Interspecific differences in the post-settlement survival of <Emphasis Type="Italic">Acropora</Emphasis> corals under a common garden experiment

Extremely low post-settlement survival is one of the largest barriers for artificial rehabilitation of Acropora corals. However, little data have been found for interspecific difference of the post-settlement survival probably because the observation of coral juvenile is difficult in the field. Here, we analyzed the survival of three dominant species of Acropora corals (A. digitifera, A. tenuis, A. yongei), with different colony morphologies and habitat preferences, for 2 years after settlement under the same environmental conditions. The post-settlement survival was significantly higher for A. tenuis than for A. digitifera 3 months after settlement. Two years later, the survival rate of A. tenuis was approximately 15 times higher than A. digitifera. In a separate analysis of three bottle-brush species (A. awi, A. echinata, A. subglabra) and A. tenuis, post-settlement survival was always higher for A. awi than for other two bottle-brush species, suggesting that the initial survival was different among morphologically sister species. Low survival was possibly associated with slow growth rates during the first 7 months. Thus, species selection is important for successful artificial coral rehabilitation, with A. tenuis being the most viable option. Alternatively, new techniques are required to improve post-settlement survival of slow growing coral species.     

Survey of the response of 82 domestic landraces of Zea mays to cucumber mosaic virus (CMV) reveals geographical region‐related resistance to CMV in Japan

Zea mays has been historically imported to Japan via two independent geographical routes: into southern Japan by trading with Europe in the 16th century and into northern Japan by import from North America in the 19th century. Breeding to genetically improve on quality traits and high yields has led to the current domestic landraces in each region. In a survey of 82 domestic landraces, nine out of 38 landraces originating from southern Japan showed complete immunity to cucumber mosaic virus yellow strain (CMV(Y)) without the formation of necrotic local lesions (NLLs). In contrast, three out of 44 landraces originating from northern Japan developed NLLs, but revealed no systemic spread of the virus. Due to the absence of good documentation on NLL formation in Z. mays, the response of domestic landraces Aso‐1 and Aso‐3, originating from Ibaraki in northern Japan, to a challenge with CMV(Y) and CMV(Ma‐1) was further analysed. Aso‐3 only formed NLL in response to CMV(Y) but not to CMV(Ma‐1). Moreover, in CMV(Y)‐inoculated Aso‐3, virus spread was restricted to the primary infection site and the expression of defence‐related genes was up‐regulated, whereas Aso‐1 became systemically infected with either CMV(Y) or CMV(Ma‐1). The response of Aso‐3 to CMV(Y) was inherited as a single dominant trait. Together, these results pointed towards the induction of hypersensitive response (HR)‐mediated resistance to CMV(Y) in Aso‐3. Although HR‐mediated resistance to viruses has been studied mainly in dicots, the pathosystem CMV–Z. mays may provide a model to investigate HR‐mediated resistance to viruses in monocot plants.     

Structure-Activity Relationship Study of the Neuritogenic Potential of the Glycan of Starfish Ganglioside LLG-3

LLG-3 is a ganglioside isolated from the starfish Linchia laevigata. To clarify the structure-activity relationship of the glycan of LLG-3 toward rat pheochromocytoma PC12 cells in the presence of nerve growth factor, a series of mono- to tetrasaccharide glycan derivatives were chemically synthesized and evaluated in vitro. The methyl group at C8 of the terminal sialic acid residue was crucial for neuritogenic activity, and the terminal trisaccharide moiety was the minimum active motif. Furthermore, the trisaccharide also stimulated neuritogenesis in human neuroblastoma SH-SY5Y cells via mitogen-activated protein kinase (MAPK) signaling. Phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 was rapidly induced by adding 1 or 10 nM of the trisaccharide. The ratio of phosphorylated ERK to ERK reached a maximum 5 min after stimulation, and then decreased gradually. However, the trisaccharide did not induce significant Akt phosphorylation. These effects were abolished by pretreatment with the MAPK inhibitor U0126, which inhibits enzymes MEK1 and MEK2. In addition, U0126 inhibited the phosphorylation of ERK 1/2 in response to the trisaccharide dose-dependently. Therefore, we concluded that the trisaccharide promotes neurite extension in SH-SY5Y cells via MAPK/ERK signaling, not Akt signaling.     

Effects of Brief Summer or Winter Fasting on the Muscle Quality of Cultured Pacific Bluefin Tuna (Thunnus orientalis)

The effects of fasting on the quality of the dorsal and ventral ordinary muscles from cultured Pacific bluefin tuna (Thunnus orientalis) during chilled storage were investigated. Tuna were subjected to fasting for 2 days in the summer or 6 days in the winter prior to harvesting. The breaking strength of the dorsal ordinary muscle sampled in the summer increased until 24 h and then decreased. There were no significant differences in the lipid and glycogen content of the ordinary muscle after 9 h of storage between the controls and either fasting group. The pH of the ordinary muscle subjected to summer and winter fasting was higher than in the controls after 24–48 h of storage. However, the relationship between the pH and glycogen content was unclear. The metmyoglobin content during chilled storage was lower in the ordinary muscles from either fasting group than in the controls. In conclusion, fasting for 6 days in the winter improved the color stability of the ordinary muscle without a decline in its lipid content.     

Application of supercooling to long-term storage of fish meat

Fish meat was brought to a supercooled state through slow cooling, and changes in the texture, histology, and protein composition of the meat were investigated. The groups whose storage temperature were lowered by 1.0°C per day (the 1.0°C group) and 0.5°C per day (the 0.5°C group) began to freeze in the vicinity of −3.5 and −5.0°C, respectively. The freezing point depended on the fish species; the lowest freezing point was −8.5°C, for the red sea bream in the 1.0°C group. The breaking strength tended to decrease more slowly in the 1.0°C group, but the collagen fibers collapsed more rapidly in the 1.0°C group. In SDS electrophoresis, a slight change in the banding patterns was observed, but the relationship between this observation and changes in histology and physical properties was unclear. This study shows that it is possible to produce a supercooled state in fish meat, and demonstrates that supercooling is a potential new storage method that lowers the temperature without generating ice crystals.     

Time dependence of Poisson’s effect in wood II: volume change during uniaxial tensile creep

To determine the viscoelasticity of wood three-dimensionally, a longitudinal tensile creep test was conducted on 12 species of wood to examine the change in the rate of volume increase (ΔV/V) with time. Immediately after the beginning of creep, ΔV/V was positive, and during creep, ΔV/V decreased rapidly, then more gradually. The decrease in tangential strain was considered to mainly contribute to the decrease in ΔV/V during creep. Immediately after the removal of the load, ΔV/V decreased to a negative value; thereafter, it decreased slowly and finally reached a certain value. The value of ΔV/V during creep tended to decrease with increasing density of wood. Also, there was a negative correlation between wood density and the rate of increase in ΔV/V.     

A 90-day Feeding Toxicity Study of l-Serine in Male and Female Fischer 344 Rats

A subchronic feeding study of l-serine (l-Ser) was conducted with groups of 10 male and 10 female Fischer 344 rats fed a powder diet containing 0, 0.06, 0.5, 1.5 or 5.0% concentrations of l-Ser for 90 days. There were no toxicologically significant, treatment-related changes with regards to body weight, food intake, water intake or urinalysis data. In several of the hematology, serum biochemistry and organ weight parameters, significant changes were observed between some of the treated groups and the controls. All these changes, however, were subtle and lacked any corresponding pathological findings. In addition, the increased or decreased values remained within the range of the historical control values. In fact, histopathological assessment revealed only sporadic and/or spontaneous lesions. In conclusion, the no-observed-adverse-effect-level (NOAEL) for l-Ser was, therefore, determined to be at least a dietary dose of 5.0% (2765.0 mg/kg body weight/day for males and 2905.1 mg/kg body weight/day for females) under the present experimental conditions.     

Collaborative non-self recognition system in S-RNase-based self-incompatibility

Self-incompatibility in flowering plants prevents inbreeding and promotes outcrossing to generate genetic diversity. In Solanaceae, a multiallelic gene, S-locus F-box (SLF), was previously shown to encode the pollen determinant in self-incompatibility. It was postulated that an SLF allelic product specifically detoxifies its non-self S-ribonucleases (S-RNases), allelic products of the pistil determinant, inside pollen tubes via the ubiquitin-26S-proteasome system, thereby allowing compatible pollinations. However, it remained puzzling how SLF, with much lower allelic sequence diversity than S-RNase, might have the capacity to recognize a large repertoire of non-self S-RNases. We used in vivo functional assays and protein interaction assays to show that in Petunia, at least three types of divergent SLF proteins function as the pollen determinant, each recognizing a subset of non-self S-RNases. Our findings reveal a collaborative non-self recognition system in plants.     

Modified plant architecture to enhance crop disease control: genetic control and possible value of upright fruit position in cucumber

Plant architectural features can facilitate disease control by creating unfavourable environments for pathogen growth or limiting pathogen contact with the host. In the case of Phytophthora capsici infection of cucumber (Cucumis sativus), the susceptible fruit typically lie in contact with soil under warm, moist conditions of a full canopy, an ideal location for exposure to inoculum and disease development. We have shown that increased row spacing, trellising and architectural variants that allow for more open canopies, such as shorter vines, reduced branching, or smaller leaves, can modify microclimate as assessed by temperature at the location of developing fruits. However, only trellising reduced infection rates (<3 % infection vs. 22 % for control). A cucumber accession PI308916, with extremely short internodes and resulting upright position of young fruit, also exhibited reduced disease. Fruit of PI308916 were susceptible when inoculated with P. capsici, indicating that reduced infection likely resulted from decreased soil contact. The compact trait is inherited as a single recessive gene, cp. Like many architectural traits, cp may be pleiotropic; PI308916-derived breeding lines were reported to have poor seedling emergence. PI308916 exhibited inconsistent apical hook formation that co-segregated with short internodes in F₂ and backcross generations, and disorganized internodal cortical cell arrangement. The combined phenotypes suggest either pleiotropy or very tight linkage of genes affecting hormone balance or cell division. The narrow chromosome region recently defined by QTL analysis includes candidate gene homologs of meristem related genes modulating cell division or spacing of lateral shoot organs and genes associated with brassinosteroid signaling or cytokinin content.     

Nutrient availability and response of sago palm (Metroxylon sago Rottb.) to controlled release N fertilizer on coastal lowland peat in the tropics

Sago palms (Metroxylon sagu Rottb.) growing on peat soils were found to grow more slowly and to show a lower production than palms growing on mineral soils. This difference was related to the physical and chemical constraints of peat soils, which include low bulk density, high acidity, and low N, P, K, Ca, Zn, and Cu levels. In coastal lowland peat soils, the distance from the sea has been found to be an important determinant of soil elemental composition. We predicted that a sufficient supply of N at the rosette stage would improve sago palm growth and that the availability of N in soil to which controlled release N fertilizer was applied might be higher than that in soil treated with soluble fertilizer. To investigate the changes in the nutrient composition of peat soils at various distances from the sea and the effect on sago palm growth, we studied sago palm areas in Indonesia and Malaysia. To observe the influence of N on the growth performance, we also conducted a fertilizer experiment on coastal lowland peat soil in Indonesia. Distance from the sea had no significant effect on the cation concentration in the soil solution (with the exception of Mg) or on the levels of soil-exchangeable cations. No significant differences were observed between the concentrations of exchangeable cations in surface peat soils and those in mature leaves. However, the concentrations of K, Na, and Ca in mature leaves increased significantly with their concentrations in the soil solution. This finding implies that the concentrations of cations in sago palm leaves depend directly on the concentrations of cations in the soil solution. No significant effect of N fertilizers on plant height and leaf formation was observed. N fertilizers applied twice a year did not affect appreciably the foliar concentration of N determined in December 1998 (5 months after the initial application) and December 1999. In June 2000, we detected a significantly higher concentration of N (p < 0.01) in young leaves of the palms treated with LP-100 or urea than in control leaves. However, no significant difference was detected between the LP-100 and urea treatments in the concentration of N in both mature and young leaves. This finding indicated that the concentration of N in sago palm leaves increased with the level of soil-applied N, regardless of whether N was applied as controlled release fertilizer or in the soluble form. We anticipate that a significant difference in the effects of these N fertilizers may occur during the next rainy season, when there should be a considerable loss of soluble N.