Rastenje i diferencijacija alge Ulva rigida C. Agardh in vitro

The in vitro growth and differentiation of the alga Ulva rigida C. Agardh have been studied. Plants grown in enriched sea water (medium II and especially medium L) have a higher chlorophyll content and regularly release a large number of reproductive cells (in 10 days). This capability does not depend on the collecting season. It has been confirmed that axenic Viva cultures grown in solution degenerate. However, if the isolated germlings were grown on semi-solid media their differentiation sometimes took place. Attachment of the germlings to the fragment of the mother plant seems also to promote differentiation. It was found that Ulva rigida could better tolerate a lower salinity than a higher one.Istraženi su rastenje i mogućnost diferencijacije alge Ulva rigida C. Agardh u in vitro uvjetima. Najpovoljniji medij za rastenje alge je solima obogaćena morska voda (medij II i naročito medij L). Osim što Ulva u tim otopinama sadržava povećanu količinu klorofila, ona redovito nakon 10 dana oslobađa velik broj mladih klica. Stvaranje klica ne ovisi o godišnjem dobu, već isključivo o uzgojnoj podlozi. Potvrđeno je da u posve akseničnim uvjetima alga degenerira. Ipak, klice se ponekad diferenciraju u normalan talus, ako se uzgajaju na polukrutoj podlozi. Povezanost klica s talusom odrasle alge povoljno djeluje na rastenje i diferencijaciju. Ulva rigida je eurihalina, a bolje podnosi niži salinitet od višeg. Primijećeno je da rizoidi uzgojeni u kulturi izlučuju Na Cl te time vjerojatno vrše osmoregulaciju stanica

Reverzibilna transformacija plastida u panaširanim listovima vrste Euonymus fortunei var. radicans

Istraženi su ultrastruktura, sadržaj pigmenata i fotosintetska aktivnost plastida panaširanih listova vrste Euonymus fortunei var. radicans. Normalni kloroplasti središnjih tamnozelenih dijelova lista imaju velika grana, mnogo klorofila i visoku fotosintetsku aktivnost. Rubni dijelovi lista, koji sadrže mutirane plastide, vrlo su osjetljivi na osvjetljenje, te mijenjaju boju ovisno o intenzitetu svjetlosti. Ako rastu u sjeni, oni su svjetlozeleni i sadrže kloroplaste s malo grana. Na jakoj sunčevoj svjetlosti ti rubni dijelovi požute, a u njihovim plastidima uz pojedinačne tilakoide pojavljuju se tubularni kompleksi, čaškasto svinuti svežnjevi tilakoida i »mostovi« među tilakoidima. Sadržaj klorofila i fotosintetska aktivnost, posebno žutih dijelova lista, vrlo su niski. Fotosintetska efikasnost (fotosintetska aktivnost izražena po jedinici klorofila), naprotiv, mnogo je viša nego u normalnim tamnozelenim dijelovima lista. Ako se listovi drže u sjeni, žuti dijelovi mogu ozelenjeti, te opet sadrže kloroplaste. Takvo svjetlozeleno tkivo može na suncu ponovno po- žutjeti, a plastidi u njima sadrže ponovno vrlo malo tilakoida. Komponente membrana, koje se iz bilo kojih razloga ne mogu ugraditi u tilakoide ili koje potječu od razgrađenih tilakoida, mogu se nagomilati u posebnim strukturama (prolamelarnim tjelešcima, tilakoiđnim tjelešcima, plastoglobulima). Te se strukture tijekom dalje diferencijacije plastida mogu po potrebi iskoristiti za izgradnju novih tilakoida

Effect of Notch and PARP Pathways’ Inhibition in Leukemic Cells

Differentiation of blood cells is one of the most complex processes in the body. It is regulated by the action of transcription factors in time and space which creates a specific signaling network. In the hematopoietic signaling system, Notch is one of the main regulators of lymphocyte development. The aim of this study was to get insight into the regulation of Notch signalization and the influence of poly(ADP-ribose)polymerase (PARP) activity on this process in three leukemia cell lines obtained from B and T cells. PARP1 is an enzyme involved in posttranslational protein modification and chromatin structure changes. B and T leukemia cells were treated with Notch and PARP inhibitors, alone or in combination, for a prolonged period. The cells did not show cell proliferation arrest or apoptosis. Analysis of gene and protein expression set involved in Notch and PARP pathways revealed increase in JAGGED1 expression after PARP1 inhibition in B cell lines and changes in Ikaros family members in both B and T cell lines after γ-secretase inhibition. These data indicate that Notch and PARP inhibition, although not inducing differentiation in leukemia cells, induce changes in signaling circuits and chromatin modelling factors

Key factors for thymic function and development

The thymus is the organ responsible for T cell development and the formation of the adaptive immunity function. Its multicellular environment consists mainly of the different stromal cells and maturing T lymphocytes. Thymus-specific progenitors of epithelial, mesenchymal, and lymphoid cells with stem cell properties represent only minor populations. The thymic stromal structure predominantly determines the function of the thymus. The stromal components, mostly epithelial and mesenchymal cells, form this specialized area. They support the consistent developmental program of functionally distinct conventional T cell subpopulations. These include the MHC restricted single positive CD4+ CD8- and CD4- CD8+ cells, regulatory T lymphocytes (Foxp3+), innate natural killer T cells (iNKT), and γδT cells. Several physiological causes comprising stress and aging and medical treatments such as thymectomy and chemo/radiotherapy can harm the thymus function. The present review summarizes our knowledge of the development and function of the thymus with a focus on thymic epithelial cells as well as other stromal components and the signaling and transcriptional pathways underlying the thymic cell interaction. These critical thymus components are significant for T cell differentiation and restoring the thymic function after damage to reach the therapeutic benefits

MiR-7 in Cancer Development

MicroRNAs (miRNAs) are short non-coding RNA involved in the regulation of specific mRNA translation. They participate in cellular signaling circuits and can act as oncogenes in tumor development, so-called oncomirs, as well as tumor suppressors. miR-7 is an ancient miRNA involved in the fine-tuning of several signaling pathways, acting mainly as tumor suppressor. Through downregulation of PI3K and MAPK pathways, its dominant role is the suppression of proliferation and survival, stimulation of apoptosis and inhibition of migration. Besides these functions, it has numerous additional roles in the differentiation process of different cell types, protection from stress and chromatin remodulation. One of the most investigated tissues is the brain, where its downregulation is linked with glioblastoma cell proliferation. Its deregulation is found also in other tumor types, such as in liver, lung and pancreas. In some types of lung and oral carcinoma, it can act as oncomir. miR-7 roles in cell fate determination and maintenance of cell homeostasis are still to be discovered, as well as the possibilities of its use as a specific biotherapeutic

Analysis of Ikaros Family Splicing Variants in Human Hematopoietic Lineages

Transcription factors from the Ikaros family are involved in lymphocyte differentiation and have a critical role at specific check points of the haemopoietic pathway. However, how developmentally regulated changes are reflected in gene expression programs of lymphocyte differentiation is not well understood. It has been suggested that disregulation of transcription factors from the Ikaros family is associated with the development of different human leukemias. In this work we analyzed the state of Ikaros family members in different leukemic cells with the aim to explore the transcriptional control of human hematopoietic lineages and shed some new light on our understanding of transcription factor significance in human leukemias. By means of RT-PCR and specific primers we investigated the expression of Ikaros, Aiolos and Helios transcription factors and their splicing variants in seven leukemia cell lines derived from different types of leukemia (ALL, CML, AML) and lymphoma (histiocytic lymphoma, Burkitt lymphoma and anaplastic large cell lymphoma). In all of the cell lines examined Ikaros was present in dominant Ik1 to Ik4 isoforms and small Ik6 isoform was absent. Aiolos was expressed in the majority of the cell lines, of both, B and T origin, in the form of the full length Aio1. Helios was also present only in two long isoforms Hel1 and Hel2, and was absent in one third of the lines. Similar distribution of positive and negative expression of Aiolos and Helios found in various types of leukemias could implicate common pathways of their regulation