scholarly journals Switching of Na+, K+-ATPase isoforms by salinity and prolactin in the gill of a cichlid fish

2011 ◽  
Vol 209 (2) ◽  
pp. 237-244 ◽  
Author(s):  
C K Tipsmark ◽  
J P Breves ◽  
A P Seale ◽  
D T Lerner ◽  
T Hirano ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Replacement Therapy ◽  
Marked Reduction ◽  
Cichlid Fish ◽  
Hormone Treatment ◽  
Salinity Acclimation ◽  
Atpase Subunit ◽  
Α Subunit ◽  
Ovine Prolactin ◽  
Significant Stimulatory Effect

We identified and investigated the changes in expression of two gill Na+, K+-ATPase α-subunit isoforms (α-1a and α-1b) in relationship with salinity acclimation in a cichlid fish, Mozambique tilapia. Transfer of freshwater (FW)-acclimated fish to seawater (SW) resulted in a marked reduction in α-1a expression within 24 h and a significant increase in α-1b expression with maximum levels attained 7 days after the transfer. In contrast, transfer of SW-acclimated fish to FW induced a marked increase in α-1a expression within 2 days, while α-1b expression decreased significantly after 14 days. Hypophysectomy resulted in a virtual shutdown of α-1a mRNA expression in both FW- and SW-acclimated fish, whereas no significant effect was observed in α-1b expression. Replacement therapy by ovine prolactin (oPrl) fully restored α-1a expression in FW-acclimated fish, while cortisol had a modest, but significant, stimulatory effect on α-1a expression. In hypophysectomized fish in SW, replacement therapy with oPrl alone or in combination with cortisol resulted in a marked increase in α-1a mRNA to levels far exceeding those observed in sham-operated fish. Expression of α-1b mRNA was unaffected by hormone treatment either in FW-acclimated fish or in SW-acclimated fish. The mRNA expression of fxyd-11, a regulatory Na+, K+-ATPase subunit, was transiently enhanced during both FW and SW acclimation. In hypophysectomized fish in FW, oPrl and cortisol stimulated fxyd-11 expression in a synergistic manner. The clear Prl dependence of gill α-1a expression may partially explain the importance of this hormone to hyperosmoregulation in this species.

Roles of three branchial Na+-K+-ATPase α-subunit isoforms in freshwater adaptation, seawater acclimation, and active ammonia excretion in Anabas testudineus

2012 ◽  
Vol 303 (1) ◽  
pp. R112-R125 ◽  
Author(s):  
Yuen K. Ip ◽  
Ai M. Loong ◽  
Jie S. Kuah ◽  
Eugene W. L. Sim ◽  
Xiu L. Chen ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Ammonia Excretion ◽  
Kinetic Properties ◽  
Anabas Testudineus ◽  
Α Subunit ◽  
Cdna Sequences ◽  
Freshwater Adaptation ◽  
Subunit Isoforms ◽  
Seawater Acclimation ◽  
Ammonia Exposure

Three Na+-K+-ATPase ( nka) α-subunit isoforms, nka α1a, nka α1b, and nka α1c, were identified from gills of the freshwater climbing perch Anabas testudineus. The cDNA sequences of nka α1a and nka α1b consisted of 3,069 bp, coding for 1,023 amino acids, whereas nka α1c was shorter by 22 nucleotides at the 5′ end. In freshwater, the quantity of nka α1c mRNA transcripts present in the gills was the highest followed by nka α1a and nka α1b that was almost undetectable. The mRNA expression of nka α1a was downregulated in the gills of fish acclimated to seawater, indicating that it could be involved in branchial Na+ absorption in a hypoosmotic environment. By contrast, seawater acclimation led to an upregulation of the mRNA expression of nka α1b and to a lesser extent nka α1c, indicating that they could be essential for ion secretion in a hyperosmotic environment. More importantly, ammonia exposure led to a significant upregulation of the mRNA expression of nka α1c, which might be involved in active ammonia excretion. Both seawater acclimation and ammonia exposure led to significant increases in the protein abundance and changes in the kinetic properties of branchial Na+-K+-ATPase (Nka), but they involved two different types of Nka-immunoreactive cells. Since there was a decrease in the effectiveness of NH4+ to substitute for K+ to activate branchial Nka from fish exposed to ammonia, Nka probably functioned to remove excess Na+ and to transport K+ instead of NH4+ into the cell to maintain intracellular Na+ and K+ homeostasis during active ammonia excretion.

scholarly journals Differential regulation of components of the apoptotic and ubiquitin-mediated proteolytic pathway in slow- and fast- twitch muscle type in lambs receiving increasing amounts of dietary non-structural carbohydrate

2010 ◽  
Vol 90 (3) ◽  
pp. 421-428 ◽  
Author(s):  
S L Greenwood ◽  
M. Steele ◽  
O. AlZahal ◽  
S E Hook ◽  
K C Swanson ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Dry Matter ◽  
Control Diet ◽  
Extracellular Fluid ◽  
Total Carbon ◽  
Α Subunit ◽  
Messenger Ribonucleic Acid ◽  
Proteolytic Pathway ◽  
Fast Twitch Muscle ◽  
Fast Twitch

Non-fibre carbohydrate (NFC) rich diets are commonly fed in ruminant production systems. The objective was to determine whether NFC challenge affects proteasome activity, or messenger ribonucleic acid (mRNA) expression of proteasome subunits or apoptotic Bcl-2 proteins, in slow- or fast- twitch muscle of sheep. For 12 d prior to slaughter, lambs (n = 8) received either a control diet (28.4% of dry matter as grain), or a diet of increasing amounts of grain up to 79.1% of dry matter. A decrease in urinary pH (P = 0.01), base excess of blood and extracellular fluid (P = 0.01), bicarbonate (P = 0.03) and total carbon dioxide (P = 0.04), and an increase in anion gap (P = 0.07) in NFC lambs are indicative of metabolic acidosis. NFC lambs had significantly lower mRNA expression of the 20S -β subunit (P = 0.05), and a tendency toward lower mRNA expression of the 20S-α subunit (P = 0.11) and the 19S isoform (P = 0.15) in soleus, but not to the same extent in extensor digitorum longus (EDL) muscle. Downregulation of Bad mRNA expression occurred in both soleus (P = 0.10) and EDL (P = 0.08) muscle as a result of NFC challenge. These results indicate that NFC challenge does affect mRNA expression of genes related to the proteasome and apoptosis in a muscle specific manner. Key words: Ubiquitin-mediated proteolytic pathway, non-fibre carbohydrate, apoptosis, sheep

scholarly journals Estrogen Replacement Therapy Induces Antioxidant and Longevity-Related Genes in Women after Medically Induced Menopause

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
C. Borrás ◽  
M. Ferrando ◽  
M. Inglés ◽  
J. Gambini ◽  
R. Lopez-Grueso ◽  
...  
Keyword(s):  
16S Rrna ◽  
Mrna Expression ◽  
Replacement Therapy ◽  
Estrogen Replacement Therapy ◽  
Mononuclear Cells ◽  
Reproductive Age ◽  
Fertility Treatment ◽  
Estrogen Replacement ◽  
Total Blood ◽  
Peripheral Blood Mononuclear

Females live longer than males in many species, including humans, and estrogens are in part responsible for this protection against aging. We reported previously that estrogens can protect rats against oxidative stress, by inducing antioxidant and longevity-related genes. Thus, this study was aimed at confirming the ability of estrogens to upregulate antioxidant and longevity-related genes in humans. For this purpose, we selected 16 women of reproductive age (18-42 years old) undergoing a fertility treatment that includes a medically induced menopause, at the Valencian Infertility Institute. We took blood samples at each time point of the treatment (basal, induced menopause, estrogen, and estrogen plus progesterone replacement therapy). mRNA expression of antioxidant and longevity-related genes in peripheral blood mononuclear cells (PBMC) was determined by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Determination of reduced glutathione (GSH) in total blood was carried out using high-performance liquid chromatography (HPLC). As expected, we found that medically induced menopause significantly decreased sexual hormone (estrogens and progesterone) levels. It also lowered glutathione peroxidase (GPx), 16S rRNA, P21, and TERF2 mRNA expression and blood GSH levels. Estrogen replacement therapy significantly restored estrogen levels and induced mRNA expression of manganese superoxide dismutase (MnSOD), GPx, 16S rRNA, P53, P21, and TERF2 and restored blood GSH levels. Progesterone replacement therapy induced a significant increase in MnSOD, P53, sestrin 2 (SENS2), and TERF2 mRNA expression when compared to basal conditions. These findings provide evidence for estrogen beneficial effects in upregulating antioxidant and longevity-related genes in women.

scholarly journals Article Commentary: The Alternatively Spliced Form “b” of the Epithelial Sodium Channel α subunit (α ENaC): Any Prior Evidence of its Existence?

2010 ◽  
Vol 4 ◽  
pp. CMC.S5270
Author(s):  
Marlene F. Shehata
Keyword(s):  
Sodium Channel ◽  
Mrna Expression ◽  
Epithelial Sodium Channel ◽  
Protein Band ◽  
Sodium Balance ◽  
Kidney Cortex ◽  
Western Blots ◽  
Α Subunit ◽  
Alternatively Spliced ◽  
Additional Protein

The epithelial sodium channel (ENaC) is critical in maintaining sodium balance across aldosterone-responsive epithelia. ENaC is a combined channel formed of three subunits (αβγ) with α ENaC subunit being the most critical for channel functionality. In a previous report, we have demonstrated the existence and mRNA expression levels of four alternatively spliced forms of the α ENaC subunit denoted by -a, -b, -c and -d in kidney cortex of Dahl S and R rats. Of the four alternatively spliced forms presently identified, α ENaC-b is considered the most interesting for the following reasons: Aside from being a salt-sensitive transcript, α ENaC-b mRNA expression is ~32 fold higher than α ENaC wildtype in kidney cortex of Dahl rats. Additionally, the splice site used to generate α ENaC-b is conserved across species. Finally, α ENaC-b mRNA expression is significantly higher in salt-resistant Dahl R rats versus salt-sensitive Dahl S rats. As such, this commentary aims to highlight some of the previously published research articles that described the existence of an additional protein band on α ENaC western blots that could account for α ENaC-b in other rat species.

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