STUDIES ON THE FUNCTION OF INTRACELLULAR RIBONUCLEASES : III. The Relationship of the Ribonuclease Activity of Rat Liver Microsomes to their Biological Activity

Attempts have been made to prepare rat liver microsomes and ribosomes free of RNase activity. Washing of microsomes with a large number of reagents, as well as preparation of microsomes by homogenizing the liver in the presence of a variety of reagents chosen to remove or inhibit RNase activity, failed to abolish completely the enzyme activity. However, when rat liver was homogenized in the presence of optimal concentrations of ATP the microsomes subsequently obtained showed no RNase activity. The composition of such microsomes was compared to controls prepared without the use of ATP. Preparation of microsomes with the use of ATP apparently repressed but did not remove the RNase activity for, when such microsomes were treated with 1 per cent deoxycholate to obtain ribosomes, the latter exhibited normal RNase activity. A possible explanation for these results based on several experiments is given. The incorporation of C¹⁴ of L-leucine-C¹⁴ into control and ATP-treated microsomes was measured. Repression of RNase activity by use of ATP or with RNase inhibitor, significantly reduced the incorporation. As a result of these and other experiments it is tentatively concluded that an alkaline RNase is a normal constituent of rat liver ribosomes and plays a role in the biological activity of these particles.     

Batchwise Purification of Liver Ribosomes and Polysomes from Unfasted Mice on Hydroxylapatite

Batchwise purification of liver ribosomes and polysomes on hydroxyl-apatite is a rapid procedure to remove glycogen, hemoglobin, ribonuclease and other contaminants from ribosomal preparations. Ribosomes and polysomes are adsorbed to hydroxylapatite in a Büchner filter funnel and the contaminants are eluted from the hydroxylapatite with 0.15 M KH₂PO₄. The ribosomes and polysomes are then eluted with 0.3–0.4 M KH₂PO₄ and concentrated by centrifugation. The resolution of the polysome profiles was greatly improved following purification. The purified ribosomes could be dissociated into subunits at 0.3 M KCl, and showed no loss of activity in poly-U directed phenylalanine synthesis.     

INTRACELLULAR LOCALIZATION OF ENZYMES IN SPLEEN : II. Some Properties and the Distribution of Ribonuclease in Rat Spleen

Some properties of rat spleen ribonuclease have been studied, and the intracellular distribution of the enzyme and ribonucleic acid have been presented. Spleen ribonuclease exhibits maximal activity at pH 5.8, and although there is some evidence for the presence of an enzyme with an optimum at pH 7.0, it is not conclusive. The enzyme is concentrated primarily in the mitochondrial fraction, but significant quantities occur in the supernatant fluid. The latter contains ribonuclease inhibitor similar to that found in liver. The effects of whole body x-irradiation, magnesium ion, substrate concentration, type of buffer, presence of p-chloromercuriphenylsulfonic acid, deoxycholate, and Triton X-100 on ribonuclease activity are examined.     

COMPARATIVE STUDIES ON RESPIRATION : IV. THE EFFECT OF ETHER ON THE RESPIRATION OF WHEAT.

These experiments show that 7.3 and 3.65 per cent ether solutions cause an increase in respiration followed by a decrease. The results agree with those of Haas on Laminaria, of Gustafson on higher fungi, and of Mrs. Brooks on bacteria. They do not agree with the theory of Verworn that anesthesia is a kind of asphyxia and that it decreases respiration.     

STUDIES OF SPERMATOGENESIS IN THE HEPATICAE. IV. ON THE BLEPHAROPLAST OF BLASIA

Spermatogenesis in Blasia pusilla L. was reexamined with electron optics to help evaluate conflicting results of the two earlier light microscope studies of this species. The present micrographic resumé of spermatid transformation confirms Sharp's observation of centrosomes in very young spermatids and agrees with Woodburn's general account of spermatozoid maturation. Further, male gamete development in Blasia is shown to be closely comparable to that of Marchantia and Pellia. It is concluded that Sharp's report of blepharoplast development in Blasia by fragmentation and coalescence was based on anomalous plant material.     

核黄素生物合成研究 1.微量培养中核黄菌(Eremothecium ashbyii)发育过程中的形态变化

从本试验观察到,核黄菌的生长全部过程是自配子或菌丝在培养基中开始发育成营养菌丝,部分菌丝形成配子囊形成配子,部分菌丝衰老自溶。当菌丝发育最盛时,核黄素的形成是最多,衰老时培养基核黄素逐渐丰富起来。核黄菌在有空气和缺乏空气时,它们的发育是有区别的,即是在缺乏空气(表面下生长)时,菌丝是细长不形成配子和产生少量核黄素。     

中国白粉菌属的分类研究Ⅳ.十字花科上的一个新种

本文描述了采自北京香山的细子薄菜 Rorippa cantoniensis(Lour.)Ohwi(十字花科)上的一种新白粉菌 Erysiphe rorippae Chen & Zheng sp.DOV.蔊菜属是白粉菌属的寄主新记录。在附属丝形态上,本新种因附属丝往往在顶部略膨大呈棍棒形而与唇形科上的华阴白粉菌 Erysiphe huayinensis Zheng & Chen 颇为近似,但因子囊壳直径较大,子囊孢子数目较少、体积较大且在两端钝尖而与该种很易区分。与十字花科上的另外两个已知种,即十字花科白粉菌 Erysiphe cruciferarura(Opiz)Junell 和南芥白粉菌 Erysiphe arabidisZheng & Chen 相比则无论在什么方面都没有共同之处。这三个种可检索如下:     

CYTOCHEMICAL STUDY ON THE PANCREAS OF THE GUINEA PIG : VII. Effects of Spermine on Ribosomes

Pancreatic ribosomes (guinea pig) aggregate and lose upon treatment with polyamines, particularly spermine, their bound secretory enzymes. Spermine, at 0.5 mM, for example, causes the release of about 85 per cent of the chymotrypsinogen and RNase, and from 85 to 100 per cent of the ribosomal amylase. At the same time, the particles lose about 10 per cent of their RNA, 7 to 24 per cent of their total protein, and from 75 to 100 per cent of their Mg⁺⁺. Observations with the electron microscope confirm the heavy agglutinating of the ribosomes but otherwise show little change in the structure of the particles. Using radioactive spermine it was found that, concomitant with the loss of bound enzymes and Mg⁺⁺ from the ribosomes, spermine became bound to the particle. The extent of binding ranged from 0.29 to 1.49 µmoles per 10µmoles RNA-P. The bound radioactive spermine can be removed by subsequent treatment of the ribosomes with GTP, ATP, or P-P, which treatment also removes most of the RNA of the particles, leaving behind ribosomes with a much lower RNA/protein ratio. From this evidence it was inferred that spermine, in releasing the Mg⁺⁺ of the particle, becomes salt-linked to the free phosphate hydroxyl groups of the RNA. Freshly isolated pancreatic and hepatic ribosomes contain very little spermine, about 0.1 to 0.2 µmoles polyamine/10 µmoles RNA-P. The results are discussed in terms of the linkages between the structural protein, the bound secretory enzymes, and the RNA of the ribosomes.     

STUDIES ON THE HUMAN CORPUS LUTEUM : II. Observations on the Ultrastructure of Luteal Cells During Pregnancy

The ultrastructure of human corpora lutea obtained during the 6th, 10th, 16th, and 35th week of pregnancy is reported. Differences between the established luteal cell of pregnancy and the transitory luteal cell of the menstrual cycle are noted. In pregnancy the luteal cell is more compartmentalized into a peripheral mass of ER (endoplasmic reticulum) and a central area where mitochondria and Golgi complexes are concentrated. The latter area extends to a cell surface where microvilli face on a perivascular space. Long bundles of filaments are prominent within the luteal cell cytoplasm and, in contiguous cells, appear to arise from adjacent desmosomal regions. Bilateral subsurface cisternae of granular ER at lateral cell borders appear to be areas of specialized junctional surfaces. Certain luteal cells with irregular nuclear membranes are also characterized by vesicular aggregates enclosed within a single membrane. These aggregates are found within the peripheral nucleoplasm or the perinuclear cytoplasm. Their single limiting membrane often appears continuous with either the inner or outer leaflet of the nuclear membrane.     

STUDIES ON LUMINOUS BACTERIA : II. THE INFLUENCE OF TEMPERATURE ON THE INTENSITY OF THE LIGHT OF LUMINOUS BACTERIA.

1. A method has been described whereby the intensity of the light of luminous bacteria may be measured in a quantitative manner. 2. It is pointed out that the temperature coefficients for light intensity do not follow the van''t Hoff rule, but are higher and vary with each 10° temperature interval. 3. From a comparison with other data it is found that the process is not a simple one, but that the observed curve is the resultant of several reactions which proceed simultaneously. 4. The discrepancies in the temperature coefficients in the neighborhood of the "optimum temperature" may be due to a process of coagulation of the colloidal particles of the enzyme. This coagulation will tend to cause a deviation of the curve away from that normal for chemical reactions.     

STUDIES OF THE TRIAD : IV. Structure of the Junction in Frog Slow Fibers

The structure of the triadic junction in frog slow fibers has been studied and compared with that of twitch fibers. The junctional gap is wider (by approximately 13%) in slow fibers. The junctional feet have the same size and disposition as in twitch fibers, although the size and shape of the junctional areas are different. It is concluded that the role of triads in slow fibers is the same as in twitch fibers     

STUDIES ON THE METABOLISM OF AUTOTROPHIC BACTERIA : I. THE RESPIRATION OF THIOBACILLUS THIOOXIDANS ON SULFUR

The data of this paper indicate that: 1. The "energy of activation" (µ) of sulfur oxidation by the autotrophic bacterium, Thiobacillus thiooxidans, is similar to that of other respirations. 2. The pH of the menstruum does not influence the respiration on sulfur between the limits of pH 2 to 4.8 once contact between the bacterial cell and the sulfur particle has been established but it does influence the rate at which such contact occurs. 3. The pO₂ has little effect upon the respiration of this organism. 4. Most organic materials have no detectable effect upon the respiration of Thiobacillus thiooxidans, but the organic acids of terminal respiration seem to stimulate the respiration in the absence of oxidizable sulfur and certain of them inhibit sulfur oxidation. 5. In so far as inhibitor studies on intact cells are trustworthy, sulfur oxidation goes through iron-containing systems similar to cytochrome. It is possible that the oxygen contained in the sulfuric acid formed during sulfur oxidation is derived from the oxygen of the water.     

COMPARATIVE STUDIES ON RESPIRATION : IX. THE EFFECTS OF ANTAGONISTIC SALTS ON THE RESPIRATION OF ASPERGILLUS NIGER.

1. In the presence of 0.05 per cent dextrose the respiration of Aspergillus niger is increased by NaCl in concentrations of 0.25 to 0.5M, and by 0.5M CaCl₂. 2. Stronger concentrations, as 2M NaCl and 1.25M CaCl₂, decrease the respiration. The decrease in the higher concentrations is probably an osmotic effect of these salts. 3. A mixture of 19 cc. of NaCl and 1 cc. of CaCl₂ (both 0.5M) showed antagonism, in that the respiration was normal, although each salt alone caused an increase. 4. Spores of Aspergillus niger did not germinate on 0.5M NaCl (plus 0.05 per cent dextrose) while they did on 0.5M CaCl₂ (plus 0.05 per cent dextrose) and on various mixtures of the two. This shows that a substance may have different effects on respiration from those which it has upon growth.     

STUDIES ON THE HUMAN OOCYTE AND ITS FOLLICLE : I. Ultrastructural and Histochemical Observations on the Primordial Follicle Stage

Oocytes in primordial (resting) follicles in adult human ovaries contain a complex paranuclear structure identified by light microscopists as Balbiani's vitelline body. By electron microscopy this structure is composed of a mass of mitochondria with associated endoplasmic reticulum, multiple compound aggregates which form a ring around the cytocentrum, and a single stack or coil of annulate lamellae either attached to the nuclear membrane or free in the cytoplasm. The compound aggregates contain vacuoles and finely divided electron-opaque material. Evidence is presented for the probable transport of this material between the oocyte and its environment. The cytocentrum contains a central aggregate of amorphous electron-opaque deposits which appear to become periodically aligned on fine fibrils to form the long coarse fibers at the periphery of the cytocentrum. The apparent prevalence of annulate lamellae attached or adjacent to the nuclear membrane of oocytes in ovaries removed during the mid-follicular (estrogenic) phase of the cycle indicates the need for further study of a possible hormonal influence on the resting oocyte. By light microscopy phosphatases were not found within the oocyte, but adenosine-monophosphatase activity is present in the cortical cells surrounding primordial follicles, and also at the periphery of each primitive follicle cell, most prominently at the oocyte side. Glucose-6-phosphate dehydrogenase activity is present within the oocyte cytoplasm.     

蓝藻(A.variabilis)藻胆体核结构与功能的研究II.变藻蓝蛋白六聚体内能量传递过程的物理机制

以变藻蓝蛋白的晶体结构和光谱性质为基础,利用密度矩阵理论对变藻蓝蛋白六聚体内的激发能传递物理机制进行分析,并利用时间分辨荧光光谱技术对其能量传递途径进行实时探测。结果表明：在变藻蓝蛋白六聚体内,色素对（毗邻单体上的色素αｉ８４βｊ８４,其中ｊ＝ｉ±１,和β＊ＬＣＭ４２）内的能量传递服从激子偶极－偶极相互作用机制;而色素对之间的能量传递机制则为Ｆｒｓｔｅｒ偶极－偶极相互作用机制,并且其能量传递途径分为两类：（１）．两个变藻蓝蛋白三聚体之间色素对的能量传递,其时间常数大约为１５ｐｓ左右;（２）．同一变藻蓝蛋白三聚体内色素对间的能量传递,在ＡＰＩＩ三聚体内,其能量传递时间大约为４５ｐｓ左右,而在ＡＰＩ三聚体内,其能量传递时间常数为４５ｐｓ和６５ｐｓ。