NADP-malic enzyme and glutathione reductase contribute to glutathione regeneration in Fragaria vesca fruit treated with protective high CO2 concentrations

Treatment of harvested strawberries (Fragaria vesca L. Mara des Bois) with high concentrations of CO₂ is an effective means of limiting fungal decay and avoiding disorders caused by low temperature storage. In the present study, we investigated the role of NADP-ME gene expression and activity in lowering malic acid contents and in the provision of NADPH required for the regeneration of the reduced form of glutathione (GSH). We also measured glutathione reductase (GR: EC 1.6.4.2) activity in strawberries treated with different high CO₂ concentrations (0, 20 and 40% for 3 days) during storage at 0 °C. A decrease in malic acid content in fruit exposed to 20% CO₂ was primarily mediated by the stimulation of NADP-ME activity, rather than associated with changes in the expression of cytosolic NADP-ME genes. Moreover, malic acid decarboxylation was associated with a marked increase in GR activity, which may account for the increased levels of glutathione in fruit following exposure to 20% CO₂. This chain of events was not observed in untreated fruit stored in air or in fruit treated with 40% CO₂, suggesting that the unique cellular redox status of 20% CO₂-treated fruit plays an important role in detoxification and protection from damage during storage. Based on these findings, we propose that NADP-ME activation in fruit exposed to 20% CO₂ provides NADPH for glutathione regeneration by GR, thereby conferring protection against the cellular damage caused by low temperatures or excessive high CO₂ levels.     

STS标记在扬麦158×淮麦18F_4群体中的应用及其与PPO活性的关系

小麦籽粒中的多酚氧化酶活性是导致酶促褐变的主要因素.选育低多酚氧化酶活性的品种是改良面制食品外观品质的重要途径之一.本研究利用位于小麦2A和2D染色体上PPO基因分子标记PPO18和STS01,对扬麦158×淮麦18组合的300个F4代分离株系进行PCR扩增,说明不同带型与PPO活性的相关性.结果表明用PP018扩增的300个分离株系中有59个扩增出876 bp(2aaa型)的目标片段,其活性均值为82.01;46个同时扩增出685 bp和876 bp的目标片段(2Aab型)其活性均值为163.41;其余195个扩增出685 bp的目标片段(2Abb型)其活性均值为233.73.方差分析表明三者的PPO活性差异达到极显著水平,其中基因型为2Aaa型的PPO活性值明显低于2Abb型;PPO18在本试验群体中对PPO活性的决定系数为66.61%;用STS01扩增的300个株系中都扩增出了560bp的片段,群体间没有差异.文中说明了两对引物在该群体中的效应及其与PPO活性的关系.     

In vitro metabolism of ovarian steroids by bovine whole blood and plasma

Experiments were conducted to evaluate the effects of time and temperature on the potential of bovine whole blood (WB) or plasma (PL) to metabolize the ovarian steroids progesterone, estradiol-17β and testosterone. During a radioimmunoassay study (Experiment 1), we observed a temperature and time-dependent reduction (P<0.001) of plasma progesterone concentrations in samples incubated as WB at 5, 15, 25, or 35C for up to 48 hr. Most notable was the observation that 27% of progesterone present in controls was lost when WB was incubated at 5C for 48 hr and a 17% reduction was observed when PL samples were incubated at 35C for 48 hr. Immunoreactive estradiol-17β concentrations (Experiment 2) in PL and WB incubates were not affected by time or temperature. However, immunoreactive testosterone concentrations increased more than 3-fold by 48 hr in WB incubates held at 35C. To examine the latter observation further, ³H-progesteone was incubated with WB at 35C, followed by extraction and thin-layer chromatography (Experiment 3). Results generally supported RIA findings and revealed the presence of significant 17α-hydroxylase, 17–20 lyase and aromatase activity. Heretofore this has not been considered to occur outside major steroid metabolizing organs.     

Tomato yield, biomass accumulation, root distribution and irrigation water use efficiency on a sandy soil, as affected by nitrogen rate and irrigation scheduling

Florida is the largest producer of fresh-market tomatoes in the United States. Production areas are typically intensively managed with high inputs of fertilizer and irrigation. The objectives of this 3-year field study were to evaluate the interaction between N-fertilizer rates and irrigation scheduling on yield, irrigation water use efficiency (iWUE) and root distribution of tomato cultivated in a plastic mulched/drip irrigated production systems. Experimental treatments included three irrigation scheduling regimes and three N-rates (176, 220 and 230 kg ha⁻¹). Irrigation treatments included were: (1) SUR (surface drip irrigation) both irrigation and fertigation line placed right underneath the plastic mulch; (2) SDI (subsurface drip irrigation) where the irrigation line was placed 0.15 m below the fertigation line which was located on top of the bed; and (3) TIME (conventional control) with irrigation and fertigation lines placed as in SUR and irrigation being applied once a day. Except for the “TIME” treatment all irrigation treatments were controlled by soil moisture sensor (SMS)-based irrigation set at 10% volumetric water content which was allotted five irrigation windows daily and bypassed events if the soil water content exceeded the established threshold. Average marketable fruit yields were 28, 56 and 79 Mg ha⁻¹ for years 1-3, respectively. The SUR treatment required 15-51% less irrigation water when compared to TIME treatments, while the reductions in irrigation water use for SDI were 7-29%. Tomato yield was 11-80% higher for the SUR and SDI treatments than TIME where as N-rate did not affect yield. Root concentration was greatest in the vicinity of the irrigation and fertigation drip lines for all irrigation treatments. At the beginning of reproductive phase about 70-75% of the total root length density (RLD) was concentrated in the 0-15 cm soil layer while 15-20% of the roots were found in the 15-30 cm layer. Corresponding RLD distribution values during the reproductive phase were 68% and 22%, respectively. Root distribution in the soil profile thus appears to be mainly driven by development stage, soil moisture and nutrient availability. It is concluded that use of SDI and SMS-based systems consistently increased tomato yields while greatly improving irrigation water use efficiency and thereby reduced both irrigation water use and potential N leaching.     

鄂通两头乌与通城猪肌肉中重要营养风味物质的比较

为比较鄂通两头乌与通城猪肌肉营养和风味物质的差异,分别对两群体背最长肌中氨基酸、脂肪酸、肌苷酸和硫胺素4类营养风味物质进行测定和分析。结果显示:通城猪肌肉氨基酸种类齐全,16种氨基酸总量为(19.42±1.31) g/100 g,必需氨基酸含量为(8.47±0.98) g/100 g,主要鲜味氨基酸含量为(6.80±0.46) g/100 g;脂肪酸种类丰富、营养风味价值高,饱和脂肪酸含量为43.04%±1.84%,不饱和脂肪酸含量为56.96%±1.84%,其中单不饱和脂肪酸含量为47.47%±2.63%,多不饱和脂肪酸含量为9.50%±2.50%,亚油酸含量达8.93%±2.36%。而其风味物质硫胺素和肌苷酸的值分别为(0.23±0.05) mg/100 g、(3.23±0.67) mg/g。鄂通两头乌肌肉中多不饱和脂肪酸(12.08%±4.72%)、亚油酸(11.36%±4.44%)和硫胺素((0.23±0.05) mg/100 g)显著或极显著高于通城猪,上述其他性状与通城猪差异不显著(P0.05)。以上结果表明:鄂通两头乌和通城猪的猪肉均具有高营养价值和独特风味等特点,而且鄂通两头乌除保留了通城猪肉的营养风味外,多不饱和脂肪酸、硫胺素含量更高,值得进一步开发利用。     

Evaluation of Streptocephalus dichotomus nauplii as a larval diet for freshwater prawn Macrobrachium rosenbergii

This study was performed to assess the nutritional value of Streptocephalus dichotomus nauplii and compared with standard larval diet and parthenogenetic strain of Artemia nauplii. The effectiveness of live feed was determined by feeding freshwater prawn Macrobrachium rosenbergii postlarvae. Results on the growth rate, weight gain, survival, fatty acid and amino acid composition show a significant variation between the dietary treatments. Mean larval growth was significantly different ( P  < 0.001) between control diet (13.5 ± 0.5 mm) and live feeds ( Streptocephalus nauplii; 18.4 ± 0.5 mm and Artemia nauplii 18.7 ± 0.2 mm). The weight of larvae-fed Streptocephalus (41.1 ± 1.44 mg) and Artemia nauplii (41.7 ± 0.2 mg) was not significantly different; however, treatment with live feeds was significantly higher than the control (16.3 ± 0.5 mg) ( P  < 0.001). Proximate composition on the fairy shrimp reveals that they are rich in protein, lipid, essential amino acids (EAA) and essential fatty acids (EFA). The polyenoic unsaturated fatty acid (18 : 2 n-6 and 18 : 3 n-3) and highly unsaturated fatty acid (20 : 4 n-3 and 20 : 5 n-3) show a dramatic increase in larval tissue relative to its proportional composition in the live diets. Amino acid composition in the live feeds, Streptocephalus and Artemia nauplii, perfectly reflects on the amino acid proportions in the larvae-fed diets which confirm its utilization.     

露地大白菜低温冻害气象指数保险费率厘定方法研究

【目的】为科学厘定露地大白菜低温冻害保险费率提供方法,为其他气象因子指数保险的保险费率厘定提供参考,为政策性农业保险的可持续发展提供助力。【方法】将1957—2018年每年初、终霜冻日期转化为儒历日,计算平均初、终霜冻日期,将平均初、终霜冻日期设定为低温冻害指数保险中的时间起赔阈值,并利用标准差分级法,对起赔阈值设置的合理性进行检验。精确统计大白菜各生长期投入成本,根据灾损率进行加权计算得出赔付比例。通过计算发生概率、灾损率与赔付比例3个因子综合得出露地大白菜低温冻害保险费率,并对种植区域进行加权计算,得出区域内的露地大白菜低温冻害保险费率。【结果】设计了露地大白菜低温冻害气象指数保险中时间和气温起赔阈值的计算方法,并制定了时间起赔阈值的检验方法。设计了低温冻害保险费率3个决定因子发生概率、灾损率和赔付比例的计算方法。【结论】经过检验,将平均初、终霜冻日期设定为丰宁满族自治县地区露地大白菜低温冻害气象指数保险的时间起赔阈值是合理的。露地大白菜在遭受轻、中、重三级低温冻害时的灾损率分别为0.3、0.7和1.0;发芽期赔付比例最高为45%,秧苗期赔付比例最高为75%,莲座期以后赔付比例最高为100%。各乡镇露地大白菜低温冻害气象指数保险费率为2%～3%,经过加权计算得出丰宁满族自治县地区低温冻害保险费率为2.14%。     

2.5%保得乳油对小麦蚜虫控制作用的研究

对不同剂量的2.5%保得乳油防治麦蚜的效果进行了评价。结果表明,2.5%保得乳油施用有效成分为7.50、6.25g/hm2时,其防效均极显著优于对照药剂处理的防效,持效期达7d以上,对小麦生长安全无害。     

Depletion of ascorbic acid derivatives in fish feed by the production process

ABSTRACT:   The depletion of ascorbic acid derivatives in fish feed during the feed processing (extrusion cooking and drying) was studied at five extrusion cooking temperatures and at 85°C for 2 h dryer processing temperature. Three ascorbic acid derivatives were used: L-ascorbyl-2-mono-phosphate Mg (APM), L-ascorbic acid sodium (AAS) and L-ascorbic acid palmitic acid ester (AAP). Samples were collected after drying and ascorbic acid derivatives losses evaluated. APM was found to be quiet stable with an average retention of 88%, but AAS and AAP were unstable and the depletion was very high.     

2BXJF-12型小麦播种机的设计及性能测试研究

在谷物条播机进行播种过程中，由于外槽轮排种器排种脉动性的缺陷，造成缺苗断垄或“疙瘩苗”的现象较为严重。在现有条播机的基础上进行了改进，设计了一种落种均匀器，大大提高了播种均匀性；并改进了镇压轮,降低了打滑率。