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

Environmental temperatures directly affect physiological rates in ectotherms by constraining the possible body temperatures they can achieve, with physiological processes slowing as temperatures decrease and accelerating as temperatures increase. As environmental constraints increase, as they do northward along the latitudinal thermal gradient, organisms must adapt to compensate for the slower physiological processes or decreased opportunity time. Evolving faster general metabolic rates is one adaptive response posited by the metabolic cold adaptation (MCA) hypothesis. Here we test the MCA hypothesis by examining metabolism of prairie lizard populations across the latitudinal thermal gradient. Our results show that populations from cooler environments have higher standard metabolic rates (SMRs), but these are explained by associated larger body sizes. However, metabolic rates of fed, postprandial individuals (MR_Fed) and metabolic energy allocated to digestion (MR_Δ) were highest in the population from the coldest environment after accounting for the effect of body size. Our results suggest cold-adapted populations compensate for lower temperatures and shorter activity periods by increasing metabolic rates associated with physiological processes and thus support the MCA hypothesis. When examining energy expenditure, metabolic rates of individuals in a postprandial state (MR_Fed) may be more ecologically relevant than those in a postabsorptive state (SMR) and give a better picture of energy use in ectotherm populations.

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.

Diving beetles (Coleoptera: Dytiscidae) are general predators that feed primarily on mosquito larvae and can control their populations, but the evidence for such an assumption remains weak. Rhantus elevatus is an important predator of this group distributed in Egypt with both larval and adult stages preying on immature mosquito. For determine predator effectiveness, it is requisite to identify the functional response (a = rate of attack and T_h= time of handling) and searching efficacy (a_t= area of discovery and m = mutual interference) as both correlate with biocontrol efficacy. This study assessed the density-dependent mortality of Culex pipiens larvae by eliciting functional responses of third-instar and adult predators at prey density ranging from 100 to 500 larvae per arena. By contrast, a searching efficacy for the same predator stages was examined at densities ranging from one to five predators per 500 prey. Predation rates of third-instar and adult of R. elevatus were fitted by a model of Type II response with coefficients were: third-instar (a = 0.208 h^-1 and T_h = 2413 h) and adult (a = 0.1191 h^-1 and T_h = 3723 h). The maximum number of mosquitoes which can be devoured by an individual larva and adult of R. elevatus within 24 h was 99.46 and 64.46 prey, respectively. The area of discovery for the larval stage declined more steeply than the adult stage of the predator as their density increased from one to five individuals, indicating more interference estimated for the larval stage. Considering these characteristics, larvae would seem to be the most effective stage against low mosquito populations due to low predation risk compared to that generated at high predator densities in the same arena from intra-specific interference. Eventually, we suggested a ratio of 1:100 (predator per prey) must be considered in biocontrol plans for mosquitoes.

Crayfish are emerging as model organisms for various disciplines. Moreover, decapod crustaceans also exhibit pain-like reactions and heightened anxiety when exposed to harmful stimuli, leading to short-term or persistent behavioral shifts. Awareness of decapod crustacean sentience and thus, suffering calls for refinement of current laboratory protocols. This study aims to enhance the standard methodology for injecting substances into crayfish by minimizing stress-inducing manipulation. We examined the impacts of various administration routes on the persistence of injected chemicals in marbled crayfish, its excretion, and animal survival. Fluorescein dye was used as a visual marker. It was administered via three alternative injection routes-intracoelomic (IC), intrapericardial administration through areola (IP-A), and intrapericardial administration through arthrodial membrane (IP-AM). Continuous video observations were made for a 4-h period under UV light, followed by intermittent observations at 12-h intervals over 48 h. The highest mortality (20%) was observed in IP-A administration. The IP-A method also provided the fastest systemic distribution of the dye in the body. Results indicated visibly higher urination frequency in IP-AM compared to IP-A. IC mirrored IP-AM outcomes without any observed mortality. We conclude that IC administration proved superior to intrapericardial methods, offering the least harmful but effective approach for crayfish injections.

Assessment of the clock genes, Period (Per) 1, Per2, Per3, and Cryptochrome (Cry) 2, Cry3, and Cry4, can help better understand eel spawning ecology. In this study, the circadian rhythm and moonlight effects of these clock genes in the eel retina and hypothalamus were analyzed. We examined clock gene expression patterns under 12 h light:12 h darkness (12L12D), constant darkness (DD), and constant light (LL) conditions; under short photoperiod (SP; 9L15D) and long photoperiod (LP; 15L9D), and during the new moon (NM) and full moon in male eels. Per2 expression increased after sunrise, Cry2, and Cry4 expression increased around sunset, and Per1, Per3, and Cry3 expression increased before sunrise. Under SP conditions, oscillations of retinal Per3 and Cry4, which did not occur under LP conditions, were generated. In addition, retinal Cry4 oscillation was generated under NM conditions. These results suggest that the retina of the eel may play an important role in regulating circadian rhythm, and migration is initiated by the synchronization of clock genes by moonlight, suggesting that photic signals are closely related to the migratory activity of the eel.

Harsh early environmental conditions can exert delayed, long-lasting effects on phenotypes, including reproductive traits such as sexual signals. Indeed, adverse early conditions can accelerate development, increasing oxidative stress that may, in turn, impact adult sexual signals. Among signals, colorations produced by red ketocarotenoids seem to depend on mitochondrial functioning. Hence, they could reveal individual cell respiration efficiency. It has been hypothesized that these traits are unfalsifiable "index" signals of condition due to their deep connection to individual metabolism. Since mitochondrial dysfunction is frequently linked to aging, red ketocarotenoid-based ornaments could also be good signals of a critical fitness component: longevity. We tested this red color per longevity correlation in captive zebra finches. In addition, we experimentally decreased the synthesis of glutathione (a critical intracellular antioxidant) during the first days of the birds' life to resemble harsh early environmental conditions (e.g., undernutrition). Longevity was recorded until the death of the last bird (almost 9 years). Males, but not females, exhibiting a redder bill in early adulthood lived longer than males with paler bills, which agrees with some precedent studies. However, such bill redness-longevity connection was absent among males with inhibited glutathione synthesis. These findings may suggest that environmental factors can alter the reliability of red ketocarotenoid-based sexual signals, making them less unfalsifiable than believed.

Expression of vibrant plumage color plays important communication roles in many avian clades, ranging from penguins to passerines, but comparatively less is known about color signals in parrots (order Psittaciformes). We measured variation in coloration from three plumage patches (red face, blue rump, red tail) in an introduced population of rosy-faced lovebirds (Agapornis roseicollis) in Phoenix, Arizona, USA and examined color differences between the sexes and ages as well as relationships with several indices of quality, including disease presence/absence (infection with beak and feather disease, Circovirus parrot, and a polyomavirus, Gammapolyomavirus avis), nutritional state (e.g., blood glucose and ketone levels), and habitat type from which birds were captured. We found that different plumage colors were linked to different quality indices: (a) adults had redder faces than juveniles, and birds with brighter faces had lower glucose levels and were less likely to have polyomavirus; (b) males had bluer rumps than females; and (c) birds caught farther from the city had redder and darker tail feathers than those caught closer to the urban center. Our findings reveal diverse information underlying variation in the expression of these disparate, ornate feather traits in an introduced parrot species, and suggest that these condition-dependent and/or sexually dichromatic features may serve important intraspecific signaling roles (i.e., mediating rival competitions or mate choices).

Treatment with mesenchymal stem cells (MSCs) is a new promising therapeutic approach with substantial very auspicious potential. They have been shown to protect various played a role in protecting organs from damage. This current study aims to evaluate the impact of the treatment of olive leaf extract (OLE), bone marrow-derived (BM-MSCs), and their combination on hepatotoxicity in pregnant rats with diabetes.

Methods: Animals were divided into five groups (10 pregnant rats each) as follows: control, GDM group, and OLE group (rats received streptozotocin (STZ) at a dose of 35 mg/kg body weight). GD + OLE set (pregnant rats were administered OLE at a dose of 200 mg extract/kg of body weight). GD + MSCs group (pregnant rats treated with MSCs). GD + OLE + MSCs group (pregnant rats were treated with both MSCs and OLE).

Results: STZ induced significant changes in liver parameters, lipid profile, and oxidative stress. Treatment with OLE, BM-MSCs, and their combination significantly ameliorated STZ-induced liver damage and oxidative stress. STZ resulted in a significant change in liver parameters, lipid profile, and oxidative stress. OLE, BM-MSC, and combination have significantly improved STZ-induced deterioration in liver and improved oxidative stress.

Conclusions: The findings demonstrate that OLE and BM-MSCs have beneficial effects in mitigating diabetes-related liver alterations. These outcomes showed that OLE and BM-MSC have beneficial effects in alleviating diabetes-related alterations in the liver.