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Topic Review
Biography
Topic Review
Bradoriids and the Cambrian Diversification
Bradoriids, among the earliest arthropods to appear in the fossil record, are extinct, ostracod-like bivalved forms that ranged from the early Cambrian to the Middle Ordovician. Bradoriids are notable for having appeared in the Cambrian fossil record before the earliest trilobites, and considering their rapid ascent to high genus-level diversity, provide key data for our understanding of the evolutionary dynamics of the Cambrian Explosion. This paper presents a broad review of bradoriid paleobiology.
932
29 Oct 2020
Topic Review
Mechanobiology of Chondrocytes
This entry is associated with a review article, published in MDPI Applied Sciences on 23 April 2020, about the current knowledge on the mechanical stimulation of mesenchymal stem cells for cartilage regeneration. Loading stresses, physiologically experienced by chondrocytes, regulate the production of glycosaminoglycan and collagen, as well as promote and preserve cell viability. Therefore, there is a rising interest in the development of devices that impose mechanical stimuli, such as compression and shear stress, on mesenchymal stem cells. The mentioned review will analyze the dynamics within the joint, the physiological stimuli experienced by the chondrocytes, and how the biomechanical stimulation can be applied to a stem cell culture in order to induce chondrogenesis. In addition to that, paper lists some of the current applications in the field.
1.2K
29 Oct 2020
Topic Review
Bisphenols
Bisphenols (BPs), and especially bisphenol A (BPA), are known endocrine disruptors (EDCs), capable of interfering with estrogen and androgen activities, as well as being suspected of other health outcomes.
1.4K
28 Oct 2020
Topic Review
GPx8
This entry aimed to illustrate the presence of glutathione peroxidase 8 (GPx8) in rat during preimplantation period of pregnancy. Females were killed on first (D1), third (D3), and fifth (D5) day of pregnancy. The presence of GPx8 in embryos was detected under the confocal microscope, the presence of GPx8 in genital organs was confirmed immunohistochemically, and the amount of GPx8 was determined using densitometry. We found that GPx8 is dispersed in the cytoplasm of oocytes, while after fertilization, it is concentrated in granules. From 4-cell stage till blastocyst, GPx8 reaction was found in the perinuclear region. In the ovary, GPx8 was seen in granulosa-lutein cells, in plasma of blood vessels, and inside Graafian follicles. In oviduct, GPx8 was detected in the plasma and in the extracellular matrix (ECM). Moreover, epithelial cells of isthmus were positive. In uterus, GPx8 was observed in the uterine glands, in the plasma, and in ECM. On D5, the enzyme disappeared from the uterine glands and appeared in fibroblasts. Densitometry revealed that the highest amount of GPx8 was on D1 and subsequently declined. To auhotr's knowledge, this is the first entry describing GPx8 presence in the oocytes, preimplantation embryos, and female genital organs in mammals. Our results improve the understanding of antioxidant enzymes presence during pregnancy in defense against oxidative stress, which is considered to be one of the main causes of infertility.
562
26 Oct 2020
Topic Review
Vertebrate Cutaneous Sensory Corpuscles
Vertebrate cutaneous sensory corpuscles are specialized sensory nerve formations located in the skin of all vertebrates and responsible for tactile sensation. Functionally, they are mechanoreceptors transducing external mechanical stimuli into electrical signals which will be later led to the Central Nervous System. The afferent innervation of vertebrate skin is supplied by nerve fibers (Aβ, Aδ, C) which are originated from peripheral neurons localized in the dorsal root ganglia (DRG). Aβ nerve fibers end at the dermis level forming several morphotypes of sensory corpuscles with capacity of detecting different stimuli: Merkel cell–neurite complexes, Ruffini corpuscles, Meissner’s corpuscles and Pacinian corpuscles are present in the glabrous skin; while pilo-neural complexes are found in hairy skin. The structure of sensory corpuscles is formed by an axon, non-myelinating Schwann-like cells, a capsule of endoneurial and/or perineurial origin and extracelullar matrix molecules. The vertebrate skin contains sensory corpuscles that are receptors for different qualities of mechanosensitivity like light brush, touch, pressure, stretch or vibration. These specialized sensory organs are linked anatomically and functionally to mechanosensory neurons, which function as low-threshold mechanoreceptors connected to peripheral skin through Aβ nerve fibers. Furthermore, low-threshold mechanoreceptors associated with Aδ and C nerve fibers have been identified in hairy skin. The process of mechanotransduction requires the conversion of a mechanical stimulus into electrical signals (action potentials) through the activation of mechanosensible ion channels present both in the axon and the periaxonal cells of sensory corpuscles (i.e., Schwann-, endoneurial- and perineurial-related cells). Most of those putative ion channels belong to the degenerin/epithelial sodium channel (especially the family of acid-sensing ion channels), the transient receptor potential channel superfamilies, and the Piezo family.
1.7K
07 Sep 2020
Topic Review
ECM decellularization methods
The extracellular matrix (ECM) is a complex network with multiple functions, including specific functions during tissue regeneration. Precisely, the properties of the ECM have been thoroughly used in tissue engineering and regenerative medicine research, aiming to restore the function of damaged or dysfunctional tissues. Tissue decellularization is gaining momentum as a technique to obtain potentially implantable decellularized extracellular matrix (dECM) with well-preserved key components. Interestingly, the tissue-specific dECM is becoming a feasible option to carry out regenerative medicine research, with multiple advantages compared to other approaches. We recently published an overview of the most common methods used to obtain the dECM from specific tissues[1]. Here we provide a summary from that report as a helpful guide for future research development.
2.9K
25 Aug 2020
Topic Review
T-Cell Receptor Signalosome
Human immunodeficiency virus type-1 (HIV-1) can undergo either a lytic pathway to cause productive systemic infection or enter a latent state in which the integrated provirus remains transcriptionally silent for decades. The ability to latently infected T-cells enables HIV-1 to establish persistent infections in resting memory CD4+ T-lymphocytes which become reactivated following disruption or cessation of intensive drug therapy. Maintenance of viral latency occurs through epigenetic and non-epigenetic mechanisms. Epigenetic mechanisms of HIV latency regulation involve deacetylation and methylation of histone proteins within Nucleosome 1 (nuc -1) at the viral long terminal repeats (LTR) such that inhibition of histone deacetyltransferase and histone lysine methyltransferase activities, respectively, reactivates HIV from latency. Non-epigenetic mechanisms involve nuclear restriction of critical cellular transcription factors such as Nuclear factor-kappa Beta (NF-kB) or Nuclear factor of activated T-cells (NFAT) which activate transcription from the viral LTR, limiting nuclear levels of viral transcription transactivator protein Tat and its cellular co-factor; positive transcription elongation factor b (P-TEFb) which together regulate HIV transcriptional elongation. The T-cell receptor (TCR) activation efficiently induces NF-kB, NFAT, and activator protein 1 (AP-1) transcription factors through multiple signal pathways and how these factors efficiently regulate HIV LTR transcription through the non-epigenetic mechanism. Elongation factor P-TEFb induced through an extracellular signal-regulated kinase (ERK) dependent mechanism regulates HIV transcriptional elongation before Tat is synthesized and the role of AP-1 in the modulation of HIV transcriptional elongation through functional synergy with NF-kB. The TCR signaling induces critical posttranslational modifications of the Cyclin-dependent kinase 9 (CDK9) subunit of P-TEFb which enhances interactions between P-TEFb and viral Tat protein and the resultant enhancement of HIV transcriptional elongation.
824
13 Aug 2020
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