Vertical distributions of Japanese sardine (Sardinops melanostictus) eggs: comparison of observations and a wind-forced Lagrangian mixing model

To understand how Japanese sardine eggs vertically disperse in water, we acquired a series of depth‐resolved samples of eggs while tracking a drogued buoy to follow the water mass in which the eggs were spawned. This survey was conducted in early March of 1991, when the sardine population was abundant and actively spawning in the Pacific off Kyushu. Buoyancy of the eggs was estimated by measuring the specific gravity, and was 1–4 × 10^?3 less than that of the water in which they were spawned, giving a rising speed of 1–2 mm s^?1. In an attempt to diagnose the dynamics underlying the observed vertical profiles of the eggs, a one‐dimensional egg distribution model incorporating the egg rising speed and wind‐ and depth‐dependent vertical diffusivity was formulated. Observed eggs were mainly in the surface mixed layer, and their vertical distribution changed with wind‐induced surface mixing: during strong winds, the eggs were distributed relatively evenly over the upper 60–75 m, whereas during weak winds and shallow pycnocline, the eggs formed a subsurface peak around 25 m depth. The model accurately reproduced these variations in the vertical distributions of eggs, suggesting that the gradients of egg concentration are sensitive to the strength of wind and the structure of underlying hydrography. Further tests with the model showed the importance of positive buoyancy: neutrally buoyant eggs formed subsurface maxima below the food‐rich euphotic zone. The balance of vertical mixing and floating, which allows the eggs to remain in the euphotic zone but away from the near‐surface waters, may be an adaptation to minimize surface‐enhanced predation, while allowing the eggs to hatch in the food‐rich euphotic zone.     

CO2施用对大花蕙兰试管苗生长和叶片气孔特征的影响

采用培养箱内增加CO2浓度的方法,在塑膜·岩棉(CP·RW)培养方式下对大花蕙兰(Cymbidium)试管苗进行培养.结果表明,在CO2施用条件下的大花蕙兰试管苗,其形态指标、叶绿素指数和叶片气孔密度均高于无CO2施用处理.采用SSR法进行比较(显著水平P≤0.05),其中在株高、叶长、叶幅、根数、最长根长、鲜重、干物重和气孔密度等重要指标之间存在显著性差异.     

Is there a relationship between the intrinsic rate of propagation and <Emphasis Type="Italic">in-vitro</Emphasis> migration and virulence of the pinewood nematode, <Emphasis Type="Italic">Bursaphelenchus xylophilus</Emphasis>?

We investigated if rates of propagation and migration were related with the level of virulence in the pinewood nematode Bursaphelenchus xylophilus using 17 offspring lines from the F₂ crosses between virulent and avirulent isolates. Virulence was tested by inoculating seedlings of Pinus thunbergii with the nematodes. The proportion of dead seedlings ranged from 13.3% to 77.8%, 20 weeks after inoculation. Migration rate of the nematodes was estimated by measuring their migration distance per unit time in an artificial substrate that imitated pathways in pine trees. Migration rate varied from 0.85 to 3.53 mm min⁻¹. Propagation rate was determined based on population growth on the fungus Botrytis cinerea, and it ranged between 10^3.88 and 10^4.99 per 12 days. Statistical analyses revealed that virulence was not correlated with migration rate, but was negatively correlated with propagation rate on Botrytis cinerea, suggesting that the nematodes paid some cost for virulence. Also, there was no relationship between rates of migration and propagation. Cluster analysis showed that the biological parameters varied between crossbred lines, with no kinship bias, suggesting the absence of sex-linked inheritance in virulence and rates of propagation and migration.     

Evaluation of novel sulfonylurea derivatives with a fused heterocyclic moiety as paddy herbicides that control sulfonylurea‐resistant weeds

Herbicidal activity and acetolactate synthase (ALS) inhibition of sulfonylurea derivatives with a fused heterocyclic moiety bonded to a sulfonyl group were investigated. Some compounds that had an imidazo[1,2‐b]pyridazine moiety substituted at the 2‐position by chlorine or methyl controlled sulfonylurea‐resistant (SU‐R) weeds and showed inhibitory activity to ALS prepared from SU‐R Schoenoplectus juncoides shoot. There was a correlation between in vitro and whole‐plant herbicidal activity of the compounds mentioned above against SU‐R Schoenoplectus juncoides. Among them 1‐(2‐chloro‐6‐propylimidazo[1,2‐b]pyridazin‐3‐ylsulfonyl)‐3‐(4,6‐dimethoxypyrimidin‐2‐yl)urea, propyrisulfuron, was selected for further evaluation. Propyrisulfuron effectively controlled paddy weeds at doses of 70 and 140 g a.i. ha^?1 with good rice selectivity in a field trial.     

Comparison of digestibility, passage rate and rumen fermentation between sika deer (Cervus nippon) and cattle fed alfalfa hay cubes

Five female sika deer and three male Holstein cattle were offered alfalfa hay cubes at 2% (deer) and 2.5% (cattle) of bodyweight, respectively. The passage rate through the digestive tract, digestibility and rumen fermentation of the animals were determined. The rate of ruminal passage was higher and the total mean retention time in the digestive tract was shorter in deer than in cattle. In addition, the rate of post‐ruminal passage in deer was lower. The digestibilities of dry matter, organic matter, crude protein and fiber in deer were significantly lower than in cattle (P < 0.05). The concentration of total volatile fatty acids in the rumen was significantly higher in deer than in cattle. The molar percentage of acetic acid was lower and that of valeric acid was higher in deer (P < 0.05). The number of protozoa was somewhat higher in deer. These results suggested that the lower digestibility in deer might be a result of the shorter retention time in the digestive tract.     

Effects of slag silicate fertilizer on silicon content of rice plants grown in paddy fields on the Shounai Plain,Yamagata, Japan

Abstract

Slag silicate fertilizer (SSF) is applied to paddy fields with different soil chemical properties to increase silicon (Si) concentration in rice (Oryza sativa L.) plants. However, the effects of soil chemical properties on Si availability of SSF to rice Si uptake is poorly understood. To investigate the relationships between chemical properties of soils and the effects of SSF application on the Si concentration in rice plants, a field experiment was conducted in 2007 and 2008 at 18 paddy fields on the Shounai Plain, Yamagata, Japan. Two treatments were implemented: SSF applied at 1.5 t ha^?1 and a no-SSF control. The Si concentrations of rice tissues were measured at the tillering and ripening stages. The difference in the Si concentrations of rice tissues between treatments (ΔSi concentration) was used to evaluate the effect of SSF. The Si concentrations in the shoots and aboveground parts of the rice plants were significantly increased by the SSF application in six or more of the fields at the two growth stages, whereas the Si concentrations in the panicles of the rice plants at the ripening stage were not increased significantly in most fields. Results of two-way analysis of variance evidenced a significant effect of field on the ΔSi concentrations in the shoots and aboveground parts at both growth stages. Furthermore, the ΔSi concentrations in the same rice plant tissues and at the same growth stages in the first year and in the second year were found to be positively correlated. These results indicate that the effect of SSF on the Si concentration in shoots and aboveground parts of rice plants varies from field to field. The ΔSi concentrations in shoots and aboveground plant parts at both growth stages were also found to be negatively correlated with soil chemical properties, i.e., available Si, Si adsorption capacity, contents of Si adsorbents (acid oxalate-extractable iron and manganese) and the pH under flooded soil conditions. These findings imply that those soil chemical properties of paddy fields should be taken into account for better prediction of ΔSi concentration of rice plants.     

Effects of an 'enrichment feeder' on behavior and feather conditions of caged laying hens

The objective of this study was to compare the behaviors and feather conditions of caged laying hens fed by two different types of feeders. Seven tennis balls were placed on the feed trough to hide the feed for each of 6 experimental cages (treatment B). The same feed troughs without balls were used for 6 control cages (treatment NB). Forty-eight commercial white leghorn type hens were housed as 4 birds per cage (474 cm² per bird). The experimental period was from 22 to 32 weeks of age. At 28 weeks of age, the hens spent more time feeding in treatment NB (35%) than in B (27%). On the other hand, prefeeding behavior (extension of the neck over the trough or pecking at the balls) occupied more time in B (14%) than in NB (6%). The birds in B spent more time thrusting (thrusting other birds aside and trying to eat) than did the birds in NB (2 vs 0%). At 32 weeks of age, the mean proportion of hens feeding and prefeeding behavior in both treatments was similar to those at 28 weeks of age; however, differences of the behavior between the B and NB were relatively small. Feather damage on a scale of 0 (no damage) to 15 (denuded) increased with age, and the scores in B were less than those in NB at 27 weeks (0.75 vs 1.37), although not at 32 weeks. Egg production in the two treatments was the same, and the type of feeder used did not affect body weight. This device might provide hens with a more attractive environment than the conventional feeders; however, the enrichment feeder might need more improvement for the welfare of caged laying hens.     

Distribution of the FoToml gene encoding tomatinase in formae speciales of Fusarium oxysporum and identification of a novel tomatinase from F. oxysporum f. sp. radicis-lycopersici, the causal agent of Fusarium crown and root rot of tomato

The antifungal glycoalkaloid -tomatine accumulates in tomato plants and may protect plants from fungal infection. Fusarium oxysporum f. sp. lycopersici, the causal agent of vascular wilt of tomato, produces a tomatinase (FoToml) that degrades -tomatine to the nontoxic compounds tetrasaccharide lycotetraose and tomatidine. Induction of tomatinases and the distribution of FoToml homologs were examined among 30 strains belonging to 16 formae speciales of F. oxysporum. Tomatinase activity was found in 27 strains belonging to 15 formae speciales, but FoToml homologs (>98% sequence identity) were detected in only six strains belonging to four formae speciales. To identify tomatinases other than FoToml, -tomatine-inducible proteins of another tomato pathogen F. oxysporum f. sp. radicis-lycopersici were analyzed by two-dimensional gel electrophoresis. A protein with a molecular mass of 64kDa accumulated in the -tomatine-induced culture filtrates, and the protein had tomatinase activity, degrading -tomatine to lycotetraose and tomatidine.     

Large sulfur isotope fractionation does not require disproportionation

The composition of sulfur isotopes in sedimentary sulfides and sulfates traces the sulfur cycle throughout Earth's history. In particular, depletions of sulfur-34 ((34)S) in sulfide relative to sulfate exceeding 47 per mil (‰) often serve as a proxy for the disproportionation of intermediate sulfur species in addition to sulfate reduction. Here, we demonstrate that a pure, actively growing culture of a marine sulfate-reducing bacterium can deplete (34)S by up to 66‰ during sulfate reduction alone and in the absence of an extracellular oxidative sulfur cycle. Therefore, similar magnitudes of sulfur isotope fractionation in sedimentary rocks do not unambiguously record the presence of other sulfur-based metabolisms or the stepwise oxygenation of Earth's surface environment during the Proterozoic.