Shaw N M, Harding R W
Smithsonian Environmental Research Center, Smithsonian Institution, Rockville, Maryland 20852-1773.
Plant Physiol. 1987 Feb;83(2):377-83. doi: 10.1104/pp.83.2.377.
Cyclic AMP and cyclic GMP were released into the growth medium of mycelia of Neurospora crassa wild-type strains St.L.74A and Em5297a and by white collar-1 and white collar-2 mutant strains. After growth for 6 days at 18 degrees C, there were 2.19 (St.L.74A), 5.83 (Em5297a), 1.38 (white collar-1), and 1.10 (white collar-2) nanomoles of cyclic AMP per gram dry weight of mycelia in the growth medium. These values corresponded to concentrations of cyclic AMP of between approximately 10 and 50 nanomolar. The corresponding values for extracellular cyclic GMP were typically less than 6% of the values for cyclic AMP. Following transfer to fresh medium, cyclic AMP efflux was demonstrated for each of the strains, and the amount of cyclic AMP exported into the fresh medium was greater at 25 degrees C than 6 degrees C. Intracellular cyclic AMP and cyclic GMP were also measured in each of the strains. The values for cyclic AMP were in the same range as those in the literature (approximately 0.5 to 1.5 nanomoles per gram dry weight of mycelia). However, the corresponding intracellular cyclic GMP values were less than 1% of the cyclic AMP values, i.e. more than 50 times lower than the value previously reported for the St.L.74A wild-type. Transfer of mycelia after 6 days at 18 degrees C to fresh media and incubation for 2 hours at 25 degrees C or 6 degrees C did not consistently affect the intracellular level of cyclic AMP or cyclic GMP in the strains examined. We could detect no change in intracellular cyclic AMP when mycelia of the St.L.74A wild-type strain were irradiated with blue light for periods of up to 3.0 hours at 18 degrees C, or in cyclic AMP and cyclic GMP for irradiation times of up to 1 minute at 6 degrees C. We propose that the plasma membrane of Neurospora crassa is permeable to cyclic nucleotides, and the export of cyclic nucleotides into the growth medium may be a means of regulating intracellular levels. We conclude that three factors that affect carotenogenesis in Neurospora crassa (blue light, temperature, and the white collar mutations) have no appreciable effect on the total measurable intracellular cyclic nucleotides in this organism. There was no extracellular or intracellular cyclic AMP or cyclic GMP in the crisp-1 mutant strain, which suggested either that adenylate cyclase (which is absent in crisp-1) catalyzes the synthesis of both cyclic AMP and cyclic GMP or that the crisp-1 mutation somehow results in a deficiency of two enzymes (adenylate and guanylate cyclase).
环磷酸腺苷（cAMP）和环磷酸鸟苷（cGMP）被释放到粗糙脉孢菌野生型菌株St.L.74A和Em5297a以及白领-1和白领-2突变菌株的菌丝体生长培养基中。在18摄氏度下生长6天后，生长培养基中每克干重菌丝体所含的环磷酸腺苷分别为2.19纳摩尔（St.L.74A）、5.83纳摩尔（Em5297a）、1.38纳摩尔（白领-1）和1.10纳摩尔（白领-2）。这些数值对应的环磷酸腺苷浓度约在10至50纳摩尔之间。细胞外环磷酸鸟苷的相应数值通常不到环磷酸腺苷数值的6%。转移至新鲜培养基后，各菌株均表现出环磷酸腺苷的外流，并且在25摄氏度时环磷酸腺苷分泌到新鲜培养基中的量要多于6摄氏度时。我们还测定了各菌株细胞内环磷酸腺苷和环磷酸鸟苷的含量。环磷酸腺苷的数值与文献报道范围相同（每克干重菌丝体约0.5至1.5纳摩尔）。然而，相应的细胞内环磷酸鸟苷数值不到环磷酸腺苷数值的1%，即比之前报道的St.L.74A野生型数值低50倍以上。18摄氏度下生长6天后的菌丝体转移至新鲜培养基，并在25摄氏度或6摄氏度下孵育2小时，这并未始终如一地影响所检测菌株细胞内环磷酸腺苷或环磷酸鸟苷的水平。当St.L.74A野生型菌株的菌丝体在18摄氏度下接受长达3.0小时的蓝光照射时，我们未检测到细胞内环磷酸腺苷的变化；在6摄氏度下照射长达1分钟时，也未检测到环磷酸腺苷和环磷酸鸟苷的变化。我们认为粗糙脉孢菌的质膜对环核苷酸具有通透性，环核苷酸向生长培养基中的输出可能是调节细胞内水平的一种方式。我们得出结论，影响粗糙脉孢菌中类胡萝卜素生成的三个因素（蓝光、温度和白领突变）对该生物体中可测量的细胞内环核苷酸总量没有明显影响。crisp - 1突变菌株中不存在细胞外或细胞内环磷酸腺苷或环磷酸鸟苷，这表明要么是腺苷酸环化酶（crisp - 1中不存在）催化了环磷酸腺苷和环磷酸鸟苷的合成，要么是crisp - 1突变以某种方式导致了两种酶（腺苷酸环化酶和鸟苷酸环化酶）的缺乏。
