MICROCYLINDERS WITHIN MITOCHONDRIAL CRISTAE IN THE RAT PINEALOCYTE

A minute cylindrical structure with a dense core, designated as "microcylinder," has been observed within enlarged spaces of mitochondrial cristae in pinealocytes of some adult rats (osmium tetroxide fixed, methacrylate embedded). The microcylinders are 270 to 330 A in diameter and of indeterminate length. Their wall is found to be made up of slender filamentous subunits, probably 6 in number, and surrounds a central filament. The microcylinders are arranged parallel to one another, forming monolayered or, more frequently, multilayered aggregates. Their number within a crista varies considerably. Packets of microcylinders may be seen located in the outer mitochondrial chamber, but are never found in the mitochondrial matrix. They have been observed neither in other cell types of the pineal gland nor in neurons, ependymal, and glial cells of the nearby epithalamic tissue. The origin and nature of the microcylinders are unknown. Glycogen-like particles have been encountered, though very infrequently, accompanying bundles of microcylinders within mitochondrial cristae.     

OSMIUM STAINING OF ENDOPLASMIC RETICULUM AND MITOCHONDRIA IN THE RAT ADRENAL CORTEX

The zona fasciculata of the rat adrenal cortex synthesizes and secretes glucocorticoids. As observed after aldehyde fixation, the cells in this zone contain an extensive endoplasmic reticulum (ER), a small Golgi apparatus, a moderate number of lipid droplets, and abundant mitochondria with tubulovesicular cristae. Numerous areas within the endoplasmic reticulum and mitochondrial cristae appear clear. In addition, a small percentage of mitochondria encompasses large, clear areas. After immersion of finely minced adrenal cortex in unbuffered 2% OsO₄ (40–48 hr at 40°C), deposits of osmium are seen within the Golgi apparatus, the entirety of the ER, and occasionally within mitochondria. In some mitochondria, the deposits are within cristae; in others, within vacuoles; in still others, in both cristae and vacuoles. These localizations correspond best to the clear areas found in aldehyde-fixed tissue. Osmium is not deposited in lipid droplets, in bar-containing inclusions, in mitochondrial matrix inclusions, or in the peripheral, outer mitochondrial spaces. Addition of zinc-iodide to OsO₄ increases the amount of Golgi apparatus and mitochondrial staining. Adrenocorticotropin (ACTH) does not affect the localization of deposits; hypophysectomy decreases mitochondrial staining. This study (a) emphasizes the necessity for electron microscopic confirmation of osmium localization when this technique is used as a Golgi apparatus stain; and (b) suggests that the ER-staining pattern may be consistent in cells actively synthesizing steroids or steroid-like compounds.     

ENZYME-STRUCTURE RELATIONSHIPS IN THE ENDOPLASMIC RETICULUM OF RAT LIVER : A Morphological and Biochemical Study

Subfractionation of preparations of rat liver microsomes with a suitable concentration of sodium deoxycholate has resulted in the isolation of a membrane fraction consisting of smooth surfaced vesicles virtually free of ribonucleoprotein particles. The membrane fraction is rich in phospholipids, and contains the microsomal NADH-cytochrome c reductase, NADH diaphorase, glucose-6-phosphatase, and ATPase in a concentrated form. The NADPH-cytochrome c reductase, a NADPH (or pyridine nucleotide unspecific) diaphorase, and cytochrome b₅ are recovered in the clear supernatant fraction. The ribonucleoprotein particles are devoid of, or relatively poor in, the enzyme activities mentioned. Those enzymes which are bound to the membranes vary in activity according to the structural state of the microsomes, whereas those which appear in the soluble fraction are stable. From these findings the conclusion is reached that certain enzymes of the endoplasmic reticulum are tightly bound to the membranes, whereas others either are loosely bound or are present in a soluble form within the lumina of the system. Some implications of these results as to the enzymic organization of the endoplasmic reticulum are discussed.     

REVERSAL BY ADENINE OF THE ETHIONINE-INDUCED LIPID ACCUMULATION IN THE ENDOPLASMIC RETICULUM OF THE RAT LIVER : A Preliminary Report

Within 3.5 to 4 hours after thionine administration, numerous small osmiophilic bodies, liposomes, appear in the endoplasmic reticulum of the liver cells. By fusion, the liposomes lead to the formation of larger collections of fat, giant liposomes. Adenine administration to ethionine-treated rats removes the liposomes from the hepatocytes and causes the transitory appearance of osmiophilic droplets in the sinusoidal space of Disse. The characteristic disaggregation of hepatic polysomes seen in the liver after ethionine administration is corrected by the injection of adenine.     

大鼠粒细胞内质网的电镜细胞化学反应

本实验用电镜细胞化学方法观察了大鼠骨髓粒细胞发育过程中内质网的髓过氧化物酶(MPO)反应和葡萄糖-6-磷酸酶(G-6-P)反??应。结果表明:MPO除定位于内质网、核膜,还出现在高尔基体和颗粒,它是粒细胞内质网的合成产物。G-6-P只在内质网、核膜中出现,它是内质网膜的结构成分。MPO反应的超微结构定位随粒细胞发育而变,利用这种变化作标志可以划分不同发育阶段的粒细胞;G-6-P反应定位不随发育而变,但反应强度与内质网的多寡、功能状态相对应。实验还表明核膜与内质网在结构、功能上的一致性;尤其在成熟粒细胞内质网很少的情况下,核膜可能代替了内质网的功能。     

DISTRIBUTION OF PEROXISOMES (MICROBODIES) IN THE NEPHRON OF THE RAT : A Cytochemical Study

The distribution of peroxisomes (microbodies) in the rat nephron was studied cytochemically, using glutaraldehyde- or formaldehyde-fixed tissue, by means of α-hydroxy acid oxidase activity in light microscopy or oxidation of 3,3'-diaminobenzidine (DAB) at pH 9 in both light and electron microscopy.The two cytochemical methods show peroxisomes to be nearly sperical particles found only in cells of the proximal convoluted tubule. Lysosomes were identified in the same or parallel sections, with β-glycerophosphate or 5'-cytidylic acid as substrate. They are found in all cells of the nephron. These cytochemical methods visualize the two organelles for light microscopy; they also permit unequivocal differentiation of all kidney peroxisomes from lysosomes in electron micrographs. Peroxisomes are larger and more reactive in the cells of the pars descendens (P₃ segment) of the proximal convolution, located in the outer medulla and medullary rays, than in the cells of the pars convoluta (P₁ and P₂ segments), situated in the cortex. In contrast, lysosomes are much smaller in the P₃ segment and larger and more reactive in the P₁ and P₂ segments. In all cells of the proximal convolution, peroxisomes tend to be concentrated nearer the base of the cells than do lysosomes. Mitochondria in P₃ cells also show low levels of DAB oxidation at pH 6, in contrast to those in P₁ and P₂ cells. The possibility is discussed that P₃ cells possess an extramitochondrial means of oxidation in which peroxisome oxidases play an important role.     

荸荠中一种生物碱（MTC）的鉴定和绝对构型的确定

本文介绍了荸荠中存在的一种生物碱(MTC)的提取、分离和鉴定,并用化学合成和~1HNMR NOESY谱数据确定其绝对构型。     

慢性缺氧大鼠心肌肌浆网功能及其钙泵基因表达的动态变化

将实验大鼠放置模拟５０００ｍ海拔高度低压舱内１、２和４周。结果表明：与对照组比较,１,２和４周组动物的心肌重量分别增加１５％,１８％和５７％;心肌ＳＲＣａ２＋摄取分别降低３３％,３８％和５３％;心肌ＳＲＣａ２＋ＡＴＰａｓｅ活性分别降低５４％,６０％和７４％;钙泵ｍＲＮＡ含量（基因表达分别降低１４％,４６％和６８％。这些结果提示,缺氧导致的ＳＲ钙泵功能降低可能是心肌功能受损的重要生化基础之一,而钙泵数目减少可能是钙泵功能降低的分子生物学机制。     

A POSSIBLE MECHANISM FOR THE MORPHOGENESIS OF LAMELLAR SYSTEMS IN PLANT CELLS

A mechanism for the formation of lamellar systems in the plant cell has been proposed as a result of electron microscope observations of young and mature cells of Nitella cristata and the plastids of Zea mays in normal plants, developing plants, and certain mutant types. The results are compatible with the concept that lamellar structures arise by the fusion or coalescence of small vesicular elements, giving rise initially to closed double membrane Structures (cisternae). In the chloroplasts of Zea, the cisternae subsequently undergo structural transformations to give rise to a compound layer structure already described for the individual chloroplast lamellae. During normal development, the minute vesicles in the young chloroplast are aggregated into one or more dense granular bodies (prolamellar bodies) which often appear crystalline. Lamellae grow out from these bodies. In fully etiolated leaves lamellae are absent and the prolamellar bodies become quite large, presumably because of inhibition of the fusion step which appears to require chlorophyll. Lamellae develop rapidly on exposure of the plant to light, and subsequent development closely parallels that seen under normal conditions. The plastids of white and very pale green mutants of Zea similarly lack lamellae and contain only vesicular elements. A specialized peripheral zone immediately below the double limiting membrane in Zea chloroplasts appears to be responsible for the production of vesicles. These may be immediately converted to lamellae under normal conditions, but accumulate to form a prolamellar body if lamellar formation is prevented, as in the case of etiolation and chlorophyll-deficient mutation, or when the rate of lamellar formation is slower than that of the production of precursor material (as appears to be the case in the early stages of normal development).     

THE SARCOPLASMIC RETICULUM IN MUSCLE CELLS OF AMBLYSTOMA LARVAE

Electron microscopy of thin sections of muscle fibers in myotomes of Amblystoma larvae has revealed the presence of a complex, membrane-limited system of canaliculi and vesicles which form a lace-like reticulum around and among the myofibrils. This seems to correspond to the sarcoplasmic reticulum of the earlier light microscopists and the endoplasmic reticulum of other cell types. The elements constituting the reticulum are disposed in a pattern which bears a constant relation to the bands of the adjacent myofibrils and is therefore repeated in each sarcomere. At the H band the system is transversely continuous but not so at other levels. Longitudinally continuity is interrupted at the Z bands where large vesicles belonging to adjacent sarcomere segments of the system face off on opposite sides of the band. The opposing faces of these vesicles are flat and separated by a space of more or less constant width, in which are located small, finger-shaped vesicles. In view of these and other close structural relationships with the myofibrils it seems appropriate to assign to the system a role in the conduction of the excitatory impulse.     

乳头体在大鼠学习记忆活动中的作用的初步探讨

在64只大鼠上观察了电损毁乳头体对动物不同条件反应和有关行为的影响。结果表明,损毁后动物的条件性防御反应的建立未受影响,但其条件性防御反应的分化和消退,以及较复杂的条件性饮水反应的建立却受到明显障碍。这些大鼠在进行条件性饮水反应的过程中对实验环境和条件信号活动明显增多。基于上述结果提示,乳头体在条件反应过程中起抑制作用,在建立这种反应的早期能影响情绪、注意和感觉信息的整合。     

THE EFFECT OF LOW TEMPERATURE ON THE DEVELOPMENT OF THE LAMELLAR SYSTEM IN CHLOROPLASTS

The influence of low temperature (3°C.) on development of submicroscopic structure in plastids of Zea m. leaves was studied. Leaves from 8-day old etiolated plants, with plastids showing the prolamellar body and few lamellae, were floated for 1 day on tap water both in the dark and in the light, at 26°C and at 3°C. The structures remain unchanged in the dark, independent of temperature. Whereas in the light at 26°C., normal development of parallel compound lamellae and formation of grana occurs, in light at 3°C. ring structures are formed. Under the latter conditions protochlorophyll is converted to chlorophyll, although the in situ absorption maximum is different from the one for chlorophyll in plants grown in light at 26°C. When leaves were transferred from light at 3°C. to light at 26°C., ring structures in the plastids disappeared and normal development occurred. The possibility is discussed that development of parallel-arranged compound lamellae is due both to photochemical and synthetic processes, involving not only accumulation of chlorophyll, but also synthesis of other compounds.     

A LARGE SCALE QUASI-CRYSTALLINE LAMELLAR LATTICE IN CHLOROPLASTS OF THE GREEN ALGA ZYGNEMA

A quasi-crystalline lamellar lattice was observed in chloroplasts of the filamentous green alga Zygnema. The lattice does not appear in the cells until cultures are at the end of the log phase of growth. Pseudograna are also present and become more numerous towards the middle of the log phase. The three-dimensional lattice superficially resembles the configuration of cubic prolamellar bodies but is about 10 times larger and is entirely different in internal structure. The lattice is composed of one or two appressed thylakoids in a stroma matrix which is bounded on each side by a single thylakoid membrane. This multilayered sandwich of membranes and matrix occupies a position equivalent to the single membrane of a cubic prolamellar body.     

TUBULES IN DILATED CISTERNAE OF ENDOPLASMIC RETICULUM OF THLASPI ARVENSE (CRUCIFERAE)

Tubular inclusions in dilated cisternae of endoplasmic reticulum (ER) were found in healthy and virus diseased pennycress (Thlaspi arvense L., Cruciferae). The dilated cisternae were encountered more often in virus-infected cells than in comparable cells from healthy control plants. Dilated ER cisternae were found in vascular parenchyma cells and were shown to be interconnected. The tubules measured 30 nm in diam and cisternae that contain them may be more than 10 μm in length.     

AN ELECTRON MICROSCOPE STUDY OF MATURE AND DIFFERENTIATING PANETH CELLS IN THE RAT, ESPECIALLY OF THEIR ENDOPLASMIC RETICULUM AND LYSOSOMES

In an electron microsope study, the morphology of mature Paneth cells from the small intestine of adult rats is compared with that of differentiating Paneth cells from young rats 2 to 4 weeks old. All mature cells exhibit a marked polarity similar to that of other exocrine gland cells and contain a well developed endoplasmic reticulum, an elaborate Golgi complex, and numerous large secretory granules; they also possess an abundance of lysosomes. The most conspicuous occurrence in the process of differentiation is the development of the endoplasmic reticulum. The most immature Paneth cells possess an endoplasmic reticulum of the vesicular type, which, during maturation, is replaced by the characteristic lamellated ergastoplasm of the mature cell. At a certain stage of differentiation the cavities of the developing cisternae show numerous communications with the perinuclear space, suggesting an outgrowth of the ergastoplasm from the nuclear envelope. Furthermore, the cavities and the perinuclear space at this particular stage contain a material which shows a remarkable intrinsic periodicity. An identical periodicity was exhibited by material contained in Golgi cisternae and secretory granules. Lysosomes are also present in the differentiating cells.