锡林郭勒草原国家级自然保护区种子植物区系研究北大核心CSCD

该研究以查阅文献和野外实地调查相结合的方法,对锡林郭勒草原国家级自然保护区种子植物进行调查、统计、排序,并对该区系种子植物的种类组成、水分生态类型、生活型及种的地理成分进行分析。结果表明:锡林郭勒草原国家级自然保护区有野生种子植物856种,分别隶属于87科,345属;其中,裸子植物3科,5属,11种;被子植物84科,340属,845种。植物水分生态类型以中生植物为主,共559种,占区系总种数的65.30%;旱生植物213种,占区系总种数的24.88%。生活型以草本植物为主,占区系总种数的88.67%。区系中种的地理成分较为复杂,既反映出保护区植物地域性强的特征,也反映出该区域生境类型多样、植物丰富度高的特征。     

绿绒蒿属一中国新记录种——尼东绿绒蒿

中国西藏植物多样性较为丰富,尽管已经进行了多次的植物多样性调查,但仍存在较严重的不均衡现象,部分地区和类群存在采集不足,甚至空白。我们针对西藏日喀则植物多样性调查薄弱区域开展调查,发现一个未记录的绿绒蒿属(Meconopsis Viguier)植物,采集了标本和种子。经查阅《西藏植物志》《中国植物志》、Flora of China、Flora of Nepal鉴定为尼东绿绒蒿(M. dhwojii G. Taylor ex Hay)。该文植物新资料报道如下:(1)尼东绿绒蒿形态描述及其彩色图片。(2)该植物种子微形态、与近似种间的形态差异。新发现丰富了中国绿绒蒿属植物多样性,对研究西藏乃至中国绿绒蒿属植物具有一定的生物地理学意义和潜在的园艺价值。绿绒蒿属分类须加强野外调研,多技术手段开展研究。     

Overproduction of medicinal ergot alkaloids based on a fungal platform

Privileged ergot alkaloids (EAs) produced by the fungal genus Claviceps are used to treat a wide range of diseases. However, their use and research have been hampered by the challenging genetic engineering of Claviceps. Here we systematically refactored and rationally engineered the EA biosynthetic pathway in heterologous host Aspergillus nidulans by using a Fungal-Yeast-Shuttle-Vector protocol. The obtained strains allowed the production of diverse EAs and related intermediates, including prechanoclavine (PCC, 333.8 mg/L), chanoclavine (CC, 241.0 mg/L), agroclavine (AC, 78.7 mg/L), and festuclavine (FC, 99.2 mg/L), etc. This fungal platform also enabled the access to the methyl-oxidized EAs (MOEAs), including elymoclavine (EC), lysergic acid (LA), dihydroelysergol (DHLG), and dihydrolysergic acid (DHLA), by overexpressing a P450 enzyme CloA. Furthermore, by optimizing the P450 electron transfer (ET) pathway and using multi-copy of cloA, the titers of EC and DHLG have been improved by 17.3- and 9.4-fold, respectively. Beyond our demonstration of A. nidulans as a robust platform for EA overproduction, our study offers a proof of concept for engineering the eukaryotic P450s-contained biosynthetic pathways in a filamentous fungal host.     

The reproduction potentials of four entomopathogenic nematode strains related to cost-effective production for biological control

Bioassays to evaluate the mortality, virulence and reproduction potentials of four indigenous EPN strains, S-PQ16, S-BM12, H-KT3987 and H-CB3452 on insect larvae of mealworm (Tenebrio molitor) and greater wax moth (Galleria mellonella) revealed the highest mortality rates of two insect larvae at the highest inoculation dose of 100 IJs to range from 89 to 100 percent and 94.3–100 percent at 48 h after inoculation, respectively. Virulence was high for all nematode strains, with LC₅₀ values between 29.6 and 47.3 IJs/insect host. The highest IJ yields were different between nematode strains and insect host, from 66.8 × 10³ IJs (S-PQ16) to 118.6 × 10³ IJs (H-KT3987) on T. molitor, and from 54.2 × 10³ IJs (S-BM12) to 163.3 × 10³ IJs (H-KT3987) on G. mellonella. The culturing cost in terms of food expenditure for rearing insect larvae varied between insect larvae and nematode strains, from 6.76 to 26.63 USD per billion IJs for nematode strains cultured on T. molitor larvae and from 3.54 to 7.81 USD per billion IJs for nematode strains cultured on G. mellonella larvae. The full cost for a nematode product of 2.5 × 10⁹ IJs per hectare, produced through in vivo mass culturing, of the most efficient nematode strain, H-KT3987, was 191.3 USD, slightly cheaper than 199.4 USD for the same nematode product produced through in vitro mass culturing.     

4种种子处理剂对菜心安全性及保护作用评价

为评价4种种子处理剂对菜心种子的安全性以及对黄曲条跳甲Phyllotreta striolata (Fabricius)的防治效果和保苗作用,本研究开展了室内、田间安全性试验以及田间保护试验。室内安全性试验结果显示,40%溴酰·噻虫嗪种子处理悬浮剂、600 g/L吡虫啉悬浮种衣剂、18%噻虫胺种子处理悬浮剂、54%吡虫·氟虫腈悬浮种衣剂用量分别低于5 120、9 600、2 880、7 040 g(a.i.)/100 kg种子时,对菜心种子发芽和生长无影响。田间安全性及保护作用结果显示,40%溴酰·噻虫嗪种子处理悬浮剂和54%吡虫·氟虫腈悬浮种衣剂保护作用显著,菜心出苗后25 d的株高和鲜重与对照组相比均有增加,且差异显著。结果表明40%溴酰·噻虫嗪种子处理悬浮剂和54%吡虫·氟虫腈悬浮种衣剂对菜心种子具有较好的安全性,且对菜心苗期有良好的保护作用。     

Individual‐ versus group‐optimality in the production of secreted bacterial compounds

How unicellular organisms optimize the production of compounds is a fundamental biological question. While it is typically thought that production is optimized at the individual‐cell level, secreted compounds could also allow for optimization at the group level, leading to a division of labor where a subset of cells produces and shares the compound with everyone. Using mathematical modeling, we show that the evolution of such division of labor depends on the cost function of compound production. Specifically, for any trait with saturating benefits, linear costs promote the evolution of uniform production levels across cells. Conversely, production costs that diminish with higher output levels favor the evolution of specialization–especially when compound shareability is high. When experimentally testing these predictions with pyoverdine, a secreted iron‐scavenging compound produced by Pseudomonas aeruginosa, we found linear costs and, consistent with our model, detected uniform pyoverdine production levels across cells. We conclude that for shared compounds with saturating benefits, the evolution of division of labor is facilitated by a diminishing cost function. More generally, we note that shifts in the level of selection from individuals to groups do not solely require cooperation, but critically depend on mechanistic factors, including the distribution of compound synthesis costs.     

Sperm divergence in a passerine contact zone: Indication of reinforcement at the gametic level

Postcopulatory sexual selection may promote evolutionary diversification in sperm form, but the contribution of between‐species divergence in sperm morphology to the origin of reproductive isolation and speciation remains little understood. To assess the possible role of sperm diversification in reproductive isolation, we studied sperm morphology in two closely related bird species, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (Luscinia luscinia), that hybridize in a secondary contact zone spanning Central and Eastern Europe. We found: (1) striking divergence between the species in total sperm length, accompanied by a difference in the length of the mitochondrial sperm component; (2) greater divergence between species in sperm morphology in sympatry than in allopatry, with evidence for character displacement in sperm head length detected in L. megarhynchos; (3) interspecific hybrids showing sperm with a length intermediate between the parental species, but no evidence for decreased sperm quality (the proportion of abnormal spermatozoa in ejaculates). Our results demonstrate that divergence in sperm morphology between the two nightingale species does not result in intrinsic postzygotic isolation, but may contribute to postcopulatory prezygotic isolation. This isolation could be strengthened in sympatry by reinforcement.     

Butterfly–host plant synchrony determines patterns of host use across years and regions

Variation in the degree of synchrony among host plants and herbivores can disrupt or intensify species interactions, alter the strength of natural selection on traits associated with phenological timing, and drive novel host plant associations. We used field observations from three regions during four seasons to examine how timing of the butterfly herbivore Anthocharis cardamines relative to six host plant species (Arabis hirsuta, Cardamine pratensis, Arabis glabra, Arabidopsis thaliana, Thlaspi caerulescens and Capsella bursa‐pastoris) influenced host species use and the choice of host plant individuals within populations. Butterflies laid a larger fraction of their eggs on species that were closer to the butterfly's preferred stage of development than on other host species. Within host plant populations, butterflies showed a stronger preference for individuals with a late phenology when plants within the population were on average more developed at the time of butterfly flight. Our results suggest that changes in synchrony between herbivores and their host plants are associated with changes in both host species use and the choice of host plant individuals differing in phenology within populations. This is likely to be an important mechanism generating variation in interaction intensities and trait selection in the wild, and therefore also relevant for understanding how anthropogenic induced changes, such as global warming, will influence natural communities.     

微生物介导反刍动物瘤胃氨生成及其对瘤胃功能的影响

反刍动物瘤胃中栖息着丰富多样的微生物,其在瘤胃内氨生成过程中发挥了重要的作用。微生物介导的氨基酸脱氨基作用和非蛋白氮水解作用是瘤胃内氨生成的主要途径。微生物介导了瘤胃内氨的生成,同时瘤胃内产生的氨也会反馈影响微生物菌群结构及瘤胃上皮功能,进而影响瘤胃发酵及宿主健康。本文主要综述了瘤胃微生物在介导氨生成中的作用和氨对瘤胃消化及瘤胃上皮功能的影响,以期对后续研究有所启发。