. The Biological bulletin. Biology; Zoology; Marine biology. VERTICAL SYMBIONT TRANSMISSION IN SOLEMYA VELUM 199 gonad. Figure 2. Agarose gel (1 %) showing PCR amplifications of a 629 bp segment (arrow) of the symbiont RubisCO gene from host gonads col- lected in July 1993 with the Solemya velum symbiont-specific 430F/ 1058R primers. Gonad samples from 3 females (lanes 5-10) and 1 male (lanes 11-12) were each run in duplicate and considered positive when product of the correct size was visualized in at least one replicate reaction per individual sample. Positive and negative controls were samp
. The Biological bulletin. Biology; Zoology; Marine biology. VERTICAL SYMBIONT TRANSMISSION IN SOLEMYA VELUM 199 gonad. Figure 2. Agarose gel (1 %) showing PCR amplifications of a 629 bp segment (arrow) of the symbiont RubisCO gene from host gonads col- lected in July 1993 with the Solemya velum symbiont-specific 430F/ 1058R primers. Gonad samples from 3 females (lanes 5-10) and 1 male (lanes 11-12) were each run in duplicate and considered positive when product of the correct size was visualized in at least one replicate reaction per individual sample. Positive and negative controls were samples of 5. velum gill (lanes 1-2) and foot (Lanes 3-4), respectively. Lambda HinDIII molecular weight marker shown in first and last lanes. of a symbiont gene with such a specific and sensitive assay suggests that symbionts are present in the ovaries of S. velum throughout the year. Juvenile host gills Bacteria are present in gills of 5". velum that are as young as 11 days postfertilization and which are still developing inside the egg capsule. The gill buds of these young clams are just beginning to form filaments, and subcellular in- clusions resembling prokaryotic cells can be identified in- side the unciliated cells located near the base of the fila- ments (Fig. 3A). As is typical of adult S. velum symbionts, the bacteria in these larvae have a gram-negative bacterial cell envelope and are surrounded by a third, outer mem- brane presumed to be derived from the host. Many of the bacteria appear to be dividing. In 64-day-old clams, the gills are composed of numer- ous filaments and resemble adult S. velum gills with re- spect to their ultrastructure. Bacteriocytes (cells containing many bacteria) and intercalary cells (symbiont-free) are readily identifiable in the region proximal to the ciHated edge of each filament, which is also symbiont-free (Fig. 3B). This bacteriocyte region of the filament is character- istically covered with microvilli. Like the bacteria in the gi
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectb, booksubjectzoology
