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Molecular profiling of behavioural development: differential expression of mRNAs for inositol 1,4,5-trisphosphate 3-kinase isoforms in naive and experienced honeybees (Apis mellifera).

In seeking genetic factors that may control the extended behavioural maturation of adult honeybees we found that inositol 1,4,5-trisphosphate (IP(3)) 3-kinase, a key enzyme in the IP(3)-mediated signalling cascade, is differentially expressed in brains of naive, newly emerged bees and experienced foragers. DNA sequencing yielded a contig of 21.5 kb spanning the honeybee IP(3)K locus and a 3' flanking gene similar to a transcription factor NFR-kappa-B. The IP(3)K locus gives rise to three differentially expressed major transcripts produced by alternative splicing that encode proteins with identical, highly conserved C-termini and distinct, non-conserved N-terminal domains. The type A transcript is dominant in the adult brain and its level of expression increases threefold during the first 4 days of adult development. The type B message is expressed in brains of naive bees, but is also found in the thorax and abdomen, whereas transcript C is expressed largely in non-neural tissues and in the antenna. In contrast to type A message, the brain levels of transcript B decrease during the first 4 days of adult life. Our data are evaluated in the context of the contrasting behavioural phenotypes of immature and experienced worker honeybees.

Animals↗

Identification of differentially expressed genes induced in the rat brain by acetyl-L-carnitine as evidenced by suppression subtractive hybridisation.

Acetyl-L-carnitine (ALC) is a molecule widely present in the central nervous system (CNS) formed by the reversible acetylation of carnitine. It acts by stimulating energy metabolism. Reported neurobiological effects of this substance include modulation of brain energy and phospholipid metabolism; cellular macromolecules (including neurotrophic factors and neurohormones); synaptic transmission of multiple neurotransmitters. ALC is of considerable interest for its clinical application in Alzheimer's disease and in the treatment of painful neuropathies. There are experimental data that it affects attention and antagonizes deterioration of ability to learn, improving long-term memory. Moreover, ALC influences nonassociative learning of sensitization type in Hirudo medicinalis. These findings are suggesting that ALC might exert its effects by means of new protein synthesis. ALC or saline solution was injected intraperitoneally each day for 21 days in rats. Poly(A)+ RNAs were isolated from control and treated rat brain. Suppression subtractive hybridisation (SSH) method was applied for the generation of subtracted cDNA libraries and the subsequent identification of differentially expressed transcripts after treatments. The technique generates an equalized representation of differentially expressed genes irrespective of their relative abundance, and it is based on the construction of forward and reverse cDNA libraries that allow the identification of the genes that are regulated or switched off/on after ALC treatment. We identified two modulated genes, the isoform gamma of 14-3-3 protein and a precursor of ATP synthase lipid-binding protein, and one gene switched on by the treatment, the heat shock protein hsp72.

14-3-3 Proteins↗

Identification of differentially expressed proteins of gamma-ray irradiated rat intestinal epithelial IEC-6 cells by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry.

To identify proteins involved in the processes of cellular and molecular response to radiation damage repair in intestinal epithelial IEC-6 cells, we comparatively analyzed the proteome of irradiated IEC-6 cells with that of normal cells. A series of methods were used, including two-dimensional gel electrophoresis (Z-DE), PDQuest software analysis of 2-DE gels, peptide mass fingerprinting based on matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS), and Swiss-Prot database searching, to separate and identify differentially expressed proteins. Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) were used to validate the differentially expressed proteins. Image analysis revealed that averages of 608 +/- 39 and 595 +/- 31 protein spots were detected in normal and irradiated IEC-6 cells, respectively. Sixteen differential protein spots were isolated from gels, and measured with MALDI-TOF-MS. A total of 14 spots yielded good spectra, and 11 spots matched with known proteins after database searching. These proteins were mainly involved in anti-oxidation, metabolism, and protein post-translational processes. Western blotting confirmed that stress-70 protein was down-regulated by gamma-irradiation. Up-regulation of ERP29 was confirmed by RT-PCR, indicating that it is involved in ionizing radiation. The clues provided by the comparative proteome strategy utilized here will shed light on molecular mechanisms of radiation damage repair in intestinal epithelial cells.

Animals↗

Direct isolation of differentially expressed genes from a specific chromosome region of common wheat: application of the amplified fragment length polymorphism-based mRNA fingerprinting (AMF) method in combination with a deletion line of wheat.

The amplified restriction fragment length polymorphism (AFLP)-based mRNA fingerprinting (AMF) method makes it possible systematically and conveniently to identify differentially expressed cDNAs with high reproducibility. We have applied the AMF method to the cloning of the Q gene of common wheat, which is located on the long arm of chromosome 5A and pleiotropically controls the spike morphology and the threshing character of seeds. Using the AMF method, we compared the fingerprints of mRNA samples extracted from the young spikes of Triticum aestivum cv. Chinese Spring (CS) carrying the Q gene to those of a chromosome deletion line of CS, namely, q5, which lacks 15% of 5AL including the Q gene. Approximately 12,200 fragments were produced after PCR with 256 primer combinations. Of these, 92 fragments were differentially expressed between CS and q5. Northern and Southern analyses showed that 16 fragments gave specific or relatively stronger transcript signals in CS, and these clones were present in single copy or in low copy numbers in the wheat genome. Four clones were genetically mapped to the region deleted in q5. Subsequently, one clone, pTaQ22, was mapped at the same locus as the Q gene, indicating that pTaQ22 corresponds to the Q gene or is tightly linked to it. DNA sequence data showed that pTaQ22 had no homology to any known genes, thus suggesting a novel function for this gene in flower morphogenesis. This AMF method might provide a straightforward method for isolating genes in the hexaploid background of common wheat.

Base Sequence↗

Differential expression of HLA-DR, HLA-DP, and HLA-DQ antigenic determinants of the major histocompatibility complex in human endometrium.

We reported on the expression of HLA-DR molecules of the major histocompatibility complex in human endometrium. We now report on the expression of two other class II molecules, the HLA-DP and HLA-DQ determinants. These molecules were localized by monoclonal antibodies in 11 proliferative and 12 secretory endometria by avidin-biotin-complex (ABC) procedure. The expression of all three molecules was invariable and consistent throughout the entire menstrual cycle in endothelial and lymphoid cells. HLA-DR molecules were expressed in endometrial epithelium, particularly in the basalis in the mid to late proliferative phases of the cycle. In contrast, through the entire menstrual cycle, the expression of HLA-DP and HLA-DQ antigenic determinants was absent, and only occasionally a focal expression of these molecules was seen in endometrial epithelium. The in vitro induction of expression of the class II molecules in human endometrial epithelial cell cultures (HEE) by IFN-gamma was dose-dependent. After treatment with low doses of IFN-gamma, these cells primarily expressed HLA-DR molecules in vitro. The differential expression of the molecules of the major histocompatibility complex in human endometrial epithelium in vivo may be due to the differential sensitivity of th epithelium in response to cytokine(s).

Antibodies, Monoclonal↗

Effect of rosiglitazone on the differential expression of diabetes-associated proteins in pancreatic islets of C57Bl/6 lep/lep mice.

The insulin sensitizer drug, rosiglitazone, has been shown to have a protective effect on pancreatic islet cell structure and function in animal models of type 2 diabetes. The identification of new molecular targets associated both with islet cell dysfunction and protection is a crucial research goal. In the present study, a proteomics approach has been used to identify such targets. Obese C57Bl/6J lep/lep mice and lean littermates were given the insulin sensitizer drug BRL49653, rosiglitazone. It normalized the impaired glucose tolerance in lep/lep mice but had no significant effect on glucose tolerance in the lean mice. Pancreatic islet polypeptides were arrayed by a two-dimensional gel electrophoresis system that separated more than 2500 individual spots. Three overexpressed and six underexpressed proteins were significant (p < 0.05) between lep/lep and lean mice, and four were modulated significantly (p < 0.05) by the rosiglitazone treatment of the obese mice. The identity of these differentially expressed proteins was made using mass spectrometric analysis and provided evidence that differential expression of actin-binding proteins may be an important aspect of defective islet function. Rosiglitazone increased carboxypeptidase B expression in both lep/lep and normal mice suggesting that this might be an independent effect of rosiglitazone that contributes to improved insulin processing.

Animals↗

Differential expression of U2AF35 in the arthritic joint of avian reovirus-infected chicks.

To identify cell types and genes that are differentially expressed during immunopathogenesis of avian reovirus (ARV)-induced viral arthritis (VA), we inoculated arthrotropic strain S1133 of ARV into 1-day-old broilers, and examined tissue histology as well as RNA expression at different days post-inoculation (PI). Using immunohistochemical staining, we detected many CD68 expressing macrophages in and around the blood vessels of the arthritic joints. By RT-PCR, we found that expression of matrix metalloproteinase-2 (MMP-2) and bone morphogenetic protein-2 (BMP-2) was induced earlier in footpads and hock joints of ARV-infected chickens. By employing suppression subtractive hybridization (SSH) technique and RT-PCR, we further identified that small subunit of U2 snRNP auxiliary factor (U2AF35 or U2AF1) mRNA was differentially induced in the joint of ARV-infected chickens. By in situ hybridization (ISH), mRNA signals of U2AF35 and BMP-2 were located in chondrocytes within/near the epiphyseal plate and secondary center of ossification, and in epidermal cells and dermal fibroblast-like cells of arthritic joints. In addition, U2AF35 mRNA was expressed in the inflammatory infiltrates of the bone marrow of ARV-infected arthritic joints, while MMP-2 was mainly detected in chondrocytes. Interestingly, among U2AF35, MMP-2, and BMP-2 that were differentially expressed in the joint of ARV-infected chickens, only U2AF35 induction correlated well with arthritic manifestation. Because U2AF35 may assist in mRNA splicing of proinflammatory chemokines and cytokines, our results indicated that U2AF35 induction might play an immunopathological role in ARV-induced arthritis. This study has first associated U2AF35 to viral arthritis.

Animals↗

Identification and partial characterization of differentially expressed mRNAs in normal human endometria and endometrial carcinomas by differential display RT-PCR.

Differential display methodology was employed to examine and compare the mRNA species derived from normal endometrial tissue and endometrial carcinoma (grade 3, stage III) tissue biopsies. Two cDNA sequences, one expressed in the tumour group only (T19) and the other expressed only in the normal group (N22), were selected for verification of differential expression by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The expression of N22 was restricted to the normal group, suggesting a possible tumour suppressing function. Sequence analysis of this fragment revealed a high degree of similarity to a human cDNA sequence of unknown function. The expression of T19 mRNA was observed in both normal and neoplastic tissues, however the relative abundance was significantly higher in endometrial carcinomas. Expression of T19 mRNA was further examined in a larger clinical sample set and was significantly increased in the tumours (n = 16), with a three-fold increase when compared with the normal endometria, n = 5 (Kruskal-Wallis analysis of variance, P<0.05). Subsequent sequence analysis of T19 revealed a high degree of similarity to the 3' untranslated region of a rat growth factor responsive gene, SM-20. Further characterization of these mRNA transcripts may lead to the identification of novel genes involved in endometrial tumourogenesis.

3' Untranslated Regions↗

Identification of mRNAs differentially-expressed between benign and malignant breast tumour cells.

Two suppression subtracted cDNA libraries have been constructed, one containing cDNAs to mRNAs present at a higher level in a benign human breast tumour-derived cell line relative to the malignant mammary cell line, MCF-7, and the other containing cDNAs present at a higher level in the MCF-7 cells relative to the benign cells. Randomly-picked cloned DNAs have been sequenced yielding 29 and 128 different cDNAs from the benign and malignant libraries, respectively. Using reverse Northern hybridisation, 76% and 83% of the cDNAs were differentially expressed by greater than two-fold, whilst 14% and 11% of cDNAs in the respective libraries were differentially expressed by more than 15-fold. Amongst these were oestrogen-responsive cDNAs and expressed sequence tags. One such oestrogen-responsive expressed sequence tag, M41, is transcribed from a gene located on chromosome 21q22.3, within an intron of a larger gene. The M41 gene contains oestrogen response elements, one of which is associated with alu repeats. M41 mRNA is expressed at a statistically significantly higher level in human breast cancer specimens than in normal human breast and benign lesions. In carcinomas, its up-regulation is associated with the development of the malignant cell.

Breast↗

Differential expression of adenosine A1 receptors in colorectal cancer and related mucosa.

Adenosine A1 receptors (A1R) are known to inhibit while the A2 receptors (A2R) stimulate the G-protein cAMP second messenger system and may play a role in cell growth and carcinogenesis. Using a quantitative reverse transcription-polymerase chain reaction (RT-PCR) method, mRNA for A1R and A2R was measured in human colorectal adenocarcinomas and individual peritumoural colon tissues. There was differential expression of the mRNA for A1R with tumour tissues having significantly higher amounts compared to peritumoural normal tissues. The mRNA for A2R was not found to be differentially expressed. The increase in the inhibitory A1 receptor in tumour tissues may be in response to increased adenosine release from the hypoxic cells found in malignant tumour tissues, thus indicating a possible role for the adenosine A1 receptor in carcinogenesis.

Adult↗

Low molecular weight fibroblast collagen: structure, secretion, and differential expression as a function of fetal and cellular age.

A unique low molecular weight collagen that was highly resistant to proteolytic degradation was originally isolated from fetal calf ligamentum nuchae fibroblasts and hence termed FCL-1 [Sage, H., Mecham, R., Johnson, C., & Bornstein, P. (1983) J. Cell Biol. 97, 1933-1938]. The differential expression of this protein was studied as a function both of fetal (donor) age and of subcultivation in vitro. Concomitant isolation, subculture, and metabolic radiolabeling experiments performed on cell strains from fetal calf ligament (FCL) and fetal bovine skin (FBS) representing different gestational ages (85-270 days in utero) showed that (a) FCL-1 was synthesized preferentially by fibroblasts from younger animals and (b) expression of FCL-1 diminished as a function of increased passage in culture. Levels of FCL-1, measured as percent of total radiolabeled culture medium protein that precipitated in a concentration range of 20-50% ammonium sulfate, ranged from 22% in FCL 85 cells to 7.7% in FCL 270 (term) cells. FBS fibroblasts at passages 6-10 secreted from 13% to 6% FCL-1, respectively. When cells from an 85-day fetal ligament were allowed to accumulate copious extracellular matrix in vitro, the production of FCL-1 was increased to 32%. FCL-1 was not immunoreactive with polyclonal antibodies directed toward most of the sequences of the interstitial type I and type III procollagens. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the apparent molecular weight of FCL-1 was 13 000 (on the basis of collagen peptide standards) and approximately 30 000 (on the basis of globular protein standards). Incubation with bacterial collagenase produced a stable cleavage product of Mr 8000 (by collagen standards) or 17 000 (by globular standards). In contrast, pepsin removed a small peptide of approximately 1000-2000 in molecular weight from FCL-1, and a gradual but progressive proteolysis of the collagen was observed over a period of 1-6 h. Pulse-chase studies revealed a secretion time of approximately 60 min for FCL-1, without the appearance of any processed, intermediate forms. These studies confirm that FCL-1 represents a novel member of the collagen gene family that manifests differential expression as a function of development.

Animals↗

Differential expression of group I metabotropic glutamate receptors in human motoneurons at low and high risk of degeneration in amyotrophic lateral sclerosis.

Glutamate excitotoxicity has been suggested to play a role in amyotrophic lateral sclerosis, since overstimulation of post-synaptic glutamate receptors by accumulated extracellular glutamate leads to motoneuron cell death. It is however unclear as to why some groups of motoneurons degenerate in this disease while other groups remain relatively intact even during terminal stages of the disease. Our previous studies in the rat showed differential expression of group I metabotropic glutamate receptors in motoneurons at low and high risk of degeneration in amyotrophic lateral sclerosis. Here we have extended this study to normal human brains. In situ hybridization showed that transcripts of both metabotropic glutamate receptor (mGluR) 1 and mGluR5 were expressed in motoneurons in both the resistant motor nucleus III and the vulnerable motor nucleus XII. Immunolabeling of mGluR1alpha and mGluR5 was found in both motoneurons and glia-like cells in all the motor nuclei and the ventral horn of the cervical spinal cord studied. Quantitative analysis of optical density measurements showed higher levels of mGluR1alpha protein expression but lower levels of mGluR5 protein expression in the vulnerable motoneuron pool (VII, XII and spinal cord) than in the resistant motoneuron pool (III, IV and VI). This differential expression of group I metabotropic glutamate receptor proteins within vulnerable motoneuron pools may predispose these neurons to degeneration as seen in amyotrophic lateral sclerosis.

Central Nervous System↗

Analysis of the complete sequence of the novel metastasis-associated candidate gene, mta1, differentially expressed in mammary adenocarcinoma and breast cancer cell lines.

To understand the genes and gene products involved in breast cancer invasion and metastasis, we previously isolated ten differentially expressed genes by differential cDNA library screening techniques, using the 13762NF rat mammary adenocarcinoma metastatic system. In this study, we further analysed a novel candidate metastasis-associated gene, mta1, previously designated clone 10.14. Northern blotting analyses showed that the steady-state mRNA expression level of mta1 was fourfold higher in a highly metastatic line (MTLn3) than in a nonmetastatic line (MTC.4). The mta1 gene was expressed at low levels in various normal rat organs, except testis, where it was expressed in high amounts. The mRNA expression levels of the human homologue of this gene were also examined in two human breast cancer metastatic systems; the ratios of mRNA were estimated to be MCF-7 (nonmetastatic):MCF7/LCC1 (invasive):MCF7/LCC2 (metastatic) = 1:2:4 and MDA-MB-468 (nonmetastatic):MDA231 (metastatic) = 1:4. Thus, the expression of this gene directly correlated with metastatic potential in two human systems, as well as in the rat metastatic system. Clone 10.14 was used to isolate a full-length cDNA clone for mta1, yielding the clone p10.14-C4.5, which was sequenced and analysed. Clone p10.14-C4.5 was 2756-bp long and contained a single open reading frame that could encode a protein of 703 amino acid (aa) residues. The aa sequence of mta1 was found to be novel by database homology search and contained possible phosphorylation sites for tyrosine kinase, protein kinase C and casein kinase II. A Pro-rich stretch was found at the C-terminal end that completely matched the consensus sequence for the SH3-binding motif.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗

Differential expression of phenylpropanoid and related genes in brown-midrib bm1, bm2, bm3, and bm4 young near-isogenic maize plants.

The expression of phenylpropanoid and related genes was investigated in bm1, bm2, bm3, and bm4 near-isogenic maize plants at the 4-5 leaf stage using a gene-specific cell wall macro-array. The bm3 mutant, which is mutated in the caffeic acid O-methyltransferase (COMT) gene, exhibited the lowest number of differentially expressed genes. Although no other phenylpropanoid gene had an altered expression, two distinct OMT and two cytochrome P450 genes were overexpressed suggesting the activation of alternative hydroxylation/methylation pathways. The bm1 mutant had the highest number of differentially expressed genes, all of which were under-expressed. Bm1 mutant plants were affected not only in cinnamyl alcohol dehydrogenase (bm1 related CAD) gene expression as expected, but also in the expression of other CAD/SAD gene family members and several regulatory genes including MYB, ARGONAUTE and HDZip. As originally believed, the bm1 mutation could be localized at the CAD locus, but more probably in a gene that regulates the expression of the CAD gene family. The profile of under-expressed genes in the bm2 mutant is nearly similar to that of bm1. These genes fell under several functional categories including phenylpropanoid metabolism, transport and trafficking, transcription factors and regulatory genes. As the bm2 mutant exhibited a lower guaiacyl (G) unit lignin content, the bm2 mutation could affect a regulatory gene involved, perhaps indirectly, in the regulation, conjugation or transport of coniferaldehyde, or the establishment of G-rich maize tissues. The pattern of gene expression in bm4 plants, characterized by the over-expression of phenylpropanoid and methylation genes, suggests that the bm4 mutation likely also affects a gene involved in the regulation of lignification.

Biosynthetic Pathways↗

[Differential expression of STRBP8, a new candidate oncogene, in cancerization of human immortalized esophageal epithelial cells].

BACKGROUND & OBJECTIVE: Recently, changes in composition, structure, and function of nuclear matrix proteins (NMPs) in generation and development of tumors evoked more and more attention. Separation and identification of tumor-related NMPs is a new way to search for tumor specific biomarkers, and to study tumor pathogenesis. This study was to analyze differential expression of STRBP8, one of esophageal carcinoma specific NMPs, in cancerization of immortalized human esophageal epithelial cells. METHODS: NMPs were extracted from immortalized human esophageal epithelial cell line SHEE and malignantly transformed esophageal carcinoma cell line SHEEC. Differential expression of STRBP8 was detected by two-dimensional electrophoresis (2-DE), matrix-assisted laser desorption/ionization time of flying mass spectrometry (MALDI-TOF-MS), and reverse transcription-polymerase chain reaction (RT-PCR). STRBP8 cDNA obtained by RT-PCR was linked to pGEM-T easy vector, and introduced into TOP10F' E.coli competent cells. Positive clones were sequenced and analyzed with BLAST. RESULTS: STRBP8 was only detected in SHEEC cells by 2-DE, MALDI-TOF-MS, and RT-PCR. The sequence of positive clones contained STRBP8 cDNA was identical to that in GenBank database. CONCLUSION: STRBP8, as a candidate oncogene, might relate to cancerization of esophageal epithelial cells, which might be a specific biomarker of esophageal carcinoma, and probe into the pathogenesis of esophageal carcinoma.

Base Sequence↗

Programmed cell death in procyclic Trypanosoma brucei rhodesiense is associated with differential expression of mRNAs.

Procyclic Trypanosoma brucei rhodesiense have a cell death mechanism which can be activated by an external signal, the lectin ConA, in vitro. ConA has been shown to cause profound changes in cellular morphology and induce fragmentation of nuclear DNA in T.b. rhodesiense which are characteristic of apoptosis, a form of programmed cell death (PCD) in other eukaryotic cells. RNA analysis of trypanosomes induced to undergo PCD revealed that RNA remains intact up to 48 h into the process, a time when nuclear DNA fragmentation has already started. Using the randomly amplified differentially expressed sequences polymerase chain reaction method, ConA-induced cell death in T.b. rhodesiense is shown to be associated with differential expression of mRNAs, including up regulation of mRNAs late in the death process. The results demonstrate that trypanosomes actively participate in their own destruction through a PCD process and confirm that cell death in trypanosomes is associated with de novo gene expression.

Journal Article↗

Differential expression profiling between the relative normal and dystrophic muscle tissues from the same LGMD patient.

BACKGROUND: Limb-girdle muscular dystrophy (LGMD) is a group of heterogeneous muscular disorders with autosomal dominant and recessive inheritance, in which the pelvic or shoulder girdle musculature is predominantly or primarily involved. Although analysis of the defective proteins has shed some light onto their functions implicated in the etiology of LGMD, our understanding of the molecular mechanisms underlying muscular dystrophy remains incomplete. METHODS: To give insight into the molecular mechanisms of AR-LGMD, we have examined the differentially expressed gene profiling between the relative normal and pathological skeletal muscles from the same AR-LGMD patient with the differential display RT-PCR approach. The research subjects came from a Chinese AR-LGMD family with three affected sisters. RESULTS: In this report, we have identified 31 known genes and 12 unknown ESTs, which were differentially expressed between the relative normal and dystrophic muscle from the same LGMD patient. The expression of many genes encoding structural proteins of skeletal muscle fibers (such as titin, myosin heavy and light chains, and nebulin) were dramatically down-regulated in dystrophic muscles compared to the relative normal muscles. The genes, reticulocalbin 1, kinectin 1, fatty acid desaturase 1, insulin-like growth factor binding protein 5 (IGFBP5), Nedd4 family interacting protein 1 (NDFIP1), SMARCA2 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 2), encoding the proteins involved in signal transduction and gene expression regulation were up-regulated in the dystrophic muscles. CONCLUSION: The functional analysis of these expression-altered genes in the pathogenesis of LGMD could provide additional information for understanding possible molecular mechanisms of LGMD development.

Journal Article↗

[Gene differential expression of liver tissues in crossbred versus purebred chicken and their relationship with heterosis of meat trait].

The concept of heterosis has already been put forward for a century. The hypothesis of Dominance, Superdominace and Epistasis has also been brought forward to explain the phenomenon of heterosis. As we know, there is spatio-temporal speciality about the expression of gene and only expressed genes contribute to the formation of heterosis. So the study on heterosis in expression level becomes more meaningful. A lot of studies on heterosis in this level have been done in plants, but there is no such study carried on animals in this area. In this study, the technique of mRNA Reverse Transcription Differential Display was used to research the heterosis molecular mechanism of animal. In order to expound the molecular genetic mechanism of animals heterosis, the 4 x 4 completely diallele cross experiment of 4 purebreds chicken was conducted among White Polymouth Rock (EE), Chinese Silk Chicken (CC), CAU Brown (DD) and White Leghorn (AA). The chicken of 16 cross combinations were reared to 8 weeks old, then 30 chicken in each combination were selected randomly and slaughtered. The traits of body weight of 8 weeks, wing weight, eviscerated weight, eviscerated weight with giblet, breast muscle yield, leg muscle yield, body length, abdomen fat weight, intramuscular fat width, tibia length were measured, and in which 8 individuals in each combination were selected randomly to collect the liver tissue samples, which were stored in liquid nitrogen or at -80 degrees C to be used for total RNA (TRNA) extracting. After the total RNA (TRNA) was extracted, 16 TRNA pools were formed in the same quantitative according to the concentration of 8 individual TRNA. They were reversely transcribed with three anchor primers H-T11 A, H-T11 G and H-T11 C. Then the reverse transcription PCR for each transcript product was done in two repeats at the same time with the same anchor primers and 8 random primers. The polyacrylamide gel electrophoresis of each PCR product was run in Bio-Rad Power 3,000 temperature control system. After electrophoresis, the gel was stained by AgNO3 according to the stain method described by Echt et al. The differential display bands in the polyacrylamide gel were counted. The band displayed is counted as 1 whereas no band is counted as 0 and only expression bands reproducible in two repeats were statistically analyzed. The correlation analysis between heterosis percentage and gene expression patterns was done with statistic analysis software (SAS) package. The statistic results indicated that among 690 total numbers of bands, the percentage of differential expression bands reproducible (457) is 66.23%. Eight kinds of gene differential expression patterns were found and listed as follow: 1): Band presents only in one purebred (P1);2): Band in one crossbred and its corresponding paternal purebred; or Band in one crossbred and its corresponding maternal purebred (P2);3): Band in purebreds and one crossbred (P3); 4): Band only in one crossbred (P4);5): Bands in both crossbreds and one purebred (P5);6): Bands only in both crossbreds (P6);7): Bands only in purebreds (P7);8): Bands both in purebreds and crossbreds P8. The differential expression of gene between purebred and crossbred chicken was detected for the first time. The proportion of each pattern in each kind of purebred combination is different. The percentage of P8 (75.34%) is the highest. The total percentage of differential expression patterns (24.66%) showed that the gene differential expression exists as a matter of fact. Among all the gene differential expression patterns, the percentage of P3 is the highest whereas the percentage of P7, P6 and P4 is very low, it indicated that different genes may have different expression patterns in purebreds and crossbreds. The results are similar to the study results on plants, which indicates that the gene differential expression between purebred and crossbred exists universally in biology. The correlation between gene expression patterns and heterosis percentage was studied, but correlation between P8 and the heterosis percentage is not significant (P > 0.05), it indicates that some patterns of gene differential expression may be the molecular genetic basic of heterosis. Among all the gene differential expression patterns, each pattern affects the expression of meat trait in different manner. There is significantly negative correlation between P4 and heterosis percentage of body weight of 8 weeks, breast muscle yield, leg muscle yield, eviscerated weight with giblet and eviscerated weight (P < 0.05); P1 is of significantly negative correlation with heterosis percentage of abdomen fat weight (P < 0.05) and of very significantly negative correlation with heterosis percentage of body length (P < 0.01); The negative correlation between P2 and heterosis percentage of intramuscular fat width is significant (P < 0.05); The positive correlation between P7 and heterosis percentage of leg muscle yield, wing weight, eviscerated weight with giblet and intramuscular fat width is significant (P < 0.05); The positive correlation between P5 and heterosis percentage of tibia length (P < 0.05) is significant. These results show that these 5 kinds of patterns play important role in heterosis forming of meat trait. P1 and P7 show that expressed gene in purebreds is depressed; P4 indicates that new gene expression occurs in crossbreds; P5 reveals that expressed gene only in one purebred express in all crossbreds. All genes of crossbreds come from purebred, which are not only the simple adding of these purebred genes, giving birth to unknown interaction between these genes coming from different purebreds, then leading to differential expression of genes. These gene differential expressions maybe form the heterosis of meat trait.

Animals↗