有关生物技术成果转化的调查研究(上)

本文通过对中国科学院等研究机构的生物技术研究人员进行问卷调查,定性的描述了目前生物技术成果转化的总体状况和存在问题,运用相关统计分析方法阐明阻碍成果转化的因素及其结构,并提出相关解决策略 。     

A comparison of the reproductive cycle of three species of Lemur.

The duration of the luteal phase and the 'proestrus' phase in three species of lemurs (Lemur macaco, Lemur catta, and Lemur variegatus) was determined by serum progesterone measurement. Total immunoreactive estrogens were measured and remained below 0.20 ng/ml except for an apparent peak of short duration during estrus. Circulating testosterone levels in males confirm previously described seasonal gonadal function. The reproductive cycle of the female lemur is discussed and compared to the cycles of estrous and menstrual animals.     

Evidence for specificity at an early step in protein export in Escherichia coli.

We previously described mutations in a gene, secB, which have pleiotropic effects on protein export in Escherichia coli. In this paper, we report the isolation of mutants in which the activity of the secB gene was eliminated. Null mutations in secB affected only a subset of exported proteins. Strains carrying these mutations, although unable to grow on L broth plates, were still viable on minimal media. These secB mutations reversed a block in the translation of an exported protein that was caused by the elimination of another component of the secretion machinery, SecA protein. These results suggest that the secB product acts at an early step in the export process and is involved in the export of only a subset of cell envelope proteins.     

A correlative radioimmunoassay and immunohistochemical study of LHRH-induced LH depletion in the anterior pituitary of male and female neonatal rats in vitro

Summary After an exposure of 24 h to synthetic LHRH (100 ng/ml) in vitro, the anterior pituitaries of 4-day-old rats show a notable loss of immunoreactive material in most LH cells in males, but not in females. When radioimmunoassayed without incubation, the pituitary LH content of 4-day-old female rats is 2.8 times higher than that of males of the same age. LHRH treatment stimulates a higher rate of LH discharge in females than in males, but if LH release is expressed as a percentage of the initial pituitary LH content, there is no apparent difference. In both sexes, more than 70% of the initially stored LH is discharged into the medium after 24 h of LHRH stimulation. In males, this discharge produces a pronounced depletion, but in females, the pituitary still contains 78.2% of the initial LH content despite the large amount of hormone released.From these results, it is concluded that in newborn rats the LH synthetic rate in females is higher than that in males. This high synthetic activity, together with the large store of LH, may explain why prolonged LHRH treatment fails to cause LH depletion in females. At 4 days of age LHRH had no stimulatory effect on pituitary synthesis of LH in either sex.     

Escherichia coli SecB stimulates export without maintaining export competence of ribose-binding protein signal sequence mutants.

Ribose-binding protein (RBP) is exported to the periplasm of Escherichia coli via the general export pathway. An rbsB-lacZ gene fusion was constructed and used to select mutants defective in RBP export. The spontaneous Lac+ mutants isolated in this selection contained either single-amino-acid substitutions or a deletion of the RBP signal sequence. Intact rbsB genes containing eight different point mutations in the signal sequence were reconstructed, and the effects of the mutations on RBP export were examined. Most of the mutations caused severe defects in RBP export. In addition, different suppressor mutations in SecY/PrlA protein were analyzed for their effects on the export of RBP signal sequence mutants in the presence or absence of SecB. Several RBP signal sequence mutants were efficiently suppressed, but others were not suppressed. Export of an RBP signal sequence mutant in prlA mutant strains was partially dependent on SecB, which is in contrast to the SecB independence of wild-type RBP export. However, the kinetics of export of an RBP signal sequence mutant point to a rapid loss of pre-RBP export competence, which occurs in strains containing or lacking SecB. These results suggest that SecB does not stabilize the export-competent conformation of RBP and may affect translocation by stabilizing the binding of pre-RBP at the translocation site.     

Absorption and distribution of high specific radioactivity 2-C-abscisic Acid in cotton seedlings

High specific radioactivity (26.3 mc/mmole) racemic 2-¹⁴C-abscisic acid was synthesized. An aliquot of abscisic acid, 1.2 × 10⁻⁴m in aqueous methanolic solution, was applied to the surface of either a cotyledon or the first true leaf of 8- to 32-day-old cotton seedlings (Gossypium hirsutum L.). After various intervals (6-192 hours), the seedlings were processed for autoradiography, counting, and identification of the radioactivity. After 6 hours, radioactivity was observed moving basipetally out of the treated leaf toward the roots. Four days later, radioactivity could be detected throughout the whole seedling. After 8 days, 10% of the recovered radioactivity was found in the roots, and 80% remained in the treated leaf blade. Neither leaf type nor age had any effect on the abscisic acid movement or pattern of distribution. Isolated radioactivity from the roots was identified as abscisic acid, based on comparison with an authentic standard by thin layer chromatography, gas-liquid chromatography, or gas-liquid chromatography-mass spectrometry.     

The role of phytochrome in an interaction with ethylene and carbon dioxide in overcoming lettuce seed thermodormancy

Ethylene and CO₂ were used to control induction of germination in thermodormant lettuce seed (Lactuca sativa L.). These experiments ultimately showed that germination depends on the presence of an active form of the phytochrome. The phytochrome system is functional and stable at 35 C, a temperature which completely inhibits germination. Phytochrome responses to red or far red light and darkness showed that this inhibition of germination under light must be due to some other block(s) rather than to a direct inactivation of the phytochrome system itself. A postred radiation increase in lettuce seed germination that is not reversed by far red light was observed. The CO₂ requirement for C₂H₄ action is not due to a change in the medium's pH; addition of C₂H₄ plus CO₂ at the start of imbibition did not result in as much germination as when they were added several hours after imbibition. This reduction in germination, when the gases are added at the start of imbibiton, is due to CO₂.     

Reassessment of gamma doses from the atomic bombs in Hiroshima and Nagasaki

Reassessment of gamma doses from the atomic bombs in Hiroshima and Nagasaki has been carried out with thermoluminescent measurements of ceramic materials, such as bricks and decorative tiles, which were collected from buildings that remain as they were at the time of the explosions. The thermoluminescent measurements were performed using thermoluminescent dating techniques generally used in archaeology. Annual background dose rates from natural radionuclides in the ceramic materials and from environmental radiation including cosmic rays were determined with commercially available thermoluminescent detectors. A time-zero point at the original firing of the ceramic materials was estimated from the age of the buildings given in "the register book." Total background dose was evaluated by multiplying the period between the time-zero point and the time of measurement by the annual dose rate. The resultant gamma doses in Hiroshima and Nagasaki are given as a function of distance from ground zero and are compared with the DS86 (Dosimetry System 1986) and the T65D (Tentative 1965 Dose) gamma doses.