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Most flowering plants, including important crops, require double fertilization to form an embryo and endosperm, which nourishes it. Independence from fertilization is a feature of apomictic plants that produce seeds, from which the plants that are clones of the mother plant arise. The phenomenon of apomixis occurs in some sexual plants under specific circumstances. Since the launch of a fertilization-independent mechanism is considered a useful tool for plant breeding, there have been efforts to artificially induce apomixis. We have been able to produce fertilization-independent endosperm in vitro in Arabidopsis over the last few years. This paper demonstrates the methods of improving the quality of the endosperm obtained using plant and mammalian steroid hormones. Additionally, it shows the study on the autonomous endosperm (AE) formation mechanism in vitro. This paper examines the effect of exogenous steroid hormones on unfertilized egg and central cell divisions in culture of unpollinated pistils of Arabidopsis Col-0 wild-type andfie-1 mutant. All media with hormones used (estrone, androsterone, progesterone, and epibrassinolide) stimulated central cell divisions and fertilization-independent endosperm development. The stages of AE development followed the pattern of Arabidopsis thaliana wild type after fertilization. Subsequent stages of AE were observed from 2-nuclear up to cellular with the most advanced occurring on medium with 24-epibrassinolide and progesterone. The significant influence of mammalian sex hormones on speed of AE development and differentiation was noticed. Using restriction analysis, the changes in methylation of FIE gene was established under in vitro condition. The authors of this paper showed that Arabidopsis thaliana has a high potency to fertilization-independent development.
In the veterinary literature there are few data concerning the expression of insulin-like growth factor type I (IGF-IR) in the canine mammary gland tumors. The aim of the present study was the evaluation of IGF-IR expression and its correlation to the expression of estrogen receptor α (ERα) and progesterone receptor (PR), proteins: Bcl-2, Bax, p53 in canine mammary gland tumors, and also a correlation with other features: bitch’s age, tumor diameter, histologic type of tumor, degree of histologic malignancy, proliferate activity. The study was done on 112 epithelial neoplasms: 21 (19%) were adenoma, 38 (34%) complex carcinoma (adenocarcinoma), 47 (42%) simple carcinoma (adenocarcinoma) and 6 (5%) solid carcinoma. Histochemistry and immunohistochemistry methods were employed. It was shown that more common and/or higher IGF-IR expression in cells of canine mammary gland tumors was related to the histologic type of cancer of worse prognostic (solid and simple carcinoma), high histologic degree of malignancy (IIIo) but the statistical analysis did not reveal any significant differences. We observed the high degree of IGF-IR expression in tumors which displayed the high ERα and PR expression. These results suggest the involvement of IGF-IR in the development of hormonosensitive canine mammary tumors. Additionally, the significant positive correlation between expression of IGF-IR and p53, Bax was found. Our study provides some evidence that interactions exist between the IGF-IR and these apoptosis-associated proteins may contribute to the development and progression of canine mammary gland tumors. These results require further investigations.
Content available remote Bile acid transport in hypercholesterolemic resistant rabbits
We examined bile acid transport and expression of the apical sodium-dependent bile acid transporter (ASBT) in ileal preparations to determine if alterations in bile acid excretion contributed to a hypercholesterolemia-resistant phenotype in rabbits (CRT/mlo). Taurocholate transport was not different between normal (NR) and CRT/mlo rabbits fed regular diet. However, feeding cholesterol-enriched diet reduced taurocholate transport significantly in CRT/mlo rabbits (0.53±0.06 pmol/µg protein) compared to regular diet (0.95±0.14 pmol/µg protein), but had no effect in NR rabbits. Cholesterol-enriched diet increased ASBT mRNA in CRT/mlo (2.6 ± 0.7 to 5.4 ± 0.1); no significant changes occurred in NR. Some CRT/mlo rabbits carry a polymorphism in ASBT at amino acid 333 (P333L). In transfected HEK293 cells, TC transport of P333L allele was significantly lower (0.08 ± 0.01 vs 0.13 ± 0.01 pmol/µg protein/15 sec, P< 0.05). This allele was not found in NR rabbits. The data suggest that the phenotype of the CRT/mlo rabbit is due to changes in bile acid transport as well as bile acid metabolism.
The aim of the present study was to determine 1) concentrations of NOx in the myometrium of pregnant gilts, and 2) the influence of estradiol-17ß (E2) and/or progesterone (P4) on NOx production by the porcine myometrium on days 5, 10, 15, 20, 25, 30, 35, 40 and 60 of pregnancy (n = 5 per day). Total NOx concentrations were determined using a microplate assay method based on the Griess reaction. During the first 60 days of gestation, a triphasic pattern in the concentration of NOx in the porcine myometrium was observed with a peak on days 10-15, 30 and 60 of gestation. We also demonstrated the stimulatory effect of E2 and/or P4 on in vitro NO production by the porcine myometrium. The stimulatory effect of steroid hormones on NOx release depended on the treatment dose of steroids and day of pregnancy. These data suggest that locally produced NO may inhibit spontaneous uterine contraction and therefore is involved in the maintenance of myometrial quiescence during pregnancy.
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