A new toad from western China, by Karl P. Schmidt and Ch'eng-chao Liu.

v.24:no.13(1940)

Characterization of spontaneous gacS and gacA regulatory mutants of Pseudomonas fluorescens biocontrol strain CHAO.

In Pseudomonasfluorescens strain CHAO, the response regulator gene gacA controls expression of extracellular enzymes and antifungal secondary metabolites, which are important for this strain's biocontrol activity in the plant rhizosphere. Two Tn5 insertion mutants of strain CHA0 that had the same pleiotropic phenotype as gacA mutants were complemented by the gacS sensor kinase gene of P. syringae pv. syringae as well as that of P. fluorescens strain Pf-5, indicating that both transposon insertions had occurred in the gacS gene of strain CHA0. This conclusion was supported by Southern hybridisation using a gacS probe from strain Pf-5. Overexpression of the wild-type gacA gene partially compensated for the gacS mutation, however, the overexpressed gacA gene was not stably maintained, suggesting that this is deleterious to the bacterium. Strain CHA0 grown to stationary phase in nutrient-rich liquid media for several days accumulated spontaneous pleiotropic mutants to levels representing 1.25% of the population; all mutants lacked key antifungal metabolites and extracellular protease. Half of 44 spontaneous mutants tested were complemented by gacS, the other half were restored by gacA. Independent point and deletion mutations arose at different sites in the gacA gene. In competition experiments with mixtures of the wild type and a gacA mutant incubated in nutrient-rich broth, the mutant population temporarily increased as the wild type decreased. In conclusion, loss of gacA function can confer a selective advantage on strain CHA0 under laboratory conditions.

Deleterious impact of a virulent bacteriophage on survival and biocontrol activity of Pseudomonas fluorescens strain CHAO in natural soil.

Many biotic and abiotic factors affect the persistence and activity of beneficial pseudomonads introduced into soil to suppress plant diseases. One such factor may be the presence of virulent bacteriophages that decimate the population of the introduced bacteria, thereby reducing their beneficial effect. We have isolated a lytic bacteriophage (phi)GP100) that specifically infects the biocontrol bacterium Pseudomonas fluorescens CHA0 and some closely related Pseudomonas strains. phiGP100 was found to be a double-stranded-DNA phage with an icosahedral head, a stubby tail, and a genome size of approximately 50 kb. Replication of phiGP100 was negatively affected at temperatures higher than 25 degrees C. phiGP100 had a negative impact on the population size and the biocontrol activity of P. fluorescens strain CHA0-Rif (a rifampicin-resistant variant of CHA0) in natural soil microcosms. In the presence of phiGP100, the population size of strain CHA0-Rif in soil and on cucumber roots was reduced more than 100-fold. As a consequence, the bacterium's capacity to protect cucumber against a root disease caused by the pathogenic oomycete Pythium ultimum was entirely abolished. In contrast, the phage affected neither root colonization and nor the disease suppressive effect of a phiDGP100-resistant variant of strain CHA0-Rif. To our knowledge, this study is the first to illustrate the potential of phages to impair biocontrol performance of beneficial bacteria released into the natural soil environment.

De chao

Invokaatio: Sun Theo.

楊淇園先生超性事蹟Yang qi yuan xian sheng chao xing shi ji.Vie et conversion de Yang Qi yuan.

Ce personnage, postnom Ting jun, docteur en 1592, fut converti par le P. Ricci. Ouvrage de Ding Zhi lin (XVIIe ou XVIIIe siècle).

熙朝崇正集Xi chao chong zheng ji.Monuments de la religion chrétienne.

Stèle de Xi an fu, croix de Wen ling, décrets et rapports : mémoires de Xu Guang qi, Zhang Geng, etc., publiés par l'église du Fu jian (1638) à Quan zhou.2 livres.

超性學要目錄Chao xing xue yao mu lu.

La somme théologique de saint Thomas, index.Impression de 1654. Livre préliminaire contenant une table générale qui indique la division de l'ouvrage en 3 sections :Livre 1 (1re section) de Dieu.Livre 2 (2e section, a) de la fin de l'homme, du bien qui concourt et du mal qui s'oppose à cette fin.Livre 3 (2e section, b) des vertus et des péchés contraires.Livre 4 (3e section) de l'incarnation et de la rédemption.Table détaillée en 4 livres.

超性學要Chao xing xue yao.

Contient : Dieu, livres 1 à 6 ; la Sainte-Trinité, livres 7 à 9 ; la création, livre 10 ; les anges, livres 11 à 15 ; la création des objets matériels, livre 16 ; l'âme de l'homme, livres 17 à 22 ; le corps de l'homme, livres 23 et 24 ; la Providence, livres 25 et 26

超性學要Chao xing xue yao.

Contient : Dieu, livres 1 à 6 ; la Sainte-Trinité, livres 7 à 9 ; la création, livre 10 ; les anges, livres 11 à 15 ; la création des objets matériels, livre 16 ; l'âme de l'homme, livres 17 à 22 ; le corps de l'homme, livres 23 et 24 ; la Providence, livres 25 et 26

超性學要Chao xing xue yao.

Contient : Dieu, livres 1 à 6 ; la Sainte-Trinité, livres 7 à 9 ; la création, livre 10 ; les anges, livres 11 à 15 ; la création des objets matériels, livre 16 ; l'âme de l'homme, livres 17 à 22 ; le corps de l'homme, livres 23 et 24 ; la Providence, livres 25 et 26

超性學要Chao xing xue yao.

Même ouvrage, impression différente ; sans la préface de Gao Zeng yun ; on y trouve une préface du P. Buglio (1654) et un avertissement.Livres 1 à 6 seulement.

口鐸日抄Kou duo ri chao.

Réponses verbales notées au jour le jour.Entretiens des PP. Aleni et André Rudomina, Jésuite (1596-1632 ; noms Chinois Lu An de Pan shi), de 1630 à 1640. Préfaces par Zhang Geng, de Wen ling, et par Lin Yi jun Yong yue ; introduction par Li Jiu biao Qi xiang. Avertissement. Table générale, incomplète ; table pour chaque livre.8 livres.

Variance estimation with Chao's sampling scheme

We show that the Hájek (Ann. Math Statist. (1964) 1491) variance estimator can be used to estimate the variance of the Horvitz–Thompson estimator when the Chao sampling scheme (Chao, Biometrika 69 (1982) 653) is implemented. This estimator is simple and can be implemented with any statistical packages. We consider a numerical and an analytic method to show that this estimator can be used. A series of simulations supports our findings.