Dispersion of viable pig liver cells with collagenase.

Viable suspended hepatocytes were prepared from surgical biopsy specimens of pig and human liver by digestion with collagenase. Initial perfusion of the tissue through cannulated blood vessels with 0.5 mM EGTA followed by 0.2% collagenase gave the best results. 20−870 × 10⁶ cells of which 60–95 % excluded trypan blue were obtained from 5–30 g pig liver pieces, while results with human liver specimens were usually less satisfactory. In some experiments, however, viable cells, as judged by vital stain exclusion and ability to synthesize lipids were obtained in sufficient yield. In the pig hepatocytes glycerolipid synthesis from [³H] glycerol and oxidation and esterification of [¹⁴C] oleic acid had the same characteristics as those observed earlier in rat hepatocytes.     

Male behavior through the breeding season in Saimiri boliviensis boliviensis

The Bolivian squirrel monkey (Saimiri boliviensis boliviensis) is a seasonal breeder. Male squirrel monkeys show distinct morphological and behavioral changes prior to and during the breeding season. A “fatting syndrome” includes increased body weight, increased levels of androgens, and in the Bolivian subspecies, an increasingly active role in the social organization of the group. In this study, the behavior of ten adult male Bolivian squirrel monkeys was analyzed over a 6-month period prior to, during, and after the breeding season. Each was housed as the only adult male in a breeding unit with six to ten adult females and one juvenile male. Employing a principle components method, 11 behavioral clusters were generated from 27 responses. Their activity clusters were identified as follows: sexual activity that showed a peak around the time of peak conceptions; excitatory activity that was initially high but decreased throughout the breeding season; and maintenance activity that did not change across the breeding season. The changing social behavior of the male squirrel monkey parallels physiological changes and is correlated with changing androgen levels.     

Geolocators lead to better measures of timing and renesting in black-tailed godwits and reveal the bias of traditional observational methods

Long-term population studies can identify changes in population dynamics over time. However, to realize meaningful conclusions, these studies rely on accurate measurements of individual traits and population characteristics. Here, we evaluate the accuracy of the observational methods used to measure reproductive traits in individually marked black-tailed godwits (Limosa limosa limosa). By comparing estimates from traditional methods with data obtained from light-level geolocators, we provide an accurate estimate of the likelihood of renesting in godwits and the repeatability of the lay dates of first clutches. From 2012 to 2018, we used periods of shading recorded on the light-level geolocators carried by 68 individual godwits to document their nesting behaviour. We then compared these estimates to those simultaneously obtained by our long-term observational study. We found that among recaptured geolocator-carrying godwits, all birds renested after a failed first clutch, regardless of the date of nest loss or the number of days already spent incubating. We also found that 43% of these godwits laid a second replacement clutch after a failed first replacement, and that 21% of these godwits renested after a hatched first clutch. However, the observational study correctly identified only 3% of the replacement clutches produced by geolocator-carrying individuals and designated as first clutches a number of nests that were actually replacement clutches. Additionally, on the basis of the observational study, the repeatability of lay date was 0.24 (95% CI 0.17–0.31), whereas it was 0.54 (95% CI 0.28–0.75) using geolocator-carrying individuals. We use examples from our own and other godwit studies to illustrate how the biases in our observational study discovered here may have affected the outcome of demographic estimates, individual-level comparisons, and the design, implementation and evaluation of conservation practices. These examples emphasize the importance of improving and validating field methodologies and show how the addition of new tools can be transformational.     

Effect of phenological development on radiophosphorus translocation from leaves in crested wheatgrass

Summary The effect of phenological development on the pattern of photosynthate translocation was studied in crested wheatgrass [Agropyron cristatum (L.) Gaertn.] plants grown in a nursery under semi-natural environmental conditions at Logan, Utah. Radiophosphorus was used to trace the photosynthate translocation from April 13, 1968, through December 2, 1968.In early spring photosynthates were translocated about equally to the roots and younger leaves. Translocation was chiefly upward during the flower stage but was reversed with raturation of the inflorescence. In late summer the plants appeared quiescent but substantial ³²P was transported to the underground portions of the plant. After quiescence was broken in the fall, shoot and root growth were resumed simultaneously with peak ³²P movement to the crown and roots.The concentration of total available carbohydrates in the roots and crowns reached a maximum level just prior to quiescence and decreased during shoot production in the fall. Presumably, the carbohydrates were used in growth and the accumulation of carbohydrates for the winter is apparently not critical in crested wheatgrass. Since the plants have many basal leaves throughout the winter, they may have the capacity to carry out photosynthesis on warm, sunny winter days and are capable of immediately initiating growth in the spring.Utah Agricultural Experiment Station Paper 1074.     

Inhibition of cell proliferation by glycerol

The effect of glycerol on proliferation of BHK, CHO, HBL, MCF-7, and human glioma cells was studied. Cell proliferation was significantly decreased in all the cell lines at glycerol concentrations of 2-4% in the culture medium. The inhibition was dose-dependent, complete suppression of proliferation occurring at a glycerol concentration of 4% for the MCF-7 cell line and 6-8% for the BHK, CHO and human glioma cells. Studies on [3H]thymidine incorporation correlate with the effect on cell proliferation. The viability of the cells was not significantly affected until higher concentrations of glycerol (12% +) were present. Recovery studies with BHK cells indicated that replacement of the glycerol medium with glycerol-free medium resulted in full recovery following exposure to 4% glycerol and only partial recovery (65%) of proliferation rate following exposure to 10-12% glycerol. It is concluded that glycerol, a substance that is normally present in tissues, can serve as a potent inhibitor of cell proliferation.