Sulfonates: novel electron acceptors in anaerobic respiration

The enrichment and isolation in pure culture of a bacterium, identified as a strain of Desulfovibrio, able to release and reduce the sulfur of isethionate (2-hydroxyethanesulfonate) and other sulfonates to support anaerobic respiratory growth, is described. The sulfonate moiety was the source of sulfur that served as the terminal electron acceptor, while the carbon skeleton of isethionate functioned as an accessory electron donor for the reduction of sulfite. Cysteate (alanine-3-sulfonate) and sulfoacetaldehyde (acetaldehyde-2-sulfonate) could also be used for anaerobic respiration, but many other sulfonates could not. A survey of known sulfate-reducing bacteria revealed that some, but not all, strains tested could utilize the sulfur of some sulfonates as terminal electron acceptor. Isethionate-grown cells of Desulfovibrio strain IC1 reduced sulfonate-sulfur in preference to that of sulfate; however, sulfate-grown cells reduced sulfate-sulfur in preference to that of sulfonate. Received: 2 May 1996 / Accepted: 8 June 1996     

Self-electrophoresis is not the mechanism for motility in swimming cyanobacteria.

Swimming cyanobacteria do not have flagella. In principle, they could be propelled by streams of ions flowing from head to tail, i.e., by a self-electrophoretic mechanism. We have ruled out this possibility by showing that cells of a swimming Synechococcus species fail to drift in an external electric field.     

A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths

Molecular systematists need increased access to nuclear genes. Highly conserved, low copy number protein-encoding nuclear genes have attractive features for phylogenetic inference but have heretofore been applied mostly to very ancient divergences. By virtue of their synonymous substitutions, such genes should contain a wealth of information about lower-level taxonomic relationships as well, with the advantage that amino acid conservatism makes both alignment and primer definition straightforward. We tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene in the noctuid moth subfamily Heliothinae, which has probably diversified since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing heliothine groupings strongly supported by previous morphological and allozyme studies. The single most parsimonious gene tree and the neighbor-joining tree for all nucleotides show almost complete concordance with the morphological tree. Homoplasy and pairwise divergence levels are low, transition/transversion ratios are high, and phylogenetic information is spread evenly across gene regions. The EF-1 alpha gene and presumably other highly conserved genes hold much promise for phylogenetics of Tertiary age eukaryote groups.      

Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Lipid remodelling is a widespread strategy in marine heterotrophic bacteria upon phosphorus deficiency

Upon phosphorus (P) deficiency, marine phytoplankton reduce their requirements for P by replacing membrane phospholipids with alternative non-phosphorus lipids. It was very recently demonstrated that a SAR11 isolate also shares this capability when phosphate starved in culture. Yet, the extent to which this process occurs in other marine heterotrophic bacteria and in the natural environment is unknown. Here, we demonstrate that the substitution of membrane phospholipids for a variety of non-phosphorus lipids is a conserved response to P deficiency among phylogenetically diverse marine heterotrophic bacteria, including members of the Alphaproteobacteria and Flavobacteria. By deletion mutagenesis and complementation in the model marine bacterium Phaeobacter sp. MED193 and heterologous expression in recombinant Escherichia coli, we confirm the roles of a phospholipase C (PlcP) and a glycosyltransferase in lipid remodelling. Analyses of the Global Ocean Sampling and Tara Oceans metagenome data sets demonstrate that PlcP is particularly abundant in areas characterized by low phosphate concentrations. Furthermore, we show that lipid remodelling occurs seasonally and responds to changing nutrient conditions in natural microbial communities from the Mediterranean Sea. Together, our results point to the key role of lipid substitution as an adaptive strategy enabling heterotrophic bacteria to thrive in the vast P-depleted areas of the ocean.     

Follow-up assessment of patients with Pure Neural Leprosy in a reference center in Rio de Janeiro—Brazil

IntroductionPure Neural Leprosy (PNL) is a rare clinical form of leprosy in which patients do not present with the classical skin lesions but have a high burden of the disability associated with the disease. Clinical characteristics and follow up of patients in PNL are still poorly described in the literature.ObjectiveThis paper aims to describe the clinical, electrophysiological and histopathological characteristics of PNL patients, as well as their evolution after multidrug therapy (MDT).MethodsFifty-two PNL patients were selected. Clinical, nerve conduction studies (NCS), histopathological and anti-PGL-1serology were evaluated. Patients were also assessed monthly during the MDT. At the end of the MDT, all of the patients had a new neurological examination and 44 were submitted to another NCS.ResultsParesthesia was the complaint most frequently reported by patients, and in the neurological examination the most common pattern observed was impairment in sensory and motor examination and a mononeuropathy multiplex. Painful nerve enlargement, a classical symptom of leprosy neuropathy, was observed in a minority of patients and in the motor NCS axonal injuries, alone or in combination with demyelinating features, were the most commonly observed. 88% of the patients did not present any leprosy reaction during MDT. There was no statistically significant difference between the neurological examinations, nor the NCS pattern, performed before and after the MDT.DiscussionThe classical hallmarks of leprosy neuropathy are not always present in PNL making the diagnosis even more challenging. Nerve biopsy is an important tool for PNL diagnosis as it may guide therapeutic decisions. This paper highlights unique characteristics of PNL in the spectrum of leprosy in an attempt to facilitate the diagnosis and management of these patients.     

One Step forward: Benthic Pelagic Coupling and Indicators for Environmental Status

A large data set from the Eastern Mediterranean was analyzed to explore the relationship between seawater column variables and benthic community status. Our results showed a strong quantitative link between the seawater column variables (Chlorophyll a and Eutrophication Index) and various indicators describing benthic diversity and community composition. The percentage of benthic opportunistic species increased significantly in the stations with high trophic status of the seawater column and so did the strength of the coupling between values of seawater column and benthic indicators. The Eutrophication Index threshold level of 0.85, separating the “Bad and Poor” from “Moderate to High” conditions could serve as an acceptable critical value above which there is a readily observable change in benthic community composition.     

Omega-3 fatty acids deprivation affects ontogeny of glutamatergic synapses in rats: Relevance for behavior alterations

Essential omega-3 polyunsaturated fatty acids (ω3) are crucial to brain development and function, being relevant for behavioral performance. In the present study we examined the influence of dietary ω3 in the development of the glutamatergic system and on behavior parameters in rats. Female rats received isocaloric diets, either with ω3 (ω3 group) or a ω3 deficient diet (D group). In ontogeny experiments of their litters, hippocampal immunocontent of ionotropic NMDA and AMPA glutamatergic receptors subunits (NR2 A\B and GluR1, respectively) and the alpha isoform of the calcium-calmodulin protein kinase type II (αCaMKII) were evaluated. Additionally, hippocampal [³H]glutamate binding and uptake were assessed. Behavioral performance was evaluated when the litters were adult (60 days old), through the open-field, plus-maze, inhibitory avoidance and flinch-jump tasks. The D group showed decreased immunocontent of all proteins analyzed at 02 days of life (P2) in comparison with the ω3 group, although the difference disappeared at 21 days of life (except for αCaMKII, which content normalized at 60 days old). The same pattern was found for [³H]glutamate binding, whereas [³H]glutamate uptake was not affected. The D group also showed memory deficits in the inhibitory avoidance, increased in the exploratory pattern in open-field, and anxiety-like behavior in plus-maze. Taken together, our results suggest that dietary ω3 content is relevant for glutamatergic system development and for behavioral performance in adulthood. The putative correlation among the neurochemical and behavioral alterations caused by dietary ω3 deficiency is discussed.     

A theoretical study of red-shifting and blue-shifting hydrogen bonds occurring between imidazolidine derivatives and PEG/PVP polymers

A theoretical study is presented with the aim to investigate the molecular properties of intermolecular complexes formed by the monomeric units of polyvinylpyrrolidone (PVP) or polyethyleneglycol (PEG) polymers and a set of four imidazolidine (hydantoine) derivatives. The substitution of the carbonyl groups for thiocarbonyl in the hydantoin scaffold was taken into account when analyzing the effect of the hydrogen bonds on imidazolidine derivatives. B3LYP/6-31G(d,p) calculations and topological integrations derived from the quantum theory of atoms in molecules (QTAIM) were applied with the purpose of examining the N–H⋯O hydrogen bond strengths formed between the amide group of the hydantoine ring and the oxygen atoms of PVP and PEG polymers. The effects caused by the N–H⋯O interaction fit the typical evidence for hydrogen bonds, which includes a variation in the stretch frequencies of the N–H bonds. These frequencies were identified as being vibrational red-shifts because their values decreased. Although the values of such calculated interaction energies are between 12 and 33 kJ mol⁻¹, secondary intermolecular interactions were also identified. One of these secondary interactions is formed through the interaction of the benzyl hydrogen atoms with the oxygen atoms of the PVP and PEG structures. As such, we have analyzed the stretch frequencies on the C–H bonds of the benzyl groups, and blue-shifts were identified on these bonds. In this sense, the intermolecular systems formed by hydantoine derivatives and PVP/PEG monomers were characterized as a mix of red-shifting and blue-shifting hydrogen-bonded complexes.     

Effect of chronic treatment with Rosiglitazone on Leydig cell steroidogenesis in rats: <Emphasis Type="Italic">In vivo</Emphasis> and <Emphasis Type="Italic">ex vivo</Emphasis> studies

Background  

The present study was designed to examine the effect of chronic treatment with rosiglitazone - thiazolidinedione used in the treatment of type 2 diabetes mellitus for its insulin sensitizing effects - on the Leydig cell steroidogenic capacity and expression of the steroidogenic acute regulatory protein (StAR) and cholesterol side-chain cleavage enzyme (P450scc) in normal adult rats.