Optimal length of leys in an area with winter damage problems     

G. Lien  A. R. Kristensen†  A. Hegrenes  J. B. Hardaker‡ 《Grass and Forage Science》2003,58(2):168-177

A model is presented to investigate the optimal economic life cycle of grass leys with winter damage problems in northern Norway and to determine the threshold of winter damage before it is profitable to reseed. A two‐level hierarchic Markov process has been constructed using the MLHMP software (the MLHMP software and the plug‐in constructed for this model are available for download at http://www.prodstyr.ihh.kvl.dk/software/mlhmp.html ). The model takes uncertainty concerning yield potential, damage estimation and weather‐dependent random fluctuations into account. A Kalman filter technique is used for updating the knowledge of yield potential and damage level. The application of the model is demonstrated using data from two commercial Norwegian farms. As parameter estimates vary considerably among farms, it is concluded that decision support concerning optimal economic life cycle of grass leys should be done at farm level. The results also show the importance of using a flexible dynamic replacement strategy. Use of the model for specific farm situations is illustrated.  相似文献   

Risk and economic sustainability of crop farming systems     

Gudbrand Lien  J. Brian Hardaker  Ola Flaten 《Agricultural Systems》2007

In economic terms, resilience in farming has to do with the capacity of a farm business to survive various risks and other shocks. Despite its importance, resilience has seldom been directly considered in evaluations of economic sustainability. A whole-farm stochastic simulation model over a 6-year planning horizon was used to analyse organic and conventional cropping systems using a model of a representative farm in Eastern Norway. The relative economic sustainability of alternative systems under changing assumptions about future technology and price regimes was examined in terms of financial survival to the end of the planning period. The same alternatives were also compared in terms of stochastic efficiency. To model the risk of business failure adequately there is a need to deal with the risk of bankruptcy, and a modification of traditional analysis was used for that purpose. The organic farming system was found to be somewhat less economically sustainable than the conventional system, especially if the organic price premiums and the organic area payments were to be phased out. The results illustrate possible conflicts between pursuit of risk efficiency and economic sustainability. The model developed could be used to support farmers’ choices between farming systems as well as to help policy makers develop more sharply targeted policies.  相似文献   

Effects of Chemical Activation Treatment on Development of Swamp Buffalo (Bubalus bubalis) Oocytes Matured In Vitro and Fertilized by Intracytoplasmic Sperm Injection     

YY Liang  DN Ye  C Laowtammathron  T Phermthai  T Nagai  T Somfai  R Parnpai 《Reproduction in domestic animals》2011,46(1):e67-e73

The objective of this study was to optimize the activation protocol for buffalo oocytes after intracytoplasmic sperm injection (ICSI). The release of the second polar body (PB) at 3, 6 and 9 h after ICSI of in‐vitro matured oocytes activated either with 5 μm ionomycin (Io) or with 7% ethanol (EtOH) was preliminary examined. The highest rate of second PB extrusion occurred at 3 h of activation, and the second PB extrusion in EtOH group was significantly higher than that in Io group. Oocytes that extruded the second PB were selected and cultured either with 1.9 mm 6‐dimethylaminopurine (6‐DMAP) for 3 h or with 10 μg/ml cycloheximide (CHX) for 5 h. Significantly higher rate of oocytes formed 2 pronuclei in EtOH combined with CHX (EtOH + CHX) (62%) group compared to those of Io + CHX (42%) and EtOH + 6‐DMAP (48%) groups (p < 0.01) whereas Io + 6‐DMAP group showed intermediate value (58%). Significantly higher blastocyst formation rates were obtained in Io + 6‐DMAP (29%) and EtOH + CHX (24%) groups than in Io + CHX (6%) and EtOH + 6‐DMAP (17%) groups. Our results indicate that buffalo ICSI oocytes are effectively activated by combination treatment of Io with 6‐DMAP and EtOH with CHX resulting in the highest cleavage and blastocyst formation rates.  相似文献   

Co-incubation with IL-18 potentiates antigen-specific IFN-γ response in a whole-blood stimulation assay for measurement of cell-mediated immune responses in pigs experimentally infected with Lawsonia intracellularis     

Riber U  Boesen HT  Jakobsen JT  Nguyen LT  Jungersen G 《Veterinary immunology and immunopathology》2011,139(2-4):257-263

The whole-blood interferon-gamma (IFN-γ) assay is a quantitative in vitro assay for a direct read-out of Ag-specific cell-mediated immune (CMI) responses to infectious diseases. The IFN-γ assay is robust in severe intracellular infections like Brucella or mycobacteria, but more difficult to evaluate for less severe or immunocompromising infections. Here we investigated the performance of the assay when recombinant co-stimulatory cytokines IL-12 and/or IL-18 were added along with Ag or PBS to cultures of whole-blood from pigs infected with Lawsonia intracellularis. In pigs recovering from a natural infection, addition of rIL-12 or rIL-18 alone increased the Ag-specific IFN-γ release while addition of both cytokines resulted in increased IFN-γ release also in PBS cultures. In analyses after experimental infections with L. intracellularis, significant increased levels of Ag-specific IFN-γ production were measured in Ag+rIL-18 cultures from infected pigs compared to the background response in PBS+rIL-18 control samples (p<0.01) or to Ag+rIL-18 cultures from non-inoculated control pigs (p<0.05). Flow cytometry identified two lymphocyte subsets as the Ag-specific IFN-γ producers. The highest IFN-γ production was by CD4(+)CD8(+) cells while a more numerous population of CD4(-)CD8(+) cells produced lower amounts of IFN-γ in response to rIL-18 and L. intracellularis Ag.  相似文献   

fgf20 is essential for initiating zebrafish fin regeneration   总被引：1，自引：0，他引：1  

Whitehead GG  Makino S  Lien CL  Keating MT 《Science (New York, N.Y.)》2005,310(5756):1957-1960

Epimorphic regeneration requires the presence or creation of pluripotent cells capable of reproducing lost organs. Zebrafish fin regeneration is mediated by the creation of blastema cells. Here, we characterize the devoid of blastema (dob) mutant that fails fin regeneration during initial steps, forms abnormal regeneration epithelium, and does not form blastema. This mutation has no impact on embryonic survival. Dob results from an fgf20a null mutation, Y148S. Fgf20a is expressed during initiation of fin regeneration at the epithelial-mesenchymal boundary and later overlaps with the blastema marker msxb. Thus, fgf20a has a regeneration-specific requirement, initiating fin regeneration, and controlling blastema formation.  相似文献   

Evidence from cassette mutagenesis for a structure-function motif in a protein of unknown structure   总被引：3，自引：0，他引：3  

N D Clarke  D C Lien  P Schimmel 《Science (New York, N.Y.)》1988,240(4851):521-523

The three-dimensional structure of most enzymes is unknown; however, many enzymes may have structural motifs similar to those in the known structures of functionally related enzymes. Evidence is presented that an enzyme of unknown structure [Ile-transfer RNA (tRNA) synthetase] may share a functionally important structural motif with an enzyme of related function (Tyr-tRNA synthetase). This approach involves (i) identifying segments of Ile-tRNA synthetase that have been unusually conserved during evolution, (ii) predicting the function of one such segment by assuming a structural relation between Ile-tRNA synthetase and Tyr-tRNA synthetase, and (iii) testing the predicted function by mutagenesis and subsequent biochemical analysis. Random mutations were introduced by cassette mutagenesis into a ten-amino-acid segment of Ile-tRNA synthetase that was predicted to be involved in the formation of the binding site for isoleucine. Few amino acid substitutions appear to be tolerated in this region. However, one substitution (independently isolated twice) increased the Michaelis constant Km for isoleucine in the adenylate synthesis reaction by greater than 6000-fold, but had little effect on the Km for adenosine triphosphate, the apparent Km for tRNA, or the rate constant kcat.  相似文献   

Targeted Isolation of Xenicane Diterpenoids From Taiwanese Soft Coral Asterospicularia laurae     

Yu-Chi Lin  Yi-Jen Chen  Shu-Rong Chen  Wan-Ju Lien  Hsueh-Wei Chang  Yu-Liang Yang  Chia-Ching Liaw  Jui-Hsin Su  Ching-Yeu Chen  Yuan-Bin Cheng 《Marine drugs》2021,19(3)

Application of LC-MS/MS-based molecular networking indicated the ethanol extract of octocoral Asterospicularia laurae is a potential source for the discovery of new xenicane derivatives. A natural product investigation of this soft coral resulted in the isolation of four new xenicane diterpenoids, asterolaurins O–R (1–4), together with six known compounds, xeniolide-A (5), isoxeniolide-A (6), xeniolide-B (7), 7,8-epoxyxeniolide-B (8), 7,8-oxido-isoxeniolide-A (9), and 9-hydroxyxeniolide-F (10). The structures of isolated compounds were characterized by employing spectroscopic analyses, including 2D-NMR (COSY, HMQC, HMBC, and NOESY) and high-resolution electrospray ionization mass spectrometry (HRESIMS). Asterolaurin O is the first case of brominated tricarbocyclic type floridicin in the family Xeniidae. Concerning bioactivity, the cytotoxic activity of those isolates was evaluated. As a result, compounds 1 and 2 demonstrated a selective cytotoxic effect against the MCF-7 cell line at IC₅₀ of 14.7 and 25.1 μM, respectively.  相似文献   

沥青混合料配合比设计应注意的问题     

隋立恩  于立成 《林业科技情报》2010,42(2):102-103

热拌沥青混合料配合比组成设计是否合理,直接影响沥青砼路面的路用性能。本文对试验人员进行配合比设计时,如何规范操作和进行数据分析,减小试验数据的变异性以及优化沥青混合料配合比组成设计应注意的事项进行了论述。  相似文献   

Associations among systemic blood pressure,microalbuminuria and albuminuria in dogs affected with pituitary- and adrenal-dependent hyperadrenocorticism     

Yu-Hsin Lien  Tsai-Yuan Hsiang  Hui-Pi Huang 《Acta veterinaria Scandinavica》2010,52(1):61

Background

Hypertension and proteinuria are medical complications associated with the multisystemic effects of long-term hypercortisolism in dogs with hyperadrenocorticism (HAC).

Methods

This study investigated the relationships among adrenocorticotropic hormone (ACTH)-stimulation test results, systemic blood pressure, and microalbuminuria in clinically-healthy dogs (n = 100), in dogs affected with naturally occurring pituitary-dependent (PDH; n = 40), or adrenal-dependent hyperadrenocorticism (ADH; n = 30).

Results

Mean systemic blood pressure was similar between clinically healthy dogs and dogs with HAC (p = 0.803). However the incidence of hypertension was highest in dogs with ADH (p = 0.017), followed by dogs with PDH, with the lowest levels in clinically healthy dogs (p = 0.019). Presence of microalbuminuria and albuminuria in clinically healthy dogs and dogs affected with HAC was significantly different (p < 0.001); incidences of albuminuria followed the same pattern of hypertension; highest incidence in dogs with ADH, and lowest level in clinically healthy dogs; but microalbuminuria showed a different pattern: clinically healthy dogs had highest incidences and dogs with ADH had lowest incidence. The presence of albuminuria was not associated with blood pressure values, regardless of whether dogs were clinically healthy or affected with ADH or PDH (p = 0.306).

Conclusions

Higher incidence of hypertension and albuminuria, not microalbuminuria was seen in dogs affected with HAC compared to clinically healthy dogs; incidence of hypertension and albuminuria was significantly higher in dogs affected with ADH compared to PDH. However, presence of albuminuria was not correlated with systemic blood pressure.  相似文献   

Effects of iodine methionine on boar sperm quality during liquid storage at 17°C          下载免费PDF全文

Q Fang  J Wang  YY Hao  H Li  JX Hu  GS Yang  JH Hu 《Reproduction in domestic animals》2017,52(6):1061-1066

Microbial environment is one of the important factors that affect the quality of preserved semen. Iodine methionine (IM), participating in the production and activation of metabolic enzymes, is a new type of amino acid chelate. To date, there has been no report to evaluate the effects of IM on boar semen preservation at 17°C. This study was designed to investigate the effects of IM on boar sperm quality and reproductive performance during liquid storage at 17°C and its antibacterial effect. Semen samples collected from six Yorkshire boars were diluted with basic liquid containing different concentrations of IM (0, 20, 40, 80, 160 and 320 μM). Subsequently, sperm motility, plasma membrane integrity and acrosome integrity were determined. After 6 days of preservation, the difference in microbial composition between control group and 80 μM IM group was compared using 16S rDNA sequencing, and the effects of IM on reproductive performance were also compared and analysed between the two groups. The results demonstrated that 20, 40 and 80 μM IM improved boar sperm motility, plasma membrane integrity and acrosome integrity. 80 μM IM was the optimum concentration. Conversely, 160 and 320 μM IM resulted in deleterious consequences to boar sperm quality compared to the control group and other treatment groups (p < .05). After 6 days of preservation, sperm motility, plasma membrane integrity and acrosome integrity were 56.0%, 51.8% and 59.4%, respectively. There was no significant difference in non‐return rate between the two groups (p > .05). But the litter size of 80 μM IM group was significantly higher than that of control group (p < .05). 80 μM IM inhibited proliferation of the phylum Proteobacteria and the genus Staphylococcus as well as Pseudomonas (p < .05). Further studies are required to understand the antibacterial mechanism of IM in liquid‐preserved boar semen.  相似文献