Effect of presence of rumen protozoa on degradation of cell wall constituents in gastrointestinal tract of cattle

The cell wall constituents of feces from three faunated and three defaunated (without ruminal ciliate protozoa) cattle fed on a Sudangrass hay and concentrate mixture (8:5) were analyzed. There was little difference in digestibility of dry matter between the faunated and defaunated cattle. Analysis of the fecal sugar residues revealed that the digestibilities of arabinose and galactose, derived from pectic and hemicellulosic substances located within the compound middle lamella, were higher in the defaunated cattle than the faunated cattle (P < 0.05), whereas the digestibilities of glucose and xylose, derived mainly from cellulose and xylan, were unchanged by the removal of protozoa. The digestibility of lignin was not different between the faunated and defaunated cattle, but those of mannose and p‐coumaric acid were lower in the defaunated than in the faunated animals (P < 0.05). The ratio of primary cell wall to secondary cell wall in fecal plant materials was lower for the defaunated than for the faunated cattle. The results in this study suggested that the defaunation enhanced the microbial degradation of the thin cell walls, but depressed the degradation of developed cell walls.     

Detoxification of α-tomatine by tomato pathogens Alternaria alternata tomato pathotype and Corynespora cassiicola and its role in infection

In tomato plants, α-tomatine, a steroidal glycoalkaloid saponin, inhibits fungal growth. Tomato pathogens that produce host-specific toxins, Alternaria alternata tomato pathotype causing Alternaria stem canker and Corynespora cassiicola causing Corynespora target spot, were investigated for sensitivity to α-tomatine. Although spore germination of A. alternata pathogenic and nonpathogenic to tomato and of C. cassiicola pathogenic to tomato was not affected by 0.1 mM α-tomatine, spore germination of C. cassiicola nonpathogenic to tomato was significantly inhibited. This result showed that A. alternata, regardless of its pathogenicity, and only the C. cassiicola pathogenic to tomato are resistant to α-tomatine. Germinating spores of A. alternata and C. cassiicola resistant to α-tomatine detoxified α-tomatine by degrading it to a less polar product. After inoculation of tomato leaves, spores of A. alternata and C. cassiicola nonpathogenic to tomato germinated and formed appressoria, but did not form infection hyphae in host tissues. When a host-specific toxin (CCT-toxin) produced by C. cassiicola pathogenic to tomato was added to nonpathogenic spores, colonization within leaves was observed in A. alternata, but not in C. cassiicola. On the other hand, when spores of C. cassiicola nonpathogenic to tomato were suspended in spore germination fluid of nonpathogenic A. alternata with α-tomatine detoxification activity, the fungus could be induced to colonize leaves in the presence of CCT-toxin. These results indicate that A. alternata tomato pathotype and C. cassiicola pathogenic to tomato detoxify α-tomatine during infection and that this detoxification is essential for host colonization by pathogens that produce host-specific toxins.     

Pathological evaluation of host-specific AAL-toxins and fumonisin mycotoxins produced by Alternaria and Fusarium species

Host-specific AAL-toxins and mycotoxin fumonisins are structurally related and were originally isolated from the tomato pathotype of Alternaria alternata and from Fusarium verticillioides, respectively. Previous reports on the production of fumonisin derivatives by the tomato pathotype suggested a possible involvement in the pathogenicity of the pathogen. Here, we have evaluated the role of fumonisin in A. alternata–tomato interactions. The results indicate that highly pathogenic isolates of A. alternata tomato pathotype produce AAL-toxin as the sole toxin, strongly implicating it as a pathogenicity factor. The related compound, fumonisin, is also toxigenic and has infection-inducing activity on susceptible tomato plants.     

In vitro but not in planta encapsidation of Rice gall dwarf virus core particles by the outer capsid P8 protein of Rice dwarf virus expressed in transgenic rice plants

Transencapsidation of the Rice gall dwarf virus (RGDV) inner core by the Rice dwarf virus (RDV) outer capsid P8 protein was examined in vitro and in planta. When RGDV core particles were incubated with an extract from RDV P8-transgenic rice leaf tissue, RDV P8 encapsidated the RGDV core particles to form double-shelled virus-like particles in vitro. In contrast, when RDV P8-transgenic rice plants were inoculated with RGDV, progeny RGDV particles contained RGDV P8 but RDV P8 was not detectable in the virions. No significant differences were found in acquisition by the vector insects and subsequent transmission rates between RGDV infecting nontransgenic rice plants and those infecting RDV P8-transgenic rice plants. These results indicate that mechanisms of and/or requirements for interactions between P8 and the inner core particles of phytoreoviruses differ between in vitro and in planta.     

Treatment of cow-waste slurry by a microbial fuel cell and the properties of the treated slurry as a liquid manure

Resource recycling and the proper treatment of animal waste to reduce its environmental impact are currently important issues for the livestock industry. A microbial fuel cell (MFC), a new type of bioreactor, is expected to play roles in both waste‐water purification and energy recovery. However, the generation of electricity from cow waste has not yet been examined. In this study, using an MFC, we examined the possibility of generating electricity from dairy‐cow waste slurry, and analyzed the properties of the treated slurry as liquid manure for resource recycling. The MFC treatment of the slurry generated electricity in a dose‐dependent manner, and the maximum power output by the MFC from a 1 g of chemical oxygen demand/L slurry was 0.34 mW/m². After the MFC treatment, 84% of the biological oxygen demand in the slurry was removed and three essential fertilizer elements (nitrogen, phosphorus, and potassium) were retained at 84, 70, and 91% levels, respectively. The amount of ammonia nitrogen in the slurry, as an element of fast‐release fertilizer, was increased by 1.9‐fold. Although the treated slurry displayed properties that made it preferable as liquid manure, further studies to improve the electrical power output by the MFC are required for practical use.     

Management approach using simple indices of deer density and status of understory vegetation for conserving deciduous hardwood forests on a regional scale

We investigated the validity and efficiency of a survey using sight per unit effort (SPUE) of sika deer and shrub-layer decline rank (SDR), which is an index of decline in the physical structure of a whole stand caused by sika deer, based on data collected on a broad scale. This survey was to be used to manage a deer population in order to conserve a forest ecosystem. First, we evaluated the spatial and temporal scales of deer density that are most appropriate for predicting decline in the status of understory vegetation. The model with SPUE calculated in a buffer with a radius of 4.5 km using data for the past 4 years was found to be the best. We showed that our knowledge of the relationship between deer density and status of shrub-layer vegetation is improved by identifying the most suitable spatial and temporal scales of SPUE for predicting SDR. Next, we quantified the effects of SPUE and environmental components on SDR in stands. We found that SPUE had the greatest effect on SDR among all explanatory variables. Moreover, the area under the curve (AUC) was large in a model that only used SPUE (AUC = 0.718). This result suggests that the variation in SDR among stands was explained well by SPUE regardless of differences in the forest environment. Furthermore, we identified the effective values of SPUE for preventing shrub-layer vegetation from declining through deer density control. We conclude that a management system based on SPUE and SDR is a simple and valid method for managing deer populations in order to conserve forest ecosystems.     

Prediction of the buckling stress of intermediate wooden columns using the secant modulus

We made several buckling tests of wooden columns with intermediate slenderness ratios () and examined the empirical formulas. On the basis of the examination, we formulated an equation for predicting the buckling stress () of an intermediate wooden column. Sitka spruce (Picea sitchensis Carr.) and buna (Japanese beech, Fagus crenata BI.) were used for the studies. A compressive load was applied on the specimen supported with pin ends, and the buckling stress was predicted by the tangent modulus theory and two empirical equations: those of Tetmajer and Newlin-Gahagan. The predicted - relations were compared with the test results, and the applicability of these predictions were examined. Based on the comparisons, we formulated an equation that can predict the - relations of materials with various stress-strain characters in the plastic strain range.     

Leaf-litter decomposition of 15 tree species in a lowland tropical rain forest in Sarawak: dynamics of carbon,nutrients, and organic constituents

The effects of tree species on the dynamics of nutrient transformations during leaf-litter decomposition are not well understood in tropical rain forests. To examine differences in the dynamics of C, nutrients, and organic constituents during decomposition among tree species, the leaf-litter decomposition of 15 trees was assessed using a litter-bag method in a lowland tropical rain forest in Sarawak. The dynamics of C was parallel to that of weight loss. The dynamics of nutrients were grouped into three patterns. The dynamics of K was characterized by a high leaching loss in the initial stages, and that of Ca and Mg generally showed a gradual decrease over the course of decomposition. The dynamics of N and P showed highly different patterns with the weight loss, and was characterized by relatively higher remaining mass at the end of the experiment. The variations or exceptions of nutrient dynamics among tree species were considered to be related to the initial concentration of each nutrient. For the dynamics of organic constituents, water-soluble carbohydrates disappeared quickly at the initial stages, and acid-soluble carbohydrates were the second fastest decomposing fraction; the decomposition of acid-insoluble residue (AIS) was the slowest. The release of limiting nutrients (N and P) generally followed the disappearance of AIS, but was independent of the disappearance of AIS when the initial concentrations of these nutrients were very low.     

Distribution of boron in wood treated with aqueous and methanolic boric acid solutions

The distributions of boron in Japanese cedar (Cryptomeria japonica D. Don) sapwood blocks treated with aqueous or methanolic boric acid [B(OH)₃] solutions were explored through Raman spectroscopy and prompt gamma-ray analysis (PGA). B(OH)₃ was the sole boron species observed in Raman spectra of the wood blocks treated with either solution. Plots of weight gain of the treated wood blocks versus boron concentration in treatment solutions were found to be linear. The results indicated that the methanolic solution makes it possible to impregnate wood with much larger amounts of boron than the aqueous solution. PGA confirmed that B(OH)₃ was highly enriched near the end grains of the treated wood blocks. Raman measurements suggested that boron content in the bulk of the wood block is not as large as expected from the weight gain of the treated wood blocks when an ordinary air-drying method is used. It was concluded that the aqueous solution impregnates the cell walls of wood with boron more easily than the methanolic solution. Part of this report was presented at the 55th (Kyoto, March 2005) and 56th (Akita, August 2006) Annual Meetings of the Japan Wood Research Society. This article follows the previous rapid communication “Analysis of boron in wood treated with boric acid solutions using Doppler broadening method of prompt gamma-rays.” J Wood Sci (2006) 52:279–281