Discovery of New Hydrothermal Activity and Chemosynthetic Fauna on the Central Indian Ridge at 18°–20°S

Indian Ocean hydrothermal vents are believed to represent a novel biogeographic province, and are host to many novel genera and families of animals, potentially indigenous to Indian Ocean hydrothermal systems. In particular, since its discovery in 2001, much attention has been paid to a so-called ‘scaly-foot’ gastropod because of its unique iron-sulfide-coated dermal sclerites and the chemosynthetic symbioses in its various tissues. Despite increasing interest in the faunal assemblages at Indian Ocean hydrothermal vents, only two hydrothermal vent fields have been investigated in the Indian Ocean. Here we report two newly discovered hydrothermal vent fields, the Dodo and Solitaire fields, which are located in the Central Indian Ridge (CIR) segments 16 and 15, respectively. Chemosynthetic faunal communities at the Dodo field are emaciated in size and composition. In contrast, at the Solitaire field, we observed faunal communities that potentially contained almost all genera found at CIR hydrothermal environments to date, and even identified previously unreported taxa. Moreover, a new morphotype of ‘scaly-foot’ gastropod has been found at the Solitaire field. The newly discovered ‘scaly-foot’ gastropod has similar morphological and anatomical features to the previously reported type that inhabits the Kairei field, and both types of ‘scaly-foot’ gastropods genetically belong to the same species according to analyses of their COI gene and nuclear SSU rRNA gene sequences. However, the new morphotype completely lacks an iron-sulfide coating on the sclerites, which had been believed to be a novel feature restricted to ‘scaly-foot’ gastropods. Our new findings at the two newly discovered hydrothermal vent sites provide important insights into the biodiversity and biogeography of vent-endemic ecosystems in the Indian Ocean

Efficacy of nivolumab plus ipilimumab as first-line therapy for primary tumors in patients with renal cell carcinoma

Objectives: With the emergence of several effective combination therapies, information on their effects at the primary site will be crucial for planning future cytoreductive nephrectomy (CN). The present study focused exclusively on changes in primary tumor sizes following treatment with nivolumab plus ipilimumab and investigated the clinical factors associated with a good response in primary tumors. Methods and materials: We retrospectively assessed 27 patients diagnosed with advanced renal cell carcinoma (RCC) who started treatment with nivolumab plus ipilimumab. Changes in tumor sizes at the primary site were described using waterfall and spider plots, respectively. We analyzed the correlation of tumor shrinkage between primary and metastatic site. The parameters analyzed between responders and non-responders according to primary tumor sizes were International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk scores, peripheral blood markers, and CRP. Results: The median age and follow-up period were 66 years and 9.3 months, respectively. The median IMDC risk score was 3 (range: 1-6). Nineteen patients were diagnosed with clear-cell RCC (ccRCC) and 8 patients with non-ccRCC. Among ccRCC patients, 9 (47.4%) achieved a significant response with a maximum reduction of 30% or more in the size of the primary tumor from baseline within 4 months, while 3 (37.5%) out of 8 patients with non-ccRCC achieved a significant response. Shrinkage of the primary tumor correlated with the metastatic tumors in both ccRCC and non-ccRCC cases. Of note, 6 patients underwent CN and no viable tumor cells were detected in the surgical specimens of 3 patients whose primary tumors shrank by approximately 50%-60% with a reduction to 4 cm or less. Among ccRCC patients, the neutrophil-to-lymphocyte ratio and monocyte-to-lymphocyte ratio were slightly lower in responders than in non-responders (P = 0.0944 and P = 0.0691). The platelet-to-lymphocyte ratio was significantly lower in responders than in non-responder (P = 0.0391). Conclusions: Significant responses in primary tumors to nivolumab plus ipilimumab were observed in 50% of ccRCC patients, while responses varied among non-ccRCC patients. Inflammation markers may be predictive factors of treatment responses in primary tumors. Although further studies are needed, the present results suggest the importance of considering CN from radiological and pathological viewpoints. (C) 2021 The Authors. Published by Elsevier Inc

Chemical compositions of hydrothermal fluids from the Dodo and Solitaire hydrothermal fields.

<p>(A) Chlorine and (B) H₂ concentrations are plotted against average fluid temperature during each sampling. Blue open circles with dashed lines and red open squares with dotted lines represent the Dodo and Solitaire fluids, respectively. Gray horizontal line in (A) indicates seawater level (560 mmol/kg).</p

Photographs of macromorphology and of microscopic and SEM-EDS analyses of sclerites from the two morphotypes of ‘scaly-foot’ gastropods.

<p>(A), (B) Photographs of the two morphotypes of ‘scaly-foot’ gastropods. Bar indicates 1 cm. (C), (F) Optical micrographs of the polished surface of the sclerite sections. (D), (G) Elemental mapping of iron in the same sections by SEM-EDS. (E), (H) Elemental mapping of sulfur by SEM-EDS. The black-white-green colors indicate the intensity of each element.</p

List of the observed and/or sampled animals in the Dodo and Solitaire fields.

<p>List of the observed and/or sampled animals in the Dodo and Solitaire fields.</p

Comparison of stress of both sclerites obtained from three-point bending test.

<p>Comparison of stress of both sclerites obtained from three-point bending test.</p

Morphological differences in the vestigial opercula of ‘scaly-foot’ gastropods.

<p>(A) Dorsal surface of the operculum of a juvenile individual. (B) Dorsal surface of the operculum of an adult individual. (C) Outer surface of the sclerite of an adult individual. (D) Ventral surface of the operculum of a juvenile individual. (E) Ventral surface of an adult individual. (F) Inner surface of the sclerite of an adult individual. Scale bar indicates 1 mm.</p