基于虚拟仪器技术的饲料体外发酵产气自动记录系统的研制

针对评定反刍动物饲料营养价值的常用体外发酵产气测试方法所存在的自动化程度低、测量误差大、工作效率低等技术方法不足,采用虚拟仪器技术设计了体外发酵产气自动记录系统。利用差压开关和电磁阀控制发酵容器内微气体压力,当压力上升至差压开关标定值时电磁阀导通并实现排气,每导通一次排出约1.0～2.8 mL标定气体,通过记录产气次数完成产气量实时记录、分析和存储。试验结果表明该系统具有良好的自动化、智能化、图形化等特点,提高了实时测定结果的重复性、准确性和工作效率,降低了科研工作者的试验劳动强度。结合气体组分分析,该系统也可作为体外法评定饲料发酵温室气体(甲烷和二氧化碳)排放量估测的科学试验研究技术手段。     

禾谷缢管蚜在越冬寄主植物上的行为研究

通过室内饲养观察、田间调查和利用微型昆虫显微摄影技术,研究了禾谷缢管蚜越冬卵在越冬寄主稠李(Prunus padis)上孵化,干母、干雌取食、生长发育和繁殖等行为过程,以及形态和体色变异特点。结果表明,禾谷缢管蚜越冬卵在室内的孵化率为88.68％-92.51％;在德国北部吕贝克附近田间孵化率为24.2％。越冬卵孵化起点温度低于4℃。在室温22℃下卵孵化历期为5-7d,孵化高峰在卵孵化始期后第3-4天。一日内最佳孵化时间在05:00-07:30。在室内饲养条件下,将越冬卵孵化的干母直接移植到麦苗上,蚜虫几乎都不能存活。     

Variations in equid SLC11A1 (NRAMP1) genes and associations with Rhodococcus equi pneumonia in horses

Rhodococcus equi is an important intracellular pathogen of horses, most commonly causing chronic, suppurative bronchopneumonia in foals. Although most foals likely are exposed to environmental R. equi within the 1st few days of life, only some develop R. equi pneumonia, and the basis of differences in susceptibility among foals currently is unknown. In this study, we investigated solute carrier family 11 member 1 (SLC11A1) gene sequences in the 5' untranslated region, exon 1, and a portion of intron 1 for variations in 3 equid species (horse, donkey, zebra) and compared variants within 3 independent horse breeding farms for associations with R. equi pneumonia by use of an age-matched case-control design. Seven novel variants in the 5'untranslated region were identified as specific for one or both of the non-horse equid species sampled. In addition, a single novel horse variant in the 5'untranslated region, -57C/T, was identified in 4 breeds. The -57C/T variant was found on 2 of the 3 farms with endemic R. equi pneumonia, representing 2 different horse breeds. Significant allelic and genotypic associations with susceptibility to R. equi pneumonia were observed for the -57C/T variant in foals from these farms. Although the functional impact of this novel variant remains to be determined, this study represents an important step in our understanding of natural resistance to R. equi foal pneumonia and other intracellular bacterial diseases affecting equids.     

Technical note: development and testing of a radio transmission pH measurement system for continuous monitoring of ruminal pH in cows

An indwelling ruminal pH system has been used for the continuous recording of ruminal pH to evaluate subacute ruminal acidosis (SARA) in dairy cows. However this system does not allow the field application. The objective of this study was to develop a new radio transmission pH measurement system, and to assess its performance and usefulness in a continuous evaluation of ruminal pH for use on commercial dairy farms. The radio transmission pH measurement system consists of a wireless pH sensor, a data measurement receiver, a relay unit, and a personal computer installed special software. The pH sensor is housed in a bullet shaped bolus, which also encloses a pH amplifier circuit, a central processing unit (CPU) circuit, a radio frequency (RF) circuit, and a battery. The mean variations of the measurements by the glass pH electrode were +0.20 (n = 10) after 2 months of continuous recording, compared to the values confirmed by standard pH solutions for pH 4 and pH 7 at the start of the recording. The mean lifetime of the internal battery was 2.5 months (n = 10) when measurements were continuously transmitted every 10 min. Ruminal pH recorded by our new system was compared to that of the spot sampling of ruminal fluid. The mean pH for spot sampling was 6.36 ± 0.55 (n = 96), and the mean pH of continuous recording was 6.22 ± 0.54 (n = 96). There was a good correlation between continuous recording and spot sampling (r = 0.986, P < 0.01). We also examined whether our new pH system was able to detect experimentally induced ruminal acidosis in cows and to record long-term changes in ruminal pH. In the cows fed acidosis-inducing diets, the ruminal pH dropped markedly during the first 2 h following the morning feeding, and decreased moreover following the evening feeding, with many pulse-like pH changes. The pH of the cows showed the lowest values of 5.3-5.2 in the midnight time period and it recovered to the normal value by the next morning feeding. In one healthy periparturient cow, the circadian changes in ruminal pH were observed as a constant pattern in the pre-parturient period, however that pattern became variable in the post-partum period. The frequency of the ruminal pH lower than 5.5 increased markedly 3 and 4 days after parturition. We demonstrated the possible application of a radio transmission pH measurement system for the assessment and monitoring of the ruminal pH of cows. Our new system might contribute to accurate assessment and prevention of SARA.     

Calcium-sensing receptor modulates pulmonary artery tension through G-protein-PLC-IP3 pathways

AIM: To observe the role of calcium-sensing receptor (CaSR) in the regulation of pulmonary artery tension. METHODS: The intracellular calcium concentration ([Ca²⁺]_i) was detected by laser-scanning confocal microscopy, and the pulmonary artery tension was determined by the pulmonary arterial ring technique. RESULTS: Increased levels of [Ca²⁺]_o or Gd³⁺ (an agonist of CaSR) induced the increase in [Ca²⁺]_i and pulmonary artery constriction in a concentration-dependent manner. Additionally, the effects of Ca²⁺ and Gd³⁺ were inhibited by U73122 and D609 (specific inhibitor of PLC), and 2-APB and heparin (specific antagonist of IP₃ receptor). However, U73343 (U73122 inactive analogue) did not take effect. CONCLUSION: CaSR may be involved in the regulation of pulmonary artery tension by increasing [Ca²⁺]_i through G-protein-PLC-IP₃ pathway.     

Early impacts of cotton and peanut cropping systems on selected soil chemical,physical, microbiological and biochemical properties

This study investigated the impacts of cropping systems of cotton (Gossypium hirsutum L.; Ct) and peanut (Arachis hypogaea L.; Pt) on a Brownfield fine sandy soil (Loamy, mixed, superactive, thermic Arenic Aridic Paleustalfs) in west Texas, United States. Samples (0–12 cm) were taken 2 and 3 years after establishment of the plots from PtPtPt, CtCtPt and PtCtCt in March, June and September 2002, and in March 2003. Soil total N and aggregate stability were generally not different among the cropping systems. The pH of the soils was >8.0. Continuous peanut increased soil organic C, microbial biomass C (C_mic) and the activities of -glucosidase, -glucosaminidase, acid phosphatase, alkaline phosphatase, phosphodiesterase and arylsulfatase compared to the peanut-cotton rotations. The arylsulfatase activity of the fumigated field-moist soil and that resulting from the difference of the fumigated minus non-fumigated soil were greater in PtPtPt, but arylsulfatase activity of non-fumigated soil was unaffected by the cropping systems. Soil C_mic showed a different seasonal variation to enzyme activities during the study. Enzyme activities:microbial biomass ratios indicated that the microbial biomass may not have produced significant amounts of enzymes or that newly released enzymes did not become stabilized in the soil (i.e., due to its low clay and organic matter contents). Fungal (18:26c and 18:19c) and bacterial (15:0, a15:0, and a17:0) FAMEs were higher in PtPtPt than in CtCtPt or PtCtCt cropping systems. Our results suggest that the quality or quantity of residues returned to the soil under a peanut and cotton rotation did not impact the properties of this sandy soil after the first 3 years of this study.     

柳茎木质部中的变异电波传递

用胞外电极记录了柳茎木质部中的变异电波传递。探讨了柳茎中变异电波传递的途径及传递机制。结果表明，柳茎中烧伤引发的变异电波可顺利地从单独的木质部通过，而不依赖韧皮部（树皮）的存在与否，并且，变异电波越过单独木质部后．可再横向传递至茎韧皮部（树皮），被表面电极记录下来。在单独的木质部中，变异电波传递的速度可达正常柳茎的３～６倍，说明韧皮部的活细胞对变异电波的传递阻力很大。变异电波在木质部的传递速度受外界供水状况的影响，让断茎吸水时，变异电波传递速度快；不让断茎吸水时，变异电波传递速度慢或不传递。由此可见，在柳茎中，变异电波可能是优先在木质部中传递的．但又同时从木质部向韧皮部（树皮）传递。变异电波传递过程中，至少同时存在两种传递方式：即娄成后等（１９５９）提出的电化学波传递方式和单靠活细胞局部电流接力传送的方式。     

Epidemiological and genetical studies in Norwegian pig herds. IV. Breed effects, recurrence of disease, and relationship between disease and some performance traits

Individual health records collected from 1984 to 1986 in 70 swine-herds in the south-eastern part of Norway were analysed by epidemiological methods. The incidence rate for most of the reported diseases was less than 1% per farrowing, and a majority of disease recordings concerned 6 frequently-occurring conditions. The incidence of several diseases was lower in crossbred sows compared to purebred Norwegian landrace sows. The risk of most diseases increased in sows that had been ill previously, and also in litters from sows that had previously had diseased litters. Disease risk in piglets also increased if the sow became ill during the first few days after farrowing. The reduced performance associated with most of the common diseases impacts adversely on economic returns.