Effects of Fluorescent Light on Growth of Bovine Retinal Pigment Epithelial Cells In Vitro Incubated with Linoleic Acid or Linoleic Acid Hydroperoxide

Light-induced peroxidation of polyunsaturated fatty acids (PUFA) may generate lipid hydroperoxides, which may have toxic effects on retinal pigment epithelial (RPE) cells in vitro. We investigated the effects of cool-white fluorescent light on the RPE cells incubated with linoleic acids (LA) or linoleic acid hydroperoxides (LHP) and the influence of antioxidative enzymes. We measured the bovine RPE cell number after exposure to fluorescent light (610 and 1,200 lux) in the presence of LA or LHP. Furthermore, the effects of superoxide dismutase (SOD) and catalase on LA- or LHP-treated RPE cells were also examined. Both LA and LHP treatment increased RPE cell number under weak illumination (610 lux), but dose-dependently decreased the number of cells exposed to strong illumination (1,200 lux). With exposure to strong illumination, LA caused a greater reduction in RPE cell number than LHP. Multiple linear regression analysis showed that the number of RPE cells was significantly decreased in a manner dependent on the interactions of the illuminance of light and the concentrations of LA or LHP. The antioxidative enzymes significantly ameliorated the damage to RPE cells from LA or LHP and exposure to light. Therefore, the exposure to fluorescent light augmented the cytotoxic effects of LA and LHP on RPE cells, and this effect is likely to be mediated by reactive oxygen species.     

Phylogeography and population structure of the Atlantic and Mediterranean green turtle Chelonia mydas: a mitochondrial DNA control region sequence assessment

Mitochondrial (mt) DNA sequences were analysed to resolve the phylogeography and population genetic structure of Atlantic and Mediterranean populations of green turtles ( Chelonia mydas ). Analysis of sequence variation over 487 base pairs of the control (D-loop) region identified 18 haplotypes among 147 individuals from nine nesting populations. Pairwise comparisons of haplotype frequencies distinguished most nesting colonies, indicating significant genetic differentiation among rookeries and a strong propensity for natal homing behaviour by nesting females. Comparison of control region sequence data to earlier restriction fragment length polymorphism (RFLP) data for the same individuals demonstrates approximately a sixfold higher substitution rate in the 5' end of the control region. The sequence data provide higher resolution both in terms of the number of mtDNA genotype variants and the phylogeographic relationships detected within the Atlantic region, and reveal a gene genealogy that distinguishes two groups of haplotypes corresponding to (i) the western Caribbean and Mediterranean, and (ii) eastern Caribbean, South Atlantic and West Africa. The data suggest that phylogeographic patterns in the Atlantic Ocean may be interpreted in terms of female nest site fidelity and episodic dispersal events. The distribution of mtDNA haplotypes within the region is thus explained by the geological and climatic alternations (glacial and interglacial) over the last million years.     

Plant phenology-mediated indirect effects: The gall midge opens the phenological window wider for a leaf beetle

We examined whether larvae of the gall midge Rabdophaga rigidae (Diptera: Cecidomyiidae) can modify the seasonal dynamics of the density of a leaf beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae), by modifying the leaf flushing phenology of its host willow species, Salix serissaefolia and Salix eriocarpa (Salicaceae). To test this, we conducted field observations and a laboratory experiment. The field observations demonstrated that the leaf flushing phenology of the willows and the seasonal dynamics of the beetle density differed between shoots with stem galls and shoots without them. On galled shoots of both willow species, secondary shoot growth and secondary leaf production were promoted; consequently, leaf production showed a bimodal pattern and leaf production periods were 1 to 2 months longer than on non‐galled shoots. The adult beetle density on galled shoots was thus enhanced late in the season, and was found to change seasonally, synchronizing with the production of new leaves on the host willow species. From the results of our laboratory experiment, we attributed this synchrony between adult beetle density and willow leaf flush to beetles’ preference to eat new leaves rather than old. Indeed, beetles consumed five times more of the young leaves when they were fed both young and old leaves. These results indicate that stem galls indirectly enhance the adult beetle density by enhancing food quality and quantity late in the beetle‐feeding season. We therefore conclude that midge galls widen the phenological window for leaf beetles by extending the willows’ leaf flush periods.     

Breakdown of middle lamella pectin by ●OH during rapid abscission in Azolla

Azolla, a small water fern, abscises its roots and branches within 30 min upon treatment with various stresses. This study was conducted to test whether, in the rapid abscission that occurs in Azolla, breakdown of wall components of abscission zone cells by ^●OH is involved. Experimentally generated ^●OH caused the rapid separation of abscission zone cells from detached roots and the rapid shedding of roots from whole plants. Electron microscopic observations revealed that ^●OH rapidly and selectively dissolved a well‐developed middle lamella between abscission zone cells and resultantly caused rapid cell separation and shedding. Treatment of abscission zones of Impatiens leaf petiole with ^●OH also accelerated the separation of abscission zone cells. However, compared with that of Azolla roots, accelerative effects in Impatiens were weak. A large amount of ^●OH was cytochemically detected in abscission zone cells both of Azolla roots and of Impatiens leaf petioles. These results suggest that ^●OH is involved in the cell separation process not only in the rapid abscission in Azolla but also in the abscission of Impatiens. However, for rapid abscission to occur, a well‐developed middle lamella, a unique structure, which is sensitive to the attack of ^●OH, might be needed.     

Systematic position of Pyloetis mimosae (Stainton) (Lepidoptera: Tineidae), with redescriptions of the adults and immature stages

Morphological characters of adults and immature stages of Pyloetis mimosae (Stainton 1859) are redescribed mainly on the basis of material collected from seed pods of Leucaena leucocephala (Lem.) in the Ryukyus, Japan. Although the systematic position of this species in the family Tineidae has been problematic, we conclude that it should be placed in the subfamily Erechthiinae based on morphological characters. Pyloetis mimosae is newly recorded from Japan.     

Thinning of the basement Membrane and Localized Cell Proliferation during Gland Formation of the Chick Proventriculus

The early processes of proventricular gland formation in the chick embryo were investigated. The glands appeared as intra-epithelial invaginations of the proventricular endoderm on day 6 of incubation. By day 6.5 they began to protrude into the mesenchyme and elongated without branching until day 9. Before elongation of the glands, the immunofluorescence of laminin and the ultrastructure of the basal lamina were consistently observed in the intra-epithelial invaginations as well as in other regions, and the mitotic activity in the gland rudiments was not different from that in other regions. However, at the tips of the elongating glands, little laminin was detected and the basal lamina were thin and discontinuous. The mitotic activity at the tip of the glands was higher than that in non-glandular epithelium or in the stalk of the glands. These results suggest causal relationships between thinning of the basement membrane and localized epithelial cell proliferation at the tip of the elongating glands.