Del Cacho E, Gallego M, Pages M, Monteagudo L, Sánchez-Acedo C
Department of Animal Pathology, Faculty of Veterinary Sciences, Miguel Servet 177, University of Zaragoza, 50013 Zaragoza, Spain.
Int J Parasitol. 2006 Dec;36(14):1515-20. doi: 10.1016/j.ijpara.2006.08.004. Epub 2006 Sep 12.
The present report concerns our attempts to further study the effect of quinolone coccidiostats on the sporulation of Eimeria tenella oocysts by analyzing the meiotic behaviour of the chromosomes. To that end, synaptonemal complexes were analyzed by TEM applied to intact meiotic chromosomes. These were isolated after disruption of oocysts, which were harvested from decoquinate-medicated and non-medicated (control) birds. In oocysts from control birds, synaptonemal complexes appeared as the 14 bivalents of the normal karyotype. However, in oocysts from medicated birds, our synaptonemal complex analysis revealed a reciprocal translocation, which was observed as an irregular pairing of chromosome axes 5 and 12 resulting in quadrivalent and trivalent configurations. This finding suggests breakage points in chromosomes 5 and 12 and exchange of chromosomal segments. Furthermore, breakpoints in chromosome 12 resulted in telomere deletion. The chromosomal aberrations described in the present study may result in reduced sporulation since chromosomes involved in translocations segregate abnormally during meiosis. In addition, the results reported provide new evidence of the inhibitory effect of quinolones on the sporulation of E. tenella oocysts, since sporocysts were not formed.
本报告涉及我们通过分析染色体减数分裂行为进一步研究喹诺酮类抗球虫药对柔嫩艾美耳球虫卵囊孢子化影响的尝试。为此，通过透射电镜对完整减数分裂染色体上的联会复合体进行分析。这些染色体是在卵囊破裂后分离得到的，卵囊取自服用地克珠利药物和未服用药物（对照）的鸡。在对照鸡的卵囊中，联会复合体呈现为正常核型的14个二价体。然而，在用药鸡的卵囊中，我们对联会复合体的分析揭示了一种相互易位，表现为染色体轴5和12的不规则配对，导致四价体和三价体构型。这一发现表明染色体5和12上存在断裂点以及染色体片段的交换。此外，染色体12上的断裂点导致端粒缺失。本研究中描述的染色体畸变可能会导致孢子化减少，因为参与易位的染色体在减数分裂过程中会异常分离。此外，所报道的结果为喹诺酮类药物对柔嫩艾美耳球虫卵囊孢子化的抑制作用提供了新的证据，因为未形成孢子囊。
