VACCINATION AND REDUCED COHORT DURATION CAN DRIVE VIRULENCE EVOLUTION: MAREK’S DISEASE VIRUS AND INDUSTRIALIZED AGRICULTURE

Marek’s disease virus (MDV), a commercially important disease of poultry, has become substantially more virulent over the last 60 years. This evolution was presumably a consequence of changes in virus ecology associated with the intensification of the poultry industry. Here, we assess whether vaccination or reduced host life span could have generated natural selection, which favored more virulent strains. Using previously published experimental data, we estimated viral fitness under a range of cohort durations and vaccine treatments on broiler farms. We found that viral fitness maximized at intermediate virulence, as a result of a trade‐off between virulence and transmission previously reported. Our results suggest that vaccination, acting on this trade‐off, could have led to the evolution of increased virulence. By keeping the host alive, vaccination prolongs infectious periods of virulent strains. Improvements in host genetics and nutrition, which reduced broiler life spans below 50 days, could have also increased the virulence of the circulating MDV strains because shortened cohort duration reduces the impact of host death on viral fitness. These results illustrate the dramatic impact anthropogenic change can potentially have on pathogen virulence.     

冬虫夏草产业化实践和思考

冬虫夏草产业化是众多企业及研究人员关注的热点。本论文基于人工繁育实践,结合相关报道,阐述冬虫夏草产业化现状及存在的问题,旨在展示冬虫夏草人工繁育研究成果,为实现冬虫夏草产业化发展提供思路和参考。     

Describing maize (Zea Mays L.) landrace persistence in the Bajío of Mexico: A survey of 1940s and 1950s collection locations

Passport data for Mexico’s Guanajuato State were used to locate the sites where maize was collected in the 1940s and 1950s in an effort to document and conserve diversity. A map presenting survey points illustrates that collections have occurred repeatedly in the same locations. Observations of these locations reveal that urbanization and industrialization, not high yielding varieties, are displacing traditional varieties. Non-linear principal components analysis was used to assess associations between variables in areas where maize persists. Landraces appear to be associated with mountains and mesas, mixed cropping, little or no access to irrigation and areas classified as having low agricultural capacity; conversely, landraces have more commonly been replaced in areas of high agricultural capacity. The areas of high agriculture capacity, located in the riparian areas and plains, also have been the easiest to develop for urban and industrial use. Increasingly high rates of urbanization and development in areas of high agriculture capacity will impede the conservation of crop diversity in these areas.     

The height of Tennessee convicts: another piece of the “antebellum puzzle”

Average height of the free population in the United States born in the mid-1830s began to decline despite growing per capita incomes. Explanations for this "antebellum puzzle" revolve around a possibly deteriorating disease environment promoted by urban agglomeration and increases in the relative price of protein-rich foods. However, several groups were immune to the effect, including members of the middle class, whose income was high enough, and increased enough to overcome the adverse developments and maintain their nutritional status. Although at the opposite end of the social spectrum, the height of male slaves also increased, as it was in their owners' interest to raise their slaves' food allotments. The height of Tennessee convicts, analyzed in this article, also increased in the late-1830s, being the third exception to the "antebellum puzzle." Mid-19th century Tennessee was integrated into interstate commerce in cotton and tobacco and experienced considerable movement of people who would have brought with them diseases from elsewhere, hence, it would have been integrated into the US disease pool, and the fact that heights did not decline in the 1830s is therefore an indication that the antebellum puzzle cannot be explained exclusively by the spread of diseases. Yet, Tennessee's economy was quite different to that of the rest of the country. Although it did export live swine to the South, these exports did not increase during the antebellum decades. Hence, Tennessee remained self-sufficient in pork, and consumption of pork did not decline. Thus, the evidence presented here is consistent with the economic interpretation of the "antebellum puzzle": self-sufficiency in protein production protected even the members of the lower-classes of Tennessee from the negative externalities associated with the onset of industrialization.     

中国南部沿海增养殖业的调查与展望 ——来自广东饶平柘林湾和南澳深澳湾“海上渔村“的思考

针对沿海增养殖业对海洋生态的影响,对中国南部沿海2个增养殖业发达区——南澳岛深澳湾"海上渔村"和赤潮灾区饶平柘林湾进行了实地考察和取样分析.考察发现,目前中国南部沿海增养殖业普遍存在技术落后、缺乏科学技术指导和统一管理等问题, 对海洋生态造成了极大的危害;通过海水水质测定实验,发现这2个养殖区水样的平均含氮量较高(2.154 mg/L),氮磷质量比较高(22),处于富营养化状态;浮游植物平均密度较高(1 908.6个/mL),个体含叶绿素a量较低(1.74×10-6 mg/个),出现生态衰退现象.     

生命伦理学视野下的转基因作物产业化问题研究

转基因作物的产业化作为当前生命伦理学的重要问题之一日益受到我国学术界、政府和广大公众的关注。转基因作物产业化不仅关涉到我国13亿人的吃饭问题,也与我国公众的身心健康、基本权利密切相关。转基因作物产业化的生命伦理意蕴主要体现在：转基因作物产业化的基础是确保公众健康与生命安全,关键是尊重公众权利,核心是促进社会公正。     

The Not-so-Dark Ages: ecology for human growth in medieval and early twentieth century Portugal as inferred from skeletal growth profiles

This study attempts to address the issue of relative living standards in Portuguese medieval and early 20th century periods. Since the growth of children provides a good measure of environmental quality for the overall population, the skeletal growth profiles of medieval Leiria and early 20th century Lisbon were compared. Results show that growth in femur length of medieval children did not differ significantly from that of early 20th century children, but after puberty medieval adolescents seem to have recovered, as they have significantly longer femora as adults. This is suggestive of greater potential for catch-up growth in medieval adolescents. We suggest that this results from distinct child labor practices, which impact differentially on the growth of Leiria and Lisbon adolescents. Work for medieval children and adolescents were related to family activities, and care and attention were provided by family members. Conversely, in early 20th century Lisbon children were more often sent to factories at around 12 years of age as an extra source of family income, where they were exploited for their labor. Since medieval and early 20th century children were stunted at an early age, greater potential for catch-up growth in medieval adolescents results from exhausting work being added to modern adolescent's burdens of disease and poor diet, when they entered the labor market. Although early 20th century Lisbon did not differ in overall unfavorable living conditions from medieval Leiria, after puberty different child labor practices may have placed modern adolescents at greater risk of undernutrition and poor growth.     

内蒙古半干旱生态脆弱矿区生态修复耦合机理与产业模式

近年,煤炭开采带动矿区经济发展的同时也造成了严重的生态环境问题。由此产生生态修复和土地复垦产业延伸的生态环境治理和矿区产业调整优化方面研究热点,二者形成的耦合系统可在恢复受损土地的同时,以治理和循环生产为契机延伸产业链。受损地形重塑及边开采边恢复技术开发及应用形成安全稳定地形条件是前提,其次是土壤的恢复重构,在当地条件下迅速恢复具备良好理化性质,供植被和经济能源作物生长和景观格局构建,最终形成修复产业和生态产业的价值创造平台。根据耦合系统的工艺特点,每年内蒙矿区利用该耦合系统以矿区受损土地修复进行循环生产生态修复产品的潜力约21915.51万吨和经济能源作物的潜力约21.15万t。     

Do you have to be tall and educated to be a migrant? Evidence from Spanish recruitment records, 1890–1950

We use Spanish military records stemming from the late-19th to the mid-20th century to assess internal migrants’ self-selection. We find that migrants were, on average over the whole period, around one centimeter taller than non-migrants, and in the booming 1920s, the height advantage of movers reached three centimeters. The positive self-selection was larger for migrants originating in poorer provinces and traveling longer distances. A further finding is that migrants were positively selected in terms of literacy and socio-economic status according to their occupation. Professionals were most likely to have migrated internally and farmers least.