Correlation Between the Molecular Structure and the Biological Activity of Co-ARIS, a Cofactor for Acrosome Reaction-Inducing Substance

Two components in the egg jelly are required for inducing the acrosome reaction in starfish; a sulfated glycoprotein called acrosome reaction-inducing substance (ARIS) and its cofactor called Co-ARIS. Three distinct molecules were isolated as the major Co-ARIS' and designated as Co-ARIS' I, II and III. Structural analysis of Co-ARIS' revealed that they are steroidal saponins comprising a sulfated steroid and a pentasaccharide chain. Co-ARIS' I and II differ only in the steroidal side chain. In the presence of ARIS, each Co-ARIS induced the acrosome reaction with a maximal effect at 100–200 μM (Co-ARIS I) or 25–50 μM (Co-ARIS' II and III). Mixtures of Co-ARIS' I, II and III were more effective than the individuals. The activity of Co-ARIS was considerably reduced by solvolytic desulfation but was not affected at all by periodate oxidation. Reduction by NaBH₄ decreased the activity of Co-ARIS I and enhanced that of Co-ARIS II. Treatment of Co-ARIS III with NaBH₄ did not affect the activity as anticipated from its structure. These results suggest that the sulfate moiety and the side chain of steroid are important for the activity of Co-ARIS. The saccharide chain, however, seems not necessarily to be strictly specified for the activity.     

Accumulation of Trehalose as a Compatible Solute under Osmotic Stress in Euglena gracilis Z

ABSTRACT. The photosynthetic protozoon Euglena gracilis, accumulated a large amount of trehalose in the cells under salt or osmotic stresses. Radioactivity of [14C] paramylon, a β-1,3-polyglucan which was stored in the cells of E. gracilis. was degraded rapidly and this radioactivity was almost stoichiometrically incorporated into trehalose. The interconversion of trehalose from paramylon by salt or osmotic stresses was dependent on the concentrations or osmotic pressures, suggesting that E. gracilis accumulate trehalose as an osmoprotectant. After the removal of salt or osmotic stresses, trehalose was gradually degraded, however, it was not converted into paramylon.     

Population structure of wild wheat D‐genome progenitor Aegilops tauschii Coss.: implications for intraspecific lineage diversification and evolution of common wheat

Aegilops tauschii Coss. is the D‐genome progenitor of hexaploid wheat. Aegilops tauschii, a wild diploid species, has a wide natural species range in central Eurasia, spreading from Turkey to western China. Amplified fragment length polymorphism (AFLP) analysis using a total of 122 accessions of Ae. tauschii was conducted to clarify the population structure of this widespread wild wheat species. Phylogenetic and principal component analyses revealed two major lineages in Ae. tauschii. Bayesian population structure analyses based on the AFLP data showed that lineages one (L1) and two (L2) were respectively significantly divided into six and three sublineages. Only four out of the six L1 sublineages were diverged from those of western habitats in the Transcaucasia and northern Iran region to eastern habitats such as Pakistan and Afghanistan. Other sublineages including L2 were distributed to a limited extent in the western region. Subspecies strangulata seemed to be differentiated in one sublineage of L2. Among three major haplogroups (HG7, HG9 and HG16) previously identified in the Ae. tauschii population based on chloroplast variation, HG7 accessions were widely distributed to both L1 and L2, HG9 accessions were restricted to L2, and HG16 accessions belonged to L1, suggesting that HG9 and HG16 were formed from HG7 after divergence of the first two lineages of the nuclear genome. These results on the population structure of Ae. tauschii and the genealogical relationship among Ae. tauschii accessions should provide important agricultural and evolutionary knowledge on genetic resources and conservation of natural genetic diversity.     

The Expression of Tyrosinase,Tyrosinase-Related Proteins 1 and 2 (TRP1 and TRP2), the Silver Protein,and a Melanogenic Inhibitor in Human Melanoma Cells of Differing Melanogenic Activities

The expression of various melanogenic proteins, including tyrosinase, the tyrosinase-related proteins 1 (TRP1) and 2 (TRP2/DOPAchrome tautomerase), and the silver protein in human melanocytes was studied in six different human melanoma cell lines and compared to a mouse derived melanoma cell line. Analysis of the expression of tyrosinase, TRP1, TRP2, and the silver protein using flow cytometry revealed that in general there was a positive correlation between melanin formation and the expression of those melanogenic enzymes. Although several of the melanoma cell lines possessed significant activities of TRP2, the levels of DOPAchrome tautomerase in extracts of human cells were relatively low compared to those in murine melanocytes. Melanins derived from melanotic murine JB/MS cells, from melanotic human Ihara cells and HM-IY cells, from sepia melanin, and from C57BL/6 mouse hair were chemically analyzed. JB/MS cells, as well as Ihara cells and HM-TY cells, possessed significant amounts of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) derived melanins, this being dependent on the activity of TRP2. Kinetic HPLC assays showed that 5,6-dihydroxyindole (DHI) produced during melanogenesis was metabolized quickly to melanin in pigmented KHm-1/4 cells, whereas DHI was stable in amelanotic human SK-MEL-24 cells. A melanogenic inhibitor that has been purified from SK-MEL-24 cells that suppressed oxidation of DHI in the presence or absence of tyrosinase, but had no effect on DHICA oxidation. The sum of these results suggest that the expression of melanogenic enzymes as well as the activity of a melanogenic inhibitor are critical to the production of melanin synthesis in humans.     

FIRST RECORD OF THE CIRRIPEDE GENUS STRAMENTUM (THORACICA, SCALPELLIFORMES) FROM THE UPPER CRETACEOUS OF JAPAN

Abstract:  The scalpelliform genus Stramentum is described from upper Turonian–Coniacian (Upper Cretaceous) strata in the Mikasa area, Hokkaido (Japan), documenting the first record of the genus from the north-west Pacific Realm. The single articulated skeleton, which is horizontally embedded in a dark grey laminated mudstone, is specifically indeterminate because capitular plates are missing. However, peduncular morphology resembles that of S. ( S .) pulchellum (Sowerby Jr), which has been described from the Cenomanian–Turonian of Europe. The present record from Japan demonstrates that this cirripede genus had a wider geographic distribution than previously assumed during the youngest phase of its radiation.     

Induction of the Acrosome Reaction in Starfish

In the starfish, Asterias amurensis , at least two distinct components of the egg jelly are required for inducing the acrosome reaction: a sulfated glycoprotein named acrosome reaction-inducing substance (ARIS) and a diffusible organic substance(s) named Co-ARIS. The following evidence suggested that ARIS and Co-ARIS cooperatively activate CA-channels of the sperm plasma membrane and eventually induce dramatic changes in sperm morphology, the acrosome reaction. 1) Pronase digest of ARIS (P-ARIS) and Co-ARIS, either as a pure or a crude preparation (Fraction M₈), were fully effective in combination for induction of the acrosome reaction in normal sea water, although they were not effective individually. P- ARIS alone induced the acrosome reaction fully in high Ca²⁺ sea water and markedly at high pHs, whereas Fraction M₈ alone did not induce the reaction even in these conditions. The reaction was not induced by increase in either the Ca²⁺ concentration or the pH of sea water, but was markedly induced in the absence of jelly components by raising both the pH and Ca²⁺ concentration together. 2) The ionophore A23187 induced the acrosome reaction appreciably when present alone and fully in the presence of monensin or Fraction M₈. Monesin alone was ineffective. 3) The jelly or a combination of ARIS and Fraction M₈ caused abrupt Ca²⁺ -uptake by the sperm. The Ca-channel blockers verapamil and diltiazem inhibited the jelly-induced acrosome reaction.     

Maitotoxin, A Presumed Calcium Channel Activator, Induces the Acrosome Reaction in Mussel Spermatozoa

Maitotoxin, a presumed activator of the voltage-sensitive calcium channel, induced the acrosome reaction in the mussel, Mytilus edulis at physiological pH and in the starfish, Asterias amurensis at pH 9.5. The induction of acrosome reaction by maitotoxin depended upon external Ca²⁺ and was inhibited by two types of calcium channel blockers; verapamil and diltiazem. These results suggest that the activation of the voltage-sensitive calcium channel takes an important part in the initiation of acrosome reaction in Mytilus and other animals.