Secretory PITS in Backswimmers (Heteroptera: Notonectidae).

Author(s):  
R. J. Williams ◽  
N. R. Dollahon ◽  
E. Larsen ◽  
S. O’Neill ◽  
R. Chapman

In studies of several families of aquatic heteropterans we have found exoskeletal pits not described in the literature. These structures are associated with the lateral margins of the pronotum and/or the dorsal surface, posterior to the scutellum in notonectids, nepids, and corixids. The function of these pits is unknown, but we presumed that they might be either sensory or secretory in nature. We undertook this study of the microscopy of pits in the notonectid, Buenoa margaritacea to learn if either of these functions is consistent with the fine structure.For TEM, adult insects were submerged in 1.0% paraformaldeyde and 2.0% glutaraldehyde in 0.02M sodium cacodylate buffer with 0.01% calcium chloride at a pH of 7.2, then dissected with a razor blade cleaned with acetone. Tissues were fixed overnight at 4°C in paraformaldehyde and glutaraldehyde, then fixed in 1% osmium tetroxide in cacodylate buffer, dehydrated in a graded series of acetone, embedded in Spurr resin and polymerized at 70°C for 21 hours. Blocks were thin sectioned with a diamond knife, and sections were stained with uranyl acetate and lead citrate. Whole specimens for SEM were similarly fixed, dehydrated in an ethanol series and critical point dried. SEM micrographs of internal pit anatomy were produced by adhering 500nm sections to a glass coverslip, then removing the embedding resin by incubation for 5 minutes in a saturated solution of potassium hydroxide in absolute ethanol, followed by three 20 minute rinses in absolute ethanol and air drying. Cover slips were attached to an aluminum specimen stub and sputter coated for 60 seconds with gold/palladium as were whole insects .

Author(s):  
Patricia L. Jansma

The presence of the membrane bound vesicles or blebs on the intestinal epithelial cells has been demonstrated in a variety of vertebrates such as chicks, piglets, hamsters, and humans. The only invertebrates shown to have these microvillar blebs are two species of f1ies. While investigating the digestive processes of the freshwater microcrustacean, Daphnia magna, the presence of these microvillar blebs was noticed.Daphnia magna fed in a suspension of axenically grown green alga, Chlamydomonas reinhardii for one hour were narcotized with CO2 saturated water. The intestinal tracts were excised in 2% glutaraldehyde in 0.2 M cacodyl ate buffer and then placed in fresh 2% glutaraldehyde for one hour. After rinsing in 0.1 M cacodylate buffer, the sample was postfixed in 2% OsO4, dehydrated with a graded ethanol series, infiltrated and embedded with Epon-Araldite. Thin sections were stained with uranyl acetate and Reynolds lead citrate before viewing with the Philips EM 200.


Author(s):  
Y. R. Chen ◽  
Y. F. Huang ◽  
W. S. Chen

Acid phosphatases are widely distributed in different tisssues of various plants. Studies on subcellular localization of acid phosphatases show they might be present in cell wall, plasma lemma, mitochondria, plastid, vacuole and nucleus. However, their localization in rice cell varies with developmental stages of cells and plant tissues. In present study, acid phosphatases occurring in root cap are examined.Sliced root tips of ten-day-old rice(Oryza sativa) seedlings were fixed in 0.1M cacodylate buffer containing 2.5% glutaraldehyde for 2h, washed overnight in same buffer solution, incubated in Gomori's solution at 37° C for 90min, post-fixed in OsO4, dehydrated in ethanol series and finally embeded in Spurr's resin. Sections were doubly stained with uranyl acetate and lead citrate, and observed under Hitachi H-600 at 75 KV.


Author(s):  
C. W. Mims ◽  
E. A. Richardson

The advantages of freeze substitution fixation over conventional chemical fixation for preservation of ultrastructural details in fungi have been discussed by various authors. As most ascomycetes, basidiomycetes and deuteromycetes do not fix well using conventional chemical fixation protocols, freeze substitution has attracted the attention of many individuals interested in fungal ultrastructure. Thus far most workers using this technique on fungi have concentrated on thin walled somatic hyphae. However, in our laboratory we have experimented with the use of freeze substitution on a variety of fungal reproductive structures and spores with promising results.Here we present data on freeze substituted samples of sporangia of the zygomycete Umbellopsis vinacea, basidia of Exobasidium camelliae var. gracilis, developing teliospores of the smut Sporisorium sorghi, germinating teliospores of the rust Gymnosporangium clavipes, germinating conidia of the deuteromycete Cercosporidium personatum, and developing ascospores of Ascodesmis nigricans.Spores of G. clavipes and C. personatum were deposited on moist pieces of sterile dialysis membrane where they hydrated and germinated. Asci of A. nigricans developed on pieces of dialysis membrane lying on nutrient agar plates. U. vinacea was cultured on small pieces of agar-coated wire. In the plant pathogens E. camelliae var. gracilis and S. sorghi, a razor blade was used to remove smal1 pieces of infected host issue. All samples were plunged directly into liquid propane and processed for study according to Hoch.l Samples on dialysis membrane were flat embedded. Serial thin sections were cut using a diamond knife, collected on slot grids, and allowed to dry down onto Formvar coated aluminum racks. Sections were post stained with uranyl acetate and lead citrate.


Author(s):  
C. C. Chen ◽  
Y. R. Chen

Two major ways of water discharge from plant leaves are vapour transpiration and liquid guttation through stomata and hydathodes, resptectively. However, besides pure water, guttation fluid contains various salts, sugars and other organic substances which cause injury to plants through their accumulation on leaf surface. Functionally, hydathodes not only play an important role on water excretion but also on retrieval of minerals and their structures are different from those of stomata, even though both have same phylogenic origin. In the present study, the distribution, strcuture, and cytology of hydathodes and stomata of Fisuc formosana Maxim were reported.Leaf blades of fully expanded leaf were cut with a razor blade into small cubes in fixation buffer containing 2.5% glutaraldehyde. These were transfered to fresh fixation buffer for 2 h, postfixed in 1% osmium tetraoxide for 4 h, dehydrated through an ethanol series, and then infiltrated and embedded in Spurr's resin. Sections in golden color were collected on grids, doubly stained with uranyl acetate and lead citrate, and observed with a Hitachi H-600 transmission electron microscope (TEM).


Author(s):  
A. Julio Martinez ◽  
Richard J. Duma ◽  
Doris G. Fultz ◽  
Ruth B. Finley

Ultrastructural components of trophozoites and cysts of Acanthamoeba-Hartmannella (A-H) and Naegleria amebas have been investigated. The present report describes a technique to study the morphological features of such protozoa.The A-H strains selected were cultured for 7 days in axenic amebic media, and the Naegleria strains were cultured for 7 days in axenic media with blood. In situ fixation was accomplished by adding an equal volume of 4% Osmic Acid in Cacodylate buffer at 4¶C for one hour. Following frequent agitation, the tubes were then spun at 2500 RPM for 10 minutes to obtain a pellet. The pellets were dehydrated in graded series of alcohols (from 50% to absolute) and propylene oxide and then embedded in EPON. One micron sections were stained with Paragon (PS 1301) for thirty seconds. Thin sections were cut with a diamond knife, double stained with 5% alcoholic uranyl acetate solution and lead citrate and observed in an Hitachi-HS-8F2 electron microscope.


Author(s):  
William H. Zucker

Planktonic foraminifera are widely-distributed and abundant zooplankters. They are significant as water mass indicators and provide evidence of paleotemperatures and events which occurred during Pleistocene glaciation. In spite of their ecological and paleological significance, little is known of their cell biology. There are few cytological studies of these organisms at the light microscope level and some recent reports of their ultrastructure.Specimens of Globigerinoides ruber, Globigerina bulloides, Globigerinoides conglobatus and Globigerinita glutinata were collected in Bermuda waters and fixed in a cold cacodylate-buffered 6% glutaraldehyde solution for two hours. They were then rinsed, post-fixed in Palade's fluid, rinsed again and stained with uranyl acetate. This was followed by graded ethanol dehydration, during which they were identified and picked clean of debris. The specimens were finally embedded in Epon 812 by placing each organism in a separate BEEM capsule. After sectioning with a diamond knife, stained sections were viewed in a Philips 200 electron microscope.


Author(s):  
Amankwah K.S. ◽  
A.D. Weberg ◽  
R.C. Kaufmann

Previous research has revealed that passive (involuntary inhalation) tobacco smoking during gestation can have adverse effects upon the developing fetus. These prior investigations did not concentrate on changes in fetal morphology. This study was undertaken to delineate fetal neural abnormalities at the ultrastructural level in mice pups exposed in utero to passive maternal smoking.Pregnant study animals, housed in a special chamber, were subjected to cigarette smoke daily from conception until delivery. Blood tests for determination of carbon monoxide levels were run at 15-18 days gestation. Sciatic nerve tissue from experimental and control animals were obtained following spontaneous delivery and fixed in 2.5% gluteraldehyde in 0.1M cacodylate buffer pH 7.3. The samples were post-fixed in osmium ferrocyanide (1:1 mixture of 1.5% aqueous OSO4 and 2.5% K4 Fe(CN)6). Following dehydration, the tissues were infiltrated with and embedded in Spurr. Sections were stained with uranyl acetate and lead citrate.


Author(s):  
M. Kessel ◽  
R. MacColl

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.


Author(s):  
Li-Chu Tung ◽  
Yung-Reui Chen ◽  
Shiu-Nan Chen ◽  
Guang-Hsiung Kuo

In the present study, the ultrastructural changes of BPK cells, a fibroblast-like cell line, derived from the kidney of juvenile black porgy Acanthopagrus schlegeli, under heat shock treatment are described.The BPK cells were maintained in L-15 medium supplemented with 10% fetal calf serum and 0.15 M NaCl at 28|C2. The heating was carried out in precalibrated water baths. Monolayers of cells, grown on coverslips in parafilm-sealed petri dishes were submerged under water for 30 min at 40|C treatments. Cells were fixed in 2.5% glutaraldehyde in 0.1 M cacodylate buffer supplemented with 6.6% sucrose, postfixed in 1% OsO4 and flat embedded in Spurr’s resin. Silver section were cut parallel to the substratum, stained with uranyl acetate and Reynold’s lead citrate, and examined in a Hitachi H-600 electron microscope at 75 KV.


Author(s):  
Hsin-Kan Wu ◽  
Mei-Chu Chung

In one of our earlier papers (Wu et al. 1978), we suggested that glutelin is the major composition of the round storage protein bodies although they also contain relatively more prolamine than the angular one does. Immunochemical studies of Krishnan et al. (1986) later showed the presence of glutelin in the irregularly-shaped (angular) protein bodies while the prolamines were found in the round ones. Our recent experiment using protein A-gold technique found that prolamine is mainly deposited into the angular protein bodies.Small blocks (1 mm3) of 7 DAF (days after flowering) caryopsis of Orvza perennis were fixed with 3% paraformaldehyde and 3% glutaraldehyde in 0.1M sodium phosphate, pH7.4, dehydrated in a graded ethanol series and infiltrated with Spurr’s resin. Thin sections, after gold labeling, were stained with uranyl acetate and lead citrate. Rabbit antibodies were raised against purified prolamine. Protein A-gold sol complex was prepared based on the technique of Horisberger et al. (1977).


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