我々は先行研究において、日本短角種において稀少mtDNA ハプログループP を報告し、その起源は日本北部の在来牛に由来することを示唆した。本研究では、日本北部在来牛の影響を受けた可能性の高い品種について、ハプログループP の調査を目的とした。そこでmtDNA ハプログループP 個体検出を目的としたPCR-RFLP 法を開発し、日本北部のウシ品種388 個体（黒毛和種、日本ホルスタイン）に対して調査を行った。その結果、遺伝子頻度は低いものの、北海道のホルスタイン集団105 個体中2 個体（0.019）でハプログループP を検出した。この2 個体が有する2 つのハプロタイプは、日本短角種、韓牛、中国ホルスタインで報告されたハプログループP 個体と同一のものであり、共通の母系起源に由来することが示された。また、欧米の純粋品種ではハプログループP が報告されていないことや東北地方の歴史に関する記録を考慮すると、北海道のホルスタインで検出されたハプログループP が日本北部の在来牛に由来すること、また、これら日本北部在来牛と他の在来牛は異なる遺伝的背景を持つことが示唆された。

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In Myanmar, native cattle are mainly used for draught. Currently, the available genetic information about them is limited. In this study, complete mtDNA D-loop sequences were analyzed for genetic diversity and differentiation of four popular local breeds – Shwe Ni, Pyar Sein, Ngwar Pyar Ni and Shan Ngwar Pu – and the crossbred population (Holstein Friesian X Myanmar native cattle) among Myanmar’s cattle. From the complete D-loop sequences, 26 polymorphic sites and 27 haplotypes were obtained. All haplotypes (MYAH01 to 27) belonged to two zebu haplogroups of I1 and I2 by the NJ tree and MJ network. A MYAH10 haplotype was major (68%) and common in all breeds and population. Fifteen haplotypes were novel. The haplotype diversity and nucleotide diversity of the four local breeds and crossbred population ranged from 0.193 in Shan Ngwar Pu to 0.832 in the crossbred, and from 0.00051 in Shan Ngwar Pu to 0.00334 in crossbred, respectively. Genetic differentiation among the breeds and population was quite low in the D-loop of Myanmar cattle because the genetic variation among populations (1.4%) was not significant in AMOVA. However, Shan Ngwar Pu was significantly different from other breeds, according to the pairwise FST values. These results provided the genetic diversity and relationship in the popular local breeds and crossbred population of the Myanmar cattle.

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This study investigated the mechanism of melanin pigmentation in muscle and internal organs of adult Silky fowl and Rhode Island Red × White Plymouth Rock F1 broiler chickens, and the expression of three genes related to melanin pigment synthesis was examined. RT-PCR of tyrosinase (TYR) and two enzymes called tyrosinase-related proteins, dihydroxy indolcarboxylic acid oxidase (tyrosinase related protein 1; TYRP1) and DOPAchrome tautomerase (tyrosinase related protein 2; TYRP2) was performed for colon, cerebrum, middle kidney, heart, and shallow pectoral muscle tissues. Silky fowl expresses TYR, TYRP1, and TYRP2 in most organs, which suggests that melanin pigment was synthesized in most organs in Silky fowl. TYR was expressed in the cerebrum and heart even in the broilers without deposition of melanin pigment. TYRP1 and TYRP2 were also expressed in some organs in broilers. Therefore, these genes may play a role other than melanin pigment synthesis in chickens.

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