Factors influencing shoot regeneration from cotyledonary explants ofCucumis melo

Cotyledonary explants of 4-day-oldCucumis melo cv. Hale's Best Jumbo in vitro seedlings showed maximum initiation of shoot buds when cultured onto a revised Murashige & Skoog medium supplemented with 5 M indole-3-acetic acid and 5 M benzylaminopurine and cultured at 25–29°C under low light intensity (5–30 mol m^-2 s^-1). Subculture of the shoot buds onto the same medium without auxin and supplemented with 3 M benzylaminopurine caused the development of shoots from 30% of the buds. The presence of abscisic acid significantly increased the number of explants producing shoot buds. Bud initiation was affected by genotype, seedling age, light intensity, and temperature. Addition of gibberellic acid, thidiazuron or silver nitrate to regeneration medium did not improve either bud initiation or shoot regeneration.     

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.     

Three-dimensional architecture of the tubular endocytic apparatus and paramembranous networks of the endoplasmic reticulum in the rat visceral yolk-sac endoderm

The three-dimensional architecture of the tubular endocytic apparatus and the endoplasmic reticulum in the rat yolk-sac endoderm was investigated after loading with horseradish peroxidase-conjugated concanavalin A by intrauterine administration. After 30 min, small vesicles (50–150 nm in diameter), small tubules (80–100 nm in diameter) and large vacuoles (0.2–1.0 m in diameter) in the apical cytoplasm were labeled with the tracer, but lysosomes (1.0–3.5 m in diameter) in the supranuclear cytoplasm were not labeled until 60 min after loading. Stereo-viewing of the labeled small tubules in thick sections revealed that they were not isolated structures but formed three-dimensional anastomosing networks, which were also confirmed by scanning electron microscopy after maceration with diluted osmium tetroxide. Their earlier labeling with the endocytic tracer, localization in the apical cytoplasm and three-dimensional network formation indicated that the labeled small tubules represented tubular endosomes (tubular endocytic apparatus). These well-developed membranous networks provided by the tubular endosomes are suggested to facilitate the receptor-mediated endocytosis and transcytosis of the maternal immunoglobulin in the rat yolk-sac endoderm. Scanning electron microscopy further revealed lace-like networks of the smooth endoplasmic reticulum near the lateral plasma membrane. Their possible involvement in transport of small molecules or electrolytes is discussed.     

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.     

The contribution of size-fractionated plankton to biomass and primary production of phytoplankton in saline–alkaline ponds

Primary productivity, biomass and chlorophyll-a of size fractionated phytoplankton (<0.22 m, <3 m, <8 m, <10 m, <40 m, <64 m, <112 m and <200 m) were estimated in 6 ponds and 5 experimental enclosures. The results showed that the planktonic algae less than 10 m are important in the biomass and production of phytoplankton in saline–alkaline ponds. The production of size fractionated phytoplankton corresponding to <112 m, <10 m and <3 m in saline–alkaline ponds were 10.5 ± 6.6 , 8.6 ± 5.4 and 0.33 ± 0.1 mgC l^–1 d^–1, respectively. Mean community respiration rate was 1.80 ± 0.73, 1.69 ± 0.90 and 1.38 ± 1.12 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) were 1.61, 8.30 and 0.33 mgC l^–1 d^–1, respectively. The ratio of those to the total phytoplankton production was 15%, 79% and 3%, respectively. The mean respiration rate of the different size groups was 0.11, 0.31 and 1.38 mgC l^–1 d^–1; the ratio of those to total respiration of phytoplankton was 6%, 17% and 77%, respectively. The production of size-fractionated phytoplankton corresponding to <200 m, <10 m and <3 m in enclosures was 2.19 ± 1.63, 2.08 ± 1.75 and 0.22 ± 0.08 mgC l^–1 d^-1, respectively. Mean community respiration rates were 1.25 ± 1.55, 1.17 ± 1.42 and 0.47 ± 0.32 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton was 0.11, 1.86 and 0.22 mgC l^–1 d^–1, respectively. The ratio of those to the total production of phytoplankton was 5%, 85% and 10%, respectively. The mean respiration rate of different size groups were 0.08, 0.72 and 0.46 mgC l^–1 d^–1, the ratio of those to total respiration of phytoplankton was 6%, 57% and 37%, respectively. The concentrations of chlorophyll-a of the phytoplankton in the corresponding size of micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) plankton in the experimental ponds were 19.3, 98.2 and 11. 9 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 15%, 76% and 9%, respectively. The concentrations of chlorophyll-a of phytoplankton micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton in enclosures were 1.7, 34.3 and 3.0 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 4%, 88% and 8%, respectively.     

Intranuclear inclusion bodies within neurons of spinal and cranial ganglia in three cyprinid species

Summary A histological examination of 205 fish representing four cyprinid species from a site 2.5 miles north of Wheeling, West Virginia, on the Ohio River revealed large (2–4 m) cuboidal intranuclear inclusion bodies (NIB's) within neurons in the cranial and spinal ganglia of three species. Because the minnows had been caught during a yearly sampling of fish, an additional 63 minnows were taken the following year. Inclusions were again observed. The NIB's stain strongly with phloxine as well as with Mallory and Giemsa stains, appearing bright red or pink. Various histochemical tests indicated that the inclusions contain protein and lipid but no carbohydrates or nucleic acids. No heavy metals were detected by electron probe analysis. At the ultrastructural level the inclusions exhibit subunits resembling hexagons measuring 326–350 nm. Previously suggested causes for such inclusions include effects of viruses, aging, drugs, cellular transformation, and an altered metabolic state of affected cells.     

Fine structure studies of the ocelli of Polyorchis penicillatus (Hydrozoa,Anthomedusae) and their connection with the nerve ring

Summary The fine structure of the small compact ocelli (50–100 m in diameter) of Polyorchis penicillatus is described. The ocellar cup is formed of pigment cells and receptor cells. The pigment cells occur in approximately a 2:1 ratio to the receptor cells. Each pigment cell has a process that may pass through the presumed photosensory region. Pigment cells are connected to adjacent receptor cell processes by septate junctions. The sensory cells are bipolar with the apical part forming the receptor process and the basal part forming an axon 8–15 m long and 1–2 m in diameter. Each receptor cell axon forms a synapse with a single second order neuron but the sensory cells are also connected to the second order neurons postsynaptically. There are also synapses between adjacent second order neurons. The second order neurons lie outside the ocellar cup, next to the tentacular mesogloea. Each second order neuron forms an axon of about 1 m thickness. The axons on each side group together to form an optic nerve having 30–40 axons that travel around the tentacle base on either side and enter the outer nerve ring independently.     

The endogenous development of three new intranuclear species of Isospora (Apicomplexa: Eimeriidae) from agamid lizards

Three new species of Isospora Schneider, 1881 are described from agamid lizards, Isospora cannoni n. sp. in Diporiphora australis from northern Queensland, Australia, I. choochotei n. sp. in Calotes mystaceus from northern Thailand, and I. deserti n. sp. in Agama pallida from Israel. I. cannoni oöcysts are subspherical, 20–25 × 22.5–27.5 m with two ovoid sporocysts, 14–15.5 × 10–11.5 m. I. choochotei oöcysts are spherical to subspherical, 24–32 × 28–32.5 m with two ovoid sporocysts, 11 × 15.5–18 m. I. deserti oöcysts are spherical, 25–28 m in diameter with two ovoid sporocysts, 10–11 × 14–17.5 m. All species had sporocysts with Stieda bodies and underwent endogenous development in the nucleus of the host gut epithelial cells. At completion of merogony and gamogony, the host nucleus was reduced to a thin envelope. The significance of endogenous stage characteristics in Isospora taxonomy is discussed.     

Efficiency of photosynthesis in continuous and pulsed light emitting diode irradiation

The light utilization efficiency and relative photon requirement of photosynthesis in pulsed and continuous light from light emitting diodes (LEDs) has been measured. First, we chacterized the photon requirement of photosynthesis from light of LEDs that differ in spectral quality. A photon requirement of 10.3±0.4 was measured using light from a 658 nm peak wavelength (22 nm half band width) LED over the range of 0–50 mol photons m^–2 s^–1 in 2 kPa O₂ in leaves of tomato (Lycopersicon esculentum Mill., cv. VF36). Because the conversion of electrical power to photons increased with wavelength, LED lamps with peak photon output of 668 nm were most efficient for converting electricity to photosynthetically fixed carbon. The effect of pulsed irradiation on photosynthesis was then measured. When all of the light to make the equivalent of 50 mol photons m^–2 s^–1 was provided during 1.5 s pulses of 5000 mol photons m^–2 s^–1 followed by 148.5 s dark periods, photosynthesis was the same as in continuous 50 mol photons m^–2 s^–1. When the pulse light and dark periods were lengthened to 200 s and 19.8 ms, respectively, photosynthesis was reduced, although the averaged photon flux density was unchanged. Under these conditions, the light pulses delivered 10¹⁷ photons m^–2, which we calculate to be equivalent to the capacitance of PS I or PS II. Data support the theory that photons in pulses of 100 s or shorter are absorbed and stored in the reaction centers to be used in electron transport during the dark period. When light/dark pulses were lengthened to 2 ms light and 198 ms dark, net photosynthesis was reduced to half of that measured in continuous light. Pigments of the xanthophyll cycle were not affected by any of these pulsed light treatments even though zeaxanthin formation occurred when leaves were forced to dissipate an equal amount of continuous light.Abbreviations CWF cool white fluorescent - EPS xanthophyll epoxidation state - LED light emitting diode - LUE light utilization efficiency - PFD photon flux density - PR photon requirement (for CO₂ fixation) - PS II primary donor in Photosystem II - RPR relative photon requirement     

On the localization,the fine structure,and the chemical composition of crystalline inclusions in theThesium humifusum haustoria

Summary TheThesium humifusum haustoria onMedicago marina roots, fixed in October–November, frequently contain in the cytoplasm of their cells inclusions consisting of sticks 0,3 m in thickness and 8 to 10 m in lenght, alone or associated in stacks of 3 or 6 units. These sticks consist of fibres, 10 nm in thickness, oriented in the same direction and separated from the others by a gap of 8 nm; these fibres seem to be composed of helically wound filaments and a less electron-dense matrix.The chemical composition of these inclusions was studied by enzymatic digestion in ultra thin sections; pronase digested the cytoplasmic paracrystals. This demonstrates that they are composed primarily of protein.The physiological significance of the inclusions is discussed: presumably the haustorium functions as a storage organe.     

Influence of inorganic microelements on the production of camptothecin with suspension cultures of <Emphasis Type="Italic">Camptotheca acuminata</Emphasis>

The effects of eight microelements (I^–, BO₃ ^3–, MoO₄ ^2–, Co²⁺, Cu²⁺, Mn²⁺, Fe²⁺, Zn²⁺) on the biosynthesis of camptothecin and the growth of suspension cultures of Camptotheca acuminata were studied. The increase of I^– to 25 M l^–1, Cu²⁺ to 1 M l^–1, Co²⁺ to 2 M l^–1 and MoO₄ ^2– to 10 M l^–1 in Murashige and Skoog (MS) medium resulted in 1.66, 2.84, 2.53 and 2.04 times higher of camptothecin yield than that in standard MS medium respectively. Combined treatment of I^– (25 M l^–1), Cu²⁺ (1 M l^–1), Co²⁺ (2 M l^–1) and MoO₄ ^2– (10 M l^–1) lead to improve cell dry weight, camptothecin content, and camptothecin yield to 30.56 g l^–1, 0.0299%, and 9.15 mg l^–1, respectively, which were 20.2, 208.9 and 273.8% increment respectively when compared with those of control.     

Arsenic concentrations in water and fish from Chautauqua Lake,New York

Synopsis Arsenic persists in Chautauqua Lake, New York waters 13 years after cessation of herbicide (sodium arsenite) application and continues to cycle within the lake. Arsenic concentrations in lake water ranged from 22.4–114.81 g l^–1, = 49.0 ag l^–1. Well water samples generally contained less than 10 g l^–1 arsenic. Arsenic concentrations in lake water exceeded U.S. Public Health Service recommended maximum concentrations (10 g l^–1) and many samples exceeded the maximum permissible limit (50 g l^–1). Fish accumulated arsenic from water but did not magnify it. Fish to water arsenic ratios ranged from 0.4–41.6. Black crappie (Pomoxis nigromaculatus) contained the highest arsenic concentrations (0.14–2.04 g g^–1 ), X = 0.7 g g^–1) while perch (Perca flavescens), muskellunge (Esox masquinongy) and largemouth bass (Micropterus salmoides) contained the lowest concentrations (0.02–0.13 g g^–1). Arsenic concentrations in fish do not appear to pose a health hazard for human consumers.     

Pesticides and heavy metals in Danish streambed sediment

The role of streambed sediment as a sink for pesticides and heavy metals was investigated in 30 Danish lowland streams. The investigated streams drain catchments varying in hydrology, topography, soil type and land use. The <250 m newly accumulated fraction of the uppermost 1–2 cm layer of streambed sediment was analysed for 19 old and modern pesticides and 9 heavy metals. DDE was present in the sediment of all the streams. Of the herbicides, fungicides and insecticides currently in use, the most frequently detected was diuron (50.0%), fenpropimorph (66.7%) and lambda-cyhalothrin (6.7%), respectively. The pesticides detected in the highest concentration were fenpropimorph (1700 ng g^–1), propiconazole (130 ng g^–1) and isoproturon (110 ng g^–1). The heavy metals are listed in order of increasing median concentration: Cd (0.80 g g^–1), Co (9.1 g g^–1), As (12.0 g g^–1), Ni (19.0 g g^–1), Cr (19.2 g g^–1), Pb (19.7 g g^–1), Cu (20.1 g g^–1), V (28.5 g g^–1), Zn (103 g g^–1). The average number of pesticides detected in the 27 streams draining predominantly agricultural catchments was (3.7±2.0) being higher (p=0.077) than in the three streams draining non-agricultural catchments (1.7±0.6). Pesticides were significantly related to catchment size, soil type and hydrological regime. Several heavy metals (Cr, Cu, Pb, V and Zn) were related to urban activity and soil type.     

Tissue culture ofKarwinskia humboldtiana—a plant producing toxins with antitumoural effects

Isolated embryos ofKarwinskia humboldtiana were cultured in vitro. The growth of embryos and development to plantlets on woody plant medium supplemented with indole-3-acetic acid 6.10^-2 mol l^–1, gibberellic acid (GA₃) 3.10^-2 mol l^–1, and 6-benzylaminopurine (BA) 2 mol l^–1 was obtained. Multiplication of shoots and rooting of excised shoots has been achieved. Callus formation on modified Murashige-Skoog medium supplemented with 1-naphthaleneacetic acid 10 mol l^–1, GA₃ 14 mol l^–1, and kinetin 5 mol l^–1 on hypocotyls, or on root cultures on medium supplemented with 2.4-dichlorophenoxyacetic acid 10 mol l^–1 and BA 10 mol l^–1 was induced.Abbreviations BA 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - TEM transmission electron microscopy     

Light response of D1 turnover and photosystem II efficiency in the seagrassZostera capricorni

Biochemical and biophysical parameters, including D1-protein turnover, chlorophyll fluorescence, oxygen evolution activity and zeaxanthin formation were measured in the marine seagrassZostera capricorni (Aschers) in response to limiting (100 mol·m^–2·^–1), saturating (350 mol·m^–2·s^–1) or photoinhibitory (1100 mol·m^–2·s^–1) irradiances. Synthesis of D1 was maximal at 350 mol·m^–2·s^–1 which was also the irradiance at which the rate of photosynthetic O₂ evolution was maximal. Degradation of D1 was saturated at 350 mol·m^–2·s^–1. The rate of D1 synthesis at 1100 mol·m^–2·s^–1 was very similar to that at 350 mol·m^–2·s^–1 for the first 90 min but then declined. At limiting or saturating irradiance little change was observed in the ratio of variable to maximal fluorescence (Fv/Fm) measured after dark adaptation of the leaves, while significant photoinhibition occurred at 1100 mol·m^–2·s^–1. The proportion of zeaxanthin in the total xanthophyll pool increased with increasing irradiance, indicative of the presence of a photoprotective xanthophyll cycle in this seagrass. These results are consistent with a high level of regulatory D1 turnover inZostera under non-photoinhibitory irradiance conditions, as has been found previously for terrestrial plants.We would like to thank Professor Peter Böger (Department of Plant Biochemistry, University of Konstanz, Germany) for the kind gift of D1 antibodies. This work was partly supported by a University of Queensland Enabling Grant to CC.     

Grazing by a dominant rotifer Conochilus unicornis Rousselet in a mountain lake: in situ measurements with synthetic microspheres

Grazing rates of zooplankton were analysed in the summer of 1999 in Yellow Belly Lake, an oligotrophic system in the Sawtooth Mountains of Idaho (U.S.A.). The colonial rotifer Conochilus unicornis was a dominant species in the epilimnion, with densities reaching 20 colonies l^–1 (ca. 400 ind. l^–1). Clearance rates were measured with an in situ Haney Grazing chamber and synthetic microspheres 5, 9 and 23m in diameter. At epilimnetic temperatures of around 14 °C, mean clearance rates for 5m particles ranged from 30 to 65 l ind.^–1 h ^–1. Clearance rates were 2–9 times higher on the 5m spheres than on the 9 m spheres, and C. unicornis almost never fed on the 23 m spheres. Grazing rates did not change over the diel cycle. Clearance rates declined more than 10-fold as temperatures declined from 14 °C in the epilimnion to 7 °C in the metalimnion. In the epilimnion, grazing by C. unicornis was more important than grazing by crustaceans in the community, at least on particles 9m. The results show the importance of grazing by rotifers in lakes, and the significance of spatial variations that influence grazing rates.     

An unusual cell in the central nervous system of Hirudo medicinalis L.: a neuron with ribbons and flags

Summary A neuron (cell 151) with the ability to silence efferent activity in the roots of a leech segmental ganglion was filled with horseradish peroxidase and studied by light-and electron microscopy. The neurites of cell 151 penetrate all areas of the neuropile except for a thin ventral layer. The branching pattern of the secondary neurites is highly variable. Post-and presynaptic structures of chemical synapses with clear vesicles of 25 nm diameter were identified. Neurites are mostly wrapped in glia and run in bundles among other axons. They frequently form ribbons which are 20–40 nm thick, extend several microns away from the dendrite and are followed up to 3 m in depth. They also form flags which are 0.5 m thick, spread out 10–20 m horizontally and run up to 80 m laterally. Both structures lie adjacent to or wrap around axons of other neurons, forming a gap of 8–10 nm. Flags and ribbons are typical for glia but have not been described previously as structures of neurons. Contralateral cells 151 appose each other in the commissures with a gap of 5–10 nm. The possible functional significance of these findings is discussed with respect to electrical coupling and to reception of strain.     

Osmotic measurements on stomatal cells ofCommelina communis L.

Summary Observations of aperture changes as sucrose is added to the solution bathing epidermal strips ofCommelina communis L. allow calculation of the osmotic changes required to open or close the stomatal pore, for comparison with changes in potassium content. With isolated guard cells, in strips in which all cells other than guard cells have been killed, the internal osmotic changes required are 83 mosmol kg^–1 m^–1 below 10m aperture, 129 mosmol kg^–1 m^–1 in the range 10–15 m, and 180 mosmol kg^–1 m^–1 above 15 m. For opening against subsidiary cell turgor in addition to guard cell turgor, in intact strips with live subsidiary and epidermal cells, these figures should each be increased by about 33 mosmol kg^–1 m^–1. A change in subsidiary cell turgor is magnified in its effects on the water relations of the guard cell by a factor greater than 3.7 for equal changes in the water potential of the two cells, or greater than 4.7 at constant volume of the guard cell.     

CO2 gas exchange of benthic microalgae during exposure to air: a technique for the rapid assessment of primary production

A method of measuring CO₂gas exchange (caused, for example, by microalgal photosynthesis on emersed tidal mudflats) using open flow IR gas analyzers is described. The analyzers are integrated in a conventional portable photosynthesis system (LI-6400, LI-COR, Nebraska, USA), which allows manipulation and automatic recording of environmental parameters at the field site. Special bottomless measuring chambers are placed directly on the surface sediment. Measurements are performed under natural light conditions and ambient CO₂concentrations, as well as under different CO₂concentrations in air, and various PAR radiation levels produced by a LED light source built into one of the measurement chambers. First results from tidal channel banks in a north Brazilian mangrove system at Bragança (Pará, Brazil) under controlled conditions show a marked response of CO₂assimilation to CO₂concentration and to irradiance. Photosynthesis at 100molmol^–1CO₂in air in one sample of a well-developed algal mat was saturated at 309mol photons m^–2s^–1, but increased with increasing ambient CO₂concentrations (350 and 1000mol mol^–1CO₂) in the measuring chamber. Net CO₂assimilation was 0.8mol CO₂m^–2s^–1at 100mol mol^–1CO₂, 5.9mol CO₂m^–2s^–1at 350mol mol^–1CO₂and 9.8mol CO₂m^–2s^–1at 1000mol mol^–1CO₂. Compensation irradiance decreased and apparent photon yield increased with ambient CO₂concentration. Measurements under natural conditions resulted in a quick response of CO₂exchange rates when light conditions changed. We recommend the measuring system for rapid estimations of benthic primary production and as a valuable field research tool in connection with certain ecophysiological aspects under changing environmental conditions.     

Tubuläre Einschlüsse in Microbodies vonSaccharomycopsis (Candida) lipolytica-Protoplasten

Zusammenfassung Auf Ultradünnschnitten Glutaraldehyd-OsO₄ oder KMnO₄ fixierterSaccharomycopsis lipolytica-Zellen, die in einem Medium mit Laktat als C-Quelle wuchsen, werden durchschnittlich 3–4 Anschnitte von Microbodies gefunden. Ihre Anzahl erhöht sich etwa um das Dreifache, wenn n-Hexadecan die C-Quelle ist.Nach der Umwandlung der Zellen zu Protoplasten mit Hilfe von Enzymgemischen vonHelix pomatia enthalten die Microbodies tubuläre Einschlüsse. Diese Tubuli, deren äußerer Durchmesser etwa 25 nm beträgt, haben eine zentrale Verdichtung und erreichen Längen bis zu 0,8 m. Sie sind in Bündeln oder Schichten angeordnet. Die Tubuli bilden sich möglicherweise durch Assemblierung von Enzymproteinen, wenn die Zellen während der Umwandlung zu Protoplasten mit hypertonischen Lösungen osmotisch geschockt werden.

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Tubular inclusions within microbodies ofSaccharomycopsis (Candida) lipolytica-Protoplasts

Summary Electron micrographs ofSaccharomycopsis lipolytica-cells grown in a medium with lactate as carbon source and fixed with glutaraldehyde-OsO₄ or KmnO₄ show 3–4 profiles of microbodies per section in average. The number of microbodies is about three times greater when cells are cultivated in a medium with n-hexadecane. The spherical to avoid microbodies (0.3–0,8 m in diameter) have a homogeneous matrix.After conversion of cells into protoplasts by the aid of snail gut juice tubular inclusions occur in microbodies. The single tubulus has an outer diameter of about 25 nm, a length up to 0.8 m and contains a central rod. Several tubules form bundles or layers. It is suggested that the tubules could be enzyme protein assembling by osmotic shock with hypertonic solutions during preparation of protoplasts.