The fine structure of the visual system of Lycosa (Araneae: Lycosidae)

Summary Wolf spiders have four pairs of eyes distributed in three rows. The first row which lie in the frontal region of the caparace, just above the chelicera, contains four eyes: a medial pair known as the anterior medial eyes (AM eyes or principal eyes) and two smaller eyes known as the anterior lateral eyes (AL eyes). The second row which is located also in the frontal region of the prosoma consists of two big eyes. These are the posterior median eyes (PM eyes). The third row contains the posterior lateral eyes (PL eyes) which lie in the flanks of the prosomal caparace. The AL, PM and PL eyes are the so-called secondary eyes.The electron microscope shows that the AM eye photoreceptor cells have the rhabdomere in their distal segment, just behind the vitreous body. The rhabdomere consists of closely packed microvilli about 0.5 long exhibiting a uniform diameter of 500 Å. Each rhabdom consists of two rhabdomeres. The distal segment of the photoreceptor has a prismatic shape with four or five faces depending of their location within the retina.The distribution of the rhabdoms follows two different patterns or organization. In the peripheral portion of the retina they lie oriented either parallel or perpendicular to the retinal radii. In this zone most cells have four sides while in the central region five sided cells are predominant. These cells bear microvilli in three of their five faces and the rhabdoms show no preferential mode of orientation. Each retina contains approximately 450 photoreceptors. In the secondary eyes the rhabdoms lie far from the vitreous body behind the level of the cell nuclei. A light reflecting layer or tapetum is present in the three pairs of secondary eyes. The microvilli forming the rhabdomeres of the AL eyes are 0.5 long and 500 Å wide, while the microvilli of the rhabdomeres in the PM and PL eyes are longer and thicker (1.5 long and 550–660 Å wide). In these eyes the rhabdomeres are surrounded by abundant extracellular material. Like in the principal eyes each rhabdom consists of two rhabdomeres.In the AL eyes the photoreceptor cells send out collateral branches which end, without any specialization, in contact with other photoreceptors. Clear fibers running parallely to the tapetum have been found in the secondary eyes. These fibers show specialized regions corresponding to the zones of contact with the photoreceptor cells. These areas are characterized by an increased density of the membranes and groups of vesicles (the vesicles lie within the fibers).The optic nerves consist of photoreceptor axons, glial cells and a fibrous perineural sheath. The AM and AL eyes are connected to the CNS by a single compact optic nerve while in the PM and PL eyes the optic nerve consists of several individual bundles. The total number of optic fibers entering into the brain is about 12.000.A layer of glial cytoplasm covers each photoreceptor axon and the mesaxons appear as double lines which bifurcate frequently.Research sponsored by the Air Force Office of Scientific Research, Office of Aerospace Research, United States Air Force, under AFOSR Grant Nr. 618-64.     

Morphology of horseradish peroxidase (HRP)-injected glial cells in the myenteric plexus of the guinea-pig

Glial cells of the myenteric plexus from guinea pig small intestine were intracellulary filled with horseradish peroxidase (HRP), and histochemically stained. Camera lucida-like drawings of twenty cells were morphologically and morphometrically analyzed. The cells have very small ellipsoid, somata (85±0.7 m equivalent diameter, i.e., about 330 m³ volume), and send up to 20 thin and short processes (less than 26 to about 110 m in length). The morphology of the cells appears to depend on their location within the plexus. Glial cells located within the ganglia are similar to CNS protoplasmic astrocytes; they are star-shaped, and their very short processes are irregularly, branched. In contrast, glial cells within the interganglionic fiber tracts resemble CNS fibrous astrocytes. They extend longer processes that are parallel to the fiber tracts, and show less tendency to branch. We propose that the morphology of enteric glia is determined by the structure of the microenvironment. Both cell types form several flat endfeet at a basal lamina either surrounding blood vessels or at the ganglionic border. Furthermore, the occurrence of holes in the glial cell processes suggests that particular neuronal cell processes may be enwrapped in a specific manner. Fractal analysis of camera lucida-like drawings of the cells showed that the cells have a highly complex surface structure, comparable to that of protoplasmic astrocytes in the brain. These tiny cells may possess a membrane surface area of 2000 m², almost 90% of which are contributed by the cell processes. This geometry may enable an intense exchange of metabolites and ions between neurons, glial cells, and the capillaries and/or environment of enteric ganglia.     

Organisation of the compound eye of a tipulid fly during the day and night

Summary The ultrastructure of the compound eye of the Australian tipulid fly,Ptilogyna spectabilis, is described. The ommatidia are of the acone type. The rhabdom corresponds to the basic dipteran pattern with six outer rhabdomeres from retinular cells 1–6 (R1-6) that surround two tiered central rhabdomeres from R7 and 8. Distally, for about 8 m, the rhabdom is closed. For the remainder, where the rhabdomere of R8 replaces that of R7, the rhabdom is open, and the rhabdomeres lie in a large central ommatidial extracellular space. In the proximal two thirds of the rhabdom, the central space is partitioned by processes from the retinular cells so that the individual rhabdomeres are contained in pockets.At night the rhabdom abuts the cone cells, but during the day it migrates some 20 m proximally and is connected to a narrow (1–2 m) cone cell tract. This tract is surrounded by two primary pigment cells, which occupy a more lateral position at night and thus act like an iris. Pigment in secondary pigment cells also migrates so as to screen orthodromic light above the rhabdom during the day. Between midday and midnight, the rhabdom changes in length and cross-sectional area as a result of asynchrony of the shedding and synthetic phases of photoreceptor membrane turnover. The effects of these daily adaptive changes on photon capture ability are discussed with regard to the sensitivity of the eye.     

Clonal propagation of Callistemon by tissue culture techniques

Callus development in Callistemon viminalis was readily achieved when axillary buds derived from nodal tissue were placed in a medium containing macro- and micro-nutrients, sucrose (0.06 M), inositol (300 M), nicotinic acid (20 M), pyridoxine hydrochloride (3 M), thiamine hydrochloride (2 M), riboflavin (10 M), cytokinins (5 M) and auxins (0.1 M). The presence of benzylaminopurine (5 M) and p-chlorophenoxyacetic acid (0.1 M) promoted the most vigorous callus development and sprout formation. Rooting of nodal material was rare but occurred readily following the transference of sprouts developed on callus to a basal medium containing sucrose and salts. Root initiation was stimulated, however, by the presence of auxins. Chlorophenoxyacetic acid while stimulating root initiation repressed root growth. Indole butyric acid stimulated both root initiation and shoot growth at concentrations of 0.005 to 0.1 M. The treatment of choice for rooting and shoot growth was the addition of indole butyric acid at a concentration of 0.01 M.     

Immunocytochemical study of the hypothalamo-neurohypophysial system

Summary An antiserum cross-reactive against ovine neurophysins-I-II and -III has been used in conjunction with the immunoperoxidase histochemical procedure to localize the cells of the sheep paraventricular (PVN) and supraoptic nuclei (SON). In order to describe the topographical distribution of the SON and PVN a study was made on the serial sections cut (a) transversely from rostral to caudal positions and (b) sagittally from lateral to medial positions of the hypothalamus.The cells of the SON, when examined in the transverse aspect, extended approximately 1900 caudally and when examined in the sagittal plane were contained within a lateral-medial distance of 4830 . In each case the SON cells lay adjacent to the optic chiasm.As sections were cut transversely, the cells of the PVN first appeared in a rostral position defined as 0 and close to the ventral lining of the third ventricle. This general ventral and ventro-lateral distribution of cells maintained up to a caudal distance of approximately 840 . From positions 1260–2310 there was a dramatic dorsal shift of the PVN cells which by this time had also extended laterally. The total rostral-caudal distance occupied by the PVN cells was 3150 . That the lateral-medial distance occupied by the PVN was small (1050 ) was determined on examining the magnocellular nuclei in sagittal section.This work was financed by a grant awarded by the Medical Research Council of New Zealand     

Role of mitochondria in ethanol tolerance of Saccharomyces cerevisiae

The presence of active mitochondria and oxidative metabolism is shown to be essential to maintain low inhibition levels by ethanol of the growth rate (), fermentation rate (v) or respiration rate () of Saccharomyces cerevisiae wild type strain S288C. Cells which have respiratory metabolism show K _i (ethanol inhibition constant) values for , v and , higher (K _i>1 M) than those of petite mutants or grande strains grown in anaerobiosis (K _i=0.7 M). In addition, the relationship between or v and ethanol concentration is linear in cells with respiratory metabolism and exponential in cells lacking respiration. When functional mitochondria are transferred to petite mutants, the resulting strain shows K _i values similar to those of the grande strain and the inhibition of and v by increasing ethanol concentrations becomes linear.     

Endogenous phosphorylation of rat brain synaptosomal plasma membranes in vitro: Some methodological aspects

The time course of endogenous phosphorylation in vitro of total or separted synaptic plasma membrane proteins (SPM) has been correlated with that of hydrolysis of the phosphate donor (ATP) in the incubation medium. The ATP/SPM ratio in the medium was varied. In a low-ratio medium (7.5 M ATP; 2.2 g SPM/l) a complete hydrolysis of ATP occurred almost instantaneously as was measured by the release of free phosphate in and the disappearance of ATP from the medium. As a consequence, only a very short peak of phosphorylation, followed by dephosphorylation was observed. However, when higher ATP/SPM ratios were used (200 M ATP; 0.4 g SPM/l and 500 M ATP; 0.4 g SPM/l), the incorporation of phosphate into SPM proteins was linear for 20 sec, and the maximum level of phosphate incorporation was increased. Similar results were obtained after separation of³²P-labeled phosphoproteins by slab gel electrophoresis. However, analysis of the autoradiographs obtained fromone SPM preparation under different ATP/SPM ratios revealed dependence of phosphorylation of individual protein bands on the conditions used.     

Cellular organization of the embryonic lobster heart

Summary The cellular organization of the embryonic heart of the lobster Homarus americanus was examined in 6-week and 6-month-old animals. The heart wall consists of an outer adventitial layer of fibroblast cells and an inner layer of transversely striated myocardial cells. Present in close association with the myocardium are cardiac neurons, hemocytes and so-called storage cells.Adjacent fibroblasts form fasciae adhaerentes and gap junctions. Adherent junctions also occur between fibroblasts and myocardial cells. Intercalated discs and differentiated membrane regions of close apposition (4 nm) occur between adjacent myocardial cells.The cardiac neurons form a ganglion that contains four small and five large somata. Regions of neuropil are present. Motor axons arising from the cardiac ganglion form neuromuscular synapses with the myocardial cells.The storage cells contain large inclusions and form gap junctions with the myocardial cells. They may supply nutritive material to the developing myocardium.The heart at 6 weeks is about 200 m long and 160 m wide. At 6 months, it is about 300 m long and 250 m wide. The myocardium at 6 weeks is one cell layer thick, and the cells are from 2–6 m in maximum width. At 6 months the myocardium is 2–4 cells thick, and the cells are from 6–12 m in width. Therefore, the myocardium grows by an increase in the number and size of the myocardial cells.     

Morphology and structural organization of spiracles in femaleArgas (Persicargas) walkerae (Acari: Argasidae)

Scanning electron microscopical investigations of fractures and corrosion casts of the spiracles from femaleA. walkerae ticks revealed a four-part structure, consisting of spiracular plate, ostium and macula forming the external closure, followed by the subostial space and the vestibulum of regulable volume, as well as the atrial chamber as the innermost part from which the main tracheal trunks originate. On the average, the spiracular plate was 158 m long and 188 m at the broadest width. It consisted of a thin, highly perforated external and a thick internal layer, which enclosed the interpedicellar space with numerous stout pedicels. In its posterior region, the spiracular plate was covered by the macula, which was up to 80 m in length and 110 m in width. The interpedicellar cavity opened into the subostial space measuring 95.5 m in length and 159.6m in width, which proceeded into the 112-m long vestibulum. The roof of the vestibulum was flexible and could be everted and inverted. Inverted, the roof formed a quadratic bulge with numerous deep cuticular folds, which confined the lumen of the vestibulum either partially or completely. In corrosion casts, the roof was everted to a length of up to 89.3 m. In the posterior part of the vestibulum, as well as in the initial fourth of the artrial chamber, numerous anvil-, cone-or drop-like cuticular projections were arranged in wedge-like fashion. The atrial chamber was almost spherical with a diameter of 138.4 m. Five main tracheal trunks of different luminal diameter as well as numerous channels opened into the atrial chamber.     

Copper but not iron limitation increases astaxanthin production by Phaffia rhodozyma in a chemically defined medium

The influence of copper (0–32 M) and iron (0–108 M) on growth and astaxanthin production by Phaffia rhodozyma was studied. Copper below 3.2 M increased the astaxanthin content of the cells (from 220 to 287 g g^–1) but at the expense of a slightly decreased growth (from 11.3 to 10.2 mg ml^–1). In contrast, iron below 1 M decreased both the growth and astaxanthin content of the cells. Using copper limitation instead of toxic respiratory inhibitors to improve astaxanthin production has obvious advantages from the product quality, environmental and process operation points of view.     

Saccharomyces cerevisiae 2-mum DNA. An analysis of the monomer and its multimers by electron microscopy.

Summary The non-tandem inverted duplication in the 2-m DNA of Saccharomyces cerevisiae has a length of 0.19 m and is located asymmetrically along the molecule. The majority of the dumb-bell structures that are formed upon denaturation and selfannealing of the 2-m monomer consists of the renatured inverted duplication sequences as double stranded stem and two single stranded loops of 0.67 m±0.06 m (S-loop) and 0.86 m±0.05 m (L-loop) length. Two additional size classes which comprised 5–10% of the measured molecules had contour lengths of around 1.7 m and 2.1 m. The smaller dumb-bells contained two S-loops and the larger dumb-bells contained two L-loops as was shown by heteroduplex mapping with an HindIII fragment from the L-loop. Two models which assume illegitimate or site specific recombination, are presented to explain the generation of double S-loop and double L-loop molecules. At least part of the 4-m and 6- circular molecules present in the yeast supercoiled DNA fraction are shown to be dimers and trimers of 2-m monomers, but often with inverted loop segments most probably due to intramolecular recombination between sequences of the inverted duplication.2-m DNA is used to indicate the supercoiled DNA fraction although in our measurements the average monomeric length is 1.9 mPart of this work has been presented at the Conference: The Genetics and Biogenesis of Chloroplasts and Mitochondria, Munich, August, 1976     

Ultrastructure of Sporothrix schenckii treated with iodine-potassium iodide solution

The ultrastructural changes produced by iodine-potassium iodide solution on yeast cells of Sporothrix schenckii were investigated by transmission electron microscopy in order to clarify the mechanism of oral potassium iodide therapy for sporotrichosis. Yeast cells were dipped with solutions containing various concentrations of iodine. The rate of germination decreased markedly between the range of iodine concentrations from 0.63 g/ml to 5.0 g/ml. No significant ultrastructural changes were seen at the concentration of the iodine of 1.25 g/ml (80% germination) or less. In the concentration of 2.5 g/ml (50% germination), normal cells and degenerated cells coexisted. When the cells were treated with 5.0 g of iodine per ml (0% germination) or more, their interior structures were completely destroyed. It is assumed that iodine treatment of the organism causes rapid destruction in the whole cell.     

Ultrastructure of serotonin-containing cells in the pineal organ of Lampetra planeri (Petromyzontidae)

Summary The ultrastructure of the cells containing residual bodies (Collin, 1969) was investigated in the pineal organ of Lampetra planeri. These cells are characterized by their indoleamine metabolism (Meiniel, 1978; Meiniel and Hartwig, 1980). Morphologically, they belong mainly to two types: (1) a photoreceptor cell type, and (2) a pinealocyte cell type. The first type is present in the pineal sensory epithelium and in the atrium, while the second is observed in the deep part of the atrium. Intermediate cell types are rare. All these cells are characterized by the presence of voluminous dense bodies, the 5-HT-storing structures, in their cytoplasm.The elongated cone-type photoreceptor cells show a segmental organization and well-developed outer segments consisting of short disks (2–3 m), while their basal pedicles form synapses with the dendritic processes of neurons. The pinealocytes are spherical or oval in shape, their receptor poles being regressed to cilia of the 9+0 type. In these cells, no synaptic ribbons have to date been observed. In both cell types a Golgi apparatus is present producing dense granules 130 nm in diameter and a polymorphous dense material.The photoreceptor cells most probably respond to light and transmit a sensory (i.e., nervous) message. In addition, they produce and metabolize indoleamines, probably including, melatonin (Meiniel, 1978; Meiniel and Hartwig, 1980). The pinealocytes, in spite of their loss of direct photosensitivity, retain their capacity to metabolize indoleamines (Meiniel, 1978; Meiniel and Hartwig, 1980).The presence, in the same pineal organ, of another photoreceptor cell type (cf. Collin, 1969–1971) differing morphologically as well as biochemically (no detectable indoleamine metabolism) from the photoreceptor cell type described in the present investigation, points to the existence of two different sensory cell lines: (1) a pure photoreceptor line, and (2) a photoneuroendocrine line. The phylogenetic evolution of these two cell lines is discussed in terms of functional analogy.     

Photosynthesis of isolated chloroplasts and protoplasts under osmotic stress

1. Isolated intact spinach chloroplasts respond to changes of the sorbitol concentration of the suspending medium as near-perfect osmometers within a large range of osmotic potentials. Under isotonic conditions (=9–10 bar), their average osmotic volume is 24 m³ and the total volume 36 m³. The osmotic volume can be increased to 63 m³ by lowering the sorbitol concentration until a critical osmotic potential of =4 bar is reached. Below that value chloroplasts rupture. Between 10 bar and 4 bar, volume changes are reversible. 2. Increasing the chloroplast volume above 24 m³ causes inhibition of photosynthesis, with 50% inhibition occurring at an osmotic potential of =5–6 bar. This corresponds to an osmotic volume of 45–55 m³. Depending on the duration of hypotonic treatment, inhibition of photosynthesis is more or less reversible. 3. Between 4 and 10 bar, the chloroplast envelope exhibits a very low permeability for ferricyanide, many metabolites, and soluble stroma proteins. 4. Electron transport is not inhibited by swelling of chloroplasts. Also, the ATP/ADP-ratio remains unchanged. 5. The solute concentration in the chloroplasts appears to be optimal for photosynthesis at 10 bar. Increasing the chloroplast volume causes inhibition of photosynthesis by dilution effects.     

Karyometry of nuclei in liver cells

Summary In untreated adult male albino rats nuclear volume and the percentage of binucleate cells were determined in the first layer of hepatocytes adjacent to hepatic venous branches of varying diameters (<40 m, 40 m–80 m, 80 m–120m, 120 m–160 m, >160 m), and in the third and fourth layer of hepatocytes in the remainder of the perivenous parenchyma. In the first layer of hepatocytes adjacent to the vascular structures means of nuclear volume are significantly lower and percentage of binucleate cells significantly higher than in the cells of the remainder of the perivenous parenchyma. Within each area measured distribution curves of nuclear volume classes were homogeneous but showed heterogeneity in comparison with each other. The morphometric data presented in this study strongly support the opinion of the heterogeneity of liver cells in the perivenous zone, as previously postulated on the basis of histochemical investigations.Supported by the Deutsche Forschungsgemeinschaft (Hi 318/2-1)     

Observations on the cytolemma of the olfactory receptor cell in the newt

Summary The fine structure of the cytolemma of olfactory receptor cells in the newt was studied by the freeze-fracture replica method. Two kinds of receptor cells were recognized, namely ciliated cells (ciliary type) and non-ciliated cells (microvilli type). The cytolemma of olfactory knobs as well as their processes from both types of receptor cells showed an abundance of large membrane particles 80110Å in diameter. The large square aggregation of membrane particles, 0.1×0.1 m to 0.2×0.3 m in size, consisting of 50100 cuboidal subunits, were found in the cytolemma of the dendrite. A structural model of aggregation is presented. The soma of the receptor cell revealed large pitted membrane particles about 140Å in diameter. These particles are possibly the morphologic counterpart to ionophores which have been proposed by electrophysiological studies.     

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. (Apicomplexa: Eimeriidae) from the black-capped bulbul,Pycnonotus xanthopygos

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. are described from the black-capped bulbul Pycnonotus xanthopygos from Lincoln Park Zoo, Chicago, Illinois. The bird came from southwestern Africa seven years earlier. I. ernsti oocysts are ellipsoidal to bluntly ovoid, 28–38 × 23–31m (mean 34 × 28 m) and have a single-layered oocyst wall. Micropyle, oocyst residuum and polar granules are absent. Sporocysts are elongate ovoid, 24–30 × 11–16 m (mean 27×13 m). Stieda and substiedal bodies and sporocyst residuum are present. I. blagburni oocysts are spherical to subspherical. 21–28 × 19–26 m (mean 25 × 23 m) and have a single oocyst wall. Sporocysts are ovoid and 17–23 × 10–13 m (mean 20 × 12 m). Stieda and substiedal bodies and sporocyst residuum are present.     

The neurotoxic effects of methylenedioxymethamphetamine (MDMA) and its metabolites on rat brain spheroids in culture

Rat whole-brain spheroids were used to assess the intrinsic neurotoxicity of methylenedioxymethamphetamine (MDMA, Ecstasy) and two of its metabolites, dihydroxymethamphetamine (DHMA) and 6-hydroxy-MDMA (6-OH MDMA). Exposure of brain spheroids to MDMA or the metabolite 6-OH MDMA (up to 500 mol/L) for 5 days in culture did not alter intracellular levels of glutathione (GSH), glial fibrillary acidic protein (GFAP) or serotonin (5-HT). In contrast, exposure to the metabolite DHMA, which can deplete intracellular thiols, significantly increased GSH levels (up to 170% of control) following exposure to 50 and 100 mol/L DHMA. There was also a significant reduction in the levels of glial fibrillary acidic protein (GFAP) and GSH by DHMA at the highest concentration tested (500 mol/L) but there was no effect on 5HT. This may constitute a sublethal neurotoxic compensatory response to DHMA in an attempt to replenish depleted intraneural GSH levels following metabolite exposure. Rat whole-brain spheroids may thus be a useful in vitro model to delineate mechanisms and effects of this class of neurotoxin.     

Stimulation of ethylene production by catecholamines and phenylethylamine in potato cell suspension cultures

The catecholamines (50 M dopamine, 50 M norepinephrine and 100 M epinephrine) and phenylethylamine (200 M) were found to stimulate ethylene production in potato suspension cultures. When 100 M amino-oxyacetic acid was added together with epinephrine, ethylene release returned to control levels. The endogenous 1-aminocyclopropane-1-carboxylic acid levels were increased in parallel with the release of ethylene, suggesting that the observed effect probably occurs via regulation of aCC synthase. Our results suggest that there is a link between these naturally occurring monoamines and ethylene in plants.Abbreviations AOA amino-oxyacetic acid - ACC 1-aminocyclopropane-1-carboxylic acid - DA dopamine - NE norepinephrine - E epinephrine - CA catecholamines - PEA phenylethylamine     

Intestinal microflora in the deep-sea isopodBathynomus giganteus

Observations with the scanning electron microscope showed that the deep-sea isopodBathynomus giganteus harbors a dense microflora within the digestive tract. The gut microflora is composed of a diversity of microorganisms, including an unusually large bacterial morphotype that predominates almost exclusively in the anterior end of the hindgut. The majority of these large bacteria measured 1.9 m×8.5 m and many reached a size of 2.0 m×10.0 m.