1,721,924 research outputs found
Replication Data for: Improving Child Health and Cognition: Evidence from a School-Based Nutrition Intervention in India
No full textKrämer, Marion, Kumar, Santosh, and Vollmer, Sebastian, (2021) “Improving Child Health and Cognition: Evidence from a School-Based Nutrition Intervention in India.” Review of Economics and Statistics 103:5, 818–834
Two ABC Transporters and a Periplasmic Metallochaperone Participate in Zinc Acquisition in Paracoccus Denitrificans
No full textBacteria must acquire the essential element zinc from extremely limited environments, and this function is performed largely by ATP binding cassette (ABC) transporters. These systems rely on a periplasmic or extracellular solute binding protein (SBP) to bind zinc specifically with a high affinity and deliver it to the membrane permease for import into the cytoplasm. However, zinc acquisition systems in bacteria may be more complex, involving multiple transporters and other periplasmic or extracellular zinc binding proteins. Here we describe the zinc acquisition functions of two zinc SBPs (ZnuA and AztC) and a novel periplasmic metallochaperone (AztD) in Paracoccus denitrificans. ZnuA was characterized in vitro and demonstrated to bind as many as 5 zinc ions with a high affinity. It does not interact with AztD, in contrast to what has been demonstrated for AztC, which is able to acquire a single zinc ion through associative transfer from AztD. Deletions of the corresponding genes singly and in combination show that either AztC or ZnuA is sufficient and essential for robust growth in zinc-limited media. Although AztD cannot support transport of zinc into the cytoplasm, it likely functions to store zinc in the periplasm for transfer through the AztABCD system.School of Natural Sciences and Mathematic
Environmental and Genetic Determinants of Biofilm Formation in Paracoccus denitrificans
No full text
The bacterium
Paracoccus denitrificans
is a model for the process of denitrification, by which nitrate is reduced to dinitrogen during anaerobic growth. Denitrification is important for soil fertility and greenhouse gas emission and in waste and water treatment processes. The ability of bacteria to grow as a biofilm attached to a solid surface is important in many different contexts. In this paper, we report that attached growth of
P. denitrificans
is stimulated by nitric oxide, an intermediate in the denitrification pathway. We also show that calcium ions stimulate attached growth, and we identify a large calcium binding protein that is required for growth on a polystyrene surface. We identify components of a signaling pathway through which nitric oxide may regulate biofilm formation. Our results point to an intimate link between metabolic processes and the ability of
P. denitrificans
to grow attached to a surface.
</jats:p
Anemia, diet, and cognitive development: Impact of health information on diet quality and child nutrition in rural India
No full textPROTOZOAN CILIATES FROM THE SULPHIDIC SEDIMENTS OF POZZO DEI CRISTALLI (FRASSASI CAVES, ITALY)
No full textThe sulfide-rich Frasassi cave complex (Genga, AN, Italy) host a still largely uncharacterised
microbiota whom study might offers an intriguing view on the solutions adopted by the different
species to survive and interact with each others in a such harsh environment. Beside the absence
of light and low temperatures (12-13°C), another environmental shaping factors is represented by
highly variable sulphide concentrations (from 0 up to 415 μM H2S). Moreover, up to now, very few
study attempted to describe ciliate communities from caves as well as, their fluctuation with respect
to environmental factors. In this analysis of the ciliate fauna of Frasassi caves, we focused our
attention on a sampling site known as “Pozzo dei Cristalli” which is highly diversified since it
include several microhabitats represented by small sulfidic (H2S-rich) ponds, streams and spring
as well as, deep and shallow muddy, stagnant lakes. Periodic sampling was realised from 2009 to
2011 in the form of water-sediments, picked up by scraping the surface. A total of 31 species were
identified; belonging to 9 classes, 15 orders and 23 genera. It was observed that some species e.g.
Urocentrum turbo, Coleps hirtus, Euplotes sp, showed adaptation for the cave environment (high
sulphur tolerance, Photo-sensitivity, feeding behaviour). Our future goal will be to study spatiotemporal
variations in the ciliate communities employing cultivation-independent, molecular
profiling assay (T-RFLP). Finally, integrating taxonomy and molecular data to obtain a more
rigorous and detailed picture of the ciliate diversity in cave sediments
Morphology, morphogenesis and molecular phylogeny of a novel soil ciliate, Pseudouroleptus plestiensis n. sp. (Ciliophora, Oxytrichidae), from the uplands of Colfiorito, Italy
No full textThe terrestrial oxytrichid ciliate Pseudouroleptus plestiensis n. sp., isolated from soil samples collected from the uplands of Colfiorito (Umbria region, Italy), was investigated using live observation and protargol impregnation. The morphology, morphogenesis and molecular phylogeny inferred from small-subunit (SSU) rRNA gene sequences were studied. The novel species is mainly characterized by the following: a cell size of about 145×35 μm in vivo; two ellipsoidal macronuclear nodules and two to four micronuclei; adoral zone about 26% of body length with a mean of 30 membranelles; about 40 cirri in the right marginal row and 38 in the left marginal row; left fronto-ventral row consisting of about 27-40 cirri, right fronto-ventral row of about three to seven cirri forming a short row to the right of the rear portion of the left fronto-ventral row; one parabuccal cirrus ( = III/2), one buccal and one post-peristomial cirrus; and four dorsal kineties with caudal cirri at the end of kineties 1 and 2. The morphogenesis of the novel species is similar to that of Pseudouroleptus caudatus. Phylogenetic analyses based on SSU rRNA gene sequences consistently placed the novel species within the family Oxytrichidae Ehrenberg, 1838, clustering with P. caudatus and the genus Strongylidium. The results from the present study contribute to the expanding knowledge of the diversity of ciliates in Italian soil
Rigidosticha italiensis n. gen., n. sp. (Ciliophora, Spirotricha), a novel large hypotrich ciliate from the soil of Lombardia, Italy
No full textThe morphology of Rigidosticha italiensis n. gen., n. sp., which was found in a soil sample collected from an uncultivated field in Lombardia, Italy, was investigated using live observation and protargol staining. Rigidosticha n. gen. is characterised by a rigid body, undulating membranes resembling a Steinia pattern, oxytrichid frontal ciliature, distinct mid-ventral cirral pairs, transverse cirri, one right and one left row of marginal cirri, absence of dorsal kinety 3 fragmentation, more than two dorsomarginal rows, and caudal cirri. The new species shows the following features: size in vivo 230–330 × 100–170 μm, on average 230 × 115 μm in protargol preparations; two ellipsoidal macronuclear nodules; 51 adoral membranelles; one buccal cirrus; one parabuccal cirrus; two frontoterminal cirri; 16 mid-ventral cirral pairs; and three transverse cirri. Rigidosticha mainly differs from Rigidothrix, Afrophrya, Uroleptus, and Territricha, in having the undulating membranes in Rigidosticha (vs. oxytrichid and cyrtohymenid) pattern. The oxytrichid frontal ciliature and midventral pattern in the present species further support the CEUU (Convergent Evolution of Urostylids and Uroleptids) hypothesis
- …
