To understand the health impact of long-duration spaceflight, one identical twin astronaut was monitored before, during, and after a 1-year mission onboard the International Space Station; his twin served as a genetically matched ground control. Longitudinal assessments identified spaceflight-specific changes, including decreased body mass, telomere elongation, genome instability, carotid artery distension and increased intima-media thickness, altered ocular structure, transcriptional and metabolic changes, DNA methylation changes in immune and oxidative stress–related pathways, gastrointestinal microbiota alterations, and some cognitive decline postflight. Although average telomere length, global gene expression, and microbiome changes returned to near preflight levels within 6 months after return to Earth, increased numbers of short telomeres were observed and expression of some genes was still disrupted. These multiomic, molecular, physiological, and behavioral datasets provide a valuable roadmap of the putative health risks for future human spaceflight.

Properties of bottomonia (ϒ, χ b , and ϒ ) in the quark-gluon plasma (QGP) are investigated by assessing inelastic reaction rates and their interplay with open-bottom states (b quarks or B mesons) and color screening. The latter leads to vanishing quarkonium-binding energies at sufficiently high temperatures (close to the dissolution point), which, in particular, renders standard gluo-dissociation, g + ϒ → b +b, inefficient because of a substantial reduction in final-state phase space. This problem is overcome by invoking a "quasifree" destruction mechanism, g, q,q + ϒ → g, q,q + b +b, as previously introduced for charmonia. The pertinent reaction rates are implemented into a kinetic theory framework to evaluate the time evolution of bottomonia in heavy-ion reactions at the Relativistic Heavy Ion Collider and the CERN Large Hadron Collider within an expanding fireball model. Although bottom quarks are assumed to be exclusively produced in primordial nucleon-nucleon collisions, their thermal relaxation times in the QGP, which importantly figure into ϒ-formation rates, are estimated according to a recent Fokker-Planck treatment. Predictions for the centrality dependence of ϒ production are given for upcoming experiments at RHIC and LHC. At both energies, ϒ suppression turns out to be the prevalent effect.

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The Tp34 (TP0971) membrane lipoprotein of Treponema pallidum, an obligate human pathogen and the agent of syphilis, was previously reported to have lactoferrin binding properties. Given the non-cultivatable nature of T. pallidum, a structureto-function approach was pursued to clarify further potential relationships between the Tp34 structural and biochemical properties and its propensity to bind human lactoferrin. The crystal structure of a nonacylated, recombinant form of Tp34 (rTp34), solved to a resolution of 1.9 Å , revealed two metaloccupied binding sites within a dimer; the identity of the ion most likely was zinc. Residues from both of the monomers contributed to the interfacial metal-binding sites; a novel feature was that the ␦-sulfur of methionine coordinated the zinc ion. Analytical ultracentrifugation showed that, in solution, rTp34 formed a metal-stabilized dimer and that rTp34 bound human lactoferrin with a stoichiometry of 2:1. Isothermal titration calorimetry further revealed that rTp34 bound human lactoferrin at high (submicromolar) affinity. Finally, membrane topology studies revealed that native Tp34 is not located on the outer surface (outer membrane) of T. pallidum but, rather, is periplasmic. How propensity of Tp34 to bind zinc and the iron-sequestering lactoferrin may relate overall to the biology of T. pallidum infection in humans is discussed.