristics to that of the power control of a phone in a real network using the two stirrers. Experimental dosimetry was performed to validate the SAR sensitivity and determine the SAR uniformity throughout the exposure volume; SAR uniformities of 0.46 dB and 0.40 dB, respectively, for rats and mice were achieved.

Investigation of chronic toxicity of hydroxyapatite nanoparticles administered orally for one year in wistar rats

Although the toxicity/biocompatibility of hydroxyapatite nanoparticles (nano HA), a prospective nano biomaterial is extensively studied, its interaction on biological systems following chronic exposure is less exploited. In the present study, Wistar rats were given various concentrations of nano HA in the diet to determine the chronic toxicity and potential carcinogenicity. Altogether 140 rats were used for the study under various administration dosages along with control. The animals were sacrificed after 12months of controlled continuous dosing. All in-life parameters, including body weight, food consumption, clinical observations, survival, biochemical and hematology, were unaffected by the chronic exposure of nano HA orally. Similarly, gross and histopathological evaluation was also unchanged following exposure to nano HA. No evidence of nano HA-related lesions or Nano HA-induced neoplasia was suggested in this rodent bioassay study.

Studying DDT Susceptibility at Discriminating Time Intervals Focusing on Maximum Limit of Exposure Time Survived by DDT Resistant Phlebotomus argentipes (Diptera: Psychodidae): an Investigative Report.

Extensive application of routine insecticide i.e., dichlorodiphenyltrichloroethane (DDT) to control Phlebotomus argentipes (Diptera: Psychodidae), the proven vector of visceral leishmaniasis in India, had evoked the problem of resistance/tolerance against DDT, eventually nullifying the DDT dependent strategies to control this vector. Because tolerating an hour-long exposure to DDT is not challenging enough for the resistant P. argentipes, estimating susceptibility by exposing sand flies to insecticide for just an hour becomes a trivial and futile task.Therefore, this bioassay study was carried out to investigate the maximum limit of exposure time to which DDT resistant P. argentipes can endure the effect of DDT for their survival. The mortality rate of laboratory-reared DDT resistant strain P. argentipes exposed to DDT was studied at discriminating time intervals of 60 min and it was concluded that highly resistant sand flies could withstand up to 420 min of exposure to this insecticide. Additionally, the lethal time for female P. argentipes was observed to be higher than for males suggesting that they are highly resistant to DDT's toxicity. Our results support the monitoring of tolerance limit with respect to time and hence points towards an urgent need to change the World Health Organization's protocol for susceptibility identification in resistant P. argentipes.

Detection of bispyribac sodium + metamifop 14% SE residue in soil by bioassay method

Bioassay studies were carried out to assess the residual effect of herbicide mixture, bipyribac-sodium + metamifop 14% SE in soil with indicator plant. A screening trial with three test crops, viz. cucumber, sunflower and maize indicated that maize was the best indicator plant, because it recorded the highest regression co-efficient for the parameters tested such as fresh and dry weight of shoot, shoot length and root length. The shoot dry weight of maize was identified as the best parameter to detect the phytotoxic residue in soil. The bioassay conducted with maize as an indicator plant in the post experiment soil revealed that there was no significant difference among the treatments (bispyribac-sodium + metamifop at 60, 70, 80, 90 g/ha, bispyribac applied alone at 25 g/ha, hand weeding twice and weedy check) during both the seasons in germination percentage, shoot length, root length, fresh weight and dry weight of maize plant. Thus it can be inferred that the herbicide mixture, bispyribac-sodium + metamifop did not leave any phytotoxic residues in soil.

Bioassay study of absorption, distribution and excretion of NY-198 compared with norfloxacin and ofloxacin

Bioassay study of absorption, distribution and excretion of NY-198 compared with norfloxacin and ofloxacin

Detoxifying enzyme studies on cotton leafhopper, Amrasca biguttula biguttula (Ishida), resistance to neonicotinoid insecticides in field populations in Karnataka, India

AbstractThe cotton leafhopper (Amrasca biguttula biguttula Ishida) is considered to be an alarming insect pest causing both quantitative and qualitative loss in cotton. In situ bioassay studies were done and the role of detoxifying enzymes in conferring resistance to neonicotinoid groups of insecticides in low (MUD), medium (DVG), high (HVR) and very high (GLB) pesticide usage areas of Karnataka were determined. Bioassay studies showed that imidacloprid, thiamethoxam, acetamiprid, thiacloprid and clothianidin registered varying levels of resistance for all the locations studied. The resistance ratio was high in imidacloprid (3.35, 8.57, 9.15 and 12.27 fold respectively) and the lowest in dinoferuran (1.86, 5.13, 6.71 and 9.88 fold respectively). Furthermore, the enzyme activity ratio (glutathione-S-transferase) was relatively greater, and corresponded to the higher LC50values of neonicotinoids for very high, high, medium and low pesticide usage areas. Our study suggested that the higher activity of the detoxifying enzyme in the resistance population of cotton leafhopper apparently has a significant role in endowing resistance to neonicotinoid groups of insecticides. However, this study recommends using neonicotinoids in cotton growing areas with caution.

Isolation, fractionation, identification and bioassay studies of the pheromone of the maconellicoccus hirsutus (green, 1908)

Maconellicoccus hirsutus (Green, 1908) is one of the invasive pests known to infest the agricultural crops of Vadodara, Gujarat. Large amount of pesticides are in use to control this pest which ultimately pose threat to both environment and mankind. So eco-friendly measures are required to limit the invasion of this pest. Hence the objective is to isolate the pheromone from Maconellicoccus hirsutus to uncover its different components through GC-MS along with the bioassay studies. Pheromone was isolated from the species through adsorbent method, and the volatiles were then subjected to GC-MS for fractionation. Crude extracts was further employed for behavioral bioassay to identify the nature of the pheromone. Combined result of GC and GC-MS indicated the presence of phenolic component in the extract. Additionally, observations from bioassay studies confirmed it as sex pheromone where attractive index of males towards volatiles was higher (0.88) than the females. Hence, identification of different pheromonal components will be helpful in synthesizing chemical analogues and their use in controlling the concerned pest in an eco-friendly way.

Biological characterization of highly pathogenic avian influenza H5N1 viruses that infected humans in Egypt in 2014-2015.

Highly pathogenic avian influenza (HPAI) H5N1 influenza viruses emerged as a human pathogen in 1997 with expected potential to undergo sustained human-to-human transmission and pandemic viral spread. HPAI H5N1 is endemic in Egyptian poultry and has caused sporadic human infection. The first outbreak in early 2006 was caused by clade 2.2 viruses that rapidly evolved genetically and antigenically. A sharp increase in the number of human cases was reported in Egypt in the 2014/2015 season. In this study, we analyzed and characterized three isolates of HPAI H5N1 viruses isolated from infected humans in Egypt in 2014/2015. Phylogenetic analysis demonstrated that the nucleotide sequences of eight segments of the three isolates were clustered with those of members of clade 2.2.1.2. We also found that the human isolates from 2014/2015 had a slight, non-significant difference in their affinity for human-like sialic acid receptors. In contrast, they showed significant differences in their replication kinetics in MDCK, MDCK-SIAT, and A549 cells as well as in embryonated chicken eggs. An antiviral bioassay study revealed that all of the isolates were susceptible to amantadine. Therefore, further investigation and monitoring is required to correlate the genetic and/or antigenic changes of the emerging HPAI H5N1 viruses with possible alteration in their characteristics and their potential to become a further threat to public health.

Conocimientos y prácticas ancestrales y tradicionales fortalecen la sustentabilidad de los sistemas hortícolas de la parroquia de San Joaquín

&lt;p&gt;El presente estudio lleva a establecer si los conocimientos y práctica ancestrales y tradicionales que desarrollan los agricultores de la parroquia de San Joaquín del Cantón Cuenca, fortalecen la sustentabilidad de los sistemas hortícolas.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt;Para conocer si estos sistemas se mantienen productivos a través del tiempo se utilizó el Marco para la Evaluación de Sistemas de Manejo de Recursos Naturales incorporando Indicadores de Sustentabilidad (MESMIS), comparando las prácticas productivas de una finca convencional con nueve fincas agroecológicas, donde se estableció los puntos críticos de los sistemas hortícolas para en el futuro modificarlos y lograr sistemas productivos más sustentables a pesar de ser intensivos.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt;En el estudio se estableció en la dimensión ambiental logra un mínimo del 2.8/5 (56%) y como máximo al 3.8/5 (76%), dentro de la dimensión social se establece un valor mínimo de 3.2/5 (64%) y un valor máximo de 4.8/5 (96%), y la dimensión económica con un valor mínimo de 2.6/5 (52%) y máximo del 4.8/5 (96%). &lt;/p&gt;&lt;p&gt; &lt;/p&gt;Los sistemas hortícolas se establece que cuentan con un grado de sustentabilidad significativo, debido a que las tres dimensiones agroecológicas se encuentran por encima del promedio, debido a que los campesinos desarrollan diversas prácticas ancestrales, tradicionales y culturales dentro de los agroecosistemas como: en lo social; la asociatividad interna de las familias para la producción y comercialización, en la producción; la asociación, la rotación y la biodiversidad, logrando una producción diversificada que genera los beneficios económicos para mejorar la calidad de vida de cada uno de los integrantes que conforman la familia campesina.

Molecular and functional characterization of cry1Ac transgenic pea lines

ABSTRACTTransgenic pea lines transformed with the cry1Ac gene were characterized at molecular (PCR, RT-PCR, qRT-PCR and immunostrip assay) and functional levels (leaf paint and insect feeding bioassays). The results showed the presence, expression, inheritance and functionality of the introduced transgene at different progeny levels. Variation in the expression of the cry1Ac gene was observed among the different transgenic lines. In the insect bioassay studies using the larvae of Heliothis virescens, both larval survival and plant damage were highly affected on the different transgenic plants. Up to 100 % larval mortality was observed on the transgenic plants compared to 17.42 % on control plants. Most of the challenged transgenic plants showed very negligible to substantially reduced feeding damage indicating the insect resistance of the developed transgenic lines. Further analysis under field condition will be required to select promising lines for future uses.

Draft Genome Sequence of Marine Sponge Symbiont Pseudoalteromonas luteoviolacea IPB1, Isolated from Hilo, Hawaii.

We report here the 6.0-Mb draft genome assembly of Pseudoalteromonas luteoviolacea strain IPB1 that was isolated from the Hawaiian marine sponge Iotrochota protea. Genome mining complemented with bioassay studies will elucidate secondary metabolite biosynthetic pathways and will help explain the ecological interaction between host sponge and microorganism.

Assessment of insecticides and Cry2AB toxin resistance development in Karnataka population of Plutella xylostella (Linn.)

Insecticidal resistance studies against third instar larvae of DBM (Plutella xylostella L.) were carried out to know the rate of development of resistance from F1 to F3 generations in Karnataka population. The third instar larvae obtained from field were subjected to bioassay studies with tested against acephate, cypermethrin, spinosad, cartap hydrochloride and Cry2Ab toxin using leaf dip method to calculate LC50 values. The LC50 values of the insecticides were further used to quantify the resistance in P. xylostella of parental generation (F0) from Karnataka field population. The survivals from F0 generation were reared to next generation (F1). Resistance development studies was assessed from F1 to F3 generation with third instar larvae in every generation with a concentration that caused 80.00 % mortality for all the test insecticides and Cry2Ab toxin. Results revealed that ((0.17 folds) no resistance was developed against acephate in F3 generation. In case of cypermethrin 2.33 folds. Resistance studies further revealed that 1.50 folds resistance was developed against spinosad, 2.28 folds against cartap hydrochloride and Cry2Ab toxin 1.49 folds resistance was recorded in F3 generation. The rate of development of resistance from F1 to F3 generations increased in all the test insecticides and Cry toxin, except against acephate in Karnataka population. This data will be useful in the development of insecticide resistance management approach for DBM.