A note on the survival of Legionella pneumophila in stagnant tap water

Tap water, from an experimental hot water system, containing a known virulent strain of Legionella pneumophila was stored in screw-capped bottles for 14 months. Viable counts showed survival of L. pneumophila and at least three other bacterial species. This reinforces the view that L. pneumophila can survive in stagnant water foatively long periods of time.     

The persistence of Legionella pneumophila in non-sterile, sterile and artificial hard waters and their growth pattern on tap washer fittings

Simultaneous experiments were performed with sterilized and non-sterile water and an artificial hard water. After seeding with an environmental isolate of Legionella pneumophila numbers in the sterile land hard water decreased rapidly and colonization of various tap washer fittings failed to take place. Adhesion and growth of an environmental isolate of L. pneumophila to washers in non-sterile tap water was followed over a 4-month period with fluorescein-labelled antibody and by scanning electron microscopy. After adherence the individual cells appeared to divide to form chains which spread over the surfaces. Organisms other than legionellas were also present and a complex colonization matt was formed which was embedded in a protective coat of slime and debris. The numbers of L. pneumophila recovered from the water were highest between 4 and 7 weeks but they could still be cultivated after 4 months.     

Industrial contributions to desertification in South America

Degradation of tropical lands has a grim inevitability. This is true of semi-arid and seasonal ecosystems as it is of the rainforests, whose plight has been the principal focus of attention in recent years. The broad belt of savanna-like vegetation in central South America has suffered an accelerating decline in productivity due to overclearing and overgrazing, a process that can be traced directly to the industrialization of Europe in the 19th century. The remorseless slide towards unproductivity need not be slow: a mere 50-100 years seems more than adequate, even for the more robust landscapes. With careful management however, some of these lands are slowly recovering.     

Why do anemonefishes inhabit only some host actinians?

Synopsis The 25 species ofAmphiprion and one ofPremnas (family Pomacentridae) are obligate symbionts of 10 species of facultatively symbiotic sea anemones. Throughout the tropical Indo-West Pacific range of the relationship, a fish species inhabits only certain of the hosts potentially available to it. This specificity is due to the fishes. Five fishes occupy six sea anemone species at Lizard Island, Great Barrier Reef, Australia.Entacmaea quadricolor harborsP. biaculeatus, A. melanopus andA. akindynos. Adults ofPremnas occur deeper than about 3 m in large, primarily solitary actinians; juveniles may occupy peripheral members ofEntacmaea clones in shallow water. Specimens ofA. melanopus live exclusively in clonal anemones, which are found no deeper than 3 m. Most individuals ofA. akindynos inEntacmaea are juveniles, occurring shallow and deep, in solitary anemones or at the margins of clones. Interspecific as well as intraspecific social control of growth may be responsible for keeping fish small at clone fringes. Conspicuous specimens ofE. quadricolor depend upon their anemonefish to survive. Actinians cleared of symbionts disappeared within 24 h, probably having been eaten by reef fishes.Entacmaea, the most abundant and widespread host actinian at Lizard Island and throughout the range of the association, is also arguably the most attractive to anemonefishes. I believe its vulnerability to predation was a factor in its evolving whatever makes it desirable to fishes. Experimental transfers pitted fish of one species against those of another, controlling for ecophenotype of host, and sex, size and number of fish. Competitive superiority was in the same order as abundance and over-all host specificity:P. biaculeatus, A. melanopus, A. akindynos. At least three factors are necessary to explain patterns of species specificity - innate or learned host preference, competition, and stochastic processes.     

A high affinity,calmodulin-responsive (Ca2+ + Mg2+)-ATPase in isolated bone cells

Although acute alterations in Ca²⁺ fluxes may mediate the skeletal responses to certain humoral agents, the processes subserving those fluxes are not well understood. We have sought evidence for Ca²⁺-dependent ATPase activity in isolated osteoblast-like cells maintained in primary culture. Two Ca²⁺-dependent ATPase components were found in a plasma membrane fraction: a high affinity component (half-saturation constant for Ca²⁺ of 280 nM, $\text{V}{}_{\mathrm{<mtext>max</mtext>}}$ of 13.5 nmol/mg per min) and a low affinity component, which was in reality a divalent cation ATPase, since Mg²⁺ could replace Ca²⁺ without loss of activity. The high affinity component exhibited a pH optimum of 7.2 and required Mg²⁺ for full activity. It was unaffected by potassium or sodium chloride, ouabain or sodium azide, but was inhibited by lanthanum and by the calmodulin antagonist trifluoperazine. This component was prevalent in a subcellular fraction which was also enriched in 5′-nucleotidase and adenylate cyclase activities, suggesting the plasma membrane as its principal location. Osteosarcoma cells, known to resemble osteoblasts in their biological characteristics and responses to bone-seeking hormones, contained similar ATPase activities. Inclusion of purified calmodulin in the assay system caused small non-reproducible increases in the Ca²⁺-dependent ATPase activity of EGTA-washed membranes. Marked, consistent calmodulin stimulation was demonstrated in membranes exposed previously to trifluoperazine and then washed in trifluoperazine-free buffer. These results indicate the presence of a high affinity, calmodulin-sensitive Ca²⁺-dependent ATPase in osteoblast-like bone cells. As one determinant of Ca²⁺ fluxes in bone cells, this enzyme may participate in the hormonal regulation of bone cell function.     

Requirements for antiribosomal activity of pokeweed antiviral protein

It has been known for some time that pokeweed antiviral protein acts by enzymatically inhibiting protein synthesis on eucaryotic ribosome systems. The site of this action is known to be the ribosome itself. In this paper we show that the pokeweed antiviral protein reaction against ribosomes is a strong function of salt concentrations, where 160 mM K⁺ and 3 mM Mg²⁺ retards the reaction, while 20 mM K⁺ and 2 mM Mg²⁺ allows maximum reaction rate. It is also shown, however, that an unidentified protein in the postribosomal supernatant solution, together with ATP, allows the ribosome to be attacked even in the presence of high salt. Kinetic analysis of the antiviral protein reaction has been carried out under both sets of conditions, and reveals that the turnover number for the enzyme is about 300–400 mol/mol per min. in each case. The K_m for ribosomes is 1 μM in the presence of low salt and 0.2 μM at higher salt in the presence of postribosomal supernatant factors plus ATP. The antiviral protein reaction is also shown to be pH dependent and is controlled by a residue with pK_a value of approx. 7.0, apparently a histidine. Stoichiometric reaction of the enzyme with iodoacetamide results in a significant loss of antiribosomal activity.     

Incidence of Infectious Drug Resistance Among Fecal Coliforms Isolated from Raw Sewage

Raw sewage was examined for the incidence of antibiotic-resistant coliforms present among both total and fecal coliforms. In both groups, it was found that approximately 3% of the coliform bacteria were resistant to two or more antibiotics. Of these organisms, 48% were capable of transferring all or part of their antibiotic resistance to an antibiotic-sensitive, F⁻, derivative of Escherichia coli K-12. Among the R factors identified, those conferring resistance to streptomycin-tetracycline, ampicillin-streptomycin-tetracycline, and ampicillin or ampicillin-streptomycin accounted for 23, 20, and 15%, respectively, of the total R factors detected. The data indicate a significant level of infectious drug resistance among the fecal coliforms of the urban population. The data indicate further that because of the high incidence of coliform bacteria found to be doubly resistant to streptomycin and tetracyline, the inclusion of these antibiotics in selective media used for routine total or fecal coliform counts may serve to identify domestic sources of pollution.     

Clinical Trial of Lincomycin Hydrochloride in Reiter's Disease

A double-blind trial comparing lincomycin hydrochloride (Mycivin) and placebo in 22 patients with Reiter''s disease showed no significant difference in clinical or laboratory findings between the two groups. It is concluded that lincomycin hydrochloride is no more effective than placebo in the treatment of Reiter''s disease.