Influence of fulvic acid on the removal of trace concentrations of cadmium(II), copper(II), and zinc(II) from water by alum coagulation

The effectiveness of Cu²⁺, Cd²⁺ and Zn²⁺ removal from solution by alum coagulation was measured with fulvic acid present and absent. A factorial experimental design and analysis of variance were used to determine the effect on metal ion removal of the individual variables pH, metal ion concentration, alum concentration and fulvic acid concentration and their combinations. The variable levels model water treatment plant conditions. Metal ion losses up to 96% for Cu²⁺. 59% for Cd²⁺ and 82% for Zn^z+ were measured in the presence of fulvic acid. In its absence the maximum metal ion losses observed were 93%, 14% and 53% for Cu²⁺, Cd²⁺ and Zn²⁺ respectively. Fulvic acid enhances metal ion removal under most experimental conditions. The practical implication of the results is that strong complexes between natural water organic matter and metal ions enhance their removal by the alum coagulation process.     

Mucosal iron retention and plasma iron absorption in the duodenum and jejunum of dogs

The electroretinograms (ERGs) from 14 patients with proliferative diabetic retinopathy were recorded before and after peripheral retinal ablation by photocoagulation. It was expected that the ERG would be reduced in amplitude in proportion to the area of retina destroyed by the treatment. The ablation treatment, carried out in a standard manner in each patient, resulted in a decrease of ERG amplitude that varied from 10 to 95% among the patients, and caused an increase in ERG latency and implicit time in several patients. This suggests a wide variability in the area of retina affected by the treatment, and the possibility of an effect of the procedure on adjacent untreated retina in some diabetic patients.     

beta-Lactamase activity in mycobacteria including Mycobacterium avium and suppression of their growth by a beta-lactamase-stable antibiotic

beta-Lactamase has been reported from only a few mycobacteria. It is widely assumed that Mycobacterium avium strains do not contain the enzyme, but earlier assays were done using insensitive methods. Thus the beta-lactamase activity in cell-free extracts of ten selected strains of mycobacteria, including four strains of M. avium, was determined using a highly sensitive spectrophotometric method. The results showed that all the mycobacteria tested possess the enzyme, which explains their resistance to beta-lactam antibiotics. However, some of the bacteria differed from others in the action of the inhibitors, clavulanate, sulbactam and tazobactam against their beta-lactamases. Growth of the mycobacteria was suppressed by novel combinations of the beta-lactam/beta-lactamase-inhibitors, and by a new beta-lactamase-stable cephalosporin, Cefepime (aminothiazolyl methoxyimino cephalosporin). The results presented, as well as reports of previous studies in vivo, suggest that the intracellular growth of the bacilli or the high partition coefficient of a beta-lactamase inhibitor such as sulbactam does not impede the antimycobacterial action of these compounds.     

Complete sequence of the bithorax complex of Drosophila

The bithorax complex (BX-C) of Drosophila, one of two complexes that act as master regulators of the body plan of the fly, is included within a sequence of 338,234 bp (SEQ89E). This paper presents the strategy used in sequencing SEQ89E and an analysis of its open reading frames. The BX-C sequence (BXCALL) contains 314,895 bp obtained by deletion of putative genes that are located at each end of SEQ89E and appear to be functionally unrelated to the BX-C. Only 1.4% of BXCALL codes for the three homeodomain-containing proteins of the complex. Principal findings include a putative ABD-A protein (ABD-AII) larger than a previously known ABD-A protein and a putative glucose transporter-like gene (1521 bp) located at or near the bithoraxoid (bxd), infra-abdominal-2 (iab-2) boundary on the opposite strand relative to that of the homeobox-containing genes.     

Response of epiphytic diatom communities from the tailwaters of glen Canyon Dam,Arizona, to elevated water temperature

The composition of epiphytic diatom communities from the cold tailwaters (12°C) of Glen Canyon Dam, Arizona, was analysed after a 2 wk incubation period at 12°C, 18°C and 21°C. There was a significant change in diatom composition between 12°C and 18°C, while no significant changes occurred between 18°C and 21°C. This suggests that a temperature threshold exists between 12°C and 18°C for the diatom flora in the tailwaters of Glen Canyon Dam. At the two higher water temperatures, smaller and closely adnate taxa became more important numerically than larger, upright, cold water stenotherms. The potential importance of this compositional shift in epiphytic diatoms on macroinvertebrate grazers has management implications regarding different release programs from reservoirs.