Analysis of DNA synthesis during meiotic prophase in Lilium

Hotta, Yasuo; Stern, Herbert

doi:10.1016/0022-2836(71)90322-6

Cited by 136 publications

(66 citation statements)

References 16 publications

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“…The premeiotic DNA replication has been reported to be longer than somatic DNA replication (55,64) a characteristic found in all organisms investigated (3,17,19,50) and in particular in the newt Triturus (11,12,13). The major phase of premeiotic DNA replication terminates at the onset of leptotene (29,32,71) but biochemical analyses have demonstrated that 0.3 % of the DNA in Lilium is delayed in replication until zygotene (29,32). This DNA fraction has been suggested to be of significance for chromosome pairing (29,32,59).…”

Section: Introductionmentioning

confidence: 99%

“…The major phase of premeiotic DNA replication terminates at the onset of leptotene (29,32,71) but biochemical analyses have demonstrated that 0.3 % of the DNA in Lilium is delayed in replication until zygotene (29,32). This DNA fraction has been suggested to be of significance for chromosome pairing (29,32,59). Histone synthesis has been reported to be uncoupled from DNA replication at this stage (8,66), and a histone unique to meiosis with properties similar to the H 1 histone is synthesized (60).…”

Section: Introductionmentioning

confidence: 99%

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The premeiotic DNA replication of euchromatin and heterochromatin in Lilium longiflorum (Thunb.)

Holm

1977

Carlsberg Res. Commun.

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The presynaptic stages of Lilium longiflorum have been analyzed in the light microscope. Seven substages can be defined on the basis of changes in morphology of the heterochromatin and the nucleoli. The duration of the presynaptic interval and the substages has been calculated from bud length measurements and cell stage gradients in the anthers. The premeiotic and somatic DNA replication has been investigated using 3H-thymidine autoradiography. The premeiotic S phase lasts 50 hours whereas the somatic S phase in root tip nuclei is six times shorter. Moreover, premeiotic S phase nuclei house 2-3 times more heterochromatin than somatic nuclei. The premeiotic DNA replication can be divided into three periods: In early S phase the DNA of euchromatin is replicated; in mid S phase synthesis is arrested for a minimum of 9 hours; and in late S phase the DNA of heterochromatin is replicated. DNA synthesis in heterochromatin is correlated with a dispersal of these chromatin regions. Determinations of volume and staining characteristics of heterochromatin after the application of C and Q banding procedures indicate that the premeiotic heterochromatin comprises C bands, Q bands and interbands. The premeiotic DNA replication is discussed in relation to the observed chromatin dynamics, and a proposal is made for the significance of the replication sequence to the formation of the leptotene chromosome and the control of crossing-over.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The premeiotic DNA replication of euchromatin and heterochromatin in Lilium longiflorum (Thunb.)

Holm

1977

Carlsberg Res. Commun.

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“…In lily microsporocytes, small amounts of DNA are synthesized during the zygotene stage; this DNA is known as zygotene DNA (13). Zygotene DNA synthesis is considered to play significant roles in meiosis, especially in the pairing of homologous chromosomes and in meiotic development (15,25).…”

Section: And Discussionmentioning

confidence: 99%

Silver staining of lily microsporocytes during meiotic prophase.

Ohyama

Ito

1987

Cell Struct. Funct.

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ABSTRACT. Nuclei of lily microsporocytes in meiotic prophase were subj ected to two-dimensional spreading and stained with silver nitrate. This method made it possible to observe the behavior of synaptonemal complexes with light microscopy. Axial cores of homologous chromosomes, which had been formed at the leptotene stage, were paired during the zygotene stage, consequently being integrated into the synaptonemal complexes. During the middle zygotene stage, a number of paired segments were observed as heavily stained stretches in the spread nuclei, thus indicating the multiple initiation of pairings along sets of homologous chromosomes. Synapsis and crossing-over between homologous chromosomes take place during the meiotic prophase in eukaryotic organisms. It has been considered that synapsis plays significant roles in recombinational events, because the accurate pairing of homologous chromosomes is prerequisite to the crossing-over. The pairing of homologous chromosomes is maintained by synaptonemal complexes (SCs), which are tripartite structures composed of two lateral elements and a central element (21).Thin-sectioned or microspread preparations of SCs have been extensively studied with the electron microscope, and information about the fine structure and the behavior of SCs during meiotic prophase have been accumulated for various organisms (reviewed in 10, 20, 21, 32). Recently, it has become possible to observe wholemounted SCs under a light microscope by the use of a silver-staining method. Although this method was initially improved for the benefit of the visualization of nucleolar organizer regions in mammalian chromosomes (3, 11), it has been advantageously applied to the cytogenetic analysis of the synapsis of homologous chromosomes in mammalian spermatocytes (5,6,8,9,22,23).The application of this method to plant meiocytes is, however, limited, because most kinds of microsporocytes are enclosed in thick callose walls which make it difficult to spread the nuclei on glass slides for silver staining. To overcome this problem, it is necessary to digest the walls with enzymes. Microsporocytes in solanaceous plants (27), Allium, Secale (1), Rhoeo (28), and some plants including lily (2) have been available for silver-staining method.Microsporocytes of liliaceous plants can be cultured in vitro through the normal meiotic process (29), and it is easy to prepare their protoplasts (16). In particular, lily microsporocytes are preferable materials for cytological and biochemical studies on SCs, not only do the meiotic processes proceed with a high degree of synchrony, but they contain a relative abundance of SCs in their nuclei.

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“…It has been shown in some organisms that DNA synthesis occurs during meiotic prophase at zygotene and pachytene (HoTTA andSTERN 1971, 1975); the very low quantity of DNA synthesized cannot be detected by autoradiographic method. Because of the lenght of the meiotic prophase stages in Asellus, it is to be excluded that.…”

Section: Discussionmentioning

confidence: 99%