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A transmission electron microscopic (TEM) study was conducted on maturing wheat to determine the sequences of events involved during the drying of preripe starchy endosperm. Field-grown hard red winter wheat Karl and soft red winter wheat Clark were harvested at 21 days after flowering (DAF) and air-dried in the spike at 20°C for 2, 4, 8, 12, 24, 48, and 96 hr and until completely air-dried (7 days). Fresh samples of Karl and Clark were also harvested and prepared immediately for microscopy. Both wheat cultivars underwent similar changes during drying. Few changes were observed during the first 8 hr of drying. By 12 hr after the start of drying, the rough endoplasmic reticulum (RER) was distended and circularized. Protein bodies were irregular in shape and small autophagic vacuoles were found in the cytoplasm. An amorphous material was first observed in areas of the cytoplasm after 24 hr of drying. RER was typically associated with those regions. Endosperm tissue looked nearly mature after 48 hr ...

The effect of high temperature on starch accumulation, starch granule populations, and expression of genes encoding key enzymes for starch biosynthesis was examined during grain development in wheat (Triticum aestivum L. cv. Butte 86). High temperature applied from anthesis to maturity reduced the duration of starch accumulation. Starch accumulation ceased approximately 6 days earlier for grain produced under a 37/17 8C (day/night) regimen and 21 days earlier under a 37/28 8C (day/night) regimen than for grain produced under a 24/17 8C (day/night) regimen. Compared to the 24/17 8C regimen, starch content was approximately 19% less for mature grain produced under the 37/17 8C regimen and 58% less under the 37/28 8C regimen. Based on relative volume, the smaller type B starch granules were the predominant class in mature grain produced under the 24/17 and 37/17 8C regimens, whereas the larger type A granules were predominant in grain produced under the 37/28 8C regimen. Under the 24/17 8C regimen, steady state transcript levels for ADP-glucose pyrophosphorylase, starch synthases I, II, and III, granule-bound starch synthase, and starch branching enzymes I and II were highest from 12/16 days post-anthesis (dpa). Under the 37/17 8C regimen, steady state levels of these transcripts followed the same temporal pattern, but were substantially lower. Under the 37/28 8C regimen, transcript levels peaked earlier, at 7 dpa. The high temperature regimens reduced the relativ el evels of transcripts for starch synthase more than the other starch biosynthetic enzymes. Published by Elsevier Science Ireland Ltd.

Plastids in the coenocytic endosperm of young wheat caryopses were mostly in the form of pleomorphic proplastids with a few of the plastids containing small starch granules. Following cellularization of the coenocytic cytoplasm, the outer one or two endosperm cell layers became meristematic and continued to divide until about 14 days after flowering (DAF). During the first week of endosperm development, newly divided cells had plastids that were pleomorphic in shape, while subaleurone cells interior to the meristematic region contained amyloplasts that contained a single-size class of starch granules (incipient A-type starch granules). The pleomorphic plastids exhibited tubular protrusions that extended a considerable distance through the cytoplasm. Amyloplasts in cells interior to the meristematic region did not exhibit protrusions. Both subaleurone and central endosperm cells had amyloplasts that exhibited protrusions at 10–12 DAF, and some of the protrusions contained small starch granules (in...

A starch isolation method and digital image analysis system were developed to accurately measure size distributions of the starch populations in wheat. The image analysis system was coupled directly to a light microscope equipped with computer controlled step stage and automatic focus. Automation of data acquisition and processing eliminated some of the labor intensive steps previously required for analyzing starch granule size distributions. This system was used to standardize starch isolation methods and compare variation and precision of the system. Operational variations were determined and statistically assessed. The number of fields of view required for low standard errors and acceptable speed of analysis was determined to be fifty. A major advantage of the system has been the increased resolution. The use of higher magnifications and stage automation allowed the analysis of starch granules as small as 0.84 μm in diameter while analyzing thousands of starch granules per sample.

Wheat contaminated with teliospores of Tilletia controversa Kuhn (TCK) was mixed with uncontaminated wheat and processed through the Kansas State University pilot mill. Two 50-bu lots of the contaminated mixture were cleaned, tempered, and milled. Approximately 500 samples of wheat, cleanings, and mill fractions were collected and examined for the presence of intact and broken TCK teliospores. Whole wheat samples (50 g) were washed, sieved through a 60-μm nylon sieve, and pelleted by centrifugation. Contents of the pellet were examined microscopically for the presence of TCK spores. The procedure was modified as needed to accommodate cleanings and mill fractions. Levels of spore contamination in whole wheat samples decreased at each step during the handling process, and large numbers of spores were found in materials that were sieved or aspirated from the grain. Very few spores were found in bran, germ, and shorts; none were detected in red dog or straight-grade flour. The results showed that a h...

The histopathology of Entomophaga grylli pathotype 2-infected tissues was investigated. Fat body, male reproductive system, gastrointestinal tract, central nervous system, and skeletal muscle of infected and uninfected grasshoppers were compared to determine the pathological events during the infection. The pathotype 2 protoplasts adhered to fat body and penetrated neural tissue early in the infection, whereas the skeletal muscle was penetrated after host death. Ultrastructural examination of infected fat body suggested one contributing cause of death was nutrient depletion.

Light and electron microscopic observations were made of protoplast changes during Entomophoga grylli pathotype 2 infections of Melanoplus differentialis. Protoplast development was divided into three stages: amoeboid, developing, and mature protoplasts. Each stage was characterized by changes in protoplast and organelle morphology. Amoeboid protoplasts were amoeboid in shape, exhibited movement, and contained very few lipid droplets. Developing and mature protoplasts were rounded in shape and contained increasing amounts of lipid droplets. Morphological changes were also observed in dense bodies, nuclei, and cell membrane as the protoplasts matured.

Ten milled rices differing in starch properties were extrusion cooked through a twin screw extruder at 15% moisture and 120, 135 and 150°C. Instron hardness values of extrudate were lowest at 150°C. Extrusion cooking drastically reduced viscosity in 0·2 n KOH and in water without any decrease in amylose content and with little increase in reducing sugars. Spherical protein bodies were intact in the protein masses uniformly dispersed in the gelatinized starch matrix. Amylose content and gel consistency of raw rice flour were significantly correlated with expansion ratio only at 135°C, water absorption and solubility indexes at all temperatures and with gel viscosity of extrudates. Only gel consistency of raw flour correlated with cold paste viscosity of extrudate. Final gelatinization temperature of starch was not significantly correlated with any extrudate property.

Protein bodies (PB) were prepared from IR480-5-9 (10.5% protein) milled rice by destarching the cooked rice flour with crystalline bacterial α-amylase. Corresponding PB from raw rice prepared by treatment with analytical grade glucoamylase were more susceptible to pepsin digestion than PB from cooked rice. The undigested residue from pepsin digestion of both cooked and raw rice PB and preparations of fecal protein particles from man and rat on an IR480-5-9 cooked milled rice diet represented the core of PB. The core protein was poorer in lysine and had lower mol. wt. subunits than whole PB protein. The pepsin-digested PB preparations had higher fat content than whole PB preparation.

(1980). Ultrastructure, Physiology, and Biochemistry of Bacillus Thuringiensis. CRC Critical Reviews in Microbiology: Vol. 8, No. 2, pp. 147-204.

A B S T R A C T The spore wall of the myxomycete, Physarella oblonga, requires only 1 hr to develop. The spore wall surface ornamentations, the warts, are secreted first, followed by an outer electrondense layer and an inner electron-lucent layer. A measurement analysis was conducted to determine if vesicles were involved in wall elaboration. By comparing spore plasmalemma length to the number of fused vesicles, a semi-quantitative analysis can be obtained. The determination reveals that very few vesicles are associated with wart and outer wall development. The greatest number of vesicles are associated with inner wall secretion. Plasmalemmasomes are most numerous during outer wall formation and Golgi bodies are observed only during inner wall elaboration. Other organelles do not seem directly involved in wall secretion. ULTRASTRUCTURAL INVESTIGATIONS of myxomy

Nuclear degeneration is a distinct and normal process occurring during sporogenesis in the myxomycete,Physarella oblonga. About 30% of the nuclei present in the developing sporangium abort. Nuclei that undergo degeneration are first surrounded by vacuoles. The membranes of the vacuoles and nuclear envelope are 75 Ā thick. As degeneration progresses the vacuoles fuse resulting in a nucleus surrounded by a single, narrow vacuole. The membrane next to the nucleus degenerates while the membrane adjacent to the sporangial cytoplasm thickens to 100 Ā. Lysosomes then fuse with the vacuole, and digestion of the nucleus begins. The undigested remains of nuclei (residual bodies) are excreted from the protoplast. Acid phosphatase is localized in the lysosomes and degenerating nuclei.

The presence of dictyosomes secreting densely stained vesicles throughout endosperm protein body formation was confirmed for four cereals (rice, Oryza sativa L.; hard red winter wheat, Triticum aestivum L.; winter feed barley and spring malting barley, Hordeum vulgare L.; oats, Avena sativa L.). The contents of the Golgi vesicles and protein bodies were digested with proteases for all cereals except rice. It was found in the case of rice that OsO4 altered the proteins in the Golgi apparatus and protein bodies making them resistant to protease digestion. These results imply that the Golgi apparatus plays an important role in the concentration and transport of storage proteins into vacuoles. SYNTHESIS OF STORAGE PROTEINS in cereal starchy endosperm involves the rough endoplasmic reticulum (RER) (Cameron-Mills and Ingversen, 1978; Cameron-Mills, Ingversen and Brandt, 1978; Larkins and Hurkman, 1978). The RER in some cereal endosperms may serve not only as the site of protein synthesis, but also function as the storage organelle (protein body; Larkins and Hurkman, 1978; Bechtel and Juliano, 1980). Cereals studied to date, however, have had at least some of the endosperm protein shown to be deposited into vacuoles (see Bechtel and Juliano, 1980, for a review). The mechanism of protein deposition into vacuoles has been under debate. Buttrose (1963) suggested that the Golgi apparatus participated in protein secretion into vacuoles in wheat endosperm. Khoo and Wolf (1970) thought that dictyosomes of corn proliferated protein granule vesicles. These suggestions were challenged by Barlow, Lee and Vesk (1974) and Briarty (1978), however. Vacuolar protein in rice endosperm was thought to occur via a direct connection between the RER and vacuoles (Ivanova, 1974). Wu and Chen (1978) concluded that Golgi secretory vesicles in rice endosperm could not be involved in protein transport because the vesicles lacked protein; yet their fig. 5 and 6 depict pepsin digestion -of secretory vesicles. Re1 Received for publication 13 July 1981; revision accepted 17 September 1981. 2 Contribution No. 81-459j, Division of Biology, Kansas Agricultural Experiment Station, Manhattan, KS 66506. Reference to a company or product does not imply approval or recommendation of the product by the U.S. Department of Agriculture to the exclusion of others that may be suitable. cently the Golgi apparatus has been again implicated in protein secretion in starchy endosperm of rice (Bechtel and Juliano, 1980). We chose to study protein body formation in four cereals (rice, Oryza sativa L.; hard red winter wheat, Triticum aestivum L.; winter feed barley and spring malting barley, Hordeum vulgare L.; oats, Avena sativa L.) because of the lack of agreement as to how deposition of protein into vacuoles occurs, whether the Golgi apparatus is present during protein secretion, and whether Golgi vesicles contain protein. This paper is a preliminary report on the occurrence of the Golgi apparatus in endosperm during protein synthesis and the enzymatic digestion of thin sections containing dictyosomes. Complete developmental studies of these cereals have either been reported or will be presented shortly (Bechtel and Juliano, 1980; Bechtel, Gaines and Pomeranz, 1980). MATERIALS AND METHODS-Rice, experimental high protein cultivar IR 480, was sectioned from samples used in a previous study (Bechtel and Juliano, 1980). Barley cultivars 'Larker' (spring malting barley) and 'Kanby' (winter feed barley), wheat cultivar 'Eagle', and Illinois 73-21-86 oats were all grown during the 1978 and 1980 seasons on experimental maturity plots near Manhattan, KS. Caryopses were sampled at day of flowering (DOF), 2, 4, 6, 7, 8, 10, 12, 14, 17, 21, 24, and 27 days after flowering (DAF) and fixed in a combination of 3% glutaraldehyde (v/v) and 3% paraformaldehyde (w/v) in 0.05 M phosphate buffer (Lillie, 1954) at pH 6.7, postfixed in buffered OSO4 and embedded as previously described (Bechtel

Transmission electron micrographs of glutaraldehyde- OsO 4 -fixed Rhizobium trifolii 0403 before and after cells were treated with 16.6 mM succinate showed that treated cells increased in mass by increasing cytoplasmic volume. The morphology of succinate-treated cells was identical to that of bacteroids, and the appearances of the envelope and periplasmic space were similar. The primary difference was in inclusion number and type.

A comprehensive ultrastructural analysis of sporulation and parasporal crystal development is described for Bacillus thuringiensis . The insecticidal crystal of B. thuringiensis is initiated at the start of engulfment and is nearly complete by the time the exosporium forms. The crystal and a heretofore unobserved ovoid inclusion develop without any clear association with the forespore septum, exosporium, or mesosomes. These observations contradict previous hypotheses that the crystal is synthesized on the forespore membrane, exosporium, or mesosomes. Formation of forespore septa involves densely staining, double-membrane-bound, vesicular mesosomes that have a bridged appearance. Forespore engulfment is subpolar and also involves mesosomes. Upon completion of engulfment the following cytoplasmic changes occur: decrease in electron density of the incipient forespore membrane; loss of bridged appearance of incipient forespore membrane; change in stainability of incipient forespore, forespore, and mother cell cytoplasms; and alteration in staining quality of plasma membrane. These changes are involved in the conversion of the incipient forespore into a forespore and reflect “commitment” to sporulation.