The occurrence of chitin in the hemocytes of invertebrates
The occurrence of chitin in the hemocytes of invertebrates
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DOI：
10.1016/j.zool.2011.02.002
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发表时间：
2011-09-01
期刊：
影响因子：
2
通讯作者：
McFall-Ngai, Margaret J.
中科院分区：
文献类型：
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作者：
Heath-Heckman, Elizabeth A. C.;McFall-Ngai, Margaret J.
夏威夷短尾乌贼 Euprymna scolopes 的光器官共生是研究动物与微生物相互作用的有用模型。最近的分析表明，几丁质分解产物在 E. scolopes 与其细菌共生体费氏弧菌之间的通讯中发挥着重要作用。在这项研究中，我们试图确定共生器官中几丁质的来源。我们使用与荧光素缀合的市售几丁质结合蛋白（CBP）来标记宿主组织中的聚合几丁质。共聚焦显微镜显示，与探针标记的共生体接触的唯一细胞是巨噬细胞样血细胞，它们进入细菌所在的光器官隐窝。用纯化的几丁质酶处理后，CBP 对提取的血细胞的标记明显减少，进一步证明标记分子是聚合几丁质。此外，CBP 阳性区域与卤化物过氧化物酶抗体和溶酶体标记物 Lysotracker 共定位，表明几丁质样生物分子出现在溶酶体或酸性液泡中。血细胞的逆转录聚合酶链反应（PCR）揭示了编码几丁质合酶的mRNA，表明血细胞从头合成几丁质。最后，在调查其他无脊椎动物物种的血细胞时，我们在所有检查的颗粒血细胞中观察到 CBP 阳性区域，表明这一特征是无脊椎动物的共同特征；我们取样的脊椎动物血细胞没有用 CBP 标记。尽管类几丁质材料的功能仍未确定，但它在无脊椎动物血细胞中的存在和亚细胞位置表明这种多糖在不同动物的免疫系统中具有保守的作用。 (C) 2011 爱思唯尔有限公司。版权所有。
The light-organ symbiosis of Euprymna scolopes, the Hawaiian bobtail squid, is a useful model for the study of animal-microbe interactions. Recent analyses have demonstrated that chitin breakdown products play a role in communication between E. scolopes and its bacterial symbiont Vibrio fischeri. In this study, we sought to determine the source of chitin in the symbiotic organ. We used a commercially available chitin-binding protein (CBP) conjugated to fluorescein to label the polymeric chitin in host tissues. Confocal microscopy revealed that the only cells in contact with the symbionts that labeled with the probe were the macrophage-like hemocytes, which traffic into the light-organ crypts where the bacteria reside. Labeling of extracted hemocytes by CBP was markedly decreased following treatment with purified chitinase, providing further evidence that the labeled molecule is polymeric chitin. Further, CBP-positive areas co-localized with both a halide peroxidase antibody and Lysotracker, a lysosomal marker, suggesting that the chitin-like biomolecule occurs in the lysosome or acidic vacuoles. Reverse transcriptase polymerase chain reaction (PCR) of hemocytes revealed mRNA coding for a chitin synthase, suggesting that the hemocytes synthesize chitin de novo. Finally, upon surveying blood cells from other invertebrate species, we observed CBP-positive regions in all granular blood cells examined, suggesting that this feature is a shared character among the invertebrates; the vertebrate blood cells that we sampled did not label with CBP. Although the function of the chitin-like material remains undetermined, its presence and subcellular location in invertebrate hemocytes suggests a conserved role for this polysaccharide in the immune system of diverse animals. (C) 2011 Elsevier GmbH. All rights reserved.