Effects of morphine andd-Ala2-d-Leu5-enkephalin in the seizure-susceptible El mouse

Opioid agonists were used to investigate the modulation of seizures in the seizure-susceptible El mouse. Morphine andd-Ala²-d-Leu⁵-enkephalin (DADLE) were injected subcutaneously or intracisternally as prototypic agonists for and opioid receptors. Systemic or intracisternal injection of both morphine and DADLE decreased the incidence of seizures and the seizure score in El mice in a dose-dependent manner. The anticonvulsant effects of morphine and DADLE were reversed by naloxone (2 mg/kg, s.c.). This implies that opioid agonists have anticonvulsant properties which are mediated by and opioid receptors. In conclusion, a deficit in endogenous opioid peptides, which act as anticonvulsants may play a significant role in the etiology or pathophysiology of seizures in the El mouse.     

Taxol derivatives are selective inhibitors of DNA polymerase alpha

During screening for mammalian DNA polymerase inhibitors, we found and succeeded in isolating a potent inhibitor from a higher plant, Taxus cuspidate. The compound was unexpectedly determined to be taxinine, an intermediate of paclitaxel (taxol) metabolism. Taxinine was found to selectively inhibit DNA polymerase alpha (pol.alpha) and beta (pol.beta). We therefore, tested taxol and other derivatives and found that taxol itself had no such inhibitory effect, and only taxinine could inhibit both pol.alpha and beta. The other compounds used, one derivative, cephalomannine, and five intermediates synthesized chemically inhibited only the pol.alpha activity in vitro. None of the compounds, including taxinine, influenced the activities of the other DNA polymerases, which are reportedly targeted by many pol.beta inhibitors. With both pol.alpha and beta, all of the compounds tested noncompetitively inhibited with respect to both the DNA template-primer and the dNTP substrate.     

Molecular characterization of human UDP-glucuronic acid/UDP-N-acetylgalactosamine transporter, a novel nucleotide sugar transporter with dual substrate specificity

A novel human nucleotide sugar transporter (NST) which transports both UDP-glucuronic acid (UDP-GlcA) and UDP-N-acetylgalactosamine (UDP-GalNAc) has been identified, cloned and characterized. The strategy for the identification of the novel NST involved a search of the expressed sequence tags database for genes related to the human UDP-galactose transporter-related isozyme 1, followed by heterologous expression of a candidate gene (hUGTrel7) in Saccharomyces cerevisiae and biochemical analyses. Significantly more UDP-GlcA and UDP-GalNAc were translocated from the reaction medium into the lumen of microsomes prepared from the hUGTrel7-expressing yeast cells than into the control microsomes from cells not expressing hUGTrel7. The possibility that this transporter participates in glucuronidation and/or chondroitin sulfate biosynthesis is discussed.     

Nocturnal emission and post-pollination change of floral scent in the leafflower tree,Glochidion rubrum,exclusively pollinated by seed-parasitic leafflower moths

Many insect-pollinated plants use floral scent signals to attract and guide the effective pollinators, and temporal patterns of their floral scent emission may be tuned to respond to the pollinator's activity and pollination status. In the intimate nursery pollination mutualism between monoecious Glochidion trees (Phyllanthaceae) and Epicephala moths (Gracillariidae), floral scent signals mediate species-specific interactions and influence the moth's efficient pollen-collecting and pollen-depositing behaviors on male and female flowers, respectively. We tested the hypotheses that both sexes of flowers of Epicephala-pollinated Glochidion rubrum exhibit a diel pattern of scent emission matching the activity period of the nocturnally active pollinator, and that female flowers change the chemical signal after pollination to reduce further visits and oviposition by the pollinator. We investigated the diel change of floral scent emissions during two consecutive days and the influence of pollination on the floral scent by conducting hand-pollinations in the field. The total scent emission of male and female flowers was higher at night than in the day, which would be expected from the nocturnal visitations of Epicephala moths. Some compounds exhibited a clear nocturnal emission rhythm. Hand-pollination experiments revealed that emission of two compounds, nerolidol and eugenol, drastically decreased in pollinated flowers, suggesting that these compounds may function as key attractants for the pollinator; however, the total scent emission of the female flower was not influenced by hand-pollination. The pattern of the floral scent emission of G. rubrum may be optimized to attract nocturnal pollinators and reduce oviposition.     

Evidence for specificity to Glomus group Ab in two Asian mycoheterotrophic Burmannia species

Nonphotosynthetic mycorrhizal plants, so‐called mycoheterotrophic plants, have long attracted the curiosity of botanists and mycologists. Recent advances in molecular methods based on fungal‐specific PCR amplification have dramatically enhanced the identification of their host mycorrhizal fungi. However, studies investigating the fungal hosts of arbuscular mycorrhizae‐forming mycoheterotrophs are still limited in Asia, which is known as one of the diversity hot spots of mycoheterotrophs that parasitize arbuscular mycorrhizae (AM). Therefore, we aimed to reveal the mycorrhizal associations of two Asian, fully mycoheterotrophic Burmannia species by molecular identification. Sequences of the small subunit ribosomal DNA showed that both Burmannia species are associated with several distinct lineages of Glomus group Ab. Because Glomus group Ab fungi have been confirmed as fungal hosts of various mycoheterotrophic plants in Africa and South America, we suggest they are widely exploited by AM‐forming mycoheterotrophs globally.     

Oxidative Stress Induced Inflammation Initiates Functional Decline of Tear Production

Oxidative damage and inflammation are proposed to be involved in an age-related functional decline of exocrine glands. However, the molecular mechanism of how oxidative stress affects the secretory function of exocrine glands is unclear. We developed a novel mev-1 conditional transgenic mouse model (Tet-mev-1) using a modified tetracycline system (Tet-On/Off system). This mouse model demonstrated decreased tear production with morphological changes including leukocytic infiltration and fibrosis. We found that the mev-1 gene encodes Cyt-1, which is the cytochrome b₅₆₀ large subunit of succinate-ubiquinone oxidoreductase in complex II of mitochondria (homologous to succinate dehydrogenase C subunit (SDHC) in humans). The mev-1 gene induced excessive oxidative stress associated with ocular surface epithelial damage and a decrease in protein and aqueous secretory function. This new model provides evidence that mitochondrial oxidative damage in the lacrimal gland induces lacrimal dysfunction resulting in dry eye disease. Tear volume in Tet-mev-1 mice was lower than in wild type mice and histopathological analyses showed the hallmarks of lacrimal gland inflammation by intense mononuclear leukocytic infiltration and fibrosis in the lacrimal gland of Tet-mev-1 mice. These findings strongly suggest that oxidative stress can be a causative factor for the development of dry eye disease.