Carbon allocation in mycelia of arbuscular mycorrhizal fungi during colonisation of plant seedlings

The direction of carbon (C) allocation in mycorrhizal mycelia is of fundamental importance to coexistence of individual plants. We therefore investigated the transfer of C from established plants to plant seedlings through fungal mycelia. C allocation by the arbuscular mycorrhizal (AM) fungus Glomus intraradices, from ‘donor’ plants to mycelia in soil and two different species of introduced ‘receiver’ seedlings, was investigated in a pot experiment using ¹³C labelling and fatty acid analysis. After ¹³CO₂ application to the shoots of Trifolium subterraneum or Plantago lanceolata, used as donor plants, T. subterraneum and P. lanceolata receiver seedlings were introduced. Samples were collected 4-20 days after ¹³CO₂ application and analysed regarding ¹³C and the fatty acid 16:1ω5, the signature of AM fungi. ¹³C transfer from T. subterraneum donor plants was demonstrated by ¹³C enrichment of the roots of the receiver seedlings, but not from the P. lanceolata donor plants. ¹³C allocation to the neutral lipid fatty acid 16:1ω5 was only 1 ng in each receiver seedling, but 2 μg of the fatty acid in whole soil. The results indicate that C allocation through mycelial networks is influenced by the donor plant species, but is not directed towards receiver seedlings to any higher degree than towards other directions. The importance of the extraradical AM fungal mycelium as a C sink was demonstrated.     

Effect of Dietary Inclusion of Blue Mussel Extract on Growth and Body Composition of Japanese Flounder Paralichthys olivaceus

Dietary inclusion of a water-soluble fraction of blue mussel Mytilus galloprovincialis was examined as a feeding stimulant for juvenile Japanese flounder Paralichthys olivaceus . The control diet mainly consisted of fish meal, potato starch, and pollack liver oil. Five, 10, and 20% (weight/weight) of the control diet was exchanged with aqueous extracts of blue mussel meat in experimental groups. Fish of about 10 g in initial body weight were fed each diet to satiation, twice daily, 6 d per wk for 6 wk at 20 C. The final body weight, weight gain, and feed efficiency of fish fed the diets containing blue mussel extracts were significantly higher than those of fish fed the control diet. However, these parameters were not different among experimental groups containing blue mussel extract independent of the inclusion level of extract. A similar trend was shown in protein efficiency ratio as fish fed the control diet had a significantly lower protein efficiency ratio than the other dietary groups. Compared to the control diet, higher plasma protein and lower triglyceride were found in fish fed the diets with the extract, while other blood constituents were relatively similar for the dietary groups tested. On the other hand, whole-body crude lipid content and lipid retention of fish fed the diets with the extract were generally significantly higher than those of fish fed the control diet. Whole body crude protein was identical regardless of the dietary composition; however, protein retention of fish showed a similar trend to lipid retention.     

电阻抗分析法在海藻酸钙胶囊干燥中的应用

海藻酸钙胶囊是由大分子、水分子和离子组成的复杂网络结构,其水分含量很高(约3500%,以干基计)。在海藻酸钙胶囊干燥过程中,用常规分析方法确定干燥机理和硬化反应关键点等比较困难。电阻抗分析法在实际分析中有很多优点,该研究用于监控海藻酸钙胶囊的干燥进程。确定了电阻抗分析法的测定条件,测定并分析了几种干燥过程中电阻抗特性的变化     

Effects of low protein diet and low protein diet supplemented with synthetic essential amino acids on meat quality of broiler chickens

We investigated the effects of a low crude protein (CP) diet and a low CP diet supplemented with synthetic essential amino acids (EAA) on the meat quality of broiler chickens. Twenty‐one‐day‐old chickens were assigned to one of three diets: control, low CP (LCP), or low CP supplemented with EAA (ELCP). The chickens received these diets for 10 days. The shear force value (SFV) and free glutamate content of the Pectoralis major muscle were measured as indicators of the meat toughness and taste. The collagen and crude fat content of the muscle and the cross‐sectional area of myofibers were measured to evaluate the effects of the LCP and ELCP diets on meat toughness. The SFV of the ELCP group was 47% lower than that of the control group (P < 0.01). However, the LCP diet did not affect the SFV. The collagen and crude fat content were not affected by the dietary treatment. The cross‐sectional area was lower in the LCP and ELCP groups (P < 0.05) than the control group. The free glutamate content of muscle was not affected by the dietary treatment. Thus, a low CP diet supplemented with EAA is an effective means of producing tender meat.     

Automated analysis of fine‐root dynamics using a series of digital images

Information related to the growth of fine roots is important for understanding C allocation in trees and the mechanisms of C cycling in ecosystems. Observations using a camera or scanner embedded in the soil enabled us to obtain continuous images of fine‐root‐growth dynamics. However, these methods are still labor‐intensive because the image analysis has to be conducted manually. We developed an automated method for tracking movement or elongation of fine roots using a sequence of scanner images. We also show how data obtained with these methods can be used for calculating fine‐root behavior. Two A4‐size scanners were buried in a mixed forest in Japan and images were taken continuously from within the soil. We preprocessed these images by extracting the fine‐root area from the images and developed an automated calculation plug‐in we named A‐root for tracking growth movement of the tips of fine roots. A‐root and manual‐tracking results were compared using the same images. The results show the A‐root and manual‐tracking methods yielded similar levels of accuracy. The average growth rate of 17 fine roots tracked using the program was 0.16 mm h^–1. The observation of the direction of growth in fine roots showed the direction may be influenced by the original root's growth where the fine roots branched, distribution of soil particles, other roots, and the force of gravity. The A‐root analysis also suggested there may be an interaction between speed of growth and changes in direction of growing fine roots.     

Control of Pseudomonas mastitis on a large dairy farm by using slightly acidic electrolyzed water

The disinfection effect of slightly acidic electrolyzed water (SAEW) use in a farm where Pseudomonas mastitis has spread was evaluated. Despite the application of antibiotic therapy and complete cessation of milking infected quarters, numerous new and recurrent Pseudomonas aeruginosa clinical mastitis infections (5.8–7.1% of clinical mastitis cases) occurred on the farm from 2003 to 2005. Procedural changes and equipment modifications did not improve environmental contamination or the incidence of Pseudomonas mastitis. To more thoroughly decontaminate the milking parlor, an SAEW system was installed in 2006. All milking equipment and the parlor environment were sterilized with SAEW (pH 5–6.5, available chlorine 12 parts per million) before and during milking time. After adopting the SAEW system, the incidence of clinical and subclinical Pseudomonas mastitis cases decreased significantly (P < 0.0001) and disappeared. These findings suggest that SAEW effectively reduced the incidence of mastitis in a herd contaminated by Pseudomonas species. This is the first report to demonstrate the effectiveness of disinfection by SAEW against mastitis pathogens in the environment.     

Transport stress increases somatic cell counts in milk, and enhances the migration capacity of peripheral blood neutrophils of dairy cows

The present study was designed to determine the effects of physiological stress on milk-somatic cell counts (SCC) and function of bovine peripheral blood leukocytes (PBL). Nine healthy lactating cows were used in the examination. Five cows were transported 100 km for 4 hr (transported group; TG), and 4 cows were penned (non-transported group; NTG). Blood and milk samples were collected at 0, 2, and 4 hr after loading, and at 2 hr, and 1, 2, 3, and 6 days after unloading. The following activities were measured: adhesion receptor (CD 18 and L-selectin) expression of neutrophils and monocytes, migration capacity and percentage of apoptotic cells of neutrophils, serum soluble L-selectin (sL-selectin), plasma cortisol, and SCC. A significant increase in plasma cortisol and milk SCC was observed in TG. Leukocytosis, derived from neutrophils was recorded in TG, and was indicated by apoptotic measurement as an increase of young cells from the marginal pool. Increased migration and decreased surface expression of both L-selectin and CD 18 in neutrophils were observed after transportation. Elevated serum sL-selectin was also noted as a result of transportation. The present study indicated that transport stress modulates peripheral blood neutrophil function, particularly enhancing migration capacity, and causes diapedesis across the mammary epithelium. Increased milk SCC in transported cattle might be due to these phenomena, and severe physiological stress may bring about an increase in SCC in milk.     

Effects of dietary lysine levels and lighting conditions on intramuscular fat accumulation in growing pigs

This study was conducted to test our hypothesis that intramuscular fat (IMF) accumulation increases in pigs fed on a low lysine diet during the dark period than those fed on the same diet during the light period. Using barrows aged 6 weeks, we monitored whether serum glucose and insulin levels were affected by light conditions. Two diets with different levels of lysine, 0.78% (LL diet) and 1.37% (control diet) were prepared. Eight pigs were fed on the diet during the light period, while the remaining pigs were fed during the dark period. The pigs were fed either the LL diet or the control diet. Although IMF contents of Longissimus dorsi (LD) muscle were higher in the pigs fed on a LL diet (p < .05), the light conditions had no effect. Low dietary lysine caused reduction in serum glucose levels (p < .05) and serum insulin levels (p = .0613). However, they were also unaffected by the lighting conditions. To gain further insights, we determined the messenger RNA levels of insulin receptor, insulin receptor substrate 1, acetyl CoA carboxylase, and fatty acid synthase in LD and Rhomboideus muscles and in the liver.     

Tomato yellow leaf curl virus accumulates in vesicle-like structures in descending and ascending midgut epithelial cells of the vector whitefly, Bemisia tabaci, but not in those of nonvector whitefly Trialeurodes vaporariorum

Begomoviruses are transmitted by a single species of vector insect, the whitefly Bemisia tabaci, in a circulative manner. However, the mechanisms of this strict vector specificity have not been clarified. By immunoelectron microscopy, we showed that a begomovirus, Tomato yellow leaf curl virus (TYLCV), can enter midgut epithelial cells of the vector whitefly B. tabaci but not those of a nonvector whitefly, Trialeurodes vaporariorum, belonging to the same family. In midgut epithelial cells of viruliferous B. tabaci, the virus was localized in vesicle-like structures, suggesting endocytosis as an entry mechanism. These structures were also observed in midgut cells of nonviruliferous B. tabaci that had fed on healthy plants and in those of the nonvector T. vaporariorum that had fed on virus-infected plants. Vesicles containing TYLCV particles were observed most frequently in cells in the anterior part of the descending midgut, suggesting that this is the major entry site. These results clearly demonstrated that the virus-containing vector and nonvector whiteflies differ in the cellular localization of the virus and strongly suggest that a critical step in determining the vector insect specificity of begomoviruses is the entry of the viruses into midgut epithelial cells.     

Effects of ammonia and hydrogen sulfide on physical and biochemical properties of the claw horn of Holstein cows

The effects of ammonia and hydrogen sulfide on the physical and biochemical properties of the claw horn of Holstein cows were evaluated. Significant (P < 0.05, 0.01) decreases in hardness and elasticity were found in claw horns soaked in ammonia (NH₃) and hydrogen sulfide (H₂S) solutions compared with those that were soaked in water for 12, 24, and 48 h. Water absorption rate, as a indicator of permeability barrier function, increased significantly (P < 0.05) over time during the soaking period and was found to be dependent on the concentrations of NH₃ and H₂S in the solutions. The contents of ceramide, the main lipid component for the permeability barrier system of the stratum corneum, were significantly decreased in claw horns soaked in NH₃ and H₂S solutions compared with the values before soaking. Quantities of eluted protein released from claw horns treated with NH₃ and H₂S solutions were approximately 20 times and 30 to 40 times greater than those released from claw horns treated with water alone. Interestingly, the quantities of cytokeratin 10, the main cytoskeletal protein of the stratum corneum, eluted from claw horns treated with NH₃ and H₂S solutions were markedly greater than the quantity released from horns soaked in water. Our results suggest that abnormal changes in the physical property of claw horn caused by NH₃ and H₂S treatment are due to disruption of the biochemical property of the claw horn induced by these chemical agents derived from slurry.