Prevalence of antibodies to Coxiella burnetii (Q fever) in bulk tank milk in England and Wales.

In the United Kingdom, the infection of people with Coxiella burnetii, the causative agent of Q fever, is of significant public health importance and is associated with contact with dairy cattle. An ELISA was developed for the detection of IgG antibodies against C burnetii in bulk tank milk, and in a survey of randomly selected samples from dairy herds in England and Wales, 21 per cent showed serological evidence of C burnetii infection.     

白芦笋花药愈伤组织诱导及绿芽分化

为建立芦笋单倍体育种技术体系以解决国内芦笋新品种资源贫乏问题,笔者以白芦笋花药为外植体进行了愈伤组织的诱导及绿芽分化研究。试验结果表明,芦笋花药经过4d的冷藏(4℃)处理后,接种于含有NAA2.0 mg/L、6-BA1.0mg/L及6%蔗糖的1/2MS培养基上,可产生愈伤组织;每年的4月份接种花药的愈伤组织诱导率最高,8月份次之,11月份最低。品种间、同一品种不同单株间花药的愈伤组织诱导率不同,以‘UC155’品种(18.9%)最高,显著高于其他三个品种‘UC142’(11.6%)、‘Gijnlim’(10.3%)、‘Thielim’(5.8%),所有试验株系中以‘UC155’-8的愈伤组织诱导率最高,达83.5%;每日补充光照强度为1000 lx的光照,比全暗培养更有利于芦笋花药愈伤组织的形成;花药接种前进行离心处理(4000 r/min)30 min,不能提高愈伤组织诱导率;愈伤组织转瓶培养于NAA 0.5 mg/L、6-BA 1.0 mg/L及3%蔗糖的MS培养基上,能分化出无根绿芽;不同品种间绿芽分化率有差别,以‘Gijnlim’品种最高(67.2%),‘UC142’品种最低(14.1%);未分化绿芽的愈伤组织再转入于不含植物生长调节剂的MS培养基上培养,部分愈伤组织能分化出绿芽     

Maize Yield Response to Zinc Sources and Effectiveness of Diagnostic Indicators

Maize yield is often limited by zinc (Zn) deficiency. The objectives of this study were to (i) evaluate maize yield response to Zn applied at four different rates, (ii) evaluate the yield response and agronomic efficiency of maize to the application of a complex fertilizer, MicroEssentials SZ (12N–40P–0K–10S–1Zn), compared to different rates of monoammonium phosphate (MAP) + ammonium sulfate (AS) + zinc sulfate (ZnSO4), and (iii) evaluate the association between tissue Zn concentration and soil-test Zn with the maize response to Zn fertilizer. Eleven experiments were carried out during the 2010, 2011, and 2012 growing seasons throughout eight states in the USA. Treatments consisted of four Zn rates of a physical blend of MAP + AS + ZnSO₄ (0, 2.24, 4.48, 6.72, and 11.2 kg/ha Zn) and MicroEssentials SZ at a Zn rate of 2.24 kg/ha Zn. Nitrogen, phosphorus (P), and sulfur (S) rates were balanced across treatments (40 kg/ha P, 22 kg/ha S) and fertilizers were broadcast and incorporated immediately prior to planting. Treatment and location main effects were significant (P < 0.001) on corn yields, whereas the interaction treatment × location was not (P = 0.33). Maize responded positively to Zn fertilization; average yields across locations increased from 10,540 kg ha^?1 without Zn to 11,530 kg ha^?1 with 11.21 kg Zn ha^?1 applied as a physical blend. The yield response and Zn agronomic efficiency of maize with the application of the complex fertilizer at a rate of 2.24 kg Zn ha^?1 averaged 1004 kg ha^?1 and 448 kg maize kg Zn^?1, respectively, significantly higher (P < 0.1) than the yield response and Zn agronomic efficiency with the application of a physical blend with the same Zn rate, which averaged 293 kg ha^?1 and 131 kg maize kg Zn^?1, respectively. The Zn concentration in plant tissue of unfertilized plots varied greatly and was not related to the maize response to Zn fertilizer (r = 0.01; P = 0.98). With respect to soil Zn, a negative but nonsignificant relationship was found between maize response to Zn fertilizer and soil-test Zn (r = ?0.51; P = 0.16).     

Accumulation of Lead and Arsenic by Potato Grown on Lead–Arsenate-Contaminated Orchard Soils

There are concerns of potential food chain transfer of metals in crops grown on lead–arsenate-contaminated soils. The objective of this study was to investigate lead and arsenic uptake by four potato (Solanum tuberosum L.) cultivars grown on lead–arsenate-contaminated soils with lead and arsenic concentrations ranging from 350 to 961 and 43 to 290 mg kg^?1, respectively. Yield was not reduced due to treatment. Potato tubers were washed thoroughly before peeling. Lead concentration in both peeled tubers and peel was below instrument detection limit. Arsenic concentration in peeled tubers grown on the lead–arsenate soils ranged from 0.24 to 1.44 mg kg^?1. Arsenic concentration was 60% higher in the peel than in the peeled tuber. The relatively high arsenic levels in the peel demonstrated that arsenic was taken up into the potato peel tissue. It is recommended that if potatoes are grown on these soils they should be peeled before consumption.

Abbreviations Pb, lead; As, arsenic; DW, dry weight; FW, fresh weight     

Effect of stocking biomass on solids,phytoplankton communities,common off‐flavors,and production parameters in a channel catfish biofloc technology production system

The effect of initial channel catfish (Ictalurus punctatus, Rafinesque, 1818) fingerling biomass (1.4, 1.8, or 2.3 kg m^?3) on phytoplankton communities, common off‐flavours and stocker catfish production parameters was evaluated in biofloc technology production tanks. Stocker catfish size (145.5–172.6 g fish^?1) at harvest did not differ among treatments, but net yield increased linearly as initial biomass increased (R² = 0.633). Mean total feed consumption increased linearly with initial catfish biomass (R² = 0.656) and ranged from 10.7 to 15.8 kg m^?3. Total suspended solids (TSS) in all treatments increased linearly with total feed addition, and high TSS appeared to impact negatively daily feed consumption. Initial phytoplankton populations were dominated by small colonial green algae and diatoms, and later transitioned to populations dominated by a small, filamentous cyanobacteria and diatoms. Low, variable concentrations of 2‐methylisoborneol and geosmin were present in biofloc tank water during most of the study and two tanks yielded catfish with 2‐methylisoborneol or geosmin concentrations that might be classified as off‐flavour. One isolate of actinomycete was isolated sporadically from some biofloc tanks, but its abundance was not correlated with 2‐methylisoborneol concentration in tank waters. The microbial sources of 2‐methylisoborneol and geosmin in biofloc tanks remain unidentified.     

Assessing the inclusion of seafood in the sustainable diet literature

The literature on sustainable diets is broad in its scope, and application yet is consistently supportive of a move away from animal‐based diets towards more plant‐based diets. The positioning of seafood within the sustainable diet literature is less clear. A literature review was conducted to examine how the environmental impacts of seafood consumption are assessed and what conclusions are being drawn about the inclusion of seafood in a sustainable diet. Seafood is an essential part of the global food system but is not adequately addressed in most of the sustainable diet literature. Aquaculture, the world's fastest growing food sector, was considered by very few papers. Seafood consumption was commonly presented as a dilemma due to the perceived trade‐offs between positive health outcomes from eating seafood and concerns of overfishing. A number of studies included seafood as part of their sustainable diet scenario, or as part of a diet that had lower impacts than current consumption. Most of the indicators used were biophysical, with a strong focus on greenhouse gas emissions, and very few studies addressed biological or ecological impacts. The assessment of seafood was limited in many studies due to relevant data sets not being incorporated into the models used. Where they were used, data sources and methodological choices were often not stated thereby limiting the transparency of many studies. Both farmed and wild‐capture production methods need to be integrated into research on the impacts of diets and future food scenarios to better understand and promote the benefits of sustainable diets.     

Differing environmental drivers of settlement across the range of southern rock lobster (Jasus edwardsii) suggest resilience of the fishery to climate change

Temporal and spatial trends in settlement of the southern rock lobster, Jasus edwardsii, were examined to identify the influence of environmental variables over different spatial scales. Settlement data were collected from 1994 to 2011 along the Southern Australian and New Zealand coasts. We identified common settlement trends at a regional scale (100–500 km): the magnitude of settlement at sites from South Australia (SA) and Victoria (VIC) were similar, but different to sites in Tasmania (TAS). In New Zealand, three spatial regions were identified: northern (NNZ), middle (MNZ) and southern regions (SNZ). Higher settlement in SA, VIC and MNZ occurred in years with higher rainfall and storms in spring and El Niño conditions. In TAS and SNZ, higher settlement occurred during La Niña conditions. These results suggest that settlement over regional scales is modulated by oceanic processes, but outcomes vary between regions. At a local scale, a higher wave period and wind relaxation were relatively more important than the sea surface temperature (SST) in SA and VIC. In TAS, the current velocity also influenced the strength of settlement. However, much of the local settlement variability was not explained by the models suggesting that settlement in J. edwardsii is a complex process where larval behaviour, biological factors and oceanographic processes interact over different scales. The apparently complex processes affecting settlement showed that environmental conditions that reduced settlement strength in one region of the fishery often increased settlement strength in other regions. This could provide resilience to climate change at the stock level.     

Effects of solids removal on water quality and channel catfish production in a biofloc technology production system

Total suspended solids control was evaluated in a channel catfish (Ictalurus punctatus) biofloc technology production system. Settling chamber flow rates were 0.9 (LO) or 2.9 (HI) L/min to reduce total suspended solids to 300 mg/L; solids were not removed from control tanks. Channel catfish yields (7.6–8.7 kg/m³) were not affected significantly, but control fish were skewed toward smaller size classes. Control treatment channel catfish tolerated 1,410 mg/L total suspended solids without adverse effects. LO- and HI-treatment fillet geosmin concentrations were high enough to be designated as off-flavor. Water quality results suggested that nitrification was affected by solids removal.