林间履带式多功能底盘的设计

针对林间运输需求,提出了履带式多功能底盘的整体设计方案,并对该底盘的几个关键部件进行了设计。     

我国生态农场建设的思考

生态农场作为生态农业的落地载体,兼顾生态环境保护与经济社会可持续发展,具有市场灵活性,在带动农户发展专业化、标准化、绿色化生产方面具有明显优势。新形势下,各地已形成了一批各具特色的生态农场典型案例。2016-2017年,作者重点围绕面源污染防控与农业清洁生产,以我国东部15个省市的468家生态农场为研究对象,制定调查问卷开展典型案例调查研究。研究结果表明,90%的农场成立时间在15年以下,生态农场经营者的平均年龄为47.5岁,土地面积在6.6~16.6 hm²的农场占到40%,土地平均租金为11 040元·hm^-2·a^-1;以公司、合作社和家庭农场为组织形式的农场各占23%、40%和30%;进行了农产品质量认证的农场占到73%;生态农业措施采用率排在前5位的是有机肥/堆肥、人工/机械除草、轮作、清洁田园、杀虫灯/秸秆还田;养殖农场的生态意识较为淡薄,生态措施的采用情况也不乐观。在农场投入方面,种植农场的肥料投入和养殖农场的饲料投入最高,劳动力工资平均在3~4万元·cap.^-1·a^-1;种植农场收益率为-21%~70%,养殖农场为13%~337%,种养结合农场为-21%~152%;50%的农场获得过农业补贴。从调研结果看,我国生态农场有着良好的发展势头,但还处于初级阶段,缺乏相应的指导。文章在调研的基础上还从技术应用、产业融合、成本收益、销售途径及补贴政策等方面分析了生态农场发展过程中面临的问题和挑战,并提出了相应的对策建议,以期对我国生态农场健康有序发展提供指导。     

黄河首曲重大生态功能区护岸林建设问题探讨

分析了河岸防护林改变区域小气候、巩固河岸、保持水土、防风固沙、改良土壤、湿地保护、提供饲料、薪材和增加收入、提高畜牧业生产力、丰富和改善高寒区景观等作用,系统阐述了加强河岸防护林建设的重要性,针对性地提出了河岸防护林树种组成单一、体系结构不够完整、自然因素恶劣等护岸林建设问题,并提出了进一步发展建设的对策,在黄河首曲重大生态功能区的环境建设中加强黄河护岸林建设,对于黄河首曲生态环境的治理、恢复、重建和改善具有十分重要的意义。     

Ontogenetic resource use and trophic dynamics of endangered juvenile Tachypleus tridentatus among diversified nursery habitats in the northern Beibu Gulf,China

Horseshoe crabs, the most well-known example of “living fossils”, are iconic and ecologically important macroinvertebrates in coastal and estuarine ecosystems. Their blood is a crucial resource for manufacturing Limulus or Tachypleus amebocyte lysate to detect bacterial endotoxins or fungal contamination in drug and medical devices. An enhanced understanding of their ecological roles and trophic interactions in the food webs is fundamental to facilitate resource management for the declining populations in Asia. Foraging information of the Asian species, however, is mainly derived from preliminary, scattered reports from a limited number of study locations. In this study, resource utilization, trophic niche dynamics, and trophic interaction of the juvenile tri-spine horseshoe crab, Tachypleus tridentatus (instars 1–12, approximately 0.5–8 years old) across ontogeny was assessed in diversified nursery habitats along the northern Beibu Gulf, China, using carbon and nitrogen stable isotopes. Our results suggest that: (i) T. tridentatus are ecological generalists given the vast range of carbon isotopic values and trophic niche width estimates exhibited between multiple instar groups; (ii) juvenile T. tridentatus across most habitat types predominantly assimilated energy from a variety of basal production sources in the food web, but primarily depended on sedimentary organic matter and seagrass resource pools; (iii) ontogenetic shifts in juvenile dietary proportions were evident, with decreased reliance on sedimentary organic matter, coupled with increased reliance on benthic macroinvertebrate grazers, detritivores, and omnivores with age; and (iv) nearly all juvenile instars occupied similar trophic positions in the food web with slight shifts in trophic position present with increasing size. Our findings indicate that resource availability and ontogenetic diet shifts strongly influence horseshoe crab trophic dynamics, and age should be accounted when formulating habitat conservation measures based on resource use for Asian horseshoe crabs.     

SNAT2介导蛋氨酸对牛乳腺上皮细胞增殖与自噬的调节作用

钠离子依赖性中性氨基酸转运体2（SNAT2）是一种氨基酸转运蛋白，可转运中性氨基酸，广泛分布于多种细胞中。氨基酸既可作为蛋白质合成的底物，也是调节细胞新陈代谢的关键信号分子，但SNAT2是否介导氨基酸调节BMECs增殖和自噬尚未见报道。本研究利用CASY细胞计数和Western blotting技术检测SNAT2过表达和siRNA干扰后牛乳腺上皮细胞（BMECs）增殖情况以及SNAT2对自噬标志蛋白LC3-Ⅰ/Ⅱ表达量的影响，并利用免疫荧光检测细胞自噬斑点（LC3-Ⅱ）变化。结果显示，SNAT2过表达时，p-PI3K、p-mTOR和Cyclin D1表达量增加，反之，p-PI3K、p-mTOR和Cyclin D1表达量下降。SNAT2抑制时，LC3-Ⅱ表达量增加，免疫荧光检测自噬斑点增多。添加自噬增强剂海藻糖（trehalose，Tre）和蛋氨酸（methionine，Met）后，与单一添加Tre组相比，Met+Tre组p-mTOR表达量增加，LC3-Ⅱ表达量降低，胞浆内绿色自噬斑点减少；添加Tre和Met并抑制SNAT2时，p-mTOR表达量下降，LC3-Ⅱ表达量增多，胞浆内绿色自噬斑点增加。以上结果表明，SNAT2可介导Met通过调控PI3K-mTOR/Cyclin D1信号通路调节BMECs的增殖与自噬。     

新疆、内蒙古部分地区乳房炎奶样中金黄色葡萄球菌的流行性与耐药性分析

为确定患乳房炎奶牛乳中金黄色葡萄球菌的流行性和耐药性状况,试验自2018年4月至2018年5月采集了新疆地区70例和内蒙古地区50例患乳房炎奶牛生鲜乳样。通过对奶样中金黄色葡萄球菌进行增菌培养、分离纯化,KB纸片扩散法药敏试验及PCR耐药基因检测发现,新疆和内蒙古地区奶样中金黄色葡萄球菌分离率分别为28.6%和54.0%;新疆地区分离的金黄色葡萄球菌菌株对青霉素G的耐药性最高(75.0%),其次是磺胺异噁唑(60.0%)、林可霉素(55.0%);内蒙古地区的金黄色葡萄球菌菌株同样对青霉素G高度耐受,耐药率为70.4%,其次为林可霉素(63.0%)、克林霉素(51.9%);两地区所分离菌株中,88.9%以上携带多种耐药基因,呈现多重耐药性;两地区所检出的高频耐药基因分别是新疆地区的ermA(30.0%)、dfrS1(30.0%)基因和内蒙古地区的lnuA(46.2%)基因。     

Apoptosis of alveolar wall cells is involved in papain-induced rat pulmonary emphysema

AIM: To observe the apoptosis of alveolar wall cells in the papin-induced rat emphysema, and to explore the role of apoptosis of alveolar wall cells in the pathogenesis of emphysema. METHODS: Rats were randomly divided into three groups: normal control group, papain only group, papain+irradiation group. Morphology of lung tissues was assessed. TUNEL assay was used to determine the apoptotic cells. Immunohistochemistry was performed to determine the expression of PCNA, Bax and SP-C in the lung alveolar wall cells. SP-C immunofluorescence stainging was performed to identify the type II alveolar cells in the TUNEL positive cells. RESULTS: Destruction of alveolar wall and loss of the alveolar unit were observed in papain only group and papain+irradiation group. There was significant difference between rats of papain+irradiation group and papain only growp in the mean linear interval (MLI), the number of alveolar counted per unit area (MAN) and mean alveoli area (MAA), respectively (P<0.01). The proliferation index(PI), apoptosis index (AI) and the percentage of Bax in the papain only group and papain+irradiation group were significantly greater than that in the normal control group (P<0.01). However, the percentage of SP-C positive cells was significantly lower in the papain only group and papain+irradiation group compared with the normal control (P<0.01). Moreover, the PI, AI and the percentage of Bax in the papain+irradiation group was higher than those in the papain only group. The percentage of SP-C positive cells in the papain+irradiation group was lower than that in the papain only group. Most of the TUNEL-positive cells expressed the SP-C. CONCLUSION: Apoptosis of rat alveolar wall cells, especially type-II cell may be involved in the pathogenesis of emphysema. Upregulation of Bax expression may lead to alveolar wall cells apoptosis in papain-induced emphysema.     

叶绿体DNA分析技术及其在栗属植物中的应用

被子植物叶绿体DNA母性遗传,有独立的进化路线,基于叶绿体DNA的分析技术在分子系统学、资源多样性评价、杂种鉴定等方面具有重要作用。栗属植物资源丰富,分布广泛。概述了叶绿体DNA分析技术在栗属植物中的研究进展,阐述了包括PCR-RFLP、DNA杂交、叶绿体SSR标记技术和叶绿体基因区段测序分析技术在内的分子标记技术的原理、特点及其在栗属植物中的应用。并对今后如何开发叶绿体DNA标记用于栗属植物的研究进行了展望。     

基于都市农业背景下的农业科技在农业生产中的作用

农业基础竞争力不强、比较优势逐步丧失等问题逐步成为我国今后一个时期农业面临的最大挑战,科技创新作为农业发展的重要支撑,必须发挥其引领作用,为农业转型升级增加新动能。北京国际都市农业科技园作为现代农业科技示范园区,紧紧围绕农业科技创新驱动,统筹国内外农业科技创新资源,在农业生产过程中实现科技全覆盖。该研究以北京国际都市农业科技园为例,从种子到餐桌的角度分析了农业科技在农业生产中的应用,以期为农业转型升级提供借鉴。     

冀北地区桑牧粮间作防风固沙生态模式探析

通过对河北省张家口、承德地区生态环境特点及梯田坝坡种植条桑优点的研究,提出将条桑在张家口、承德地区推广,与牧草、粮等作物间作,形成适宜河北北方的防风固沙高效生态模式。