Identification of the surface components of Trypanosoma evansi.

125I-labelling was used to characterise the surface components of five stocks of Trypanosoma evansi. Two components of 67 and 60.5 kD were labelled in two of the stocks, a single 60.5 kD component in two other stocks and no components in the remaining stock. These differences are probably related to the labelling method and biochemical differences between the stocks.     

达氏鳇谷氨酸脱氢酶基因的克隆及双低菜粕添加对其表达的影响

谷氨酸脱氢酶(glutamate dehydrogenase,GDH)可通过逆催化谷氨酸脱氨参与氨基酸代谢,也可生产合成氨,参与氮代谢。实验克隆得到达氏鳇(Huso dauricus)谷氨酸脱氢酶基因(gdh)的开放阅读框序列。该序列全长为1 635 bp,编码544个氨基酸。氨基酸序列多重比对结果显示达氏鳇GDH与其它脊椎动物的序列一致性较高。进一步的系统进化树分析发现,达氏鳇GDH与两栖类、爬行类及哺乳类聚为一支。组织表达分析结果表明,达氏鳇gdh的mRNA在各组织中都有分布,并且在肠中转录水平最高。随后,采用荧光定量PCR分析了饲料中添加双低菜粕对达氏鳇蛋白质代谢相关基因(gdh、氨肽酶N apN、小肽转运载体pepT1)及应激反应相关的热休克蛋白(hsp 90)基因表达的影响。在肝脏中,不同饲料投喂组gdh和hsp90的转录水平没有显著差异。在肠中,菜粕组gdh及apN基因的转录水平显著高于基础饲料组;菜粕组pepT1基因的转录水平也高于基础饲料组,但是没有显著性差异。以上结果表明,植物蛋白原料菜粕添加可引起达氏鳇肠道中蛋白质代谢水平上升,而不引起鱼体的应激反应。     

Nitrolimigation: A Nutrient-in-Water Resource for Sustainable Crop Production on ‘Acid Sands’ of Southern Nigeria

The effects of a low-external-input soil fertility enhancement solution – hereafter termed ‘nitrolimigation’ were examined, as a preferred technique of applying nitrogen and calcium in the “Acid Sands” soils of southern Nigeria. Two types of nitrogenous fertilizer sources [urea and liquid pig manure (LPM)] and two types of lime {limestone (CaCO₃) and hydrated lime [Ca(OH)₂]} were used both in greenhouse and in field experiments at varying levels: Urea [CO (NH₂)₂] 0, 40, 50, 80, 100, 120, and 150 kg ha^?1; lime 0, 0.1, 0.3, 0.5, 1.0, 5.0, and 10.0 metric tonnes per hectare (t ha^?1) and LPM 0, 30, 60, 90, and 120 t ha^?1. The rates were arranged factorially and laid out in randomized complete block design (RCBD). The results indicated that combining lime at 9 t ha^?1 and LPM at 90 t ha^?1 in irrigation water had significant (P < 0.01) positive effects on the fertility status of the “Acid Sands” soils and growth of okra- Abelmoschus esculentus, the test crop. When urea was combined with hydrated lime, it reduced acidity and provided nutrient balance in the Acid Sands of Calabar. Total nitrogen was significantly (P < 0.01) boosted from 0.05 to 0.11%, base saturation (BS) from 46 to 62%, and exchange acidity was reduced from 2.93 to 1.35 cmol kg^?1. Combining urea (46-0-0) at 80 kg ha^?1 with lime (CaCO₃) at 5 t ha^?1 raised the soil pH from 4.4 to 7.1. Exchange acidity was reduced from 0.8 cmol kg^?1 to a negligible value, but electrical conductivity was improved from 170.7 to 291.9 μS cm^?1. When LPM and lime were combined, organic carbon was increased from 2.75 to 2.93%, BS was increased from 46.72 to 75.19%, and pH was raised from 6.0 to 6.73. Plant height was increased from 9.5 to 16.9 cm while mean number of leaves was also increased from 5.6 to 6.3 only with lower level of lime (3 t ha^?1) and LPM at 90 t ha^?1. Of the nitrogen and calcium sources, LPM and limestone were better at 120 t ha^?1 and 9 t ha^?1, respectively, to offset soil acidity, boost nutrient availability, and provide balanced nutrition to arable crops grown on the “Acid Sands” of southern Nigeria.     

Effects of Ostertagia ostertagi and omeprazole treatment on feed intake and gastrin-related responses in the calf

Infection with the bovine abomasal nematode, Ostertagia ostertagi, results in a loss of acid-secreting parietal cells and an increase in gastric pH. The effects of an experimental infection with Ostertagia and/or daily treatment with omeprazole (OMP) at 2mgkg(-1) bodyweight for four consecutive days (experiment days 24-27, inclusive) on voluntary feed intake, blood and tissue gastrin concentrations, abomasal G-cell numbers, gastric pH, and blood cholecystokinin (CCK) and pepsinogen concentrations were investigated in the calf. Ostertagia-infected calves demonstrated a significant drop in feed intake between days 24 and 27 post-infection (38%; P<0.001) and in G-cell numbers (42%; P<0.05) and significant increases in abomasal pH (P<0.001), fundic mucosal weight (99%; P<0.01), and blood gastrin (P<0.05) and pepsinogen (P<0.0001). OMP treatment of worm-free animals resulted in a significant drop in intake between days 24 and 27 (30%; P<0.001) and in G-cell numbers (17%; P<0.05) and significant increases in abomasal pH (P<0.01) and blood gastrin (P<0.001). OMP treatment of Ostertagia-infected animals with an existing hypergastrinaemia had no effect on feed intake, abomasal pH, blood gastrin or pepsinogen or abomasal G-cell numbers. Blood CCK concentrations were also unaffected by either Ostertagia infection or OMP treatment. These data suggest that: (a) the depression in feed intake associated with OMP in worm-free calves was not due to a side effect of drug treatment; (b) inappetance in Ostertagia-infected animals is closely associated with the parasite-induced hypergastrinaemia; and (c) the elevation in abomasal pH was a major factor responsible for the elevated blood gastrin concentrations seen in parasitised and OMP-treated animals.     

Gastrin and gastrin-related responses to infection with Ostertagia ostertagi in the half

The effects of a single challenge with 60,000 infective Ostertagia ostertagi larvae on blood and gastrointestinal mucosal gastrin concentrations, gastrin-producing G-cell numbers in the pyloric mucosa and growth of different parts of the gut were investigated in 16, two-and-a-half-month-old calves. Infected calves exhibited a rise in abomasal pH which was accompanied by a 145 per cent increase in wet weight of the fundic mucosa (P<0·05) and a significant rise in blood total gastrin concentrations (P<0·01). Circulating little gastrin (G-17) was unaffected. Pyloric mucosal total gastrin concentrations remained unaltered in the infected calves until day 28 when levels fell to 36·9 per cent of control group values (P<0·01). Pyloric mucosal G-cell numbers declined during the experiment in the infected group. It is suggested that release of previously stored tissue gastrin and not a change in Gcell numbers contributes to the hypergastrinaemia associated with ostertagia infection in the calf.     

耕作方式与秸秆还田对冬小麦–夏玉米轮作系统中干物质生产和水分利用效率的影响

为探讨黄淮海地区一年两熟制下土壤耕作方式与秸秆还田相结合的适宜模式,2010—2012年进行了两年度的田间试验,研究不同处理对冬小麦–夏玉米轮作系统干物质生产和水分利用效率的影响。通过比较常规耕作+秸秆还田、常规耕作+无秸秆还田、深耕+秸秆还田、深耕+无秸秆还田、深松+秸秆还田、深松+无秸秆还田6个处理,发现深松(耕)与秸秆还田可以增加冬小麦和夏玉米的农田耗水量,降低休闲期农田耗水量,提高作物叶片相对含水量、净光合速率、蒸腾速率和茎秆伤流量,促进植株干物质积累,进而提高作物籽粒产量和水分利用效率。耕作方式与秸秆还田对冬小麦和夏玉米的干物质生产和水分利用效率存在显著交互作用。与常规耕作+无秸秆还田相比,深耕+秸秆还田和深松+秸秆还田处理的作物干物质积累量分别提高19.3%和22.9%,周年作物产量分别提高18.0%和19.3%,水分利用效率分别提高15.9%和15.1%,且两处理无显著差异。因此认为,与本试验相似环境条件下,宜在秸秆还田的基础上配合深松或深耕。     

Magnetic field effect on picosecond electron transfer

The recombination dynamics of a transition metal redox system monitored by femtosecond pump-probe spectroscopy are shown to be sensitive to high magnetic fields at times shorter than 10 picoseconds. The effect, based on coherent population beats of different spin states, is quantitatively accounted for and allows direct access to spin relaxation rates far beyond the time resolution of the fastest electron paramagnetic resonance technique. The presence of this ultrafast magnetic field effect helps in understanding complex reaction schemes in transition metal chemistry, which occur in a wide range of fields, such as bioinorganic chemistry and catalysis.