The Role of Geography, Diet, and Host Phylogeny on the Gut Microbiome in the Hawaiian Honeycreeper Radiation.

The animal gut microbiome can have a strong influence on the health, fitness, and behavior of its hosts. The composition of the gut microbial community can be influenced by factors such as diet, environment, and evolutionary history (phylosymbiosis). However, the relative influence of these factors is unknown in most bird species. Furthermore, phylosymbiosis studies have largely focused on clades that diverged tens of millions of years ago, and little is known about the degree of gut microbiome divergence in more recent species radiations. This study explores the drivers of microbiome variation across the unique and recent Hawaiian honeycreeper radiation (Fringillidae: Drepanidinae). Fecal samples were collected from 14 extant species spanning the main islands of the Hawaiian archipelago and were sequenced using three metabarcoding markers to characterize the gut microbiome, invertebrate diet, and plant diet of Hawaiian honeycreepers. We then used these metabarcoding data and the honeycreeper host phylogeny to evaluate their relative roles in shaping the gut microbiome. Microbiome variation across birds was highly individualized; however, source island had a small but significant effect on microbiome structure. The microbiomes did not recapitulate the host phylogenetic tree, indicating that evolutionary history does not strongly influence microbiome structure in the honeycreeper clade. These results expand our understanding of the roles of diet, geography, and phylogeny on avian microbiome structure, while also providing important ecological information about the diet and gut microbiota of wild Hawaiian honeycreepers.

Wild gut microbiomes reveal individuals, species, and location as drivers of variation in two critically endangered Hawaiian honeycreepers.

BACKGROUND: The gut microbiome of animals is an important component that has strong influence on the health, fitness, and behavior of its host. Most research in the microbiome field has focused on human populations and commercially important species. However, researchers are now considering the link between endangered species conservation and the microbiome. In Hawai'i, several threats (e.g., avian malaria and habitat loss) have caused widespread population declines of Hawaiian honeycreepers (subfamily: Carduelinae). These threats can have a significant effect on the avian gut microbiome and may even lead to disruption of microbial function. However, the gut microbiome of honeycreeper in the wild has yet to be explored. METHODS: We collected 13 and 42 fecal samples, respectively, from two critically endangered honeycreeper species, the 'akikiki (Oreomystis bairdi) and the 'akeke'e (Loxops caeruleirostris). The 16S rRNA gene was sequenced and processed though a MOTHUR-based bioinformatics pipeline. Bacterial ASVs were identified using the DADA2 program and bacterial community analyses, including alpha and beta diversity measures, were conducted using R packages Phyloseq and vegan. RESULTS: A total of 8,958 bacterial ASVs were identified from the fecal samples. Intraspecific differences in the gut microbiome among individual birds explained most of the variation present in the dataset, however differences between species did exist. Both species had distinct microbiomes with minimal overlap in beta diversity. 'Akikiki had a more diverse microbiome compared to 'akeke'e. Additionally, small but stastically significant differences in beta diversity also exist between sampling location and sexes in 'akikiki. CONCLUSION: 'Akikiki and 'akeke'e are currently the focus of captive breeding efforts and plans to translocate the two species to other islands are underway. This baseline knowledge will help inform management decisions for these honeycreeper species in their native habitats, on other islands, and in captivity.

Plant part and a steep environmental gradient predict plant microbial composition in a tropical watershed.

Plant microbiomes are shaped by forces working at different spatial scales. Environmental factors determine a pool of potential symbionts while host physiochemical factors influence how those microbes associate with distinct plant tissues. These scales are seldom considered simultaneously, despite their potential to interact. Here, we analyze epiphytic microbes from nine Hibiscus tiliaceus trees across a steep, but short, environmental gradient within a single Hawaiian watershed. At each location, we sampled eight microhabitats: leaves, petioles, axils, stems, roots, and litter from the plant, as well as surrounding air and soil. The composition of bacterial communities is better explained by microhabitat, while location better predicted compositional variance for fungi. Fungal community compositional dissimilarity increased more rapidly along the gradient than did bacterial composition. Additionally, the rates of fungal community compositional dissimilarity along the gradient differed among plant parts, and these differences influenced the distribution patterns and range size of individual taxa. Within plants, microbes were compositionally nested such that aboveground communities contained a subset of the diversity found belowground. Our findings indicate that both environmental context and microhabitat contribute to microbial compositional variance in our study, but that these contributions are influenced by the domain of microbe and the specific microhabitat in question, suggesting a complicated and potentially interacting dynamic.

Primer estudio epidemiológico de injuria renal aguda con requerimiento de terapia de reemplazo renal en argentina. sobrevida general y renal a mediano plazo / First epidemiological study of acute kidney injury with requirement of renal replacement therapy in argentina. intermediate general and renal survival

Resumen Introducción: La injuria renal aguda es un trastorno complejo, multicausal, asociado con alta mortalidad y ocasional dependencia de diálisis crónica. Se desconoce la evolución de los pacientes que requieren terapia de reemplazo renal por injuria renal aguda en Argentina. Material y métodos: Estudio prospectivo, observacional, longitudinal y multicéntrico, en mayores de 14 años, ingresados en hospitales públicos de la provincia de Santa Fe, con diagnóstico de injuria renal aguda y necesidad de terapia de reemplazo renal, durante dos años (2017 y 2018). Resultados: Total 255 pacientes. Frecuencia 164 ppm/año, 1.85/1000 internaciones por año, varones 70,98%, edad 46-66 años, comorbilidades en 71,37%, internación en unidad de cuidados críticos 89.02%, compromiso extrarrenal 82.52%. Causas más frecuentes: hipotensión arterial 62.35%, infecciones 52.73%, nefrotóxicos 17.65%. Terapia de reemplazo renal: hemodiálisis intermitente 74.51%, diálisis lenta 11.76%, terapia continua 13.73%. Evolución: vivos a 30 días 116 (45.49%), dependencia de diálisis crónica 12 (10.34%). Mortalidad: 54.51% a 30 días, progresando al 65.88% a los 420 días. Sin diferencia significativa en mortalidad a 30 días según edad, sexo, terapia de reemplazo renal, comorbilidades ni creatininemia en primera diálisis. Hubo diferencia significativa (p <0.05) en mortalidad en injuria renal aguda aislada versus compromiso extrarrenal (RR: 1.55), Unidad de Cuidados Críticos versus Sala (RR: 3.31) e hipotensión arterial (RR: 1.79) como causa. Los pacientes con dependencia de diálisis crónica presentaron mayor mortalidad a 420 días que aquellos que recuperaron función renal (50% vs 22%, RR: 2.26). Conclusiones: Este es el primer estudio epidemiológico de injuria renal aguda, con seguimiento de la población que requirió terapia de reemplazo renal en Argentina. Está compuesto por pacientes jóvenes, graves y con alta proporción de compromiso de órganos extrarrenales. La mortalidad es elevada y se prolonga más allá del inicio de la terapia de reemplazo renal, la dependencia de diálisis crónica conlleva un peor pronóstico vital.

Abstract Introduction: Acute kidney injury is a complex, multicausal disorder associated with high mortality and chronic dialysis dependence. The evolution of patients who required renal replacement therapy due to acute kidney injury in Argentina is unknown. Methods: Prospective, observational, longitudinal, multicentric study in individuals over 14 years of age admitted to public hospitals (Province of Santa Fe) with a diagnosis of acute kidney injury and need for renal replacement therapy; study duration: two years (2017 and 2018). Results: Total 255 patients. Frequency 164 ppm/year, 1.85/1000 hospitalizations/year, males 70.98%, age 46.66 years, comorbidities present in 71.37%, hospitalization in critical care 89.02%, extra renal involvement 82.52%. Most frequent causes: arterial hypotension 62.35%, infections 52.73%, nephrotoxic 17.65%. Renal replacement therapy: intermittent hemodialysis 74.51%, sustained low-efficiency dialysis 11.76%, continuous: 13.73%. Evolution: alive at 30 days 116 (45.49%), chronic dialysis dependence 12 (10.34%). Mortality: at 30 days 54.51%, progressing to 65.88% at 420 days. No significant difference in mortality at 30 days according to age, sex, renal replacement therapy, comorbidities or creatinine in first dialysis. There was a significant difference (p <0.05) in mortality in isolated acute renal injury extra renal involvement (RR: 1.55), Critical Care Unit vs Ward (RR: 3.31) and arterial hypotension as cause (RR: 1.79). Patients with chronic dialysis dependence presented higher mortality than those who recovered renal function (50% vs 22%, RR: 2.26). Conclusions: This is the first epidemiological study with follow-up of the population that required renal replacement therapy in Argentina. It is composed of young, severe patients with a high proportion of extra renal organ involvement. Mortality is high and continues beyond the onset of renal replacement therapy, chronic dialysis dependence leads to a worse vital prognosis.