CD8(+) T cell knockout mice are less susceptible to Cowdria ruminantium infection than athymic, CD4(+) T cell knockout, and normal C57BL/6 mice

The role of T cells in immunity to Cowdria ruminantium was investigated by studying the responses to infection of normal, athymic, CD4(+) T cell knock out (KO) and CD8(+) T cell KO C57BL/6 mice. Normal C57BL/6 mice could be immunized by infection and treatment, and immunity was adoptively transferable from immune to naive mice by splenocytes. Following infection, athymic mice died sooner than normal mice (P=0.0017), and could not be immunized by infection and treatment. CD4(+) T cell KO mice were as susceptible to infection as normal mice and could be immunized by infection and treatment. In contrast, CD8(+) T cell KO mice were less susceptible than normal and CD4(+) T cell KO mice and 43% self-cured, while those that died did so after a prolonged incubation period. Antibody responses to C. ruminantium were CD4(+) T cell dependent, because responses were detected in immune normal and CD8(+) T cell KO mice but not in immune CD4(+) KO mice (P=0.005). Since CD8(+) T cell KO mice were less susceptible to infection, and since CD4(+) T cell KO mice could be immunized, it can be concluded that immunity to C. ruminantium can be mediated by both CD4(+) and CD8(+) T cells.     

高产母猪矿物质需要的变化——需要什么及关键时期

现代养猪生产中,由于高产母猪品系的引入,使窝产仔数和断奶仔猪数不断增加,仔猪初生重和断奶重也不断提高。母猪妊娠的最后14天,胎儿将占总需求量近50%的矿物质(常量和微量元素)沉积到发育中的自身体组织中。哺乳阶段,母猪沉积的矿物质比妊娠后期更高,并且随着窝产仔数的增加而增加。这样看来,妊娠后期和哺乳期是研究母猪矿物质营养的关键时期。母猪奶水中矿物质的组成主要受基因控制,但也受到哺乳阶段和母猪窝产仔数的影响。在连续6个繁殖周期给母猪饲喂有机微量矿物元素的试验中,母猪的繁殖表现有所改善,每年能够多产1~2头仔猪。相对于低生产力母猪和非繁殖母猪,高产母猪机体矿物质含量更低,这是因为高生产力使母猪矿物质损耗加剧。     

克拉玛依市鼠害发生及其综合防治

于2003～2005年对克拉玛依境内的害鼠种类、数量分布和发生危害规律进行了全面系统的调查,结果表明,克拉玛依境内的害鼠分属1目、3科、11属,共计13种.为克拉玛依市农林牧业害鼠的决策防治及综合治理提供科学依据.     

The effect of subclinical experimental Cowdria ruminantium infection in ewes on the growth and milk consumption of pre-weaning lambs.

An alternative control option for heartwater (Cowdria ruminantium infection) is the establishment and maintenance of endemic stability which would lessen the existing dependence on acaricides. In an endemically stable state, animals become infected by vaccination or natural challenge at an early age, following which the immunity so created is boosted by continuing tick challenge. In this study, growth rates, health and hematological parameters were monitored at regular intervals for lambs born to two matched groups of ewes until weaning at 4 mo of age. One group of ewes was infected multiple times with Cowdria ruminantium; the other group remained uninfected. The overall mean leucocyte count of lambs born to infected ewes was significantly lower than that of lambs born to uninfected ewes (P=0.04). However, there were few other significant differences in the other hematological data between the two groups. The mean birth weight of single lambs born to uninfected ewes (4.6 kg) was significantly higher than the mean birth weight of single lambs born to infected ewes (4.4 kg) (P=0.02). Trends in milk consumption and growth rates were similar for the two groups, with few significant differences detected. Likewise, there were no significant differences in the incidences of health problems or pre-weaning mortalities between the two groups of lambs. The results of this study indicate that there is no detectable effect on productivity of pre-weaning lambs when their dams are carriers of C. ruminantium--a situation likely to occur in an endemically stable state. Hence, maintenance of endemic stability would be a suitable control option for heartwater.     

Effect of injected and dietary iron in young pigs on blood hematology and postnatal pig growth performance

The relationship of injected Fe doses on blood hematology and pig growth performance during both preweaning and postweaning periods was studied. In Exp. 1, the effect of BW of 347 pigs injected with 200 mg of Fe (dextran) intramuscularly (i.m.) at birth on hemoglobin (Hb) and percent hematocrit (Hct) at weaning was assessed. As BW increased there was a decline (P < 0.01) in Hb and Hct. In Exp. 2, Fe injection doses and timing of injected Fe on blood hematology and pig growth were evaluated. Injections were as follows: 1) 200 mg of Fe at birth; 2) 300 mg of Fe at birth; or 3) 200 mg of Fe at birth + 100 mg of Fe at d 10. A total of 269 pigs were allotted within litter to 3 treatments. The 2 greater quantities of injected Fe (i.e., 300 or 200 + 100 mg of Fe) had similar but greater (P < 0.05) Hb and Hct values than pigs receiving 200 mg of Fe, but growth rates were similar at weaning. The effects of injecting 200 mg of Fe at birth and either saline or 100 mg of Fe at 10 d of age were investigated in Exp. 3. Weaned pigs of each group were fed diets with 0, 80, or 160 mg/kg of added Fe for 35 d as a 2 × 3 factorial arrangement with 12 replicates (n = 360 pigs) in a randomized complete block design (RCB). The innate Fe contents of diets averaged 200 mg/kg. The greater Fe injection group (200 + 100 mg) had greater (P < 0.01) Hb and Hct values through 14 d postweaning (P < 0.05) and greater (P < 0.01) Hct values through 21 d postweaning. As dietary Fe increased, Hb was greater only at d 14 (P < 0.05 4), whereas Hct increased linearly to d 35 (P < 0.01) postweaning. Dietary Fe resulted in linear increases (P < 0.01) in ADG from d 21 to 35 and d 0 to 35. In Exp. 4, 3 dietary Fe (80, 160, and 240 mg/kg of diet), 2 injected Fe treatments (200 or 300 mg of Fe) at birth, and birth BW (<1.5 or ≥1.5 kg) were evaluated as a 2 × 2 × 3 factorial arrangement of treatments in a RCB design with 6 replicates (n = 280 pigs). The 300 mg of Fe injection group had lighter BW in both birth BW groups, with a birth BW × injected Fe interaction (P < 0.01). This resulted in the lighter birth BW pigs receiving 200 mg of Fe having greater BW gains to 240 mg/kg of dietary Fe, whereas light birth BW pigs injected with 300 mg of Fe plateaued at 160 mg/kg of Fe. Pigs in the heavy birth BW group injected with 200 or 300 mg of Fe at birth responded similarly to dietary Fe postweaning. These results indicate that blood Hb and Hct were affected by pig BW at weaning, but the additional 100 mg of Fe i.m. at 10 d of age increased blood hematology and that Fe injected preweaning affected initial postweaning performance.     

The genetic program of hematopoietic stem cells

Blood cell production originates from a rare population of multipotent, self-renewing stem cells. A genome-wide gene expression analysis was performed in order to define regulatory pathways in stem cells as well as their global genetic program. Subtracted complementary DNA libraries from highly purified murine fetal liver stem cells were analyzed with bioinformatic and array hybridization strategies. A large percentage of the several thousand gene products that have been characterized correspond to previously undescribed molecules with properties suggestive of regulatory functions. The complete data, available in a biological process-oriented database, represent the molecular phenotype of the hematopoietic stem cell.     

Thermal environment of cotton irrigated using canopy temperature

The threshold canopy temperature method for controlling a drip irrigation system includes a physiologically based threshold temperature and irrigation application rate that responds to the environment. Energy input from the environment causes canopy temperature to exceed the threshold value and irrigation is then applied. This study evaluated temperature distributions, amount of optimum time, and the amount of irrigation control time for cotton where irrigation scheduling was controlled by different threshold temperatures during the years 1988 to 1991. Optimum time for cotton growth was defined as the accumulated time that canopy temperatures were between 25 and 31 °C and the time accumulated above different threshold temperatures was designated as irrigation control time. Threshold temperatures over a 26 to 32 °C range altered the frequency distribution of temperature within the optimum temperature range (25–31 °C) by reducing temperatures above the threshold. Frequency of canopy temperatures of a 28 °C threshold temperature treatment decreased in the 28 to 29 °C increment and then remained below air temperature. Irrigation control time was more sensitive than optimum time to changes in threshold temperature between 26 and 31 °C. Optimum time and irrigation control time of the 28 °C threshold temperature varied by 37% and 29%, respectively. Lint yields in 1988 and 1990 were high while those in 1989 and 1991 were low because of unfavorable weather. Irrigation amounts applied during DOY 198–273 that were above 20 cm in high yield years or 12 cm in low yield years did not increase yield.     

Thermal dependence of glutathione reductase in one tetraploid and its near-isogenic diploid alfalfa

Summary A more thorough understanding of the biochemical basis of superior performance of one alfalfa (Medicago sativa L.) genotype compared to another would expedite improvement in agronomically useful genotypes. Information on thermal dependence of glutathione reductase (GR, E.C. 1.6.4.2) in different ploidy levels of alfalfa is lacking. Our objective was to investigate the thermal dependency of GR in two genetically comparable populations of alfalfa at diploid and tetraploid levels. Thermal stability was similar for the enzyme from both populations, whereas variation was found for: i) the minimum apparent Km (0.53 and 4.14 M NADPH), ii) the temperature at which the minimum apparent Km was observed (15 and 25° C), and iii) the thermal kinetic windows (TKW) (the temperature range over which the apparent Km is within 200% of the observed minimum Km, 5 and 20° C width) in diploid and tetraploid alfalfa, respectively. The TKW data suggest that the diploid can perform optimally under a narrower (i.e. smaller TKW) and lower range (i.e. the temperature at which the lowest Km was observed) of temperatures, whereas the tetraploid can perform optimally under a wider range (i.e. larger TKW) of temperatures. This finding is in agreement with previously published growth data on near-isogenic populations of diploid and tetraploid alfalfa.Abbreviations GR glutathione reductase - TKW thermal kinetic window - Km apparent Km This work was supported by USDA Specific Cooperative Agreement No. 58-7MN1-8-143 from the Plant Stress and Water Conservation Unit, USDA-ARS, Lubbock, Texas. Joint contribution of the Texas Tech University, USDA-ARS, Lubbock, TX and University of Wisconsin, Madison, WI. TTU Journal No. T-4-306.     

Chemical composition and protein quality comparisons of soybeans and soybean meals from five leading soybean-producing countries

Soybeans (SBs) were obtained from five leading SB-producing countries (Argentina, Brazil, China, India, and the United States), imported to the United States, and processed into soybean meal (SBM) under uniform conditions in the United States. SBs from China had the highest crude protein (CP) content while SBs and the resultant SBM from Argentina had the lowest. Additional differences in the quality of the SB and resultant SBM samples collected were noted. An additional set of SBM produced in these five countries and subjectively evaluated to be of low, intermediate, and high quality also were obtained and evaluated. Overall, SBM quality affected amino acid and mineral concentrations with differences existing both among and within countries. SBM produced in the United States had a higher CP content than SBM produced in other countries. Amino acid concentrations generally increased, and antinutritional factors decreased with increasing subjective quality assessment.