THE STRUCTURE AND FORMATION OF PROTEIN GRANULES IN THE FAT BODY OF AN INSECT

In the larva of the butterfly Calpodes ethlius, the fat body begins to store protein in the form of granules at about 30 to 35 hours before pupation, at a time when the endocuticle is being resorbed. At least two sorts of granule can be distinguished. The first granules to arise are those within vesicles of the Golgi complex. These may increase in size by incorporating material from microvesicles at their surface and by coalescence with one another. Later, at about 10 hours before pupation, another sort of granule arises by the isolation of regions of the endoplasmic reticulum (ER) within paired membranes derived from Golgi vesicles. Several of these ER isolation bodies coalesce, with fusion of their outer isolating membranes. The ribosomes and membranes may then disappear and the granules become indistinguishable from the protein granules formed from Golgi vesicles, or the ribosomes may remain and be embedded in dense crystalline protein, forming a storage body for both protein and RNA. Mitochondria are isolated within paired membranes in the same way as regions of the ER. The isolated mitochondria also coalesce in a similar manner. When the inner membranes are lost, the structure of a group of isolation bodies is indistinguishable from that of a cytolysome. Isolation within paired membranes, as described here, may be of general importance in segregating regions of massive lysis or massive sequestration.     

黔西北地区农田鼠类群落结构的研究

本文根据黔西北地区农田鼠类的种类组成和数量,将该地区农田鼠类划分为如下４个鼠类群落：Ａ．高山姬鼠＋社鼠群落,Ｂ．黑线姬鼠＋锡金小家鼠＋高山姬鼠群落,Ｃ．黑线姬鼠＋大足鼠＋锡金小家鼠群落和Ｄ．黑线姬鼠＋小家鼠群落。在群落Ｂ中多样性指数（１．４３３）和均匀性指数（０．６８９）最高,最低是群落Ａ,分别为０．８８９和０．４５７;最高的优势度指数（０．５０５）是群落Ａ,而群落Ｂ是０．３０３为最低;群落Ｂ和群落Ｃ之间的相似性指数（０．７５０）最高,群落Ａ和群落Ｄ之间是０．０７５为最低。     

七种啮齿动物视觉器官形态结构的比较研究

用光镜和扫描电镜观察褐家鼠,黑线姬鼠、大仓鼠、棕色田鼠、甘肃Ｆｅｎ鼠、达乌尔黄鼠和岩松鼠的视沉器官形态与构造,对其视网膜的厚度、各核层胸核的层数及大小进行了比较,在扫描电镜下统计了褐家鼠和达乌尔黄鼠和视细胞密度,结果表明,鼠类视觉器官的形态结构与其生活习性相关,即生活习性相似的种类,视器的形态结构也相似;即生活习性差异较大的种类,视器的形态结构差异也较大,同时还发现夜行性鼠视网膜上的核层局部增厚,     

ESTIMATION OF EFFECTIVE EOSINOPOIESIS AND BONE MARROW EOSINOPHIL RESERVE CAPACITY IN NORMAL MAN

The eosinophil reserve capacity of the post-mitotic granulocyte compartment in the bone marrow and the effective eosinopoiesis in three haematologically normal men have been quantified by means of kinetic parameters of [³H]thymidine flash-labelled peripheral blood eosinophils. From (a) the time of the appearance in the blood of labelled eosinophils after the tracer injection, (b) the inflow characteristics of the labelled eosinophils in the blood and (c) the magnitude of the eosinophil granulocyte pool in the venous blood, the effective eosinopoiesis (i.e. the eosinophil turnover) was calculated to range between 0.014 and 0.031 × 10⁹ cells/kg body weight per day (mean 0.22 × 10⁹ cell/kg per day). The post-mitotic eosinophil reserve capacity of the bone marrow ranged from 0.09 to 0.20 × 10⁹ cells/kg body weight (mean 0.14 × 10⁹ cells/kg). The large reserve pool and the high turnover rate may contribute to sudden rises of the peripheral blood oesinophil counts in some cases of eosinophilia.     

ON THE MOLECULAR STRUCTURE OF STARCH GRANULES

It is a problem how to fit the molecules of amylose and amylopectin into the ultrastructural apposition layers of starch granules which have a width of only 0.1μ. Stretched amylose chains with a length up to 1 μ can be ruled out. In addition to the proposal of Miihlethaler, who visualizes folded amylopectin chains, a model with a helical amylose chain is discussed. A helix with six glucose residues per turn would be compatible with the crystal lattice found by Kreger; and the disorder caused by this helix in the hexagonal lattice of the parallel side chains of the amylopectin would account for the low optical anisotropy of the starch granules as compared to the parallel β-polyglucosan chains in cellulose. The proposed model, fitted into the 0.1 μ apposition ring of the starch granule, shows tangential strata with a layer repeat of about 80 A and a radial chain lattice with the fibre period 10.6 A; i.e., it shows a combination of a lamellar and a fibrous structure.     

THE INFLUENCE OF ENVIRONMENT ON THE SHELL STRUCTURE OF STARCH GRANULES

It is well known from light microscope studies of potato starch that the granules formed in a constant environment (of light and temperature) have a ring formation indistinguishable from that of granules formed under field conditions. Electron microscope studies have confirmed that normal potato starch granules have a fine shell structure not usually resolved by the light microscope, and also that shells do not develop in barley granules grown in a constant environment. The paper presented here reports a further study of the dependence of shell formation on environment. Potatoes were grown in a constant environment and starch granules from the newly formed tubers were examined in the light microscope, and in the electron microscope after corrosion by acid. No difference between these granules and normal granules was observed; both wide (light microscope) rings and fine lamellae developed in both granules. Parallel studies were made on wheat starch granules. In this case, shells were not differentiated in granules that developed in a constant environment, but they could be produced at will by imposing a dark period. Thus, shell formation in potato granules must be controlled by an endogenous rhythm, whereas in wheat granules it must be controlled by external environment.     

ELECTRON MICROSCOPE STUDIES OF EPIDERMAL MELANOCYTES, AND THE FINE STRUCTURE OF MELANIN GRANULES

Melanocytes and melanin granules have been studied by electron microscopy in normal human and cat skin, and in hyperplastic human skin lesions. The melanocytes have always been found as free cells within the epidermis,i.e., on the epidermal side of the dermal membrane. Melanocytes frequently rest on the dermal membrane or bulge towards the dermis. In such cases the uninterrupted dermal membrane is uniformly thin and smooth in appearance, in contrast with the regions alongside Malpighian cells, where it appears appreciably thicker and seemingly anchored to the basal cell layer. Two types of melanin granules have been distinguished according to their location in the melanocytes and to morphological characteristics which may only express different stages in the maturation of the granules: (a) light melanin granules in which a structure resembling a fine network is apparent; (b) dense melanin granules which, in osmium-fixed preparations, appear as uniformly dense masses surrounded by a coarsely granular, intensely osmiophilic shell. Treatment of sections of osmium-fixed tissues with potassium permanganate has revealed within the dense granules the existence of an organized framework in the form of a regular, crystalline-like lattice. It is suggested that this basic structure is protein in nature and may include the enzymatic system capable of producing melanin. The existence is reported of fine filaments located in the cytoplasm of melanocytes and morphologically distinct from the tonofilaments found in Malpighian cells.     

ELECTRON-OPAQUE FIBRILS AND GRANULES IN AND BETWEEN THE CELL WALLS OF HIGHER PLANTS

The components of higher-plant cell walls which become electron-opaque after staining with ruthenium-osmium were studied by electron microscopy. A fibrillar material which absorbs this stain is a major wall constituent in the root epidermal cells of carrot and morning glory. In both form and size, these fibrils resemble those found on the surface of suspension-cultured cells of the same species Some cells of woody species show an irregular distribution of electron-opaque material in the cell wall matrix and middle lamella. This material, which has an amorphous appearance with many electron stains, is shown by ruthenium-osmium staining to be an aggregate of discrete granules, 150–220 A in diameter. These observations are not consistent with the concept of the cell wall matrix and middle lamella as an amorphous, uniform gel     

THE DEVELOPMENT OF PIGMENT GRANULES IN THE EYES OF WILD TYPE AND MUTANT DROSOPHILA MELANOGASTER

The eye pigment system in Drosophila melanogaster has been studied with the electron microscope. Details in the development of pigment granules in wild type flies and in three eye color mutants are described. Four different types of pigment granules have been found. Type I granules, which carry ommochrome pigment and occur in both primary and secondary pigment cells of ommatidia, are believed to develop as vesicular secretions by way of the Golgi apparatus. The formation of Type II granules, which are restricted to the secondary pigment cells and contain drosopterin pigments, involves accumulation of 60- to 80-A fibers producing an elliptical granule. Type III granules appear to be empty vesicles, except for small marginal areas of dense material; they are thought to be abnormal entities containing ommochrome pigment. Type IV granules are characteristic of colorless mutants regardless of genotype, and during the course of development they often contain glycogen, ribosomes, and show acid phosphatase activity; for these reasons and because of their bizarre and variable morphology, they are considered to be autophagic vacuoles. The 300-A particles commonly found in pigment cells are identified as glycogen on the basis of their morphology and their sensitivity to salivary digestion.     

THE OCCURRENCE OF TWO MYELIN BASIC PROTEINS IN THE CENTRAL NERVOUS SYSTEM OF RODENTS IN THE SUBORDERS MYOMORPHA AND SCIUROMORPHA

Extracts containing myelin basic proteins have been prepared from CNS tissue of representatives of the three suborders of Rodentia—Myomorpha, Hystricomorpha and Sciuro-morpha. Analyses of the extracts by electrophoresis at low pH showed that one type (L) of myelin basic protein is present in the CNS of all of the rodents examined (rat, mouse, hamster, guinea pig, chinchilla, prairie dog, woodchuck and squirrel). This protein is comparable in molecular size and charge to the CNS myelin basic proteins found in several other mammalian orders. In the CNS of the myomorphs (rat, mouse, hamster) and sciuro-morphs (prairie dog, woodchuck, squirrel) there is an additional type (S) of myelin basic protein of higher cathodic mobility and smaller molecular size. This additional protein is absent from the CNS of the hystricomorphs (guinea pig, chinchilla). These findings indicate that the presence of two myelin basic proteins originally reported in the CNS of the inbred rat is not an anomaly of inbreeding. These data further suggest that the presence of a single L-type CNS myelin basic protein might be a general characteristic of hystricomorphs, while the presence of both L- and S-type CNS myelin basic proteins might be a general characteristic of the myomorphs and sciuromorphs. Analyses by electrophoresis at low pH failed to reveal differences in mobility among either the L-type or the S-type CNS myelin basic proteins of the different species. In contrast, when electrophoresis was carried out cathodically at high pH, species-related differences in mobility were observed among the L- and S-type CNS myelin basic proteins.     

类根瘤对烟草叶片中叶绿体及其淀粉粒含量的影响

目的：探讨类根瘤对烟草叶片中的叶绿体及其淀粉粒含量的影响。方法：无菌培养烟草再生植株,其中一部分经过一定浓度的2,4－D与豇豆根瘤菌512快生型突变株菌液诱导处理,另外一部分为对照。运用常规电镜技术制作叶片厚切片,通过显微观察,对两组烟草叶片细胞中的叶绿体及其淀粉粒含量进行对比分析。结果：结瘤植株叶片细胞内的叶绿体含量虽然与对照之间无明显差异,但叶片栅栏组织和海绵组织细胞内淀粉粒的含量却均较对照减少,其中前者减少更为明显（P＜0.05)。结论：结瘤烟草叶片内光合产物的大量同化可能与类根瘤的形成有关。