Functional analysis of a fatty acid binding protein produced by Aphidius ervi teratocytes
Functional analysis of a fatty acid binding protein produced by Aphidius ervi teratocytes
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DOI：
10.1016/j.jinsphys.2011.12.019
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发表时间：
2012-05-01
影响因子：
2.2
通讯作者：
Giordana, Barbara
中科院分区：
文献类型：
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作者：
Caccia, Silvia;Grimaldi, Annalisa;Giordana, Barbara
蜜蜂蚜（Aphidius ervi，膜翅目，小蜂科）是多种蚜虫的内食寄生性昆虫，其中包括本研究的模式寄主——蜜蜂蚜（Acyrthosiphon pisum，同翅目，蚜虫科）。被寄生的寄主对发育中的寄生蜂幼虫的营养适宜性显著提高。这种生化和代谢特征的改变是由于在产卵时注射的毒液和胚胎膜分离产生的畸胎化细胞的共同作用介导的阉割过程。畸胎化细胞在宿主血液中产生和释放两种寄生特异性蛋白，这对其姐妹幼虫的发育至关重要。其中一种蛋白质是脂肪酸结合蛋白（Ae-FABP），对C14-C18饱和脂肪酸（FAs）、油酸和花生四烯酸具有高亲和力。为了更好地确定该蛋白可能的营养作用，我们研究了其在体内的免疫定位特征以及对银夜蛾幼虫表皮和中肠上皮摄取FA的影响。在寄生蜂幼虫的指数生长过程中，Ae-FABP分布在离散的脂质颗粒周围，这些脂质颗粒大量存在于寄主蚜虫的血腔和寄生蜂幼虫的中肠腔中。此外，参与营养吸收的两种幼虫上皮：拟寄生虫中肠上皮和外表皮层表面有明显的免疫检测信号。这两种上皮可以有效地吸收放射性标记的肉豆蔻酸，但FA的运输速率不受Ae-FABP介质存在的影响。该蛋白似乎在宿主血淋巴中充当载体，将FAs从宿主脂质消化部位转移到生长中的拟寄生虫幼虫。这些数据表明，弓形虫致畸细胞产生的蛋白质可能在宿主的营养利用中发挥互补作用。(C) 2011 Elsevier Ltd.版权所有。
Aphidius ervi (Hymenoptera, Braconidae) is an endophagous parasitoid of various aphid species, including Acyrthosiphon pisum (Homoptera, Aphididae), the model host used in the present study. Parasitized hosts show a marked increase of their nutritional suitability for the developing parasitoid larvae. This alteration of the biochemical and metabolic profile is due to a castration process mediated by the combined action of the venom, injected at the oviposition, and of the teratocytes, cells deriving from the dissociation of the embryonic membrane. Teratocytes produce and release in the host haemocoel two parasitism-specific proteins, which are of crucial importance for the development of their sister larvae. One of the proteins is a fatty acid binding protein (Ae-FABP), which shows a high affinity for C14-C18 saturated fatty acids (FAs) and for oleic and arachidonic: acids. To better define the possible nutritional role of this protein, we have studied its immunolocalization profile in vivo and the impact on FA uptake by the epidermal and midgut epithelia of A. ervi larvae.During the exponential growth of A. ervi larvae, Ae-FABP is distributed around discrete lipid particles, which are abundantly present in the haemocoel of parasitized host aphids and in the midgut lumen of parasitoid larvae. Moreover, a strong immunodetection signal is evident on the surface of the two larval epithelia involved in nutrient absorption: the parasitoid midgut epithelium and the external epidermal layer. These two epithelia can effectively absorb radiolabelled myristic acid, but the FA transport rates are not affected by the presence in the medium of Ae-FABP. The protein appears to act essentially as a vector in the host haemolymph, transferring FAs from the digestion sites of host lipids to the growing parasitoid larvae. These data indicate that the proteins produced by A. ervi teratocytes may play complementary roles in the nutritional exploitation of the host. (C) 2011 Elsevier Ltd. All rights reserved.