Structural Changes of Goat Parotid Salivary Gland: Pre‐ and Post‐Weaning Periods

Previously, the structure of the adult goat parotid salivary glands (PGs) was studied. However, little information was elucidated of the juvenile ones. This study aimed to clarify the correlations between the structure of goats' PGs and the nature of food intake among milk‐suckling kids (MSKs) and diet‐fed goats (DFGs). The secretory endpieces of the goats' PGs are of the pure serous type. The serous cells in MSKs showed apical accumulation of numerous secretory granules (SGs) of smaller size and of more intense positive periodic acid‐Schiff reaction. Ultrastructurally, most of the SGs in the DFGs contained peripherally located inclusions that showed dense reaction products for acid phosphatase. In MSKs, the PGs showed less‐developed basal infoldings, sparseness of the inter‐cellular inter‐digitations, fewer inter‐cellular canaliculi and microvilli and also less‐developed myoepithelial cells with fewer and shorter cytoplasmic processes. In conclusion, the less‐developed membrane specializations and myoepithelial cells, as well as the accumulated SGs in the PGs of MSKs, suggest that it secretes less saliva with a little secretory activity than that of DFGs, which may be correlated with the reduced masticatory activity.     

Land tenure and farm management efficiency: The case of smallholder rubber production in customary land areas of Sumatra

This study assesses the impact of land tenure institutions on the efficiency of farm management based on a case study of rubber production in customary land areas of Sumatra, Indonesia. Using the modes of land acquisition as measures of land tenure institutions, we estimated tree planting, revenue, income, and short-run profit functions, and internal rates of return to tree planting on smallholder rubber fields. We find generally insignificant differences in the incidence of tree planting and management efficiency (defined as residual profits) of rubber production between newly emerging private ownership and customary ownership. This is consistent with our hypothesis that tree planting confers stronger individual rights, if land rights are initially weak (as in the case of family land under customary land tenure systems). On the other hand, short-term profits are higher on land that is rented through share tenancy. This result indicates that rubber trees are over-exploited under renting arrangements due partly to the short-run nature of the land tenancy contracts and partly to the difficulty landowners face in supervising tapping activities of tenants in spatially dispersed rubber fields. This revised version was published online in June 2006 with corrections to the Cover Date.     

Characterisation of starch properties and physical characteristics in buckwheat (Fagopyrum esculentum Moench.) mutant lacking accumulation of ‘granule-bound starch synthase a’

The concentration of amylose, which is synthesised using granule-bound starch synthase, affects the physical properties of food. However, no studies have focused on starch properties and physical characteristics of low-amylose buckwheat. Here, we hypothesised that low-amylose buckwheat would be useful to produce new buckwheat products because low-amylose characteristics change the texture of buckwheat food. In this study, we bred relatively low-amylose buckwheat compared to wild type and investigated the causative genes of the traits, starch properties and physical properties of noodles. In the GBSSa mutant, the amylose concentration was lower than that in the wild type. Compared with the wild type, the mutant exhibited the following traits: Amylose concentration decreased by approximately 2%, setback in the Rapid Visco Analyzer decreased by 30 points and the physical characteristics of noodles in the sensory analysis were soft and sticky. These results suggest that this trait may be useful for changing the texture of foods. In addition, the mutant is promising for producing new foods with physical characteristics that are different from those of the wild type.     

Temporal shifts in diversity and quantity of nirS and nirK in a rice paddy field soil

Denitrification is an important part of the nitrogen cycle in the environment, and diverse bacteria, archaea, and fungi are known to have denitrifying ability. Rice paddy field soils have been known to have strong denitrifying activity, but the microbes responsible for denitrification in rice paddy field soils are not well known. Present study analyzed the diversity and quantity of the nitrite reductase genes (nirS and nirK) in a rice paddy field soil, sampled four times in one rice-growing season. Clone library analyses suggested that the denitrifier community composition varied over sampling time. Although many clones were distantly related to the known NirS or NirK, some clones were related to the NirS from Burkholderiales and Rhodocyclales bacteria, and some were related to the NirK from Rhizobiales bacteria. These denitrifiers may play an important role in denitrification in the rice paddy field soil. The quantitative PCR results showed that nirK was more abundant than nirS in all soil samples, but the nirK/nirS ratio decreased after water logging. These results suggest that both diversity and quantity changed over time in the rice paddy field soil, in response to the soil condition.     

Food-drug interaction between ferulic acid and nateglinide involving the fluorescein/H+ cotransport system

In clinical, patients usually take many kinds of drugs at the same time. Thus, drug-drug interactions involving transporters can often directly affect the therapeutic safety and efficacy of many drugs. However, there have been few studies on food-drug interactions involving transporters. Dietary polyphenols have been widely assumed to be beneficial to human health. Polyphenols are commercially prepared and used as functional foods. We report here for the first time that ferulic acid, which is widely used as a functional food, affects the transport of clinical agents. It is important to be aware of the potential of food-drug interactions and to act in order to prevent undesirable and harmful clinical consequences.     

Influences of indigenous phototrophs on methane emissions from a straw-amended paddy soil

A pot experiment was conducted to investigate the influences of indigenous phototrophs on methane (CH₄) emissions from a paddy soil where rice straw was incorporated or was surface-applied. During the cultivation, half of the pots were covered with aluminum foil, except for the minimum space for rice plants, to prevent ambient light reaching the floodwater or the soil surface. Growth of oxygen-producing phototrophs was hardly observed in the unilluminated plots, whereas intensive growth of algae, duckweed and hydrophytes was found in the illuminated ones. Plant growth was not affected by the different treatments. Seasonal changes in CH₄ emission determined by a closed chamber method indicated that illumination had no or only minor effects on CH₄ emissions when rice straw was incorporated or was not applied, but significantly reduced CH₄ emissions when rice straw was surface-applied. Methanogenesis occurring in the soil-floodwater interface was further investigated in two lab-scale model experiments measuring methanogenic activity. As a result, more activated methanogenesis was found in the surface-applied rice straw and the soil around the straw compared with the soil incubated without rice straw. The magnitude of the methanogenic activity in the rice straw incubated under illuminated conditions was significantly lower than that incubated in the dark. Consequently, this study demonstrates that methanogenesis in paddy soil occurs even in the soil-floodwater interface if plant residues like rice straw exist, and such methanogenesis is likely to be suppressed by growth of indigenous phototrophs under illumination.     

Effects of Inoculation of Phototrophic Purple Bacteria on Grain Yield of Rice and Nitrogenase Activity of Paddy Soil in a Pot Experiment

Phototrophic purple bacteria (PPB) are one group of dinitrogen (N₂)-fixing bacteria often found in the anoxic and photic zone of paddy soil. In the present study, the effects of inoculation of PPB on grain yield of rice and changes in their populations and nitrogenase activity were investigated with and without surface application of rice straw in a pot experiment. As an inoculant, Rhodopseudomonas palustris strain KN122 isolated from a paddy soil was selected, and the cell suspension was inoculated into the floodwater once or three times during the cultivation. As a result, the inoculation of PPB increased the grain yield of rice. Compared to the control, the grain yield was 9% higher in the inoculated plot without rice straw application. The treatment was more effective in combination with rice straw application. In the plots where PPB were inoculated with rice straw, grain yields were 21% (single inoculation) and 29% (triple inoculation) higher. Populations of PPB in the plots without rice straw application significantly increased by the inoculation, unlike those in the plots with rice straw application, except for the bulk soil. Phototrophic and heterotrophic nitrogenase activities (acetylene-reducing activity) associated with the soils or residues of the rice straw were not affected by PPB inoculation throughout the experiment. This indicates that the inoculation of PPB into floodwater may not be effective for enhancing N₂ fixation in paddy soils and that the beneficial effect of PPB inoculation on the grain yield of rice may be due to unidentified functions of PPB other than biological N₂ fixation.