蜱源淋巴细胞脉络丛脑膜炎病毒的分子特征

淋巴细胞脉络丛脑膜炎病毒(lymphocytic chorimeningtis virus,LCMV)是一种经鼠传播的人畜共患病毒。为明确东北地区LCMV在蜱的感染本底,2015年在吉林省采集蜱534只,其中草原革蜱占43.1%;森林革蜱38.4%;长角血蜱11.4%和全沟硬蜱7.1%。将采集蜱按蜱种及地区分组,进行宏病毒组测序,发现蜱感染LCMV。通过RT-PCR检测发现吉林省LCMV蜱感染率为3.5%,其中长角血蜱、草原革蜱、森林革蜱和全沟硬蜱感染率分别为12.2%,2.5%,4.4%和2.5%,长角血蜱携带率最高。通过全基因组测序获得LCMV全基因组序列,并对其进行遗传进化分析,结果表明东北地区蜱感染的LCMV属于基因Ⅰ型,提示蜱可能作为LCMV的传播媒介。本研究确定了东北地区蜱的LCMV感染率及基因型,为LCMV的防控监测提供科学依据。     

重穗型水稻品种Ⅱ优6078物质积累与运转的研究

研究了重穗型水稻品种Ⅱ优6078冗余度、库容量、物质积累等指标与产量的关系.结果表明:Ⅱ优6078最佳冗余度比汕优63(对照)降低10.39%,库容量提高11.51%,颖花数提高15.55%;在生育后期,光合产物向穗部运转比汕优63强,群体单位面积生物量提高9.1%,单株物质积累量比汕优63多60%.     

Scheduling Viability Tests for Seeds in Long-Term Storage Based on a Bayesian Multi-Level Model

Genebank managers conduct viability tests on stored seeds so they can replace lots that have viability near a critical threshold, such as 50 or 85?% germination. Currently, these tests are typically scheduled at uniform intervals; testing every 5 years is common. A?manager needs to balance the cost of an additional test against the possibility of losing a seed lot due to late retesting. We developed a data-informed method to schedule viability tests for a collection of 2,833 maize seed lots with 3 to 7 completed viability tests per lot. Given these historical data reporting on seed viability at arbitrary times, we fit a hierarchical Bayesian seed-viability model with random seed lot specific coefficients. The posterior distribution of the predicted time to cross below a critical threshold was estimated for each seed lot. We recommend a predicted quantile as a retest time, chosen to balance the importance of catching quickly decaying lots against the cost of premature tests. The method can be used with any seed-viability model; we focused on two, the Avrami viability curve and a quadratic curve that accounts for seed after-ripening. After fitting both models, we found that the quadratic curve gave more plausible predictions than did the Avrami curve. Also, a receiver operating characteristic (ROC) curve analysis and a follow-up test demonstrated that a 0.05 quantile yields reasonable predictions.     

RZWQM simulated effects of crop rotation, tillage, and controlled drainage on crop yield and nitrate-N loss in drain flow

Accurate simulation of agricultural management effects on N loss in tile drainage is vitally important for understanding hypoxia in the Gulf of Mexico. An experimental study was initiated in 1978 at Nashua, Iowa of the USA to study long-term effects of tillage, crop rotation, and N management practices on subsurface drainage flow and associated N losses. The Root Zone Water Quality Model (RZWQM) was applied to evaluate various management effects in several previous studies. In this study, the simulation results were further analyzed for management effects (tillage, crop rotation, and controlled drainage) on crop production and N loss in drain flow. RZWQM simulated the observed increase in N concentration in drain flow with increasing tillage intensity from NT (no-till) to RT (ridge till) to CP (chisel plow) and to MP (moldboard plow). It also adequately simulated tillage effects on yearly drain flow and yearly N loss in drain flow. However, the model failed to simulate lower corn and soybean yields under NT than under MP, CP, and RT. On the other hand, RZWQM adequately simulated lower yearly drain flow and lower flow-weighted N concentration in drain flow under CS (corn-soybean) and SC (soybean-corn) than under CC (continuous corn). The model adequately simulated higher corn yield under CS and SC than under CC. Applying the newly suggested N management practice for the Midwest of controlled drainage, the model simulated a 30% reduction in drain flow and a 29% decrease in N losses in drain flow under controlled drainage (CD) compared to free drainage (FD). With most of the simulations in reasonably close agreement with observations, we concluded that RZWQM is a promising tool for quantifying the relative effects of tillage, crop rotation, and controlled drainage on N loss in drainage flow. Further improvements on simulated management effects on crop yield and N mineralization are needed, however.     

Economic development and biotechnology: Public policy response to the farm crisis in Iowa

In periods of social crisis, policymakers become particularly vulnerable to interest groups mobilizing to compete for scarce funds. At this point, legislators are no longer able to address the specific needs of their primary constituency directly, but rather are forced to do so in pretext only. New, unfamiliar technologies provide ample ammunition for astute interest groups to take advantage of times of economic turmoil and maneuver for policy support through dramatic campaigns of “salesmanship.” By publicizing a crisis situation, dramatizing it effectively, and advertising an innovation as the solution to the crisis, legislators may be effectively persuaded to give priority to interest group pressures above and beyond those of the local constituency. Iowa's attempts to address the farm crisis through economic development strategies relying on biotechnology is examined in this paper. The results of extensive surveys of Iowa's legislators and farmers are examined and the consequences for Iowa's policy process of using biotechnology under the auspices of economic development are discussed.     

A MYELOGRAPHIC TECHNIQUE FOR AVIAN SPECIES

A post-mortem myelogram was used to diagnose a vertebral fracture in a Red-tailed Hawk ( Buteo jamaicenis ). This diagnosis led the authors to believe that myelography would be useful in live birds. In a pilot study using live adult female chickens (Gallus domesticus) , mammalian myelographic techniques were modified for avian anatomic differences. A thoracolumbar puncture site was used rather than the lumbar or cisternal site which is commonly used in mammals. The volume of contrast medium needed to produce a diagnostic myelogram in birds(0.8–1.2 ml/kg) was found to be approximately four times that needed in mammals. A 25 gauge spinal needle was used rather than a 23 gauge needle. Myelograms of diagnostic quality were obtained with normal subject recovery. Seizures, the most common post-myelographic complication in mammals, were not observed in any of the birds studied. Avian myelography was found to be a cost effective and humane technique with potential application to avian practice.     

The State‐by‐State Economic Impacts of the 2002 Shutdown of the Los Angeles–Long Beach Ports

In previous research, the economic impacts of temporary shutdowns of the Los Angeles–Long Beach harbors were simulated after a hypothetical terrorist attack, applying the National Interstate Economic Model to estimate state‐by‐state as well as interindustry impacts. However, the unpredictable characteristic of terrorist attacks might not be applicable to the case of a ports shutdown such as the one caused by the lockout of September–October 2002. Market participants can be expected to have contingency plans based on anticipations of a strike or shutdown. Can we identify any of these in terms of the use of alternate ports, in terms of alternate modes or even alternate time periods? The purpose of this study is to examine these questions. The approach is elaborated by testing for the possible effects of trade diversion to other West Coast ports, transportation modes, and intertemporal substitutions. We use data from WISERTrade describing commodity‐specific trade for the major West Coast ports before, during, and after the 11‐day shutdown of the fall of 2002. Shippers’ ability to divert trade is a key ingredient in the economy's ability to withstand attacks and disruptions. The work estimates the impacts on 47 industrial sectors across 50 states (and the District of Columbia).     

Linkages among agronomic,environmental and weed management characteristics in North American sweet corn

Much of our understanding of weed communities and their interactions with crops comes from studies conducted at, or below, the spatial scale of individual fields. This scale allows for tight control of experimental variables, but systematically ignores the potential for regional-scale environmental variation to affect agronomic operations and thereby influence weed management outcomes. We quantified linkages among agronomic, environmental and weed management characteristics of 174 commercial sweet corn fields throughout the north central United States and evaluated crop and weed responses to these variables using classification and regression tree (CART) analysis. Multi-model selection indicated that characteristics of weed management systems, especially total cost and herbicide rate, were important predictors of weed diversity, interference and fecundity. Adding agronomic variables, such as planting date, or environmental variables, such as latitude, explained additional variation in weed floristic measures. We tested yield predictions of the most parsimonious CART model against a verification data set comprised of over 1500 published observations from 25 experiments conducted in the major North American regions where sweet corn is grown for processing. Yield values fell within the 95% confidence interval of observed data for most branches of the tree, suggesting the experimental and analytical approaches were reasonably robust. Several characteristics favoring sweet corn productivity and weed management sustainability were identified. This work resulted in easily interpretable models, both by scientists and producers, which place crop and weed responses within the context of regional-scale variation in agricultural management and the environment.     

云南河口地区香蕉褐缘灰斑病的发生规律研究

对云南河口地区香蕉褐缘灰斑病（BananaSigatokaLeMSpotDisease）进行研究,结果表明：病害的发生、发展规律主要受温度和降雨量的影响;春季气温回升时开始发病,10～11月危害达到高峰值;不同地理环境危害程度有明显差异．病情指数东部地区（11．81）〉中南部地区（10．40）〉西部地区（7．94）,但危害的基本规律是低海拔地区比高海拔地区先发病．且发病程度比高海拔地区严重,病情指数随着海拔的升高而降低。     

Estimation of (co)variance components for birth weight in Nellore cattle using alternative data editing criteria

The aim of this study was to estimate the (co)variance components and breeding values for birthweight (BW) in Nellore cattle by considering or not identical weights that exhibit a high frequency within the contemporary group (CG). A total of 175,258 BW records of Nellore cattle born between 2002 and 2018 were used. The CG was formed by farm, year of birth, sex and feeding regime at birth. CGs with more than 16% of identical BW values were eliminated, generating a data file called BWd. Another file was created without removing these animals (BWt). A mixed linear model was used for statistical analysis, which included fixed and random effects. In both data files analysed, single-trait analysis was performed by Bayesian inference. The mean direct and maternal heritability for BW and the correlation between direct and maternal effects were 0.27, 0.07 and −0.07 for BWt, respectively, and 0.30, 0.093 and −0.07 for BWd. This method should affect the estimation of genetic merits of animals for BW, providing greater safety in the choice of sires.