Direct binding of ESCRT protein Chm7 to phosphatidic acid–rich membranes at nuclear envelope herniations

Mechanisms that control nuclear membrane remodeling are essential to maintain the integrity of the nucleus but remain to be fully defined. Here, we identify a phosphatidic acid (PA)–binding capacity in the nuclear envelope (NE)–specific ESCRT, Chm7, in budding yeast. Chm7’s interaction with PA-rich membranes is mediated through a conserved hydrophobic stretch of amino acids, which confers recruitment to the NE in a manner that is independent of but required for Chm7’s interaction with the LAP2-emerin-MAN1 (LEM) domain protein Heh1 (LEM2). Consistent with the functional importance of PA binding, mutation of this region abrogates recruitment of Chm7 to membranes and abolishes Chm7 function in the context of NE herniations that form during defective nuclear pore complex (NPC) biogenesis. In fact, we show that a PA sensor specifically accumulates within these NE herniations. We suggest that local control of PA metabolism is important for ensuring productive NE remodeling and that its dysregulation may contribute to pathologies associated with defective NPC assembly

Quasi-classical path integral approach to supersymmetric quantum mechanics

{}From Feynman's path integral, we derive quasi-classical quantization rules in supersymmetric quantum mechanics (SUSY-QM). First, we derive a SUSY counterpart of Gutzwiller's formula, from which we obtain the quantization rule of Comtet, Bandrauk and Campbell when SUSY is good. When SUSY is broken, we arrive at a new quantization formula, which is found as good as and even sometime better than the WKB formula in evaluating energy spectra for certain one-dimensional bound state problems. The wave functions in the stationary phase approximation are also derived for SUSY and broken SUSY cases. Insofar as a broken SUSY case is concerned, there are strong indications that the new quasi-classical approximation formula always overestimates the energy eigenvalues while WKB always underestimates.Comment: 13 pages + 5 figures, complete paper submitted as postscript file, to appear in Phys. Rev.

A species-specific DNA probe for Providencia stuartii identification.

A DNA probe is described that can be used for identification of Providencia stuartii by means of filter hybridization assays. The probe, which is a fragment of the P. stuartiiphoN gene coding for an acid phosphatase, appeared to be able to recognize only P. stuartii strains in slot-blot hybridization experiments performed with total DNA extracted from 545 strains of 64 different Gram-negative bacterial species, including all the major representatives of the family Enterobacteriaceae. Owing to the problems that may be often encountered for correct identification of P. stuartii at the species level when using commercial identification systems, this probe may result useful for fast and reliable identification of P. stuartii strains for taxonomical, epidemiological and diagnostic studies

A MODIFIED MACCONKEY MEDIUM WHICH ALLOWS THE RECOGNITION OF ENTEROBACTERIACEAE FROM OTHER GRAM-NEGATIVE BACTERIA ON PRIMARY CULTURE PLATES

A selective-differential medium is proposed for the preliminary recognition of Enterobacteriaceae from other Gram-negative bacteria directly on the primary isolation plates. The modified medium, named MCPB, is constituted by a MacConkey agar base with 6-benzoyl-naphthyl-phosphate (as a substrate for the phosphatase activity), and a small amount of dextrose and aniline blue. On the MCPB medium all the enterobacteria and Xanthomonas maltophilia were phosphatase positive and developed red (lactose-negative), or violet (lactose-positive), colonies; all other Gram-negative bacteria formed colourless colonies. Therefore, it is possible to recognize enterobacteria from non-enteric bacteria on the basis of the growth colour and correctly choose the identification kit (either for enterobacteria or for non-enteric bacteria) without the aid of supplemental tests

EFFECT OF SLIME PRODUCTION ON THE ANTIBIOTIC SUSCEPTIBILITY OF ISOLATES FROM PROSTHETIC INFECTIONS

[No abstract available

DOUBLE SUGAR-TYROSINE MEDIUM IMPROVES O-1 PHAGE SALMONELLA SCREENING

A modification of the procedure for O-1 phage Salmonella screening is presented. The novel method is based on the use of two media, i.e., a new medium (double sugar-tyrosine [DST]), which permits the combination of adonitol and sucrose fermentation and tyrosine clearing tests, and the previously described o-nitrophenyl-beta-D-galactopyranoside urease indole medium. In comparative trials, the new procedure and the conventional one were used to screen for Salmonella isolates from 553 lactose-negative strains of members of the family Enterobacteriaceae. The O-1 phage test, performed on DST medium, recognized the same number of phage-susceptible Salmonella strains as did the standardized method; however, it permitted the correct identification of a greater number of phage-resistant strains for discard (95.6 versus 85.3%). In particular, DST medium presented a higher efficacy than triple sugar iron agar (which is the corresponding medium in the reference procedure) in correctly identifying phage-negative cultures for discard (69.1 versus 28.5%)

Incidence of antibiotic resistance in the microbial community of the Tiber River (Rome)

The increased antibiotic use (for humans/animals, in clinics and agriculture) leads to the propagation of resistant variants in microbial communities. This phenomenon has been verified for bacterial communities in water and sediments of Tiber River. The heterotrophic aerobic isolates were checked for resistance to ampicillin, chloramphenicol, streptomycin, sulfadimethoxine and tetracycline. From 1 to 5 resistances were found in more than 80% of isolates. Sulfadimethoxine and tetracycline were ascertained to be the most and the least diffuse resistances, respectively. Resistance incidence is independent from the variation in total microbial count. Multiresistance was also observed, and 5-antibiotic-resistant isolates were mainly found in sediments. The resistance pattern has been explained in term of use and persistence of the different antimicrobial