磁处理改善豌豆根际土壤生物学性状

采用盆栽的方法,分析磁处理对豌豆根际土壤生物学性状的影响,旨在探究磁处理对豌豆根际土壤肥力及健康状况的影响。试验设置无处理（对照CK）,添加铁粉（A）、磁化铁粉（B）、场强为0.2特斯拉（T）磁铁+铁粉（C）以及0.2 T磁铁（D）的处理,基于高通量测序技术分析磁处理对豌豆根际土壤生物学性状的影响。结果表明：C处理显著增加豌豆根际土壤中可培养细菌和真菌数量,同时微生物生物量C、N、P与CK相比分别增加了34.0%、46.0%、44.2%;β-葡萄糖苷酶、氨肽酶、磷酸酶酶活性分别增加了24.6%、23.7%、31.8%;另一方面,C处理中土壤细菌丰富度和多样性指数Ace、Chao1、Shannon指数显著高于CK;属（Genus）分类水平韦恩图分析中上,CK处理特有的属细菌主要有3个：Sneathiella、Desulfurispora、nannocystaceae;A处理特有的属细菌有7个;B处理特有的属细菌亦有7个;C处理特有的属细菌有11个;D处理特有的属细菌有8个。综上所述,C处理能够显著提高豌豆根际土壤中可培养微生物数量、微生物生物量（C、N、P）、酶活性和细菌多样性等多项指示土壤肥力和健康状况的生物学指标,表明磁场强度为0.2 T的磁铁+5 g磁化铁粉处理具有提高土壤肥力抵御土传病害的能力。     

基于森林功能分区的经营小班划分研究

基于湖南省慈利县二类调查数据，根据森林主导功能的差异、森林林种种类和坡度的不同，将慈利县森林划分成不同的森林功能区，并基于森林功能区按照树种的不同将其进一步划分成不同的经营小班。最后，在地理信息系统的支持下绘制出森林功能分区图和经营小班划分图。结果表明，公益林的面积多于商品林的面积，其中特殊公益林区和一般公益林区面积为1 290 hm²，限制性商品林和一般性商品林面积为1 144 hm²，马尾松和杉木是主要的经济树种。划分经营小班有利于森林的分类经营，为实现林业从传统的以木材生产为主向发挥森林的多功能、多效益的经营方式转变提供条件，进而实现森林的可持续经营，并为促进森林经营单位的可持续发展提供数据支持。     

Characterization of Spray-Dried Hydrolyzed Proteins from Pink Perch Meat Added with Maltodextrin and Gum Arabic

In the present study, spray-dried pink perch meat protein hydrolysate (PPH) and hydrolysate with maltodextrin and gum arabic (PPHMG) were characterized in relation to their physical, rheological, functional, antioxidant, thermal, and sensory properties. The Herschel–Bulkley model was suitable to explain the flow behavior of PPH and PPHMG emulsions. Both the samples exhibited functional and antioxidant properties. Antioxidant activities were significantly higher for PPH compared with PPHMG (p<0.05). PPH and PPHMG alone did not exhibit antimicrobial activity but enhanced the activity of chitosan against pathogens. Sensory acceptability of the samples in soup revealed that PPHMG of up to 4% was highly scored without any traces of bitterness, whereas for PPH, a concentration of up to 3% was acceptable.     

Infection routes of Aeromonas salmonicida in rainbow trout monitored in vivo by real‐time bioluminescence imaging

Recent development of imaging tools has facilitated studies of pathogen infections in vivo in real time. This trend can be exemplified by advances in bioluminescence imaging (BLI), an approach that helps to visualize dissemination of pathogens within the same animal over several time points. Here, we employ bacterial BLI for examining routes of entry and spread of Aeromonas salmonicida susbp. salmonicida in rainbow trout. A virulent Danish A. salmonicida strain was tagged with pAKgfplux1, a dual‐labelled plasmid vector containing the mutated gfpmut3a gene from Aequorea victoria and the luxCDABE genes from the bacterium Photorhabdus luminescens. The resulting A. salmonicida transformant exhibited growth properties and virulence identical to the wild‐type A. salmonicida, which made it suitable for an experimental infection, mimicking natural conditions. Fish were infected with pAKgfplux1 tagged A. salmonicida via immersion bath. Colonization and subsequent tissue dissemination was followed over a 24‐h period using the IVIS spectrum imaging workstation. Results suggest the pathogen's colonization sites are the dorsal and pectoral fin and the gills, followed by a progression through the internal organs and an ensuing exit via the anal opening. This study provides a tool for visualizing colonization of A. salmonicida and other bacterial pathogens in fish.     

Liver histology and histomorphometry in hybrid sorubim (Pseudoplatystoma reticulatum × Pseudoplatystoma corruscans) reared on intensive fish farming

This study aimed to characterize the liver histology and histomorphometry in sorubim hybrid of different categories (nursery, growth and grow‐out) reared on fish farming. The categories were defined considering body weight (BW): nursery category (n = 5): BW = 37.06 ± 6.00 g (31.6–45.3 g); growth category (n = 5): BW = 310.40 ± 53.80 g (242.1–376.4 g) and grow‐out category (n = 5): BW = 874.28 ± 27.59 g (846.2–913.1 g). Liver fragments were processed to paraffin inclusion, and sections were stained by haematoxylin and eosin (H&E), PAS (Periodic Acid Schiff) and Perl's staining to histology, histomorphometry and density volumetric of liver structures; glycogen analysis and to detect ferric irons (Fe³⁺) respectively. The hepatosomatic index decreased between the categories (P < 0.01). The percentage of PAS‐positive hepatocytes in the nursery category was higher (P < 0.05) in relation to the growth and grow‐out categories. The hepatocytes from all fish were positive to Perl's staining. The density volumetric of liver structures did not differ among categories except to blood vessels were higher (P < 0.01) in the nursery and growth. The area (μm²) and perimeter (μm) of hepatocytes, and the area (μm²), perimeter (μm) and volume (μm³) of the nuclei from grow‐out fish were lower (P < 0.01) than those from the nursery and growth categories. Changes in morphometric characteristics of hepatocytes may result from metabolic changes associated with body growth surubins; therefore, these morphometric characteristics of liver tissue can be used as functional biomarkers for the assessment of fish health and nutrition status.     

Three‐dimensional visualization of green fluorescence protein‐labelled Edwardsiella tarda in whole Medaka larvae

The invasive fish pathogen Edwardsiella tarda is common in aquatic environments and causes the environmentally and economically destructive emphysematous putrefactive disease called edwardsiellosis. In order to understand the organism's infection pathway, medaka larvae (Oryzias latipes) were immersion‐infected with E. tarda labelled with green fluorescence protein (GFP) and then visualized in three dimensions under confocal laser microscopy and light‐sheet fluorescence microscopy. Confocal microscopy revealed GFP‐labelled E. tarda in the mouth, head, gill bridges, gill cover, skin, membrane fin, gastrointestinal tract and air bladder, and in the caudal vein, somite veins, caudal artery and caudal capillaries. Light‐sheet microscopy additionally showed GFP‐labelled E. tarda in the pharyngeal cavity, muscle of the pectoral fin and cardiac atrium and ventricle. These findings suggest that during its infection of fish, E. tarda initially adheres to, and invades, the epithelial cells of the skin, gills and gastrointestinal tract (through the pharyngeal cavity); E. tarda then enters the blood vessels to access organs, including the air bladder and heart.     

Comparative functional responses of native and high‐impacting invasive fishes: impact predictions for native prey populations

Comparative functional responses (FRs) can predict impacts of invasive species, including piscivorous fishes, via quantifying their depletion of native food resources as a function of prey density. The utility of FRs for predicting impacts on prey populations by invasive fishes of different trophic guilds was tested here by comparing the FRs of the invaders Cyprinus carpio and Carassius auratus, with three native, trophically analogous fishes, Barbus barbus, Squalius cephalus and Tinca tinca. Chironomid larvae and Gammarus pulex were used as prey items. Predictions, developed from studies on the foraging of C. carpio and C. auratus in the literature, were that the invaders would have significantly higher consumption rates for chironomids than the native fishes, but not for G. pulex. Mean consumption rates for chironomids were significantly lower for both invaders than B. barbus and S. cephalus, but were similar to T. tinca. Barbus barbus had a significantly lower consumption rate of G. pulex than both invaders, but there were no significant differences between S. cephalus, T. tinca and the invaders. All FRs were type II, with FR curves for the invaders preying upon chironomids never being significantly higher than the native fishes, contrary to predictions. For G. pulex, some significant differences were apparent between the invaders and native fishes, but again were contrary to predictions. These results indicated that when predation impacts of invasive fishes could also be a function of their population density and body sizes, these parameters should be incorporated into FR models to improve impact predictions.     

基于无人机成像高光谱影像的冬小麦LAI估测

利用无人机Cubert UHD185 Firefly成像光谱仪和ASD光谱仪获取了冬小麦挑旗期、开花期和灌浆期的成像和非成像高光谱以及LAI数据。首先,对比ASD与UHD185光谱仪数据光谱反射率,评价两者精度;然后,选取7个光谱参数,分析其与冬小麦3个生育期LAI的相关性,并使用线性回归和指数回归挑选出最佳估测参数;最后利用多元线性回归、偏最小二乘、随机森林、人工神经网络和支持向量机构建了冬小麦3个不同生育期LAI的估测模型。结果表明:UHD185光谱仪光谱反射率在红边区域与ASD光谱仪趋势一致性很高,反射率在挑旗期、开花期、灌浆期的R^2分别为0.9959、0.9990和0.9968,UHD185光谱仪数据精度较高;7种光谱参数在挑旗期、开花期、灌浆期与LAI相关性最高的参数分别是NDVI(r=0.738)、SR(r=0.819)、NDVI×SR(r=0.835);LAI-MLR为冬小麦LAI的最佳估测模型,其中开花期拟合性最好,精度最高(建模R^2=0.6788、RMSE为0.69、NRMSE为19.79%,验证R^2=0.8462、RMSE为0.47、NRMSE为16.04%)。