Nudivirus Sequences Identified from the Southern and Western Corn Rootworms (Coleoptera: Chrysomelidae)

Analysis of pooled genomic short read sequence data revealed the presence of nudivirus-derived sequences from U.S. populations of both southern corn rootworm (SCR, Diabrotica undecimpunctata howardi Barber) and western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte). A near complete nudivirus genome sequence was assembled from sequence data for an SCR population with relatively high viral titers. A total of 147,179 bp was assembled from five contigs that collectively encode 109 putative open reading frames (ORFs) including 20 nudivirus core genes. In contrast, genome sequence recovery was incomplete for a second nudivirus from WCR, although sequences derived from this virus were present in three geographically dispersed populations. Only 48,989 bp were assembled with 48 putative ORFs including 13 core genes, representing about 20% of a typical nudivirus genome. Phylogenetic analysis indicated that both corn rootworm nudiviruses grouped with the third known nudivirus of beetles, Oryctes rhinoceros nudivirus in the genus Alphanudivirus. On the basis of phylogenetic and additional analyses, we propose further taxonomic separation of nudiviruses within Alphanudivirus and Betanudivirus into two subfamilies and five genera. Identification of nudivirus-derived sequences from two species of corn rootworm highlights the diversity of viruses associated with these agricultural insect pests.     

Role of a gamma‐aminobutryic acid (GABA) receptor mutation in the evolution and spread of Diabrotica virgifera virgifera resistance to cyclodiene insecticides

The western corn rootworm, Diabrotica virgifera virgifera, is a damaging pest of cultivated corn that was controlled by applications of cyclodiene insecticides from the late 1940s until resistance evolved ∼10 years later. Range expansion from the western plains into eastern USA coincides with resistance development. An alanine to serine amino acid substitution within the Rdl subunit of the gamma‐aminobutyric acid (GABA) receptor confers resistance to cyclodiene insecticides in many species. We found that the non‐synonymous single nucleotide polymorphism (SNP) G/T at the GABA receptor cDNA position 838 (G/T⁸³⁸) of D. v. virgifera resulted in the alanine to serine change, and the codominant SNP allele T⁸³⁸ was genetically linked to survival of beetles in aldrin bioassays. A phenotypic gradient of decreasing susceptibility from west to east was correlated with higher frequencies of the resistance‐conferring T⁸³⁸ allele in the eastern‐most populations. This pattern exists in opposition to perceived selective pressures since the more eastern and most resistant populations probably experienced reduced exposure. The reasons for the observed distribution are uncertain, but historical records of the range expansion combined with the distribution of susceptible and resistant phenotypes and genotypes provide an opportunity to better understand factors affecting the species' range expansion.     

Identification and Quantification of a Toxigenic and Non-Toxigenic Aspergillus flavus Strain in Contaminated Maize Using Quantitative Real-Time PCR

Aflatoxins, which are produced by Aspergillus flavus, are toxic to humans, livestock, and pets. The value of maize (Zea mays) grain is markedly reduced when contaminated with aflatoxin. Plant resistance and biological control using non-toxin producing strains are considered effective strategies for reducing aflatoxin accumulation in maize grain. Distinguishing between the toxin and non-toxin producing strains is important in determining the effectiveness of bio-control strategies and understanding inter-strain interactions. Using polymorphisms found in the fungal rRNA intergenic spacer region (IGS) between a toxigenic strain of A. flavus (NRRL 3357) and the non-toxigenic strain used in the biological control agent Afla-Guard^® (NRRL 21882), we developed a set of primers that allows for the identification and quantification of the two strains using quantitative PCR. This primer set has been used to screen maize grain that was inoculated with the two strains individually and co-inoculated with both strains, and it has been shown to be effective in both the identification and quantification of both strains. Screening of co-inoculated ears from multiple resistant and susceptible genotypic crosses revealed no significant differences in fungal biomass accumulation of either strain in the field tests from 2010 and 2011 when compared across the means of all genotypes. Only one genotype/year combination showed significant differences in strain accumulation. Aflatoxin accumulation analysis showed that, as expected, genotypes inoculated with the toxigenic strain accumulated more aflatoxin than when co-inoculated with both strains or inoculated with only the non-toxigenic strain. Furthermore, accumulation of toxigenic fungal mass was significantly correlated with aflatoxin accumulation while non-toxigenic fungal accumulation was not. This primer set will allow researchers to better determine how the two fungal strains compete on the maize ear and investigate the interaction between different maize lines and these A. flavus strains.     

Formation of trans fatty acids during the frying of chicken fillet in corn oil

To assess effects of heated edible oils on intake of trans fatty acids (TFAs); the formation of TFAs in cooking conditions was investigated by a frying system model, in which chicken fillet was fried in a commercial corn oil at 170?°C, for 12 frying cycles. The main TFAs detected in chicken fillet were trans C18:2 fatty acids (FAs) and trans C18:3 FAs, which exhibited no significant differences among the frying cycles. Besides, the content of trans C18:1 FAs were very low in all samples on different frying cycles. The intake of TFAs was estimated to be 0.06?g/100?g when chicken fillet fried in this process was consumed. These results suggest that an ordinary frying process upon a commercial corn oil has little impact on the daily TFAs intake.     

玉米肽对微波辐射大鼠肝组织损伤的治疗作用

目的：探讨玉米肽对微波辐射引起动物肝细胞肝组织损伤的治疗作用。方法36只Wistar大鼠随机分为正常对照组、辐射模型组和辐射给药组,辐射模型组和辐射给药组大鼠给予100 mW/cm2的微波辐照6 min,辐射给药组辐射后给予600 mg/（ kg· d）玉米肽,连续7 d。7 d后处死大鼠,光学显微镜观察肝细胞形态学变化,检测大鼠血清中乳酸脱氢酶（LDH）、丙二醛（MDA）、超氧化物歧化酶（SOD）、谷丙转氨酶（ALT）活性。结果与对照组比较,辐射模型组肝细胞体积增大,细胞核形态不规则,细胞水肿严重,细胞之间界限不明显,胞质淡染,肝血窦明显缩小或消失。血清LDH显著升高（ P＜0．05）, MDA和ALT含量升高极为显著（ P＜0．01）,SOD含量极显著下降（P＜0．01）。辐射给药组血清ALT含量显著升高（P＜0．05）。与辐射模型组比较,辐射给药组肝组织结构有明显恢复,肝细胞水肿明显减轻,细胞边界较清晰。血清ALT含量下降极为显著（P＜0．01）,SOD活性显著升高（P＜0．05）,LDH和MDA呈下降趋势。结论100 mW/cm2的微波辐照可引起大鼠肝组织损伤,玉米肽对微波辐射引起的肝组织损伤有一定的治疗效果。     

*研究快报*玉米秸秆水解液的黑曲霉发酵生产高浓度柠檬酸

柠檬酸是在饮料、制药、化妆品等领域有广泛应用的重要有机酸。利用玉米秸秆等木质纤维素原料生产柠檬酸可以显著降低其生产成本。目前,木质纤维素柠檬酸发酵的技术指标偏低,不具备工业应用价值。本文以黑曲霉Aspergillus niger SIIM M288为发酵菌株,以干法稀酸预处理和生物脱毒后获得的玉米秸秆酶水解液为原料,在优化条件下柠檬酸发酵质量浓度达到97.45 g/L,相对于葡萄糖的得率达到了87.27%,是迄今为止所有报道的最高指标,已经接近以淀粉为原料的柠檬酸发酵指标。这一结果为以木质纤维素为原料生产柠檬酸的技术产业化提供了重要的依据。     

From the Cover: Genetic erosion in maize’s center of origin

Crop genetic diversity is an indispensable resource for farmers and professional breeders responding to changing climate, pests, and diseases. Anecdotal appraisals in centers of crop origin have suggested serious threats to this diversity for over half a century. However, a nationwide inventory recently found all maize races previously described for Mexico, including some formerly considered nearly extinct. A flurry of social studies seems to confirm that farmers maintain considerable diversity. Here, we compare estimates of maize diversity from case studies over the past 15 y with nationally and regionally representative matched longitudinal data from farmers across rural Mexico. Our findings reveal an increasing bias in inferences based on case study results and widespread loss of diversity. Cross-sectional, case study data suggest that farm-level richness has increased by 0.04 y⁻¹ nationwide; however, direct estimates using matched longitudinal data reveal that richness dropped −0.04 y⁻¹ between 2002 and 2007, from 1.43 to 1.22 varieties per farm. Varietal losses occurred across regions and altitudinal zones, and regardless of farm turnover within the sector. Extinction of local maize populations may not have resulted in an immediate loss of alleles, but low varietal richness and changes in maize’s metapopulation dynamics may prevent farmers from accessing germplasm suitable to a rapidly changing climate. Declining yields could then lead farmers to leave the sector and result in a further loss of diversity. Similarities in research approaches across crops suggest that methodological biases could conceal a loss of diversity at other centers of crop origin.A decade ago, crop scientists considered maize (Zea mays L.) diversity in danger across wide areas of Mexico, its center of origin and diversity: seven races at risk for extinction and many others under threat (1, 2). However, those appraisals, like others before them (3, 4), were anecdotal. In 2011, the Global Project on Native Maize—a 3-y effort involving 55 institutions and 138 researchers—reported encouraging findings from its first nationwide inventory: all 59 races previously described for Mexico were recorded, including those formerly considered nearly extinct (5). Scientists also found unexpectedly high diversity of races endemic to northern Mexico, several maize types in Michoacán that could represent new races, and new records for some locations (including Vandeño in Sonora and four Guatemalan races). Contrary to previous appraisals, only two races (Palomero Toluqueño and Chapalote) were listed under threat based on small population sizes. Leading experts remain cautious nevertheless (6).Crop genetic erosion has been a constant concern since the late 1940s, when conservation efforts began in earnest, but it has never been demonstrated by longitudinal data across environments for any major crop in its center of diversity (3, 4, 7–10). Inconsistencies in the classification of infraspecific diversity have been a serious hurdle. Utilitarian rather than natural, taxonomies reflect large disciplinary biases: crop scientists favor racial groupings, whereas social scientists prefer folk taxonomies (1–6, 9–14). Phenotypic variation across races is indeed remarkable (1, 2, 5, 6, 15, 16), yet racial groups account for only 2–3% of genetic variation in maize (6). Moreover, races are not discrete entities (13–15). Farmers recognize, value, and maintain unique traits in innumerable racial variants and mixtures—known as farmer varieties or landraces—exerting an influence on maize’s genetic structure (12–14, 17). Seed exchange presumably explains why 91% of isoenzymatic variation in maize landraces occurs within populations, whereas individual teosinte (wild Z. mays) populations remain genetically distinct (6, 18). The low genetic diversity of some accessions also has been attributed to human factors—i.e., small field sizes (or few ears used for seed) for specialty varieties (1). In fact, most maize alleles are very rare (frequencies <0.01), and many are found in single accessions that presumably correspond with farmer fields (1). Rather than segregated into discrete races, maize diversity may be spread continuously across thousands of populations (i.e., fields) in rural Mexico (13, 14, 17, 18). Accounting for maize’s metapopulation structure is difficult because of farmers’ extensive control of crop population dynamics (11, 13). Although maize demography can be modeled on management practices, the data required remain critically scarce (11, 19). Numerous statistics have been reported, but only average varietal richness per farm is estimated consistently across studies. This is considered the key statistic for diversity conservation in crops (10).We compare farm richness estimates based on cross-sectional case study data and longitudinal survey data from a representative sample of rural farms to assess the state of maize conservation in Mexico. Our findings reveal significant changes in maize diversity between 2002 and 2007 that are not evident in case study data. This represents the first (to our knowledge) formal assessment of genetic erosion in a center of crop diversity. A social perspective on maize diversity allows us to explore possible reasons for recent changes and their potential implications.     

Toward an animal model of chronic pancreatitis

Summary There is currently no reproducible model of the painful and lithogenic disease, chronic pancreatitis. Its biphasic evolution, from acinar cell hyperplasia and hyperactivity toward effacement of enzyme as well as bicarbonate secretory parenchyma, would be rationalized if it was linked to induction of cytochrome P450 mono-oxygenases (CYP): the increased oxidant load from long-term CYP induction eventually erodes micronutrient antioxidant defenses to injure cells. This philosophy would also rationalize the reported hepatobiliary aberrations associated with the human disease, including increases in free radical oxidation products in bile. Accordingly pancreatic and biliary secretions were studied in Syrian golden hamsters that were reared for 6 mo on low or high (16% corn oil) fat diets that were supplemented with a prototype inducer of CYP2 (200 ppm phenobarbitone) or CYP1 (100 ppm β naphthoflavone) enzyme families, with or without a putative enzyme inhibitor (400 ppm cimetidine). The drugs did not alter the reduction in flowrate or bicarbonate concentration of pancreatic juice caused by the high fat diet alone, but, in contrast, evoked pancreatic protein hypersecretion in a number of animals. β naphthoflavone, but not phenobarbitone, augmented the output of biliary lipid peroxidation products irrespective of dietary fat content and cimetidine cotreatment with either inducer did the same. We conclude: (1) that drug modifiers of CYP magnify the deleterious pancreatobiliary effects of corn oil-enriched diets and draw them closer to those found in human chronic pancreatitis; (2) that these functional derangements are accompanied by pancreatic lipoatrophy; and (3) that long-term CYP induction does not, of its own, cause fibrosis or the ductal abnormalities that generally accompany loss of pancreatic acinar cells in the human disease and, also in contrast, the changes that are caused appear to be painless.     

玉米乳酸饮料的研制

利用玉米生产乳酸饮料工艺为,先将玉米用质量分数0.2%的乳酸在50 ℃的水中浸泡48 h,然后用质量分数0.5%的α-淀粉酶液化、0.6%的糖化酶糖化.将糖化液与鲜牛奶以体积分数14∶6的比例混合进行乳酸发酵,可制出优质保健玉米乳酸饮料.     

血浆置换在抢救酵米面中毒的临床应用

目的　提高酵米面中毒抢救的成功率 ,减少病死率。方法　对 44例酵米面中毒在内科综合治疗基础上部分分别联合血浆置换 (PE)、血液透析、换血治疗 ;15例单纯内科综合治疗 (综合组 )。并对各种疗效进行分析和对比。结果　PE组 18例中 ,治愈 15例 ,死亡 3例 ;血透组 2例中 ,死亡 2例 ;换血组 9例中 ,治愈 5例 ,死亡 4例 ;单纯综合治疗组 15例中 ,死亡 15例。PE与综合组比效差异有高度显著性 (P <0 .0 1)。结论　在内科综合抢救治疗基础上及时配合PE治疗 ,是减少酵米面中毒病死率的重要措施。