Genomic analysis of Bartonella identifies type IV secretion systems as host adaptability factors

The bacterial genus Bartonella comprises 21 pathogens causing characteristic intraerythrocytic infections. Bartonella bacilliformis is a severe pathogen representing an ancestral lineage, whereas the other species are benign pathogens that evolved by radial speciation. Here, we have used comparative and functional genomics to infer pathogenicity genes specific to the radiating lineage, and we suggest that these genes may have facilitated adaptation to the host environment. We determined the complete genome sequence of Bartonella tribocorum by shotgun sequencing and functionally identified 97 pathogenicity genes by signature-tagged mutagenesis. Eighty-one pathogenicity genes belong to the core genome (1,097 genes) of the radiating lineage inferred from genome comparison of B. tribocorum, Bartonella henselae and Bartonella quintana. Sixty-six pathogenicity genes are present in B. bacilliformis, and one has been lost by deletion. The 14 pathogenicity genes specific for the radiating lineage encode two laterally acquired type IV secretion systems, suggesting that these systems have a role in host adaptability.     

构造、地貌和气候对汶川地震同震及震后地质灾害的控制作用——以龙门山北段通口河流域为例*

通过对汶川地震驱动的通口河流域同震崩塌、滑坡等地质灾害的野外实地考察和遥感影像分析,获得通口河流域同震及震后地质灾害的空间分布情况,结合对通口河流域构造、地貌和气候等因素的分析,获得以下认识：（1）构造因素（汶川地震）是导致通口河流域同震地质灾害的根本原因;（2）地貌因素为同震及震后地质灾害的发生提供了重要的环境条件;（3）以降雨为主的气候因素是导致震后通口河流域地质灾害发生的直接诱发因素。     

Fluorescence response of acridine orange to changes in pH gradients across liposome membranes

Summary The influence that changes in proton distribution have on the fluorescence of acridine orange was examined using negatively charged liposomes. Our results indicate that at least two mechanisms are involved: distribution of the probe between the internal aqueous phase of the liposomes and the outside medium, and binding of the probe to the liposome membranes.     

Bakteriostatisch wirksame Trichloräthylidenketone

Summary The bacteriostatic action of a series of trichloroethylidene-ketones R-CO-CH=CH-CCl₃ is described. Certain compounds, wherein R is a halogen-substituted aromatic ring, are active in a dilution up to 1:4 millions (0.25 mg in a liter) againstStrept. hm.     

Calcium uptake by sarcoplasmic reticulum from nerve-intact and standard skeletal muscle grafts

A freely grafted rat soleus muscle exhibits a decrease in velocity and capacity of SR calcium uptake. This deficit is not prevented by maintaining neural connections (nerve-intact graft) during grafting. Thus the greater mechanical capability of nerve-intact grafts, relative to standard grafts, is not accompanied by any enhancement of the SR tubules.     

Free amino acids in the egg fluid and embryos ofPila

Résumé Dans la capsule des ufs dePila (Gastéropode), le fluide alimentaire contient à peu près tous les acides-aminés libres qui existent aussi dans l'embryon bien développé. L'auteur a déterminé le nombre des acidesaminés libres qui se trouvent dans le corps de ces escargots après l'éclosion. Le modèle-type des acides-aminés libres reste inchangé chez les individus affamés.