Light Signals are Perceived by ATP-GTP(NTP)-binding Proteins in the Mycelia of Neurospora crassa

Blue light induced ADP ribosylation of 38 and 56 kDa proteins in the soluble fraction of mycelia of Neurospora crassa

Soluble fractions prepared from the mycelia of wild type (74-OR23-1A) and band (bd) exhibited an increase in the rate of the ADP ribosylation of a 38 kDa protein from nicotinamide adenine [32P]dinucleotide ([32P]NAD) in the presence of 10(-7) M riboflavin caused by blue light irradiation in vitro. The soluble fraction was mixed with a reaction mixture containing 5 microCi [32P]NAD at 0 degree C for 20 s and then it was irradiated with blue light (420 nm, 42 mumol m-2 s-1) for 12.5, 25, 50, 100, 200 or 400 s at 0 degree C or for 100 s with photon irradiance of 0.42, 4.2, 6.4 or 42 mumol m-2 s-1. Immediately after irradiation, the reaction was stopped and analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. An increase in the ADP ribosylation of the 38 kDa protein could be detected within 100 s of irradiation, and the enhancement in the rate of ADP ribosylation of the 38 kDa protein was proportional to the increase in the photon irradiance. By the irradiation with blue light for 200 or 400 s, the ADP ribosylation of a 56 kDa protein could also be detected. Analysis by two-dimensional gel electrophoresis of proteins after ADP ribosylation of them revealed that the 38 kDa proteins displayed at least four radioactive protein spots and the 56 kDa protein a single radioactive protein spot. Soluble fractions of mycelia prepared from blind mutants wc-1, wc-2, delta ps15-1, lis-1, lis-2 and lis-3 exhibited also the enhancement of the ADP ribosylation of the 38 kDa protein by blue light irradiation, and at least wc-1, delta ps15-1, lis-1 and lis-2 displayed a similar blue light response in the 56 kDa protein.

Allodiploid nature of Allium wakegi Araki revealed by genomic in situ hybridization and localization of 5S and 18S rDNAs

Allium wakegi Araki could be originated from cross hybridization between close relatives of a form of A. cepa and A. fistulosum. Chromosomes of each parental haploid set were identified in the chromosome complement of A. wakegi by genomic in situ hybridization using probes of the total, parental genomic DNAs of A. cepa and A. fistulosum, respectively. The results of GISH suggested significant differentiation of genomic DNAs between these closely related species. Allium cepa had two 5S rDNA loci at the interstitial regions of the short arms of small chromosome pair (the 7th pair) and A. fistulosum had one locus at the interstitial region of the homologous short arms. Allium wakegi had two chromosomes carrying one and two 5S rDNA loci which appeared to correspond to those of A. fistulosum and A. cepa, respectively. Chromosomes carrying 18S rDNA loci originated from those of both A. cepa and A. fistulosum were also observed in the chromosome complement of A. wakegi.

Light signals are transduced to the phosphorylation of 15 kDa proteins in Neurospora crassa

A microsomal fraction prepared from the mycelia of the band (bd) strain of Neurospora crassa showed enhanced phosphorylation of two small proteins with molecular masses of around 15 kDa (ps15) by the irradiation of the reaction mixture containing [gamma-32P]ATP at 0 degrees C for 1 s with blue light (450 nm, 6 mumol/m2/s or 420 nm, 80 mumol/m2/s). The reaction was stopped at 5 s of incubation at 0 degrees C after blue light irradiation. The light effect could not be detected in ps15, when a microsomal fraction from a blind mutant, wc-1 or wc-2 was used. The mixing followed by homogenization of the microsomal fractions from wc-1 and wc-2 restored the activity to simulate the phosphorylation of ps15 by blue light. The phosphorylated amino acid residue of ps15 was unstable when the proteins on a nylon membrane were exposed to an acid or alkaline solution, suggesting that the phosphorylated residue was aspartic acid. The other phosphorylated protein with a molecular mass of 70 kDa (p70) showed no light effect in the phosphorylation and the phosphorylated residue was estimated to be histidine, since it was stable in alkaline solution.