Relationship between fallow period,forest vegetation and weeds in swidden agriculture in northern Laos

Weed suppression is an important reason for fallowing in swidden systems. Recently, in Laos, an increase in weeds and resulting increase in labor input has become a problem; however, causal factors influencing weed growth and weeding labor other than fallow period have yet to be fully examined. Therefore, an experimental research on swidden weeds, combining a forest survey and interviews with local farmers, was conducted in a mountain village in northern Laos where swidden agriculture is practiced as a major means of livelihood. Weed amount, weed composition and time required for weeding were found to be more influenced by fallow vegetation than fallow period. Bushy vegetation in a short fallow field was shown to lead to abundance of herbaceous weeds, resulting in higher labor input. There was a possibility that increases in some bamboo species were a cause of recent weed increases. Based on the results, we suggest that maintaining a minimum fallow period of forest fallowing, with fallow management to suppress bamboo and promote tree growth may be effective in reducing labor input in swidden agriculture.     

Effect of a Large Dose of Di (2-ethylhexyl) phthalate (DEHP) on Hepatic Peroxisome in Cynomolgus Monkeys (Macaca Fascicularis)

To elucidate the effect of a large dose of di (2-ethylhexyl) phthalate (DEHP), a plasticizer and peroxisome proliferator-activated receptor-α (PPARα) agonist, on hepatic peroxisomes, we orally administered 1,000 mg/kg/day, once daily, to 3 male and 4 female cynomolgus monkeys for 28 days consecutively. Light-microscopic and electron microscopic examinations of the liver were carried out in conjunction with measurement of the hepatic fatty acid β-oxidation system (FAOS), carnitine acetyltransferase (CAT) and carnitine palmitoyltransferase (CPT) activities, which are peroxisomal and/or mitochondrial enzyme activities. Electron microscopically, enlargement of the mitochondria was observed with lamellar orientation of the cristae along the major axis. Although the number of peroxisomes showed a tendency to increase when compared with those in a biopsied specimen before treatment, no abnormality in morphology was observed. A slight increase in CPT activity was noted at termination. No changes were noted in hepatic FAOS or CAT activity. In conclusion, although repeated oral treatment of cynomolgus monkeys with a large dose of DEHP induced a subtle increase in the numbers of peroxisomes with slight enlargements of the mitochondria, this low-sensitivity response to peroxisome proliferators in cynomolgus monkeys was considered to be closer to the response in humans than that in rodents.     

Cynomolgus macaque CYP4 isoforms are functional, metabolizing arachidonic acid

Cytochrome P450 (CYP) is important for metabolism of not only xenobiotics such as drugs, but also endogenous compounds including arachidonic acids. CYP4A11, CYP4F3v2, CYP4F11, and CYP4F45 have been identified in cynomolgus macaque, an animal species widely used for investigation of drug metabolism due to its evolutionary closeness to human. However, their metabolic functions have not been investigated. In this study, proteins were heterologously expressed in Escherichia coli and characterized by metabolic assays using arachidonic acids as substrates that are metabolized by CYP4 isoforms in human. The results showed that all four CYPs metabolized arachidonic acids. Therefore, cynomolgus macaque CYP4A11, CYP4F3v2, CYP4F11, and CYP4F45 are functional enzymes.     

Multifunctional activity of vitamin E in animal and animal products: A review

Vitamin E is an essential nontoxic fat‐soluble micronutrient whose effects on livestock performance and products can be attributed to its antioxidant and nonantioxidant properties. Although it is needed in small quantity in the diet, its roles in livestock production are indispensable as it is required in boosting performance, nutritional qualities, and yield of animal and animal products. The dietary or oral supplementation of vitamin E is essential in reducing lipid oxidation in muscle, egg, and dairy products as well as lowering cholesterol concentrations and improving antioxidant status of livestock. Evidence has shown that bioavailability of vitamin E–enriched animal products could serve as an invaluable nutritional benefit to consumers; especially those in regions of limited resources where vitamin E deficiencies pose a risk that may be detrimental to some cellular activities of the body and on human health. It is therefore important to redirect research on the impact of vitamin E supplementation as antioxidant on livestock performance and animal products.     

Genetic relationships of soybean cyst nematode resistance originated in Gedenshirazu and PI84751 on Rhg1 and Rhg4 loci

Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is one of the most damaging pests of soybean (Glycine max (L.) Merr.). Host plant resistance has been the most effective control method. Because of the spread of multiple SCN races in Hokkaido, the Tokachi Agricultural Experiment Station has bred soybeans for SCN resistance since 1953 by using 2 main resistance resources PI84751 (resistant to races 1 and 3) and Gedenshirazu (resistant to race 3). In this study, we investigated the genetic relationships of SCN resistance originating from major SCN resistance genes in Gedenshirazu and PI84751 by using SSR markers. We confirmed that race 1 resistance in PI84751 was independently controlled by 4 genes, 2 of which were rhg1 and Rhg4. We classified the PI84751- type allele of Rhg1 as rhg1-s and the Gedenshirazu-type allele of Rhg1 as rhg1-g. In the cross of the Gedenshirazu-derived race 3-resistant lines and the PI84751-derived races 1- and 3-resistant lines, the presence of rhg1-s and Rhg4 was responsible for race 1-resistance. These results indicated that it was possible to select race 1 resistant plants by using marker-assisted selection for the rhg1-s and Rhg4 alleles through a PI84751 origin × Gedenshirazu origin cross.     

Characteristics of various fibrolytic isozyme activities in the rumen microbial communities of Japanese Black and Holstein Friesian cattle under different conditions

Rumen microorganisms produce various fibrolytic enzymes and degrade lignocellulosic materials into nutrient sources for ruminants; therefore, the characterization of fibrolytic enzymes contributing to the polysaccharide degradation in the rumen microbiota is important for efficient animal production. This study characterized the fibrolytic isozyme activities of a rumen microbiota from four groups of housed cattle (1, breeding Japanese Black; 2, feedlot Japanese Black; 3, lactating Holstein Friesian; 4, dry Holstein Friesian). Rumen fluids in all cattle groups showed similar concentrations of total volatile fatty acids and reducing sugars, whereas acetic acid contents and pH were different among them. Predominant genera were commonly detected in all cattle, although the bacterial compositions were different among cattle groups. Zymograms of whole proteins in rumen fluids showed endoglucanase activities at 55 and 57 kDa and xylanase activity at 44 kDa in all cattle. Meanwhile, several fibrolytic isozyme activities differed among cattle groups and individuals. Treponema, Succinivibrio, Anaeroplasma, Succiniclasticum, Ruminococcus, and Butyrivibrio showed positive correlations with fibrolytic isozyme activities. Further, endoglucanase activity at 68 kDa was positively correlated with pH. This study suggests the characteristics of fibrolytic isozyme activities and their correlations with the rumen microbiota.     

Pathogenicity of an isolate of infectious bursal disease virus in local Nigerian ducks

Summary Three to six-week old local Nigerian ducks were inoculated orally and intraocularly with an isolate of infectious bursal disease virus (IBDV) serotype 1 which was pathogenic for chickens. Neither clinical signs nor gross or microscopic lesions were observed. IBDV antigen was not detected in the bursa by the agar gel diffusion precipitation test. Precipitins and neutralising antibodies to IBDV were also not detected in the serum samples and IBDV was not isolated from the bursa, spleen and liver of the ducks. The above observations suggest that the ducks might be resistant to IBDV infection.

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Patogenicidad De Una Cepa Del Virus De La Enfermedad Infecciosa De La Bolsa En Patos Nigerianos Locales

Resumen Se inocularon patos nigerianos locales de tres a cuatro semanas de edad, vía oral, con una cepa del virus de la enfermedad infecciosa de la bolsa (EIVB), serotipo I, el cual fue patógeno en pollos. No se observaron sintomas clínicos ni lesiones microscópicas. No se detectó antígeno de EIVB en la bolsa, mediante la prueba de difusión precipitación en agar gelatina. No se detectaron anticuerpos neutralizantes, ni precipitinas de EIVB en las muestras de suero. EI virus no se aisló tampoco de la bolsa, bazo e hígado de los patos infectados. Estas observaciones sugieren que los patos pudieran ser resistentes a la EIVB.

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Pathogenicite D'un Isolat De Bursite Infectieuse Sur Des Canards Nigerians De Souche

Résumé Des canards nigérians de 3 à 6 semaines ont reçu, par injection orale et intraoculaire, un isolat du virus de la Bursite infectieuse (sérotype I), pathogène pour les poulets. Ni signes cliniques ni lésions macro ou microscopiques n'ont été observées. L'antigène viral de la Bursite infectieuse n'a pas été détecté dans les séreuses par le test de précipito—diffusion en agar. De même les précipitines et les anticorps neutralisants n'ont pas été isolés des séreuses, du foie et de la rate des canards. Ces observations montrent que les canards pourraient être résistants au virus de la Bursite infectieuse.

     

Development of PCR-based DNA marker for detection of white carrot contamination caused by Y2 locus

In carrot (Daucus carota L.), the taproot colors orange, yellow and white are determined mostly by the Y, Y2, and Or loci. One of the most severe issues in carrot seed production is contamination by wild white carrot. To evaluate the contamination ratio, easily detectable DNA markers for white carrot are desired. To develop PCR-based DNA markers for the Y2 locus, we have re-sequenced two orange-colored carrot cultivars at our company (Fujii Seed, Japan), as well as six white- and one light-orange-colored carrots that contaminated our seed products. Within the candidate region previously reported for the Y2 locus, only one DNA marker, Y2_7, clearly distinguished white carrots from orange ones in the re-sequenced samples. The Y2_7 marker was further examined in 12 of the most popular hybrid orange cultivars in Japan, as well as ‘Nantes’ and ‘Chantenay Red Cored 2’. The Y2_7 marker showed that all of the orange cultivars examined had the orange allele except for ‘Beta-441’. False white was detected in the orange-colored ‘Beta-441’. The Y2_7 marker detected white root carrot contamination in an old open-pollinated Japanese cultivar, ‘Nakamura Senkou Futo’. This marker would be a useful tool in a carrot seed quality control for some cultivars.     

Functional degeneration of the resistance gene nsv against Melon necrotic spot virus at low temperature

The single recessive gene, nsv, which confers resistance against Melon necrotic spot virus (MNSV), has recently been used to develop virus-resistant melon cultivars in Japan. However, the Chiba isolate of MNSV, a common isolate in Japan, infected resistant cultivars when inoculated melon plants were grown at 15°C. Viral RNAs accumulated in protoplasts from resistant cultivars at both 15 and 20°C. Mechanical inoculation of the cotyledons caused MNSV to spread throughout the leaves at 15°C, but not at 20°C. These results support our novel hypothesis that a temperature-sensitive inactivation of disease resistance genes occurs at the nsv locus in melon cultivars with the resistance gene grown at temperatures below 20°C. The first and second authors contributed equally to this research.     

Bacterial communities are more dependent on soil type than fertilizer type, but the reverse is true for fungal communities

The soil microbial community is strongly influenced by a wide variety of factors, such as soil characteristics and field management systems. In order to use biological indicators based on microbial community structure, it is very important to know whether or not these factors can be controlled. The present study aimed to determine whether soil type or fertilization has a greater influence on the soil microbial community based on denaturing gradient gel electrophoresis (DGGE) analysis of 12 experimental field plots containing four different soil types, Cumulic Andosol, Low-humic Andosol, Yellow Soil and Gray Lowland Soil, kept under three different fertilizer management systems since 2001 (the application of chemical fertilizer, the application of rice husk and cow manure, and the application of pig manure). Bacterial DGGE analysis using 16S rRNA genes and fungal DGGE analysis using 18S rRNA genes revealed that the bacterial community was related to the soil type more than the fertilization; however, the fungal community was related to the fertilization more than the soil type. These results might suggest that the fungal community is easier to control by fertilization than the bacterial community. Thus, we propose that indicators based on the fungal community might be more suitable as microbial indicators for soil quality.