High‐throughput identification and quantification of Vagococcus salmoninarum by SYBR Green I‐based real‐time PCR combined with melting curve analysis

This work describes a primer pair and a high‐throughput SYBR Green I‐based real‐time PCR protocol combined with melting curve analysis for identification and quantification of Vagococcus salmoninarum in bacterial cultures and infected fish tissues. The 16S rRNA gene was selected for the design of the primer pair (SalF and SalR). The sensitivity and specificity of this primer pair were compared with other previously designed for conventional PCR. Although both primer pairs showed 100% specificity using pure bacterial cultures or DNA extracted from bacteria or fish tissues, the primer pairs designed in this study showed the highest sensitivity with a detection limit of 0.034 × 10⁰ amplicon copies per assay (equivalent to 2 × 10^?11 ng/µl, C_q value of 30.49 ± 1.71). The developed qPCR protocol allowed the detection of V. salmoninarum in non‐lethal and lethal fish samples with detection levels of 0.17 × 10⁰ gene copies in tissues artificially infected and 0.02 × 10⁰ in tissues of fish experimentally infected with V. salmoninarum. The high sensitivity of the developed method suggests that it could be considered as a useful tool for diagnosis of vagococcosis and the detection of V. salmoninarum in asymptomatic or carrier fish.     

Climate Change During the Last Deglaciation in Antarctica

Greenland ice core records provide clear evidence of rapid changes in climate in a variety of climate indicators. In this work, rapid climate change events in the Northern and Southern hemispheres are compared on the basis of an examination of changes in atmospheric circulation developed from two ice cores. High-resolution glaciochemical series, covering the period 10,000 to 16,000 years ago, from a central Greenland ice core and a new site in east Antarctica display similar variability. These findings suggest that rapid climate change events occur more frequently in Antarctica than previously demonstrated.     

INDEPTH Wide-Angle Reflection Observation of P-Wave-to-S-Wave Conversion from Crustal Bright Spots in Tibet

Three-component wide-angle seismic data acquired in southern Tibet during Project INDEPTH show strong P-to-S converted reflections from reflectors that are aligned at a depth of approximately 15 kilometers beneath the northern Yadong-Gulu rift. These converted reflections are locally higher in amplitude than the corresponding P-wave reflections. Modeling of reflection mode conversion as a function of incidence angle indicates that this condition obtains for a reflector that is a solid over fluid interface; it is not typical of a solid-solid interface. The likely candidates for a fluid trapped within the crystalline crust of southern Tibet are granitic magma and water (brine).     

Enhancement of reproductive performance in shrimp Litopenaeus vannamei (Boone, 1931) by supplementation of Ulva clathrata meal in maturation diet in two commercial hatcheries

The effect of supplementing dehydrated seaweed Ulva clathrata (20 g/kg) in the squid fraction of a formulated fresh diet on the reproductive performance of Litopenaeus vannamei broodstock was evaluated in two commercial hatcheries (A and B). The origin of broodstock, use of ablation on females, tank/culture conditions (for maturation, spawning, and larval rearing) were different between hatcheries. Daily mortality was higher (p < .01) for females in the control group compared to Ulva‐fed group of hatchery A, where females were ablated. No differences in mortality were found for unablated females in hatchery B, or with males from either hatchery. In hatchery A, broodstock fed Ulva produced more eggs (an increase in +5% compared to control, p < .05) and nauplii per female (+18%, p < .01). In hatchery B, broodstock fed Ulva produced significantly more eggs (+26%, p < .05) and nauplii per day (+33%, p < .05). In hatcheries A and B, eggs from broodstock fed Ulva had increased hatching rates (+13 and +7%, respectively, p < .001 in both cases). The number of spawns per day had a tendency to be higher in broodstock fed Ulva in both hatcheries, but the difference did not reach statistical significance (+14% for hatchery A and +20% for hatchery B). Dehydrated U. clathrata appears therefore as a functional additive in L. vannamei maturation diets that enhances the reproductive performance at commercial scale, regardless of the management conditions.     

Cultivar‐dependent yield reductions in white clover due to simulated grazing and White clover mosaic virus infection are associated with differences in storage reserves and antioxidant metabolism

White clover is considered amongst the most important forage legumes in temperate agricultural systems. It contributes to increased quality of pastures through its ability to fix atmospheric nitrogen, providing high nutritional feed for livestock. White clover is host to the potexvirus White clover mosaic virus (WClMV), which is readily transmitted via animal trampling/grazing and mowing. WClMV infection may strongly impact white clover's performance, affecting its ability to compete with other plants in the pasture. Understanding the extent to which the virus influences white clover's growth and yield may contribute to improve pastoral management by pointing out the importance of stress factors on pasture plant performance and herbage yield. In the current study, the effects of WClMV infection and simulated grazing on white clover's fitness, oxidative damage and the induction of antioxidants were investigated. Two cultivars of white clover, Grasslands Huia and Grasslands Kopu II, were subjected to three harvests. In response to WClMV infection and grazing‐like cutting, white clover experienced oxidative stress as evidenced by the accumulation of lipid peroxides and protein carbonyls. Biomass accumulation, given as fresh weight and dry matter content, was also negatively affected. Both stresses induced an increase in ascorbate and glutathione levels and enhanced the activity of superoxide dismutase, ascorbate peroxidase, glutathione peroxidase, catalase and glutathione reductase. Glutathione S‐transferase activity and the levels of reduced ascorbate and reduced glutathione were not affected by either stress.     

Soil organic matter in Northern Ethiopia,current level and predicted trend: a study case of two villages in Tigray

Soil degradation resulting from permanent and high pressure on natural resources is a threat for the present and future of agricultural production in Ethiopia. Mono‐cropping, cultivation on steep slopes, use of cattle manure and crop residues as an energy source for cooking are common practices that have led to declining soil organic matter (SOM) contents. The objective of this research was to evaluate the current status of SOM in farmlands and exclosures (areas protected from grazing to allow their natural restoration) in Northern Ethiopia and to explore the long‐term effects of current agricultural practices and an improved scenario on SOM. At present, the SOM content of farmland soils is small, ranging from 2.1% to 2.9%, while exclosures showed a significant recovery after 20 yr of protection, with SOM contents ranging from 2.6% to 5.6%. However, the level of SOM in farmland soils is envisaged to decline given current agricultural practices, that is removal of crop residues and use of manure as an energy source for cooking. We found that applying manure alone appeared to be insufficient to revert this trend, due to limited availability and its alternative uses. Therefore, a multidisciplinary approach including improved manure and compost management needs to be supplemented with energy saving techniques, as fuel use is currently the largest competing claim for organic matter in the area.     

Splenic lymphoma in a short-beaked echidna (Tachyglossus aculeatus)

A 23-year-old, male short-beaked echidna ( Tachyglossus aculeatus ) housed at a North American zoo was successfully treated for flea-associated anaemia, but subsequently died. Cause of death was presumptive septicaemia secondary to splenic lymphoma. This is only the fifth case of neoplasia reported in this monotreme species, and the first from outside of Australia.