Sources of the lipids in the bottom sediments of an English oligo-mesotrophic lake

SUMMARY. 1. The organic geochemistry of Coniston Water, a low productivity lake, has been investigated.
2. The relative inputs of the various known sources to different compound classes suggest terrestrial higher plants as the major source of sedimentary organic matter.
3. Early lipid diagenesis, proceeding in the bottom sediments as a result of microbial activity, produces relatively rapid changes, with shorter chain and unsaturated compounds being preferentially degraded.
4. Free and bound (acid liberated) lipids exhibit significant differences in composition, related to their respective sources and stability towards degradation.
5. The lipid composition of an aquatic higher plant, growing in the margins of the lake, has been determined; comparison with the sedimentary lipids reveal it not to be a significant source.     

Surface Remodelling of Reticulocytes produced in Response to Erythroid Stress

ACCELERATED erythropoiesis is associated with the production of reticulocytes of excessive size, perhaps as the result of skipped divisions during erythroid cell proliferation in the bone marrow¹. Isotopic studies have been interpreted as showing that these “stress reticulocytes” are short-lived and are replaced by progressively smaller cells with more normal life spans^1–6. It has recently been suggested, however, that stress reticulocytes are not destroyed in toto but are made smaller by a process of remodelling or surface fragmentation⁷; loss of only portions of these cells could explain most of the isotopic findings, although the residual cells might remain intact.