Bioturbation in matgrounds at Lake Bogoria in the Kenya Rift Valley: implications for interpreting the heterogeneous early Cambrian seafloor

Modern burrowing organisms feed on microbial organic matter in matgrounds near hot springs on the margins of Lake Bogoria, a saline alkaline lake in the Kenya Rift Valley. The burrowers produce a low-diversity trace assemblage similar to those produced by undermat miners during the Ediacaran–Cambrian transition. Despite obvious differences in body plans and phylogenetic affinities, these modern animals feed on microbes in similar ways to those inferred for primitive bilaterians. With increasing distance from hot-spring vents, outflow channels and adjacent matgrounds, the diversity and depth of the traces increase and mixgrounds become dominant. This modern extreme environment gives clues for interpreting the heterogeneous early Cambrian seafloor, with: (1) the restriction of ‘pre-agronomic revolution’ matground substrates; and (2) expansion of adjacent ‘post-agronomic revolution’ mixground areas.     

Wetland Waterbird Food Resources Increased by Harvesting Invasive Cattails

The conservation of many freshwater marsh waterbirds (i.e., waterfowl, shorebirds, wading birds, and secretive marshbirds) in the Laurentian Great Lakes requires managing invasive emergent macrophytes, which degrade waterbird habitat by creating dense, litter-clogged stands, and excluding plants that produce nutritionally balanced and high-energy food (seeds, tubers, and submerged aquatic vegetation). The most commonly used management approach in the United States Great Lakes region involves the application of herbicides, which can stimulate waterbird forage plants but does not address the accumulation of plant litter, the underlying cause of plant community diversity loss and habitat degradation. We experimentally evaluated the effects of an alternative approach, harvesting invasive plants and their litter followed by flooding, on plant communities, focusing on the effects of these treatments to increase the abundance of high-energy wetland plants. At the Shiawassee National Wildlife Refuge in Michigan, USA, we experimentally treated an invasive cattail (Typha × glauca)-dominated wetland in August and September of 2016, 2017, and 2018, using a randomized block design with 4 blocks and 3 treatments (sediment surface harvest, above ground harvest, and control). We monitored the effects of these treatments on the abundance and dominance of waterbird forage-producing plants, plant diversity, and plant communities prior to (Jul 2016) and during the summer following each treatment (late Jul or early Aug 2017, 2018, and 2019). Additionally, we used pre- and post-treatment waterbird use-day data collected at the unit scale and compared values with satellite imagery-derived land cover changes. Compared to control plots, 3 years of harvesting and flooding significantly increased plant species diversity, increased the abundance of waterbird seed- and tuber-producing plant species by 5 times, and increased annual plant dominance by more than 10 times, while substantially reducing all measures of cattail and its litter. Use-days increased for total waterbirds, including waterfowl and dabbling ducks, following treatment. Cattail cover decreased and open water and non-cattail emergent vegetation cover increased. Harvesting invasive plant biomass coupled with flooding promoted a plant community composition and structure beneficial to waterbirds. © 2020 The Wildlife Society.     

Gopher Tortoise Demographic Responses to a Novel Disturbance Regime

The long-term viability of gopher tortoise (Gopherus polyphemus) populations is jeopardized by increased urbanization and habitat degradation owing to fire suppression. Because the species' remaining natural habitats in the southeastern United States exist within a mosaic of anthropogenic land uses, it is important to understand demographic responses to contrasting land uses and habitat management regimes. We examined differences in demographic parameters among fire-suppressed sandhill, restored sandhill, and former sandhill (i.e., ruderal) land use-land cover (LULC) types at Archbold Biological Station in south-central Florida, USA. Using Program MARK, we estimated population size, and sex-specific and LULC-specific survivorship based on 6 years of mark-recapture data. We also analyzed individual growth trajectories and clutch sizes to determine whether growth rates or reproductive output differed among LULC types. Tortoises in an open, ruderal field occurred at a higher density (7.79/ha) than in adjacent restored (1.43/ha) or fire-suppressed (0.40/ha) sandhill. Despite this higher density, both adult survivorship and body size were significantly higher in the ruderal field. Furthermore, the larger female body size in the ruderal field likely contributed to increased annual survivorship and slightly larger average clutch sizes. We did not detect offsetting negative demographic effects; in particular, we did not find significant biological or statistical differences in body condition, asymptotic body size, or growth rate among the 3 LULC types. Our results suggest that anthropogenic, grass-dominated land-cover types may be important components of the habitat mosaic currently available to this at-risk species. © 2019 The Wildlife Society.     

Sex-based differences in vigor and site preferences of Juniperus communis subsp. nana

Dioecious alpine juniper has been influenced by human impacts, management and climate changes; hence, its present populations are remnant fragments of its former distribution in central Europe. Complex environmental shifts have had fatal consequences for growth, reproduction and health of juniper and hence for its population structure. We asked the questions: 1) what was the population size structure, the sex ratio and the health status of individuals? 2) How were the population parameters linked with the environmental conditions and surrounding vegetation? The study area was close and above the upper forest limit in central Europe, the Hrubý Jeseník Mts. The parameters of each juniper individual and its environmental conditions were obtained, Ellenberg's indicator values and habitat categories were also determined. Proportions of sex categories, shrub size and environmental conditions were investigated to assess relationships between the population categories and environmental factors. We revealed linkage among the shrub size, health vigor, vegetation cover, a habitat and environmental factors. While there was equal ratio of females and males (1:1), small individuals of undetermined sex predominated that reducing the effective population size. Juniper health vigor was associated with surrounding vegetation cover. Individuals of undetermined sex were smaller than those of remaining sex categories and prefer specific habitats at higher elevation, underlining the effect of abiotic conditions on sex performance and ratio. The observed pattern, which was attributed to shift in land-use practices in the middle of 20th century and climate changes, could be improved by management. We recommended experimental local grazing and mowing accompanying by profound and continuing assessment of interaction among environmental factors and juniper performance.     

植物病媒昆虫的翅型分化

翅多型现象是昆虫非遗传多型性的一种表现,包括不具飞行能力的短翅型或无翅型,以及可以进行长距离迁飞的长翅型或有翅型。翅多型现象常发生在可以携带病原并将其传播给植物宿主的媒介昆虫中,对植物病害的时空分布与暴发有重要影响。本文从翅型分化的遗传规律、诱导因素、分子机制和伴随翅型分化的其他生理表现4个方面,对植物病原主要传播媒介蚜虫和飞虱的翅型分化研究进行综述和梳理。昆虫翅型分化的诱导因素主要包括温度、湿度和光周期等非生物因素以及虫口密度、宿主营养、病毒等生物因素;而其内在的分子机制大多是通过胰岛素/胰岛素样生长因子信号(IIS)通路、c-Jun氨基末端激酶(c-Jun NH 2-terminal kinase,JNK)信号通路、Wingless和嗅觉受体SaveOrco等调控。翅型分化的同时伴随着生理状态的变化,表现为短翅型具有更强的繁殖能力和长翅型含有更丰富的飞行肌结构成分。目前,昆虫翅型分化的研究尚不够完善,有许多需要解答的问题,如找到胰岛素/胰岛素样生长因子信号通路中真正发挥功能的靶基因,JNK如何调控翅型分化以及虫媒病毒影响媒介昆虫翅型的分子机理。本综述可为控制虫媒病原的传播以及其他昆虫翅多型的研究提供参考。     

LC-MS/MS-based metabolic profiling of Escherichia coli under heterologous gene expression stress

Escherichia coli is frequently exploited for genetic manipulations and heterologous gene expression studies. We have evaluated the metabolic profile of E. coli strain BL21 (DE3) RIL CodonPlus after genetic modifications and subjecting to the production of recombinant protein. Three genetically variable E. coli cell types were studied, normal cells (susceptible to antibiotics) cultured in simple LB medium, cells harboring ampicillin-resistant plasmid pET21a (+), grown under antibiotic stress, and cells having recombinant plasmid pET21a (+) ligated with bacterial lactate dehydrogenase gene grown under ampicillin and standard isopropyl thiogalactoside (IPTG)-induced gene expression conditions. A total of 592 metabolites were identified through liquid chromatography-mass spectrometry/mass spectrometry analysis, feature and peak detection using XCMS and CAMERA followed by precursor identification by METLIN-based procedures. Overall, 107 metabolites were found differentially regulated among genetically modified cells. Quantitative analysis has shown a significant modulation in DHNA-CoA, p-aminobenzoic acid, and citrulline levels, indicating an alteration in vitamin K, folic acid biosynthesis, and urea cycle of E. coli cells during heterologous gene expression. Modulations in energy metabolites including NADH, AMP, ADP, ATP, carbohydrate, terpenoids, fatty acid metabolites, diadenosine tetraphosphate (Ap4A), and l -carnitine advocate major metabolic rearrangements. Our study provides a broader insight into the metabolic adaptations of bacterial cells during gene manipulation experiments that can be prolonged to improve the yield of heterologous gene products and concomitant production of valuable biomolecules.     

Larval development and proteolytic activity of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) exposed to different soybean protease inhibitors

Anticarsia gemmatalis represents a relevant factor for lowering soybean and other legume crop productivities. Protease inhibitors affect protein degradation and reduce the availability of amino acids, impairing the development and survival of insect pests. To evaluate the possible use of proteinaceous protease inhibitors in the management of this pest, the activities of midgut proteases and the growth and development of A. gemmatalis larvae exposed to soybean Bowman–Birk trypsin-chymotrypsin inhibitor (SBBI) and soybean Kunitz trypsin inhibitor (SKTI) were determined. The survival curves obtained using Kaplan–Meier estimators indicated that SKTI and SBBI stimulated larval survival. However, the development of A. gemmatalis was delayed, and prepupal weight decreased in the presence of both inhibitors. The results showed that SKTI and SBBI inhibited the trypsin-like and total proteolytic activities of larvae on the 12th day after eclosion. On the 15th day after eclosion, larvae exposed to SKTI increased the activities of trypsin and total proteases. Although SKTI and SBBI did not affect the survival of the insect, they had effects on midgut proteases in a stage wherein A. gemmatalis fed voraciously, increased the larval cycle, and decreased prepupal weight. These findings provide baseline information about the potential of proteinaceous protease inhibitors to manage the velvetbean caterpillar, avoiding chemical pesticides.     

Persistence of extended-spectrum β-lactamase plasmids among Enterobacteriaceae in commercial broiler farms

To clarify the persistence of extended-spectrum β-lactamase (ESBL) producers, 13 plasmids from two broiler farms were analyzed. On the farm not using antimicrobials, one plasmid from Klebsiella pneumoniae isolated from a day-old chick was similar to that from Escherichia coli isolated a year later, with the deletion of two transposons. On the farm using antimicrobials, most circulating plasmids (eight out of nine) in a flock of 40-days-old chicks were identical, although one from K. pneumoniae had a deletion of a transposon carrying a class 1 integron containing aadA2 and dfrA12. Thus, ESBL plasmids persisted in the farms with or without antimicrobial agent use.     

基于转录组的苹小卷叶蛾杀虫剂靶标及解毒代谢相关基因分析

【目的】建立苹小卷叶蛾Adoxophyes orana转录组数据库,挖掘杀虫剂靶标及解毒代谢相关基因。【方法】采用Illumina HiSeq~(TM) 2000高通量测序技术对苹小卷叶蛾进行转录组测序,挖掘并分析杀虫剂靶标基因;利用qPCR检测6个杀虫剂靶标基因在苹小卷叶蛾卵、幼虫、蛹和成虫各不同发育阶段的表达;挖掘并分析苹小卷叶蛾转录组中解毒代谢相关基因的代谢通路及进化关系。【结果】通过组装有效序列共获得48 610条unigene(GenBank登录号:GGMW00000000)。挖掘鉴定到155个杀虫剂靶标unigene;qPCR结果显示,1个蜕皮激素受体(ecdysone receptor, ECR)、2个乙酰胆碱酯酶(acetylcholinesterase, AChE)、1个氯离子通道蛋白(chloride channel, CLC)、1个几丁质酶(chitinase, CS)和1个鱼尼丁受体(ryanodine receptor, RyR)基因在苹小卷叶蛾不同发育阶段均存在表达差异。挖掘鉴定到69个羧酸酯酶(carboxylesterase, CarE)unigene、66个谷胱甘肽S-转移酶(glutathion S-transferase, GST)unigene和205个细胞色素P450(cytochrome P450)unigene等解毒代谢相关基因,共鉴定20个CarE unigene, 32个GST unigene和30个P450 unigene与有毒物质代谢相关的通路有关。基于氨基酸序列对具有完整ORF的unigene聚类分析结果显示:12个CarEs中9个为G类,即鳞翅目保幼激素类;分别有10个AoGSTs属于Delta和Epsilon亚家族;18个P450全部聚到CYP3集团。【结论】该研究有助于苹小卷叶蛾杀虫剂靶标基因的挖掘及抗药性的研究。