Comment on "Protein sequences from mastodon and Tyrannosaurus rex revealed by mass spectrometry"

We used authentication tests developed for ancient DNA to evaluate claims by Asara et al. (Reports, 13 April 2007, p. 280) of collagen peptide sequences recovered from mastodon and Tyrannosaurus rex fossils. Although the mastodon samples pass these tests, absence of amino acid composition data, lack of evidence for peptide deamidation, and association of alpha1(I) collagen sequences with amphibians rather than birds suggest that T. rex does not.     

Insight in the PCB-degrading functional community in long-term contaminated soil under bioremediation

Purpose  

A small-scale bioremediation assay was developed in order to get insight into the functioning of a polychlorinated biphenyl (PCB) degrading community during the time course of bioremediation treatment of a contaminated soil. The study was conducted with the aim to better understand the key mechanisms involved in PCB-removal from soils.     

Compatibility with killer explains the rise of RNAi-deficient fungi

The RNA interference (RNAi) pathway is found in most eukaryotic lineages but curiously is absent in others, including that of Saccharomyces cerevisiae. We show that reconstituting RNAi in S. cerevisiae causes loss of a beneficial double-stranded RNA virus known as killer virus. Incompatibility between RNAi and killer viruses extends to other fungal species in that RNAi is absent in all species known to possess double-stranded RNA killer viruses, whereas killer viruses are absent in closely related species that retained RNAi. Thus, the advantage imparted by acquiring and retaining killer viruses explains the persistence of RNAi-deficient species during fungal evolution.     

Stickstoffaufnahme und ‐Freisetzung durch Ruderalzönosen auf Dauerbrachen im Mitteldeutschen Trockengebiet

Auf einer selbstbegrünten Dauerbrache ohne Pflegemaßnahmen (seit 1991) wurden in 4–6 wöchigen Abständen die Trockenmasse (TM) und die N‐Mengen im Pflanzenspross und in verschiedenen Streufraktionen untersucht. In Abhängigkeit von der dominierenden Pflanzenart wurden bis zu 2700 g TM/m² (= 270 dt TM/ha) gebildet. Darin waren bis zu 48 g N/m² (=48g N/ha) enthalten. Nach dem Absterben der Pflanzenbestände bildet sich Streu, die sich auf diesem Standort akkumulierte. In Abhängigkeit von der Güllebelastung des Bodens (hohe Belastung, geringe Belastung, unbelastet) wurde das Maximum der Streu‐TM mit 1345, 1506 bzw. 970 g TM/m² nach 4, 5 bzw. 6 Jahren Brachedauer erreicht. Die N‐Mengen in der Streu stiegen bis zum letzten untersuchten Jahr 1995 allmählich an. Die maximalen Jahresmittelwerte betrugen bei hoher Güllebelastung 27, bei geringer Güllebelastung 31 und ohne Gülle 10 g N/m²(= 270, 310 bzw. 100 kg N/ha). Die N‐Freisetzung aus der Streu begann noch im gleichen Jahr. Sie war im Wesentlichen auf der unbelasteten Parzelle nach 2 Jahren, auf den Gülleparzellen nach 3 Jahren abgeschlossen. Zukünftig müssen die Teilprozesse der N‐Freisetzung aus der Streu und ihre Wechselwirkungen sowie der Einbau des unkrautbürtigen? in die Boden‐N‐Fraktionen und die Wiederaufnahme durch die nächsten Pflanzengenerationen intensiver untersucht werden.     

A new approach to kelp mariculture in Chile: production of free-floating sporophyte seedlings from gametophyte cultures of Lessonia trabeculata and Macrocystis pyrifera

Substantial amounts of Macrocystis and Lessonia are traditionally harvested and exported from Chile as raw material for alginate. Because of intense mariculture of abalone (Haliotis ssp.), herbivorous molluscs that feed on brown kelps, pressure on local populations of Macrocystis and Lessonia has increased to critical levels within the past 5 years, strongly supporting efforts to produce algae maricultured biomass. Here, we present our results on the development of new techniques for large‐scale kelp mariculture in Chile. We have abandoned the traditional technique of direct spore seeding onto inoculation lines. Instead, we used gametophyte cultures that were manipulated to enter gametogenesis and to produce synchronous batches of 10⁴–10⁵ embryos. Juvenile sporophytes were cultured under permanent aeration and agitation, floating unattached in contamination‐free glass bottles up to 10 L, plexiglass cylinders and 800 L greenhouse tanks. When holdfast initials were formed at a size of 8 cm, the sporophytes were spliced into Nylon rope fragments and transferred to the sea. Twelve months after initiation of gametogenesis in the laboratory, Macrocystis pyrifera attained 14 m length and 80 kg fresh weight m^?1 line in the sea. For Lessonia trabeculata 6 months after gametogenesis initiation, 0.25 kg fresh weight m^?1 was attained in the sea.     

Antibacterial Polyketides from the Marine Alga-Derived Endophitic Streptomyces sundarbansensis: A Study on Hydroxypyrone Tautomerism

Polyketide 13 [=2-hydroxy-5-((6-hydroxy-4-oxo-4H-pyran-2-yl)methyl)-2-propylchroman-4-one] and three related known compounds 7, 9 and 11 were obtained and structurally characterized from Streptomyces sundarbansensis strain, an endophytic actinomycete isolated from the Algerian marine brown algae Fucus sp. Compound 13 was obtained as the major metabolite from optimized culture conditions, by using Agar state fermentation. Due to tautomeric equilibrium, 13 in CD₃OD solution was able to incorporate five deuterium atoms, as deduced by NMR and ESI-MS/MS analysis. The 2-hydroxy-γ-pyrone form was established for these metabolites based on the comparison of their experimental IR spectra with the DFT calculated ones, for both the corresponding 4-hydroxy-α-pyrone and 2-hydroxy-γ-pyrone forms. During antibacterial evaluation, compound 13 stood out as the most active of the series, showing a selective activity against the gram positive pathogenic methicillin-resistant S. aureus (MRSA, MIC = 6 μΜ), with a bacteriostatic effect.     

Diversity of five glutenin loci within durum wheat (Triticum turgidum L. ssp. durum (Desf.) Husn.) germplasm grown in Algeria

The HMW and B‐LMW glutenin subunits composition of 120 durum wheat germplasm grown in Algeria was examined using SDS‐PAGE. All together, 39 glutenin patterns were detected, including eight for HMW and 21 for B‐LMW glutenin subunits. Twenty‐six different alleles were identified for the five glutenin loci studied, that is, Glu‐A1 (3), Glu‐B1 (7), Glu‐A3 (5), Glu‐B3 (9) and Glu‐B2 (2). Two new alleles were found at Glu‐B3 locus: Glu‐B3new₁ encodes for five subunits (7 + 8 + 14 + 16 + 18) and Glu‐B3new₂ codes for five subunits (4 + 6* + 12 + 15 + 15*), of which subunit 15* with mobility between bands 15–16 was not described previously. At the Glu‐1 loci, the Glu‐A1c/Glu‐B1e allelic composition was predominant. For the B‐LMW glutenins, the most common allelic composition was Glu‐A3a/Glu‐B3a/Glu‐B2a. The collection analysed shows glutenin alleles and allele combinations related to high gluten strength. This information could be useful to select varieties with improved quality and also as a source of genes to develop new lines when breeding for quality.     

Metabolic response of Medicago sativa to severe nutrient imbalances and disturbances under field conditions

Our experiments were focused on the metabolic footprint of mineral‐nutrient availability under field conditions. While there are multiple factors potentially blurring such footprints, we hypothesized that physiological and metabolic adaptations of established plants are particularly important mechanisms under field conditions. To study respective differences between young and established plants and to study the impact of disturbances on the adaptive capacity of established plants, we analyzed Medicago sativa plants of different age from plots with marked differences in the levels of soil mineral nutrients established in a long‐term fertilization experiment. Gas chromatography–mass spectrometry was used to determine metabolite profiles of sink and source leaves of plants in an early state of development (“young plants”), just before the first harvest (“established plants”), and a short time after the second harvest (“regrowing plants”). Metabolite profiles from young plants were markedly responsive to soil mineral nutrients and resembled respective profiles from controlled conditions, demonstrating that overall variability of growth and sampling conditions had relatively little importance for the metabolite profiles recorded. In the case of established plants, however, we observed only little impact of availability of mineral nutrients on metabolite profiles. This low metabolic responsiveness of plants was partially lost after severe disturbances (removal of the plant shoot). Metabolite profiling, in summary, is able to detect a metabolic footprint of mineral‐nutrient availability in young plants under field conditions and may provide information about the ability of older plants to partially uncouple their metabolism from the environment. In addition, it is also possible to determine the impact of disturbances on this ability of the plant organism.