Morphological and molecular phylogenetic analysis of two Saprolegnia sp (Oomycetes) isolated from silver crucian carp and zebra fish

Two Saprolegnia isolates, JY isolated from silver crucian carp (Carassius auratus gibelio Bloch) and BMY isolated from zebra fish (Brachydanio rerio Hamilton) came from infections occurring concurrently in different locations in China. To confirm whether the two isolates were from the same Saprolegnia clone, comparative studies have been carried out based on their morphological, physiological and molecular characteristics. Observations showed that morphologically (both asexual and sexual organs) the two isolates were broadly similar and both isolates under-went repeated zoospore emergence. Comparing 704 base pairs of internal transcribed spacer (ITS) region and the 5.8S rDNA, we found isolates JY and BMY shared an identical ITS sequence with a minor variation (99.6 % similarity). Forty available sequences for representatives Saprolegnia spp. belonged to four phylogenetically separate clades. The two studied isolates fell within clade I that comprised a group of isolates which showed almost an identical ITS sequence but had been identified as a number of different morphological species. our findings suggest that isolates JY and BMY appear to belong to the S. ferax clade and this clade (1) contains a number of closely related phylogenetic species. This is distinct from the more common fish pathogenic isolates, which belong to the S. parasitica clade (III) and are characterized by having cysts decorated by bundles of long hooked hairs and two further clades (II and IV) containing largely saprotrophic or soil born species. (C) 2009 Published by Elsevier Ltd on behalf of The British Mycological Society.

Influence of Potamogeton crispus growth on nutrients in the sediment and water of Lake Tangxunhu

An incubation experiment was performed on Potamogeton crispus (P. crispus) using sediment collected from Lake Tangxunhu in the center of China, in order to determine the effects of plant growth on Fe, Si, Cu, Zn, Mn, Mg, P, and Ca concentrations in the sediments and overlying waters. After 3 months of incubation, Ca, Mg, and Si concentrations in the water column were significantly lower, and P and Cu concentrations were significantly higher than in unplanted controls. The effect of P. crispus growth on sediment pore waters and water-extractable elements varied. Concentrations of Ca, Mg, Si, Fe, Cu, and Zn were significantly higher, and P was significantly lower, than in pore waters of the control. Water-extracted concentrations of Fe, Mg, and Si in the sediments were lower, and P was higher, than in the control. Presence of P. crispus generally enhanced concentration gradients of elements between pore waters and overlying waters but not for P. The growth of P. crispus was associated with an increase in water pH and formation of root plaques, resulting in complex effects on the sediment nutritional status.

Synopsis of the species of Myxobolus Butschli, 1882 (Myxozoa : Myxosporea : Myxobolidae)

A synopsis of 744 nominal species of Myxobolus Butschli, 1882 (Myxozoa, Myxosporea, Myxobolidae) is presented. For each species, the relevant morphometric and morphological data are indicated, as well as the host(s), site(s) of infection within the host and type-locality.

Retroposon analysis of major cetacean lineages: The monophyly of toothed whales and the paraphyly of river dolphins

SINE (short interspersed element) insertion analysis elucidates contentious aspects in the phylogeny of toothed whales and dolphins (Odontoceti), especially river dolphins. Here, we characterize 25 informative SINEs inserted into unique genomic loci during evolution of odontocetes to construct a cladogram. and determine a total of 2.8 kb per taxon of the flanking sequences of these SINE loci to estimate divergence times among lineages. We demonstrate that: (i) Odontocetes are monophyletic; (ii) Ganges River dolphins, beaked whales, and ocean dolphins diverged (in this order) after sperm whales; (iii) three other river dolphin taxa, namely the Amazon, La Plata, and Yangtze river dolphins, form a monophyletic group with Yangtze River dolphins being the most basal; and (iv) the rapid radiation of extant cetacean lineages occurred some 28-33 million years B.P., in strong accord with the fossil record. The combination of SINE and flanking sequence analysis suggests a topology and set of divergence times for odontocete relationships, offering alternative explanations for several long-standing problems in cetacean evolution.

The quantum tunnelling between two-component Bose-Einstein condensates in a double-well configuration

We examine in terms of exact solutions of the time-dependent Schrodinger equation, the quantum tunnelling process in Bose-Einstein condensates of two interacting species trapped in a double well configuration. Based on the two series of time-dependent SU(2) gauge transformations, we diagonalize the Hamilton operator and obtain analytic time-evolution formulas of the population imbalance and the berry phase. the particle population imbalance (a(L)(+)aL - a(R)(+)a(R)) of species A between the two wells is studied analytically.

The quantum tunneling between two-component Bose-Einstein condensates in a double-well configuration

In terms of exact solution of the time-dependent Schrodinger equation. we examine the quantum tunneling process in Bose condensates of two interacting species trapped in a double well configuration. We use the two series of time-dependent SU(2) gauge transformation to diagonalize the Hamilton operator obtain analytic time-evolution formulas of the population imbalance and the berry phase. The particle population imbalance (a(L)(+)a(L) - a(R)(+)a(R)) of species A between the two wells is studied analytically.

针对C语言的自动微分系统及其应用

采用切线性模式和代码转换策略,开发了C语言自动微分转换系统(DTC),用于牛顿法求解非线性方程中Jacobi矩阵—向量乘积计算。介绍系统计算模型、功能、特色,并讨论系统的设计与实现技术,包括编译技术、微分代码转换及输入/输出(I/O)相关分析。最后给出了几个具有说服力的测试与应用。

金属酞菁对单加氧酶的模拟

合成Mn~(++)、Fe~(++)、Co~(++)、Cu~(++)、Zn~(++)过渡金属酞菁和Sn~(++)酞菁，并对它们作了红外、紫外和元素分析。用上述金属酞菁、抗坏血酸和分子氧构成了一种新的单加氧酶和化学模拟体系，发现都可以在常温、常压下使苯羟化成酚。其中以铁酞菁活性最高，反应八小时苯的克分子转化率可达0.7%左右，其余（包括铈酞菁）大约比铁体系活性低20倍，约为0.02%～0.04%。与典型的模拟单加氧酶Udenfriend试剂比较，在没有丙酮等有机介质的情况下具有更高的活性。考察了抗坏血酸浓度、P~H值。底物苯的加入量以及温度等对羟化反应起始吸氧速度、苯的转化率的影响。发现，羟化反应速度与加入反应的抗坏血酸浓度成反比；中性、微酸性介质（P~H=4.7）对羟化反应有利，温度以35℃为宜；在抗坏血酸浓度较低时，苯的转化率几乎与其成正比关系，在浓度大于1M/g时，苯转化率的提高就比较小了。考察了含氮的各种胺类及含氧的丙酮等配位对化学模拟体系中Fe~(++)活性的影响。发现Fe~(++)周围的N原子数与铁离子的比例按1：1、1：2、1：3、1：4增加时铁模拟体系的活性几乎成正比提高，但是这又不如铁酞菁体系的活性，说明含N大环配位体-酞菁对铁离子的活化更为优越。并利用量子化学的概念对此作了解释。发现以往作为分散剂而加入到体系中的丙酮也是一种可以活化Fe~(++)的配位体。根据实验事实以及反应液的电子光谱分析，对羟化反应机理作了探讨，提出Fe~(++)、抗坏血酸(AsH_2)与适当配位体在微酸性介质中(P~H=4.7)形成中间三元络合物是羟化反应的第一步，指出G.A.Hamilton等人提出的“Oxenoid”机理忽略了适当配位体的重要作用；指明了Udenfriend试剂中的CDTA以及本实验所用的各种胺和丙酮的作用实质。提出Fe~(++)、适当配位体在低浓度和高浓度的抗坏血酸溶液中形成五配位和六配位的中间三元络合物，二者处于化学平衡状态。因为只有五配位的中间三元络合物才有活性，园满地解释了在抗坏血酸浓度低时羟化反应速度反而高于高浓度的这一反常的实验现象。根据五配位中间三元络合物的模型，进一步指出在模拟体纱中抗坏血酸不仅仅起到了授氢体的作用，它与单加氧酸酶P-450辅基的轴向第五配位体-含硫的胱氨酸残基类似，在分子氧的还原断裂中起着非常重要的作用。根据实验中的一些现象，对中间双氧络合物的存在也提出了看法。

海底沉积物声衰减同轴差距衰减测量法与其他测量方法的对比研究

以精度较高的现场测量Hamilton的原位测量所得数据为标准，对比研究了钱正明的直立同轴衰减测量法、刘强

支承弹簧对输液曲管固有频率和极限流速的影响

基于Hamilton变分原理,导出具有弹性支撑的1/4圆形输液曲管的变分—积分方程.采用多个函数组合的方法,选取满足边界条件的试函数,利用Galerkin直接法求出系统的固有频率和极限流速的近似解析公式.数值结果表明,弹簧对固有频率和极限流速都有显著影响.根据数值结果,用最小二乘法给出固有频率和极限流速与弹簧刚度的关系公式

不同积分变分原理的统一

依据定量因果原理的数学表示,统一地导出了Lagrange量中含坐标关于时间一阶、二阶导数的积分型的Hamilton原理、Voss原理、Hlder原理和Maupertuis-Lagrange原理等,给出了这些原理的本质联系和统一描述.得出f0=0并不是通常的保持Euler-Lagrange方程不变的结果,而是满足定量因果原理的结果.还得出Lagrange量的所有的积分型变分原理等价地对应于两类满足定量因果原理的不变形式.同时发现所有积分型变分原理的运动方程都是Euler-Lagrange方程,但不同条件的变分原理所对应的不同群G作用下的守恒量是不同的.从而可对过去众多零散的积分型变分原理有一个系统和深入的理解,并使这些变分原理自然地成为定量因果原理的推论.

Unified expressions of all integral variational principles

In terms of the quantitative causal principle, this paper obtains a general variational principle, gives unified expressions of the general, Hamilton, Voss, Holder, Maupertuis-Lagrange variational principles of integral style, the invariant quantities of the general, Voss, Holder, Maupertuis-Lagrange variational principles are given, finally the Noether conservation charges of the general, Voss, Holder, Maupertuis-Lagrange variational principles axe deduced, and the intrinsic relations among the invariant quantities and the Noether conservation charges of all the integral variational principles axe achieved.

Identification of a quasiparticle band in very neutron-rich Zr-104

The high spin levels of a very neutron-rich Zr-104 nucleus have been reinvestigated by measuring the prompt. rays in the spontaneous fission of Cf-252. The ground-state band has been confirmed. A new sideband has been identified with a band-head energy at 1928.7 keV. The projected shell model is employed to investigate the band structure of Zr-104. The results of calculated levels are in good agreement with the experimental data, and suggest that the new band in Zr-104 may be based on the neutron nu 5/2(-)[532] circle times nu 3/2(+)[411] configuration.