Metal accumulation in juvenile and sub-adult loggerhead and green turtles in northern Cyprus.

Sea turtles are considered pollution bioindicators due to their tendency to accumulate high metal levels in their tissues during their long lifespans. In this context, we aimed to analyse the concentrations of 12 elements in liver, kidney, heart and muscle samples from green turtles (Chelonia mydas; n = 41) and loggerhead turtles (Caretta caretta; n = 14) found stranded in Northern Cyprus. The samples were collected between 2019 and 2021, stored in sterile Eppendorf tubes at -20 °C until metal analysis, and analysed with an inductively coupled plasma mass spectrometer. With this study, we contribute to the limited number of studies on metal accumulation in heart tissue and present the first data for Mg accumulation in the heart, liver, muscle and kidney tissues of both species. We found that metal accumulation levels differed among the two study species' tissues, with some elements in the same tissue (AlKidney, AsHeart, AsLiver, FeMuscle, FeKidney, FeHeart, MnHeart, PbHeart, ZnMuscle and ZnKidney) significantly differing between species. The observed variation likely resulted from their different feeding habits, which cause them to be exposed to different levels of metals. We also found significant associations among elements within tissues, as well as between the same element across different tissues in both species, which may indicate the differential accumulation of elements among organs due to physiological processes in turtle metabolism, bioaccumulation or excretion.

Skeletal description of Pelophylax caralitanus (Anura: Ranidae): Comparison with other ranids.

A description of the skeletal development of ranids is scarce despite being well known in the family Ranidae. Herein, the description of several species of two genera representing the family Ranidae from Turkey is studied wherein the larval and adult cranial skeletons of Pelophylax caralitanus are described and compared with that of the water frog (Pelophylax bedriagae) and mountain frog (Rana macrocnemis). The data are based on cleared and double-stained specimens of 20 Gosner developmental Stages (26-46). The first element to ossify in P. caralitanus is the parasphenoid (Stage 30), followed by the exoccipitals (Stage 34) and prootics (Stage 35). The metamorphic climax commences at Stage 42 during which several modifications to the chondrocranium will unfold. In addition, ranids demonstrate remarkable differences between the water (Pelophylax sp.) and mountain (Rana sp.) frog species: (a) the ventromedial bridge between the corpora of the suprarostral cartilage in the larval upper jaw, (b) the number of processes of the central corpus in the hyobranchial skeleton, and (c) the differences in the ossification time and sequence between Pelophylax sp. and Rana sp. A detailed description of the larval osteological features of P. caralitanus conforms to the current phylogenetic position and provides a model for comparison with other ranids.

Sex-related differences in aging rate are associated with sex chromosome system in amphibians.

Sex-related differences in mortality are widespread in the animal kingdom. Although studies have shown that sex determination systems might drive lifespan evolution, sex chromosome influence on aging rates have not been investigated so far, likely due to an apparent lack of demographic data from clades including both XY (with heterogametic males) and ZW (heterogametic females) systems. Taking advantage of a unique collection of capture-recapture datasets in amphibians, a vertebrate group where XY and ZW systems have repeatedly evolved over the past 200 million years, we examined whether sex heterogamy can predict sex differences in aging rates and lifespans. We showed that the strength and direction of sex differences in aging rates (and not lifespan) differ between XY and ZW systems. Sex-specific variation in aging rates was moderate within each system, but aging rates tended to be consistently higher in the heterogametic sex. This led to small but detectable effects of sex chromosome system on sex differences in aging rates in our models. Although preliminary, our results suggest that exposed recessive deleterious mutations on the X/Z chromosome (the "unguarded X/Z effect") or repeat-rich Y/W chromosome (the "toxic Y/W effect") could accelerate aging in the heterogametic sex in some vertebrate clades.

A biphasic navigational strategy in loggerhead sea turtles.

The homing journeys of nine loggerhead turtles translocated from their nesting beach to offshore release sites, were reconstructed through Argos and GPS telemetry while their water-related orientation was simultaneously recorded at high temporal resolution by multi-sensor data loggers featuring a three-axis magnetic sensor. All turtles managed to return to the nesting beach area, although with indirect routes encompassing an initial straight leg not precisely oriented towards home, and a successive homebound segment carried out along the coast. Logger data revealed that, after an initial period of disorientation, turtles were able to precisely maintain a consistent direction for several hours while moving in the open sea, even during night-time. Their water-related headings were in accordance with the orientation of the resulting route, showing little or no effect of current drift. This study reveals a biphasic homing strategy of displaced turtles involving an initial orientation weakly related to home and a successive shift to coastal navigation, which is in line with the modern conceptual framework of animal migratory navigation as deriving from sequential mechanisms acting at different spatial scales.

Investigation of the behavioral and neurochemical effects of monosodium glutamate on neonatal rats.

BACKGROUND/AIM: The objective of this study was to investigate and analyze the behavioral and neurochemical effects of monosodium glutamate (MSG) injections at various and subsequent dosages on male Wistar rats during the neonatal period. MATERIALS AND METHODS: In order to determine the behavioral and neurochemical effects of MSG, the experiment was implemented on neonatal male Wistar rats and the test was repeated for various MSG dosages. After completing the experiment, additionally, levels of dopamine, GABA, catecholamine (dopamine, noradrenaline, and adrenaline) and glutamate in the brain cells of the decapitated rats were also measured using the ELISA method. RESULTS: Considering the results of the behavioral test, when we compared the test values of the control group with the values of the MSG-injected groups we noted that there were significant differences in the statistical figures obtained. Additionally, we found that the statistical figures of some neurochemical parameters were also significantly different when we compared the values of the MSG group with the control values. CONCLUSION: MSG injection has a clear effect on the neurochemical parameters, learning memory, and locomotor activities of rats.

Some water chemistry parameters of breeding habitats of the Caucasian salamander, Mertensiella caucasica in the Western Lesser Caucasus.

Selection of breeding habitat plays a fundamental role in the reproductive success of urodeles and anurans. We studied the influence of water chemistry variables on the selection of a specific water resource as breeding habitat in Mertensiella caucasica. To determine the influence of water chemistry parameters on their habitat selection, we surveyed a total of 45 small river, streams and brooks in the Western Lesser Caucasus (northeastern Turkey and southwestern Georgia). The water samples taken from these localities were analyzed for 14 chemical variables and the results submitted to multiple logistic regression analysis in order to evaluate the influence of these parameters on the presence or absence of the species in the localities. Of these parameters, chloride concentration influenced the breeding habitat selection of Mertensiella caucasica significantly.

Sex ratio estimations of loggerhead sea turtle hatchlings by histological examination and nest temperatures at Fethiye beach, Turkey.

Hatchling sex ratios in the loggerhead turtle (Caretta caretta) were estimated by placing electronic temperature recorders in 21 nests at Fethiye beach during 2000-2002. Over the seasons, the mean temperature in the middle third of the incubation period ranged from 26.7 to 32.1 degrees C, and incubation periods ranged from 49 to 67 days. Based on the mean temperatures during the middle third of the incubation period, and on histologically sexed dead hatchlings, the sex ratios of hatchlings at Fethiye beach were roughly equal, i.e. 60-65% of the hatchlings were females. This contrasts with the highly female-skewed sex ratios in loggerhead turtles elsewhere; Fethiye has a relatively high proportion of male hatchlings. For endangered sea turtles, the knowledge of hatchling sex ratios at different beaches, coupled with appropriate conservation measures, can make an important contribution to their survival.