• Afforestation with an age-sequence of Mongolian pine plantation promotes soil microbial residue accumulation in the Horqin Sandy Land, China

    分类: 生物学 >> 生态学 提交时间: 2024-04-15 合作期刊: 《干旱区科学》

    摘要: Land use change affects the balance of organic carbon (C) reserves and the global C cycle. Microbial residues are essential constituents of stable soil organic C (SOC). However, it remains unclear how microbial residue changes over time following afforestation. In this study, 16-, 23-, 52-, and 62-year-old Mongolian pine stands and 16-year-old cropland were studied in the Horqin Sandy Land, China. We analyzed changes in SOC, amino sugar content, and microbial parameters to assess how microbial communities influence soil C transformation and preservation. The results showed that SOC storage increased with stand age in the early stage of afforestation but remained unchanged at about 1.27−1.29 kg/m2 after 52 a. Moreover, there were consistent increases in amino sugars and microbial residues with increasing stand age. As stand age increased from 16 to 62 a, soil pH decreased from 6.84 to 5.71, and the concentration of total amino sugars increased from 178.53 to 509.99 mg/kg. A significant negative correlation between soil pH and the concentration of specific and total amino sugars was observed, indicating that the effects of soil acidification promote amino sugar stabilization during afforestation. In contrast to the Mongolian pine plantation of the same age, the cropland accumulated more SOC and microbial residues because of fertilizer application. Across Mongolian pine plantation with different ages, there was no significant change in calculated contribution of bacterial or fungal residues to SOC, suggesting that fungi were consistently the dominant contributors to SOC with increasing time. Our results indicate that afforestation in the Horqin Sandy Land promotes efficient microbial growth and residue accumulation in SOC stocks and has a consistent positive impact on SOC persistence.

  • Spatiotemporal characteristics of seed rain and soil seed bank of artificial Caragana korshinskii Kom. forest in the Tengger Desert, China

    分类: 生物学 >> 植物学 提交时间: 2024-04-15 合作期刊: 《干旱区科学》

    摘要: Vegetation restoration and reconstruction are effective approaches to desertification control and achieving social and economic sustainability in desert areas. However, the self-succession ability of native plants during the later periods of vegetation restoration remains unclear. Therefore, this study was conducted to bridge the knowledge gap by investigating the regeneration dynamics of artificial forest under natural conditions. The information of seed rain and soil seed bank was collected and quantified from an artificial Caragana korshinskii Kom. forest in the Tengger Desert, China. The germination tests were conducted in a laboratory setting. The analysis of species quantity and diversity in seed rain and soil seed bank was conducted to assess the impact of different durations of sand fixation (60, 40, and 20 a) on the progress of vegetation restoration and ecological conditions in artificial C. korshinskii forest. The results showed that the top three dominant plant species in seed rain were Echinops gmelinii Turcz., Eragrostis minor Host., and Agropyron mongolicum Keng., and the top three dominant plant species in soil seed bank were E. minor, Chloris virgata Sw., and E. gmelinii. As restoration period increased, the density of seed rain and soil seed bank increased first and then decreased. While for species richness, as restoration period increased, it gradually increased in seed rain but decreased in soil seed bank. There was a positive correlation between seed rain density and soil seed bank density among all the three restoration periods. The species similarity between seed rain or soil seed bank and aboveground vegetation decreased with the extension of restoration period. The shape of the seeds, specifically those with external appendages such as spines and crown hair, clearly had an effect on their dispersal, then resulting in lower seed density in soil seed bank. In addition, precipitation was a crucial factor in promoting rapid germination, also resulting in lower seed density in soil seed bank. Our findings provide valuable insights for guiding future interventions during the later periods of artificial C. korshinskii forest, such as sowing and restoration efforts using unmanned aerial vehicles.

  • Effects of wind speed, underlying surface, and seed morphological traits on the secondary seed dispersal in the Tengger Desert, China

    分类: 生物学 >> 植物学 提交时间: 2024-04-15 合作期刊: 《干旱区科学》

    摘要: The maintenance of sand-fixing vegetation is important for the stability of artificial sand-fixing systems in which seed dispersal plays a key role. Based on field wind tunnel experiments using 11 common plant species on the southeastern edge of the Tengger Desert, China, we studied the secondary seed dispersal in the fixed and semi-fixed sand dunes as well as in the mobile dunes in order to understand the limitations of vegetation regeneration and the maintenance of its stability. Our results indicated that there were significant variations among the selected 11 plant species in the threshold of wind speed (TWS). The TWS of Caragana korshinskii was the highest among the 11 plant species, whereas that of Echinops gmelinii was the lowest. Seed morphological traits and underlying surface could generally explain the TWS. During the secondary seed dispersal processes, the proportions of seeds that did not disperse (no dispersal) and only dispersed over short distance (short-distance dispersal within the wind tunnel test section) were significantly higher than those of seeds that were buried (including lost seeds) and dispersed over long distance (long-distance dispersal beyond the wind tunnel test section). Compared with other habitats, the mobile dunes were the most difficult places for secondary seed dispersal. Buried seeds were the easiest to be found in the semi-fixed sand dunes, whereas fixed sand dunes were the best sites for seeds that dispersed over long distance. The results of linear mixed models showed that after controlling the dispersal distance, smaller and rounder seeds dispersed farther. Shape index and wind speed were the two significant influencing factors on the burial of seeds. The explanatory power of wind speed, underlying surface, and seed morphological traits on the seeds that did not disperse and dispersed over short distance was far greater than that on the seeds that were buried and dispersed over long distance, implying that the processes and mechanisms of burial and long-distance dispersal are more complex. In summary, most seeds in the study area either did not move, were buried, or dispersed over short distance, promoting local vegetation regeneration.

  • First histochemical examination of a Miocene ostrich eggshell with the oldest mineral-bound peptides

    分类: 生物学 >> 动物学 提交时间: 2024-04-03 合作期刊: 《古脊椎动物学报》

    摘要: 古蛋白质比古DNA具有更高的保存潜力,因此蛋白质组学研究可以帮助阐明一些超出 古DNA研究领域的灭绝生物群体的生物学特征。迄今为止最古老的多肽发现于中国西北地区晚中新世临夏盆地的鸵鸟蛋壳化石中,是与蛋壳矿化相关的蛋白质struthiocalcin (SCA-1) 的 一部分。前人认为SCA-1在蛋壳中均匀分布,并因其与方解石晶体结合的特性而得以在地 质历史中长时间保存。本次对同一鸵鸟蛋壳化石进行了组织学、扫描电子显微镜和拉曼光 谱分析,发现蛋壳内侧锥体层的晶核含有部分磷灰石,其他部位则完全由方解石构成;这 些晶核部分应当是在成岩作用过程中经历了磷酸盐化。在对该化石蛋壳样品脱钙处理后, 其锥体层晶核部分存在残留物,呈现网络状纤维结构,其位置和形态与现生鸵鸟蛋壳中脱 钙后残留的有机质相似。结果表明,该化石蛋壳中的古多肽可能集中保存在锥体层晶核 处,而非在整个蛋壳中均匀分布。磷酸盐化可能是另一个有利于有机物长期保存的埋藏过 程。临夏盆地的古气候和埋藏环境可能为该古蛋白分子的保存提供了有利的条件。建议在 未来研究中进行更深入的组织化学和矿物学分析,以进一步了解该盆地有机质和古蛋白的 保存机制。

  • 中甸刺玫的叶绿体基因组特征及种内变异

    分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2024-03-26 合作期刊: 《广西植物》

    摘要: 中甸刺玫(Rosa praelucens Byhouwer)是云南香格里拉县的特有“极危”植物和国家二 级重点保护植物,也是著名的高山花卉和重要的十倍体月季种质资源,种内存在丰富的表型 多样性。为了澄清中甸刺玫种内表型变异的遗传背景,该文利用二代测序技术对40 个不同 表型的中甸刺玫代表性个体的叶绿体基因组进行测序、组装和比较分析,结果表明:(1) 中甸刺玫的基因组序列长157 173~157 261bp,植株间仅相差88bp,共编码132 个功能基因, 主要为与光合作用和自我复制相关的基因。全部基因共由27 155 个密码子编码,以A-和U- 为末端的密码子较常见。(2)中甸刺玫的叶绿体基因组共鉴定出36 个重复序列和73 个简 单重复序列,后者大部分为单核苷酸SSRs,主要位于大单拷贝区的基因间隔区。(3)中甸 刺玫种内叶绿体全基因组的单倍型多样性为0.928±0.027,核酸多态性为0.00012;位于LSC 的petN-trnD、psaA-ycf3 等基因间隔区,以及rps16 和ycf1 等基因的核酸多态性相对较高; 不同表型的代表性个体的叶绿体基因组间在结构上不存在大片段或基因的逆转或者丢失。研 究结果表明中甸刺玫种内在叶绿体基因组大小、序列和基因结构等方面均高度保守,其种内 丰富的表型多样性不是由于叶绿体基因组的变异。

  • 叶面施硒对水稻叶片亚细胞组分中硒分布和累积的影响

    分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2024-03-26 合作期刊: 《广西植物》

    摘要: 叶面喷硒是一种有效提高作物硒含量的农艺强化手段。探究硒在水稻叶片组分中的分 布、积累特征及影响因子,可为提高叶施硒的利用效率,减少硒的生态环境风险提供支撑。 该研究利用叶片离体培养技术,比较了不同硒形态、浓度、处理时间及不同表面活性剂载体 对水稻叶片亚细胞组分中硒的分布和累积的影响。结果表明:(1)硒主要分布在水稻叶片 细胞壁中,其次是叶绿体和线粒体组分,细胞液最少;(2)叶施硒肥数小时内叶片对亚硒 酸钠的吸收能力显著高于纳米硒、硒代蛋氨酸和酵母硒,分别高出1.25 倍、1.32 倍和5.43 倍,迁移能力高出其余三者约1.26 倍;(3)水稻每片叶片的最佳施硒量为0.008 mg,此时 叶绿体和线粒体中硒含量达到最大值;(4)叶施硒后3~7 h 是叶片吸收转运硒的关键时间 点;(5)同时相比于环糊精和烷基糖苷,在外源硒中添加浓度为30 mg·L-1 的鼠李糖脂可以 更好的促进水稻叶片对硒的吸收,吸收含量增加0.8 倍。综上结果为后续了解硒在叶片中的 迁移机制奠定基础,也为未来硒配方优化、科学施硒制度建立以及降低硒生态环境风险提供 支撑。

  • 遮阴对3 种毛茛科植物光合特性的影响及耐阴性评价

    分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2024-03-26 合作期刊: 《广西植物》

    摘要: 为探究毛茛、华东唐松草和卵瓣还亮草三种毛茛科植物对不同光环境的响应机制,该文设置5 个光梯度的处理水平(0%、30%、50%、70%和90%的遮阴程度),测定三种植物的光合指标,研究 不同遮阴处理对其光合特性的影响以及耐阴性评价。结果表明:随遮阴程度逐渐增加,(1)3 种植物 的叶绿素a、叶绿素b、叶绿素(a+b)和类胡萝卜素含量呈上升趋势,而叶绿素a/b 含量则下降。(2) 3 种植物的表观量子效率(AQY)均先上升后下降;毛茛和卵瓣还亮草最大净光合速率(Pmax)呈先 升后降的变化趋势,华东唐松草的Pmax 呈下降趋势;3 种植物的光饱和点(LSP)、光补偿点(LCP)、 暗呼吸速率(Rd)则均逐渐降低。(3)三种植物的初始荧光(Fo)先下降后上升,最大荧光(Fm)、 可变荧光(Fv)、PSⅡ最大光化学效率(Fv/Fm)和PSⅡ潜在活性(Fv/Fo)值则先上升后下降;热耗 散的量子比率(φDo)、单位反应中心耗散掉的能量(DIo/RC)呈先下降后上升的变化趋势,电子传 递量子产额(φEo)、单位反应中心吸收的光能(ABS/RC)、单位反映中心所捕获的光能(TRo/RC)、 单位反映中心用于传递电子的能量(ETo/RC)、光合性能指数(PIabs)及综合性能指数(PItotal)呈 先上升后下降趋势。(4)利用主成分分析、隶属函数法等分析方法对20 个单指标进行综合分析,三 种植物的耐阴性排序为:华东唐松草>卵瓣还亮草>毛茛。综上结果认为,三种毛茛科植物对光照有 着不同的适应能力,该结论为毛茛科植物在园林绿化的应用中提供了依据。

  • 杉木林改造成阔叶林对根际和非根际土壤磷组分和转化的影响

    分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2024-03-26 合作期刊: 《广西植物》

    摘要: 磷(P)是维持亚热带森林生态系统生产力的关键因子。杉木主要分布于我国亚热 带地区,杉木林的土壤酸化,P 素利用效率低,研究杉木林转化后对土壤P 素的影响对生 态系统的稳定和森林可持续经营具有重要意义。该研究以南亚热带杉木林采伐迹地上重新 种植的杉木林、红锥林、米老排林和红锥/米老排混交林为研究对象,采集根际土和非根际 土,重点探究南亚热带杉木人工林改造成阔叶林后土壤P 组分及转化的影响。结果表明: (1)改造后的红锥林、米老排林和红锥/米老排混交林的根际和非根际土壤的微生物生物 量P 含量及酸性磷酸酶活性均显著高于杉木林;红锥林和红锥/米老排混交林的土壤全P 比 杉木林和米老排林更容易转化为速效P;(2)红锥林和红锥/米老排混交林的根际和非根 际土壤中氯化钙提取P 含量均显著高于杉木林和米老排林,米老排林和红锥/米老排混交林 根际和非根际土壤中酶提取P、盐酸提取P 和柠檬酸提取P 含量显著高于杉木林和红锥林; (3)RDA 结果表明调控根际和非根际土壤P 组分的关键因子分别是土壤含水量和微生物 生物量碳。综上所述,将杉木林改造成阔叶林有利于森林土壤P 的储存和供应。该研究为 提高南亚热带人工林土壤P 有效性的树种选择和经营管理策略等方面提供重要科学依据。

  • 漓江水陆交错带不同植被类型及其土壤养分变异规律

    分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2024-03-26 合作期刊: 《广西植物》

    摘要: 为促进水陆交错带生态系统恢复与重建,在典型样地调查的基础上,采用Pearson 相 关系数法和冗余分析法研究了漓江水陆交错带不同植被类型下的植被物种组成及多样性、土 壤养分的变异规律。结果表明:(1)不同植被类型(砾石滩、草地、灌草地和疏林地)的 植物群落结构及物种多样性均有显著差异。随着水淹时间的减少,水陆交错带由分布零星草 本植物群落逐渐演变为草、灌、乔植物群落,植被物种α多样性(Shannon-Wiener 指数、Pielou 指数和Simpson 指数)和植被覆盖度呈逐渐增加趋势,在砾石滩最低,在疏林地最高。(2) 不同植被类型的土壤养分含量有显著差异。随水淹时间的减少,土壤有机质含量逐渐增加, 而土壤含水量、有效氮、有效磷和速效钾呈先上升后下降趋势,以上养分含量最大值多出现 在灌草地或疏林地,草地次之,砾石滩最低。(3)相关性及冗余分析得出土壤有效氮、速 效钾、有效磷和有机质与植被物种α多样性各指标呈极显著正相关,其中土壤有效氮和速效 钾与植被物种多样性的关联性最强。综上:漓江水陆交错带不同植被类型下植被物种组成及 多样性、土壤养分具有异质性分配格局,适度水淹有利于植被群落聚集,对土壤养分积累有 一定促进作用;草本植物对适度水淹环境的适应能力更强;漓江水陆交错带生态修复过程中 需针对性设计不同植被类型区域的修复方案,并充分考虑植被物种多样性与土壤有效养分之 间的关系。

  • 药用植物穿心莲离体培养技术及其应用研究进展

    分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2024-03-26 合作期刊: 《广西植物》

    摘要: 穿心莲为我国重要的南药之一,用于清热解毒,凉血消肿之功效,其主要活性成分穿 心莲内酯具有抗癌、抗HIV 病毒、抗炎、保肝等功效。穿心莲内酯人工合成难度较大,主 要依靠从人工栽培的植物原料中提取,但由于栽培药材的质量受土壤、气候、水肥管理等各 种因素的影响而参差不齐,且穿心莲生长周期长,占用土地资源。植物离体培养技术在种苗 快繁及活性成分积累等方面都具有显著优势,是实现穿心莲活性成分的快速、高效生产的重 要途径之一。穿心莲组织离体再生技术体系日益完善,从外植体到完整植株的组织离体再生 技术日渐成熟,已在种苗繁育、倍性育种等方面有了一定的应用。同时,在穿心莲愈伤组织 培养、细胞悬浮培养、不定根培养、毛状根培养过程中,通过优化培养条件和使用适宜的诱 导子可大幅增加培养物中穿心莲内酯等活性成分的积累。该文分别从穿心莲组织、细胞、不 定根及毛状根培养等方面,全面系统地综述了近年来国内外穿心莲离体培养技术以及其生产 穿心莲内酯的研究进展,以期促进穿心莲离体培养技术的发展与应用,为离体生产穿心莲内 酯的研究提供参考。该文还提出了未来在穿心莲离体培养技术及通过该技术生产穿心莲内酯 的研究中需重点关注的3 个方面:(1)熟化完善穿心莲组织离体再生技术体系,建立全面 系统的评价体系。(2)优化培养条件和高效诱导子联用,进一步提高穿心莲内酯等重要活 性成分产量。(3)开展通过细胞悬浮培养技术生产穿心莲内酯的生物反应器培养研究。

  • 大苞苣苔属(苦苣苔科)一新组合及一新异名

    分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2024-03-26 合作期刊: 《广西植物》

    摘要: 大苞苣苔属(Anna Pellegr.)自1930 年建立以来,对该属植物的分类修订甚少,早期 的物种发表和修订都依据采集的标本完成,存在性状描述简略或不准确、物种界定模糊等问 题。在对白花大苞苣苔[Anna ophiorrhizoides (Hemsl.) B.L.Burtt & R.A.Davidson]和红花大苞 苣苔(Anna rubidiflora S. Z. He, F. Wen & Y. G. Wei)的历史考证、形态学对比和模式产地的 调查考证中,作者发现1911 年H. Léveillé发表的Didymocarpus cavaleriei H. Lév.与红花大苞 苣苔(Anna rubidiflora)实为同种,前者被处理为白花大苞苣苔的异名。在对白花大苞苣苔 和红花大苞苣苔的多个居群形态特征对比和地理分布信息整理后,发现二者的形态特征有一 定的差异,但仅依据花冠颜色作为种一级分类单位的界限并不恰当,综合考虑形态和地理分 布特征,故提出将红花大苞苣苔处理为白花大苞苣苔的变种。依据2018 年《国际藻类、菌 物和植物命名法规》中的规定和建议, 本文提出一个新组合兼新等级名称Anna ophiorrhizoides (Hemsl.) B. L. Burtt & R. A. Davidson var. cavaleriei(H.Lév.)X. X. Bai & F. Wen,并将Anna rubidiflora 处理为新组合的异名。

  • 异质生境下山东银莲花的转录组分析及EST-SSR 分子标记开发

    分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2024-03-26 合作期刊: 《广西植物》

    摘要: 为探究山东银莲花在全光照的山顶灌丛和阴暗的针阔混交林下两种不同生境中的生态适应机制, 并开发其EST-SSR 分子标记,该研究利用Illumina 高通量测序技术对开花期的山东银莲花叶片进行转 录组测序,获取其功能注释和差异表达基因。结果表明:(1)转录组测序共得到53 536 条Unigenes 序 列,其中27 448 条成功获得注释。(2)差异表达基因5 635 个,1 600 个在山顶灌丛的山东银莲花中上 调表达,其余4 035 个下调表达。有2 460 个差异表达基因注释到GO 数据库2 533 个三级条目中,1 051 个差异表达基因注释到KEGG 数据库的113 条代谢通路中。(3)山东银莲花适应于异质生境的代 谢通路主要涉及光合作用-天线蛋白通路和类黄酮生物合成通路,光合作用-天线蛋白通路中lhca5 基因 上调表达,lhca1-3 基因下调表达,类黄酮生物合成通路中chs、c4h、f3’h、f3h、fls、ans、chi、 ccoaomt 和hct 基因均上调表达。(4)从山东银莲花转录组数据中共搜索获得7 146 个SSR 位点分布于 6 006 条Unigenes 序列中,共计106 种重复基序,优势重复基序为单核苷酸重复。设计合成100 对ESTSSR 引物中共有68 对引物具有有效性,其中11 对具有多态性,共扩增24 个多态性片段。该研究结果 有助于更深入地理解山东银莲花在不同生境中的适应性调节机制,并首次开发其EST-SSR 分子标记填 补该方面的空白,为该生物的保护和利用提供了重要的分子标记资源。

  • A taxonomical revision of ‘Dongfangaspis qujingensis’from the Lower Devonian of Qujing, Yunnan Province

    分类: 生物学 >> 动物学 提交时间: 2024-03-22 合作期刊: 《古脊椎动物学报》

    摘要: “曲靖东方鱼”(‘Dongfangaspis qujingensis’)的归属长期以来存在争议,其最初被归入 东方鱼属(Dongfangaspis), 之后被归入宽甲鱼属(Laxaspis)。然而,由于宽甲鱼属模式种为 曲靖宽甲鱼(Laxaspis qujingensis), 这一分类学厘定又引起异物同名的问题。描述了来自云 南曲靖早泥盆世洛赫考夫期西山村组的“曲靖东方鱼”和变异坝鱼(Damaspis vartus)的新材 料。“曲靖东方鱼”在头甲长略大于宽,侧横管末端呈二分叉,V字型后眶上管不汇合,以 及至少7条侧横管从侧背管发出等方面与变异坝鱼高度相似。这些相似之处表明,相较于 宽甲鱼属和东方鱼属, “曲靖东方鱼”更接近坝鱼属。因此提出将“曲靖东方鱼”从宽甲鱼属 中移除,归入坝鱼属。新标本表明变异坝鱼多出来第5对长的侧横管是该种的一个鉴别特 征,而正型标本所呈现的非对称感觉管系统应为种内变异所造成。

  • A taxonomical revision of ’Dongfangaspis qujingensis’from the Lower Devonian of Qujing, Yunnan Province

    分类: 生物学 >> 生物进化论 提交时间: 2024-03-21

    摘要: The affinity of ‘Dongfangaspis qujingensis’, initially assigned to Dongfangaspisbut later to Laxaspis, has long been controversial. However, the taxonomical revision raisesa new problem of junior homonym since the type species of Laxaspis is L. qujingensis. Here,we describe some new materials of ‘Dongfangaspis qujingensis’ and Damaspis vartus fromthe Xishancun Formation (early Lochkovian, Early Devonian) in Qujing, Yunnan Province.‘Dongfangaspis qujingensis’ strikingly resembles Damaspis vartus in the slightly longerheadshield, bifurcated ends of the lateral transverse canals, unconnected V-shaped posteriorsupraorbital canals, and at least seven pairs of lateral transverse canals issuing from the lateraldorsal canal. These similarities indicate that ‘D. qujingensis’ is more suggestive of Damaspis thanDongfangaspis and Laxaspis. Therefore, we propose to remove ‘Dongfangaspis qujingensis’ fromLaxaspis to Damaspis. The new specimens of Damaspis vartus reveal five long lateral transversecanals on the right side, corroborating that the asymmetric sensory canal system in the holotype isthe intraspecific variation.

  • A possible new amphicyonid from the Miocene of the Linxia Basin

    分类: 生物学 >> 生物进化论 提交时间: 2024-03-20

    摘要: Here we report a new form of amphicyonid from an uncertain locality in the LinxiaBasin. The derived dental traits imply an affinity to Magericyon, previously known from Europe and possibly southern Asia. The specimen suggests a higher diversity of amphicyonids in eastern Asia than previously thought, and more discovery with stratigraphic information will be needed to elucidate the evolution of Amphicyonidae in eastern Asia.

  • Taxonomic revision of Sinoeugnathus kueichowensis from the Middle Triassic of Guizhou and Yunnan, China

    分类: 生物学 >> 生物进化论 提交时间: 2024-03-15

    摘要: The previously alleged ‘eugnathid amiiform’ Sinoeugnathus kueichowensis is asmall-sized halecomorph from the Middle Triassic (Ladinian) marine deposits of Guizhou andYunnan, China. A morphological redescription and taxonomic revision of this taxon are providedbased on a detailed examination of 15 new specimens. Among them, IVPP V24315 (standardlength = 64 mm) is appointed as the neotype, given that the holotype is missing. Studies of thesespecimens revealed some morphological details previously undescribed or misidentified forthis taxon, including a hatchet-shaped antorbital, two broad suborbitals, a sensory canal in themaxilla, and three pairs of extrascapulars. For the first time, Sinoeugnathus was incorporatedinto an analysis of halecomorph phylogeny, and the results recover it as the sister taxon of theAnisian Subortichthys from Luoping, Yunnan, and both are grouped with two Ladinian generaAllolepidotus and Eoeugnathus from the Monte San Giorgio area into a monophyletic group(namely Subortichthyidae fam. nov. herein) at the base of Ionoscopiformes. This taxonomicreassessment of Subortichthys provides new insights into the phylogeny and paleogeographicevolution of Ionoscopiformes.

  • A restudy of Rhinocerotini fossils from the Miocene Jiulongkou Fauna of China

    分类: 生物学 >> 生物进化论 提交时间: 2024-03-15

    摘要: All the extant rhino species belong to Rhinocerotini and either have one horn (a nasal horn) or two horns (a nasal horn and frontal horn). So far, the earliest Rhinocerotini to have been identified in China is the “Dicerorhinus” cixianensis, which was based on a juvenile skull with an associated mandible from the Middle Miocene locality of Jiulongkou in Cixian County, HebeiProvince of northern China. Our analyses suggest that there are similarities between this specimenand the modern genus, Dicerorhinus, but it differs in several cranial traits and therefore cannotbe assigned to the modern genus. Instead, it is closer to the Middle Miocene Lartetotheriumfrom Europe, especially the specimen from La Retama in Spain and should be assigned to thatgenus, indicating the presence of intracontinental dispersal at this time. The Jiulongkou faunais the only Middle Miocene fauna with Rhinocerotini in China, and, together with the faunalcomposition, this implies a more humid and closed environment, in contrast to those found inwestern China. We suggest that the position of the posterior border of the nasal notch is a goodindication of the specimen’s evolutionary level in Rhinocerotini. The anterior position of the nasalnotch as seen in modern Dicerorhinus, together with its certain similarities to L. cixianensis aswell as its differences with more specialized species of the Dihoplus-Pliorhinus-Stephanorhinus-Coelodonta lineage, supports the conclusion that Dicerorhinus experienced little change during anearly 10 Myr evolutionary history, possibly due to the low selection pressure seen in the tropical/subtropical forests in southeastern Asia.

  • Responses of plant diversity and soil microorganism diversity to nitrogen addition in the desert steppe, China

    分类: 生物学 >> 生态学 提交时间: 2024-03-13 合作期刊: 《干旱区科学》

    摘要: Nitrogen (N) deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity. The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention. Soil microorganisms have been proven to provide nutrients for specific plant growth, especially in nutrient-poor desert steppe ecosystems. However, the effects of N deposition on plant-soil microbial community interactions in such ecosystems remain poorly understood. To investigate these effects, we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb. desert steppe in Inner Mongolia Autonomous Region, China. Four N treatment levels (N0, N30, N50, and N100, corresponding to 0, 30, 50, and 100 kg N/(hm2•a), respectively) were applied to simulate atmospheric N deposition. The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants. N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in the desert steppe, and low and mediate N additions (N30 and N50) had a promoting effect on them. The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index. N deposition significantly affected the beta-diversity of plants and soil bacteria, but did not significantly affect fungal communities. In conclusion, N deposition led to co-evolution between desert steppe plants and soil bacterial communities, while fungal communities exhibited strong stability and did not undergo significant changes. These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.

  • Morphometric analysis of the cervical vertebral series in extant birds with implications for Mesozoic avialan feeding ecology

    分类: 生物学 >> 人类学 提交时间: 2024-03-06

    摘要: The inference of Mesozoic avialan bird diets previously relied on traditional methods such as morphological comparisons among taxa and direct evidence such as identifiable stomach contents. However, the application of these approaches has been limited because of uncommon preservation of relevant fossil evidence. We searched for additional informative characteristics to help develop new methods to assess the diet of fossil birds. In particular, the morphology of the avialan neck is highly modularized and plays roles in multiple functions including food acquisition. The structure of and variation among the cervical vertebrae likely reflects the demands of feeding ecology in fossil and extant birds because the avialan neck evolved to, at least in part, replace the forelimbs by assisting with activities such as cranioinertial feeding and other ecological functions. Here, we utilize morphometric and statistical analyses to establish an initial quantitative relationship between cervical morphology and dietary modes in both extant and extinct birds. This morphometric framework derived from the cervical morphology of living birds is used as a basis to estimate the diet categories of five taxa of Mesozoic birds. The results indicate that there is a quantitative correlation between cervical morphology differentiation and their interrelated feeding modes. The enantiornithine taxa examined exhibit cervical morphologies similar to extant insectivorous or carnivorous birds. The ornithurine species show cervical morphologies that are more aligned with generalist or herbivorous birds, and exhibit preliminary morphological features tied to aquatic adaptions. These findings are consistent in part with other direct fossil evidence, as well as hypotheses developed from other skeletal comparisons. Therefore, the cervical vertebral series, as a skeletal system closely linked to food acquisition, can serve as one of the valuable metrics to provide information for inferring the diet of long extinct Mesozoic birds.

  • Direct detection of twenty amino acids and discrimination of pathological peptides with functionalized nanopore

    分类: 生物学 >> 生物工程 提交时间: 2024-03-05

    摘要: Single-molecule discrimination among amino acids is crucial to the realization of next-generation protein sequencing. Owing to the heterogeneous charge and subtle volume difference of underivatized amino acids, it remains a challenge for single-molecule techniques to recognize each of them. Here, we report the direct detection of twenty proteinogenic amino acids using a copper(II)-functionalized MspA nanopore. The binding sites for copper(II) ion are constructed by introducing histidine mutation (N91H) to M2MspA protein. With copper ion binding to histidine residues, amino acids can reversibly coordinate the copper-histidine complex, generating well-defined current signals. Using this strategy, all twenty amino acids can be detected. Assisted by a machine learning algorithm, we can identify 100% of signals with 70.2% accuracy or 60% of signals with 93.4% accuracy in the validation set. In successively addition experiment, each amino acid in a mixture of 10 amino acids can be identified precisely. Furthermore, we use carboxypeptidase A1 to partly release the C-terminal amino acids of peptides with different lengths (9, 10 and 22 residues). The hydrolysates of peptides can be identified and distinguished. These results demonstrate the feasibility of this system for amino acids detection and peptide identification, shedding new lights on the development of single-molecule protein sequencing.