Insight into the Fecal Microbiota Signature Associated with Growth Specificity in Korean Jindo Dogs Using 16S rRNA Sequencing.

Gut microbiomes are well recognized to serve a variety of roles in health and disease, even though their functions are not yet completely understood. Previous studies have demonstrated that the microbiomes of juvenile and adult dogs have significantly different compositions and characteristics. However, there is still a scarcity of basic microbiome research in dogs. In this study, we aimed to advance our understanding by confirming the difference in fecal microbiome between young and adult dogs by analyzing the feces of 4-month and 16-month-old Jindo dogs, a domestic Korean breed. Microbiome data were generated and examined for the two age groups using 16S rRNA analysis. Comparison results revealed that the 16-month-old group presented a relatively high distribution of Bacteroides, whereas the 4-month-old group presented a comparatively high distribution of the Lactobacillus genus. Microbial function prediction analyses confirmed the relative abundance of lipid metabolism in 4-month-old dogs. In 16-month-old dogs, glucose metabolism was determined using microbial function prediction analyses. This implies that the functional microbiome changes similarly to the latter in adults compared with childhood. Overall, we discovered compositional and functional variations between genes of the gut microbial population in juveniles and adults. These microbial community profiles can be used as references for future research on the microbiome associated with health and development in the canine population.

Insight into the Candidate Genes and Enriched Pathways Associated with Height, Length, Length to Height Ratio and Body-Weight of Korean Indigenous Breed, Jindo Dog Using Gene Set Enrichment-Based GWAS Analysis.

As a companion and hunting dog, height, length, length to height ratio (LHR) and body-weight are the vital economic traits for Jindo dog. Human selection and targeted breeding have produced an extraordinary diversity in these traits. Therefore, the identification of causative markers, genes and pathways that help us to understand the genetic basis of this variability is essential for their selection purposes. Here, we performed a genome-wide association study (GWAS) combined with enrichment analysis on 757 dogs using 118,879 SNPs. The genomic heritability (h2) was 0.33 for height and 0.28 for weight trait in Jindo. At p-value < 5 × 10-5, ten, six, thirteen and eleven SNPs on different chromosomes were significantly associated with height, length, LHR and body-weight traits, respectively. Based on our results, HHIP, LCORL and NCAPG for height, IGFI and FGFR3 for length, DLK1 and EFEMP1 for LHR and PTPN2, IGFI and RASAL2 for weight can be the potential candidate genes because of the significant SNPs located in their intronic or upstream regions. The gene-set enrichment analysis highlighted here nine and seven overlapping significant (p < 0.05) gene ontology (GO) terms and pathways among traits. Interestingly, the highlighted pathways were related to hormone synthesis, secretion and signalling were generally involved in the metabolism, growth and development process. Our data provide an insight into the significant genes and pathways if verified further, which will have a significant effect on the breeding of the Jindo dog's population.

Genome-wide analysis of the diversity and ancestry of Korean dogs.

There are various hypotheses on dog domestication based on archeological and genetic studies. Although many studies have been conducted on the origin of dogs, the existing literature about the ancestry, diversity, and population structure of Korean dogs is sparse. Therefore, this study is focused on the origin, diversity and population structure of Korean dogs. The study sample comprised four major categories, including non-dogs (coyotes and wolves), ancient, modern and Korean dogs. Selected samples were genotyped using an Illumina CanineHD array containing 173,662 single nucleotide polymorphisms. The genome-wide data were filtered using quality control parameters in PLINK 1.9. Only autosomal chromosomes were used for further analysis. The negative off-diagonal variance of the genetic relationship matrix analysis depicted, the variability of samples in each population. FIS (inbreeding rate within a population) values indicated, a low level of inbreeding within populations, and the patterns were in concordance with the results of Nei's genetic distance analysis. The lowest FST (inbreeding rate between populations) values among Korean and Chinese breeds, using a phylogenetic tree, multi-dimensional scaling, and a TreeMix likelihood tree showed Korean breeds are highly related to Chinese breeds. The Korean breeds possessed a unique and large diversity of admixtures compared with other breeds. The highest and lowest effective population sizes were observed in Korean Jindo Black (485) and Korean Donggyeong White (109), respectively. The historical effective population size of all Korean dogs showed declining trend from the past to present. It is important to take immediate action to protect the Korean dog population while conserving their diversity. Furthermore, this study suggests that Korean dogs have unique diversity and are one of the basal lineages of East Asian dogs, originating from China.

Functional analysis of expressed sequence tags from the liver and brain of Korean Jindo dogs.

We generated 16,993 expressed sequence tags (ESTs) from two libraries containing full-length cDNAs from the brain and liver of the Korean Jindo dog. An additional 365,909 ESTs from other dog breeds were identified from the NCBI dbEST database, and all ESTs were clustered into 28,514 consensus sequences using StackPack. We selected the 7,305 consensus sequences that could be assembled from at least five ESTs and estimated that 12,533 high-quality single nucleotide polymorphisms (SNPs) were present in 97,835 putative SNPs from the 7,305 consensus sequences. We identified 58 Jindo dog-specific SNPs in comparison to other breeds and predicted seven synonymous SNPs and ten non-synonymous SNPs. Using PolyPhen, a program that predicts changes in protein structure and potential effects on protein function caused by amino acid substitutions, three of the non-synonymous SNPs were predicted to result in changes in protein function for proteins expressed by three different genes (TUSC3, ITIH2, and NAT2).

Behavioral reactivity of Jindo dogs socialized at an early age compared with non-socialized dogs.

The aim of this study was to determine whether socialized Jindo puppies would show different behavioral reactivity from non-socialized puppies. Puppies (n=12), 7 weeks of age, were divided into socialized and non-socialized groups. The socialized group from the 7th until 13th week after birth was provided a socialization program, and the non-socialized group was reared in a semi-isolated environment without being exposed to the program. At 13 weeks after birth, both groups were adopted by new families and raised as a family pet until adulthood. Both groups were tested in 5 behavioral tests at 7, 9, 11, 13 and 60 weeks of age, and their behavioral responses to the tests were recorded using video cameras. The contact, fearful and playful behaviors toward each behavioral test were scored on a scale of 1 to 5 points. Using all of the score data, a principal component analysis (PCA) extracted three primary factors: 'social reactivity towards humans and a dog', 'playful reactivity towards novel stimuli and a dog' and 'fearful reactivity towards social stimuli'. The three extracted factors were compared between the socialized and non-socialized groups in each test session (weeks). Based on the results, the socialized Jindo puppies in the test session at the 9th week after birth, in contrast to the non-socialized puppies, exhibited a higher intensity of playful reactivity towards novel stimuli and a dog. However, there were no effects of the socialization program on the Jindo puppies in terms of social reactivity towards humans and a dog as well as fearful reactivity towards social stimuli.