Overview of the Distribution,Habitat Association and Impact of Exotic Ants on Native Ant Communities in New Caledonia

Ants are among the most ubiquitous and harmful invaders worldwide, but there are few regional studies of their relationships with habitat and native ant communities. New Caledonia has a unique and diverse ant fauna that is threatened by exotic ants, but broad-scale patterns of exotic and native ant community composition in relation to habitat remain poorly documented. We conducted a systematic baiting survey of 56 sites representing the main New Caledonian habitat types: rainforest on ultramafic soils (15 sites), rainforest on volcano-sedimentary soils (13), maquis shrubland (15), Melaleuca-dominated savannas (11) and Acacia spirorbis thickets (2). We collected a total of 49 species, 13 of which were exotic. Only five sites were free of exotic species, and these were all rainforest. The five most abundant exotic species differed in their habitat association, with Pheidole megacephala associated with rainforests, Brachymyrmex cf. obscurior with savanna, and Wasmannia auropunctata and Nylanderia vaga present in most habitats. Anoplolepis gracilipes occurred primarily in maquis-shrubland, which contrasts with its rainforest affinity elsewhere. Multivariate analysis of overall ant species composition showed strong differentiation of sites according to the distribution of exotic species, and these patterns were maintained at the genus and functional group levels. Native ant composition differed at invaded versus uninvaded rainforest sites, in the absence of differences in habitat variables. Generalised Myrmicinae and Forest Opportunists were particularly affected by invasion. There was a strong negative relationship between the abundance of W. auropunctata and native ant abundance and richness. This emphasizes that, in addition to dominating many ant communities numerically, some exotic species, and in particular W. auropunctata, have a marked impact on native ant communities.     

Proteomic Characterization of Murid Herpesvirus 4 Extracellular Virions

Gammaherpesvirinae, such as the human Epstein-Barr virus (EBV) and the Kaposi’s sarcoma associated herpesvirus (KSHV) are highly prevalent pathogens that have been associated with several neoplastic diseases. As EBV and KSHV are host-range specific and replicate poorly in vitro, animal counterparts such as Murid herpesvirus-4 (MuHV-4) have been widely used as models. In this study, we used MuHV-4 in order to improve the knowledge about proteins that compose gammaherpesviruses virions. To this end, MuHV-4 extracellular virions were isolated and structural proteins were identified using liquid chromatography tandem mass spectrometry-based proteomic approaches. These analyses allowed the identification of 31 structural proteins encoded by the MuHV-4 genome which were classified as capsid (8), envelope (9), tegument (13) and unclassified (1) structural proteins. In addition, we estimated the relative abundance of the identified proteins in MuHV-4 virions by using exponentially modified protein abundance index analyses. In parallel, several host proteins were found in purified MuHV-4 virions including Annexin A2. Although Annexin A2 has previously been detected in different virions from various families, its role in the virion remains controversial. Interestingly, despite its relatively high abundance in virions, Annexin A2 was not essential for the growth of MuHV-4 in vitro. Altogether, these results extend previous work aimed at determining the composition of gammaherpesvirus virions and provide novel insights for understanding MuHV-4 biology.     

The res (restored cell structure by salinity) tomato mutant reveals the role of the DEAD-box RNA helicase SlDEAD39 in plant development and salt response

Increasing evidences highlight the importance of DEAD-box RNA helicases in plant development and stress responses. In a previous study, we characterized the tomato res mutant (restored cell structure by salinity), showing chlorosis and development alterations that reverted under salt-stress conditions. Map-based cloning demonstrates that RES gene encodes SlDEAD39, a chloroplast-targeted DEAD-box RNA helicase. Constitutive expression of SlDEAD39 complements the res mutation, while the silencing lines had a similar phenotype than res mutant, which is also reverted under salinity. Functional analysis of res mutant proved SlDEAD39 is involved in the in vivo processing of the chloroplast, 23S rRNA, at the hidden break-B site, a feature also supported by in vitro binding experiments of the protein. In addition, our results show that other genes coding for chloroplast-targeted DEAD-box proteins are induced by salt-stress, which might explain the rescue of the res mutant phenotype. Interestingly, salinity restored the phenotype of res adult plants by increasing their sugar content and fruit yield. Together, these results propose an unprecedented role of a DEAD-box RNA helicase in regulating plant development and stress response through the proper ribosome and chloroplast functioning, which, in turn, represents a potential target to improve salt tolerance in tomato crops.     

Exogenous strigolactones impact metabolic profiles and phosphate starvation signalling in roots

Strigolactones (SLs) are important ex-planta signalling molecules in the rhizosphere, promoting the association with beneficial microorganisms, but also affecting plant interactions with harmful organisms. They are also plant hormones in-planta, acting as modulators of plant responses under nutrient-deficient conditions, mainly phosphate (Pi) starvation. In the present work, we investigate the potential role of SLs as regulators of early Pi starvation signalling in plants. A short-term pulse of the synthetic SL analogue 2′-epi-GR24 promoted SL accumulation and the expression of Pi starvation markers in tomato and wheat under Pi deprivation. 2′-epi-GR24 application also increased SL production and the expression of Pi starvation markers under normal Pi conditions, being its effect dependent on the endogenous SL levels. Remarkably, 2′-epi-GR24 also impacted the root metabolic profile under these conditions, promoting the levels of metabolites associated to plant responses to Pi limitation, thus partially mimicking the pattern observed under Pi deprivation. The results suggest an endogenous role for SLs as Pi starvation signals. In agreement with this idea, SL-deficient plants were less sensitive to this stress. Based on the results, we propose that SLs may act as early modulators of plant responses to P starvation.     

A new genus and two new species of trypanorhynch cestodes (Tentaculariidae) from the sharks Carcharhinus sorrah (Müller & Henle) and Sphyrna lewini (Griffith & Smith) from off the coasts of Malaysia and Mexico

Two new tentaculariid species were found infecting carcharhiniform sharks from off the coasts of Malaysian Borneo and the southwestern coast of the Baja California Sur, Mexico. Both new species exhibit a homeoacanthous heteromorphous basal and a homeoacanthous homeomorphous metabasal armature. Since this hook arrangement is unique within the tentaculariids and the taxonomy in this group deeply depends on the tentacular armature, Reimeriella n. g. is erected to accommodate R. varioacantha n. sp. ex Carcharhinus sorrah (Müller & Henle) and R. mexicoensis n. sp. ex Sphyrna lewini (Griffith & Smith). Unlike R. mexicoensis n. sp., R. varioacantha n. sp. has a pars bothrialis not overlapping the pars bulbosa and the number of testes is higher. Reimeriella mexicoensis n. sp. possesses very large uncinate to falcate hooks in the basal armature, while in R. varioacantha n. sp. these hooks are almost the same in size as the remaining hooks in both the basal and metabasal armature. The latter species is the first tentaculariid species where the metabasal armature very closely resembles an eutetrarhynchid with a heteroacanthous typical homeomorphous metabasal armature and a high number of spiniform hooks per half spiral row (10–11 vs 6–7 in R. mexicoensis n. sp.) in the metabasal and apical armature. This pattern provides further morphological evidence for the close relationship of the Eutetrarhynchoidea and the Tentacularioidea. Reimeriella varioacantha n. sp. enriches the trypanorhynch fauna from off the coast of Malaysian Borneo while R. mexicoensis n. sp. is a novel record of a tentaculariid trypanorhynch from the Mexican Pacific.

     

Length-weight relationships of seven fish species from the laguna del cisne basin (Canelones,Uruguay)

This work provides new length-weight information for seven species of freshwater fishes. The analyzed specimens were collected monthly during a year (April 2018–March 2019) in a coastal lagoon system and its associated streams in southern Uruguay. During each sampling campaign, fishes were captured using gillnets in the lagoon and electrofishing in the streams. This study reports a new maximum size for four species and the first length-weight relationship report for Gymnogeophagus terrapurpura. Length-weight estimates and their confidence intervals are provided for all species.