人生殖道源乳酸杆菌的筛选及在小鼠阴道假丝酵母病模型中的应用评价

【目的】分离筛选人阴道环境中具有益生特性的乳酸杆菌,探索外阴阴道假丝酵母病的益生菌疗法。【方法】利用含1%碳酸钙的de Man,Rogosa and Sharpe (MRS)培养基从无症状育龄女性阴道分泌物中分离乳酸杆菌,采用共培养方法评价其对白色念珠菌(Candida albicans)的抑制作用,通过对乳酸杆菌的耐酸性能、体外聚集特性和黏附能力测试考察其益生特性,并进行乳酸杆菌株功能化组合。通过构建小鼠外阴阴道假丝酵母病模型,初步探索乳酸杆菌株组合对C. albicans的抑制作用。【结果】从53个样品中分离得到19株乳酸杆菌,筛选获得4株乳酸杆菌(Lactobacillus crispatus ZH08、L. fermentum ZH09、L. fermentum ZH11和L. crispatus ZH17)具有较强抑制 C. albicans生长的能力。4株乳酸杆菌均能耐受低pH环境,能快速降低培养液pH。其中2株L. fermentum具有更强的抑制活性,能在24 h内快速抑制C. albicans生长,抑制率可达到95%以上;另2株L. crispatus具有更强的聚集特性和对上皮细胞有较强黏附性。乳酸杆菌ZH17和ZH11组合应用小鼠阴道假丝酵母病模型治疗,能显著抑制C. albicans生长和菌丝相转化,促进粘膜修复和缓解炎症。【结论】本研究筛选的乳酸杆菌具有生殖道益生菌的特性,乳酸杆菌组合应用具有潜在的临床前景。     

安徽南部上奥陶统的笔石并论围笔石属

1982年夏,钱义元、方一亭、夏广胜、张俊明和笔者观察安徽南部奥陶、志留纪地层剖面时,在宁国胡乐新岭上奥陶统新岭组和石台丁香及泾县北贡上奥陶统五峰组采得的一些笔石,和1974年穆恩之等在宁国上荆山村新岭组采得的Diceratograptus cf.mirus Mu,现在此一起予以报道。同时,本文介绍了上奥陶统围笔石的分布及其在地层对比中的作用,讨论了围笔石属的定义;又根据重新厘定的定义,对该属所包括的种进行了系统整理。     

What is the usual internal carbon dioxide concentration in C<Subscript>4</Subscript> species under midday field conditions?

The carbon dioxide concentrating system in C₄ photosynthesis allows high net photosynthetic rates (P _N) at low internal carbon dioxide concentrations (C _i), permitting higher P _N relative to stomatal conductance (g _s) than in C₃ plants. This relation would be reflected in the ratio of C _i to external ambient (C _a) carbon dioxide concentration, which is often given as 0.3 or 0.4 for C₄ plants. For a C _a of 360 μmol mol⁻¹ that would mean a C _i about 110–140 μmol mol⁻¹. Our field observations made near midday on three weedy C₄ species, Amaranthus retroflexus, Echinochloa crus-galli, and Setaria faberi, and the C₄ crop Sorghum bicolor indicated mean values of C _i of 183–212 μ mol mol⁻¹ at C _a = 360 μmol mol⁻¹. Measurements in two other C₄ crop species grown with three levels of N fertilizer indicated that while midday values of C _i at high photon flux were higher at limiting N, even at high nitrogen C _i averaged 212 and 196 μmol mol⁻¹ for Amaranthus hypochondriacus and Zea mays, respectively. In these two crops midday C _i decreased with increasing leaf to air water vapor pressure difference. Averaged over all measurement days, the mean C _i across all C₄ species was 198 μmol mol⁻¹, for a C _i/C _a ratio of 0.55. Prior measurements on four herbaceous C₃ species using the same instrument indicated an average C _i/C _a ratio of 0.69. Hence midday C _i values in C ₄ species under field conditions may often be considerably higher and more similar to those of C₃ species than expected from measurements made on plants in controlled environments. Reducing g _s in C₄ crops at low water vapor pressure differences could potentially improve their water use efficiency without decreasing P _N.     

Effects of light,temperature and salinity on the growth rate of harmful marine diatoms,Chaetoceros convolutus and C. concavicornis that kill netpen salmon

Chaetoceros convolutus and C. concavicornis have been implicated in the death of salmon in netpens in the Pacific Northwest by damaging the salmon's gills. To better understand how environmental factors affect the distribution of these two species, the interacting effects of light, temperature and salinity on growth rate were examined by growing these species under a range of temperatures (4–18 °C), light (10–175 μmol photon m⁻² s⁻¹) and salinities (10–30‰). For C. convolutus, the growth rate showed a hyperbolic relationship with irradiance at 8, 14 and 18 °C and light saturation occurred at 9, 14 and 20 μmol photon m^t s⁻¹ respectively. At 4 °C for C. convolutus and 8 °C for C. concavicornis, cells grew at μ_max, even at the lowest irradiances tested (10 μmol photon m⁻² s⁻¹). For C. convolutus, the amount of light required to saturate growth rate increased with temperature in an approximately linear fashion. The Q₁₀ was 1.88, calculated by averaging over both species. C. concavicornis was the more euryhaline species growing at salinities as low as 17.5‰, while C. convolutus grew only at 25‰ and above.     

Interactions of Elevated CO2 Concentration and Drought Stress on Photosynthesis in Eucalyptus Cladocalyx F. Muell

Response of net photosynthetic rate (P _N), stomatal conductance (g _s), intercellular CO₂ concentration (c _i), and photosynthetic efficiency (F_v/F_m) of photosystem 2 (PS2) was assessed in Eucalyptus cladocalyx grown for long duration at 800 (C₈₀₀) or 380 (C₃₈₀) μmol mol^-1 CO₂ concentration under sufficient water supply or under water stress. The well-watered plants at C₈₀₀ showed a 2.2 fold enhancement of P _N without any change in g _s. Under both C₈₀₀ and C₃₈₀, water stress decreased P _N and g _s significantly without any substantial reduction of c _i, suggesting that both stomatal and non-stomatal factors regulated P _N. However, the photosynthetic efficiency of PS2 was not altered. This revised version was published online in June 2006 with corrections to the Cover Date.     

Compensatory effects of elevated CO<Subscript>2</Subscript> concentration on the inhibitory effects of high temperature and irradiance on photosynthetic gas exchange in carrots

We determined the interactive effects of irradiance, elevated CO₂ concentration (EC), and temperature in carrot (Daucus carota var. sativus). Plants of the cv. Red Core Chantenay (RCC) were grown in a controlled environmental plant growth room and exposed to 3 levels of photosynthetically active radiation (PAR) (400, 800, 1 200 μmol m⁻² s⁻¹), 3 leaf chamber temperatures (15, 20, 30 °C), and 2 external CO₂ concentrations (C _a), AC and EC (350 and 750 μmol mol⁻¹, respectively). Rates of net photosynthesis (P _N) and transpiration (E) and stomatal conductance (g _s ) were measured, along with water use efficiency (WUE) and ratio of internal and external CO₂ concentrations (C _i/C _a). P _N revealed an interactive effect between PAR and C _a. As PAR increased so did P _N under both C _a regimes. The g _s showed no interactive effects between the three parameters but had singular effects of temperature and PAR. E was strongly influenced by the combination of PAR and temperature. WUE was interactively affected by all three parameters. Maximum WUE occurred at 15 °C and 1 200 μmol m⁻² s^{− 1} PAR under EC. The C _i /C _a was influenced independently by temperature and C _a. Hence photosynthetic responses are interactively affected by changes in irradiance, external CO₂ concentration, and temperature. EC significantly compensates the inhibitory effects of high temperature and irradiance on P _N and WUE.     

Photosynthetic response of <Emphasis Type="Italic">Quercus ilex</Emphasis> L. plants grown on compost and exposed to increasing photon flux densities and elevated CO<Subscript>2</Subscript>

Quercus ilex plants grown on two different substrates, sand soil (C) and compost (CG), were exposed to photosynthetic photon flux densities (PPFD) at 390 and 800 μmol(CO₂) mol⁻¹ (C₃₉₀ and C₈₀₀). At C₈₀₀ both C and CG plants showed a significant increase of net photosynthetic rate (P _N) and electron transport rate (ETR) in response to PPFD increase as compared to C₃₉₀. In addition, at C₈₀₀ lower non-photochemical quenching (NPQ) values were observed. The differences between C₃₉₀ and C₈₀₀ were related to PPFD. The higher P _N and ETR and the lower dissipative processes found in CG plants at both CO₂ concentrations as compared to C plants suggest that substrate influences significantly photosynthetic response of Q. ilex plants. Moreover, short-term exposures at elevated CO₂ decreased nitrate photo-assimilation in leaves independently from substrate of growth.     

四川古蔺下奥陶统桐梓组笔石的发现

1978年7月,笔者与龚联瓒等同志在四川古蔺大坪测制奥陶纪地层剖面时,于下奥陶统桐梓组近顶部采得反称笔石科的笔石。计有Adelograptus sichuanensis sp. nov., Adelograptus minor sp. nov., Kiaerograptus? gulinensis sp. nov., Kiaerograptus? sp.等。这些笔石与三叶虫Tungizuella szechuanensis Sheng, T. kweichowensis sheng及腕足类Tritoechia cf. quebecensis Ulrich and Cooper, Lingulella sp.等产于同一层位。因此,该地桐梓组顶部可称为Adelograptus-Tungtzuella带,并与鄂西分乡组Acanthograptus sinensis带相当。     

新疆吐鲁番盆地桃树园晚二叠世非海相腹足类*

新疆吐鲁番盆地桃树园地区晚二叠世地层称作下仓房沟群, 自下而上分为泉子街组、梧桐沟组和锅底坑组, 为河–湖相碎屑沉积, 剖面连续, 层序清楚, 动、植物化石丰富。文中研究的腹足类标本产于桃东沟剖面梧桐沟组下部和中部的介壳灰岩层和灰岩透镜体中, 见有2层, 计有2科4属6种: Xinjiangospira rotundata Yu et Zhu, Xinjiangospira habita sp. nov.、Hydrobia turpanensis Wei、Hydrobia orientalis sp. nov.、Pseudamnicola taodonggouensis sp. nov.和Valvata complanusa sp. nov.; 与腹足类共生的有双壳类、叶肢介、介形类, 以及植物和脊椎动物化石等, 其中双壳类主要是Palaeanodonta, Palaeomutela和Anthraconauta 等属。该腹足动物群由Hydrobiidae 和 Valvatidae的属种组成, 标本数量多, 壳体小, 保存完好, 是迄今已知属种最丰富的古生代淡水腹足类动物群。当前梧桐沟组腹足动物群面貌与准噶尔盆地大龙口剖面小龙口组(锅底坑组), 以及非洲罗得西亚南部上二叠统卡鲁系的腹足动物群面貌一致。     

西藏纳木错西岸班戈县新吉乡早白垩世的石珊瑚

西藏纳木错西岸班戈县新吉乡的早白垩世地层发育, 珊瑚化石丰富, 经过鉴定、描述、研究, 计有白垩纪石珊瑚10属10种(其中有3新种), 它们是Axosmilia sp., Cyathophora? sp., Eohydnophora baingoinensis sp. nov., Epistrepto-phyllum cf. diatritum Wu, Hydnophora styriaca (Michelin), Ironella giseldonensis Starostina and Krasnov in Krasnov and Starostina, Placophyllia baingoinensis sp. nov., Protethmos cf. discus Liao and Xia, Protochocyathus ? sp., Stylina namcoensis sp. nov.。上述石珊瑚属在欧亚大陆的侏罗、白垩纪地层中都有广泛分布。其中, Cyathophora ? sp. 与申扎县果芒错下白垩统所产出的Cyathophora gomangcoensis Liao and Xia比较相似, 只是个体直径要稍微小一些; Hydnophora styriaca与欧洲上白垩统的模式种也有某些相似之处, 只是我们的标本每个脊塍上有较多的隔片; 新种Eohydnophora baingoinensis与日本早白垩世的Eohydnophora tosaensis Yabe and Eguchi的主要区别只是其脊塍和隔片都比较细薄; Protochocyathus? sp.的外壁比匈牙利下白垩统的Protochocyathus valanginicus Kolosvary的外壁薄。总之, 西藏班戈县新吉乡的早白垩世石珊瑚群与西藏申扎、日本、俄罗斯、匈牙利和斯洛文尼亚等地同期的石珊瑚有许多相似之处, 完全可以进行对比。本文的研究成果将对我国西藏地区地层层序的建立和详细对比以及对早白垩世石珊瑚群的动物地理亲缘关系的了解提供重要依据。     

西藏南部聂拉木志留纪笔石新材料*

西沙群岛琛航岛琛科二井(CK-2)有878.3 m厚的新生代珊瑚礁灰岩(Cenozoic reef limestone)。新生代珊瑚礁灰岩自上而下包括了第四系的全新统和更新统以及新近系的上新统和中新统。其中, 中新统厚514.3 m, 产19属石珊瑚(Scleractinia corals)。更新统厚215.6 m, 产21属石珊瑚(Scleractinia)和1属八射珊瑚(Octocorallia)。珊瑚是营底栖固着生活的动物, 在地层断代方面它没有能像一些浮游动物(例如浮游有孔虫等)那么“精准”。但也有一些珊瑚的地质历程相对比较短暂的, 它们在地层划分和对比方面还是能起到一定的重要作用。根据本文的研究在琛科二井井深364–878.3 m的这一段中新世地层中就鉴定出有好几个只见于中新世或者常见于中新世的珊瑚, 如: 星日珊瑚(Astrhelia)、安的列斯珊瑚(Antillophyllia)和大安的列斯珊瑚(Antillia)等。另外在井深21.4–237 m的更新世地层中也发现了好几个只限于第四纪的珊瑚, 如: 叶状珊瑚(Lobophyllia)、合叶珊瑚(Symphyllia)、轮沙珊瑚(Trochopsammia)和苍珊瑚(Heliopora)等。上述那些珊瑚的地质分布与有孔虫(Foraminifera)生物地层鉴定的结果以及古地磁(Palaeomagnetism)和同位素(Isotope)年代地层测定的数据完全吻合。此外, 珊瑚除了在地层的划分对比方面(subdivision and correlation of the stratigraphy)能够起到一些关键的作用外, 更重要的是它在恢复和解释古地理(Palaeogeography)、古气候(Palaeoclimatology)和古生态(Palaeoecology)等方面也都能起到非常重要的作用。     

Aeronian (Llandovery, Lower Silurian) palynomorphs and graptolites from the Lipeón Formation, Eastern Cordillera, north-west Argentina

The lower levels of the Lipeón Formation, in the Eastern Cordillera, north-west Argentina, yield a marine-dominated palynomorph assemblage, together with graptolites of mid to late mid Llandovery age (Demirastrites convolutus and probably Stimulograptus sedgwickii zones). The palynomorph assemblage is dominated by acritarchs, but also contains algae and terrestrial cryptospores. Crassiangulina variacornuta, considered a potentially good global biostratigraphical marker for the Upper Llandovery is recovered for the first time from the Silurian of Argentina. The occurrence of this species in strata not younger than late Aeronian, and independently dated by graptolites, indicates an early first appearance for Crassiangulina variacornuta, in the Lipeón Formation, below the Aeronian/Telychian boundary. The lower part of the unit corresponds to a quiet marine environment; thus supporting that Crassiangulina variacornuta is a facies-sensitive acritarch.     

Cyrtocrinids (Echinodermata,Crinoidea) from Upper Jurassic Štramberk‐type limestones in southern Poland

Abstract: A systematic account of highly diverse cyrtocrinid faunules from Upper Jurassic strata of ?tramberk type (Oxfordian–Tithonian) in southern Poland (Polish Carpathians) is presented. Fourteen taxa (Phyllocrinus malbosianus, Ph. stellaris, Ph. sp., Psalidocrinus armatus, Sclerocrinus compressus, S. polonicus sp. nov., Hemicrinus aff. kabanovi, Ancepsicrinus parvus gen. et sp. nov., Tetracrinus baumilleri sp. nov., Eugeniacrinites alexandrowiczi, E. cf. moravicus, E. sp., Eudesicrinus gluchowskii sp. nov. and Hemibrachiocrinus tithonicus sp. nov. are described and illustrated. Representatives of the genus Eudesicrinus, previously recorded only from the Lower Jurassic, are here shown to extend into the uppermost Jurassic. Other cyrtocrinids considered are common in Jurassic/Cretaceous strata across Europe. In the present faunules, isocrinid (Isocrinida), comatulid (Comatulida) and roveacrinid (Roveacrinida sensu Rasmussen, inclusive of Saccocoma) crinoids are associated.     

Early Silurian (Telychian) rugose coral fauna of Daguan area, northeast Yunnan province, China

Study on rugose coral fauna of the Sifengya Formation (early Telychian) and Daluzhai Formation (mid-late Telychian) in Daguan area, northeast Yunnan Province, China was carried out. Rugose coral fauna of the Sifengya Formation included 18 genera and 34 species, while Daluzhai Formation with nine genera, ten species. We described rugose coral fauna (12 genera, 19 species) including one new genus and five new species, i.e. Protoketophyllum daguanense gen. et sp. nov., Crassilasma huanggexiense sp. nov., Pseudophaulactis heae sp. nov., P. convolutus sp. nov., and Shensiphyllum minor sp. nov. The characteristics and geological significance of rugose coral fauna of Sifengya Formation and Daluzhai Formation were analyzed. Particularly, rugose coral fauna of the Sifengya Formation represent early Telychian rugosan fauna in the Upper Yangtze region and improve the sequences of early Silurian (Llandovery) rugose coral assemblages in Yangtze region. It is therefore very meaningful to further analyze radiation period of rugose coral fauna in such epoch. __________ Translated from Acta Palaeontologica Sinica, 2005, 44(2): 229–246 [译自: 古生物学报, 2005, 44(2): 229–246]     

Silurian radiolarians from the Jenolan Caves region,New South Wales,Australia

Moderately-preserved Silurian radiolarians have been recovered from the Jenolan Caves region, eastern NSW, Australia. Radiolarians were first reported from this area in the late 19th Century by T.W. Edgeworth David, but were not described in detail, neither were they illustrated. Nearly 120 years later, the first images of these fossils are presented. The radiolarians reported include: ?Futobari cf. solidus Furutani, ?Zadrappolus sp., Haplentactiniid gen. and sp. indet, Borisella sp., ?Palaeoephippium sp., ?Insolitignum vivanima MacDonald and ?Helenifore speciosus (Furutani). The fauna is similar to others described from Upper Silurian strata in Japan.     

Sorbus cibagouensis sp. nov. (Rosaceae) from Zayü County,southeastern Xizang,China

Sorbus cibagouensis sp. nov. (Rosaceae subfam. Rosaceae), a new taxon from Cibagou National Nature Reserve, Zayü County, southeastern Xizang (Tibet), China, is described and illustrated. It is related to S. monbeigii (Cardot) Balakr., but primarily differs in the number of styles (S. cibagouensis = 5; S. monbeigii = 4) and the shape of stipules and leaves (S. cibagouensis: stipules caducous, small, with entire margin, leaflets in 9–11 pairs; S. monbeigii: stipules persistent, large, serrate, leaflets in 6–8 (–10) pairs).     

A new diverse shark fauna from the Wordian (Middle Permian) Khuff Formation in the interior Haushi‐Huqf area,Sultanate of Oman

Abstract: Chondrichthyans are newly reported from the autochthonous Wordian Khuff Formation (middle Permian), cropping out in well‐exposed, low‐palaeolatitude sections in the interior Haushi‐Huqf area of Oman. The shark remains comprise isolated teeth, dermal denticles and fin spines and have been recovered by processing limestone in buffered acetic acid from bulk rock samples. The fauna consists of mainly ctenacanthiform and hybodontiform taxa, identified as Glikmanius cf. myachkovensis, Glikmanius culmenis sp. nov., Omanoselache hendersoni gen. et sp. nov., Omanoselache angiolinii gen. et sp. nov., cf. Omanoselache sp., Reesodus underwoodi gen et sp. nov., Teresodus amplexus gen. et sp. nov., Gunnellodus bellistriatus, Khuffia lenis gen. et sp. nov., Khuffia prolixa gen. et sp. nov. and Euselachii sp. indet. Additional specimens include rare teeth of the lonchidiid cf. ‘Palaeozoic Genus 1’ sp., of the neoselachian Cooleyella cf. fordi and a further indeterminate neoselachian, of an indeterminate petalodont and of the holocephalan Deltodus aff. mercurei and Solenodus cf. crenulatus. Fin spines add a further two taxa, Nemacanthus sp. and Amelacanthus cf. sulcatus, which have neoselachian affinities and therefore an unclear relationship to the recovered teeth. The occurrence of Nemacanthus within this Wordian fauna represents the oldest record of this taxon and its only known occurrence in the Palaeozoic. Of the remaining genera, Glikmanius has previously been recorded from the Wordian, whereas for all the others, this study represents their youngest known stratigraphic occurrence and first occurrence in Guadalupian (middle Permian) strata. This adds significantly to our knowledge of the global diversity of chondrichthyans preceding the end‐Guadalupian biotic crisis. Palaeogeographically, for all taxa, this study represents the first record from the western fringe of the marine Neotethyan basin, and only Cooleyella was previously known from the southern (Gondwanan) part of the Pangaean continental margin.     

The first record of genus Neocsikia Ôhira & Becker (Coleoptera,Elateridae, Dimini) in China,with the description of a new species

The click-beetle genus Neocsikia Ôhira & Becker, 1972 is newly recorded from Xizang, China upon the discoveries of Neocsikia nepalensis Ôhira & Becker, 1972 and N. xuhaoi Qiu, sp. nov. Neocsikia nepalensis is redescribed based on the type material from Nepal and material collected in Nyalam County, Xizang, China. Neocsikia xuhaoi Qiu, sp. nov. is described based on the material collected in Mêdog County, Xizang, China. Both species are illustrated and their principal diagnostic features are provided. A key to the species of Neocsikia is presented.https://www.zoobank.org/urn:lsid:zoobank.org:pub:1B7F59D5-02BC-4739-9B71-B560DA341FF3     

AMMONOIDS AND THE TRIASSIC/JURASSIC BOUNDARY IN THE HIMALAYAS OF SOUTHERN TIBET

Abstract:  The sections of Germig in the Nyalam area, southern Tibet, provide a continuous exposure of ammonoid-bearing, uppermost Triassic and basal Jurassic strata. Eighteen species (three of them new) are described and illustrated: Choristoceras marshi Hauer , C. aff. marshi, C. cf. nobile Mojsisovics , C. nyalamense sp. nov., Eopsiloceras germigense sp. nov. , Pleuroacanthites aff. biformis (Sowerby) , Rhacophyllites sp., Nevadaphyllites cf. psilomorphus (Neumayr), Neophyllites sp. indet., Neophyllites cf. biptychus (Lange), Psiloceras tibeticum sp. nov., P. calliphyllum (Neumayr), Euphyllites cf. struckmanni (Neumayr), Discamphiceras pleuronotum (Canavari), Alsatites spp., Kammerkarites frigga , and K. sp. The ammonoid fauna shows a strong affinity to that of the Northern Calcareous Alps, although diversity in the Calliphyllum Zone is markedly lower. The ammonoid succession across the Triassic/Jurassic boundary is subdivided into four zones: the Rhaetian Marshi, the basal Hettangian Tibeticum, the lower Hettangian Calliphyllum, and the middle Hettangian Pleuronotum zones. It is the only known succession across the Triassic/Jurassic boundary in the Tethyan Realm that is not condensed. The Marshi and Calliphyllum zones are correlated with the same zones in the Northern Calcareous Alps. The Tibeticum Zone, a new local zone, is transitional between the Marshi and the Calliphyllum zones in that it yields both choristoceratids and psiloceratids. Its base is taken to mark the base of the Jurassic System in the eastern Tethys.     

Stratigraphy of the Lungmachi black shales from the Huaying drill core in southwestern China and its palaeogeographic implications

Core samples from the Huaying well, Sichuan Province, have been analyzed for both graptolite biostratigraphy and carbon isotope chemostratigraphy. The result shows a stratigraphic sequence of Lituigraptus convolutus, Stimulograptus sedgwickii and Spirograptus guerichi biozones, and records a strong positive shift of δ¹³C_org at the base of the Stimulograptus sedgwickii Biozone, which coincides with those from Cornwallis Island (Arctic Canada), Arisaig (Nova Scotia, Canada), and the Barrandian area (Bohemia). Two outcrops were also studied in the Huaying region. The Yanwanggou section shows a continuous, but complicated, stratigraphical sequence, from the upper Katian to the lower–middle Rhuddanian, then a sedimentary hiatus of ∼3.26 Ma, and finally a continuous sequence from the upper Aeronian to the lower Telychian, whereas the Liziya section and the Huaying well exhibit significant hiatus, which lasted from Hirnantian to middle Rhuddanian or early Aeronian times. Therefore, the eastern boundary of the Central Sichuan Oldland during the Ordovician and Silurian transition can be precisely constrained to a narrow area between the Huaying well-Liziya section and the Yanwanggou section, which indicates that the Central Sichuan Oldland was much larger than previously considered. The present data also indicate the existing of a so far unidentified stage of the Kwangsian Orogeny, which resulted in the uplift of some portions of the Yangtze Platform region and the consequent delay of the transgression in those places. The multi-stage hiatus, spanning at least from the upper Katian to middle Aeronian in the study area, resulted from a combined effect of the Hirnantian glacio-eustatic sea-level fall and the regional tectonic activity of the Kwangsian Orogeny.