On the Theory of ICR Heating by the Magnetic Beach Method

Plasma Physics Reports - Current interest in ion cyclotron resonance (ICR) heating by the magnetic beach method is motivated by the experiments carried out with the VASIMR plasma thruster. The...     

Nrf2基因敲除小鼠的繁育及生长发育的生物学特性

目的了解ICR-Nrf2小鼠的生物学特性。方法用原种繁殖扩群,观察繁殖性能及仔鼠的生长发育。结果ICR-Nrf2--/-与ICR-Nrf2-＋/＋比,总的产仔数与离乳数减少（P〈0.01或P〈0.05）;体重在出生后第3周时差异有显著性（P〈0.01）,第5周至第25周时同性别间差异非常显著（P〈0.01）。结论Nrf2基因缺失小鼠的产仔数、离乳数均少于野生型小鼠,仔鼠的生长速度也较野生型小鼠慢。     

Some Behavioral Features of Drosophila melanogasterStrains Carrying a flamencoGene Mutation

Olfactory sensitivity and locomotor activity was assayed in Drosophila melanogasterstrains carrying a mutation of the flamencogene, which controls transposition of retrotransposon gypsy. A change in olfactory sensitivity was detected. The reaction to the odor of acetic acid was inverted in flies of the mutator strain (MS), which carried the flammutation and active gypsycopies and were characterized by genetic instability. Flies of the genetically unstable strains displayed a lower locomotor activity. The behavioral changes in MS flies can be explained by the pleiotropic effect of the flammutation or by insertion mutations which arise in behavior genes as a result of genome destabilization by gypsy.     

适应性突变的遗传学特征

基于大肠杆菌FC40菌株的研究结果表明,适应性突变依赖RecBCD重组途径的酶,要求SOS反应的部分基因功能,lac+回复突变序列都是在单核苷酸短重复序列处的一个碱基缺失。有证据表明有的适应性突变来自一个或多个暂时性的超突变的细胞亚群,它们的基因组发生大量的突变,转座子高频丢失。产生这种暂时性的超突变的增变子可能是因为细胞的MMR活性暂时不足,或是因错误翻译产生丧失了校读活性的DNA聚合酶III。其他一些研究系统虽然得到了一些同FC40菌株不一致的结论,但所有实验证据都表明,在饥饿等环境胁迫因子作用下,非生长或缓慢生长的细胞可以产生突变,这种突变具有生长依赖的自发突变所不同的一些遗传学特征。 Abstract:The research based on the Escherichia coli FC40 showed that adaptive mutations required the enzymes of RecBCD recombination pathway and some unknown proteins of SOS response,and the mutation spectrum of lac+ revertants is single-base deletions in the small mononucleotide repeats.Some evidence showed that the revertants with adaptive mutations partly come from one (or some) subset of transient hypermutable subpopulation of cells,in which high frequently losing of transposons and genome-wide mutations were observed.It was suggested that this kind of transient hypermutability may be due to the transient deficient activity of mismatch repair (MMR) system,or a defective epsilon unit of DNA polymerase III generated by mistranslation.Although other systems demonstrated some different mechanisms from FC40,all research works suggested that,adaptive mutations occurred in nondividing or nongrowing cells under environmental stresses,for example,starvation,displayed different genetic features from growth-dependent spontaneous mutation.     

ICR heating of a plasma with a complex ion composition

Two methods for simultaneously heating ions with different masses and, accordingly, with different gyrofrequencies are considered. The first is heating in a steady uniform magnetic field by a nonmonochromatic RF field, and the second is heating in a nonuniform magnetic field by a monochromatic RF field. In the first method, the cyclotron resonance condition is ensured by the finite width of the RF field spectrum, while in the second one, by a drop in the magnetic field along the system. The study is based on the previously developed analytic model of the excitation of RF fields by current-carrying antennas. Nonlinear effects caused by variations in the longitudinal ion velocities during the ICR interaction are taken into account. It is found that ions with atomic masses in the range 85 < A < 150 (fragments of a spent nuclear fuel) can be efficiently heated in systems with moderate parameters.     

Analysis of the separation of gadolinium isotopes by the ICR method

The problem of separating gadolinium isotopes is discussed. The parameters of isotope separation in a plasma by the ICR method are estimated for a device with given operating parameters. The mean transverse energy 〈E_⊥〉 of the heated ions of the ¹⁵⁷Gd isotope and the heating efficiency η are calculated as functions of the frequency of the RF electric field in the plasma. The dependence of the heating efficiency η on the longitudinal temperature of the plasma flow is investigated. The issue of how the concentration of the target isotope ions at the collector plate depends on the longitudinal coordinate measured from the front edge of the plate is analyzed for different values of the frequency detuning parameter. The extraction coefficient Г for the target isotope is calculated as a function of the distance b between the collector plates for different frequency detunings.     

注射法制作ICR小鼠肝癌模型及其改进

应用直接注射法制作ICR小鼠原发肝癌模型并成功地进行方法改进。对模型小鼠进行了体重监测、原位移植成功率统计和病理检查,结果表明改进后的直接注射法制作小鼠原发肝癌模型的成功率显著提高,并成功模拟出肿瘤的多器官转移及人类肝癌常见的临床症状、体征。模型可以很好的满足抗肿瘤药物开发、肝癌发生发展机制研究的需要。同时,直接注射法改进方案和理念解决了直接注入细胞产生返漏的技术难题,为进一步建立其他脏器的原发或继发性癌症移植模型打下了基础。     

Theory of the ICR heating of a plasma column: Methodological note

A set of wave equations is derived that describes electromagnetic waves at frequencies on the order of the ion gyrofrequency in a plasma column with an arbitrary electron temperature. This set takes into account, in particular, the resonant interaction of electrons with waves in the transit-time magnetic pumping regime. The effect of the amplification of the electromagnetic fields of current-carrying antennas by the plasma is analyzed. The evolution of the fields with an increase of plasma density from a zero value (vacuum) is considered. The main parameters are determined for minority ion cyclotron resonance heating in the planned EPSILON system.     

口服他莫昔芬法建立ICR小鼠子宫腺肌病模型

目的使用口服他莫昔芬法建立ICR小鼠子宫腺肌病模型,并检测其病灶特征、动情周期、血管生成、子宫炎症等变化,以介绍和评价这一动物模型。方法新生ICR小鼠（15只）连续4 d滴喂他莫昔芬,并与同龄对照小鼠（15只）分别于42、85-95、135-145日龄处死,使用苏木素-伊红染色检测子宫病理改变;阴道脱落细胞法检测动情周期变化;免疫组化补体31（CD31）染色计算子宫微血管的密度、直径及所占面积比;逆转录-聚合酶链反应（RT-PCR）检测子宫缓激肽受体、神经激肽受体的基因表达。结果使用口服他莫昔芬法建立ICR小鼠子宫腺肌病模型的造模率为100%,且疾病严重程度随病程进展。部分给药小鼠可出现动情周期紊乱。85-95及135-145日龄给药小鼠子宫肌层微血管密度和面积比均高于对照小鼠（P〈0.05）。135-145日龄给药小鼠子宫缓激肽受体、神经激肽受体的基因表达较对照组明显升高（P〈0.05）。结论口服他莫昔芬法可方便、高效的建立腺肌病小鼠模型,出现腺肌病相关的血管生成、炎症状态、疼痛相关受体表达增高等特征,是研究腺肌病发生、发展的良好模型。     

Formation of Mutagens by Heating the Aqueous Solution of Amino Acids and Some Nitrogenous Compounds with Addition of Glucose

A ³H-labeled bicyclic phosphate (BP), 4-[2,3-³H]propyl-2,6,7-trioxa-1-phosphabicyclo-[2.2.2]octane 1-oxide, bound specifically to rat brain synaptic membrane preparations. The apparent dissociation constant and the quantity of the BP bound at saturation were estimated to be about 30 μm and about 2 pmol per mg of protein, respectively. BP analogs except 4-amino BP, which is extremely low in toxicity, inhibited the binding but no obvious correlation was observed between the toxicity and the inhibitory potency of the BP analogs. The binding was also inhibited by high concentrations of GABA and picrotoxinin, whereas it was enhanced by bicuculline methiodide.     

On Some Features of Early Embryonic Development Stages of Cnidaria

Division of the life cycle of Cnidaria (except for Anthozoa) into two independent generations, polypoid and medusoid, i.e., metagenesis, is considered to be unjustified. Like other Metazoa, their life cycle can be divided into three periods: embryonic, postembryonic, and definitive, i.e., according to the age [9, 10]. An important feature of Cnidaria is the transition of some postembryonic stages to the sedentary mode of life. As in other animals, this change results in a substantial reduction in organismic integrity and an anarchical type of cell division. Some researchers [3, 5, 7] regard this type of cell division as original. However, the anarchical type of cell division itself is secondary and, for this reason, cannot be ancestral to other types. The statement that the spiral type of cell division originated from the pseudo-spiral type also arouses serious criticism. The spiral type is caused by a change in the structure of the blastomere ooplasm rather than the appropriate arrangement of blastomeres.     

Some Specific Features of the Respiration of Hydrocarbon-utilizable Candida Yeasts

The respiration of both glucose-grown and hydrocarbon-grown cells of Candida tropicalis pK 233 harvested in the stationary phases was not inhibited by cyanide when glucose was used as oxidation substrate, but the former was rather stimulated in the presence of cyanide. When n-alkanes were used as oxidation substrate, cyanide lowered the respiratory activities of both cells to about 50%. With respect to the susceptibility to cyanide, the younger cells growing on n-alkanes were less sensitive in hydrocarbon oxidizing ability than the older cells, whereas the older cells growing on glucose or n-alkanes were more resistant in glucose oxidizing ability than the younger cells. Acetate was oxidized by both glucose-grown and hydrocarbon-grown cells of the yeast. Laurate was oxidized by hydrocarbon-grown cells, but not by glucose-grown cells. The respiration on laurate was inhibited completely by 3.3 mM of cyanide. In general, hydrocarbon-grown cells of Candida tropicalis pK 233 were more sensitive to various respiratory inhibitors than glucose-grown cells, although the oxidation substrates had a significant effect.

The respiration of both glucose-grown and hydrocarbon-grown cells of C. albicans, C. guilliermondii and C. lipolytica harvested in the stationary phases was also resistant to cyanide when glucose was used as oxidation substrate. But the respiration on n-alkanes of these cells was inhibited significantly by 3.3 mM of cyanide except for C. albicans.     

Racemization of Valine by Impact-Induced Heating

Homochirality plays an important role in all living organisms but its origin remains unclear. It also remains unclear whether such chiral molecules survived terrestrial heavy impact events. Impacts of extraterrestrial objects on early oceans were frequent and could have affected the chirality of oceanic amino acids when such amino acids accumulated during impacts. This study investigated the effects of shock-induced heating on enantiomeric change of valine with minerals such as olivine ([Mg_0.9, Fe_0.1]₂SiO₄), hematite (Fe₂O₃), and calcite (CaCO₃). With a shock wave generated by an impact at ~0.8 km/s, both d- and l-enriched valine were significantly decomposed and partially racemized under all experimental conditions. Different minerals had different shock impedances; therefore, they provided different P-T conditions for identical impacts. Furthermore, the high pH of calcite promoted the racemization of valine. The results indicate that in natural hypervelocity impacts, amino acids in shocked oceanic water would have decomposed completely, since impact velocity and the duration of shock compression and heating are typically greater in hypervelocity impact events than those in experiments. Even with the shock wave by the impact of small and decelerated projectiles in which amino acids survive, the shock heating may generate sufficient heat for significant racemization in shocked oceanic water. However, the duration of shock induced heating by small projectiles is limited and the population of such decelerated projectiles would be limited. Therefore, even though impacts of asteroids and meteorites were frequent on the prebiotic Earth, impact events would not have significantly changed the ee of proteinogenic amino acids accumulated in the entire ocean.     

老龄ICR小鼠对SARS-CoV的易感性

目的为探讨SARS的发病机制并提供易感的SARS动物模型。方法利用RT-PCR和病毒分离后免疫荧光技术检测成龄鼠和老龄鼠接种SARS-CoV后肺组织内病毒复制情况,同时观察两组动物的肺脏和肺外组织器官的病理变化,对肺组织进行免疫组化分析,观察SARS-CoV在肺内复制的主要部位。结果老龄鼠的感染率明显高于成龄鼠;老龄鼠肺脏出现更为严重的弥漫性肺泡损伤,其中两只老龄鼠的肺外器官出现了变性、灶状坏死以及血管广泛的扩张充血等全身中毒性变化;肺脏内病毒抗原主要存在于肺泡上皮细胞和间质的血管内皮细胞。结论老龄ICR小鼠对SARS-CoV的易感性明显高于成龄鼠,有可能作为研究SARS发病机制以及药物评价的动物模型。