. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 1C. JfKU it n x K K r< u li M if 11 it ur )C II II II U I) H 7( )f If It M H U If Figure 1. Fluorescence in situ hybndi/ation (FISH) signals and chromosomal location of the major rRNA genes in live species of Crassostmi, (A) C. gigas rDNA probe on C. gigas chromosomes; (B) C. gigas probe on C filicatulu; (C) C. gigas probe on C. ariakfiisis: (D) C. virginica probe on C. rhi~ophorae; (E) C. virginica probe on C. virginica: (F) chromosome alignment of live species. Arrows show FISH signals. discrepancy between the FISH and
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 1C. JfKU it n x K K r< u li M if 11 it ur )C II II II U I) H 7( )f If It M H U If Figure 1. Fluorescence in situ hybndi/ation (FISH) signals and chromosomal location of the major rRNA genes in live species of Crassostmi, (A) C. gigas rDNA probe on C. gigas chromosomes; (B) C. gigas probe on C filicatulu; (C) C. gigas probe on C. ariakfiisis: (D) C. virginica probe on C. rhi~ophorae; (E) C. virginica probe on C. virginica: (F) chromosome alignment of live species. Arrows show FISH signals. discrepancy between the FISH and NOR data may be caused by either false-positive Ag-NOR staining or by a lack of correspondence between NORs and the major rRNA genes. Ag-NOR staining targets transcriptionally active NOR sites and is known to produce variable and inconsis- tent results in the number and sometimes the location of NORs within the same species (Insua and Thiriot- guievrcux. 1W; Li and Havenhand. IW). Also. Ag-NOR staining may not be able to separate major () from minor (5S) rDNA and other actively transcribed genes. One of the two signals described by Leitao <•/ ul. (1999b) seems to correspond to the major rDNA Incus m our studs, hul the nature of the other site is unknown. Based on preliminary FISH data (Wang and Guo. unpubl.). the extra NOR site in C. rir^inicu is not the site ol 5S rDNA. Clearly. Ag-NOK staining can accurately detect major rRNA genes sometimes—as shown by results from C. ,t,'/,i,'</.v, C. rhizo- I'horiic. and C. nn^iilaui (Thiriot-Quievreux and Insua. IW2; Lapeguc <v/o of Crassoslrea % Nuclei with liorae 67(24) 100(10) -P C. virginiea probe C. xina\ 51)114) 100(14) lOq phoi\ic 68(40) 100(19) -P All ItK'iitions arc Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biolo
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
