Characterization of an enriched lipoxygenase extract from Aspergillus niger in terms of specificity and nature of flavor precursors production

Aspergillus niger was grown for 6 days, and the harvested biomass was homogenized; the resultant supernatant, considered as the crude enzymatic extract, was enriched by ammonium sulfate precipitation. The extract was assayed for its lipoxygenase (LOX) activity using a wide range of polyunsaturated fatty acids (PUFAs), including linoleic, linolenic and arachidonic acids, as substrates. Two pH maxima were determined at 5.0, 10.5. The K_m and V_max values indicated that the microbial LOX displayed preferential substrate specificity towards linolenic acid at low pH. The microbial LOX demonstrated preferential substrate specificity towards free fatty acids over the acyl esters of linoleic acid. It was shown that the LOX activity of A. niger produced all monohydroperoxy regioisomers of the PUFAs, and there was a predominance of conjugated diene hydroperoxides. Significant production of the unconjugated 10-hydroperoxides of both linoleic and linolenic acids was obtained by the LOX activity. The amounts of 10-hydroperoxides ranged from 15 to 21% of total produced isomers, for linolenic and linoleic acids, respectively. The greatest proportion of the 10-regioisomer was attributed to the maximum activity at pH 5.0. Four major hydroperoxy-eicosatetraenoic acid (HPETE) regioisomers were isolated from the bioconversion of arachidonic acid, including the 8-, 9-, 12- and 15-HPETE, which accounted for approximately 97% of total isomers.     

Leishmania tarentolae: proline anabolism in promastigotes.

Using ¹⁴C-labeled substrates in conjunction with thin-layer Chromatographic radioautography, studies were done to determine the precursors for proline synthesis utilized by promastigotes of Leishmania tarentolae. The only substances in Trager's Defined Medium capable of acting as proline precursors under the conditions studied were l-arginine and l-ornithine. None of the other substrates tested (16 amino acids, five purines and pyrimidines, and glucose) were converted to proline. l-glutamate, l-aspartate, and d-glucose did not act as precursors for the imino acid although they stimulated oxygen uptake better than did l-arginine and l-ornithine. Proline synthesis was unaffected by the presence of preformed proline indicating the absence of end product feedback inhibition.     

Glial cells positive for glial fibrillary acidic protein in the neurohypophysis of the Djungarian hamster (Phodopus sungorus)

Summary The presence and distribution of the glial fibrillary acidic protein (GFAP; an astrocytic marker protein associated with glial filaments) in the neurohypophysis of the Djungarian hamster (Phodopus sungorus) were investigated immunohistochemically. Our study revealed characteristic GFAP-staining patterns within the median eminence, infundibular stem and neural lobe. In the whole neurohypophysis, few glial cells showed immunoreactivity. In the neural lobe, immunopositive pituicytes appeared preferentially in the periphery. At the ultrastructural level, we found some pituicytes containing filaments, most notably in their processes. We thus demonstrated that, in contrast to the GFAP-immunoreactivity of cultured pituicytes, pituicytic GFAP-expression in vivo coincides with the presence of electron-microscopically detectable filaments.     

Differential Effects of GM1 Ganglioside Treatment on Glial Fibrillary Acidic Protein Content in the Rat Septum and Hippocampus After Partial Interruption of Their Connections

Abstract: The glial fibrillary acidic protein (GFAP) content was investigated using immunoblotting techniques in the septum and hippocampus of the rat after bilateral lateral fimbria transection. Seven days after surgery GFAP content increased significantly both in the septum (140% of control) and hippocampus (120% in dorsal, the less denervated, and 145% in the most denervated ventral part), indicating the occurrence of reactive gliosis. The GM1 treatment caused statistically significant attenuation of GFAP increment in all hippocampal parts. In contrast, GM1 treatment has no influence on the increase of GFAP content in the septum. Results suggest a differential effect of GM1 on the two gliotic reactions formed as a consequence of the lesion at the level of the source of innervation (septum) and the target (hippocampus).     

Enhanced production of total flavones from Inonotus baumii by multiple strategies

As one kind of important secondary metabolites produced by Inonotus baumii, flavones can be applied in food, medicine, and other industries due to their biological activities such as antioxidant, anticancer, and antibacterial activity. To enhance total flavone production in submerged fermentation of I. baumii, three different strategies, optimization of fermentation parameters by statistical designs including Plackett–Burman design and response surface methodology, addition of precursors and elicitors, and two-phase culture, were used. The production of total flavones (PTF) reached 1532.83?mg/L when the optimized medium was used. All precursors and elicitors can increase the PTF. The maximum PTF (2184.06?mg/L, up to 1.57-fold) was obtained with the addition of both AgNO₃ and glutathione in fermentation media. Interestingly, when 0.5% (w/v) DM130 macroporous resin as adsorbent was added to fermentation broth on day 4 of culture, the highest production reached 2407.79?mg/L with this two-phase culture strategy. These methods can be further applied to large-scale industrial production and broaden the application of flavones.     

Comparative Study of Glial Marker Proteins in the Hypoplastic Cerebellum of Jaundiced Gunn Rats

The behavior of marker proteins of glial cells [alpha-enolase, beta-S100 protein, and glial fibrillary acidic protein (GFAP)] was investigated quantitatively by using enzyme immunoassay systems during the development of cerebellar hypoplasia in jaundiced Gunn rats. A neuronal marker protein, gamma-enolase, was also measured as a reference. At postnatal day 8 corresponding to the early stage of cerebellar damage, the amount of beta-S100 on a protein basis was significantly higher in jaundiced homozygotes (jj) than in control nonjaundiced heterozygotes (j+), whereas no differences in alpha- and gamma-enolases and GFAP were observed between the two groups of rats. At days 15 and 30, which correspond, respectively, to the advanced and late stages of cerebellar damage, the three glial proteins, especially GFAP, were higher and the neuronal protein was lower in the jj rat cerebellum than in the control. These results are consistent with the reported histological observations that neuronal cells are vulnerable and damaged by bilirubin, whereas glial cells seem to be less sensitive. On the other hand, the amounts of beta-S100 and alpha-enolase per cerebellum were significantly lower in jj rats at days 15 and 30, as in the case of gamma-enolase, whereas that of GFAP remained at the same level as the control at day 15 and showed a slight but significant decrease at day 30. The possibility is suggested that beta-S100 and GFAP may be available as biochemical indicators of glial cells, especially in the early and advanced stages of cerebellar damage, respectively, but that alpha-enolase is less available.