Browsing by Subject "Niche"

Now showing 1 - 4 of 4
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    Alimentary biology of the golden billed saltator Saltator aurantiirostris (aves: emberizidae) in the Parana River floodplain (Argentina)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 1997) Beltzer, Adolfo H.; Comini, B.; Latino, S.; Quiroga, M.; Facultad de Biología
    This study was undertaken to investigate the alimentary ecology of Saltator a. aurantiirostris by quantifyng the trophic spectrum, niche breadth, circadian alimentary activity rythm and habitat selection throughout the four seasons (spring, summer, autumn and winter). Twenty three stomachs were studied, identifying and quantifying the organisms into different taxonomic levels. Results show an omnivore diet, Solanum amigdalifolium and Acromirmex sp. being the prevailing organisms out of 23 taxonomic entities. The following values were obtained for the trophic niche breadth: 1.26 in spring, 2.64 in summer, 3.17 in autumn and 2.07 in winter. A bell standard was observed as regards the daily alimentary activity rythm, whereas the habitat preference index gave values higher than 0.48 for the forest and 0.42 gallery forest, revealing a marked preference for these environmental units. The obtained results show important advances in the knowledge of the alimentary biology of Saltator a. aurantiirostris, mainly those concerning the interactions between populations and the environment.
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    Biología alimentaria del carpintero real Colaptes melanochloros (Aves: picidae) en el valle aluvial del Rio Paraná, Argentina
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 1995) Beltzer, Adolfo H.; Paporello de Amsler, Graciela; Neffen, María Inés; Facultad de Biología
    Se dan a conocer los resultados de un estudio realizado sobre la dieta del carpintero real (Colaptes melanochloros) basado en ejemplares capturados en el período 1984-1987. El estudio se efectuó con la finalidad de presentar datos cuantificados sobre el espectro trófico a lo largo del ciclo anual y discutir sobre las posibles diferencias que pueda presentar la dieta y la amplitud trófica del nicho, como así también el tamaño de las presas y ntmo diario de actividad alimentaria. Los resultados revelan una dieta carnívora, siendo Iridomyrmex humilis la especie más importante sobre un total de 15 entidades taxonómicas. La amplitud trófica del nicho varió estacionalmente (2,04 en primavera, 1,64 en verano, 2,07 en otoño y 2,31 en invierno). En lo referente al ritmo diario de actividad alimentaria se observó un patrón lineal decreciente entre las 09:OO y 17:OO horas.
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    Melanocyte stem cells in skin diseases and their potential in cell-based therapy
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2022) Wang, Zi Han; Liu, Li-Ping; Zheng, Yun-Wen
    Melanocytes have a complex function and play an important role in a variety of regulatory mechanisms in the human system. Melanocyte stem cells (MelSCs) serve as a reservoir to replenish the melanocytes by regenerating new ones, and they are capable of self-renewal and differentiation to maintain their homeostasis, repair, and regeneration in tissues. The numerical decrease and functional impairment of MelSCs may be closely related to the development and treatment response of many skin diseases. However, the current knowledge about MelSCs mainly comes from studies in mice, and little is known about human MelSC markers; especially, their markers are still unclear or lack consensus. This leads to uncertainty in clinical findings, which further limits our comprehensive understanding of pigmentary disorders and also hinders the progress of new treatments. Thus, in this review article, combined with our previous and current work, we summarize and update the recent advances in MelSC research, including the molecular markers of human MelSCs and their niche, as well as the association of MelSCs with skin diseases, including vitiligo, hair greying, and melanoma. Due to the limited tools available to explore the identified characteristics of human MelSCs, pluripotent stem cells can provide a new research model for further study, especially combined with CRISPR/Cas9 technology. The visualization of human MelSCs’ development and differentiation can help to identify their molecular characteristics and understand their cellular fate dynamically, which will allow us not only to further explore their roles in associated diseases, but also to achieve MelSC-based cellular therapy.
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    Regulation of spermatogonial stem cell self-renewal and proliferation in mammals
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2022) Wei, Bang Hong; Hao, Shuang Li; Yang, Wan Xi
    The generation of functional sperm relies on spermatogonial stem cells (SSCs) as they can maintain a stem cell pool for continuous generation of functional spermatozoa. The maintenance of SSCs is regulated by several factors. In this paper, we summarize the niche and intrinsic factors in regulating SSC self-renewal and proliferation. GDNF regulates SSC self-renewal through Ras-ERK1/2, SFC, PI3K/Akt and MEK/ERK-mTOR signaling pathways. FGF activates MAPK2K1, ERK and Akt pathways and EGF activates ERK and Akt pathways to induce SSC proliferation. Wnt ligands regulate SSC self-renewal and proliferation through both β-catenin dependent and independent pathways. SCF1 and CXCL12 are also found to have roles in SSC maintenance. As for intrinsic factors in SSCs, ETV5, Bcl6b, Lhx1, ID4 and Nanos2 are regulated by niche factors. They act as the downstream factors of niche factors in regulating SSC self-renewal and proliferation. Transcriptional factors OCT4 and PLZF, as well as FOXO1 in SSCs can directly regulate SSC self-renewal and proliferation. Although we have identified the factors, the detailed mechanism of these factors in regulating SSC fate determination is largely unknown. Here, we summarize factors which have roles in SSC fate determination and hope it will be beneficial for further study and treatment of male infertility.