Ultrastructure of mature spermatozoa of
was studied by transmission electron microscopy and its phylogenetic implications are discussed for the first time in this paper. The mature spermatozoon is composed of a head which contains a cone-shaped acrosome, a round nucleus and a tail region. The subacrosomal space is less electron dense which contains a homogeneous material. No axial rod and a basal plate were observed in subacrosomal space. No anterior invagination exists in the nucleus, but an inverted shallow V-shaped posterior invagination is visible. Nuclear lacunae could be seen clearly although the nucleus is highly condensed. Within the mid-piece of the spermatozoon there exist five spherical mitochondria while the long whip-like end portion is composed of an axoneme with the typical 9 + 2 structure. The spermatozoon of
is a product of the evolution of the reproductive system of the family Arcidae. Whether the particular acrosome, subacrosomal space, or the highly condensed nucleus might be adaptations of high fertilization rate in the particular environment of this species is discussed.
The h-index and EigenfactorTM values of top and specialized scientific/engineering journals are tabulated and combined to provide a simple graphical representation
of the journals. The information may be tailored to specific uses by respective stakeholders to aid decision making processes
with regards to scholarly research and scientific journal publications.
Authors:Yang-Xi Yu, Qing-Yin Zhang and Guang-Hua Gao
In order to predict extraction equilibria for uranyl nitrate and nitric acid between aqueous and tributyl phosphate (TBP)-hydrocarbon diluent solutions, activity coefficient equations for the three components in the system HNO3-UO2(NO3)2-H2O were derived and the general equation for excess Gibbs energy, proposed by Clegg and Pitzer, simplified. The activity coefficient equations comprise a Debye-Hückel term and a Margules expansion carried out to the four suffix level, where the higher order electrostatic contribution was neglected. The binary parameter was determined from the thermodynamic properties of the two relevant aqueous solutions. The three mixing parameters were obtained by correlating data for the partial pressure of nitric acid over HNO3-UO2(NO3)2-H2O solutions at 298.15 K. By using the mixing parameters, the activity coefficients of the ternary system can be calculated with good accuracy, and the solubility of uranyl nitrate in aqueous nitric acid with concentration up to 14 mol/kg can be satisfactorily predicted.
Authors:Xiao Wei Zhao, Guo Yu Zhang, Lin Yang, Jia Xi Qiang and Zi Qiang Chen
Li-ion batteries with LiFePO4/C composites are difficult to be charged at low temperatures. In order to improve the low temperature performance of LiFePO4/C power batteries, the charge–discharge characteristics were studied at different temperatures, and a new charging mode under low temperature was proposed. In the new charging mode, the batteries were excited by current pulses with the charge rates between 0.75 C and 2 C, while the discharge rates between 3 and 4 C before the conventional charging (CC–CV). Results showed that the surface temperature of Li-ion battery ascended to 3 °C at the end of pulse cycling when the environment temperature was −10 °C. Comparing with the conventional charging, the whole charge time was cut by 36 min (23.4%) and the capacity was 7.1% more at the same discharge rate, respectively.
Authors:Changwei Lu, Yufen Zhang, Xuehua Yang, Yunxian Chen, Tonggeng Xi and Jingkun Guo
The criterion of forming the carbon layer on the interface of the SiC fiber reinforced lithium alumino-silicate (LAS) composite
studied by thermodynamic and mass spectrometric thermal analysis was presented for the first time in this paper.
Authors:Peng Sun, Cunquan Yuan, Li Dai, Yang Xi, Yunfei Li, Ruiyang Hu, Yuhan Sun, Zhaohe Xu and Yun Li
Emasculation and bagging of flowers, which are widely used in the controlled pollination of monoclinous plants, may induce premature senescence, flower abscission and low fruit set. To determine the mechanism responsible for these phenomena, levels of abscisic acid (ABA), jasmonic acid (JA), indole-3-acetic acid (IAA), ethylene, soluble sugars, reducing sugars and free amino acids in black locust (Robinia pseudoacacia) flowers subjected to different treatments were quantified at different developmental stages. The phytohormones and assimilates were also quantified in untreated flowers to investigate the presence of discernible patterns. The levels of ethylene and ABA in emasculated and bagged (EB) flowers increased prematurely compared with those of untreated flowers, whereas the content of reducing sugars in EB flowers decreased compared with that of untreated flowers. These results indicated that the premature increase in ethylene and ABA synthesis, and the decrease in reducing sugars content, in EB flowers may cause flower abscission and result in low fruit set, which may be relevant for assimilate applications and future research on the regulation of controlled pollinations with exogenous phytohormones.
Authors:Zong-Xi Cao, Pei-Rong Jiao, Yu-Mao Huang, Hong-Yang Qin, Liu-Wu Kong, Quan-Hui Pan, Yi-Min He and Gui-Hong Zhang
To understand the genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) in South China, we collected 231 clinical samples from pigs with suspected PRRSV infection in Guangdong between 2007 and 2009. We found that 74 of 231 samples were positive by RT-PCR. The PCR products of the ORF5 gene of 35 isolates from different farms were sequenced and their DNA sequences were compared to 23 other PRRSV isolates in the GenBank. We found that the nucleotide similarity among all South China isolates ranged from 87.6% to 100%, and all belonged to the North American genotype. Most of them were classified into subgenotype I, but the rest mapped to subgenotypes III, V or VI. Those in subgenotypes I and III were found to be highly variable in the primary neutralising epitope (PNE) with a specific amino acid mutation (F39/L39→I39), and a few isolates in subgenotypes I and III isolates also had a mutation at L41 (L41→S41). PRRSV isolates in subgenotypes III, V and VI had less potential glycosylation sites than those in subgenotype I. Our data contribute to the understanding of molecular variation of PRRSV in South China.
Authors:Xiang-Rong Xu, Fu-Qing Tan, Jun-Quan Zhu, Ting Ye, Chun-Lin Wang, Yi-Feng Zhu, Hans-Uwe Dahms, Fan Jin and Wan-Xi Yang
We used single-cell gel electrophoresis (SCGE) to detect the integrity of sperm DNA of the teleost large yellow croaker, Pseudosciaena crocea, cryopreserved with Cortland solution and a range of 5% to 30% DMSO concentrations in order to test how sperm cryopreservation affected the DNA stability of nuclei. Electrophoresis was conducted for 60 min at 130 mA and 15 V. The comet images were analyzed with software CometScore 1.5, and parameters such as comet length, tail length and percentage DNA in the tail were obtained. Then the comet rate and damage coefficient were calculated. Results demonstrated that there were no significant differences in motility, comet rate and damage coefficient between fresh sperm and cryopreserved sperm stored in 5%, 10%, 15% and 20% DMSO, while the sperm cryopreserved with 25% and 30% DMSO had a lower motility, higher comet length and damage coefficients than those of fresh sperm. There was a positive correlation between comet rate of cryopreserved sperm and the concentration of DMSO. Our results demonstrate that toxicity of the cryoprotectant is the main cause of DNA damage in cryopreserved sperm nuclei.