Labrosse C, Eslin P, Doury G, Drezen J M, Poirié M
Institut de Recherche sur la Biologie de l'Insecte UMR CNRS 6035, Université F. Rabelais, Parc Grandmont, 37 200 Tours, France.
J Insect Physiol. 2005 Feb;51(2):161-70. doi: 10.1016/j.jinsphys.2004.10.004.
The hymenopteran wasp Leptopilina boulardi (Figitidae) is a larval solitary parasitoid of Drosophila larvae of the melanogaster sub-group. The factors used by parasitoid females to prevent encapsulation of their eggs by the host are localized in the female long gland and reservoir. We report here the physiological effects of these factors on host haemocytes using in vivo injection experiments. The total number of haemocytes, the number of plasmatocytes and the number of crystal cells were not modified by injection of long gland extracts. In contrast, long gland extracts either from virulent or avirulent strains had a significant effect on the lamellocyte number. Compared to the Ringer control, the avirulent long gland products induced an increase of the lamellocyte number while virulent extracts induced a drastic decrease together with an alteration of the morphology of these cells. Interestingly, changes in the lamellocyte morphology were also observed following injection of the P4 protein, a major component of L. boulardi female long glands that displays a strong immune suppressive effect on Drosophila larvae. The implication of the P4 protein in suppressing the host cellular immunity is discussed in correlation with its predicted molecular function as a Rho-GAP protein.
膜翅目黄蜂布氏细蜂（姬小蜂科）是黑腹果蝇亚组果蝇幼虫的一种孤雌寄生性幼虫。寄生蜂雌蜂用于防止宿主对其卵进行包囊化的因子定位于雌蜂的长腺和贮液囊。我们在此报告这些因子通过体内注射实验对宿主血细胞产生的生理效应。注射长腺提取物后，血细胞总数、浆血细胞数量和晶细胞数量均未改变。相比之下，来自有毒或无毒菌株的长腺提取物对片状细胞数量有显著影响。与林格氏液对照相比，无毒的长腺产物可使片状细胞数量增加，而有毒提取物则导致其急剧减少，并伴有这些细胞形态的改变。有趣的是，注射P4蛋白后也观察到片状细胞形态的变化，P4蛋白是布氏细蜂雌蜂长腺的主要成分，对果蝇幼虫具有强大的免疫抑制作用。结合其作为Rho-GAP蛋白的预测分子功能，讨论了P4蛋白在抑制宿主细胞免疫中的作用。
