Mapping of Sequence-Tagged Sites in Rice by Single Strand Conformation Polymorphism

The conditions for efficient single-strand conformation polymorphism(SSCP) detection were examined for its application to mappingof DNA regions in the rice genome. Temperature for electrophoresisand glycerol concentrations in gel affected SSCP patterns significantly.The optimal detection conditions for SSCP also depends on thenucleotide sequences of fragments analyzed. Fragments over 300bp show complicated patterns depending on their nucleotide sequencesand were not suitable for SSCP analysis. Seventy primer pairswere designed from the sequence data available to amplify DNAregions as sequence tagged sites (STSs), and 39 of these STSswere found to generate SSCP between japonica rice (Nipponbare)and indica rice (Kasalath) in at least one of the experimentalconditions. The maps of DNA fragments amplified from 186 F₂-plantDNAs with 17 primer pairs were successfully determined. Thisdirect mapping method of the amplified DNA fragments with PCRis simple and quite sensitive, and can be used to set markersin the gap regions of a genetic linkage map.     

Spectroscopic and ITC study of the conformational change upon Ca2+-binding in TnC C-lobe and TnI peptide complex from Akazara scallop striated muscle

Akazara scallop (Chlamys nipponensis akazara) troponin C (TnC) of striated adductor muscle binds only one Ca²⁺ ion at the C-terminal EF-hand motif (Site IV), but it works as the Ca²⁺-dependent regulator in adductor muscle contraction. In addition, the scallop troponin (Tn) has been thought to regulate muscle contraction via activating mechanisms that involve the region spanning from the TnC C-lobe (C-lobe) binding site to the inhibitory region of the TnI, and no alternative binding of the TnI C-terminal region to TnC because of no similarity between second TnC-binding regions of vertebrate and the scallop TnIs. To clarify the Ca²⁺-regulatory mechanism of muscle contraction by scallop Tn, we have analyzed the Ca²⁺-binding properties of the complex of TnC C-lobe and TnI peptide, and their interaction using isothermal titration microcalorimetry, nuclear magnetic resonance, circular dichroism, and gel filtration chromatography. The results showed that single Ca²⁺-binding to the Site IV leads to a structural transition not only in Site IV but also Site III through the structural network in the C-lobe of scallop TnC. We therefore assumed that the effect of Ca²⁺-binding must lead to a change in the interaction mode between the C-lobe of TnC and the TnI peptide. The change should be the first event of the transmission of Ca²⁺ signal to TnI in Tn ternary complex.     

Accumulation and leakage of abscisic acid during embryo development and seed dormancy in wheat

Seed dormancy develops latein embryogenesis after a period of potential prematuregermination and has been associated with levels ofabscisic acid (ABA) in, and sensitivity to, ABA ofembryos. In wheat (Triticum aestivum L.)embryos, there are two peaks in levels of ABA duringdevelopment: the first occurs 25 days afterpollination (DAP) and the second from 35 to 40 DAP. The first peak of ABA appears to be associated withthe development of the embryo's sensitivity to ABAsince such sensitivity was altered in seeds on earsthat were incubated in a solution of ABA from 15 and20 DAP. In the embryos of Kitakei wheat, a line thatexhibits dormancy, the second peak, at around 35 DAP,was more prolonged in comparison to Chihoku, anon-dormant line. The results support the proposedinvolvement of ABA in the formation and maintenance ofseed dormancy during middle and late embryogenesis. When developing embryos were incubated in water,embryonic ABA leaked out from the embryos, inparticular between 30 and 40 DAP. Prematuregermination observed between 30 and 40 DAP might berelated to such leakage of ABA from embryos.     

Rare seed-predating mammals determine seed fate of <Emphasis Type="Italic">Canarium euphyllum</Emphasis>, a large-seeded tree species in a moist evergreen forest,Thailand

Natural seed deposition patterns and their effects on post-dispersal seed fate are critical to tropical tree recruitment. The major dispersal agents of the large-seeded tree Canarium euphyllum in Khao Yai National Park, Thailand, are large frugivorous birds such as hornbills, which generated spatially heterogeneous seed deposition patterns because they regurgitated seeds at perching trees and conspecific and heterospecific feeding trees. We investigated the fate of seeds dispersed in this manner using seed removal experiments and automatic camera trapping. Seeds placed experimentally around conspecific feeding trees had higher removal rates than seeds placed elsewhere. These effects were likely mediated by two seed-eating rodents, the Indochinese ground squirrel (Menetes berdmorei) and the giant long-tailed rat (Leopoldamys sabanus). Consequently, the spatial patterns generated by hornbills had consequences for post-dispersal seed fates, particularly whether or not the seeds were removed by rodents. Primary dispersal by hornbills does alter seed fate by altering the probability of rodent–seed interaction, but the ultimate impact of dispersal by hornbills will depend on how important rodent scatterhoarding is to seed germination and seedlings. Given that major seed dispersers of C. euphyllum are now absent or rare in degraded forests in tropical Asia, it is becoming increasingly important to understand the roles of scatterhoarding rodents in these altered habitats in this region.     

Relationship of butterfly diversity with nectar plant species richness in and around the Aokigahara primary woodland of Mount Fuji,central Japan

We examined the relationships between the diversities of vegetation, adult nectar plants, and butterflies in and around the Aokigahara primary woodland on the northwestern footslopes of Mount Fuji, central Japan. The results showed that the nectar resource utilization by adult butterflies was significantly biased to herbaceous plants, especially to perennials, compared to woody species, although most of the study area was in and near a primary woodland. There were greater nectar plant species in sites with greater plant species richness. Among the butterfly community indices analyzed, the strongest correlation was detected between butterfly species richness and nectar plant species richness at each site. Another close correlation was detected between the species richness of nectar plants and herbaceous plants at each site. These results suggest that herbaceous plant species richness in a habitat plays a central role in its nectar plant species richness, and the nectar plant richness is a highly important factor supporting its adult butterfly species richness. Consequently, we propose that the maintenance and management of herbaceous plant species richness in a butterfly habitat, which lead to those of its nectar plant species richness, are very important for conservation of butterfly diversity even in and around woodland landscapes of temperate regions.     

Diet of Grauer's Gorillas in the Montane Forest of Kahuzi,Democratic Republic of Congo

We describe the diet of a semihabituated group of Grauer's gorillas (Gorilla beringei graueri) inhabiting the montane forest of Kahuzi-Biega National Park, Democratic Republic of Congo, based on direct observations, feeding remains in their fresh trails, and fecal samples collected over 9 yr. We examined fruit availability in their habitat; consumption of fruit, vegetative, and animal food; and daily intake of vegetative plant food using a transect, fruit monitoring trails, fecal analysis, and tracing of the animal's daily trails between consecutive nest sites. The fruit food repertoire of Kahuzi gorillas resembles that of western and eastern lowland gorillas inhabiting lowland tropical forests, while their vegetative food repertoire resembles that of mountain gorillas inhabiting montane forests. Among 236 plant foods (116 species), leaves, pith, and barks constitute the major parts (70.2%), with fruit making up the minor part (19.7%). About half (53.2%) of the total fecal samples included fruit remains. The gorillas used leaves, stems and other vegetative plant parts as staples. Their fruit intake was similar to that reported for mountain gorillas in Bwindi. They ate animal foods, including earthworms, on rare occasions. Variation in fruit consumption was positively associated with variation in fruit production. The gorillas ate fig fruits frequently; fig intake is positively correlated with that of other fruits, and figs were not fallback foods. They relied heavily on bamboo shoots on a seasonal basis; however, no bamboo shoots were available for several years after a major flowering event. Our results support the argument that variation in gorilla diets mostly reflects variation in vegetational composition of their habitats.     

Tricalysiosides H-O: Ent-kaurane glucosides from the leaves of Tricalysia dubia

Eight ent-kaurane glucosides, named tricalysiosides H-O, were isolated from Tricalysia dubia. Tricalysioside H possessed a hydroxyl group at the 1-position, to which the glucose moiety was attached. The structure was first elucidated by means of spectroscopic data analysis and finally confirmed by X-ray crystallography. Since acid hydrolysis of 1 gave D-glucose, the aglycone was proved to have an enantio-kaurane type skeleton. The structures of tricalysiosides I-O were mainly elucidated from analysis of spectroscopic evidence.     

Limited ability of antigen-specific Th1 responses to inhibit Th2 cell development in vivo

Th1 and Th2 cells mutually antagonize each other's differentiation. Consequently, allergen-specific Th1 cells are believed to be able to suppress the development of Th2 cells and to prevent the development of atopic disorders. To determine whether a pre-existing Ag-specific Th1 response can affect the development of Th2 cells in vivo, we used an immunization model of Ag-pulsed murine dendritic cell (DC) transfer to induce distinct Th responses. When transferred into naive mice, Ag-pulsed CD8alpha(+) DCs induced a Th1 response and the production of IgG2a, whereas CD8alpha(-) DCs primed a Th2 response and the production of IgE. In the presence of a pre-existing Ag-specific Th2 environment due to Ag-pulsed CD8alpha(-) DC transfer, CD8alpha(+) DCs failed to prime Th1 cells. In contrast, CD8alpha(-) DCs could prime a Th2 response in the presence of a pre-existing Ag-specific Th1 environment. Moreover, exogenous IL-4 abolished the Th1-inducing potential of CD8alpha(+) DCs in vitro, but the addition of IFN-gamma did not effectively inhibit the potential of CD8alpha(-) DCs to prime IL-4-producing cells. Thus, Th1 and Th2 cells differ in their potential to inhibit the development of the other. This suggests that the early induction of allergen-specific Th1 cells before allergy sensitization will not prevent the development of atopic disorders.     

Heat stability of carboxypeptidase R of experimental animals

Carboxypeptidase N (CPN) and carboxypeptidase R (CPR) are present in fresh serum, and cleave C-terminal arginine or lysine residues from bioactive peptides such as anaphylatoxins and kinins resulting in regulation of peptide activity. Although CPN is present in the active form in plasma, CPR is generated from proCPR by trypsin-like enzymes such as thrombin. CPR regulates not only inflammatory peptides but also restricts fibrinolysis. To elucidate the complex role of CPN and CPR in vivo, studies in animal models will be essential. CPR of guinea pig, rat and rabbit decayed at 37 C rapidly as in the case of human CPR. However, at 25 C, CPR of those species decayed to some extent, although human serum CPR did not decay within 60 min. In the presence of thrombin inhibitor, CPR in the sera of animals tested decayed more rapidly than CPR in serum without thrombin inhibitor suggesting that additional generation of CPR may have been prevented during decay evaluation. However, human serum CPR decayed more rapidly in the absence of thrombin inhibitor indicating that thrombin may accelerate the decay in human serum.     

Resource use of insect seed predators during general flowering and seeding events in a Bornean dipterocarp rain forest

Insect seed predators of 24 dipterocarp species (including the genera ot Dipterocarpus, Dryobalanops and Shorea) and five species belonging to the Moraceae, Myrtaceae, Celastraceae and Sapotaceae were investigated. In a tropical lowland dipterocarp forest in Sarawak, Malaysia, these trees produces seeds irregularly by intensely during general flowering and seeding events in 1996 and/or 1998. Dipterocarp seeds were preyed on by 51 insect species (11 families), which were roughly classified into three taxonomic groups: smaller moths (Trotricidae, Pyralidae, Crambidae, Immidae, Sesiidae, and Cosmopterigidae), scolytids (Scolydae) and weevils (Curdulionidae, Apionidae, Anthribidae, and Attelabidae). Although the host-specificity of invertebrate seed predators has been assumed to be high in tropical forests, it was found that the diet ranges of some insect predators were relatively wide and overlapped one another. Most seed predators that were collected in both study years changes their diets between general flowering and seeding events. The results of cluster analyses based on the number of adult of each predator species that emerged from 100 seeds of each tree species, suggested that the dominant species was not consistent, alternating between the two years.