Sucrose efflux mediated by SWEET proteins as a key step for phloem transport

Plants transport fixed carbon predominantly as sucrose, which is produced in mesophyll cells and imported into phloem cells for translocation throughout the plant. It is not known how sucrose migrates from sites of synthesis in the mesophyll to the phloem, or which cells mediate efflux into the apoplasm as a prerequisite for phloem loading by the SUT sucrose-H(+) (proton) cotransporters. Using optical sucrose sensors, we identified a subfamily of SWEET sucrose efflux transporters. AtSWEET11 and 12 localize to the plasma membrane of the phloem. Mutant plants carrying insertions in AtSWEET11 and 12 are defective in phloem loading, thus revealing a two-step mechanism of SWEET-mediated export from parenchyma cells feeding H(+)-coupled import into the sieve element-companion cell complex. We discuss how restriction of intercellular transport to the interface of adjacent phloem cells may be an effective mechanism to limit the availability of photosynthetic carbon in the leaf apoplasm in order to prevent pathogen infections.     

农村养老新出路——农村社区养老模式的提出与分析

建立和谐社会执政目标的提出引发了我们对于农村老人安老养老问题的关注。从农村社区养老模式提出的背景出发,具体分析了社区养老这一模式在农村开展的合理性和先进性,进而提出了几点推广、发展农村社区养老的建议。     

传统发酵食品中功能成分的研究进展

传统发酵食品具有悠久的历史,且种类繁多,因其独特的风味和功能而深受大众欢迎.该文就传统发酵食品的功能成分及其作用,以及传统发酵行业所面临的问题作一综述,并对其发展前景进行了展望.     

简帛资料所见汉代猪文化

汉简资料记载,汉初为了保护农业发展,律令禁止放牧养猪的养殖方式,这或许促使了圈养方式的兴起。两汉时期既有民间个体饲养也有政府集体养殖两种方式,边塞的戍守系统继续沿用此种模式。汉代人们对猪的认知度颇高,无论是在朝廷赏赐、医疗、饮食,还是在地名、人名中都广泛应用,猪文化影响深远。此外,西北汉简中的“肉价”可能就是猪肉价格的简称,这为深化汉代社会生活史研究提供了重要参考。     

新农村示范镇建设和实践教学基地有机结合的创新研究——农村区域发展专业实践教学新模式

从新农村示范镇建设的实际要求出发,根据农村区域发展专业培养目标,提出将新农村建设示范镇作为实践教学基地,从专业实践教学活动的开展和新农村示范镇的建设两个方面进行分析探讨,提出促进共建基地顺利发展的措施。     

多种杀菌剂对苹果斑点落叶病的田间防治效果

为筛选对苹果斑点落叶病具有良好防治效果的杀菌剂,以‘首红’苹果为材料,对苹果斑点落叶病进行14种药剂的田间药效试验。结果表明：10%苯醚甲环唑WG、430 g/L戊唑醇SC和70%丙森锌WP防治苹果斑点落叶病的效果最好,明显高于其他药剂。2013和2014年春梢期的防效分别为81.65%、81.24%、79.97%和82.36%、86.14%、83.42%,秋梢期防效分别为76.22%、77.83%、73.84%和81.80%、82.18%、75.58%。其次为50%克菌丹WP、50%嘧菌环胺WP和10%多抗霉素WP,在防治苹果斑点落叶病上也表现出较好的效果。春梢期防效分别为78.35%、78.17%、77.34%和81.89%、82.03%、81.88%,秋梢期的防效分别为73.47%、72.58%、74.45%和78.73%、74.69%、77.44%。80%代森锰锌WP对苹果斑点落叶病的防治效果较差,均低于其他药剂。方差分析表明,三唑类杀菌剂苯醚甲环唑与保护性杀菌剂代森锰锌处理间的防效差异在2年的试验结果中均显著。     

红掌的组织培养和快速繁殖

对红掌（Anthuriun andraeanum Lind)的组织培养和快速繁殖技术进行了研究。采用叶片，叶柄和茎段作初代诱导，结果发现，茎段的诱导效果最好。葡萄糖作碳源的效果优于蔗糖，1/2MS作基本培养基优于MS，红掌试管苗在MS BA1.0mg/L KT1.0mg/L的培养基上生长增殖倍数最高。     

我国特种养殖业发展趋势及其措施

对我国特种养殖业的发展进行了系统地概括 ,指出了养殖业中存在的一些问题 ,并提出了养殖业发展的措施。     

早春地膜小拱棚架豆无公害栽培技术

地膜覆盖栽培技术一直是蔬菜栽培中的一种主要形式。用地膜直接覆盖地表,秧苗出土后若扒孔不及时,常造成农膜烫苗现象,而扒孔放苗后,又易受倒春寒的危害。为解决上述矛盾,并实现最大限度提早栽培,我们经几年的试验示范,探索出适于冀北地区采用的地膜覆盖栽培的一种新途径,即作物播种或定植后,直接用竹片起拱,拱上覆膜,两侧用土压实,为作物前期生长创造良好的温光条件。     

Effects of ambient temperature on growth performance and carcass traits of male growing White Pekin ducks

ABSTRACT

1. An experiment was conducted to investigate the effects of ambient temperature on growth performance and carcass traits in male growing Pekin ducks from 14 to 42 d of age in order to establish their optimal temperature requirements.

2. A total of 216 14 d old male White Pekin ducks were allocated randomly to six environmentally controlled chambers with ambient temperature set at 20°C, 22°C, 24°C, 26°C, 28°C, and 30°C from 14 to 42 d of age, respectively.

3. As ambient temperature increased from 20°C to 30°C, the body weight and weight gain decreased linearly or quadratically (P < 0.05) and was accompanied by linearly decreasing feed intake (P < 0.05). According to broken-line regression, the upper critical level of ambient temperature during the growing period for body weight, weight gain, and feed conversion ratio were 27.4°C, 27.4°C, and 26.0°C, respectively.

4. The weight of breast meat, leg meat, and abdominal fat decreased linearly or quadratically as ambient temperature increased and declined to a minimum when the temperature increased to 30°C (P < 0.05). The percentage of breast meat and abdominal fat showed a linear or quadratic decreasing response to increasing temperature, but leg meat percentage increased as temperature increased and reached maximum at 30°C (P < 0.05). According to broken-line regression, the upper critical ambient temperatures during the growing period for breast meat weight and percentage were 25.5°C and 25.6°C, respectively.

5. It was concluded that both growth performance and breast meat of growing ducks were sensitive to increasing ambient temperature and this should be kept below the upper critical temperature during the growing period in order to optimise growth performance and carcass traits at market age.