Gastrointestinal uptake of trace elements are changed during the course of a common human viral (Coxsackievirus B3) infection in mice.

Most infectious diseases are accompanied by a change in levels of several trace elements in the blood. However, it is not known whether changes in the gastrointestinal uptake of trace elements contribute to this event. Coxsackievirus B3 (CVB3), adapted to Balb/c mice, was used to study whether infection induces gene expression of metallothionein (MT1) and divalent-metal transporter 1 (DMT1) in the intestine and liver and hepcidin in the liver, as well as whether trace elements in these tissues are changed accordingly. Quantitative expression of CVB3, MT1, DMT1 and hepcidin was measured by real-time RT-PCR and six trace elements by ICP-MS on days 3, 6 and 9 of the infection. The copper/zinc (Cu/Zn) ratio in serum increased as a response to the infection. High concentrations of virus were found in the intestine and liver on day 3 and in the intestine on day 6. MT1 in the intestine and liver increased on days 3 and 6. The increase of MT1 in the liver correlated positively with Cu and Zn. Hepcidin in the liver showed a non-significant increase on days 3 and 6 of the infection, whereas DMT1 in the intestine decreased on day 9. Accordingly, iron (Fe) in the liver increased progressively during the disease, whereas in the intestine DMT1 was negatively correlated to Fe. Arsenic (As), cadmium (Cd) and mercury (Hg) were found to decrease to various degrees in the intestine, serum and liver. Thus, enteroviral infections, and possibly many other infections, may cause a change in the gastrointestinal uptake of both non-essential and essential trace elements.     

How nutritionally imbalanced is phloem sap for aphids?

Aphids harbour intracellular symbionts (Buchnera) that provide their host with amino acids present in low amounts in their diet, phloem sap. To find out the extent to which aphids depend on their symbionts for synthesis of individual essential amino acids, we have evaluated how well phloem sap amino acid composition matches the aphids' needs. Amino acid compositions of the ingested phloem sap were compared to amino acids in aphid body proteins and also to available information about optimal diet composition for other plant feeding insects. Phloem sap data from severed stylets of two aphid species, Rhopalosiphum padi (L.) (Homoptera: Aphididae) feeding on wheat, and Uroleucon sonchi (L.) (Homoptera: Aphididae) feeding on Sonchus oleraceus (L.), together with published information on phloem sap compositions from other plant species were used.Phloem sap has in general only around 20% essential amino acids, with a range from 15–48%. Aphid body proteins and optimal diets for two other plant feeding insects have around 50%. The phloem sap of early flowering S. oleraceus ingested by U. sonchi contained 48%, which seems to be exceptional. Aphids feeding on different plants appear to be very differently dependent on their symbionts for their overall essential amino acid synthesis, due to the large variation in proportion of essential amino acids in phloem sap from different plants.The profile of the essential amino acids in phloem sap from different plant species corresponds rather well to profiles of both aphid body proteins and optimal diets determined for plant feeding insects. However, methionine and leucine in phloem sap are in general low in these comparisons, suggesting a higher dependence on the symbiont for synthesis of these amino acids. Concentrations of several essential amino acids in phloem from different plant species seem to vary together, suggesting that levels of symbiont provisioning of different amino acids are adjusted in parallel.     

Crosslinks rather than strand breaks determine access to ancient DNA sequences from frozen sediments

Diagenesis was studied in DNA obtained from Siberian permafrost (permanently frozen soil) ranging from 10,000 to 400,000 years in age. Despite optimal preservation conditions, we found the sedimentary DNA to be severely modified by interstrand crosslinks; single- and double-stranded breaks; and freely exposed sugar, phosphate, and hydroxyl groups. Intriguingly, interstrand crosslinks were found to accumulate approximately 100 times faster than single-stranded breaks, suggesting that crosslinking rather than depurination is the primary limiting factor for ancient DNA amplification under frozen conditions. The results question the reliability of the commonly used models relying on depurination kinetics for predicting the long-term survival of DNA under permafrost conditions and suggest that new strategies for repair of ancient DNA must be considered if the yield of amplifiable DNA from permafrost sediments is to be significantly increased. Using the obtained rate constant for interstrand crosslinks the maximal survival time of amplifiable 120-bp fragments of bacterial 16S ribosomal DNA was estimated to be approximately 400,000 years. Additionally, a clear relationship was found between DNA damage and sample age, contradicting previously raised concerns about the possible leaching of free DNA molecules between permafrost layers.     

Rational recombinant XMRV antigen preparation and bead coupling for multiplex serology in a suspension array

Diagnosis of infectious diseases often requires demonstration of antibodies to the microbe (serology). A large set of antigens, covering viruses, bacteria, fungi and parasites may be needed. Recombinant proteins have a prime role in serological tests. Suspension arrays offer high throughput for simultaneous measurement of many different antibodies. We here describe a rational process for preparation, purification and coupling to beads of recombinant proteins prepared in Escherichia coli derivate Origami B, to be used in a serological Luminex suspension array. All six Gag and Env proteins (p10, p12, p15, p30, gp70 and p15E), from the xenotropic murine leukemia virus-related virus (XMRV), were prepared, allowing the creation of a multiepitope XMRV antibody assay. The procedure is generic and allows production of protein antigens ready for serological testing in a few working days. Instability and aggregation problems were circumvented by expression of viral proteins fused to a carrier protein (thioredoxin A; TrxA), purification via inclusion body formation, urea solubilization, His tag affinity chromatography and direct covalent coupling to microspheres without removal of the elution buffer. The yield of one preparation (2–10 mg fusion protein per 100 ml culture) was enough for 20–100 coupling reactions, sufficing for tests of many tens of thousands of sera. False serological positivity due to antibodies binding to TrxA and to traces of E. coli proteins remaining in the preparation could be reduced by preabsorption of sera with free TrxA and E. coli extract. The recombinant antigens were evaluated using anti-XMRV antibodies. Although hybrid proteins expressed in E. coli in this way will not have the entire tertiary structure and posttranslational modifications of the native proteins, they contain a large subset of the epitopes associated with them. The described strategy is simple, quick, efficient and cheap. It should be applicable for suspension array serology in general.     

Plant regeneration from seeds responds to phylogenetic relatedness and local adaptation in Mediterranean Romulea (Iridaceae) species

Seed germination is the most important transitional event between early stages in the life cycle of spermatophytes and understanding it is crucial to understand plant adaptation and evolution. However, so far seed germination of phylogenetically closely related species has been poorly investigated. To test the hypothises that phylogenetically related plant species have similar seed ecophysiological traits thereby reflecting certain habitat conditions as a result of local adaptation , we studied seed dormancy and germination in seven Mediterranean species in the genus Romulea (Iridaceae). Both the across‐species model and the model accounting for shared evolutionary history showed that cool temperatures (≤ 15°C) were the main factor that promoted seed germination. The absence of embryo growth before radicle emergence is consistent with a prompt germination response at cool temperatures. The range of temperature conditions for germination became wider after a period of warm stratification, denoting a weak primary dormancy. Altogether these results indicate that the studied species exhibit a Mediterranean germination syndrome, but with species‐specific germination requirements clustered in a way that follows the phylogenetic relatedness among those species. In addition, species with heavier seeds from humid habitats showed a wider range of conditions for germination at dispersal time than species from dry habitats possessing lighter seeds. We conclude that while phylogenetically related species showed very similar germination requirements, there are subtle ecologically meaningful differences, confirming the onset of adaptation to local ecological factors mediated by species relatedness.     

Ecosystem properties of semiarid savanna grassland in West Africa and its relationship with environmental variability

The Dahra field site in Senegal, West Africa, was established in 2002 to monitor ecosystem properties of semiarid savanna grassland and their responses to climatic and environmental change. This article describes the environment and the ecosystem properties of the site using a unique set of in situ data. The studied variables include hydroclimatic variables, species composition, albedo, normalized difference vegetation index (NDVI), hyperspectral characteristics (350–1800 nm), surface reflectance anisotropy, brightness temperature, fraction of absorbed photosynthetic active radiation (FAPAR), biomass, vegetation water content, and land‐atmosphere exchanges of carbon (NEE) and energy. The Dahra field site experiences a typical Sahelian climate and is covered by coexisting trees (~3% canopy cover) and grass species, characterizing large parts of the Sahel. This makes the site suitable for investigating relationships between ecosystem properties and hydroclimatic variables for semiarid savanna ecosystems of the region. There were strong interannual, seasonal and diurnal dynamics in NEE, with high values of ~?7.5 g C m^?2 day^?1 during the peak of the growing season. We found neither browning nor greening NDVI trends from 2002 to 2012. Interannual variation in species composition was strongly related to rainfall distribution. NDVI and FAPAR were strongly related to species composition, especially for years dominated by the species Zornia glochidiata. This influence was not observed in interannual variation in biomass and vegetation productivity, thus challenging dryland productivity models based on remote sensing. Surface reflectance anisotropy (350–1800 nm) at the peak of the growing season varied strongly depending on wavelength and viewing angle thereby having implications for the design of remotely sensed spectral vegetation indices covering different wavelength regions. The presented time series of in situ data have great potential for dryland dynamics studies, global climate change related research and evaluation and parameterization of remote sensing products and dynamic vegetation models.     

The evolution of pedipalps and glandular hairs as predatory devices in harvestmen (Arachnida,Opiliones)

Pedipalps are the most versatile appendages of arachnids. They can be equipped with spines (Amblypygi), chelae (Scorpiones), or adhesive pads (Solifugae), all of which are modifications to grasp and handle fast‐moving prey. Harvestmen (Opiliones) show a high diversity of pedipalpal morphologies. Some are obviously related to prey capture, like the enlargement and heavy spination of Laniatores pedipalps. Many Dyspnoi, by contrast, exhibit thin, thread‐like pedipalps that are covered with complex glandular setae (clavate setae). These extrude viscoelastic glue that is used to immobilize prey items. Comparable setae (plumose setae) have previously been found in representatives of both Eupnoi and Dyspnoi, yet comprehensive data on their distribution are lacking. This study examined the distribution and ultrastructure of glandular setae in harvestmen and related them to pedipalpal morphology. Pedipalpal and setal characters were analysed in a phylogenetic framework. We found that glandular setae are synapomorphic for and widespread in the Palpatores clade (Eupnoi plus Dyspnoi). Their occurrence correlates with pedipalp morphology and feeding habit. Remnants of arthropod cuticular structures or secretions, frequently found attached to glandular setae, and behavioural observations, underlined the importance of the setae for capturing and securing prey. We hypothesize that glandular setae evolved as an adaptation to capture small and agile prey, which are hard to catch with a capture basket. Details of ultrastructure indicate that the setae are derived sensilla chaetica, with both a secretory and sensory function. Derived ultrastructural characters of the glandular setae, such as slit‐like channel openings and a globular arrangement of the microtrichia, may increase their effectiveness. The functional role of further pedipalpal modifications, such as apophyses, stalked and hyperbendable joints, and curved segments, as well as sexual dimorphism and ontogenetic polymorphism, are discussed. Some implications of the results obtained for the taxonomic treatment of Phalangiidae are also discussed. These results shed new light on the biology and evolutionary history of this fascinating group of arthropods.