Identification of metolachlor mineralizing bacteria in aerobic and anaerobic soils using DNA-stable isotope probing

The influence of soil environmental factors such as aeration on the ecology of microorganisms involved in the mineralization and degradation of the popular soil-applied pre-emergent herbicide, metolachlor is unknown. To address this knowledge gap, we utilized DNA-based stable isotope probing (SIP) where soil microcosms were incubated aerobically or anaerobically and received herbicide treatments with unlabeled metolachlor or ¹³C-metolachlor. Mineralization of metolachlor was confirmed as noted from the evolution of ¹⁴CO₂ from ¹⁴C-metolachlor-treated microcosms and clearly demonstrated the efficient utilization of the herbicide as a carbon source. Terminal restriction fragment length polymorphisms (T-RFLP) bacterial community profiling performed on soil DNA extracts indicated that fragment 307 bp from aerobic soil and 212 bp from anaerobic soil were detected only in the herbicide-treated (both unlabeled metolachlor and ¹³C-metolachlor) soils when compared to the untreated control microcosms. T-RFLP profiles from the ultracentrifugation fractions illustrated that these individual fragments experienced an increase in relative abundance at a higher buoyant density (BD) in the labeled fractions when compared to the unlabeled herbicide amendment fractions. The shift in BD of individual T-RFLP fragments in the density-resolved fractions suggested the incorporation of ¹³C from labeled herbicide into the bacterial DNA and enabled the identification of organisms responsible for metolachlor uptake from the soil. Subsequent cloning and 16S rRNA gene sequencing of the ¹³C-enriched fractions implicated the role of organisms closely related to Bacillus spp. in aerobic mineralization and members of Acidobacteria phylum in anaerobic mineralization of metolachlor in soil.     

Multiple origins of secondary temporal fenestrae and orbitozygomatic junctions in birds

Orbitozygomatic junctions (bony connections between the postorbital and zygomatic processes) and secondary temporal fenestrae have long been known to occur in a few avian species, but no comprehensive study of this phenomenon has ever been published. Having surveyed all non‐passerine and most passerine families, we established that the orbitozygomatic junction evolved 18–20 times independently in Cracidae, Phasianoidea (Odontophoridae and Phasianidae), Gastornis, Columbidae (three times), Pteroclidae (Syrrhaptes), Aptornis, Thinocoridae (Thinocorus), Scolopacidae (possibly twice), Ciconiidae (twice), Brachypteraciidae (Uratelornis), Picidae (Picus spp.), Psittacidae (Melopsittacus), Cacatuidae, and Alaudidae (twice). The junction arises in evolution as a result of either elongation of the two processes that meet at angles or the appearance of a bony cross‐bridge in place of a ligament or aponeurosis. In the first case, the junction is initially non‐adaptive, as indicated by its extreme variation (e.g., in Cracinae and Ciconiidae), and may or may not prove functional as an exaptation. Whenever adaptive, the junction supports an expansion of the adductor mandibulae externus (primarily its pars media). In addition, a rostral extension of the tympanic wing has come to cross the temporal fossa in Strigidae (at least twice) and probably Podargus. Altogether, secondary bony connections across the temporal fossa evolved independently at least 21–23 times in neornithine birds.     

Accumulation of ubiquitinated proteins in mouse neuronal cells induced by oxidative stress

Ubiquitin protein conjugates are commonly detected in neuronal brain inclusions of patients with neurodegenerative disorders. The failure to eliminate the ubiquitin-protein deposits in the degenerating neurons may result from changes in the activity of the ubiquitin/ATP-dependent proteolytic pathway. This proteolytic pathway plays a major role in the degradation of short lived, abnormal and denatured proteins. Cadmium is a potent cell poison and is known to affect the ubiquitin pathway and to cause oxidative stress. Increases in protein mixed-disulfides (Pr-SSG) and decreases in glutathione (GSH) are often used as markers of oxidative stress. To investigate the relationship between the ubiquitin pathway and cellular glutathione (GSH), we treated HT4 cells (a mouse neuronal cell line) and rat mesencephalic primary cultures with different concentrations of the heavy metal. We observed marked increases in Pr-SSG as well as decreases in GSH, after exposure of HT4 cells or primary mesencephalic cultures to Cd²⁺. Furthermore, our results show that Cd²⁺ induced the accumulation of ubiquitinated proteins. Detection was by Western blotting of total cell extracts probed with antibodies that recognize ubiquitin-protein conjugates. These results suggest that the ubiquitin-pathway is closely involved in the cell response to cadmium-mediated oxidative stress. Abbreviations: GSH – glutathione; GSSG – glutathione disulfide; Pr-SSG – protein mixed disulfides.     

Benzodiazepine Prevention of Swim Stress-Induced Sensitization of Cortical Biogenic Amines: An in Vivo Microdialysis Study

In vivo microdialysis was used to determine the effect of diazepam, flumazenil and FG-7142 upon the biogenic amine response to acute and repeated swim stress in the medial prefrontal cortex of the rat. Acute swim stress increased norepinephrine levels, although dopamine and serotonin levels remained stable. Upon re-exposure to swim stress twenty-four hours later, sustained increases (200–300% of baseline) in all three biogenic amines were detected. This enhanced response to re-stress was not seen in rats pretreated with either a benzodiazepine agonist (diazepam, 2 mg/kg), an antagonist (flumazenil, 10 mg/kg), or an inverse agonist (FG-7142, 10 mg/kg) given prior to the first swim stress. Therefore, the sensitization of biogenic amine response to re-stress may be prevented by compounds which differ in their activity at the benzodiazepine receptor.     

Salt-induced changes in protein composition in light-grown callus of Mesembryanthemum crystallinum

The halophyte Mesembryanthemum crystallinum (ice plant) has been suggested as a model for salt-tolerance in higher plants. To investigate salt-induced changes in polypeptide patterns at the cellular level, a light-grown callus of M. crystallinum with substantial chlorophyll content, was established and the effect of NaCl on the composition of phenol-extracted protein was examined by SDS- and 2D-polyacrylamide gel electrophoresis (PAGE). SDS-PAGE showed the accumulation of five polypeptides with estimated molecular masses of 40, 34, 32, 29 and 14 kDa was enhanced by the addition of 200 m M NaCl to the culture media. The addition of ABA (10 μ M ) or mannitol (400 m M ) did not elicit the same degree of accumulation of these salt-specific proteins. These polypeptides were classified into two groups according to their course of induction: early responsive (40, 34, 29 kDa) and late-responsive (32, 14 kDa) proteins. In addition, two polypeptides (20, 18 kDa) were transiently accumulated during salt treatment. Further separation of soluble proteins by 2-D gel electrophoresis, either isoelectric focusing (IEF) or non-equilibrium pH-gradient electrophoresis (NEPHGE) followed by SDS-PAGE, showed more alterations in accumulation of polypeptides by NaCl than 1-D gel electrophoresis. Overall, levels of more than 30% of basic polypeptides, detected by NEPHGE/SDS-PAGE, were altered by 200 m M NaCl treatment, while only 10% of neutral and acidic polypeptides, detected by IEF/SDS-PAGE, were changed. The enhanced expression of these proteins by salt in cultured cells is most likely related to the cellular responses to salinity, and not to the mechanism of CAM induction in this facultative halophyte.     

CytochromeBSequences Suggest Convergent Evolution of the Asian Takin and Arctic Muskox

Relationships of the takin (Budorcas taxicolor) and muskox (Ovibos moschatus) have been speculated upon for many years. Morphological and behavioral similarities between these species have led to suggestions that they are closely related. To test the hypothesis that characteristics shared by the takin and muskox stem from a recent common ancestor, we compared sequences of their mitochondrial cytochromebgenes with those of three other species of Caprinae. We present data that may support rejection of the hypothesis of recent common ancestry and suggest that similarities in behavior and morphology in these two species might be attributed to convergent evolution rather than shared phylogeny.     

A Gene Related to Yeast HOS2 Histone Deacetylase Affects Extracellular Depolymerase Expression and Virulence in a Plant Pathogenic Fungus

A gene, HDC1, related to the Saccharomyces cerevisiae histone deacetylase (HDAC) gene HOS2, was isolated from the filamentous fungus Cochliobolus carbonum, a pathogen of maize that makes the HDAC inhibitor HC-toxin. Engineered mutants of HDC1 had smaller and less septate conidia and exhibited an approximately 50% reduction in total HDAC activity. Mutants were strongly reduced in virulence as a result of reduced penetration efficiency. Growth of hdc1 mutants in vitro was normal on glucose, slightly decreased on sucrose, and reduced by 30 to 73% on other simple and complex carbohydrates. Extracellular depolymerase activities and expression of the corresponding genes were downregulated in hdc1 mutant strains. Except for altered conidial morphology, the phenotypes of hdc1 mutants were similar to those of C. carbonum strains mutated in ccSNF1 encoding a protein kinase necessary for expression of glucose-repressed genes. These results show that HDC1 has multiple functions in a filamentous fungus and is required for full virulence of C. carbonum on maize.     

A UNIQUELY CALCIFIED BROWN ALGA FROM HAWAII: NEWHOUSIA IMBRICATA GEN. ET SP. NOV. (DICTYOTALES,PHAEOPHYCEAE)1

An encrusting brown alga from subtidal habitats around the island of Oahu (Hawaiian Islands) represents only the second genus of the class Phaeophyceae to form calcium carbonate, which it deposits primarily as both extracellular and intracellular aragonite, admixed with small (3.3%) amounts of calcite. Plants form expanses 15–100+ cm in extent consisting of horizontally aligned imbricating tiers of distromatic blades 1–4 mm in diameter that are separated from one another by cementing layers of extracellular aragonite, the tiers forming stacks of dozens of laminae and anchored to coral substrata by a basement layer that adheres tightly without haptera or rhizoids. The hypodermal layer of each blade consists of lightly pigmented rectilinear cells bearing either one or two smaller deeply pigmented epidermal cells in cross‐sectional profiles and three or four in long‐sectional profiles, the cells of both layers becoming encased in rigid carbonate skeletons laid down in their outer wall matrices. The successive tiers become stacked by either overgrowing marginal proliferations or new blade primordia that arise from the hypodermal layer of surface laminae and initially spread centrifugally by means of continuous marginal meristems. Neither plurilocular nor unilocular reproductive structures are known. The alga is described as the new genus and species Newhousia imbricata Kraft, G.W. Saunders, Abbott et Haroun and is assigned on the basis of small subunit rDNA gene sequence analyses to the order Dictyotales, family Dictyotaceae, within a strongly supported monophyletic clade that includes Distromium, Lobophora, and Zonaria.