A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

A Direct Screening Procedure for Gravitropism Mutants in Arabidopsis thaliana (L.) Heynh.

In order to isolate gravitropism mutants of Arabidopsis thaliana (L.) Heynh. var Estland for the genetic dissection of the gravitropism pathway, a direct screening procedure has been developed in which mutants are selected on the basis of their gravitropic response. Variability in hypocotyl curvature was dependent on the germination time of each seed stock, resulting in the incorrect identification of several lines as gravitropism mutants when a standard protocol for the potentiation of germination was used. When the protocol was adjusted to allow for differences in germination time, these lines were eliminated from the collection. Out of the 60,000 M2 seedlings screened, 0.3 to 0.4% exhibited altered gravitropism. In approximately 40% of these mutant lines, only gravitropism by the root or the hypocotyl was altered, while the response of the other organ was unaffected. These data support the hypothesis that root and hypocotyl gravitropism are genetically separable.     

Analysis of genome-specific sequences inPhleum species: Identification and use for study of genomic relationships

Sau3AI shot gun cloning and colony hybridization with total genomic probes were used to isolate genome-specific sequences inPhleum species. The total DNA isolated from diploid speciesP. alpinum andP. bertolonii was partially digested withSau3AI and cloned using pUC19 as a vector to anE. coli strain DH5mcr. A partial genomic DNA library consisting of 3030 colonies for the genome ofP. alpinum and one consisting of 3240 colonies for the genome ofP. bertolonii were constructed. Twelve hundred and thirty colonies from the DNA library ofP. alpinum and 1320 from that ofP. bertolonii were respectively blotted to membrane filters and hybridized to the total genomic probes from these two species. Eight clones specific toP. alpinum and 13 specific toP. bertolonii were isolated through colony hybridization and further dot-blot hybridization. Most of these clones may carry highly or moderately repetitive sequences. Three sequences specific toP. alpinum and 3 specific toP. bertolonii were used as probes to hybridize theEcoRI-digested DNA samples from four species,P. alpinum,P. bertolonii,P. pratense andP. montanum, on Southern blot. The results from these hybridization experiments showed that all 3P. bertolonii-specific probes and 2 of the 3P. alpinum-specific probes hybridized to the DNA ofP. pratense, thus confirming the conclusion of the close relationships between the cultivated timothy and its two wild relatives that was drawn in our previous study using the C-banding technique.     

Anaerobic CO2 Cabinet for the Cultivation of Strict Anaerobes

The design and construction of an anaerobic CO(2) cabinet are described. Air is displaced by a stream of oxygen-free CO(2), and anerobic conditions are produced in 3 hr. The equipment is simple and cheap to operate and has been found to be satisfactory for the isolation of strict anaerobes from the mouse intestine.     

Effect of photosynthetic biofilms on the open‐circuit potential of stainless steel

Periodic illumination of photosynthetic biofilms on AISI* 316L stainless steel resulted in evolution of oxygen (1–7 mg.1^‐1) and a corresponding increase in open circuit potential (E_corr) from 2 to 15 mV. The change in E^ depended on the interval of illumination. When the dark cycle began, elevation in potential was followed by an immediate drop. Illumination did not affect E_corr in sterile systems or in systems that contained only nonphotosynthetic eubacteria. Radiated heat from illumination accounted for changes of 4 to 5°C in temperature which, in the absence of oxygen production, should decrease dissolved oxygen by 0.75 mgl^‐1 and decrease E_corr by 1 mV. Positive shifts of E_corr induced by periodic illumination of photosynthetic biofilms are primarily the result of oxygen production.     

Characterization of a Serine Hydrolase Targeted by Acyl-protein Thioesterase Inhibitors in Toxoplasma gondii

In eukaryotic organisms, cysteine palmitoylation is an important reversible modification that impacts protein targeting, folding, stability, and interactions with partners. Evidence suggests that protein palmitoylation contributes to key biological processes in Apicomplexa with the recent palmitome of the malaria parasite Plasmodium falciparum reporting over 400 substrates that are modified with palmitate by a broad range of protein S-acyl transferases. Dynamic palmitoylation cycles require the action of an acyl-protein thioesterase (APT) that cleaves palmitate from substrates and conveys reversibility to this posttranslational modification. In this work, we identified candidates for APT activity in Toxoplasma gondii. Treatment of parasites with low micromolar concentrations of β-lactone- or triazole urea-based inhibitors that target human APT1 showed varied detrimental effects at multiple steps of the parasite lytic cycle. The use of an activity-based probe in combination with these inhibitors revealed the existence of several serine hydrolases that are targeted by APT1 inhibitors. The active serine hydrolase, TgASH1, identified as the homologue closest to human APT1 and APT2, was characterized further. Biochemical analysis of TgASH1 indicated that this enzyme cleaves substrates with a specificity similar to APTs, and homology modeling points toward an APT-like enzyme. TgASH1 is dispensable for parasite survival, which indicates that the severe effects observed with the β-lactone inhibitors are caused by the inhibition of non-TgASH1 targets. Other ASH candidates for APT activity were functionally characterized, and one of them was found to be resistant to gene disruption due to the potential essential nature of the protein.     

Short-term resistance to diet-induced obesity in A/J mice is not associated with regulation of hypothalamic neuropeptides

To investigate the mechanisms underlying long-term resistance of the A/J mouse strain to diet-induced obesity, we studied, over a period of 4 wk, the expression of uncoupling proteins in brown adipose tissue and the expression of hypothalamic neuropeptides known to regulate energy homeostasis and then used microarray analysis to identify other potentially important hypothalamic peptides. Despite increased caloric intake after 2 days of high-fat feeding, body weights of A/J mice remained stable. On and after 1 wk of high-fat feeding, A/J mice adjusted their food intake to consume the same amount of calories as mice fed a low-fat diet; thus their body weight and insulin, corticosterone, free fatty acid, and glucose levels remained unchanged for 4 wk. We found no changes in hypothalamic expression of several orexigenic and/or anorexigenic neuropeptides known to play an important role in energy homeostasis for the duration of the study. Uncoupling protein-2 mRNA expression in brown adipose tissue, however, was significantly upregulated after 2 days of high-fat feeding and tended to remain elevated for the duration of the 4-wk study. Gene array analysis revealed that several genes are up- or downregulated in response to 2 days and 1 wk of high-fat feeding. Real-time PCR analysis confirmed that expression of the hypothalamic IL-1 pathway (IL-1beta, IL-1 type 1 and 2 receptors, and PPM1b/PP2C-beta, a molecule that has been implicated in the inhibition of transforming growth factor-beta-activated kinase-1-mediated IL-1 action) is altered after 2 days, but not 1 wk, of high-fat feeding. The role of additional molecules discovered by microarray analysis needs to be further explored in the future.     

Regulation of adiponectin and its receptors in response to development of diet-induced obesity in mice

Adiponectin and its receptors play an important role in energy homeostasis and insulin resistance, but their regulation remains to be fully elucidated. We hypothesized that high-fat diet would decrease adiponectin but increase adiponectin receptor (AdipoR1 and AdipoR2) expression in diet-induced obesity (DIO)-prone C57BL/6J and DIO-resistant A/J mice. We found that circulating adiponectin and adiponectin expression in white adipose tissue are higher at baseline in C57BL/6J mice compared with A/J mice. Circulating adiponectin increases at 10 wk but decreases at 18 wk in response to advancing age and high-fat feeding. However, adiponectin levels corrected for visceral fat mass and adiponectin mRNA expression in WAT are affected by high-fat feeding only, with both being decreased after 10 wk in C57BL/6J mice. Muscle AdipoR1 expression in both C57BL/6J and A/J mice and liver adipoR1 expression in C57BL/6J mice increase at 18 wk of age. High-fat feeding increases both AdipoR1 and AdipoR2 expression in liver in both strains of mice and increases muscle AdipoR1 expression in C57BL/6J mice after 18 wk. Thus advanced age and high-fat feeding, both of which are factors that predispose humans to obesity and insulin resistance, are associated with decreasing adiponectin and increasing AdipoR1 and/or AdipoR2 levels.     

Formation of Tellurium Nanocrystals during Anaerobic Growth of Bacteria That Use Te Oxyanions as Respiratory Electron Acceptors

Certain toxic elements support the metabolism of diverse prokaryotes by serving as respiratory electron acceptors for growth. Here, we demonstrate that two anaerobes previously shown to be capable of respiring oxyanions of selenium also achieve growth by reduction of either tellurate [Te(VI)] or tellurite [Te(IV)] to elemental tellurium [Te(0)]. This reduction achieves a sizeable stable-Te-isotopic fractionation (isotopic enrichment factor [] = −0.4 to −1.0 per ml per atomic mass unit) and results in the formation of unique crystalline Te(0) nanoarchitectures as end products. The Te(0) crystals occur internally within but mainly externally from the cells, and each microorganism forms a distinctly different structure. Those formed by Bacillus selenitireducens initially are nanorods (~10-nm diameter by 200-nm length), which cluster together, forming larger (~1,000-nm) rosettes composed of numerous individual shards (~100-nm width by 1,000-nm length). In contrast, Sulfurospirillum barnesii forms extremely small, irregularly shaped nanospheres (diameter < 50 nm) that coalesce into larger composite aggregates. Energy-dispersive X-ray spectroscopy and selected area electron diffraction indicate that both biominerals are composed entirely of Te and are crystalline, while Raman spectroscopy confirms that they are in the elemental state. These Te biominerals have specific spectral signatures (UV-visible light, Raman) that also provide clues to their internal structures. The use of microorganisms to generate Te nanomaterials may be an alternative for bench-scale syntheses. Additionally, they may also generate products with unique properties unattainable by conventional physical/chemical methods.