Original paper

Glyconeogenesis, Krebs Cycle Intermediates and Enzymes during Embryogenesis of the Camel Tick, Hyalomma dromedarii (Acarina: Ixodidae)

Hamed, Ragaa R.; Fahmy, Afaf S.; Kamel, Mamdouh Y.

Entomologia Generalis Volume 15 Number 1 (1990), p. 11 - 23

47 references

published: Feb 1, 1990

DOI: 10.1127/entom.gen/15/1990/11

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ArtNo. ESP146001501002, Price: 14.30 €

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Abstract

The TC-A cycle enzymes and intermediates were examined in eggs of Hyalomma dromedarii (Koch 1844). Unlike insects α-ketoglutarate and not citrate is the major carboxylic acid accumulated. The decrease in α-ketoglutarate and proline at the late stage of embryogenesis coincide with the abrupt increase in glutamate-pyruvate and glutamate-oxaloacetate transaminases and NAD (P) malic enzymes, suggested the possible role of malic enzyme and the transaminases in disappearance of a-ketoglutarate. The specific activities of TC-A cycle enzymes, citrate synthase, aconitase, isocitrate dehydrogenase (IC-DH), succinate dehydrogenase (S-DH), fumarase and malate dehydrogenase (M-DH) were followed during embryogenesis. The TC-A cycle is characterized by the low level of S-DH and the possible operation of M-DH in the reversed direction (oxaloacetate - malate). The low activity of the TC-A cycle enzymes and the operation of the aspartate-malate cycle suggested the biosynthetic role of the TC-A cycle in developing eggs. The specific activities of fructose 1,6-bisphosphatase and phosphoenol pyruvate (PE-P) carboxykinase at late stage of embryogenesis were reported. The functional significance of the operation of the TC-A, glyoxylate, aspartate-malate cycles under low oxygen conditions and the presence of fructose 1,6-bisphosphatase and PE-P carboxykinase in relation to glycogenesis is discussed.

Keywords

AcarinaHyalomma dromedariiembryogenesisglyconeogenesiskrebs cycle intermediates and enzymes