Comparison of the gut microbiota of captive common bottlenose dolphins Tursiops truncatus in three aquaria.

AIMS: This study was conducted to assess the presence and extent of differences in the gut microbiota of common bottlenose dolphins depending on rearing facilities. METHODS AND RESULTS: Faecal samples were collected from 16 common bottlenose dolphins at three aquaria in Japan. After extracting DNA from the faeces, the V3-V4 region of bacterial 16S rRNA was amplified and sequenced using Illumina MiSeq platform. The constituent phyla of the gut microbiota were similar among aquaria; however, the most dominant phylum differed depending on the facility, and the compositions of microbiota were remarkably varied at the family level among aquaria. The alpha diversity indices tended to differ among aquaria. Some bacterial families observed in terrestrial mammalian carnivores or carnivorous fish were detected, as well as several bacterial species suspected of being pathogenic in dolphins. CONCLUSION: Our findings indicate that captive environmental conditions including prey and housing types may contribute to differences in the gut microbiota of the dolphins. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study revealing the differences in gut microbiota of captive dolphins among facilities. Our findings will provide valuable information for improving the health management of dolphins.

Surfactant protein D suppresses lung cancer progression by downregulation of epidermal growth factor signaling.

Surfactant protein D (SP-D) is a member of the collectin family that has an important role in maintaining pulmonary homeostasis. In this study, we demonstrated that SP-D inhibited the proliferation, migration and invasion of A549 human lung adenocarcinoma cells. We found that SP-D suppressed epidermal growth factor (EGF) signaling in A549 cells, H441 human lung adenocarcinoma cells and human EGF receptor (EGFR) stable expression CHO-K1 cells. A binding study using (125)I-EGF demonstrated that SP-D downregulated the binding of EGF to EGFR. A ligand blot indicated that SP-D bound to EGFR, and a lectin blot suggested that EGFR in A549 cells had both high-mannose type and complex type N-glycans. We purified the recombinant extracellular domain of EGFR (soluble EGFR=soluble EGFR (sEGFR)), and demonstrated that SP-D directly bound to sEGFR in a Ca(2+)-dependent manner. The binding of SP-D to sEGFR was suppressed by EDTA, mannose or N-glycopeptidase F treatment. Mass spectrometric analysis indicated that N-glycans in domain III of EGFR were of a high-mannose type. These data suggest that SP-D reduces EGF binding to EGFR through the interaction between the carbohydrate recognition domain of SP-D and N-glycans of EGFR, and downregulates EGF signaling. Our finding suggests the novel type of regulation system of EGF signaling involving lectin-to-carbohydrate interaction and downregulation of ligand binding.

Genetic mapping of genes for susceptibility to black spot disease in Japanese pears.

Black spot disease, which is caused by the Japanese pear pathotype of Alternaria alternata (Fr.) Keissler, is one of the most harmful diseases in Japanese pear cultivation. We identified the exact positions and linkage groups (LGs) of the genes for susceptibility to black spot in the Japanese pear (Pyrus pyrifolia Nakai) cultivars 'Osa Nijisseiki' (gene Ani) and 'Nansui' (gene Ana). Segregation of susceptibility and resistance fitted the expected ratio of 1:1 in progeny of 'Nansui' but showed a slight distortion in progeny of 'Osa Nijisseiki'. We mapped the genes for susceptibility to black spot in both populations using a genome scanning approach. The simple sequence repeat (SSR) markers CH04h02 and CH03d02 showed tight linkage to Ani and Ana. Although Ani and Ana are derived from different sources, both genes are located at the top region of LG 11. Information about the positions of the susceptibility genes and the molecular markers linked to them will be useful for marker-assisted selection in pear breeding programs.

Primary phloem-specific expression of a Zinnia elegans homeobox gene.

Some plant homeobox genes are expressed specifically in vascular cells and are assumed to function in the differentiation of specific types of vascular cells. However, homeobox genes exhibiting primary phloem-specific expression have not been reported. To elucidate the molecular mechanisms of vascular development, we undertook to isolate from Zinnia elegans primary phloem-specific homeobox genes that may function in phloem development. An HD-Zip type homeobox gene, ZeHB3, was isolated. This gene encodes a class I HD-Zip protein, and constitutes a gene subfamily with the Daucus carota gene CHB6, and Arabidopsis thaliana genes Athb-5, Athb-6, and Athb-16. In situ hybridization of 1-, 14- and 50-day-old plants demonstrated that ZeHB3 mRNA accumulation is restricted to a few cells destined to differentiate into phloem cells and to the immature phloem cells surrounding the sieve elements and companion cells. ZeHB3 protein was also localized to immature phloem cells. These findings clearly indicate that ZeHB3 is a novel homeobox gene that marks, and may function in, the early stages of phloem differentiation.

Heme mediates derepression of Maf recognition element through direct binding to transcription repressor Bach1.

Heme controls expression of genes involved in the synthesis of globins and heme. The mammalian transcription factor Bach1 functions as a repressor of the Maf recognition element (MARE) by forming antagonizing hetero-oligomers with the small Maf family proteins. We show here that heme binds specifically to Bach1 and regulates its DNA-binding activity. Deletion studies demonstrated that a heme-binding region of Bach1 is confined within its C-terminal region that possesses four dipeptide cysteine-proline (CP) motifs. Mutations in all of the CP motifs of Bach1 abolished its interaction with heme. The DNA-binding activity of Bach1 as a MafK hetero-oligomer was markedly inhibited by heme in gel mobility shift assays. The repressor activity of Bach1 was lost upon addition of hemin in transfected cells. These results suggest that increased levels of heme inactivate the repressor Bach1, resulting in induction of a host of genes with MARES:

Molecular analysis of delta-aminolevulinate dehydratase deficiency in a patient with an unusual late-onset porphyria.

Cloning, expression, and genotype studies of the defective gene for delta-aminolevulinate dehydratase (ALAD) in a patient with an unusual late onset of ALAD deficiency porphyria (ADP) were carried out. This patient was unique in that he developed the inherited disease, together with polycythemia, at the age of 63. ALAD activity in erythrocytes of the patient was less than 1% of the normal control level. ALAD complementary DNA (cDNA) isolated from the patient's Epstein-Barr virus (EBV)-transformed lymphoblastoid cells had 2 base transitions in the same allele, G(177) to C and G(397) to A, resulting in amino acid substitutions K59N and G133R, respectively. It has been verified that the patient had no other ALAD mutations in this and in the other allele. By restriction fragment length polymorphism (RFLP) analysis, all family members of the proband who had one-half ALAD activity compared with the ALAD activity of the healthy control were shown to have the same set of base transitions. Expression of ALAD cDNA in CHO cells revealed that K59N cDNA produced a protein with normal ALAD activity, while G133R and K59N/G133R cDNA produced proteins with 8% and 16% ALAD activity, respectively, compared with that expressed by the wild type cDNA. These findings indicate that while the proband was heterozygous for ALAD deficiency, the G(397) to A transition resulting in the G133R substitution is responsible for ADP, and the clinical porphyria developed presumably due to an expansion of the polycythemic clone in erythrocytes that carried the mutant alad allele.