A bacterial protein targets the BAHD1 chromatin complex to stimulate type III interferon response

Intracellular pathogens such as Listeria monocytogenes subvert cellular functions through the interaction of bacterial effectors with host components. Here we found that a secreted listerial virulence factor, LntA, could target the chromatin repressor BAHD1 in the host cell nucleus to activate interferon (IFN)-stimulated genes (ISGs). IFN-λ expression was induced in response to infection of epithelial cells with bacteria lacking LntA; however, the BAHD1-chromatin associated complex repressed downstream ISGs. In contrast, in cells infected with lntA-expressing bacteria, LntA prevented BAHD1 recruitment to ISGs and stimulated their expression. Murine listeriosis decreased in BAHD1(+/-) mice or when lntA was constitutively expressed. Thus, the LntA-BAHD1 interplay may modulate IFN-λ-mediated immune response to control bacterial colonization of the host.     

The wetland plant and macroinvertebrate assemblages of temporary ponds in England and Wales

The biodiversity value of Northern European temporary ponds has been little recognised, and there are many gaps in our understanding of their ecology. This study investigated the wetland (including aquatic) plant and macroinvertebrate assemblages, and the physico-chemical characteristics of 71 temporary ponds in semi-natural habitats. Temporary ponds supported on average 17 (SD ± 8) wetland plant and 25 (SD ± 10) macroinvertebrate species. Over 75% of temporary ponds supported at least one uncommon (local, nationally scarce or Red Data Book) species. The number of uncommon wetland plant species and total number of macroinvertebrate species were both positively correlated with the total number of wetland plant species (richness), but there was no correlation between the number of uncommon and common macroinvertebrate species. Almost three-quarters of temporary ponds supported at least one nationally scarce macroinvertebrate and 8% supported at least one nationally scarce plant across a wide range of physico-chemical characteristics. The main environmental factor influencing the composition of temporary pond communities was water chemistry, particularly pH and alkalinity. The occurrence of facultative as well as obligate temporary pond species suggested that this habitat may play an important role in the interchange of species between waterbodies at the landscape scale.     

Comparative biodiversity of rivers, streams, ditches and ponds in an agricultural landscape in Southern England

Information about the relative biodiversity value of different waterbody types is a vital pre-requisite for many strategic conservation goals. In practice, however, exceptionally few inter-waterbody comparisons have been made. The current study compared river, stream, ditch and pond biodiversity within an 80 km² area of lowland British countryside. The results showed that although all waterbody types contributed to the diversity of macrophytes and macroinvertebrates in the region, they differed in relative value. Individual river sites were rich but relatively uniform in their species composition. Individual ponds varied considerably in species richness, with the richest sites supporting similar numbers of taxa to the best river sections, but the poorest sites amongst the most impoverished for all waterbody types. At a regional level, however, ponds contributed most to biodiversity, supporting considerably more species, more unique species and more scarce species than other waterbody types. Streams typically supported fewer species and fewer unique species at local and regional level than either ponds or rivers. Ditches (most of which were seasonal) were the least species-rich habitat, but supported uncommon species, including temporary water invertebrates not recorded in other waterbody types. Multivariate analysis indicated that permanence, depth, flow and altitude were the main environmental variables explaining invertebrate and plant assemblage composition. The findings, as a whole, suggest that ponds and other small waterbodies can contribute significantly to regional biodiversity. This contrasts markedly with their relative status in national monitoring and protection strategies, where small waterbodies are largely ignored.     

Monitoring nitrogen forms in soil/plant systems under different fertilizer managements. A preliminary investigation

A field experiment was carried out on maize (Zea mays, L.) to study the effects of different fertilizer management on nitrogen status in soil and plant response. Three different fertilizers, mineral (MN), mineral plus buffalo manure (MN + BM) and organo-mineral with peat (OMP), were added at the usual (140, 61 and 116 kg ha⁻¹) and the reduced (70, 31 and 58 kg ha⁻¹) rates of N, P and K. respectively. Soil samples were analyzed for N by both the Kjeldahl method and the electro-ultrafiltration technique (EUF). The soil Kjeldahl-N concentrations were scarcely affected by the different fertilizer treatments, while the EUF-N concentrations were closely correlated with the amounts of N added. The EUF also discriminated between the NO₃-N and the sum of the ammonium and the easily extractable organic N forms (EUF-N_org + NH₄). The largest proportions of EUF-Norg + NH₄ were found in the untreated plots and in the plots treated with buffalo manure. The different fertilizer treatments significantly affected grain yield, which ranged from a minimum of 6.3 t ha⁻¹ from the untreated plots, to a maximum of 11.9 t ha⁻¹ from those supplied with 140 kg N, 61 kg P and 116 kg K ha⁻¹ by OMP fertilizer. The highest agronomic efficiency index for N was exhibited in the OMP treatment at the reduced rate. The grain yield was closely correlated with the total extractable EUF-N, but different relationships were found between the rate of N added, the level of EUF-NO,-N in soil and grain yield for the different fertilizer treatments.     

Sulphur fertilization may improve the nutritional value of Brassica rapa L. subsp. sylvestris

Sulphur is essential in the biosynthesis of secondary metabolites with high nutritional value that typically accumulate in brassica species. Among these, glucosinolates are the most representative. The level of glucosinolates in these plants is highly dependent on genetic factors as well as environmental determinants, such as the available soil sulphur content. There is an increasing need of defining the metabolic profile of brassica species in response to both cultivation practices and environmental factors since a targeted modification of its constituents may significantly affect the functional properties and the commercial value of these vegetables. Here, we report on the effects of sulphur fertilization on flavonols, phenolic acids and glucosinolates contents of two friariello (Brassica rapa L. subsp. sylvestris L. Janch. var. esculenta Hort.) ecotypes—Lingua di Cane and Sorrentino. Friariello quality in terms of sprouts plus inflorescence nitrate and chlorophyll contents was also assessed. We found a significantly higher flavonols content in the ecotype Sorrentino, whereas its glucosinolates level was relatively smaller compared to Lingua di Cane. Sulphur fertilization significantly improved the antioxidant activity of both ecotypes and was associated with a genotype-dependent significant reduction of leaf nitrate content.     

Can salt stress-induced physiological responses protect tomato crops from ozone damages in Mediterranean environments?

The main route for ozone entry in plants is through the stomata. Consequently, environmental factors that may expose plants to any stress that will eventually lead to stomatal closure, will also reduce the rate of ozone entry into the plant and will possibly counteract ozone damages. In addition, several abiotic stresses activate the synthesis of antioxidant compounds, which are responsible for neutralizing toxic ozone derivatives. Due to this complex response, it is critical to assess how abiotic stresses and ozone toxicity will interactively affect plant growth and yield, especially in those areas, such as the coastal Mediterranean regions, where these types of stress and ozone exposure typically coexist. In this research we exposed tomato plants to salt stress in presence and absence of ozone to assess how salinity and ozone may interfere in terms of physiological responses and final yield. Plants grown in absence of ozone had a greater total biomass and higher yield compared to those grown in presence of ozone. Nevertheless these differences disappeared upon salinization. The reduced ozone damage in saline environment must be interpreted on relative terms, however, since salinity by itself caused a general inhibition of plant growth and yield. Based on these results, it was concluded that defining environment-specific ozone toxicity thresholds is necessary for developing reliable prediction models and/or assessing environmental safeguard levels.     

Characterisation of Erianthus sect. Ripidium and Saccharum germplasm (Andropogoneae - Saccharinae) using RFLP markers

A collection of 65 Erianthus Michx. sect. Ripidium Henrard accessions (representing seven accepted species) and 14 Saccharum L. representatives (S. officinarum L. and S. spontaneum L.) were studied by RFLP analysis using 14 dispersed nuclear single-copy probes from maize. An intergeneric distance (1–F) of 0.748 was revealed between Erianthus and Saccharum. Within the Erianthus collection, the greatest distances were found between E. elephantinus Hook f. or E. ravennae (L.) P. Beauv. (the two 2n=20 species), and the rest of the Erianthus collection. The smallest distances were found amongst the E. arundinaceus (Retz.) Jeswiet clones collected in Indonesia ((1–F)=0.005). In addition, a partition based on the geographical origin and consistent with the chromosome numbers, ie E. arundinaceus from Indonesia versus E. arundinaceus and E. procerus from India, was revealed. E. bengalense was intermediate. The study of the Saccharum individuals confirmed the greater variability of S. spontaneum compared to the so called noble cane, S. officinarum. The 2n=80 S. spontaneum genotypes were shown to be closely related to S. officinarum. The implication of these results on the involvement of S. spontaneum and Erianthus sect. Ripidium in the origin of S. officinarum is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Carbon and nitrogen mobilization in Larix x eurolepis leafy stem cuttings assessed by dual (13)C and (15)N labeling: relationships with rooting

Changes in use of both stored and newly synthesized sources of carbon (C) and nitrogen (N) were investigated during rooting of leafy cuttings of Larix x eurolepis A. Henry. We used dual (13)C and (15)N long-term labeling of reserves of stock plants and followed isotope dilution of the labels in the cuttings to determine the respective proportions of C and N derived from stock plant reserves (Q(C,old), Q(N,old)) and from newly synthesized sources (Q(C,new), Q(N,new)). We also assessed their partitioning into the growing needles and roots. Because rooting development occurred over several months, destructive harvests were made during three periods (t(0): April 9; t(1): May 15 to June 5; t(2): June 12 to June 26). Total C content (Q(C)) of cuttings did not change with time, whereas total N content (Q(N)) decreased significantly between t(0) and t(2). In rooted cuttings, unlike unrooted cuttings, total N concentration decreased less markedly in needles and in the lower stem component between t(1) and t(2) than between t(0) and t(2). The lower stem of rooted cuttings contained more Q(N,old) than that of unrooted cuttings and showed lower C:N and (13)C:(15)N ratios. The increase in Q(N,new) in the lower stem was positively correlated with rooting status. At t(1), new roots appeared and grew mainly at the expense of Q(C,new) and Q(N,old). By t(2), root growth was mainly dependent on new assimilates. We conclude that in leafy cuttings the initial amount of N reserves, rather than C reserves, may constitute a limiting factor for rooting.     

Extended surveillance for CBPP in a free country: Challenges and solutions regarding the potential caprine reservoir

Contagious bovine pleuropneumonia (CBPP) is a severe respiratory disease of cattle and buffalo caused by Mycoplasma mycoides subsp. mycoides "Small Colony" (MmmSC). The agent of CBPP has been isolated from goats in different countries including CBPP-free areas. Goats can therefore be regarded as a putative MmmSC reservoir. No diagnostic test for CBPP surveillance in goats has been proposed as yet. Furthermore, serological tests could be seriously hampered by a widespread caprine infection due to the subspecies M. mycoides subsp. capri (Mmc), which is antigenically very close to MmmSC and displays high levels of genetic variability. A competition ELISA (cELISA) is currently used to screen for CBPP in cattle at the herd level in infected areas. The aim of this study was to see if the same cELISA would be specific enough to be used to screen goats despite the potential concomitant infection with Mmc. The cELISA titers of goats from Mmc-infected and non-infected herds were comparable and negative using the accepted cutoff for bovine sera. In contrast, seroconversion was observed in goats experimentally inoculated with an Mmc strain that cross-reacted with a monoclonal antibody targeting the same epitope as that used in cELISA. The probability of such false positivity occurring under field conditions is very low since Mmc strains with such an atypical antigenic profile emerge only rarely as a result of random nucleotide variation of the epitope-coding region. In conclusion, the commercially available cELISA can be considered specific enough to be used as a primary test to monitor passage of the CBPP agent in goats, but its sensitivity in goats requires further investigation.