Freeze-fracture studies on the cockroach hemocyte membrane complex: Symmetric and asymmetric membrane particle distributions

Summary Freeze-fracture studies were conducted on the membranes of normal cockroach hemocytes. The plasmalemma is asymmetric with the A fracture face containing 80–100 Å membrane intercalated particles at a concentration of 2500/². The B fracture face contains 120–150 Å particles with a relatively low density (800/²). The nuclear envelope displays an asymmetry with the A fracture face containing 1500 particles/² and the B face containing 300/ ². No significant particle size differences were observed in nuclear envelope fracture faces. Two types of symmetric membranes were also found in these cells. Both A and B fracture faces of the membrane surrounding the numerous cytoplasmic inclusion bodies contain particle sizes and concentrations similar to the B face of the plasmalemma. A second type of symmetry was observed in cells apparently engaged in exocytosis. Vesicles (0.1 D) from this process were completely particle free on both fracture faces. Such particle free vesicles could be found in the cytoplasm, attached to the plasmalemma, or completely separated from the cell.Supported by a Pharmaceutical Manufacturers Association Foundation Fellowship.The author wishes to thank Ms. Annalena K. Charla for assistance in plate preparation, Dr. Julius Schultz and the Papanicolaou Cancer Research Institute for use of the freeze-etch device, and Dr. David Smith for the electron microscope facilities.     

“Sunbursts” and “christiesomes”: Cellular fragments in normal cow and goat milk

Summary Goats' milk includes numerous cell fragments (christiesomes) which originate from the mammary secretory cells, contain well preserved endoplasmic reticulum, mitochondria and lipid droplets, and are responsible for the considerable triglyceride synthesising capacity of fresh goat milk. Cows' milk shows a few such particles only after repeated oxytocin-aided milkings. Cows' milk does contain quite different particles which have a dense content with a few small vesicles and numerous microvillus-like protrusions on one side (sunbursts). These have not been found in goats milk. Cytoplasmic particles similar to sunbursts have been found on the surface of the mammary secretory epithelium. It is suggested that they are residues of dead cells.     

Ultrastructure of four types of striated muscle fibers in the atlantic hagfish (Myxine glutinosa,L.)

Summary Four types of striated muscle fibers with distinctive ultrastructure were defined in the Atlantic hagfish (Myxine glutinosa, L.): white, intermediate, and red fibers of m. parietalis, and red fibers of m. craniovelaris.White fibers are thick, contain very few mitochondria and fat vacuoles, and possess distinct and separate myofibrils with thin Z-disks and distinct M-lines. Intermediate fibers are thinner, possess largely similar myofibrils that often are even better separated due to a higher content of fat vacuoles and especially mitochondria and glycogen granules. Red fibers of m. parietalis contain large amounts of mitochondria, fat vacuoles, and glycogen granules. Their myofibrils possess M-lines, and although branching more, the myofibrils of red fibers conform with a Fibrillenstruktur pattern like those of white and intermediate fibers. Red fibers of m. craniovelaris are very thin, possess many smaller fat vacuoles, and large amounts of mitochondria and glycogen granules. The myofibrils are significantly thinner than in m. parietalis fibers, run as quite independent well separated units, possess thicker Z-disks, and lack M-lines. Large amounts of myosatellite cells are associated with these red fibers.Triads are located near A/I-junctions in all four fiber types and occur irregularly, the density of triads being different in the various fiber types.We are indebted to Dr. Finn Walvig, Biological Station, University of Oslo, Drøbak, for supply of hagfishes, and we also wish to thank Dr. Jan K. S. Jansen, Institute of Physiology, University of Oslo, for valuable suggestions during this study.     

Decay of γ particles in germinating zoospores of Blastocladiella emersonii

Summary The breakdown and disappearance of particles was followed by electron microscopy on synchronously germinating populations of B. emersonii zoospores. The sequence of morphological changes, unaffected by the method used to induce germination, was divided into four stages. Initially, the particle's surrounding unit membrane becomes amorphous and buds off vesicles that fuse with the plasma membrane. Simultaneously, ca. 80 m vesicles are visible either partially embedded in, or lying free along, the inner surface of the electron dense matrix. These small vesicles seem to originate from a newly detected membrane system in the electron dense matrix. In the next stage, particles characteristically adhere to various organelles, especially the nuclear cap. In subsequent stages the particles continue to decay by releasing 80 m vesicles from their matrices and by budding off vesicles from their surrounding membranes. Often, multivesicular bodies are formed when the 80 m vesicles become enclosed by the particle's budding outer membrane. In the final stage, the surrounding membranes of the different particles fuse and produce large vacuoles containing many of the electron dense matrices which, though by now partially fragmented, continue to release 80 m vesicles. The relationship of the above events to the formation of the cell wall is discussed.     

Cytokinesis in the green alga Eremosphaera viridis: Plasmalemma formation from “open membranes”

Summary Cytokinesis in the unicellular chlorococcalean alga Eremosphaera viridis de Bary has been investigated by electron microscopy of thin sections. The new plasmalemmata of the daughter cells in this organism form centrifugally within a phycoplast. Unlike other cell division systems each new plasmalemma is formed, not by the fusion of vesicles, but rather by the fusion of open membranes which are characteristically heavily stained. Measurements of these open membranes reveal that they are 11 nm thick with a central 4,5 nm unstained portion. The possible origin of these open membranes as burst-open vesicles has been suggested from the presence of intensely straining vesicles in the vicinity of the cell equator. Calculations of vesicle and open membrane surface areas support this contention.     

Structural differences in active site-labeled thrombin complexes with hirudin isoinhibitors

Hirudin, a 65 amino acid polypeptide from the medicinal leech, is the most potent thrombin inhibitor known to date. Recently, recombinant forms have been reported, which are as effective as the isolated forms. The studies presented here demonstrate sensitive spectroscopic methods for distinguishing binding of two recombinant hirudins, HV1 and HV2-Lys 47, with active site-labeled human -, - and -thrombins. Specifically, fluorosulfonylphenyl nitroxide spin labels, dansyl fluoride and p-nitrophenylanthranilate, were employed as active site-directed covalent reporter groups. In general, the nitroxide immobilization was greater for spin-labeled thrombin complexes with HV2-Lys 47 vs. HV1. The two fluorophore moieties, dansyl and anthraniloyl, were also sensitive to differences in HV1 and HV2-Lys 47 binding, including interactions with loop 145–150 of the thrombin structure where the - and -thrombin cleavages exist. Speculation over sequence differences between the two isoinhibitors centers on residues 24 and 47, both of which involve either a loss or gain of charge on the side chain.     

Endocrine cells in the human fetal small intestine

Summary In this report we describe the time of appearance and ultrastructural features of enteroendocrine cells (EECs) in the human fetal small intestine (SB) between 9 and 22 weeks gestation. Thirteen distinctive EECs were identified in fetal SB. Two of these, not found in normal adult SB, appeared within the stratified epithelium of the proximal SB at 9–10 weeks. They were arbitrarily termed primitive and precursor cells. As in all fetal EECs, the pale cytoplasm of the primitive cell contains a distinctive population of secretory granules (SGs). Primitive cell SGs average 200–330 nm; some have dense cores with lucent halos while others are filled with a homogeneous dense or flocculent material. The SGs of the precursor cells are larger, averaging up to 1 m in diameter and their contents vary in electron density. A third group of cells not described in normal adult SB was arbitrarily termed transitional cells. These have two populations of SGs; one resembles the SGs of the precursor cells, and the other resembles the SGs of some of the specific adult type EECs. Transitional EC, S, I and G cells are seen. In addition, mature appearing EC, S, G, I, L, D, and D₁ cells were identified by 12 weeks of gestation. The primitive, precursor, and transitional cells may represent sequential developmental precursors of adult type EECs.Supported by Research Grant AM-17537 from the National Institutes of Health, Besthesda, MarylandThe authors would like to thank Ms. Linda Barstein for her excellent technical assistance     

Das organische Gerüstwerk der Kalkschale des Schwanen-Eies

Zusammenfassung Kegel und Säulen der Schwanen-Eischale hinterlassen am Querschliff nach Entkalkung mit EDTA organisches (mucoproteides) Material als ein zusammenhängendes Gerüst, das sich mit Thionin metachromatisch färbt; ohne Demineralisierung oder wenigstens Anätzung bleibt Thionin an Schliffen und Bruchkanten der Schale wirkungslos. Das Lichtmikroskop zeigt an Schliffen nichts von dem organischen Material, es wurde während des Kristallwachstums fein zerteilt in Gitterlücken des Schalencalcits eingeschlossen. Es findet sich am stärksten angehäuft an den äueren und inneren Oberflächen der Kristall-individuen. In den Kegeln ist das Gerüst radial ausgebildet als die Loculi der Keile, und konzentrisch geschichtet, entsprechend den Lagen der Globularinklusionen, um deren jede herum Verdichtung der organischen Substanz statthat. In den inneren Säulen folgt das organische Gerüst dem Rhombenmuster; die äueren Säulen sind arm an organischer Substanz, hier verbleibt nach der Entkalkung eine dünne laterale Oberflächenschicht.

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Summary The cones and columns of the swans egg shell leave behind after decalcification with EDTA an organic (mucoproteid) material in form of a continuous frame work stainable metachromatically with thionine. Without demineralisation or at least etching, thionine proves ineffectual in ground sections or breaking edges of the shell. In ground sections the light microscope demonstrates nothing of the organic material: it was inclosed during the crystal growth in submicroscopical lattice gaps of the calcite individuals. The organic material is chiefly accumulated in the outer and inner surfaces of the crystals. In the cones the organic frame work is developed radially as the loculi of the wedges and concentrically layered corresponding with the globular inclusions, concentrated in the circumference of each. In the inner columns the organic material follows to the rhomb pattern. The outer columns after decalcification only leave behind a thin lateral organic sheath.

     

The glycolipid specificity ofErythrina cristagalli agglutinin

The interaction of¹²⁵I-labeledErythrina cristagalli agglutinin (ECA) with neutral glycosphingolipids on thin layer chromatograms was examined by the overlay technique followed by radioautography. The lectin bound topara-globoside with a sensitivity about 10 times higher than to lactosylceramide or globoside, in agreement with the specificity of the lectin forN-acetyllactosamine. The lower limit of detection ofpara-globoside was about 0.66 nmol. The specific binding of ECA to this glycolipid was confirmed by a highly sensitive enzyme-linked lectin assay (ELLA), utilizing the horseradish peroxidase-avidin-biotin system for detection of bound lectin. Overlays of neutral glycosphingolipid extracts from human erythrocyte membranes and from human granulocytes with ECA demonstrated that the lectin can be employed for the detection of small amounts ofpara-globoside in biological materials also in the presence of excess globoside. No staining was obtained when thin layer chromatograms of neutral glycosphingolipid extracts from rabbit erythrocyte membranes were overlayed with¹²⁵I-ECA. Afterin situ treatment of the chromatograms with -galactosidase, the lectin bound to several components, one of which had a mobility corresponding to that of the pentahexosylceramide Gal3Gal4GlcNAc3Gal4Glc1Cer, the major neutral glycosphingolipid of rabbit erythrocytes, thus providing further evidence for the specificity of ECA forpara-globoside.Abbreviations GSL glycosphingolipid(s) - CDH lactosylceramide, Gal4Glc1Cer - CTH trihexosylceramide, Gal4Gal4Glc1Cer - GLOB globoside, GalNac3Gal4Gal4Glc1Cer - PG para-globoside, Gal4GlcNAc3Gal4Glc1Cer - AsG_M1 asialo-G_M1, Gal3GalNAc4Gal4Glc1Cer - FORS Forsmann antigen, GalNAc3GalNAc3Gal4Gal4Glc1Cer - CPH pentahexosylceramide, Gal3Gal4GlcNAc3Gal4Glc1Cer - ECA Erythrina cristagalli agglutinin - SBA soybean agglutinin - PBS phosphate-buffered saline - PVP-40 polyvinylpyrrolidone M.W. 40000 - BSA bovine serum albumin - HRP-avidin horseradish peroxidase conjugated to avidin - ELLA enzyme-linked lectin assay - ELISA enzyme-linked immunosorbent assay - PMNL polymorphonuclear leukocytes - HPTLC high performance thin layer chromatography     

Production of a novel syrup containing neofructo-oligosaccharides by the cells of Penicillium citrinum

A novel syrup containing neofructo-oligosaccharides was produced from sucrose (Brix 70) by whole cells of Penicillium citrinum. The efficiency of fructo-oligosaccharides production was more than 55% and those of the main carbohydrate components, 1-kestose (Fruf 21Fruf 21 Glc), nystose (Fruf 21Fruf 21 Fruf 21 Glc) and neokestose (Fruf 26 Glc12 Fruf), were 22, 14 and 11%, respectively.     

Molecular switch of F0F1-ATP synthase,G-protein,and other ATP-driven enzymes

Exchange-out of amide tritium from labeled -subunit of ₃₃ complex of F₀F₁-ATP synthase was not accelerated by ATP, suggesting that hemagglutinin-type transition of coiled-coil structure did not occur in -subunit. Local topology of nucleotide binding site and switch II region of G-protein resemble those of F₁- subunit and other proteins which catalyze ATP-triggered reactions. Probably, binding of nucleotide to F₀F₁-ATP synthase induces conformational change of the switch II-like region with transforming subunit structure from open to closed form and this transformation results in loss of hydrogen bonds with the subunit, thus enabling the subunit to move.     

Fine root biomass,production and turnover in a fertilized <Emphasis Type="Italic">Larix leptolepis</Emphasis> plantation in central Korea

The effects of fertilization [control (C), 200kgNha^–1+25kgP ha^–1 (LNP) and 400kgNha^–1+ 50kgP ha^–1 (HNP)] on fine root dynamics were examined in a 40-year-old Larix leptolepis plantation in central Korea. The average fine root biomass during the growing season for C, LNP and HNP was 957, 934 and 814kgha^–1, respectively, whereas the fine root production for C, LNP and HNP was 2103, 2131 and 2066kgha^–1, respectively. Nitrogen and P inputs into the soil via fine root turnover for C, LNP and HNP were 23.0 and 1.2, 23.3 and 1.2 and 22.6 and 1.2kgha^–1, respectively. There were no significant differences in fine root biomass, production and N and P inputs through fine root turnover between the fertilization treatments during the first growing season after fertilization.     

Synthesis of disaccharide derivatives employing β-N-acetyl- d-hexosaminidase, β-d-galactosidase and β-d-glucuronidase

-N-Acetyl-d-hexosaminidase from Aspergillus oryzae catalysed the stereo- and regiospecific formation of the 6-O-benzylated disaccharide derivatives GalNAc1-3(6- OBn)Gal-SEt and GlcNAc1-3(6-OBn)Gal-SEt, which were obtained in transglycosylation reactions employing ethyl 6- O-benzyl-1-thio--d-galactopyranoside as acceptor. Preparative amounts of the chitobiose derivative GlcNAc1- 3GlcNAc-OPhNO2-p was prepared as well. - N-Acetyl-d-hexosaminidase from bovine testes catalysed the specific synthesis of GlcNAc1-3(6-OBn)GlcNH2-SEt and GalNAc1-3(6-OBn)GlcNH2-SEt, employing ethyl 2-amino-6-O-benzyl-2-deoxy-1-thio--d-glucopyranoside as acceptor. -d-Glucuronidase from E. coli was found to catalyse the formation of GlcA1-3(6-OBn)GlcNH2- SEt employing the same acceptor.     

X-ray microanalysis of calcium binding sites in Paramecium

Summary In Paramecium cells Ca⁺⁺-stimulated triggering of the exocytosis of secretory vesicles (trichocysts) was achieved by ionophores X-537 A or A 23187. Under triggering conditions electron dense deposits were present in some resting trichocysts and regularly in discharging trichocysts; upon subsequent fixation deposits occurred on the trichocyst membrane (on the inner side or within the membrane) and on the inner lamellar sheath from where deposits seemed to radiate into the secretory materials. Similar results were obtained with glutardialdehyde fixation alone which also triggers exocytosis but only at low concentrations. Element analysis by energy dispersive x-ray microanalysis ascertained the presence of Ca and P in deposits occurring in trichocysts. Those resting trichocysts which were devoid of deposits did not contain Ca or P enriched. Hence, an abrupt Ca⁺⁺-influx into individual trichocysts just before exocytosis seems to be involved in the triggering mechanism, possibly in combination with the sudden activation of an ATPase systemlocalized at those sites of the trichocysts which primarily contain the deposits. When paramecia were treated only with Ca⁺⁺ and then fixed with OsO₄ plus oxalate or merely with glutardialdehyde, electron scattering deposits were formed also on the inner side of the cell membrane and within the ciliary shaft (but rarely in trichocysts). Deposits obtained on cilia (including ciliary granule plaques) also contained Ca, P and S. Cells contain osmiophilic calcium-storing vacuoles which were selectively rich in Ca and S but devoid of P.     

An increase in the “inhibitor-β” content of detached wheat leaves following a period of wilting

Summary Wheat seedlings were grown under a 14-hour photoperiod and the first leaves excised at the end of the eighth dark period. The effect of treatments causing wilting on the inhibitor- content of such leaves was studied.When leaves were rapidly wilted (i.e. to a 6% fresh weight loss) and extracted immediately, the amount of inhibitor- per leaf was found to be the same as in fresh turgid leaves. However, when the leaves were maintained in a wilted condition in darkness for a period of 110 minutes, there was a marked increase in inhibitor- content.The greater the degree of wilting (i.e. up to about a 9% loss in fresh weight) the greater the eventual inhibitor- content. Moreover, the increment in inhibitor- was shown to be temperature dependent.The time lapse requirement and the temperature dependency of the inhibitor- formation suggest an enzymic conversion from a precursor.If a similar phenomenon occurs during the wilting of intact plants then the increase in this growth inhibitor might play a role in some of the physiological changes which accompany water stress.     

β-Ether cleavage of the lignin model compound 4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether and derivatives by Phanerochaete chrysosporium

The white rot basidiomycete Phanerochaete chrysosporium metabolized 4-ethoxy-3-methoxyphenyl-glycerol--guaiacyl ether (V) in low nitrogen, stationary cultures under which conditions the ligninolytic enzyme system is expressed. 4-Ethoxy-3-methoxyphenylglycerol XIII, guaicol and 4-ethoxy-3-methoxybenzyl alcohol (II) were isolated as metabolic products. Exogenously added XIII was rapidly converted to 4-ethoxy-3-methoxybenzyl alcohol indicating that it is an intermediate in the metabolism of V. P. chrysosporium also metabolized 1-(4-ethoxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-3-hydroxypropane VI. The degradation pathway for this dimer also included initial -ether cleavage and -hydroxylation of the diol product 1-(4-ethoxy-3-methoxyphenyl) 2,3 dihydroxypropane (XI) to yield the triol XIII which was cleaved at the , bond to yield 4-ethoxy-3-methoxybenzyl alcohol. Finally P. chrysosporium also cleaved the dimer 1-(4-ethoxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-1-hydroxypropane (VIII) at the -ether linkage yielding 1-(4-ethoxy-3-methoxyphenyl) 1,2 dihydroxypropane (IX) which was subsequently cleaved at the , bond to yield II. All of the results indicate that oxidative -ether cleavage is an important initial reaction in the metabolism of -aryl ether lignin substructure dimeric compounds. Metabolities were identified after comparison with chemically synthesized standards by gas liquid chromatography-mass spectrometry.Abbreviations GLC Gas liquid chromatography - TMSi trimethylsilyl - TLC thin layer chromatography     

Effect of oxygen on growth and respiration of potato tuber callus

Growth and oxygen uptake of potato callus is faster in an oxygen-enriched atmosphere (70% oxygen, v/v; oxygen-callus) than in air (20% oxygen, v/v; air-callus). Especially the non-mitochondrial, so-called residual respiration is increased in oxygen-callus. The capacities of the mitochondrial respiratory pathways (cytochrome pathway, V_cyt and alternative pathway, V_alt) are also higher in this callus. In both callus types only a small part of the alternative pathway capacity is used in uninhibited respiration. The lower oxygen uptake of air-callus at normal air oxygen pressures is partially due to diffusional impedance. Measurement of the respiratory parameters of air-callus in oxygen-saturated medium leads to higher values than measurement in air-saturated medium, although these values are still lower than those of oxygen-callus.ATP-production was calculated from the oxygen-uptake data and compared with the dry weight production of the callus to give values of 10.0 and 10.8 g dry weight produced.-mol ATP^-1, for air-callus and oxygen-callus respectively. As no harmful side-effects are observed, cultivation of callus under elevated oxygen pressures may be useful, when rapid callus-growth is necessary.Abbreviations AA antimycin A; A; - BHAM benzohydroxamate - DW dry weight - FW fresh weight - 8-OHQ 8-hydroxyquinolin - RC respiratory control - SHAM salicylhydroxamate     

The cytology of phytophthora infestans

Summary Phytophthora infestans has three kinds of somatic nuclei: an oval shaped nucleus (approx. 3.1×2.7 ) which stains diffusely except for a crescent shaped Feulgen positive cap which stains intensely; a granular nucleus whose contents are organized into a fairly constant number of stained bodies, and, a deeply staining condensed nucleus. The capped nucleus is thought to be metabolic or resting and the granular nucleus is thought to be dividing as it is most commonly found in hyphal tips. Attenuated forms of all three kinds of nuclei are found.Nuclear division is mitotic and intranuclear. Eight—ten chromosomes are seen at metaphase.Sporangia have a mean of 6.3 nuclei which is constant for age and strain of culture. Sporangia become multinucleate as a result of nuclear migration and not by division in the developing sporangium. Zoospores are usually uninucleate.The nuclear cap is persistent throughout nuclear division when it also divides. It is associated with flagella production and nuclear migration and has some of the properties of a blepharoplast.     

Single mid-chain GlcNAcβ1-6Galβ1-4R sequences of linear oligosaccharides are resistant to endo-β-galactosidase ofBacteroides fragilis

Endo--galactosidase (EC 3.2.1.103) ofBacteroides fragilis, at 250 mU ml^–1, did not cleave the internal galactosidic linkage of the linear radiolabelled trisaccharide GlcNAc1-6Gal1-4GlcNAc, or those of the tetrasaccharides Gal1-4GlcNAc1-6Gal1-4GlcNAc and Gal1-4GlcNAc1-6Gal1-4Glc. The isomeric glycans which contained the GlcNAc1-3Gal1-4GlcNAc/Glc sequence were readily cleaved.Abbreviations GlcNAc 2-acetamido-2-deoxy-d-glucose - Lact lactose - MT maltotriose - MTet maltotetraose - R _MTet chromatographic migration rate in relation to that of maltotetraose     

Elektronenmikroskopische Untersuchungen über Bildung und Struktur der Zygotenwand beiMicrasterias papillifera (Desmidiaceae)

Zusammenfassung Die Feinstruktur von Mesospor und Endospor reifer Zygoten vonMicrasterias papillifera wurde untersucht. Das für die Resistenz der Zygoten gegenüber ungünstigen Umweltbedingungen wichtige Mesospor besteht aus vier Schichten von unterschiedlicher Elektronendichte. Es ist insgesamt 460–500 nm dick. Die Schichten Mes a und Mes c bestehen aus akkrustierten, dicht gepackten globulären Elementen eines Stoffes, der dem Sporopollenin ähnlich ist. Die Schicht Mes b zeigt ein fibrilläres Grundgerüst, wahrscheinlich aus Zellulose, in das Stoffe inkrustiert sind, die nicht mit denen der Schichten Mes a und Mes c identisch, aber gegen Abbauversuche ähnlich résistent sind.Die Schicht Mes d ist eine Übergangsschicht zum Endospor. Zwischen die Zellulose-Mikrofibrillen in Streutextur sind isolierte Partikel des Materials der Schicht Mes c eingestreut. Das etwa 650 nm dicke Endospor ist eine Zelluloseschicht mit Streutextur. Es wird als Wand der sogenannten Keimblase bei der Zygotenkeimung nach Sprengung von Exospor und Mesospor stark gedehnt.

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Electron microscopical investigations on the structure and formation of the zygote wall inMicrasterias papillifera (Desmidiaceae) II. The structure of the mesospore and the endospore

Summary The mesospore (460–500 nm thick) which is responsible for the resistance of the zygote against desiccation during its resting period, consists of four layers of different electron density. The layers Mes a and Mes c are composed of densely packed amorphous globular elements of a substance resembling sporopollenine. The layer Mes b has a fibrillar, probably cellulosic frame. It is incrusted by a substance which is not identical with that of Mes a or Mes c but which shows a comparable resistance against degradation.The layer Mes d contains isolated particles such as in Mes c and cellulose microfibrils of the endospore. The endospore (650 nm thick) has foliate texture. This layer surrounds the protoplast after it has escaped from the ruptured exospore and mesospore during zygospore germination.

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Der Deutschen Forchungsgemeinschaft dank ich f:ur Sachbeihilfe.