Baoliang Fan

Over-expression of the bovine FcRn in the mammary gland results in increased IgG levels in both milk and serum of transgenic mice

The neonatal Fc receptor (FcRn) protects immunoglobulin G (IgG) from catabolism and is also responsible for IgG absorption in the neonatal small intestine. However, whether it mediates the transfer of IgG from plasma to milk still remains speculative. In the present study, we have generated transgenic mice that over‐express the bovine FcRn (bFcRn) in their lactating mammary glands. Significantly increased IgG levels were observed in the sera and milk from transgenic animals, suggesting that the over‐expressed bFcRn could bind and protect endogenous mouse IgG and thus extend its lifespan. We also found that injected human IgG showed a significantly longer half‐life (7–8 days) in the transgenic mice than in controls (2·9 days). Altogether, the data suggested that bFcRn could bind both mouse and human IgG, showing a cross‐species FcRn–IgG binding activity. However, we found no selective accumulation of endogenous mouse IgG or injected bovine IgG in the milk of the transgenic females, supporting a previous hypothesis that IgG was transported from serum to milk in an inverse correlation to its binding affinity to FcRn.

Construct synthetic gene encoding artificial spider dragline silk protein and its expression in milk of transgenic mice.

Based on the known partial cDNA sequence of dragline silk protein an artificial gene monomer, a 360 bp sequence, was designed and polymerized to encode an analog of dragline silk protein. Six tandem copies of monomer were cloned into pBC1 vector and microinjected into the pronuclei of fertilized Kunming White eggs. Transgenic mice were screened by Polymerase Chain Reaction (PCR) and Southern blot which revealed that 10 mice (5 male, 5 female) among 58 mice were transgenic positive. Milk of five F0 mice and eight F1 mice was analyzed by Western blot, and two F0 mice and seven F1 mice expressed recombinant dragline silk protein. In transgenic mice milk a maximum of concentration of recombinant dragline silk protein was 11.7 mg/L by radioimmunoassay.

Production of transgenic blastocyst by nuclear transfer from different types of somatic cells in cattle

The present study examined the effects of genetic manipulation to the donor cell and different types of transgenic donor cells on developmental potential of bovine nuclear transfer (NT) embryos. Four types of bovine somatic cells, including granulosa cells, fetal fibroblasts, fetal oviduct epithelial cells and fetal ovary epithelial cells, were transfected with a plasmid (pCE-EGFP-Ires-Neo-dNdB) containing the enhanced green fluorescent protein (EGFP) and neomycin-resistant (Neor) genes by electroporation. After 14 days selection with 800 μg/mL G418, transgenic cell lines from each type of somatic cells were obtained. Nontransgenic granulosa cells and all 4 types of transgenic somatic cells were used as nuclear donor to produce transgenic embryos by NT. There was no significant difference in development rates to the blastocyst stage for NT embryos from transgenic and nontransgenic granulosa cells (44.6% and 42.8%, respectively), and transfer of NT embryos derived from transgenic and nontransgenic granulosa cells to recipients resulted in similar pregnancy rates on day 90 (19% and 25%, respectively). The development rates to the blastocyst stage of NT embryos were significantly different among different types of transgenic donor cells (P<0.05). Blastocyst rates from fetal oviduct epithelial cell and granulosa cell (49.1% and 44.6%, respectively) were higher than those from fetal fibroblast (32.7%) and fetal ovary epithelial cell (22.5%). These results suggest that (i) genetic manipulation to donor cells has no negative effect on in vitro and early in vivo developmental competence of bovine NT embryos and (ii) granulosa and fetal oviduct epithelial cells can be used to produce transgenic bovine NT embryos more efficiently. In addition, GFP can be used to select transgenic NT embryos as a non-invasive selective marker.

Maternally Derived Recombinant Human Anti-Hantavirus Monoclonal Antibodies Are Transferred to Mouse Offspring during Lactation and Neutralize Virus In Vitro

ABSTRACT Transgenic mice expressing a recombinant human monoclonal antibody (rHMAb) against hantavirus were generated. These mice could be used as models to explore the possibilities of producing rHMAbs for therapeutic purposes. The highest concentration of the rHMAb in the milk of the transgenic females was 6.6 mg/ml. The rHMAb was also detected in the sera of pups fed by the transgenic females. Both the rHMAbs in the milk of transgenic mice and those in the sera of suckling pups were found to be active against hantaviruses, although the light chain of the antibody absorbed by the pups was modified by N-linked glycosylation.

Comparative analysis of the pig BAC sequence involved in the regulation of myostatin gene

Myostatin (GDF8, MSTN) is a member of the transforming growth factor beta superfamily that is essential for proper regulation of skeletal muscle mass. In order to study its expression and regulatory mechanism deeply, we have presented a comparative analysis of about 170-kb pig BAC sequence containing the myostatin gene among pig, human and mouse. The genomic region is characterized by high interspersed repeats and low G+C content. As for the myostatin gene, a higher sequence similarity is found between human and pig than between these species and the mouse. One striking feature is that the structure of two TATA-boxes in the nearby downstream of CCAAT-box is identified in the promoter. Further analysis reveals that the TATA-box1 is responsible for the transcription in pig and human, but the TATA-box2 acts on the transcription in mouse. The other interesting feature is that two polyadenylation signal sequences (AATAAA) exist in 3’UTR of the pig myostatin gene. Moreover, a large number of potential transcription factor-binding sites are also identified in evolutionary conserved regions (ECRs), which may be associated with the regulation of myostatin. Many putative transcription factors play an important role in the muscle development, and the complex interaction between myostatin and these factors may be required for proper muscle development.

Differential Glycosylation of rhLf Expressed in the Mammary Gland of Transgenic Mice

Differential glycosylation of natural hLf and rhLf from hLf-transgenic mice, which harbored a 146 Kb BAC insert that includes the intact hLf gene sequence, was studied in the present report. There were significant differences between the immunoblotting results of rhLf and natural hLf, which were denatured with nonreducing SDS sample buffer. The differences disappeared after rhLf and natural hLf samples were digested with N-glycosidase F, respectively. The results showed that there were significant differences (P < 0.01) between the glycosylation of natural hLf and rhLf that were purified, respectively, from milk samples of seven hLf-transgenic mouse lines.

Cloning and sequencing of quail and pigeon prion genes.

ABSTRACT Quail and pigeon PrP genes were cloned and sequenced. Like mammalianPrP genes, quail and pigeon genes are encoded by a single exon of a single copy gene in the genome. All of the structural features of mammalian PrP genes were found in the quail and pigeon PrP gene. Compared with the nucleotide sequences of mammalian PrP, they display generally 30% similarity. When compared with chicken PrPs DNA sequence, they show a higher homology (90%), and an even higher homology (99%) when compared to each other. A phylogenetic tree was constructed to trace the evolution of the prion gene in animals.

Assembly and in vitro functional analysis of zinc finger nuclease specific to the 3' untranslated region of chicken ovalbumin gene.

Synthetic zinc finger nucleases (ZFNs) are useful for the improvement of site directed integration of foreign gene into vertebrate chromosomes. To facilitate site-directed integration of foreign genes into the 3′-untranslated region of the chicken ovalbumin gene, we have constructed ZFN expression vectors using Zinc Finger Consortium Vector Kits and tested the functionality of these ZFN constructs. Coding sequences for 6 zinc fingers were assembled following the modular assembly method. The zinc finger assembly was fused to two FokI catalytic domains. Various configurations of linker regions between domains were tested for their influence on enzymatic activity, using plasmid substrate containing the target sequence. Results indicated that ZFN with an elongated linker between two nuclease domains had a high catalytic activity.

Cloning, sequencing and phylogenic analysis of duck prion gene

Abstract Duck prion gene was cloned and sequenced. Similar to mammalian prion protein (PrP), duck prion is encoded by a single exon of a single copy in genome, which was confirmed by Southern blot analysis. All of the structural features of mammalian PrP were also identified in the duck PrP. Compared with mammalian PrP, it exhibited a 30% of general similarity. When compared with chicken PrP, it showed a higher homology of 97%. A phylogenetic tree was constructed to trace evolution of prion gene in animals.

Analysis of cDNA sequence, protein structure and expression of parotid secretory protein in pig

Parotid secretory protein (PSP) secreted abundantly in saliva, whose function is related with the anti-bacterial effect. ThePSP cDNA has been isolated from pig parotid glands by 3′ and 5′ rapid amplification of cDNA end (RACE), based on the conserved signal peptide region among the known mammalian PSP. The result of homologous comparison shows that pig PSP and human PSP shares the high identity at the level of the primary, secondary and tertiary protein structure. A search for functionally significant protein motifs revealed a unique amino acid sequence pattern consisting of the residues Leu-X(6)-Leu-X(6)-Leu-X(7)-Leu-X(6)-Leu-X(6)-Leu near the amino-terminal portion of the protein, which is important to its function. RT-PCR, Dot blot and Northern blot analysis demonstrated that PSP was strongly expressed in parotid glands, but not in other tissues.