Multiple high-throughput analyses monitor the response of E. coli to perturbations

Analysis of cellular components at multiple levels of biological information can provide valuable functional insights. We performed multiple high-throughput measurements to study the response of Escherichia coli cells to genetic and environmental perturbations. Analysis of metabolic enzyme gene disruptants revealed unexpectedly small changes in messenger RNA and proteins for most disruptants. Overall, metabolite levels were also stable, reflecting the rerouting of fluxes in the metabolic network. In contrast, E. coli actively regulated enzyme levels to maintain a stable metabolic state in response to changes in growth rate. E. coli thus seems to use complementary strategies that result in a metabolic network robust against perturbations.     

Pigmentation of cultured red sea bream, Chrysophrys major, using astaxanthin from Antarctic krill, Euphausia superba, and a mysid, Neomysis sp.

Pigmentation enhancement in cultured red sea bream, Chrysophrys major, was investigated using Antarctic krill, Euphausia superba, and a mysid, Neomysis sp., as a source of astaxanthin. Diets fortified with processed Antarctic krill (krill meal) and its acetone extract, containing 0.82–4.92 mg carotenoids/100 g dry weight, and raw krill and raw mysid supplemented diets, containing about 2.00 mg carotenoids/100 g wet weight, were formulated and tested for carotenoid deposition. The rate of carotenoid deposition in fish fed with raw krill and raw mysid was significantly higher and resulted in distinct pigmentation. The groups fed with the krill meal and acetone extract diets showed varied concentrations of skin carotenoids and resulted in faint pigmentation. Pigmented fish then fed on a carotenoid-free diet for the same length of time showed no apparent differences in the skin pigmentation although the detectable amounts of carotenoids varied. The bream converted some of the dietary astaxanthin to skin tunaxanthin.     

In vitro platelet release by rat megakaryocytes: effect of metabolic inhibitors and cytoskeletal disrupting agents

Development of an in vitro visual assay facilitated the study of large numbers of megakaryocytes undergoing proplatelet formation in short-term cultures. Approximately 9% of megakaryocytes formed platelets during a 24-hour period. In the presence of an inhibitor of anaerobic glycolysis (NaF), proplatelet formation was inhibited, whereas inhibitors of respiration (NaCN) did not significantly (P greater than 0.05) decrease proplatelet formation. Presence of the microtubule-disrupting agents colchicine and vincristine sulfate in culture medium inhibited proplatelet formation, whereas the microfilament-disrupting agent cytochalasin B had a less pronounced inhibition.     

In vitro platelet release by rat megakaryocytes: effect of heterologous antiplatelet serum

A visual assay to study megakaryocyte platelet release via proplatelet formation in vitro was established. Samples of megakaryocyte-enriched rat bone marrow were incubated (37 C) in RPMI-1640 medium with 15% autologous serum in specially prepared chambers. In the culture system, approximately 6% of megakaryocytes formed proplatelet processes within 24 hours. Inclusion of a heterologous antiplatelet antibody in the culture system inhibited proplatelet formation, compared with that in controls.