An electron microscopic and radioautographic study on experimental kernicterus. II. Bilirubin movement within neurons and release of waste products via astroglia

Response of the neurons to bilirubin in asphyxiated newborn rabbits was studied in vivo with the use of the electron microscope and radioautographic technics. A morphologic basis for the mode of intraneuronal bilirubin movement in kernicterus has been established. The absorbed bilirubin had ready access to the Golgi complex from the dendrite through the neurotubules by a mechanism of centripetal dendroplasmic flow. The endoplasmic reticulum provided a subcellular canalicular system for the directed passage from the Golgi complex to the nuclear membrane. Proximodistal flow of bilirubin in the axoplasm caused spotty destruction of axons. The release of waste products from the affected neurons toward the capillaries is very likely an effect of reverse transastroglial transport.

An electron microscopic and radioautographic study on experimental kernicterus. I. Bilirubin transport via astroglia

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The biogenesis of ethylene in penicillium digitatum

The origin of the ethylene carbon skeleton in Penicillium digitatum appears to be intimately associated with the Krebs cycle acids, particularly the middle carbon atoms of dicarboxylic acids. Among the other compounds studied, certain carbon atoms of beta-alanine, propionic acid, and methionine can be incorporated into the ethylene carbon skeleton presumably by way of an indirect route via the Krebs cycle acids. Carbon atoms of acrylic acid, particularly C-2, were also found to be incorporated into the ethylene skeleton. Inhibition of ethylene but not respiratory CO(2) formation in the mold by cis-3-chloroacrylic acid at 1 x 10(-3)m pointed to the possibility that acrylic acid may be related to the precursor for ethylene.

Utilization of fructose and glutamate by Rhodospirillum rubrum

Fructose served as sole carbon source for the growth of Rhodospirillum rubrum anaerobically under light or aerobically in the dark while glucose did not. Glucose was not utilized by the organism at all. Radiorespirometric studies, using 14C specifically labelled fructose as substrate, revealed that fructose is catabolized exclusively via the Embden–Meyerhof–Parnas (EMP) glycolytic pathway. Both L-glutamic and D-glutamic acids can be utilized by this organism, via the tricarboxylic acid cycle (TCA) pathway, under either aerobic-dark or anaerobic-light conditions.

Comparative glucose catabolism of Xanthomonas species

Glucose catabolism in eight Xanthomonas species has been comparatively examined by means of the radiorespirometric method. The basic mechanisms for the respective xanthomonads closely resembled each other. The Entner-Doudoroff pathway, in conjunction with the tricarboxylic acid cycle pathway, was the predominant mechanism for glucose catabolism. A small portion (8 to 16%) of substrate glucose was routed into the pentose phosphate pathway. The hexose cycle pathway did not appear to play any significant role in glucose catabolism of these xanthomonads. The results are also consistent with the well-recognized close phylogenic relationship between xanthomonads and pseudomonads.