Morphological comparison of the ampullae of Lorenzini of three sympatric benthic rays

Calcium-Activated Big-Conductance (BK) Potassium Channels Traffic through Nuclear Envelopes into Kinocilia in Ray Electrosensory Cells

Electroreception through ampullae of Lorenzini in the little skate, Leucoraja erinacea, involves functional coupling between voltage-activated calcium channels (CaV1.3, cacna1d) and calcium-activated big-conductance potassium (BK) channels (BK, kcnma1). Whole-mount confocal microscopy was used to characterize the pleiotropic expression of BK and CaV1.3 in intact ampullae. BK and CaV1.3 are co-expressed in electrosensory cell plasma membranes, nuclear envelopes and kinocilia. Nuclear localization sequences (NLS) were predicted in BK and CaV1.3 by bioinformatic sequence analyses. The BK NLS is bipartite, occurs at an alternative splice site for the mammalian STREX exon and contains sequence targets for post-translational phosphorylation. Nuclear localization of skate BK channels was characterized in heterologously transfected HEK293 cells. Double-point mutations in the bipartite NLS (KR to AA or SVLS to AVLA) independently attenuated BK channel nuclear localization. These findings support the concept that BK partitioning between the electrosensory cell plasma membrane, nucleus and kinocilium may be regulated through a newly identified bipartite NLS.

Sixth sense in the deep-sea: the electrosensory system in ghost shark Chimaera monstrosa

Animals that continually live in deep sea habitats face unique challenges and require adaptive specializations solutions in order to locate and identify food, predators, and conspecifics. The Ampullae of Lorenzini are specialized electroreceptors used by chondrichthyans for important biological functions. Ampullary organs of the ghost shark Chimaera monstrosa, a deep-sea species commonly captured as by-catch in the bottom trawl fishery, are here described for the first time using macroscopic, ultrastructural and histological approaches. The number of ampullary pores in C. monstrosa is about 700, distributed into the whole cephalic section of C. monstrosa, and organized in12 pore clusters and they are arranged into different configurations and form a distinct morphological pattern for this species, showing some anatomical peculiarities never described before in others cartilaginous fishes and may constitute an evolutionary adaptation of this ancient chondrichthyan species to the extreme environmental conditions of its deep sea niche.

First report on metal and metalloid contamination of Ampullae of Lorenzini in sharks: A case study employing the Brazilian sharpnose shark Rhizoprionodon lalandii from Southeastern Brazil as an ecotoxicological model

Metal contamination has never been assessed in Ampullae of Lorenzini. This study employed Rhizoprionodon lalandii, as an ecotoxicological model to investigate potential metal accumulation in Ampullae of Lorenzini jelly. No differences between sexes were observed regarding jelly metal concentrations at Rio das Ostras (RJ) or Santos (SP). Statistically significant correlations were noted between total lengths (TL) and condition factors and several metals at both sampling sites, demonstrating the potential for Chondrichthyan sensory capacity disruption and possible effects on foraging success. Maternal metal transfer to Ampullae jelly was confirmed. Rhizoprionodon lalandii is thus, a good model to assess Ampullae of Lorenzini contamination, as this electrosensory organ seems to be highly vulnerable to metal contamination.

Analysis of Ultrasound Images of Superficial Organs Based on the Combination of Global Features and Local Features

Ultrasound imaging has become the preferred method for early detection of superficial organ lesions due to its non-invasive, economical, convenient, and radiation-free features. First, in the superficial organ ultrasound image analysis module based on local features, using Dense Sift as the local feature descriptor, the similarity sequence of the local features of the input image and the images in the sample library is calculated by the BOW algorithm and sorted in descending order of similarity. Secondly, using the wavelet transform’s local feature information representation capabilities in the time and frequency domains, the wavelet transform is performed on the small and identical feature information contained in the image to remove redundant information in each feature map to obtain a salient part of the image’s local features. Finally, through the analysis of elastic ultrasound images, a quantitative index that can be used to evaluate ultrasound images of superficial organs is proposed, which has higher accuracy and reliability than the current clinical methods for evaluating ultrasound images of superficial organs. By analyzing the features of superficial organ ultrasound images, it is proposed that the overall features of superficial organ ultrasound images are more conducive to distinguishing benign and malignant lesions than local features. Based on the initial localization of the lesion, the global features of the superficial organ ultrasound image were combined with the local features of the B-ultrasound image, and the method of combining global features with local features was used to classify and achieved good results.

Comparative morphology of the electrosensory system of the epaulette shark Hemiscyllium ocellatum and brown-banded bamboo shark Chiloscyllium punctatum

We compared the electrosensory system of two benthic elasmobranchs Hemiscyllium ocellatum and Chiloscyllium punctatum. The distribution of the ampullary pores on the head was similar for both species, with a higher density of pores anteriorly and a lower density posteriorly, although C. punctatum generally possessed larger pores. Ampullary canals of the mandibular cluster were quasi-sinusoidal in H. ocellatum, a shape previously found in benthic rays only, whereas ampullary canals in C. punctatum were of a linear morphology as reported for many shark and ray species previously. The ampullae proper were of the lobular type, as occurs in most galean sharks. Chiloscyllium punctatum had six sensory chambers compared with the five per ampulla in H. ocellatum, which were generally smaller than those of C. punctatum. The sensory epithelium comprised flattened receptor cells, compared with the usual pear-shaped receptor cells encountered in other elasmobranchs and their apically nucleated supportive cells did not protrude markedly into the ampullary lumen, unlike those in benthic rays.