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1.
Ann M Dvorak 《The journal of histochemistry and cytochemistry》2005,53(9):1043-1070
Ultrastructural studies of human mast cells (HMCs) and basophils (HBs) are reviewed. Sources of HMCs include biopsies of tissue sites and in situ study of excised diseased organs; isolated, partially purified samples from excised organs; and growth-factor-stimulated mast cells that develop de novo in cultures of cord blood cells. Sources of HBs for study include partially purified peripheral blood basophils, basophils in tissue biopsies, and specific growth factor-stimulated basophils arising de novo from cord blood cells. The ultrastructural studies reviewed deal with identity, secretion, vesicles, recovery, and synthesis issues related to the biology of these similar cells. 相似文献
2.
Indirect evidence suggests that legumes can adjust rapidly theresistance of their root nodules to O2 diffusion. Here we describeexperiments using O2 specific micro-electrodes and dark fieldmicroscopy to study directly the operation of this diffusionbarrier. The O2 concentration sensed by the electrode decreasedsharply in the region of the inner cortex and was less than1.0 mmol m3 throughout the infected tissue in nodulesof both pea (Pisum sativum) and french bean (Phaseolus vulgaris).In a number of experiments the ambient O2 concentration wasincreased to 40% while the electrode tip was just inside theinner cortex. In 13 out of 21 cases the O2 concentration atthis position either remained low and unchanged or increasedirreversibly to near ambient values. In the remaining casesthe O2 concentration increased after 1 to 2.5 min and then decreasedto its former value. These results are ascribed to an increasein resistance of the barrier in response to increased O2 fluxinto the nodule. It was shown microscopically that air spacesboth at the boundary between the infected zone and the innercortex, and within the infected zone started to disappear 3min after nodules were exposed to high ambient O2 concentrationsand had disappeared completely after 8 min. These spaces werenot changed by exposure of the nodule for 10 min to either N2or air. Key words: Oxygen, root nodules, air spaces 相似文献
3.
A M Dvorak R A Monahan-Earley H F Dvorak S J Galli 《The journal of histochemistry and cytochemistry》1987,35(3):351-360
We used ultrastructural autoradiographic and cytochemical methods to localize esterase activities in unstimulated guinea pig basophils and in basophils undergoing degranulation or recovery from degranulation. We used tritium-labeled diisopropylfluorophosphate (DFP) as a probe for serine enzymes and localized this probe by ultrastructural autoradiography to cytoplasmic granules of immature or mature unstimulated basophils, as well as to granules released by degranulating basophils. Ultrastructural cytochemistry using alpha naphthyl acetate (ANA) as substrate localized nonspecific esterase activity to extruded granules, either within the interiors of degranulation sacs or within granules completely separated from degranulating basophils. Extruded granules retained their esterase activity for as long as 24 hr after antigen-induced degranulation. The plasma membranes of unstimulated or degranulating basophils, as well as of basophils recovering from degranulation, displayed prominent cell surface ANA esterase ectoenzyme activity. Lipid bodies, organelles present in the cytoplasm of both control and recovering basophils, were also alpha naphthyl acetate esterase (ANAE)-positive. Thus, cytochemical and autoradiographic techniques localized esterase and/or [3H]-DFP-binding activities to cytoplasmic granules, lipid bodies, and cell surface of basophils, and these enzyme activities persisted during both degranulation and recovery from degranulation. 相似文献
4.
Evolution of the 28S ribosomal RNA gene in anurans: regions of variability and their phylogenetic implications 总被引:1,自引:0,他引:1
Fifteen restriction sites were mapped to the 28S ribosomal RNA gene of
individuals representing 54 species of frogs, two species of salamanders, a
caecilian, and a lungfish. Eight of these sites were present in all species
examined, and two were found in all but one species. Alignment of these
conserved restriction sites revealed, among anuran 28S rRNA genes, five
regions of major length variation that correspond to four of 12 previously
identified divergent domains of this gene. One of the divergent domains
(DD8) consists of two regions of length variation separated by a short
segment that is conserved at least throughout tetrapods. Most of the
insertions, deletions, and restriction-site variations identified in the
28S gene will require sequence-level analysis for a detailed reconstruction
of their history. However, an insertion in DD9 that is coextensive with
frogs in the suborder Neobatrachia, a BstEII site that is limited to
representatives of two leptodactylid subfamilies, and a deletion in DD10
that is found only in three ranoid genera are probably synapomorphies.
相似文献
5.
We describe an algorithm, Vout = Integer ([2(12)-1/2(12 lambda)-1] V lambda in-1) + 1; lambda greater than 0 based upon Box-Cox transformations as an alternative to nonlinear electronic amplifiers to expand or compress high- or low-amplitude flow cytometer-derived signals. If the indexing parameter lambda less than 1, input channels in the high-amplitude input range are compressed in the output range as occurs when an electronic logarithmic amplifier is used. However, if lambda greater than 1, input channels in the low-amplitude input range are compressed in the output range as occurs when an electronic power amplifier is used. Our modified Box-Cox transform can be implemented either during data collection or off-line for the transformation of previously collected raw data. The transform is the equivalent of an infinite class of nonlinear amplifiers. As the transform is implemented in software, it does not suffer from many of the disadvantages of nonlinear electronic amplifiers. 相似文献
6.
C57B1/6 mice were infected with Brasil strain Trypanosoma cruzi trypomastigotes. The leg muscles of the mice were serial-sectioned with a cryostat, and individual fibers were classified histochemically as type I or type II on the basis of succinic dehydrogenase or adenosine triphosphatase activity. Although markedly more type II fibers were present in the leg muscles, the percentage of infected type I fibers was nearly five-fold higher than type II. This is the first demonstration of a preferential in vivo distribution of T. cruzi in muscle fibers based upon muscle type. 相似文献
7.
C57B1/6 mice were infected with Brasil strain Trypanosoma cruzi trypomastigotes. The leg muscles of the mice were serial-sectioned with a cryostat, and individual fibers were classified histochemically as type I or type II on the basis of succinic dehydrogenase or adenosine triphosphatase activity. Although markedly more type II fibers were present in the leg muscles, the percentage of infected type I fibers was nearly five-fold higher than type II. This is the first demonstration of a preferential in vivo distribution of T. cruzi in muscle fibers based upon muscle type. 相似文献
8.
Intracellular recordings combined with iontophoretic injection of Procion Yellow M4RAN were used to study the anatomy and physiology of the centrifugal horizontal cells (CH-cells) in the lobula plate of the blowfly, Phaenicia sericata.Anatomy: The CH-cells comprise a set of two homolateral, giant visual interneurones (DCH, VCH) at the rostral surface of each lobula plate. Their extensive arborizations in the lobula plate possess bulbous swellings (boutons terminaux). The arborization of one cell (DCH) covers the dorsal, and the arborization of the other cell (VCH) the ventral half of the lobula plate. Their axons run jointly with those of the horizontal cells through the chiasma internum and the optic peduncle. Their protocerebral arborization possesses spines; they form a dense network together with the axonal arborization of the horizontal cells, a second type of giant homolateral cell most sensitive to horizontal motion. The protocerebral arborization of the CH-cells gives rise to a cell body fibre which traverses the protocerebrum dorsally to the oesophageal canal. The cell body lies on the contralateral side laterally and slightly dorsally to the oesophageal canal in the frontal cell body layer.Physiology: The CH-cells respond with graded potentials to rotatory movements of their surround. Cells in the right lobula plate respond with excitation (excitatory postsynaptic potentials, membrane depolarization) to clockwise motion (contralateral regressive, ipsilateral progressive), and with inhibition (inhibitory postsynaptic potentials, membrane hyperpolarization) to counterclockwise motion in either or both receptive fields; CH-cells respond to motion presented to the ipsilateral and/or contralateral eye. Cells of the left lobula plate respond correspondingly to the reverse directions of motion. Vertical pattern motion and stationary patterns are ineffective.The heterolateral H1-neurone elicits excitatory postsynaptic potentials in the DCH-cell; these postsynaptic potentials are tightly correlated 1:1 to the preceding H1-action potentíal. The delay between the peak of the action potential and the beginning of the DCH-postsynaptic potential is 1.15 msec, agreeing very well with the value reported previously for the blowfly, Calliphora (Hausen, 1976a). The synaptic input and output connections of the CH-cells are discussed. 相似文献
9.
10.
High voltage electrical pulses were used to introduce the CAT reporter gene into cultured protoplasts of breadwheat,Triticum aestivum. Four DNA constructs harboring the CAT gene and the 35S or mannipine synthase promoter were tested for levels of CAT activity 40–45 hr after electroporation of protoplasts. One construct, containing a maize intron sequence between 35S and CAT sequences, conferred 30 to 185 fold greater CAT activity over the other three constructs. Data from these experiments suggest that a maize intron or sequences with similar effects may be required in DNA constructs for efficient heterologous gene expression in cultured cells of breadwheat.Abbreviations CAT
Chloramphenicol acetyl transferase
- NPT II
neomycin phosphotransferase
- 35S
the 35S promoter of Cauliflower Mosaic Virus
- PEG
Polyethylene glycol
- MES
2-[N-morpholino] ethanesulfonic acid 相似文献