Godfrey Earl W, Sanders George E
Department of Pathology and Anatomy, Eastern Virginia Medical School, P.O. Box 1980, Norfolk, Virginia 23501, USA.
Comp Med. 2004 Apr;54(2):170-5.
Husbandry and health of the African clawed frog, Xenopus laevis, greatly influences the quality of oocytes produced. One factor affecting oocyte quality is the water conditions in which females are maintained. Dechlorination and adequate salt concentration are known to affect oocytes, but water hardness has not been considered an important factor in Xenopus husbandry by the research community. We found that, when females were kept in soft water or water with marine salts alone, even when it was cooled to 17 to 18 degrees C, the quality of oocytes decreased; only 20 to 25% of resulting embryos developed to tailbud stages. Survival and normal development of embryos increased significantly within one month of addition to the laboratory housing water of salts that mimic conditions in African Rift Valley lakes. These salts greatly increased water hardness; development of embryos to tailbud stages remained high (50 to 70% on average) for more than a year after their addition to the water housing females. Water from South African ponds where X. laevis are collected, and from wells used by the major suppliers of X. laevis, also was moderately to very hard. Our results suggest that X. laevis is naturally adapted to hard water, and indicate that increasing general hardness during laboratory housing is more important for oocyte quality and embryo development than is increasing carbonate hardness (alkalinity) in the water used to house females.
非洲爪蟾（非洲爪蟾，光滑爪蟾）的饲养与健康状况对所产卵母细胞的质量有很大影响。影响卵母细胞质量的一个因素是雌性爪蟾所处的水质条件。已知脱氯和适当的盐浓度会影响卵母细胞，但水硬度尚未被研究界视为非洲爪蟾饲养中的重要因素。我们发现，当雌性爪蟾饲养在软水或仅含海盐的水中时，即使水温冷却至17至18摄氏度，卵母细胞质量仍会下降；只有20%至25%的胚胎发育到尾芽期。在实验室饲养用水中添加模拟非洲裂谷湖条件的盐后一个月内，胚胎的存活率和正常发育显著提高。这些盐大大增加了水硬度；在向饲养雌性爪蟾的水中添加这些盐一年多后，胚胎发育到尾芽期的比例仍保持在较高水平（平均为50%至70%）。从南非采集光滑爪蟾的池塘以及光滑爪蟾主要供应商使用的水井中获取的水，硬度也为中度至非常硬。我们的研究结果表明，光滑爪蟾自然适应硬水，并表明在实验室饲养期间提高总硬度对卵母细胞质量和胚胎发育比提高用于饲养雌性爪蟾的水中的碳酸盐硬度（碱度）更为重要。
