Formation of aerial hyphae and conidia under orthophosphate-limited conditions inNeurospora crassa: Role of repressible cyclic phosphodiesterase

A wild type strain ofNeurospora crassa produced aerial hyphae and luxuriant conidia in standing culture in low phosphate liquid media.nuc-1 andnuc-2, which have no ability to derepress repressible cyclic phosphodiesterase (cPDase) (3′; 5′-cyclic AMP 5′-nucleotidohydrolase, EC 3.1.4.17) and several other repressible enzymes, did not form them. Heterocaryon between them restored the abilities not only to produce aerial hyphae and conidia but also to produce cPDase. Revertants fromnuc-1 and a mutant in alkaline phosphatase,pho-2, produced aerial hyphae and conidia in low phosphate condition, whereas a mutant in cPDase,pho-3, produced only a limited amount of them. In media containing low levels of 2′, 3′-cAMP, the wild type, the revertants fromnuc-1, pho-2 andpho-3 produced aerial hyphae and conidia in abundance, whereas in media containing 3′, 5′-cAMP these strains produced no or only limited amounts of them. In low phosphate medianuc-1, nuc-2 andpho-3 showed higher levels of 3′, 5′-cAMP as compared with those strains which have the ability to derepress cPDase. The cPDase activities in crude mycelial extracts fromnuc-1 andpho-3 grown in low phosphate media were 5.6 and 17.5% of that ofpho-2 when assayed for 3′,5′-cAMP at an intracellular level of 2 μM.     

The first record of spawning-season homing of gin-buna crucian carp Carassius sp. to a lakeside biotope connected to Lake Biwa confirmed via acoustic telemetry and egg surveys

Ichthyological Research - Gin-buna crucian carp Carassius sp. is a widely distributed cyprinid fish inhabiting lakes and rivers throughout Japan. The species is categorized on the Red List of Shiga...     

Role of MAP kinase in neurons

Extracellular stimuli such as neurotransmitters, neurotrophins, and growth factors in the brain regulate critical cellular events, including synaptic transmission, neuronal plasticity, morphological differentiation and survival. Although many such stimuli trigger Ser/Thr-kinase and tyrosine-kinase cascades, the extracellular signal-regulated kinases, ERK1 and ERK2, prototypic members of the mitogen-activated protein (MAP) kinase family, are most attractive candidates among protein kinases that mediate morphological differentiation and promote survival in neurons. ERK1 and ERK2 are abundant in the central nervous system (CNS) and are activated during various physiological and pathological events such as brain ischemia and epilepsy. In cultured hippocampal neurons, simulation of glutamate receptors can activate ERK signaling, for which elevation of intracellular Ca²⁺ is required. In addition, brain-derived neurotrophic factor and growth factors also induce the ERK signaling and here, receptor-coupled tyrosine kinase activation has an association. We describe herein intracellular cascades of ERK signaling through neurotransmitters and neurotrophic factors. Putative functional implications of ERK and other MAP-kinase family members in the central nervous system are give attention.