Molecular characterization of common carp (Cyprinus carpio) Sonic Hedgehog and discovery of its maternal expression

Sonic hedgehog (Shh), one of important homologous members of the hedgehog (Hh) family in vertebrates, encodes a signaling molecule that is involved in short- or long-range patterning processes during embryogenesis. In zebrafish, maternal activity of Hh was found to be contributing to the formation of primary motoneurons. However, we found that all of the known Hh members were not maternally expressed in zebrafish. In the present study, full-length cDNA of common carp (Cyprinus carpio) Shh (cShh) was gained by degenerate reverse-transcription PCR (RT-PCR) and rapid amplification of cDNA ends. Sequence comparison shows that cShh coding sequence shares 93.4% identity with zebrafish Shh coding sequence, and their corresponding protein sequences have 91.9% similarity. Comparative analysis of Shh genomic sequences and Hh protein sequences from different species revealed that the genomic structures of Hh are conserved from invertebrate to vertebrate. In contrast to zebrafish Shh, cShh transcripts were detectable from one-cell stage by RT-PCR analysis. Whole mount in situ hybridization verified the maternal expression of Shh in common carp, which is, to our knowledge, the first report of that in vertebrates, suggesting that Shh might be responsible for the maternal Hh activity in common carp.

Chemical kinetics and self-ignition in a model supersonic hydrogen-air combustor

Self-ignition tests of a model scramjet combustor were conducted by using parallel sonic injection of gaseous hydrogen from the base of a blade-like strut into a supersonic vitiated airstream. The range of stagnation pressure and temperature studied varied from 1.0 to 4.5 MPa and from 1300 to 2200 K, respectively. Experimental results show that the self-ignition limit, in terms of either global or local quantities of pressure and temperature, exhibits a nonmonotonic behavior resembling the classical homogeneous explosion limit of the hydrogen-oxygen system. Specifically, for a given temperature, increasing pressure from a low value can render a nonignitable mixture to first become ignitable, then nonignitable again, This correspondence shows that, despite the globally supersonic nonpremixed configuration studied herein, ignition is strongly influenced by the intricate chemical reaction mechanism and thereby exhibits the homogeneous explosion character. Consequently, self-ignition criteria based on a global reaction rate approximating the complex chemistry are inadequate. An auxiliary computational study on counterflow ignition was also conducted to systematically investigate the contamination effects of vitiated air. Results indicate that the net contamination effects for the present experimental data are expected to be substantially smaller than contributions from the individual contamination species because of the counterbalancing influences of the H2O-inhibition and NO-promotion reactions in effecting ignition.

Combustion and Ignition of Thermally Cracked Kerosene in Supersonic Model Combustors

A series of experiments were conducted to characterize the self-ignition and combustion of thermally cracked kerosene in both a Mach 2.5 model combustor with a combustor entrance height of 51 mm and a Mach 3.0 model combustor with an entrance height of 70 mm. A unique kerosene heating and delivery system was developed, which can prepare heated kerosene up to 950 K at a pressure of 5.5 MPa with negligible fuel coking. The extent of China no. 3 kerosene conversion under supercritical conditions was measured using a specially designed system. The compositions of gaseous products as a result of thermal cracking were analyzed using gas chromatography. The mass flow rates of cracked kerosene were also calibrated and measured using sonic nozzles. With the injection of thermally cracked kerosene, the ability to achieve enhanced combustion performance was demonstrated under a variety of airflow and fuel conditions. Furthermore, self-ignition tests of cracked kerosene in a Mach 2.5 model combustor over a range of fuel injection conditions and with the help of different amounts of pilot hydrogen were conducted and discussed.

Experimental Study on Hydrodynamic Behaviors of High-Speed Gas Jets in Still Water

The present paper describes experimental investigation on the flow pattern and hydrodynamic effect of underwater gas jets from supersonic and sonic nozzles operated in correct- and imperfect expansion conditions. The flow visualizations show that jetting is the flow regime for the submerged gas injection at a high speed in the parameter range under consideration. The obtained results indicate that high-speed gas jets in still water induce large pressure pulsations upstream of the nozzle exit and the presence of shock-cell structure in the over- and under-expanded jets leads to an increase in the intensity of the jet-induced hydrodynamic pressure.

Experimental studies on self-ignition of hydrogen/air supersonic combustion

Self-ignition tests of a model scramjet combustor were conducted by using parallel sonic injection of gaseous hydrogen from the base of a blade-like strut into a supersonic airstream, The vitiated air was produced by burning H-2, O-2, and air to a stagnation temperature of 1000-2100 K and a stagnation pressure of 0.8-1.6 MPa, The effects of different parameters on the self-ignition limits were analyzed, In addition, the effects of the combustor's different wall configurations on self-ignition limits were specifically studied. It was found that the wall configurations of the combustor had a significant effect on self-ignition limits, which might have variations of 420-840 K deg in stagnation temperature; however, the local static temperature in the recirculation zones for different wall configurations remained the same at approximately 1100 K, It was found that self-ignition could initiate at the exit of the combustor and this can be considered as a weak self-ignition characteristic.

Numerical-simulation of low supersonic-flow around a sphere

The controlled equations defined in a physical plane are changed into those in a computational plane with coordinate transformations suitable for different Mach number M(infinity). The computational area is limited in the body surface and in the vicinities of detached shock wave and sonic line. Thus the area can be greatly cut down when the shock wave moves away from the body surface as M(infinity) --> 1. Highly accurate, total variation diminishing (TVD) finite-difference schemes are used to calculate the low supersonic flowfield around a sphere. The stand-off distance, location of sonic line, etc. are well comparable with experimental data. The long pending problem concerning a flow passing a sphere at 1.3 greater-than-or-equal-to M(infinity) > 1 has been settled, and some new results on M(infinity) = 1.05 have been presented.

Performance of a Supersonic Model Combustor using Vaporized Kerosene Injection

Characteristics of supersonic combustion by injecting kerosene vapor into a Mach 2.5 crossflow at various preheat temperatures and pressures were investigated experimentally. A two-stage heating system has been designed and tested, which can prepare heated kerosene of 0.8 kg up to 820 K at pressure of 5.5 Mpa with minimum/negligible fuel coking. In order to simulate the thermophysical properties of kerosene over a wide range of thermodynamic conditions, a three-component surrogate that matches the compound class of the parent fuel was employed. The flow rate of kerosene vapor was calibrated using a sonic nozzle. Computed flow rates using the surrogate fuel are in agreement with the experimental data. Kerosene jets at various preheat temperatures injecting into both quiescent environment and Mach 2.5 crossflow were visualized. It was found that at injection pressure of 4 Mpa and preheat temperature of 550 K the kerosene jet was completely in vapor phase, while keeping almost the same penetration depth as compared to the liquid kerosene injection. Supersonic combustion tests were also carried out to compare the combustor performance for the cases of vaporized kerosene injection, liquid kerosene injection, and effervescent atomization with hydrogen barbotage, under the similar stagnation conditions. Experimental results demonstrated that the use of vaporized kerosene injection leads to better combustor performance. Further parametric study on vaporized kerosene injection in a supersonic model combustor is needed to assess the combustion efficiency as well as to identify the controlling mechanism for the overall combustion enhancement.

Catalytic Cracking and Heat Sink Capacity of Aviation Kerosene Under Supercritical Conditions

Catalytic cracking of China no. 3 aviation kerosene using a zeolite catalyst was investigated under supercritical conditions. A three-stage heating/cracking system was specially designed to be capable of heating 0.8 kg kerosene to a temperature of 1050 K and pressure of 7.0 MPa with maximum mass flow rate of 80 g/s. Sonic nozzles of different diameters were used to calibrate and monitor the mass flow rate of the cracked fuel mixture. With proper experiment arrangements, the mass flow rate per unit throat area of the cracked fuel mixture was found to well correlate with the extent of fuel conversion. The gaseous products obtained from fuel cracking under different conditions were also analyzed using gas chromatography. Composition analysis showed that the average molecular weight of the resulting gaseous products and the fuel mass conversion percentage were a strong function of the fuel temperature and were only slightly affected by the fuel pressure. The fuel conversion was also shown to depend on the fuel residence time in the reactor, as expected. Furthermore, the heat sink levels due to sensible heating and endothermic cracking were determined and compared at varying test conditions. It was found that at a fuel temperature of similar to 1050 K, the total heat sink reached similar to 3.4 MJ/kg, in which chemical heat sink accounted for similar to 1.5 MJ/kg.

Thermal cracking of aviation kerosene for scramjet applications

Thermal cracking of China No.3 aviation kerosene was studied experimentally and analytically under supercritical conditions relevant to regenerative cooling system for Mach-6 scramjet applications. A two-stage heated tube system with cracked products collection/analysis was used and it can achieve a fuel temperature range of 700-1100 K, a pressure range of 3.5-4.5 MPa and a residence time of approximately 0.5-1.3 s. Compositions of the cracked gaseous products and mass flow rate of the kerosene flow at varied temperatures and pressures were obtained experimentally. A one-step lumped model was developed with the cracked mixtures grouped into three categories: unreacted kerosene, gaseous products and residuals including liquid products and carbon deposits. Based on the model, fuel conversion on the mass basis, the reaction rate and the residence time were estimated as functions of temperature. Meanwhile, a sonic nozzle was used for the control of the mass flow rate of the cracked kerosene, and correlation of the mass flow rate gives a good agreement with the measurements.

A Wide Band Strong Acoustic Absorption in a Locally Network Anechoic Coating

Composite materials with interpenetrating network structures usually exhibit unexpected merit due to the cooperative interaction. Locally resonant phononic crystals (LRPC) exhibit excellent sound attenuation performance based on a periodical arrangement of sound wave scatters. Inspired by the interpenetrating network structure and the LRPC concept, we develop a locally network anechoic coating (LNAC) that can achieve a wide band of underwater strong acoustic absorption. The experimental results show that the LNAC possesses an excellent underwater acoustic absorbing capacity in a wide frequency range. Moreover, in order to investigate the impact of the interpenetrating network structure, we fabricate a faultage structure sample and the network is disconnected by hard polyurethane (PU). The experimental comparison between the LNAC and the faultage structure sample shows that the interpenetrating network structure of the LNAC plays an important role in achieving a wide band strong acoustic absorption.

Locally resonant phononic woodpile: A wide band anomalous underwater acoustic absorbing material

To meet the demand of modern acoustic absorbing material for which acoustic absorbing frequency region can be readily tailored, we introduced woodpile structure into locally resonant phononic crystal (LRPC) and fabricated an underwater acoustic absorbing material, which is called locally resonant phononic woodpile (LRPW). Experimental results show that LRPW has a strong capability of absorbing sound in a wide frequency range. Further theoretical research revealed that LRPC units and woodpile structure in LRPW play an important role in realization of wide band underwater strong acoustic absorption.

Mutation analysis of a large Chinese pedigree with congenital preaxial polydactyly

Mutations in the long-range limb-specific cis-regulator (ZRS) could cause ectopic shh gene expression and are responsible for preaxial polydactyly (PPD). In this study, we analyzed a large Chinese isolated autosomal dominant PPD pedigree. By fine mapping

东亚人群 LMBR1 基因 Intron 5的遗传多样性研究

人LMBR1(Limb region 1 homolog (mouse)) 基因位于染色体7q36区域，全长约210.2 kb，含17个外显子，编码一个由490个氨基酸构成的跨膜蛋白。研究表明，LMBR1 基因的表达活性与脊椎动物四肢的手指或脚趾数目变化有关；另外，发生在其重要元件——intron 5 内的许多变异与多种表型的轴前多指症((PPD, Preaxial polydactyly)存在相关性，这主要是因为LMBR1 intron 5 内含有一个与骨骼系统发育有关的基因（SHH(Sonic hedgehog)基因）的远程顺式调控元件。本研究旨在探究LMBR1基因 intron 5 内的遗传多样性，进而评估HapMap计划的样本选择策略，并检测该区域是否受自然选择的作用。 国际人类基因组单体型图计划(HapMap Project，The International Haplotype Map Project) 于2002年10月正式启动，该计划旨在构建人类基因组中常见变异的遗传图式。自其数据发布以来，广泛应用于生物医学、群体遗传学等领域，在复杂疾病的遗传机理研究、自然选择的检测等方面做出了前所未有的贡献；但是HapMap计划中样本的代表性有待评估。 本研究中，我们综合考虑地理来源信息及线粒体单倍型类群 (Haplogroup)信息选择了41个东亚人作为样本（以保证样本的代表性），测定位于LMBR1 基因intron 5 内的目的片段中存在的单核苷酸多态性(SNP, Singe nucleotide polymorphism)位点，通过所得数据与HapMap数据的比较，发现二者之间差异显著且HapMap数据不能覆盖所有我们得到的常见变异，因而我们认为：HapMap计划中国部分的样本选择策略有待进一步完善。 关于自然选择的研究不仅可以使我们了解生物的进化机制，同时还对复杂疾病的遗传机理研究具有重要的提示作用，因而，对于自然选择的检测，一直以来都是生物学研究的重点。平衡选择是一种维持遗传多态性的自然选择方式，现已发现很多与特定疾病或性状相关的基因或调控序列受平衡选择的作用，如 G6PD 基因、PTC 基因、FMO3 基因、FSHB 基因及 CCR5 基因5’端顺式调控区等我们对41个东亚样本中LMBR1 intron 5 内一段长为9256 bp (Chr7: 156280954-156271699 (Build36))的序列进行以 Tajima’s D 检验为主的群体遗传学分析，发现该区域在进化历程中受到平衡选择的作用。LMBR1 intron 5 内的多态位点与多种表型的多指症存在相关性，受其调控的 SHH 基因在骨骼系统发育中具有重要作用，人类骨骼系统的适应性进化等三方面的因素为该区域受平衡选择的作用提供了进一步的佐证。 总之，本研究对HapMap计划的样本选择策略和数据应用提供了一定的参考；同时还发现一个与骨骼系统发育有关的基因调控元件受平衡选择的作用。

云南中部无量山大寨子黑长臂猿（Nomascus concolorjingdongensis）生态与行为研究

从2003年3月到2006年5月期间，在云南中部无量山大寨子（24°21′N, 100°42′E）对一个黑长臂猿种群进行了研究。2003年3月至2004年3月主要研究了 3个群体的鸣叫行为。2005年3月一个群体被习惯化，随后对其进行了14个月的连 续观察。在此期间，主要对食性、时间分配、栖息地选择和利用、过夜地及过夜 树的选择等方面进行了研究。这些资料将有助于了解黑长臂猿对其高海拔、高纬 度、季节性变化明显栖息地的适应性，并且对了解长臂猿独特的社会结构具有重 要意义。另外，本研究结合获得的行为生态方面的数据，通过漩涡模型（VORTEX） 对该种群未来动态进行了模拟，对大寨子种群的保护和发展提出了保护建议。 黑长臂猿叫声在所有长臂猿中频率最高。成年雄性能发出boom、简单重复 音节和调节音节；成年雌性只能发出成功的激动鸣叫和失败的激动鸣叫。两者互 相配合组成结构复杂的二重唱，配对个体很少单独鸣叫，青年个体经常会加入二 重唱。同一群内两个成年雌性多数时候一起鸣叫。配对个体平均两天鸣叫一次 （53%），每次鸣叫平均持续时间12.9 分钟，雌性激动鸣叫4.6 次，激动鸣叫的 平均时间间隔为115 秒，91.5%的鸣叫发生在日出前半小时和日出后3 小时之间。 通过对相邻群体间鸣叫行为的分析，结果发现相邻群体倾向于不在同一天鸣叫， 如果同一天鸣叫，鸣叫的时间间隔显著长于不在同一天鸣叫的时间间隔，这些结 果不支持鸣叫具有调节群体空间距离的功能（inter-group spacing）的假说。雄性 倾向选择一个区域内最高的树进行鸣叫，这可能是为了声音的远距离传播。另外 雄性对鸣叫树的选择也兼顾了安全因素。通过比较鸣叫前后个体间的距离，黑长 臂猿的鸣叫具有群内通讯的功能，鸣叫后个体间的距离显著短于鸣叫前的距离。 虽然鸣叫树的分布与食物斑块的分布在不同海拔段和不同网格内都呈现出了高 度的相关性，但不能确定黑长臂猿在食物斑块附近进行鸣叫就是为了对食物资源 进行防御。 利用扫描法对研究群体的食性和时间分配进行了研究。结果显示研究群体共 取食77 种植物和至少6 种动物，其中10 种重要食物占到取食比例的76.7%。在 10396 次确定食物类别的记录中，除无花果外的其它果实占25.5%，藤子叶和芽占21.0%，树叶和芽占19.2%，无花果占18.6%，花占9.1%，寄生植物的叶占6.3%， 另外其它食物占0.3%。黑长臂猿的食性具有明显的日变化和季节性变化。与其 它长臂猿相比，黑长臂猿的食性更加广泛。虽然黑长臂猿进食叶（藤子的叶和芽、 树叶和芽、寄生植物的叶）的比例稍多于进食果实（无花果和其它果实）的比例， 但当果实丰富时，它们仍然优先选择果实。 黑长臂猿平均在日出后33 分钟离开过夜树，在日落前128 分钟进入过夜树， 平均每天活动518 分钟。活动期间，黑长臂猿用于休息的时间最多，达到40.0%， 其次是取食28.7%，排在第三的是移动19.8%，排在第四的是觅食占到6.1%，鸣 叫占2.6%，玩耍和其它活动一共占活动时间的2.8%。时间分配具有明显的日变 化和季节性变化。食物和温度因素是影响黑长臂猿时间分配季节性变化的最主要 的原因。 群体一共利用129 个1 公顷的网格，如果包含在活动路线内的空隙，活动范 围达到151 公顷，主要由3 个大的山沟组成。黑长臂猿平均每天移动1391 米， 进入9 个网格，连续两天倾向于利用家域中的同一条山沟。群体平均每月仅利用 家域的19%~50%，集中利用家域中的小部分区域，除2 月份外群体总是选择利 用原始常绿阔叶林。形成这种现象的原因主要与食物的分布及其季节性变化有 关、并且与该群生活地区的地形有关。 黑长臂猿喜欢选择高大的，生长在陡坡上的树过夜，群体一般形成4 个不同 的小单元过夜（青年个体与成年雄性睡在一起，两个成年雌性与未独立的婴猿分 别睡在一起，亚成年雄性单独过夜），过夜时总是快速进入过夜树，然后立即安 静下来，利用很多棵不同的过夜树，并且间隔很长时间后才重复利用，这些行为 都是为了避免被捕食者发现和攻击。群体喜欢在山坡上过夜，并且在冬天喜欢选 择在长有寄生植物的大树枝上过夜，这些行为可能与研究地点冬天的低气温有 关。此外，过夜树的选择可能兼顾舒适和方便寻找食物的功能。 通过获得的生态学资料，结合近缘种生态学参数，利用漩涡模型（VORTEX） 对该种群未来动态进行了模拟。结果显示：大寨子亚种群是一个具有很强的潜在 繁殖力的种群，如果没有偷猎，亚种群在100a 之内不会灭绝，并且能迅速达到 环境容纳量。但是每年如果有1 只成年雄性和1 只成年雌性被猎杀，该种群将会在第78a 灭绝，且灭绝概率为100%。不同程度的死亡率对种群影响不大，但高 死亡率显著延缓了种群到达环境容纳量的时间。环境容纳量对种群遗传多样性损 失具有重要的影响，在没有猎杀的情况下，种群的长期存活需要一个较大的环境 容纳量。因此，在黑长臂猿受到严格保护、且栖息地主要在保护区内的今天，严 密监控火灾的发生，限制牲畜进入林区等人为干扰的影响，保护好黑长臂猿栖息 地是首要工作之一。但如果能使其栖息地周围的森林植被得到恢复，增加其栖息 范围，将有利于该地区黑长臂猿的发展。