Biomedical subjects

L L Loguercio

Publications and source records attributed to L L Loguercio.

4 recordsLinked to original sources

PubMed2002

Combined analysis of supernatant-based feeding bioassays and PCR as a first-tier screening strategy for Vip -derived activities in Bacillus thuringiensis strains effective against tropical fall armyworm.

AIMS: To assess whether feeding bioassays using culture-supernatant proteins could be combined with PCR into a first-tier screening strategy for Vip3A-like genes efficient against tropical Spodoptera frugiperda. METHODS AND RESULTS: Out of 12 Bacillus thuringiensis strains studied, the total protein concentrated from the culture supernatant of only the strain HD125 yielded a significantly increased armyworm mortality and an intense band of the predicted size for VIP3A protein in SDS-PAGE. However, PCR and sequencing data indicated Vip-like genes are ubiquitous in tropical B. thuringiensis isolates. Interestingly, the HD125 strain was also the only one displaying a single-band amplification pattern and the highest sequence identity to the reported Vip3A(a) gene. CONCLUSIONS: Results suggest the insecticidal effectiveness of putative VIPs in B. thuringiensis isolates can be preliminarily estimated by the use of supernatant-derived total protein in feeding experiments, though only in a limited manner. SIGNIFICANCE AND IMPACT OF THE STUDY: A simple and cost-effective first-tier screening strategy for VIP-derived activities in B. thuringiensis collections can be developed by combining PCR and feeding bioassays. Moreover, the employed primers showed to be useful as a tool for strains differentiation at DNA level, and for characterization and isolation of Vip-like genes in tropical B. thuringiensis germplasm.

Animals↗

PubMed2001

Association of PCR and feeding bioassays as a large-scale method to screen tropical Bacillus thuringiensis isolates for a cry constitution with higher insecticidal effect against Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae.

AIMS: To verify whether the presence of any of the cry1C, 1D, 1E and 1F genes could be associated with high toxicity against fall armyworm. METHODS AND RESULTS: A sample of 60 strains from a large collection of tropical Bacillus thuringiensis (B.t.) isolates was subjected to feeding bioassays and gene-specific PCR. Positive amplification of cry-specific fragments, so confirmed by sequencing, revealed that cry1C was ubiquitous and distributed among high and low mortality classes, cry1D was underrepresented and showed no clear association to high toxicity, and cry1F was not detected. The presence of cry1E significantly correlated to high levels of insecticidal activity, as estimated by linear regression analysis. CONCLUSION: The PCR amplification of cry1E-specific fragments alone appears to be sufficient to identify B.t. strains with high mortality levels against tropical armyworm. SIGNIFICANCE AND IMPACT OF THE STUDY: The approach presented is promising as a simple and efficient method for first-tier, marker-assisted screening of environment-specific B.t. germplasm effective in controlling a single target pest.

Animals↗

PubMed1999

Hmg-coA reductase gene family in cotton (Gossypium hirsutum L.): unique structural features and differential expression of hmg2 potentially associated with synthesis of specific isoprenoids in developing embryos.

As a first step towards understanding the biosynthesis of isoprenoids that accumulate in specialized pigment glands of cotton at the molecular level, two full-length genes (hmg1 and hmg2) were characterized encoding hmg-coA reductase (HMGR; EC 1.1.1.34), the enzyme that catalyzes the formation of a key isoprenoid precursor. Cotton hmgr genes exhibited features typical of other plant genes, however, hmg2 encodes the largest of all plant HMGR enzymes described to date. HMG2 contains several novel features that may represent functional specialization of this particular HMGR isoform. Such features include a unique 42 amino acid sequence located in the region separating the N-terminal domain and C-terminal catalytic domain, as well as an N-terminal hydrophobic domain that is not found in HMG1 or other HMGR enzymes. DNA blot analysis revealed that hmg1 and hmg2 belong to small subfamilies that probably include homeologous loci in allotetraploid cotton (Gossypium hirsutum L.). Ribonuclease protection assays revealed that hmg1 and hmg2 are differentially expressed in a developmentally- and spatially-modulated manner during morphogenesis of specialized terpenoid-containing pigment glands in embryos. Induced expression of hmg2 coincided with a possible commitment to sesquiterpenoid biosynthesis in developing embryos, although other developmental processes also requiring HMGR cannot be excluded.

Base Sequence↗

PubMed1998

Structural analysis of a hmg-coA-reductase pseudogene: insights into evolutionary processes affecting the hmgr gene family in allotetraploid cotton (Gossypium hirsutum L.).

Structural analysis of hmg-coA reductase (hmgr) genes in the allotetraploid cotton species Gossypium hirsutum L. revealed the first-known existence of a pseudogene, psihmg5, for this important enzyme. Complete sequencing of the genomic clone hmg5 unveiled several deleterious lesions, resulting in an organization that departed significantly from the linear canonical hmgr gene structure. Although analysis of the 5' flanking region indicated a promoter-like composition based on comparison with other known plant hmgr genes, the precise loss of intron 3, and putative poly-(A) signals, small poly-(A) tracts, and terminal repeats (TRs) found in the 3'-flanking region are characteristic features of retro-pseudogenes. DNA-blot analysis indicated that a psihmg5-related subfamily exists within a larger hmgr gene family in cotton. Several mechanisms are proposed to account for the formation of this partially intronless pseudogene, including intragenic homologous-replacement recombination and gene conversion involving a cDNA. Alignments of psihmg5 with functional cotton homologs also raised interesting possibilities for the formation of 'chimeric' gene structures, or differential intragenic mutation rates, as potential evolutionary mechanisms involved in shaping the hmgr gene family in cotton.

Amino Acid Sequence↗