Braz G R, Abreu L, Masuda H, Oliveira P L
Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, 21941-590, RJ, Rio de Janeiro, Brazil.
Insect Biochem Mol Biol. 2001 Mar 15;31(4-5):359-64. doi: 10.1016/s0965-1748(00)00129-6.
We have previously shown that the pathway of porphyrin synthesis operates in the blood feeding triatomine bug Rhodnius prolixus but not in the cattle tick Boophilus microplus. In the present paper we studied the correlation between heme synthesis and egg development in Rhodnius. There is a sharp increase heme biosynthetic capability in the fat body (160%) and in the ovaries (360%) in response to a blood meal, as evaluated from the activity of the enzyme delta-aminolevulinate dehydratase (EC 4.2.1.24). The in vivo inhibition of ALA-D by succinyl acetone results in a dose dependent decrease of oviposition. Oviposition is recovered when porphobilinogen, the product of the impaired reaction, is added to the succinyl acetone enriched blood. Taken together, these results show that heme biosynthesis is a fundamental event to vitellogenic females. The demand for heme in this metabolic juncture cannot be supplied by the heme eventually absorbed during blood digestion and associated with Rhodnius heme binding protein (RHBP), which is then incorporated into growing oocytes. Inhibition of heme biosynthesis results in lower levels of RHBP in the hemolymph, suggesting that the synthesis of this protein is controlled by heme availability.
我们之前已经表明，卟啉合成途径在吸血的锥蝽（Rhodnius prolixus）中起作用，但在牛蜱（Boophilus microplus）中不起作用。在本文中，我们研究了红猎蝽（Rhodnius）中血红素合成与卵子发育之间的相关性。通过δ-氨基乙酰丙酸脱水酶（EC 4.2.1.24）的活性评估，取食血液后，脂肪体（160%）和卵巢（360%）中的血红素生物合成能力急剧增加。琥珀酰丙酮对体内δ-氨基乙酰丙酸脱水酶（ALA-D）的抑制作用导致产卵量呈剂量依赖性下降。当向富含琥珀酰丙酮的血液中添加受损反应的产物胆色素原时，产卵量得以恢复。综上所述，这些结果表明血红素生物合成是卵黄生成期雌性的一个基本事件。在这个代谢阶段对血红素的需求无法由血液消化过程中最终吸收并与红猎蝽血红素结合蛋白（RHBP）相关联的血红素来满足，而该蛋白随后会整合到生长中的卵母细胞中。血红素生物合成的抑制导致血淋巴中RHBP水平降低，这表明该蛋白的合成受血红素可用性的控制。
