[123I-MIBG scintigraphy in patients with neuroblastoma]

123I-meta-iodobenzylguanidine (123I-MIBG) scintigraphy was performed in 9 patients who were suspected to have a neuroblastoma. Positive images were obtained in 4 patients who had a neuroblastoma. Negative images were obtained in 5 patients who did not have a neuroblastoma. 123I-MIBG scan revealed an active tumor in a patient who had received intensive chemotherapy for the recurrence of neuroblastoma with returning of all tumor markers including neuron specific enolase to normal range. This indicated that 123I-MIBG scan can be used to assess the effect of therapy.

Ultrastructural localization of carbonyl reductase in mouse lung

The immunocytochemical localization of tetrameric carbonyl reductase in the mouse lung was determined by an electron-microscopical immunogold procedure using monospecific antibodies against the enzyme. The labelling of carbonyl reductase was observed within the mitochondria of the ciliated and non-ciliated cells of the bronchioles and the type II alveolar pneumocytes, and the density of labelling in the non-ciliated cells was higher than those in the other cells. No significant labelling was detected over other compartments of the epithelial cells. The labelling was undetectable in the type I alveolar cells, alveolar macrophages and connective tissue cells of the lung. These results clearly indicate the localization of carbonyl reductase to the mitochondrial matrix of these epithelial cells, of which the non-ciliated bronchiolar cells contained particularly high amounts of the enzyme.

Kinetic studies on the plasminogen activation by the staphylokinase-plasmin complex

A pure complex of staphylokinase and plasmin was prepared by affinity chromatography with lysine-Sepharose, which enabled the simple analysis of the mechanism of plasminogen activation by staphylokinase. We used a truncated staphylokinase (SAK), which lacks the 10 amino acid residues at the NH2 terminal of native staphylokinase. The purity of this complex was confirmed by the native PAGE profile. Image analysis of the SDS-PAGE profile revealed that the molar ratio of plasmin and SAK in the complex was about 1:1. Using this SAK-plasmin complex, the kinetic parameters for the activation of Glu- or Lys-plasminogen were determined. The kinetic constant, kcat/Km, obtained when Lys-plasminogen was used as a substrate was approximately 10 times higher than that obtained when Glu-plasminogen was used. This plasminogen activation property of the SAK-plasmin complex was comparable to that of other plasminogen activators, such as streptokinase, urokinase, and tissue-type plasminogen activator (t-PA). This SAK-plasmin complex will simplify the elucidation of plasminogen activation by SAK. Through kinetic studies, the fibrin specificity and participation of plasminogen activator inhibitor will be clarified.

Phylogenetic evidence for Sphingomonas and Rhizomonas as nonphotosynthetic members of the alpha-4 subclass of the Proteobacteria

To clarify the taxonomic relationships of the genera Rhizomonas and Sphingomonas, the 16S rRNA sequence of Rhizomonas suberifaciens IFO 15211T (T = type strain) was determined. A phylogenetic analysis of aligned 16S rRNA gene sequences revealed that eight species of the genus Sphingomonas and R. suberifaciens are closely related to Erythrobacter longus and Porphyrobacter neustonensis and, therefore, belong in the alpha-4 subclass of the Proteobacteria. Within this subclass, Sphingomonas species and R. suberifaciens are phylogenetically interrelated and comprise several subgroups. Our findings show that the genus and species definitions of these organisms are in need of revision.

Living related liver transplantation across ABO blood groups with FK506 and OKT3

In living related liver transplantation (LRLT), the use of graft livers across ABO blood groups is unavoidable since the organ donor is usually one of the recipient's parents. This report presents our initial experiences with LRLT, focusing on ABO-incompatible cases. From June 1990 to May 1992, we successfully performed a series of 34 LRLT on children (15 males and 19 females) ranging in age from 7 months to 15 years. Overall recipient survival rates were 90% (25/28) in elective LRLT and 50% (3/6) in emergency LRLT. These cases were classified into three groups: ABO blood group-identical (n = 21), compatible (n = 10), and incompatible (n = 3). The immunosuppressive regimen consisted of FK506 and low-dose steroids in the first two groups. In the incompatible cases, exchange transfusion was performed to decrease anti-A and/or -B antibody titers before LRLT, and prophylactic OKT3 was added to FK506 and steroids after LRLT. No significant difference in recipient and graft survival was observed among the groups. In the identical group, no rejection episodes have been observed thus far. Rejection occurred in two out of the ten compatible cases. Among the incompatible cases, one recipient had mild rejection and was treated. The remaining two recipients have had no rejection episodes thus far. Although all three recipients had cytomegalovirus (CMV) infection, they were successfully treated with ganciclovir, and no lethal infection has developed in any of these cases. The present results suggest that graft livers from living related donors across ABO blood groups can function well with FK506, low-dose steroids, and prophylactic OKT3 without causing lethal complications.

Extramedullary tumor as presentation of leukemia: establishment of a new human GPIIb- and GPIIIa-positive leukemia cell line

A 25-year-old man noted swelling of the right cervical lymph nodes in October 1983. Diagnosis of malignant lymphoma was made on the basis of pathological examination of biopsies. Despite both chemotherapy and irradiation treatment, blast cells appeared in the peripheral blood and bone marrow in April 1984. Immunophenotypic analysis demonstrated that the blasts in the patient's peripheral blood expressed CD13, CD33, CD41a, and no markers for T or B lymphocytes, suggesting that he had been suffering from megakaryocytic sarcoma. We established a new cell line derived from the blasts in the peripheral blood, designated KH184. KH184 cells expressed glycoprotein (GP) Ib (CD42b) and GPIIb/IIIa (CD41a), while platelet peroxidase (PPO) activity was negative in an ultrastructural study. Both Northern blot and flow cytometric analysis of surface antigens and DNA content revealed that treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) did not induce the maturation of these cells. Various cytokines such as interleukin 3 (IL-3), interleukin 6 (IL-6), and leukemia inhibitory factor (LIF) had no effect in promoting the growth of KH184 cells. KH184 cells expressing CD41a seem to possess unusual characteristics. KH184 cells, human GPIIb- and GPIIIa-positive leukemia cells, which lack response to TPA-induced differentiation, provide a new and unique model for the characterization of factors that are implicated in the terminal differentiation of megakaryocytes, and should aid in studies of the mechanism underlying the occurrence of megakaryocytic sarcoma.

Type VI collagen in the rat testis: monoclonal antibody, isolation, and localization during development

To investigate the components of the seminiferous tubule extracellular matrix (ST-ECM), monoclonal antibodies were raised against ST-ECM. One of these (15B6) recognized the nonreduced form of type VI collagen. With this antibody as a probe, type VI collagen was isolated from an SDS-urea extract of ST-ECM. It took a tetrameric form, and upon reduction dissociated into a major 140-kDa band and two bands at 190 and 210 kDa. Developmental changes in the distribution of type VI collagen were investigated by immunofluorescence microscopy. In 16-day rat embryos when myoid cells began to differentiate, type VI, collagen was seen in the urogenital mesentery, and it had begun to surround the gonad and, in some embryos, the seminiferous cords. In newborn rats, it was found throughout the extracellular spaces between the cords, being localized in the interstitium. In adults, however, it was confined to two parallel lines around the seminiferous tubules and to filamentous structures in the adventitia of vascular systems. Immunoelectron microscopy showed that this collagen was distributed in the interstitium independently from collagenous fibrils, but was excluded from the basal lamina of Sertoli cells. These observations indicate that type VI collagen is a major component of the ST-ECM and that it may be important in the organization of the matrix and in the differentiation of peritubular cells.

Effects of subacute administration of methamphetamine and nicotine on locomotor activity in transgenic mice expressing the human tyrosine hydroxylase gene

We produced transgenic (Tg) mice carrying the human tyrosine hydroxylase (TH) gene. To investigate differences in the dopaminergic (DAergic) neuronal activity between the Tg and nTg mice, we examined changes in the locomotor activity induced by methamphetamine (MAP) and nicotine (NIC), which enhances DA release and induces TH enzyme activation, respectively. Surprisingly, however, the intensity of MAP (2.5 mg/kg, once a day for 14 days)-induced hyperlocomotion in the nTg mice was greater than that in the Tg mice, and, furthermore, the Tg mice were less sensitive to subacute administration of NIC (0.5 mg/kg, once a day for 14 days) than the nTg mice. These results suggest that DAergic neuronal function is suppressed in Tg mice to compensate for the overexpression of TH.

Nicotine-induced regulation of tyrosine hydroxylase activity in adrenal gland of transgenic mouse carrying human tyrosine hydroxylase gene

We investigated the effect of subcutaneous injection of nicotine on in vitro tyrosine hydroxylase (TH) activity in adrenal gland and brain of the transgenic mice carrying an 11-kb fragment containing the entire human TH gene. Injection of 5 mg nicotine/kg (as free base) for 3 days caused a statistically significant increase in vitro TH activity in the adrenal gland, whereas brain TH activity was not affected at all. The adrenal gland of non-transgenic C57BL/6J mice treated in the same way as for transgenic mice tended to enhance TH activity, although not to a significant level. This observation might indicate the possibility that the machinery used by nicotine in regulating the properties or expression of TH in the adrenal gland should be similar between transgenic and non-transgenic mice.

Molecular basis of beta-thalassemia in Japan: heterogeneity and origins of mutations

Characterization of beta-thalassemia mutations was attempted for 13 unrelated Japanese patients heterozygous for beta-thalassemia. We have systematically analyzed beta-thalassemia genes using polymerase-chain-reaction-related techniques; dot blot hybridization with oligonucleotide probes complementary to known mutations, restriction endonuclease assay and direct sequencing of amplified genomic DNA. Seven different mutations were detected. Six of them are an amber mutation in codon 90 (GAG to TAG), a four-base-pair deletion in codons 41 and 42 causing premature termination due to frameshift, a C-T substitution at position 654 of IVS-2, a G-A substitution at position 1 of IVS-2 and a C-G substitution at position 848 of IVS-2, leading to splicing defects, and an ocher mutation (GAA-TAA) in codon 121 causing a thalassemia intermedia phenotype with inclusion body formation in erythrocytes. A silent mutation (CTG-TTG) was also detected in codon 91 of the allele with the IVS-2 position 1 mutation. These mutations have been reported previously in the Japanese population. The other mutation is a novel one in the Japanese, an amber mutation (TGG-TAG) in codon 15, causing a beta zero-thalassemia phenotype by premature termination of the beta-globin chain synthesis. We analyzed haplotypes of chromosomes bearing each beta-thalassemia mutation. Origins and a spectrum of mutations in comparison with those detected in malaria-endemic regions are discussed.

Inhibition of erythroid differentiation by stem cell factor in K562 cells expressing the c-kit gene

We found a K562 subclone (K562YO) that highly expressed the c-kit gene. K562YO had a higher capability of erythroid differentiation by hemin and cytosine arabinoside (Ara-C) than its parent K562 (KIT-). We obtained the transfectant expressing c-kit by introducing c-kit cDNA into K562 (KIT-). The differentiation of the transfectant was similar to that of the parent cell. Thus the difference described above was not due to the expression of c-kit. Next, we investigated the effects of stem cell factor (SCF) on the differentiation of the K562 cell expressing c-kit. SCF did not enhance the cell growth of K562YO. On the other hand, SCF suppressed induction of benzidine-positive cells when c-kit-positive cells were treated with hemin and Ara-C, especially at a low concentration. Furthermore, c-kit mRNA and protein were down-regulated during erythroid differentiation. SCF also downregulated the c-kit proteins. Our results suggest that the SCF/c-kit signals could act negatively for erythroid differentiation of the K562 cells expressing c-kit. K562YO is also useful for studying the mechanism that controls the expression of the c-kit gene because there is a K562 counterpart cell line that does not express this gene.

Selective inhibition of human immunodeficiency virus type 1 replication by novel fluoroalkylated oligomers in vitro

Several fluoroalkylated oligomers were found to be potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) in vitro. Among the test compounds, bis(perfluoro-1,4,7,10-tetramethyl-2,5,8,11-tetraoxatetradecyl+ ++)methacrylic acid oligomer (MAA-HFPO5) emerged as the most potent inhibitor of HIV-1 replication. Its 50% antivirally effective concentration for the IIIB strain was 2.8 mu g/ml, whereas the compound did not affect the growth and viability of mock-infected MT-4 cells at concentrations < or = 100 micrograms/ml. MAA-HFPO5 was also inhibitory to other strains of HIV-1 in various human T-cell systems, including peripheral blood lymphocytes. MAA-HFPO5 inhibited syncytium formation and virus adsorption. The combination of MAA-HFPO5 with either 3'-azido-3'dioxythymidine or dextran sulfate resulted in an additive effect. Thus, fluoroalkylated oligomers are novel HIV-1 inhibitors that warrant further evaluation of their therapeutic potential.

Different ratios in 20 S proteasomes and regulatory subunit complexes in two isoforms of the 26 S proteasome purified from rabbit skeletal muscle

A ubiquitin/ATP-dependent proteinase complex (26 S proteasome) was highly purified from rabbit skeletal muscle. The purified 26 S proteasome easily dissociated into a 20 S proteasome and a regulatory subunit complex on non-denaturing PAGE. By using cleavable and non-cleavable cross-linkers, it was revealed that the 26 S proteasome exists in two isoforms: one (D complex) consists of the 20 S proteasome and the regulatory subunit complex in the ratio of one to two, while the other (C complex) exists in an equal molar ratio. Molecular masses of the former and the latter isoforms were estimated to be 1,700 kDa and 1,400 kDa, respectively, by gel filtration, and 2,400 kDa and 1,400 kDa, respectively, by Ferguson plot analysis. Furthermore, both isoforms efficiently hydrolyzed Suc-Leu-Leu-Val-Tyr-MCA and ubiquitin-conjugated [125I]lysozyme. These results suggest that the D and C complexes are active proteinase complexes, most probably corresponding to the dumbbell-like and mushroom-like (or space capsule-like) molecules, respectively.

Monkey 3-deoxyglucosone reductase: tissue distribution and purification of three multiple forms of the kidney enzyme that are identical with dihydrodiol dehydrogenase, aldehyde reductase, and aldose reductase

3-Deoxyglucosone (3DG) is a reactive intermediate in the glucose-mediated cross-linking of proteins. An enzyme catalyzing the reduction of 3DG is thought to prevent the damage to protein by the formation of 3DG. The NADPH-dependent enzyme activity was detected in the extracts of various monkey tissues, among which kidney exhibited the highest specific activity. One dimeric enzyme with subunit M(r) of 39,000 and two monomeric enzymes with M(r) of 38,000 and 34,000 were purified from monkey kidney. The dimeric enzyme exhibited high dihydrodiol dehydrogenase activity and was immunochemically identical to dimeric dihydrodiol dehydrogenase of monkey kidney. The two monomeric enzymes exhibited aldehyde reductase activity, but were clearly distinct from each other in substrate specificity, inhibitor sensitivity, and effect of sulfate ions. One enzyme was immunologically cross-reacted with human liver aldehyde reductase, whereas sequence data of digested peptides from the other enzyme revealed > 97% identity with human placental aldose reductase. Comparison of kinetic constants among the monkey kidney enzymes and aldoketo reductases from several mammalian tissues indicated that dimeric dihydrodiol dehydrogenase and aldose reductase exhibited higher catalytic efficiency for 3DG than did aldehyde reductase, carbonyl reductase, and monomeric dihydrodiol dehydrogenase.

Purification and properties of N-acetylglucosaminidase from eggs of the ascidian, Halocynthia roretzi

In several ascidians, beta-D-N-acetylglucosaminidase (GlcNAcase) released from eggs following fertilization is proposed to play a key role in polyspermy block through its binding to the sperm receptor on the vitelline coat [C. C. Lambert (1989) Development 105, 415-420]. In the ascidian Halocynthia roretzi, GlcNAc-specific lectins inhibited the fertilization most strongly among various lectins. Furthermore, GlcNAcase activity was released from the eggs in response to the egg activation. The GlcNAcase was purified from the eggs to apparent homogeneity by chromatographies on DEAE-Toyopearl, SP-Toyopearl, Toyopearl HW-65, and Mono S. The purified enzyme gave a single band on isoelectric focusing with an isoelectric point of 7.0. It gave two bands on SDS/PAGE: the molecular masses of the bands were estimated to be 65 kDa/66 kDa, and 84 kDa/85 kDa under reducing/non-reducing conditions, respectively. The two bands were found to converge to a single band of 56 kDa after deglycosylation, which suggests microheterogeneity in the sugar moiety. The enzyme showed an oligomeric structure with an apparent molecular mass of 520 kDa, estimated by gel filtration. The optimum pH of the activity was around 4.5. The enzyme hydrolyzed both 4-methylumbelliferyl-GlcNAc and 4-methylumbelliferyl-GalNAc, suggesting that it should be characterized as a beta-D-N-acetylhexosaminidase, with Km values of 1.2 mM and 0.52 mM, respectively. The purified enzyme was found to be capable of binding to the vitelline coat in a GlcNAc-specific manner. Immunoblot analysis using antibody raised against the purified GlcNAcase revealed that the enzyme itself is released from the eggs upon fertilization. Thus, the GlcNAcase purified in this study is released from eggs following fertilization and bound to the vitelline coat in order to function in the polyspermy blocking mechanism.

Alpha-fetoprotein-producing esophageal adenocarcinoma: report of a case

This paper describes a rare case of adenocarcinoma located in the middle portion of the esophagus with liver metastasis. An 80-year-old man was admitted to our hospital with dysphagia and vomiting, following which an upper gastrointestinal series and esophagoscopy located an elevated-type carcinoma in the middle thoracic esophagus. Computed tomography revealed an esophageal tumor invading the left atrium and aorta, and multiple intrathoracic lymph node swellings, and an ultrasonograph of the liver showed multiple liver metastases. The serum carcinoembryonic antigen, carbohydrate antigen 19-9, and squamous cell carcinoma-related antigen levels were normal, but the serum alpha-fetoprotein (AFP) level was 351.5 ng/ml. The patient died 124 days after undergoing an esophageal bypass operation. On post-mortem histological examination, the original esophageal tumor was diagnosed as a poorly differentiated adenocarcinoma without a squamous component and immunohistochemical staining for AFP showed positive granules in the cytoplasm. All the metastatic nodules, including the lymph nodes, liver, spleen, and lungs, showed the same histological type and AFP-staining pattern as the original esophageal tumor. To our knowledge, this is the first case of AFP-producing esophageal carcinoma to be reported in Japan.

Living related liver transplantation across ABO blood groups with FK506 and OKT3

In living related liver transplantation (LRLT), the use of graft livers across ABO blood groups is unavoidable since the organ donor is usually one of the recipient's parents. This report presents our initial experiences with LRLT, focusing on ABO-incompatible cases. From June 1990 to May 1992, we successfully performed a series of 34 LRLT on children (15 males and 19 females) ranging in age from 7 months to 15 years. Overall recipient survival rates were 90% (25/28) in elective LRLT and 50% (3/6) in emergency LRLT. These cases were classified into three groups: ABO blood group-identical (n = 21), compatible (n = 10), and incompatible (n = 3). The immunosuppressive regimen consisted of FK506 and low-dose steroids in the first two groups. In the incompatible cases, exchange transfusion was performed to decrease anti-A and/or -B antibody titers before LRLT, and prophylactic OKT3 was added to FK506 and steroids after LRLT. No significant difference in recipient and graft survival was observed among the groups. In the identical group, no rejection episodes have been observed thus far. Rejection occurred in two out of the ten compatible cases. Among the incompatible cases, one recipient had mild rejection and was treated. The remaining two recipients have had no rejection episodes thus far. Although all three recipients had cytomegalovirus (CMV) infection, they were successfully treated with ganciclovir, and no lethal infection has developed in any of these cases. The present results suggest that graft livers from living related donors across ABO blood groups can function well with FK506, low-dose steroids, and prophylactic OKT3 without causing lethal complications.

Saponins from leaves of Acanthopanax sieboldianus

Two new triterpenoid saponins named sieboldianoside A and B were isolated from the leaves of Acanthopanax sieboldianus together with five known triterpenoid saponins, kalopanax-saponins A and B, saponin A, CP3, sapindoside B, and a known flavonol glycoside, kaempferol 3-O-rutinoside. On the basis of chemical and spectral evidence, the structures of the new saponins (sieboldianoside A and B) were concluded to be alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)- beta-D-glucopyranosyl esters of hederagenin and oleanolic acid 3-O-beta-D- xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopy ranosides, respectively.

Proposal for rejection of Agrobacterium tumefaciens and revised descriptions for the genus Agrobacterium and for Agrobacterium radiobacter and Agrobacterium rhizogenes

The 16S rRNA sequences of seven representative Agrobacterium strains, eight representative Rhizobium strains, and the type strains of Azorhizobium caulinodans and Bradyrhizobium japonicum were determined. These strains included the type strains of Agrobacterium tumefaciens, Agrobacterium rhizogenes, Agrobacterium radiobacter, Agrobacterium vitis, Agrobacterium rubi, Rhizobium fredii, Rhizobium galegae, Rhizobium huakuii, Rhizobium leguminosarum, Rhizobium loti, Rhizobium meliloti, and Rhizobium tropici. A phylogenetic analysis showed that the 15 strains of Agrobacterium and Rhizobium species formed a compact phylogenetic cluster clearly separated from the other members of the alpha subclass of the Proteobacteria. However, Agrobacterium species and Rhizobium species are phylogenetically entwined with one another, and the two genera cannot be separated. In the Agrobacterium species, the strains of biovar 1, biovar 2, Agrobacterium rubi, and Agrobacterium vitis were clearly separated. The two biovars exhibited homogeneity in their phenotypic, chemotaxonomic, and phylogenetic characteristics, and two species should be established for the two biovars. We considered the nomenclature of the two biovars, and revised descriptions of Agrobacterium radiobacter (for the biovar 1 strains) and Agrobacterium rhizogenes (for the biovar 2 strains) are proposed. The name Agrobacterium tumefaciens is rejected because the type strain of this species was assigned to Agrobacterium radiobacter, and consequently the description of the genus Agrobacterium is revised.

Physarum vitronectin-like protein has extensive homology to dihydrolipoamide acetyltransferase

Physarum vitronectin-like protein with a molecular mass of 70 kDa cross-reacts with anti-bovine vitronectin and promotes cell-spreading (Miyazaki, K. et al. 1992. Exp. Cell Res., 199: 106-110.). The amino-terminal sequence of Physarum vitronectin-like protein is, however, distinct from those of animal vitronectins but shows significant sequence homology with dihydrolipoamide acetyltransferase, a component of pyruvate dehydrogenase complex. We have investigated the structural relationships between Physarum vitronectin-like protein and dihydrolipoamide acetyltransferase by using both antibody and protein-chemical methods. The vitronectin-like protein reacted with both anti-bovine vitronectin IgG and anti-rat pyruvate dehydrogenase complex IgG, indicating that it shares common antigenic determinant(s) with rat pyruvate dehydrogenase complex. Furthermore, sequencing studies of peptides obtained by lysylendopeptidase digestion indicated that internal sequences of Physarum vitronectin-like protein show significant homology with dihydrolipoamide acetyltransferase, but do not show any homology with the primary structures of authentic vitronectins. Immunocytochemistry revealed that the protein is widely localized in cytoplasm and nuclei of Physarum polycephalum, but is not present in the central area of vacuoles. Our results indicate that Physarum vitronectin-like protein is a molecule structurally and immunologically related to dihydrolipoamide acetyltransferase but functionally similar to animal vitronectin, although its localization is unique.

Effects of protease inhibitors on binding of sperm to the vitelline coat of ascidian eggs: implications for participation of a proteasome (multicatalytic proteinase complex)

Among various protease inhibitors, chymostatin (an inhibitor of sperm chymotrypsin-like protease) strongly inhibited the binding of sperm to the vitelline coat of glycerinated eggs of the ascidian Halocynthia roretzi, whereas leupeptin (an inhibitor for sperm acrosin), antipain, and soybean trypsin inhibitor had no significant inhibitory effects. Dansyl-Val-Pro-argininal (an inhibitor of the sperm trypsin-like protease, spermosin) had an inhibitory effect on the binding of sperm that was much smaller than its effects on fertilization. Since the sperm chymotrypsin-like protease that is involved in ascidian fertilization has been identified as a proteasome (multicatalytic proteinase complex), we tested the effects of several peptidyl argininals, inhibitors of the activities of proteasomes, on this binding process. The ranking of the inhibitory effects of these compounds on the binding of sperm was the same as that of their effects on the chymotrypsin-like activity of the proteasome, reported previously. The potent inhibitors of binding used in these studies had no or minimal effects on sperm motility. These results suggest that a sperm chymotrypsin-like protease (most probably the chymotrypsin-like protease in the proteasome) plays a key role in binding of sperm to the vitelline coat of the ascidian egg.