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1

Morphology and developmental potential of bovine parthenotes after spontaneous activation in vitro

100%
Lechniak D., Cieslak D., Sosnowski J.
Journal of Applied Genetics
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1998
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vol. 39
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issue 2
193-198
EN
Spontaneous parthenogenetic activation of bovine oocytes in an in vitro maturation and fertilization system (IVM/IVF) is described. Altogether, 1403 follicular oocytes, collected by the aspiration method, were matured in vitro and then cultured without insemination in the same conditions as a group of inseminated oocytes. After 48-72 h of additional culture, 141 oocytes (10%) were found to be spontaneously activated. Morphological evaluation revealed that the number of blastomeres within parthenotes ranged from 2 to 16 cells, with a minority (15.7%) comprising of 9-16 blastomeres. According to a cytogenetic analysis, only 1.2% of the analysed parthenotes consisted of more than 9 cells. Parthenotes may not be distinguished from embryos produced in vitro and spontaneous parthenogenetic activation in an IVM/IVF system indicates suboptimal culture conditions. A group of non-inseminated oocytes should be included in each experiment to serve as a control. Spontaneously activated bovine parthenotes only occasionaly developed beyond the 8-blastomere stage in a common IVM/IVF system. The incidence of parthenotes interferes with the efficiency of in vitro embryo production but it is doubtful whether it lowers the pregnancy rate after transfer of IVF embryos.
2

Activation of mammalian oocytes in vitro

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Cieslak D., Lechniak D.
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issue 3
52-60
EN
Parthenogenesis is a phenomenon accompanying the in vitro oocyte culture. It is stimulated by a variety of physical and chemical factors which oocytes are facing in vitro. As a consequence of artificial activation, a few different types of parthenones can be formed. Commonly observed are homogenous haploid parthenogenones but also mosaic haploids and diploids can arise. The karyotype of parthenones is not stable and can undergo modifications during further development. Mammalian parthenones do not usually develop beyond the blastocyst stage. Up to now, only one experiment carried out on sheep parthenones has demonstrated their developmental competence up to the 26th day of gestation. Usually, most parthenones die shortly after activation because of damages caused by the activating factors and decreased developmental potential. Moreover, the rate of parthenogenetic development, compared to IVF embryos, is delayed. Since the mechanism of parthenogenesis in mammals still remains unclear, the problem needs further studies.
3

Automictic and apomictic parthenogenesis in psocids (Insecta: Psocoptera)

100%
Nokkala S., Golub N. V.
Folia Biologica
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2006
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vol. 54
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issue 1-2
19-22
EN
Karyotypes and meiosis patterns in three obligatory thelytokous Psocoptera species have been studied for the first time. Females of Aaroniella badonneli (Danks) display 9 chiasmatic bivalents in oocyte metaphase I (2n = 18), hence meiosis is of the automictic type. Females of Ectopsocus meridionalis Ribaga and Valenzuela sp. display 3n = 27, and 27 univalent chromosomes are present in oocyte metaphase I. Thus, meiosis in these species is of the apomictic type.
4

In vitro gynogenesis as a method for haploid plant production

100%
Mol R.
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2003
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issue 3
52-61
EN
This paper reviews last three decades of work on in vitro cultures of unpollinated ovaries or ovules. During in vitro gynogenesis, plants are produced from embryos or callus tissue of haploid (parhtenogenetic or apogamic) origin. Thus, in vitro gynogenesis offers an efficient method for plant breeders who want to obtain haploid plants and homozygous lines. Stability of DH-lines and very limited albinism of regenerated plants are major advantages of the method. The limiting factors are genotype effects in particular species and relatively high labour compared to another or microspore cultures. Since 1976, the studies on in vitro gynogenesis have been performed in 27 species including many crops. Furthermore, gynogenetic haploids have been routinely used in breeding programmes for sugar beet, onion and rice. Because of labour expenses, cultures of unpollinated ovaries or ovules are usually chosen when no other efficient method is available for haploid production in a given species.
5

Spontanous tetraploids of white lupin (Lupinus albus L.s.I.).I.Origin and some morphological characters

88%
Kazimierski T., Kazimierska E. M.
Genetica Polonica
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1994
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vol. 35
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issue 4
271-284
EN
The studies focused on the mechanism of autotetraploid plant occurrence in a hybrid progeny obtained from crossing geographically distant white lupin subspecies.It has been found that autotetraploid plants occurred : a) parthenogenetically - through dupllication of chromosome number in an unreduced megaspore; b) amphimitically - due to duplication of chromosome number in part of somatic cells: in sectors with a doubled chromosome number there occur 2n gametes.Tetraploid plants occurred parthenogenetically died in the next generation, wheres those occurred amphimitically on chimera plants appeared to be viable.Autotetraploid plants in comparison to diploid forms flowered and matured later were less fertile and characterized by larger seeds.
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