Pathways involved in pony body size development.

BACKGROUND: The mechanism of body growth in mammals is poorly understood. Here, we investigated the regulatory networks involved in body growth through transcriptomic analysis of pituitary and epiphyseal tissues of smaller sized Debao ponies and Mongolian horses at the juvenile and adult stages. RESULTS: We found that growth hormone receptor (GHR) was expressed at low levels in long bones, although growth hormone (GH) was highly expressed in Debao ponies compared with Mongolian horses. Moreover, significant downregulated of the GHR pathway components m-RAS and ATF3 was found in juvenile ponies, which slowed the proliferation of bone osteocytes. However, WNT2 and PLCß2 were obviously upregulated in juvenile Debao ponies, which led to premature mineralization of the bone extracellular matrix. Furthermore, we found that the WNT/Ca2+ pathway may be responsible for regulating body growth. GHR was demonstrated by q-PCR and Western blot analyses to be expressed at low levels in long bones of Debao ponies. Treatment with WNT antagonistI decreased the expression of WNT pathway components (P < 0.05) in vitro. Transduction of ATDC5 cells with a GHR-RNAi lentiviral vector decreased the expression of the GHR pathway components (P < 0.05). Additionally, the expression of the IGF-1 gene in the liver was lower in Debao ponies than in Mongolian horses at the juvenile and adult stages. Detection of plasma hormone concentrations showed that Debao ponies expressed higher levels of IGF-1 as juveniles and higher levels of GH as adults than Mongolian horses, indicating that the hormone regulation in Debao ponies differs from that in Mongolian horses. CONCLUSION: Our work provides insights into the genetic regulation of short stature growth in mammals and can provide useful information for the development of therapeutic strategies for small size.

[Review on the genomic imprinting at the mammalian DLK1-DIO3 cluster.].

The mammalian imprinting domain DLK1-DIO3 is located on distal human chromosome 14, mouse chromosome 12 and sheep chromosome 18. This cluster contains three imprinted protein-coding genes (Dlk1, Rtl1, and Dio3), which were expressed from the paternally inherited chromosome and several imprinted noncoding RNA genes expressed from the maternally inherited allele, such as miRNAs, snoRNAs, and large noncoding RNA Gtl2. The altered gene dosage of DLK1-DIO3 cluster resulted in several severe abnormal phenotypes in human and mouse, even death, suggesting the importance of these genes for normal development. This review focuses on the function of imprinted genes on this domain and the mechanism of their imprinting regulation.

Isolation and identification of bovine nasopharyngeal mucosal epithelial cells and establishment of cell models of acute infection by foot-and-mouth disease virus.

Foot-and-mouth disease (FMD) commonly occurs via the respiratory tract, and bovine nasopharyngeal mucosal epithelial cells are the primary infection cells in cattle. The aim of the present study was to isolate and culture epithelial cells from the bovine nasopharyngeal mucosa in vitro using a mechanical separation method. The cells were expanded, established in continuous cell culture, and used for immunofluorescence cytochemistry and establishment of infection models. We detected pan-cytokeratin markers of bovine nasopharyngeal mucosal epithelial cells by immunofluorescence. Bovine nasopharyngeal mucosal epithelial cells were then infected with foot-and-mouth disease virus (FMDV) serum type O. RT-PCR demonstrated the successful establishment of acute FMDV infection in the cell models. This infection model provides the basis for clarification of the interaction between FMDV and host bovine nasopharyngeal mucosal epithelial cells in vitro.

[Genomic characterization of SARS coronavirus: a novel member of coronavirus].

In March 2003, SARS-CoV, a novel coronavirus which has been proved to be a pathogen causing Severe Acute Respiratory Syndrome (SARS). The complete genome of SARS-CoV has been sequenced by international collaboration including China. In the present study, the genome sequences were collected from NCBI and genomic characterization was analyzed. SARS-CoV has a genome of 28-30 kb including 11 ORFs (Open Reading Frames), which is consistent with that of coronavirus family, and its genome organization is similar to those of other coronaviruses as well. SARS-CoV evolutionally closes to other coronavirus in their corresponding proteins, such as spike protein, small membrane protein and nucleocapsid protein. In some regions of the genome, the genomic sequence of SARS-CoV was significantly different from that of other coronavirus, and has a self-conservative genomic sequence. Moreover, its encoding protein sequences were greatly different from those of other coronavirus. The analysis indicated that SARS-CoV has lower redundancy, that is, it has a high variation possibility. It may not be a variant of other coronaviruses but a novel coronavirus, which existed independently in nature and was not recognized by human being before, although SARS-CoV is morphologically similar to other coronavirus and belongs to coronavirus family. The sequences of its genes and encoding proteins are substantially different from those of other coronavirus.

[Cloning and analysis of six full-length cDNA similar to sheep KAP6-1 from cashmere goat].

Cashmere is the fiber of kings, produced from the cashmere goat (Capra hircus). Cashmere fabric has little squama. Due to its lightness cashmere feels smooth and silky. An intriguing feature of cashmere structure is multiplicity of the hair keratin proteins with distinctive amino acid compositions. To study the role and regulation of one of these keratins, we used the SMART ( switching mechanism at 5' end of RNA transcript) technology to construct a cDNA library of skin tissue from an Inner Mongolia male cashmere goat. A total of 636 cDNA sequences were obtained by randomly sequenced from 5' of cDNA library. Sequence comparison with the GenBank database confirmed that there are 41 sequences showed high nucleotide sequence identity in the coding region with sheep keratin associated protein 6-1 (KAP6-1). They represent six different cDNAs (The accession numbers in GenBenk are AY310749, AY310750, AY310751, AY310752, AY310753 and AY310754, respectively). They are full-length cDNAs according to the known KAP6-1 genomic gene sequences of sheep. From the nucleotide sequences the open reading frames were identified, that encoded six basic proteins of 82, 84, 71, 71, 83, 83 amino acids, respectively, with a combined glycine and tyrosine content of about 60%. Compared analysis showed that the KAPs from goats shared more than 55.4% identities in nucleotide sequences and more than 79.8% identities in amino acid sequences with each other, and shared highest identities (81.9% approximately 98.8%) with KAP6-1 from sheep. The KAP6s from different animal species shared more than 50% identities in amino acid sequences with each other.

Isolation, culture, and characterization of primordial germ cells in Mongolian sheep.

This study was performed to culture and preliminarily identify the primordial germ cells (PGCs) isolated from the genital ridge of the Mongolian sheep fetus. The growth characteristics of the sheep PGCs were detected in different culture systems such as culture media, resources, and state and passages of feeder cells. The obtained embryonic germ (EG) cells were identified by morphology, enzymology, and immunofluorescence. The results showed that the sheep EG cell colonies were ridgy, typically nest like, and compact, and had regular edges. Alkaline phosphatase staining reaction was weakly positive. EG cells expressed Kit, Rex-1, Nanog, and Oct-4. Immunofluorescence detection was weakly positive for Oct3/4, whereas positive for SSEA-1, SSEA-3, SSEA-4, TRA-1-61, and TRA-1-80.