The nucleotide sequence of a cDNA clone containing the entire coding region for mouse X-chromosome-linked phosphoglycerate kinase

A clone containing cDNA for X chromosome-linked phosphoglycerate kinase (PGK-1) was isolated from a mouse myeloma cDNA library. The nucleotide (nt) sequence of the cDNA has been determined, and the amino acid (aa) sequence of the enzyme thereby deduced. At the nt level, the coding region of mouse PGK cDNA has 93% homology with human X-linked cDNA and 60% homology with the yeast gene. Mouse PGK-1 protein contains 416 aa and is 98%, 96% and 64% homologous with human, horse, and yeast enzyme sequences, respectively.     

Regulation of the yeast metallothionein gene

To study regulation of the yeast CUP1 gene, we have employed plasmids containing the CUP1 regulatory sequences fused to the Escherichia coli galK gene. A comparison of galK expression from low- and high-copy-number CUP1/galK fusion plasmids demonstrated that both basal and induced levels of galactokinase (GalK) increase proportionately with plasmid copy number. Host strains with an amplified, single or deleted CUP1 locus were compared to look for effects of chromosomal CUP1 gene dosage on expression from the episomal CUP1 promoter. Basal GalK levels are similar in CUP1R and cupls hosts, but can be induced to higher levels in the cup1s than the CUP1R host. In contrast, in a strain deleted for the chromosomal copy of CUP1, synthesis of GalK is constitutive but can be induced to yet higher levels by copper. A hybrid vector, placing the CUP1 coding sequence under the control of a constitutive promoter, was constructed. Introduction of this hybrid CUP1 gene into the deletion host containing the CUP1/galK plasmid restores regulation. Thus, metallothionein, in trans, can effect repression of the CUP1 promoter. The possible roles of metallothionein and free copper in CUP1 regulation are discussed.     

Methyl bromide inhibits ripening and ethylene production in tomato (lycopersicon esculentum mill.) fruit

Tomato fruit ripening and ethylene production were inhibited following treatment with methyl bromide (MB). Methyl bromide significantly delayed ripening initiation in mature-green (MG) fruit and retarded the rate of ripening of turning (T) fruit as measured by color development and flesh softening. Treatment with MB caused an initial transient burst of ethylene production, but the subsequent ripening-associated increase in ethylene was delayed. Ethylene treatment partially overcame MB inhibition in MG fruit but had no affect on T fruit. The inhibition of ethylene production by MB appears to be due to lack of formation of 1-aminocycloprone-1-carboxylic acid (ACC) in MG fruit, whereas in T fruit lack of conversion of ACC to ethylene is indicated. A key feature of MB inhibition of ripening in tomato appears to be reduced sensitivity to ethylene.     

The effects of aluminum loading on the renal response to parathyroid hormone in the vitamin D-replete rat

Aluminum (Al) may cause vitamin D-resistant osteomalacia and depress the serum levels of immunoreactive parathyroid hormone (iPTH) in patients treated with maintenance dialysis and those on total parental nutrition (TPN). Both conditions have been associated with low serum levels of 1,25(OH)2-vitamin D (1,25(OH)2D). Al may inhibit PTH secretion in vitro; however, induction of hypocalcemia can enhance endogenous PTH secretion in Al-loaded dogs and TPN patients. Despite hypocalcemia and/or increased endogenous iPTH levels, Al-loaded TPN patients fail to show the expected rise in serum 1,25(OH)2D levels. Such observations suggest that Al may impair the renal response to PTH. We studied vitamin D-replete rats given Al or saline vehicle IP for 5 days. Al and control rats then received a saline infusion with an IV bolus of PTH 1-34. Urinary cyclic AMP and P excretion rose in Al and control rats by 1 hr post-PTH, without differences between the groups. Serum P and ionized Ca levels were not different between Al and control rats. In other Al and control rats, serum 1,25(OH)2D levels were measured after saline without PTH. Serum 1,25(OH)2D levels were higher in controls given PTH than in those without, but 1,25(OH)2D levels were not different between Al rats given PTH and those with none. Thus, aluminum does not affect cyclic AMP or P excretion but may impair 25(OH)D-1 alpha-hydroxylase activity in response to PTH.     

确定动态经济阈值的微计算机模型

经济阈值必须有动态的特征,甚至在同一块田里,也可能每年不一样,本文建立了确定经济阈值的系统模型。它们是由4个模型所组成:1,温度模型;2.种群动态模型;3.防治消费模型;4.产量模型。然后经济阈值这一点,通过计算机模拟,在边际步入等于边际消费时得到。用户可以按照不同的情形输入不同的参数,计算机输出将给出经济阈值及纯收益。 从系统观点看,确定经济阈值可以看作管理农业生态系统寻求最优管理措施。所以,本文提出的模型,也可看作最优管理模型,细节将在文内讨论。     

Randomised controlled trial of computer assisted management of hypertension in primary care.

The hypothesis that general practitioners would obtain better outcomes for patients with hypertension using a computer than doctors not using a computer was tested. Sixty family physicians were randomised to two treatment strategies. "Test" physicians completed a data collection form after each visit from a patient with hypertension and mailed the forms to the test centre for processing. Computer feedback on management was mailed to the doctors. This encouraged doctors to apply the "stepped care" protocol, supplied charts of diastolic blood pressure v time, and ranked patients'' diastolic blood pressures by percentile. Letters were mailed to patients to remind them of appointments. "Control" doctors filled out the same data collection forms as test physicians, but neither doctors nor patients received computer feedback. Physicians who used the computer saw more patients per practice than control doctors (test 50 patients, control 40). For all patients the length of follow up was significantly longer in test practices (test 199 days, control 167), and a smaller percentage dropped out of active treatment in test practices (test 37.5%, control 42.1%). For patients with "moderate" hypertension of a baseline diastolic pressure of greater than 104 mm Hg the mean score of the last recorded pressure was below the goal of 90 mm Hg in test practices (88.5 mm Hg), but it failed to reach this goal in control practices (93.3 mm Hg). A greater average reduction of diastolic pressure was achieved in test practices (test 21.7 mm Hg, control 16.7 mm Hg). Though patients with "moderate" hypertension were better controlled in test practices than in control practices, the patients in test practices visited their doctors less often (test 13.3 visits per patient-year, control 17.4 visits). Among patients with newly detected hypertension test practices achieved a greater reduction in diastolic pressure than control practices (test 15.1 mm Hg v control 11.3 mm Hg) and more sustained control of hypertension (test 323 days per patient-year with a diastolic pressure of 90 mm Hg or less v control 259 days).     

夏蜡梅核型的研究

本文首次报道我国特有重点保护植物夏蜡梅的核型为K(2n)=2x=22=18m+2m(SAT)+2sm,属Stebbins的“1A”类型,在演化上处于相当原始的地位。它的核型似比北美的光叶红对称和原始,因此至少夏蜡梅属可能起源于中国。