Expression of alkaline proteinase gene in two recombinant <Emphasis Type="Italic">Bacillus cereus</Emphasis> feather-degrading strains

Two Bacillus cereus feather-degrading strains (23/1 and 6/2) were transformed using a recombinant plasmid p5.2 carrying the alkaline proteinase gene (aprE). A high level of the aprE gene expression was observed when the recombinant strains were grown on sporulation medium. The expression of the aprE gene proceeded during the early stationary phase and the p5.2 plasmid was segregationally and structurally stable in both strains. The two recombinant strains grown on a mineral medium with 1 % chicken feather as source of energy, carbon and nitrogen exhibited higher proteolytic activity (≈6-fold and 2.4-fold higher for strains 23/1 (p5.2) and 6/2 (p5.2), respectively. Keratinolytic activity increased ≈3.5-fold and 4.15-fold, respectively. The keratinolytic activity further increased when an optimized medium with yeast extract and corn oil was used. Considerable amounts of free amino acids were obtained after the biodegradation of feather which makes the new strains promising for application in feather-waste treatment to, e.g., transformation to animal feedstuff.     

Engineering ascorbic acid biosynthetic pathway in Arabidopsis leaves by single and double gene transformation

Six genes, which encode enzymes involved in ascorbic acid (AsA) biosynthesis, including guanosine diphosphate (GDP)-mannose pyrophosphorylase (GMP), GDP-mannose-3′,5′-epimerase (GME), GDP-galactose guanylyltransferase (GGT), L-galactose-1-phosphate phosphatase (GPP), L-galactose dehydrogenase (GDH) and L-galactono-1,4-lactone dehydrogenase (GLDH) were transformed into Arabidopsis thaliana, to evaluate the contribution of each gene to AsA accumulation. Additionally, two combinations, GGT-GPP and GGT-GLDH, were co-transformed into Arabidopsis with a reliable double-gene transformation system. AsA content of GGT transgenic lines was 2.9-fold higher as compared to the control, and co-transformation led up to 4.1-fold AsA enhancement. These results provided further evidence that GGT is the key enzyme in plant AsA biosynthesis.     

Tailoring Tropane Alkaloid Accumulation in Transgenic Hairy Roots of Atropa baetica by Over-expressing the Gene Encoding Hyoscyamine 6β-hydroxylase

Atropa baetica hairy roots, over-expressing cDNA from Hyoscyamus niger encoding the gene for hyoscyamine 6β-hydroxylase (H6H), were produced by Agrobacterium rhizogenes infection. The transgenic roots over-expressing h6h had an altered alkaloid profile in which hyoscyamine was entirely converted into scopolamine. In the best h6h clone, scopolamine accumulation increased 9-fold compared to plants, amounting to 5.6 mg g dry wt⁻¹, some of which was released into the liquid medium. Only negligible amounts of hyoscyamine were detected. In contrast, the gus control culture contained a much higher amount of hyoscyamine than scopolamine, mimicking the situation in the plant. At the molecular level, a higher conversion of hyoscyamine into scopolamine was related to a higher level of h6h mRNA; in some instances this was 5–10-fold higherThis article is dedicated to the memory of Professor Antonio G. González     

Differential channelling of liver lipids in relation to susceptibility to hepatic steatosis in two species of ducks

In the human, hepatic steatosis can be associated with an imbalance between synthesis, secretion and storage of hepatic lipids, and exhibits a genetic susceptibility. The effect of overfeeding on hepatic lipid channelling was investigated in two genotypes of ducks that differ in their susceptibility to fatty liver, i.e. the common duck, Anas platyrhynchos, and the Muscovy duck, Cairina moschata. Before overfeeeding, the Muscovy duck exhibited a lower subcutaneous adiposity and a higher muscular development, whereas hepatic composition was similar in both genotypes (>5% lipids and triglycerides accounting for 6–10% lipids). In the plasma lipoprotein profile, HDL predominated (5.5–7.8 g/l) over VLDL (0.09–0.25 g/l) and LDL (0.65–1.06 g/l). All lipid and lipoprotein concentrations were lower in the Muscovy duck. In response to overfeeding, the Muscovy duck exhibited a higher degree of hepatic steatosis (62 vs. 50% lipids), and a lower increase in adiposity and in the concentration of plasma triglycerides (6-fold vs. 10-fold) and VLDL (23-fold vs. 34-fold). Thus, certain genotypes may be more responsive to the dietary induction of fatty liver because of a less efficient channelling of hepatic lipids towards secretion into plasma and adipose storage, and the duck may represent a suitable model in which to study the development of hepatic steatosis and its pathogenesis.     

Long-Term Waterlogging: Nutrient,Gas Exchange,Photochemical and Pigment Characteristics of Eucalyptus nitens Saplings

Imposition of waterlogging for eight months induced morphological adaptation in Eucalyptus nitens in the form of adventitious and aerenchymatous roots and hypertrophy of stems. Foliar calcium (1.3-fold), potassium (2-fold) and phosphorus (2.4-fold) were lower and iron (5.6-fold) was higher in waterlogged than control saplings. Stem Ca (1.7-fold) was lower, whereas Mn (1.8-fold) and Fe (117-fold) were higher in waterlogged than control saplings. Distinct purple pigmentation was observed in xylem tissues of waterlogged saplings. A significant reduction in the maximum photosynthetic rate and photochemical efficiency was observed in waterlogged compared to control saplings. Although chlorophyll levels were similar, the xanthophyll cycle pool size was significantly greater in waterlogged saplings and may have contributed to the relatively greater capacity for light energy dissipation observed. Predawn xanthophyll cycle engagement was significantly greater in waterlogged than control saplings, despite relatively mild temperatures. Foliar anthocyanin concentration was higher in waterlogged than control saplings.     

Synthetic Nasonov gland pheromone enhances abundance and visitation of honeybee,Apis mellifera,in Korla fragrant pear,Pyrus sinkiangensis

1. Korla fragrant pear (Pyrus sinkiangensis Yü) depends on cross-pollination by honeybees (Apis mellifera) but may suffer from low honeybee visitation.
2. We assessed whether honeybee abundance and visitation frequency are enhanced by using synthetic Nasonov gland pheromone (NGP), which is naturally produced by worker bees to stimulate the aggregation of bees to food resources or nesting sites.
3. The response of honeybees to synthetic NGP was firstly assessed using Y-tube olfactometer tests in the laboratory, and subsequently in the field, by placing NGP lures on Korla fragrant pear trees in orchards with and without beehives. Honeybee abundance was assessed using coloured pan traps while honeybee visits were assessed by visual observations on pear flowers.
4. Y-tube olfactometer tests showed a significant preference of honeybees for NGP. In pear orchards with beehives, honeybee abundance was 2.5-fold higher on trees with NGP lures than on trees without NGP, and 2.2-fold higher in orchards in which all trees contained NGP lures than in orchards without NGP lures. Such positive effects were not observed in orchards without beehives.
5. Flower visitation by honeybees was significantly higher in trees with NGP lures than without NGP lures, irrespective of the presence (5.7-fold higher) or absence of beehives (27.6-fold higher).
6. In mixed pear-apricot orchards, honeybee abundance was higher in pear trees with NGP lures than without lures.
7. Our results show that NGP lures attract honeybees to flowering pear trees in monoculture pear and mixed pear-apricot orchards, and that this effect is greatest in orchards with beehives.

     

Densities of the arundo wasp,Tetramesa romana (Hymenoptera: Eurytomidae) across its native range in Mediterranean Europe and introduced ranges in North America and Africa

Tetramesa romana is a biological control agent of the giant reed, Arundo donax (Poaceae: Arundinoideae), which is an invasive weed in the riparian habitats of the Rio Grande Basin of Texas, the southwestern U.S.A. and northern Mexico. Field evaluations were conducted in the native range of T. romana in Mediterranean Europe and in the introduced ranges of Texas, California, and South Africa to compare densities of the wasp. Population densities and percentage parasitism levels for the 2017 year are compared to meteorological variables (average temperature, precipitation, and heat units). In the introduced ranges of Texas (intentional) and South Africa (adventive) T. romana population densities were 39 and 10-fold higher than in the native range, respectively. Percentage parasitism of T. romana in Texas and in the native range of Thessaloniki, Greece were 2.0% and 34.3%, respectively. Annual heat unit accumulation was 1.3–2.7-fold higher at Texas sites than at other introduced or native sites, and heat units were positively associated with exit hole counts at introduced sites. Annual precipitation was 2-fold higher at Texas and South African sites than in California and the native range sites. Favourable weather conditions and reduced parasitism in Texas along the Rio Grande, as compared to the native range, allows T. romana to reach higher population levels and cause considerable damage to A. donax.     

Application of medium optimization tools for improving recombinant human interferon gamma production from Kluyveromyces lactis

The present study is focused upon improving biomass of Kluyveromyces lactis cells expressing recombinant human interferon gamma (hIFN-γ), with the aim of augmenting hIFN-γ concentration using statistical and artificial intelligence approach. Optimization of medium components viz., lactose, yeast extract, and trace elements were performed with Box–Behnken design (BBD) and artificial neural network linked genetic algorithm (ANN-GA) for maximizing biomass of recombinant K. lactis (objective function). The studies resulted over 1.5-fold improvement in the biomass concentration in a medium composed of 80?g/L lactose, 10.353?g/L yeast extract, and 15?mL/L trace elements as compared with initial biomass value. In the same study hIFN-γ concentration reached 881?µg/L which was 2.28-fold higher as compared with initial hIFN-γ concentration obtained in unoptimized medium. Further the batch fermentation study displayed mixed growth associated kinetics with the maximum hIFN-γ production rate of 1.1?mg/L. BBD and ANN-GA, both optimization techniques predicted a higher lactose concentration was clearly beneficial for augmenting K. lactis biomass which in turn increased hIFN-γ concentration.     

Serum TNFRII: A promising biomarker for predicting the risk of subcentimetre lung adenocarcinoma

Early diagnosis of lung adenocarcinoma requires effective risk predictors. TNFRII was reported to be related to tumorigenesis, but remained unclear in lung cancer. This research set out to investigate the relationship between the sTNFRII (serum TNFRII) level and the risk of lung adenocarcinoma less than 1 cm in diameter. Seventy-one pairs of subcentimetre lung adenocarcinoma patients and healthy controls were analysed through multiplex bead-based Luminex assay and found a significantly lower expression of sTNFRII in patients with subcentimetre lung adenocarcinoma than that in the healthy controls (P < .001), which was further verified through ONCOMINE database analysis. Increased levels of sTNFRII reduced the risk of subcentimetre lung adenocarcinoma by 89% (P < .001). Patients with a higher level of BLC had a 2.70-fold (P < .01) higher risk of subcentimetre adenocarcinoma. Furthermore, a higher BLC/TNFRII ratio was related to a 35-fold higher risk of subcentimetre adenocarcinoma. TNFRII showed good specificity, sensitivity and accuracy (0.72, 0.75 and 0.73, respectively), with an AUC of 0.73 (P < .001). In conclusion, the present study assessed the value of sTNFRII as a potential biomarker to predict the risk of subcentimetre lung adenocarcinoma and provided evidence for the further use of TNFRII as an auxiliary marker in the diagnosis of subcentimetre lung adenocarcinoma.     

Overproduction of a stable acetaldehyde dehydrogenase with high affinity to acetaldehyde by Escherichia coli expressing the ACOD gene of Alcaligenes eutrophus

Summary The acoD gene of Alcaligenes eutrophus, which encodes a very stable NAD dependent aldehyde dehydrogenase with high affinity toward acetaldehyde (K _m = 4M), was overexpressed in Escherichia coli. Plasmid pDel087, a deletion derivative of a plasmid constructed recently (Priefert et al., 1992), conferred acetaldehyde dehydrogenase activity of 2.5 U/mg of protein to E. coli, which was about 8-fold higher than the activity in ethanol-grown cells of A. eutrophus.     

Activity and stability of chemically modified Candida antarctica lipase B adsorbed on solid supports

The effect of various covalent chemical modifications on the transesterification activity and stability of adsorbed lipase B from Candida antarctica (CALB) was studied in 2-butanone and o-xylene. CALB species modified with either polyethylene glycol 2000 monomethyl ether (MPEG), polyethylene glycol 300 mono-octyl ether (OPEG) or n-octanol (OCT) were used in combination with a hydrophobic (Accurel) and a hydrophilic (Duolite) support. The thermostabilities of adsorbed CALB in both solvents, and that of free CALB in o-xylene were not influenced by the modifications. In contrast, the thermostability of free CALB in 2-butanone decreased 2.5-fold after MPEG modification and increased 1.5-fold after modification with OPEG and n-octanol, compared to that of native CALB. The activities of the native and modified CALB species were up to 9-fold higher after adsorption onto Accurel than those of the corresponding free enzymes. Adsorption of these enzyme species onto Duolite only resulted in a 2- to 3-fold increase in the activity of OPEG- and OCT-modified CALB. The modified CALB species adsorbed onto Accurel show similar or up to 2-fold lower activities than do native adsorbed CALB species, while 1.5- to 6-fold higher activities were found for modified CALB species adsorbed onto Duolite. We propose that hydrophobic modifiers induce conformational changes of CALB during adsorption on a hydrophobic support whereas all three modifiers protect CALB from structural alterations during adsorption onto a hydrophilic support. Received: 18 March 1999 / Received revision: 21 June 1999 / Accepted: 27 June 1999     

AMP-activated protein kinase and metabolic regulation in cold-hardy insects

Winter survival for many insects depends on cold hardiness adaptations as well as entry into a hypometabolic diapause state that minimizes energy expenditure. We investigated whether AMP-activated protein kinase (AMPK) could be involved in this adaptation in larvae of two cold-hardy insects, Eurosta solidaginis that is freeze tolerant and Epiblema scudderiana that uses a freeze avoidance strategy. AMPK activity was almost 2-fold higher in winter larvae (February) compared with animals collected in September. Immunoblotting revealed that phosphorylation of AMPK in the activation loop and phosphorylation of acetyl-CoA carboxylase (ACC), a key target of AMPK, were higher in Epiblema during midwinter whereas no seasonal change was seen in Eurosta. Immunoblotting also revealed a significant increase in ribosomal protein S6 phosphorylation in overwintering Epiblema larvae, and in both Eurosta and Epiblema, phosphorylation of eukaryotic initiation factor 4E-binding protein-1 dramatically increased in the winter. Pyruvate dehydrogenase (PDH) E1α subunit site 1 phosphorylation was 2-fold higher in extracts of Eurosta larvae collected in February versus September while PDH activity decreased by about 50% in Eurosta and 80% in February Eurosta larvae compared with animals collected in September. Glycogen phosphorylase phosphorylation was 3-fold higher in Epiblema larvae collected in February compared with September and also in these animals, triglyceride lipase activity increased by 70% during winter. Overall, our study suggests a re-sculpting of metabolism during insect diapause, which shifted to a more catabolic poise in freeze-avoiding overwintering Epiblema larvae, possibly involving AMPK.     

Giardia intestinalis: Expression of ubiquitin, glucosamine-6-phosphate and cyst wall protein genes during the encystment process

We determined the relative expression of ubiquitin (ub), glucosamine-6-phosphate-isomerase (gn6pi) and cyst wall protein (cwp) genes during encystment of the Portland-1 and Portland-1R strains of Giardia intestinalis. Encystment was induced with bile for different time periods. The presence of encystment-specific vesicles (ESVs) and the relative expression of genes (log₁₀ΔRn) were determined by transmission electron microscopy and real-time PCR, respectively. Our results demonstrated the gene expression and the presence of ESVs after 6 h of encystment. Values of cwp2 gene expression increased by 591-fold in strain Portland-1 and 78.2-fold in strain Portland-1R at this time point compared to values at 0 h, after which values gradually decreased until reaching basal values between 8 and 18 h after the encystment started. Expression of gn6pi was 43.5- and 46.3-fold higher than basal values, in Portland-1 and Portland-1R, respectively. Ub gene expression was 82.25-fold higher than its basal levels at 4 h, after which expression decreased gradually until reaching basal values after 16 h. Conclusions: This work showed the relationship between the presence of ESVs and encystment gene expression at 6 h, and resistance to albendazole does not inhibit the encystment process. The results revealed important knowledge with implications in the control of parasite dissemination for preventing parasite transmission.     

Microhabitats and Water Relations of Epiphytic Cacti and Ferns in a Lowland Neotropical Forest1

The pattern of canopy distribution and some water relations characteristics of the epiphytic cacti Epiphyllum phyllanthus and Rhipsalis baccifera and the epiphytic ferns Polypodium crassifolium and Polypodium phyllitidis were examined in the tropical forest of Barro Colorado Island, Panama. The epiphytic cacti were 6-fold more succulent than the epiphytic ferns, which had a 9-fold higher root: shoot ratio. The four species, especially the cacti, were more abundant on the deciduous trees Ceiba pentandra, Platypodium elegans. and Tabebuia guayacan than on the evergreen Anacardium excelsum. The water-holding capacity of the bark was 2-fold higher for A. excelsum and T. guayacan than for C. pentandra and P. elegans; the main crotches of the latter species intercepted 2-fold more rainfall than those of the former. Well-watered plants of all epiphytic species showed similar total daily transpiration. After 2 weeks of drought, daily transpiration decreased an average of 48 percent for the cacti and 73 percent for the ferns. After 4 weeks of drought, daily transpiration decreased 80 percent for the cacti and was eliminated for the ferns; succulence then decreased an average of 29 percent for the cacti and 98 percent for the ferns, but all species recovered fully within 2 d after rewetting. The epiphytic ferns had a low relative capacitance (0.16 M/Pa), causing these presumably C₃ plants often to be under water stress. A high relative capacitance (0.50 M/Pa) and crassulacean acid metabolism allowed the epiphytic cacti to occur most frequently on the driest sites of this tropical forest.     

Misting and nitrogen fertilization of shoots of a saltmarsh grass: effects upon fungal decay of leaf blades

We conducted a 12-week field manipulation experiment in which we raised the nitrogen availability (ammonium sulfate fertilization to roots) and/or water potential (freshwater misting) of decaying leaf blades of a saltmarsh grass (smooth cordgrass, Spartina alterniflora) in triplicate 11-m² plots, and compared the manipulated plots to unmanipulated, control plots. The ascomycetous fungi that dominate cordgrass leaf decomposition processes under natural conditions exhibited a boosting (>2-fold) of living standing crop (ergosterol content) by misting at the 1 st week after tagging of senescent leaves, but afterwards, living-fungal standing crop on misted blades was equivalent to that on control blades, confirming prior evidence that Spartina fungi are well adapted to natural, irregular wetting. Misting also caused 2-fold sharper temporal declines than control in instantaneous rates of fungal production (ergosterol synthesis), 5-fold declines in density of sexual reproductive structures that were not shown by controls, and 2-fold higher rates of loss of plant organic mass. Extra nitrogen gave a long-term boost to living-fungal standing crop (about 2-fold at 12 weeks), which was also reflected in rates of fungal production at 4 weeks, suggesting that saltmarsh fungal production is nitrogen-limited. Although bacterial and green-microalgal crops were boosted by manipulations of nitrogen and/or water, their maximal crops remained 0.3 or 2% (bacteria or green microalgae, respectively) of contemporaneous living-fungal crop. The fungal carbon-productivity values obtained, in conjunction with rates of loss of plant carbon, hinted that fungal yield can be high (>50%), and that it is boosted by high availability of nitrogen. We speculate that one partial cause of high fungal yield could be subsidy of fungal growth by dissolved organic carbon from outside decomposing leaves.     

Chromobacterium violaceum delivers violacein,a hydrophobic antibiotic,to other microbes in membrane vesicles

This study describes Chromobacterium violaceum's use of extracellular membrane vesicles (MVs) to both solubilize and transport violacein to other microorganisms. Violacein is a hydrophobic bisindole with known antibiotic activities against other microorganisms. Characterization of the MVs found they carried more violacein than protein (1.37 ± 0.19-fold), suggesting they may act as a reservoir for this compound. However, MVs are not produced in response to violacein – a ΔvioA isogenic mutant, which is incapable of making violacein, actually produced significantly more MVs (3.2-fold) than the wild-type strain. Although violacein is insoluble in water (Log P_{octanol:water} = 3.34), 79.5% remained in the aqueous phase when it was present within the C. violaceum MVs, an increase in solubility of 1740-fold. Moreover, tests with a strain of Staphylococcus aureus showed MV-associated violacein is bactericidal, with 3.1 mg/l killing 90% of S. aureus in 6 h. Tests with the ΔvioA MVs found no loss in the S. aureus viability, even when its MVs were added at much higher concentrations, demonstrating violacein is the active component within the wild-type MVs. In conclusion, our study clearly demonstrates C. violaceum produces MVs and uses them as vehicles to solubilize violacein and transport this hydrophobic antibiotic to other microbes.     

Studies on water transport through the sweet cherry fruit surface: IX. Comparing permeability in water uptake and transpiration

Water uptake and transpiration were studied through the surface of intact sweet cherry (Prunus avium L.) fruit, exocarp segments (ES) and cuticular membranes (CM) excised from the cheek of sweet cherry fruit and astomatous CM isolated from Schefflera arboricola (Hayata) Hayata, Citrus aurantium L., and Stephanotis floribunda Brongn. leaves or from Lycopersicon esculentum Mill. and Capsicum annuum L. var. annuum Fasciculatum Group fruit. ES and CM were mounted in diffusion cells. Water (deionized) uptake into intact sweet cherry fruit, through ES or CM interfacing water as a donor and a polyethyleneglycol (PEG 6000, osmotic pressure 2.83 MPa)-containing receiver was determined gravimetrically. Transpiration was quantified by monitoring weight loss of a PEG 6000-containing donor (2.83 MPa) against dry silica as a receiver. The permeability coefficients for osmotic water uptake and transpiration were calculated from the amount of water taken up or transpired per unit surface area and time, and the driving force for transport. Permeability during osmotic water uptake was markedly higher than during transpiration in intact sweet cherry fruit (40.2-fold), excised ES of sweet cherry fruit (12.5- to 53.7-fold) and isolated astomatous fruit and leaf CM of a range of species (on average 23.0-fold). Partitioning water transport into stomatal and cuticular components revealed that permeability of the sweet cherry fruit cuticle for water uptake was 11.9-fold higher and that of stomata 56.8-fold higher than the respective permeability during transpiration. Increasing water vapor activity in the receiver from 0 to 1 increased permeability during transpiration across isolated sweet cherry fruit CM about 2.1-fold. Permeability for vapor uptake from saturated water vapor into a PEG 6000 receiver solution was markedly lower than from liquid water, but of similar magnitude to the permeability during self-diffusion of ³H₂O in the absence of osmotica. The energy of activation for self-diffusion of water across ES or CM was higher than for osmotic water uptake and decreased with increasing stomatal density. The data indicate that viscous flow along an aqueous continuum across the sweet cherry fruit exocarp and across the astomatous CM of selected species accounted for the higher permeability during water uptake as compared to self-diffusion or transpiration.     

Deletion of the budBAC operon in Klebsiella pneumoniae to understand the physiological role of 2,3-butanediol biosynthesis

Klebsiella pneumoniae is known to produce 2,3-butanediol (2,3-BDO), a valuable chemical. In K. pneumoniae, the 2,3-BDO operon (budBAC) is involved in the production of 2,3-BDO. To observe the physiological role of the 2,3-BDO operon in a mixed acid fermentation, we constructed a budBAC-deleted strain (SGSB109). The production of extracellular metabolites, CO₂ emission, carbon distribution, and NADH/NAD⁺ balance of SGSB109 were compared with the parent strain (SGSB100). When comparing the carbon distribution at 15 hr, four significant differences were observed: in 2,3-BDO biosynthesis, lactate and acetate production (lactate and acetate production increased 2.3-fold and 4.1-fold in SGSB109 compared to SGSB100), CO₂ emission (higher in SGSB100), and carbon substrate uptake (higher in SGSB100). Previous studies on the inactivation of the 2,3-BDO operon were focused on the increase of 1,3-propanediol production. Few studies have been done observing the role of 2,3-BDO biosynthesis. This study provides a prime insight into the role of 2,3-BDO biosynthesis of K. pneumoniae.     

Renal responses to diuretics in the turtle

Summary We administered the diuretics furosemide and ethacrynic acid to conscious freshwater turtles to assess changes in renal function and plasma renin activity (PRA) in an animal which lacks a loop of Henle. Furosemide (2 and 5 mg/kg) produced no changes in blood pressure, hematocrit, plasma electrolytes, glomerular filtration rate (GFR), or PRA. Furosemide doubled urine volume while sodium excretion increased 20-fold and chloride and potassium excretion increased 12-fold (P<0.05 in each case). Net potassium secretion was observed. Ethacrynic acid (2 and 5 mg/kg) also produced no changes in blood pressure, hematocrit, plasma electrolytes, or PRA. At the lower dose GFR increased by 40% and urine volume nearly doubled (P<0.05 in each case). Sodium, chloride, and potassium excretion increased roughly 10-fold (P<0.05 in each case). At the higher dose, GFR increased by 80% and urine volume more than doubled (P<0.05 in each case). Sodium excretion rose 40-fold, chloride excretion rose 25-fold, and potassium excretion rose 10-fold (P<0.05 in each case). At both doses net potassium secretion occurred. The results demonstrate that both drugs inhibit tubular reabsorption in the turtle, acting primarily on distal segments of the nephron. The failure of either drug to alter PRA suggests that the turtle lacks a tubular mechanism for alterig renin release.Abbreviations GFR glomerular filtration rate - PRA plasma renin activity Supported by the University of Delaware Honors Program, American Heart Association of Delaware, NIH Biomedical Support Program, and USPHS #HL2808401