Paleolimnological evidence for recent acidification of Big Moose Lake,Adirondack Mountains,N.Y. (USA)

Big Moose L. has become significantly more acidic since the 1950s, based on paleolimnological analyses of sediment cores. Reconstruction of past lakewater pH using diatom assemblage data indicates that from prior to 1800 to ca. 1950, lakewater pH was about 5.8. After the mid-1950s, the inferred pH decreased steadily and relatively quickly to about 4.6. Alkalinity reconstructions indicate a decrease of about 30 eq · l^-1 during the same period. There was a major shift in diatom assemblage composition, including a nearly total loss of euplanktonic taxa. Chrysophyte scale assemblages and chironomid (midge larvae remains also changed in a pattern indicating decreasing lakewater pH starting in the 1950s. Accumulation rates of total Ca, exchangeable and oxide Al, and other metals suggest recent lake-watershed acidification. Cores were dated using²¹⁰Pb, pollen, and charcoal. Indicators of watershed change (deposition rates of Ti, Si, Al) do not suggest any major erosional events resulting from fires or logging. Accumulation rates of materials associated with combustion of fossil fuels (polycyclic aromatic hydrocarbons, coal and oil soot particles, some trace metals, and sulfur) are low until the late 1800s-early 1900s and increase relatively rapidly until the 1920s–1930s. Peak rates occurred between the late 1940s and about 1970, when rates declined.The recent decrease in pH of Big Moose L. cannot be accounted for by natural acidification or processes associated with watershed disturbance. The magnitude, rate and timing of the recent pH and alkalinity decreases, and their relationship to indicators of coal and oil combustion, indicate that the most reasonable explanation for the recent acidification is increased atmospheric deposition of strong acids derived from combustion of fossil fuels.     

Manganese cycling in an acidic Adirondack lake

There is considerable interest in the chemistry of Mn in acidic waters because of its role in the generation of acid neutralizing capacity during reduction processes, as an adsorbent in element cycling, and as a potential toxicant to aquatic organisms. Temporal and spatial variations in the concentration of Mn were evident in acidic Dart's Lake (1.0–2.3 mol l^–1), located in the Adirondack Region of New York. Seasonal changes in pH and dissolved oxygen concentration had subtle effects on the chemistry and transport of Mn. Despite oversaturation with respect to the solubility of manganite during periods of stratification, vertical deposition of Mn was minimal. The conservative nature of Mn appears to be due to the acidic conditions in Dart's Lake.     

Lake-watershed acidification in the North Branch of the Moose River: Introduction

An integrated analysis of a terrestrial-aquatic ecosystem, the North Branch of the Moose River in the Adirondack region of New York, was conducted. This basin contains a large number of interconnected surface waters that exhibit marked gradients in pH and acid neutralizing capacity (ANC). As a result, the basin has been the focus of research activity, including the Regional Integrated Lake-Watershed Acidification Study (RILWAS). The objective of the current analysis was to use the North Branch of the Moose River as a case study to:

1. Evaluate processes regulating the acid-base chemistry of surface waters.
2. To assess the effects of surface water acidification on fish populations.

The observations of this study were consistent with the model of surface water acidification developed during the Integrated Lake-Watershed Acidification Study (ILWAS). The processes depicted in the original ILWAS simulation model were adequate to describe the acid-base chemistry of surface waters in the North Branch of the Moose River. However, the reduction of SO ₄ ^2? in lake sediments, a process not represented in the original model, proved to be a significant source of acid neutralizing capacity (ANC) for some of these waters. As a result, reduction processes were added to the model. Analysis of in-situ bioassay and survey data indicate that acid-sensitive fish species have disappeared from the more acidic areas of the basin over the last half century. Paleoecological analyses indicate that pH has decreased from the high 5's to about 5 in Big Moose Lake during this period. ILWAS model simulations indicate that the pH of Big Moose Lake would increase by at least 0.1 to 0.5 pH units (depending on the season) in response to a 50% reduction in total atmospheric S deposition. Considerable variability in processes regulating acid/base chemistry was evident in the North Branch of the Moose River. Therefore, regional assessments of past or possible future effects of acidic deposition require widespread application of ILWAS theory within the Adirondack region and other potentially acid-sensitive areas.     

Cloning of an Arabidopsis thaliana gene encoding 5-enolpyruvylshikimate-3-phosphate synthase: sequence analysis and manipulation to obtain glyphosate-tolerant plants

Summary 5-enolpyruvylshikimate-3-phosphate synthase (EPSPs), the target of the herbicide glyphosate, catalyzes an essential step in the shikimate pathway common to aromatic amino acid biosynthesis. We have cloned an EPSP synthase gene from Arabidopsis thaliana by hybridization with a petunia cDNA probe. The Arabidopsis gene is highly homologous to the petunia gene within the mature enzyme but is only 23% homologous in the chloroplast transit peptide portion. The Arabidopsis gene contains seven introns in exactly the same positions as those in the petunia gene. The introns are, however, significantly smaller in the Arabidopsis gene. This reduction accounts for the significantly smaller size of the gene as compared to the petunia gene. We have fused the gene to the cauliflower mosaic virus 35 S promoter and reintroduced the chimeric gene into Arabidopsis. The resultant overproduction of EPSPs leads to glyphosate tolerance in transformed callus and plants.     

Immunoaffinity-purified opiate receptor specifically binds the delta-class opiate receptor ligand, cis-(+)-3-methylfentanylisothiocyanate, SUPERFIT

Using an antibody generated against the opiate receptor on NG108-15 cells, we recently purified the putative receptor from this hybrid cell line. We herein report that the purified receptor complex specifically binds tritiated cis-(+)-3-methylfentanylisothiocyanate (SUPERFIT), with the predominant binding associated with a 58 kDa polypeptide chain. Consistent with these findings is the in situ labeling of a 58 kDa protein with [3H]SUPERFIT on NG108-15 cells.     

Comparative organization of nitrogen fixation-specific genes from Azotobacter vinelandii and Klebsiella pneumoniae: DNA sequence of the nifUSV genes.

In the facultative anaerobe Klebsiella pneumoniae 17 nitrogen fixation-specific genes (nif genes) have been identified. Homologs to 12 of these genes have now been isolated from the aerobic diazotroph Azotobacter vinelandii. Comparative studies have indicated that these diverse microorganisms share striking similarities in the genetic organization of their nif genes and in the primary structure of their individual nif gene products. In this study the complete nucleotide sequence of the nifUSV gene clusters from both K. pneumoniae and A. vinelandii were determined. These genes are identically organized on their respective genomes, and the individual genes and their products exhibit a high degree of interspecies sequence homology.     

The use of biochemical markers, serotype and fimbriation in the detection of Escherichia coli clones

Biochemical reactions, O and K serotypes and presence of P-fimbriae were analysed in 116 Escherichia coli strains isolated in blood cultures from patients with bacteraemia and in 99 faecal strains isolated from healthy individuals. By using biochemical typing, the strains could be grouped into six main clusters with similarity index less than 0.8 (Gower, 1971) and altogether 16 subclusters with similarity index 0.82-0.89. The most discriminating tests between the clusters were fermentation of D-tagatose, saccharose, salicin and sorbose. No single biochemical property could differentiate bacteraemic isolates from faecal strains, although strains isolated from blood were significantly more often found in certain subclusters, whereas other subclusters contained mainly control strains. Bacteraemic strains possessed P-fimbriae more often, especially strains isolated from patients with E. coli in the urine concomitantly with bacteraemia. Equally, no single reaction could separate P-fimbriated from non-P-fimbriated strains. D-Tagatose was fermented more often by the P-fimbriated strains; on the other hand, melibiose and lactose fermentation tests were less often positive. Certain O serotypes (O1, O4, O6, O7, O18 and O25) were more common among bacteraemic isolates than controls. K serotypes such as K1, K5 and K52 were also more frequent among blood isolates. We conclude that a combination of biochemical tests, fimbriation and serotyping might be used to identify potentially pathogenic clusters of E. coli.     

Cell matrix adhesion-related proteins VLA-1 and VLA-2: regulation of expression on T cells

The mitogens phytohemagglutinin (PHA) and concanavalin A inhibited the appearance of the very late activation antigen (VLA)-1, but did not inhibit VLA-2 expression on cultured activated T cells. In contrast to diminished VLA-1 expression, mitogen treatment caused increased cell surface expression of other activation antigens such as T10, HLA-DR, interleukin 2 (IL 2) receptor, and 4F2, and greater cell proliferation. Conversely, when T cells were not repetitively restimulated with mitogen, these less proliferative "postactivated" T cells had elevated VLA-1 expression. The diminished expression of VLA-1 caused by PHA was reversible since subsequent removal of mitogen was associated with increased VLA-1, paralleled by a decrease in interleukin 2 receptor levels. In addition to preventing or delaying the initial appearance of VLA-1, PHA stimulation also was somewhat effective in causing the disappearance of VLA-1 already present, especially on recently established cultures. However, cultures that had either never seen PHA, not seen PHA for several weeks, or been stimulated regularly with PHA, but were several months old, did not lose VLA-1 in response to PHA stimulation, suggesting that a state of insensitivity to PHA effects could be attained. Unlike PHA-stimulated T cells, T cells repetitively restimulated with alloantigen or the monoclonal antibody T3 did not show a marked absence of VLA-1 but rather showed an increased level of VLA-2 relative to VLA-1. Taken together, results of stimulation by either mitogen, alloantigen, or anti-T3 monoclonal antibody support the conclusion that T cell stimulation in general can cause a decreased VLA-1:VLA-2 ratio, whether by decreased VLA-1 or increased VLA-2. These shifts in VLA-1:VLA-2 ratios are probably not simply the result of shifts in the relative proportions of different subpopulations, because similar growth-related changes in this ratio were observed on the T cell line ANITA, which is a homogeneous population of cells. Because both VLA-1 and VLA-2 are differentially regulated on cultured, long term activated T cells depending on stage of activation and growth conditions, and are members of a family of at least five heterodimers that includes cell matrix adhesion molecules, we suggest that these studies will provide clues to novel aspects of T cell growth regulation, perhaps relating to T cell-matrix adhesion.     

Characterization of polymers of adenosine diphosphate ribose generated in vitro and in vivo

Methods have been developed and applied to determine the size and branching frequency of polymers of ADP-ribose synthesized in nucleotide-permeable cultured mouse cells and in intact cultured cells. Polymers were purified by affinity chromatography with a boronate resin and were fractionated according to size molecular sieve high-performance liquid chromatography. Fractions were enzymatically digested to nucleotides, which were separated by strong anion exchange high-performance liquid chromatography. From these data, average polymer size and branching frequency were calculated. A wide range of polymer sizes was observed. Polymers as large as 190 residues with at least five points of branching per molecule were generated in vitro. Polymers of up to 67 residues containing up to two points of branching per molecule were isolated from intact cells following treatment with the DNA alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine. Cells treated with hyperthermia prior to DNA damage contained polymers of an average maximum size of 244 residues containing up to six points of branching per molecule. The detection of large polymers of ADP-ribose in intact cells suggests that alterations in chromatin organization effected by poly(ADP-ribosylation) may extend beyond the covalently modified proteins and very likely involve noncovalent interactions of poly(ADP-ribose) with other components of chromatin.     

Succinate metabolism related to lipid synthesis in the housefly Musca domestica L

The metabolism of succinate was examined in the housefly Musca domestica L. The labeled carbons from [2,3-¹⁴C]succinate were readily incorporated into cuticular hydrocarbon and internal lipid, whereas radioactivity from [1,4-¹⁴C]succinate was not incorporated into either fraction. Examination of the incorporation of [2,3-¹⁴C]succinate, [1-¹⁴C]acetate, and [U-¹⁴C]proline into hydrocarbon by radio-gas-liquid chromatography showed that each substrate gave a similar labeling pattern, which suggested that succinate and proline were converted to acetyl-CoA prior to incorporation into hydrocarbons. Carbon-13 nuclear magnetic resonance showed that the labeled carbons from [2,3-¹³C]succinate enriched carbons 1, 2, and 3 of hydrocarbons with carbon-carbon coupling showing that carbons 2 and 3 of succinate were incorporated as an intact unit. Radio-high-performance liquid chromatographic analysis of [2,3-¹⁴C]succinate metabolism by mitochondrial preparations showed that in addition to labeling fumarate, malate, and citrate, considerable radioactivity was also present in the acetate fraction. The data show that succinate was not converted to methylmalonate and did not label hydrocarbon via a methylmalonyl derivative. Malic enzyme was assayed in sonicated mitochondria prepared from the abdomens and thoraces of 1- and 4-day-old insects; higher activity was obtained with NAD⁺ in mitochondria prepared from thoraces, whereas NADP⁺ gave higher activity with abdomen preparations. These data document the metabolism of succinate to acetyl-CoA and not to a methylmalonyl unit prior to incorporation into lipid in the housefly and establish the role of the malic enzyme in this process.