Rizki T M, Rizki Rose M, Grell E H
Department of Zoology, The University of Michigan, 48109, Ann Arbor, Michigan, USA.
Biology Division, Oak Ridge National Laboratory, 37830, Oak Ridge, Tennessee, USA.
Wilehm Roux Arch Dev Biol. 1980 Jun;188(2):91-99. doi: 10.1007/BF00848799.
Black cells (Bc, 2-80.6±) mutant larvae ofDrosophila melanogaster have pigmented cells in the hemolymph and lymph glands. In this report we present evidence that these melanized cells are a mutant form of the crystal cells, a type of larval hemocyte with characteristic paracrystalline inclusions.Bc larvae lack crystal cells. Furthermore, the distribution pattern of black cells inBc larvae parallels that of experimentally-blackened crystal cells in normal larvae (phenocopy).InBc/Bc zygotes black cells appear during mid embryonic development but inBc /Bc zygotes pigmented cells are not found until late in the first larval instar.Crystal cells are present in the heterozygous larvae until this time, and paracrystalline inclusions can be seen in some of the cells undergoing melanization in these larvae.The rate of phenol oxidase activity inBc /Bc larval cell-free extracts is less than half that ofBc /Bc extracts whereas enzyme activity is undetectable inBc/Bc larvae. We propose that theBc gene product is required for maintaining the integrity of the paracrystalline inclusions; inBc/Bc larvae either the product is absent or nonfunctional so an effective contact between substrate and enzyme results in melanization of the cells.Phenol oxidase itself is either destroyed or consumed in the melanization process accounting for the absence of enzyme activity inBc/Bc larvae. These studies confirm that the crystal cells store phenolic substrates and are the source of the hemolymph phenol oxidase activity in the larva ofD. melanogaster.
黑细胞（Bc，2 - 80.6±）突变型果蝇幼虫的血淋巴和淋巴腺中有色素沉着细胞。在本报告中，我们提供证据表明这些黑化细胞是晶体细胞的突变形式，晶体细胞是一种具有特征性平行排列包含物的幼虫血细胞。Bc幼虫缺乏晶体细胞。此外，Bc幼虫中黑细胞的分布模式与正常幼虫中经实验黑化的晶体细胞的分布模式相似（拟表型）。在Bc/Bc合子中，黑细胞在胚胎发育中期出现，但在Bc/Bc合子中，直到一龄幼虫后期才发现有色素沉着细胞。在此之前，杂合幼虫中存在晶体细胞，并且在这些幼虫中一些正在黑化的细胞中可以看到平行排列的包含物。Bc/Bc幼虫无细胞提取物中酚氧化酶活性的速率不到Bc/Bc提取物的一半，而在Bc/Bc幼虫中未检测到酶活性。我们认为Bc基因产物是维持平行排列包含物完整性所必需的；在Bc/Bc幼虫中，要么该产物不存在，要么无功能，因此底物与酶之间的有效接触导致细胞黑化。酚氧化酶本身在黑化过程中要么被破坏，要么被消耗，这就是Bc/Bc幼虫中缺乏酶活性的原因。这些研究证实，晶体细胞储存酚类底物，是果蝇幼虫血淋巴中酚氧化酶活性的来源。
