Chromosome mutation | ScienceGate

Uniparental disomy (UPD) can be caused by various genetic mechanisms such as gamete complementation, chromosome duplication in a monosomic zygote or postzygotic aneuploid correction. This latter mechanism has been recently well documented in human reproduction and seems to be strictly related to placental mosaicism. We have therefore studied some aspects of confined placental mosaicism (CPM) which are useful to clarify one of the most common sources of UPD in humans.Abnormal distribution of chromosomes in postzygotic mitotic cell divisions may result in a mosaic condition with two or more cell lines showing different chromosome constitutions. The effects on fetal phenotype and pregnancy development depend on the chromosomes involved, the distribution of the abnormal cells among tissues and on the precise stage at which chromosome mutation occurs.As shown in Fig. 1, when the mutational event occurs in the blastocyst, prior to the differentiation of embryonic and chorionic compartments, the mosaicism is found in both the placental and fetal tissues. In contrast, when the chromosome mutation occurs at a later stage, after embryonic and chorionic compartment separation, the abnormal cells may be confined to the placenta or to the embryo, and are not necessarily found in both.

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Cytogenetic studies on two rubus arcticus-hybrids

Agricultural and Food Science ◽

10.23986/afsci.71255 ◽

1948 ◽

Vol 20 (2) ◽

pp. 67-79

Author(s):

Antero Vaarama

Keyword(s):

Chromosome Pairing ◽

Chromosome Structure ◽

Gene Mutations ◽

Cytogenetic Studies ◽

Chromosome Mutation ◽

The Subject ◽

Strong Segregation ◽

F2 Generation ◽

Fruit Formation ◽

F1 Generation

The subject of the study has been the F1- and F2-generations of an artificial diploid Ruhus idaeus x arcticus hybrid and the regeneration of a spontaneous triploid R. saxatilis x arcticus hybrid. In these the meiosis in the PMC has been studied. In the F2-generation of the former hybrid observations on the inheritance of a number of species characters have been made. The meiosis of the F1-generation in R. idaeus x arcticus is regular. In 83.4 % of the divisions chromosome pairing is complete and 7 bivalents are formed. In 10.6 % of the cells 6 bivalents and 2 univalents are observed. In 6.0 % of the cells the division of one bivalent was irregular. In the meiotic divisions of the F2-generation no disturbances were observed. In the meiosis of R. saxatilis x arcticus varying numbers of univalents, bivalents and trivalents are seen. The trivalents sometimes form inversion bridges and are delayed in their division. Some chromosomes are consequently eliminated and the chromosomes are divided unequally between the poles. The second division is more regular; sometimes, however, a few chromosomes are eliminated. The F1-generation of R. idaeus x arcticus now studied is very sterile. In part this sterility depends on chromosomal irregularities. Mainly, however, it is caused by the fact that the anthers and the pollen suffer from drought during the summer and consequently no fertilization can take place. In autumn when the humidity of the air becomes higher, some fruit formation takes place. This sterility is here called seasonal sterility and it is thought to depend on an unfavourable gene combination formed by the idaeus and arcticus chromosome complements. In the F2- generation fertility is restored owing to the breakdown of this combination. R. saxatilis X arcticus is completely sterile owing to irregular meiosis. In the F2generation of R. idaeus x arcticus a strong segregation of the species characters takes place. The observations indicate that the two species have a number of allelomorphs in common. It is assumed that the inheritance of some characters is connected with the action of several modifier genes. It has been established that R. arcticus belonging to the Cylactis section of the genus Rubus and R. idaeus belonging to the Idaeobatus section have been derived from common ancestral forms at some time before the pleistocene period. The differentiation has probably been caused by a gene or chromosome mutation leading to seasonal sterility. Speciation has then continued mainly through gene mutations. Rearrangements in chromosome structure have been so small that the ability of the chromosomes to conjugate has not been changed.

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Induksi Mutasi Kromosom dengan Kolkisin Pada Bawang Putih (Allium sativum L.) Kultivar ‘Kesuna Bali’ (Induced Chromosome Mutation Using Colchicine in Garlic (Allium sativum Linn.) Cultivar ‘Kesuna Bali’)

JURNAL BIOS LOGOS ◽

10.35799/jbl.5.1.2015.9317 ◽

2015 ◽

Vol 5 (1) ◽

Author(s):

Made Pharmawati ◽

Ni Luh Ayu Jami Wistiani

Keyword(s):

Chromosome Number ◽

Traditional Medicine ◽

Allium Sativum ◽

Block Design ◽

Colchicine Treatment ◽

Horticultural Crop ◽

Induced Mutation ◽

Randomized Block Design ◽

Chromosome Mutation

Abstrak Tanaman bawang putih (Allium sativum L.) adalah tanaman holtikultura yang memiliki banyak manfaat terutama umbinya yang umumnya digunakan sebgai bumbu dan obat. Salah satu kultivar bawang putih yang ditanam di Bali adalah ‘Kesuna Bali’ yang hanya memiliki satu siung. Salah satu cara untuk memperbaiki karakter tanaman adalah dengan cara induksi mutasi kromosom dengan kolkisin. Penelitian ini bertujuan menganalisis pengaruh perlakuan kolkisin terhadap indeks stomata dan jumlah kromosom dari tanaman ‘Kesuna Bali’. Penelitian menggunakan Rancangan Acak Kelompok dengan enam ulangan. Perlakuan kolkisin yang digunakan adalah 5%, 10% dan 20%. Hasil penelitian menunjukkan bahwa perlakuan kolkisin menurunkan indeks stomata dan meningkatkan jumlah kromosom. Kromosom triploid (2n=3x=24) dihasilkan pada perlakuan kolkisin 20%. Kata kunci : Allium sativum L., ’Kesuna Bali”, kolkisin, mutasi, sitologi Abstract Garlic (Allium sativum L.) is a horticultural crop that has many benefits, especially as spice and traditional medicine. One of garlic cultivars planted in Bali is ‘Kesuna Bali’ which only has one clove. To improve characters of ‘Kesuna Bali’, modification of ‘Kesuna Bali’ properties can be done by means of induced mutation using colchicine. This research aims to analyse the effect of colchicine on stomata index and the number of chromosomes of 'Kesuna Bali'. This research used randomized block design with six replicates. In this experiment the concentration of colchicine used were 5%, 10% and 20%. The results of this study showed that colchicine treatment of 20% resulted in the lowest stomata index and there was an increase in chromosome number. Colchicine at concentration of 20% resulted in triploid chromosome set (2n = 3x = 24). Keywords: Allium sativum L., ’Kesuna Bali”, cholchicine, mutation, cytology

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DUCKY, A NEW SECOND CHROMOSOME MUTATION IN THE MOUSE

Journal of Heredity ◽

10.1093/oxfordjournals.jhered.a106505 ◽

1955 ◽

Vol 46 (1) ◽

pp. 27-29 ◽

Cited By ~ 30

Author(s):

GEORGE D. SNELL

Keyword(s):

Chromosome Mutation

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