The identification of ᴅ-tryptophan as a bioactive substance for postembryonic ovarian development in the planarian Dugesia ryukyuensis.

Many metazoans start germ cell development during embryogenesis, while some metazoans possessing pluripotent stem cells undergo postembryonic germ cell development. The latter reproduce asexually but develop germ cells from pluripotent stem cells or dormant primordial germ cells when they reproduce sexually. Sexual induction of the planarian Dugesia ryukyuensis is an important model for postembryonic germ cell development.

Participation of D-serine in the development and reproduction of the silkworm Bombyx mori.

The silkworm Bombyx mori contains high concentrations of free D-serine, an optical isomer of L-serine. To elucidate its function, we first investigated the localization of D-serine in various organs of silkworm larvae, pupae, and adult moths. Using immunohistochemical analysis with an anti-D-serine antibody, we found D-serine in the microvilli of midgut goblet and cylindrical cells and in peripheral matrix components of testicular and ovarian cells.

Effect of D-serine on spermatogenesis and extracellular signal-regulated protein kinase (ERK) phosphorylation in the testis of the silkworm, Bombyx mori.

Although the pupae and larvae of Bombyx mori possess especially large amounts of free d-serine, the physiological role of the amino acid in the silkworm is unknown. We investigated the effect of d-serine on spermatogenesis. A lowered d-serine level throughout larval development caused a delay in spermatogenesis and resulted in reduced numbers of eupyrene sperm.

Immunohistochemical localization of D-serine dehydratase in chicken tissues.

Chicken D-serine dehydratase (DSD) degrades d-serine to pyruvate and ammonia. The enzyme requires both pyridoxal 5'-phosphate and Zn(2+) for its activity. d-Serine is a physiological coagonist that regulates the activity of the N-methyl-d-aspartate receptor (NMDAR) for l-glutamate.

Planarian D-amino acid oxidase is involved in ovarian development during sexual induction.

To elucidate the molecular mechanisms underlying switching from asexual to sexual reproduction, namely sexual induction, we developed an assay system for sexual induction in the hermaphroditic planarian species Dugesia ryukyuensis. Ovarian development is the initial and essential step in sexual induction, and it is followed by the formation of other reproductive organs, including the testes. Here, we report a function of a planarian D-amino acid oxidase, Dr-DAO, in the control of ovarian development in planarians.

Crystallization and preliminary crystallographic analysis of D-aspartate oxidase from porcine kidney.

D-Aspartate oxidase (DDO) from porcine kidney was crystallized by the sitting-drop vapour-diffusion method using PEG 8000 as a precipitant. The crystal belonged to space group P2(1), with unit-cell parameters a = 79.38, b = 144.

Rapid determination of free D-serine with chicken D-serine dehydratase.

We have developed a simple, rapid, and inexpensive method of measuring the concentration of intrinsic free D-serine in tissue samples. This method uses chicken D-serine dehydratase in an enzymatic reaction to produce pyruvate, which is detected spectrophotometrically. Pyridoxal 5'-phosphate (PLP), a cofactor of D-serine dehydratase, increased pyruvate formation by 28%.

Crystal structure of a zinc-dependent D-serine dehydratase from chicken kidney.

D-serine is a physiological co-agonist of the N-methyl-D-aspartate receptor. It regulates excitatory neurotransmission, which is important for higher brain functions in vertebrates. In mammalian brains, D-amino acid oxidase degrades D-serine.

Crystallization and preliminary crystallographic analysis of D-serine dehydratase from chicken kidney.

D-Serine dehydratase purified from chicken kidney was crystallized by the hanging-drop vapour-diffusion method using PEG 4000 and 2-propanol as precipitants. The crystal belonged to space group P422, with unit-cell parameters a=105.0, c=81.

Immunohistochemical localization of D-aspartate oxidase in porcine peripheral tissues.

D-Aspartate (D-Asp) is an endogenous substance in mammals. Degradation of D-Asp is carried out only by D-aspartate oxidase (DDO). We measured DDO activity in porcine tissues, and produced an anti-porcine DDO antibody to examine the cellular localization of DDO.

Calorie restriction enhances cell adaptation to hypoxia through Sirt1-dependent mitochondrial autophagy in mouse aged kidney.

Mitochondrial oxidative damage is a basic mechanism of aging, and multiple studies demonstrate that this process is attenuated by calorie restriction (CR). However, the molecular mechanism that underlies the beneficial effect of CR on mitochondrial dysfunction is unclear. Here, we investigated in mice the mechanisms underlying CR-mediated protection against hypoxia in aged kidney, with a special focus on the role of the NAD-dependent deacetylase sirtuin 1 (Sirt1), which is linked to CR-related longevity in model organisms, on mitochondrial autophagy.

D-Serine dehydratase from chicken kidney: a vertebral homologue of the cryptic enzyme from Burkholderia cepacia.

D-serine dehydratase (DSD) catalyses the conversion of d-serine to pyruvate and ammonia. d-Serine is a physiological modulator of glutamate neurotransmission in vertebrate brains. In mammals d-serine is degraded by d-amino-acid oxidase, whereas in chicken brain it is degraded by DSD, as we have recently demonstrated [Tanaka et al.

Simultaneous measurement of D-serine dehydratase and d-amino acid oxidase activities by the detection of 2-oxo-acid formation with reverse-phase high-performance liquid chromatography.

N-methyl-D-aspartate receptors (NMDARs) play critical roles in excitatory synaptic transmission in the vertebrate central nervous system. NMDARs need D-serine for their channel activities in various brain regions. In mammalian brains, D-serine is produced from L-serine by serine racemase and degraded by D-amino acid oxidase (DAO) to 3-hydroxypyruvate.

Functional and structural characterization of D-aspartate oxidase from porcine kidney: non-Michaelis kinetics due to substrate activation.

D-aspartate oxidase (DDO, EC 1.4.3.

Single-turnover kinetics of 2,3-dihydroxybiphenyl 1,2-dioxygenase reacting with 3-formylcatechol.

2,3-Dihydroxybiphenyl 1,2-dioxygenase (EC 1.13.11.

Quantitative structure-activity relationship for the cleavage of C3/C4-substituted catechols by a prototypal extradiol catechol dioxygenase with broad substrate specificity.

Catechol 2,3-dioxygenase [EC 1.13.11.

Dependence of effective communication distance and characteristic time on the secretion rate in intercellular signaling.

Effective communication distance and characteristic time are discussed in relation to the temporal nonuniformity of the secretion rate in intercellular signaling. We demonstrated that these characteristics significantly depend on secretion time and the strength of the enhanced secretion rate for human cytokines.

Accurate measurement of near-micromolar oxygen concentrations in aqueous solutions based on enzymatic extradiol cleavage of 4-chlorocatechol: applications to improved low-oxygen experimental systems and quantitative assessment of back diffusion of oxygen from the atmosphere.

An enzymatic method for measuring the O(2) concentrations of aqueous solutions was developed by involving 4-chlorocatechol and catechol 2,3-dioxygenase from Pseudomonas putida. With this system, the amount of O(2) in a sample solution can be measured as the amount of 5-chloro-2-hydroxymuconate semialdehyde formed through the enzyme reaction. The product was stable and its anion exhibited strong absorption around 380 nm (molar absorption coefficient of 4.

Reduced activity of mtTFA decreases the transcription in mitochondria isolated from diabetic rat heart.

To evaluate abnormalities in the mitochondrial transcription factor A (mtTFA) function as a cause of mitochondrial dysfunction in diabetes, we measured the mRNA contents of the proteins consisting of the mitochondrial respiratory chain as well as transcriptional and translational activities in the mitochondria isolated from controls and streptozotocin-induced diabetic rat hearts. Using Northern blot analysis, we found 40% reduced mRNA contents of mitochondrial-encoded cytochrome b and ATP synthase subunit 6 in diabetic rat hearts compared with control rats (P < 0.05).