High-frequency1H NMR studies of the effects of growth factors and phorbol esters on normal syrian hamster diploid fibroblast cells

The nuclear magnetic resonance (NMR) parameters, spin-lattice (T₁), and spin-spin (T₂) relaxation time, are usually longer for neoplastic cells than for normal cells of the same cell type. This has generally been true at low NMR frequencies (≤100 MHz) when comparisons have been made between normal and neoplastic cells that have both spent a short time in culture. We have previously demonstrated that although the T₁ values of paired normal and neoplastic Syrian hamster (SH) fibroblastic cells in culture are not significantly different when measured at 300 MHz, the 300 MHz T₂ values for the neoplastic cells are smaller than those of the normal cells. (Xin et al. (1986),Cell Biophysics 8, 213.) Since treatment of normal diploid cells with polypeptide growth factors or tumor promoters frequently results in reversible expression of neoplasia-associated phenotypes, T₁ and T₂ were obtained at 300 MHz for treated and untreated SH cells to see if these compounds could also produce smaller 300 MHz T₂ values. Secondary culture SH fetal fibroblast cells were treated with epidermal growth factor (EGF), fibroblast growth factor (FGF), phorbol-12,13-didecanoate (PDD) and 4-α-phorbol-12,13-didecanoate (4αPDD). Treatment with either growth factor resulted in smaller T₂ values, but a statistically significant decrease was not observed for PDD or 4αPDD. The observed reductions in T₂ values were correlated with the morphological and growth-stimulatory effects of these compounds on the cells.     

A method for studying vegetation dynamics when there are no obvious individuals: Virtual-population analysis applied to the tundra shrub Betula nana L.

A method is presented to study dynamics of plants that cannot be separated into individuals such as many grassland, salt marsh and tundra species. A virtual population is created by using a permanent transect line through the vegetation and individuals are defined as the branch segments distal to the intercept with the transect line. Addition and loss of individuals together with growth or shrinkage form the basis for constructing a size-structured transition matrix. A discrete-event simulation demonstrates that: 1) a virtual population of individuals grows at the same rate as the parent population; and, 2) size-structured transition matrices for a virtual population and parent vegetation have similar dominant and subdominant eigenvalues so a virtual population can be used to describe the dynamics of a parent vegetation.Dwarf birch, Betula nana L., was studied in the northern foothills of the Brooks Range, Alaska, by using photography to record branch intercepts along permanent transect lines. The distal branch segments constitute a virtual population of the parent vegetation. Transects were photographed in 1985 and again in 1986 and changes of branch segments were used to construct two transition matrices for shrubs with and without elevated fertilizer treatment. Analysis of the virtual populations suggests that although Betula nana may show increased branch growth with increased fertilizer, in the long run this shrub may decline in the tundra in response to such treatment.     

Comparison of serum free thyroxine measurements by chemiluminescence and equilibrium dialysis

A study of 239 patients compared free thyroxine (FT4) measurements made by equilibrium dialysis (ED) with measurements made using the Magic Lite FT4 chemiluminescence (Cl) immunoassay (Ciba Corning Immunodiagnostics). Patient groups: 41 normals; 27 hyperthyroid; 29 hypothyroid; 37 sick euthyroid; 10 chronic renal failure (CRF) and 25 pregnant patients; 13 oestrogen; 10 heparin; 12 salicylate; and 9 dilantin-treated patients; 3 lipaemic; 5 haemolysed; 6 hyperbilirubinaemic patients; 6 low thyroid binding protein (TBP) and 6 high TBP level patients. The two assays gave comparable results in most groups. Both assays tended to give elevated values in heparinized patients but FT4–ED results were more obviously affected. Pregnant patients and women on oral oestrogen had higher mean values with FT4–ED. In both assays the sick euthyroid and CRF patients had mean FT4 values similar to healthy euthyroid patients; the range of values in sick euthyroid and CRF patients was similar in both assays but wider than in healthy euthyroid patients. A supplemental study of 81 unselected acutely ill patients using FT4–Cl alone confirmed the wider range of values to be anticipated in sick euthyroid patients.     

Growth factor modulation of melanoma growth stimulatory activity mRNA expression in human malignant melanoma cells correlates with cell growth

This report demonstrates that the expression of melanoma growth stimulatory activity (MGSA) mRNA can be modulated in a positive fashion in the Hs294T human melanoma cell line by PDGF and MGSA. There is close correlation between MGSA expression and the pattern of cell growth in Hs294T cells.     

Micronekton and macrozooplankton in the open waters near Antarctic ice edge zones (AMERIEZ 1983 and 1986)

Summary Micronekton and macrozooplankton assemblages (0–1000 m) were sampled from the open ocean in the vicinity of marginal ice zones in the southern Scotia and western Weddell Seas using midwater trawls. Small regional differences in species composition were found in the differing hydrographic settings with the Scotia Sea being slightly more diverse. Most species exhibited broad vertical ranges with no distinct pattern of vertical movement. Exceptions were mesopelagic fish and Salpa thompsoni which undertook diel vertical migrations. Biomass was high (2.4–3.1 g DW/m²), comparable to Pacific subarctic waters. Euphausia superba and Salpa tompsoni were the numerical and biomass dominants, representing over 50% of the total numbers and standing stocks. In terms of biomass, euphausiids were the most important group at shallow depths (0–200 m) but were surpassed by salps in the Scotia Sea and mesopelagic fish in the Weddell Sea when all depths down to 1000 m were considered. Pelagic fish biomass (3.3–4.4 g WW/m²) greatly exceeded published estimates for birds (0.025–0.070 g WW/m²), seals (0.068–0.089 g WW/m²) and whales (0.167 to 0.399 g WW/m²), making mesopelagic fish the most prevalent krill predators in the Antarctic oceanic system.     

A duplex of the oligonucleotides d(GGGGGTTTTT) and d(AAAAACCCCC) forms an A to B conformational junction in concentrated salt solutions

The coexistence of both A form and B form tracts and formation of an A-B junction in the oligomer d(GGGGGTTTTT).d(AAAAACCCCC) in saturated sodium chloride solution have been detected by Raman spectroscopy. The entire duplex adopts the familiar B-form conformation in aqueous solution at low salt concentrations (0.1M NaCl). In 6M NaCl the adoption of an A form is observed within the G,C tract while a B-form is maintained in the A.T tract. The experimental results indicate that two different helical forms can co-exist in a rather short oligonucleotide and that formation of an A-B junction can occur over a fairly small span of bases. This is in agreement with recent rules governing the relation between base sequence and secondary structure of DNA published from this laboratory. The conformational preferences of each of the individual oligomers d(AAAAACCCCC) and d(GGGGGTTTTT) have also been investigated. The oligomer d(AAAAACCCCC) is single stranded but some evidence for base stacking is observed at 2 degrees C. In contrast, a double stranded B-form structure characterized by wobble G-T base pairing is observed for d(GGGGGTTTTT) in 0.1M and 6M NaCl.