Gunn S J, Hilburn L R
University of Texas-Pan American, Department of Biology, Edinburg 78539-2999.
J Parasitol. 1995 Feb;81(1):25-9.
The karyotypes of 5 species of Amblyomma ticks found in North America were examined for the presence and location of constitutive heterochromatin (C-bands). All specimens examined had 20 autosomes and an XX:XO sex-determining system, with the X being the largest element in the karyotype. Except as noted in text, the autosomes of all species were acrocentric and heterochromatin was restricted to the centromeric region. The third largest autosome in 4 of the 5 species displayed a consistent band of heterochromatin just below the centromere; Amblyomma imitator displayed heterochromatin on the third largest pair of autosomes but in the form of an entire heterochromatic short arm. It is hypothesized that the third largest autosome could be the location of the nucleolar organizer region. Unique features of the C-banded karyotype that characterize and differentiate each species are presented. Similarity in the C-banding pattern exists between Amblyomma americanum and Amblyomma maculatum (the C-band in the X chromosome) and Amblyomma cajennense and A. imitator (the extreme subacrocentric X chromosome). The placement of Amblyomma inornatum remains difficult and cannot be clearly determined based on the placement of heterochromatin.
对在北美发现的5种钝缘蜱的核型进行了检查，以确定组成型异染色质（C带）的存在和位置。所有检查的标本都有20条常染色体和XX:XO性别决定系统，其中X是核型中最大的染色体。除文中另有说明外，所有物种的常染色体均为近端着丝粒染色体，异染色质仅限于着丝粒区域。5种中的4种的第三大常染色体在着丝粒下方显示出一条一致的异染色质带；拟钝缘蜱在第三大对常染色体上显示异染色质，但呈整个异染色质短臂的形式。据推测，第三大常染色体可能是核仁组织区的位置。本文展示了C带核型的独特特征，这些特征可用于表征和区分每个物种。美洲钝缘蜱和黄斑钝缘蜱（X染色体中的C带）以及卡延钝缘蜱和拟钝缘蜱（极端近端部着丝粒X染色体）之间存在C带模式的相似性。无饰钝缘蜱的位置仍然难以确定，无法根据异染色质的位置明确判断。
