Cardiac plasticity influences aerobic performance and thermal tolerance in a tropical, freshwater fish at elevated temperatures

. Although larval stages are often considered particularly vulnerable to stressors, for many marine invertebrates studies of thermal tolerance have focused on adults. Here we determined the upper thermal limit (LT50) of the zoea I of four Caribbean crab species (Macrocoelomatrispinosum, Aratuspisonii, Armasesricordi, and Minucarapax) and compared their thermal tolerance over time and among species. The zoea from the subtidal species M.trispinosum and tree climbing mangrove species A.pisonii had a lower thermal tolerance, 35 and 38.5 °C respectively, than did the semiterrestrial A.ricordi and M.rapax. In all four species tested, the estimates of thermal tolerance depend on the duration of exposure to elevated temperatures. Longer exposures to thermal stress produce lower estimates of LT50, which decreased by ~1 °C from a two- to a six-hour exposure. Crab embryos develop on the abdomen of the mother until the larvae are ready to hatch. Therefore, the thermal tolerances of the embryos which need to coincide with the environmental conditions experienced by the adult stage, may carry over into the early zoea stage. Our results suggest that semiterrestrial species, in which embryos may need to withstand higher temperatures than embryos of subtidal species also produce larvae with higher thermal tolerances. Over the short term, the larvae of these tropical crab species can withstand significantly higher temperatures than those experienced in their marine habitat. Longer term rearing studies are necessary to determine the temperature at which chronic exposure has a negative impact on embryonic and larval survival.

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Comparative Effect of Heat Shock on Survival of O157:H7 and Non-O157 Shiga Toxigenic Escherichia coli and Salmonella in Lean Beef with or without Moisture-Enhancing Ingredients

Journal of Food Protection ◽

10.4315/0362-028x.jfp-16-335 ◽

2017 ◽

Vol 80 (6) ◽

pp. 1002-1008 ◽

Cited By ~ 1

Author(s):

Akhila Vasan ◽

Steven C. Ingham ◽

Barbara H. Ingham

Keyword(s):

Escherichia Coli ◽

Heat Shock ◽

Thermal Tolerance ◽

Pathogenic Bacteria ◽

Elevated Temperatures ◽

Sodium Tripolyphosphate ◽

Beef Industry ◽

Linear Portion ◽

Beef Products ◽

Pathogen Control

ABSTRACT Thermal tolerance of pathogenic bacteria has been shown to increase after exposure to sublethal elevated temperatures, or heat shock. We evaluated the effect of heat shock at 48°C on thermal tolerance (D55°C) of cocktails of O157 and non-O157 Shiga toxigenic Escherichia coli (STEC) and Salmonella in lean ground beef with or without moisture-enhancing ingredients. Beef was moisture enhanced to 110% (w) with a 5% NaCl–2.5% sodium tripolyphosphate (w/w) brine. Meat, with or without added brine, was inoculated (∼108 CFU/g) and heat shocked at 48°C for 0, 5, or 30 min, followed by isothermal heating at 55°C. Inoculated control samples were unenhanced and were not subject to heat shock. From the linear portion of the log CFU per gram surviving cells over time plots, D55°C-values (minutes) were calculated. D55°C was 20.43, 28.78, and 21.15 min for O157, non-O157, and Salmonella controls, respectively. Overall, heat shock significantly increased D55°C, regardless of pathogen (P < 0.05). After 30 min of heat shock, D55°C increased 89 and 160% for O157 STEC, 32 and 49% for non-O157 STEC, and 29 and 57% for Salmonella, in unenhanced and enhanced samples, respectively, relative to the pathogen control. D55°C for Salmonella was the same or significantly less than for O157 and non-O157 STEC, regardless of heat shock, and was significantly less than for O157 and non-O157 STEC in all trials with moisture-enhanced meat (P < 0.05). Moisture-enhancing ingredients significantly increased D55°C, regardless of pathogen (P < 0.05). We suggest that thermal processes validated against Salmonella may not prove effective against STEC in all cases and that regulators of the beef industry should focus attention on STEC in nonintact moisture-enhanced beef products.

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Oxygen limitation of thermal tolerance defined by cardiac and ventilatory performance in spider crab, Maja squinado

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2000.279.5.r1531 ◽

2000 ◽

Vol 279 (5) ◽

pp. R1531-R1538 ◽

Cited By ~ 160

Author(s):

Markus Frederich ◽

Hans O. Pörtner

Keyword(s):

Thermal Tolerance ◽

Aerobic Performance ◽

Spider Crab ◽

Critical Temperatures ◽

Physiological Processes ◽

Anaerobic Energy ◽

Distribution Limits ◽

On Line ◽

Ventilation Rates ◽

Thermal Limitation

Geographic distribution limits of ectothermal animals appear to be correlated with thermal tolerance thresholds previously identified from the onset of anaerobic metabolism. Transition to these critical temperatures was investigated in the spider crab ( Maja squinado) with the goal of identifying the physiological processes limiting thermal tolerance. Heart and ventilation rates as well as Po 2 in the hemolymph were recorded on-line during progressive temperature change between 12 and 0°C (1°C/h) and between 12 and 40°C (2°C/h). Lactate and succinate were measured in tissues and hemolymph after intermediate or final temperatures were reached. High levels of hemolymph oxygenation suggest that an optimum range of aerobic performance exists between 8 and 17°C. Thermal limitation may already set in at the transition from optimum to pejus (pejus = turning worse, progressively deleterious) range, characterized by the onset of a decrease in arterial Po 2 due to reduced ventilatory and cardiac performance. Hemolymph Po 2 values fell progressively toward both low and high temperature extremes until critical temperatures were reached at ∼1 and 30°C, as indicated by low Po 2 and the onset of anaerobic energy production by mitochondria. In conclusion, the limited capacity of ventilation and circulation at extreme temperatures causes insufficient O2 supply, thereby limiting aerobic scope and, finally, thermal tolerance.

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Thelohanellus habibpuri sp. n. (Myxozoa: Bivalvulida) from the tropical freshwater fish rohu, Labeo rohita (Hamilton-Buchanan, 1882) in West Bengal, India: Light and electron microscope observations

Animal Biology ◽

10.1163/157075607781753119 ◽

2007 ◽

Vol 57 (3) ◽

pp. 293-300 ◽

Cited By ~ 9

Author(s):

Tanusree Dutta ◽

Subhendu Acharya

Keyword(s):

Freshwater Fish ◽

West Bengal ◽

Labeo Rohita ◽

Polar Filament ◽

Pectoral Fin ◽

Filament Wound ◽

Host Fishes ◽

A New Species ◽

Iodinophilous Vacuole ◽

Tropical Freshwater

AbstractA new species of myxozoan (Myxozoa: Bivalvulida) Thelohanellus habibpuri sp. n. parasitic in tropical freshwater fish collected from the Habibpur, West Bengal, India is described in this paper. T. habibpuri was found in the Pectoral fin of Labeo rohita (Hamilton-Buchanan, 1882). The diagnostic characters of T. habibpuri are: generally oval milky-whitish plasmodia attached in the pectoral fin of host fishes; spore egg-shaped to ovoid with slightly tapering anterior and rounded posterior end, averaging 13.9 × 8.5 μm in size; a single oval-round polar capsule 6.0 × 4.9 μm in diameter, with polar filament wound in 3-4 coils. Finely granular sporoplasm containing two slightly oval nuclei (1.4 μm in diameter) and a small iodinophilous vacuole (3.0 μm in diameter) present in the spore.SEM study of this myxozoan reveals the anterior extremity of spore is truncated. The Cnidocyst discharge channel appear as a dark area. The longitudinal wavy surface are visible on the spore.

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