Latent virus influences the generation and maintenance of CD8+ T cell memory

The influence of latent virus on CD8+ T cell memory is poorly understood. HSV type 1 specifically establishes latency in trigeminal ganglia (TG) after corneal infection of mice. In latently infected TG, IL-15 deprivation reduced the following: 1) accumulation of HSV-specific CD8+ effector T cells (HSV-CD8(eff)), 2) accumulation of CD127(+) putative HSV-CD8 memory precursors, and 3) the size and functionality of the memory (HSV-CD8(mem)) population. Although compromised in IL-15(-/-) mice, the HSV-CD8(mem) pool persisted in latently infected tissue, but not in noninfected tissue of the same mice. Anti-IL-2 treatment also dramatically reduced the size of the HSV-CD8(eff) population in the TG, but did not influence the concomitant generation of the CD127+ putative HSV-CD8(mem) precursor population or the size or functionality of the HSV-CD8(mem) pool. Thus, the size of the memory pool appears to be determined by the size of the CD127+ CD8(mem) precursor population and not by the size of the overall CD8(eff) pool. HSV-CD8(mem) showed a higher basal rate of proliferation in latently infected than noninfected tissue, which was associated with a reduced population of CD4+FoxP3+ regulatory T cells. Thus, the generation, maintenance, and function of memory CD8+ T cells is markedly influenced by latent virus.     

Correction to: Managing biological invasions: the cost of inaction

Biological Invasions -     

Early stages of the apoptotic pathway in plant cells are reversible

Chromatin condensation and nDNA fragmentation, indicators of apoptosis in mammalian cells, occur in plant cells during senescence and following induction by chemical agents. In Nicotiana plumbaginifolia cells, camptothecin, okadaic acid, salicylic acid, hydrogen peroxide, and the calcium ionophore A23187 induced chromatin condensation and nDNA fragmentation. Exposure of cells to low concentrations or removal of the chemical agent resulted in an initial phase of chromatin condensation, followed by its reversal. A further feature of apoptosis in mammalian cells, annexin V binding, indicative of phosphotidylserine exposure, was also confirmed in relation to the other events in the apoptotic pathway. With respect to flow cytometric characteristics, apoptosis triggered by a variety of chemicals occurs in plant cells in a manner closely related to that in mammalian cells. However, the extent of chromatin condensation is substantially greater, and in the early stages is reversible.     

Plate 483. Camassia leichtlinii 'Lady Eva Price'Liliaceae sens. lat.

The history, ecology, and distribution of Camassia leichtlinii are given and particularly the deep violet cultivar of subsp. suksdorfii‘Lady Eva Price’, which is illustrated. The position of Camassia within the Liliaceae sens. lat. is discussed in the light of recent DNA studies.     

Evolutionary analysis of the multigene pregnancy-specific β1-Glycoprotein family: Separation of historical and nonhistorical signals

The pregnancy-specific ₁-glycoproteins (PSG) form a large family of closely related proteins. Using newly developed methods of sequence analysis, in combination with protein modeling, we provide a framework for investigating the evolution and biological function of genes like the PSG. Evolutionary trees, based on C-terminal sequence, group PSG genes in a manner consistent with their genomic organization. Trees constructed using the N-terminal domain sequences are unreliable as an indicator of phylogeny because of non-neutral processes of sequence change. During duplication of the PSG genes, evolutionary pressures have resulted in a gradient of constrained change across each gene. The N-terminal domains show a nonrandom pattern of amino acid substitutions clustered in the immunoglobulin complementarity-determining region (CDR)-like regions, which appear to be important in the function of the protein.     

Limitations of Time-Resolved Fluorescence Suggested by Molecular Simulations: Assessing the Dynamics of T?cell Receptor Binding Loops

Time-resolved fluorescence anisotropy (TRFA) has a rich history in evaluating protein dynamics. Yet as often employed, TRFA assumes that the motional properties of a covalently tethered fluorescent probe accurately portray the motional properties of the protein backbone at the probe attachment site. In an extensive survey using TRFA to study the dynamics of the binding loops of a αβ T cell receptor, we observed multiple discrepancies between the TRFA data and previously published results that led us to question this assumption. We thus simulated several of the experimentally probed systems using a protocol that permitted accurate determination of probe and protein time correlation functions. We found excellent agreement in the decays of the experimental and simulated correlation functions. However, the motional properties of the probe were poorly correlated with those of the backbone of both the labeled and unlabeled protein. Our results warrant caution in the interpretation of TRFA data and suggest further studies to ascertain the extent to which probe dynamics reflect those of the protein backbone. Meanwhile, the agreement between experiment and computation validates the use of molecular dynamics simulations as an accurate tool for exploring the molecular motion of T cell receptors and their binding loops.     

Recommendations for the presentation of NMR structures of proteins and nucleic acids – IUPAC-IUBMB-IUPAB Inter-Union Task Group on the Standardization of Data Bases of Protein and Nucleic Acid Structures Determined by NMR Spectroscopy

The recommendations presented here are designed to support easier communication of NMR data and NMR structures of proteins and nucleic acids through unified nomenclature and reporting standards. Much of this document pertains to the reporting of data in journal articles; however, in the interest of the future development of structural biology, it is desirable that the bulk of the reported information be stored in computer-accessible form and be freely accessible to the scientific community in standardized formats for data exchange. These recommendations stem from an IUPAC-IUBMB-IUPAB inter-union venture with the direct involvement of ICSU and CODATA. The Task Group has reviewed previous formal recommendations and has extended them in the light of more recent developments in the field of biomolecular NMR spectroscopy. Drafts of the recommendations presented here have been examined critically by more than 50 specialists in the field and have gone through two rounds of extensive modification to incorporate suggestions and criticisms.