Reproductive losses associated with porcine circovirus type 2 in a Japanese herd of seronegative sows

From April to July 2009, there was a high rate of reproductive losses in a 30-sow, farrow-to-finish swine herd in Yamagata Prefecture, Japan. Histopathological examinations of heart tissue from stillborn and preweaning piglets showed nonsuppurative, necrotizing lesions. Immunohistochemical staining and polymerase chain reaction analysis of myocardial lesions revealed the presence of porcine circovirus type 2 (PCV2) antigens and DNA in these tissues. Indirect immunofluorescence also showed that the PCV2 antibody positive rate in the sows was higher in May 2009 than in December 2008. The results of this study suggest that PCV2 spread to this farm and caused a high rate of reproductive losses.     

Genotypic differences in chlorophyll, lutein, and beta-carotene contents in the fruits of actinidia species

Chlorophyll, lutein, and beta-carotene contents in Actinidia fruits were determined by high-performance liquid chromatography in various genotypes, including five Actinidia deliciosa, seven Actinidia chinensis, two Actinidia rufa, five Actinidia arguta, and three interspecific hybrids. The concentrations of chlorophyll, lutein, and beta-carotene in the fruit of A. deliciosa Hayward were 1.65, 0.418, and 0.088 mg/100 g fresh weight, respectively. Of A. deliciosa cultivars, Koryoku showed significantly higher concentrations in chlorophyll, lutein, and beta-carotene than Hayward. In most cultivars of A. chinensis, although both chlorophyll and lutein contents were significantly lower than in Hayward, the beta-carotene content tended to be slightly higher. In A. rufa, A. arguta, and their interspecific hybrids, the contents of chlorophyll, lutein, and beta-carotene were much higher than in Hayward. In particular, these fruits were found to be the richest dietary source of lutein among commonly consumed fruits.     

Development and evaluation of a support system for forest education

Field education programs have been conducted throughout the world because learning through experience is an important process in environmental and forest education. We developed a support system for forest education that consists mainly of a Global Positioning System (GPS) and personal digital assistant (PDA). Moreover, field experiments were conducted to evaluate educational efficacy as well as usability of the developed system. Through a post-questionnaire the developed system was highly evaluated in terms of educational efficacy and enjoyment. On the other hand, the questionnaire revealed the need for technical improvements. For example, the drawing function, which involves the use of a stylus pen, was the most poorly evaluated because a drawing could not be partially erased as with an eraser and representation was not sufficiently accurate. In addition, positions where information on nature appeared were sometimes inaccurate due to positional errors caused by using the autonomous GPS. Some participants answered that walking with the developed system was also troublesome due to its shape and size. In fact, they did not feel comfortable about the cables connecting the GPS to the PDA and GPS to its antenna. Although there were some problems with the system, we believe that the field education program was successful because 95% of the participants answered that they would join a similar program again.     

Virtual forest: design and evaluation of a walk-through system for forest education

Forest education is generally conducted in a real forest to provide learners a direct experience with reality. However, often it is not easy to participate in forest education programs carried out in remote places due to distance, limited time, or economic or physical restrictions. Therefore, we developed a walk-through system for forest education in a virtual forest and evaluated its educational efficacy as well as usability through indoor experiments. The virtual forest was constructed with omnidirectional images taken in a forest using a digital camera with an omnidirectional vision sensor. The results of the postquestionnaire showed that the developed system was highly evaluated by the participants in the experiments in terms of educational efficacy and enjoyment. Also, comparison of results of prequestionnaire and postquestionnaire showed that it had educational value. On the other hand, some technical problems in the developed system were revealed. For example, 45.0% of the participants answered that the walk-through in the virtual forest did not proceed with sufficient smoothness, and encountered unexpected slowdowns and stops. In addition, image quality was not high enough to identify small objects in the virtual forest. Regardless of these problems, we believe that the computer-based forest education was successful because 88.3% of the participants answered that they would like to join a similar program again and 90.0% answered that they would like to visit the real forest that the virtual forest imitated.     

Increase of inbreeding by stocking on wild population assessed by using in dividual-based life history model

ABSTRACT:   The genetic impact of stocking on natural populations was assessed by using individual-based life history models. Models were constructed that included density-dependent mortality at the early life stage, natural mortality, fishing mortality, and the number of released fish. These variables were varied by using random numbers. The focus was on the genetic impact of the number of released fish, the number of parent fish producing seedlings that were released, the sex ratio of the parent fish, fishing mortality, and the methods to select the parents of the seedlings. When brood stock size in the hatchery was five males and five females, the coefficient of inbreeding was about 27-fold as high as that in the case of 50 males and 50 females at the 50th generation. The coefficient increased about fivefold at the 50th generation, when the sex ratio of the parents changed from 50 males and 50 females to 10 males and 90 females. When parents were taken from wild populations at random, extreme fishing mortality reduced genetic diversity.     

Suppression of chicken J chain production by in ovo bursectomy

The influence of in ovo bursectomy on the levels of J and mu chains in the sera of embryonic and hatched chicks was studied by the dot blotting immunoassay. The results indicated a decrease in the level of J chains during the embryonic stage after treatment with testosterone compared with normal chicks. Testosterone treatment caused a decrease in J-chain levels after hatching which was more marked in reduced-alkylated than in non-reduced sera. In contrast, testosterone caused no significant change in serum levels of mu chains, either in ovo or after hatching. Our findings further present the paradox that although removal of the bursa of Fabricius by testosterone treatment did not impair mu-chain synthesis, B-cell differentiation was suppressed. These observations indicate that in ovo bursectomy selectively inactivates B-cell differentiation as indicated by the induction of immunodeficiency, and results in the failure of J-chain production.     

Nitrification and denitrification in an acidic soil of tea (Camellia sinensis L.) field estimated by δ15N values of leached nitrogen from the soil columns treated with ammonium nitrate in the presence or absence of a nitrification inhibitor and with slow-release fertilizers

Forty-two-day-old wheat (Triticum aestivum L. var. Asakazekomugi) plants were treated with complete, K-free (—K), Ca-limited (—Ca), and Mg-free (—Mg) nutrient solutions for 10 days using 2 mM NH₄NO₃ as the nitrogen source, which was replaced with 4 mM ¹⁵ NH₄C1 or Na¹⁵NO₃ for the subsequent 2 days to investigate the absorption, translocation, and assimilation of inorganic nitrogen in relation to the mineral supply. In another experiment plants were grown on NO₃ ^?, NH₄ ⁺, NH₄N0₃, and K-free and Ca-limited NH₄N0₃ nutrient solutions for 10 days, and then in the latter three treatments the nitrogen source was replaced with NO₃ ^? and half of the —K plants received K for 6 days to examine the changes in the nitrate reductase activity (NRA).

Wheat plants absorbed NH₄ ^?N and NO₃-N at a similar rate. Influence of K on the absorption of N0₃-N was stronger than that on the absorption of NH₄-N in wheat plants. The supply of K to the —K plants increased the absorption of NO₃-N, while the absorption of NH₄-N still remained at a lower rate in spite of the addition of K. A limited supply of Ca and lack of Mg in nutrient media slightly affected the absorption of NH₄-N. The influence of K was stronger on the translocation of nitrogen from roots to shoots, while Ca and Mg had little effect. When K was supplied again to the —K plants the translocation of NO₃,-N was more accelerated than that of NH₄-N. Incorporation of NH₄-N into protein was higher than that of NO₃-N in all the tissues; root, stem, and leaf. Assimilation of NH₄-N and NO₃-N decreased by the —K and —Mg treatments.

Leaf NRA of wheat plants decreased in the —K and —Ca plants. Higher leaf NRA was found when K was given again to the —K plants than when the plants were continuously grown in K-free media. Replacement of NO₃ ^? with NH₄ ⁺ as the nitrogen source caused a decline of leaf NRA, while the supply of both NH₄ ^?N and NO₃-N slightly affected the leaf NRA.     

Resonant amplification of magnetic domain-wall motion by a train of current pulses

The current-induced motion of magnetic domain walls confined to nanostructures is of interest for applications in magnetoelectronic devices in which the domain wall serves as the logic gate or memory element. The injection of spin-polarized current below a threshold value through a domain wall confined to a pinning potential results in its precessional motion within the potential well. We show that by using a short train of current pulses, whose length and spacing are tuned to this precession frequency, the domain wall's oscillations can be resonantly amplified. This makes possible the motion of domain walls with much reduced currents, more than five times smaller than in the absence of resonant amplification.