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Current models of chemical evolution during star and planetary formation rely on the presence of dust grains to act as a third body. However, they generally ignore the reactivity of the dust grains themselves. Dust grains present in the protoplanetary phase will evolve as the Solar system forms and, after protoplanets have appeared, they will be constantly delivered to their surfaces in the form of large aggregates or meteorites. Chondritic meteorites are mostly unaltered samples of the dust present in the first stages of the Solar system formation, which still arrive nowadays to the surface of Earth and allow us to study the properties of the materials forming the early Solar system. These materials contain, amongst others, transition metals that can potentially act as catalysts, as well as other phases that can potentially react in different astrophysical conditions, such as FeS. In this work, we present the reactivity of chondritic meteorites under H |$_{2}$| -rich atmospheres, particularly towards the reduction of FeS for the formation of H |$_{2}$| S and metallic Fe during the early phases of the planetary formation. We present the obtained results on the reaction rates and the percentage of FeS available to react in the materials. Additionally, we include a computational study of the reaction mechanism and the energetics. Finally, we discuss the implications of an early formation of H |$_{2}$| S in planetary surfaces. [ABSTRACT FROM AUTHOR]

Context. The presence of grains is key to the synthesis of molecules in the interstellar medium that cannot form in the gas phase due to its low density and temperature conditions. In these reactions, the role of the grains is to enhance the encounter rate of the reactive species on their surfaces and to dissipate the energy excess of largely exothermic reactions, but less is known about their role as chemical catalysts; namely, bodies that provide low activation energy pathways with enhanced reaction rates. Different refractory materials with catalytic properties, such as those containing space-abundant d-block transition metals like iron (Fe), are present in astrophysical environments. Aims. Here, we report for first time mechanistic insights into the Fischer-Tropsch-type (FTT) synthesis of ethanol (CH3CH2OH), through ketene (CH2CO) and acetaldehyde (CH3CHO) intermediates, and methane (CH4) via a chain growing mechanism using a single-Fe atom supported on silica (SiO2) surfaces as a heterogeneous astrocatalyst. Methods. Quantum chemical simulations based on extended periodic surfaces were carried out to characterize the potential energy surfaces of the FTT chain growing mechanism. Calculations of the binding energies of reaction intermediates and products and Rice–Ramsperger–Kassel–Marcus kinetic calculations were performed to evaluate catalytic efficiencies and determine the feasibility of the reactions in different astrophysical environments. Results. Mechanistic studies demonstrate that the FTT chain growing mechanism enters into direct competition with FTT methanol formation, since formation of the CH2 chain growth initiator is feasible. The coupling of the CH2 with CO (forming ketene) and subsequent H2 additions yield acetaldehyde and finally ethanol, while direct H2 addition to CH2 produces methane. Thermodynamically, both processes are largely exergonic, but they present energy barriers that require external energy inputs to be overcome. Kinetic calculations demonstrate the strong temperature dependency of the FTT processes as tunneling does not dominate. Conclusions. The results could explain the presence of CH3CH2OH and CH4 in diverse astrophysical regions where current models fail to reproduce their observational quantities. The evidence that the chain growing mechanism is operating opens a new reactivity paradigm toward the formation of complex organic molecules, which is constrained by the temperature-dependent behaviour of the FTT reactions and by making their energy features a crucial aspect. [ABSTRACT FROM AUTHOR]

Importance: Brucella spp. are zoonotic pathogens that can affect both terrestrial and marine mammals. Brucella ceti has been identified in various cetacean species, but only one sequence type (ST27) has been reported in humans. However, it is important to conduct surveillance studies to better understand the impact of marine Brucella species on marine mammals, a typically understudied host group. Here, we describe a systemic infection by two related strains of Brucella pinnipedialis (ST25) in a couple of live-stranded bottlenose dolphins, with more severe lesions in the younger animal. Furthermore, B. pinnipedialis was first detected in milk from a female cetacean that stranded with its offspring. Our study reveals novel insights into the epidemiology and pathological consequences of B. pinnipedialis infections in cetaceans, emphasizing the crucial importance of ongoing surveillance and accurate diagnosis to understand the impact of this pathogen on marine mammal populations., Competing Interests: The authors declare no conflict of interest.

Background: A wide variety of lesions have been associated with herpesvirus in cetaceans. However, descriptions of herpesvirus infections in the digestive system of cetaceans are scarce., Case Report: A young female striped dolphin stranded in the Valencian Community (Spain) on the 6th August 2021. The animal showed external macroscopic lesions suggestive of an aggressive interaction with bottlenose dolphins (rake marks in the epidermis). Internally, the main findings included congestion of the central nervous system and multiple, well-defined, whitish, irregularly shaped, proliferative lesions on the oropharyngeal and laryngopharyngeal mucosa. Histopathology revealed lymphoplasmacytic and histiocytic meningoencephalitis, consistent with neuro brucellosis. The oropharyngeal and laryngopharyngeal plaques were comprised histologically of focally extensive epithelial hyperplasia. As part of the health surveillance program tissue samples were tested for cetacean morbillivirus using a real-time reverse transcription-PCR, for Brucella spp. using a real-time PCR, and for herpesvirus using a conventional nested PCR. All samples were negative for cetacean morbillivirus; molecular positivity for Brucella spp. was obtained in pharyngeal tonsils and cerebrospinal fluid; herpesvirus was detected in a proliferative lesion in the upper digestive mucosa. Phylogenetic analysis showed that the herpesvirus sequence was included in the Gammaherpesvirinae subfamily. This novel sequence showed the greatest identity with other Herpesvirus sequences detected in skin, pharyngeal and genital lesions in five different species., Conclusions: To the best of the authors' knowledge, this is the first report of a proliferative lesion in the upper digestive mucosa associated with gammaherpesvirus posititvity in a striped dolphin (Stenella coeruleoalba)., (© 2023. The Author(s).)

Homing pigeons (Columba livia domestica) were used to test whether clinical magnetic resonance (MR) imaging disrupts orientation of animals that sense the earth's magnetic field. Thirty young pigeons were randomly separated into three groups (n = 10/group). Two groups were anaesthetized and exposed to either a constant (no sequence) or a varying (gradient echo and echo planar sequences) magnetic field within a 3 Tesla MR unit for 15 minutes. The control group was not exposed to the MR field but shared all other aspects of the procedure. One day later, animals were released from a site they had never visited, 15 km from the home loft. Three weeks after the procedure, animals were released from a different unfamiliar site 30 km from the loft. Measured variables included the time to disappear from sight (seconds), vanishing bearing (angle), and the time interval from release to entering the home loft (hours). On first release, the group exposed to varying field gradients during image acquisition using 2 different standard sequences showed more variability in the vanishing bearing compared to the other groups (p = 0.0003 compared to control group), suggesting interference with orientation. Other measures did not show significant differences between groups. On second release, there were no significant differences between groups. Our results on homing pigeons show that regular clinical MR imaging exposure may temporarily affect the orientation of species that have magnetoreception capabilities. If exposure to MR imaging disrupted processes that are not specific to magnetoreception, then it may affect other species and other capabilities as well., Competing Interests: The authors have declared that no competing interests exist.

Background: Herpesvirus infections in cetaceans have always been attributed to the Alphaherpesvirinae and Gammaherpesvirinae subfamilies. To date, gammaherpesviruses have not been reported in the central nervous system of odontocetes., Case Presentation: A mass stranding of 14 striped dolphins (Stenella coeruleoalba) occurred in Cantabria (Spain) on 18th May 2019. Tissue samples were collected and tested for herpesvirus using nested polymerase chain reaction (PCR), and for cetacean morbillivirus using reverse transcription-PCR. Cetacean morbillivirus was not detected in any of the animals, while gammaherpesvirus was detected in nine male and one female dolphins. Three of these males were coinfected by alphaherpesviruses. Alphaherpesvirus sequences were detected in the cerebrum, spinal cord and tracheobronchial lymph node, while gammaherpesvirus sequences were detected in the cerebrum, cerebellum, spinal cord, pharyngeal tonsils, mesenteric lymph node, tracheobronchial lymph node, lung, skin and penile mucosa. Macroscopic and histopathological post-mortem examinations did not unveil the potential cause of the mass stranding event or any evidence of severe infectious disease in the dolphins. The only observed lesions that may be associated with herpesvirus were three cases of balanitis and one penile papilloma., Conclusions: To the authors' knowledge, this is the first report of gammaherpesvirus infection in the central nervous system of odontocete cetaceans. This raises new questions for future studies about how gammaherpesviruses reach the central nervous system and how infection manifests clinically.