Journal of experimental zoology. Part A, Ecological and integrative physiology最新文献

Different light colors have different effects on endogenous melatonin. The preference for light colors has been studied in various animal species, except hamsters. Additionally, no research has been done on how melatonin affects color preference. In this study, I investigated whether melatonin can influence Syrian hamsters' preferences for various light colors. Eighteen female Syrian hamsters were divided into a control group and a test group orally administered 0.01 mg melatonin daily for 30 days. On Day 31, I placed each hamster in the test box at four stages: dark mid-phase; beginning, middle, and end of day. The box had four areas with red, yellow, green, and blue lamps. In each stage, the hamsters' movements were recorded for 5 min. I tested the effects of color, stage, and melatonin treatment using a mixed model analysis. The preferences of both groups changed between the stages (p < 0.001) with the except stages 1 and 4 of the control group (p = 0.012); and stages 2 and 3 of the test group for the yellow color (p = 0.104). There was a significant difference between the test and the control groups in all stages and all colors (p < 0.001) except the green light color in stage 2 (p = 0.007). The results suggest that exogenous melatonin controls the preference for monochromatic light by an unknown mechanism. Circadian endogenous melatonin levels are also effective. Scientists must consider melatonin levels in studies evaluating responses to light.

Mesenchymal stem cells-derived exosomes (MSCs-EXs) applications have brought a key breakthrough in treating type 1 diabetes mellitus (T1DM) and its diabetic complications. However, various recent strategies aimed to construct prominent engineered EXs with greater precision and higher efficiency for diabetes syndrome were conducted. In this research, we seek to enhance the medicinal potentialities of MSCs-EXs on type 1 diabetic rats' hepatic complications, via loading with either selenium (Se) or nano selenium (NSe) particles. For consecutive 4-weeks, rats were divided into 8 groups as; control, EXs, EXs + Se, EXs + NSe, STZ-diabetic (D), D + EXs, D + EXs + Se, and D + EXs + NSe groups. The three diabetic-treated groups manifested a significant reduction in hepatic contents of oxidative stress (OS) (MDA, NO, and H₂O₂) inflammatory (IL-6, TNF-α, and TGF-β), and apoptotic (P53, BAX, caspase-3, and Bcl2) markers, with marked elevation in hepatic antioxidant levels (GSH, GPX, SOD, and CAT). Such results were supported by the marked diminish in serum total proteins, liver function enzymes (AST, ALT, and bilirubin), and both serum and liver lipid profile fractions. In addition, hepatic histological examination showed marked improvement in liver architecture of all treated diabetic rats' groups, compared to diabetic untreated rats. Significantly, diabetic rats with EXs loaded with NSe exhibited the most therapeutic superiority.

Elevated ultraviolet radiation (UVR) is postulated as one of multiple, interrelated environmental stressors driving amphibian population declines globally. However, key knowledge gaps remain in elucidating the link between elevated UVR and amphibian declines in a changing climate, including whether timing and irradiance of UVR exposure in early life dictates the onset of detrimental carryover effects post-metamorphosis. In this study, striped marsh frog larvae (Limnodynastes peronii) were exposed to UVR at one of two different irradiances for up to 7 days, either as hatchlings (Gosner stage 23) or as older larvae (Gosner stage 25−28). These animals were then reared to metamorphosis in the absence of UVR to examine independent and interactive carryover effects throughout development. Older larvae were more sensitive to UVR than hatchlings, with 53.1% and 15.6% mortality in larvae exposed to high and low irradiance respectively, compared with no mortality of hatchlings in either irradiance treatment. Irradiance and timing of UVR exposure had interactive effects on larval body length, causing stunted growth patterns and a lack of compensatory growth following UVR exposure, particularly in animals exposed to high irradiance UVR later in development. Timing of UVR exposure also determined the severity of carryover effects into metamorphosis, including delayed metamorphosis and the first published account (to our knowledge) of latent UVR-induced depigmentation in an amphibian. These findings highlight how acute changes to the larval UVR exposure regime can impact on amphibian health later in life, with implications for our understanding of the effects of climate change on UVR-related amphibian declines.

Pomacea canaliculata (Lamarck 1822), a freshwater gastropod indigenous to lower Del Plata Basin of Argentina, has become the most destructive and invasive rice pests in south China since its introduction in the 1980s. In Guangdong, the main production areas for double rice, most of P. canaliculata overwinter in paddy field ditches after late-rice harvesting in mid-November and diapause to temporarily to avoid the damaging effects of extreme low temperatures. This pest aroused from diapause and migrated to the paddy field after early-rice reviving in next late March. Overwintering and cold tolerance of natural P. canaliculata have a non-negligible impact on population dynamics and distribution in the following year. We tested the supercooling capability, levels of cryoprotectant synthesis, activity of antioxidant defense system (antioxidant enzymes and reduced glutathione), and degree of oxidative damage (concentration of malondialdehyde as an index of lipid peroxidation) monthly, using natural P. canaliculata samples with a size-gender structure (i.e., juveniles, female, and male adults) from experimental ponds during the period of mid-November to the following April. P. canaliculata survived the winter with a monthly death rate of 7%–16.5% in coldest January. The supercooling point (SCP) of overwintering P. canaliculata decreased initially before increasing subsequently with monthly changes in water temperature. P. canaliculata accumulated a high glycogen content before December, which depleted towards the end of January, while lipid content reached peak in January and depleted since February. Activity of antioxidant defense system of P. canaliculata exhibited significant monthly differences and showed relatively higher size heterogeneity than monthly variations. The results contribute to the knowledge of adaptability in overwintering P. canaliculata and help to understand the mechanism of the invasive success of this species.

Bivalve mollusks frequently experience salinity fluctuations that may drive oxidative stress (OS) in the organism. Here we investigated OS markers and histopathological changes in gills and hemolymph of Mediterranean mussels Mytilus galloprovincialis Lamarck, 1819 exposed to a wide range of salinities (6, 10, 14, 24, and 30 ppt). Mussels were captured at the shellfish farm with the salinity 18 ppt and then exposed to hypo- and hypersaline conditions in the laboratory. Indicators of redox balance in hemocytes (intracellular reactive oxygen species (ROS) levels, DNA damage) and gills (thiobarbituric acid reactive substances (TBARS), protein carbonyls (PC), activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) were measured. The effect of salinity stress on microstructure of gills has been evaluated as well. The results revealed induction of OS in tissues and cells of mussels for both experimental increase and decrease salinity modelings. Hemocytes showed higher sensitivity to osmotic stress compared to gills. In gills TBARS were stable in all experimental groups and PC increased only at salinity 6 ppt. The activity of SOD, CAT and GPx in gills decreased only in mussels acclimated to salinity 24 ppt and further salinisation up to 30 ppt was associated with the recovery of the activity of all enzymes. Major histopathological changes in gills upon salinity fluctuations included inflammatory reactions, circulatory alterations, regressive and progressive changes. Our findings clearly indicate that salinity fluctuations promote OS at cellular and tissue level and also affect microstructure of gills in mussels. The results provide new insights into the mechanisms of osmotic stress in bivalves.

The continuous requirement to substitute safe and affordable alternatives for helminth medications, as well as address the resistance of some used drug classes, introduced bioactive products derived from marine animals into the field of competition; however, almost all the previous research only focused on their impact on bacterial and protozoal infection. In the present work, we investigated the potential in vitro nematocidal effect of the aqueous extract of defense secretions for four species of marine mollusks: two cephalopods, namely the cuttlefish Sepia pharaonis and the common Octopus Octopus vulagris and two gastropods, the sea hare Aplysia argus and the sea slug Berthillina citrina, against the adult murine pinworm Syphacia obvelata. Data showed dose and time efficacy in all examined extracts. The sea slug's skin acid secretion has the highest impact, causing death in the cultivated worms, followed by the ink of the sea hare, the common octopus and the cuttlefish, where LC90 after 10 h of exposure were 250, 290, 316, and 391 µg/mL, respectively. Comparatively with the control and albendazole-treated groups, the skin acid secretion of the sea slug caused the highest levels of the antioxidant enzymes SOD, Cat and GSH-PX; however, albendazole prompted the highest level of GSH-PX enzyme in all experimental groups.

There is insufficient information about the migratory Eurasian teal, Anas crecca. The study provides the first anatomical description of lingual adaptations and their relationship with the species-specific feeding behavior of A. crecca collected near Egyptian Lake Nasser. Our investigation was applied with the help of gross, scanning electron microscopy (SEM), and morphometric analysis. The study focused on the feeding filtering apparatus that depends on eight lingual papillae. The spatula-shaped nail is adapted for food particle pecking, while the lingual combs, rostral border of the prominence, unique papillary crest, median groove, and papillary system aid in intra-oral transportation. The feeding apparatus is formed by the lateral and dorsal papillary systems. The lateral papillary system had conical papillae with numerous long filiform and hair-like filiform papillae to constitute the food filtration apparatus, while the dorsal papillary system had ridged-like and rod-like papillae in addition to the small papillae of the papillary crest and spinated border of the root to help in moving the food particles with water to the lateral sides of the prominence. The laryngeal region exhibited papillary (pre-glottic) and non-papillary (glottic) areas. The papillary area had two lateral papillary portions and a median smooth portion, while the non-papillary area had an ovoid laryngeal mound with a median glottic opening that was bordered by a papillary border. The papillary portion had three slightly oblique longitudinal papillary rows.