. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OOCYTE MATURATION IN BRACHIOPODS 267 1/16 3 1/32. 1/64 1/128 1/256 Number of Cases Figure 4. Histogram indicating the lowest 1/2 dilution of lophophore extract from a population of animals that induces oocyte maturation and follicle cell retraction in a piece of ovary. Each unit is one individual. was boiled and diluted 1/32 with PSW. Then protease bound to agarose beads (Type VIII-A, 2-3 units per ml. Sigma) was slowly added to part of the diluted extract under a dissecting microscope until the solution could not accept any
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OOCYTE MATURATION IN BRACHIOPODS 267 1/16 3 1/32. 1/64 1/128 1/256 Number of Cases Figure 4. Histogram indicating the lowest 1/2 dilution of lophophore extract from a population of animals that induces oocyte maturation and follicle cell retraction in a piece of ovary. Each unit is one individual. was boiled and diluted 1/32 with PSW. Then protease bound to agarose beads (Type VIII-A, 2-3 units per ml. Sigma) was slowly added to part of the diluted extract under a dissecting microscope until the solution could not accept any more. After 60 min of incubation at room temperature, the solution was centrifuged and the treated supernatant was collected. The last 1/2 dilution that would induce oocyte maturation in pieces of gonad was then compared for protease-treated and untreated extracts. In one experiment, this dilution was 1/128 for both extracts. In another experiment, it was 1/128 for the untreated extract and 1/64 for the protease-treated extract. The third procedure characterized the lophophore ex- tract by determining whether it would pass through a filter (Amicon) with a molecular weight cutoff of ca. 2000. Ex- tract was boiled and diluted 1/32 with PSW prior to fil- tration. The lowest dilution of unfiltered solution that in- duced maturation in gonad pieces was 1/128, whereas the lowest dilution of filtered solution that induced matura- tion was 1/64. Because a large number of lophophores had to be dissected out and homogenized, this experiment was done only once. These experiments indicate that the oocyte-maturing activity of the lophophore is due to a relatively small mol- ecule and that it is probably not a peptide. The last part of the conclusion should be viewed with caution, however, because some small peptides can show marked resistance to boiling and protease activity. The role ofcAMP in inducing oocyte maturation In many animals the levels of second messengers such as adenosine 3'5
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
