Living on the Edge: Settlement Patterns by the Symbiotic Barnacle \u3cem\u3eXenobalanus globicipitis\u3c/em\u3e on Small Cetaceans

The highly specialized coronulid barnacle Xenobalanus globicipitis attaches exclusively on cetaceans worldwide, but little is known about the factors that drive the microhabitat patterns on its hosts. We investigate this issue based on data on occurrence, abundance, distribution, orientation, and size of X. globicipitis collected from 242 striped dolphins (Stenella coeruleoalba) that were stranded along the Mediterranean coast of Spain. Barnacles exclusively infested the fins, particularly along the trailing edge. Occurrence, abundance, and density of X. globicipitis were significantly higher, and barnacles were significantly larger, on the caudal fin than on the flippers and dorsal fin. Barnacles were found more frequently and in greater numbers on the dorsal rather than ventral side of the caudal fin and on the central third of dorsal and ventral fluke surfaces. Nearly all examined individuals attached with their cirral fan oriented opposite to the fluke edge. We suggest that X. globicipitis may chemically recognize dolphins as a substratum, but fins, particularly the flukes, are passively selected because of creation of vortices that increase contact of cyprids with skin and early survival of these larvae at the corresponding sites. Cyprids could actively select the trailing edge and orient with the cirri facing the main direction of flow. Attachment on the dorsal side of the flukes is likely associated with asymmetrical oscillation of the caudal fin, and the main presence on the central segment of the flukes could be related to suitable water flow conditions generated by fluke performance for both settlement and nutrient filtration

Niche partitioning amongst northwestern Mediterranean cetaceans using stable isotopes

Ten species of cetaceans coexist in the Mediterranean Sea, one of the richest seas in biodiversity and endemisms worldwide. The conservation status of Mediterranean cetaceans has been a concern for many years, particularly due to increasing anthropogenic threats such as global warming and overfishing. We established the stable isotopic niches of carbon, nitrogen, and sulphur for five species of cetaceans inhabiting the northwestern Mediterranean Sea to elucidate the mechanisms of coexistence. The fin whale exploited epipelagic habitats with a low trophic level; the bottlenose dolphin was mostly neritic and had a high trophic level; the Risso's dolphin was oceanic and fed bathypelagically and at a high trophic level; finally, the common and striped dolphins displayed epipelagic distributions and similarly intermediate trophic levels. The isotopic niches of all species were exclusive except the common and striped dolphins, whose niches overlapped by 25%. These results suggest that the majority of species avoid competitive exclusion by trophic or spatial segregation with the exception of striped and common dolphins, in which interspecific competition is apparent. It is suggested that this competition brought the striped dolphin to displace the common dolphin from part of its distribution range, restricting it to the southern fringe of the western Mediterranean and, particularly, to the Alboran Sea. In this area, coexistence of the two species would be permitted by some degree of spatial segregation between them and a remarkably high productivity, all which mitigate competition

The orosomucoid 1 protein (α1 acid glycoprotein) is overexpressed in odontogenic myxoma

Odontogenic myxoma (OM) is a benign, but locally invasive, neoplasm occurring in the jaws. However, the molecules implicated in its development are unknown. OM as well as Dental Follicle (DF), an odontogenic tissue surrounding the enamel organ, is derived from ectomesenchymal/mesencyhmal elements. To identify some protein that could participate in the development of this neoplasm, total proteins from OM were separated by two-dimensional electrophoresis and the profiles were compared with those obtained from DF, used as a control

Consumption of pelagic tunicates by cetaceans calves in the Mediterranean Sea

Gelatinous zooplankton, including jellyfish, ctenophores and pelagic tunicates, constitutes fragile marine animals that live in the water column, and represent an important resource for marine food webs through their seasonal pulses. Although there is scarce evidence on the occurrence of gelatinous zooplankton in stomach contents of apex, endothermic predators such as cetaceans, the ecological significance of such observations requires consideration. In this study, we report on the occurrence of pelagic tunicates in the stomach of three individual calves of two cetacean species from the western Mediterranean, and collate all previous reports of gelatinous zooplankton in cetacean diets. We then briefly discuss the possible dietary significance of these observations.This study was financially supported by projects CGL/2012/39545 and AGL2015/68405/R (Spanish Ministry of Economy and Competitiveness) and PROMETEO II/2015/018 (Generalitat Valenciana, Spain)

Reversible Functional Changes Evoked by Anodal Epidural Direct Current Electrical Stimulation of the Rat Auditory Cortex

Rat auditory cortex was subjected to 0.1 mA anodal direct current in seven 10-min sessions on alternate days. Based on the well-known auditory cortex control of olivocochlear regulation through corticofugal projections, auditory brainstem responses (ABRs) were recorded as an indirect test of the effectiveness and reversibility of the multisession protocol of epidural stimulation. Increases of 20–30 dB ABR auditory thresholds shown after epidural stimulation reverted back to control levels 10 min after a single session. However, increases in thresholds revert 4 days after multisession stimulation. Less changes in wave amplitudes and threshold shifts were shown in ABR recorded contralaterally to the electrically stimulated side of the brain. To assess tissue effects of epidural electric stimulation on the brain cortex, well characterized functional anatomical markers of glial cells (GFAP/astrocytes and Iba1/microglial cells) and neurons (c-Fos) were analyzed in alternate serial sections by quantitative immunocytochemistry. Restricted astroglial and microglial reactivity was observed within the cytoarchitectural limits of the auditory cortex. However, interstitial GFAP overstaining was also observed in the ventricular surface and around blood vessels, thus supporting a potential global electrolytic stimulation of the brain. These results correlate with extensive changes in the distribution of c-Fos immunoreactive neurons among layers along sensory cortices after multisession stimulation. Quantitative immunocytochemical analysis supported this idea by showing a significant increase in the number of positive neurons in supragranular layers and a decrease in layer 6 with no quantitative changes detected in layer 5. Our data indicate that epidural stimulation of the auditory cortex induces a reversible decrease in hearing sensitivity due to local, restricted epidural stimulation. A global plastic response of the sensory cortices, also reported here, may be related to electrolytic effects of electric currents

Combining Genetic and Transcriptomic Approaches to Identify Transporter-Coding Genes as Likely Responsible for a Repeatable Salt Tolerance QTL in Citrus

The excessive accumulation of chloride (Cl−) in leaves due to salinity is frequently related to decreased yield in citrus. Two salt tolerance experiments to detect quantitative trait loci (QTLs) for leaf concentrations of Cl−, Na+, and other traits using the same reference progeny derived from the salt-tolerant Cleopatra mandarin (Citrus reshni) and the disease-resistant donor Poncirus trifoliata were performed with the aim to identify repeatable QTLs that regulate leaf Cl− (and/or Na+) exclusion across independent experiments in citrus, as well as potential candidate genes involved. A repeatable QTL controlling leaf Cl− was detected in chromosome 6 (LCl-6), where 23 potential candidate genes coding for transporters were identified using the C. clementina genome as reference. Transcriptomic analysis revealed two important candidate genes coding for a member of the nitrate transporter 1/peptide transporter family (NPF5.9) and a major facilitator superfamily (MFS) protein. Cell wall biosynthesis- and secondary metabolism-related processes appeared to play a significant role in differential gene expression in LCl-6. Six likely gene candidates were mapped in LCl-6, showing conserved synteny in C. reshni. In conclusion, markers to select beneficial Cleopatra mandarin alleles of likely candidate genes in LCl-6 to improve salt tolerance in citrus rootstock breeding programs are provided

Capturado y registrado: potencial de las redes de varamientos para el estudio de las capturas accidentales de cetáceos

XII Congreso de la Sociedad Española de Cetáceos, 4 al 7 de octubre de 2021, onlineN

The first cetacean sightings network in Spain: results of a co-operation within the Spanish Cetacean Society

3 pages, 2 tables.-- Fifteenth Annual Conference of the European Cetacean Society, Rome, Italy, 6-10 May 200ln 1999, the Spanish Cetacean Society (SEC) was created in order to co-ordinate the activities of different organisations and research groups in Spain, and to provide assistance to regional and national authorities in issues related to the conservation of the marine environment. In July 1999, the Spanish Ministry for the Environment appointed to the SEC the custody of a national database of shandings and sightings of cetaceans in order to standardise the methodology used by all groups involved in these activities, and to facilitate the exchange of information among researchers. The Sightings Working Group of the SEC has been, since then, developing and updating the cetacean sightings database with the participation of most research and conservation groups working in Spain. This is the fìrst time in Spain that most groups put together their information creating a National Sightings Network and giving a fairly complete vision of cetacean distribution throughout the whole country, showing the importance of co-ordinated co-operation in the context of conservationDGCN (National Environment Agency) of the Spanish Ministry for the EnvironmentN

3D Morphology, Ultrastructure and Development of Ceratomyxa puntazzi Stages: First Insights into the Mechanisms of Motility and Budding in the Myxozoa

Free, amoeboid movement of organisms within media as well as substrate-dependent cellular crawling processes of cells and organisms require an actin cytoskeleton. This system is also involved in the cytokinetic processes of all eukaryotic cells. Myxozoan parasites are known for the disease they cause in economical important fishes. Usually, their pathology is related to rapid proliferation in the host. However, the sequences of their development are still poorly understood, especially with regard to pre-sporogonic proliferation mechanisms. The present work employs light microscopy (LM), electron microscopy (SEM, TEM) and confocal laser scanning microscopy (CLSM) in combination with specific stains (Nile Red, DAPI, Phalloidin), to study the three-dimensional morphology, motility, ultrastructure and cellular composition of Ceratomyxa puntazzi, a myxozoan inhabiting the bile of the sharpsnout seabream