Effect of magnesium on the growth and cell cycle of transformed and non-transformed epithelial rat liver cells in vitro

The effects of magnesium (Mg) restriction on cell growth and the cell cycle were determined in transformed (TRL-8) and non-transformed (TRL-12-15) epithelial-like rat liver cells. Cells were cultured in RPMI 1640 medium in which the Mg concentration was reduced to 0.5, 0.1, and 0 × the concentration in the regular RPMI 1640 media (100mg/l). Cell growth in the transformed cells was not influenced by the Mg restriction as greatly as in the non-transformed cell line. Transit through the cell cycle also exhibited an independence of the Mg in the medium in the transformed cells. When transformed cells were grown for two generations in Mg-limited medium, the growth rate slowed to a rate similar to that demonstrated by the non-transformed cells. Analysis by flow cytometry showed that transit through the cell cycle was minimally slowed in Mg deficient transformed cells; however, transit through the G₁ and S phases in the non-transformed cells was slowed. The TRL-8 cells in Mg-limited medium resulted in fewer nuclei in G₁ with subsequent increases in the percentages of S-phase nuclei. The TRL 12-15 cells reacted oppositely with the number of G₁ nuclei increased and the number of S-phase nuclei decreased. In respect to growth, these results show that epithelial cells respond in a similar manner to Mg-limitation as do fibroblast cells. The transformed cells exhibited a level of independence from Mg in respect to growth, reproduction, and cell-cycle kinetics.     

Improving Smear Technics by the Use of Enzymes

A method for securing spreading of large meiotic chromosomes is described. It consists in treating a piece of fixed anther in a 1% solution of Clarase, a proprietary enzyme complex, or in an extract prepared by grinding the contents of flask cultures of certain fungi (Aspergillus niger, Chaetomium globosum, Metarrhizium sp.) with quartz sand in a mortar containing 10 ml. of a sodium acetate buffer, pH 5.0. The fixed anthers are thoroughly washed in H₂O prior to the enzyme treatment. Length of treatment may vary from as little as 10 minutes to several hours. The usual aceto-carmine or propionic-carmine smear technic may then be used. The treatment destroys some of the elasticity of the cytoplasm so that the chromosomes remain spread out when light pressure is exerted on the cover slip.     

The occurrence of the septal perforation of the humerus in three non-human primate species

Evidence is presented concerning the occurrence of the coronoid-olecranon perforation of the humerus in three species of Old World monkeys. Significant relationships are found to exist between the occurrence of the perforation and smaller minimum midshaft diameters of humeri, younger ages, and more protruding processes of ulnae. A possible explanation for perforated coronoid-olecranon septums is advanced. The olecranon process of the ulna is found to project relatively more from the shaft in young individuals than old individuals. Since the protrusion of this process is positively correlated with the occurrence of the septal perforation, it is suggested that the articulation of the point of the ulna causes resorption of the coronoid-olecranon septum. With advancing age, the contact is broken, and the perforation is filled in. Since significant correlations are shown for the occurrence of the perforation and the size of the humerus, even for an adult sample, it seems probable that the robustness of the humerus is an inhibiting factor in the occurrence and maintenance of the perforation. In larger humeri, it is possible that the point of the ulna cannot cause complete resorption, and resorption would be more likely to cause a perforation in humeri with thinner coronoid-olecranon septums. Because extreme extension of the elbow always forms an angle considerably less than 180° between the axes of the shafts in the humerus and the ulna in these monkeys, it is strongly indicated that hyperextension of the elbow joint beyond 180° is not a primary cause of the septal perforation when it appears in man.     

The Indigenous People of the Caribbean

The Indigenous People of the Caribbean. Samuel M. Wilson. ed. Gainesville: University of Florida Press, 1997.254 pp.     

The Customer Isn't Always Right—Conservation and Animal Welfare Implications of the Increasing Demand for Wildlife Tourism

Tourism accounts for 9% of global GDP and comprises 1.1 billion tourist arrivals per annum. Visits to wildlife tourist attractions (WTAs) may account for 20–40% of global tourism, but no studies have audited the diversity of WTAs and their impacts on the conservation status and welfare of subject animals. We scored these impacts for 24 types of WTA, visited by 3.6–6 million tourists per year, and compared our scores to tourists’ feedback on TripAdvisor. Six WTA types (impacting 1,500–13,000 individual animals) had net positive conservation/welfare impacts, but 14 (120,000–340,000 individuals) had negative conservation impacts and 18 (230,000–550,000 individuals) had negative welfare impacts. Despite these figures only 7.8% of all tourist feedback on these WTAs was negative due to conservation/welfare concerns. We demonstrate that WTAs have substantial negative effects that are unrecognised by the majority of tourists, suggesting an urgent need for tourist education and regulation of WTAs worldwide.     

Cytochrome Composition of Some Members of the Actinoplanaceae

The cytochrome composition of 19 strains of Actinoplanaceae has been investigated. The principal cytochrome found was cytochrome b, and occasional strains showed the presence of cytochrome a.     

Coincident isolation of a novel homoisoflavonoid from Resnova humifusa and Eucomis montana (Hyacinthoideae: Hyacinthaceae)

We report on the first phytochemical investigation of a member of the African genus Resnova (Hyacinthoideae: Hyacinthaceae). From the dichloromethane extract of the bulbs of both Resnova humifusa and Eucomis montana (Hyacinthoideae: Hyacinthaceae) a novel 3-benzyl-4-chromanone homoisoflavonoid, 5,6-dimethoxy-7-hydroxy-3-(4′-hydroxybenzyl)-4-chromanone, was isolated. A further 11 known homoisoflavonoids were also identified, the 12 in total presenting a clear biosynthetic sequence. Eight of the 12 compounds found were common to both species.