scholarly journals Temperature affects the hypoxia tolerance of neotropical Cichlid Geophagus brasiliensis

2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Jéssica A. Pereira ◽  
Alexandra C.S. Veronez ◽  
Gabriel C. Coppo ◽  
Charles Duca ◽  
Adriana R. Chippari-Gomes ◽  
...  
Keyword(s):  
White Muscle ◽  
Citrate Synthase ◽  
Hypoxia Tolerance ◽  
Limiting Factors ◽  
Biological Processes ◽  
Significant Difference ◽  
Geophagus Brasiliensis ◽  
Different Temperatures ◽  
Increased Activity ◽  
Main Strategy

ABSTRACT Oxygen and temperature are the most limiting factors in aquatic environments. Several species are exposed to variations of these factors in water because of physical, chemical and biological processes. The objective of this study was to evaluate the metabolic profile and the tolerance to the hypoxia of Geophagus brasiliensis exposed to changes in temperature and oxygen availability. The fish were exposed to 20 and 90% of oxygen saturation combined with different temperatures (20°, 24° and 28° C) for 8 h. Hepatic and muscular glycogen, as well as the activities of lactate dehydrogenase (LDH), malate dehydrogenase (MDH), citrate synthase (CS) and their ratios were evaluated. Both glycogen and MDH activity showed a significant difference in the liver. While CS showed increased activity only in the heart. The increase in LDH activity in the white muscle shows the importance of the anaerobic pathway as energy source in this tissue. The MDH / LDH ratio increased in all tissues, while CS / LDH increased in the liver and decreased in the heart. Based on the results of the present study it may be concluded that this species used the anaerobic metabolism as the main strategy for hypoxia tolerance.

scholarly journals Effect of water temperature and salinity in oviposition, hatching success and infestation of Aphanoblastella mastigatus (Monogenea, Dactylogyridae) on Rhamdia quelen

2015 ◽  
Vol 75 (4 suppl 1) ◽  
pp. 245-252 ◽  
Author(s):  
N. C. Marchiori ◽  
E. L. T. Gonçalves ◽  
K. R. Tancredo ◽  
J. Pereira-Junior ◽  
J. R. E. Garcia ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Aquatic Invertebrates ◽  
Prophylactic Treatment ◽  
Hatching Success ◽  
Environmental Parameters ◽  
Biological Processes ◽  
Significant Difference ◽  
Rhamdia Quelen ◽  
Different Temperatures ◽  
Effects Of Temperature

Abstract Several environmental parameters may influence biological processes of several aquatic invertebrates, such as the Monogenea. Current analysis investigates oviposition, hatching success and infestation of Aphanoblastella mastigatus, a parasite of the silver catfish Rhamdia quelen at different temperatures (~ 24 and 28 °C) and salinity (by adding sodium chloride to water, at concentrations 0, 5 and 9 g/L) in laboratory. There was no significant difference in oviposition rate and in A. mastigatus infestation success at 24 and 28 °C. On the other hand, the concentration 9 g/L of sodium chloride in the water impaired the parasite’s survival and the viability of the eggs. Results show that its usage is efficient as a possible prophylactic treatment. Eclosion rate of A. mastigatus’s eggs was significantly higher at 28 °C, although it was significantly less from 5 g/L. Two oviposition peaks (06h15 and 18h15) occurred during a 24-hour period, or rather, during the highest variations in luminosity. Further studies are recommended with greater temperature intervals and more intense experimental infestations to verify the effects of temperature in the life span and infestation success of A. mastigatus.

scholarly journals Seed longevity of maize conserved under germplasm bank conditions for up to 60 years

2021 ◽  
Author(s):  
Filippo Guzzon ◽  
Maraeva Gianella ◽  
Jose Alejandro Velazquez Juarez ◽  
Cesar Sanchez Cano ◽  
Denise E Costich
Keyword(s):  
Seed Germination ◽  
Plant Genetic Resources ◽  
Seed Viability ◽  
Storage Conditions ◽  
Seed Longevity ◽  
Germplasm Bank ◽  
Significant Difference ◽  
Different Temperatures ◽  
Germination Experiments

Abstract Background and Aims The long-term conservation of seeds of plant genetic resources is of key importance for food security and preservation of agrobiodiversity. Nevertheless, there is scarce information available about seed longevity of many crops under germplasm bank conditions. Methods Through germination experiments as well as the analysis of historical monitoring data, we studied the decline in viability manifested by 1000 maize (Zea mays subsp. mays) seed accessions conserved for an average of 48 years at the CIMMYT germplasm bank, the largest maize seedbank in the world, under two cold storage conditions: an active (–3 °C; intended for seed distribution) and a base conservation chamber (–15 °C; for long-term conservation). Key Results Seed lots stored in the active chamber had a significantly lower and more variable seed germination, averaging 81.4 %, as compared with the seed lots conserved in the base chamber, averaging 92.1 %. The average seed viability detected in this study was higher in comparison with that found in other seed longevity studies on maize conserved under similar conditions. A significant difference was detected in seed germination and longevity estimates (e.g. p85 and p50) among accessions. Correlating seed longevity with seed traits and passport data, grain type showed the strongest correlation, with flint varieties being longer lived than floury and dent types. Conclusions The more rapid loss of seed viability detected in the active chamber suggests that the seed conservation approach, based on the storage of the same seed accessions in two chambers with different temperatures, might be counterproductive for overall long-term conservation and that base conditions should be applied in both. The significant differences detected in seed longevity among accessions underscores that different viability monitoring and regeneration intervals should be applied to groups of accessions showing different longevity profiles.

scholarly journals NMR Experiments Shed New Light on Glycan Recognition by Human and Murine Norovirus Capsid Proteins

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 416
Author(s):  
Robert Creutznacher ◽  
Thorben Maass ◽  
Patrick Ogrissek ◽  
Georg Wallmann ◽  
Clara Feldmann ◽  
...  
Keyword(s):  
Blood Group ◽  
Protein Interactions ◽  
Capsid Proteins ◽  
Blood Group Antigens ◽  
Biological Processes ◽  
Murine Norovirus ◽  
Human Norovirus ◽  
Head Groups ◽  
Significant Difference

Glycan–protein interactions are highly specific yet transient, rendering glycans ideal recognition signals in a variety of biological processes. In human norovirus (HuNoV) infection, histo-blood group antigens (HBGAs) play an essential but poorly understood role. For murine norovirus infection (MNV), sialylated glycolipids or glycoproteins appear to be important. It has also been suggested that HuNoV capsid proteins bind to sialylated ganglioside head groups. Here, we study the binding of HBGAs and sialoglycans to HuNoV and MNV capsid proteins using NMR experiments. Surprisingly, the experiments show that none of the norovirus P-domains bind to sialoglycans. Notably, MNV P-domains do not bind to any of the glycans studied, and MNV-1 infection of cells deficient in surface sialoglycans shows no significant difference compared to cells expressing respective glycans. These findings redefine glycan recognition by noroviruses, challenging present models of infection.

scholarly journals Reaction Kinetics of Iron Oxides in Ok Tedi Magnetite Skarn Ore

2020 ◽  
pp. 1-13
Author(s):  
Mary Kama ◽  
Kaul Gena ◽  
Tindi Seje Nuru
Keyword(s):  
Reaction Kinetics ◽  
Papua New Guinea ◽  
Iron Reduction ◽  
New Guinea ◽  
Reaction Rate Constant ◽  
Close Monitoring ◽  
Significant Difference ◽  
Different Temperatures ◽  
C 30 ◽  
Kinetics Of

Magnetic skarn ore (MSO) is one of the major copper bearing ore extracted by the Ok Tedi Copper Mine in Papua New Guinea (PNG). Copper minerals are recovered by flotation while the iron not associated with copper are discarded as tailings. The objective of this investigation was to determine the iron ore reduction kinetics for the Ok Tedi MSO and ascertain if it can be processed to produce sponge iron for a mini steel plant in Papua New Guinea. SEM-EDAX analyses of the Ok Tedi MSO indicated 10.1% C, 30% O, 0.6% Mg, 1.1% Si, 21.1% S, 0.8% Ca and 36.2 % Fe. Most of the iron is in sulfide form. Both naturally occurring and roasted sinters of Ok Tedi MSO samples of different particle sizes were reduced by charcoal carbon at three different temperatures and seven different reduction times. Analyses of the reduced products indicated a metallic iron content of more than 65 wt. % on average. Results showed that there was no significant difference in reduction between fluxed and control materials. Only a slight increase in kinetics with reduced particle size, hence the reaction rate constant (K) did not vary much within the temperatures investigated. Reaction kinetics increases with increasing reduction time at 900°C. Therefore, more iron reduction is observed with particles of 106 µm size. In addition, the results also confirmed that the reduction energy used was higher at 800°C and lower at 1000°C. In conclusion, iron reduction can be improved but close monitoring of temperature and reduction times are essential to determine the reaction kinetics of the Ok Tedi MSO.

scholarly journals Oxidative properties of carp red and white muscle

1989 ◽  
Vol 143 (1) ◽  
pp. 321-331 ◽  
Author(s):  
C. D. Moyes ◽  
L. T. Buck ◽  
P. W. Hochachka ◽  
R. K. Suarez
Keyword(s):  
Amino Acids ◽  
White Muscle ◽  
Citrate Synthase ◽  
Ketone Bodies ◽  
Redox Balance ◽  
Fatty Acyl ◽  
Oxidation Rates ◽  
Substrate Preferences ◽  
Glycerophosphate Dehydrogenase ◽  
Wide Range

Substrate preferences of isolated mitochondria and maximal enzyme activities were used to assess the oxidative capacities of red muscle (RM) and white muscle (WM) of carp (Cyprinus carpio). A 14-fold higher activity of citrate synthase (CS) in RM reflects the higher mitochondrial density in this tissue. RM mitochondria oxidize pyruvate and fatty acyl carnitines (8:O, 12:O, 16:O) at similarly high rates. WM mitochondria oxidize these fatty acyl carnitines at 35–70% the rate of pyruvate, depending on chain length. WM has only half the carnitine palmitoyl transferase/CS ratio of RM, but similar ratios of beta-hydroxyacyl CoA dehydrogenase/CS. Ketone bodies are poor substrates for mitochondria from both tissues. In both tissues mitochondrial alpha-glycerophosphate oxidation was minimal, and alpha-glycerophosphate dehydrogenase was present at low activities, suggesting the alpha-glycerophosphate shuttle is of minor significance in maintaining cytosolic redox balance in either tissue. The mitochondrial oxidation rates of other substrates relative to pyruvate are as follows: alpha-ketoglutarate 90% (RM and WM); glutamate 45% (WM) and 70% (RM); proline 20% (WM) and 45% (RM). Oxidation of neutral amino acids (serine, glycine, alanine, beta-alanine) was not consistently detectable. These data suggest that RM and WM differ in mitochondrial properties as well as mitochondrial abundance. Whereas RM mitochondria appear to be able to utilize a wide range of metabolic fuels (fatty acids, pyruvate, amino acids but not ketone bodies), WM mitochondria appear to be specialized to use pyruvate.

scholarly journals The effect of temperature change on fluoride uptake from a mouthrinse by enamel specimens

2012 ◽  
Vol 06 (04) ◽  
pp. 361-369 ◽  
Author(s):  
Serdar Baglar ◽  
Adil Nalcaci ◽  
Mustafa Tastekin
Keyword(s):  
Body Temperature ◽  
Room Temperature ◽  
Hot Water ◽  
Effect Of Temperature ◽  
Distilled Water ◽  
Fluoride Solution ◽  
Fluoride Uptake ◽  
Significant Difference ◽  
Human Body Temperature ◽  
Different Temperatures

ABSTRACTObjective: The aim of this study was to examine the effect of temperature on fluoride uptake by enamel specimens from a 0.05% NaF-fluoridated mouthrinse (Oral-B Advantage; Oral-B Laboratories, Newbridge, UK).Methods: Enamel specimens were prepared from extracted human maxillary central incisors. A fluoride-specific ion electrode was used to measure the uptake from a 2 ppm fluoride solution containing 50.0 mL of distilled water, total ion strength adjustment buffer, and fluoridated rinse at 3 different temperatures (room temperature, 25°C; human body temperature, 37°C; hyper-fever temperature, 43°C). One-way analysis of variance and least significant difference were used to assess intragroup and intergroup differences (P<.05).Results: The study found that both the amount and the rate of fluoride uptake increased significantly with increase in temperature. This effect was particularly noticeable at 43°C.Conclusions: The temperature of the NaF mouthrinse may easily and safely be increased beyond room temperature by placing a container of the NaF mouthrinse in a bowl of hot water, allowing greater fluoride penetration into the enamel from the mouthrinse when used at home as a routine prophylactic agent. (Eur J Dent 2012;6:361-369)

scholarly journals Lipolysis and oxidation of lipids during egg storage at different temperatures

2017 ◽  
Vol 35 (No. 3) ◽  
pp. 229-235 ◽  
Author(s):  
Qingling Wang ◽  
Guofeng Jin ◽  
Ning Wang ◽  
Yongguo Jin ◽  
Meihu Ma ◽  
...  
Keyword(s):  
Lipase Activity ◽  
Storage Temperature ◽  
Egg Yolk ◽  
Lipid Profiles ◽  
Composition Analysis ◽  
C Storage ◽  
Physicochemical Index ◽  
Significant Difference ◽  
Different Temperatures ◽  
Egg Storage

The aim of this study was to investigate lipolysis and lipid oxidation of stored eggs at different temperatures (4 and 22°C) by evaluating the changes in physicochemical index, lipid profiles, enzymatic activity, and oxidative index. The results showed that the changes in physicochemical index were more significant at 22°C than at 4°C. Weight loss, moisture content, and pH of egg yolk increased significantly (P &lt; 0.05), whereas the yolk index decreased during storage. However, there was no significant difference in lipid profiles between 4 and 22°C storage temperature. The lipid composition analysis demonstrated that lipid hydrolysis took place during egg storage and resulted in a marked decrease of PL and increase of FFA. It was also found that the content of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylinositol (PI) decreased significantly during storage. The correlation analysis showed that the lipid degradation is significantly positively related to lipase activity (P &lt; 0.05), and the marked changes of lipid fractions are results of both hydrolysis and oxidation. It can be concluded that the egg physicochemical index and lipase activity were greatly influenced by temperature during storage, but the yolk lipid stability was not significantly influenced by storage temperature.

scholarly journals Changes of antioxidant activity in honey after heat treatment

2013 ◽  
Vol 31 (No. 6) ◽  
pp. 601-606 ◽  
Author(s):  
G. Šarić ◽  
K. Marković ◽  
D. Vukičević ◽  
E. Lež ◽  
M. Hruškar ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Total Phenolic Content ◽  
Phenolic Content ◽  
Total Phenolic ◽  
Antioxidant Power ◽  
Dpph Method ◽  
Significant Difference ◽  
Acacia Honey ◽  
Different Temperatures ◽  
Ferric Reducing Antioxidant Power

We determined how the antioxidant activity and total phenolic content of honey changed after being subjected to a high temperature. Antioxidant activity was determined using two methods &ndash; FRAP (ferric reducing antioxidant power) and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays. Total phenolic content was determined by modified Folin-Ciocalteu method. The research was conducted on 31 samples of acacia honey and 8 samples of chestnut honey. All measurements were done at two temperatures &ndash; at 23&deg;C (room temperature) and after 5 min of heating at 95&deg;C. The obtained results show uneven changes of antioxidant activity and total phenolic content among individual samples, i.e. in some samples antioxidant activity decreased after heating, while in others it increased. The same applies to the total phenolic content. Statistical analysis of the results (t-test) showed no statistically significant differences between the results measured at two different temperatures (P &gt; 0.05) in all three methods used, and in both types of honey. The only statistically significant difference (P &lt; 0.05) was observed when using DPPH method in acacia honey.

Competition Between Saccade Goals in the Superior Colliculus Produces Saccade Curvature

2003 ◽  
Vol 89 (5) ◽  
pp. 2577-2590 ◽  
Author(s):  
Robert M. McPeek ◽  
Jae H. Han ◽  
Edward L. Keller
Keyword(s):  
Superior Colliculus ◽  
Search Task ◽  
Visual Target ◽  
Temporal Structure ◽  
Saccade Target ◽  
Stimulation Site ◽  
Electrical Microstimulation ◽  
Saccade Onset ◽  
Significant Difference ◽  
Increased Activity

When saccadic eye movements are made in a search task that requires selecting a target from distractors, the movements show greater curvature in their trajectories than similar saccades made to single stimuli. To test the hypothesis that this increase in curvature arises from competitive interactions between saccade goals occurring near the time of movement onset, we performed single-unit recording and microstimulation experiments in the superior colliculus (SC). We found that saccades that ended near the target but curved toward a distractor were accompanied by increased presaccadic activity of SC neurons coding the distractor site. This increased activity occurred ∼30 ms before saccade onset and was abruptly quenched on saccade initiation. The magnitude of increased activity at the distractor site was correlated with the amount of curvature toward the distractor. In contrast, neurons coding the target location did not show any significant difference in discharge for curved versus straight saccades. To determine whether this pattern of SC discharge is causally related to saccade curvature, we performed a second series of experiments using electrical microstimulation. Monkeys made saccades to single visual stimuli presented without distractors, and we stimulated sites in the SC that would have corresponded to distractor sites in the search task. The stimulation was subthreshold for evoking saccades, but when its temporal structure mimicked the activity recorded for curved saccades in search, the subsequent saccades to the visual target showed curvature toward the location coded by the stimulation site. The effect was larger for higher stimulation frequencies and when the stimulation site was in the same colliculus as the representation of the visual target. These results support the hypothesis that the increased saccade curvature observed in search arises from rivalry between target and distractor goals and are consistent with the idea that the SC is involved in the competitive neural interactions underlying saccade target selection.

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