. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 226 D. 6 FOIGHIL AND C. THIRIOT-QUIEVREUX Relative length - - - 3,00 - 2,00 -. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 ly 2(1 21 22 23 24 25 26 27 28 29 30 31 32 Chromosome pairs B m D sm D sm-st D st D st-sm [3 t 0 t-st Figure 3. Ideogram of northeastern Pacific Lasaea chromosomes constructed from relative length and centromeric index values. Lengths are in ^m. m, metacentric; sm, submetacentric; sm-st, submetacentric- subtelocentric; st, subtelocentric; st-sm, subtelocentric-submetacentric; t, telocentr
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 226 D. 6 FOIGHIL AND C. THIRIOT-QUIEVREUX Relative length - - - 3,00 - 2,00 -. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 ly 2(1 21 22 23 24 25 26 27 28 29 30 31 32 Chromosome pairs B m D sm D sm-st D st D st-sm [3 t 0 t-st Figure 3. Ideogram of northeastern Pacific Lasaea chromosomes constructed from relative length and centromeric index values. Lengths are in ^m. m, metacentric; sm, submetacentric; sm-st, submetacentric- subtelocentric; st, subtelocentric; st-sm, subtelocentric-submetacentric; t, telocentric; t-st, telocentric-sub- telocentric. Chromosomes were measured from seven well-spread metaphases (3 with 95 chromosomes, 3 with 97, and 1 with 100). Table I gives the mean and standard deviations of the relative lengths, arm ratios, and centromere indices of 32 chromosome triplets and their classification. An ideogram (Fig. 3) was constructed from the relative length and centromere index values so that the different mor- phological types of chromosomes could be better visual- ized. The karyotype of northeastern Pacific Lasaea consists of 8 metacentrics, 8 submetacentrics (including 6 sub- metacentric-subtelocentrics), 4 subtelocentrics (including 2 subtelocentric-submetacentrics), and 11 telocentrics (including 2 telocentric-subtelocentrics). Within each morphological grouping of chromosomes, some triplets were difficult to distinguish because of their similar lengths: metacentrics no. 7-8, submetacentric-sub- telocentrics no. 12-13 and 15-16, subtelocentrics no. 20-21, and telocentrics no. 27-28 and 30-31. In these cases, the loss of individual chromosomes or the occur- rence of supernumary chromosomes could not be as- signed with accuracy. Pronnclear interaction A single sperm penetrates the cell membrane of each egg shortly after spawning. The egg germinal vesicle breaks down, and the egg chromosomes condense and become aligned for first metaphase (Fig. 4a). The inc
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
