Cultivation of hitherto-uncultured bacteria belonging to the Verrucomicrobia subdivision 1 from the potato (Solanum tuberosum L.) rhizosphere

The role of dominant bacterial groups in the plant rhizosphere, e.g., those belonging to the phyla Acidobacteria and Verrucomicrobia, has, so far, not been elucidated, and this is mainly due to the lack of culturable representatives. This study aimed to isolate hitherto-uncultured bacteria from the potato rhizosphere by a combination of cultivation approaches. An agar medium low in carbon availability (oligotrophic agar medium) and either amended with potato root exudates or catalase or left unamended was used with the aim to improve the culturability of bacteria from the potato rhizosphere. The colony forming unit numbers based on colonies and microcolonies were compared with microscopically determined fluorescence-stained cell numbers. Taxonomical diversity of the colonies was compared with that of library clones made from rhizosphere DNA, on the basis of 16S rRNA gene comparisons. The oligotrophic media amended or not with catalase or rhizosphere extract recovered up to 33.6% of the total bacterial numbers, at least seven times more than the recovery observed on R2A. Four hitherto-uncultured Verrucomicrobia subdivision 1 representatives were recovered on agar, but representatives of this group were not found in the clone library. The use of oligotrophic medium and its modifications enabled the growth of colony numbers, exceeding those on classical agar media. Also, it led to the isolation of hitherto-uncultured bacteria from the potato rhizosphere. Further improvement in cultivation will certainly result in the recovery of other as-yet-unexplored bacteria from the rhizosphere, making these groups accessible for further investigation, e.g., with respect to their possible interactions with plants.

A split-pot experiment with sorghum to test a root water uptake partitioning model

Correct modeling of root water uptake partitioning over depth is an important issue in hydrological and crop growth models. Recently a physically based model to describe root water uptake was developed at single root scale and upscaled to the root system scale considering a homogeneous distribution of roots per soil layer. Root water uptake partitioning is calculated over soil layers or compartments as a function of respective soil hydraulic conditions, specifically the soil matric flux potential, root characteristics and a root system efficiency factor to compensate for within-layer root system heterogeneities. The performance of this model was tested in an experiment performed in two-compartment split-pot lysimeters with sorghum plants. The compartments were submitted to different irrigation cycles resulting in contrasting water contents over time. The root system efficiency factor was determined to be about 0.05. Release of water from roots to soil was predicted and observed on several occasions during the experiment; however, model predictions suggested root water release to occur more often and at a higher rate than observed. This may be due to not considering internal root system resistances, thus overestimating the ease with which roots can act as conductors of water. Excluding these erroneous predictions from the dataset, statistical indices show model performance to be of good quality.

Natural regeneration of Atlantic Forest species in the understory of Eucalyptus saligna Smith. in a former forest production unit at the Parque das Neblinas, Bertioga, SP

This study aimed at characterizing the potential for natural regeneration of native vegetation in the under-story of an earlier Eucalyptus saligna Smith production stand. The study was carried out at the Parque das Neblinas, Bertioga municipality, SP, in a 45 ha third rotation stand; which had been abandoned 15 years ago for natural regeneration to occur. The sampling was done in 24 plots of 20 x 40 m. The sampled area was of 19,200 m(2), with inventory made of 100% of the eucalyptus trees. All regeneration trees with a height >= 1.30 m and DBH >= 5.0 cm were measured, as well as adult individuals with DBH >= 5.0 cm; surveyed in two size classes. 1,417 individuals of E. saligna were measured, with a density of 738,02 individuals/ha and a basal area of 22.69 m(2)/ha. Among 2,763 natural regeneration individuals, 111 species belonged to 66 genera and 34 botanical families. The species represented 43.7% of the tree richness of neighboring native forest fragments. The total estimated density and the basal area were respectively 1,052.6 individuals/ha and 6.4 m(2)/ha of autochthonous trees with DBH >= 5.0 cm (Class 1); while for regeneration there were 3,864.58 individuals/ha, and 2.76 m(2)/ha of individuals with a height >= 1.30 m and DBH <5.0 cm (Class 2). Shannon diversity (H`) was 2.83 and 3.68, respectively, for Classes 1 and 2, and the corrected species richness for a 1000-individual sample (R(1000)) were 75.6 and 87.29 (Fisher`s a index) for the same classes. The majority of the species (34.84%) was typical from the understory of wet tropical forest and had zoochoric fruit dispersal (67.57%). The results indicate that, under these conditions, a eucalyptus forest is able to provide adequate regeneration niches for native vegetation, and may represent a sink habitat for local populations.

Physical-chemical and functional properties of maca root starch (Lepidium meyenii Walpers)

The starch of maca (Lepidium meyenii Walpers) presented oval and irregular morphology, with granule size between 7.4 and 14.9 mu m in length and 5.8 and 9.3 mu m in diameter. The isolated starch showed the following features: purity of 87.8%, with 0.28% lipids, 0.2% fibre and 0.12% fixed mineral residue, and no protein detected; the ratio between the amylose and amylopectin contents were 20:80: the solubility at 90 degrees C was 61.4%, the swelling power was 119.0g water/g starch and the water absorption capacity was 45.9 g water/g starch; the gel turbidity rose 44% during the storing time; the gelatinization temperature was 47.7 degrees C and the transition enthalpy 6.22 J/g; the maximum viscosity reached 1260 UB at 46.4 degrees C, with breakdown, setback and consistence of 850, 440 and -410 UB, respectively. The low gelling temperature and the stability during gel refrigeration could be adequate for foods requiring moderate temperature process, but not for frozen food. (C) 2008 Elsevier Ltd. All rights reserved.

Nosocomial outbreak by imipenem-resistant metallo-beta-lactamase-producing Pseudomonas aeruginosa in an adult intensive care unit in a Brazilian teaching hospital

Objective: To describe an outbreak of imipenem-resistant metallo-beta-lactamase-producing Pseudomonas aeruginosa, enzyme type bla, by horizontal transmission in patients admitted to a mixed adult ICU. Methods: A case-control study was carried out, including 47 patients (cases) and 122 patients (control) admitted to the mixed ICU of a university hospital in Minas Gerais. Brazil from November 2003 to July 2005. The infection site, risk factors, mortality, antibiotic susceptibility, metallo-beta-lactamase (MBL) production, enzyme type, and clonal diversity were analyzed, Results: A temporal/spatial relationship was detected in most patients (94%), overall mortality was 55.3%, and pneumonia was the predominant infection (85%). The majority of isolates (95%) were resistant to imipenem and other antibiotics, except for polymyxin, and showed MBL production (76.7%). Only bla SPM-1 (33%) was identified in the 15 specimens analyzed. In addition, 4 clones were identified, with a predominance of clone A (61.5%) and B (23.1%). On multivariate analysis, advanced age, mechanical ventilation, tracheostomy, and previous imipenem use were significant risk factors for imipenem-resistant P. aeruginosa infection. Conclusions: Clonal dissemination of MBL-producing P. aeruginosa strains with a spatial/temporal relationship disclosed problems in the practice of hospital infection control, low adherence to hand hygiene, and empirical antibiotic use. (C) 2008 Elsevier Espana, S.L. All rights reserved.

Aboriginal and Torres Strait Islander Studies Unit Annual Report

Welcome to the 2002 Aboriginal and Torres Strait Islander Studies Unit Annual Report. This report is a brief summary of Unit activities during the 2002 calendar year. The Unit provides personal and academic support for Aboriginal and Torres Strait Islander students and specifically aims to increase the recruitment, retention, academic performance and graduation rates of Indigenous students. The Unit also administers schemes to help Indigenous students gain access to, and receive support in, tertiary studies such as the Alternative Entry scheme and the federally funded Aboriginal Tutorial Assistance Scheme (ATAS). The Unit is also the focus for teaching and research in Aboriginal and Torres Strait Islander Studies at the University of Queensland.

Aboriginal and Torres Strait Islander Studies Unit Annual Report 2003

Welcome to the 2003 Aboriginal and Torres Strait Islander Studies Unit Annual Report. This report is a brief summary of Unit activities during the 2003 calendar year. The Unit provides personal and academic support for Aboriginal and Torres Strait Islander students and specifically aims to increase the recruitment, retention, academic performance and graduation rates of Indigenous students. The Unit also administers schemes to help Indigenous students gain access to, and receive support in, tertiary studies such as the Alternative Entry scheme and the federally funded Aboriginal Tutorial Assistance Scheme (ATAS). The Unit is also the focus for teaching and research in Aboriginal and Torres Strait Islander Studies at the University of Queensland.

Aboriginal and Torres Strait Islander Studies Unit Annual Report 2005

Welcome to the 2005 Aboriginal and Torres Strait Islander Studies Unit Annual Report. This report is a brief summary of Unit activities during the 2005 calendar year. The Unit provides personal and academic support for Aboriginal and Torres Strait Islander students and specifically aims to increase the recruitment, retention, academic performance and graduation rates of Indigenous students. The Unit also administers schemes to help Indigenous students gain access to, and receive support in, tertiary studies such as the Alternative Entry scheme and the federally-funded Indigenous Tutorial Assistance Scheme (ITAS). The Unit is also the focus for teaching and research in Aboriginal and Torres Strait Islander Studies at the University of Queensland.

Radiative Relaxation Quantum Yields for Synthetic Eumelanin

We report absolute values for the radiative relaxation quantum yield of synthetic eumelanin as a function of excitation energy. These values were determined by correcting for pump beam attenuation and emission reabsorption in both eumelanin samples and fluorescein standards over a large range of concentrations. Our results confirm that eumelanins are capable of dissipating >99.9% of absorbed UV and visible radiation through nonradiative means. Furthermore, we have found that the radiative quantum yield of synthetic eumelanin is excitation energy dependent. This observation is supported by corrected emission spectra, which also show a clear dependence of both peak position and peak width on excitation energy. Our findings indicate that photoluminescence emission in eumelanins is derived from ensembles of small chemically distinct oligomeric units that can be selectively pumped. This hypothesis lends support to the theory that the basic structural unit of eumelanin is oligomeric rather than heteropolymeric.

Acquisition of the English article system in SLA and the Missing Surface Inflection Hypothesis

This paper examines the article system in interlanguage grammar focusing on Japanese learners of English, whose native language lacks articles. It will be demonstrated that for the acquisition of the English article system, count/mass distinctions and definiteness are the crucial factors. Although Japanese does not employ the article system to encode these aspects, it will be argued that they are nevertheless syntactically encoded through its classifier system. Hence, the problem for these learners must be to map these features onto the appropriate surface forms as the Missing Surface Inflection Hypothesis predicts (Prévost & White 2000). This suggestion will further be supported empirically by a fill-in-the article task. It will be concluded that these Japanese learners understand the English article system fairly well, possibly due to their native language, yet have problems with realizing the relevant features (i.e. count/mass distinctions and definiteness) in the target language.

Effect of Mn deficiency and legume inoculation on rhizosphere pH in highly alkaline soils

Although plant growth is often limited at high pH, little is known about root-induced changes in the rhizospheres of plants growing in alkaline soils. The effect of Mn deficiency in Rhodes grass (Chloris gayana cv. Pioneer) and of legume inoculation in lucerne (Medicago sativa L. cv. Hunter River), on the rhizosphere pH of plants grown in highly alkaline bauxite residue was investigated. Rhizosphere pH was measured quantitatively, with a micro pH electrode, and qualitatively, with an agar/pH indicator solution. Manganese deficiency in Rhodes grass increased root-induced acidification of the rhizosphere in a soil profile in which N was supplied entirely as NO3-. Rhizosphere pH in the Mn deficient plants was up to 1.22 pH units lower than that of the bulk soil, while only 0.90 to 0.62 pH units lower in plants supplied with adequate Mn. When soil N was supplied entirely as NO3-, rhizosphere acidification was more efficient in inoculated lucerne (1.75 pH unit decrease) than in non-inoculated lucerne (1.16 pH unit decrease). This difference in capacity to lower rhizosphere pH is attributable to the ability of the inoculated lucerne to fix atmospheric N2 rather than relying on the soil N (NO3 ) reserves as the non-inoculated plants. Rhizosphere acidification in both Rhodes grass and lucerne was greatest in the meristematic root zone and least in the maturation root zone.