The nervous system component of the mesentery of the sea cucumber Holothuria glaberrima in normal and regenerating animals

Adult neurogenesis, generation of new functional cells in the mature central nervous system (CNS), has been documented in a number of diverse organisms, ranging from humans to invertebrates. However, the origin and evolution of this phenomenon is still poorly understood for many of the key phylogenetic groups. Echinoderms are one such phylum, positioned as a sister group to chordates within the monophyletic clade Deuterostomia. They are well known for the ability of their adult organs, including the CNS, to completely regenerate after injury. Nothing is known, however, about production of new cells in the nervous tissue under normal physiological conditions in these animals. In this study, we show that new cells are continuously generated in the mature radial nerve cord (RNC) of the sea cucumber Holothuria glaberrima. Importantly, this neurogenic activity is not evenly distributed, but is significantly more extensive in the lateral regions of the RNC than along the midline. Some of the new cells generated in the apical region of the ectoneural neuroepithelium leave their place of origin and migrate basally to populate the neural parenchyma. Gene expression analysis showed that generation of new cells in the adult sea cucumber CNS is associated with transcriptional activity of genes known to be involved in regulation of various aspects of neurogenesis in other animals. Further analysis of one of those genes, the transcription factor Myc showed that it is expressed, in some, but not all radial glial cells, suggesting heterogeneity of this CNS progenitor cell population in echinoderms

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Antibiotics Modulate Intestinal Regeneration

Biology ◽

10.3390/biology10030236 ◽

2021 ◽

Vol 10 (3) ◽

pp. 236

Author(s):

Lymarie M. Díaz-Díaz ◽

Natalia Rosario-Meléndez ◽

Andrea Rodríguez-Villafañe ◽

Yariel Y. Figueroa-Vega ◽

Omar A. Pérez-Villafañe ◽

...

Keyword(s):

Cell Proliferation ◽

Sea Cucumber ◽

Regenerative Processes ◽

Ecm Remodeling ◽

Bacterial Cultures ◽

Intestinal Regeneration ◽

Negative Effect ◽

Altered Cell ◽

Holothuria Glaberrima ◽

Mtt Assays

The increased antibiotics usage in biomedical and agricultural settings has been well documented. Antibiotics have now been shown to exert effects outside their purposive use, including effects on physiological and developmental processes. We explored the effect of various antibiotics on intestinal regeneration in the sea cucumber Holothuria glaberrima. For this, holothurians were eviscerated and left to regenerate for 10 days in seawater with different penicillin/streptomycin-based cocktails (100 µg/mL PS) including: 100 µg/mL kanamycin (KPS), 5 µg/mL vancomycin (VPS), and 4 µg/mL (E4PS) or 20 µg/mL (E20PS) erythromycin. Immunohistological and histochemical analyses were performed to analyze regenerative processes, including rudiment size, extracellular matrix (ECM) remodeling, cell proliferation, and muscle dedifferentiation. A reduction in muscle dedifferentiation was observed in all antibiotic-treated animals. ECM remodeling was decreased by VPS, E4PS, and E20PS treatments. In addition, organisms subjected to E20PS displayed a significant reduction in the size of their regenerating rudiments while VPS exposure altered cell proliferation. MTT assays were used to discard the possibility that the antibiotics directly affect holothurian metabolic activity while bacterial cultures were used to test antibiotic effects on holothurian enteric microbiota. Our results demonstrate a negative effect on intestinal regeneration and strongly suggest that these effects are due to alterations in the microbial community.

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Is there a central nervous system component to acute baroreflex resetting in rats?

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1992.262.2.h503 ◽

1992 ◽

Vol 262 (2) ◽

pp. H503-H510 ◽

Cited By ~ 2

Author(s):

C. M. Heesch ◽

K. W. Barron

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Nerve Stimulation ◽

Sympathetic Nerve ◽

Sympathetic Nerve Activity ◽

System Component ◽

Nerve Activity ◽

Linear Portion ◽

Aortic Nerve ◽

Maximum Inhibition

This study was designed to evaluate a possible central nervous system (CNS) component to acute baroreflex resetting. In nine arterial baroreceptor-denervated, chloralose-urethan-anesthetized rats, a control (C) aortic nerve stimulation curve (3-5 V, 1 ms, 0-64 Hz) was obtained. Next, a constant "baroreceptor" input was delivered to the CNS (left aortic nerve stimulation, 10 min, 10.2 +/- 1.5 Hz). Within the first 13 s of aortic nerve stimulation, maximum inhibition of lumbar sympathetic nerve activity (LSNA) was 60 +/- 7.8% of baseline and at 1 min it increased to 68 +/- 5.6% of baseline. At the end of the 10-min aortic nerve stimulation, LSNA was not different from the response at 1 min (68 +/- 5.6% = 74 +/- 4.1%). Immediately after the constant stimulation (within 30 s), a test or reset (RS) curve was obtained (0-64 Hz). A recovery (RC) curve was obtained 10-20 min later. The slope of the linear portion of the curve and the stimulation frequency that produced 50% maximum inhibition (ES50) were compared among the three baroreflex curves (C, RS, RC,) and no significant differences were found. Thus, although a CNS component to baroreflex adaptation was evident during the first minute of aortic nerve stimulation, a longer term acute resetting of the baroreflex curve did not occur.

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A Roadmap for Intestinal Regeneration

The International Journal of Developmental Biology ◽

10.1387/ijdb.200227dq ◽

2020 ◽

Vol 52 ◽

Cited By ~ 2

Author(s):

David Quispe-Parra ◽

Griselle Valentín ◽

José E. García-Arrarás

Keyword(s):

Molecular Mechanism ◽

Sea Cucumber ◽

Regenerative Process ◽

Research Model ◽

Functional Studies ◽

Cellular Processes ◽

Sequencing Technologies ◽

Cellular Events ◽

Intestinal Regeneration ◽

Holothuria Glaberrima

Regeneration of lost or injured organs is an intriguing process where numerous cellular events take place to form the new structure. Studies of this process during reconstitution of the intestine have been performed in echinoderms, particularly in holothurians. Many cellular events triggered during regeneration have been described using the sea cucumber Holothuria glaberrima as a research model. More recent experiments have targeted the molecular mechanism behind the process, a task that has been eased by the new sequencing technologies now available. In this review we present the studies involving cellular processes and the genes that have been identified to be associated with the early events of gut regeneration. We also present the ongoing efforts to perform functional studies necessary to establish the role(s) of the identified genes. A synopsis of the studies is given with the course of the regenerative process established so far.

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