Effects of light regime on the growth,leaf morphology,and water relations of seedlings of two species of tropical trees

An experiment was conducted with Heliocarpus appendiculatus, a pioneer or large gap species of tropical moist forest in Costa Rica, and Dipteryx panamensis, a small gap species. Seedlings were grown in full sun, partial (80%) shade, and full (98%) shade. After one month of growth they were switched between environments and grown for two more months. Growth in height of Heliocarpus was greatly affected by irradiance, being increased in response to full shade and decreased in full sun. Height of Dipteryx was unaffected by irradiance level. Survival of Heliocarpus seedlings was only 49% in full shade, whereas Dipteryx had 100% survival. Biomass of Heliocarpus was not significantly greater in full sun than in partial shade whereas it was for Dipteryx. The response of root: shoot ratio was similar for both species. They were lowest in full shade and highest in full sun. Heliocarpus exhibited greater changes in leaf thickness, specific leaf weight, and stomatal density than did Dipteryx. Stomatal conductance of both species was lower in full shade and full sun than in partial shade. The results of the experiment indicate that growth of Heliocarpus is more plastic than that of Dipteryx in response to changes in irradiance. Previous environment did not affect the response to the present environment in either species. Both species responded positively to increases in irradiance.     

Formation of isoaspartate 99 in bovine and porcine somatotropins

Asparagine 99 in bovine (BST) and porcine somatotropins (PST) was converted to an isoaspartate residue during incubation at neutral or alkalinepH. Isoaspartate 99 BST or isoaspartate 99 PST was resolved from the normal somatotropin by reversed-phase high-performance liquid chromatography (HPLC). The altered peptide of residues 96–108 which contains isoaspartate 99 was detected by tryptic peptide mapping of the modified BST or PST. Amino acid sequencing, amino acid analysis, mass spectrometry, and co-elution with a chemically synthesized peptide containing isoaspartate 99 were used to demonstrate the existence of isoaspartate in the modified peptides. Peptide bond cleavage between Asn 99 and Ser 100 also occurred during incubation of BST and PST at neutral or alkalinepH. This chemically cleaved product was resolved on reversed-phase HPLC from both the isoaspartate 99 and normal somatotropin molecules.