Fluorescence staining of living cells with fluorescamine.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
B A Palevitz
Publications and source records attributed to B A Palevitz.
Polarity of actin filaments in Characean algae.
Heavy meromyosin from rabbit muscle combines with oriented Nitella and Chara actin in vitro to form arrowhead structures directed opposite to the cytoplasmic flow in the living plant cell. All filaments and all bundles of filaments in the apically directed stream are similarly oriented; polarity with respect to the axis of the thallus is reversed in the downward stream. The actin filaments are attached to the chloroplasts at the ectoplasm-endoplasm interface, where the motive force for streaming is known to be generated.
Actins↗
Structure and development of P-protein in phloem parenchyma and companion cells of legumes.
Phloem parenchyma and companion cells from four species of legumes, Phaseolus vulgaris L., Melilotus alba Desr., Desmodium canadense, L. and Dolichos lablab L., were examined electron microscopically to estabish the presence, structure and development of P-protein. P-protein components consisting of granular, fibrillar, tubular or crystalline structures were found in parenchyma cells of all species and in companion cells of M. alba. The earliest stages of P-protein formation were closely associated with dictyosome cisternae, dictyosome vesicles and/or spiny vesicles. After their formation, the P-protein bodies were frequently transformed into one or more structurally different components. Although these components appeared to be develop-mentally related, their specific associations and transformations differed in each species examined.
Inclusion Bodies↗
Identification of actin in situ at the ectoplasm-endoplasm interface of Nitella. Microfilament-chloroplast association.
Using a glycerination procedure designed to avoid excessive plasmolysis or disruption of the ectoplasm, microfilaments in bundles at the ectoplasm-endoplasm interface of Nitella internode cell segments were found to bind rabbit heavy meromyosin (HMM) in situ. All HMM arrowheads in a bundle seem to have the same polarity and many lie in register as judged from the electron micrographs; the arrowhead periodicity is approximately 380 . The decorated microfilaments are thus similar to those seen in negatively stained cytoplasmic suspensions of internode cells. In glycerinated material, as well as in suspensions, the microfilaments are closely associated with chloroplasts. The microfilaments lie adjacent to or are attached to the chloroplast envelope. The results provide further evidence that the microfilaments thought to play a role in cytoplasmic streaming in vivo in Nitella consist of actin and suggest that they may be anchored to the chloroplasts.
Actins↗
Actin in the green alga, Nitella.
Bundles of microfilaments very similar in appearance to actin are present in cytoplasmic suspensions obtained from Nitella flexilis. The microfilaments bind rabbit heavy meromyosin in arrowhead arrays similar to those produced on muscle actin. The arrowheads are removed with ATP. The results provide evidence that actin is present in green plants, probably in the form of microfilaments thought to be involved in cytoplasmic streaming.
Actins↗
A study of sieve element starch using sequential enzymatic digestion and electron microscopy.
The fine structure of plastids and their starch deposits in differentiating sieve elements was studied in bean (Phaseolus vulgaris L.). Ultrastructural cytochemistry employing two carbohydrases specific for different linkages was then used to compare the chemical nature of "sieve tube starch" (the starch deposited in sieve elements) with that of the ordinary starch of other cell types. Hypocotyl tissue from seedlings was fixed in glutaraldehyde, postfixed in osmium tetroxide, and embedded in Epon-Araldite. Treatment of thin sections on uncoated copper grids with alpha-amylase or diastase at pH 6.8 to cleave alpha-(1 --> 4) bonds resulted in digestion of ordinary starch grains but not sieve element grains, as determined by electron microscopy. Since alpha-(1 --> 6) branch points in amylopectin-type starches make the adjacent alpha-(1 --> 4) linkages somewhat resistant to hydrolysis by alpha-amylase, other sections mounted on bare copper or gold grids were treated with pullulanase (a bacterial alpha-[1 --> 6] glucosidase) prior to digestion with diastase. Pullulanase did not digest sieve element starch, but rendered the starch digestible subsequently by alpha-amylase. Diastase followed by pullulanase did not result in digestion. The results provide evidence that sieve element starch is composed of highly branched molecules with numerous alpha-(1 --> 6) linkages.
Aldehydes↗