Effect of catechins on mutagenesis of Salmonella typhimurium TA 102 elicited by tert-butyl hydroperoxide (t-BuOOH)

Green tea, one of the most popular beverages consumed in Asian countries, has been reported to possess anticarcinogenic and antimutagenic properties. The aim in this study is to test the radical scavenging effect of catechins and caffeine, which were major components of green tea, and if they really prevent oxygen radical-induced mutagenesis. We used TA102 strain of Salmonella typhimurium which is sensitive to hydroxyl radical in the Ames mutation assay. We found that caffeine did not show any effects on mutagenesis in this system, but catechin significantly reduced mutagenesis or genotoxicity caused by hydroxyl radical. This radical-scavenging action of catechins may indeed contribute to the anticarcinogenic activity of green tea as has been proposed.     

Effects of twice harvesting on total dry matter yield of rice

We examined the effect of twice harvesting of forage rice with the first harvest at the full heading stage on total dry matter yield in the cultivars Taporuri, Mohretsu, and Hinohikari and in line Saikaishi 253 in southwestern Japan. Taporuri produced the highest total dry matter yield, with a value 60% higher than that of Hinohikari. The first crop of Taporuri had a longer duration of vegetative growth than those of Mohretsu and Hinohikari, and had the highest dry matter yield because of its greater weight per tiller than Hinohikari and its more tillers per square meter than Saikaishi 253, which had a similar duration of vegetative growth. The second crops of Mohretsu, Taporuri, and Saikaishi 253 had longer vegetative growth and higher dry matter yields than Hinohikari. Dry matter yields of both crops were closely related to the duration of vegetative growth and the weight per tiller, but not to tillers per square meter. These results suggest that cultivars with a long duration of vegetative growth, high weight per tiller, and adequate tillers per square meter can produce high dry matter yield in both crops. There was a significant interaction (P < 0.05) in total dry matter yield between cultivar or line and cultivation type. The total dry matter yield of Taporuri in twice harvesting was about 10% higher than that in once harvesting, whereas that of Hinohikari was about 10% lower. The suitability for twice harvesting ([total dry matter yield in twice harvesting]/[total dry matter yield in once harvesting]) was significantly positively correlated (r = 0.875) with the increase in dry weight before the full heading stage, but significantly negatively correlated (r = −0.903) with the increase in dry weight between full heading and the yellow ripe stage. Thus, cultivars with a high increase in dry weight before full heading appear to be more suitable for twice harvesting than those with a high increase between full heading and the yellow ripe stage. In addition, our study showed that twice harvesting can prevent lodging in Taporuri, thereby increasing the suitability of this cultivar as a forage rice. Our results suggest that twice harvesting can be performed in southwestern Japan and warmer regions.     

Caprine somatic cell nuclear transfer using in vivo matured oocytes collected by laparoscopic follicular aspiration

In vivo matured oocytes collected by laparoscopic follicular aspiration (LFA) from hormone treated female goats were used as recipient ooplasts for somatic cell nuclear transfer (SCNT). Japanese native (Shiba) goats were used as donor females and some donor females were used repeatedly (two or three times) at intervals of a few months. To induce synchronization of estrus, a sponge containing 0.5 g of progesterone was inserted into the vagina of each goat for 14 days. These animals were also treated with follicle stimulating hormone (FSH) in a series of 8 injections over 4 days. The first FSH injection was administered on the morning of day 9 of sponge insertion. On the morning of day 13, 50 µg of gonadotropin‐releasing hormone (GnRH) was injected into each animal. Twenty‐nine hours after GnRH injection, LFA was performed. After removal of cumulus cells, collected oocytes with the first polar body were selected and enucleated for nuclear transfer. Anterior pituitary cells isolated from an adult male Shiba goat were transfected with a DNA fragment containing the enhanced green flourescent protein gene and the puromycin resistance gene. A single donor cell was inserted into the perivitelline space of each enucleated oocyte and fusion was induced with one electric pulse of 20 V for 10 µs. The SCNT goat eggs were cultured in chemically defined medium at 38.5°C in 5% CO₂, 5% O₂, 90% N₂ for 9 days. By LFA, 396 oocytes were collected from a total of 30 females. After removal of cumulus cells, 64% of them extruded the first polar body. The percentage of SCNT goat eggs produced using in vivo matured oocytes which developed to the blastocyst stage (20–21%) was significantly higher (P < 0.05) than that produced with in vitro matured oocytes (3–8%).     

Effects of a severe typhoon on forest dynamics in a warm-temperate evergreen broad-leaved forest in southwestern Japan

The effects of a typhoon on forest dynamics and the response of major tree species were studied in a warm-temperate evergreen broad-leaved forest in southwestern Japan. The strongest typhoon on record (T9313) passed through this region in 1993. Return periods of typhoons over 30 ms⁻¹ in instantaneous wind velocity and T9313 were estimated to be 2.2 and 104.5 years, respectively. Approximately 10% of all stems suffered some damage from T9313 and annual stem mortality rose from 1.3 to 2.7%. The estimated period that the number of stems would fall below 10% of the initial was four years shorter with T9313-class typhoons than without them. Thus, the disturbance by T9313 was not catastrophic at the site although T9313 was an episodic typhoon. The short-term responses of major tree species to T9313 were classified into four types: 1) blunt-response type with little decrease and recruitment of stems in the DBH ≥ 5 cm class (Distylium racemosum), 2) retreat type with larger decrease than recruitment (e.g. Quercus acuta), 3) sharp-response type with a large decrease and much recruitment (e.g. Cinnamomum japonicum), and 4) advance type with less decrease than recruitment (Eurya japonica). Among the four regeneration types classified by previous studies (climax, light-demanding, subcanopy, and few-sapling), the climax and few-sapling types each showed a specific short-term response, the blunt-response and retreat types, respectively, that explains one aspect of the regeneration strategies of each type. On the other hand, the light-demanding or sub-canopy type showed multiple short-term responses, indicating that each regeneration type contains species with various regeneration strategies. In this paper, I analyzed data from the database that was compiled by the Aya Research Team.     

Effects of heat treatment on brittleness of <Emphasis Type="Italic">Styrax tonkinensis</Emphasis> wood

A new approach is proposed for the evaluation of the brittleness of heat-treated Styrax tonkinensis wood. Heat treatment made wood more brittle when wood was heated at a higher temperature or for a longer time. The brittleness increased to four times that of the control when wood was heated at 200°C for 12 h. For treatment at 160°C, the increase in brittleness without any change in weight is thought to be possibly caused by the relocation of lignin molecules. At higher temperatures, loss of amorphous polysaccharides due to degradation is thought to become the main factor affecting brittleness. The crystallites that were newly formed after 2 h of treatment showed brittleness that was different from that of the inherent crystallites remaining after 12 h of heat treatment. This inherent crystalline cellulose possibly plays a role in brittleness. There is also the possibility of using color to predict the brittleness of heat-treated wood.     

Comparative functional anatomy of hindlimb muscles and bones with reference to aquatic adaptation of the sea otter

Although the sea otter (Enhydra lutris) is a complete aquatic species, spending its entire life in the ocean, it has been considered morphologically to be a semi-aquatic animal. This study aimed to clarify the unique hindlimb morphology and functional adaptations of E. lutris in comparison to other Mustelidae species. We compared muscle mass and bone measurements of five Mustelidae species: the sea otter, Eurasian river otter (Lutra lutra), American mink (Neovison vison), Japanese weasel (Mustela itatsi) and Siberian weasel (M. sibirica). In comparison with the other 4 species, E. lutris possessed significantly larger gluteus, popliteus and peroneus muscles, but smaller adductor and ischiopubic muscles. The popliteus muscle may act as a medial rotator of the crus, and the peroneus muscle may act as an abductor of the fifth toe and/or the pronator of the foot. The bundles of the gluteus superficialis muscle of E. lutris were fused with those of the tensor fasciae latae muscle and gluteofemoralis muscles, and they may play a role in femur abduction. These results suggest that E. lutris uses the abducted femur, medially rotated crus, eversion of the ankle and abducted fifth digit or extended interdigital web as a powerful propulsion generator. Therefore, we conclude that E. lutris is a complete aquatic animal, possessing differences in the proportions of the hindlimb muscles compared with those in other semi-aquatic and terrestrial mustelids.