Golgi Dictyosomes Research Articles

ISOLATION OF β-GLUCAN SYNTHETASE PARTICLES FROM PLANT CELLS AND IDENTIFICATION WITH GOLGI MEMBRANES

A variety of particle-bound synthetases that use sugar nucleotides as glycosyl donors for the formation of polysaccharides similar to those of the cell wall have been demonstrated in mung beans and other plant tissues,(1) but the particles in question have not been previously identified.(2, 3) The polysaccharide synthetase particles from peas that form mainly beta-1,4-glucan from UDPG and GDPG have now been separated from other cell particles by combinations of velocity and isopycnic density gradient centrifugation. The particles have an effective density of about 1.15 gm cm(-3), exhibit latent nucleoside diphosphatase activity upon IDP, UDP, GDP, and to a lesser extent upon ADP, and also possess acid phosphatase and weak ATPase activity. The isolated synthetase particles consist of somewhat condensed Golgi dictyosomes and free dictyosomal membranes bearing vesicles. It is concluded that the synthetase particles are Golgi membranes. The nucleoside diphosphatase activity of these particles may represent inactivated polysaccharide synthetase.

ULTRASTRUCTURE OF THE HYPHAE AND HAUSTORIA OF PHYTOPHTHORA INFESTANS AND HYPHAE OF P. PARASITICA

The ultrastructure of the mycelium of both Phytophthora infestans and P. parasitica is consistent with that reported for other Oomycetes. A distinct plasmalemma, porate nuclei, tubular endoplasmic reticulum, mitochondria with tubular cristae, Golgi dictyosomes, and lipid bodies are present within the protoplast. The haustoria produced by P. infestans in the leaves of susceptible potato varieties consist of an expanded haustorial head surrounded by a fungus wall which is continuous with the wall of the intercellular mycelium. The haustorium lacks the long narrow stalk or neck often associated with this organ, and there is considerable cytoplasmic continuity between the haustorium and the intercellular mycelium. All P. infestans haustoria observed were anucleate and generally contained only a few mitochondria and sparse endoplasmic reticulum. The haustorium is enclosed in an encapsulation surrounded by a membrane which is continuous with the host plasmalemma. There is no evidence, around any portion of the haustorium, of a sheath originating from the cell wall of the host. A survey of the current literature on the ultrastructure of the Eumycotinia shows that the parasitic fungi exhibit no unique cytoplasmic features when compared with non-parasitic fungi, and the ultrastructure of the haustoria-producing facultative saprophyte is similar to that of the obligate parasites.

Cytochemistry of Protozoa, with Particular Reference to the Golgi Apparatus and the Mitochondria

This chapter describes cytochemistry of protozoa with emphasis on the Golgi apparatus and the mitochondria. The vast studies on cytoplasmic inclusions of the subclass Phytomastigina pertain to the order Euglenoidina. In addition to the chloroplasts, stigma, and associated structures the euglenoids have been considered to have four types of cytoplasmic inclusions: (1) mitochondria or chondriome, (2) vacuome, (3) Golgi material, and (4) mucous bodies. The Golgi material found in the various classes of protozoa has been shown to be homologous with the Golgi dictyosomes of all metazoan cells except the neurons of vertebrates. In a large number of species belonging to all the five classes of the protozoa, studies with the electron microscope have made abundantly clear that the Golgi material exists in the form of typical dictyosomes, exactly similar to those of the metazoan cells. Each dictyosome consists of very flat saccules, the walls of which enclose a slit-shaped area and appear as very conspicuous membranes. It is the walls of these saccules that show osmiophily whereas the contents of the saccules always appear brighter.

CYTOLOGY OF SPERMATOGENESIS IN THE HONEY‐BEE, APIS INDICA (F.)

SYNOPSISThe spermatogenesis of the honey‐bee, Apia indica (F.), has been worked out with special reference to the abortive meiosis and the role of cytoplasmic organelles.The haploid number of sixteen chromosomes in the parthenogenetic males remains constant through‐out spermatogenesis.Meiosis I is abortive, resulting in the formation of a definite non‐nucleated cytoplasmic bud containing some extra‐nuclear spindle fibres and the cytoplasmic body.The significance of an extra‐and an intra‐nuclear spindle in relation to the abortive meiosis is discussed.Meiosis II is normal so far as the nuclear division is concerned. The cytoplasm, however, divides unequally, resulting in the formation of a normal spermatid and a diminutive non‐functional spermatid body.The mitochondria are in the form of filaments and granules in the early stages. During meiosis I they assume a characteristic “blebbed” appearance. In the spermatid they fuse to form a typical mitochondrial nebenkern, which ultimately gives rise to the mitochondrial sheath around the axial filament of the sperm.A number of typical duplex spheroids (“Golgi dictyosomes”), each with a lipid sheath enclosing a non‐lipid medulla, are present in the spermatocytes. In the spermatid these duplex spheroids fuse to form a typical single acroblast which is sloughed off after depositing a pro‐acrosome at the nuclear membrane. The pro‐acrosome condenses to form the acrosome of the ripe sperm.

Cytochemical evidence of the origin of lipid bodies (so-called Golgi bodies) from mitochondria.

SINCE Hirsch's1 theory of the Golgi presubstance, according to which there exist homogeneous granular mass as a precursor of the ‘Golgi’ system, there has been very little attempt to investigate the origin of these inclusions in the cell. Nath and Chopra2 reported the origin of ‘Golgi dictyosomes’ from mitochondria in the spermatocytes of the slug, Anadenus altivagus. However, such a conclusion was arrived at on the basis of morphological study inasmuch as the ‘Golgi dictyosomes’ disappear at the metaphase and anaphase stages of meiosis I and II, probably merging into the mitochondria ; they again appear in the respective telophase stages by the alignment of lipid granules, which seemed to take their origin from the mitochondria. These observations were later confirmed by Nath and Gupta3 in the living spermatocytes of Anadenus and Euaustenia under phase-contrast microscopy.

The mitochondria during the differentiation and growth of the nerve cells of Schistocerca gregaria.

SYNOPSISThe mitochondria occur as granules and short rods throughout the various developmental stages of the locust. No filamentous mitochondria could be detected. In early germ‐band cells the mitochondria exist as small granules and very short rods scattered in the cytoplasm. They are shared out between the dividing neuroblasts, and remain as such in the early ganglion cells and in the first four nymphal instars.The nerve cells of the fifth instar nymph (as well as the large neurones of the fourth instar nymph) and adult locust contain, besides the normal mitochondria, a number of swollen bodies which we consider as metamorphosed mitochondria. The latter type, in old neurones, decreases in number and moves towards the cell periphery.In the senile condition the metamorphosed mitochondria are no longer visible.The pictures of mitochondria in living unstained or vitally stained preparations do not differ from those of fixed and stained materials.The mitochondria are not responsible for the production of the Golgi dictyosomes as an effect of fixation and metallic impregnation, as is shown from the following: In the early germ‐band cells, a single osmiophilic globule (Golgi body) is found, whereas the mitochondria appear in the form of many small granules and very short rods scattered in the cytoplasm. In the early developmental stages, the mitochondria are evenly scattered in the cytoplasm, whereas the Golgi dictyosomes are polarized. The mitochondria and dictyosomes can be demonstrated side by side in the same cell.

Golgi Bodies in the Spermatogenesis of Pulmonate Gastropods

Nath and Chopra have recently completed investigations on the spermatogenesis of the Simla slug, Anadenus altivagus (Theobald). This material has unexpectedly turned out to be an excellent material for the demonstration of (1) the origin of Golgi dictyosomes from the mitochondrial granules by alignment, and (2) the secretion of the acrosome by the dictyosomes. These workers have also examined the living material under the phase-contrast microscope.