Panapa Saksoong

Kasetsart University, Krung Thep, Bangkok, Thailand

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Publications (8)4.9 Total impact

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    ABSTRACT: The novel δ-endotoxin from Bacillus thuringiensis (Bt) is one of the alternative measures for lepidopteran pest control. A survey of 31 Bt isolates, obtained from Thailand and previously screened for their toxicity to lepidopterans, was conducted to determine the presence of cry1-type genes, using polymerase chain reaction -restriction fragment length polymorphism analysis. Seven distinct types of cry1 genes: cry1Aa, cry1B, cry1C, cry1Cb, cry1D, cry1E, and cry1F, were identified. The most common of the cry1-type genes was cry1Cb, followed by cry1C and cry1D, which covered 64.6, 48.4, and 25.8%, respectively. Besides cry1C and cry1Cb, two candidate cry genes, cry1E and cry1D, of isolate JC 190 (harbouring cry1C/1E), with cotton bollworm toxin specificity, showed 99% amino acid sequence identity to Cry1Ea of B. thuringiensis subsp. kenyae, while isolate JC 291 (containing cry1C/1Cb/1D), with Asian corn borer toxin specificity, harboured Cry1Dc, which exhibited only 84% amino acid sequence identity to Cry1Da of B. thuringiensis subsp. aizawai. The C-terminus of the JC291Cry1Dc possessed a unique sequence, 812-NVPIIPIISPW-822. Furthermore, the major differences between the 3D structure of Cry1Dc and Cry1Aa were confined to Domain II as three loop structures.
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    ABSTRACT: The novel δ-endotoxin from Bacillus thuringiensis (Bt) is one of the alternative measures for lepidopteran pest control. A survey of 31 Bt isolates, obtained from Thailand and previously screened for their toxicity to lepidopterans, was conducted to determine the presence of cry1-type genes, using polymerase chain reaction -restriction fragment length polymorphism analysis. Seven distinct types of cry1 genes: cry1Aa, cry1B, cry1C, cry1Cb, cry1D, cry1E, and cry1F, were identified. The most common of the cry1-type genes was cry1Cb, followed by cry1C and cry1D, which covered 64.6, 48.4, and 25.8%, respectively. Besides cry1C and cry1Cb, two candidate cry genes, cry1E and cry1D, of isolate JC 190 (harbouring cry1C/1E), with cotton bollworm toxin specificity, showed 99% amino acid sequence identity to Cry1Ea of B. thuringiensis subsp. kenyae, while isolate JC 291 (containing cry1C/1Cb/1D), with Asian corn borer toxin specificity, harboured Cry1Dc, which exhibited only 84% amino acid sequence identity to Cry1Da of B. thuringiensis subsp. aizawai. The C-terminus of the JC291Cry1Dc possessed a unique sequence, 812-NVPIIPIISPW-822. Furthermore, the major differences between the 3D structure of Cry1Dc and Cry1Aa were confined to Domain II as three loop structures.
    ScienceAsia 09/2010; 36(4):271-279. DOI:10.2306/scienceasia1513-1874.2010.36.271 · 0.35 Impact Factor
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    ABSTRACT: This research was designed to identify forty-eight exotic germplasm lines that were genetically and geographically distinct from the existing Thai soybean lines. Using 11 morphological descriptors, all genotypes were classified according to 37 morphological markers which allowed fully discrimination of the cultivars. Similarity indices between cultivars were calculated from 37 binary character states using Dice coefficient, which varied from 0.0 to 0.92 with an average of 0.449. The UPGMA cluster analysis revealed two groups, one formed by 32 cultivars and the other by the remaining 16 cultivars.
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    ABSTRACT: To determine and utilize RAPD markers linked to resistance to downymildew incited by Peronospora manshurica in soybean, a resistantcultivar `AGS129' was crossed to a susceptible cultivar `Nakhon Sawan 1'(NS1). F2 and BC1 populations were advanced from the F1 and evaluatedfor resistance to the disease. 2-test demonstrated that the resistancewas controlled by a single dominant gene (Rpmx). Near-isogenic lines(NILs) and bulked segregant analysis (BSA) were used to identify RAPDmarkers linked to the gene. Six DNA bulks namely F5(R), F5(S),BC6F3(R), BC6F3(S), F2(R) and F2(S) were set up by pooling equalamount of DNA from 8 randomly selected plants of each disease responsetype. A total of 180 random sequence decamer oligonucleotide primerswere used for RAPD analysis. Primer OPH-02 (5 TCGGACGTGA 3 andOPP-10 (5 TCCCGCCTAC 3) generated OPH-021250 and OPP-10831fragments in donor parent and resistant bulks, but not in the recurrentparent and susceptible ones. Co-segregation analysis using 102 segregatingF2 progenies confirmed that both markers were linked to the Rpmxgene controlling downy mildew disease resistance with a genetic distance of4.9 cm and 23.1 cm, respectively. Marker OPH-021250 was presentin 13 of 16 resistant soybean cultivars and absent in susceptible cultivars,thus confirming a potential for MAS outside the mapping population.
    Euphytica 10/2002; 128(1):55-60. DOI:10.1023/A:1020635501050 · 1.69 Impact Factor
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    ABSTRACT: To determine trends and associated risk factors of HIV incidence (1989-1997) in a drug abuse treatment clinic in northern Thailand where HIV is epidemic. Retrospective cohort study. Nine-years (1989-1997) of data (excluding names) from the logbook of drug abusers seeking treatments in Mae Chan Hospital in Chiangrai Thailand, were transcribed and double-entered into separate computer files which were later validated against each other. For each patient, the dates of the first HIV negative, the last HIV negative, and the first HIV positive were determined. A retrospective cohort of drug users who were initially HIV-negative and treated for more than once was constructed. HIV seroconversion was assumed to follow a uniform distribution between the last negative and the first positive HIV tests. The incidence rates and their 95% confidence intervals (CI) were calculated. Of the 378 repeat patients, 16 (4.2%) HIV seroconverted. This is equivalent to 5.11 per 100 person-years of observation (PYO) (95% CI = 3.13-8.35). The incidence remained relatively stable over the study period while the prevalence was on the decline. The younger, Thai lowlanders, drug injectors had higher incidence rates than the older, ethnic minorities and drug smokers, respectively. Prevalence can give illusional results. It is necessary to know baseline HIV incidence to monitor and evaluate an HIV intervention program.
    Journal of Epidemiology 05/1999; 9(2):114-20. DOI:10.1016/S0895-4356(99)80058-4 · 2.86 Impact Factor
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    ABSTRACT: Fifty l0-mer primers of a total 244 screened gave positive responses to DNAs of five morphologically different strains of silkworm. Of the sum of 381 bands, 335 were clearly polymorphic. Some of the DNA fragments were strain specific and some could differentiate the multivoltine from the bivoltine strains or vice versa. The genetic similarity among the strains and their phylogenetic relationships were discussed.
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    ABSTRACT: An experiment was carried out to evaluate the effect of texture layer of mungbean seed on infestation of bruchids (Callosobruchus maculatus and C. chinensis) (Coleoptera: Bruchidae). Seventeen BC9 near-isogenic mungbean lines (NILs) which are resistant to the insects, and their parents (KPS 1, CN 60 and the wild mungbean TC 1966), were compared. Each entry was prepared in two sets, one with intact texture layer and the other with texture layer removed by 15% NaOH. Each set was divided into 8 samples of 5 g each to test against the bruchids. The results revealed that both bruchid species laid more eggs on no texture layer seeds than on the intact ones. The difference in egg laying was especially high on seed of the wild mungbean TC 1966. The NILs, KPS 1 and CN 60 harbored several eggs on seed surfaces. However, the resistant lines had almost no damaged seed, regardless the removal of texture layer. The highest damage among the resistant NILs was only 5.5% while the susceptible recurrent parents were completely damaged. The texture layer seemed to affect only insect oviposition but not seed damage. Thus, to evaluate for chemical resistance to bruchids in a mixture of dull-and shiny-seeded mungbean, their texture layer should be removed to normalize the number of eggs laid on seeds.
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    ABSTRACT: This research was designed to identify forty-eight exotic germplasm lines that were genetically and geographically distinct from the existing Thai soybean lines. Using 11 morphological descriptors, all genotypes were classified according to 37 morphological markers which allowed fully discrimination of the cultivars. Similarity indices between cultivars were calculated from 37 binary character states using Dice coefficient, which varied from 0.0 to 0.92 with an average of 0.449. The UPGMA cluster analysis revealed two groups, one formed by 32 cultivars and the other by the remaining 16 cultivars. DNA samples from forty-eight exotic soybean cultivars was examined to determine the efficiency of randomly amplified polymorphic DNA (RAPD) markers in identifying cultivars and determining level of genetic similarity. Out of 80 random primers, 37 generated highly reproducible polymorphic RAPD fragments. With these primers, 274 clear-cut RAPD markers were produced and only 85 (31%) were polymorphic, which indicated that high level of genetic similarities existed in these exotic cultivars. One to six alleles per primer were detected with a polymorphic information content varying from 0.04 to 0.50. The use of only 14 RAPD markers amplified from five primers was sufficient to identify uniquely all the cultivars, indicating that RAPD markers are efficient for use in genetic fingerprinting in soybean. Genetic similarities of 85 RAPD profiles were estimated via the DICE coefficient and then the data were processed using UPGMA clustering method. Each genotype was clearly identified and separated from the others. RAPD based dendrogram revealed that the 48 cultivars could be classified into four groups at 0.57 similarity scale, between which the similarity coefficient was as low as 0.51, even though the cultivars are morphologically or geographically very close. The Principal Component Analysis (PCA) yielded rather similar results to the UPGMA dendrogram. RAPD genetic similarity coefficients were correlated with morphological similarity coefficients (r = 0.241). Comparing agronomic performance and RAPD analysis via dendrogram, a total of 11 cultivars were ear-marked for crossing program. These genotypes can be useful to soybean breeders in Thailand who want to utilize genetically diverse introductions in soybean improvement.