Purification and partial amino acid sequencing of a mycorrhiza-related chitinase isoform from Glomus mosseae-inoculated roots of Pisum sativum L.

Colonization of Pisum sativum L. cv. Frisson roots with the arbuscular mycorrhizal fungus Glomus mosseae leads to the induction of four acidic symbiosis-related chitinase (SR-chi) isoforms (EC 3.2.1.14). These isoforms were characterized as 30-kDa proteins with isoelectric points ranging between 5.2 and 5.85. One of these SR-chis was purified by affinity and anion-exchange chromatographies, and isoelectric focusing electrophoresis. The sequences of four internal peptides were obtained. They showed high homology to a class-I chitinase isoform from pea shoots. Parts of the conserved regions of class-I chitinases were found in this SR-chi. This result strongly supports the argument that this SR-chi isoform is of plant origin. The functional role of the SR-chis in arbuscular mycorrhizal symbiosis is discussed.     

Relaxometric evaluation of novel manganese(II) complexes for application as contrast agents in magnetic resonance imaging

Three novel Mn(II) complexes bearing benzyloxymethyl functionalities are reported and their ability to enhance water (1H and 17O) relaxation times is investigated in detail. Two of them contain one coordinated water molecule and display relaxivity values only slightly smaller than those shown by the most clinically used contrast agents (e.g. [Gd(DTPA)(H2O)]2-). Moreover, in these Mn(II) chelates the exchange rate of the coordinated water is ca. one order of magnitude higher if compared to the exchange rates previously reported for Gd(III) complexes with octadentate ligands. The occurrence of such fast exchange rates of the coordinated water is exploited in the formation of macromolecular adducts with human serum albumin to attain systems displaying relaxivity values in the upper range of those so far reported for analogous Gd(III) systems. These results strongly support the view that Mn(II) complexes, in spite of the lower effective magnetic moment, can be considered as viable alternatives to the currently used Gd(III) complexes as contrast agents for MRI applications.     

Relaxometric characterization of human hemalbumin

Hemalbumin [i.e., Fe(III)-protoporphyrin IX-human serum albumin; Fe(III)heme-HSA] is an important intermediate in the recovery of heme iron following hemolysis. Relaxometric data are consistent with the occurrence of a hexacoordinated high-spin Fe(III) center with no water in the inner coordination sphere. The relatively high relaxation enhancement observed for an aqueous solution of Fe(III)heme-HSA (r1p=4.8 mM(-1)s(-1) at 20 MHz, pH 7, and 25 C) is ascribed to the occurrence of a strong contribution from water molecules in the second coordination sphere. Structural analysis of the putative binding region has been performed by a Monte Carlo simulated annealing procedure, which allowed us to identify His105 and Tyr148 as axial ligands. The role of a tyrosinate as the sixth Fe(III)heme ligand is supported by the pH-dependent analysis. Interestingly, when Fe(III) is replaced by Mn(III), the occurrence of a fast exchanging water molecule at pH values close to neutrality is detected. As the pH is increased, the Mn(III) containing system behaves analogously to Fe(III)heme-HSA. At higher pH, the phenolate ligand is eventually displaced by OH- from both Fe(III) and Mn(III) centers. Support for the proposed bonding scheme has been gained also from competitive binding assays for the sixth coordination site by fluoride, azide, and imidazole ligands.     

Short stature in a patient with cystic fibrosis caused by a 6.7-kb human growth hormone gene deletion.

A recent longitudinal study in children with cystic fibrosis (CF) challenged the common idea that CF is causing short stature. The data, however, showed clearly that short stature cannot be explained by CF alone after the first year of life. We report on a girl suffering from CF and short stature in whom DNA analysis using polymerase chain reaction and Southern blot techniques of the human growth hormone (hGH) gene cluster revealed a 6.7-kb gene deletion encompassing the hGH-1 gene. Anti-hGH antibodies of polyclonal origin developed, leading to a growth arrest after only 2 months of hGH replacement. In addition, a family study was performed, and the haplotypes of the CF gene and hGH gene cluster were analyzed.     

Classification of β-hairpin repeat proteins

In recent years, a number of new protein structures that possess tandem repeats have emerged. Many of these proteins are comprised of tandem arrays of β-hairpins. Today, the amount and variety of the data on these β-hairpin repeat (BHR) structures have reached a level that requires detailed analysis and further classification. In this paper, we classified the BHR proteins, compared structures, sequences of repeat motifs, functions and distribution across the major taxonomic kingdoms of life and within organisms. As a result, we identified six different BHR folds in tandem repeat proteins of Class III (elongated structures) and one BHR fold (up-and-down β-barrel) in Class IV (“closed” structures). Our survey reveals the high incidence of the BHR proteins among bacteria and viruses and their possible relationship to the structures of amyloid fibrils. It indicates that BHR folds will be an attractive target for future structural studies, especially in the context of age-related amyloidosis and emerging infectious diseases. This work allowed us to update the RepeatsDB database, which contains annotated tandem repeat protein structures and to construct sequence profiles based on BHR structural alignments.     

Influence of nutrient management on growth and nutrient use efficiency of two plant species for mineland revegetation

Rehabilitation of degraded areas by mining activities is necessary to achieve sustainable mining. For an effective revegetation, the understanding of plant growth and the nutrient requirements of native plant species, especially those with the potential to be used in the rehabilitation of mined areas such as waste piles or mine pits, is indispensable. In this study, we evaluated the growth performance, nutrient levels, and nutrient use efficiency of an endemic plant (Mimosa acutistipula var. ferrea) and ruderal shrub (Solanum crinitum) that are both found in ferriferous savannas, locally called “canga” in Carajás Mineral Province, Brazil. An experiment was conducted under greenhouse conditions using samples of three different soils (oxisol, canga soil, and iron mining waste) without and with nutrient application; additionally, an omission trial was carried out in canga soils. Fertilization increased the growth of both plant species in all substrates. Macronutrient omission reduced the growth of plants stronger than micronutrient omission, indicating that the lack of N, P, and K may especially impact the rehabilitation of areas. The growth of S. crinitum was higher than M. acutistipula var. ferrea, highlighting its preponderance in mineland rehabilitation, although concerns regarding its role as a ruderal species persist. Therefore, further research is necessary for a risk assessment of the propagation of S. crinitum within mineland restoration projects.     

Breakdown in classical biological control of Argentine stem weevil: a matter of time

Earlier study at a national scale has shown that insect pests in agriculture can develop resistance to natural enemies following ongoing expansion and simplification of agricultural systems. Here, we used 25 years of field-sampling data segmented into three distinct ecoregions in New Zealand to show that parasitism rate of a key pasture pest (Listronotus bonariensis, Argentine stem weevil) by the introduced parasitoid Microctonus hyperodae has significantly declined. However, this decline has not happened simultaneously in all three ecoregions but with a one year time-lag. The variation in parasitism rate trends might be attributed to subsets of the weevil populations that became resistant to their biocontrol agent once having been exposed to seven years selection pressure (ca. 14 generations) since the parasitoid releases. This result supports the hypothesis that adaptation leading to resistance might have similarly occurred in different parts of the country indicating that the genetic variation needed for the acquisition of resistance was equally present everywhere.     

Ecological guidelines for designing networks of marine reserves in the unique biophysical environment of the Gulf of California

No-take marine reserves can be powerful management tools, but only if they are well designed and effectively managed. We review how ecological guidelines for improving marine reserve design can be adapted based on an area’s unique evolutionary, oceanic, and ecological characteristics in the Gulf of California, Mexico. We provide ecological guidelines to maximize benefits for fisheries management, biodiversity conservation and climate change adaptation. These guidelines include: representing 30% of each major habitat (and multiple examples of each) in marine reserves within each of three biogeographic subregions; protecting critical areas in the life cycle of focal species (spawning and nursery areas) and sites with unique biodiversity; and establishing reserves in areas where local threats can be managed effectively. Given that strong, asymmetric oceanic currents reverse direction twice a year, to maximize connectivity on an ecological time scale, reserves should be spaced less than 50–200 km apart depending on the planktonic larval duration of target species; and reserves should be located upstream of fishing sites, taking the reproductive timing of focal species in consideration. Reserves should be established for the long term, preferably permanently, since full recovery of all fisheries species is likely to take?>?25 years. Reserve size should be based on movement patterns of focal species, although marine reserves?>?10 km long are likely to protect?~?80% of fish species. Since climate change will affect species’ geographic range, larval duration, growth, reproduction, abundance, and distribution of key recruitment habitats, these guidelines may require further modifications to maintain ecosystem function in the future.     

Geographical variation in egg size of the Great Tit Parus major: a new perspective

A recent study on geographical variation in egg size of Great Tits Parus major concluded that: (1) mean egg size tended to increase with increasing latitude; and (2) mean egg size was positively correlated with mean clutch size. Including new data on both egg and clutch size, we reanalysed the relationships between egg size, clutch size and latitude, and investigated the possible effects of habitat type, female body size and egg shape on these relationships. We found that (1) egg volume showed minimum values around 51°N, increasing both north and southwards; (2) female body size increased linearly with increasing latitude; (3) female body size was positively correlated with egg breadth, but not with egg length or egg volume; (4) the sphericity index of the eggs (breadth to length ratio) was largest at medium latitudes, and eggs were more elongated towards the north and the south; (5) the relationship between clutch size and latitude was curvilinear, with the largest clutch sizes at intermediate latitudes; (6) egg size was not correlated with clutch size when the complete latitudinal range was considered, but egg size was negatively correlated with clutch size between 40 and 51°N; and (7) egg size did not differ among habitat types. We suggest that female body size (which probably limits egg breadth), and the pressure for producing large eggs (which in turn increases the reproductive success) are the main determinants of geographical variation in egg size and shape. Populations of small-bodied Great Tits seem to escape from the limits of their size, producing relatively elongated eggs, so that from a certain latitude southwards, egg volume does not decrease in spite of a decrease in female body size. Moreover, the negative relationship between egg and clutch size at low latitudes suggests that energetic trade-offs may also contribute to determine egg size in the south.