Suzuki M, Tanaka T
Applied Entomology, Graduate School of Bio-Agricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
J Insect Physiol. 2006 Jun;52(6):602-13. doi: 10.1016/j.jinsphys.2006.02.009. Epub 2006 Mar 2.
Ultrastructural studies on the reproductive tract and venom apparatus of a female braconid, Meteorus pulchricornis, revealed that the parasitoid lacks the calyx region in its oviduct, but possesses a venom gland with two venom gland filaments and a venom reservoir filled with white and cloudy fluid. Its venom gland cell is concaved and has a lumen filled with numerous granules. Transmisson electron microscopic (TEM) observation revealed that virus-like particles (VLPs) were produced in venom gland cells. The virus-like particle observed in M. pulchricornis (MpVLP) is composed of membranous envelopes with two different parts: a high-density core and a whitish low-density part. The VLPs of M. pulchricornis is also found assembling ultimately in the lumen of venom gland cell. Microvilli were found thrusting into the lumen of the venom gland cell and seem to aid in driving the matured MpVLPs to the common duct of the venom gland filament. Injection of MpVLPs into non-parasitized Pseudaletia separata hosts induced apoptosis in hemocytes, particularly granulocytes (GRs). Rate of apoptosis induced in GRs peaked 48h after VLP injection. While a large part of the GR population collapsed due to apoptosis caused by MpVLPs, the plasmatocyte population was minimally affected. The capacity of MpVLPs to cause apoptosis in host's hemocytes was further demonstrated by a decrease ( approximately 10-fold) in ability of host hemocytes to encapsulate fluorescent latex beads when MpVLPs were present. Apparently, the reduced encapsulation ability was due to a decrease in the GR population resulting from MpVLP-induced apoptosis.
对雌性茧蜂（丽蝇蛹集金小蜂）生殖道和毒液器官的超微结构研究表明，该寄生蜂输卵管中没有萼区，但拥有一个毒液腺，其中有两条毒液腺细丝和一个充满白色浑浊液体的毒液储存器。其毒液腺细胞呈凹陷状，有一个充满大量颗粒的管腔。透射电子显微镜（TEM）观察显示，毒液腺细胞中产生了病毒样颗粒（VLPs）。在丽蝇蛹集金小蜂中观察到的病毒样颗粒（MpVLP）由具有两个不同部分的膜包膜组成：一个高密度核心和一个白色低密度部分。丽蝇蛹集金小蜂的VLPs最终也在毒液腺细胞的管腔中组装。发现微绒毛伸入毒液腺细胞的管腔，似乎有助于将成熟的MpVLPs驱赶到毒液腺细丝的共同管道中。将MpVLPs注射到未被寄生的粘虫宿主中会诱导血细胞，特别是粒细胞（GRs）凋亡。GRs中诱导的凋亡率在VLP注射后48小时达到峰值。虽然由于MpVLPs引起的凋亡，大部分GR群体崩溃，但浆血细胞群体受到的影响最小。当存在MpVLPs时，宿主血细胞包裹荧光乳胶珠的能力下降（约10倍），进一步证明了MpVLPs在宿主血细胞中引起凋亡的能力。显然，包裹能力的降低是由于MpVLP诱导的凋亡导致GR群体减少。
