Carbon uptake in Eurasian boreal forests dominates the high-latitude net ecosystem carbon budget

Arctic-boreal landscapes are experiencing profound warming, along with changes in ecosystem moisture status and disturbance from fire. This region is of global importance in terms of carbon feedbacks to climate, yet the sign (sink or source) and magnitude of the Arctic-boreal carbon budget within recent years remains highly uncertain. Here, we provide new estimates of recent (2003–2015) vegetation gross primary productivity (GPP), ecosystem respiration (R_eco), net ecosystem CO₂ exchange (NEE; R_eco − GPP), and terrestrial methane (CH₄) emissions for the Arctic-boreal zone using a satellite data-driven process-model for northern ecosystems (TCFM-Arctic), calibrated and evaluated using measurements from >60 tower eddy covariance (EC) sites. We used TCFM-Arctic to obtain daily 1-km² flux estimates and annual carbon budgets for the pan-Arctic-boreal region. Across the domain, the model indicated an overall average NEE sink of −850 Tg CO₂-C year⁻¹. Eurasian boreal zones, especially those in Siberia, contributed to a majority of the net sink. In contrast, the tundra biome was relatively carbon neutral (ranging from small sink to source). Regional CH₄ emissions from tundra and boreal wetlands (not accounting for aquatic CH₄) were estimated at 35 Tg CH₄-C year⁻¹. Accounting for additional emissions from open water aquatic bodies and from fire, using available estimates from the literature, reduced the total regional NEE sink by 21% and shifted many far northern tundra landscapes, and some boreal forests, to a net carbon source. This assessment, based on in situ observations and models, improves our understanding of the high-latitude carbon status and also indicates a continued need for integrated site-to-regional assessments to monitor the vulnerability of these ecosystems to climate change.     

Comparative Analysis of Genetic Chemotyping Methods for Fusarium: Tri13 Polymorphism Does not Discriminate between 3‐ and 15‐acetylated Deoxynivalenol Chemotypes in Fusarium graminearum

Genetic chemotyping is an essential tool for characterizing Fusarium populations causing head blight on wheat and other cereals. Three PCR methods, based on tri cluster polymorphism, were optimized and compared on 94 single‐spore isolates obtained from three continents belonging to F. gramineaurm, F. culmorum, F. poae, F. avenaceum and Microdochium nivale. While the methods based on the tri3, tri7 and tri12 polymorphism correctly identified all the tested strains, the method based on tri13 polymorphism was unable to discriminate between the 3‐ and 15‐acetylated DON forms in F. graminearum. It is advised to avoid the use of tri13 polymorphism for genetic chemotyping of the two acetylated chemotypes.     

Skeletal development in the Chinese soft‐shelled turtle Pelodiscus sinensis (Testudines: Trionychidae)

We investigated the development of the whole skeleton of the soft‐shelled turtle Pelodiscus sinensis, with particular emphasis on the pattern and sequence of ossification. Ossification starts at late Tokita‐Kuratani stage (TK) 18 with the maxilla, followed by the dentary and prefrontal. The quadrate is the first endoskeletal ossification and appears at TK stage 22. All adult skull elements have started ossification by TK stage 25. Plastral bones are the first postcranial bones to ossify, whereas the nuchal is the first carapacial bone to ossify, appearing as two unstained anlagen. Extensive examination of ossification sequences among autopodial elements reveals much intraspecific variation. Patterns of ossification of cranial dermal elements are more variable than those of endochondral elements, and dermal elements ossify before endochondral ones. Differences in ossification sequences with Apalone spinifera include: in Pelodiscus sinensis the jugal develops relatively early and before the frontal, whereas it appears later in A. spinifera; the frontal appears shortly before the parietal in A. spinifera whereas in P. sinensis the parietal appears several stages before the frontal. Chelydrids exhibit an early development of the postorbital bone and the palatal elements as compared to trionychids. Integration of the onset of ossification data into an analysis of the sequence of skeletal ossification in cryptodirans using the event‐pairing and Parsimov methods reveals heterochronies, some of which reflect the hypothesized phylogeny considered taxa. A functional interpretation of heterochronies is speculative. In the chondrocranium there is no contact between the nasal capsules and planum supraseptale via the sphenethmoid commissurae. The pattern of chondrification of forelimb and hind limb elements is consistent with a primary axis and digital arch. There is no evidence of anterior condensations distal to the radius and tibia. A pattern of quasi‐ simultaneity is seen in the chondrogenesis of the forelimb and the hind limb. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.     

Quinidine,but Not Eicosanoid Antagonists or Dexamethasone,Protect the Gut from Platelet Activating Factor-Induced Vasoconstriction,Edema and Paralysis

Intestinal circulatory disturbances, atony, edema and swelling are of great clinical relevance, but the related mechanisms and possible therapeutic options are poorly characterized, in part because of the difficulties to comprehensively analyze these conditions. To overcome these limitations we have developed a model of the isolated perfused rat small intestine where all of these symptoms can be studied simultaneously. Here we used this model to study the role of eicosanoids, steroids and quinidine in platelet-activating factor (PAF)-induced intestinal disorders. A vascular bolus of PAF (0.5 nmol) triggered release of thromboxane and peptidoleukotrienes into the vascular bed (peak concentration 35 nM and 0.8 nM) and reproduced all symptoms of intestinal failure: mesenteric vasoconstriction, translocation of fluid and macromolecules from the vasculature to the lumen and lymphatics, intestinal edema formation, loss of intestinal peristalsis and decreased galactose uptake. All effects of PAF were abolished by the PAF-receptor antagonist ABT491 (2.5 μM). The COX and LOX inhibitors ASA and AA861 (500 μM, 10 μM) did not exhibit barrier-protective effects and the eicosanoid antagonists SQ29548 and MK571 (10 μM, each) only moderately attenuated the loss of vascular fluid, the redistribution to the lumen and the transfer of FITC dextran to the lumen. The steroid dexamethasone (10 μM) showed no barrier-protective properties and failed to prevent edema formation. Quinidine (100 μM) inhibited the increase in arterial pressure, stabilized all the intestinal barriers, and reduced lymph production and the transfer of FITC dextran to the lymph. While quinidine by itself reduced peristalsis, it also obviated paralysis, preserved intestinal functions and prevented edema formation. We conclude that quinidine exerts multiple protective effects against vasoconstriction, edema formation and paralysis in the intestine. The therapeutic use of quinidine for intestinal ailments deserves further study.     

Local chromatin microenvironment determines DNMT activity: from DNA methyltransferase to DNA demethylase or DNA dehydroxymethylase

Insights on active DNA demethylation disproved the original assumption that DNA methylation is a stable epigenetic modification. Interestingly, mammalian DNA methyltransferases 3A and 3B (DNMT-3A and -3B) have also been reported to induce active DNA demethylation, in addition to their well-known function in catalyzing methylation. In situations of extremely low levels of S-adenosyl methionine (SAM), DNMT-3A and -3B might demethylate C-5 methyl cytosine (5mC) via deamination to thymine, which is subsequently replaced by an unmodified cytosine through the base excision repair (BER) pathway. Alternatively, 5mC when converted to 5- hydroxymethylcytosine (5hmC) by TET enzymes, might be further modified to an unmodified cytosine by DNMT-3A and -3B under oxidized redox conditions, although exact pathways are yet to be elucidated. Interestingly, even direct conversion of 5mC to cytosine might be catalyzed by DNMTs. Here, we summarize the evidence on the DNA dehydroxymethylase and demethylase activity of DNMT-3A and -3B. Although physiological relevance needs to be demonstrated, the current indications on the 5mC- and 5hmC-modifying activities of de novo DNA C-5 methyltransferases shed a new light on these enzymes. Despite the extreme circumstances required for such unexpected reactions to occur, we here put forward that the chromatin microenvironment can be locally exposed to extreme conditions, and hypothesize that such waves of extremes allow enzymes to act in differential ways.     

Proteome and radioimmunoassay analyses of pituitary hormones and proteins in response to feed restriction of dairy cows

The hypothalamic-pituitary system controls homeostasis during feed energy reduction. In order to examine which pituitary proteins and hormone variants are potentially associated with metabolic adaptation, pituitary glands from ad libitum and energy restrictively fed dairy cows were characterized using RIA and 2-DE followed by MALDI-TOF-MS. We found 64 different spots of regulatory hormones: growth hormone (44), preprolactin (16), luteinizing hormone (LH) (1), thyrotropin (1), proopiomelanocortin (1) and its cleavage product lipotropin (1), but none of these did significantly differ between feeding groups. Quantification of total pituitary LH and prolactin concentrations by RIA confirmed the results obtained by proteome analysis. Also, feed energy restriction provoked increasing non-esterified fatty acid, decreasing prolactin, but unaltered glucose, LH and growth hormone plasma concentrations. Energy restriction decreased the expression of glial fibrillary acidic protein, triosephosphate isomerase, purine-rich element-binding protein A and elongation factor Tu, whereas it increased expression of proline synthetase co-transcribed homolog, peroxiredoxin III, β-tubulin and annexin A5 which is involved in the hormone secretion process. Our results indicate that in response to feed energy restriction the pituitary reservoir of all posttranslationally modified hormone forms remains constant. Changing plasma hormone concentrations are likely attributed to a regulated releasing process from the gland into the blood.     

Macronutrient balancing in free‐ranging populations of moose

At northern latitudes, large spatial and temporal variation in the nutritional composition of available foods poses challenges to wild herbivores trying to satisfy their nutrient requirements. Studies conducted in mostly captive settings have shown that animals from a variety of taxonomic groups deal with this challenge by adjusting the amounts and proportions of available food combinations to achieve a target nutrient balance. In this study, we used proportions‐based nutritional geometry to analyze the nutritional composition of rumen samples collected in winter from 481 moose (Alces alces) in southern Sweden and examine whether free‐ranging moose show comparable patterns of nutrient balancing. Our main hypothesis was that wild moose actively regulate their rumen nutrient composition to offset ecologically imposed variation in the nutritional composition of available foods. To test this, we assessed the macronutritional composition (protein, carbohydrates, and lipids) of rumen contents and commonly eaten foods, including supplementary feed, across populations with contrasting winter diets, spanning an area of approximately 10,000 km². Our results suggest that moose balanced the macronutrient composition of their rumen, with the rumen contents having consistently similar proportional relationship between protein and nonstructural carbohydrates, despite differences in available (and eaten) foods. Furthermore, we found that rumen macronutrient balance was tightly related to ingested levels of dietary fiber (cellulose and hemicellulose), such that the greater the fiber content, the less protein was present in the rumen compared with nonstructural carbohydrates. Our results also suggest that moose benefit from access to a greater variety of trees, shrubs, herbs, and grasses, which provides them with a larger nutritional space to maneuver within. Our findings provide novel theoretical insights into a model species for ungulate nutritional ecology, while also generating data of direct relevance to wildlife and forest management, such as silvicultural or supplementary feeding practices.     

Molecular systematics and morphological character evolution of the Condamineeae (Rubiaceae)

? Premise of the study: The Condamineeae have in previous molecular studies been shown to be part of an early-divergent clade within the subfamily Ixoroideae, together with the tribes Calycophylleae, and Hippotideae, and genera of the former Cinchoneae and Rondeletieae. Generic relationships within this clade have, however, remained largely unresolved. ? Methods: In this study, the systematics of the Condamineeae was further examined by phylogenetic reconstruction of six cpDNA regions and one nrDNA region using parsimony and Bayesian Markov chain Monte Carlo inference. Morphological character evolution within the tribe was assessed by ancestral state reconstruction using likelihood optimization of characters onto Bayesian trees. ? Key results: Calycophylleae appears polyphyletic. "Hippotideae" is monophyletic but nested within the Condamineeae. The phylogenetic hypotheses presented support a resurrection of the genera Holtonia, Schizocalyx, and Semaphyllanthe. Furthermore, Bathysa is found to be polyphyletic, Tresanthera is found nested within Rustia, and the taxonomically disputed genus Dialypetalanthus is here shown to be sister to a Bothriospora-Wittmackanthus clade. Morphological ancestral state reconstructions indicate that protogyny have evolved at least two times within the tribe and that indehiscent fruits, loculicidal fruit dehiscence, and intrapetiolar stipules have evolved independently several times. The occurrence of calycophylls (leaf-like calyx lobes), poricidal anthers, and winged seeds also appear homoplastic within the tribe. ? Conclusions: A diagnosis and delimitation of the tribe Condamineeae is presented, with taxonomic proposals to synonymize Tresanthera and to transfer several species of Bathysa as well as Phitopis to a resurrected Schizocalyx.     

Two different lantibiotic-like peptides originate from the ericin gene cluster of Bacillus subtilis A1/3

A lantibiotic gene cluster was identified in Bacillus subtilis A1/3 showing a high degree of homology to the subtilin gene cluster and occupying the same genetic locus as the spa genes in B. subtilis ATCC 6633. The gene cluster exhibits diversity with respect to duplication of two subtilin-like genes which are separated by a sequence similar to a portion of a lanC gene. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analyses of B. subtilis A1/3 culture extracts confirmed the presence of two lantibiotic-like peptides, ericin S (3,442 Da) and ericin A (2,986 Da). Disruption of the lanB-homologous gene eriB resulted in loss of production of both peptides, demonstrating that they are processed in an eriB-dependent manner. Although precursors of ericins S and A show only 75% of identity, the matured lantibiotic-like peptides reveal highly similar physical properties; separation was only achieved after multistep, reversed-phase high-performance liquid chromatography. Based on Edman and peptidase degradation in combination with MALDI-TOF MS, for ericin S a subtilin-like, lanthionine-bridging pattern is supposed. For ericin A two C-terminal rings are different from the lanthionine pattern of subtilin. Due to only four amino acid exchanges, ericin S and subtilin revealed similar antibiotic activities as well as similar properties in response to heat and protease treatment. For ericin A only minor antibiotic activity was found.     

Proteome dynamics during plastid differentiation in rice

We have analyzed proteome dynamics during light-induced development of rice (Oryza sativa) chloroplasts from etioplasts using quantitative two-dimensional gel electrophoresis and tandem mass spectrometry protein identification. In the dark, the etioplast allocates the main proportion of total protein mass to carbohydrate and amino acid metabolism and a surprisingly high number of proteins to the regulation and expression of plastid genes. Chaperones, proteins for photosynthetic energy metabolism, and enzymes of the tetrapyrrole pathway were identified among the most abundant etioplast proteins. The detection of 13 N-terminal acetylated peptides allowed us to map the exact localization of the transit peptide cleavage site, demonstrating good agreement with the prediction for most proteins. Based on the quantitative etioplast proteome map, we examined early light-induced changes during chloroplast development. The transition from heterotrophic metabolism to photosynthesis-supported autotrophic metabolism was already detectable 2 h after illumination and affected most essential metabolic modules. Enzymes in carbohydrate metabolism, photosynthesis, and gene expression were up-regulated, whereas enzymes in amino acid and fatty acid metabolism were significantly decreased in relative abundance. Enzymes involved in nucleotide metabolism, tetrapyrrole biosynthesis, and redox regulation remained unchanged. Phosphoprotein-specific staining at different time points during chloroplast development revealed light-induced phosphorylation of a nuclear-encoded plastid RNA-binding protein, consistent with changes in plastid RNA metabolism. Quantitative information about all identified proteins and their regulation by light is available in plprot, the plastid proteome database (http://www.plprot.ethz.ch).