The influence of cell surface properties of thermophilic streptococci on attachment to stainlesssteel

The quality of milk products is threatened by the formation of biofilms of thermophilicstreptococci on the internal surfaces of plate heat exchangers used in milk processing. Althoughattachment to stainless steel surfaces is one of the first stages in the development of a biofilm, themechanisms involved in attachment have not been reported. The cell surface properties of 12strains of thermophilic streptococci were examined to determine their importance in attachment tostainless steel surfaces. Hydrophobicity, extracellular polysaccharide production and cell surfacecharge varied between the different strains but could not be related to numbers attaching. Treatingthe cells with sodium metaperiodate, lysozyme or trichloroacetic acid to disrupt cell surfacepolysaccharide had no effect on attachment. Treatment with trypsin or sodium dodecyl sulphate toremove cell surface proteins resulted in a 100-fold reduction in the number of bacteria attaching.This result suggests that the surface proteins of the thermophilic streptococci are important intheir attachment to stainless steel.     

Seasonal reproductive cycles in three commercially exploited fishes from the slope waters off New Zealand

Reproductive cycles were investigated in orange roughy, Hoplostethus atlanticus , smooth oreo, Pseudocyttus maculatus , and black oreo dory, Allocyttus sp., from mid-slope waters (600–1300 m) around New Zealand from 1982 to 1985. Orange roughly displayed a mid-winter spawning period in July and August, whereas both dory species spawned in November and December. In all three species, the timing of spawning was consistent from year to year. Ovarian development in orange roughy and black oreo dory was found to be synchronous, with a single clutch of oocytes being matured for each spawning season. In males, testes of a given macroscopic stage were dominated by a single gamete stage, supporting the existence of a brief rather than prolonged spawning period. The possible relationship of spawning period to seasonal changes in the productivity of the surface water is discussed.     

Cytokine production in a model of wound healing: the appearance of MIP-1, MIP-2, cachectin/TNF and IL-1

Macrophages are essential for normal wound repair and many of their effects on healing wounds are likely to be mediated by the secretion of cytokines. This study examines the appearance of messenger RNA (mRNA) for cachectin/tumor necrosis factor (TNF), IL 1, and macrophage inflammatory proteins 1 and 2 (MIP-1 and MIP-2), as well as the mature peptides, in a model of wound healing using wound chambers. RNA for all four cytokines can be detected in wound inflammatory cells by polymerase chain reaction amplification throughout the first 7 days. Cachectin/TNF and IL 1 protein levels peaked on the first day after wound chamber implantation, and MIP-1 and MIP-2 were detected only on day 3. The data suggest that these cytokines participate in the early inflammatory response to wounding.     

Standardizing Immunohistochemistry: A New Reference Control for Detecting Staining Problems

A new standardized immunohistochemistry (IHC) control for breast cancer testing comprises formalin-fixed human epidermal growth factor receptor 2, estrogen receptor, or progesterone receptor peptide antigens covalently attached to 8-µm glass beads. The antigen-coated beads are suspended in a liquid matrix that hardens upon pipetting onto a glass microscope slide. The antigen-coated beads remain in place through deparaffinization, antigen retrieval, and immunostaining. The intensity of the beads’ stain provides feedback regarding the efficacy of both antigen retrieval and immunostaining. As a first report, we tested the sensitivity and specificity of the new IHC controls (“IHControls”). To evaluate sensitivity, various staining problems were simulated. IHControls detected primary and secondary reagent degradation similarly to tissue controls. This first group of IHControls behaved similarly to tissue controls expressing high concentrations of the antigen. The IHControls were also able to detect aberrations in antigen retrieval, as simulated by sub-optimal times or temperatures. Specificity testing revealed that each antigen-coated bead was specific for its cognate IHC test antibody. The data support the conclusion that, like tissue controls, IHControls are capable of verifying the analytic components of an immunohistochemical stain. Unlike tissue controls, IHControls are prepared in large bulk lots, fostering day-to-day reproducibility that can be standardized across laboratories.     

Variability in response to UV-B among species and strains of Metarhizium isolated from sites at latitudes from 61 degrees N to 54 degrees S.

The effects of irradiances of 920 and 1200 mW m(-2) (biologically effective weighted irradiance) were examined in 2 Metarhizium album strains, 26 M. anisopliae strains, 1 M. flavoviride strain, and 1 M. taii strain isolated from sites located at latitudes from 61 degrees N to 54 degrees S. Conidia were exposed to UV-B from 1 to 6 h and subsequently examined for relative percentage culturability. Total dosage received at the end of the exposure periods ranged from 3.3 to 19.9 kJ m(-2) for the lower irradiance and from 4.3 to 25.9 kJ m(-2) for the higher irradiance. Both the irradiance values and the doses are environmentally realistic and can be observed even in temperate regions. The relationships between latitude of origin and UV-B tolerance were compared for the two levels of irradiance for the data from 1 and 2 h exposure. Exposure to both irradiances drastically reduced the relative percentage culturability of all strains. Tolerance to UV-B varied widely among strains and high variation was observed for both irradiances after all periods of exposure. After 1 h of exposure, a difference between the two irradiance levels was detectable, and this difference was magnified at longer irradiations. A significant quadratic relationship of decreasing UV-B tolerance with increasing latitude was observed after exposure of 1 and 2 h. The shape of the relationship did not differ for the two levels of irradiance. Also, we studied the effect of 1200 mW m(-2) irradiance on conidial germination time in 1 M. album strain, 7 M. anisopliae strains, and 1 M. taii strain. Exposure to UV-B delayed the germination of surviving conidia of all strains. In general, the delay in germination was directly proportional to the dose.     

Molecular cloning of genes from Ruminococcus flavefaciens encoding xylanase and beta(1-3,1-4)glucanase activities

Clones expressing activity against xylan or beta(1-3,1-4)glucan (lichenan) were isolated from a library of Ruminococcus flavefaciens 17 DNA made in bacteriophage lambda EMBL3. Hybridization analyses indicated the recovery of four separate genes encoding xylanases that showed no detectable associated carboxylmethylcellulase activity. One of these genes was associated with clones that also expressed beta(1-3,1-4)glucanase and beta-xylosidase activities.     

DNA-binding properties of an adenovirus 289R E1A protein.

An adenovirus 2 289 amino acid (289R) E1A protein purified from Escherichia coli has been shown to interact with DNA by two independent methods. UV-crosslinking of complexes containing unmodified, uniformly 32P-labelled DNA and purified E1A protein induced efficient labelling of the protein with covalently attached oligonucleotides, indicating that the E1A protein itself contacts DNA. Discrete nucleoprotein species were also observed when E1A protein--DNA complexes were analysed by gel electrophoresis. Although the 289R E1A protein exhibited no significant binding to single-stranded DNA or to RNA, no evidence for its sequence-specific binding to double-stranded DNA was obtained with either assay. Identification of the sites of covalent attachment of 32P-labelled oligonucleotides by partial proteolysis of the crosslinked E1A protein indicated that the interaction of this protein with DNA is mediated via domain(s) in the C-terminal half of the protein. Such previously unrecognized DNA-binding activity is likely to contribute to the regulatory activities of this important adenoviral protein.     

Plasmid-associated transfer of tetracycline resistance in Bacteroides ruminicola

Tetracycline resistance was transferred at frequencies between 10(-7) and 10(-6) per recipient cell in anaerobic matings between two strains of the strictly anaerobic rumen bacterium Bacteroides ruminicola. The donor strain, 223/M2/7, was a multiple-plasmid-bearing tetracycline-resistant strain from the ovine rumen, and the recipient, F101, was a rifampin-resistant mutant of B14, a bovine strain belonging to B. ruminicola subsp. brevis. Resistance transfer could occur in the presence of DNase, but not in dummy mating mixtures in which filtrate from a donor culture replaced donor cells. Acquisition of tetracycline resistance by the recipient was accompanied by the appearance of a 19.5-kilobase pair plasmid (designated pRRI4) which was homologous with a plasmid of similar size and restriction pattern present in the donor strain. A transconjugant (F115) carrying pRRI4 was also able to act as a donor of tetracycline resistance and plasmid DNA in matings with another recipient. Derivatives of F115 that had spontaneously lost tetracycline resistance lacked detectable plasmid DNA. It is concluded that pRRI4 mediated the transfer of tetracycline resistance. Transfer of resistance was not detectably enhanced by pregrowth of the donor in medium containing tetracycline. Transfer of tetracycline resistance was not detected from 223/M2/7 to a strain, 23 belonging to B. ruminicola subsp. ruminicola.