绿豆线粒体呼吸链在不同电子传递途径中的电子漏

绿豆线粒体的呼喊链在氧化不同义莪时有不同的呼吸速率和电子漏速率,但是Ｏ２＾－／Ｏ２比值较稳定。呼吸链部位Ⅱ的抑制剂抗霉素Ａ对α－酮茂二酸、琥珀酸及苹果本工物时的电子漏速率和Ｏ２＾－／Ｏ２比值都明显的促进作用,说明电子漏发生的位点可能在抗纱Ａ的抑制点之前。呼吸链在氧化外源ＮＡＤＨ时,线料体所产生的地氰化物、鱼藤酮、抗弱Ａ及ＳＨＡＭ都不敏感,而对钙离子的螯合剂ＥＧＴＡ显著敏感。因此,依赖于钙离子的ＮＡ     

MICROINCINERATION, ELECTRON MICROSCOPY, AND ELECTRON DIFFRACTION OF CALCIUM PHOSPHATE-LOADED MITOCHONDRIA

Isolated rat liver mitochondria were incubated in vitro under conditions supporting the massive accumulation of calcium and phosphate. Samples were embedded, thin sectioned, and examined in the electron microscope. The intramitochondrial distribution of insoluble or structure-bound mineral substances was studied by electron microscopy coupled with recently developed techniques of high resolution microincineration. As shown previously, the ion-loaded mitochondria acquire large, internal granules which have inherent electron opacity indicative of high mineral content. Study of ash patterns in preselected areas of sections directly confirmed the high mineral content of the granules, and the appearance of the residues was consistent with the copresence in the granules of some organic material. Other mitochondrial structures were almost devoid of mineral. Thin sections of unincubated control mitochondria also were incinerated. They were found to contain appreciable amounts of intrinsic mineral, seemingly associated with membranes. The normal, dense matrix granules commonly seen in unaltered mitochondria could be seen in intact sections of these control preparations, but after burning no definite correspondence of any ash to the granules could be demonstrated. The normal granules perhaps do not contain mineral. Heating experiments on ash patterns of all the preparations demonstrated the thermal stability and crystallizability of the ash. The crystallized ash of the in vitro-produced dense granules was tentatively shown by electron diffraction to be β-tricalcium phosphate (whitlockite). This, together with evidence from the literature, suggests that the original, noncrystalline mineral may be a colloidal, subcrystalline precursor of calcium-deficient hydroxyapatite. Experiments were performed on synthetic calcium phosphates for comparison. Other possible applications of the microincineration techniques are briefly discussed.     

ELECTRON MICROSCOPY AND ELECTRON PROBE ANALYSIS OF MITOCHONDRIAL CATION ACCUMULATION IN SMOOTH MUSCLE

The contractile responses to barium and the ultrastructure and ionic composition of mitochondria were studied in vascular smooth muscle. In normal rabbit portal anterior mesenteric vein (PAMV) and main pulmonary artery (MPA) smooth muscle mitochondria were frequently associated with the surface vesicles. The average distance between the outer mitochondrial and inner surface vesicle membrane was 4–5 nm. Ba contractures of MPA were tonic and of PAMV were phasic. Incubation of MPA and PAMV with Ba resulted in the accumulation of mitochondrial granules, followed in the MPA by massive mitochondrial swelling. Oligomycin and anoxia inhibited the appearance of mitochondrial electron-opaque granules and prevented the Ba-induced mitochondrial swelling in the MPA. Electron probe analysis of mitochondria in PAMV incubated with Ba and containing granules showed characteristic Ba signals over the mitochondria. Electron probe X-ray microanalysis also showed a highly significant (P < 0.001) correlation of P with mitochondrial Ba, in an estimated elemental ratio of approximately 3 Ba/4 P. Mitochondrial granules were still prominent after block staining of the osmium-fixed, Ba-loaded PAMV, but electron probe microanalysis showed no Ba, but only U, emissions. Tissues incubated with strontium had electron-opaque mitochondrial granules and deposits in the sarcoplasmic reticulum. X-ray microanalysis of mitochondria containing granules showed the presence of characteristic Sr and Ca emissions. The presence of Sr was similarly verified in the sarcoplasmic reticulum. These findings indicate the energy dependent uptake of divalent cations, in association with phosphate, by mitochondria in vascular smooth muscle in situ and the possibility that mitochondria may contribute to the regulation of intracellular divalent cation levels in smooth muscle.     

POLYESTER-METHACRYLATE EMBEDMENTS FOR ELECTRON MICROSCOPY

It has been found that tissues fixed for electron microscopy and dehydrated in acetone can be embedded in mixtures of n-butyl methacrylate and polyester resin. Activation with 1 per cent tert-butyl hydroperoxide followed by 12 to 48 hours at 60°C produces blocks that section well with glass knives. The ribbons are cleared of methacrylate by heat (200–250°C for 1 hour) and/or immersion in organic solvents (CCL₄, acetone-ether). After removal of the methacrylate the residual polyester matrix provides thermostable and insoluble support for the tissue. Its insolubility permits staining by immersion of cleared preparations in organic solvents carrying heavy metal compounds in solution. Clearing by heat stabilizes section-grid relationships. The removal of volatile materials by clearing substantially reduces contamination of both specimen and microscope. Tissue fine structure is well preserved in these preparations.     

RESOLUTION IN ELECTRON MICROSCOPE RADIOAUTOGRAPHY

An analysis of grain distributions around a radioactive line source (consisting of polystyrene-³H) showed that the shape of the distribution was independent of the factors that influence resolution, i.e. section and emulsion thickness, silver halide crystal, and developed grain size. These factors did effect the spread of the distribution, however, and thus the distance from the line source within which 50% of the total developed grains fell. We called this distance "half distance" (HD) and determined it for a variety of specimens. When grain distributions were normalized in units of HD, one could plot universal grain distributions for specimens with radioactive sources of various shapes. The use of HD and the universal curves in interpreting radioautograms is discussed.     

SCANNING ELECTRON MICROSCOPY AND ELECTRON MICROPROBE ANALYSIS OF SILICIFICATION PATTERNS IN INFLORESCENCE BRACTS OF AVENA SATIVA

Using scanning electron microscopy, we determined the kinds and distribution of epidermal cell types in Avena inflorescence bracts (glume, lemma, and palea). Electron microprobe analysis of silica deposition in these epidermal cells showed that silica cells constitute one of the important deposition sites. Probe ratio data indicate that the silica deposited is 74 % pure. Significant amounts of silica also become deposited in the trichomes and lesser amounts in the walls of long epidermal cells. None could be detected in the stomata. The possible functional significance of silica deposition in epidermal cells of these bracts is discussed.     

构象电子系统的集体激发,跃迁过程和合作现象

本文给出了一套对分子生物学问题进行理论分析的方法并列举简单应用的实例.以分子构象和前沿电子为变数,引入了构家电子场,给出了研究其集体激发的Green函数途径,指出生物凝聚态中存在新型局域激发.导出了构象电子跃迁哈密顿量,特别研究了光致构家电子跃迁,指出低阶跃迁为非Franck—Condon型的.研究了链式分子的合作现象,阐明了振动激发对于实现合作转变的重要性及转变中可能存在反常温度依赖.     

蚤类足跗节细微结构的扫描电镜观察

本文报道4科18属26种蚤类足附节的扫描电镜观察结果, 发现了蚤类足咐节上的若干种感器和类似于爪垫的结构.感器的形式主要是毛形感器和刺形感器;以爪垫结构位于副爪下方, 具有许多微小棘毛.爪与副瓜对应面上均具有横纹.多数种类第5跗节蹠面上具有许多感觉毛, 其数量和分布在不同种甚至两性之间均有差异, 拟可用于分类鉴定.根据第5跗节侧蹠鬃的数目及本研究第一部分感觉板上感觉室的数目对所观察的4科蚤类进行了分型, 并对其进化地位进行了讨论.     

三维电子显微镜方法进展

从生物样品（细胞或大分子）的电镜图象重组其三维结构的方法近年取得了重大进展,这是冷冻电镜样品制备、电镜设备、图象处理和分析方法等几方面进步的综合结果。三维电镜方法的进步和完善,使细胞和学家得以了解在复杂的细胞过程中各种相关细胞器之间的空间关系,而使分子生物学家不仅可以研究那些能够形成二维结晶的样品,并为分析具有重要生物功能但不能形成二维结晶的大分子或分子聚休物的结构提供了一种强大的手段。     

ELECTRON MICROSCOPIC STUDIES OF RENAL DISEASE

The nephrotic syndrome, glomerulonephritis, disseminated lupus erythematosus and the Fanconi syndrome show characteristic changes with electron microscopy.Experimental studies of animals were carried out to determine the significance of such changes by observing reactions that occur under carefully controlled conditions. A lesion with collagen deposition that was found in the centrolobular region of glomeruli sheds new light on the function of this region. This evidence must be considered in developing an understanding of how the production of urine is controlled. Fluid-filled compartments and various bodies associated with the ultrastructure of tubule cells can be produced under conditions which suggest that these structures play a role in tubular resorption.     

ELECTRON MICROSCOPY OF CARTERIA AND CHLAMYDOMONAS

Cultures of Chlamydomonas eugametos, Chl. sp., Carteria eugametos, C. crucifera, C. radiosa, and C. sp. were examined with the electron microscope to determine generic differences between Carteria and Chlamydomonas at the ultrastructural level. The ultrastructure of the flagella, mitochondria, dictyosomes, nuclei and ground substance was noted to be similar in all species. The cellular boundary of all species except Chlamydomonas eugametos contains a 250 A intermediate layer of unknown chemical composition between the fibrillar cellulose wall and the outer capsule layer. Four structural features other than the number of flagella distinguish Carteria from Chlamydomonas: the intermediate layer of the cellular boundary, the chloroplast, the pyrenoid and the eyespot. Only in the Carteria species is the intermediate layer traversed by striations or 12-mμ-wide bars. Striations in the cellulose wall surrounding the flagellar channels also appear in Carteria eugametos and C. crucifera. The chloroplast lamellae of the Carteria species are grouped into discrete stacks of invaginated thylakoids termed pseudograna. The chloroplast lamellae of Chlamydomonas are broad and sheet-like and are also invaginated although less frequently than are the pseudograna of Carteria. The phenomenon of infolding of the chloroplast lamellae is suggested as a general developmental process in the formation of new thylakoids. In Carteria, single thylakoids traverse the pyrenoid and there are 2 rows of granules in the eyespot. Favorable micrographs of the eyespot indicate that the granules may be osmiophilic granules of the chloroplast chemically modified for a photoreceptive function.     

ELECTRON MICROSCOPE OBSERVATIONS ON FROZEN-DRIED CELLS

To explore the problem of artefacts which may be produced during usual fixation, dehydration, and embedding, the authors have examined pancreas, liver, and bone marrow frozen at about -180°C., dried, at -55 to -60°C., embedded in methacrylate, sectioned, and floated on a formol-alcohol mixture. By these treatments the labile structure of living cells can be fixed promptly and embedded in methacrylate avoiding possible artefacts caused by direct exposure to chemical fixatives. Cell structures are ultimately exposed to a fixative when the sections are floated on formol-alcohol, but at this stage artefacts due to chemical fixation are expected to be minimized, as the fixatives act on structures tightly packed in methacrylate polymer. In the central zone of tissue blocks so treated, the cells are severely damaged by ice crystallization but at the periphery of the blocks the cell structure is well preserved. In such peripherally located cells, elements of the endoplasmic reticulum (ER), Palade's granules, homogeneously dense mitochondria, and nuclear envelopes and pores, can be demonstrated without poststaining with OsO₄. The structural organization in the nucleus is distorted by vacuolization. The mitochondrial membranes and cristae, cellular membrane, and the Golgi apparatus, however, are detected only with difficulty. The Golgi region generally appears as a light zone, in which some ambiguous structures are encountered. After staining the sections with OsO₄ or Giemsa solution, an inner mitochondrial structure which resembles the cristae seen in conventional OsO₄-fixed specimens appears, but the limiting membrane is absent. Treatment with OsO₄ or Giemsa solution also renders more distinct the membrane of the ER and Palade's granules but not the Golgi apparatus and cellular membrane. Treatment with ribonuclease results in the disappearance of Palade's granules. On the strength of these observations the authors conclude that OsO₄ fixation gives a satisfactory preservation of such cell structures as the nuclear envelope, endoplasmic reticulum, and Palade's granules, though it may induce slight swelling of these cell components.     

ELECTRON DENSITOMETRY OF STAINED VIRUS PARTICLES

Methods are described for determining the relative mass of particles in electron microscope specimens through the measurement of photographic densities in recorded images. These methods were applied to a quantitative study of the amounts of electron stains that could be associated with the particles of tomato bushy stunt virus (BSV) and tobacco mosaic virus (TMV). In the pH range above 2 where the viruses are stable, the amount of stain absorbed is too small to produce adequate contrast in the electron microscope. Maximum stain absorption was achieved at pH about 1 where with several reagents and combinations of reagents the mass of BSV could be increased to about four times that of the unstained particles. Optimum results were obtained with phosphotungstic acid alone or in combination with Pt, Th, or La ions. Since the pH conditions for high stain absorption are normally destructive, morphology is satisfactorily preserved only when the phosphotungstic acid is applied in concentrations of 10 per cent or greater or when the use of destructive reagents is preceded by a preliminary fixation under mild conditions. Maximum staining of TMV increased the mass of the particles to about two times that of the unstained. Estimates of the mass of heavily stained BSV particles indicate that their density is 3.3 gm./cm.³ The high internal hydration of BSV probably accounts for the greater stain absorption and penetration compared to those of TMV which has very low or zero internal hydration. Anomalous images resulting from the use of electron stains are shown and discussed.     

ELECTRON BEAM THERAPY OF MYCOSIS FUNGOIDES

Ionizing radiation in the form of x-ray therapy is the best modality of treatment available at the present time for single, isolated lesions of mycosis fungoides. However, for generalized mycosis fungoides, generalized x-ray therapy is technically difficult and dangerous. It is now possible to employ electron beam therapy for generalized mycosis fungoides, using energies which confine the dose to the superficial layers of the skin and thus avoid hematopoietic injury. A technique for wide field electron beam therapy has been developed for this purpose which has been effective and well tolerated in limited trials to date.