Chloroplasts in Living Cells and the String-of-Grana Concept of Chloroplast Structure Revisited.

In 1980, Wildman et al. (Bot Gaz 141: 24-36) proposed a three-dimensional model for chloroplast structure whereby the grana were arranged in non-overlapping rows, like beads on a string. This string-of-grana model was developed from phase microscope analysis of living cells and partially disrupted, isolated chloroplasts.

Extended leukocyte parameters for hematology analyzers.

Newly introduced, extended leukocyte parameters on laser-based hematology analyzers permit normal samples to be readily identified allowing these samples to be excluded from manual analysis. This enables more hematology laboratory resources to be focused on abnormal specimens. A new reagent that lyses erythrocytes while leaving the optical properties of the leukocytes unaltered is used.

Controls for flow cytometers in hematology and cellular immunology.

The necessity of using freshly prepared biological samples to control and calibrate flow cytometers has impeded the utilization of flow cytometry in the clinical laboratory where regulations demand careful control calibration and yet workload and technician training militate against the preparation of specialized control samples. For a number of years, cell preparations with stabilized properties have been used routinely in hematology laboratories to evaluate the daily performance of automated blood cell counters including optical flow cytometers. Unfortunately, the stabilized preparations do not necessarily duplicate many important aspects of whole blood, resulting in variable performance of a given control preparation on different types of instrumentation.

Automated analysis of reticulocytes using fluorescent staining with both acridine orange and an immunofluorescence technique.

We have used an automated system to measure serial reticulocyte samples from phlebotomized rats and rats treated with the chemotherapeutic agent actinomycin-D. In performing the automated samples, we utilized two different methods. The first method employed a fluorescent dye, acridine orange, which stains RNA in a manner similar to supravital stains presently used in performing reticulocyte counts.

Chill-induced morphological alterations in Anacystis Nidulans as a function of growth temperature.

Cells of Anacystis nidulans grown at 25 or 30°C were examined both by thin-section and freeze-fracture electron microscopy. Cells grown at either temperature appeared similar when fixed at the growth temperature prior to observation. When cells were chilled to near 0°C for 30 min prior to fixation, those previously grown at 25° appeared unchanged as judged by thin sectioning while those grown at 39° showed considerable morphological alteration.

Interpreting the results of freeze-etching.

Morphological data obtained by freeze-fracturing and other low temperature techniques must be interpreted in terms of molecular organization and function. Interpretation is aided by physical and biochemical approaches. Physical approaches such as rotary replication and ultralow temperature fracturing can improve resolution and preserve molecular arrangements which are difficult or impossible to observe with standard freeze-etching techniques.

Comparative Studies of the Thylakoid Proteins of Mesophyll and Bundle Sheath Plastids of Zea mays.

The proteins from both grana and stroma lamellae of maize (Zea mays) mesophyll plastids and from maize bundle sheath plastid membranes have been compared by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels using a discontinuous buffer system. Peptide differences between grana and stroma lamellae were essentially quantitative and not qualitative. Bundle sheath plastid membrane peptides more closely resembled those of the ultrastructurally similar stroma lamellae.