INFLUENCE OF METABOLIC DNA ON DETERMINATIONS OF THE CELL CYCLE

Abstract. Evidence in favour of labelling of DNA in excess of requirements for mitosis was found in adult organs showing no mitosis (heart muscle and brain), in organs with low mitotic indexes (liver, seminal vesicle) and, more recently, in the small intestine of rodents, in bone formation and in growing roots of Vicia faba. A survey of published data showed higher labelling indexes than would be expected from the data for S, M and t _c deducted from labelled mitoses curves. to improve the accuracy of the data needed for a complete assessment the duration of mitosis (M) and the proportion of cells which are no longer in the mitotic cycle in the crypts were determined using Colcemid. the fact that all cells in the villi are derived from the crypts and that there is no cell-loss in the villi was checked by cell-counts.
The results show that 3040%of the labelled nuclei found in crypts of the jejunum of mice at 1 hr after injection of ³H-thymidine do not proceed to mitosis.
The labelling after the last mitosis is interpreted as formation of the metabolic DNA necessary for the function of the differentiated cells in the villi. There is some evidence that metabolic DNA necessary for the processes of mitosis might be lost     

SWELLING OF ERYTHROCYTES IN SOLUTIONS OF AMMONIUM SALTS

Two rather simple equations have been derived, which make it possible to express in a single number the result of a series of determinations of the volume of erythrocytes swelling in solutions of ammonium salts. In all experiments made with several combinations of different concentrations of permeating and non-permeating salts, the curves calculated from the equations have covered the points found by experiment.     

INFLUENCE OF IONIC CONDITIONS ON CELL DIFFERENTIATION AND MORPHOGENESIS OF THE CELLULAR SLIME MOLDS

Effects of various ionic conditions on the development of the cellular slime molds D. discoideum and D. mucoroides were studied. A certain concentration of lithium ions (7 mM) promoted differentiation of the stalk cells and conversely inhibited formation of the spores. The presence of calcium and magnesium ions was needed for Li to manifest its specific effect. A high concentration of Ca (100-120 mM) also facilitated differentiation of the stalk cells. On the other hand, fluoride ions stimulated considerable formation of spores at 15 mM. In the absence of divalent cations, sodium ions inhibited morphogenesis and cell differentiation proportionately with its concentration, and complete inhibition was obtained at 20 mM. The inhibitory effect of Na was nullified by addition of small amounts of Ca. Possible mechanisms by which these ions exert their influences on development of this organism were discussed.     

温度对人肺癌细胞 A549蛋白质表达的影响

肺癌蛋白质组的研究,有助于阐明其发病机制并对肺癌的防治有益。本文从研究人肺癌细胞热休克蛋白的表达情况出发,通过比较37℃、42℃和45℃培养条件下的人肺癌细胞A549总蛋白质的双向电泳图谱,获得3个温度敏感的差异蛋白点,依次命名为P_1、P_2、P_3。对差异蛋白进行MALDI-TOF-MS分析和采用SWISS-PROT数据库中的Peptident软件检索后,初步鉴定P_1与2种醛酮还原酶家族成员相匹配,P_2可能为一种新蛋白,P_3为锌指蛋白11A。     

孕激素的长期作用对子宫内膜癌Ishikawa细胞生物学行为的影响

研究孕激素的长期作用对子宫内膜癌Ishikawa细胞增殖、侵袭能力的影响及雌孕激素受体亚型表达的改变。将对孕激素抑制作用敏感的Ishikawa细胞长期暴露于含梯度递增的醋酸甲羟孕酮(medroxyprogesterone acetate,MPA)培养基中。MTT法、流式细胞技术(FACS)、Transwell小室法分别检测MPA对细胞增殖活力、细胞周期、侵袭能力的影响。RT-PCR技术检测MPA对CyclinD1、MMP2、MMP9表达的影响,细胞免疫化学检测雌、孕激素受体各亚型表达的变化。Ishikawa细胞(母代Ishikawa)经MPA作用10个月后,对MPA的生长抑制作用耐受(耐药Ishikawa)。MPA由对母代Ishikawa细胞增殖、侵袭能力的抑制作用转为对耐药Ishikawa细胞的促进作用。MPA抑制母代Ishikawa细胞CyclinD1、MMP2、MMP9的表达,促进耐药Ishikawa细胞CyclinD1、MMP2、MMP9的表达。与母代Ishikawa细胞相比,耐药Ishikawa细胞ERα、PRB阳性表达率明显下降,ERβ阳性表达率明显上升(均有P<0.05)。结果提示:MPA的长期作用能够导致对孕激素抑制作用敏感的Ishikawa细胞对MPA耐受,MPA对子宫内膜癌细胞增殖、侵袭能力的抑制作用转为促进作用,ER、PR亚型表达的失衡可能为子宫内膜癌孕激素耐药发生的机制之一。     

IONIZING INFLUENCE OF SALTS WITH TRIVALENT AND TETRAVALENT IONS ON CRYSTALLINE EGG ALBUMIN AT THE ISOELECTRIC POINT

1. While crystalline egg albumin is highly soluble in water at low temperature at the pH of its isoelectric point, it is coagulated by heating. It has long been known that this coagulation can be prevented by adding either acid or alkali, whereby the protein is ionized. 2. It is shown in this paper that salts with trivalent or tetravalent ions, e.g. LaCl₃ or Na₄Fe(CN)₆, are also able to prevent the heat coagulation of albumin at the isoelectric point (i.e. pH 4.8), while salts with a divalent ion, e.g. CaCl₂, BaCl₄, Na₂SO₄, or salts like NaCl, have no such effect. 3. This is in harmony with the fact shown in a preceding paper that salts with trivalent or tetravalent ions can cause the ionization of proteins at its isoelectric point and thus give rise to a membrane potential between micellæ of isoelectric protein and surrounding aqueous solution, while the above mentioned salts with divalent and monovalent ions have apparently no such effect.     

泽蛙单倍体细胞RNA含量对胚胎发育和成活的影响

对两栖类单倍体的综合症以及死亡原因,前人有许多不同认识,本文用实验说明,单倍体细胞的RNA含量不及二倍体的一半,并认为,单倍体泽蛙的死亡原因与其细胞中RNA含量不足密切相关。     

INFLUENCE OF THE TONIC EFFECT OF GRAVITATION AND AUXIN ON CELL ELONGATION AND POLARITY IN ROOTS

The influence of a longitudinal (tonic) gravitational force and of auxin on the pattern of growth and cell polarity has been studied on intact roots of wheat seedlings. A klinostat technique was used for controlling gravitation. Growth in length was evaluated as cell division activity, rate of cell elongation (μ/h) and duration of elongation (h). Exogenous auxin (1-NAA) increases the rate of cell elongation in all concentrations tested (10⁻⁸ — 3 × 10⁻⁷m ) and shortens the time of elongation with increasing concentration. It promotes rate of cell elongation in roots as it does in shoots. It also accentuates the polar insertion of root hairs and their growth. The tonic effect of gravitation resembles that of an increase in auxin both in light and darkness. The results are discussed in relation to plagiotropic growth of roots, root growth promotions by auxin, and the difference between root and shoot growth.     

THE EFFECT OF NaCl ON THE PHAGE-BACTERIUM REACTION

1. The presence of 0.25 M NaCl during the reaction between a staphylococcus phage and susceptible organisms results in a five to tenfold increase in the amount of phage produced. 2. Analysis of the reaction indicates that normal kinetic relationships exist until just before lysis occurs. At this time the organisms enter the stationary phase, lysis is delayed approximately 0.7 hour as compared with control mixtures and phage continues to be produced at the usual rapid rate. 3. Apparently there are conditions under which phage can be produced in the absence of bacterial growth although previous work has uniformly emphasized growth of the bacterial substrate as the prime conditioning factor for formation of phage.     

超声波和相转移催化下的Reimer—Tiemann反应

本文研究了超声波和相转移催化剂在Ｒｅｉｍｅｒ—Ｔｉｅｍａｎｎ反应中的应用,提出了超声波和相转移催化下Ｒｅｉｍｅｒ—Ｔｉｅｍａｎｎ反应的机理。研究结果表明：在超声波和相转移催化剂的共同作用下,二氯卡宾形成十分迅速,羟基苯甲醛产率显著提高,反应时间成倍缩短。