Biological Control of Sclerotinia Diseases of Rapeseed by Aerial Applications of the Mycoparasite Coniothyrium minitans

Indoor and field experiments were conducted to evaluate the efficacy of applying the mycoparasite Coniothyrium minitans to the aerial parts of rapeseed plants at the flowering stage to control sclerotinia diseases caused by Sclerotinia sclerotiorum. Under controlled conditions, a petal inoculation technique was used to determine the effect of conidial suspensions of C. minitans on suppression of sclerotinia leaf blight. Results showed that C. minitans was effective in inhibiting infection initiated by ascospores of S. sclerotiorum on flower petals by restricting mycelial growth of the pathogen. Suppression of lesion development was related to the conidial concentration of C. minitans, with larger lesions at low concentration (5×10³conidia ml⁻¹), but smaller lesions at high concentration (5×10⁴ conidia ml⁻¹ or higher). When C. minitans-treated rapeseed leaves were inoculated with mycelia of S. sclerotiorum, C. minitans failed to prevent infection of leaves, but caused a significant reduction in number of sclerotia produced on the diseased leaves. No significant difference in efficacy was detected between the two isolates of C. minitans, LRC 2137 and Chy-1, on the two rapeseed cultivars, Westar (spring type) and Zhongyou 821 (winter type). Results of field trials showed a significant reduction of stem rot of rapeseed in four (1997, 1999, 2003 and 2004) out of five years by aerial application of C. minitans, compared with controls. No significant difference in suppressive efficacy was observed between the treatments of C. minitans (10⁶ conidia ml⁻¹), C. minitans (10⁶ conidia ml⁻¹) + benomyl (50 μg ml⁻¹) and benomyl (100 μg ml⁻¹) in 2003, and between the treatments of C. minitans (10⁶ conidia ml⁻¹), C. minitans (10⁶ conidia ml⁻¹) + vinclozolin (100 μg ml⁻¹) and vinclozolin (500 μg ml⁻¹) in 2004. Sclerotia of S. sclerotiorum collected from diseased plants in plots treated with C. minitans in 1999, 2000 and 2003, or with C. minitans + benomyl in 2003 were infected by C. minitans at frequencies ranging from 21.3 to 54.5%. This study concludes that aerial spraying of C. minitans is an effective method for controlling sclerotinia diseases of rapeseed.     

1-O-Alkylglycerol Ethers from the Marine Sponge Guitarra abbotti and Their Cytotoxic Activity

The cytotoxicity-bioassay-guided fractionation of the ethanol extract from the marine sponge Guitarra abbotti, whose 1-O-alkyl-sn-glycerol ethers (AGEs) have not been investigated so far, led to the isolation of a complex lipid fraction containing, along with previously known compounds, six new lipids of the AGE type. The composition of the AGE fraction as well as the structures of 6 new and 22 previously known compounds were established using ¹H and ¹³C NMR, GC/MS, and chemical conversion methods. The new AGEs were identified as: 1-O-(Z-docos-15-enyl)-sn-glycerol (1), 1-O-(Z-docos-17-enyl)-sn-glycerol (2), 1-O-(Z-tricos-15-enyl)-sn-glycerol (3), 1-O-(Z-tricos-16-enyl)-sn-glycerol (4), 1-O-(Z-tricos-17-enyl)-sn-glycerol (5), and 1-O-(Z-tetracos-15-enyl)-sn-glycerol (6). The isolated AGEs show weak cytotoxic activity in THP-1, HL-60, HeLa, DLD-1, SNU C4, SK-MEL-28, and MDA-MB-231 human cancer cells. A further cytotoxicity analysis in JB6 P⁺ Cl41 cells bearing mutated MAP kinase genes revealed that ERK2 and JNK1 play a cytoprotective role in the cellular response to the AGE-induced cytotoxic effects.     

利用微滴数字PCR技术分析转基因大豆‘GE-J12’中外源基因的拷贝数

为鉴定抗除草剂转基因大豆新品种‘GE-J12’的外源基因插入拷贝数,以该转化体的外源插入目的基因G2-EPSPS和GAT的序列、3′转化体特异性序列为靶序列,设计PCR扩增引物和TaqMan探针,并对引物探针特异性进行鉴定,同时以大豆内标基因Lectin为参照,建立微滴数字PCR拷贝数检测体系。特异性试验结果显示,只有以抗除草剂转基因大豆‘GE-J12’基因组DNA为模板才有扩增信号。以单株转基因大豆‘GE-J12’基因组DNA为模板,进行外源目的基因G2-EPSPS和GAT、3′转化体特异性序列的微滴数字PCR检测,转基因大豆‘GE-J12’的外源目的基因G2-EPSPS和GAT在基因组上的插入拷贝数均值分别为0.99和1.01。同时3′转化体特异性序列的拷贝数均值为1.00,验证单株转基因大豆‘GE-J12’为纯合子,因此鉴定该单株转基因大豆‘GE-J12’的外源基因在大豆基因组上为单拷贝插入,同时与Southern blot方法进行比较,结果一致。     

Clinical and subclinical mastitis in smallholder dairy farms in Tanzania: risk, intervention and knowledge transfer

In a cross-sectional study of 400 randomly selected smallholder dairy farms in the Tanga and Iringa regions of Tanzania, 14.2% (95% confidence interval (CI)=11.6-17.3) of cows had developed clinical mastitis during the previous year. The point prevalence of subclinical mastitis, defined as a quarter positive by the California Mastitis Test (CMT) or by bacteriological culture, was 46.2% (95% CI=43.6-48.8) and 24.3% (95% CI=22.2-26.6), respectively. In a longitudinal disease study in Iringa, the incidence of clinical mastitis was 31.7 cases per 100 cow-years. A randomised intervention trial indicated that intramammary antibiotics significantly reduced the proportion of bacteriologically positive quarters in the short-term (14 days post-infusion) but teat dipping had no detectable effect on bacteriological infection and CMT positive quarters. Other risk and protective factors were identified from both the cross-sectional and longitudinal included animals with Boran breeding (odds ratio (OR)=3.40, 95% CI=1.00-11.57, P<0.05 for clinical mastitis, and OR=3.51, 95% CI=1.29-9.55, P<0.01 for a CMT positive quarter), while the practice of residual calf suckling was protective for a bacteriologically positive quarter (OR=0.63, 95% CI=0.48-0.81, P相似文献   

Selection on multiple QTL with control of gene diversity and inbreeding for long-term benefit

The purpose of this study was to develop and investigate selection strategies that aim at maximizing long-term genetic response while conserving gene diversity and controlling inbreeding in populations of limited effective size, assuming complete knowledge of all genes affecting a quantitative trait. Three selection strategies were proposed to select on 100 quantitative trait loci (QTL) and compared with truncation selection on breeding value. Alternative selection strategies aimed at maximizing the average breeding value of parents with a penalty on (1) the number of unfavourable QTL genotypes among parents (OS-I), (2) the negative of the logarithm of the frequency of the favourable allele at each QTL among parents (OS-II), and (3) the average pedigree relationship among parents (OS-III). When all QTL and their effects were known, the strategies examined were able to obtain extra long-term responses, conserve QTL diversity and reduce inbreeding, compared with truncation selection. Strategy OS-II was the most effective in conserving QTL diversity and OS-III in reducing inbreeding. By changing the magnitude of the penalties applied, the impact on long-term response, inbreeding and diversity can be controlled. Extra long-term responses over truncation selection of OS-I and OS-II were even greater when effects of QTL were estimated rather than assumed known, indicating the applicability of results to practical strategies for marker-assisted selection. Extra responses are expected to be reduced for larger population sizes.     

Comparative toxicology of monensin sodium in laboratory animals

The toxicology of monensin has been studied in several laboratory animal species. There was considerable species variation in acute oral LD50 values. The consistent signs of acute toxicity were: anorexia, hypoactivity, skeletal muscle weakness, ataxia, diarrhea, decreased weight gain and delayed deaths. The 3-mo study in rats fed diets containing 0, 50, 150 or 500 ppm monensin resulted in no effects at the lowest dose level, slight reduction of body weight gain in the middle-dose group and severe depression in body weight gain, skeletal and cardiac lesions, and deaths in the highest dose group. The 3-mo study in dogs given daily oral doses of 0, 5, 15 or 50 mg/kg monensin resulted in no effects at the lowest dose level. Dogs in the 15 and 50 mg/kg groups developed, during test wk 1 to 4, anorexia, weakness, ataxia, labored respiration, body weight loss, increased serum muscle enzyme values, severe skeletal muscle degeneration and necrosis with less severe heart lesions and deaths. Mice fed diets containing 0, 37.5, 75, 150 or 300 ppm monensin for 3 mo had reduced body weight gain in all test groups but no other physical signs. Serum creatine phosphokinase (CPK) values were increased in mice in the two highest dose groups and minimal heart lesions were found in the highest dose group. Dogs given daily oral doses of 0, 1.25, 2.5, 5 or 7.5 mg/kg monensin for 1 yr survived with no evidence of toxicity in the two lowest dose groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Arachidonic acid immunoregulation in lambs persistently infected with border disease virus

To evaluate arachidonic acid-related immunoregulatory mechanisms during long-term persistent pestivirus infection, we measured plasma contents of leukotriene C4 (LTC4), prostaglandin D2 (PGD2) and their plasma fatty acid (FA) precursor, arachidonic acid (AA), in six lambs with congenital border disease (BD). Significantly elevated average plasma LTC4 during the first half year of life was associated with increased PDG2 when compared to uninfected control lambs. Significantly elevated total plasma esterified AA stores suggest an effective BDV-mediated prostenoid immunostimulation. However, at 1 yr old, prostenoid secretion had fallen to normal (LTC4) or below normal (PGD2) levels. In contrast, there remained significantly elevated plasma esterified AA, present as available substrate for formation of these anti-viral immunoregulatory agents. These results suggested that preventing mobilization of AA from lipid stores for effective immune responses may be a viral strategy of BD virus that is associated with long term border disease effects.     

Effects of perineural capsaicin treatment on compound action potentials of superior laryngeal nerve afferents in sevoflurane-anesthetized dogs

Effects of perineural capsaicin (CAPS) treatment on compound action potentials of the superior laryngeal nerve (SLN) afferents were studied in 6 sevoflurane-anesthetized dogs. Perineural CAPS (100 microg/ml) to the bilateral SLNs reduced (P<0.01) the peak and integral amplitudes of the C-wave of the compound action potential. By contrast, the perineural CAPS had no effect on the A-wave component (P>0.05). Removal of the perineural CAPS recovered the C-wave to pretreatment level. The perineural CAPS treatment selectively blocks C-wave compound action potentials of the SLN afferents, providing a useful tool for studies of laryngeal C-fibers in respiratory physiology.