Skin photorejuvenation effects of light-emitting diodes (LEDs): a comparative study of yellow and red LEDs in vitro and in vivo.

BACKGROUND: Red-coloured light-emitting diodes (LEDs) can improve skin photorejuvenation and regeneration by increasing cellular metabolic activity. AIM: To evaluate the effectiveness of visible LEDs with specific wavelengths for skin photorejuvenation in vitro and in vivo. METHODS: Normal human dermal fibroblasts (HDFs) from neonatal foreskin were cultured and irradiated in vitro by LEDs at different wavelengths (410-850 nm) and doses (0-10 J/cm(2) ). In vivo experiments were performed on the skin of hairless mice. Expression of collagen (COL) and matrix metalloproteinases (MMPs) was evaluated by semi-quantitative reverse transcription PCR (semi-qRT-PCR), western blotting and a procollagen type I C-peptide enzyme immunoassay (EIA). Haematoxylin and eosin and Masson trichrome stains were performed to evaluate histological changes. RESULTS: In HDFs, COL I was upregulated and MMP-1 was downregulated in response to LED irradiation at 595 ± 2 and 630 ± 8 nm. In the EIA, a peak result was achieved at a dose of 5 J/cm(2) with LED at 595 ± 2 nm. In vivo, COL I synthesis was upregulated in a dose-dependent manner to both 595 and 630 nm LED irradiation, and this effect was prolonged to 21 days after a single irradiation with a dose of 100 J/cm(2) . These histological changes were consistent with the results of semi-qRT-PCR and western blots. CONCLUSION: Specific LED treatment with 595 ± 2 and 630 ± 8 nm irradiation was able to modulate COL and MMPs in skin, with the effects persisting for at least 21 days after irradiation. These findings suggest that yellow and red LEDs might be useful tools for skin photorejuvenation.

Developmental regulation of K accumulation in pollen, anthers, and papillae: are anther dehiscence, papillae hydration, and pollen swelling leading to pollination and fertilization in barley (Hordeum vulgare L.) regulated by changes in K concentration?

The presence of potassium (K) in pollen, anthers and papillae from barley (Hordeum vulgare L.) flowers with different levels of developmental stages starting from boot stage to fully mature flower, was studied by using the K-sensitive fluorescent dye PBFI (potassium-binding benzofuran isophthalate) and confocal laser scanning microscopy. The presence of heavy K fluorescence was detected only at the aperture area of the mature pollen. Similarly, the presence of K increased with the progression from immature to mature anther and papillae. In addition, a higher concentration of K was observed only at the stomium area (the place of anther dehiscence) of mature anthers. Keeping in view the role of K as an active osmoticum and the consistent and synchronized appearance of K in mature pollen, anthers, and papillae, it was concluded that K may regulate anther dehiscence, pollen imbibition, and papillae hydration leading to pollination and fertilization.

Molecular cloning and characterization of a tobacco leaf cDNA encoding a phosphate transporter.

Phosphate acquired by roots is translocated to and utilized by the upper part of the plant, where the phosphate transport in the cell is also important in the phosphate metabolism. In order to study the role of the phosphate transporter in the regulation of the phosphate movement across the membranes in leaf cells, we isolated and characterized a 2,059 bp tobacco leaf cDNA clone, NtPT1. The 537 amino acid sequences, deduced from NtPT1, exhibited 93 and 91% identites to one of the high affinity phosphate transporters constitutively expressed in potato and tomato roots, respectively. The NtPT1 contains 12 membrane-spanning domain with a central hydrophilic region. The expression of NtPT1 in the yeast high affinity phosphate transporter mutant strain, NS219, complemented the mutant and promoted cell growth significantly. These results strongly suggest that NtPT1 encodes a functional phosphate transporter and that one of the high affinity phosphate transporters expressed in roots is also expressed in leaves. Southern analysis indicated that tobacco phosphate transporter genes are low copy number genes and members of a small multi-gene family.

Tissue specific and inducible expression of resveratrol synthase gene in peanut plants.

The expression of resveratrol synthase (RS) genes is induced by biotic and abiotic factors in peanut cell cultures. However, little is known about the regulation of the RS gene expression in peanut plants. The expression of RS genes was investigated in peanut plants with a peanut RS clone, pPRS3C, which encodes two polypeptides that show about a 96% amino acid sequence identity to peanut RS2 and RS3, respectively. A low level of RS mRNA was detected in the roots of peanut plants grown aseptically in vitro. In mature peanut plants that were grown in the field, however, RS mRNAs were present at relatively high levels in both the roots and pods, but at below the detection limit in leaves. RS mRNAs were abundant in young pods and decreased dramatically in mature pods. The RS mRNA expression was induced by yeast extract and UV in leaves and roots, and also by wounding in leaves. Stress hormones, such as ethylene, jasmonic acid, and salicylic acid, induced RS mRNA accumulation in leaves. These results indicate that the RS gene expression is induced by biotic and abiotic stresses through the stress hormones in peanut plants. The induction of the RS gene expression by biotic and abiotic stresses could provide peanut plants with protection from microbial infections through resveratrol synthesis. The RS gene expression in developing pods has significant implications in terms of the role of resveratrol as a phytochemical for human health.

Cloning and characterization of a tobacco cDNA encoding calcium/calmodulin-dependent glutamate decarboxylase.

In plants, gamma-aminobutyric acid (GABA), a major transmitter in the central nervous system in animals, is synthesized by glutamate decarboxylase (GAD), the activity of which is tightly modulated by Ca2+/calmodulin. To study the molecular mechanism of GAD regulation and examine the physiological role of GABA in plants, we isolated and characterized a 1771 bp tobacco cDNA clone, pNtGAD2. The 496 amino acid sequence deduced from pNtGAD2 showed 97, 92, and 81% identity to NtGAD1, petunia, and tomato GAD, respectively. The 26 amino acid sequence within the putative calmodulin binding domain at the carboxy terminus showed a typical alpha-helical structure with hydrophobic and charged amino acid clusters. The pNtGAD2-encoded 56 kDa protein interacted strongly with a monoclonal antibody against the petunia GAD and its GAD activity was stimulated markedly by the addition of exogenous calcium and calmodulin. The molecular sequence of pNtGAD2 and biochemical characteristics of the pNtGAD2-encoded protein confirmed that pNtGAD2 is a clone encoding a functional calmodulin-binding and Ca2+/calmodulin-dependent tobacco glutamate decarboxylase. This result indicates that tobacco plants also have Ca2+/calmodulin-dependent GADs.