Heavy metal and waste metabolite accumulation and their potential effect on rainbow trout performance in a replicated water reuse system operated at low or high system flushing rates

A six-month trial was conducted to compare the effects of high and low make-up water flushing rates on rainbow trout performance and water quality in replicated water reuse aquaculture systems (WRAS). Six identical 9.5 m³ WRAS, containing a single 5.3 m³ tank and operated at a total recirculating flow of 380 L/min were stocked with 1000 rainbow trout each (133 ± 1 g). Three WRAS were operated at high flushing rates (2.6% of total flow) and three were operated at low flushing rates (0.26% of total flow), providing system hydraulic retention times of 0.67 and 6.7 days, respectively. During a one-week period when fish were at maximum feeding (i.e., mean feed loadings of 0.53 and 5.3 kg/m³ make-up water flow high and low make-up conditions, respectively) and maximum densities (80 kg/m³), water samples were collected across all unit processes. All typical water quality parameters measured at the culture tank outlet during this week were significantly different between treatments, except for dissolved oxygen, carbon dioxide, and temperature, which were controlled. Within the low exchange WRAS, total suspended solids (TSS), carbonaceous biochemical oxygen demand, total ammonia nitrogen, un-ionized ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, dissolved organic carbon, particle counts, true color, and total heterotrophic plate counts were significantly greater, whereas UV transmittance (%) and alkalinity were significantly reduced. Of these parameters, TSS, fine particles, and heterotrophic bacteria counts were the only parameters of concern within the low exchange WRAS. The potential impacts of each water quality constituent are discussed. Element analysis indicated that concentrations of nine metals were significantly greater within the low exchange WRAS. The highest metal concentrations measured at low exchange were within safe recommended limits, with the exception of copper (0.037–0.056 mg/L), which could have reached chronically toxic levels. Although cumulative mortality was relatively low for all WRAS, a linear trend between copper concentration and mortality was evident. The highest mortality, which occurred within a low exchange WRAS, coincided with the highest copper (0.056 mg/L); and the lowest mortality, which occurred within a high exchange WRAS, coincided with non-detectable copper levels. A comparison of survival between treatments bordered significance, 99.5 ± 0.1 and 98.9 ± 0.4% for the high and low exchange WRAS, respectively. There was no significant difference in rainbow trout weight at the conclusion of the study, i.e., approximately one year post-hatch: 1401 ± 23 and 1366 ± 33 g for the high and low exchange WRAS, respectively. There were no differences in thermal growth coefficients or feed conversion ratios between the high and low exchange treatments. Rainbow trout condition factor was significantly greater within the low exchange WRAS.     

Estimating tree component biomass using variable probability sampling methods

As a signatory to the Kyoto Protocol, Australia is obliged to stabilize greenhouse gas emissions at 8% above 1990 levels by 2008–2012. To demonstrate achievement of this goal, Australia requires national annual estimates of changes in vegetation biomass as greenhouse gas emissions from land use change. These emission estimates are, however, uncertain due largely to the scarcity of existing allometric equations for calculating biomass. The large investment of time and funding required for harvesting, particularly using traditional techniques such as double regression and ratio sampling, also precludes the generation of new equations. Alternative techniques for rapid, cost-effective, and reliable estimation of biomass therefore require investigation. This study, conducted in central Queensland, compared estimates of component biomass that were generated for seven trees of the woodland species Eucalyptus populnea (poplar box) using ratio sampling and variable probability sampling techniques, namely randomized branch sampling (RBS) and RBS with importance sampling (IS). Application of randomized branch sampling consistently underestimated the biomass of leaf and small branches (<1 cm in diameter) and produced weak prediction equations. In contrast, results suggest that RBS with IS is particularly useful in predicting woody (trunk and branches >1 cm in diameter) biomass, and prediction equations agreed with existing equations for this species. However, this method tended to overestimate individual tree woody biomass. The study concluded that RBS with IS was a viable alternative to current methods.     

Conservation of amenity trees in the Lothian Region of Scotland

Amenity trees, defined as all trees excluding those in Forestry Commission and grant-aided woodlands, worked coppice, commercial orchards and hardy-stock nurseries, were surveyed in the Lothian Region between 1972 and 1975. The Region (c. 188,000 ha or 1,877 km²) was stratified into three land categories-(i) burghs (Scottish equivalent of English boroughs), (ii) lowland rural and (iii) upland rural, parts of at least 10% of the 1 km squares (vide Ordnance Survey maps) of each land category being surveyed; the surveyed squares were selected randomly.Numbers of trees per ha ranged from 59 in burghs to 43 and 24 in lowland and upland (above 150m) rural areas respectively. In total there were 6·7 ± 1·9 million amenity trees in the Region divided as follows: 1·4 ± 0·4, 3·2 ± 0·9 and 2·1 ± 0·6 millions between the burghs and lowland and upland rural areas respectively; c. 1·0 m of the 1·4 million trees in burghs were located in Edinburgh. Approximately 70% of trees were deciduous with a larger proportion of conifers in upland areas than elsewhere; sycamore (Acer pseudoplatanus L.), hawthorn (Crataegus spp.) and Scots pine (Pinus sylvestris L.) were the commonest of 76 species or generic groupings recorded, accounting for 11·6, 11·1 and 10·5% respectively of the regional total. Birch (Betula spp.) was the commonest deciduous tree in upland areas where ash (Fraxinus excelsior L.) and beech (Fagus sylvatica L.) were more abundant than sycamore. In the burghs wych elm (Ulmus glabra Huds.) was more numerous than hawthorn and less than sycamore. Trees in Edinburgh differed greatly from those in the smaller towns (burghs) with more rural atmospheres, where sycamore, wych elm, hawthorn, elder and birch contrasted with apple, lilac, flowering cherry, sycamore and rowan occurring abundantly in Edinburgh.Excluding Edinburgh, over 50% of the Region's trees were identified in broadleaved (26·7%), coniferous (21·4%) and mixed (13·6%) woodlands, with 12·0% and 8·1% occurring in shelterbelts and hedgerows respectively; gardens and parks, of all sorts, only accounted for 4·5% and 1·1% respectively.Size class distribution ssuggest that there are sufficient developing saplings to maintain the existing number of mature trees but that wych elm (Ulmus glabra Huds.), unless devastated by Dutch elm disease, sycamore and ash are likely to increase at the expense of oak (Quercus spp.), lime (Tilia spp.), Scots pine and beech. In some situations, however, the resourse seems to be seriously deficient in saplings, e.g. oaks in parks.     

Pyogenic bacterial infections in humans with IRAK-4 deficiency

Members of the Toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) superfamily share an intracytoplasmic Toll-IL-1 receptor (TIR) domain, which mediates recruitment of the interleukin-1 receptor-associated kinase (IRAK) complex via TIR-containing adapter molecules. We describe three unrelated children with inherited IRAK-4 deficiency. Their blood and fibroblast cells did not activate nuclear factor kappaB and mitogen-activated protein kinase (MAPK) and failed to induce downstream cytokines in response to any of the known ligands of TIR-bearing receptors. The otherwise healthy children developed infections caused by pyogenic bacteria. These findings suggest that, in humans, the TIR-IRAK signaling pathway is crucial for protective immunity against specific bacteria but is redundant against most other microorganisms.     

增加城市绿量的好方法--垂直绿化

垂直绿化做为一种立体绿化形式,占地少,绿化效果好,是增加城市绿量和形成城市美好景观的好方法.本文从垂直绿化的特点、垂直绿化的材料、垂直绿化的形式三方面详尽阐述了在城市中发展垂直绿化的必要性.     

The dynamic influence of the DRB1*1101 allele on the resistance of sheep to experimental Teladorsagia circumcincta infection

ABSTRACT: Suffolk sheep carrying the DRB1*1101 (previously referred to as-DRB1*0203 or G2) allele have been reported to show increased resistance to natural Teladorsagia circumcincta infection compared to non-carriers. The objective of this study was to compare the biochemical and physiological responses of DRB1*1101 carrier and non-carrier twin lambs to an experimental infection with 3 × 104 L3 Teladorsagia circumcincta. The variables studied included worm burden, faecal egg count, abomasal mast cells, IgA, IgE, IgG1 plus IgG2 and haematological parameters at 0, 3, 7, 21 and 35 days post infection (dpi), and duodenal smooth muscle contractility at 0 and 35 dpi. DRB1*1101 carrier lambs had significantly lower worm burden, higher mast cell and plasma platelet counts than the DRB1*1101 non-carriers (P < 0.05). Before infection, the non-carrier lambs exhibited significantly higher mucosal levels of all antibody isotypes measured compared to the carriers; these levels remained relatively stable over the course of infection in the non-carriers while there was a slow build up of these antibodies in the carriers up to day 21 post infection (pi). The DRB1*1101 non-carrier lambs had a significantly higher plasma lymphocyte count, and produced greater duodenal contractile force relative to the carrier lambs (P < 0.05). There was no significant difference between genotypes in the level of plasma eosinophils, monocytes, neutrophils or FEC. This evidence suggests that resistance conferred by DRB1*1101 is acquired rather than innate, depends on worm expulsion rather than fecundity and is dependent on mucosal mast cell proliferation, platelet activation, and IgA and IgE antibody responses.     

Longer-term risk of Mycobacterium bovis in Irish cattle following an inconclusive diagnosis to the single intradermal comparative tuberculin test

In Ireland, new bovine tuberculosis (bTB) cases are detected using both field and abattoir surveillance. During field surveillance, an animal may be deemed a 'standard inconclusive reactor' (SIR) to the single intradermal comparative tuberculin test (SICTT) if the bovine response is >2mm, and from 1 to 4mm greater than the avian response. Little is known about the future infection risk posed by SIR animals that pass a subsequent retest, so-called 'transient SIR' (TIR) animals. The objective of this study was to critically evaluate the future bTB status of TIR animals, by examining the future risk of bTB diagnosis over the 4 years following initial SIR diagnosis and clearance at the subsequent retest. The study included all TIRs that were identified as SIRs in 2005 in otherwise free herds at tests with no other reactors at that test and that were clear at the subsequent retest. The analysis was restricted to cows that were neither sold, other than direct to slaughter, nor exported from the herd during the follow up period (to the end of 2009). Five control cows were randomly selected from each study herd. A parametric survival model with shared frailties, to account for clustering within herds, was developed to model time from passing a retest to future bTB diagnosis. The final parametric survival model contained the variables: TIR status in 2005, inconclusive status during the follow-up period, location, herd restricted during the study, time since last restriction within the herd and age. The time ratio for the TIR status variable was significant (p<0.001) indicating that on average the time to diagnosis with bTB for TIRs was 78% shorter compared to the non-TIRs. The frailty term was significant (p<0.001) indicating that animals within some herds were more likely to become reactors compared to other herds. These results have important implications for national policy and future management of TIR animals. Further, private veterinary practitioners and their clients should be aware of the increased risk associated with TIRs.     

The comparative performance of the single intradermal test and the single intradermal comparative tuberculin test in Irish cattle, using tuberculin PPD combinations of differing potencies

In national bovine tuberculosis (BTB) control programmes, testing is generally conducted using a single source of bovine purified protein derivative (PPD) tuberculin. Alternative tuberculin sources should be identified as part of a broad risk management strategy as problems of supply or quality cannot be discounted. This study was conducted to compare the impact of different potencies of a single bovine PPD tuberculin on the field performance of the single intradermal comparative tuberculin test (SICTT) and single intradermal test (SIT). Three trial potencies of bovine PPD tuberculin, as assayed in naturally infected bovines, namely, low (1192IU/dose), normal (6184IU/dose) and high (12,554IU/dose) were used. Three SICTTs (using) were conducted on 2102 animals. Test results were compared based on reactor-status and changes in skin-thickness at the bovine tuberculin injection site. There was a significant difference in the number of reactors detected using the high and low potency tuberculins. In the SICTT, high and low potency tuberculin detected 40% more and 50% fewer reactors, respectively, than normal potency tuberculin. Furthermore, use of the low potency tuberculin in the SICTT failed to detect 20% of 35 animals with visible lesions, and in the SIT 11% of the visible lesion animals would have been classified as negative. Tuberculin potency is critical to the performance of both the SICTT and SIT. Tuberculin of different potencies will affect reactor disclosure rates, confounding between-year or between-country comparisons. Independent checks of tuberculin potency are an important aspect of quality control in national BTB control programmes.