The protection of invertebrates, fish, and vascular plants against inorganic mercury poisoning by sulfur and selenium derivatives.

Protection of organisms against mercury (Hg) poisoning is most commonly associated with the antagonistic effects of selenium (Se)-compounds against mercury alkyls in higher animals. This study shows that there is no consistent difference among Periodic Group VIA derivatives including S(IV), S(II) organic, Se (IV), Se (II) organic, possibly Se VI, as well and Te (IV) in their ability to protect against mercury poisoning. The organisms used in assays were: Coleus explants (leaf abscission); turnip (germination); pea (growth inhibition and Hg uptake); a planarian (regeneration); the brineshrimp (excystment, phototaxy); the mealworm larva Tenebrio (metamorphosis) and the fish "tilapia" (survival, Hg uptake). Thiamine was the most effective of the Group VIA derivatives against the widest spectrum of organisms and test systems. In planarian regeneration, it was active where S and Se compounds failed. The most unexpected observation was the hastening of insect metamorphosis by HgCl2 and the enhancement of that effect by thiamine.

Preservation of ATP in hypersaline environments.

High concentrations of particulate ATP were found in the anoxic brines of the Orca Basin and East Flower Garden, Gulf of Mexico. Other measurements indicative of growth and respiration suggested that the microbial community in the brines was inactive, but somehow the ATP associated with the cells persisted. Conceivably, when cells growing just above the interface sank into the brine, the increased osmotic stress could elicit an osmoregulatory response resulting in increased ATP. It was also possible that hydrolytic enzymes were inactivated, resulting in the preservation of ATP. Experiments in which a culture of marine bacteria was suspended in menstrua of different salinities comparable to those found across the Orca Basin interface revealed that as salinity increased, ATP increased three- to sixfold. Within 24 h the ATP fell to its initial level and remained at that concentration for 3 days, at which time the experiment was terminated. In contrast, the control suspensions, at a salinity of 28% (grams per liter) had 1/10th of the initial ATP concentration when the experiment was ended. Cells were also exposed to killing UV irradiation, enabling us to demonstrate with absolute certainty that cellular ATP could be preserved. At the end of the experiment, the viable component of the population was reduced by orders of magnitude by UV irradiation, but the ATP levels of the cells suspended in brine did not decrease. In certain environments it appears that the conventional analytical tools of the microbial ecologist must be interpreted with caution.

Ultrastructural localization of uranium biosorption in Penicillium digitatum by stem X-ray microanalysis.

When Penicillium digitatum Saccardo cultures are exposed to aqueous solutions containing soluble uranium salts, considerable amounts of this element are accumulated in the fungal mycelium. The accumulated uranium is retained after thorough rinsing with distilled water but is removed by alkali carbonate solutions. Analysis of thick sections (0.5 microm) of the fungal hyphae with TEM, after incubation in UO(2)Cl(2) solutions of varying concentrations under both light and dark conditions, revealed conspicuous crystal-like deposits in UO(2)Cl(2)-exposed hyphae, but none in the control hyphae. Thick sections were necessary for crystal visualization. Using energy-dispersive X-ray analysis, uranium was detected as the only heavy element in these crystals. Uranium crystal biosorption was localized on the outside surface of the hyphal cell wall (following short exposures to relatively low uranium concentrations) or inside the cell wall (following long exposure to relatively high uranium concentrations). In some cases, crystal-like deposits of uranium salts were located on the outside surface as well as inside the cell.

Trends in birth defects for a Hawaiian population exposed to heptachlor and for the United States.

The 1980-1982 milk supply contamination on the island of Oahu, Hawaii, by the insecticide heptachlor offered an opportunity to investigate the possible human teratogenicity of this organochlorine. An analysis of incidence rates for 23 major congenital malformations, derived from hospital-generated data collected by the Birth Defects Monitoring Program of the Centers for Disease Control, failed to show any remarkable rate increase on Oahu in 1981-1983, based on comparisons with the rates for previous time periods on this island and with the rates for two unexposed populations (the other Hawaiian islands and the total U.S.). A rise in the rates of cardiovascular malformations and hip dislocation was apparent but antedated the exposure. These results suggest that no major rate increase for malformations recognized at birth resulted from the heptachlor contamination on Oahu. However, misclassification of exposure status in this study may have obscured a more moderate effect.

Short-term and long-term clinostat and vibration-induced biochemical changes in dwarf marigold stems.

Stems of 21-day dwarf Marigold plants cultivated on the clinostat were compared with plants cultivated on vertical axis rotators ("vibrational controls") and stationary controls for long-term changes in cell wall composition. Stems of 21-day plants grown under stationary conditions and subsequently exposed to the clinostat for 24 hours were also analyzed. Among the long-tern markers, calciun, lignin, and protein-bound hemicellulose (possibly cell wall glycoprotein) clearly differentiated the effects of vibration from those of the clinostat. Short-term differential responses included rate of ethylene production, nastic movement and peroxidase activity of the cell wall, but not of the protoplast.

An extraterrestrial habitat on Earth: the algal mat of Don Juan [correction of Jaun] Pond.

On the edge of Don Juan Pond in the Wright Valley of Antarctica lies a mat of mineral and detritus cemented by organic matter. In spite of a CaCl2 concentration of about 33% (w/v), the mat contains Oscillatoria and other cyanobacteria, unicellular forms, colonial forms rich in carotenoids, and diatoms. Bacteria are rare; fungal filaments are not. Oscillatoria showed motility but only at temperatures <10 degrees C. Acetone extracts of the mat and nearby muds yielded visible spectra similar to those of laboratory grown O. sancta, with 50- to 70-fold molar ratio of chlorophyll a to b. Although rare, tardigrades were also found. The algal mat had enzymatic activities characteristic of peroxidase, catalase, dehydrogenase, and amylase. Cellulose, chitin, protein, lipid and ATP were present. Previously, algae in the Wright Valley have been described in melt water, not in the brine itself. Wright Valley has been used as a near sterile Martian model. It obviously contains an array of hardy terrestrial organisms.

Removal of Uranium(VI) from Solution by Fungal Biomass and Fungal Wall-Related Biopolymers.

Penicillium digitatum mycelium can accumulate uranium from aqueous solutions of uranyl chloride. Azide present during the uptake tests does not inhibit the process. Killing the fungal biomass in boiling water or by treatment with alcohols, dimethyl sulfoxide, or potassium hydroxide increases the uptake capability to about 10,000 parts per million (dry weight). Formaldehyde killing does not enhance the uranium uptake. The inference that wall-binding sites were involved led to the testing of uranium uptake by chitin, cellulose, and cellulose derivatives in microcolumns. All were active, especially chitin.

Mercury content of equisetum plants around mount st. Helens one year after the major eruption.

The mercury content of young Equisetum plants collected around Mount St. Helens was higher in the direction of Yakima and Toppenish, Washington (northeast to east-northeast), than at any other compass heading and was about 20 times that measured around Portland, Oregon. The increase in substratum mercury was not as pronounced as that in plants but was also higher toward the northeast, the direction taken by the May 1980 volcanic plume.

Enzyme-mimicking properties of silicates and other minerals.

The adsorptive and/or catalytic properties of clays, silicates in general, and other minerals are well known. More recently, their probable role in prebiotic syntheses of bio-organic compounds has become a matter of record. We demonstrate that, in addition to their role in de novo formation of important biomolecules, clays, micas, fibrous silicates and other minerals mimic the activities of contemporary enzymes including oxidases, esterases, phosphatases and glucosidases. The existence of such capabilities in substances likely to be represented on the surfaces of Earth-like planets may offer a challenge to the technology and design of remote life detection systems which must then distinguish between bona fide biological chemistry and mineral-base pseudometabolism. It also raises questions about the importance of mineral surfaces in post-mortem transformations of organic metabolites in our own biosphere.

Effects of salts and temperatures on post-irradiation growth of Penicillium exposed to ultraviolet.

The growth of Penicillium notatum colonies after UV irradiation of dried mycelium or spores was studied in relation to post-irradiation temperature and salt environment. Dried mycelium and spores behaved differently with respect to sensitivity to temperature, salts and UV, especially the latter. Threshold inhibitory doses for spores were modified markedly either at 4 degrees C or in magnesium and calcium chlorides. It is suggested that these temperature and salt effects are related to prevention of photochemical membrane damage.

Further studies on the environmental capabilities of fungi: interactions of salinity, ultraviolet irradiation, and temperature in Penicillium.

A strain of Penicillium currently under study in this laboratory has revealed some unexpected features in response to salts and UV-radiation. These responses include: (a) stimulation of growth by one molar NaCl and KCl at 23 degrees but not at 5 degrees C, (b) total inhibition by LiCl and RbCl at 5 degrees but not at 23 degrees C, (c) stimulation by 254 nm radiation (2 x 10(6) erg cm-2 min-1, 30-90 minutes) at 23 degrees and 5 degrees C, and (d) very elevated growth rates at 23 degrees after incubation at 5 degrees C.

Gravity and land plant evolution: experimental induction of lignification by simulated hypergravity and water stress.

The ability to lignify cell walls has long been associated with the upright condition and sometimes massive body of the land plant, and gravitational regulation of lignification has been demonstrated by clinostat/centrifuge techniques. Previous centrifuge experiments were conducted using plants in the early stages of growth, hence already programmed for immediate lignification. Elodea, an aquatic Angiosperm long believed to be incapable of lignification synthesizes lignin or lignin-like phenolics during 6 days incubation at 80 g . Yields in some cases exceeded stationary controls by as much as 300%. Supporting data were obtained using bean cotyledons. Exposure to 80 g induced lignification in extra-vascular tissue along with vascular lignin deposits. The loss of a buoyant medium also deprived early land plants of unlimited water: the lignin content in cucumber seedlings grown in water is reduced 50% or more relative to pot grown plants but water stress elevates lignin content as much as 100%. This suggests that the water status of the land environment may have provided a "backup" or "reinforcement" signal for an adaptive axial support system.

Growth of fungi in NaCl-MgSO4 brines.

Long-term studies have shown that common fungi of the Penicillium-Aspergillus group can be grown in a variety of brines or on moist salt crystals, simulating a range of natural terrestrial habitats such as salt flats, or special water-bodies such as the Dead Sea. In general, salt media rich in KCl are favored over other alkali halides; the media become more selective as the salt concentration rises and nutrient requirements become more complex. We here demonstrate that media which resemble the Dead Sea salt mix can support the growth of selected fungal strains, even in the absence of reduced organic nutrients other than glucose. Such media may serve as models for localized microhabitats on Mars.

The effects of temperature, salinity, and other factors on the growth and formation of UV-absorbing substances by the fungus Aspergillus.

Aspergillus niger can be grown at 263 degrees K in a KCl-saturated medium with glucose as the sole C-source. In spite of their similarities K and Rb-ions are not equivalent, but unlike Na-ion, both support growth. The dependency of growth rate upon the nitrogen source is peptone > NH4+ > NO3-. In KCl-medium at 263 degrees K, the production of UV-absorbing aromatic substances normally elaborated by this fungus and soluble in alcohol is reduced more than 20-fold as indicated by comparisons of total absorbance per unit dry weight in the range 210-280 nm. Both the low temperature and salt contribute to alterations in the chemistry of these potential photoprotectants.

Vulcanism, mercury-sensitized photo-reactions and abiogenetic synthesis: a theoretical treatment.

Attention is called to the photodynamic and thermodynamic properties of Periodic Group IIb elements, most notably Hg, as they relate to ultra-violet sensitization in organic chemical reactions. The energy levels of 6(1) P1 and 6(3) P1 resonance states and the high vapor pressure ((greater than 10(-3) mm) of the metal at temperatures as low as 293 K bring Hg with the range of bond dissociation energies in most organic molecules and many inorganics. These capabilities considered together with recent evidence for Hg emission as a regular part of volcanic and geothermal processes provide the basis for our proposal that Hg-sensitized ultraviolet photo-reactions may have played a significant part in abiogenetic organic synthesis on the primative earth.

Thallium antagonism toward potassium dependent systems.

When a number of Group 1A chlorides were added to yeast solutions which were inhibited by 20 mM Tl+, the greatest restorative effect was shown by KCl, with a lesser effect by NH4Cl. Sodium, rubidium and cesium chlorides had no significant effect on Tl+-inhibited CO2 production, and lithium chloride inhibited the system even further. Removal of potassium ions by dialysis reduced CO2 production by about 70% and the restorative effect of potassium was markedly reduced when this ion was added in the presence of thallium.

A selective role for potassium in the phytotoxicity of thallium.

The presence of K-ion prevents inhibition of Plantago maritima seed germination and Asperigillus flavus mycelial growth by Tl-ion. The effect of potassium could not be replaced by Na-ion in either system. Aspergillus was cultured in a medium low in light metal ions (Na+ and K+), and its growth was enhanced quantitatively by addition of Kminus but not Na-ions. Growth without added potassium was inhibited severely by Tl-ions, whereas K-enhanced growth was not. It is suggested that the thallium-potassium interaction is specific involving competition between ions of quite similar charge and radius.