Immune responses and enhanced disease resistance in Chinese drum, Miichthys miiuy (Basilewsky), after oral administration of live or dead cells of Clostridium butyrium CB2

Clostridium butyrium CB2 isolated from chickens was tested as a potential fish probiotic in the Chinese drum, Miichthys miiuy . Fish were fed live (CB), dead CB2 (D-CB) cells (10⁸ cells g⁻¹) or spent culture supernatant (SCS), for 30 days and challenged with Vibrio anguillarum or Aeromonas hydrophila . Survival was higher in both the CB and the CB-D fed groups, but the SCS group was not significantly different from the control. After feeding live or dead CB2 cells, there was increase in phagocytic activity of the head kidney macrophages, the lysozyme activity of serum and gut mucosa and immunoglobulin (Ig) level. The SCS group showed no obvious change in immune parameters. The results suggest that live or dead Clostridium butyrium CB2 has an immunomodulatory effect on fish.     

Effects of extruded and pelleted diets with differing lipid levels on growth,nutrient retention and serum biochemical indices of tilapia (Oreochromis aureus × Tilapia nilotica)

This study was conducted to evaluate the effects of extruded diets and pelleted diets with varying dietary lipid levels on growth performance and nutrient utilization of tilapia. Six diets, containing three levels of lipid at 40, 60 or 80 g kg^?1 (with the supplemental lipid of 0, 20 or 40 g kg^?1, respectively), were prepared by extruding or pelleting and then fed to tilapia juveniles (8.0 ± 0.1 g) in cages (in indoor pools) for 8 weeks. The results indicated that the fish that were fed the diet with 60 g kg^?1 of lipid had a higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), lipid retention (LRE), energy retention (ERE), apparent protein digestibility, apparent dry matter digestibility and a lower feed conversion ratio (FCR) than those fed the diet with 40 g kg^?1 lipid in both the extruded diet and pelleted diet (P < 0.05). As the dietary lipid level increased from 60 to 80 g kg^?1, these parameters were not further improved, even digestibilities of the crude protein and dry matter decreased (P < 0.05). With the dietary lipid level increased, whole‐body lipid content significantly increased (P < 0.05), serum aspartate aminotransferase, alkaline phosphatase, total cholesterol and low‐density lipoprotein cholesterol (LDL‐C) tended to increase (P > 0.05), whereas whole‐body protein content, serum triglyceride (TG), high‐density lipoprotein cholesterol (HDL‐C) and HDL‐C/LDL‐C tended to decrease (P > 0.05). Fish fed with the extruded diets had a higher WG, SGR, hepatosomatic index (HSI), PER, protein retention (PRE), LRE, ERE, TG, apparent digestibility of protein and dry matter, as well as a lower FCR, than those fed with the pelleted diets at the same dietary lipid level (P < 0.05). These results suggested that tilapia fed with the extruded diets had a better growth and higher nutrient utilization than fish fed with the pelleted diets, when dietary lipid level ranged from 40 to 80 g kg^?1 and at dietary crude protein level was 280 g kg^?1. The optimum dietary lipid level was 60 g kg^?1 in both the pelleted and extruded diets, and extrusion did not affect dietary lipid requirement of the tilapia.     

孝感市农业环境污染与治理初探

大量使用化肥、农药、农膜及生产、生活产生的废水污染了农业环境,影响农作物正常生长,降低了品质.治理污染可采取充分开发利用农作物秸秆和动物粪便、科学施肥、综合防治病虫害、宣传普及科学技术、强化农业执法等措施,以达到农业可持续发展和人与自然和谐共存的目的.     

Seasonal Changes of Mineral Nutrients in Fruit and Leaves of ‘Newhall’ and ‘Skagg's Bonanza’ Navel Oranges

In southern Jiangxi province of China, ‘Newhall’(Citrus sinensis Osbeck) navel orange presented a conspicuous symptom of boron (B) deficiency in mature leaves, whereas B deficiency symptoms were not manifested on ‘Skagg's Bonanza’(C. sinensis Osbeck) navel orange. In this study, changes in concentrations of B, calcium (Ca), potassium (K), magnesium (Mg), manganese (Mn), and zinc (Zn) were comparatively investigated in the structural parts of the fruit (rind and pulp) and leaves (old leaves from last season and spring-flush leaves from current year) of ‘Newhall’ and ‘Skagg's Bonanza’ navel orange during the growing season. Two peaks of B concentrations were observed in the rind of the two cultivars during fruitlet growth and fruit enlargement, respectively. Boron concentrations were relatively high in the rind during fruitlet growth, and then decreased in both rind and pulp, whereas, during middle and late fruit enlargement significant increases were found for B in both rind and pulp of the two cultivars. Boron concentrations in old leaves of ‘Newhall’ decreased progressively and remained relatively low, whereas that of ‘Skagg's Bonanza’ was relatively high and changed slightly as the season progresses. Both Ca and K concentrations were above the critical threshold values, while their dynamics were reverse to that of B in fruit and leaves during certain times. Old leaf Mg concentrations of samples at 140 days after full bloom from the two cultivars and spring-flush leaves from ‘Newhall’ were below the threshold limit for sufficiency. In addition, Mg in old leaves was much lower from ‘Newhall’ than from ‘Skagg's Bonanza’. Spring-flush leaf concentrations of Mn and Zn and Mn concentrations in old leaves from ‘Newhall’ were relatively lacking during middle and late season, which accelerated the occurrence of B deficiency symptoms on mature leaves of ‘Newhall.’     

Impacts of soil erosion on organic carbon and nutrient dynamics in an alpine grassland soil

The impact of soil erosion on the nutrient dynamics in alpine grassland soils is still an essential problem. Selecting a grass-covered hillslope in eastern Tibet Plateau, the cesium-137 (¹³⁷Cs) technique was used to determine the impacts of soil erosion on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK). The ¹³⁷Cs data revealed that there were distinct soil redistribution patterns in different hillslope positions because of the influences of slope runoff, plant coverage and grazing activity. For the upper slope, soil erosion first decreased downward, followed by soil deposition in its lower part. In contrast, for middle and toe slopes, there was an increasing soil erosion along a downslope transect. Across the lower slope, soil erosion showed an irregular variation. Influenced by the selective transport of water erosion, SOC, TN and TP storage decreased with increasing soil erosion in upper, middle and toe slopes. In contrast, SOC, TN and TP storage varied little with soil erosion in the lower slope. On the whole hillslope, TK storage also varied little with soil erosion due to the large amount of potassium elements derived from soil parent materials. Particularly noteworthy was the greatest storage of SOC, TN and TP in the lower slope where most obvious net soil erosion occurred, which is closely related to the humus accumulation combined with gravel separation as well as weathering and pedogenesis of parent rocks induced by soil freeze-thaw.     

Amino acids in grassland soils: Climatic effects on concentrations and chirality

The response of soil organic nitrogen (SON) dynamics to climate may partly be deduced from changes in the concentration and origin of the major N constituents in soil, such as amino acids. In this study, we determined the enantiomers of bound amino acids in 18 native grassland soils (0–10 cm) that were sampled along a transect from central Saskatchewan, Canada, to Southern Texas, USA. Mean annual temperature (MAT) ranged from 0.9 to 23.4 °C and mean annual precipitation (MAP) from 300 to 1308 mm. d-alanine and d-glutamic acid served as markers for the bacterial origin of SON. The d-content of lysine, phenylalanine, and aspartic acid indicated an ageing of the respective SON forms. Deuterium labeling was applied to account for hydrolysis-induced racemization reactions. We found that the concentration of the bacterial biomarkers was weakly but significantly parabolically related to MAT, as previously reported for microbial-derived amino sugars. The age markers d-lysine, d-phenylalanine, and d-aspartic acid comprised 2–15% of the respective l-form. The presence of these compounds demonstrated that the structures that contained these d-enantiomers had survived microbial attack, i.e., these hydrolyzable SON forms were conserved in soil despite a living environment. First estimates indicate that the mean residence time of the lysine-containing organic matter forms extend beyond a century. Within this time-scale we did not find that climate significantly affects the degree of ageing of SON constituents in the studied topsoils.     

Correlation analysis of mineral element contents and quality traits in milled rice (Oryza stavia L.)

The relationships among potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) contents in milled rice (Oryza stavia L.) of 274 genotypes and the relationships between these mineral element contents and other rice quality traits including 3 cooking quality traits, 17 amino acid contents, and protein content were investigated. The results showed that there were significant correlations among most of mineral element contents. Mg, Fe, and Mn contents were significantly correlated with most of the other mineral element contents, while Cu content had significantly negative associations with the K and Mg contents of rice. The relationships between mineral element contents and cooking quality traits showed that gel consistency (GC) was significantly correlated with K, Cu, and Mn contents of rice. Amylose content (AC) was significantly associated with K, Na, Mg, Cu, and Mn contents. The alkali spreading value (ASV) had closely positive relationships with Ca, Mg, and Mn contents. In addition, 8 mineral element contents had obvious correlations with different amino acid contents. Mg, Ca, and Zn contents were significantly correlated with most of the 17 amino acid contents, but Na content did not correlate with amino acid contents except aspartic acid of rice. Furthermore, significant associations were found between protein content and Na, Mg, Zn, Cu, or Mn content. Six principal components were extracted to explain 84.50% of the total variances and contained the information provided by the original 29 variables according to the principal component analysis.     

The genetic relationship between popping expansion volume and two yield components in popcorn using unconditional and conditional QTL analysis

Popping expansion volume (PEV) is the most important quality trait in popcorn, while its germplasm is inferior to normal dent/flint corn in yield. In this study, 259 F_2:3 families, developed from the cross between a dent corn inbred Dan232 and a popcorn inbred N04, were evaluated for their PEV, grain weight per plant (GWP) and 100-grain weight (100 GW) in two environments. The genetic relationship between PEV and GWP, and 100 GW on individual gene loci were evaluated using unconditional and conditional QTL mapping methods. In total, five, one and three unconditional QTL were identified for PEV, GWP, and 100 GW, respectively. The positive alleles of all QTL for PEV were from N04, while positive alleles of all QTL for GWP and 100 GW were from Dan232. In conditional mapping, one and two QTL failed to be detected, and all four additional QTL were detected. Nevertheless, three QTL were identified, which controlled PEV independently from GWP/100 GW. They seemed to be potential candidates in popcorn breeding to increase PEV without decreasing GWP/100 GW. The results suggested that for significantly correlated traits, the conditional QTL mapping method could be used to dissect the genetic interrelationship between traits at the level of individual QTL, as well as reveal additional QTL that were undetectable by unconditional mapping.