Studies on the structure and stabilizing factor of the CUUCGG hairpin RNA using chemically synthesized oligonucleotides.

A tridecaribonucleotide, r-UGAGCUUCGGCUC, and two analogues r(UGAGC)d(UUCG)r(GCUC) and r-UGAGCUUCIGCUC, which form a hairpin structure with a four-base-paired stem and a UUCG loop, were synthesized by the solid-phase phosphoramidite method. Properties of these three oligomers and d-TGAGCTTCGGCTC, the DNA analogue, were studied by UV, CD and NMR spectroscopy. The melting temperature (Tm) data suggest that the 2'-hydroxy1 groups and the 2-amino group of guanosine in the loop (9G) stabilize the CUUCGG hairpin which is known to have an unusually high Tm. NMR studies show that this 9G takes a syn conformation and the phosphodiester backbone has a turn at 9G-10G which is a junction of the stem and loop.     

Multiple expression of keratins, vimentin, and S-100 protein in pleomorphic salivary adenomas.

Immunohistochemical staining for S-100 protein and the intermediate filaments keratin and vimentin, was made in 41 salivary adenomas. In pleomorphic adenomas, great heterogeneity in the staining, as well as multiple and co-expressions of these proteins were found in the outer tumor cells of tubulo-ductal structures and modified myoepithelial cells, but not in the luminal tumor cells. All the outer tumor cells stained for S-100 protein, 97% for K8.12 keratin and 85% for vimentin. Of these cells, 29% showed multiple expression of K8.12 keratin, vimentin, and S-100 protein, and 17% showed co-expression of K8.12 and S-100 protein. Modified and neoplastic myoepithelial cells showed similar expressions of these proteins to those of outer tumor cells; myoepithelioma cells displayed the most complicated pattern, being positive for KL1, PKK1, and K8.12 keratins, vimentin and S-100 protein. In luminal tumor cells there was a heterogeneous expression of KL1 and PKK1 in 82%, and of KL1, PKK1, and K8.12 in only 14.7%. Based on the immunohistochemical findings obtained with different monoclonal antibodies in pleomorphic salivary adenomas, outer tumor cells may be derived from ductal basal cells and luminal tumor cells from intercalated duct cells.     

Effect of marking pheromone on clutch size in the Mediterranean fruit fly

Abstract Using acridine orange to selectively stain eggs, we showed that wild-collected female Mediterranean fruit flies (Ceratitis capitata Wiedemann) laid fewer eggs per clutch in fruit previously infested with eggs than in uninfested fruit. This effect is apparently attributable to marking pheromone deposited by females after oviposition: clutch size on fruit infested with eggs but free of marking pheromone was not statistically different from that on uninfested fruit. Clutch size on uninfested fruit on which marking pheromone was artificially transferred was significantly lower than that on uninfested and untreated fruit. Marking pheromone had a comparable though not statistically significant effect on the clutch size of females originating from a strain maintained in the laboratory for several hundred generations.     

Human mononuclear phagocyte activation antigens

Activation of mononuclear phagocytes causes changes in plasma membrane composition that include the expression of surface antigens and receptors. Monoclonal antibody technology has made it possible to identify and characterize newly expressed surface antigens. Among these "activation antigens" is a glycoprotein, Mo3, which (among hematopoietic cells) is selectively expressed by human mononuclear phagocytes that have been exposed to inflammatory factors in vitro and in vivo. Progress toward a functional and structural analysis of Mo3 is described.     

Effect of the Photosynthetic Light Period on the Carbon Budget of Young Tomato Leaves

This study was carried out to elucidate the carbon budget inyoung tomato plants in photosynthetic light periods of 8, 12and 16 h after being acclimated to an 8-h light period. Thephotosynthetic rate was nearly constant for 16 h: thereforethe amount of ¹⁴C fixed was proportional to the light period(13·77 mg C per 8 h, 20·2 mg C per 12 h, 30·5mg C per 16 h). The amounts exported, lost by respiration and accumulated whenexpressed as percentages of the carbon fixed in the day differedlittle between the light periods. The leaf continued to exportcarbon at a nearly constant rate during the light periods and,for example, exported approximately twice as much during a 16-hperiod as in an 8-h light period, even though it was not acclimatedto the long light period. The amount of starch breakdown affected the amount of carbonexported and carbon lost by respiration at night, although itwas not sufficient to account for these losses altogether. Thepossible roles of carbon accumulation and respiration are alsodiscussed. Carbon budget, steady state feeding, ¹⁴C, photosynthesis, respiration, translocation, carbon metabolism, tomato, Lycopersicon esculentum Mill     

Regulation of Drosophila myosin ATPase activity by phosphorylation of myosin light chains--II. Flightless mfd- fly

1. The Ca2(+)-activated and Mg2+ actin-activated myosin ATPase activities of flightless mfd- mutant Drosophila flight muscle myosin were one-half and one-third of those of the wild-type fly muscle myosin, respectively. 2. In the two-dimensional gel electrophoresis, the spots corresponding to phosphorylated myosin light chains, Lfl and Ltl, were hardly detected in mfd- mutant myosin. 3. These results support not only the conclusion that phosphorylation of myosin light chains regulates Drosophila myosin ATPase activity but also the assumption that the phosphorylation of myosin light chains is directly involved in flight function of the Drosophila fly.