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.     

Structure of the precursor to an enzyme mediating COOH-terminal amidation in peptide biosynthesis

Many bioactive peptides terminate with an amino acid alpha-amide at their COOH terminus. The enzyme responsible for this essential posttranslational modification is known as peptidyl-glycine alpha-amidating monooxygenase or PAM. We identified cDNAs encoding the enzyme by using antibodies to screen a bovine intermediate pituitary lambda gt11 expression library. Antibodies to a beta-galactosidase/PAM fusion protein removed PAM activity from bovine pituitary homogenates. The 108,207 dalton protein predicted by the complete cDNA is approximately twice the size of purified PAM. An NH2-terminal signal sequence and short propeptide precede the NH2 terminus of purified PAM. The sequences of several PAM cyanogen bromide peptides were localized in the NH2-terminal half of the predicted protein. The cDNA encodes an additional 430 amino acid intragranular domain followed by a putative membrane spanning domain and a hydrophilic cytoplasmic domain. The forms of PAM purified from bovine neurointermediate pituitary may be generated by endoproteolytic cleavage at a subset of the 10 pairs of basic amino acids in the precursor. High levels of PAM mRNA were found in bovine pituitary and cerebral cortex. In corticotropic tumor cells, levels of PAM mRNA and pro-ACTH/endorphin mRNA were regulated in parallel by glucocorticoids and CRF.     

Hormonal regulation of fat esterification & oxidation in hepatocytes from fed rats: modulation by 3-mercaptopicolinate

3-Mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase (PEPCK), decreased esterification of [1-14C] oleate and [1-14C] myristate in hepatocytes from fed rats. In the absence of 3-mercaptopicolinate, adrenaline, noradrenaline, vasopressin or angiotensin II increased esterification to triacylglycerol of [1-14C] oleate but not [1-14C] myristate. Cyclic AMP decreased esterification of both oleate and myristate. In the presence of 3-mercaptopicolinate, stimulation of oleate esterification by the catecholamines, vasopressin or angiotensin II was increased, and stimulatory effects of these hormones on myristate esterification were observed. Adrenaline, noradrenaline, vasopressin or angiotensin II increased 14CO2 production from both [1-14C] oleate and [1-14C] myristate but the degree of stimulation was similar in the absence or presence of 3-mercaptopicolinate. The results indicate a role for the catecholamines and angiotensin II in the regulation of liver fat metabolism and emphasize the potential importance of changes in activity of PEPCK as determinants of hepatic carbon flux.     

Ketone-body metabolism after partial hepatectomy in the rat.

Fed or 24 h-starved rats were subjected to two-thirds partial hepatectomy or sham-operation and subsequently starved for 4, 14 or 24 h. Despite high plasma fatty acid concentrations, the partially hepatectomized rats failed to respond to post-operative starvation with increased blood and liver ketone-body concentrations or to maintain the high ketone-body concentrations associated with pre-operative starvation. Hypoglycaemia and hyperlactaemia were observed within 30 min of functional hepatectomy, but not partial hepatectomy, of 24 h-starved rats, and, even after a further 24 h starvation of partially hepatectomized rats, blood glucose concentrations were only slightly decreased. The results are discussed with reference to fat oxidation and gluconeogenesis in the liver remaining after partial hepatectomy.     

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.