Carotenoid synthesis in Streptomyces setonii ISP5395 is induced by the gene crtS, whose product is similar to a sigma factor

In many species of actinomycetes, carotenogenesis can be photoinduced. The capacity to respond to photoinduction is, however unstable and, in various strains of Streptomyces, is lost at a relatively high frequency. In Streptomyces setonii ISP5395, which normally produces no carotenoids, carotenoid-producing mutants can be obtained following protoplast regeneration. We report here the characterization of a gene, crtS, which was isolated from one such mutant and can confer on wild-type S. setonii ISP5395 cells the capacity to synthesize carotenoids. Sequence analysis of crtS reveals an open reading frame, which shows homology to genes that encode alternative sigma factors in Bacillus subtilis. We propose that crtS encodes a sigma factor which is necessary for the expression of a cryptic gene(s) for carotenoid biosynthesis in S. setonii ISP5395.     

Changes in Targeting Efficiencies of Proteins to Plant Microbodies Caused by Amino Acid Substitutions in the Carboxy-terminal Tripeptide

It has been demonstrated that the carboxyl terminus of microbodyenzymes functions as a targeting signal to microbodies in higherplants. We have examined an ability of 24 carboxy-terminal aminoacid sequences to facilitate the transport of a cytosolic passengerprotein, ß-glucuroni-dase, into microbodies in greencotyledonary cells of trans-genic Arabidopsis. Immunoelectronmicroscopic analysis revealed that carboxy-terminal tripeptidesequences of the form [C/A/S/P]-[K/R]-[I/L/M] function as amicrobody-targeting signal, although tripeptides with prolineat the first amino acid position and isoleucine at the carboxylterminus show weak targeting efficiencies. All known micro-bodyenzymes that are synthesized in a form similar in size to themature molecule, except catalase, contain one of these tripeptidesequences at their carboxyl terminus. (Received April 14, 1997; Accepted April 8, 1997)     

Purification of Protein Body-I of Rice Seed and its Polypeptide Composition

Protein body type one (PB-I) was isolated and purified fromdeveloping rice grain by a combination of sucrose density gradientcentrifugation and treatment with pepsin. SDS-PAGE analysisshowed that isolated PB-I contains several polypeptide groups,the largest having an apparent molecular size of 13 kDa andtwo smaller ones of 10 kDa and 16 kDa. The 13-kDa group wasfound to be composed of two polypeptides of slightly differentmolecular sizes, 13a (larger component) and 13b (smaller component).Most of the 13a and 13b polypeptides were shown to be largelyprolamins, although there were also some salt- and alcohol-insolublepolypeptides with an apparent molecular size of 13 kDa. It wasconcluded that PB-I is the accumulation site of rice prolamin.It was further estimated that the protein amount in PB-I accountedfor about 20% of the total protein of rice endosperm. (Received March 20, 1987; Accepted September 8, 1987)     

Kinetic studies on the prenyl chain elongation by undecaprenyl diphosphate synthase with artificial substrate homologues

In the undecaprenyl diphosphate synthase reaction, an allylic substrate homologue, (2Z,6E,10E)-4-methyl-geranylgeranyl diphosphate was found to be a potent competitive inhibitor against the allylic primer, (2Z,6E,10E)-geranylgeranyl diphosphate. On the other hand, it acted as a strong noncompetitive inhibitor against isopentenyl diphosphate. On the basis of these facts, the topology of the substrate-binding sites as well as the reason why the synthase reaction with (E)-3-methyl-3-pentenyl diphosphate always stops completely at the first stage of condensation, yielding an allylic diphosphate with a methyl group at the 4-position, are discussed.     

Folic acid as a dietary factor affecting the wing morph of the planthopper, Laodelphax striatellus (hemiptera, delphacidae)

A factor effecting the production of brachypterous adults in Laodelphax striatellus was studied by comparing a diet on which brachypterous adults sometimes developed and a diet on which they never developed. By substituting components distinctive of the latter diet into the former, or by varying the concentration of certain components of the latter diet, the production of brachypterous adults was found to vary with the concentration of a vitamin, folic acid. Brachypterous adults were produced only when the diet contained folic acid at concentrations between 0.5 mg/l and 7.5 mg/l.

---

Résumé Un facteur efficace pour la production d'adultes brachyptères chez Laodelphax striatellus a été recherché en comparant une nourriture sur laquelle des adultes brachyptères se développent parfois et une nourriture sur laquelle ils ne se développent jamais. En substituant les constituants spécifiques de cette dernière par ceux de la première ou en variant les concentrations de certains des constituants de la dernière on a montré que la production d'adultes brachyptères varie avec la concentration d'une vitamine, l'acide folique. Ceux-ci sont produits seulement lorsque l'alimentation contient de l'acide folique à des concentrations comprises entre 0,5 mg/l et 7,5 mg/l.

     

Necessity of IgE antibodies and mast cells for manifestation of resistance against larval Haemaphysalis longicornis ticks in mice

Genetically mast cell-deficient WBB6F1-W/Wv mice showed an apparent defect in manifestation of the resistance against larval Haemaphysalis longicornis ticks, but their serum IgE levels increased more than 100-fold after the second tick infestation. Immune sera obtained from the WBB6F1-W/Wv mice were adoptively transferred to the other WBB6F1-W/Wv mice which had received intracutaneous injections of WBB6F1-+/+ mouse-derived cultured mast cells. Because the resistance against ticks was detectable only when both mast cells and IgE antibodies were available, immediate hypersensitivity reaction appeared to have a physiologic role in the manifestation of the resistance against H. longicornis ticks.     

Utilization of Anhydrous Aluminum Phosphate as a Sole Source of Phosphorous by a Selected Carrot Cell Line

Two variants of carrot (Daucus carota L. cv. MS Yonsun) celllines, which had been selected with Al-phosphate as a sole sourceof phosphorous, were characterized on their mechanisms of phosphate-utilizationfrom Al-phosphate. Both cell lines excreted citrate into themedium. The amount of citrate excretion was highly correlatedwith cell growth in the presence of Al-phosphate. There wasabout a 1 to 1 correlation between solublized-Al and excreted-citratein the medium during cell growth. These results suggest that1) the citrate could chelate with Al, at a 1 to 1 ratio, inAl-phosphate, 2) the citrate-chelated Al remains outside thecells, and 3) solublized phosphate from Al-phosphate is utilizedfor the growth of carrot cells. The characteristics of the selectedcells were very stable, since the rate of citrate-excretionshowed no change after subculturing 25 passages without Al-phosphate. (Received August 7, 1989; Accepted October 19, 1989)     

Mutations associated with floral organ number in rice

How floral organ number is specified is an interesting subject and has been intensively studied in Arabidopsis thaliana. In rice (Oryza sativa L.), mutations associated with floral organ number have been identified. In three mutants of rice, floral organ number 1 (fon1) and the two alleles, floral organ number 2-1 (fon2-1) and floral organ number 2-2 (fon2-2), the floral organs were increased in number centripetally. Lodicules, homologous to petals, were rarely affected, and stamens were frequently increased from six to seven or eight. Of all the floral organs the number of pistils was the most frequently increased. Among the mutants, fon1 showed a different spectrum of organ number from fon2 -1 and fon2 -2. Lodicules were the most frequently affected in fon1, but pistils of more than half of fon1 flowers were unaffected; in contrast, the pistils of most flowers were increased in fon2 -1 and fon2-2. Homeotic conversion of organ identity was also detected at a low frequency in ectopically formed lodicules and stamens. Lodicules and stamens were partially converted into anthers and stigmas, respectively. Concomitant with the increased number of floral organs, each mutant had an enlarged apical meristem. Although meristem size was comparable among the three mutants and wild type in the early phase of flower development, a significant difference became apparent after the lemma primordium had differentiated. In these mutants, the size of the shoot apical meristem in the embryo and in the vegetative phase was not affected, and no phenotypic abnormalities were detected. These results do not coincide with those for Arabidopsis in which clavatal affects the sizes of both shoot and floral meristems, leading to abnormal phyllotaxis, inflorescence fasciation and increased floral organs. Accordingly, it is considered that FON1 and FON2 function exclusively in the regulation of the floral meristem, not of the vegetative meristem.Abbreviation DIC differential interference contrast This work was supported in part by Grant-in-Aid for Scientific Research on Priority Areas from the Ministry of Education, Science and Culture of Japan.