Immunoglobulin joining (J) chain and its expression in the Chinese soft-shelled turtle (Pelodiscus sinensis)

The immunoglobulin (Ig) joining (J) chain plays an important role in the formation of polymeric Igs and their transport into secretions. In the present study, the cDNA sequence of J chain has been cloned from the Chinese soft-shelled turtle (Pelodiscus sinensis) by reverse transcription (RT)-PCR and rapid amplification of cDNA ends (RACE). The cDNA sequence is 2347 bp in length and contains an open reading frame of 480 bp encoding 160 aa including the signal sequence. The deduced amino acid sequence has a high degree of homology with that of an already reported turtle J chain (80.7%), and of chicken (71.3%). By using real-time quantitative RT-PCR analysis, a significant up-regulation of J-chain transcripts was observed in spleen, kidney and blood of turtles injected with inactivated Aeromonas hydrophila, indicating the immune role of J chain in response to bacterial infection. (C) 2009 Elsevier B.V. All rights reserved.

IgM, IgD and IgY and their expression pattern in the Chinese soft-shelled turtle Pelodiscus sinensis

Three Ig isotypes, IgM, IgD, and IgA, were previously known in reptiles. Here, in this report we describe IgM, IgD and a novel immunoglobulin heavy-chain isotype upsilon (IgY) in Chinese soft-shelled turtle (Pelodiscus sinensis). The IgM and IgY constant domains are characteristically similar to their counterparts described in other vertebrates. The expression of IgM and IgD were detected at mRNA level early during embryonic development, and their expression increased during further development. However, the IgY expression was not detected in larval turtles until 90 days after hatching-out. The increase in the transcription of these three Ig molecules was analyzed by using real-time PCR in spleen, kidney and blood following the injection of inactivated Aeromonas hydrophila. The primary increase in the expression of these three Igs was observed I week after the first injection, although not statistically significant, and the second injection 2 weeks after the first injection provoked a significant increase in the expression of these Igs, revealing a pattern of primary and secondary antibody response in the turtle. The present study represents the first report on reptile IgY and the pattern of IgM, IgD and IgY transcription in reptiles. (C) 2009 Elsevier Ltd. All rights reserved.

Molecular characterization and expression profiles in response to bacterial infection of Chinese soft-shelled turtle interleukin-8 (IL-8), the first reptilian chemokine gene

In this study, an IL-8 homologue has been cloned and identified from a reptile, Chinese soft-shelled turtle for the first time. The full-length cDNA of turtle IL-8 was 1188 bp and contained a 312 bp open reading frame (ORF) coding for a protein of 104 amino acids. The chemokine CXC domain, which contained Glu-Leu-Arg (ELR) motif and four cysteine residues, was well conserved in turtle IL-8. The 4924 bp genomic DNA of turtle IL-8 contained four exons and three introns. Phylogenetic analysis showed that the amino acid sequence of turtle IL-8 clustered together with birds. RT-PCR analysis showed that turtle IL-8 mRNA was constitutively expressed liver, spleen, kidney, heart, blood and intestine tissues of control turtles. Real-time quantitative PCR analysis further indicated that the turtle IL-8 mRNA expression was apparent in various tissues at 8 h and up-regulated significantly during 8 h-7 d after Aeromonas hydrophila infection. The present studies will help us to understand the evolution of IL-8 molecule and the inflammatory response mechanism in reptiles. (C) 2009 Elsevier Ltd. All rights reserved.

Identification of differentially expressed immune-relevant genes in Chinese soft-shelled turtle (Trionyx sinensis) infected with Aeromonas hydrophila

Expressed sequence tag (EST) analysis is an efficient tool for gene discovery and profiling gene expression. Aeromonas hydrophila, a ubiquitous waterborne bacterium, is one of the most frequent pathogens isolated from diseased aquatic organisms. In order to understand the molecular mechanism of anti-bacteria immune response in reptile, we have investigated the differentially expressed genes in Chinese soft-shelled turtle (Trionyx sinensis) experimentally infected with A. hydrophila by suppression subtractive hybridization (SSH). Forty-two genes were identified from more than 200 clones, of which 25 genes are found for the first time in reptiles, and classified into 6 categories: 18 in defense/immunity. 4 in catalysis, 2 in retrotransposon; 2 in cell signal transduction, 5 in cell metabolism, 10 in protein expression, and 1 in cell structure. Of the 42 differentially expressed genes, 6 genes, IL-8, serum amyloid A (SAA), CD9, CD59, activating transcription factor 4 (ATF4) and cathepsin L genes, were further observed to be up-regulated in the infected turtles by virtual Northern hybridization and RT-PCR assays. (C) 2008 Elsevier B.V. All rights reserved.

Isolation and characterization of microsatellites in Chinese soft-shelled turtle, Pelodiscus sinensis

Fifteen polymorphic microsatellite loci were developed for the Chinese soft-shelled turtle (Pelodiscus sinensis) from the (GT)(n) microsatellite-enriched genomic library, using the fast isolation by amplified fragment length polymorphism of sequences containing repeats protocol. The polymorphism of all 15 loci ranged from two to seven alleles with observed heterozygosities ranging from 0.03 to 0.98 (mean 0.43) in one population of 40 individuals. These novel loci will be helpful for understanding the population structure at genetic level and marker-assisted breeding of this vulnerable species.

Effects of animal-plant protein ratio in extruded and expanded diets on nitrogen and energy budgets of juvenile Chinese soft-shelled turtle (Pelodiscus sinensis Wiegmann)

In this study, we investigated the effects of animal-plant protein ratio in extruded and expanded diets on nutrient digestibility, nitrogen and energy budgets of juvenile soft-shelled turtle (Pelodiscus sinensis). Four extruded and expanded feeds (diets 1-4) were formulated with different animal-plant protein ratios (diet 1, 1.50:1; diet 2, 2.95:1; diet 3, 4.92:1; diet 4, 7.29:1). The apparent digestibility coefficients (ADCs) of dry matter and crude lipid for diet 1 were significantly lower than those for diets 2-4. There was no significant difference in crude protein digestibility among diets 1-4. The ADC of carbohydrate was significantly increased with the increase in animal-plant protein. Although nitrogen intake rate, faecal nitrogen loss rate and excretory nitrogen loss rate of turtles fed diet 1 were significantly higher than those fed diets 2-4, nitrogen retention rate, net protein utilization and biological value of protein in these turtles were significantly lower than those fed diets 2-4. In addition, energy intake rate, excretory energy loss rate and heat production rate of turtles fed diet 1 were also significantly higher than those fed diets 2-4. Faecal energy loss was significantly reduced with the increase in the animal-plant protein ratio. The ADC of energy and assimilation efficiency of energy significantly increased with a higher animal-plant protein ratio. The growth efficiency of energy in the group fed diet 1 was significantly lower than those in the groups fed diets 2-4. Together, our results suggest that the optimum animal-plant protein ratio in extruded and expanded diets is around 3:1.

Co doping enhanced giant magnetocaloric effect in Mn1-xCoxAs films epitaxied on GaAs (001)

A giant magnetocaloric effect was found in series of Mn1-xCoxAs films epitaxied on GaAs (001). The maximum magnetic entropy change caused by a magnetic field of 4 T is as large as 25 J/kg K around room temperature, which is about twice the value of pure MnAs film. The observed small thermal hysteresis is more suitable for practical application. Growing of layered Mn1-xCoxAs films with Co concentration changing gradually may draw layered active magnetic regenerator refrigerators closer to practical application. Our experimental result may provide the possibility for the combination of magnetocaloric effect and microelectronic circuitry.

Electronic structures of wurtzite ZnO, BeO, MgO and p-type doping in Zn1-xYxO (Y = Mg, Be)

Using the density function theory within the generalized gradient approximation, the band structures of wurtzite ZnO, BeO and MgO have been calculated. The effective-mass parameters are fitted using the calculated eigenvalues. The Dresselhaus spin-orbit effect appears in the k[1 00] direction, and is zero in the high symmetry direction k[00 1]. The orderings of valence band split by the crystal-field and spin-orbit coupling in wurtzite ZnO, BeO and MgO are identified by analyzing the wave function characters calculated by projecting the wave functions onto p-state in the spherical harmonics. For wurtzite ZnO, the ordering of valence band is Still Gamma(7) > Gamma(9) > Gamma(7) due to the negative spin-orbit coupling splitting energy and the positive crystal-field splitting energy. Thus, the Thomas' conclusion is confirmed. For wurtzite BeO and MgO, although their orderings of valence bands are Gamma(7) > Gamma(9) > Gamma(7) too, the origins of their orderings are different from that of wurtzite ZnO. Zn1-x,YxO (Y = Mg, Be) doped with N and P atoms have been studied using first-principles method. The calculated results show that N atom doped in Zn1-x BexO has more shallow acceptor energy level with increasing the concentration of Be atom. (C) 2008 Elsevier B.V. All rights reserved.

Influence of Si doping on magnetic properties of (Ga,Mn)As

We have systematically investigated the magnetic properties of Si-doped (Ga,Mn)As films. When the Si content is low, both Curie temperature (T-C) and carrier density (p) decrease compared with undoped (Ga,Mn)As, whereas a monotonic increase of T-C and p is observed with further increase in the doping content of Si. We discuss the possible mechanism for the changes obtained by different Si doping contents and attribute the results to a competition between the existence of Si-Ga (Si substitutes for Ga site) that acts as a donor and Si-I (Si interstitials) which is in favor of the improvement of ferromagnetism. (C) 2008 Elsevier B.V. All rights reserved.

Electronic structure and optical properties of GaN with Mn-doping

Calculations of the electronic structure and the density of states of GaN with Mn are carried out by means of first-principles plane-wave pesudopotential method based on density functional theory. The results reveal a 100% spin polarized impurity band in band structure of Ga1-xMnxN due to hybridization of Mn 3d and N 2p orbitals. The material is half metallic and suited for spin injectors. In addition, a peak of refractive index can be observed near the energy gap. The absorption coefficient increases in the UV region with the increase of the Mn content.

Mg acceptor energy levels in AlxInyGa1-x-yN quaternary alloys: An approach to overcome the p-type doping bottleneck in nitrides

The Mg-Ga acceptor energy levels in GaN and random Al8In4Ga20N32 quaternary alloys are calculated using the first-principles band-structure method. We show that due to wave function localization, the MgGa acceptor energy level in the alloy is significantly lower than that of GaN, although the two materials have nearly identical band gaps. Our study demonstrates that forming AlxInyGa1-x-yN quaternary alloys can be a useful approach to lower acceptor ionization energy in the nitrides and thus provides an approach to overcome the p-type doping difficulty in the nitride system.

Origin of the doping bottleneck in semiconductor quantum dots: A first-principles study

Doping difficulty in semiconductor nanocrystals has been observed and its origin is currently under debate. It is not clear whether this phenomenon is energetic or depends on the growth kinetics. Using first-principles method, we show that the transition energies and defect formation energies of the donor and acceptor defects always increase as the quantum dot sizes decrease. However, for isovalent impurities, the changes of the defect formation energies are rather small. The origin of the calculated trends is explained using simple band-energy-level models.

The bipolar doping of ZnS via native defects and external dopants

By employing first-principle total-energy calculations, a systematic study of the dopability of ZnS to be both n- and p-types compared with that of ZnO is carried out. We find that all the attempted acceptor dopants, group V substituting on the S lattice site and group I and IB on the Zn sites in ZnS, have lower ionization energies than the corresponding ones in ZnO. This can be accounted for by the fact that ZnS has relative higher valence band maximum than ZnO. Native ZnS is weak p-type under S-rich condition, as the abundant acceptor V-Zn has rather large ionization energy. Self-compensations by the formation of interstitial donors in group I and IB-doped p-type ZnS can be avoided when sample is prepared under S-rich condition. In terms of ionization energies, Li-Zn and N-S are the preferred acceptors in ZnS. Native n- type doping of ZnS is limited by the spontaneous formation of intrinsic V-Zn(2-); high efficient n-type doping with dopants is harder to achieve than in ZnO because of the readiness of forming native compensating centers and higher ionization energy of donors in ZnS. (C) 2009 American Institute of Physics. [DOI 10.1063/1.3103585]