Cloning and sequence analysis of the highly expressed melanin-synthesizing gene operon from Streptomyces castaneoglobisporus

 Streptomyces castaneoglobisporus HUT6202 overproduces a diffusible melanin-like pigment. An operon, designated mel, containing a gene that encodes tyrosinase, which is involved in the synthesis of melanin pigment, was cloned from the chromosomal DNA of the microorganism into the high-copy plasmid pAK114 and expressed in S. lividans. The tyrosinase activity of the transformed cells was at approximately a 110-fold higher level than that of the same host carrying the plasmid pIJ702, which has the same replication origin as pAK114 and carries the mel operon from S. antibioticus. The sequence analysis of the S. castaneoglobisporus mel operon revealed that an open- reading frame consisting of 378 base pairs(bp), designated ORF378, was found upstream of the tyrosinase gene (TYRC) consisting of 819 bp. In the present study, we constructed a chimeric mel operon consisting of ORF378 from S. castaneoglobisporus and the tyrosinase gene (TYRA) from S. antibioticus. The chimeric mel operon or the S. antibioticus mel operon, which consists of ORF438 and TYRA, expressed the tyrosinase activity in Escherichia coli intracellularly when located under the control of lacZ promoter, and the tyrosinase activity from the former was at a 30-fold higher level than that from the latter. This suggests that the gene contributing to the high expression of the tyrosinase activity in S. castaneoglobisporus is ORF378, rather than TYRC. Received: 12 June 1995/Received revision: 24 July 1995/Accepted: 7 September 1995     

Age-dependent aluminum accumulation in the human aorta and cerebral artery

The purpose of this study was to determine the extent of aluminum (Al) accumulation in the human aorta and cerebral arteries. The Al contents in the aortae and in the cerebral arteries from 23 human subjects was determined by inductively coupled plasma atomic emission spectrophotometry (ICP-AES). The subjects' age range was 45–99-yr-old; 15 of the subjects were males and 8 were females. Al was detected in twelve aortae and in six cerebral arteries, when the entire specimen was analyzed. Two specimens where Al was found in the cerebral arteries contained no Al in the aorta. No relationship to the subject's sex was found. When related to age, two groups were established. Group L (45–75 yr old) and group H (>75 yr old), which exhibited aortal Al concentrations of 33.3 and 72.7%, respectively. When the aortic wall was dissected into the tunica intima, media, and adventitia, Al was found mainly in the tunica media. In the aorta, significant relationships were found between Al and phosphorus (P) levels (r=0.801,p<0.01) and between Al and calcium (Ca) (r=0.661,p<0.05). We have concluded that Al accumulation is age-dependent and that it occurs both in the aorta and in the cerebral artery. In the aorta, accumulation occurs mainly in the tunica media. Both P and Ca appear to enhance aortal Al accumulation.     

Urocystis tranzscheliana,a newly recorded smut fungus onPrimula sieboldii from Japan

A smut fungus onPrimula sieboldii was newly found in Japan and identified asUrocystis tranzscheliana by comparative morphology. This species causes systemic infection ofP. sieboldii and produces sori in its ovaries.Contribution No. 121, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Inactivation of bleomycin by an N-acetyltransferase in the bleomycin-producing strain Streptomyces verticillus

Abstract Bleomycin-producing Streptomyces verticillus ATCC15003 possesses a bleomycin acetyltransferase which inactivates the drug in the presence of acetyl coenzyme A. The site of acylation in enzymically prepared acetylbleomycin A2 was determined by nuclear magnetic resonance analysis; the primary amino group of the β-aminoalanine moiety of bleomycin was acetylated. Acetylbleomycin A2 had no detectable antibacterial activity and did not induce in vitro DNA degradation.     

Stable isotopic structure of aquatic ecosystems

Isotopic, biogeochemical and ecological structure can provide a new dimension for understanding material flows, and the simultaneous function and structure of an ecosystem. Distributions ofδ ¹³C andδ ¹⁵N for biogenic substances in the Nanakita river estuary involving Gamo lagoon in Japan were investigated to construct isotope biogeochemical and ecological structure for assessing fate and transfer of organic matter, and food web structure. The isotopic framework of the ecosystem was successfully described in aδ ¹⁵N–δ ¹³C map. In this estuary the variations of isotope ratios of biogenic substances were clearly explained by the mixing of land-derived organic matter, and marine-derived organic matter. A trophic-level effect of¹⁵N enrichment was clearly observed. Organisms were classified into three groups depending upon the contribution of land-derived organic matter in a food chain. Almost all biota except mollusca in the lagoon depend on organic matter of marine origin. The contributions of both land and marine organic matter were comparable for mollusca in the lagoon.     

Lattice population dynamics for plants with dispersing seeds and Vegetative propagation

The population dynamics of plants in a lattice structured habitat are studied theoretically. Plants are assumed to propagate both by producing seeds that scatter over the population and by vegetative reproduction by extending runners, rhizomes, or roots, to neighboring vacant sites. In addtion, the seed production rate may be dependent on the local density in the neighborhood, indicating beneficial or harmful crowding effects. Two sets of population dynamical equation(s) are derived: one based onmean-field approximation and the other based onpair approximation (tracing both global and local densities simultaneously). We examine the accuracy of these approximate dynamics by comparing them with direct computer simulation of the stochastic lattice model. Pair approximation is much more accurate than mean-field approximation. Mean-field approximation overestimates the parameter range for persistence if crowding effects on seed production are harmful or weakly beneficial, but underestimates it if crowding effects are highly beneficial. Dynamics may show bistability (both population persistence and extinction) if the effect of crowding is strongly beneficial. If there is a linear trade-off between seed production and vegetative reproduction, the equilibrium abundance of the population may be maximised by a mixture of seed production and vegetative reproduction, rather than by pure seed production or by pure vegetative reproduction. This result is correctly predicted by pair approximation but not by mean-field approximation.     

Archiascomycetes: detection of a major new lineage within the Ascomycota

For phylogenetic analysis of the higher fungi, we sequenced the nuclear small subunit rRNA (18S rRNA) gene fromTaphrina populina, the type species of the genusTaphrina, andProtomyces lactucae-debilis. The molecular phylogeny inferred from these 2 sequences and 75 sequences from the DNA data bank divided the Ascomycota into three major lineages: the hemiascomycetes, the euascomycetes, and the archiascomycetes, newly described herein. The former two lineages are monophyletic, whereas the archiascomycetes, which originated first and are comprised ofTaphrina, Protomyces, Saitoella, Schizosaccharomyces, andPneumocystis, may not be monophyletic. Among the archiascomycetes, theTaphrina/Protomyces branch is monophyletic. Confirmation of the archiascomycetes as a monophyletic taxonomic class will require comparison of additional genetically defined characters.This work was supported in part by grants 05454030 from the Ministry of Education, Science, and Culture of Japan (to J. S.) and 4369 from the Japan Society for the Promotion of Science Fellowship Programs (to H. N.).