Molecular analysis and chromosomal assignment of the canine CALC-I/alpha-CGRP gene

Canine cryptorchidism: An update

This review article is aimed at providing an update on canine cryptorchidism based on the research studies published in this area over the last 26 years. Although a majority of these research studies were directed at investigating the genetic and molecular basis of cryptorchidism, the mechanisms underlying this problem in dogs are still not clear. Future studies using advanced genomic and molecular approaches and including a larger number of dogs of multiple breeds are required to further our understanding of canine cryptorchidism. Diagnosis and treatment of cryptorchidism in dogs have not received much attention. Research advancements include investigation of ultrasonography and anti-Müllerian hormone assay as potential diagnostic methods. Advancements in treatment include the use of laparoscopic-assisted cryptorchidectomy. Based on the available literature, this method appears to be the best for removal of abdominal cryptorchid testes from dogs. However, future studies that compare laparoscopic-assisted cryptorchidectomy with the traditional approaches are required for a more conclusive determination of the best method for cryptorchidectomy in dogs.

Analysis of single nucleotide polymorphisms in the 3' region of the estrogen receptor 1 gene in normal and cryptorchid Miniature Dachshunds and Chihuahuas

This study was performed to examine the distribution of single nucleotide polymorphisms (SNPs) and estimated haplotypes in the canine estrogen receptor (ER) alpha gene (ESR1) and the association of them with different phenotypes of cryptorchidism (CO) in Miniature Dachshunds and Chihuahuas. Forty CO and 68 normal dogs were used, and CO was classified into unilateral (UCO; n=33) and bilateral CO (BCO; n=5) or into abdominal (ACO; n=16) and inguinal CO (ICO; n=22). Thirteen DNA fragments located in the 70-kb region at the 3' end of ESR1 were amplified by PCR and sequenced to examine 13 SNPs (#1-#13) reported in a canine SNP database. Ten SNPs (#1-#4, #7, #8, #10-#13) were not polymorphic, and 5 new SNPs (#14-#18) were discovered. A common haplotype block in normal, CO and CO phenotypes was identified for an approximately 20-kb region encompassing 4 SNPs (#14-#17). Allele, genotype and haplotype frequencies in CO without classification by phenotype and also in UCO, ACO and ICO phenotypes were not statistically different from the normal group. Significant differences in genotype frequencies and homozygosity for the estimated GTTG haplotype within the block were observed in BCO compared with the normal group, although the number of BCO animals was small. Our results demonstrate that the examined SNPs and haplotypes in the 3' end of canine ESR1 are not associated with unilateral, abdominal and inguinal CO phenotypes and CO per se in Miniature Dachshunds and Chihuahuas. Further studies are necessary to suggest a clear association between the ESR1 SNPs and bilateral CO in dogs.

Genomic and expression analysis of canine calcitonin receptor-stimulating peptides and calcitonin/calcitonin gene-related peptide

Calcitonin receptor-stimulating peptides (CRSPs) are new members of the calcitonin/calcitonin gene-related peptide (CT/CGRP) family identified in pigs, dogs and other domestic animals, and CRSP-1 is an active ligand for the CT receptor (CT-R). We recently sequenced porcine CRSP genes (Crsps) and found similarity with the CT/CGRP gene (Ct/Cgrp) in sequence and genomic organization. In this study, we identified five Crsps, Crsp-1 to Crsp-5, in dogs. Crsp-1 has five exons with an exon-intron organization identical to that of porcine Crsp-1 or Crsp-2, while Crsp-2 and Crsp-3 have additional CT-2- and CT-3-coding exons like Ct/Cgrp. Crsp-2 was renamed as Ct-2/Crsp-2 because both CRSP-2 and CT-2 mRNAs were tissue-specifically expressed. Crsp-4 and Crsp-5 are presumably generated by retrotransposition. We postulate that Crsps were generated from the gene duplication of Ct/Cgrp, and gained their diversity during mammalian evolution. Among the canine CTs and CRSPs, CRSP-1, CT-1 and CT-2 are active ligands for the CT-R, but CRSP-2 and others are inactive. Canine CRSP-1 and CT-2 are expressed in the central and peripheral systems, while CT-1 is localized in the thyroid gland. These findings indicate that dogs can be used for an experimental model as analysing the physiological roles of the CT/CGRP/CRSP family.