Vibrio coralliilyticus infection triggers a behavioural response and perturbs nutritional exchange and tissue integrity in a symbiotic coral

Under homoeostatic conditions, the relationship between the coralPocillopora damicornisandVibrio coralliilyticusiscommensal. An increase in temperature, or in the abundance ofV. coralliilyticus, can turn this association pathogenic,causing tissue lysis, expulsion of the corals’symbiotic algae (genusSymbiodinium), and eventually coral death. Using acombination of microfluidics,fluorescence microscopy, stable isotopes, electron microscopy and NanoSIMS isotopicimaging, we provide insights into the onset and progression ofV.coralliilyticusinfection in the daytime and at night, atthe tissue and (sub-)cellular level. The objective of our study was to connect the macro-scale behavioural response ofthe coral to the micro-scale nutritional interactions that occur between the host and its symbiont. In the daytime, polypsenhanced their mucus production, and actively spewed pathogens.Vibrioinfection primarily resulted in the formationof tissue lesions in the coenosarc. NanoSIMS analysis revealed infection reduced13C-assimilation inSymbiodinium, butincreased13C-assimilation in the host. In the night incubations, no mucus spewing was observed, and a mucusfilm wasformed on the coral surface.Vibrioinoculation and infection at night showed reduced13C-turnover inSymbiodinium, but didnot impact host13C-turnover. Our results show that both the nutritional interactions that occur between the two symbioticpartners and the behavioural response of the host organism play key roles in determining the progression and severity ofhost-pathogen interactions. More generally, our approach provides a new means of studying interactions (ranging frombehavioural to metabolic scales) between partners involved in complex holobiont systems, under both homoeostatic andpathogenic conditions

Inflammatory markers predict insulin sensitivity in active rheumatoid arthritis but not in psoriatic arthritis

Whether the insulin resistance commonly observed in patients with inflammatory arthritis is a disease-specific feature and/or is limited to a disease phase (i.e., it occurs only during phases of high disease activity) is unknown. Fifty-three rheumatoid arthritis (RA) and 44 psoriatic arthritis (PsA) patients were recruited consecutively along with 194 controls matched for age, sex and body mass index for a case-control study. All underwent an oral glucose tolerance test, the results of which were analysed to derive the following indexes: homeostatic model of insulin resistance (HOMA-IR), insulin sensitivity index (ISI) and early insulin sensitivity index (EISI). These data were related to anthropometric, clinical and laboratory findings. Metabolic parameters of patients and controls were similar. Neither inflammatory markers nor disease activity scores were related to glucose metabolism for the generality of RA and PsA patients; however, by restricting the analysis to the subset of RA patients with residual disease activity, an association emerged between erythrocyte sedimentation rate, on the one hand, and fasting insulin (β=0.46, p=0.047) and HOMA-IR (β=0.44, p=0.02), on the other. Moreover, C-reactive protein (CRP) levels were associated with plasma glucose and insulin levels measured 120 min after the glucose load (β=0.91, p=0.0003 and β=0.77, p=0.0006, respectively); ISI and EISI were predicted by CRP (β=-0.79, p=0.0006; β=-0.80, p=0.0001, respectively). The same did not hold true for PsA patients. The association between systemic inflammation and insulin resistance indexes is a feature of RA with residual disease activity, not a universal feature of inflammatory arthritides

Use of vocalic information in the identification of /s/ and /sh/ by children with cochlear implants

Objective: When a syllable such as "sea" or "she" is spoken, listeners with normal hearing extract evidence of the fricative consonant from both the fricative noise and the following vocalic segment. If the fricative noise is made ambiguous, listeners may still perceive "s" or "sh" categorically, depending on information in the vocalic segment. Do children whose auditory experience comes from electrical stimulation also display this effect, in which a subsequent segment of speech disambiguates an earlier segment? Design: Unambiguous vowels were appended to ambiguous fricative noises to form tokens of the words "she," "sea," "shoe," and "Sue." A four-choice identification test was undertaken by children with normal hearing (N = 29), prelingually deaf children with the Nucleus Spectra-22 implant system using the SPEAK coding strategy (N = 13), postlingually deafened adults with the same implant system (N = 26), and adults with normal hearing (N = 10). The last group undertook the test before and after the stimuli were processed to simulate the transformations introduced by the SPEAK coding strategy. Results: All four groups made use of vocalic information. Simulated processing reduced the use made by normal-hearing adults. Implanted subjects made less use than the other groups, with no significant difference between implanted children and implanted adults. The highest levels of use by implanted subjects were within one standard deviation of the mean level displayed when normal-hearing adults listened to processed stimuli. Analyses showed that the SPEAK strategy distorted formant contours in the vocalic segments of the stimuli in ways that are compatible with the errors of identification made by implanted subjects. Conclusions: Some children with implants can extract information from a following vowel to disambiguate a preceding fricative noise. The upper limit on this ability may be set by distortions introduced by the implant processor, rather than by the auditory experience of the child

Metabolic fluxes and chemical signaling during coral disease at the single cell-level.

Metabolic fluxes and chemical signaling during coral disease at the single cell-level

Using NanoSIMS coupled with microfluidics to visualize the early stages of coral infection by Vibrio coralliilyticus

Abstract Background Global warming has triggered an increase in the prevalence and severity of coral disease, yet little is known about coral/pathogen interactions in the early stages of infection. The point of entry of the pathogen and the route that they take once inside the polyp is currently unknown, as is the coral’s capacity to respond to infection. To address these questions, we developed a novel method that combines stable isotope labelling and microfluidics with transmission electron microscopy (TEM) and nanoscale secondary ion mass spectrometry (NanoSIMS), to monitor the infection process between Pocillopora damicornis and Vibrio coralliilyticus under elevated temperature. Results Three coral fragments were inoculated with 15N-labeled V. coralliilyticus and then fixed at 2.5, 6 and 22 h post-inoculation (hpi) according to the virulence of the infection. Correlative TEM/NanoSIMS imaging was subsequently used to visualize the penetration and dispersal of V. coralliilyticus and their degradation or secretion products. Most of the V. coralliilyticus cells we observed were located in the oral epidermis of the fragment that experienced the most virulent infection (2.5 hpi). In some cases, these bacteria were enclosed within electron dense host-derived intracellular vesicles. 15N-enriched pathogen-derived breakdown products were visible in all tissue layers of the coral polyp (oral epidermis, oral gastrodermis, aboral gastrodermis), at all time points, although the relative 15N-enrichment depended on the time at which the corals were fixed. Tissues in the mesentery filaments had the highest density of 15N-enriched hotspots, suggesting these tissues act as a “collection and digestion” site for pathogenic bacteria. Closer examination of the sub-cellular structures associated with these 15N-hotspots revealed these to be host phagosomal and secretory cells/vesicles. Conclusions This study provides a novel method for tracking bacterial infection dynamics at the levels of the tissue and single cell and takes the first steps towards understanding the complexities of infection at the microscale, which is a crucial step towards understanding how corals will fare under global warming