The effects of supplementary bacterial phytase on dietary energy and total tract amino acid digestibility when fed to young chickens

1. Four diets were offered to broiler chickens from 7 to 17 d of age; these included a phosphorus-adequate positive control (PC) (4·7 g/kg available P), a sub-optimal P negative control (NC, 2·5 g/kg available P) with (500 and 12500 FTU/kg) and without phytase. Dietary apparent metabolisable energy (AME), dietary net energy for production (NEp), the efficiency of AME retention (Kre), heat production and total tract amino acid digestibility coefficients were determined. The determination of NEp involved a comparative slaughter technique in which growing chickens were fed the experimental diets ad libitum. 2. Feed intake, weight gain and feed conversion efficiency increased significantly in a dose dependent manner in response to dietary phytase activity. Overall, the NEp of the phytase supplemented diets significantly improved by approximately 15·6% compared with the negative control, while dietary AME was unaffected. Although phytase did not affect AME, the large increase in the NEp demonstrated that dietary phytases improves energy utilisation, i.e. diverting more energy, not accounted for in the AME procedure, for production. This is largely a result of the stimulatory effect that phytase has on feed intake rather than on digestibility of the diet. 3. Overall, the diet supplemented with 12500 FTU had 6·4% significant improvement in total tract digestibility coefficients of the total amino acids compared with the negative control. With regard to individual amino acids, the impact of phytase was far more pronounced for threonine, an important component of the gastrointestinal mucin, than for other amino acids. 4. Dietary NEp was more highly correlated with performance criteria than dietary AME and seems to be a more sensitive way to evaluate broiler response to phytase supplementation.     

Effect of postmortem storage on activity of mu- and m-calpain in five bovine muscles

An in situ system involving incubation of 60- to 80-g pieces of muscle at 4 degrees C under different conditions was used to determine the effects of time of postmortem storage, of pH, and of temperature on activities of mu- and m-calpain activity in bovine skeletal muscle. Casein zymograms were used to allow measurement of calpain activity with a minimum of sample preparation and to ensure that the calpains were not exposed to ionic strengths of 100 or greater before assay of their activities. In 4 of the 5 muscles (longissimus dorsi, lumbar; longissimus dorsi, thoracic; psoas major; semimembranosus; and triceps brachii) studied, mu-calpain activity decreased nearly to zero within 48 h postmortem. Activity of m-calpain also decreased in the in situ system used but at a much slower rate. Activities of both mu- and m-calpain decreased more slowly in the triceps brachii muscle than in the other 4 muscles during postmortem storage. Although previous studies have indicated that mu-calpain but not m-calpain is proteolytically active at pH 5.8, these studies have used calpains obtained from muscle at death. Both mu- and m-calpain are proteolytically inactive if their activities are measured at pH 5.8 and after incubating the muscle pieces for 24 h at pH 5.8. Western analysis suggested that neither the large 80-kDa subunit nor the small 28-kDa subunit of m-calpain was autolyzed during postmortem storage of the muscle pieces. As has been reported previously, the 80-kDa subunit of mu-calpain was autolyzed to 78- and then to a 76-kDa polypeptide after 7 d postmortem, but the 28-kDa small subunit was not autolyzed; hence, the autolyzed mu-calpain molecule in postmortem muscle is a 76-/28-kDa molecule and not a 76-/18-kDa molecule as previously assumed. Because both subunits were present in the postmortem calpains, loss of mu-calpain activity during postmortem storage is not due to dissociation of the 2 subunits and inactivation. Although previous studies have shown that the 76-/18-kDa mu-calpain molecule is completely active proteolytically, it is possible that the 76-/28-kDa mu-calpain molecule in postmortem muscle is proteolytically inactive and that this accounts for the loss of mu-calpain activity during postmortem storage. Because neither mu- nor m-calpain is proteolytically active at pH 5.8 after being incubated at pH 5.8 for 24 h, other proteolytic systems such as the caspases may contribute to postmortem proteolysis in addition to the calpains.     

麦谷蛋白Glu-1和Glu-3位点基因等位变异对籽粒聚合体蛋白粒度分布的影响

用单向一步SDS-PAGE方法分析表明小麦品种Suneca和Cook在麦谷蛋白5个亚基位点（Glu-B1,Glu-D1,Glu-A3,Glu-B3和Glu-D3）均含不同等位基因。选用Suneca×Cook的F#-4代群体中在麦谷蛋白亚基位点均为纯合基因的60个系,研究麦谷蛋白亚基位点基因等位变异对小麦籽粒聚合体蛋白粒度大小分布（用SE-HPLC测定）的影响。结果表明：Glu-B1位点等位基因i和u,Glu-D1位点等位基因d和a,对籽粒聚合体蛋白粒度大小相对分布（用不溶聚合体蛋白占总聚合体蛋白含量的百分数表示,即UPP%）的效应存在显著差异,含Glu-Blu基因和Glu-D1d基因的系分别比含Glu-Bli和Glu-D1a的系有较大的UPP%;同样,Glu-A3位点等位基因d和b,Glu-B3位点等位基因h和b,对籽粒聚合体蛋白粒度大小相对分布的效应显著不同,Glu-A3b基因和Glu-B3b基因与较大的UPP%有关。Glu-D3位点等位基因e和b对UPP%无显著影响。Glu-1位点和Glu-3位点间对籽粒聚合体蛋白大小相对分布的影响存在累加和互作效应。     

小麦谷蛋白聚合体粒度分布与面粉揉面特性关系的研究

 选用在谷蛋白 Glu- 1和 Glu- 3的 5个位点 (除 Glu- A1位点外 )上均带有不同等位基因的小麦品种 Suneca和 Cook的杂交 F4 代群体中谷蛋白各亚基位点均为纯合基因的 60个系 ,测定基因型不同的系间谷蛋白聚合体粒度分布和面粉揉面特性的变异 ,研究小麦谷蛋白聚合体粒度分布与面粉揉面特性的关系。结果表明 ,不同的谷蛋白基因型 ,其谷蛋白聚合体粒度大小相对分布 (即 U PP% )和面团形成时间 (即揉面曲线图峰值的和面时间 ,PTM)均有显著差异。面粉的揉面曲线形状与其 U PP%值密切相关 ,U PP%与 PTM呈极显著正相关 ,与揉面曲线图峰高 ( PHM)呈显著负相关 ;与面粉蛋白质含量 ( FP% )相比 ,U PP%对 PTM和 PHM的影响更大些 ,可作为育种早代品质性状选择的一个指标     

小麦抗赤霉病菌毒素的生化机制探讨：II.赤霉病菌粗毒素对小麦幼苗活…

研究了在赤霉病菌粗毒素作用下，西农６７（抗病品种）和８４３３（感病品种）小麦幼苗ＭＤＡ含量，ＳＯＤ，ＰＯＤ活性及其同工酶变化。结果表明，西农６７小麦幼苗在粗毒作用２４ｈ内ＳＯＤ和ＰＯＤ活性迅速增加，随着毒素作用时间的延长，这两种酶能够维持高的活性水平，其ＭＤＡ累积缓慢，累积量少，感病品种８４３３在粗毒作用下，ＳＯＤ和ＰＯＤ活性的均呈先增加后降低的趋势，且两种酶活性增加幅度均小于西农６７，其ＭＤＡ则     

陕西省小麦资源主要加工品质特性及其相关性

本研究对陕西省１３１个农家小麦品种和１４８个育成品种的三个重要加工品质性状即籽粒硬度、粗蛋白质含量和全麦粉ＳＤＳ淀淀值进行了测定。发现陕西省农家品种硬度较大而沉淀值偏低；育成品种硬度较大而沉淀值偏高。     

水分胁迫对小麦幼苗抗氧化物质含量的影响及其与抗旱性的关系

水分胁迫下,抗旱性强的小麦品种陕合6号在一定干旱限度内能维持其叶片抗氧化物质GSH和Vc含量水平稳定,从而保护了细胞,其膜脂过氧化水平较低,膜受伤害较轻;而对干旱敏感的品种郑引1号在轻度干旱条件下叶片GSH和Vc含量就显著降低,其膜脂过氧化水平较高,质膜透性增加较大,膜损伤严重。在正常生长条件下,陕合6号Vc和GSH含量高于郑引1号。因此,GSH和Vc在作物抗旱性方面有积极作用。     

Synthesis and antifungal action of new tricyclazole analogues

Melanins are very important pigments for the survival and longevity of fungi, so their biosynthesis inhibition is a new biochemical target aiming at the discovery of selective fungicides. In this work is described the synthesis of new pyrazolo-thiazolo-triazole compounds, analogues of tricyclazole (a commercial antifungal product that acts by inhibiting melanin synthesis), and their biological activity was studied on some dermatophytes and phytopathogens. The compounds poorly inhibited the growth and pigmentation of fungi tested and were less efficient than tricyclazole. Electron microscopy on Botrytis cinerea showed that treatment with the most active compound caused abnormally thickened and stratified walls in fungi, whose ultrastructure was, in contrast, generally normal. The fungus treated with tricyclazole, on the other hand, appeared to be drastically altered, so as to become completely disorganized. These results suggest that the new azole compounds employ an action mechanism similar to that of other azoles, but dissimilar to that of tricyclazole.     

小麦谷蛋白亚基的等位基因变异及其对面团和面时间的影响

利用澳大利亚不同谷蛋白亚基组成的小麦配制的４个组合的Ｆ４代材料，研究了小麦高低分子量谷蛋白亚基的等位基因变异及其对面团和面时间的影响，结果表明由Ｇｌｕ－Ｄ１位点内等位基因ｄ控制的５＋１０亚基和由Ｇｌｕ－Ｂ１位点内等位基因ｉ控制的１７＋１８亚基，分别比其相应的等位基因ａ控制的２＋１２和等位基因ｅ控制的２０ｘ＋２０ｙ亚基可以显著地提高面团和面时间；Ｇｌｕ－３位点内同源染色等位基因之间对面时间具有加性和