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Fig. 9 | BMC Ecology and Evolution

Fig. 9

From: Evolutionary pattern of karyotypes and meiosis in pholcid spiders (Araneae: Pholcidae): implications for reconstructing chromosome evolution of araneomorph spiders

Fig. 9

Pholcinae, males, NORs (FISH) I. Figures b, e contain scheme of sex chromosome trivalent X1X2Y (red circle at c = signal formed by several NORs). Arrowhead = NOR bearing chromosome (c, d, f), bivalent (ac, e) or trivalent (b, e), open arrowhead = sex chromosome-linked NOR, T = sex chromosome trivalent (a, b, e), X = X chromosome, X1 = X1 chromosome, X2 = X2 chromosome, Xs = X chromosomes, Y = Y chromosome, +  = signal formed by several NORs. a Spermophora senoculata (X1X2Y), diakinesis, note three NOR-bearing bivalents, sex chromosome trivalent separated by line (X chromosomes considerably decondensed). Inset: mitotic metaphase, chromosome pair bearing two terminal NOR loci; b Aetana kinabalu (X1X2Y), metaphase I, the largest bivalent and one medium-sized bivalent bear a terminal NOR. The sex chromosome trivalent (separated by line) also includes NOR signal. Position of NOR is, however, unclear. Inset: diplotene, sex chromosome trivalent and its scheme, note NOR at the end of X1 chromosome; c, d Belisana sabah (X0), c Metaphase I. Five bivalents contain NOR, sex chromosome with NOR at both ends. d Incomplete mitotic metaphase (21 chromosomes), NORs terminal, X chromosome with NOR at both ends; e, f Pholcus phalangioides (X1X2Y). e Metaphase I, three bivalents contain NOR. The sex chromosome trivalent contains the signal in region of chromosome pairing (see scheme). f Mitotic metaphase, NORs terminal. X1 chromosome bears NOR at both ends. Number of the other NOR-bearing chromosomes (seven) suggests that the X2 chromosome contains a NOR too. Inset: another mitotic metaphase, Y chromosome considerably condensed, without NOR. Bar = 5 µm; insets 1 µm

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