Understanding feeding competition under laboratory conditions: Rohu (Labeo rohita) versus Amazon sailfin catfish (Pterygoplichthys spp.)

Competitive interactions between species is widely prevalent within the animal world. In this manuscript, we attempted to understand feeding competitions between the Amazon sailfin catfish, an invasive species introduced globally, and rohu, a keystone species native to several countries within southeast Asia. We used two different size classes of each species, large-size having total length (TL, from snout tip to caudal fin) of 15-20 cm and fingerling having TL<6 cm, and feeding duration was used as a proxy to understand competition. Our results demonstrated that feeding durations of large-size rohu were either similar or significantly (P<0.05) higher in presence of catfish when compared to trials in presence of conspecifics, indicating that large-size rohu is not a weak competitor. However, feeding durations of fingerling rohu was significantly (P<0.05) reduced in presence of both large-size and fingerling catfish, when compared to trials in presence of conspecifics. Moreover, fingerling rohu also displayed freeze (alarm) behavior in presence of the catfish. Interestingly, presence of rohu had no significant (P>0.05) impact on feeding durations of catfish. Overall, the study demonstrated that invasive catfish may behaviorally outcompete fingerling rohu, thus, threatening the sustenance of a species that is native to several freshwaters around the globe.

Measuring Total Mercury Through Freeze-Thaw Cycles

Total mercury (THg) analysis of fish tissue requires the samples to be frozen for long-term storage or analyzed immediately after the fish sample has been obtained. Such rigid field sampling protocols do not account for the logistical challenges that can occur if sampling is conducted in remote areas or collaboratively via community-based monitoring initiatives. Here we present a study that examines the loss of THg from Walleye tissue that has thawed for 3 and 5 days, mimicking potential thaw during transport from remote locations. THg concentrations were not significantly influenced (Kruskal-Wallace, p-value > 0.05) by the thaw and refreeze events. The mean THg concentration per day group was 0.67 ug/g, SD = 0.03, 0.65 ug/g, SD = 0.01, and 0.72 ug/g, SD = 0.01 for the control (no thaw), 3-day thaw and 5-day thaw, respectively. Results from this study suggest the analytical integrity of samples may be maintained if freeze-thaw situations arise when conducting community-based mercury monitoring programs.

Cellular and Molecular Consequences of Stallion Sperm Cryopreservation: Recent Approaches to Improve Sperm Survival

Cryopreservation of stallion semen does not achieve the post-thaw quality or fertility results observed in other species like cattle. There are many reasons for this, but the membrane composition and intracellular changes in stallion sperm predispose them to low resistance to the cooling, freezing, and subsequent thawing process. Damage to the sperm results from different processes activated during cryopreservation, including oxidative stress, apoptosis, and structural modifications in the sperm membrane that increase the deleterious effect on sperm. In addition, significant individual variability is observed among stallions in the ability of sperm to survive the freeze-thaw process. Recent advances in genomics, transcriptomics, proteomics, metabolomics, and epigenetics are making it possible to advance our understanding of the cellular and molecular processes involved in the cryopreservation process, opening new possibilities for improvement. This review addresses the ongoing research on stallion semen cryopreservation, focusing on the cellular and molecular consequences of this procedure in stallions and discusses the new tools currently available to increase the tolerance of equine spermatozoa to freeze-thaw.

Photodegradation of norfloxacin in ice: Role of the fluorine substituent

Ice is an important medium in cold regions, because it regulates the environmental behaviors and the fate of pollutants. The photodegradation of fluoroquinolone (FQ) antibiotics as emerging contaminants of concern in ice remains poorly understood. Here, the photodegradation of fluorine-containing norfloxacin (NOR) as one model of FQs in ice formed from freezing solutions was investigated. Pipemidic acid (PPA) as a structural analogue of NOR was selected to compare the effect of molecular structure on the antibiotic photodegradation in the ice. Results suggested that the photodegradation rate constant of NOR in ice relative to pure water increased by 40.0%. Both the absorbance in the absorption spectra and quantum yields of NOR in ice over water increased by 1.4 times. Direct photodegradation mainly caused the defluorination of NOR, which was more important than cleavage and oxidation of the piperazine ring by self-sensitized photooxidation in ice. The defluorination rate of NOR in the ice relative to water increased by about 12.7%. The fluorine substituent played a more important role in the NOR photodegradation in the ice, resulting in a 1.6-fold increase in the photodegradation rate constant of NOR relative to PPA. This work provides a new insight into the role of fluorine substituents in the photodegradation of fluorinated pharmaceuticals in cold regions.

Gelation behavior of egg yolk under physical and chemical induction: A review

Gelation is one of the most important functional properties of egg yolk. High content and rich variety of protein and lipid in egg yolk are the material basis of gel formation. The natural structure of proteins in egg yolk is unfolded under treatments such as heat, alkali, salt, etc., thus causing the interactions between protein-protein and protein-lipid and forming the gel. Under different methods of induction, egg yolk is solidified to form different three-dimensional network structures. Different inducing methods exhibit different gel formation mechanisms. In this paper, the gelation behavior of egg yolk and its internal molecular agglomeration mechanism induced by heat, alkali, salt, freezing, high pressure, and salt-heating synergy were reviewed to provide a reference for further studies on the formation mechanisms and product development of egg yolk gel.

Does resveratrol affect prepared sperm parameters and chromatin quality in normozoospermic and asthenozoospermic patients before and after freezing? A lab trial study

Background

Previous studies have examined the effect of resveratrol as a potent antioxidant for free radicals in semen. While, the prepared spermatozoa are more affected by ROS factors due to centrifugation and incubation.

Objective

To evaluate the RSV's effects on the prepared sperm parameters and chromatin quality in both normozoospermic and asthenozoospermic cases before and after freezing.

Materials and Methods

The sample of 10 normozoospermic and asthenozoospermic men was prepared through the swim-up method. The groups were then divided into two samples of control and experimental (exposure to 30 µmol/l of RSV) to evaluate and compare the sperm parameters and chromatin quality before and after freezing.

Results

The motility and viability of spermatozoa were seen to be significantly different before and after freezing separately in the control and treatment samples of the groups (p ≤ 0.001 and p = 0.001, respectively). However, the stated difference between the control and treatment samples of normozoospermic and asthenozoospermic patients were not significant (p > 0.05). In addition, the sperm morphology and chromatin quality were not significantly different between the two samples of each group; nonetheless, chromatin quality of the treated sample was better than that of the control before and after freezing.

Conclusion

Despite the protective effects of RSV on the semen samples, RSV cannot affect significantly the prepared sperms parameters and chromatin quality in normozoospermic and asthenozoospermic patients.

Presence of a basic secretory protein in xylem sap and shoots of poplar in winter and its physicochemical activities against winter environmental conditions

XSP25, previously shown to be the most abundant hydrophilic protein in xylem sap of Populus nigra in winter, belongs to a secretory protein family in which the arrangement of basic and acidic amino acids is conserved between dicotyledonous and monocotyledonous species. Its gene expression was observed at the same level in roots and shoots under long-day conditions, but highly induced under short-day conditions and at low temperatures in roots, especially in endodermis and xylem parenchyma in the root hair region of Populus trichocarpa, and its protein level was high in dormant buds, but not in roots or branches. Addition of recombinant PtXSP25 protein mitigated the denaturation of lactate dehydrogenase by drying, but showed only a slight effect on that caused by freeze-thaw cycling. Recombinant PtXSP25 protein also showed ice recrystallization inhibition activity to reduce the size of ice crystals, but had no antifreezing activity. We suggest that PtXSP25 protein produced in shoots and/or in roots under short-day conditions and at non-freezing low temperatures followed by translocation via xylem sap to shoot apoplast may protect the integrity of the plasma membrane and cell wall functions from freezing and drying damage in winter environmental conditions.

Phosphorus recovery from freeze-microwave pretreated sludge supernatant by phosphate sedimentation

A novel pretreatment approach combined freeze with microwave was developed to promote the release of orthophosphate from excess sludge, and the phosphorus (P) was recovered from the produced supernatant by phosphate sedimentation. Batch tests examined the effects of freezing time, pH, and microwave time on the release of phosphate (PO₄^3--P) of the excess sludge during the freezing-microwave pretreatment. The release amount of PO₄^3--P reached 276 mg/L under the conditions of the freezing time of 23 h, microwave time of 5 min, and pH of 4. The optimal conditions for phosphate precipitation were pH of 9.5, the mole ratio of Mg/P of 1.8, and stirring speed of 200 rpm. The recovery efficiency of PO₄^3--P reached 97.42% after the reaction of 20 min and the precipitation of 50 min. The precipitated sediment mainly consisted of amorphous calcium phosphate and magnesium ammonium phosphate (MAP) which can be used as a substitute for phosphorus minerals.

Stabilisation and dewatering of primary sludge using ferrate(VI) pre-treatment followed by freeze-thaw in simulated drainage beds

This study evaluated the ability of potassium ferrate(VI) and freeze-thaw to stabilise and dewater primary sludge. Potassium ferrate(VI) additions of 0.5 and 5.0 g/L were used as a pre-treatment prior to freeze-thaw. Samples were frozen at -10, -20 and -30 °C, and were kept frozen for 1, 8 and 15 days. The samples were subsequently thawed at room temperature in a setup which allowed meltwater to be separated from the sludge cake via gravity drainage. The meltwater was characterised in terms of fecal coliform, soluble chemical oxygen demand (COD), soluble proteins, soluble carbohydrates, pH and turbidity. The sludge cake was characterised in terms of fecal coliform, total solids (TS) and volatile solids (VS). Freeze-thaw with gravity meltwater drainage reduced the sludge volume by up to 79%. After being frozen for only 1 day, the concentrations of fecal coliform in many of the primary sludge samples were reduced to <1000 MPN/g dry solids (DS), representing >3-log inactivation in some cases. However, pre-treatment of the primary sludge with ≤5.0 g/L potassium ferrate(VI) resulted in significant increases in soluble proteins, soluble carbohydrates, and sCOD, and reduced the effectiveness of stand-alone freeze-thaw. Follow-up experiments using higher doses ranging from 5.1 to 24.9 g/L of potassium ferrate(VI) demonstrated that >5-log inactivation of fecal coliform in raw primary sludge can be achieved within 15 min using 15 g/L of potassium ferrate(VI), and the resulting concentration of fecal coliform in the sludge was 1023 MPN/g DS. Pre-treatment with 22.0 g/L of potassium ferrate(VI), followed by freeze-thaw, with only 3 days frozen, reduced the concentration of fecal coliform to below the detection limit in the meltwater and the sludge cake. This demonstrates that potassium ferrate(VI) and freeze-thaw offers the flexibility to adjust the ferrate(VI) dose to meet treatment requirements for land application, and can be used as a stand-alone sludge treatment technology for primary sludge that achieves both treatment and dewatering.

Genetic parameter and breeding value estimation of donkeys' problem-focused coping styles

Donkeys are recognized therapy or leisure-riding animals. Anecdotal evidence has suggested that more reactive donkeys or those more easily engaging flight mechanisms tend to be easier to train compared to those displaying the natural donkey behaviour of fight. This context brings together the need to quantify such traits and to genetically select donkeys displaying a neutral reaction during training, because of its implication with handler/rider safety and trainability. We analysed the scores for coping style traits from 300 Andalusian donkeys from 2013 to 2015. Three scales were applied to describe donkeys' response to 12 stimuli. Genetic parameters were estimated using multivariate models with year, sex, husbandry system and stimulus as fixed effects and age as a linear and quadratic covariable. Heritabilities were moderate, 0.18 ± 0.020 to 0.21 ± 0.021. Phenotypic correlations between intensity and mood/emotion or response type were negative and moderate (-0.21 and -0.25, respectively). Genetic correlations between the same variables were negative and moderately high (-0.46 and -0.53, respectively). Phenotypic and genetic correlations between mood/emotion and response type were positive and high (0.92 and 0.95, respectively). Breeding values enable selection methods that could lead to endangered breed preservation and genetically selecting donkeys for the uses that they may be most suitable.

Cryopreservation at -75°C of Agaricus subrufescens on wheat grains with sucrose

Agaricus subrufescens is a basidiomycete which is studied because of its medicinal and gastronomic importance; however, less attention has been paid to its preservation. This study aimed to evaluate the effect of sucrose addition to substrate and cryotube on the viability of Agaricus subrufescens cryopreserved at −20 °C and at −75 °C for one and two years. Zero, 10% or 20% sucrose was added to potato dextrose agar or wheat grain. The mycelia were cryopreserved in the absence of cryoprotectant or with sucrose solutions at 15%, 30% or 45%. After one or two years at −75 °C or at −20 °C, mycelia were thawed and evaluated about viability, initial time of growth, colony diameter and genomic stability. Cryopreservation at −20 °C is not effective to keep mycelial viability of this fungus. Cryopreservation at −75 °C is effective when sucrose is used in substrates and/or cryotubes. Without sucrose, cryopreservation at −75 °C is effective only when wheat grains are used. Physiological characteristic as mycelial colony diameter is negatively affected when potato dextrose agar is used and unaffected when wheat grain is used after two-year cryopreservation at −75 °C. The fungus genome does not show alteration after two-year cryopreservation at −75 °C.

Cognitive Factors Affecting Freeze-like Behavior in Humans

Contemporary research on survival-related defensive behaviors has identified physiological markers of freeze/flight/fight. Our research focused on cognitive factors associated with freeze-like behavior in humans. Study 1 tested if an explicit decision to freeze is associated with the psychophysiological state of freezing. Heart rate deceleration occurred when participants chose to freeze. Study 2 varied the efficacy of freezing relative to other defense options and found "freeze" was responsive to variations in the perceived effectiveness of alternative actions. Study 3 tested if individual differences in motivational orientation affect preference for a "freeze" option when the efficacy of options is held constant. A trend in the predicted direction suggested that naturally occurring cognitions led loss-avoiders to select "freeze" more often than reward-seekers. In combination, our attention to the cognitive factors affecting freeze-like behavior in humans represents a preliminary step in addressing an important but neglected research area.

Experimental evaluation of freezing preparation for the macroscopic inspection in putrefied brain

PURPOSE

To evaluate the usefulness of freezing preparation for macroscopic investigation in advanced putrefied brain.

MATERIALS AND METHODS

After sealing in individual plastic bags, 10 pig heads were stored at 20°C for 5days allow postmortem change (putrefaction) to progress. After an observation period, they were divided into 2 groups to evaluate the usefulness of the freezing effect in macroscopic investigation. The process over the postmortem period and the freezing process were examined.

RESULTS

At day-5, the presence of air density was detected between the inner surface of the cranium and the brain parenchyma. Intra-cranial air accumulation presented on CT in all heads. In the control group, the brain parenchyma leaked out from the hole in the meninges, and the gray-white matter difference was clear in 3/72 (4.2%), moderate in 7/72 (9.7%), ambiguous in 17/72 (23.6%), and poor in 45/72 (62.5%). In the freezing group, the brain parenchyma presented homogeneous low density after more than 14h freezing. On opening the cranium, the entire brains were frozen, and the gray-white matter difference was clear in 33/72 (46.0%), moderate in 17/72 (24.0%), ambiguous in 15/72 (21.0%), and poor in 7/72 (10.0%). The freezing group afforded greater clarity in the gray-white matter inspection (p<0.05).

CONCLUSION

Freezing preparation was useful for the macroscopic investigation of putrefied brain compared with the ordinary autopsy.

Storage of Heparinised Canine Whole Blood for the Measurement of Glutathione Peroxidase Activity

Glutathione peroxidase activity is used as a biomarker of selenium status in dogs. Freshly collected blood samples are usually measured, due to the lack of knowledge on the effect of storing the samples. This study investigated if the analysis of glutathione peroxidase activity in whole blood collected from dogs was affected by storage of between 5 and 164 days. Results indicated that glutathione peroxidase activity was more variable in the freshly analysed samples compared to the stored samples. Although the mean differences between fresh and stored samples were not always equal to zero, this is thought to be caused by the variability of reagent preparation rather than by storage, as no consistent increase or decrease in glutathione peroxidase activity was found. Therefore, it can be concluded that heparinised dog blood samples can be successfully stored up to 164 days before analysis of glutathione peroxidase activity.

Effect of ethanol induced mild stress on post-thawed bull sperm quality

This study was performed to investigate the effect of sub-lethal exposure of bull semen to ethanol on the post-thaw spermatozoa quality. Semen samples (n=24, 6 ejaculates/bull) from 4 Holstein bulls were collected and pooled. Pooled samples were divided into 4 equal parts and each part was frozen after being diluted with Optidyl® extender containing 0 (O-E0), 0.03 (O-E3), 0.09 (O-E9) and 0.15 (O-E15) % (v/v) absolute ethanol. Sperm motility and velocity, plasma membrane integrity and functionality, mitochondrial activity, malondialdehyde concentration, and apoptosis status were evaluated after thawing. A higher percentage of total motility was observed in the O-E9 group as compared to the O-E0, O-E3 and O-E15 groups (p<0.05). Also, plasma membrane integrity was higher (p<0.05) in the O-E9 group compared to the O-E3, and O-E15 groups. However, the difference between the O-E9 and O-E0 groups was not significant (p>0.05). In terms of the proportion of sperm abnormality and plasma membrane functionality no differences (p>0.05) were observed between the groups. Our results revealed that malondialdehyde level was lower in ethanol treated (O-E3, O-E9 and O-E15) groups compared to the O-E0 group (p<0.05). Furthermore, the percentage of live spermatozoa with active mitochondria was higher in the O-E9 and O-E15 groups compared to the O-E0 and O-E3 groups (p<0.05). The O-E3 and O-E9 groups resulted in the highest and lowest percentage of apoptotic spermatozoa, respectively (p<0.05). The results of this study demonstrate that supplementation of semen extender with sub-lethal concentration of ethanol influences post-thawed bull sperm quality in a dose dependent manner.

Protective role of glutathione in buck semen cryopreservation

The aim of this study was to determine the effect of low levels of glutathione on post-thawed buck sperm quality. In this experiment, different concentrations of glutathione [0 (LG-0), 0.5 (LG-0.5), 1 (LG-1), 1.5 (LG-1.5), and 2 (LG-2) mM] were added in a soybean lecithin-based extender. A total of 16 ejaculates from four bucks were collected and pooled. Each pooled sample was divided into five equal parts and each part was diluted by one of the above mentioned groups. After freeze-thawing process, motility and velocity, plasma membrane integrity and functionality, and apoptosis features of spermatozoa were evaluated. The results of this experiment showed that total motility (50.75 ± 2.33), plasma membrane integrity (55.75 ± 3.01) and functionality (46.75 ± 2.79) were higher in LG-1 extender compared to other extenders (P<0.05). The percentage of live spermatozoa (53.23 ± 3.26) was higher in LG-1 extender compared to other extenders, with the exception of LG-1.5 extender (P<0.05). Also, the percentage of late apoptotic spermatozoa (21.33 ± 1.63) was lower in LG-1 extender compared to other extenders (P<0.05). In conclusion, our results showed that GL-1 extender resulted in higher post-thawed buck sperm quality compared to other extenders.