Pyridoxine stimulates filaggrin production in human epidermal keratinocytes

Molecular Biology Reports - Pyridoxine (PN), one of the vitamers of vitamin B6, plays an important role in the maintenance of epidermal function and is used to treat acne and rough skin. Clinical...     

Pyridoxine is required for post-embryonic root development and tolerance to osmotic and oxidative stresses

Pyridoxine (vitamin B6) is a cofactor required by numerous enzymes in all cellular organisms. Plants are the major source of vitamin B6 for animals, yet the biosynthesis pathway and the function of vitamin B6 in plants are not well elucidated. In this study, an Arabidopsis pyridoxine synthase gene PDX1 was characterized and its in vivo functions were investigated. The PDX1 gene was expressed in all plant parts examined and its expression level was not significantly regulated by abiotic stress or the phytohormone abscisic acid. In roots, PDX1 was highly expressed in a defined region behind the root tips that undergoes rapid cell division. The PDX1 protein was mainly associated with the plasma membrane and endomembranes, implying a potential involvement of vitamin B6 in membrane function. To reveal the in vivo role of PDX1, Arabidopsis insertional mutants were isolated. Strikingly, the pdx1 knockout mutants were impaired in root growth and early seedling development. The stunted roots resulted from both reduced cell division and elongation. Supplementation of the growth media with pyridoxine or reintroduction of the wild-type PDX1 gene into the mutants completely restored the mutant growth, demonstrating that PDX1 is required for pyridoxine biosynthesis in planta. In addition to the developmental defects, pdx1 mutants are hypersensitive to osmotic stress and oxidative stress. These mutant seedlings had increased peroxidation of membrane lipids following UV treatment. Our study establishes a critical role of vitamin B6 in plant development and stress tolerance and suggests that vitamin B6 may represent a new class of antioxidant in plants.     

Energy supply in early development of living cell

It is proposed that before light and oxidation of organic compounds became the predominant energy suppliers of the living cell, electron charge energy derived from heat energy by mineral particles, was the first energy source. The basis of this hypothesis is the finding that Al2O3 in electrolytic condensors can produce an electron driving force with a potential high enough for electrolysis of water and subsequent reduction of CO2 into organic molecules. This electron driving force is likely to originate from one-way movement of electrons in tunnel structures of the Al2O3 layer, driven by temperature kinetic energy.     

Pyridoxine kinase in Plasmodium lophurae and duckling erythrocytes.

Pyridoxine kinase enzyme activity was greatly increased in duckling erythrocytes infected with Plasmodium lophurae. Pyridoxine kinase activity in parasites freed from erythrocytes was much greater than that of uninfected erythrocytes. The apparent Km for pyridoxine of the parasite enzyme was 6.6 times 10(-5) M whereas the host red cell enzyme Km was 1.9 times 10(-6) M. Deoxypyridoxine inhibited host and parasite pyridoxine kinase activity with an apparent Ki of 1.5 times 10(-6) and 8.6 times 10(-6) M, respectively. These results suggest that the vitamin B6 metabolism of the malaria parasites is distinct and separate from that of the host erythrocytes.     

Unbuffered and buffered supply chains in human metabolism

The investigation of very complex dynamical systems like the human metabolism requires the comprehension of important subsystems. The present paper deals with energy supply chains as subsystems of the metabolism on the molecular, cellular, and individual levels. We form a mathematical model of ordinary differential equations and we show fundamental properties by Fourier techniques. The results are supported by a transition from a system of ordinary differential equations to a partial differential equation, namely, a transport equation. In particular, the behavior of supply chains with dominant pull components is discussed. A special focus lies on the role of buffer compartments.     

Pyridoxine Kinase in Plasmodium lophurae and Duckling Erythrocytes*

SYNOPSIS. Pyridoxine kinase enzyme activity was greatly increased in duckling erythrocytes infected with Plasmodium lophurae. Pyridoxine kinase activity in parasites freed from erythrocytes was much greater than that of uninfected erythrocytes. The apparent K_m for pyridoxine of the parasite enzyme was 6.6 × 10^-5 M whereas the host red cell enzyme K_m was 1.9 × 10^-6 M. Deoxypyridoxine inhibited host and parasite pyridoxine kinase activity with an apparent K_i of 1.5 × 10^-6 and 8.6 × 10^-6 M, respectively. These results suggest that the vitamin B₆ metabolism of the malaria parasites is distinct and separate from that of the host erythrocytes.     

Pyridoxine deficiency and cytotoxicity of T lymphocytes in vitro.

The effect of pyridoxine deficiency on the proliferation and cytotoxicity of BALB/c mouse lymphocytes stimulated in vitro with irradiated spleen cells from C3H mice was studied. Cytotoxicity was measured by Na⁵¹CrO₄ release from L cells which have the same histocompatibility loci as C3H mouse cells. Pyridoxal-5′-phosphate (PLP) content in the spleen and liver of pyridoxine-deficient animals was determined with Escherichia coli B/1 t7A apotryptophanase. Maintenance of animals on a pyridoxine-deficient diet for 1 to 3 weeks affected neither proliferation of lymphocytes in vitro nor their cytotoxicity. Lymphocytes from mice fed a pyridoxine-deficient diet for 5 to 6 weeks had a reduced capacity to respond to foreign lymphoid cells in vitro. The Cytotoxicity of these lymphocytes was also significantly decreased. PLP, but not pyridoxal, added directly to the medium in vitro partially restored the impaired functions of T lymphocytes.