Effects of pharmaceutical wastes on growth of microalgae

The purpose of this work was to assay samples of waste material from Puerto Rican pharmaceutical industries for inhibition of growth of algae. Two samples (noted as I and II) supplied to us were tested for toxicity to six microalgae. The test organisms, two blue-green algae, two green algae, and two diatoms [r]epresent three major divisions of algae.University of Texas Marine Science InstituteMarine Scienc

Studies of the phosphorus deficient state in the blue-green alga Anacystis nidulans

The normal level of phosphorus in Anacystis nidulans is approximately 3.7 μg Pi/mm³ cells. This value falls to 0.5 μg Pi/mm³ cells under prolonged starvation. However, even under this condition complete viability is indicated and also a slow rate of cell division. With cells containing approximately 1.5 μg Pi/mm³ cells a rapid dark uptake (15 minutes) of 0.8 μg Pi/mm³ cells was found. Data obtained in the rapid dark fixation suggest 1) that the binding of phosphorus is a specific metabolic process, and 2) that approximately 25% of the total normal cellular phosphorus is possibly bound on these sites. Light had little effect on this first phase of phosphate uptake. The subsequent uptake to the normal phosphorus content per cell required light and nitrogen. Coincident with the rapid dark phosphate incorporation, synthesis of ATP began and continued, rising far above the level of normal cells in light. Normal cells in dark also showed an increase in ATP content but not nearly as great as in phosphorus deficient cells. The reason(s) for the rise in ATP is not understoodPlant Biolog

A study of halotolerance in blue-green algae

General characteristics of blue-green algal halotolerance were studied by growth experiments and selected analyses. Variation in NaCl concentration was used to mimic salinity. Marine isolates were more halotolerant (8 to 10% NaCl) than non-marine isolates (2% NaCl). Although growth experiments showed NaCl saturation at 1 mg/1 for non-marine isolates and 100 mg/1 for marine isolates, the higher NaCl requirements of marine bacteria (18 g/1) or halophilic bacteria (50 to 200 g/1) were not seen in blue-green algae. Intracellular Na+ values were affected by washing; however, bound- K+ values for both marine and fresh-water blue-greens ranged from 1 to 3 μg/mg cells. The reversal of a KCI-inhibition of growth (60 g/1) with small additions of NaCl (1 g/1) indicated a specific Na+ function. This was also implied by the retention after washing of ²²Na+ (0.3 μg/mg cells) by Agmenellum quadruplicatum (PR-6), a marine coccoid blue-green alga. High concentrations of NaCl apparently inhibit growth more by ionic (Na+) stress than by osmotic stress. Changes in light, temperature, or composition of the basal medium failed to alleviate this stress. In contrast to marine bacteria, cells of PR-6 grown in Medium ASP-2 + 90 g NaCl/1 did not undergo lysis when suspended in distilled water. However, viability of cells grown in ASP-2 + 90 g NaCl/1 decreased rapidly compared to cells grown in ASP-2 + 18 g NaCl/1. Cells of PR-6 grown in ASP-2 + 90 g NaCl/1 were larger than normal, formed chains (3 to 16 cells), and appeared bleached. Analyses of such cells revealed an overall decrease in fatty acids, hydrocarbons, and pigment levels. Electron micrographs showed changes in cellular lamellar systems. These data imply that a better understanding of halotolerance may be obtained by further study of NaCl effects on cellular membranes and photosynthetic lamellae. The photosynthetic rate of PR-6 cells was immediately depressed when the cells were transferred from 18 g NaCl/1 to 70 g NaCl/1 medium. When held in the latter for several hours the rate recovered and approached the initial photosynthetic rate maintained before NaCl-shock. This phenomenon was never seen with non-marine isolates. The explanation may lie in the ability of the cell to adjust to sudden Na+ increase via an ion (Na+) pump, for example adenosine triphosphatase (ATPase). Subsequent assays showed more ATPase activity in a marine isolate than in a non-marine isolate. It is suggested that marine blue-green algal isolates are characteristically more halotolerant, perhaps by selection, than fresh-water forms. This difference may be due in part to inherent capacity of the cell to extrude Na+. Alternatively, in fresh-water forms the Na+ sites are more Na+ sensitive than in marine formsEcology, Evolution and Behavio

A Massive Expansion of Effector Genes Underlies Gall-Formation in the Wheat Pest Mayetiola destructor

Gall-forming arthropods are highly specialized herbivores that, in combination with their hosts, produce extended phenotypes with unique morphologies [1]. Many are economically important, and others have improved our understanding of ecology and adaptive radiation [2]. However, the mechanisms that these arthropods use to induce plant galls are poorly understood. We sequenced the genome of the Hessian fly (Mayetiola destructor; Diptera: Cecidomyiidae), a plant parasitic gall midge and a pest of wheat (Triticum spp.), with the aim of identifying genic modifications that contribute to its plant-parasitic lifestyle. Among several adaptive modifications, we discovered an expansive reservoir of potential effector proteins. Nearly 5% of the 20,163 predicted gene models matched putative effector gene transcripts present in the M. destructor larval salivary gland. Another 466 putative effectors were discovered among the genes that have no sequence similarities in other organisms. The largest known arthropod gene family (family SSGP-71) was also discovered within the effector reservoir. SSGP-71 proteins lack sequence homologies to other proteins, but their structures resemble both ubiquitin E3 ligases in plants and E3-ligase-mimicking effectors in plant pathogenic bacteria. SSGP-71 proteins and wheat Skp proteins interact in vivo. Mutations in different SSGP-71 genes avoid the effector-triggered immunity that is directed by the wheat resistance genes H6 and H9. Results point to effectors as the agents responsible for arthropod-induced plant gall formation