Lipophorin acts as a shuttle of lipids to the milk gland during tsetse fly pregnancy.
Lipophorin acts as a shuttle of lipids to the milk gland during tsetse fly pregnancy.
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DOI：
10.1016/j.jinsphys.2011.08.009
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发表时间：
2011-11
影响因子：
2.2
通讯作者：
Attardo GM
中科院分区：
文献类型：
--
作者：
Benoit JB;Yang G;Krause TB;Patrick KR;Aksoy S;Attardo GM
在胎生采采蝇怀孕期间，脂质动员对于产生乳汁以喂养发育中的宫内幼虫是必不可少的。脂蛋白（Lp）是昆虫和节肢动物体内主要的脂质转运蛋白。在这项研究中，我们评估了Lp和脂磷脂受体（LpR）在采采蝇繁殖过程中的脂质动员过程中的作用。我们从morsitans morsitans基因组中鉴定出GmmLp和GmmLpR的单基因序列，并测定了GmmLp和GmmLpR在雌性生殖周期中的时空表达。结果表明，gmmlp的表达对成虫脂肪体和幼虫具有特异性。在成年女性中，gmmlp的表达是构成性的。然而，随着幼虫在母亲子宫内成熟，转录水平增加，在分娩前达到峰值表达。在怀孕雌性和幼虫的血淋巴中检测到GmmLp，但在子宫液或幼虫肠道内容物中未检测到GmmLp，排除了GmmLp从母亲直接转移到后代的可能性。在头部、卵巢、中肠、乳腺/脂肪体、卵巢和发育中的幼虫中检测到gmmlpr转录本。gmmlpr的水平在第一个和第二个淋养循环中保持稳定，在第一个淋养循环中观察到轻微的下降。在中肠、脂肪体、乳腺、精囊和头部等多个组织中均检测到GmmLpR。通过RNA干扰抑制gmmlp可导致血淋巴脂质水平降低、卵母细胞发育延迟和幼虫妊娠期延长。同样抑制gmmlpr并没有显著降低血淋巴脂水平或卵发生时间，但确实延长了幼虫发育的时间。因此，GmmLp和GmmLpR分别作为中肠和脂肪体的脂质向卵巢和乳腺的主要通道，为卵母细胞的发育和幼虫的营养提供资源。然而，一旦进入乳腺，脂质显然不是通过脂蛋白而是通过另一种载体脂蛋白转移到发育中的幼虫体内。
During pregnancy in the viviparous tsetse fly, lipid mobilization is essential for the production of milk to feed the developing intrauterine larva. Lipophorin (Lp) functions as the major lipid transport protein in insects and closely-related arthropods. In this study, we assessed the role of Lp and the lipophorin receptor (LpR) in the lipid mobilization process during tsetse reproduction. We identified single gene sequences for GmmLp and GmmLpR from the genome of Glossina morsitans morsitans, and measured spatial and temporal expression of gmmlp and gmmlpr during the female reproductive cycle. Our results show that expression of gmmlp is specific to the adult fat body and larvae. In the adult female, gmmlp expression is constitutive. However transcript levels increase in the larva as it matures within the mother’s uterus, reaching peak expression just prior to parturition. GmmLp was detected in the hemolymph of pregnant females and larvae, but not in the uterine fluid or larval gut contents ruling out the possibility of direct transfer of GmmLp from mother to offspring. Transcripts for gmmlpr were detected in the head, ovaries, midgut, milk gland/fat body, ovaries and developing larva. Levels of gmmlpr remain stable throughout the first and second gonotrophic cycles with a slight dip observed during the first gonotrophic cycle. GmmLpR was detected in multiple tissues, including the midgut, fat body, milk gland, spermatheca and head. Knockdown of gmmlp by RNA interference resulted in reduced hemolymph lipid levels, delayed oocyte development and extended larval gestation. Similar suppresion of gmmlpr did not significantly reduce hemolymph lipid levels or oogenesis duration, but did extend the duration of larval development. Thus, GmmLp and GmmLpR function as the primary shuttle for lipids originating from the midgut and fat body to the ovaries and milk gland to supply resources for developing oocytes and larval nourishment, respectively. Once in the milk gland however, lipids are apparently transferred into the developing larva not by lipophorin but by another carrier lipoprotein.