Sousa M, Cunha C, Erkan M, Guerra R, Oliveira E, Baldaia L
Laboratory of Cell Biology, Institute of Biomedical Sciences, University of Porto, Portugal.
Tissue Cell. 2000 Feb;32(1):88-94. doi: 10.1054/tice.1999.0090.
In Scrobicularia plana testis, a nuclear acid phosphatase (ACPase) activity was detected in mid and late spermatids with the improved Gomori-chloride procedure. Lead deposits were first observed in mid spermatids at focal points over condensed chromatin strands, increasing in density as chromatin further condensated. In late spermiogenesis, lead deposits became concentrated between chromatin aggregates, and after total DNA compaction were transfered to the nuclear periphery and then shed into the cytoplasm. The specificity of the nuclear ACPase was tested against different pH values (3.9, 7.2, 7.8, 9.0), substrates (TPP, IDP, TMP, p-NCS, ATP, GTP, AMP, ADP, AMP-PNP) and inhibitors (NaF, levamisole, Zn, vanadate, theophylline). To further specify the nature of this nuclear ACPase, other enzymes were comparatively studied at their optimal pH values and at pH 5.0: nucleoside-diphosphatase, thiamin-pyrophosphatase, inorganic trimetaphosphatase, lysosomal arylsulfatases A and B, ATPase, GTPase, 5'-nucleotidase, adenylate kinase, and adenylate cyclase. Several other controls were introduced to exclude artefactual deposits induced by lead ions and tissue molecules. The results showed that the enzyme has an optimal pH at 5.0, a high specific affinity for beta-GP, and is inhibited by NaF, which suggests that it behaves as a type B-ACPase, and all controls demonstrated the specificity of the enzymic activity. Because lead deposits were specifically and temporally associated with spermatid chromatin condensation, when DNA and RNA synthesis, histones, phosphoproteins and RNA molecules strongly decrease, it is possible to suggest that the nuclear ACPase could be associated with DNA processing during chromatin compaction or involved in the hydrolysis of 2' and 3' nucleotides resulting from nuclear RNase action during RNA degradation.
在扁玉螺睾丸中，采用改良的Gomori - 氯化物法在中期和晚期精子细胞中检测到一种核酸磷酸酶（ACPase）活性。在中期精子细胞中，首先在浓缩染色质链上的焦点处观察到铅沉淀，随着染色质进一步浓缩，密度增加。在精子发生后期，铅沉淀集中在染色质聚集体之间，在DNA完全压缩后转移到核周边，然后释放到细胞质中。针对不同的pH值（3.9、7.2、7.8、9.0）、底物（TPP、IDP、TMP、p - NCS、ATP、GTP、AMP、ADP、AMP - PNP）和抑制剂（NaF、左旋咪唑、Zn、钒酸盐、茶碱）测试了核ACPase的特异性。为了进一步明确这种核ACPase的性质，在其最佳pH值和pH 5.0下对其他酶进行了比较研究：核苷二磷酸酶、硫胺素焦磷酸酶、无机三聚磷酸酶、溶酶体芳基硫酸酯酶A和B、ATP酶、GTP酶、5'-核苷酸酶、腺苷酸激酶和腺苷酸环化酶。引入了其他几个对照以排除由铅离子和组织分子诱导的人为沉淀。结果表明，该酶的最佳pH值为5.0，对β - GP具有高特异性亲和力，并被NaF抑制，这表明它表现为B型ACPase，并且所有对照都证明了酶活性的特异性。由于铅沉淀与精子细胞染色质浓缩在时间和空间上具有特异性关联，此时DNA和RNA合成、组蛋白、磷蛋白和RNA分子强烈减少，因此可以推测核ACPase可能与染色质压缩过程中的DNA加工相关，或者参与RNA降解过程中核核糖核酸酶作用产生的2'和3'核苷酸的水解。
