Journal of Comparative Physiology B-Biochemical Systems and Environmental Physiology最新文献

Caligus elongatus is a marine copepod ectoparasite on a wide variety of fish species. It has also been observed on fish farms cultivating Atlantic salmon and reports shows that this parasite can be a problem for the industry and for the fish's welfare. Freshwater is used as one of the non-medical treatment methods against the salmon louse (Lepeophtheirus salmonis). However, the efficacy of freshwater treatment against C. elongatus is still unknown. This study aims to fill this gap by examining the salinity tolerance limits of both adult and copepodid life stages of C. elongatus. Our findings reveal that detached adult C. elongatus exhibit low tolerance to reduced salinity, with mortality occurring within hours at salinities below 20 ppt. In contrast, copepodid stages demonstrated a slightly higher tolerance, surviving at salinities as low as 15 ppt for one day. Adult lice attached to a host quickly detached from the fish as soon as the salinity was lower than 20 ppt, suggesting that freshwater delousing might be effective in this species. To further understand the genetic basis of acclimation to reduced salinities, we performed RNA-sequencing to assemble the first transcriptome of this species and identify differentially expressed genes. Several genes regulated upon low-salinity transfer were identified. These include genes involved in proline metabolism, energy metabolism, and the transport of various ions and betaine, an osmolyte. The potential roles of these genes in salinity acclimation are discussed within an evolutionary context, providing valuable insights into the survival mechanisms of C. elongatus under low-salinity conditions.

The present study investigates the roles of melatonin (MEL) and its agonist ramelteon (RAM) on blood pressure regulation, nitric oxide (NO), and oxidative stress and plasma endothelin-1(ET-1) levels in continuous light exposure and pinealectomized conditions. This study includes two experiments. The first experiment involved control, continuous light emitting diode (LED) exposure, continuous LED + MEL administration, and continuous LED + RAM. The second experiment included control, pinealectomy, pinealectomy + MEL administration, pinealectomy + RAM administration, and pinealectomy + continuous LED exposure. The present results showed significant increase of systolic blood pressure (SBP) of continuous LED exposure group, pinealectomy, and pinealectomy with continuous LED exposure. On the contrary, MEL and RAM both decreased SBP. Additionally, the continuous LED exposure considerably increased malondialdehyde (MDA). However, MEL increased both plasma ET-1 slightly and ET-1 significantly but RAM dramatically increased ET-1. While, both of MEL and RAM decreased MDA. In the second experiment, while MDA dramatically increased after pinealectomy and pinealectomy with LED illumination, ET-1 and NO were only a little reduced. Melatonin elevated plasma ET-1 and NO significantly. While, MDA was greatly reduced by MEL but not by RAM. The results suggested that MEL and RAM could attenuate SBP mostly via increasing NO generation and oxidative stress reduction.

We developed and validated a surgical technique to measure central venous pressure (CVP) in Nile tilapia, and investigated the effects of an acute temperature decrease (from 30 vs. 24 °C) and changes in heart rate (f_H) using zatebradine hydrocholoride, which decreases intrinsic f_H, on this species' cardiac function. As predicted, f_H and cardiac output ( $\dot{Q}$ ) were ~ 40% lower in the acutely cooled fish, and both groups had very comparable (i.e., within 10%) values for stroke volume (V_S)_. The CVP of fish acutely exposed to 24 °C was consistently ~ 0.04 kPa higher than in those measured at 30 °C across all concentrations of zatebradine (i.e., CVP increased from 0.04 to 0.11 kPa vs. - 0.01-0.07 kPa for 24 vs. 30 °C tilapia, respectively, as f_H was reduced). However, this did not result in an increase in V_S due to a right-shifted relationship between CVP and V_S for the 24 °C fish. These data suggest that the V_S of tilapia is less sensitive to changes/increases in CVP when temperature is acutely lowered, and that regardless of increases in preload (CVP), $\dot{Q}$ is primarily modulated by f_H in this species.

The knowledge about the occurrence and biochemical characteristics of key digestive enzymes is crucial for an enhanced understanding of the dietary ecophysiology of the species. On the other hand, integrative studies on digestive physiology and on tissue content of glycogen, glucose, lipid and protein in groups of ecological and economic importance are currently limited. In this work, we determined the occurrence and biochemical characteristics in intestine of key digestive enzymes activities as indexes of the ability to digest different dietary substrates and of functional differentiation for digestion/absorption of nutrients along with the intestinal coefficient as index of dietary habit and digestion efficiency in adults of Odonthtestes argentinensis inhabiting Mar Chiquita Coastal Lagoon (Buenos Aires, Argentina). Furthermore, to identify storage sites, glycogen, triglycerides and protein content in different tissues were also analyzed. The presence and biochemical characteristics of amylase, maltase, sucrase, lipase, trypsin and aminopeptidase-N activity in intestine, as well as the tissue content of glycogen, triglycerides and protein suggests that adults of O.argentinensis exhibit an adequate digestive battery to potentially perform complete hydrolysis of various dietary substrates and capacity for storage and/or utilization of energy reserves. Our study provides novel insights into the digestive/metabolic traits in adults of the resident silverside O. argentinensis from Mar Chiquita Coastal Lagoon.

Larvae of Galleria mellonella are well known for their parasitisation of honeybees, so developing new methods of controlling the pest population is an important issue. The present research examined the immunotoxic effects of 2-octenoic acid against wax moth larvae. The last instar larvae were used for all experimental analyses. The tested fatty acid doses LD50 and LD100 (9.66 µg/mg and 11.72 µg/mg of body mass) were applied topically to insects under in vivo conditions and the hemolymph was collected after 24 and 48 h. To check the in vitro impact of the 2-octenoic acid, the examined fatty acid was given directly to the cultured hemocytes (to a final concentration: 0.33 and 0.16 µg/µl) and incubated for 24 and 48 h. Current research using fluorescence microscopy and spectrofluorimetric measurements indicates the death of immunocompetent cells via the apoptosis pathway. Moreover, it shows the activation of caspases and an increase in the level of reactive oxygen/nitrogen damage after both in vivo and in vitro treatment of 2-octenoic acid. This points to the impact of both cellular and humoral elements on the immunological response to the toxic compound. Hence, 2-octenoic acid seems to have significant potential as an insecticide while being safe for humans and the environment. Therefore, further research into its potential is warranted.

Ischemia-reperfusion (I-R) injury represents a predominant etiology of acute kidney injury (AKI), for which effective treatments remain unavailable. In contrast, hibernating mammals exhibit notable resistance to cell death induced by I-R injury. However, the impact of I-R injury on cellular senescence-an important factor in AKI-has not been extensively studied in these species. Comparative biology may offer novel therapeutic insights. Renal proximal tubular epithelial cells (RPTECs) from the native hibernator Syrian hamster or mouse RPTECs were subjected to anoxia-reoxygenation. Proteins involved in DNA damage response (DDR) and cellular senescence were assessed using western blotting, reactive oxygen species (ROS) levels and cell death were quantified colorimetrically, and IL-6 with ELISA. Anoxia-reoxygenation induced oxidative stress in both mouse and hamster RPTECs; however, cell death was observed exclusively in mouse cells. While anoxia-reoxygenation elicited a DDR and subsequent senescence in mouse RPTECs, such responses were not detected in hamster RPTECs. Thus, RPTECs from the Syrian hamster exhibited increased ROS production upon reoxygenation but did not show DDR or cellular senescence. Further research is required to elucidate the specific protective molecular mechanisms in hibernators, which could potentially lead to the development of novel therapeutic approaches for I-R injury in non-hibernating species, including humans.

The pirarucu is one of the very few obligate air-breathing fish, employing a gigantic, highly vascularized air-breathing organ (ABO). Traditionally, the ABO is thought to serve mainly for O₂ uptake (ṀO₂), with the gills providing the major route for excretion of CO₂ (ṀCO₂) and N-waste. However, under aquatic hypercapnia, a common occurrence in its natural environment, branchial ṀCO₂ to the water may become impaired. Under these conditions, does the ABO become an important route of ṀCO₂ excretion to the air? We have answered this question by measuring ṀCO₂ and ṀO₂ in both air and water phases, as well as the pattern of air-breathing, in pirarucu under aquatic normocapnia and hypercapnia (3% CO₂). Indeed, ṀCO₂ to the air phase via the ABO increased 2- to 3-fold during exposure to high water PCO₂, accounting for 59-71% of the total, with no change in the dominant contribution of the ABO to ṀO₂ (71-75% of the total). These adjustments were quickly reversed upon restoration of aquatic normocapnia. During aquatic hypercapnia, ṀCO₂ via the ABO became more effective over time, and the pattern of air-breathing changed, exhibiting increased frequency and decreased breath volume. Ammonia-N excretion (86-88% of total) dominated over urea-N excretion and tended to increase during exposure to aquatic hypercapnia. We conclude that the ability of the ABO to take on the dominant role in CO₂ excretion when required may have been an important driver in the original evolution of air-breathing, as well as in the functionality of the ABO in modern air-breathing fish.

Sleep deprivation (SD) can affect the adaptive thermogenesis in laboratory rodents, but the molecular mechanism and the crosstalk with other organs remain largely unknown. In order to investigate the effects and mechanisms of SD on thermoregulation and energy metabolism, here we measured the changes of body weight, body fat mass, body temperature, resting metabolic rate (RMR), and thermogenic gene expression in brown adipose tissue (BAT), white adipose tissue (WAT), skeleton muscle and liver in C57BL/6J mice during 7-day SD with rotating rod sleep deprivation device. Results showed that compared with the control group, the body weight and body fat mass of SD mice were decreased and RMR of SD mice increased. The gene expression of Ampk, Pgc1α and Ucp1 which related to thermogenesis in BAT and WAT were significantly increased, and the expression of Ampk, Serca1, Serca2 and Ucp3 which related to thermogenesis in skeletal muscle were significantly increased in SD mice. Taken together, these data demonstrated that 7-day SD enhanced the adaptive thermogenesis in mice by activating AMPK, including the upregulation of the AMPK - PGC1α - UCP1 pathway in BAT, and the AMPK - UCP3 and SLN - SERCA pathway in skeleton muscle. Our data provide the molecular evidence for SD-stimulated adaptive thermogenesis and energy metabolism in small mammals.

The optimisation of livestock production relies on efficient energy metabolism. This review focused on elaborate regulatory processes governed by non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). It explores the complex energy metabolism processes in livestock, elucidating the functions of ncRNAs in the expression of genes and pathways. miRNAs have been identified as significant regulators of glycolysis and glucose metabolism, whereas lncRNAs are known to affect adipogenesis and mitochondrial activity. Moreover, circRNAs have a substantial influence on the regulation of energy. In addition, this is not only enriching non-coding RNA-mediated energy control but also sheds light on possible applications. It is derived from its ability to condense complex molecular systems, thereby offering crucial insights to researchers. Through a comprehensive analysis of the intricate relationship between ncRNAs and energy metabolism, the information of this review provides a valuable framework for the implementation of focused interventions that hold the potential to significantly enhance the efficiency of livestock production.

Dietary fatty acids (FAs) are essential macronutrients affecting animal fitness, growth, and development. While the degree of saturation of FAs usually determines the level of absorption and allocation within the body, the utilization of dietary FAs across the life stages of individuals remains unknown. We used three different 13 C labeled FAs, with a different saturation level (linoleic acid (18:2), oleic acid (18:1), and palmitic acid (16:0)), to investigate the absorption and allocation of dietary FAs across the life stages of the Oriental hornet. Our results show that only larvae utilized all tested FAs as metabolic fuel, with palmitic acid being oxidized at the highest rate. Oleic and palmitic acids were predominantly incorporated into larval tissues, while oleic acid dominated pupal tissues. In contrast, linoleic and oleic acids were predominantly incorporated into adult tissues. These findings highlight a life stage-dependent shift in certain FAs utilization, with palmitic acid mostly utilized in early stages and linoleic acid in adulthood, while oleic acid remained consistently utilized across all life stages. This study emphasizes the importance of considering FA saturation and life stage dynamics in understanding FA utilization patterns.