Phylogenetic and functional diverse ANME-1 thrive in Arctic hydrothermal vents.

The methane-rich areas, the Loki's Castle vent field and the Jan Mayen vent field at the Arctic Mid Ocean Ridge (AMOR), host abundant niches for anaerobic methane-oxidizers, which are predominantly filled by members of the ANME-1. In this study, we used a metagenomic-based approach that revealed the presence of phylogenetic and functional different ANME-1 subgroups at AMOR, with heterogeneous distribution. Based on a common analysis of ANME-1 genomes from AMOR and other geographic locations, we observed that AMOR subgroups clustered with a vent-specific ANME-1 group that occurs solely at vents, and with a generalist ANME-1 group, with a mixed environmental origin. Generalist ANME-1 are enriched in genes coding for stress response and defense strategies, suggesting functional diversity among AMOR subgroups. ANME-1 encode a conserved energy metabolism, indicating strong adaptation to sulfate-methane-rich sediments in marine systems, which does not however prevent global dispersion. A deep branching family named Ca. Veteromethanophagaceae was identified. The basal position of vent-related ANME-1 in phylogenomic trees suggests that ANME-1 originated at hydrothermal vents. The heterogeneous and variable physicochemical conditions present in diffuse venting areas of hydrothermal fields could have favored the diversification of ANME-1 into lineages that can tolerate geochemical and environmental variations.

Effect of human recombinant tumor necrosis factor on the growth of different human and mouse long-term hematopoietic cell lines.

Previous studies have demonstrated that one of the most salient features of tumor necrosis factor (TNF) is its ability to induce tumor necrosis in vivo, and the specificity of its cytotoxic/cytostatic activity for tumor cells has been demonstrated in in vitro studies in which this lymphokine has been shown to kill cultured cells of malignant lines and to have no effect on cells of normal diploid lines. Studies described herein defined the effect of highly purified human recombinant TNF on cells of 34 different human and murine hematopoietic cell lines, particularly human leukemic T and B cells of long-term lymphoblastoid cultures. Results of these studies demonstrated that TNF at concentrations of 3,600 U/ml had no significant effect on the growth of these cells as defined by cytotoxicity, measured with the use of the trypan blue dye-exclusion assay and as defined by cytostasis, assayed by the enumeration of cells and the uptake of [3H]-thymidine and -uridine. In contrast, positive control cultures of TNF-sensitive cells from a murine tumor (L-M/clone L-929, connective tissue) displayed at 50% (LD50) reduction in growth by TNF at approximately 5 U/ml. Likewise, human tumors (MCF-7, breast, and HT-29, colon) were also highly sensitive (LD50 less than 100 U/ml). These studies demonstrate that T and B cells of lymphoblastoid lines as well as cells of other hematopoietic lines display little or no sensitivity to TNF.

Absorption of trace metals in the zinc-deficient rat.

The effects of zinc deficiency on the whole-body absorption and intestinal content of Zn, Cd, Cu, Co, Fe, Mn, and Cr were determined in the rat 1 h after oral administration of the isotopes. Both the absorption and intestinal content of Zn and Cr were increased in zinc-deficient rats, and the intestinal content of Feand Co was also increased in the zinc-deficient animals. Zinc administered orally with Cr decreased both absorption and intestinal content of the isotope in zinc-deficient rats. Chromium administered orally with Zn decreased intestinal content and absorption of Zn in zinc-deficient rats. Fractionation of mucosal supernatants by gel filtration showed that both zinc and chromium eluted in the same low molecular weight fraction. The elution patterns of zinc and cadmium from that of zinc-supplemented animals. These experiments provide some insight into the specificity of the zinc absorption pathway and present some explanations for the interaction or lack of interaction among trace elements.