Experience overrides personality differences in the tendency to follow but not in the tendency to lead

In many animal groups, coordinated activity is facilitated by the emergence of leaders and followers. Although the identity of leaders is to some extent predictable, most groups experience frequent changes of leadership. How do group members cope with such changes in their social role? Here, we compared the foraging behaviour of pairs of stickleback fish after a period of either (i) role reinforcement, which involved rewarding the shyer follower for following, and the bolder leader for leading, or (ii) role reversal, which involved rewarding the shyer follower for leading, and the bolder leader for following. We found that, irrespective of an individual''s temperament, its tendency to follow is malleable, whereas the tendency to initiate collective movement is much more resistant to change. As a consequence of this lack of flexibility in initiative, greater temperamental differences within a pair led to improved performance when typical roles were reinforced, but to impaired performance when typical roles were reversed.     

Sequence-specific 1HN, 13C, and 15N backbone resonance assignments of the 34 kDa Paramecium bursaria Chlorella virus 1 (PBCV1) DNA ligase

Chlorella virus DNA ligase (ChVLig) is a minimal (298-amino acid) pluripotent ATP-dependent ligase composed of three structural modules—a nucleotidyltransferase domain, an OB domain, and a β-hairpin latch—that forms a circumferential clamp around nicked DNA. ChVLig provides an instructive model to understand the chemical and conformational steps of nick repair. Here we report the assignment of backbone ¹³C, ¹⁵N, ¹H^N resonances of this 34.2 kDa protein, the first for a DNA ligase in full-length form.     

Isolation and characterization of a methyl chloride utilizing,strictly anaerobic bacterium

From sludge obtained from the sewage digester plant in Stuttgart-Möhringen a strictly anaerobic bacterium was enriched and isolated with methyl chloride as the energy source. The isolate, which was tentatively called strain MC, was nonmotile, gram-positive, and occurred as elongated cocci arranged in chains. Cells of strain MC formed about 3 mol of acetate per 4 mol of CH₃Cl consumed, indicating that the organism was a homoacetogenic bacterium fermenting methyl chloride plus CO₂ according to: The organism grew with 2–3% methyl chloride in the gas phase at a doubling time of near 30 h. Dichloromethane was not utilized. The bacterium also grew on carbon monoxide, H₂ plus CO₂, and methoxylated aromatic compounds. Optimal growth with methyl chloride was observed at 25°C and pH 7.3–7.7. The G+C-content of the DNA was 47.5±1.5%. The methyl chloride conversion appeared to be inducible, since H₂ plus CO₂-grown cells lacked this ability. From the morphological and physiological characteristics, the isolate could not be affiliated to a known species.     

Strong postmating reproductive isolation in Mimulus section Eunanus

Postmating reproductive isolation can help maintain species boundaries when premating barriers to reproduction are incomplete. The strength and identity of postmating reproductive barriers are highly variable among diverging species, leading to questions about their genetic basis and evolutionary drivers. These questions have been tackled in model systems but are less often addressed with broader phylogenetic resolution. In this study we analyse patterns of genetic divergence alongside direct measures of postmating reproductive barriers in an overlooked group of sympatric species within the model monkeyflower genus, Mimulus. Within this Mimulus brevipes species group, we find substantial divergence among species, including a cryptic genetic lineage. However, rampant gene discordance and ancient signals of introgression suggest a complex history of divergence. In addition, we find multiple strong postmating barriers, including postmating prezygotic isolation, hybrid seed inviability and hybrid male sterility. M. brevipes and M. fremontii have substantial but incomplete postmating isolation. For all other tested species pairs, we find essentially complete postmating isolation. Hybrid seed inviability appears linked to differences in seed size, providing a window into possible developmental mechanisms underlying this reproductive barrier. While geographic proximity and incomplete mating isolation may have allowed gene flow within this group in the distant past, strong postmating reproductive barriers today have likely played a key role in preventing ongoing introgression. By producing foundational information about reproductive isolation and genomic divergence in this understudied group, we add new diversity and phylogenetic resolution to our understanding of the mechanisms of plant speciation.     

The distribution of coastal fish eDNA sequences in the Anthropocene

Aim

Coastal fishes have a fundamental role in marine ecosystem functioning and contributions to people, but face increasing threats due to climate change, habitat degradation and overexploitation. The extent to which human pressures are impacting coastal fish biodiversity in comparison with geographic and environmental factors at large spatial scale is still under scrutiny. Here, we took advantage of environmental DNA (eDNA) metabarcoding to investigate the relationship between fish biodiversity, including taxonomic and genetic components, and environmental but also socio-economic factors.

Location

Tropical, temperate and polar coastal areas.

Time period

Present day.

Major taxa studied

Marine fishes.

Methods

We analysed fish eDNA in 263 stations (samples) in 68 sites distributed across polar, temperate and tropical regions. We modelled the effect of environmental, geographic and socio-economic factors on α- and β-diversity. We then computed the partial effect of each factor on several fish biodiversity components using taxonomic molecular units (MOTU) and genetic sequences. We also investigated the relationship between fish genetic α- and β-diversity measured from our barcodes, and phylogenetic but also functional diversity.

Results

We show that fish eDNA MOTU and sequence α- and β-diversity have the strongest correlation with environmental factors on coastal ecosystems worldwide. However, our models also reveal a negative correlation between biodiversity and human dependence on marine ecosystems. In areas with high dependence, diversity of all fish, cryptobenthic fish and large fish MOTUs declined steeply. Finally, we show that a sequence diversity index, accounting for genetic distance between pairs of MOTUs, within and between communities, is a reliable proxy of phylogenetic and functional diversity.

Main conclusions

Together, our results demonstrate that short eDNA sequences can be used to assess climate and direct human impacts on marine biodiversity at large scale in the Anthropocene and can further be extended to investigate biodiversity in its phylogenetic and functional dimensions.     

Enterocin M-Producing Enterococcus faecium CCM 8558 Demonstrating Probiotic Properties in Horses

The effects of non-authochtonous Enterococcus faecium AL41 = CCM 8558, enterocin M-producing and probiotic strain were tested on the microbiota, phagocytic activity, hydrolytic enzymes, biochemical parameters and dry matter in horses based on its previous benefits demonstrated in other animals. E. faecium CCM 8558 sufficiently colonized the digestive tract of horses. At day 14, its counts reached 2.35 ± 0.70 CFU/g (log 10) on average. The identity of CCM 8558 was confirmed by means of PCR after its re-isolation from horse faeces. The inhibition activity of CCM 8558 was demonstrated against Gram-negative aeromonads, counts of which were significantly reduced (P < 0.001). After 14 days application of CCM 8558, a tendency towards increased phagocytic activity (PA) was measured; PA value was 73.13% ± 8.55 on average at day 0/1; at day 14, it was 75.11 ± 8.66%. Cellulolytic, xylanolytic and pectinolytic activity in horse faeces was significantly increased (P < 0.001) at day 14 (after CCM 8558 application) and amylolytic activity as well (P < 0.01) compared to day 0/1. Inulolytic activity increased with mathematical difference 1.378. Dry matter value reached 20.81 ± 2.29% on average at day 0/1; at day 14, it was 20.77 ± 2.59% (P = 0.9725). Biochemical parameters were influenced mostly in the physiological range. These results achieved after application of CCM 8558 in horses are original, giving us further opportunity to continue these studies, to measure additional parameters and to show the benefits of CCM 8558 application in horses.

     

Glycosaminoglycan-dependent restriction of FGF diffusion is necessary for lacrimal gland development

Glycosaminoglycans (GAGs) play a central role in embryonic development by regulating the movement and signaling of morphogens. We have previously demonstrated that GAGs are the co-receptors for Fgf10 signaling in the lacrimal gland epithelium, but their function in the Fgf10-producing periocular mesenchyme is still poorly understood. In this study, we have generated a mesenchymal ablation of UDP-glucose dehydrogenase (Ugdh), an essential biosynthetic enzyme for GAGs. Although Fgf10 RNA is expressed normally in the periocular mesenchyme, Ugdh mutation leads to excessive dispersion of Fgf10 protein, which fails to elicit an FGF signaling response or budding morphogenesis in the presumptive lacrimal gland epithelium. This is supported by genetic rescue experiments in which the Ugdh lacrimal gland defect is ameliorated by constitutive Ras activation in the epithelium but not in the mesenchyme. We further show that lacrimal gland development requires the mesenchymal expression of the heparan sulfate N-sulfation genes Ndst1 and Ndst2 but not the 6-O and 2-O-sulfation genes Hs6st1, Hs6st2 and Hs2st. Taken together, these results demonstrate that mesenchymal GAG controls lacrimal gland induction by restricting the diffusion of Fgf10.     

Achromobacter xylosoxidans: An Emerging Pathogen Carrying Different Elements Involved in Horizontal Genetic Transfer

In the last few years, numerous cases of multidrug-resistant Achromobacter xylosoxidans infections have been documented in immunocompromised and cystic fibrosis patients. To gain insights into the molecular mechanisms and mobile elements related to multidrug resistance in this bacterium, we studied 24 non-epidemiological A. xylosoxidans clinical isolates from Argentina. Specific primers for plasmids, transposons, insertion sequences, bla _ampC, intI1, and intI2 genes were used in PCR reactions. The obtained results showed the presence of wide host range IncP plasmids in ten isolates and a high dispersion of class 1 integrons (n?=?10) and class 2 integrons (n?=?3). Four arrays in the variable region (vr) of class 1 integrons were identified carrying different gene cassettes as the aminoglycoside resistance aac(6′)-Ib and aadA1, the trimethoprim resistance dfrA1 and dfrA16, and the β-lactamase bla _OXA-2. In only one of the class 2 integrons, a vr was amplified that includes sat2-aadA1. The bla _ampC gene was found in all isolates, confirming its ubiquitous nature. Our results show that A. xylosoxidans clinical isolates contain a rich variety of genetic elements commonly associated with resistance genes and their dissemination. This supports the hypothesis that A. xylosoxidans is becoming a reservoir of horizontal genetic transfer elements commonly involved in spreading antibiotic resistance.