In isolated DNA, formamidopyrimidine-DNA glycosylase-sensitive sites determined by electrophoresis correspond to the amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine by HPLC-ECD.

Several methods have been developed for determining the amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in DNA. In the present study, we compared an electrophoretic method that uses formamidopyrimidine-DNA glycosylase (FPG protein) with a HPLC-ECD method. Firstly, we produced 8-oxodG in lambda DNA with methylene blue and visible light and cleaved it in one-half of the modified DNA enzymatically with FPG protein. Then, we determined the number of FPG protein-sensitive sites by electrophoresis (Y) and the number of 8-oxodGs by HPLC-ECD (X) per 10(5)dG of isolated DNA. Simple regression analysis of the data showed Y=1.07X+1.52 to be the most likely relationship. The correlation coefficient was 0.97. The values obtained by the two methods were very similar. This result is noteworthy because the number of FPG protein-sensitive sites determined by other methods have not yet come close to the number obtained by HPLC-ECD. Thus, this method might be more quantitative than other methods that measure FPG protein-sensitive sites. Another reason this electrophoresis method might be more useful than HPLC-ECD is that we can determine some other types of oxidative DNA damage well, by changing the DNA glycosylase.     

Effects of aging on bone mineral content and bone biomarkers in female cynomolgus monkeys.

Age-related changes in bone mineral content and bone biomarkers were assessed over the complete lifespan of female cynomolgus monkeys. The bone mass of the lumbar spine increased linearly from birth to about 2.5 years of age, and this increase gradually slowed thereafter until a peak bone mass was achieved at 9 years of age. The bone mass stabilized after 9 years of age, showing no sign of further reduction with age. In contrast with the significant increase in bone mass before 2.5 years of age, significant decreases occurred in the serum concentrations of the following bone formation markers: intact osteocalcin, bone-specific alkaline phosphatase and amino-terminal propeptide of type I procollagen, but the serum concentration of carboxy-terminal propeptide of type I procollagen did not change significantly throughout the entire lifespan. Concerning the bone resorption markers, the levels of tartrate-resistant acid phosphatase fluctuated throughout the entire lifespan. The skeleton of an aging female monkey undergoes changes similar to those observed in senescent humans, but did not undergo the menopausal changes seen in women. The use of female cynomolgus monkeys to model human skeletal interventions should therefore be undertaken with consideration of the similarities and differences between cynomolgus monkeys and humans.     

DOMOIC ACID PRODUCTION IN NITZSCHIA SP. (BACILLARIOPHYCEAE) ISOLATED FROM A SHRIMP-CULTURE POND IN DO SON, VIETNAM

Domoic acid (DA), a neuroexcitatory amino acid, was detected in batch culture of the newly recognized species Nitzschia navis-varingica Lundholm et Moestrup . The production of DA by this diatom was confirmed by electrospray ionization mass spectrometry. The diatom was collected from a shrimp-culture pond in Do Son, Vietnam. The production of DA (1.7 pg·cell ^{− 1}) is within the levels reported for Pseudo-nitzschia multiseries (Hasle) Hasle. The DA production started during the late exponential growth phase and reached a maximum during the early stationary growth phase. Maximum DA levels in the axenic culture decreased to about half that of the nonaxenic culture (0.9 pg·cell ^{− 1} vs. 1.7 pg·cell ^{− 1}), suggesting that DA production by the new species is influenced by bacteria.     

Effects of reserpine and adenosine agonist on α2-adrenergic receptor of rat vas deferens examined with [3H]yohimbine and [3H]clonidine

The changes of [³H]yohimbine and [³H]clonidine binding sites in rat vas deferens on treatments with adenosine receptor agonists (2-chloroadenosine, adenosine) or reserpine were examined. Treatment with adenosine agonist in vitro increased [³H]clonidine binding sites but had no influence on affinity and number of binding sites of α₂-antagonist, [³H]yohimbine. Amount of [³H]yohimbine binding sites was found to be higher than that of [³H]clonidine with or without the treatment. Inhibition curves of α₂-agonists, clonidine and norepinephrine, on [³H]yohimbine binding were less than unity though α₂-antagonist inhibited with about 1.0 of n_H. The treatment with adenosine agonist reduced the IC₅₀ value of agonists on the [³H]yohimbine binding but had no influence on the inhibitory effect of antagonist. These effect of adenosine agonists was completely blocked by theophylline. Accordingly it was considered that activation of adenosine receptor caused configurational change in α₂-adrenergic receptor from low affinity state for agonist to the high affinity state, though both states had same affinity for antagonist.On the other hand, treatment with reserpine in vivo increased the affinity of clonidine for α₂-adrenergic receptors and also increased the amount of the α₂-receptors.     

Structure and property of self-assemble valinyl bolaform amides having different chirality.

Bolaform amides were designed from N,N'-bis(carboethoxy-L-valinyl)-diaminoethane (1) by linking t-butyloxycarbonyl-valine through ethylenediamine (EDA) to enable spectroscopic and X-ray diffraction analyses. N,N'-Bis(Boc-L-valinyl)-diaminoethane (2) and N,N'-bis(Boc-D-valinyl)-diaminoethane (3) were composed of L-Val and D-Val, respectively. N-(Boc-L-valinyl)-N'-(Boc-D-valinyl)-diaminoethane (4) was composed of both L-Val and D-Val, and was achiral (meso-peptide). Peptide 5 was a 1:1 mixture of 2 and 3, and was also achiral (racemate). These peptides mediated gelation of corn oil at a concentration of approximately 1%. Within crystals, the peptides formed beta-sheet ribbons, but differences were observed in hydrogen-bonding patterns and side-chain arrangements. These differences were also deduced from temperature dependence of amide protons. Force-field calculations based on the crystal structures indicated that association of beta-sheet ribbons had energy benefits, and it was assumed that molecular aggregation progressed spontaneously. These structural studies indicated the chirality of amino acids affected for the properties of bolaform amides.     

SAPK/JNK plays a role in transforming growth factor-beta-induced VEGF synthesis in osteoblasts.

We previously reported that transforming growth factor-beta (TGF-beta) activates p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase, resulting in the stimulation of vascular endothelial growth factor (VEGF) synthesis in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the involvement of stress-activated protein kinase/c- Jun N-terminal kinase (SAPK/JNK), another member of the MAP kinase superfamily, in TGF-beta-induced VEGF synthesis in these cells. TGF-beta markedly induced SAPK/JNK phosphorylation. SP600125, a specific inhibitor of SAPK/JNK, markedly reduced TGF-beta-induced VEGF synthesis. SP600125 suppressed TGF-beta-induced SAPK/JNK phosphorylation. PD98059, an inhibitor of upstream kinase of p44/p42 MAP kinase and SB203580, an inhibitor of p38 MAP kinase, each failed to reduce TGF-beta-induced SAPK/JNK phosphorylation. A combination of SP600125 and PD98059 or SP600125 and SB203580 suppressed TGF-beta-stimulated VEGF synthesis in an additive manner. These results strongly suggest that TGF-beta activates SAPK/JNK in osteoblasts, and that SAPK/JNK plays a role in addition to p42/p44 MAP kinase and p38 MAP kinase in TGF-beta-induced VEGF synthesis.     

Recent advances in ecological stoichiometry: insights for population and community ecology

Conventional theories of population and community dynamics are based on a single currency such as number of individuals, biomass, carbon or energy. However, organisms are constructed of multiple elements and often require them (in particular carbon, phosphorus and nitrogen) in different ratios than provided by their resources; this mismatch may constrain the net transfer of energy and elements through trophic levels. Ecological stoichiometry, the study of the balance of elements in ecological processes, offers a framework for exploring ecological effects of such constraints. We review recent theoretical and empirical studies that have considered how stoichiometry may affect population and community dynamics. These studies show that stoichiometric constraints can affect several properties of populations (e.g. stability, oscillations, consumer extinction) and communities (e.g. coexistence of competitors, competitive interactions between different guilds). We highlight gaps in general knowledge and focus on areas of population and community ecology where incorporation of stoichiometric constraints may be particularly fruitful, such as studies of demographic bottlenecks, spatial processes, and multi-species interactions. Finally, we suggest promising directions for new research by recommending potential study systems (terrestrial insects, detritivory-based webs, soil communities) to improve our understanding of populations and communities. Our conclusion is that a better integration of stoichiometric principles and other theoretical approaches in ecology may allow for a richer understanding of both population and community structure and dynamics.