EXPERIMENTAL ECOLOGICAL GENETICS IN PLANTAGO IV. EFFECTS OF TEMPERATURE ON GROWTH RATES AND REPRODUCTION IN THREE POPULATIONS OF PLANTAGO LANCEOLATA L. (PLANTAGINACEAE)

The effects of temperature on growth rates and flowering responses of Plantago lanceolata L. populations sampled from open, shaded, and sunflecked habitats were studied in controlled environments. A large number of characteristics were phenotypically plastic in response to a broad range of temperatures. Low night temperatures substantially reduced reproductive effort, whereas high temperatures produced a reduction in total biomass. Temperature had little effect on leaf or inflorescence production rates, other than at very low temperatures. The phenotypic plasticity observed in the growth chamber correlated well with the observed seasonal phenology. Genetic differences were found in inflorescence height and total plant productivity. The rapid growth rate, the high reproductive effort, and generally broad temperature optimum to moderate temperatures are consistent with the occurrence of P. lanceolata in a wide variety of disturbed habitats in temperate latitudes.     

How reliable are Chinese hamster ovary (CHO) cell genome-scale metabolic models?

Genome-scale metabolic models (GEMs) possess the power to revolutionize bioprocess and cell line engineering workflows thanks to their ability to predict and understand whole-cell metabolism in silico. Despite this potential, it is currently unclear how accurately GEMs can capture both intracellular metabolic states and extracellular phenotypes. Here, we investigate this knowledge gap to determine the reliability of current Chinese hamster ovary (CHO) cell metabolic models. We introduce a new GEM, iCHO2441, and create CHO-S and CHO-K1 specific GEMs. These are compared against iCHO1766, iCHO2048, and iCHO2291. Model predictions are assessed via comparison with experimentally measured growth rates, gene essentialities, amino acid auxotrophies, and ¹³C intracellular reaction rates. Our results highlight that all CHO cell models are able to capture extracellular phenotypes and intracellular fluxes, with the updated GEM outperforming the original CHO cell GEM. Cell line-specific models were able to better capture extracellular phenotypes but failed to improve intracellular reaction rate predictions in this case. Ultimately, this work provides an updated CHO cell GEM to the community and lays a foundation for the development and assessment of next-generation flux analysis techniques, highlighting areas for model improvements.     

Androgen binding to ammonium sulfate precipitates of human adipose tissue cytosols

Although androgens are believed to influence the distribution of human adipose tissue and have been detected in human fat, receptors for these sex hormones have yet to be identified. These studies demonstrate that a high-affinity, limited-capacity binding component for the synthetic androgen methyltrienolone (R1881) exists in ammonium sulfate precipitates of human adipose tissue cytosols. The equilibrium dissociation constant (Kd = 0.1 to 0.4 nmol/L, n = 6) and the number of binding sites (2 to 26 fmol/mg protein, n = 22) are consistent with those reported for androgen receptors in rat prostate, human prostatic carcinoma, MCF-7 cells, and baboon myocardium. The relative steroid-binding specificities of the human adipose tissue androphile (R1881 approximately 5 alpha-dihydrotestosterone greater than testosterone greater than estradiol approximately progesterone much greater than dexamethasone) are similar, but not identical, to those reported for androgen receptors in rat prostate (R1881 greater than 5 alpha-dihydrotestosterone approximately testosterone greater than estradiol greater than progesterone much greater than cortisol) and baboon myocardium (R1881 greater than 5 alpha-dihydrotestosterone greater than testosterone greater than progesterone greater than estradiol much greater than cortisol). The function of the androgen-binding component in human adipose tissue is not known.     

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.