Detection of early pregnancy factor in superovulated mice

Rosette inhibition tests for the detection of early pregnancy factor (EPF) were performed on naturally ovulated and superovulated mice from day 2 of pregnancy up to 4 days after parturition. In both groups of mice, the rosette inhibition titre (RIT) increased on day 2 of pregnancy, and persisted at high levels until day 15. Thereafter, the RITs of both groups of mice decreased to the non-pregnancy range. No significant differences of the mean RITs between these two groups were observed during the high RIT period. These results showed that the superovulatory treatment did not cause any changes or interference in the detection of EPF. In order to investigate the initial time of appearance of EPF in the maternal circulation in relation to the stage of fertilization, measurement of RIT and examination of the fertilization stage were carried out on superovulated mice 1 day after mating. The mean RIT of mice with pronucleus stage ova was significantly (p less than 0.01) higher than that of mice with sperm-penetrated ova. EPF was considered to appear in the maternal peripheral blood at the pronucleus stage.     

Type-I hypersensitivity as a component of eosinophilic myositis (muscular sarcocystosis) in cattle

Eight bovine hearts with lesions of eosinophilic myositis (EM) and 2 bovine hearts without EM lesions were collected at slaughter. Blood samples from these 10 hearts, and the heart of a newborn calf also were collected. Histologically, Sarcocystis cruzi was identified in the 8 hearts with EM lesions and the 2 hearts without EM lesions, but not in the heart of the newborn calf. Serum was harvested from the 10 blood samples and was used in homologous, modified, passive cutaneous anaphylaxis tests. Antigen was prepared from S cruzi bradyzoites isolated from the 2 hearts without EM lesions. Serum samples from the 8 cattle with EM lesions reacted positively to S cruzi antigen. When heat-inactivated IgE in serum (56 C for 4 hours) was used, all passive cutaneous anaphylaxis responses were considered negative. Using ELISA, serum IgE concentrations from the 10 cattle with and without EM lesions were 2.2 to 9 U/ml. As determined by radial immunodiffusion, IgM concentrations were 80 to 215 mg/dl. Immunoglobulin G concentrations were 420 to 2,050 mg/dl, but most were less than or equal to 1,700 mg/dl. Immunoglobulin A concentrations were 0 to 62 mg/dl; 1 steer with EM lesions had 0 mg/dl. Double-gel immunodiffusion confirmed the presence of Sarcocystis-specific precipitating antibodies. Sera from the 10 cattle with and without EM lesions formed at least 1 precipitin band.     

Effects of abiotic variables on the response of carnation cultivars to Fusarium oxysporum f.sp. dianthi

The effects of abiotic variables on the response of carnation cultivars to Fusarium oxysporum f.sp. dianthi ( F.o. dianthi  ) were examined in experiments conducted under semi-controlled environments. The abiotic variables examined were solar radiation intensity, temperature and growth substrate. Temperature was not controlled, but differed markedly among experiments, thus, its effect was not determined quantitatively. Disease incidence and disease severity varied significantly among the experiments (due mainly to differences in temperature), among the solar radiation treatments and among the cultivars tested. The three-way interaction term (i.e. cultivar × shade treatment × experiment) was highly significant ( P  < 0.001) when both disease incidence and disease severity were considered, indicating that no single variable was predominant in determining disease intensity. The effects of the growth substrate on disease progress was examined in plants grown in tuff or in tuff mixed with peat (1 : 1 and 1 : 3) substrates. The growth substrate had a potent effect on disease development in the less susceptible cultivars. Severe epidemics developed in all cultivars when they were grown in the tuff/peat mixture, although some were resistant when grown in tuff alone. These results led to the conclusion that the carnation response to F.o. dianthi is substantially influenced by the environmental conditions of the test.     

The effects of stubble burning and tillage on soil carbon sequestration and crop productivity in southeastern Australia

Abstract. In Australia, stubble burning and tillage are two of the major processes responsible for the decline of soil organic carbon concentration in cropped soils, and the resulting soil degradation. However, the relative importance of these two practices in influencing the soil organic carbon concentration and the long-term impact on soil quality and productivity are not clear. The effects of stubble burning as practised by farmers in southeastern Australia were evaluated in two field trials, one of 19 years duration, the other of 5 years. Conventional tillage (three tillage passes) led to greater loss of soil organic carbon than stubble burning. Loss of total soil organic carbon attributed to stubble burning in the 0–10 cm layer was estimated to be 1.75 t C ha⁻¹ over the period of the 19-year trial, equivalent to 29% of that lost due to tillage. In the 5-year trial, no change in soil organic carbon due to stubble burning was detectable. Changes in soil quality associated with stubble burning detected in the longer trial included a reduction in macro-aggregate stability, and increases in pH and exchangeable K⁺. Only the latter two were detected in the shorter trial. A higher mean wheat yield (average 0.15 t ha⁻¹) following stubble burning was observed in the 19-year trial but not in the 5-year trial. Research to monitor the longer term effects of stubble burning is needed, and to identify conditions where loss of soil organic carbon is minimized.     

不同蚕品种的饲料效率初探

本文调查分析了近二、三十年来,我国春用蚕品种和夏秋用蚕品种主要经济性状的变迁情况。结果表明,目前推广的蚕品种与五十、六十年代推广的品种相比较,茧层量、茧层率,茧丝量、茧丝长等主要经济指标都有了显著的提高,尤其是茧层量、茧层率的增长更为突出.但5龄经过和食下量也相应地增加,蚕的消化率以及饲料效率几乎没有提高。从而认为,在今后蚕品种改良过程中,应重视提高饲料效率的研究,并通过桑品种改良、饲育技术等途径,提高饲料效率,提高养蚕的经济效益。     

不同途径感染猪血球凝集性脑脊髓炎病毒的比较病理学

用传代鼠血球凝集性脑脊髓炎病毒接种液，经不同途径感染12头5日龄仔猪作比较病理学研究。结果表明，经脑内注射、前后肢肌肉注射、口服、口服兼滴鼻等途径接种的仔猪全部感染发病，并在接种后36～98h死亡。发病猪出现脑、脊髓的小静脉和毛细管充血、出血、水肿，神经原水肿、急性肿胀、急性液化及中央染色质溶解，胶质细胞轻微增生等非化脓性脑脊髓炎特征。口服兼滴鼻接种猪脑脊髓出血、脑水肿最明显，神经原变质也最重。脑内接种猪脑膜的血管周围出现明显的免疫细胞反应。     

Effect of ivermectin and oxfendazole on shedding of larvae of the lungworm (Dictyocaulus viviparus) by red deer (Cervus elaphus)

Thirty eight newly weaned hinds were randomly allocated to one of two equal groups. One group received ivermectin, the other, oxfendazole at dose rates of 0.2 mg/kg and 4.5 mg/kg, respectively. All deer were drenched four times and were grazed on pasture. Both anthelmintics reduced D. viviparus faecal larval counts to low levels 20 days after dosing, but the mean larval output and the proportion of deer shedding D. viviparus larvae at 27 and 33 days after treatment, were significantly lower in the ivermectin treated group. There was no significant difference in weight gain between the two groups throughout the trial. This study suggests that ivermectin prevents reinfection with D. viviparus for approximately 14 days longer than oxfendazole.     

Synergistic interactions between phenylamide fungicides and respiration inhibitors in controlling phenylamide-resistant populations ofPhytophthora infestans on potato tuber disks

The efficacy of mixtures of respiration inhibitors and phenylamide fungicides (oxadixyl and metalaxyl) in controlling late blight was investigated using potato tuber disks. Results showed that uncoupling agents(e.g. DNP), inhibitors of ATP formation(e.g. oligomycin), ionophores(e.g, valinomycin) and inhibitors that block specific carriers in the electron transport chain(e.g. rotenone, antimycin A) increased significantly the control efficacy of both metalaxyl and oxadixyl towards populations ofPhytophthora infestons when applied to tuber slices pretreated with sublethal doses of both fungicides. When applied alone at the same doses, respiration inhibitors did not inhibit the development of the late blight fungus. Increased control efficacy of mixtures was not noted against phenylamide-sensitive populations of the fungus.