Structural characterization and reactivity of gamma-octamolybdate functionalized by proline

The reaction of molybdate and dl-proline at pH 3.4 results in the formation of a Na₄[Mo₈O₂₆(proO)₂] · 22H₂O complex (pro = proline) in which two proline ligands are attached to molybdenum(VI) ions via monodentate coordination of the carboxylate groups. The structure of the complex was determined by single crystal X-ray diffraction and by combination of ¹H, ¹³C and ⁹⁵Mo NMR spectroscopy techniques in solution. The structure of the complex is strongly dependant on the pH. At native pH 3.4 the octamolybdate-type structure seems to be present in solution, but the increase of pH to 5.8 resulted in a rearrangement of the structure to a heptamolybdate-type structure. At physiological pH, the polyoxometalate framework was completely dissociated into the monomeric unit. The reactivity of the Na₄[Mo₈O₂₆(proO)₂] · 22H₂O towards the hydrolysis of ATP was tested at different pH values. While in solution at pH 3.4 the hydrolysis proceeded to yield AMP (adenosine monophosphate) and ADP (adenosine diphosphate) in nearly equal amounts, reaction mixture at pH 5.8 gave ADP as the only product of hydrolysis after 24 h of reaction. At neutral pH, the hydrolysis of ATP was slower, but it proceeded to yield 75% of ADP after 48 h of reaction.     

Thyroid hormone receptor α<Subscript>1</Subscript>–β<Subscript>1</Subscript> expression in epididymal epithelium from euthyroid and hypothyroid rats

The objectives of the present work were to assess whether epithelial cells from the different segments of epididymis express TRα₁–β₁ isoforms, to depict its subcellular immunolocalization and to evaluate changes in their expression in rats experimentally submitted to a hypothyroid state by injection of 131I. In euthyroid and hypothyroid groups, TR protein was expressed in epididymal epithelial cells, mainly in the cytoplasmic compartment while only a few one showed a staining in the nucleus as well. A similar TR immunostaining pattern was detected in the different segments of the epididymis. In hypothyroid rats, the number of TR-immunoreactive epithelial cells as well as the intensity of the cytoplasmic staining significantly increased in all sections analyzed. In consonance to the immunocytochemical analysis, the expression of TRα₁–β₁ isoforms, assessed by Western blot revealed significantly higher levels of TR in cytosol compared to the nuclear fractions. Furthermore, TR expression of both α₁ and β₁ isoforms and their mRNA levels were increased by the hypothyroid state. The immuno-electron-microscopy showed specific reaction for TR in principal cells associated with eucromatin, cytosolic matrix and mitochondria. The differences in expression levels assessed in control and thyroidectomized rats ascertain a specific function of TH on this organ.     

Neuroglobin and cytoglobin. Fresh blood for the vertebrate globin family

Neuroglobin and cytoglobin are two recently discovered members of the vertebrate globin family. Both are intracellular proteins endowed with hexacoordinated heme-Fe atoms, in their ferrous and ferric forms, and display O₂ affinities comparable with that of myoglobin. Neuroglobin, which is predominantly expressed in nerve cells, is thought to protect neurons from hypoxic–ischemic injury. It is of ancient evolutionary origin, and is homologous to nerve globins of invertebrates. Cytoglobin is expressed in many different tissues, although at varying levels. It shares common ancestry with myoglobin, and can be traced to early vertebrate evolution. The physiological roles of neuroglobin and cytoglobin are not completely understood. Although supplying cells with O₂ is the likely function, it is also possible that both globins act as O₂-consuming enzymes or as O₂ sensors. Here, we review what is currently known about neuroglobin and cytoglobin in terms of their function, tissue distribution and relatedness to the well-known hemoglobin and myoglobin. Strikingly, the data reveal that O₂ metabolism in cells is more complicated than was thought before, requiring unexpected O₂-binding proteins with potentially novel functional features.     

Neuromuscular electrical stimulation increases muscle protein synthesis in elderly type 2 diabetic men

Physical activity is required to attenuate the loss of skeletal muscle mass with aging. Short periods of muscle disuse, due to sickness or hospitalization, reduce muscle protein synthesis rates, resulting in rapid muscle loss. The present study investigates the capacity of neuromuscular electrical stimulation (NMES) to increase in vivo skeletal muscle protein synthesis rates in older type 2 diabetes patients. Six elderly type 2 diabetic men (70 ± 2 yr) were subjected to 60 min of one-legged NMES. Continuous infusions with l-[ring-(13)C(6)]phenylalanine were applied, with blood and muscle samples being collected regularly to assess muscle protein synthesis rates in both the stimulated (STIM) and nonstimulated control (CON) leg during 4 h of recovery after NMES. Furthermore, mRNA expression of key genes implicated in the regulation of muscle mass were measured over time in the STIM and CON leg. Muscle protein synthesis rates were greater in the STIM compared with the CON leg during recovery from NMES (0.057 ± 0.008 vs. 0.045 ± 0.008%/h, respectively, P < 0.01). Skeletal muscle myostatin mRNA expression in the STIM leg tended to increase immediately following NMES compared with the CON leg (1.63- vs. 1.00-fold, respectively, P = 0.07) but strongly declined after 2 and 4 h of recovery in the STIM leg only. In conclusion, this is the first study to show that NMES directly stimulates skeletal muscle protein synthesis rates in vivo in humans. NMES likely represents an effective interventional strategy to attenuate muscle loss in elderly individuals during bed rest and/or in other disuse states.     

A comparative evaluation of phenotypic and molecular methods in the identification of members of the Staphylococcus sciuri group

Members of the Staphylococcus sciuri group (S. sciuri, S. lentus, and S. vitulinus) are coagulase-negative, novobiocin-resistant staphylococci that could be distinguished from other staphylococci on the basis of positive oxidase activity. In the present study, a scheme based on conventional methods and utilization of various carbohydrates was evaluated for the identification of oxidase-positive staphylococci, and validated using two molecular techniques. Of the 173 oxidase-positive staphylococcal tested strains, 161 were identified as S. sciuri, 9 as S. lentus, 2 as S. vitulinus, and one as S. fleurettii by our scheme. The level of agreement with tRNA intergenic length polymorphism analysis (tDNA-PCR) was high (97.5-100% correlation). The accuracy and ease of use of this protocol suggest that it may be useful and valuable in microbiological laboratories for the identification of members of this group.     

Ligation tunes protein reactivity in an ancient haemoglobin: kinetic evidence for an allosteric mechanism in Methanosarcina acetivorans protoglobin

Protoglobin from Methanosarcina acetivorans (MaPgb) is a dimeric globin with peculiar structural properties such as a completely buried haem and two orthogonal tunnels connecting the distal cavity to the solvent. CO binding to and dissociation from MaPgb occur through a biphasic kinetics. We show that the heterogenous kinetics arises from binding to (and dissociation from) two tertiary conformations in ligation-dependent equilibrium. Ligation favours the species with high binding rate (and low dissociation rate). The equilibrium is shifted towards the species with low binding (and high dissociation) rates for the unliganded molecules. A quantitative model is proposed to describe the observed carbonylation kinetics.     

Sexually Dimorphic Intrasexual Duetting in an Otherwise Monomorphic Green Lacewing (Neuroptera, Chrysopidae, Chrysoperla plorabunda): Sexual Selection or Sex Recognition?

Songs produced during heterosexual duets in a green lacewing, C. plorabunda, are sexually monomorphic. However, individuals of either sex will also engage in intrasexual duets, which can exhibit sexual dimorphism. We confined males and females together in various combinations in a small arena to study the phenotypes, behavioral interactions, and functional roles of duetting in this species. The goal was to test whether sexual selection or sex recognition provided the better explanation of song sexual dimorphism. We determined that the monomorphic form of the intrasexual duet was long and stable, and could take place either between males or between females. Such “standard” intrasexual duetting songs were acoustically indistinguishable from heterosexual songs. However, males could also engage other males in special “fast duets” that sped up and terminated abruptly. Equivalent fast duets were not part of the female repertory. Fast duetting songs between males differed significantly from other types of male or female duetting songs in every measurable characteristic, but their role in the mating system was ambiguous. Contrary to one prediction of the sexual selection hypothesis, fast duetting between males occurred less often in situations where it might be the most useful to males in securing mates, i.e., during male-male-female interactions (trios). In addition, fast songs that started, ended, both started and ended, or neither started nor ended duets were acoustically indistinguishable, making it unlikely that females were choosing males based on such variation. However, songs that “both started and ended” fast duets were associated with a significant mating advantage, indicating a possible role for fast duetting in male-male sexual competition. Because the alternative hypothesis of sex recognition was also supported by some of our results, we conclude that aggressive qualities of male-male fast duets probably mediate intrasexual selection, while their increasing tempo serves as an adaptive response to promote rapid sex recognition by truncating unproductive and potentially dangerous intrasexual duetting.     

Testing the usefulness of a simple automatic method for particles abundance and size determination to derive cost-effective biological indicators in large monitoring networks

A simple automatic method has been tested for biological quality assessment in coastal and estuarine waters. Samples collected in routine campaigns along the Basque coast (northern Spain) were analysed by both, a traditional microscopy technique (Utermöhl) and the flow cytometer and microscope (FlowCAM). The FlowCAM was operated in AutoImage mode (i.e. without fluorescence measurements). Two different FlowCAM procedures were carried out in two campaigns separately (2005 and 2008). These differed mainly in the lower size-threshold of the particles sampled: 10 μm in 2005, and 4 μm in 2008. The degree of divergence was evaluated, recognizing that the Utermöhl method and the FlowCAM (as employed here) count differently (i.e. phytoplankton cells and particles, respectively). In general, higher concentrations were observed with the FlowCAM (although there were some exceptions in 2005). Relationships between physico-chemical and FlowCAM variables were studied and patterns of natural variability were identified. However, a clear response to nutrient pressure was not found. It is concluded that the potential of this automatic method for deriving cost-effective indicators is limited, especially in estuaries, due to the high interference with suspended material. Further studies incorporating fluorescence measurements with the FlowCAM may be more promising. The standardization of procedures is highly recommended.     

Resurrecting complexity: the interplay of plasticity and rapid evolution in the multiple trait response to strong changes in predation pressure in the water flea Daphnia magna

A resurrection ecology reconstruction of 14 morphological, life history and behavioural traits revealed that a natural Daphnia magna population rapidly tracked changes in fish predation by integrating phenotypic plasticity and widespread evolutionary changes both in mean trait values and in trait plasticity. Increased fish predation mainly generated rapid adaptive evolution of plasticity (especially in the presence of maladaptive ancestral plasticity) resulting in an important change in the magnitude and direction of the multivariate reaction norm. Subsequent relaxation of the fish predation pressure resulted in reversed phenotypic plasticity and mainly caused evolution of the trait means towards the ancestral pre‐fish means. Relaxation from fish predation did, however, not result in a complete reversal to the ancestral fishless multivariate phenotype. Our study emphasises that the study population rapidly tracked environmental changes through a mosaic of plasticity, evolution of trait means and evolution of plasticity to generate integrated phenotypic changes in multiple traits.     

Food supplementation to optimize inoculative release of the predatory bug Macrolophus pygmaeus in sweet pepper

Biological control is widespread in management of greenhouse sweet pepper crops. Several species of predatory mites, bugs, and parasitoids are used against a wide range of pest species. However, biological control of particular pests like aphids, caterpillars, and the tobacco whitefly, Bemisia tabaci Gennadius, remains problematic. Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a generalist predatory bug which is used on a large scale in Western European tomato greenhouses. It has already been demonstrated that M. pygmaeus is a valuable biocontrol option in sweet pepper crops, but it has yet to find its way into common practice. Macrolophus pygmaeus should be introduced at the start of the growing season and determining an optimal release strategy is a key step in this process. In tomato crops, M. pygmaeus requires supplemental food releases to reach sufficient population numbers and dispersal levels. In this study, the need for food supplementation in sweet pepper is investigated. Three strategies were tested: (1) no food supplementation, (2) local food supplementation, and (3) full field food supplementation. Both population numbers and dispersal rates of the second generation were higher under the third strategy. Macrolophus pygmaeus oviposits near food sources, therefore dispersal rates are higher when food is more spread out. Pest control was achieved in all treatments, but faster and at lower pest levels under the full field strategy.