Endoscopic Imaging of Gonads,Sex Ratio and Temperature Dependent Sex Determination in Captive Bred Juvenile Burmese Star Tortoises Geochelone platynota

The possibility of temperature dependent sex determination makes it important to evaluate sex ratios in captive breeding programs of threatened tortoises. We assessed the sex ratio of juvenile Burmese Star Tortoises Geochelone platynota by direct observation of their gonads through an endoscope in the captive breeding program of the Behler Chelonian Center （BCC） in California. The gonads of small juvenile G. platynota are thin and elongate, and fixed to the dorsal part of body cavity, with ovaries appearing as transparent sheaths with some oocytes visible and testes appearing as small, transparent, thin, sausage-like structures with a net of fine blood vessels on the surface. With growth, ovaries expand and masses of pre-vitellogenic follicles appear on the surface. Testes are transparent in small juveniles and, with growth, turn pinkish-white and then yellowish, with tubuli structures visible through a thin, transparent theca containing a network of fine blood vessels. Egg incubation temperatures were not rigorously monitored, but a temperature of 28.9 ℃ produced a heavily male biased sex ratio whereas a temperature of 30 ℃ produced a balanced sex ratio. This suggests that G. platynota has temperature dependent sex determination.

The complex contribution of the astrocyte scar

It is tempting to assign positive or negative roles to components of neurotrauma pathology,in an effort to generate an ordered picture and design therapeutic strategies accordingly.However nature is seldom so obliging.This principle is elegantly illustrated in a recent publication from Anderson,

Delayed treatment of secondary degeneration following acute optic nerve transection using a combination of ion channel inhibitors

Studies have shown that a combined application of several ion channel inhibitors immediately after central nervous system injury can inhibit secondary degeneration. However, for clinical use, it is necessary to determine how long after injury the combined treatment of several ion channel inhibitors can be delayed and efficacy maintained. In this study, we delivered Ca^2＋ entry-inhibiting P2X7 receptor antagonist oxidized-ATP and AMPA receptor antagonist YM872 to the optic nerve injury site via an iPRECIO-@ pump immediately, 6 hours, 24 hours and 7 days after partial optic nerve transection surgery. In addition, all of the ion channel inhibitor treated rats were administered with calcium channel antagonist lomerizine hydrochloride. It is important to note that as a result of implantation of the particular pumps required for programmable delivery of therapeutics directly to the injury site, seromas occurred in a significant proportion of animals, indicating infection around the pumps in these animals. Improvements in visual function were observed only when treatment was delayed by 6 hours; phosphorylated Tau was reduced when treatment was delayed by 24 hours or 7 days. Improvements in structure of node/paranode of Ranvier and reductions in oxidative stress indicators were also only observed when treatment was delayed for 6 hours, 24 hours, or 7 days. Benefits of ion channel inhibitors were only observed with time-delayed treatment, suggesting that delayed therapy of Ca^2＋ ion channel inhibitors produces better neuroprotective effects on secondary degeneration, at least in the presence of seromas.

FGF-2 is required to prevent astrogliosis in the facial nucleus after facial nerve injury and mechanical stimulation of denervated vibrissal muscles

Recently,we have shown that manual stimulation of paralyzed vibrissal muscles after facial-facial anastomosis reduced the poly-innervation of neuromuscular junctions and restored vibrissal whisking.Using gene knock outs,we found a differential dependence of manual stimulation effects on growth factors.Thus,insulin-like growth factor-1 and brain-derived neurotrophic factor are required to underpin manual stimulation-mediated improvements,whereas FGF-2 is not.The lack of dependence on FGF-2 in mediating these peripheral effects prompted us to look centrally,i.e.within the facial nucleus where increased astrogliosis after facial-facial anastomosis follows ＂synaptic stripping＂.We measured the intensity of Cy3-fluorescence after immunostaining for glial fibrillary acidic protein（GFAP） as an indirect indicator of synaptic coverage of axotomized neurons in the facial nucleus of mice lacking FGF-2（FGF-2^（-/-） mice）.There was no difference in GFAP-Cy3-fluorescence（pixel number,gray value range17-103） between intact wildtype mice（2.12± 0.37×10~7） and their intact FGF-2^（-/-） counterparts（2.12±0.27×10~7） nor after facial-facial anastomosis ＋handling（wildtype：4.06±0.32×10~7;FGF-2^（-/-）：4.39±0.17×10~7）.However,after facial-facial anastomosis,GFAP-Cy3-fluorescence remained elevated in FGF-2^（-/-）-animals（4.54±0.12×10~7）,whereas manual otimulation reduced the intensity of GFAP-immunofluorescence in wild type mice to values that were not significantly different from intact mice（2.63±0.39×10）.We conclude that FGF-2 is not required to underpin the beneficial effects of manual stimulation at the neuro-muscular junction,but it is required to minimize astrogliosis in the brainstem and,by implication,restore synaptic coverage of recovering facial motoneurons.

Optimising repetitive transcranial magnetic stimulation for neural circuit repair following traumatic brain injury

While it is well-known that neuronal activity promotes plasticity and connectivity, the success of activity-based neural rehabilitation programs remains extremely limited in human clinical experience because they cannot adequately control neuronal excitability and activity within the injured brain in order to induce repair. However, it is possible to non-invasively modulate brain plasticity using brain stimu- lation techniques such as repetitive transcranial （rTMS） and transcranial direct current stimulation （tDCS） techniques, which show promise for repairing injured neural circuits （Henrich-Noack et al., 2013; Lefaucher et al., 2014）. Yet we are far from having full control of these techniques to repair the brain following neurotrauma and need more fundamen- tal research （Ellaway et al., 2014; Lefaucher et al., 2014）. In this perspective we discuss the mechanisms by which rTMS may facilitate neurorehabilitation and propose experimental techniques with which magnetic stimulation may be investi- gated in order to optimise its treatment potential.

Strategies to limit dysmyelination during secondary degeneration following neurotrauma

Following trauma to the central nervous system （CNS）, cells in the lesion site die rapidly. In addition, neurons and glia be- yond the initial lesion are vulnerable. These cells can undergo delayed death due to metabolic events that follow the initial trauma, via mechanisms thought to he triggered by gluta- mate-induced excitotoxicity and Ca2＋ overload, leading to mitochondrial dysfunction, associated with increased oxida- tive stress （Camello-Almaraz et al., 2006; Peng and Jou, 2010）. The resultant death of areas of grey and white matter adjacent to the lesion site is termed secondary degeneration, and is a feature of brain and spinal cord injury （Park et al., 2004; Gi- aume et al., 2007）. Secondary degeneration contributes sub- stantially to functional loss following neurotrauma （Profyris et al., 2004; Farkas and Povlishock, 2007） and rescuing this intact, but vulnerable, tissue is considered critical to mini- mising adverse sequelae and improving long term functional outcomes after CNS trauma （Fehlings et al., 2012）. However, our understanding of many of the metabolic events thought to contribute to secondary degeneration is based largely on in vitro studies （Khodorov, 2004; Tretter et al., 2007; Peng and Jou, 2010） and there is a need to confirm the relevance of these mechanisms in vivo, as well as their structural and func- tional consequences.

The sensory world of fish and fisheries: Impact of human activities–An international conference to evaluate the effects of environmental changes on the sensory world of fish/aquatic animals and fisheries

This special issue of Integrative Zoology(the official journal of the International Society of Zoological Sciences and the Institute of Zoology,Chinese Academy of Sciences)is dedicated to the sensory world of fish and fisheries and the impacts of human activities.The papers in this issue are the outcome of an international conference that was held at the Institute for Marine Biosystem and Neurosciences,College of Fisheries and Life Science,Shanghai Ocean University,Shanghai,China from 29 October to 1 November 2012.The conference was generously sponsored by The Shanghai Ocean University,The University of Maryland and The University of Western Australia.

Developmental transcription factors in age-related CNS disease: a phoenix rising from the ashes?

Few would doubt that understanding the developmental landscape from which a mature neuron is derived is essential to understand its biology.The temporal and spatial position of a cell from the very earliest stages of development predicts the unique combinations of growth factors it will subsequently be exposed to.

Modes of genetic adaptations underlying functional innovations in the rumen

The rumen is the hallmark organ of ruminants and hosts a diverse ecosystem of microorganisms that facilitates efficient digestion of plant fibers.We analyzed 897 transcriptomes from three Cetartiodactyla lineages:ruminants,camels and cetaceans,as well as data from ruminant comparative genomics and functional assays to explore the genetic basis of rumen functional innovations.We identified genes with relatively high expression in the rumen,of which many appeared to be recruited from other tissues.These genes show functional enrichment in ketone body metabolism,regulation of microbial community,and epithelium absorption,which are the most prominent biological processes involved in rumen innovations.Several modes of genetic change underlying rumen functional innovations were uncovered,including coding mutations,genes newly evolved,and changes of regulatory elements.We validated that the key ketogenesis rate-limiting gene(HMGCS2)with five ruminant-specific mutations was under positive selection and exhibits higher synthesis activity than those of other mammals.Two newly evolved genes(LYZ1 and DEFB1)are resistant to Gram-positive bacteria and thereby may regulate microbial community equilibrium.Furthermore,we confirmed that the changes of regulatory elements accounted for the majority of rumen gene recruitment.These results greatly improve our understanding of rumen evolution and organ evo-devo in general.

Vision and photoentrainment in fishes: The effects of natural and anthropogenic perturbation

Vision and photoentrainment in fishes are vital for feeding,avoiding predation,spatial orientation,navigation,social communication and the synchronization of many homeostatic functions such as activity patterns and sleep.The camera-like(image-forming)eyes of fishes are optimized to provide a clear view of their preferred ecological niche,while non-visual photoreceptors provide irradiance detection that mediates circadian photoentrainment,an endogenous time-keeping mechanism(biological clock)to respond to predictable changes in environmental conditions.Fish and fisheries are under pressure from both natural and anthropogenic perturbation,which in many cases alters the intensity and spectral composition of the light environment on which they depend for their survival.This review examines the effects of a changing light environment and turbidity on the health of fishes within a developmental and ecological context.Understanding the sensory environment of fishes is vital to predicting their responses and,ultimately,their resilience to environmental change and the potential for maintaining sustainable levels of biodiversity.

Sharks senses and shark repellents

Despite over 70 years of research on shark repellents,few practical and reliable solutions to prevent shark attacks on humans or reduce shark bycatch and depredation in commercial fisheries have been developed.In large part,this deficiency stems from a lack of fundamental knowledge of the sensory cues that drive predatory behavior in sharks.However,the widespread use of shark repellents is also hampered by the physical constraints and technical or logistical difficulties of deploying substances or devices in an open-water marine environment to prevent an unpredictable interaction with a complex animal.Here,we summarize the key attributes of the various sensory systems of sharks and highlight residual knowledge gaps that are relevant to the development of effective shark repellents.We also review the most recent advances in shark repellent technology within the broader historical context of research on shark repellents and shark sensory systems.We conclude with suggestions for future research that may enhance the efficacy of shark repellent devices,in particular,the continued need for basic research on shark sensory biology and the use of a multi-sensory approach when developing or deploying shark repellent technology.