CoNIC Challenge: Pushing the frontiers of nuclear detection, segmentation, classification and counting

Nuclear detection, segmentation and morphometric profiling are essential in helping us further understand the relationship between histology and patient outcome. To drive innovation in this area, we setup a community-wide challenge using the largest available dataset of its kind to assess nuclear segmentation and cellular composition. Our challenge, named CoNIC, stimulated the development of reproducible algorithms for cellular recognition with real-time result inspection on public leaderboards. We conducted an extensive post-challenge analysis based on the top-performing models using 1,658 whole-slide images of colon tissue. With around 700 million detected nuclei per model, associated features were used for dysplasia grading and survival analysis, where we demonstrated that the challenge's improvement over the previous state-of-the-art led to significant boosts in downstream performance. Our findings also suggest that eosinophils and neutrophils play an important role in the tumour microevironment. We release challenge models and WSI-level results to foster the development of further methods for biomarker discovery.

Captive Blue-and-yellow macaws (Ara ararauna) show facial indicators of positive affect when reunited with their caregiver

In mammals, human-animal bonding is recognized as a source of positive affect for companion or farm animals. Because this remains unexplored in birds, we investigated captive parrots' perspective of the human-animal relationship. We used a classical separation-reunion paradigm and predicted that variations in parrots' facial displays and behaviours would indicate their appraisal of the relationship. The test was divided into three phases of two minutes each: the bird was placed in an unfamiliar environment with a familiar caregiver (union), then the bird was left alone (separation) and finally, the caregiver returned (reunion). The test was repeated 10 times for each bird and video recorded in order to analyze their behaviour. The data show significantly higher crown and nape feather heights, higher redness of the skin and higher frequency of contact-seeking behaviours during the union and reunion phases than during the separation phase during which they expressed long distance contact calls. We observed the expression of eye pinning during the union and reunion phases in one out of five macaws. We argue that variation in facial displays provides indicators of parrot's positive appraisal of the caretaker presence. Our results broaden the scope for further studies on parrots' expression of their subjective feelings.

Seasonal remodeling of the progenitor pool and its distribution in the ewe mediobasal hypothalamus

Recent studies have reported the presence of adult neurogenesis in the arcuate nucleus periventricular space (pvARH) and in the median eminence (ME), two structures involved in reproductive function. In sheep, a seasonal mammal, decreasing daylight in autumn induces a higher neurogenic activity in these two structures. However, the different types of neural stem and progenitor cells (NSCs/NPCs) that populate the arcuate nucleus and median eminence, as well as their location, have not been evaluated. Here, using semi-automatic image analyzing processes, we identified and quantified the different populations of NSCs/NPCs, showing that, during short days, higher densities of [SOX2 +] cells are found in pvARH and ME. In the pvARH, higher densities of astrocytic and oligodendrocitic progenitors mainly contribute to these variations. The different populations of NSCs/NPCs were mapped according to their position relative to the third ventricle and their proximity to the vasculature. We showed that [SOX2 +] cells extended deeper into the hypothalamic parenchyma during short days. Similarly, [SOX2 +] cells were found further from the vasculature in the pvARH and the ME, at this time of year, indicating the existence of migratory signals. The expression levels of neuregulin transcripts (NRGs), whose proteins are known to stimulate proliferation and adult neurogenesis and to regulate progenitor migration, as well as the expression levels of ERBB mRNAs, cognate receptors for NRGs, were assessed. We showed that mRNA expression changed seasonally in pvARH and ME, suggesting that the ErbB-NRG system is potentially involved in the photoperiodic regulation of neurogenesis in seasonal adult mammals.

Seasonal vascular plasticity in the mediobasal hypothalamus of the adult ewe

Sheep, like most seasonal mammals, exhibit a cyclic adaptive reproductive physiology that allows ewes to give birth to their progeny during the spring when environmental conditions are favorable to their survival. This process relies on the detection of day length (or photoperiod) and is associated with profound changes in cellular plasticity and gene expression in the hypothalamic-pituitary-gonadal axis, mechanisms that are suggested to participate in the seasonal adaptation of neuroendocrine circuits. Recently, pituitary vascular growth has been proposed as a seasonally regulated process in which the vascular endothelial growth factor A (VEGFA), a well-known angiogenic cytokine, is suspected to play a crucial role. However, whether this mechanism is restricted to the pituitary gland or also occurs in the mediobasal hypothalamus (MBH), a crucial contributor to the control of the reproductive function, remains unexplored. Using newly developed image analysis tools, we showed that the arcuate nucleus (ARH) of the MBH exhibits an enhanced vascular density during the long photoperiod or non-breeding season, associated with higher expression of VEGFA. In the median eminence (ME), a structure connecting the MBH to the pituitary gland, higher VEGFA, kinase insert domain receptor (KDR/VEGFR2) and plasmalemma vesicle-associated protein (PLVAP) gene expressions were detected during the long photoperiod. We also found that VEGFA and its receptor, VEGFR2, are expressed by neurons and tanycytes in both the ARH and ME. Altogether, these data show variations in the MBH vasculature according to seasons potentially through a VEGFA-dependent pathway, paving the way for future studies aiming to decipher the role of these changes in the hypothalamic control of seasonal reproduction.

MALDI-TOF Mass Spectrometry Revealed Significant Lipid Variations in Follicular Fluid and Somatic Follicular Cells but Not in Enclosed Oocytes between the Large Dominant and Small Subordinate Follicles in Bovine Ovary

Lipid metabolism in ovarian follicular cells supports the preparation of an enclosed oocyte to ovulation. We aimed to compare lipid composition of a dominant large follicle (LF) and subordinated small follicles (SFs) within the same ovaries. Mass spectrometry imaging displayed the differences in the distribution of several lipid features between the different follicles. Comparison of lipid fingerprints between LF and SF by Matrix Assisted Laser Desorption/Ionisation Time-Of-Flight (MALDI-TOF) mass spectrometry revealed that in the oocytes, only 8 out of 468 detected lipids (1.7%) significantly changed their abundance (p < 0.05, fold change > 2). In contrast, follicular fluid (FF), granulosa, theca and cumulus cells demonstrated 55.5%, 14.9%, 5.3% and 9.8% of significantly varied features between LF and SF, respectively. In total, 25.2% of differential lipids were identified and indicated potential changes in membrane and signaling lipids. Tremendous changes in FF lipid composition were likely due to the stage specific secretions from somatic follicular cells that was in line with the differences observed from FF extracellular vesicles and gene expression of candidate genes in granulosa and theca cells between LF and SF. In addition, lipid storage in granulosa and theca cells varied in relation to follicular size and atresia. Differences in follicular cells lipid profiles between LF and SF may probably reflect follicle atresia degree and/or accumulation of appropriate lipids for post-ovulation processes as formation of corpus luteum. In contrast, the enclosed oocyte seems to be protected during final follicular growth, likely due in part to significant lipid transformations in surrounding cumulus cells. Therefore, the enclosed oocyte could likely keep lipid building blocks and energy resources to support further maturation and early embryo development.

Progesterone induces sperm release from oviductal epithelial cells by modifying sperm proteomics, lipidomics and membrane fluidity

The sperm reservoir is formed after insemination in mammals, allowing sperm storage in the oviduct until their release. We previously showed that physiological concentrations of progesterone (P4) trigger in vitro the sperm release from bovine oviductal epithelial cells (BOECs), selecting a subpopulation of spermatozoa with a higher fertilizing competence. Here, by using Western-Blot, confocal microscopy and Intact Cell MALDI-TOF-Mass Spectrometry strategies, we elucidated the changes derived by the P4-induced release on sperm cells (BOEC-P4 spz). Our findings show that, compared to controls, BOEC-P4 spz presented a decrease in the abundance of Binder of Sperm Proteins (BSP) -3 and -5, suggesting one mechanism by which spermatozoa may detach from BOECs, and thus triggering the membrane remodeling with an increase of the sperm membrane fluidity. Furthermore, an interesting number of membrane lipids and proteins were differentially abundant in BOEC-P4 spz compared with controls.

Facial display and blushing: Means of visual communication in blue-and-yellow macaws (Ara Ararauna)?

Mainly recognized for their cognitive performance, the visual communication system and, particularly, the potential function of facial displays in parrots remain thus far unexplored. Here, we provide the first descriptive study of facial display use in captive blue-and-yellow macaws. We observed the feather position (sleeked or ruffled) on the crown, nape and cheek at the group level during the macaws' daily routine and individually while interacting with a familiar animal caretaker. In the latter context, blushing was also assessed on the bare skin of the cheek. Group level observations showed that crown, nape and cheek feathers ruffling was more frequent in activities requiring no locomotion than in activities requiring locomotion. With the animal caretaker, crown ruffling was significantly more frequent when the caretaker was actively engaging with the parrot than during a control phase with no mutual interaction. In addition, a significantly higher proportion of naïve observers judged blushing as being present on photographs taken during the mutual interaction phase than during the control phase. We thus showed significant variations in facial displays and bare skin colour based on the birds' social context and activity. Our results broaden the scope for further studies to determine whether parrots' faces provide visual social signals.

Are there facial indicators of positive emotions in birds? A first exploration in Japanese quail

The positive aspect of emotions, like pleasure, remains overlooked in birds. Our aim was to contribute to the exploration of facial indicators of positive emotions. To observe contrasting emotional expressions, we used two lines of Japanese quail divergently selected on their inherent fearfulness: a fearful line (long tonic immobility duration: LTI) and a less fearful line (short tonic immobility duration: STI). To induce positive emotions, we gave individual quail the opportunity to perform a rewarding behaviour, dustbathing, in an unfamiliar cage. More STI than LTI quail expressed dustbathing and latencies to dustbathe were significantly shorter in STI than LTI quail. This result indicated that the lines of quail differed in their fearfulness of the situation. We observed crown feather height, throat feather angle and pupil surface before (control) and during dustbathing. We found significant increases in crown feather height, pupil area and angle of throat feathers between the control and the dustbathing phases in STI quail, and pupil area correlated positively with crown feather height. In LTI quail, the angle of throat feathers increased during dustbathing, but the other parameters did not differ. We argue that variation in crown feather height and pupil area may provide indications of positive emotions in Japanese quail.

G protein-dependent signaling triggers a β-arrestin-scaffolded p70S6K/ rpS6 module that controls 5'TOP mRNA translation

Many interaction partners of β-arrestins intervene in the control of mRNA translation. However, how β-arrestins regulate this cellular process has been poorly explored. In this study, we show that β-arrestins constitutively assemble a p70S6K/ribosomal protein S6 (rpS6) complex in HEK293 cells and in primary Sertoli cells of the testis. We demonstrate that this interaction is direct, and experimentally validate the interaction interface between β-arrestin 1 and p70S6K predicted by our docking algorithm. Like most GPCRs, the biological function of follicle-stimulating hormone receptor (FSHR) is transduced by G proteins and β-arrestins. Upon follicle-stimulating hormone (FSH) stimulation, activation of G protein-dependent signaling enhances p70S6K activity within the β-arrestin/p70S6K/rpS6 preassembled complex, which is not recruited to the FSHR. In agreement, FSH-induced rpS6 phosphorylation within the β-arrestin scaffold was decreased in cells depleted of Gα_s. Integration of the cooperative action of β-arrestin and G proteins led to the translation of 5' oligopyrimidine track mRNA with high efficacy within minutes of FSH input. Hence, this work highlights new relationships between G proteins and β-arrestins when acting cooperatively on a common signaling pathway, contrasting with their previously shown parallel action on the ERK MAP kinase pathway. In addition, this study provides insights into how GPCR can exert trophic effects in the cell.-Tréfier, A., Musnier, A., Landomiel, F., Bourquard, T., Boulo, T., Ayoub, M. A., León, K., Bruneau, G., Chevalier, M., Durand, G., Blache, M.-C., Inoue, A., Fontaine, J., Gauthier, C., Tesseraud, S., Reiter, E., Poupon, A., Crépieux, P. G protein-dependent signaling triggers a β-arrestin-scaffolded p70S6K/ rpS6 module that controls 5'TOP mRNA translation.

Steroid hormones regulate sperm-oviduct interactions in the bovine

After insemination in the cow, a sperm reservoir is formed within the oviducts, allowing the storage and then progressive release of spermatozoa toward the ovulated oocyte. In order to investigate the hormonal regulation of these events in vitro, the ovarian steroids 17β-estradiol (E2) and progesterone (P4) were added at various concentrations to monolayers of bovine oviduct epithelial cells (BOEC) before or during co-incubation with spermatozoa. Main findings demonstrate that (1) a 18-h pretreatment of BOEC with 100 pg/mL and 100 ng/mL of E2 decreased by 25% the ability of BOEC to bind spermatozoa after 10 min, and for the highest dose of E2, 60 min of co-incubation; (2) P4 at concentrations of 10, 100 and 1000 ng/mL induced the release within 60 min of 32-47% of bound spermatozoa from BOEC; this sperm-releasing effect was maintained after a 18-h pretreatment of BOEC with 100 pg/mL of E2; (3) E2 in concentrations above 100 pg/mL inhibited the releasing effect of P4 on bound sperm in a dose-dependent manner; (4) spermatozoa bound to BOEC, then released from BOEC by the action of P4-induced higher cleavage and blastocyst rates after in vitro fertilization than the control group. These results support the hypothesis that the dynamic changes in steroid hormones around the time of ovulation regulate the formation of the sperm reservoir and the timed delivery of capacitated spermatozoa to the site of fertilization.

Versatile cellular uptake mediated by catanionic vesicles: simultaneous spontaneous membrane fusion and endocytosis

Lactose-derived catanionic vesicles offer unique opportunities to overcome cellular barriers. These potential nanovectors, very easy to formulate as drug delivery systems, are able to encapsulate drugs of various hydrophilicity. This article highlights versatile interaction mechanisms between these catanionic vesicles, labeled with hydrophilic and amphiphilic fluorescent probes, and a mammalian cell line, Chinese Hamster Ovary. Confocal microscopy and flow cytometry techniques show that these vesicles are internalized by cells through cellular energy dependent processes, as endocytosis, but are simultaneously able to spontaneously fuse with cell plasma membranes and release their hydrophilic content directly inside the cytosol. Such innovative and polyvalent nanovectors, able to deliver their content via different internalization pathways, would positively be a great progress for the coadministration of drugs of complementary efficiency.

Giant lipid vesicles under electric field pulses assessed by non invasive imaging

We present experimental results regarding the effects of electric pulses on giant unilamellar vesicles (GUVs). We have used phase contrast and coherent anti-Stokes Raman scattering (CARS) microscopy as relevant optical approaches to gain insight into membrane changes under electropermeabilization. No addition of exogenous molecules (lipid analogue, fluorescent dye) was needed. Therefore, experiments were performed on pure lipid systems avoiding possible artefacts linked to their use. Structural membrane changes were assessed by loss of contrast inside the GUVs due to sucrose and glucose mixing. Our observations, performed at the single vesicle level, indicate these changes are under the control of the number of pulses and field intensity. Larger number of pulses enhances membrane alterations. A threshold value of the field intensity must be applied to allow exchange of molecules between GUVs and the external medium. This threshold depends on the size of the vesicles, the larger GUVs being affected at lower electric field strengths than the smaller ones. Our experimental data are well described by a simple model in which molecule entry is driven by direct exchange. The CARS microscopic study of the effect of pulse duration confirms that pulses, in the ms time range, induce loss of lipids and membrane deformations facing the electrodes.