Dual Vα T cells

The assumption that T cells can only express a single receptor for antigen has in recent years been shown to be incorrect. However, the finding that a substantial number of T cells express two distinct antigen receptors at the cell surface raises a number of questions. In particular, it has been suggested that cells expressing low levels of a self-reactive T cell receptor may escape self-tolerance mechanisms and in certain situations trigger the onset of autoimmune disease. Such a hypothesis in turn raises questions central to the understanding of the nature of T cell recognition and the process of thymocyte maturation.     

Peptide-induced conformational change of the class I heavy chain

There is evidence that peptide ligands take part in the assembly of class I molecules. In particular, addition of peptides to extracts of the mutant cells RMA-S and .174/T2, in which stable assembly of class I does not occur, results in a conformational change in the class I heavy chain and stable association of the heavy chain with beta 2-microglobulin (beta 2m). Thus specific peptides may stabilize or induce a conformational change in the class I heavy chain that results in a rise in the binding affinity of the heavy chain for beta 2m (Fig. 1a). Here we show that peptides have two cooperative roles in class I assembly. Specific short peptides (9-10 amino acids) can induce folding of the heavy chain in the absence of beta 2m. Both short (nine amino acids) and longer sequences (15 amino acids) can stabilize performed low-affinity complexes of heavy chain and beta 2m. To alter the conformation of free heavy chains, the peptides must be exactly the correct size, and they are found to correspond to the sequences isolated from infected cells. This property may therefore be the basis for selection of epitopes presented in vivo.     

Postemergence development and interyear residence of juvenile Columbian ground squirrels in the Idaho Primitive Area

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Monthly percent nutrient and moisture levels of plant species on two summer ranges in the River of No Return Wilderness Area of Idaho were determined. Festuca idahoensis exhibited the highest average crude protein content of graminoids on both study areas. Achillea millefolium and Balsamorhiza saggittata at Rush Point and Trifolium spp. and Achillea millefolium at Cold Meadows possessed the highest mean crude protein content of the forbs examined. Grasses exhibited greater average seasonal levels of crude fiber, and forbs generally contained significantly larger levels of Ca, P, and moisture.     

Mutations in CEP57 cause mosaic variegated aneuploidy syndrome

Using exome sequencing and a variant prioritization strategy that focuses on loss-of-function variants, we identified biallelic, loss-of-function CEP57 mutations as a cause of constitutional mosaic aneuploidies. CEP57 is a centrosomal protein and is involved in nucleating and stabilizing microtubules. Our findings indicate that these and/or additional functions of CEP57 are crucial for maintaining correct chromosomal number during cell division.     

Effects of ornithine8-oxytocin and ornithine8-vasopressin on the permeability of toad skin

Résumé En employant des crapauds pour doser l'action des peptides sur la perméabilité de la peau, l'effet hydrosmotique de l'arginine⁸-vasotocine s'est montré 200 fois plus puissant que celui de l'ornithine⁸-oxytocine. Ce fait confirme l'importance hydrosmotique de l'acide aminé arginine dans la position 8. Tous 2 ont eu un effet natriférique, mais ce ne fut pas le cas de la lysine⁸-vasopressine et l'ornithine⁸-vasopressine. L'importance natriférique de l'acide aminé isoleucine dans la position 3 en est confirmée.     

Nesting and predatory behavior of some Tachysphex from the western United States (Hymenoptera: Sphecidae)

The first published observations on the nesting and predatory behavior of Tachysphex antennatus Fox, T. occidentalis Pulawski, T. williamsi Bohart, T. yolo Pulawski, T. alpestris Rohwer, T. clarconis Viereck, T. apricus Pulawski, and T. cockerellae Rohwer are presented herein. Also included are host and behavioral data on T. tarsatus (Say), T. apicalis fusus Fox, T. similis Rohwer, T. ashmeadii Fox, and T. mundus exsectus Fox.