BIOCHEMICAL CYTOLOGY OF HOST-PARASITE INTERACTIONS IN PARASITIC PROTOZOA

利什曼原虫的细胞生物学被作为一种模型进行研究。 以及胞外寄生。重点放在描述 其表面膜(SM)的生化和生理功能 为了确定它们在寄生虫生存和发展中的作用 发展。 利什曼原虫前鞭毛虫具有许多SM运输系统 某些必需氨基酸和核苷的活跃积累。在……里面 为了识别这些，一系列独特的、放射性标记的底物 设计、合成了特异的亲和结合试剂，并将其用于 原位共价标记杜氏乳杆菌前鞭毛体的SM。是这样的 标记被特异性和竞争性地禁止(&gt；90%+) 存在过多的未标记底物。累积起来，两种不同的， 这些研究确定了面向外部的SM转运体。这个 首先，甲硫氨酸的特异性由2个多肽组成，其中明显 分子量约为54 kDa和56 kDa，第二个是特定的 腺苷转运，由约33个单链多肽链组成 KDA。研究正在进行中，以进一步确定这些必要的特征 蛋白质。SM酸性磷酸酶的其他化学性质是 勾勒出来的。分泌型酸性磷酸酶(SACP)具有 独特的[PO4-6Gal(Beta)，4Man]，与SM相同的重复表位 脂多糖(LPG)。SACP和LPG都是在 并通过高尔基隔间运输。限制和遗传 对野生型和lpg突变体的分析正被用于鉴定基因。 参与液化石油气的表达。获得了SACP基因的420bpDNA编码片段 克隆并用于鉴定和分离该基因的全长拷贝。 设计了连续试管培养的方法。 多诺氏乳杆菌在37℃时的“无鞭毛体”形态。 这种形式应该有助于研究寄生虫受调控的基因。 差异化发展。 目前的结果对改进的发展具有重要意义 诊断、化疗和免疫预防药物。

The cell biology of Leishmania is investigated as a model of both intra- and extracellular parasitism. Emphasis is placed on characterizing the biochemical and physiological functions of its surface membrane (SM) and secreted components toward defining their roles in parasite survival and development. Leishmania promastigotes possess a number of SM transport systems for the active accumulation of certain essential amino acids and nucleosides. In order to identify these, a series of unique, radiolabeled, substrate specific, affinity-binding reagents were devised, synthesized and used to covalently label the SM of living L. donovani promastigotes in situ. Such labeling was specifically and competitively inhibited (>90+%) in the presence of excess unlabeled substrate. Cumulatively, two different, externally oriented, SM transporters are identified in these studies. The first, specific for methionine was composed of 2 polypeptides with apparent molecular weights of about 54 and 56 kDa and the second was specific for adenosine transport and consisted of a single polypeptide chain of about 33 kDa. Studies are in progress to further characterize these essential proteins. Additional chemical properties of the SM acid phosphatase were delineated. The secretory acid phosphatase (SACP) was shown to possess the unique [PO4-6Gal(beta),4Man], repetitive epitope in common with the SM lipophophoglycan (LPG). Both SAcP and LPG were terminally co-processed in and transported through the Golgi compartment. Restriction and genetic analyses of wild type and LPG- mutants are being used to identify genes involved in LPG expression. A 420 bp DNA coding fragment for SAcP was cloned and used to identify and isolate a full length copy of this gene. Methods are devised for the continuous in vitro cultivation of "amastigote-like" forms of L. donovani at 37 degrees C. The availability of such forms should facilitate studies of parasite gene regulated differentiation and development. The current results are of relevance toward the development of improved diagnostic, chemotherapeutic and immunoprophylactic agents.