Affect Respiration Rates Research Articles

Elevated plasma corticosterone increases metabolic rate in a terrestrial salamander

Plasma glucocorticoid hormones (GCs) increase intermediary metabolism, which may be reflected in whole-animal metabolic rate. Studies in fish, birds, and reptiles have shown that GCs may alter whole-animal energy expenditure, but results are conflicting and often involve GC levels that are not physiologically relevant. A previous study in red-legged salamanders found that male courtship pheromone increased plasma corticosterone (CORT; the primary GC in amphibians) concentrations in males, which could elevate metabolic processes to sustain courtship behaviors. To understand the possible metabolic effect of elevated plasma CORT, we measured the effects of male courtship pheromone and exogenous application of CORT on oxygen consumption in male red-legged salamanders ( Plethodon shermani). Exogenous application of CORT elevated plasma CORT to physiologically relevant levels. Compared to treatment with male courtship pheromone and vehicle, treatment with CORT increased oxygen consumption rates for several hours after treatment, resulting in 12% more oxygen consumed (equivalent to 0.33 J) during our first 2 h sampling period. Contrary to our previous work, treatment with pheromone did not increase plasma CORT, perhaps because subjects used in this study were not in breeding condition. Pheromone application did not affect respiration rates. Our study is one of the few to evaluate the influence of physiologically relevant elevations in CORT on whole-animal metabolism in vertebrates, and the first to show that elevated plasma CORT increases metabolism in an amphibian.

Microbial and hydrolase activity after release of indoleacetic acid and ethylene–polyamine precursors by a model root surface

Effects of indoleacetic acid (IAA) and ethylene (E) precursors on microbial biomass, respiration, and various hydrolase activities of the rhizosphere and bulk soil, were studied using a model system simulating this environment. The effects of IAA and E precursors were compared to those of glucose-C, N and S (GNS) applied at the same rate to soils. None of the treatments significantly affected respiration rates and ATP contents of soils. The IAA precursor significantly increased phosphatase, β-glycosidase, urease and protease activities of the rhizosphere layer of both soils; the E precursor significantly increased phosphodiesterase, urease and protease activities of both soils. The GNS treatment did not significantly increase any hydrolase activity. The IAA precursor also stimulated the phosphatase activity of the bulk layer of the sandy soil after 7 d of incubation, possibly due to its diffusion from the rhizosphere to the bulk soil, whereas no stimulation in the bulk soil layer was observed in either E or GNS treatments. The increased hydrolase activities in the rhizosphere upon addition of both IAA and E precursors may be due to the role of these precursors as microbial metabolic activators, and may be involved in stimulation of plant growth through other processes involving IAA and E producing root associated microorganisms.

EFFECT OF 1-MCP AND DIFFERENT ECOLOGICAL CONDITIONS ON POSTHARVEST QUALITY OF 'EŞME' QUINCE FRUIT DURING LONG TERM STORAGE

The aim of this study was to determine the effect of 1-MCP and different growing regions on quality of 'Esme' quince (Cydonia oblonga Mill.) fruit during storage. Fruit samples were taken from Ankara (Central Anatolia region) during commercial harvest period (beginning of October) over two seasons and from Sakarya-Geyve (Marmara region) for only one season. The latter region is responsible for the highest quince production of Turkey. Immediately after harvest, fruit were treated with 0 (Control) and 625 ppb 1-MCP at 12°C under gas tight conditions for 24 hours and subsequently they were stored at 2±1°C and 85-90% RH for six moths. During the storage period, respiration rate, ethylene production, flesh firmness, soluble solid content, titratable acidity, fruit skin and flesh color, weight loss, sensory evaluation and flesh browning were observed at monthly intervals. As a result, 1-MCP mostly affected respiration rate, flesh browning and decay in fruits from both regions. Moreover, they showed higher soluble solid content and sensory evaluation value. Based on sensory characteristics and inhibition on flesh firmness, flesh browning data, pre-storage 1-MCP treatment may be a promising postharvest treatment to keep postharvest quality of 'Esme' quince fruit from both regions.

Effect of temperature and exogenous ethylene on the physiological and quality traits of purslane ( Portulaca oleracea L.) leaves during storage

The effect of storage conditions on shelf life of purslane leaves ( Portulaca oleracea L.) was investigated. In a first trial, fresh leaves were harvested and stored under different temperatures (0, 5, and 10 °C) for 17 days. Storage temperature significantly affected color, visual quality, respiration rate, ethylene production, weight loss, vitamin C content, antioxidant activity, total phenolic and total and soluble oxalic acid contents. Leaves stored at 10 °C did not withstand the entire storage period, being judged not marketable after 8 days, while leaves stored at 0 and 5 °C were still marketable after 13 and 10 days, respectively. Samples stored at 10 °C showed a lower hue angle value and a higher chlorophyll loss compared to other samples, while no symptom of chilling injury was observed in leaves stored at 0 and 5 °C. Respiration rate significantly increased with increasing storage temperature; ethylene production was also affected by storage temperature, although values were very low (<1 nL C 2H 4/kg/h at 10 °C). Vitamin C was more sensitive to postharvest deterioration during storage and a marked reduction was observed in samples stored at 10 °C. In addition, purslane was found to be high in antioxidants (192 mg TEAC/100 g fw, at harvest) and total phenols (471 mg GAE/100 g fw) and the decline observed during storage was influenced by temperature. A second trial was performed in order to evaluate the effect of exogenous ethylene on leaves during storage at two temperatures. Fresh leaves were harvested and exposed to air (as control), and to 0.1, 1, and 10 μL/L of ethylene for 15 days at 0 and 15 °C. Exposure to C 2H 4 affected respiration rate, color and overall appearance but only at 15 °C and for high ethylene concentrations (1 and 10 μL/L). Leaves did not withstand the entire storage period and marketable life was about 7 days at 15 °C, except for leaves exposed to 10 μL/L of C 2H 4, while for all samples held at 0 °C marketable life exceeded 10 days. Loss of marketability was due to yellowing and discoloration. It is concluded that purslane is not chilling sensitive, can be stored successfully at low temperatures, produces very small amounts of ethylene and is not sensitive to a low concentration of ethylene, especially when exposure occurs at low temperature.

Ecophysiological responses of salt cedar (Tamarix spp. L.) to the northern tamarisk beetle (Diorhabda carinulata Desbrochers) in a controlled environment

The northern tamarisk beetle (Diorhabda carinulata Desbrochers) was released in several western states as a biocontrol agent to suppress Tamarix spp. L. which has invaded riparian ecosystems; however, effects of beetle herbivory on Tamarix physiology are largely undocumented and may have ecosystem ramifications. Herbivory by this insect produces discoloration of leaves and premature leaf drop in these ecosystems, yet the cause of premature leaf drop and the effects of this leaf drop are still unknown. Insect herbivory may change leaf photosynthesis and respiration and may affect a plant’s ability to regulate water loss and increase water stress. Premature leaf drop may affect plant tissue chemistry and belowground carbon allocation. We conducted a greenhouse experiment to understand how Tamarix responds physiologically to adult beetle and larvae herbivory and to determine the proximate cause of premature leaf drop. We hypothesized that plants experiencing beetle herbivory would have greater leaf and root respiration rates, greater photosynthesis, increased water stress, inefficient leaf nitrogen retranslocation, lower root biomass and lower total non-structural carbohydrates in roots. Insect herbivory reduced photosynthesis rates, minimally affected respiration rates, but significantly increased water loss during daytime and nighttime hours and this produced increased water stress. The proximate cause for premature leaf drop appears to be desiccation. Plants exposed to herbivory were inefficient in their retranslocation of nitrogen before premature leaf drop. Root biomass showed a decreasing trend in plants subjected to herbivory. Stress induced by herbivory may render these trees less competitive in future growing seasons.

Use of crude glycerol, a biodiesel coproduct, in diets for lactating sows1,2

An experiment was conducted to evaluate the effect of dietary crude glycerol in lactating sow diets on sow and litter performance under heat stress conditions. Mixed parity (range = 0 to 13) sows (n = 345; 253 +/- 24 kg of BW) were assigned randomly within gestation housing location and parity to 1 of 4 dietary treatments. Treatments consisted of a corn-soybean-based control diet (CON) and 3, 6, or 9% glycerol added at the expense of corn and soybean meal. Liquid crude glycerol was incorporated in the complete diet at the time of mixing. Dietary treatments were imposed on d 109 of gestation (2.25 kg/d) when sows were moved into farrowing rooms. Heat index during lactation in farrowing rooms exceeded 25 degrees C for all sows. At farrowing, sows were allowed ad libitum access to feed throughout lactation. Dietary treatment tended (P = 0.08) to influence ADFI of sows (CON = 6.04 kg/d; 3% = 6.21 kg/d; 6% = 5.69 kg/d; 9% = 6.00 kg/d; pooled SE = 0.18). Up to 9% crude glycerol in the diet had no effect on sow BW and backfat loss, weaning-to-estrus interval, preweaning mortality of piglets, and ADG of piglets. Increasing dietary glycerol linearly reduced (P = 0.10) litter size at weaning (CON = 9.50; 3% = 9.60; 6% = 9.36; 9% = 9.39; pooled SE = 0.08). Daily water consumption was not affected by dietary treatment. Crude glycerol did not affect respiration rates or rectal body temperatures, indicating no efficacy in reducing heat stress of sows. Plasma glycerol concentrations increased linearly (P < 0.05) as dietary crude glycerol increased (CON = 1.21 microM; 3% = 1.69 microM; 6% = 7.21 microM; 9% = 29.04 microM; pooled SE = 1.58), but plasma glucose concentrations were not affected. Crude protein content of the milk of sows was not affected (P = 0.16) by dietary treatment. Dry matter (P = 0.07) and crude fat (P = 0.09) content of the milk of the sows tended to increase linearly (DM basis: CON = 17.84%; 3% = 18.43%; 6% = 18.98%; 9% = 18.48%; pooled SE = 0.34; crude fat: CON = 4.78%; 3% = 4.91%; 6% = 5.50%; 9% = 5.24%; pooled SE = 0.30), whereas milk ash concentration tended (P = 0.09) to decrease linearly with increasing dietary glycerol (CON = 0.77%; 3% = 0.79%; 6% = 0.74%; 9% = 0.74%; pooled SE = 0.02). Increasing dietary crude glycerol linearly increased (P < 0.05) lactose concentration in the milk of sows (CON = 5.16%; 3% = 5.30%; 6% = 5.43%; 9% = 5.46%; pooled SE = 0.10). Results from this study indicate that lactating sows fed diets containing up to 9% crude glycerol perform similarly to sows fed a standard corn-soybean meal diet.

Depression of belowground respiration rates at simulated high moose population densities in boreal forests

Large herbivores can affect the carbon cycle in boreal forests by changing productivity and plant species composition, which in turn could ultimately alter litter production, nutrient cycling, and the partitioning between aboveground and belowground allocation of carbon. Here we experimentally tested how moose (Alces alces) at different simulated population densities affected belowground respiration rates (estimated as CO2 flux) in young boreal forest stands situated along a site productivity gradient. At high simulated population density, moose browsing considerably depressed belowground respiration rates (24-56% below that of no-moose controls) except during June, where the difference only was 10%. Moose browsing depressed belowground respiration the most on low-productivity sites. Soil moisture and temperature did not affect respiration rates. Impact of moose on belowground respiration was closely linked to litter production and followed Michaelis-Menten dynamics. The main mechanism by which moose decrease belowground respiration rates is likely their effect on photosynthetic biomass (especially decreased productivity of deciduous trees) and total litter production. An increased productivity of deciduous trees along the site productivity gradient causes an unequal effect of moose along the same gradient. The rapid growth of deciduous trees may offer higher resilience against negative effects of moose browsing on litter production and photosynthate allocation to roots.

A Metabolic Model for the Ocean QuahogArctica islandica—Effects of Animal Mass and Age, Temperature, Salinity, and Geography on Respiration Rate

Owing to its extraordinary lifespan and wide geographical distribution along the continental margins of the North Atlantic Ocean, the ocean quahog Arctica islandica may become an important indicator species in environmental change research. To test for applicability and ''calibrate'' the Arctica-indicator, metabolic properties of A. islandica specimens were compared across different climatic and oceanographic regions. Fully saline populations from Iceland to the North Sea as well as animals from polyhaline and low salinity, environments, the White Sea and the Baltic were included in the study. This calibration centrally includes recordings of growth-age relationships in different populations. Shells were used as age recorders by counting annual growth bands. As a result of this study, we propose a general respiration model that links individual metabolic rates of A. islandica from five populations: Norwegian coast, Kattegat, Kiel Bay (Baltic Sea), White Sea and German Bight (North Sea), to body mass, water temperature and site. Temperature exerts distinct site specific effects on respiration rate, which is indicated by Q10 values ranging from 4.48 for German Bight to 1.15 for Kiel Bay animals. Individual age, occurrence of apneal respiratory gaps, parasite infestation and salinity do not affect respiration rate. Respiration of Arctica islandica is significantly below the average of 59 bivalve species when compared at the same temperature and animal mass. This respiration model principally enables the coupling of A. islandica life history and population dynamics to regional oceanographic temperature models.

Shelf-life extension of minimally processed carrots by gaseous chlorine dioxide

Chlorine dioxide (ClO 2) gas is a strong oxidizing and sanitizing agent that has a broad and high biocidal effectiveness and big penetration ability; its efficacy to prolong the shelf-life of a minimally processed (MP) vegetable, grated carrots ( Daucus carota L.), was tested in this study. Carrots were sorted, their ends removed, hand peeled, cut, washed, spin dried and separated in 2 portions, one to be treated with ClO 2 gas and the other to remain untreated for comparisons. MP carrots were decontaminated in a cabinet at 91% relative humidity and 28 °C for up to 6 min, including 30 s of ClO 2 injection to the cabinet, then stored under equilibrium modified atmosphere (4.5% O 2, 8.9% CO 2, 86.6% N 2) at 7 °C for shelf-life studies. ClO 2 concentration in the cabinet rose to 1.33 mg/l after 30 s of treatment, and then fell to nil before 6 min. The shelf-life study included: O 2 and CO 2 headspace concentrations, microbiological quality (mesophilic aerobic bacteria, psychrotrophs, lactic acid bacteria, and yeasts), sensory quality (odour, flavour, texture, overall visual quality, and white blushing), and pH. ClO 2 did not affect respiration rate of MP carrots significantly ( α ≤ 0.05), and lowered the pH significantly ( α ≤ 0.05). The applied packaging configuration kept O 2 headspace concentrations in treated samples in equilibrium and prevented CO 2 accumulation. After ClO 2 treatment, the decontamination levels (log CFU/g) achieved were 1.88, 1.71, 2.60, and 0.66 for mesophilic aerobic bacteria, psychrotrophs, and yeasts respectively. The initial sensory quality of MP carrots was not impaired significantly ( α ≤ 0.05). A lag phase of at least 2 days was observed for mesophilic aerobic bacteria, psychrotrophs, and lactic acid bacteria in treated samples, while mesophilic aerobic bacteria and psychrotrophs increased parallelly. Odour was the only important attribute in sensory deterioration, but it reached an unacceptable score when samples were already rejected from the microbiological point of view. The shelf-life extension was limited to one day due to the restricted effect of the ClO 2 treatment on yeast counts. Nevertheless, ClO 2 seems to be a promising alternative to prolong the shelf-life of grated carrots.

Storage response of cactus pear fruit following hot water brushing

The storage response of cactus pear [ Opuntia ficus-indica Miller (L.)] following hot water brushing was investigated. Fruit were simultaneously brushed for spine removal and sprayed with water. Ranges of temperature (60–70 °C) and treatment time intervals (10–30 s) were evaluated. All tested treatments were found not to significantly affect respiration rate, total soluble solids or acid concentrations. Treatments at 60 and 65 °C were found to reduce water loss and the incidence of rusty-brown spots on fruit peel. At higher temperatures, some negative effects were observed, namely increased electrolyte leakage and extended light brown areas on the fruit peel, indicating heat damage to the fruit. All the treatments effectively controlled decay in fruit stored at 6 ± 1 °C for 4 weeks followed by 1 week at 20 ± 1 °C. The effectiveness of treatments to control decay was increased with temperature and treatment time. Based on the results of this study, treatments at 60 °C for 30 s or 65 °C for 20 s reduced the decay incidence by 86–91% without compromising fruit quality. These treatments can be easily applied in commercial practice with slight modification of the despining facilities in use.

EFFECTS OF GIBBERELLIC ACID ON THE VASE LIFE OF CUT PATUMMA (CURCUMA ALISMATIFOLIA GAGNEP.) 'CHAING MAI' FLOWERS

Cutflowers of Patumma (Curcuma alismatifolia Gagnep.) ‘Chaing Mai’ were held in 50-200 ppm gibberellic acid (GA3) or distilled water (control) at 25°C with 75-80% relative humidity. GA3 at 100 ppm increased vase life by four days compared to the control (10 days). Increasing the concentration to 150-200 ppm did not correspondingly extend vase life despite improvement in weight retention, absorption capacity and water conductivity of stem tissues. The vase life of the flower held in 150-200 ppm GA3 was similar to that with 100 ppm GA3. GA3 did not generally affect respiration rate but significantly reduced ethylene production. At lower concentration of 50 ppm GA3, responses of the flowers were comparable to the control.

Effect of the Combination of MCP and Sanitizer on Storage Life of Fresh-cut Cilantro

The effects of 1-methylcyclopropene (MCP), sanitizer and their combination on ethylene action, microbial growth and storage life of fresh-cut cilantro were studied. Fresh cilantro was treated with 1.5 μL·L-1 MCP for 18 hours at 10 °C. The treated and nontreated cilantro leaves were cut and washed in water, chlorine, and mixed solution of sodium chlorite and citric acid (SANOVA). Samples were dried, packaged with 29.2μmol·kg-1 Pa s oxygen transmission rate films, and stored for 14 days at 5 °C. Results indicated that MCP affected respiration rate of fresh-cut cilantro and the headspace gas composition (O2 and CO2) of sample packages. The combined treatment had lower tissue electrolyte leakage and ethanol concentration, and delayed color changes during storage. SANOVA and the combination of MCP and SANOVA were effective in reducing aerobic microbial population and coliform population. Samples treated with MCP and SANOVA had good quality with high overall quality score at the end of storage.

Soil microbial eco-physiology as affected by short-term variations in environmental conditions

Short-term variations in abiotic and biotic environmental conditions modify microbial metabolism. These effects were studied in an arable soil during the oat straw decomposition. Cumulative CO 2 evolution was significantly higher when soil was subjected weekly to drying–rewetting cycles (DR) or had been initially fertilised with nitrogen (+N, as NH 4NO 3) in comparison to samples incubated at constant conditions (CC). The microbial metabolic quotient (respiration rate per unit microbial C) of DR and +N exceeded CC by approximately 100–150%, indicating that variable water availability and improved N availability induced a higher activity level of the microbial biomass. In addition, the metabolic-responsive microbial communities, calculated by the ratio of microbial C estimated by substrate-induced respiration to fumigation–extraction technique, increased from 1.0 to approximately 1.3 after 7 weeks for DR and +N, but remained essentially at 1.0 for CC and control. A high abundance of soil nematodes significantly affected respiration rate, metabolic-responsive biomass and metabolic quotient during the early stages of decomposition. We concluded that short-term variation in environmental conditions promoted decomposition processes by influencing the physiology of soil microorganisms and increasing the metabolic-responsive biomass. Such a stimulated microbial metabolism seems to be unspecific due to stressing environmental conditions. The role of the interacting fauna such as nematodes varied during decomposition.

Effects of size and light on respiration and activity of walleye pollock (Theragra chalcogramma) larvae.

The respiration rate and swimming activity of walleye pollock (Theragra chalcogramma) larvae were measured in the laboratory to determine how these were affected by body size (measured as dry weight), and amount of light. Size influenced respiration rates, but not activity. Activity increased with increased light, and as walleye pollock larvae developed, light had an increasingly important effect on respiration rate. For older larvae, light is an important factor affecting respiration rate and this may be due to an increased sensitivity to light. Thus, in addition to size, light plays an important role in the energetics of walleye pollock larvae.

A semi-closed recirculating system for the in situ study of feeding and respiration of benthic suspension feeders

Suspension feeding is one of the most widespread feeding strategies among benthic organisms. However, natural feeding ecology and energetics of benthic suspension feeders are poorly known. The scarcity of field methods, apparatus and protocols that facilitate obtention of reliable in situ data has contributed to this lack of knowledge. A detailed description of an improved semi-closed recirculating system as well as the experimental set up is provided for the study of energetics in benthic suspension feeders. The system, completely submersible and surface-independent, allows us to assess oxygen concentration changes and feeding rates under natural conditions. Methodological examinations are conducted to investigate: a) the circulation of the water within the chamber; b) the time required for the flushing pump to entirely renew the volume of water of the incubation chambers; c) the behavior of the species within the chambers; d) the time of acclimation to the chamber conditions for the different species; e) the maximum decrease in oxygen concentration without affecting respiration rate; f) the time required to detect changes in concentration of the natural food sources. The system and experimental protocol is tested with species from three representative phyla, Porifera, Cnidaria and Tunicata.

100 Microbial Evaluation of Electrolyzed Water Treated Fresh-cut Carrots in CA/MA Storage

The effect of electrolyzed water on bacterial count was evaluated on CA/MA stored carrot shreds. Electrolyzed water (pH 6.8) containing 50 ppm available chlorine, was generated by electrolysis of 2.5% NaCl solution using an electrolyzed neutral water generator, Ameni Clean (Matsushita Seiko, Osaka, Japan). Electrolyzed water treatment reduced counts of total bacteria and lactic acid bacteria on surface of carrot shreds by about 1 log CFU/g as compared to water-rinsed control. Microbial population increased on treated carrot shreds stored in air or 3% O2 atmosphere at 10 or 20 °C. The increasing count of lactic acid bacteria was less on electrolyzed water treated samples than on control samples during storage at 10 °C. Electrolyzed water did not affect respiration rate of carrot shreds during storage at 10 and 20 °C. For MA study, the treated carrot shreds were packaged and stored in a polymeric film in which the O2 and CO2 concentrations equilibrated to about 10% and 3% at 10 °C and about 6% and 7% at 20 °C, respectively. The lactic acid bacterial count on shreds in MAP was lower with electrolyzed water treated samples than water treated controls during storage at 10 and 20 °C.

Effects of temperature on gas exchange of ‘Braeburn’ apples

Gas exchange attributes of fruits affect their responses to modified atmosphere and surface coating treatments. In this study, variations in respiration rate, internal partial pressures of O2 and CO2, and skin permeance to O2 and CO2 associated with storage at 0, 5, 10, 15, 20, 25, and 30°C were characterised in ‘Braeburn’ apples (Malus domestica Borkh.) There was an 11‐fold difference in respiration rate between fruit kept at 0 and 30°C, although permeance to each of the two respiratory gases differed only by a factor of two. The differing effects of temperature upon these two variables was responsible for the depression of internal O2 and elevation of internal CO2associated with increase in temperature from 0 to 30°C. The magnitude of decline in internal O2 was slightly greater than the increase in internal CO2 over the temperature range in the experiment. For apples that were respiring aerobically, and with a respiratory quotient of unity, this would indicate that the fruit skin had a somewhat higher permeance to CO2 than to O2, Permeance values for the two respiratory gases were strongly related but permeance to CO2 exceeded that to O2 for fruit with a low permeance to O2. This is attributable to the greater ease of diffusion of CO2 through the cuticle, an effect which became more pronounced as transcuticular diffusion was facilitated at high temperatures. Given the importance of internal atmosphere composition in affecting respiration rate and disorder development in apples, the gas exchange characteristics of ‘Braeburn’ appear likely to be influential in the outcome of different storage regimes.

Predominance of ecophysiological controls on soil CO2 flux in a Minnesota grassland

Ecosystem studies often study soil CO2 flux as a function of environmental factors, such as temperature, that affect respiration rates by changing the rate of utilization of carbon substrates. These studies tend not to include factors, such as photosynthesis, that affect the supply of carbon substrates to roots and root-associated processes. We examined the role of decreased carbohydrate source on soil CO2 flux and root respiration in an annually-burned grassland through manipulations of light intensity and removal of above ground biomass. We also quantified the contribution of root respiration to soil CO2 flux by measuring the respiration rates of excised roots. Two days of shading caused a 40% reduction in soil CO2 flux, while clipping was associated with a 19% reduction in soil CO2 flux. Both reductions were independent of soil and air temperature at the time of measurement. The relative decrease in soil CO2 flux observed in the clipping experiment was similar in magnitude to an observed decrease in root respiration per gram of root, linking decreased root activity and soil CO2 flux. From these experiments, we conclude that variation in factors that affect carbon availability to roots can be important determinants of soil CO2 flux and should be included explicitly in studies that measure or model soil CO2 flux.

Effect of salinity, temperature and acclimation on oxygen consumption of Nassarius festivus (Powys, 1835) (Gastropoda: Nassariidae)

Abstract Temperature tolerance ( lt 50) of the scavenging gastropod Nassarius festivus was determined as 22.5, 64.3 and 160 hr at temperatures of 38, 36 and 33°C, respectively. Hyposalinity tolerance ( lt 50) at salinities of 0, 5 and 10‰ was found to be 60, 67 and 170 hr respectively. Respiration rate was measured at combinations of four levels of temperature (20, 25, 30 and 35°C) and six levels of salinity (10, 15, 20, 25, 30 and 35‰) before and after acclimation. Temperature, salinity and their interactions were significant in affecting respiration rate of both non-acclimated and acclimated individuals. Among these, salinity has the greatest effect. Although respiration rate was increased following acclimation, the values obtained were lower than the control, indicating incomplete acclimation.

Influence of environment on respiration, heart rate and body temperature of filial crosses compared to local Awassi sheep

Sheep in the study were on the American University of Beirut Agricultural Research and Education Center in the Beka'a Valley of Lebanon. The flock ( n = 36) had native Awassi (A) and crossbreds from imported Finn Landrace (F), Texel (T) and FT crosses. Respiration rates were higher for all animals at higher ambient temperatures. Genotype ( P < 0.05) affected respiration rate, with Awassi having lower rates than filial crosses (63.8 vs. 76.5 breaths/min) during all seasons. Animal sex also ( P < 0.05) affected respiration rate between crosses and Awassi (71.2 vs. 49.6 breaths/min). Awassi classes differed ( P < 0.05) from each other during the summer with young females having highest rates (90.7 breaths/min). Shearing caused ( P > 0.05) changes between the crosses and Awassi during summer. Heart rates of the crosses were ( P < 0.05) higher than of Awassi during fall and spring seasons (116.3, 125.8 vs. 104.8, 117.1 beats/min, respectively). Young filial males had ( P < 0.05) higher pulse rates than the same Awassi class during all seasons. Body temperatures of filial crosses during all seasons were ( P > 0.05) higher than Awassi (39.41 vs. 39.31 °C). Rectal temperatures increased with higher ambient temperatures and were lower in the morning hours. Filial crosses had higher respiration, heart rate and body temperature than Awassi. Age and sex of the animal, breed and season influenced physiological parameters. Awassi were more adapted and tolerant of prevailing conditions although the filial crosses survived these conditions.