Illuminating the life of GPCRs

The investigation of biological systems highly depends on the possibilities that allow scientists to visualize and quantify biomolecules and their related activities in real-time and non-invasively. G-protein coupled receptors represent a family of very dynamic and highly regulated transmembrane proteins that are involved in various important physiological processes. Since their localization is not confined to the cell surface they have been a very attractive "moving target" and the understanding of their intracellular pathways as well as the identified protein-protein-interactions has had implications for therapeutic interventions. Recent and ongoing advances in both the establishment of a variety of labeling methods and the improvement of measuring and analyzing instrumentation, have made fluorescence techniques to an indispensable tool for GPCR imaging. The illumination of their complex life cycle, which includes receptor biosynthesis, membrane targeting, ligand binding, signaling, internalization, recycling and degradation, will provide new insights into the relationship between spatial receptor distribution and function. This review covers the existing technologies to track GPCRs in living cells. Fluorescent ligands, antibodies, auto-fluorescent proteins as well as the evolving technologies for chemical labeling with peptide- and protein-tags are described and their major applications concerning the GPCR life cycle are presented

Cool-season annual pastures with clovers to supplement wintering beef cows nursing calves

<p>Abstract</p> <p>In December of 3 years, 87 beef cows with nursing calves (594 ± 9.8 kg; calving season, September to November) at side were stratified by body condition score, body weight, cow age, and calf gender and divided randomly into 6 groups assigned to 1 of 6 cool-season annual pastures (0.45 ha/cow) that had been interseeded into a dormant common bermudagrass (<it>Cynodon dactylon</it> [L.] Pers.)/bahiagrass (<it>Paspalum notatum</it> Flugge) sod. Pastures contained 1 of the following 3 seeding mixtures (2 pastures/mixture): 1) wheat (<it>Triticum aestivum</it> L.) and ryegrass (<it>Lolium multiflorum</it> Lam., <b>WRG</b>), 2) wheat and ryegrass plus red clover (<it>Trifolium pretense</it> L., <b>WRR</b>), or 3) wheat and ryegrass plus white (<it>Trifolium repens</it> L.) and crimson clovers (<it>Trifolium incarnatum</it> L., <b>WRW</b>). All groups had <it>ad libitum</it> access to grass hay (12% crude protein; 58% total digestible nutrients). The second week in December, cow estrous cycles were synchronized and artificially inseminated. In late December, a bull was placed with each group for 60-d. Data were analyzed with an analysis of variance using a mixed model containing treatment as the fixed effect and year as the random effect. Body weight and condition scores did not differ (<it>P</it> ≥ 0.27) among cows between February and June. Calf birth weights or average daily gain did not differ (<it>P</it> ≥ 0.17) among treatments; however, calves grazing pastures with clovers did tend (<it>P</it> = 0.06) to weigh more than calves grazing grass only. Weaning weight per cow exposed to a bull was greater (<it>P</it> = 0.02) for WRR and WRW than WRG. Cows grazing winter-annual pastures containing clovers tended to wean more calf body weight per cow exposed to a bull than cows grazing the grass only pastures.</p