Development and application of transgenic technologies in cassava

The capacity to integrate transgenes into the tropical root crop cassava (Manihot esculenta Crantz) is now established and being utilized to generate plants expressing traits of agronomic interest. The tissue culture and gene transfer systems currently employed to produce these transgenic cassava have improved significantly over the past 5 years and are assessed and compared in this review. Programs are underway to develop cassava with enhanced resistance to viral diseases and insects pests, improved nutritional content, modified and increased starch metabolism and reduced cyanogenic content of processed roots. Each of these is described individually for the underlying biology the molecular strategies being employed and progress achieved towards the desired product. Important advances have occurred, with transgenic plants from several laboratories being prepared for field trails.     

Karyotypic study of five Lutjanid species using conventional and Ag-NORs banding techniques

The first cytogenetic comparisons of five snapper species from Thailand were presented here. Renal cell samples were taken from blacktail snapper (Lutjanus fulvus), five lined snapper (L. quinquelineatus), dory snapper (L. fulviflamma), brownstripe red snapper (L. vitta), and mangrove red snapper (L. argentimaculatus). The mitotic chromosome preparation was prepared directly from kidney cells. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results exhibited that all five snapper species have the diploid chromosome numbers of 2n = 48 and the fundamental numbers (NF) of 48. The presences of large, medium, and small telocentric chromosomes were 22-24-2, 24-20-4, 36-10-2, 28-16-4 and 36-10-2, respectively. The Ag- NORs banding technique provides the pair of nucleolar organizer regions (NORs) at subcentromeric region of the long arm of the respective telocentric chromosome pairs 9, 1, 3, 4 and 9. Their karyotype formulas is as follows: L. fulvus (2n = 48): L ₂₂ ^t + M ₂₄ ^t + S ₂ ^t , L. quinquelineatus (2n = 48): L ₂₄ ^t + M ₂₀ ^t + S ₄ ^t , L. fulviflamma (2n = 48): Lt36 + Mt10 + St2, L. vitta (2n = 48): L ₂₈ ^t + M ₁₆ ^t + S ₄ ^t , and L. argentimaculatus (2n = 48): L ₃₆ ^t + M ₁₀ ^t + S ₂ ^t .     

Synthesis and biological activity of analogs of a nonapeptide inhibitor of peptidyldipeptidase

The synthesis of 5 analogues of the effective inhibitor of peptidyl dipeptidase, teprotide, has been carried out. The inhibitory and bradykinin-potentiating activity of these compounds has been assayed. N-Terminal pyroglutamic acid and positive charge of arginine in position 4 were found to be essential for biological activity of the inhibitor.     

Synthesis of angiotensin converting enzyme inhibitors containing residues of substituted quinolines and a study of their biological activity]

Inhibitors of the angiotensin-converting enzyme were synthesized by substituting N-and C-terminal amino acid residues of tripeptide Bz-Phe-Ala-Pro by the residues of 8-methoxy-5-sulphoquinoline and carboxy-1,2,3,4-tetrahydroquinoline, respectively, and their in vivo and in vitro biological activity was determined. The enzyme's S2' site proved to be non specific to the position of the carboxylic group in the C-terminal heterocyclic part of the inhibitor molecule. Introducing a modified quinoline residue into the N-terminal part of the inhibitor does not increase its specific interaction with the hydrophobic pocket of the angiotensin-converting enzyme.