Defect-disorder and risk assessment of heritage trees in urban Hong Kong

Heritage trees in a city, echoing factors conducive to outstanding performance, deserve special care and conservation. To understand their structural and health conditions in urban Hong Kong, 30 defect-disorder (DD) symptoms (physical and physiological) subsumed under four tree-position groups (soil-root, trunk, branching, and crown-foliage) and tree hazard rating were evaluated. The surveyed 352 trees included 70 species; 14 species with 233 trees were native. More trees had medium height (10–15 m), medium DBH (1–1.5 m) and large crown (>15 m). In ten habitats, public park and garden (PPG) accommodated the most trees, and roadside traffic island (RTI) and public housing estate (PH) had the least. Tree dimensions and tree habitats were significantly associated. The associations between the 2831 DD and tree-position groups, tree habitats and tree hazard rating were analyzed. Fourteen trees from Ficus microcarpa, Ficus virens and Gleditsia fera had high hazard rating, 179 trees from 22 species moderate rating, and 159 trees from 55 species low rating. RTI, roadside tree strip (RTS), roadside tree pit (RTP), roadside planter (RP) and stone wall (SW) had more moderate hazard rating, and PPG, roadside slope (RS) and government, institutional and community land (GIC) more low rating. Redundancy analysis showed that DD were positively correlated with RTS, RTP, RP and SW, but negatively correlated with PPG, RS and GIC (p < 0.05). The DD significantly increased tree hazard rating and failure potential. Future management implications for heritage-tree conservation and enhancement focusing squarely on critical tree defect-disorder in urban Hong Kong were explored, with application to other compact cities.     

Modeling the fate of dietary 17B-estradiol and its metabolites in an American eel (Anguilla rostrata) recirculating aquaculture system

Recirculating aquaculture system (RAS) is being applied in many aquaculture industries as it provides an opportunity to produce fish in a contained system with minimal use of water. In proposed RAS-based farming of the American eel, 17β-estradiol (E2) is being investigated as an in-feed drug to feminize and increase growth of farmed eels. This creates potential for release of E2 and its metabolites from the eel RAS and information is needed to monitor and manage eel farm effluents to reduce impact on the environment. In the current study, the concentrations of E2 and its metabolites (i.e., estrone (E1) and estriol (E3)) were monitored from different compartments in the RAS and analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS). E2 levels ranged from 8 to 25 ng/L in the water recirculating within the RAS and declined to 2–6 ng/L in the weeks post-treatment. E1 levels were within similar ranges as E2, whereas E3 levels were below 2 ng/L throughout the study. The results were used to develop a computational model to describe the fate of E2 and its metabolites in the RAS, and to delineate the influences of metabolism and hydrodynamics for the removal of E2 by RAS processes. The rapid removal of uneaten feed and feces downstream of inventory tanks was found to be the most significant mechanism for the removal of 2–6% of the E2 added in feed daily, producing a concentrated effluent stream suitable for strategic treatment strategies. Greater than 94% of E2 added to the system with feed was either metabolized by the eels and/or bacteria in the biofilters of the RAS or was sufficiently bound to solids fractions in the solid samples to resist organic extraction and detection. Additionally, reducing daily water exchange from 23 to 7% of the system water inventory resulted in an increase of only 1 ng/L in E1 concentrations within the RAS system while a negligible change in the concentration of E2 was observed.     

Laboratory and clinical findings and their association with viral and proviral loads in cats naturally infected with feline leukemia virus

This study was conducted to correlate clinical, laboratory, and bone marrow (BM) changes in cats naturally infected with feline leukemia virus and their association with viral loads in blood and BM and proviral loads in BM. Cats were classified into five groups based on antigenemia, clinical and/or laboratory findings and viral/proviral loads, according to a prospective study: symptomatic progressive (GI); asymptomatic progressive (GII); regressive (GIII); unclassified (GIV); or healthy (GV). |Correlations between these five groups and viral/proviral loads were evaluated. High viral and proviral loads were detected in GI and GII and viral loads were significantly associated with laboratory signs. Proviral loads detected in BM were significantly lower in GIII and GIV. GI cats were more likely to develop hematopoietic disorders than those from the other groups. Hematological and clinical disorders and disease severity are related to higher viral blood and proviral BM loads.     

Porcine circovirus type 2 (PCV2) and Campylobacter infection induce diarrhea in piglets: Microbial dysbiosis and intestinal disorder

Diarrhea is considered to be associated with microbial dysbiosis caused by infection of pathogens but poorly understood. We herein characterized the colonic microbiota of diarrheal early-weaning piglets infected with porcine circovirus type 2 (PCV2) and Campylobacter. Campylobacter infection significantly decreased species richness and Shannon diversity index of colonic microbiota together with a significant increase in the proportion of Campylobacter and Enterobacteriaceae, whereas no significant difference on the above indexes was observed in piglets infected with PCV2 compared with healthy piglets. PCV2 and Campylobacter infection could disturb the homeostasis of colonic microbiota through deterioration of ecological network within microbial community, and specially Campylobacter performed as a module hub in ecological networks. The microbial dysbiosis caused metabolic dysfunction and led to a remarkable reduction in production of short chain fatty acids, following by a higher pH level in colon cavity. Campylobacter infection disturbed the function of colonic tract barrier observed in terms of significant lower relative expression of claudin-1, occluding, and zonula occludens protein-1 genes, and PCV2 infection induced intestinal inflammation together with a higher permeability of colon. Generally, these results suggested that PCV2 and Campylobacter infection could induce microbial dysbiosis and metabolic dysfunction, and cause intestinal disorder, all of which finally were associated to contribute to the diarrhea of early-weaning piglets.     

L-色氨酸研究进展

色氨酸作为一种必须氨基酸,广泛应用于医药、食品及饲料等方面。随着对色氨酸研究的不断深入,其生产方式也从蛋白水解及化学合成发展到微生物直接发酵等方法。而基因工程等生物技术的发展,使得代谢工程逐渐在色氨酸生产菌种的选育中成为研究热点。综述了色氨酸的生产方式、菌株构建以及应用等方面的研究进展。     

Update on Metabolic Diseases Associated With Laminitis in Horses and Ponies

Several recent scientific publications describe some important findings that may further improve our ability to diagnose and manage both equine Cushing's disease (ECD) and equine metabolic disease (EMD). This abstract provides a brief summary of recent findings in ECD and EMD that have immediate application for clinical practice.     

Metabolic and histological parameters of silver catfish (Rhamdia quelen) exposed to commercial formulation of 2,4-dichlorophenoxiacetic acid (2,4-D) herbicide

The objective of this study was to investigate the effects of commercial formulation of herbicide 2,4-D on metabolic parameters, acetylcholinesterase (AChE) activity and liver histological evaluation of silver catfish (Rhamdia quelen) exposed for 96 h. AChE activity increased in brain (600 and 700 mg L⁻¹) and decreased in all concentrations tested in muscle tissue. Hepatic glycogen was reduced after 2,4-D exposure ranging from 47.67% (400 mg L⁻¹) until 59.3% (700 mg L⁻¹). Hepatic tissue showed lactate reduction at all 2,4-D concentrations tested and glucose was reduced only at 700 mg L⁻¹. In the highest concentration tested hepatic glycogen and glucose reduced instead plasma glucose levels increased. White muscle tissue showed glycogen reduction in fingerlings exposed to all herbicide concentrations and glucose reduction at 700 mg L⁻¹. Muscle lactate levels increase at all 2,4-D concentrations tested. Vacuolation of hepatocytes and changes in its arrangement cords were observed by histologic analysis in group treated with 700 mg/L of 2,4-D. These results suggest that silver catfish exposed to concentrations of 2,4-D near of CL₅₀ showed metabolic and histological response to compensate some stress caused by herbicide exposure. Taken together parameters measured can be used as biomarkers to monitor herbicide contaminated water.     

日粮中代谢能和粗蛋白水平对马冈鹅繁殖性能的影响

[目的]探讨不同代谢能水平和粗蛋白水平对马冈鹅产蛋性能以及种蛋孵化率的影响。[方法]选择健康2年龄马冈母鹅随机分为试验Ⅰ、Ⅱ、Ⅲ组和对照组,分别饲喂含有不同代谢能和粗蛋白水平的日粮,收集鹅蛋并进行孵化。试验期间,观察鹅群的健康状况,记录蛋重、产蛋数以及种蛋孵化率。[结果]试验Ⅰ、Ⅱ和Ⅲ组的马冈鹅平均产蛋率以及平均蛋重均显著高于对照组;种蛋合格率以及种蛋受精率也明显提高,试验Ⅲ组均显著高于其他各组（P〈0.05）;3个试验组的饲料成本均低于对照组,其中试验Ⅲ组的饲料成本高于试验Ⅰ和Ⅱ组。[结论]日粮中代谢能和粗蛋白水平对马冈鹅的产蛋性能以及种蛋孵化率均有显著影响。     

Postharvest ethylene conditioning as a tool to reduce quality loss of stored mature sweet oranges

Ethylene is related to senescence but also induces protective mechanisms against stress in plants. The citrus industry only applies the hormone to induce fruit degreening. The aim of this work was to determine the effect of ethylene on the quality of colored citrus fruit stored under commercial conditions to extend postharvest life, since it protects them from stress causing postharvest disorders such as chilling injury (CI) and non-chilling peel pitting (NCPP). The effect of conditioning mature Navelate and Lane Late sweet oranges (Citrus sinensis L. Osbeck) for 4 days with 2 μL L⁻¹ ethylene at 12 °C, rather than at higher temperatures used for degreening, on the quality of fruit stored at 2 or 12 °C, was examined. The ethylene conditioning (EC) treatment did not increase color but reduced calyx abscission and NCPP in fruit of both cultivars stored at 12 °C, and also CI in Navelate fruit at 2 °C. Lane Late fruit did not develop CI but showed a new disorder in EC fruit held at 2 °C. This disorder began as scalded areas around the fruit stem end and extended over the fruit surface during storage. EC had no deleterious effect on the quality of Navelate oranges stored at either 2 or 12 °C. Similar results were found in Lane Late fruit although EC slightly increased off-flavor perception at 2 °C and the maturity index at 2 and 12 °C. Moreover, EC slightly increased the content of bioactive flavonoids in the pulp of Navelate fruit but significant differences between control and EC fruit were only found after prolonged storage at 2 °C. In Lane Late fruit, EC avoided the initial decrease in flavonoid content found in control samples. Results show, therefore, that EC at 12 °C may be a tool to extend postharvest life of NCPP and CI-sensitive oranges, and that the tolerance of citrus cultivars to the combined effect of EC and non-freezing low temperature (2 °C) should be tested to select the proper storage temperature.