Bovine herpesvirus-1 (BHV-1) recombinant expressing pseudorabies virus (PrV) glycoproteins B and C induces type 1 immune response in BALB/c mice

Bovine herpesvirus 1 (BHV-1) attached poorly and penetrated into a mouse cell line, BALB 3T3/A31, but a recombinant BHV-1/TF7-6, which expresses pseudorabies virus (PrV) gB and gC genes, did attach and penetrated into cells more efficiently. In this study the gene green fluorescent protein (GFP) has been integrated into genome of BHV-1/TF7-6 and its parental line of BHV-1. When the mouse mesenteries were incubated in vitro and infected with BHV-1/TF7-6/GFP, strong fluorescence was observed while BHV-1/GFP infection hardly demonstrated fluorescence, suggesting that BHV-1 recombinant expressing PrV gB and gC can infect mouse tissue cells more efficiently than the parental BHV-1 does. When BALB/c mice were inoculated with purified BHV-1/TF7-6 or its parental BHV-1, the former induced lower level of anti-BHV-1 immunoglobulin G (IgG) than the latter did. When sub-classes of anti-BHV-1 IgG were analyzed, it was found that mice immunized with BHV-1/TF7-6 or the parental BHV-1 demonstrated the same level of IgG2a. Since anti-BHV-1 IgG1 level was lower in mice inoculated with BHV-1/TF7-6, the IgG2a:IgG1 ratio was higher in BHV-1/TF7-6 inoculated mice than in the parental BHV-1 inoculated ones. These results indicate that BHV-1/TF7-6 induces type 1 predominant immune to BALB/c mice.     

Experimental and clinical studies on plasma leptin in obese dogs

Leptin is a protein synthesized and secreted primarily by adipocytes, and the circulating leptin concentration is elevated in obese humans and rodents. Recently, we have established a sandwich enzyme-linked immunosorbent assay for canine leptin. In the present study, plasma leptin concentrations were measured in experimentally developed obese beagles and in clinically obese dogs. When 5 male beagles were given a high-energy diet for 3 months, all of them became obese and the plasma leptin concentration significantly increased from 2.4+/-1.2 to 4.9+/-0.9 ng/ml, positively correlating with body fat content estimated by the deuterium oxide dilution method (r=0.87). The leptin concentrations of plasma samples collected from 59 dogs in veterinary practices were compared with their body condition scores (BCS). The plasma leptin concentrations of obese dogs were 9.7+/-0.7 and 12.3+/-1.5 ng/ml at BCS=4 and BCS=5, respectively, which were significantly higher than those of optimal (BCS=3) dogs (2.7+/-0.3 ng/ml). There was no significant effect of sex and breed. A weak positive correlation (r=0.37) was found between the plasma leptin concentration and age, probably due to the lesser content of visceral fat in puppies younger than 1 year old. These results indicate that plasma leptin is a good index of adiposity in dogs regardless of breed, age and sex, and may be useful for quantitative assessment of obesity in small animal practice.     

Immunogenic properties of a bovine herpesvirus-1 (BHV-1) recombinant expressing major pseudorabies virus (PrV) glycoproteins in combination

A recombinant bovine herpesvirus type 1 (BHV-1), designated BHV-1/TF17-1, which expresses pseudorabies virus (PrV) glycoproteins gB, gC, gD, gE and gI in combination was constructed. To test the protective immunity, 10 mice were inoculated with BHV-1/TF17-1 and three weeks later 10 mice were intraperitoneally (i.p.) challenged with 20 LD50 virulent PrV (YS-81). BHV-1/TF17-1 protected all the mice from the PrV lethal challenge while all the control mice died in around 3 days. Mice vaccinated with BHV-1/TF17-1 acquired high PrV-neutralizing antibody titers and demonstrated strong delayed type hypersensitivity responses and moderate in vitro lymphocyte proliferative responses to PrV antigen. Since the major PrV glycoproteins were integrated into virions (probably into viral envelope), BHV-1/17-1 was neutralized with anti-PrV antiserum. However, the susceptibility of BHV-1/TF17-1 to anti-PrV antiserum is 2- to 4-fold lower than that of PrV vaccine lines. Our results demonstrated the possibility of BHV-1/17-1 as a vaccine to protect piglets from Audjesky's disease where maternal antibodies against PrV interfere attenuated live PrV vaccines.     

Effects of carbon and nitrogen amendment on soil carbon and nitrogen mineralization in volcanic immature soil in southern Kyushu,Japan

Soil N mineralization is affected by microbial biomass and respiration, which are limited by available C and N. To examine the relationship between C and N for soil microbial dynamics and N dynamics, we conducted long-term laboratory incubation (150 days) after C and N amendment and measured changes in C and N mineralization, microbial biomass C, and dissolved C and N throughout the incubation period. The study soil was volcanic immature soil from the southern part of Japan, which contains lower C and N compared with other Japanese forest soils. Despite this, the area is covered by well-developed natural and plantation forests. Carbon amendment resulted in an increase in both microbial biomass and respiration, and net N mineralization decreased, probably due to increasing microbial immobilization. In contrast, N amendment resulted in a decrease in microbial respiration and an increase in net N mineralization, possibly due to decreased immobilization by microbes. Amendment of both C and N simultaneously did not affect microbial biomass and respiration, although net N mineralization was slightly increased. The results suggested that inhibitory effect on microbial respiration by N amendment should be reduced if carbon availability is higher. Thus, soil available C may limit microbial biomass and respiration in this volcanic immature soil. Even in immature soil where C and N substrate is low, soil C, such as plant root exudates and materials from above- and belowground dead organisms, might help to maintain microbial activity and N mineralization in this study site.     

Host selection of small cedar longicorn beetle, <Emphasis Type="Italic">Callidiellum rufipenne</Emphasis> (Coleoptera:Cerambycidae), on Japanese cedar, <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>, in terms of bark water content of host trees

We caught the adults of a secondary wood-boring insect, Callidiellum rufipenne (Motschulsky), on Japanese cedar, Cryptomeria japonica D. Don., trees and logs with manipulated bark water contents to clarify the mechanism of host selection by C. rufipenne. More C. rufipenne were trapped when the bark water content range was ca. 120–200%. Fewer C. rufipenne were trapped at higher and lower bark water contents. These findings indicate that C. rufipenne adults do not simply select weakened or dying trees. Bark water content is one of important factors for C. rufipenne choosing their host for oviposition.     

Establishment and growth of coniferous seedlings in an altered forest floor after long-term exclusion of deer

We evaluated differences between the forest floors and the establishment and growth of coniferous seedlings in fenced (13 years) and unfenced plots on Mt Ohdaigahara where the sika deer (Cervus nippon) population density is high. Large coniferous seedlings (height > 0.05 m) were less abundant in the unfenced plot, as a result of deer browsing. Small coniferous seedlings (height < 0.05 m), however, were more abundant in the unfenced plot, where most seedlings of Abies homolepis were found on bare ground and those of Picea jezoensis var. hondoensis were found on buttresses and fallen logs. The large area of bare ground in the unfenced plot was caused by deer browsing. Deer therefore have an indirect effect on the emergence and growth of small coniferous seedlings by modifying the forest floor.     

Investigation of relationships between cell and pulp properties in Eucalyptus by examination of within-tree property variations

 Relationships between cell and pulp properties were investigated by examining the within-tree property variations in Eucalyptus camaldulensis and Eucalyptus globulus. Properties investigated included proportions of ray and axial parenchyma, thickness of cell walls and cell wall percentages. The characteristics of the ray and axial parenchyma (their proportions and wall thickness) were found to have a significant influence on all measured pulp properties, including paper strength properties. Multiple regression of pulp properties in relation to cell properties revealed that nearly all measured pulp properties were explained by cell properties at the 1% significance level. It was concluded, therefore, that all cell types are important for predicting pulp properties, and it is strongly recommended that tree breeding programs for Eucalyptus include the measurement of all cell types. Received 6 July 1999     

Termiticidal activity of wood vinegar, its components and their homologues

The termiticidal activity of wood vinegar, its components, and their homologues have been studied. Three kinds of wood vinegar made from the mixed chips ofCryptomeria japonlca andPseudotsga menziesii (wood vinegar A),Quercus serrata (wood vinegar B), andPinus densiflora (wood vinegar C) exhibited high termiticidal activities againstReticulitermes speratus. Acetic acid, which is the largest content of wood vinegar, exhibited high termiticidal acitivity. The contents of organic fraction of wood vinegars and acetic acid might be responsible for the differences in termiticidal activities among these wood vinegars. The structure and termiticidal activity relations of phenols were studied. Phenol with some substituents revealed higher termiticidal activity than benzene derivatives, which have no hydroxyl group; an ortho substituent of phenol plays an important role in termiticidal activity. It has become apparent that high termiticidal activity cannot be obtained by a phenolic hydroxyl group alone; it can be obtained, however, by some substituents, especially an ortho substituent in addition to a phenolic hydroxyl group. The bulkiness of the substituent at the ortho position participates in termiticidal activity; activity decreases as the size of an ortho substituent increases. It is thought that the interaction at the receptor site of termites is affected by the increased size of the ortho substituent.     

Melatonin Supplementation During In Vitro Maturation and Development Supports the Development of Porcine Embryos

Melatonin has been reported to improve the in vitro development of embryos in some species. This study was conducted to investigate the effect of melatonin supplementation during in vitro maturation (IVM) and development culture on the development and quality of porcine embryos. In the first experiment, when the in vitro fertilized embryos were cultured with different concentrations of melatonin (0, 10, 25 and 50 ng/ml) for 8 days, the blastocyst formation rate of embryos cultured with 25 ng/ml melatonin (10.7%) was significantly increased (p < 0.05) compared to the control embryos cultured without melatonin (4.2%). The proportion of DNA‐fragmented nuclei in blastocysts derived from embryos cultured with 50 ng/ml melatonin was significantly lower (p < 0.05) than that of embryos cultured without melatonin (2.1% vs 7.2%). In the second experiment, when oocytes were cultured in the maturation medium supplemented with different concentrations of melatonin (0, 10, 25 and 50 ng/ml), fertilized and then cultured with 25 ng/ml melatonin for 8 days, there were no significant differences in the rates of cleavage and blastocyst formation among the groups. However, the proportions (2.7–5.4%) of DNA‐fragmented nuclei in blastocysts derived from oocytes matured with melatonin were significantly decreased (p < 0.05) compared to those (8.9%) from oocytes matured without melatonin, irrespective of the concentration of melatonin. Our results suggest that supplementation of the culture media with melatonin (25 ng/ml) during IVM and development has beneficial effects on the developmental competence and quality of porcine embryos.