Response to ‘The European nitrogen cycle: response to Schulze et al,Global Change Biology (2010) 16, pp. 1451–1469’

Winniwarter and colleagues present alternative estimates for several of the nitrogen (N) fluxes provided by Schulze and colleagues. They reason that numeric discrepancies between largely dependent estimates and lack of detail in Schulze's estimates urges caution in interpreting these numbers. In this reply we provide methodological details enhancing the transparency of Schulze's estimates and argue that convergence between land‐ and atmosphere‐based estimates should be reached before individual estimates can be rejected. Only for the nitrous oxide and NO_x fluxes a balance between atmosphere and land‐based estimates has been reached. Convergence between independent estimates has not been reached yet for NO‐, NH₃‐ and N‐deposition estimates. As stated by Schulze and colleagues these N‐fluxes remain potentially biased and therefore come with a large uncertainty, irrespective of the reported precision.     

Phylogenetic analysis of genera of ‘Akanthophoreinae’ (Crustacea: Tanaidacea)

Phylogenetic relations among tanaidacean genera within ‘Akanthophoreinae’ are addressed using computer-assisted parsimony methods. The morphology-based analysis includes 10 well-defined and described genera: Araphura, Chauliopleona, Collettea, Paragathotanais, Metagathotanais, Paraleptognathia, Paranarthrura, Portaratrum, and Tanaella in Tanaidomorpha, and Glabroapseudes in Apseudomorpha as the outgroup. Chauliopleona and Paraleptognathia form a monophylum; Portaratrum cannot be placed in any known family. These three genera are considered as incertae sedis. The analysis does not support the monophyly of ‘Akanthophoreinae’, and further questions the monophyly of Tanaellidae.     

The European nitrogen cycle: commentary on Schulze et al., Global Change Biology (2010) 16, pp. 1451–1469

This paper compares data on N fluxes compiled by Schulze and colleagues, with information available in the literature and publicly available open databases, and finds important discrepancies for a number of such fluxes for Europe (emissions, deposition, aerosol formation of compounds containing N) – exceeding a factor of two in several cases. A qualitative assessment of the uncertainties of the respective approaches indicates that these differences are beyond the uncertainty margins that can be reasonably attributed to the respective data. We conclude that the results should be used with caution, that agricultural application of N should still be considered to be the largest source of N released to the environment, and that this agricultural N affects soils more strongly than atmospheric deposition, at the European scale.     

Multilocus sequence analysis (MLSA) of ‘Rickettsiella costelytrae' and ‘Rickettsiella pyronotae’, intracellular bacterial entomopathogens from New Zealand

Aims

Larvae of scarab beetles live in the soil and are frequently hosts for microbial pathogens. In New Zealand, larvae of the grass grub, Costelytrae zealandica (Coleoptera: Scarabaeidae), and manuka beetles, Pyronota spp. (Coleoptera: Scarabaeidae), have been collected from field populations showing loss of vigour and a whitened appearance. Diagnosis indicated an intracellular infection of fat body tissues by Rickettsiella‐like micro‐organisms. Rickettsiella bacteria are under evaluation as a possible new source of insect bio‐control agents for important agricultural pests as, e.g. scarabaeid and elaterid larvae. The present study aimed at the unequivocal molecular taxonomic identification and comparison of the bacteria associated with Costelytra and Pyronota.

Methods and Results

Electron microscopy and phylogenetic reconstruction using a multilocus sequence analysis approach based on the 16S ribosomal RNA gene together with four protein‐encoding markers (ftsY, gidA, rpsA, and sucB) demonstrated that both bacteria from New Zealand are phylogenetically closely related, but not identical, and belong to the taxonomic genus Rickettsiella.

Conclusions

The bacteria under study should be referred to as pathotypes ‘Rickettsiella costelytrae’ and ‘Rickettsiella pyronotae’, respectively. Moreover, on the basis of the currently accepted systematic organization of the genus Rickettsiella, both pathotypes should be considered synonyms of the nomenclatural type species, Rickettsiella popilliae.

Significance and Impact of the Study

The study demonstrates that Rickettsiella bacteria are geographically widespread pathogens of scarabaeid larvae. Implications of the phylogenetic findings presented for the stability of host adaptation by Rickettsiella bacteria are critically discussed.     

Comment to Shinohara et al. (1991) FEBS Letters 293, 173-174. The uncoupling protein is not expressed in rat liver.

Using Northern blot analysis, immunoblotting with purified antibodies and Polymerase Chain Reaction analysis, we were unable to detect the Uncoupling Protein-UCP or its mRNA in liver of control, cold-exposed or newborn rats. The unique expression of this protein in brown adipocytes was confirmed. These data refute the surprising recent report on UCP expression in rat liver (Shinohara (1991) FEBS Lett. 293, 173-174). Moreover we report that the hybridization signal obtained by these authors is probably non-specific and due to the 3' non-coding domain of the UCP cDNA probe.     

Ultrastructure of the Flame Bulbs of Urastoma cyprinae (Platyhelminthes, ‘Prolecithophora’, Urastomidae)

The ultrastructure of the flame bulbs of the turbellarian Urastoma cyprinae from Mytilus galloprovincialis in the Mediterranean is described. The nucleus of the terminal cell is located some distance basal to the rootlets of the cilia forming the flame; the cytoplasm contains numerous tubules approximately 54–66 nm in diameter, and vesicles. Thick walled, densely packed rod-like structures coil around each other with a tendency towards longitudinal orientation close to the flame. The rod-like structures tightly surround the basal part of the flame and the distal cytoplasmic tube in the apical part of the flame. Some of them, including the inner predominantly longitudinally directed ones, are continuous with the cytoplasm of the terminal cell, others are continuous with the cytoplasm of the distal cytoplasmic tube. Internal leptotriches arise from the cytoplasm of the terminal cell and intrude between the basal parts of the cilia of the flame. The distal cytoplasmic tube possesses a septate junction. The flame bulb of Urastoma differs distinctly from those known from other Platyhelminthes; implications for the phylogeny of Platyhelminthes are discussed.     

Structure of sperm,spermatozeugmata and ‘lateral organs’ in the bivalve Arthritica (Galeommatoidea: Leptonidae)

The position and structure of paired ‘lateral organs’ in the foot of Arthritica semen and Arthritica bifurca might indicate a chemosensory function. In both species part of the organ is also glandular. In A. semen the glandular epithelium is detached piecemeal and, probably by means of the foot, is moved to and grafted upon the gills of the same individual. The transferred epithelia appear as disk‐shaped actively secretory ‘gill bodies’ which, attached to the abfrontal side of the inner demibranch, replace the ordinary unciliated gill epithelium. The secretion is liberated into the suprabranchial chamber, which serves as a marsupium, but its function is uncertain. Arthritica semen is a protandric hermaphrodite and produces very large ova that undergo a direct development that results in a non‐planktonic lecithotrophic crawling juvenile stage. The sperm cells have filiform nuclei that are straight in the euspermatozoa and more or less helicoidal in what is considered to represent paraspermatozoa. By a process of aggregation, spermatozeugmata are formed which consist exclusively either of euspermatozoa or paraspermatozoa. Spermatozoa are stored in the oviduct in A. semen but in paired seminal receptacles in A. bifurca.