Polymerase chain reaction (PCR) is the most convenient and direct method for analyzing and manipulating DNA and RNA. PCR needs polymerase, templates, and primers. In this review, we focus our attention on the chemistry of PCR primers. Because PCR is a basic technology in biology research fields, we sometimes use chemically labeled primers without any awareness of the chemistry they leave behind. In this primer designing, there are a lot of potential for different chemistry ideas and much study is still necessary to advance PCR for single-nucleotide polymorphism (SNP) typing, genetic diagnosis, and other fields. We provide an overview of the labeling chemistry of PCR primers, especially the concept and its application to SNP and gene typing, and show a new type of PCR monitoring system in here.

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It is widely accepted that the N-methyl-D-asparate type glutamate receptor (NMDAR) plays a crucial role in expression of a wide variety of higher order brain functions in mammals. In agreement with this concept, antagonists for the NMDAR display schizophrenomimetic effects, suggesting that reduced transmission via the receptor may be involved in the pathophysiology of schizophrenia. Because D-serine plays a pivotal role in the control of NMDAR as its endogenous co-agonist in the central nervous system, disturbed signaling of D-serine could cause the possible hypofunction of the NMDAR in schizophrenia. However, the exact mechanisms underlying the regulation of extracellular release of D-serine await further elucidation. Recently, we have demonstrated that the inhibition of neutral amino acid transporter Asc-1, the stimulation of calcium permeable AMPA receptor and the deletion of serine racemase (SR) expressed in neurons modify the extracellular D-serine contents in the medial prefrontal cortex. Therefore, these molecules may participate in tuning of the extracellular D-serine liberation and could be suitable targets for development of new pharmacotherapies for brain disorders.

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D-Amino acids have long been considered to be unique to microorganisms, which utilize some D-amino acids to construct the peptidoglycan layer of their cell wall. However, several D-amino acids have been detected in many organisms and even in mammals. Aquatic crustaceans and some bivalve mollusks contain a large amount of free D-alanine in their tissues. Along with the hyper-osmotic stress, several free amino acids have been known to increase as intracellular osmolytes in aquatic invertebrates, and the tissue levels of D- and L-alanine in crustaceans and bivalve mollusks were both increased during high salinity acclimation. These data suggest that D-alanine is also a major compatible osmolyte responsible for intracellular isosmotic regulation. Alanine racemase has been proven to catalyze the interconversion of D- and L-alanine in crustacean. A cDNA clone encoding alanine racemase has been isolated from the muscle and hepatopancreas of kuruma prawn Marsupenaeus japonicus for the first time in the animal kingdom.
In this article, I would like to describe the physiological function and metabolism of D-alanine in kuruma prawn Marsupenaeus japonicus.

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