乳酸菌固态混合发酵研究

以玉米粉、豆粕、麦麸为基质,以保加利亚乳杆菌、嗜酸乳杆菌、嗜热链球菌为发酵菌种,采用固态发酵技术,以活菌数为指标,通过单因素和L9(34)正交试验确定了三种菌混合发酵的最佳条件,并对其发酵产物的常规营养成分进行分析测定。结果表明:固态基质中玉米粉:豆粕:麦麸=1:1:1、培养基初始含水量80%p、H值6.3、接种量为10%、三种菌接种比例为1:1:1、发酵温度40℃时的发酵效果最好。在此条件下,保加利亚乳杆菌数为3.0×109 CFU/g,嗜酸乳杆菌数为4.6×109 CFU/g,嗜热链球菌数为5.8×109 CFU/g,发酵产物粗蛋白质、粗脂肪和氨基酸态氮含量分别是发酵前的1.16、1.12和6.94倍。为开发一种新型生物饲料打下基础。     

一株产细菌素植物乳酸杆菌YJG发酵液对蛋鸡生产性能以及蛋品质的影响

研究一株植物乳酸杆菌细菌素对蛋鸡生产性能和蛋品质的影响。选用232日龄产蛋率和体重相近、健康状况良好的海兰灰蛋鸡225只,试验期为34 d。结果表明:日粮中添加500 AU/kg植物乳酸杆菌细菌素对蛋鸡的产蛋率和平均蛋重的提升幅度最大,各细菌素添加组对降低料蛋比均有显著的效果(P<0.05),对平均日采食量、蛋黄色泽、哈氏单位、蛋壳强度和蛋形指数都有不同程度的改善。植物乳酸杆菌细菌素可以明显改善蛋鸡生产性能和蛋品质,可以为饲料添加剂的研发提供新的思路。     

Maternal Administration of GHRP-6-loaded PLGA-PEG-PLGA Thermosensitive Hydrogel Increases Growth and Vitality of Piglets

Both growth hormone-releasing peptide 6 (GHRP-6) and growth hormone-releasing hormone (GHRH) have potent GH-releasing activity in animals.We have previously demonstrated that the administration of a plasmid encoding the GHRH gene to pregnant mice and pig augmented long-term growth in first generation progeny,and that the administration of GHRP-6 results in growth augmentation in mice and rabbits.However,it has not yet been reported if GHRP-6 induces intergenerational growth effects in pigs.Ploy lactic-co-glycolic acid (PLGA) microsphere adsorption of treatment proteins enhances gene expression,genetic immunization and the ability to protect plasmid DNA and peptides from degradation.The current study was conducted to determine the growth performance of piglets born to gilts treated with GHRP-6 incorporated into thermosensitive PLGA-PEG-PLGA triblock copolymers.Gilts were injected intra-muscularly once at day 85 of gestation with 30 mg of GHRP-6-loaded thermosensitive PLGA-PEG-PLGA triblock copolymers.Piglets were weighed periodically between birth and 28 days.Mean body weights of piglets born to GHRP-6-treated gilts were 6.58％ to 18.89％ (P ＜ 0.05 ) greater than those of piglets born to control gilts.This study confirms that enhanced maternal GHRP-6 mediated by thermosensitive PLGA-PEG-PLGA can augment growth of piglets.     

Serological Survey of Toxoplasma gondii Infection in the Domestic Goose (Anser domestica) in Southern China

In the present study, the antibodies to Toxoplasma gondii in 191 farm‐bred and 83 house‐bred geese (Anser domestica) were assessed for the prevalence of T. gondii infection in southern China with the modified agglutination test. Antibodies to T. gondii (MAT ≥ 1 : 5) were found in 27 (14.14%) of farm‐bred geese and 14 (16.87%) of house‐bred geese. Geese infected with T. gondii may be a source of T. gondii infection for humans and cats.     

Improving ‘Bing’ sweet cherry fruit quality with plant growth regulators

Final fruit diameter is the prime determinant of sweet cherry fruit value. Previous research has shown that mesocarp cell size accounts predominantly for variability in final fruit size, within a genotype. Our research program evaluated the potential to improve sweet cherry fruit size/weight with growth regulators to affect cell division and/or cell expansion stages. In the current study we screened 8 plant growth regulators (PGRs), including cytokinins, gibberellins, and auxins, and their combinations for their ability to increase ‘Bing’ fruit weight. Each PGR was mixed in lanolin paste and applied to fruit pedicels at 9 or 30 days after full bloom (DAFB), to coincide with estimated peak in cell division and cell expansion activity, respectively. Several cytokinins applied 30 DAFB improved fruit weight significantly (ca. +15%) with N-(2-Chloro-4-pyridyl)-N′-phenylurea (CPPU) and 6-(3-hydroxybenzylamino) purine (mt-Topolin) at 100 mg l⁻¹ being the most effective. Gibberellins, applied alone, improved fruit size and delayed fruit maturation and exocarp coloration. GA₃ at 200 mg l⁻¹ applied at 9 DAFB was the most effective and improved final fruit weight by 15%. Fifty-six percent of the fruit from this treatment were ≥9 g compared to 15% of similar weight fruit from untreated limbs. Both GA₃ and GA_4/7 treatments applied 9 DAFB increased fruit radial expansion. 4-Chlorophenoxyacetic acid, a synthetic auxin, also stimulated higher fruit growth rates at stage I and stage II, and fruit color development, but did not improve final fruit size.     

Effect of different drip irrigation methods and fertilization on growth,physiology and water use of young apple tree

A pot experiment was conducted to investigate the effect of three drip irrigation methods (i.e. conventional drip irrigation (CDI), both sides of the root-zone irrigated with full watering, alternate drip irrigation (ADI), both sides of the root-zone irrigated alternatively with half of the full watering, and fixed drip irrigation (FDI), only one side of the root-zone irrigated with half of the full watering) on growth, physiology, root hydraulic conductance and water use of young apple tree under different nitrogen (N) or phosphorus (P) fertilization (i.e. CK (no fertilization), N₁ (0.2 g N/kg), N₂ (0.4 g N/kg), P₁ (0.2 g P₂O₅/kg) and P₂ (0.4 g P₂O₅/kg)). Results show that compared to CDI, ADI and FDI reduced mean root dry mass, daily transpiration, root hydraulic conductance (K_r), leaf photosynthesis rate, transpiration rate and stomatal conductance of young apple tree by 6.9 and 27.7, 29.3 and 45.0, 6.8 and 37.9, 2.5 and 4.8, 32.6 and 33.0, 22.1 and 22.3%, but increased leaf water use efficiency (WUE) by 31.3 and 29.8%, respectively when they saved irrigation water by 50%. Compared to the CK, N or P fertilization significantly increased K_r, and K_r was increased with the increased N or P fertilization level. There were parabolic correlations between K_r and root dry mass, daily transpiration and stomatal conductance. Our results indicate that ADI reduced transpiration rate significantly, but it did not reduce photosynthesis rate and K_r significantly, thus alternate drip irrigation improved WUE and the regulation ability of water balance in plants.     

Exploitation of SSR,SRAP and CAPS-SNP markers for genetic diversity of Citrus germplasm collection

The present study was to assess informativeness and efficiency of three different molecular markers for genetic diversity among 24 Citrus and its relative species. Sixty one SSR, 33 SRAP and 24 CAPS-SNP markers were used to evaluate the level of polymorphism and discriminating capacity. A total of 596, 656 and 135 polymorphic amplicons were observed in SSR, SRAP and CAPS-SNP markers with average polymorphism information content (PIC) of 0.97, 0.98 and 0.89, respectively. High levels of polymorphism were recorded for SSR and SRAP compared with CAPS-SNP markers. The highest correlations (r = 0.930) were obtained between SSR and SRAP markers, whereas SSR and CAPS-SNP were poorly correlated (r = 0.833). Cluster analysis was performed to construct dendrograms using UPGMA. And the dendrogram from SSR data was most congruent with the general dendrogram. These findings provide basis for future efficient use of these molecular markers in the genetic analysis of Citrus and its relatives.     

Starch granule size variation and relationship with tuber dry matter content in heritage potato varieties

Heritage potato varieties in Canada are historic old varieties collected from Canada and various countries before the formal establishment of the Canadian plant variety registration system and may be a valuable gene resource for beneficial traits in potato breeding and bioproducts development. Greater evaluation is the key for the enhanced use of these materials. It is unknown how much variation of starch granules occurs among Canadian heritage potato varieties. We analyzed the starch granule size of 14 potato heritage varieties held in the Canadian Plant Gene Resources collection over 2 years using a squeezed juice and microscopic method recently developed at the Potato Research Centre. The varieties demonstrated considerable variation in starch granule size and shape. The granules showed average lengths ranging from 18 μm in the variety Congo to 32 μm in ‘Russet Burbank’. The largest single granule measured from 64 μm in ‘Congo’ to 91 μm in ‘Crotte d’Ours.’ The granule sizes of the varieties showed a very high correlation (r = 0.975, P < 0.0001) between years. This high reproducibility suggests the existence of genetic factors in determining starch granule size. We also found that the starch granule size is positively correlated with tuber dry matter (in terms of specific gravity) in these heritage potatoes. The results demonstrated reproducible genotypic variation for starch granule size and shape in tubers with a significant correlation to tuber dry matter in these heritage potato varieties, and offers the possibility for and agronomic relevance of genetic modification of starch granules through selective breeding.