Microbiome analysis and predicted relative metabolomic turnover suggest bacterial heme and selenium metabolism are altered in the gastrointestinal system of zebrafish (Danio rerio) exposed to the organochlorine dieldrin.

Dietary exposure to chemicals alters the diversity of microbiome communities and can lead to pathophysiological changes in the gastrointestinal system. The organochlorine pesticide dieldrin is a persistent environmental contaminant that bioaccumulates in fatty tissue of aquatic organisms. The objectives of this study were to determine whether environmentally-relevant doses of dieldrin altered gastrointestinal morphology and the microbiome of zebrafish. Adult zebrafish at ∼4 months of age were fed a measured amount of feed containing either a solvent control or one of two doses of dieldrin (measured at 16, and 163.5 ng/g dry weight) for 4 months. Dieldrin body burden levels in zebrafish after four-month exposure were 0 (control), 11.47 ± 1.13 ng/g (low dose) and 18.32 ± 1.32 ng/g (high dose) wet weight [mean ± std]. Extensive histopathology at the whole organism level revealed that dieldrin exposure did not induce notable tissue pathology, including the gastrointestinal tract. A repeated measure mixed model analysis revealed that, while fish gained weight over time, there were no dieldrin-specific effects on body weight. Fecal content was collected from the gastrointestinal tract of males and 16S rRNA gene sequencing conducted. Dieldrin at a measured feed dose of 16 ng/g reduced the abundance of Firmicutes, a phylum involved in energy resorption. At the level of class, there was a decrease in abundance of Clostridia and Betaproteobacteria, and an increase in Verrucomicrobiae species. We used a computational approach called predicted relative metabolomic turnover (PRMT) to predict how a shift in microbial community composition affects exchange of metabolites. Dieldrin was predicted to affect metabolic turnover of uroporphyrinogen I and coproporphyrinogen I [enzyme]-cysteine, hydrogen selenide, selenite, and methyl-selenic acid in the fish gastrointestinal system. These pathways are related to bacterial heme biosynthesis and selenium metabolism. Our study demonstrates that dietary exposures to dieldrin can alter microbiota composition over 4 months, however the long-term consequences of such impacts are not well understood.

Antemortem Diagnosis of Coxiellosis in a Blue and Gold Macaw ( Ara ararauna).

A 15-year-old female blue and gold macaw ( Ara ararauna) was presented for evaluation after being found laterally recumbent, reluctant to move, and lethargic. Results of a complete blood count showed an increased number of immature heterophils with increased cytoplasmic basophilia and degranulation and the presence of a left shift. Radiographs and a computed tomography scan were performed and revealed a markedly enlarged spleen. An ultrasound-guided fine-needle aspirate of the spleen was submitted for cytologic examination and aerobic bacterial culture. While the culture revealed no growth, cytologic examination identified mononuclear phagocytes with cytoplasmic vacuoles containing structures consistent with bacteria. Pan-bacterial 16S rRNA polymerase chain reaction of the splenic sample followed by direct sequencing identified a Coxiella-like agent identical to one previously isolated in the liver of a golden-mantled rosella ( Platycercus eximius). Phylogenetic analysis shows that avian coxiellosis agents and Coxiella burnetii, the agent of Q fever, represent 2 independent events of development of vertebrate pathogenicity in this group of tick endosymbionts. This report suggests diagnostic and treatment directions for coxiellosis in avian patients and indicates where further study is needed.

Sexual dimorphic function of IL-17 in salivary gland dysfunction of the C57BL/6.NOD-Aec1Aec2 model of Sjögren's syndrome.

Interleukin (IL)-17 is one of the critical inflammatory cytokines that plays a direct role in development of Sjögren's syndrome (SjS), a systemic autoimmune disease characterized by a progressive chronic attack against the exocrine glands. The expression levels of IL-17 are correlated with a number of essential clinical parameters such as focus score and disease duration in human patients. Significantly immunological differences of Th17 cells were detected at the onset of clinical disease in female SjS mice compared to males. To further define the role of IL-17 in SjS and elucidate its involvement in the sexual dimorphism, we examined the systemic effect of IL-17 by genetically ablating Il-17 in the C57BL/6.NOD-Aec1Aec2, spontaneous SjS murine model. The results indicate that IL-17 is a potent inflammatory molecule in the induction of chemoattractants, cytokines, and glandular apoptosis in males and females. Elimination of IL-17 reduced sialadenitis more drastically in females than males. IL-17 is highly involved in modulating Th2 cytokines and altering autoantibody profiles which has a greater impact on changing plasma cells and germinal center B cell populations in females than males. The result supports a much more important role for IL-17 and demonstrates the sexual dimorphic function of IL-17 in SjS.

Report of wood decay fungus Inonotus tropicalis (phylum Basidiomycota) from a dog with a granulomatous mediastinal mass.

A 75.9-kg, 3.5-year-old male Irish Wolfhound dog with a 2-3-week history of gagging and eating difficulties was referred to the University of Florida Veterinary Medical Hospital (Gainesville, Florida) for evaluation of a large cranial mediastinal mass suspected to be a thymoma or lymphosarcoma. The patient had 4 months of nearly 10 kg progressive weight loss with severe flank sensitivity and radiographically apparent lumbar vertebral changes interpreted as discospondylitis. Lab work revealed hyperglobulinemia, mild proteinuria, normal T4, negative Brucella canis titer, and negative blood and urine bacterial cultures. A thoracotomy revealed a nonresectable, destructive, space-occupying mediastinal mass resulting in euthanasia without surgical recovery. Biopsies from the mass were collected during surgery for histology. Microscopic examination revealed extensive granulomatous cellulitis and lymphadenitis characterized by central cavitated necrotic areas containing debris and degenerate neutrophils, intermediate zones of fibrovascular proliferation with marked mixed inflammation, peripheral fibrosis, frequent multinucleated macrophages, and scattered mineralization. The necrotic material contained dense mats of 2 µm wide by 8-15 µm long fungal hyphae with parallel walls, acute angle branching, frequent septae, and occasional bulb-like dilations. DNA sequencing and phylogenetic analysis of the internal transcribed spacer region confirmed the presence of a fungus in the Inonotus tropicalis group. Inonotus tropicalis is primarily a wood decay fungus that is found on dead wood from angiosperms in tropical and subtropical habitats. Isolates of the I. tropicalis group have been detected a few times from immunosuppressed human beings with X-linked granulomatous disease.