In the late stages of the global dispersal of dogs, dingoes appear in the Australian archaeological record 3500 years BP, and dogs were one of three domesticates brought with the colonization of Polynesia, but the introduction routes to this region remain unknown. This also relates to questions about human history, such as to what extent the Polynesian culture was introduced with the Austronesian expansion from Taiwan or adopted en route, and whether pre-Neolithic Australia was culturally influenced by the surrounding Neolithic world. We investigate these questions by mapping the distribution of the mtDNA founder haplotypes for dingoes (A29) and ancient Polynesian dogs (Arc1 and Arc2) in samples across Southern East Asia (n = 424) and Island Southeast Asia (n = 219). All three haplotypes were found in South China, Mainland Southeast Asia and Indonesia but absent in Taiwan and the Philippines, and the mtDNA diversity among dingoes indicates an introduction to Australia 4600–18 300 years BP. These results suggest that Australian dingoes and Polynesian dogs originate from dogs introduced to Indonesia via Mainland Southeast Asia before the Neolithic, and not from Taiwan together with the Austronesian expansion. This underscores the complex origins of Polynesian culture and the isolation from Neolithic influence of the pre-Neolithic Australian culture.

Expression and localization of mRNAs for vascular endothelial growth factor (VEGF), VEGF receptor 1 (Flt) and VEGF receptor 2 (KDR) (VEGFR-1 and VEGFR-2, respectively) were investigated in pig corpora lutea. Northern blot analysis of total RNA indicated hybridization of pig VEGF, VEGFR-1 and VEGFR-2 cDNA probes to mRNA transcripts of approximately 3.9, 7.0 and 5.0 kb, respectively. The expression of mRNAs for VEGF and its receptors during the luteal phase (days 4, 7, 10, 13 and 15 after the onset of oestrus) were assessed by northern blot analysis, and hybridization signals were normalized to expression of pig 18S rRNA. Relative hybridization signals of expression of VEGF mRNA appeared to be constant; however, expression of VEGFR-1 mRNA was low on day 4, increased on day 7, and was higher on days 10, 13 and 15 (P<0.05, compared with day 4). In contrast, no changes in expression of mRNA for VEGFR-2 were evident on days 4-13, but a decrease was detected (P<0.05) at day 15. In situ hybridization revealed that VEGF mRNA was localized predominantly in large luteal cells, whereas both VEGFR-1 and VEGFR-2 were localized to small cells. These data indicate that the VEGF system may be involved in the regulation of luteal vasculature throughout the lifespan of the corpus luteum. Although the expression of VEGF mRNA was unchanged during the luteal phase, variations in the expression of VEGFR-1 and VEGFR-2 mRNAs indicate that differential regulation of expression of the VEGF receptors may play a role in the control of VEGF-mediated vascular growth at different phases of development and maturation of the pig corpus luteum.

Changes in the expression and localization of luteal mRNA for PGF(2alpha) (FP) receptors may be critical in determining the luteolytic action of PGF(2alpha) in pig corpora lutea. In this study, a full-length FP receptor (FPr) cDNA was isolated and cloned from pig corpora lutea. This isolate (GenBank accession no. U91520) contains an open reading frame of 1086 bases coding for a protein of 362 amino acids with seven potential transmembrane domains. The predicted amino acid sequence of this isolate was 83% identical to the FPr amino acid sequence of other species including sheep, cattle and humans. Northern blot analysis showed the presence of an FPr message of about 5 kb in mRNA from pig corpora lutea. Relatively weak FPr mRNA expression was detected on day 4 and day 7 of the oestrous cycle. The expression was greater (P < 0.05) on days 10, 13 and 15 than on days 4 and 7. In situ hybridization analysis revealed that mRNA for FPr was expressed predominantly in the steroidogenic large luteal subtype of cell, although there was some expression in small luteal cells, with histological appearance of steroidogenic small cells. Localization of hybridization signals of FPr was observed in luteal tissue at all stages examined. These data demonstrate that FPr is expressed in pig corpora lutea throughout the oestrous cycle and that upregulation of the FPr mRNA occurs when the corpora lutea becomes sensitive to PGF(2alpha). Direct luteal targets of PGF(2alpha) appear to be primarily large steroidogenic cells in this species.

We determined whether a single injection of slow-release estradiol-17beta (SRE2) would induce pseudopregnancy in gilts and whether PGF2alpha would regress the corpora lutea (CL) of pseudopregnancy. Crossbred gilts (n = 40) were induced to ovulate by treatment with 400 IU of hCG + 200 IU of eCG (PG600, Intervet, Millsboro, DE) given at 180 d of age (d = 0). On d 14, gilts were injected i.m. with one of five doses (n = 8 gilts/dose) of SRE2 (0, 12.5, 25, 50, or 100 mg). Blood samples were collected before SRE2 and twice weekly until d 73 to monitor serum progesterone (P4) and estradiol (E2). On d 59, gilts received (i.m.) 10 mg of PGF2alpha (Lutalyse, Pharmacia Upjohn, Kalamazoo, MI) and were checked for estrus for 7 d. On d 62, mammary development was scored (0 = no development; 1 = some development; 2 = teat and gland development) by a neutral observer. Treatment with SRE2 increased (P < .05) peak E2 concentrations, duration of luteal function, and mammary gland score. There were no differences (chi-square, P > .05) among doses of SRE2 in the percentage of pseudopregnant gilts that showed luteolysis after PGF2alpha. We conclude that a single injection of SRE2 can induce pseudopregnancy and that the CL can be regressed with PGF2alpha, providing a simple method for controlling estrus in gilts.

The dog population of Southern East Asia is unique in harboring virtually the full range of the universal mtDNA gene pool, and consequently, it has the highest genetic diversity worldwide. Despite this, limited research has been performed on dog genetics within this region. Here we present the first comprehensive study of a sub-region within Southern East Asia, analyzing 528 bp of mtDNA for 265 dogs from Thailand, in the context of dogs from across the Old World. We found that Thailand was the only region in the world that has the full range of the universal mtDNA gene pool, that is, all 10 sub-haplogroups. Consequently, the statistics for diversity are among the highest, especially in North Thailand, which had high values for haplotype diversity and the number of haplotypes, and the lowest proportion of individuals with a universal type-derived haplotype (UTd) among all regions. As previously observed, genetic diversity is distinctly lower outside Southern East Asia and it decreases following a cline to the lowest values in western Eurasia. Thus, the limited geographical region of Thailand harbors a distinctly higher genetic diversity than much larger regions in western Eurasia, for example, Southwest Asia and Europe which have only five and four of the 10 sub-haplogroups, respectively. Within Thailand, diversity statistics for all four sub-regions follow the general pattern of Southern East Asia, but North Thailand stands out with its high diversity compared to the other regions. These results show that a small part of Southern East Asia harbors the full range of the mtDNA gene pool, and they emphasize the exceptional genetic status of Southern East Asia. This indicates that today’s dogs can trace a major part of their ancestry to Southern East Asia or closely situated regions, highlighting Thailand as a region of special interest. Considering the large genetic diversity found in Thailand and that many neighboring regions, e.g., Myanmar and Laos, have not been studied for dog genetics, it is possible that large parts of the dog gene pool remain undiscovered. It will be an important task for future studies to fill in these blanks on the phylogeographic map.