Purification and characterization of an angiotensin I‐converting enzyme inhibitory peptide derived from porcine troponin C

To search for a novel angiotensin I‐converting enzyme (ACE) inhibitory peptide, porcine skeletal troponin was hydrolyzed with pepsin. This hydrolysate showed ACE inhibitory activity, and was applied to various kinds of chromatography to separate an active peptide. Analysis using a protein sequencer identified this peptide as RMLGQTPTK (9mer). This sequence was estimated to occur at the 44–52 position of troponin C, and its 50% inhibitory protein concentration (IC₅₀) was 34 µM. RMLGQTP (7mer), a partial peptide of 9mer, showed activity with an IC₅₀ of 503 µM. RP‐HPLC analysis of a reaction mixture of 9mer and ACE showed that 9mer was slowly hydrolyzed by ACE. On the other hand, 7mer was rapidly hydrolyzed by ACE. Activity of 9mer was reduced as its hydrolysis by ACE proceeded. To estimate the resistance of 9mer to digestive proteases after oral administration, it was reacted with pepsin, α‐chymotrypsin, or trypsin. In each of these reaction mixtures, a significant amount of 9mer remained as a substrate after digestion. Remaining ACE inhibitory activity was close to that of 9mer. These results suggest that 9mer might not be digested after oral administration, because of its relatively high resistance to digestive proteases. Therefore, 9mer might be expected to work well in vivo as an ACE inhibitor.     

Predator–prey size relationship in siphon cropping between the juvenile stone flounder Platichthys bicoloratus and the bivalve Nuttallia olivacea

ABSTRACT:   The purpose of the present paper was to examine the size relationship between the juvenile stone flounder Platichthys bicoloratus and the bivalve Nuttallia olivacea , the siphon of which is important prey for the juvenile flounder. Juvenile stone flounder feed mainly on tips of the inhalant siphon of the bivalve. The maximum width of siphon tips in the stomach contents of age-0 fish could not reach that of age-1 fish, although the siphons in age-0 fish became larger as they grew. This size discrepancy indicated a limitation in the size of bivalves available to juveniles. The proportion of total cropping frequency for the siphon of the bivalve by juveniles was estimated according to the bivalve size class. Most bivalves that had cropped siphon tips ranged from 5 to 30 mm in shell length. The total cropping frequency per bivalve was particularly intense on bivalves of 10–25 mm shell length in spite of their small proportion of 24.9% of the total. This frequency intensity indicated that the size of bivalves with cropped siphons by juvenile stone flounder might depend on the ability of juveniles rather than the size composition of the bivalves.     

Factors affecting the growth of in vitro cultured lateral buds from Phalaenopsis flower stalks

Phalaenopsis flower-stalk buds cultured in vitro show 3 modes of growth: dormant, vegetative and reproductive. The effects of bud position on the stalk, temperature, and benzyladenine (BA) on the mode of bud growth were examined.Flower stalks were cut into 1-node sections, each with 1 bud, and inserted into solid culture medium, top side up. Buds on the upper sections had a tendency to remain dormant regardless of temperature. Sprouting buds placed at 20°C or 25°C showed reproductive growth except for some on the basal sections which grew vegetatively. At 28°C, all buds developed vegetatively independent of their original position on the stalk. The buds on the sections taken from both stalks which had elongated at min 18°C and min 28°C were subcultured; the mode of growth of the cultured buds was not affected by the temperature during flower-stalk elongation but was affected by the subsequent culture temperature.Cultured buds which had remained dormant were stimulated to sprout by addition of BA to the medium. At 5 p.p.m. and above, all buds began to develop, but malformations developed on the leaves of the shoots. All factors considered, BA at 2.5 p.p.m. was found to be the optimum level. The further development of the buds released from dormancy by BA was also affected by the position on the flower stalk and by cultural temperature.     

Foraging adaptation and the relationship between food-web complexity and stability

Ecological theory suggests that complex food webs should not persist because of their inherent instability. "Real" ecosystems often support a large number of interacting species. A mathematical model shows that fluctuating short-term selection on trophic links, arising from a consumer's adaptive food choice, is a key to the long-term stability of complex communities. Without adaptive foragers, food-web complexity destabilizes community composition; whereas in their presence, complexity may enhance community persistence through facilitation of dynamical food-web reconstruction that buffers environmental fluctuations. The model predicts a linkage pattern consistent with field observations.     

Photoinduced oxidation of the insecticide phenothrin on soil surfaces

Photodegradation profiles of the pyrethroid insecticide phenothrin on a moistened U.S. soil thin layer was investigated by using its predominant component, the 1R-trans-isomer (I), under continuous exposure to light at >290 nm from a xenon arc lamp. Its degradation was moderately accelerated by irradiation with half-lives of 5.7-5.9 days (dark control 21-24 days), mainly via successive oxidation of the 2-methylprop-1-enyl group and ester cleavage followed by mineralization to carbon dioxide. Spectroscopic and cochromatographic analyses showed that the major degradates were the alcohol and ketone derivatives of I formed via photoinduced oxidation of the 2-methylprop-1-enyl group by singlet oxygen. The photoinduced generation of singlet oxygen in/on the soil surface was confirmed by using chemical trapping reactions together with ESR spectroscopy.     

Age validation,growth and annual reproductive cycle of chub mackerel <Emphasis Type="Italic">Scomber japonicus</Emphasis> off the waters of northern Kyushu and in the East China Sea

The age and growth of chub mackerel Scomber japonicus collected from the East China Sea and the northern waters off Kyushu between June 2000 and June 2001 were determined by observing the otolith surface after dipping it in xylene. The translucent and opaque zones on the otolith surface were identified, and the number of translucent zones was counted. Monthly changes in the frequency of fish with translucent zones on the otolith margin, and in the marginal increments, indicated that the translucent zones were formed between April and June. The seasonal pattern of annulus formation on the otolith became clear by observing the otoliths of fish with known ages, and the otolith formation in wild fish was consistent with that of fish with known ages. The mean gonadosomatic index of male and female fish was high from March to May, and spawning females were observed from mid-March to mid-May. The estimated ages were 1–5 years for males and 1–6 years for females. The von Bertalanffy growth parameters did not significantly differ between male and female. The model was obtained as FL _t=406×{1−exp[−0.372×(t+1.68)]     

Migration pattern of shirauo Salangichthys microdon Bleeker, in the Ishikari River system and adjacent nearshore sea area, Japan, as estimated by otolith microchemistry analysis

ABSTRACT:   The purpose of the present paper was to reveal the migration pattern of shirauo Salangichthys microdon Bleeker, in the Ishikari River system and its adjacent coastal sea areas. To this end, the strontium–calcium (Sr:Ca) ratios of the otoliths of 98 individuals were examined. Profiles of the Sr:Ca ratios during the life history after hatching in the estuary of the Ishikari River fell into two different patterns. One was characterized by a high (slightly fluctuating) Sr:Ca ratio throughout the life history; the other was characterized by an initial high Sr:Ca ratio followed by a lower value later in life. The former pattern was considered to be that of estuary–sea residents and the latter that of upstream migrants. Most upstream migrants migrated upstream once, although several did it twice. Back-calculated body lengths during the upstream and seaward migrations of the upstream migrants varied widely from 6.4 mm to 39.8 mm and from 13.5 mm to 79.4 mm, respectively. These findings suggest that estuary–sea residents and upstream migrants co-occurred spatiotemporally, and suggest a wide variation in migration patterns in the shirauo's life history.     

Natural Abundance 14C Content of Dibutyl Phthalate (DBP) from Three Marine Algae

Analysis of the natural abundance ¹⁴C content of dibutyl phthalate (DBP) from two edible brown algae, Undaria pinnatifida and Laminaria japonica, and a green alga, Ulva sp., revealed that the DBP was naturally produced. The natural abundance ¹⁴C content of di-(2-ethylhexyl) phthalate (DEHP) obtained from the same algae was about 50–80% of the standard sample and the ¹⁴C content of the petrochemical (industrial) products of DBP and DEHP were below the detection limit.     

Is It Possible to Use 90Sr and 137Cs As Tracers for the Aeolian Dust Transport?

A noble approach for the estimation of the deposition of the Asian dust over Japan by using atmospheric anthropogenic radioactivity, ⁹⁰Sr and ¹³⁷Cs, is proposed. Those radioactivities once deposited globally onto the ground by the past nuclear test, etc. are resuspended along with the surface soil particles in the air by the storm and deposited again on the ground. The difference in ¹³⁷Cs/⁹⁰Sr activity ratios in the surface soil between dry and wet climatic conditions gives a clue to know about the source of the dust. It was found that the average activity ratio in the deposited material (average: 2.1, n=82) at MRI, Tsukuba in the 1990s is not close to that of the surface soil taken in neighborhood (median: 6.8, n=8), which had been considered as the primary source. While, it is close to that of the soil samples taken in the arid area in the Asian continent (median: 2.0, n=4), which is the one of the source regions of the aeolian dust. Thus we can reasonably assume that deposited dust in Tsukuba is brought not only from the neighboring fields, etc. but also from the arid area in the continent. Using a simple two-component model it was estimated that the Asian dust may transport about 90% of ⁹⁰Sr and 70% of ¹³⁷Cs depositions observed in Tsukuba in the 1990s. Also, Asian dust may transport about 2/3 of the dust deposited in Tsukuba.     

Isolation of Araguspongine M,a New Stereoisomer of an Araguspongine/Xestospongin alkaloid,and Dopamine from the Marine Sponge Neopetrosia exigua Collected in Palau

A new stereoisomer of an araguspongine/xestospongin alkaloid, named araguspongine M (1), has been isolated together with 12 known compounds, araguspongines B (2) and D (3), dopamine, three galactosyl diacylglycerols, 24-methyl cholesterol, 5,6-dihydrocholesterol, β-sitosterol, and three 5α,8α-epidioxy sterols (11–13), from the marine sponge Neopetrosia exigua (formerly Xestospongia exigua) collected in Palau. The structure of 1 was assigned on the basis of its spectral data analysis. This is the first report on the isolation of dopamine from a marine sponge. This compound may be produced by an endosymbiotic Synechococcus-like cyanobacterium. Compounds 1–3 and 11–13 showed cytotoxicity against HL-60 at IC₅₀’s of 5.5, 5.5, 5.9, 22.4, 9.5, and 9.6 μM, respectively. The possible biosynthesis origin of the isolated metabolites is discussed.