Meiosis in autopolyploid Crepis capillaris
Tóm tắt
Meiotic chromosome pairing of triploid and trisomic Crepis capillaris was analysed by electron microscopy in surface-spread prophase I nuclei and compared with light microscopic observations of metaphase I. This system allows identification and separate analysis of each chromosome of the C. capillaris genome. Prophase I trivalent frequencies are very high in all three trisomes and only slightly dependent on chromosome size. At metaphase I, on the other hand, trivalent frequencies are much lower and strongly dependent on chromosome size. There is no evidence for trivalent elimination during prophase I in this system, and the reduction in trivalent frequency at metaphase I can be explained by an insufficiency of appropriately placed chiasmata. The high prophase I trivalent frequencies far exceed the two-thirds expected on a simple model with two terminal independent pairing initiation sites per trisome, suggesting that multiple pairing initiation occurs. Direct observations reveal high frequencies of pairing partner switches (PPSs) in prophase I trisomes, which confirms this supposition. The numbers of PPSs per trisome shows a better fit to the Poisson than to the binomial distribution and their positional distribution along trisomes is random and non-localized. All these observations favour a model of pairing initiation in trisomes based on a large number of evenly distributed autonomous pairing sites each with a uniform and low probability of generating a PPS.
Tài liệu tham khảo
AlaniE, PadmoreR, KlecknerN (1990) Analysis of wild-type and rad 50 mutants of yeast suggests an intimate relationship between meiotic chromosome synapsis and recombination. Cell 61: 419–436
AlbiniSM, JonesGH (1984) Synaptonemal complex-associated centromeres and recombination nodules in plant meiocytes prepared by an improved surface-spreading technique. Exp Cell Res 155:588–592
AlbiniSM, JonesGH (1987) Synaptonemal complex spreading in Allium cepa and A. fistulosum. I. The initiation and sequence of pairing. Chromosoma 95:324–338
AndersonLK, StackSM, ShermanJD (1988) Spreading synaptonemal complexes from Zea mays. I. No synaptic adjustment of inversion loops during pachytene. Chromosoma 96:295–305
CallowRS, GladwellI (1984) A general treatment of chromosome synapsis in even-numbered polyploids. J Theor Biol 106:455–494
CarpenterATC (1975) Electron microscopy of meiosis in Drosophila melanogaster females I. Structure, arrangement and temporal change of the synaptonemal complex in wild-type. Chromosoma 51:157–182
DarlingtonCD (1937) Recent advances in cytology, second edition. J.A. Churchill, London
EinsetJ (1943) Chromosome length in relation to transmission frequency of maize trisomes. Genetics 28:349–364
EvansGM (1981) Polyploidy and crop improvement. J Agric Soc University College of Wales 62:93–116
GilliesCB (1985) An electron microscopic study of synaptonemal complex formation at zygotene in rye. Chromosoma 92:165–175
Gillies CB (1989) Chromosome pairing and fertility in polyploids. In: Gillies CB (ed) Fertility and chromosome pairing: recent studies in plants and animals. CRC Press
GilliesCB, KuspiraJ, BhambhaniRN (1988) Genetic and cytogenetic analyses of the A genome of Triticum monococcum. IV Synaptonemal complex formation in autotretraploids. Genome 29:309–318
HameyY, AbbertonMT, WallaceAJ, CallowRS (1988) Pairing autonomy and chromosome size. In: BrandhamPE (ed) Kew chromosome conference III. Her Majesty's Stationery Office, London
JacksonRC, CaseyJ (1982) Cytogenetic analyses of autopolyploids: models for triploids to octoploids. Am J Bot 69:487–501
JenkinsG, WhiteJ (1990) Elimination of synaptonemal complex irregularities in a Lolium hybrid. Heredity 64:45–53
JohnB, HendersonSA (1962) Asynapsis and polyploidy in Schistocerca paranensis. Chromosoma 13: 111–147
JonesGH, WhitehornJAF, AlbiniSM (1989) Ultrastructure of meiotic pairing in B chromosomes of Crepis capillaris. I One-B and two-B pollen mother cells. Genome 32:611–621
LoidlJ, JonesGH (1986) Synaptonemal complex spreading in Allium. I. Triploid A. sphaerocephalon. Chromosoma 93:420–428
McClintockB (1931) Cytological observations of deficiencies involving known genes, translocations and an inversion in Zea mays. Montana Agric Exp Station Bull 163:1–30
MoensPB (1969) The fine structure of meiotic chromosome pairing in the triploid Lilium tigrinum. J Cell Biol 40:273–279
MoensPB (1970) The fine structure of meiotic chromosome pairing in natural and artificial Lilium polyploids. J Cell Sci 7:55–64
NavashinM (1929) Studies on polyploidy. I. Cytological investigations on triploidy in Crepis. Univ Calif Publ Agric Sci 2:377–400
NewtonWCF, DarlingtonCD (1929) Meiosis in polyploids. I. Triploid and pentaploid tulips. J Genet 21:1–15
QiLL, SybengaJ, deJongJH (1988) Synpatonemal complex pairing and metaphase I association in a telo-substituted telotrisomic of rye (Secale cereale L.). Chromosoma 97:88–95
RasmussenSW (1977) Chromosome pairing in triploid females of Bombyx mori analysed by three dimensional reconstructions of synaptonemal complexes. Carlsberg Res Commun 42:163–197
RasmussenSW, HolmPB, LuBC, ZicklerD, SageJ (1981) Synaptonemal complex formation and distribution of recombination nodules in pachytene trivalents of triploid Coprinus cinereus. Carlsberg Res Commun 46:347–360
ShermanJD, StackSM, AndersonLK (1989) Two-dimensional spreads of synaptonemal complexes from solanaceous plants. IV. Synaptic irregularities. Genome 32:743–753
StackSM, AndersonLK (1986) Two-dimensional spreads of synaptonemal complexes from solanaceous plants. II. Synapsis in Lycopersicon esculentum (tomato). Am J Bot 73:264–281
SvedJA (1966) Telomere attachment of chromosomes. Some genetical and cytological consequences. Genetics 53:747–756
SybengaJ (1975) Meiotic configurations. Springer, Berlin Heidelberg New York
Vincent JE (1991) Chromosome pairing in Crepis rubra and Crepis capillaris. Ph D thesis, University of Birmingham
WhiteJ, JenkinsG, ParkerJS (1988) Elimination of multivalents during meiotic prophase in Scilla autumnalis. I. Diploid and triploid. Genome 30:930–939