Androgenesis


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Related to Androgenesis: angiogenesis, gynogenesis

androgenesis

[‚an·drə′jen·ə·səs]
(embryology)
Development of an embryo from a fertilized irradiated egg, involving only the male nucleus.

Androgenesis

 

development of an egg cell with a male nucleus that has been introduced by sperm in the process of fertilization.

Androgenesis is observed in certain species of animals (silkworms) and plants (tobacco, corn) in cases where the maternal nucleus is destroyed before fertilization, which in such cases is false; that is, the female and male nuclei are not united, and only the male nucleus participates in the segmentation. Androgenesis is a special case of virgin development, or parthenogenesis; it is sometimes called male parthenogenesis. It may be caused artificially when either the nucleus of the egg cell itself is removed (for example, by microsurgery, by centrifugation, or by snaking, all of which cause the nucleus-containing fragments to break off) or is damaged by specific nuclear poisons (“tripoflavin”), ionizing radiation, intense heat and other means, and finally degenerates. Experiments have been instituted to obtain an-drogenetic offspring from sharply differing parents (for example, with distant crossbreeding) for the purpose of solving the problem of which cell element—the cytoplasm obtained from the mother or the nucleus obtained from the father—controls the development of the inherited characteristics of the androgenetic individual. In almost all experiments, only the initial stages of the development of androgenetic zygotes were obtained. Such embryos are viable when the set of diploid chromosomes is restored, which is possible when the egg cell is simultaneously penetrated by several spermatozoa and a union of two paternal nuclei occurs. Cases in which only a part of the ovum’s cytoplasm participates in the development of an egg cell with a male nucleus are usually designated by the term “merogony.” Sexually mature animals (always males) have been obtained only in the case of the Chinese silkworm and the ichneumon fly Habrobracon juglandis. In regard to this, B. L. Astaurov and V. P. Ostriakova achieved (1956) complete interspecific androgenesis in animals for the first time by crossbreeding two species of silkworm. A few cases of complete androgenesis have been observed in plants, in cases of the distant crossbreeding of various species of tobacco, hawk’s-beard, and corn. In all cases of complete androgenesis the androgenetic offspring of both animals and plants have resembled the paternal species, which indicates the primacy of the cell nucleus in heredity. Thus it is possible by means of androgenesis to clarify a number of problems connected with nucleoplasmic relations and to evaluate the role of the cytoplasm and the nucleus in transmitting species characteristics. It is also used for the purpose of governing sex when it is necessary to obtain only male offspring (for example, in breeding silkworms).

REFERENCES

Astaurov, B. L. “Znachenie opytov po merogonii i androgenezu dlia teorii razvitiia i nasledstvennosti.” Uspekhi sovremennoi biologii, 1948, vol. 25, no. 1.
Astaurov, B. L., and V. P. Ostriakova-Varshaver. “Poluchenie polnogo geterospermnogo androgeneza u mezhvidovykh gibridov shelkovichnogo chervia.” Izv. AN SSSR: Ser. biologicheskaia, 1957, no. 2.

B. L. ASTAUROV

References in periodicals archive ?
Androgenesis (anther or microspores culture) is the most interested method because of its higher efficiency and number of male gametes existing in each bud.
Petals were removed aseptically and anthers were carefully excised with forceps and placed on MS (Murashige and Skoog 1962) media modified with different auxins and cytokinin either alone or in combination for androgenesis called as MSA media (Table 1).
The term androgenesis was initially confined to a male-specific form of parthenogenesis by which an embryo is believed to originate from a fertilized egg where the female nucleus is somehow inactivated or eliminated (Fig.
This occurs in two ways: (1) via "genome addition" giving rise to triploids, or (2) through androgenesis, producing diploid bisexual ancestors.
Both in vitro androgenesis and gynogenesis have been induced in cucurbit crops for doubled haploid production (Metwally et al., 1998; Lotfi et al., 2003; Song et al., 2007; Galazka and Niemirowicz-Szczytt, 2013).
Globular, heart-like, torpedo and cotyledonary embryos appeared after 8 weeks of androgenesis induction for both species.
Assay for doubled haploid sunflower (Helianthus annuus) plant production by androgenesis: Fact or artifact.
These include genotype-specific responses with a high frequency of recalcitrant genotypes, low induction rates of androgenesis and low regeneration capacity of the microspore-derived embryos, a high frequency of albino plants, and spontaneous polyploidization enhanced by long culture periods of embryos, especially when the callus stage is involved.
Because the allowed concentrations of PCBs in food samples are in the 0.3-5 ppm range (35), the sensitivity of testicular androgenesis to PCB mixture in the subnanomolar to nanomolar concentration ranges is of potential importance for environmental contamination and altered reproductive function.
Microspores at late unicellular or early bicellular stage can be out of the normal process of pollen formation to undergo androgenesis (Heberle-Bors, 1985).
Cytological evidence of spontaneous androgenesis in the freshwater clam Corbicula leana Prime.