Studies on the functional site on staphylococcal enterotoxin A responsible for production of murine gamma interferon

To identify the functional region(s) associated with induction of gamma interferon on the staphylococcal enterotoxin A molecule, native staphylococcal enterotoxin A molecules and 12 various synthetic peptides corresponding to different regions of entire staphylococcal enterotoxin A were compared to induce gamma interferon production in murine spleen cells. The native staphylococcal enterotoxin A molecule induced gamma interferon production, whereas all of the 12 synthetic peptides did not. Pre-treatment of the murine spleen cells with synthetic peptide A-9 (corresponding to amino acid residues 161-180) significantly inhibited the staphylococcal enterotoxin A-induced gamma interferon production, whereas those with other synthetic peptides did not. When native staphylococcal enterotoxin A was pre-treated with either anti-staphylococcal enterotoxin A serum or anti-peptide sera, anti-staphylococcal enterotoxin A serum and antisera to peptides A-1 (1-20), A-7 (121-140), A-8 (141-160), A-9 (161-180) and A-10 (181-200) inhibited the staphylococcal enterotoxin A-induced gamma interferon production. From these findings, the amino acid residues 161-180 on the staphylococcal enterotoxin A molecule may be an essential region for murine gamma interferon production. Furthermore, the neutralizing epitopes may be also located on regions of amino acid residues 1-20, 121-140, 141-160 and 181-200 on the staphylococcal enterotoxin A molecule.     

Two Modes of Regulation of the Fatty Acid Elongase ELOVL6 by the 3-Ketoacyl-CoA Reductase KAR in the Fatty Acid Elongation Cycle

Fatty acids (FAs) are diverse molecules, and such diversity is important for lipids to exert their functions under several environmental conditions. FA elongation occurs at the endoplasmic reticulum and produces a variety of FA species; the FA elongation cycle consists of four distinct enzyme reactions. For this cycle to be driven efficiently, there must exist coordinated regulation of protein components of the FA elongation machinery. However, such regulation is poorly understood. In the present study, we performed biochemical analyses using the FA elongase ELOVL6 and the 3-ketoacyl-CoA reductase KAR, which catalyze the first and second steps of the FA elongation cycle, respectively. In vitro FA elongation assays using membrane fractions demonstrated that ELOVL6 activity was enhanced ∼10-fold in the presence of NADPH, although ELOVL6 itself did not require NADPH for its catalysis. On the other hand, KAR does use NADPH as a reductant in its enzyme reaction. Activity of purified ELOVL6 was enhanced by ∼3-fold in the presence of KAR. This effect was KAR enzyme activity-independent, since it was observed in the absence of NADPH and in the KAR mutant. However, ELOVL6 enzyme activity was further enhanced in a KAR enzyme activity-dependent manner. Therefore, KAR regulates ELOVL6 via two modes. In the first mode, KAR may induce conformational changes in ELOVL6 to become structure that can undergo catalysis. In the second mode, conversion of 3-ketoacyl-CoA to 3-hydroxyacyl-CoA by KAR may facilitate release of the product from the presumed ELOVL6–KAR complex.     

Studies on Changes in Stored Shell Eggs

The content of the ovomucin gel obtained from the gel parts of stored thick white decreased during storage. Changes of the content of the ovomucin gel (A) was much larger than that of the ovomucin gel (B). The content of the ovomucin sol obtained from the sol parts of stored thick white increased during storage.

The hexose and hexosamine contents of the ovomucin gel (B) decreased to about one half and the sialic acid content decreased to one eighth after 20 days storage at 30°C On the other hand, the carbonhydrate contents of the ovomucin sol (B) increased during storage and those obtained from sol parts of the stored (20 days) thick white were higher than those of the control ovomucin gel (B) obtained from the newly laid thick white. The amino acid composition of the ovomucin gel (B) and sol (B) did not show a great deal of change during storage.

It is suggested from these results that the properties of the ovomucin gel (B) changed greatly during storage; one portion of the ovomucin gel (B), the carbohydrate-rich component, solubilized to the sol parts of stored thick white and the other portion, the carbohydrate-poor component, remained insoluble.     

Cytological and molecular analysis of centromere misdivision in maize.

B chromosome derivatives suffering from breaks within their centromere were examined cytologically and molecularly. We showed by high resolution FISH that misdivision of the centromere of a univalent chromosome can occur during meiosis. The breaks divide the centromere repeat sequence cluster. A telocentric chromosome formed by misdivision was found to have the addition of telomeric repeats to the broken centromere. A ring chromosome formed after misdivision occurred by fusion of the broken centromere to the telomere. Pulsed-field electrophoresis analyses were performed on the telocentric and ring chromosomes to identify fragments that hybridize to both the telomeric repeat and the B-specific centromeric repeat. We conclude that healing of broken maize centromeres can be achieved through the mechanisms of addition or fusion of telomeric repeat sequences to the broken centromere.     

Inhibition of larval recruitment of ARmandia sp. (Polychaeta: Opheliidae) by established adults of Pseudopolydora paucibranchiata (Okuda) (Polychaeta : Spionidae) on an intertidal sand flat

Inhibition of larval settlement by a dense assemblage of established adults was examined by observing natural and experimental abundance patterns of two polychaete species on an intertidal sand flat in west Kyushu, Japan. A cage left for 43 days in the field in spring-summer brought about a remarkable increase in the within-cage density of adults of the tube-building spionid polychaete Pseudopolydorapaucibranchiata (Okuda) as compared with the density in an uncaged plot (× 52). In contrast, the densities of juveniles of the burrowing opheliid polychaete Armandia sp. showed an inverse trend (× $\text{1}\text{22}$). The attractiveness of the within-cage sediment for settling larvae of Armandia (cage-induced artifact) was assessed in a laboratory experiment: given an alternative choice between the sediments from the cage and the uncaged plot, Armandia larvae produced by artificial fertilization showed no substratum-preference. In another laboratory experiment, it was confirmed that Pseudopolydora paucibranchiata adults at a density of only $\text{1}\text{30}$ of that in the cage exerted a great lethal effect (probably ingestion) on Armandia larvae. These two results strongly support the hypothesis that the low density of Armandia juveniles in the cage was induced not through avoidance of the cage sediment by the larvae themselves but through inhibition of recruitment by the dense assemblage of established Pseudopolydora paucibranchiata adults in the cage. Moreover, the natural abundance pattern of Armandia juveniles in summer could partly be explained in relation to spatial and temporal changes in the density of Pseudopolydora paucibranchiata adults.