We compiled a data set of the compounds that terrestrial vertebrates (amniotes) use to send chemical signals, and searched for relationships between signal compound properties and signal function. ...Overall, relationships were scarce and formed only small-scale patterns. Terrestrial vertebrate signalling compounds are invariably components of complex mixtures of compounds with diverse molecular weights and functionalities. Signal compounds with high molecular weights (MWs) and low vapour pressures, or that are bound to carrier proteins, are detected during direct contact with the source of the signal. Stable compounds with aromatic rings in their structures are more common in signals of social dominance, including territoriality. Aldehydes are emitted from the sender's body rather than from scent marks. Lipocalin pheromones and carriers have a limited range of MWs, possibly to reduce the metabolic costs of their biosynthesis. Design constraints that might channel signal chemistry into patterns have been relaxed by amniote behavior and biochemistry. Amniote olfaction has such a high sensitivity, wide range and narrow resolution that signal detection imposes no practical constraints on the structures of signalling molecules. Diverse metabolic pathways in amniotes and their microbial commensals produce a wide variety of compounds as chemical signals and as matrix compounds that free signal components from the constraints of stability, vapor pressure, species-specificity etc. that would otherwise constrain what types of compound operate optimally under different conditions.
Most studies of adaptive immunity to SARS-CoV-2 infection focus on peripheral blood, which may not fully reflect immune responses at the site of infection. Using samples from 110 children undergoing ...tonsillectomy and adenoidectomy during the COVID-19 pandemic, we identified 24 samples with evidence of previous SARS-CoV-2 infection, including neutralizing antibodies in serum and SARS-CoV-2-specific germinal center and memory B cells in the tonsils and adenoids. Single-cell B cell receptor (BCR) sequencing indicated virus-specific BCRs were class-switched and somatically hypermutated, with overlapping clones in the two tissues. Expanded T cell clonotypes were found in tonsils, adenoids and blood post-COVID-19, some with CDR3 sequences identical to previously reported SARS-CoV-2-reactive T cell receptors (TCRs). Pharyngeal tissues from COVID-19-convalescent children showed persistent expansion of germinal center and antiviral lymphocyte populations associated with interferon (IFN)-γ-type responses, particularly in the adenoids, and viral RNA in both tissues. Our results provide evidence for persistent tissue-specific immunity to SARS-CoV-2 in the upper respiratory tract of children after infection.
Remote monitoring of communal marking sites, or latrines, provides a unique opportunity to observe undisturbed scent marking behaviour of African wild dogs (Lycaon pictus). We used remote camera trap ...observations in a natural experiment to test behavioural scent mark responses to rivals (either familiar neighbours or unfamiliar strangers), to determine whether wild dogs exhibit the “dear enemy” or “nasty neighbour” response. Given that larger groups of wild dogs represent a greater threat to smaller groups, including for established residents, we predicted that the overarching categories “dear enemy” vs. “nasty neighbour” may be confounded by varying social statuses that exists between individual dyads interacting. Using the number of overmarks as a metric, results revealed an interaction between sender and receiver group size irrespective of familiarity consistent with this prediction: in general, individuals from large resident packs overmarked large groups more than they overmarked smaller groups, whereas individuals from smaller packs avoided overmarking larger groups, possibly to avoid detection. Monitoring a natural system highlights variables such as pack size that may be either overlooked or controlled during scent presentation experiments, influencing our ability to gain insights into the factors determining territorial responses to rivals.
Using camera traps to generate behavioural data to act as a “natural experiment” to determine African wild dog responses to rivals (unfamiliar strangers vs. familiar neighbours). Authors found that group size impacts behavioural responses, and highlights shortcomings of scent presentation experiments in determining territorial responses to rivals.
People with mitochondrial disease (MtD) are susceptible to metabolic decompensation and neurological symptom progression in response to an infection. Increasing evidence suggests that mitochondrial ...dysfunction may cause chronic inflammation, which may promote hyper-responsiveness to pathogens and neurodegeneration. We sought to examine transcriptional changes between MtD patients and healthy controls to identify common gene signatures of immune dysregulation in MtD.
We collected whole blood from a cohort of MtD patients and healthy controls and performed RNAseq to examine transcriptomic differences. We performed GSEA analyses to compare our findings against existing studies to identify commonly dysregulated pathways.
Gene sets involved in inflammatory signaling, including type I interferons, interleukin-1β and antiviral responses, are enriched in MtD patients compared to controls. Monocyte and dendritic cell gene clusters are also enriched in MtD patients, while T cell and B cell gene sets are negatively enriched. The enrichment of antiviral response corresponds with an independent set of MELAS patients, and two mouse models of mtDNA dysfunction.
Through the convergence of our results, we demonstrate translational evidence of systemic peripheral inflammation arising from MtD, predominantly through antiviral response gene sets. This provides key evidence linking mitochondrial dysfunction to inflammation, which may contribute to the pathogenesis of primary MtD and other chronic inflammatory disorders associated with mitochondrial dysfunction.
Aggressive encounters may have important life history consequences due to the potential for injury and death, disease transmission, dispersal opportunities or exclusion from key areas of the home ...range. Despite this, little is known of their detailed dynamics, mainly due to the difficulties of directly observing encounters in detail. Here, we describe detailed spatial dynamics of inter-pack encounters in African wild dogs (Lycaon pictus), using data from custom-built high-resolution GPS collars in 11 free-ranging packs. On average, each pack encountered another pack approximately every 7 weeks and met each neighbour twice each year. Surprisingly, intruders were more likely to win encounters (winning 78.6% of encounters by remaining closer to the site in the short term). However, intruders did tend to move farther than residents toward their own range core in the short-term (1 h) post-encounter, and if this were used to indicate losing an encounter, then the majority (73.3%) of encounters were won by residents. Surprisingly, relative pack size had little effect on encounter outcome, and injuries were rare (<15% of encounters). These results highlight the difficulty of remotely scoring encounters involving mobile participants away from static defendable food resources. Although inter-pack range overlap was reduced following an encounter, encounter outcome did not seem to drive this, as both packs shifted their ranges post-encounter. Our results indicate that inter-pack encounters may be lower risk than previously suggested and do not appear to influence long-term movement and ranging.
Tandem marking occurs when both members of a pair scent-mark the same location in quick succession. This widespread behaviour, common in canids and monogamous antelopes, is generally believed to be ...involved in pair bond formation and advertisement. Despite their potential utility in determining tandem mark function, observations of individual contributions to tandem marking within pairs are rare. To this end, we made detailed observations of free-ranging dominant African wild dogs, Lycaon pictus, uncovering differences in the tandem-marking behaviour of pairs depending on their relatedness. In all packs, dominants were more likely to overmark their partner's scent mark than their own, but dominant-initiated scent marks were more likely to become tandem marks in related (full-sibling) pairs than in unrelated pairs. Despite this, females were more frequently on top at the end of marking bouts in related pairs than in unrelated pairs, because females in related pairs were more likely to overmark initial scent marks left by males, and less likely to have their scent marks subsequently overmarked by males. Scent-marking bout length was also significantly longer in related pairs. These differences suggest that advertising the presence of a mated dominant pair may be the main function of tandem marking in African wild dogs, but when mating opportunities are absent within the pack, contributions to tandem marking are altered, with individual advertisement perhaps becoming more important.
•In African wild dogs, relatedness affects scent-marking patterns within pairs.•In unrelated pairs, marking bouts are short and male marks are usually on top.•In related pairs, females mark more and are more likely to emerge on top at the end.•Advertising the presence of a mated pair may be the main function of tandem marking.•When mating opportunities are absent, individual advertisement takes precedence.
Scent‐marking is common in mammals, but where signals are carried by urine and faeces, distinguishing between scent‐marking and mere elimination is problematic. To do so, we documented behaviours and ...context variables associated with urination and defecation in free‐ranging endangered African wild dogs (Lycaon pictus) and tested whether these were related to the responses of other dogs to deposits. We found that distinct postures were almost uniquely associated with deposits by dominant wild dogs, were more common during urination than defecation, and increased the likelihood that these deposits would be investigated by other wild dogs. The likelihood of investigation depended on the sex and dominance status of the depositor, the type of deposit and the substrate. Urine from dominant females was more likely to be investigated by other wild dogs than any other deposits, and deposits placed on vegetation were more likely to be investigated than those on bare ground. The likelihood that a deposit would be overmarked was affected by the deposit type and the sex and dominance status of the last depositor. Collectively, these results suggest that dominant wild dog urine is of greatest interest to other dogs. Our results show that some deposits by African wild dogs are not scent‐marks and that detailed observations of behaviours and context variables during elimination events can be used to distinguish deposits that are likely to be of communication value.
High-performance liquid chromatography (HPLC)-UV and HPLC–Mass Spectrometry (MS) methods were developed for the quantitative analysis of the family of
Hoodia gordonii steroid glycosides with appetite ...suppressing properties in dried plant material, in purified and enriched extracts and in various prototype food-products fortified with
H. gordonii extracts.
For solid materials, e.g. dried plants or for non-fatty foods, extraction of the steroid glycosides is performed using methanol. For products where the steroid glycosides are present in an oil matrix, direct injection of the oil after dilution in tetrahydrofuran is applied. The HPLC separation is performed on an octyl-modified reversed-phase column in the gradient mode with UV detection at
λ
=
220
nm. Quantification is performed against an external calibration line prepared using either one of the pure steroid glycosides or geranyl-tiglate. Short- and long-term repeatabilities of the methods are better than 3 and 6%, respectively. Recoveries are better than 85%, even in the analysis of the least abundant steroid glycosides in a complex yoghurt drink. Linearity is better than 3–4 orders of magnitude and the detection limits are below approximately 2
μg
g
−1 for the individual steroid glycosides in dried plant material and food products. HPLC–MS is used to confirm that the steroid glycosides contain the characteristic steroid core, the carbohydrate chain and the tigloyl group.
Evaporation losses of organic solvents used to dissolve reference solutions and samples lead directly to errors in the measurement of amount of substance. This is due to changes in the mass fraction ...composition and the mass:volume concentration of solutions. We have found that measuring the amount of solute added to a solution by weighing by difference is vulnerable to negative bias in the measured amount of solute added, because solvent vapour is lost from opened vials and from syringe needles. Relative negative bias became larger with higher solvent volatility and with smaller volumes, reaching −28% for 10 µL of dichloromethane. Straightforward precautions that reduce the impact of evaporation on gravimetric operations with volatile solvents are presented.
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