The endotoxic effect from gram negative bacteria is primarily due to the lipopolysaccharides (LPS). LPS activates the innate immune response through a Toll‐like receptor 4 (TLR4) known as the CD14/TLR4/MD2 receptor complex in mammals. The Toll receptors are conserved from primates to insects. However, in insects the peptidoglycan recognition proteins (PGRPs) are the receptors which respond to LPS from gram negative bacteria. These PGRPs activate the Immune Deficient (IMD) signaling cascade. There is a family of these receptors known in Drosophila melanogaster but their expression profiles in different tissues has yet to be fully elucidated. We examined a variety of model preparations to better understand the acute actions of exposure to LPS of Serratia marcescens to better understand the varied mechanisms of action. There is a differential, dose dependent effect of LPS in increasing and decreasing HR heart rate (HR) in the larval medicinal blow fly (Phaenicia sericata) and a fruit fly (Drosophila melanogaster). LPS depressed evoked and miniature (quantal) EJPs while hyperpolarizing the skeletal muscle in larval Drosophila, but increased EJPs with no effect on muscle membrane potential at the crayfish NMJ. Both NMJs are glutamatergic. LPS had no effect on sensory transduction of proprioceptive sensory neurons in crayfish and blue crab. LPS at the cholinergic frog NMJ depressed synaptic transmission with no effect on muscle membrane potential. LPS depressed sensory‐CNS‐motor nerve circuits in both crayfish and larval Drosophila. Synaptically‐evoked population spikes in field CA1 of the mouse hippocampus were also significantly reduced by acute LPS applications. The varied effects of LPS in different model systems paves the way to examining differential cellular mechanisms induced by acute exposure to LPS. Support or Funding Information Dept of Biology, Univ. of KY laboratory funds and personal funds (RLC) This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The direct action of bacterial lipopolysaccharides (LPS) endotoxin was shown to enhance synaptic transmission and hyperpolarize the membrane potential at low doses, but block glutamatergic receptors and decrease observable spontaneous events at a high dosage. The dosage effects are LPS type specific. The hyperpolarization is not due to voltage-gated potassium channels or to activation of nitric oxide synthase (NOS). The effects are induced directly by LPS, independent of an immune response.

Two cases of acardiac fetuses are presented. Pathological data in 61 cases are tabulated. Cliassification, terminology and patho-physiological findings are discussed. The Acardiac Monster is a form of monozygotic multiple gestation lacking a physiological heart and resulting in a bizarre fetal malformation which is sustained in utero by parasitic anastomoses to the circulation of a normal twin fetus. The precise etiology of this phenomenon is still obscure and suggestions are made for the future evaluation of the acardiac fetus.

No abstract

The endotoxic effect from gram negative bacteria is primarily due to the lipopolysaccharides (LPS). LPS activates the innate immune response through a Toll‐like receptor 4 (TLR4) known as the CD14/TLR4/MD2 receptor complex in mammals. The Toll receptors are conserved from primates to insects. However, in insects the peptidoglycan recognition proteins (PGRPs) are the receptors which respond to LPS from gram negative bacteria. These PGRPs activate the Immune Deficient (IMD) signaling cascade. There is a family of these receptors known in Drosophila melanogaster but their expression profiles in different tissues has yet to be fully elucidated. We examined a variety of model preparations to better understand the acute actions of exposure to LPS of Serratia marcescens to better understand the varied mechanisms of action. There is a differential, dose dependent effect of LPS in increasing and decreasing HR heart rate (HR) in the larval medicinal blow fly (Phaenicia sericata) and a fruit fly (Drosophila melanogaster). LPS depressed evoked and miniature (quantal) EJPs while hyperpolarizing the skeletal muscle in larval Drosophila, but increased EJPs with no effect on muscle membrane potential at the crayfish NMJ. Both NMJs are glutamatergic. LPS had no effect on sensory transduction of proprioceptive sensory neurons in crayfish and blue crab. LPS at the cholinergic frog NMJ depressed synaptic transmission with no effect on muscle membrane potential. LPS depressed sensory‐CNS‐motor nerve circuits in both crayfish and larval Drosophila. Synaptically‐evoked population spikes in field CA1 of the mouse hippocampus were also significantly reduced by acute LPS applications. The varied effects of LPS in different model systems paves the way to examining differential cellular mechanisms induced by acute exposure to LPS.Support or Funding InformationDept of Biology, Univ. of KY laboratory funds and personal funds (RLC)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.