Fort Douglas J, Rogers Robert L, McLaughlin Daniel W, Sellers Chris M, Schlekat Christian L
Fort Environmental Laboratories, Stillwater, OK 74074, USA.
Biol Trace Elem Res. 2002 Winter;90(1-3):117-42. doi: 10.1385/BTER:90:1-3:117.
The toxicity of boron has been understood for many years. However, limited data currently exist concerning the nutritional essentiality of B in chordates. Results from an ongoing research program evaluating the nutritional essentiality of B in the South African clawed frog, Xenopus laevis, found that X. laevis fed a low-B diet in a low-B culture media produced a substantially higher number of necrotic eggs and fertilized embryos than frogs fed a boron-sufficient diet. Markedly decreased embryo cell counts at mid-blastula transition and an increased frequency of abnormal gastrulation were also noted in embryos from adult frogs fed the B-deficient diet. By 96 h of development, none of the larvae collected from the B-deficient adults and maintained in low-boron culture media developed normally. Reproductive effects associated with B deficiency in female Xenopus included ovary atrophy, oocyte necrosis, and incomplete oocyte maturation. In males, a decrease in testis weight and sperm count was noted. These studies suggest that these adverse effects resulting from B deficiency could be found during gametogenesis, gamete maturation, embryonic development, and larval maturation. The studies also confirmed that B deficiency was capable of interrupting the X. laevis life cycle. Additional studies evaluating the role of B in the thyroid axis and the oocyte plasma membrane progesterone receptor provide the first line of direct evidence for a biochemical role of boron in X. laevis. Combined together, this research program provides firm evidence that B is nutritionally essential in X. laevis.
硼的毒性已被了解多年。然而，目前关于硼在脊索动物中营养必需性的数据有限。一项正在进行的评估南非爪蟾（非洲爪蟾）体内硼营养必需性的研究项目结果表明，在低硼培养基中喂食低硼饮食的非洲爪蟾所产生的坏死卵和受精卵胚胎数量，比喂食硼充足饮食的青蛙要多得多。在喂食缺硼饮食的成年青蛙的胚胎中，还观察到囊胚中期过渡时胚胎细胞数量显著减少，以及原肠胚形成异常的频率增加。到发育96小时时，从缺硼成年青蛙收集并饲养在低硼培养基中的幼体均未正常发育。雌性非洲爪蟾缺硼相关的生殖影响包括卵巢萎缩、卵母细胞坏死和卵母细胞成熟不完全。在雄性中，观察到睾丸重量和精子数量减少。这些研究表明，缺硼导致的这些不良反应可能在配子发生、配子成熟、胚胎发育和幼体成熟过程中出现。这些研究还证实，缺硼能够中断非洲爪蟾的生命周期。另外一些评估硼在甲状腺轴和卵母细胞质膜孕酮受体中作用的研究，为硼在非洲爪蟾中的生化作用提供了直接的首要证据。综合起来，该研究项目提供了确凿证据，证明硼在非洲爪蟾中具有营养必需性。
