Development of an ELISA to detect antibodies to a protective lipopolysaccharide fraction of Leptospira borgpetersenii serovar hardjo in cattle.

Monoclonal antibodies (Mabs) were produced against Leptospira borgpetersenii serovar hardjo-type Bovis antigens. A panel of 28 Mabs were characterised. Only the nine Mabs toward a lipopolysaccharide (LPS) fraction of 18, 24 kDa bands and a 26-28 kDa smear showed agglutinating, leptospiricidal and growth-inhibition activities, and passively protected hamsters against renal infection with hardjo. They also reacted strongly in the CH-ELISA, captured killed whole hardjo leptospires, gave good fluorescence in indirect FAT against smears of hardjo culture and exhibited no cross reactivity with strains in heterologous serogroups. On the basis of optimal activity in a range of tests, one IgG class Mab (designated 25) was selected for use in an antibody-capture ELISA system for the detection of bovine anti-hardjo antibodies. The system gave a wide separation of absorbance values between positive and negative sera at a 1:10 dilution. The antibodies detected by this assay are believed to be protective anti-LPS IgG.     

Peroxidase activity as a measure of neutrophil populations in inflammatory peritoneal exudates of rainbow trout, Oncorhynchus mykiss (Walbaum)

A quantitative peroxidase assay using tetramethylbenzidine was applied to exudates from peritoneal cavities of rainbow trout which had been inflamed by intraperitoneal injection of Yersinia ruckeri . Most of the peroxidase activity was cell-associated, with values for extracellular peroxidase below 5% of total peroxidase. No free peroxidase activity was detected in resting cavities. The kinetics of neutrophil numbers and peroxidase activity in peritoneal exudates during the 6 days of inflammation studied followed identical patterns, with a correlation coefficient of 0.996. This shows that the peroxidase assay can be used as an indirect, quantitative evaluation of neutrophil responses during peritoneal inflammation.     

Effect of room temperature and dietary amino acid concentration on performance of lactating sows. NCR-89 Committee on Swine Management.

Mixed-parity sows (n = 267) from five research stations were used to investigate whether a reduction of excess dietary amino acids would improve feed intake and performance of lactating sows experiencing heat stress. Experimental treatments included effects of room temperature (warm or hot) and diet (adequate protein [AP] or low protein [LP]). The corn-soybean meal AP diet was formulated to contain 16.5% CP, .8% lysine, and .67% digestible lysine. The LP diet was formulated to contain 13.7% CP, .76% lysine, and .66% digestible lysine using corn, soybean meal, and synthetic lysine. Feed intake during gestation was standardized at 1.8 kg x sow(-1) x d(-1). At parturition, litter size was adjusted to no fewer than nine pigs. Mean high temperature in the warm and hot rooms was 20.4 and 29.2 degrees C and mean low temperature was 17.7 and 27.1 degrees C, respectively. The hot environment reduced (P < .01) feed intake of sows (4.19 vs 6.38 kg/d) during lactation, weaning weight of sows (176.2 vs 193.6 kg), percentage of sows displaying estrus (79.2 vs 93.4%) by d 15 postweaning, and litter growth rate (1.74 vs 2.11 kg/d) and increased (P < .01) respiration rate of sows on d 10 postpartum (71.9 vs 36.5 breaths/min) compared with the warm environment. Litter size and backfat loss of sows were not affected by treatments. No significant diet x room temperature interactions were observed for voluntary feed intake, body weight loss, backfat loss, or respiration rate of sows. Litter growth rate was depressed by feeding the LP diet in the warm room but was improved by feeding the LP diet in the hot room (warm-AP, 2.17; warm-LP, 2.05; hot-AP, 1.71; hot-LP, 1.77 kg/d; P < .05). Reduction of dietary crude protein combined with supplementation of crystalline lysine to reduce concentrations of excess dietary amino acids did not significantly reduce heat stress of sows, but it did support slight improvements in weight gain of litters nursing heat-stressed sows.     

Macroalgal meadow habitats support fish and fisheries in diverse tropical seascapes

Canopy‐forming macroalgae can construct extensive meadow habitats in tropical seascapes occupied by fishes that span a diversity of taxa, life‐history stages and ecological roles. Our synthesis assessed whether these tropical macroalgal habitats have unique fish assemblages, provide fish nurseries and support local fisheries. We also applied a meta‐analysis of independent surveys across 23 tropical reef locations in 11 countries to examine how macroalgal canopy condition is related to the abundance of macroalgal‐associated fishes. Over 627 fish species were documented in tropical macroalgal meadows, with 218 of these taxa exhibiting higher local abundance within this habitat (cf. nearby coral reef) during at least one life‐history stage. Major overlap (40%–43%) in local fish species richness among macroalgal and seagrass or coral reef habitats suggest macroalgal meadows may provide an important habitat refuge. Moreover, the prominence of juvenile fishes suggests macroalgal meadows facilitate the triphasic life cycle of many fishes occupying diverse tropical seascapes. Correlations between macroalgal canopy structure and juvenile abundance suggests macroalgal habitat condition can influence levels of replenishment in tropical fish populations, including the majority of macroalgal‐associated fishes that are targeted by commercial, subsistence or recreational fisheries. While many macroalgal‐associated fishery species are of minor commercial value, their local importance for food and livelihood security can be substantial (e.g. up to 60% of landings in Kenyan reef fisheries). Given that macroalgal canopy condition can vary substantially with sea temperature, there is a high likelihood that climate change will impact macroalgal‐associated fish and fisheries.     

The suitability of VIE tags to assess stock enhancement success in juvenile European lobsters (Homarus gammarus)

Assessments of stock enhancement programmes for European lobsters (Homarus gammarus) require mark‐recapture analysis of stocked individuals. However, established tag technology is deemed unsuitable for extensive use by many current lobster hatcheries, particularly upon the early juvenile stages. We tested the suitability of fluorescent Visible Implant Elastomer (VIE) tags for use in 5‐month‐old juvenile lobsters. Three treatment groups comprising 348 cultured lobsters in total were used to examine survival, growth and tag retention, and to assess mobility, shelter use and moulting behaviours. Tagging had no significant effect on lobster survival, growth, mobility, shelter use or moult frequency. Survival over 7 weeks was 75% among lobsters tagged with two elastomers, 76% in those with one elastomer and 74% among untagged controls. Mortality during moulting did not increase in tagged (6%) compared to untagged lobsters (9%). We found no evidence that VIE tags cause any negative effects that would be expected to inhibit survival upon wild release, but tag loss had reached 12% in both tagged treatments after 7 weeks and showed no sign of abating. Our study suggests that VIEs effectiveness in discerning cultured lobsters long after wild release may be limited when used in smaller juveniles.     

Possible role of ectomycorrhizal fungi in cycling of aluminium in podzols

Budget studies in boreal podzols indicate a considerable upward transport of aluminium (Al) from the mineral soil into the organic horizon. In this paper we studied if ectomycorrhizal (EcM) fungi can be involved in this upward transport via their extramatrical hyphae. We tested the use of gallium (Ga) as proxy for Al. Transport of Al through EcM hyphae was studied in vitro in a two-compartment Petri dish system. Two of the five fungal isolates tested transported Al. Using Ga instead of Al revealed the same trend in these systems, confirming the use of Ga as proxy for Al. Upward transport of Ga was studied in an artificial podzol. Pinus sylvestris seedlings were colonised by a natural community of EcM fungi from fresh forest soil. Gallium addition to the mineral soil led to increased Ga content in roots in the organic horizon and in the shoot. Upward Ga allocation was significantly higher when roots were excluded from the mineral soil by a mesh, only allowing fungal mycelium to grow through. We conclude that at least some EcM fungi transport Al and that Ga, and probably also Al, can be transported upwards by EcM fungal hyphae in a podzol system. These findings support the hypothesis that EcM fungi play a role in upward transport of Al in podzols.     

Effects of multiple concurrent stressors on rectal temperature, blood acid-base status, and longissimus muscle glycolytic potential in market-weight pigs

Sixty-four market-weight (130.0 +/- 0.65 kg) barrows (n = 16) and gilts (n = 48) were used in a split-plot design with a 2 x 2 x 2 factorial arrangement of treatments: 1) handling intensity (gentle vs. aggressive), 2) transport floor space (0.39 vs. 0.49 m(2)/pig), and 3) distance moved during handling (25 vs. 125 m) to determine the effects of multiple concurrent stressors on metabolic responses. For the handling intensity treatment, pigs were moved individually approximately 50 m through a handling course with either 0 (gentle) or 8 (aggressive) shocks from an electric goad. Pigs were loaded onto a trailer and transported for approximately 1 h at floor spaces of either 0.39 or 0.49 m(2)/pig. After transport, pigs were unloaded, and the distance moved treatment was applied; pigs were moved 25 or 125 m through a handling course using livestock paddles. Rectal temperature was measured, and blood samples (to measure blood acid-base status) were collected 2 h before the handling intensity treatment was applied and immediately after the distance moved treatment was applied. A LM sample to measure glycolytic potential was collected after the distance moved treatments on a subset of 32 pigs. There were handling intensity x distance moved interactions (P < 0.05) for several blood acid-base measurements. In general, there was no effect of distance moved on these traits when pigs were previously handled gently. However, when pigs were previously handled aggressively, pigs moved 125 compared with 25 m had greater (P < 0.05) blood lactate and less (P < 0.05) blood pH, bicarbonate, and base-excess. Pigs transported at 0.39 compared with 0.49 m(2)/pig had a greater (P < 0.01) increase in creatine kinase values; however, transport floor space did not affect any other measurements. Data were analyzed by the number of stressors (the aggressive handling, restricted transport floor space, and 125-m distance moved treatments) experienced by each pig (0, 1, 2, or 3). As the number of stressors experienced by the pig increased, rectal temperature, blood lactate, and LM lactate increased linearly (P 相似文献   

Distributions of soil phosphorus in China’s densely populated village landscapes

Purpose  

Village landscapes, which integrate small-scale agriculture with housing, forestry and a host of other land use practices, cover more than 2 × 10⁶ km² across China. Village lands tend to be managed at very fine spatial scales (≤30 m), with managers altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Under these conditions, accumulation of excess phosphorous in soils has become important contributor to eutrophication of surface waters across China’s densely populated village landscapes. The aim of this study was to investigate relationships between fine-scale patterns of agricultural management and soil total phosphorus (STP) within China’s village landscapes.