Effect of Salinity on the Survival, Ions and Urea Modulation in Red-eared Slider(Trachemys scripta elegans)

To understand the tolerance to salinity and osmoregulation of the introduced Trachemys scripta elegans, the salinity stress of four groups （salinity 5‰, 15‰, 25‰ and control group） were conducted. Inorganic ions, osmotic pressure, glucose and aldosterone of blood and urine in T. s. elegans （BW： 125.60 ±19.84 g） were analyzed at 30 d, 60 d and 90 d stress. The results showed that： 1） inorganic ions concentration of blood and urine increased with ambient salinity, which indicated that high influx of ions was combined with higher outflow when exposed to saline water in T. s. elegans. However, blood aldosterone decreased with increasing salinity, which indicated that an increased sodium intake resulting in a diminished aldosterone production. However, with elapsed time, inorganic ions in urine decreased, which indicated that inorganic ions in blood would be accumulated, and Na^＋ and Cl^- in the plasma inevitably build up to harmful levels, at last death was happening when T. s. elegans was exposed to salinity 25 during 90 d salinity stress; 2） blood osmotic pressure increased as ambient salinity increased, it would reach 400 mOsm/kg in the group of salinity 25, which was about 1.5 fold of the control group. Higher blood osmotic pressure was due to both higher blood ions and urea concentrations. There may be another mechanism to avoid an excess of NaCl together with an important loss of water using one of the end-products of nitrogen metabolism; 3） blood glucose in each group except the group of salinity 5 decreased with time elapsed and with salinity increased. Therefore, we can conclude that T. s. elegans is an osmoregulator that limits the entry of Na^＋ and Cl^-, but can also tolerate certain degrees of increases in plasma Na^＋ and Cl^-. When ambient salinity was lower than 15‰, T. s. elegans can increase blood osmotic pressure by balancing the entry of NaCl with the secretion of aldosterone decreased, and by accumulating blood urea for osmoregulation effectors, and survive for at least three months. These results could provide theoretical basis for salinity tolerance and the invasion on physiological mechanism for T. s. elegans.

Single-cell transcriptomic landscape of peripheral blood cells provides insights into adaptation of red-eared sliders(Trachemys scripta elegans)

Red-eared sliders(Trachemys scripta elegans),as one of the 100 most threatening aliens,have stronger immunity than the native species in response to environmental stress.Blood cells are an important component of immunity in the body.However,the blood cell researches of turtle are still in the traditional blood cell classification and morphological structure observation.Furthermore,turtle granulocytes cannot be accurately identified using traditional methods.Single-cell RNA sequencing techniques have been successfully implemented to study cells based on the mRNA expression patterns of each cell.The present study profiled the transcriptomes of peripheral blood cells in red-eared sliders to construct a single-cell transcriptional landscape of the different cell types and explored environmental adaptation mechanism from the perspective of hematology.All 14 transcriptionally distinct clusters(platelets,erythrocytes1,erythrocytes2,CSF1R monocytes,POF1B monocytes,neutrophils,GATA2high basophils,GATA2low basophils,CD4 T cells,CD7 T cells,B cells,ACKR4 cells,serotriflin cells,and ficolin cells)were identified in the peripheral blood cells of the red-eared sliders.In particular,a subtype of erythrocytes(erythrocytes1)that expressed immune signals was identified.Peripheral blood cells were grouped into three lineages:platelet,erythroid/lymphoid,and myeloid cell lineages.Furthermore,based on differentiation trajectory and up-regulated gene expression,ACKR4 cells were newly identified as lymphocytes,and serotriflin and ficolin cells as granulocytes.The single-cell transcriptional atlas of the peripheral blood cells in red-eared sliders provided in the present study will offer a comprehensive transcriptome reference for the exploration of physiological and pathological hematology in this species.

Interspecific Differences in Diet between Introduced Red-eared Sliders and Native Turtles in China

Although the alien Red-eared slider （Trachemys scripta elegans） is generally argued as an invasive species that competes with native turtles, the field evidence on its diet is controversial. Field studies conducted at the Gutian Nature Reserve of Guangdong and along the Wanquan River in Hainan, China show that T. s. elegans is an opportunitic omnivore, consuming a wide variety of food items. Consumption varies throughout its range; more plant material is consumed in Guangdong, compared to a more carnivorous diet in Hainan; and juveniles are also found to have a more carnivorous diet than adults. This implies a high adaptability to new environment. Sympatrie native Mauremys sinensis shows a more herbivorous diet and a narrower niche breadth （0.0260） in Hainan, plus a low niche overlap （0.3048） with T. s. elegans, providing a potential empty niche for the invasive T. s. elegans. Red-eared slider is also known to consume large quantities of native prey species to disrupt the ecological balance. It is imperative to understand the invasive nature of this species and the mechanisms by which it affects native ecology.

Effects of Pesticide Exposure on Embryonic Development and Hatchling Traits of Turtles

Deltamethrin is a widespread environmental hormone with endocrine-disrupting properties, but its effect on embryonic development of reptiles is largely unexplored. We investigated the effects of deltamethrin on embryonic development and offspring traits in two turtle species, one with parchment-shelled eggs and the other with rigidshelled eggs. Deltamethrin exposure during egg incubation did not affect hatching success and hatchling body size in either species. However, embryonic exposure to deltamethrin resulted in reduced hatchling locomotor performance in the red-eared slider turtle（Trachemys scripta） with parchment-shelled eggs, but not in the Chinese three-keeled pond turtle（Chinemys reevesii） with rigid-shelled eggs. These results suggest that parchment-shelled eggs are likely more vulnerable to deltamethrin than rigid-shelled eggs.

Remote Navigation of Turtle by Controlling Instinct Behavior via Human Brain-computer Interface

Brain-Computer Interface （BCI） techniques have advanced to a level where it is now eliminating the need lor hand-based activation. This paper presents a novel attempt to remotely control an animal＇s behavior by human BCI using a hybrid of Event Related Desynchronization （ERD） and Steady-State Visually Evoked Potential （SSVEP） BCI protocols. The turtle was chosen as the target animal, and we developed a head-mounted display, wireless communication, and a specially designed stimulation device for the turtle. These devices could evoke the turtle＇s instinctive escape behavior to guide its moving path, and turtles were remotely controlled in both indoor and outdoor environments. The system architecture and design were presented. To demon- strate the feasibility of the system, experimental tests were performed under various conditions. Our system could act as a framework for future human-animal interaction systems.

Parasitic Robot System for Waypoint Navigation of Turtle

In research on small mobile robots and biomimetic robots, locomotion ability remains a major issue despite many advances in technology. However, evolution has led to there being many real animals capable of exceUent locomotion. This paper presents a ＂parasitic robot system＂ whereby locomotion abilities of an animal are applied to a robot task. We chose a turtle as our first host animal and designed a parasitic robot that can perform ＂operant conditioning＂. The parasitic robot, which is attached to the turtle, can induce object-tracking behavior of the turtle toward a Light Emitting Diode （LED） and positively reinforce the behavior through repeated stimulus-response interaction. After training sessions over five weeks, the robot could successfully control the direction of movement of the trained turtles in the waypoint navigation task. This hybrid animal-robot interaction system could provide an alternative solution to some of the limitations of conventional mobile robot systems in various fields, and could also act as a useful interaction system for the behavioral sciences.