RNA METABOLISM IN THE GOLDFISH RETINA DURING OPTIC NERVE REGENERATION 1, 2

In goldfish, regeneration of the optic nerve following axotomy is accompanied by changes in retinal RNA metabolism. Approximately 4 days after unilateral optic nerve crush, there is an increased uptake of 3 H-labeled precursors of RNA into cells of the retina as well as an increase in labeling of total retinal RNA following incubation for 3–4 h in vitro. Subfractionation indicates that the resultant labeled free ribosomai RNA has a much higher specific activity than that from membrane-bound ribosomes in post-crush, as compared to normal retinas. Total retinal RNA content also increases, reaching a peak value about 8 days after axotomy, coincident with the time of observed maximum labeling of ribosomal RNA. No change in the total protein or DNA content of the retina is detected during this period as a result of the optic nerve crush. Saturating amounts of uridine or adenosine in the medium eliminate the general effects of enhanced uptake of the precursors on RNA labeling. Elevated labeling of poly(A)-containing RNA in retinal cytoplasm is nevertheless detected 10–14 days after optic nerve crush with no change in the labeling of the polyadenylate segment. A decrease in the labeling of poly(A)-containing nuclear RNA, from a significantly greater amount than that of normal retinas to a significantly lower one, occurs during the period of observed increased labeling of cytoplasmic poly(A)-containing RNA. The results indicate that in addition to changes in RNA precursor metabolism, optic nerve regeneration is characterized by alterations in the labeling of free and membrane-bound retinal ribosomes as well as in the post-transcriptional processing of messenger RNA.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66175/1/j.1471-4159.1978.tb12462.x.pd

COMPARISON OF THE FATTY ACIDS OF LIPIDS OF SUBCELLULAR BRAIN FRACTIONS

Rat brain grey and white matter were fractionated to yield myelin, nerve terminal, synaptic vesicle, nerve terminal ‘ghost’, and microsomal fractions of white and grey matter. Ester-type glycolipids were found in all fractions except myelin, while cerebrosides occurred in significant concentrations only in myelin and white microsomes. Comparison of the fatty acid profile of the ethanolamine- and serine-containing phospholipids showed marked differences between myelin and the particles from grey matter, while the microsomes of white matter were of intermediate composition. Docosahexaenoic acid, a minor acid in myelin, was a major fatty acid in microsomes of grey and white matter. The fatty acid composition of sphingomyelin was distinctly different in the fractions derived from grey and white matter, clustering about stearate and nervonate in the latter, but only about stearate in the grey. Marked differences in the positional distribution of fatty acids were seen within phosphatidyl choline from myelin and nerve terminals. Ribonucleic acid was found in nerve terminal and synaptic vesicle fractions. The sphingosine found in the ganglioside from microsomes of both grey and white matter was similar with respect to distribution of the C 18 and C 20 homologues. The possibility is discussed that microsomes furnish characteristic lipids for the synthesis or renewal of specific membranes, and that these lipids are accumulated somewhat before being released.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65163/1/j.1471-4159.1969.tb10380.x.pd

Effect of various stresses on the incorporation of [3H]orotic acid into goldfish brain RNA

The effect of a number of stresses on the incorporation of [5-3H]orotic acid into total goldfish brain RNA and its pyrimidine precursors is reported. The ratio of labeling of the uridylate and cytidylate moieties of the RNA (U/C) varied as a function of the temperature and duration of the experiment. The ratio was elevated when fish were subjected to pentylenetetrazol-induced convulsions or to mild electrical shock, with or without training of an avoidance conditioning task. The increase in ratio in all cases resulted from a decrease in cytidylate labeling. In experiments where this decrease was marked, a substantial decrease in the labeling of total RNA was seen as well. The observation that the increase in U/C was greater when increased numbers of fish were shocked per tank eventually led to the finding that addition of carbon dioxide to tank water results in a decrease in labeling of cytidylate isolated from RNA hydrolysates, as well as decreased labeling of cytidine precursors of RNA.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34119/1/0000403.pd

EFFECTS OF PUROMYCIN, ACETOXYCYCLOHEXIMIDE AND ACTINOMYCIN D ON PROTEIN SYNTHESIS IN GOLDFISH BRAIN *

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65427/1/j.1471-4159.1966.tb10284.x.pd

Management Capabilities and Policy Capacity Where are the Links?

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Sugar receptor specificity in the fleshfly, Sarcophaga bullata

Various carbohydrates were tested for stimulating activity of the sweet receptor of Sarcophaga bullata. Efficacy appears to be highest in -pyranosides having equatorial substituents at C-2, C-3, C-4 and C-5, with the exception of the C-1 position where equatorial substituents detract. Similarly, myo-inositol, having 5 equatorial and 1 axial hydroxyl, is the most stimulatory of the cyclitols tested. The anomalous action of several compounds remains unexplained. -Glucose is stimulatory, while its [alpha]- and [beta]-pyranosides are not. Similarly, free fructose, an extremely potent sugar, is completely inactive as its [alpha]- or [beta]-furanoside or its [alpha]- or [beta]-pyranoside. This finding is discussed in relation to the stimulatory action of sucrose.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33504/1/0000001.pd

Muscarinic receptor-stimulated Ca2+ signaling and inositol lipid metabolism in avian salt gland cells

Activation of muscarinic cholinergic receptors was studied by measuring agonist-stimulated inositol lipid turnover and changes in [Ca2+]i in dissociated salt gland secretory cells. Carbachol stimulation of quin2-loaded cells results in a sustained 4-fold increase in [Ca2+]i, while incorporation of [32P]Pi into phosphatidylinositol (PI) and phosphatidate are similarly increased. [3H]Inositol phosphates, measured in the presence of Li+, increased 13-fold. The stimulated increment in [Ca2+]i required extracellular Ca2+, whereas [3H]inositol phosphate accumulation was independent of external Ca2+. Dose-response curves for carbachol-induced increments in [Ca2+]i, PI labeling, and labeled inositol phosphate release are similar, with EC50 values of 6, 4.5 and 8 [mu]M, respectively. Dissociation constants for atropine vs. the quin2 and phospholipid responses are 0.59 +/- 0.3 nM and 0.48 +/- 0.28 nM, respectively. These cells thus provide a model system for the study of non-exocytotic secretion as a consequence of stimulated inositol lipid turnover.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25973/1/0000039.pd

Use of [1 or 3-3H, U-14c]glucose to estimate the synthesis of glycerolipids via acyl dihydroxyacetone phosphate

SummaryBHK-21-cl3 fibroblasts were incubated with [1-3H, U-14c]glucose or [3-3H, U-14c]glucose to produce intracellular [3H]NADPH via the phosphogluconate pathway. 3H and 14C were then determined at the three positions of glycerol in glycerol phosphate, saponifiable glycerolipids, alkyl ether glycerolipids and plasmalogens. The 3H/14C ratio at C-2 in glycerol of saponifiable glycerolipids is 2-10 fold greater than in glycerol phosphate and approaches the ratio found in ether-containing glycerolipids. This suggests that a significant fraction of the glycerolipids in BHK-21-cl3 fibroblasts is synthesized via acyl dihydroxyacetone phosphate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22025/1/0000441.pd

Towards a typology of inter-municipal cooperation in emerging metropolitan regions. A case study in the solid waste management sector in Ecuador

Inter-municipal cooperation (IMC) is a widely studied governance solution. Most literature defines IMC as a particular service delivery arrangement. However, we argue that IMC manifests itself in several forms and thus a broader definition is necessary. To explore this, we conducted a case study in the solid waste management sector of the emerging metropolitan region in Cuenca-Azogues, Ecuador. Emerging metropolitan regions are particularly suitable for analysing IMC, and so far, there are few studies on IMC in Latin America. Based on the discrepancy between previous studies and the results of our research, we develop a new definition and a new typology of IMC, which can be related to multiple service delivery arrangements