Biodegradation of Metal-Nitrilotriacetate Complexes by a Pseudomonas Species: Mechanism of Reaction

A nitrilotriacetate (NTA)-degrading Pseudomonas species was shown to degrade Ca, Mn, Mg, Cu, Zn, Cd, Fe, and Na chelates of NTA at nearly equal rates when the appropriate metal concentrations are low enough to avoid toxicity from the freed metal. Ni-NTA, however, was not degraded. When higher concentrations of metal-NTA substrates were used, soil stimulated degradation of Cu, Zn, and Cd complexes, probably as a result of binding toxic freed metals. The metal associated with the NTA substrate does not appear to be transported into the cell, since metals do not accumulate in the cells and the presence of NTA reduces metal toxicity. The data are consistent with the hypothesis that an envelope-associated component, probably a transport protein involved in binding, is responsible for the disassociation of the metal from the NTA. Both soil and this NTA-degrading organism destabilize the metal-NTA complex, which suggests that in the natural environment both would act to limit mobilization of metals as soluble NTA chelates. Crude soluble enzyme preparations degrade Fe-, Mn-, and Na-NTA complexes but not Cu-NTA.     

Determination of acid α-naphthyl acetate esterase enzyme activity in peripheral blood leukocytes of gazelles (Gazella subgutturosa)

We examined gazelle peripheral blood leucocytes using the α-Naphthyl acetate esterase (ANAE) staining technique (pH 5.8). Our purpose was to determine the percentage of ANAE positive lymphocytes. The proportion of ANAE positive T-lymphocytes was 72%. T-lymphocytes showed an ANAE positive reaction, but eosinophilic granulocytes and monocytes also showed a positive reaction. By contrast, no reaction was detected in B-lymphocytes, neutrophil granulocytes or platelets. The reaction observed in T-lymphocytes was a red-brown coloration, usually 1–2 granules, but enough granules to fill the cytoplasm were detected rarely. As a result of ANAE enzyme staining, we concluded that the staining technique can be used as a cytochemical marker for gazelle T-lymphocytes.     

Phylogeographical population structure of tiger quolls Dasyurus maculatus (Dasyuridae: Marsupialia), an endangered carnivorous marsupial

Tiger quolls, Dasyurus maculatus, are the largest carnivorous marsupials still extant on the mainland of Australia, and occupy an important ecological niche as top predators and scavengers. Two allopatric subspecies are recognized, D.m. gracilis in north Queensland, and D.m. maculatus in the southeast of the mainland and Tasmania. D.m. gracilis is considered endangered while D.m. maculatus is listed as vulnerable to extinction; both subspecies are still in decline. Phylogeographical subdivision was examined to determine evolutionarily significant units (ESUs) and management units (MUs) among populations of tiger quolls to assist in the conservation of these taxa. Ninety-three tiger quolls from nine representative populations were sampled from throughout the species range. Six nuclear microsatellite loci and the mitochondrial DNA (mtDNA) control region (471 bp) were used to examine ESUs and MUs in this species. We demonstrated that Tasmanian tiger quolls are reciprocally monophyletic to those from the mainland using mtDNA analysis, but D.m. gracilis was not monophyletic with respect to mainland D.m. maculatus. Analysis of microsatellite loci also revealed significant differences between the Tasmanian and mainland tiger quolls, and between D.m. gracilis and mainland D.m. maculatus. These results indicate that Tasmanian and mainland tiger quolls form two distinct evolutionary units but that D.m. gracilis and mainland D.m. maculatus are different MUs within the same ESU. The two marker types used in this study revealed different male and female dispersal patterns and indicate that the most appropriate units for short-term management are local populations. A revised classification and management plan are needed for tiger quolls, particularly in relation to conservation of the Tasmanian and Queensland populations.     

Membrane ruffling requires coordination between type Ialpha phosphatidylinositol phosphate kinase and Rac signaling

Membrane ruffle formation requires remodeling of cortical actin filaments, a process dependent upon the small G-protein Rac. Growth factors stimulate actin remodeling and membrane ruffling by integration of signaling pathways that regulate actin-binding proteins. Phosphatidylinositol 4,5-bisphosphate (PIP2) regulates the activity of many actin-binding proteins and is produced by the type I phosphatidylinositol phosphate kinases (PIPKIs). Here we show in MG-63 cells that only the PIPKIalpha isoform is localized to platelet-derived growth factor (PDGF)-induced membrane ruffles. Further, expression of kinase dead PIPKIalpha, which acts as a dominant negative mutant, blocked membrane ruffling, suggesting that PIPKIalpha and PIP2 participate in ruffling. To explore this, PIPKIalpha was overexpressed in serum-starved cells and stimulated with PDGF. In serum-starved cells, PIPKIalpha expression did not stimulate actin remodeling, but when these cells were stimulated with PDGF, actin rapidly reorganized into foci but not membrane ruffles. PIPKIalpha-mediated formation of actin foci was independent of both Rac1 and phosphatidylinositol 3-kinase activities. Significantly, coexpression of dominant active Rac1 with PIPKIalpha in PDGF-stimulated cells resulted in membrane ruffling. The PDGF- and Rac1-stimulated ruffling was inhibited by expression of kinase-dead PIPKIalpha. Combined, these data support a model where the localized production of PIP2 by PIPKIalpha is necessary for actin remodeling, whereas formation of membrane ruffles required Rac signaling.     

Water Content Mediated Microaerophilic Toluene Biodegradation in Arid Vadose Zone Materials

We investigated the conditions promoting toluene biodegradation for gasoline-contaminated near-surface (0.6 m depth) and subsurface (4.7 to 5.0 m depth) vadose zone soils sampled from an arid environment. At both depths, water addition was required for toluene biodegradation to occur. In near-surface samples, no inorganic nutrient addition was necessary and (i) biodegradation was fastest at 0.0 MPa, (ii) biodegradation rates decreased with decreasing water potential down to ?1.0 MPa, and (iii) biodegradation was undetectable at ?1.5 MPa. For subsurface material, toluene depletion was stimulated either by slurrying with a nutrient solution or by adjusting the moisture content to 20% (0.0 MPa) with nutrient solution and lowering the oxygen concentration (to effectively 1 mg L-1 in the aqueous phase). Thus, in the subsurface material, toluene depletion was microaerobic and nutrient-limited, occurring only under low oxygen and with inorganic nutrient addition. Our studies implicate microaerophily as an important characteristic of the toluene-degrading communities in these dry soils, with soil water as a primary controller of oxygen availability.