Memory of Social Partners in Hermit Crab Dominance

We investigated the possibility that invertebrates recognize conspecific individuals by studying dominance relationships in the long‐clawed hermit crab, Pagurus longicarpus. We conducted three sets of laboratory experiments to define the time limits for acquiring and maintaining memory of an individual opponent. The results reveal two characteristics that make individual recognition in this species different from standard associative learning tasks. Firstly, crabs do not require training over many repeated trials; rather, they show evidence of recognition after a single 30‐min exposure to a stimulus animal. Secondly, memory lasts for up to 4 d of isolation without reinforcement. A third interesting feature of individual recognition in this species is that familiar opponents are recognized even before the formation of a stable hierarchical rank. That is, recognition seems to be relatively independent of repeated wins (rewards) or losses (punishments) in a dominance hierarchy. The experimental protocol allowed us to show that this species is able to classify conspecifics into two ‘heterogeneous subgroups’, i.e. familiar vs. unfamiliar individuals, but not to discriminate one individual of a group from every other conspecific from ‘a unique set of cues defining that individual’. In other words, we demonstrated a ‘binary’– and not a ‘true’– individual recognition. However, 1 d of interactions with different crabs did not erase the memory of a former rival, suggesting that P. longicarpus uses a system of social partner discrimination more refined than previously shown.     

Viral gut metagenomics of sympatric wild and domestic canids,and monitoring of viruses: Insights from an endangered wolf population

Animal host–microbe interactions are a relevant concern for wildlife conservation, particularly regarding generalist pathogens, where domestic host species can play a role in the transmission of infectious agents, such as viruses, to wild animals. Knowledge on viral circulation in wild host species is still scarce and can be improved by the recent advent of modern molecular approaches. We aimed to characterize the fecal virome and identify viruses of potential conservation relevance of diarrheic free‐ranging wolves and sympatric domestic dogs from Central Portugal, where a small and threatened wolf population persists in a highly anthropogenically modified landscape. Using viral metagenomics, we screened diarrheic stools collected from wolves (n = 8), feral dogs (n = 4), and pet dogs (n = 6), all collected within wolf range. We detected novel highly divergent viruses as well as known viral pathogens with established effects on population dynamics, including canine distemper virus, a novel bocavirus, and canine minute virus. Furthermore, we performed a 4‐year survey for the six wolf packs comprising this endangered wolf population, screening 93 fecal samples from 36 genetically identified wolves for canine distemper virus and the novel bocavirus, previously identified using our metagenomics approach. Our novel approach using metagenomics for viral screening in noninvasive samples of wolves and dogs has profound implications on the knowledge of both virology and wildlife diseases, establishing a complementary tool to traditional screening methods for the conservation of threatened species.     

Immune activation suppresses plasma testosterone level: a meta-analysis

Females often select mates on the basis of sexual signals, which can be reliable indicators of male quality when the costliness of these signals prevents cheating. The immunocompetence handicap hypothesis (ICHH) provides a mechanistic explanation of these costs, by proposing a trade-off between immune function and sexual displays. This trade-off arises because testosterone enhances sexual signals, but suppresses immune function. Many studies have investigated the ICHH by administrating testosterone, and a recent meta-analysis found little evidence that testosterone suppressed immune function. However, another component of the ICHH, which has received less empirical interest, suggests that there may also be an interaction in the other direction, with immune activation suppressing testosterone levels. We present a meta-analysis to test for this effect. Overall, there was a strong suppressive effect of experimental immune activation on testosterone levels (r=-0.52), regardless of whether live pathogens or non-pathogenic antigens were used to challenge the immune system. The latter is important because it shows that immune activation per se suppresses testosterone levels. Thus, a trade-off between immunocompetence and sexual displays may primarily be generated by the effect of immune activation on testosterone, rather than the opposite effect that has received most attention.     

Autocorrelated logistic ridge regression for prediction based on proteomics spectra

This paper presents autocorrelated logistic ridge regression, an extension of logistic ridge regression for ordered covariates that is based on the assumption that adjacent covariates have similar regression coefficients. The method is applied to the analysis of proteomics mass spectra.     

Full genome-based classification of rotaviruses reveals a common origin between human Wa-Like and porcine rotavirus strains and human DS-1-like and bovine rotavirus strains

Group A rotavirus classification is currently based on the molecular properties of the two outer layer proteins, VP7 and VP4, and the middle layer protein, VP6. As reassortment of all the 11 rotavirus gene segments plays a key role in generating rotavirus diversity in nature, a classification system that is based on all the rotavirus gene segments is desirable for determining which genes influence rotavirus host range restriction, replication, and virulence, as well as for studying rotavirus epidemiology and evolution. Toward establishing such a classification system, gene sequences encoding VP1 to VP3, VP6, and NSP1 to NSP5 were determined for human and animal rotavirus strains belonging to different G and P genotypes in addition to those available in databases, and they were used to define phylogenetic relationships among all rotavirus genes. Based on these phylogenetic analyses, appropriate identity cutoff values were determined for each gene. For the VP4 gene, a nucleotide identity cutoff value of 80% completely correlated with the 27 established P genotypes. For the VP7 gene, a nucleotide identity cutoff value of 80% largely coincided with the established G genotypes but identified four additional distinct genotypes comprised of murine or avian rotavirus strains. Phylogenetic analyses of the VP1 to VP3, VP6, and NSP1 to NSP5 genes showed the existence of 4, 5, 6, 11, 14, 5, 7, 11, and 6 genotypes, respectively, based on nucleotide identity cutoff values of 83%, 84%, 81%, 85%, 79%, 85%, 85%, 85%, and 91%, respectively. In accordance with these data, a revised nomenclature of rotavirus strains is proposed. The novel classification system allows the identification of (i) distinct genotypes, which probably followed separate evolutionary paths; (ii) interspecies transmissions and a plethora of reassortment events; and (iii) certain gene constellations that revealed (a) a common origin between human Wa-like rotavirus strains and porcine rotavirus strains and (b) a common origin between human DS-1-like rotavirus strains and bovine rotaviruses. These close evolutionary links between human and animal rotaviruses emphasize the need for close simultaneous monitoring of rotaviruses in animals and humans.     

Long-term memory of individual identity in ant queens

Remembering individual identities is part of our own everyday social life. Surprisingly, this ability has recently been shown in two social insects. While paper wasps recognize each other individually through their facial markings, the ant, Pachycondyla villosa, uses chemical cues. In both species, individual recognition is adaptive since it facilitates the maintenance of stable dominance hierarchies among individuals, and thus reduces the cost of conflict within these small societies. Here, we investigated individual recognition in Pachycondyla ants by quantifying the level of aggression between pairs of familiar or unfamiliar queens over time. We show that unrelated founding queens of P. villosa and Pachycondyla inversa store information on the individual identity of other queens and can retrieve it from memory after 24h of separation. Thus, we have documented for the first time that long-term memory of individual identity is present and functional in ants. This novel finding represents an advance in our understanding of the mechanism determining the evolution of cooperation among unrelated individuals.     

Heterologous expression of cDNAs encoding monodehydroascorbate reductases from the moss, <Emphasis Type="Italic">Physcomitrella patens</Emphasis> and characterization of the expressed enzymes

Monodehydroascorbate reductase (MDHAR; EC 1.6.5.4) catalyses the reduction of the monodehydroascorbate (MDHA) radical to ascorbate, using NADH or NADPH as an electron donor, and is believed to be involved in maintaining the reactive oxygen scavenging capability of plant cells. This key enzyme in the ascorbate-glutathione cycle has been studied here in the moss Physcomitrella patens, which is tolerant to a range of abiotic stresses and is increasingly used as a model plant. In the present study, three cDNAs encoding different MDHAR isoforms of 47 kDa were identified in P. patens, and found to exhibit enzymic characteristics similar to MDHARs in vascular plants despite low-sequence identity and a distant evolutionary relationship between the species. The three cDNAs for the P. patens MDHAR enzymes were expressed in Escherichia coli and the active enzymes were purified and characterized. Each recombinant protein displayed an absorbance spectrum typical of flavoenzymes and contained a single non-covalently bound FAD coenzyme molecule. The K _m and k _cat values for the heterologously expressed PpMDHAR enzymes ranged from 8 to 18 μM and 120–130 s⁻¹, respectively, using NADH as the electron donor. The K _m values were at least an order of magnitude higher for NADPH. The K _m values for the MDHA radical were ∼0.5–1.0 μM for each of the purified enzymes, and further kinetic analyses indicated that PpMDHARs follow a ‘ping–pong’ kinetic mechanism. In contrast to previously published data, site-directed mutagenesis indicated that the conserved cysteine residue is not directly involved in the reduction of MDHA.     

The Itaconate Pathway Is a Central Regulatory Node Linking Innate Immune Tolerance and Trained Immunity

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