Seasonal Enzyme Activities of Sympatric Calanus glacialis and C. finmarchicus in the High-Arctic

In the Arctic shelf seas, the mesozooplankton biomass is dominated by the arctic copepod Calanus glacialis, but its boreal congeneric C. finmarchicus is expanding northwards. Even though it is already there, C. finmarchicus may not be able to truly establish itself in the Arctic seas and potentially replace C. glacialis. We compared metabolic and digestive enzyme activities of sympatric C. glacialis and C. finmarchicus from Isfjorden, Svalbard and off-shelf north of Svalbard. The seasonal regulation of anabolic and catabolic enzyme activities was generally similar for the two species, but with some interspecific differences corresponding to their ontogeny. Wake-up from overwintering started earlier in adults of C. glacialis than in C. finmarchicus, while the onset of dormancy started early in the overwintering stages of both species. Furthermore, C. glacialis showed an earlier and higher mobilization of lipase enzyme activities, indicating higher efficiency in assimilating dietary lipids compared to C. finmarchicus. Similar population sizes and population structures for C. finmarchicus off-shelf north of Svalbard and in Isfjorden support a similar origin. Still, C. finmarchicus was able to match regulation of enzyme activities to the bloom even though the bloom peaked approximately a month later off-shelf north of Svalbard, indicating that food availability is an important signal for the final step of termination of diapause. Even though the two species largely follow the same patterns of metabolic enzyme activities, the more efficient lipid anabolism of C. glacialis may give it an advantage over C. finmarchicus in high-Arctic unpredictable environments with short-pulsed primary production regimes.publishedVersio

Ventx factors function as Nanog-like guardians of developmental potential in Xenopus

International audienceVertebrate development requires progressive commitment of embryonic cells into specific lineages through a continuum of signals that play off differentiation versus multipotency. In mammals, Nanog is a key transcription factor that maintains cellular pluripotency by controlling competence to respond to differentiation cues. Nanog orthologs are known in most vertebrates examined to date, but absent from the Anuran amphibian Xenopus. Interestingly, in silico analyses and literature scanning reveal that basal vertebrate ventral homeobox (ventxs) and mammalian Nanog factors share extensive structural, evolutionary and functional properties. Here, we reassess the role of ventx activity in Xenopus laevis embryos and demonstrate that they play an unanticipated role as guardians of high developmental potential during early development. Joint over-expression of Xenopus ventx1.2 and ventx2.1-b (ventx1/2) counteracts lineage commitment towards both dorsal and ventral fates and prevents msx1-induced ventralization. Furthermore, ventx1/2 inactivation leads to down-regulation of the multipotency marker oct91 and to premature differentiation of blastula cells. Finally, supporting the key role of ventx1/2 in the control of developmental potential during development, mouse Nanog (mNanog) expression specifically rescues embryonic axis formation in ventx1/2 deficient embryos. We conclude that during Xenopus development ventx1/2 activity, reminiscent of that of Nanog in mammalian embryos, controls the switch of early embryonic cells from uncommitted to committed states

Ex vivo multiscale quantitation of skin biomechanics in wild-type and genetically-modified mice using multiphoton microscopy

International audienceSoft connective tissues such as skin, tendon or cornea are made of about 90% of extracellular matrix proteins, fibrillar collagens being the major components. Decreased or aberrant collagen synthesis generally results in defective tissue mechanical properties as the classic form of Elhers-Danlos syndrome (cEDS). This connective tissue disorder is caused by mutations in collagen V genes and is mainly characterized by skin hyperextensibility. To investigate the relationship between the microstructure of normal and diseased skins and their macroscopic mechanical properties, we imaged and quantified the microstructure of dermis of ex vivo murine skin biopsies during uniaxial mechanical assay using multiphoton microscopy. We used two genetically-modified mouse lines for collagen V: a mouse model for cEDS harboring a Col5a2 deletion (a.k.a. pN allele) and the transgenic K14-COL5A1 mice which overexpress the human COL5A1 gene in skin. We showed that in normal skin, the collagen fibers continuously align with stretch, generating the observed increase in mechanical stress. Moreover, dermis from both transgenic lines exhibited altered collagen reorganization upon traction, which could be linked to microstructural modifications. These findings show that our multiscale approach provides new crucial information on the biomechanics of dermis that can be extended to all collagen-rich soft tissues

Sex differences in lipid and glucose kinetics after ingestion of an acute oral fructose load

The increase in VLDL TAG concentration after ingestion of a high-fructose diet is more pronounced in men than in pre-menopausal women. We hypothesised that this may be due to a lower fructose-induced stimulation of de novo lipogenesis (DNL) in pre-menopausal women. To evaluate this hypothesis, nine healthy male and nine healthy female subjects were studied after ingestion of oral loads of fructose enriched with 13C6 fructose. Incorporation of 13C into breath CO2, plasma glucose and plasma VLDL palmitate was monitored to evaluate total fructose oxidation, gluconeogenesis and hepatic DNL, respectively. Substrate oxidation was assessed by indirect calorimetry. After 13C fructose ingestion, 44·0 (sd 3·2)% of labelled carbons were recovered in plasma glucose in males v. 41·9 (sd 2·3)% in females (NS), and 42·9 (sd 3·7)% of labelled carbons were recovered in breath CO2 in males v. 43·0 (sd 4·5)% in females (NS), indicating similar gluconeogenesis from fructose and total fructose oxidation in males and females. The area under the curve for 13C VLDL palmitate tracer-to-tracee ratio was four times lower in females (P<0·05), indicating a lower DNL. Furthermore, lipid oxidation was significantly suppressed in males (by 16·4 (sd 5·2), P<0·05), but it was not suppressed in females (−1·3 (sd 4·7)%). These results support the hypothesis that females may be protected against fructose-induced hypertriglyceridaemia because of a lower stimulation of DNL and a lower suppression of lipid oxidatio

Revealing the relational mechanisms of research for development through social network analysis

Achieving impact through research for development programmes (R4D) requires engagement with diverse stakeholders across the research, development and policy divides. Understanding how such programmes support the emergence of outcomes, therefore, requires a focus on the relational aspects of engagement and collaboration. Increasingly, evaluation of large research collaborations is employing social network analysis (SNA), making use of its relational view of causation. In this paper, we use three applications of SNA within similar large R4D programmes, through our work within evaluation of three Interidsiplinary Hubs of the Global Challenges Research Fund, to explore its potential as an evaluation method. Our comparative analysis shows that SNA can uncover the structural dimensions of interactions within R4D programmes and enable learning about how networks evolve through time. We reflect on common challenges across the cases including navigating different forms of bias that result from incomplete network data, multiple interpretations across scales, and the challenges of making causal inference and related ethical dilemmas. We conclude with lessons on the methodological and operational dimensions of using SNA within monitoring, evaluation and learning (MEL) systems that aim to support both learning and accountability

Les larmes d’Héraclès: langage et émotion dans l’ode V de Bacchylide

In lyrical poet Bacchylides’s Ode 5 (first half of 5th c. BC), the mighty Heracles, a hero the classical age remembered as impassive, gets emotional and even starts weeping while listening to Meleager’s shade telling him about his own destiny. The depiction of this encounter in the Underworld uses many Homeric motifs to express an original emotion, a hero’s compassion for a stranger’s tragic fate that seems to replace self-pity, one of Homer’s heroes’ characteristics. The former emotion arises in a powerful discourse that is fraught with implications and communicates the sentiment by framing a mythological tale within a victor’s panegyric.Dans l’ode V de Bacchylide, poète lyrique de la première moitié du Ve&nbsp;siècle av.&nbsp;J.-C., le puissant Héraclès, héros réputé impassible à l’époque classique, s’émeut en écoutant le récit que l’ombre du défunt Méléagre lui fait de son propre destin, au point de se mettre à pleurer. Cette rencontre aux enfers reprend de nombreux motifs homériques pour exprimer une émotion apparemment originale&nbsp;: la compassion d’un héros devant le triste sort d’un inconnu, qui semble remplacer l’apitoiement sur soi-même des héros d’Homère. Cette émotion naît d’une parole puissante, riche d’implications, et se communique à l’auditoire de l’ode grâce à un dispositif d’enchâssement et d’échos.Nell’ode V di Bacchilide, poeta lirico della prima metà del V secolo a.C., l’eroe ritenuto impassibile all’epoca classica, il potente Eracle, si commuove ascoltando il racconto sul suo destino da parte dell’ombra di Meleagro a tal punto che l’eroe si mette a piangere. Quest’incontro negli Inferi riprende numerosi motivi omerici per esprimere un’emozione in apparenza originale: la compassione di un eroe davanti alla triste sorte di uno sconosciuto, che sembra sostituire l’autocommiserazione degli eroi omerici. Quest’emozione nasce da una parola potente, ricca di implicazioni, e si comunica al pubblico dell’ode tramite un dispositivo d’enchâssement e di echi.&nbsp

Chikungunya intra-vector dynamics in Aedes albopictus from Lyon (France) upon exposure to a human viremia-like dose range reveals vector barrier’s permissiveness and supports local epidemic potential

Arbovirus emergence and epidemic potential, as approximated by the vectorial capacity formula, depends on host and vector parameters, including the vector’s intrinsic ability to replicate then transmit the pathogen known as vector competence. Vector competence is a complex, time-dependent,quantitative phenotype influenced by biotic and abiotic factors. A combination of experimental andmodelling approaches is required to assess arbovirus intra-vector dynamics and estimate epidemicpotential. In this study, we measured infection, dissemination, and transmission dynamics of chikungunya virus (CHIKV) in a field-derived Aedes albopictus population (Lyon, France) after oral exposureto a range of virus doses spanning human viraemia. Statistical modelling indicates rapid and efficientCHIKV progression in the vector mainly due to an absence of a dissemination barrier, with 100% ofthe infected mosquitoes ultimately exhibiting a disseminated infection, regardless of the virus dose.Transmission rate data revealed a time-dependent, but overall weak, transmission barrier, with individuals transmitting as soon as 2 days post-exposure (dpe) and &gt;50% infectious mosquitoes at 6dpe for the highest dose. Based on these experimental intra-vector dynamics data, epidemiologicalsimulations conducted with an agent-based model showed that even at low mosquito biting rates,CHIKV could trigger outbreaks locally. Together, this reveals the epidemic potential of CHIKV upontransmission by Aedes albopictus in mainland Franc

Modelling the within-herd transmission of in closed pig herds.

BACKGROUND A discrete time, stochastic, compartmental model simulating the spread of within a batch of industrially raised pigs was developed to understand infection dynamics and to assess the impact of a range of husbandry practices. A 'disease severity' index was calculated based on the ratio between the cumulative numbers of acutely and chronically diseased and infectious pigs per day in each age category, divided by the length of time that pigs spent in this age category. This is equal to the number of pigs per day, either acutely or chronically infectious and diseased, divided by the number of all pigs per all days in the model. The impact of risk and protective factors at batch level was examined by adjusting 'acclimatisation of gilts', 'length of suckling period', 'vaccination of suckling pigs against ', 'contact between fattening pigs of different age during restocking of compartments' and 'co-infections in fattening pigs'. RESULTS The highest 'disease severity' was predicted, when gilts do not have contact with live animals during their acclimatisation, suckling period is 28 days, no vaccine is applied, fatteners have contact with pigs of other ages and are suffering from co-infections. Pigs in this scenario become diseased/infectious for 26.1 % of their lifetime. Logistic regression showed that vaccination of suckling pigs was influential for 'disease severity' in growers and finishers, but not in suckling and nursery pigs. Lack of contact between gilts and other live pigs during the acclimatisation significantly influenced the 'disease severity' in suckling pigs but had less impact in growing and finishing pigs. The length of the suckling period equally affected the severity of the disease in all age groups with the strongest association in nursery pigs. The contact between fatteners of different groups influenced the course of infection among finishers, but not among other pigs. Finally, presence of co-infections was relevant in growers and finishers, but not in younger pigs. CONCLUSION The developed model allows comparison of different prevention programmes and strategies for controlling transmission of