The Knobbed mutant of the silkworm, Bombyx mori, is a dermal mutant characterized as having paired knobs in specific regions of larval segments. To clarify the knob formation mechanisms, the epidermal cell proliferation and morphology of the knobbed region during the fourth instar were investigated. Mitosis of the epidermis in the non-knobbed region was mainly observed to occur at 48 hours (h) after ecdysis. Conversely, numerous mitotic cells were observed in the knobbed region not only at 48 h but also 24 h after ecdysis. Mitotic cells were also observed at 72 h after ecdysis. According to observation using the transmission electron microscope, epidermal cells at the knobbed region were considerably longer and more slender than those of the non-knobbed region. The unusual shape of the epidermal cells in the knobbed region appeared attributable to abnormally prolonged mitotic activity. In this paper, based on these morphological observations, the process of knob formation was discussed.

View full abstract

To learn how to regulate carotenoid content in citrus fruit, we studied the mechanism of carotenoid accumulation using physiological and genetic methods. Based on differences in the carotenoid profiles of flavedo and juice sacs, citrus species could be roughly divided into three groups: carotenoid-poor, violaxanthin-abundant, and β-cryptoxanthin-abundant groups. A comparison of the gene expression among several citrus species with different carotenoid profiles showed that the difference in carotenoid profiles among citrus species was highly regulated by coordination of the expression for genes related to carotenoid biosynthesis and catabolism. Quantitative trait loci related to carotenoid content were also identified to select progeny with high carotenoid content. Moreover, we showed that the effect of postharvest ethylene on carotenoid accumulation in flavedo varied with temperature. Under an ethylene atmosphere, in flavedo, carotenoid accumulation was enhanced more dramatically than under an ethylene-free atmosphere at 20°C but repressed at 5°C.

View full abstract

Land plants respond to cold through complicated physiological, morphological, and metabolic processes, including abnormalities and changes in organelles, while plant mitochondrial gene expressions are regulated through several unique post-transcriptional events, such as cis-/trans-intron splicing and RNA editing. The author tries to clarify the relationship between these post-transcriptional events at low temperatures. Some intron-containing transcripts before splicing increase in rice and wheat after several days under cold conditions, while certain RNA editing events in IBS (Intron Binding Sites: which is present in exons and make complementary base pairing with Exon Binding Sites located in introns) have tight associations with splicing, some of which are sensitive to cold in intron-containing transcripts. However no correlation is observed between post-transcriptional events and the organization of introns: the primary sequence of introns, splicing manner (cis or trans), intron length, and splice-site sequence. These findings suggest that nucleus-encoded factors regulate mitochondrial gene expressions, some of which are cold-sensitive. In wheat, a cold acclimatable plant, accumulation of some intron-spliced transcripts also increase at low temperatures, as well as intron-containing transcripts, which may be one of the phenomena related to cold acclimation. The study about plant mitochondrial gene expression at low temperatures has the potential to become an alternative system to see how mitochondrial genes are regulated, which, in turn, has the potential to enhance plant breeding for cold tolerance.

View full abstract

Calcium is involved in several disorders and influences the storage life of different fruit species. Moreover, applying preharvest foliar Ca spray is a standard practice to control fruit Ca concentration in certain deciduous fruit trees. Conversely, the effects of foliar Ca spray on the Ca concentration in fruit and the incidence of disorder are sometimes inconsistent. This article provides an overview of recent works on foliar Ca application and discusses Ca application inconsistencies. Foliar Ca sprays reduced bitter pit, enhanced fruit firmness and storage time, and sometimes reduced the incidence of brown rot during storage in apples; reduced internal browning during storage and the incidence of brown rot in peaches; decreased postharvest decay and cork spot in pears; and increased shelf life in grapes. Experiments using ⁴⁵Ca or isolated cuticular revealed the effects of fruit growth stages, atmospheric conditions, and adjuvants on Ca penetration. Finally, three possible reasons for inconsistencies of foliar Ca application are discussed.

View full abstract

Torymus sinensis is a parasitoid wasp that was introduced from China to Japan to control the invasive chestnut gall wasp Dryocosmus kuriphilus. Interaction between T. sinensis and the indigenous parasitoid T. beneficus has been of interest since T. sinensis was first released in chestnut orchards, as hybridization between them might impede the success of biological control by the introduced parasitoid. Such apprehensions disappeared with the drastic decrease in damage caused by D. kuriphilus. However, the emergence of morphologically intermediate individuals between them after the introduction of the parasitoid has triggered renewed interest in hybridization, specifically on the non-target effects of biological control. In this review, the interaction between both species, specifically hybridization, species composition and species displacement, is surveyed. Molecular markers are used, not only because T. sinensis and T. beneficus are similar morphologically, but also because the latter has two emergence strains (early- and late-spring). Surveys show that 1) T. sinensis has displaced both emergence strains of T. beneficus; 2) hybridization between T. sinensis and early-spring T. beneficus occurs at a low frequency (≤ 1%); but that 3), hybrid F₁s between T. sinensis and late-spring T. beneficus occur at a much higher frequency (≤ 20%). A study of phylogenetic relationships indicates that the late-spring T. beneficus is closer to the different species T. sinensis than the early-spring T. beneficus. This can partly explain why T. sinensis hybridizes more readily with the late-spring T. beneficus than with the early-spring T. beneficus.

View full abstract

A simple and highly sensitive assay method for α-glucosidase inhibitory activity was devised and a microplate method using absorbance at 450 nm for angiotensin-converting enzyme activity was introduced. Successful examples using these methods are shown, in which active components from Chinese traditional fermented foods and Mongolian fermented milk products were identified. These traditional fermented foods are expected to elicit effective components against lifestyle-related diseases.

View full abstract

Rice flour is used to make various traditional foods and also increasingly as a substitute for wheat flour. To explore rice suitable for milling, the properties of grain and flour in floury rice mutants were investigated. Floury rice mutants commonly show loosely packed starch granules in the endosperm, which results in decreased grain hardness. The starch and amylose content of some floury mutant lines declined slightly compared to the wild-type. In wild-type rice, fine flour with low starch damage is obtained when jet-milled under wet condition; while flour which is pin-milled under dry conditions is coarser and more damaged compared to jet-milled flour. Rice flour prepared from floury mutant lines shows low starch damage and fine particle size, in both jet- or pin-milling. The differences in grain components, starch damage and particle size would lead to a characteristic RVA profile. In some mutant lines, the specific loaf volume (SLV) of rice bread made from pin-milled floury mutant rice is reportedly equivalent to that made from the jet-milled wild-type. The dry-milling process needs none of the excess water treatment required in wet-milling. Therefore, using floury mutant lines and the pin-mill, industrial production of rice flour suitable for high-SLV rice bread would be easier.

View full abstract

Flesh texture of peach (Prunus persica Batsch) was classified into melting and non-melting, while in 1976, the stony hard variety was reported as a third type. However, the fruit ripening characteristics and inheritance of stony hard trait remained unclear. The fruit of melting and non-melting cultivars showed increased ethylene production and softer flesh, although their degrees differed. Conversely, the stony hard texture was characterized by the absence of both ethylene production and postharvest softening in mature fruit, while the firmness of the stony hard peach decreased effectively with continuous ethylene treatment. Treatment of the stony hard peach with 1-aminocyclopropane-1-carboxylic acid (ACC), which is the immediate precursor to ethylene, softened the fruit and rapidly induced ethylene production. The genetic separation of the flesh texture characteristics in F₁ and F₂ offspring from the cross of non-melting and stony hard cultivars indicated that the stony hard trait was controlled by a single gene, and inherited independently of melting flesh/non-melting flesh traits. The stony hard peach is expected to be used as a genetic source to enhance the preservability of the table peach.

View full abstract

In this study, the relationship between the predation of weed seed by crickets and the distance from the edge of paddy fields after the irrigation water receded was investigated. In September 2011, the activity density of crickets and invertebrate seed predation were investigated twice in a paddy field at distances of 0, 5, 10, and 15 m from the field edge, and on a paddy levee. The activity density of all cricket species in the field was 2.8-4.6 individuals/trap/day (first trial) and 2.4-6.0 individuals/trap/day (second trial), with no significant difference in activity density between the examined distances from the field edge. However, the cricket species differed in their spatial distribution. The activity density of Teleogryllus emma peaked at 5 m from the field edge, whereas that of Velarifictorus micado peaked 15 m from the edge. In contrast, the activity density of Loxoblemmus spp., including L. campestris, was higher on the paddy levee than in the field. The proportion of invertebrate seed predation on Echinochloa crus-galli var. crus-galli (23.9-40.9%/day) and Lolium multiflorum (81.0-98.8%/day) did not differ significantly between the examined distances from the field edge. Camera recordings showed crickets to be the predominant invertebrate seed predators. These results suggest that crickets can help deplete weed seed banks over a large portion of paddy fields.

View full abstract

It is important to use food waste as organic fertilizer because considerable energy is needed to produce inorganic fertilizer, while most food waste is burned and landfilled. Recently, a groundbreaking method, organic hydroponics, has been developed, which enables the cultivation of vegetables by directly adding organic fertilizers to the hydroponic solution. Organic fertilizer is degraded to mineral nutrients by a microbial method, multiple parallel mineralization, involving concurrent ammonification and nitrification reactions. Previous studies have shown vegetables thriving when raised on liquid organic fertilizers via organic hydroponics. However, cultivation using solid organic fertilizers has yet to be examined. In this study, we examined the feasibility of using solid food waste generated from a shopping center as a fertilizer for organic hydroponics. We confirmed nitrate ion generation from the food waste by multiple parallel mineralization. Using solid organic matter and the anaerobic conditions at the bottom of a rectangular container might stimulate denitrification. We improved the retrieval rate of inorganic nitrogen ions by filtrating the solution with a nonwoven fabric bag to remove undegraded organic matter and successfully cultivated butterhead lettuce using the food waste as fertilizer in the hydroponics. The results provided a methodological basis for a new effective means of recycling food waste.

View full abstract

A decade after the introduction of the DOI MOI policy and agricultural reform, Vietnam was positioned as the world′s second largest rice exporter, whereas rice farming itself became a grim business. The government relaxed their egalitarian land allocation policy and encouraged diversification from rice monoculture. The land price had soared in 2000 and the 2003 land law stipulated measures to prevent land speculation. The objective of the research is to identify the effect of land speculation on the structural change in agriculture in the Mekong delta between 1997 and 2002. A follow-up census of an ex-hamlet was undertaken in Can Tho (current Hau Giang) province in 2002. Data from households were stratified by land size and compared with those studied from 1993 to 1997. Branched-out households had multiplied, probably due to the appreciation in land prices. Households were differentiated at around 1 ha subject to their competencies in rice production. Diversification from rice monoculture emerged as another factor differentiating farmers at around 2ha. A ceiling in yield due to land fragmentation and expectations of the agricultural land as an appreciating asset could have affected the farmers′ decision at around 3 ha whether to emigrate from or remain in the hamlet.

View full abstract

We surveyed the rates of internal infection of swine with gastrointestinal tract protozoa by checking the stools of 334 pigs (suckling pigs, growing pigs aged 1 to 6 months and sows or sow candidates) on 8 hog farms in Saitama, Japan from September to November 2009. Oocysts and cysts per gram of stools in all pigs were calculated. Parasite detection rates were statistically analyzed for each of the farms, age groups, and stool condition scores, and the relationship between parasitic infection and diarrhea was investigated. Cryptosporidium was detected in 79 pigs (23.7%) of all pigs checked, Giardia was found in 53 (15.9%), Balantidium in 155 (46.4%), and coccidium in 20 (6.0%). The rate of Cryptosporidium infection was higher in the 2- and 3-month-old groups (55.6 to 60.0%) than in the others (2.5 to 27.6%) (P < 0.05): oocysts per gram of stools of 10⁴ to 10⁵ were detected in a total of 33 suckling pigs and 2- and 3-month-old pigs, including 10 of an outdoor farm. There was a correlation between the infection rate and diarrhea in five piglets aged 1 month or younger. In addition, the number of 6-month-old pigs infected with Giardia was 40.0%, as opposed to just 5.1% (P < 0.05) of suckling pigs. Detection rates differed among farms. The Balantidium infection rate was high in pigs older than 4 months (45.0 to 78.9%), as opposed to 15.4 to 17.2% (P < 0.05) in pigs younger than 1 month.

View full abstract

To develop silvicultural methods for dipterocarp species in degraded lands in a tropical monsoon climate, we examined uneven-aged forest management, in which dipterocarp trees were planted under nurse trees, by monitoring their growth for 20 years. In 1989, seedlings of four dipterocarp species (Dipterocarpus alatus, D. turbinatus, Hopea odorata and Shorea henryana) were planted beneath a 3-year-old Leucaena leucocephala plantation and in an open site in Sakaerat, north-east Thailand. The survival rate and tree size of the dipterocarp seedlings were monitored at both sites until 1995. Surand svival rates of the dipterocarp trees were significantly better under the Leucaena plantation. However, no apparent difference was observed in basal area between both sites, since saw vigorous growth of the surviving seedlings compensated for the loss of dead seedlings at the open site. Our results showed that D. alatus and H. odorata could be planted in an open site due to the vigorous growth of the seedlings, but that it was preferable to plant D. turbinatus beneath nurse trees. The Leucaena plantation was partially thinned to 50, 75 and 100% (clear-cut) in 1993, and the survival rate and growth of the dipterocarps was monitored until 2009. Thinning had no apparent effect on the survival rates of the dipterocarp seedlings. Although relative growth rates (RGR) of the dipterocarps reduced after thinning, thinning rates did not affect the growth of the dipterocarps. After thinning, dipterocarp trees overtook Leucaena in height at all thinning rates, possibly from 1999. An uneven-aged system combining Leucaena and dipterocarp trees is likely to be applicable to several dipterocarp species.

View full abstract