Sexual immaturity in the Paramecium aurelia species complex is genetically controlled, its duratin being expressed by the number of cell divisions between successive conjugations or autogamies.During post-conjugational immaturity mating eractivity is regulated by a cytoplasmic protein - immaturin.The present study revealed that cytoplasm containing immaturin of Paramecium primaurellia injected into preautogampus cells of Paramecium tetraurelia does not inhibit the latter in entering autogamy.This results suggests that immaturin is inefective in the inhibition of autogamy.
Cytoplasm in the quantity of about 5% of the cell volume was transferred from young clonal age donors into older recipients. The experimental post-transplantation clones showed statistically significant prolongation of the IAIs as compared with those stemming from the original recipients or donors. This suggests that the cytoplasm of young postautogamous cells contains a component retarding the expression of the autogamy-inducing gene(s).
The gene construct and the kind of its promotor have the major influence on the effectiveness of transgenesis via microinjection.A new succesful transgenesis technique is described.
Microinjection is one of the most successfully used methods to produce transgenic farm animals. But the effectiveness of transgenesis with the use of microinjection, specially in cattle is still low. Many steps of the transgenesis has been found to influence its effectiveness; DNA purity, the site of its injection, the culture system. There are no reports on the influence of a DNA vector concentration influence on the developmental ability of transformed bovine eggs to the blastocyst stage in the in vitro culture. In presented experiments we investigated the influence of different DNA concentrations on the developmental rate of microinjected immature bovine oocytes, zygotes and 2-cell embryos to the blastocyst stage.
This paper reviews recent investigations on nuclear and cytoplasmic factors affecting the interautogamous interval. It is concluded that although its length is essentially determined by the macronucleus, cytoplasmic factors also play an important role in its regulation. Apart from immaturin, the authors summarize observations indicating the possible presence of an 'autogamous immaturity factor' and 'autogamy accelerating factor'.
There are four main trends in the use of transgenic animals. One of the most interesting is the use of transgenic animals as the donors of tissue or organs suitable for transplantation in human ? xenotransplantation. This field of research has been undergoing intensive and increasing study during the past few years, and some encouraging progress is being made. A pig has been identified as the most suitable donor animal. The aim of the presented experiment was to produce transgenic pigs which tissues and organs could be used for the xenotransplantation needs. To target the goal, a competitive gene construct coding the same substrate as the endogenous enzyme of organ donor was introduced. In effect, transgenic boar was produced with confirmed integration of human a1,2 fucosyltransferase gene. Also, F1 generation of transgenic pigs was generated to preserve ongoing needs of preliminary research of xenotransplantation project.
This paper presents the methods of transgenic pigs production and the results based on the long experience of the authors in this area. Moreover, the trends and current issues of transgenic modification in pigs are discussed.
There are many factors affecting transgenic farm animals production. One of them is the effectiveness of the transfer of zygotes and embryos obtained after DNA microinjection. Low effectiveness of the transfer of potentially transgenic blastocysts in cattle is due to their decreased developmental potential in comparison to the blastocysts developed from not microinjected zygotes. A simple short term in vitro culture used for rabbit zygotes after microinjection increased twice the number of produced potentially transgenic rabbits.
The gene construct WAP(6xHisThr):hGH containing the entire human growth hormone gene (hGH) under the rat whey acidic protein (WAP) promoter regulating the expression in mammary glands of mammals was prepared. The 5? end of the gene was modified by the addition of a sequence encoding six histidine residues and a sequence recognized by thrombin. The gene construct was introduced by microinjection into the male pronucleus of a fertilized oocyte. The founder male rabbit was obtained with the transgene mapping to chromosome 7. The presence of the growth hormone was confirmed in samples of milk collected during the lactation of F1 generation females. The growth hormone can be easily purified by affinity chromatography and cleavage by thrombin to an active form.
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