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31.
Current information on the structure and function of motile tubular vacuoles in Pisolithus tinctorius and other fungi is reviewed. The use of fluorochromes to label the vacuole lumen is evaluated and observations on the structure and motility of vacuoles in P. tinctorius are differentiated from possible artifacts. The styryl dyes FM4-64 and MDY-64, used in yeast to demonstrate endocytosis, show little or no labeling of internal membranes in undamaged P. tinctorius cells. This agrees with our data showing that other probes for endocytosis such as Lucifer yellow CH are not taken up by hyphal tip cells. Overall, the observations do not support endocytosis in hyphal tips. It has been suggested that tubular vacuole systems carry out longitudinal transport, and evidence in favor of this hypothesis is evaluated. New data are presented to show that many of the large vacuoles in subapical cells are attached to the plasma membrane and are relatively immobile, while video sequences show movement of fluorochrome in pulses along a series of several large vacuoles, all interconnected via tubules. Tubular vacuoles from thick sections of hyphae processed under anhydrous conditions are shown by X-ray microanalysis to contain relatively high levels of P and K, as seen previously in the larger vacuoles. These results provide further evidence for a role of the tubular vacuoles in longitudinal transport of P. Copyright 1998 Academic Press. 相似文献
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Pig to human xenotransplantation is considered a possible solution to the
prevailing chronic lack of human donor organs for allotransplantation. The
Galalpha1,3Gal determinant is the major porcine xenogeneic epitope causing
hyperacute rejection following human antibody binding and complement
activation. In order to characterize the tissue distribution of
Galalpha1,3Gal-containing and blood group- type glycosphingolipids in pig,
acid and nonacid glycosphingolipids were isolated from the kidney, small
intestine, spleen, salivary gland, liver, and heart of a single pig
obtained from a semi-inbred strain homozygous at the SLA locus. Glycolipids
were analyzed by thin-layer immunostaining using monoclonal antibodies, and
following ceramide glycanase cleavage as permethylated oligosaccharides by
gas chromatography, gas chromatography-mass spectrometry, and matrix-
assisted laser desorption/ionization mass spectrometry. The kidney
contained large amounts of Galalpha1,3Gal-containing penta- and
hexasaccharides having carbohydrate sequences consistent with the
Galalpha1,3nLc4and Galalpha1,3Lexstructures, respectively. The former
structure was tentatively identified in all organs by GC/MS. The presence
of extended Galalpha1,3Gal-terminated structures in the kidney and heart
was suggested by antibody binding, and GC/MS indicated the presence of a
Galalpha1,3nLc6structure in the heart. The kidney, spleen, and heart
contained blood group H pentaglycosylceramides based on type 1 (H-5-1) and
type 2 (H-5-2) chains, and H hexaglycosylceramides based on the type 4
chain (H-6-4). In the intestine H-5-1 and H-6-4 were expressed, in the
salivary gland H-5-1 and H-5-2, whereas only the H-5-1 structure was
identified in the liver. Blood group A structures were identified in the
salivary gland and the heart by antibody binding and GC/MS, indicating an
organ- specific expression of blood group AH antigens in the pig.
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1. We experimentally reduced densities of predatory fish in replicated 2 m2 areas of the littoral zone in two ponds to test whether density and biomass of invertebrates would respond to release from fish predation. The ponds are of similar size and in close proximity, but support different fish assemblages: bluegills ( Lepomis macrochirus Rafinesque) and largemouth bass ( Micropterus salmoides (Lacepede)) in one pond, and bluespotted sunfish ( Enneacanthus gloriosus (Holbrook)) and chain pickerel ( Esox niger Lesueur) in the other. Fish densities were reduced to less than 15% of ambient levels in both experiments.
2. In the bluegill–bass pond, density and biomass of most invertebrate taxa and size classes were unaffected by the fish manipulation. Total invertebrate densities did not differ significantly between fish treatments, but total invertebrate biomass was significantly greater where fish density was reduced, averaging 30% higher over the course of the study. Likewise, manipulation of fish in the bluespotted sunfish–pickerel pond had few significant effects on individual taxa and size classes. There were no significant effects on total invertebrate abundance in the bluespotted sunfish–pickerel pond.
3. Our results provide direct experimental evidence consistent with the collective evidence from previous work, suggesting that the impact of fish predation on density and biomass of invertebrate prey in littoral habitats is variable, but generally weak. Invertebrates that coexist successfully with fish in littoral systems probably are adept at taking advantage of refugia offered by the structurally complex physical environment. 相似文献
2. In the bluegill–bass pond, density and biomass of most invertebrate taxa and size classes were unaffected by the fish manipulation. Total invertebrate densities did not differ significantly between fish treatments, but total invertebrate biomass was significantly greater where fish density was reduced, averaging 30% higher over the course of the study. Likewise, manipulation of fish in the bluespotted sunfish–pickerel pond had few significant effects on individual taxa and size classes. There were no significant effects on total invertebrate abundance in the bluespotted sunfish–pickerel pond.
3. Our results provide direct experimental evidence consistent with the collective evidence from previous work, suggesting that the impact of fish predation on density and biomass of invertebrate prey in littoral habitats is variable, but generally weak. Invertebrates that coexist successfully with fish in littoral systems probably are adept at taking advantage of refugia offered by the structurally complex physical environment. 相似文献
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