Survival of pathogenic bacteria in various freshwater sediments

Four human-associated bacteria, Pseudomonas aeruginosa, Salmonella newport, Escherichia coli, and Klebsiella pneumoniae, were tested for survival in five freshwater sediments. Bacterial survival in continuous-flow chambers was monitored over 14-day periods on sediments ranging from organically rich high-clay fractions to organically poor sandy fractions. Bacterial die-off ranged from 1 to 5 orders of magnitude in sediments. E. coli survived as long as or longer than S. newport. P. aeruginosa and K. pneumoniae tended to survive longer than E. coli. Survival of E. coli and S. newport was greater in sediments containing at least 25% clay. Good reproducibility allowed the development of linear models to describe die-off rates.     

Antibody-induced association between discrete regions of HLA class I and II antigens

The anti-HLA-DR + DP monoclonal antibody (MoAb) CR11-462 was unexpectedly found to cross-inhibit the binding to B lymphoid cells of the anti-HLA Class I MoAb CR10-215 and CR11-115. The latter two antibodies recognized the same or spatially close antigenic determinant. The cross-blocking of anti-HLA Class I MoAb CR10-215 and CR11-115 by MoAb CR11-462 reflects neither its contamination by anti-HLA Class I antibodies nor its cross-reactivity with HLA Class I antigens. On the other hand, the cross-blocking appears to reflect redistribution of HLA Class II antigens by the MoAb CR11-462, since the MoAb CR10-215 and CR11-115 are not susceptible to blocking when lymphoid cells are treated with 0.025% glutaraldehyde or are coated with Fab' fragments of the MoAb CR11-462. Furthermore, immunoprecipitates from B lymphoid cells preincubated with the MoAb CR11-462 before solubilization contain HLA Class I antigens. Therefore, these results have shown for the first time an antibody-induced association between discrete regions of HLA Class I and Class II antigens on the membrane of B lymphoid cells.     

Expression of HOX homeogenes in human neuroblastoma cell culture lines

Mammalian genes containing a class-I homeobox (HOX genes) are highly expressed in the embryonic nervous system. As a first step towards the molecular analysis of the role these genes play in neural cells, we studied the expression of four human HOX genes in five neuroblastoma (NB) cell lines - SK-N-BE, CHP-134, IMR-32, SK-N-SH and LAN-1 - during the process of differentiation induced by treatment with retinoic acid (RA). The four genes, HOX1D, 2F, 3E and 4B, located at corresponding positions in the four HOX loci, share a high degree of sequence similarity with the Drosophila Deformed homeotic gene and constitute a homology group, group 10. One of these genes, HOX1D, is not expressed in the cells used, whereas the other three are highly expressed in untreated and RA-induced NB cells, even though the expression pattern in the various lines is slightly different for the three genes. Our analysis reveals a complex and specific expression pattern in these lines, paving the way to an identification of different NB-cell populations by means of specific HOX gene expression schemes. On the other hand, in every line studied, morphological maturation toward a neuronal differentiated phenotype appears to be associated with increased HOX gene expression.     

Importance of some factors on the dimorphism of Candida albicans

The passage between the yeast and mycelial forms of Candida albicans B 311-10 was studied by using the minimal syntehtic medium of Shepherd et al. [19] modified without biotin and with low glucose concentrations. It was observed that biotin, aminoacids and particularly pH are not important factors in the dimorphism of C. albicans. The only factor of notable importance in the passage of yeast form to mycelial form in C. albicans was glucose concentration.     

Deletion 2q31.3→2q33.3: gene dosage effect of ribulose 5-phosphate 3-epimerase

In a new case of interstitial del(2q), measurements of ribulose 5-phosphate 3-epimerase activity suggested that the locus for this enzyme might be localized to the subregion 2q32q33.3.     

Antibacterial activity of rufloxacin in theStaphylococcus aureus rat granuloma pouch model

The protective effects of rufloxacin againstStaphylococcus aureus-induced infections were compared with those of ciprofloxacin in the granuloma pouch model in the rat. Two strains with different in vitro sensitivity to the drugs were studied. Rufloxacin concentrations persisted longer than ciprofloxacin in the exudate in the pouch cavity and were about eight times higher. Equal doses of rufloxacin and ciprofloxacin had similar antibacterial activities. However, rufloxacin inhibitedStaphylococcus aureus bacterial growth significantly longer than did ciprofloxacin.     

Surface spreading of synaptonemal complexes in three isopod crustacean species

The technique of whole mount spreading is used to investigate the SC of three species of Asellidae (isopod crustaceans), Asellus aquaticus, Proasellus coxalis and Proasellus meridianus, which display considerable differences in genomic DNA content.The three species, originally considered to belong to the same genus Asellus, were subsequently assigned to two separate genera: Asellus and Proasellus. The SCs of the three species differ in morphological details related to the shape of the centromere region, the attachments to the nuclear envelope, the width of the central region and the presence of twists of the lateral elements. Furthermore, they display some differences in the degree of compaction of genomic DNA in the mitotic chromosomes. The greatest differences are found between A. aquaticus and P. coxalis, while P. meridianus has several features in common with either species.