In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia,
- Award ID(s):
- 1755016
- NSF-PAR ID:
- 10474556
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 13
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Prolactin (PRL) cells within the rostral pars distalis (RPD) of euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, rapidly respond to a hyposmotic stimulus by releasing two distinct PRL isoforms, PRL 188 and PRL 177 . Here, we describe how environmentally relevant temperature changes affected mRNA levels of prl 188 and prl 177 and the release of immunoreactive prolactins from RPDs and dispersed PRL cells. When applied under isosmotic conditions (330 mosmol/kgH 2 O), a 6°C rise in temperature stimulated the release of PRL 188 and PRL 177 from both RPDs and dispersed PRL cells under perifusion. When exposed to this same change in temperature, ∼50% of dispersed PRL cells gradually increased in volume by ∼8%, a response partially inhibited by the water channel blocker, mercuric chloride. Following their response to increased temperature, PRL cells remained responsive to a hyposmotic stimulus (280 mosmol/kgH 2 O). The mRNA expression of transient potential vanilloid 4, a Ca 2+ -channel involved in hyposmotically induced PRL release, was elevated in response to a rise in temperature in dispersed PRL cells and RPDs at 6 and 24 h, respectively; prl 188 and prl 177 mRNAs were unaffected. Our findings indicate that thermosensitive PRL release is mediated, at least partially, through a cell-volume-dependent pathway similar to how osmoreceptive PRL release is achieved.more » « less
-
null (Ed.)Euryhaline teleost fish are characterized by their ability to tolerate a wide range of environmental salinities by modifying the function of osmoregulatory cells and tissues. In this study, we experimentally addressed the age-related decline in the sensitivity of osmoregulatory transcripts associated with a transfer from fresh water (FW) to seawater (SW) in the euryhaline teleost, Mozambique tilapia, Oreochromis mossambicus . The survival rates of tilapia transferred from FW to SW were inversely related with age, indicating that older fish require a longer acclimation period during a salinity challenge. The relative expression of Na + /K + /2Cl − cotransporter 1a ( nkcc1a ), which plays an important role in hyposmoregulation, was significantly upregulated in younger fish after SW transfer, indicating a clear effect of age in the sensitivity of branchial ionocytes. Prolactin (Prl), a hyperosmoregulatory hormone in O. mossambicus , is released in direct response to a fall in extracellular osmolality. Prl cells of 4-month-old tilapia were sensitive to hyposmotic stimuli, while those of >24-month-old fish did not respond. Moreover, the responsiveness of branchial ionocytes to Prl was more robust in younger fish. Taken together, multiple aspects of osmotic homeostasis, from osmoreception to hormonal and environmental control of osmoregulation, declined in older fish. This decline appears to undermine the ability of older fish to survive transfer to hyperosmotic environments.more » « less
-
The genus
Oreochromis is among the most popular of the tilapiine cichlid tribe for aquaculture. However, their temperature and hypoxia tolerance, if tested at all, is usually tested at temperatures of 20–25°C, rather than at the considerably higher temperatures of 30–35°C typical of tropical aquaculture.We hypothesized that both larvae and adults of the heat and hypoxia‐adapted Tabasco‐line of the Nile tilapia
Oreochromis niloticus would be relatively hypoxia‐tolerant. Oxygen consumption rate (), Q10and aquatic surface respiration (ASR) was measured using closed respirometry at 2 ( c . 0.2 g), 30 (c . 2–5 g), 105c . (10–15 g) and 240 (c . 250 g) days of development, at 25°C, 30°C and 35°C.at 30°C was inversely related to body mass: c . 90 μM O2g−1/h in larvae down toc . 1 μM O2g−1/h in young adults. Q10forwas typical for fish over the range 25–35°C of 1.5–2.0. ASR was exhibited by 50% of the fish at pO2of 15–50 mmHg in a temperature‐dependent fashion. However, the largest adults showed notable ASR only when pO2fell to below 10 mmHg. Remarkably, pcritfor was 12–17 mmHg at 25–30°C and still only 20–25 mmHg across development at 35°C. These values are among the lowest measured for teleost fishes. Noteworthy is that all fish maintain equilibrium, ventilated their gills and showed routine locomotor action for 10–20 min after ceased at near anoxia and when then returned to oxygenated waters, all fish survived, further indicating a remarkable hypoxic tolerance. Remarkably, data assembled for from >30 studies showed a > x2000 difference, which we attribute to calculation or conversion errors. Nonetheless, pcritwas very low for all Oreochromis sp. and lowest in the heat and hypoxia‐adapted Tabasco line. -
Abstract Cunner (
Tautogolabrus adspersus ) are a temperate labrid species that inhabit the Western Atlantic and experience temperatures ranging from 0°C to 25°C. During autumn, once temperatures drop below 10°C in Long Island Sound, cunner find shelter and enter a state of quiescence. Previous work has shown that acclimation to low temperatures limits the performance of locomotor musculature, which significantly lowers steady swimming capabilities. We aimed to understand how the escape response (C‐start) might be impacted by temperatures experienced by cunner in Long Island Sound over the course of a year. Escape responses were recorded at 250 frames/s at 20°C, 15°C, 10°C, and 5°C. Average peak velocities and accelerations were faster in fish acclimated to 20°C than to 5°C and 10°C. Despite taking a similar turn angle to 10°C and 15°C fish, the 5°C treatment group took longer to complete the C‐start, which might make them more susceptible to predation at this temperature. Based on these results it appears that the escape response is reduced at cold temperatures. Previous research has shown that locomotor musculature performance is significantly reduced at cold temperatures, which could explain the results seen here. The decrease in escape performance at cold temperatures could explain their state of extended torpor as the slowed C‐start at these cold temperatures might make them more susceptible to predation. -
Premise Cold tolerance is an important factor limiting the geographic distribution and growing season for many plant species, yet few studies have examined variation in cold tolerance extensively within and among closely related species and compared that to their geographic distribution.
Methods This study examines cold tolerance within and among species in the genus
Arabidopsis . We assessed cold tolerance by measuring electrolyte leakage from detached leaves in multiple populations of fiveArabidopsis taxa. The temperature at which 50% of cells were lysed was considered the lethal temperature (LT 50).Results We found variability within and among taxa in cold tolerance. There was no significant within‐species relationship between latitude and cold tolerance. However, the northern taxa,
A. kamchatica ,A. lyrata subsp.petraea , andA. lyrata subsp.lyrata , were more cold tolerant thanA. thaliana andA. halleri subsp.gemmifera both before and after cold acclimation. Cold tolerance increased after cold acclimation (exposure to low, but nonfreezing temperatures) for all taxa, although the difference was not significant forA. halleri subsp.gemmifera . For all taxa exceptA. lyrata subsp.lyrata , theLT 50values for cold‐acclimated plants were higher than the January mean daily minimum temperature (Tmin), indicating that if plants were not insulated by snow cover, they would not likely survive winter at the northern edge of their range.Conclusions Arabidopsis lyrata andA. kamchatica were far more cold tolerant thanA. thaliana . These extremely cold‐tolerant taxa are excellent candidates for studying both the molecular and ecological aspects of cold tolerance.