Contraception, reproduction and demography of free-ranging Etosha lions (Panthera leo)

The use of long-acting contraceptives as an effective population control mechanism for free-ranging lions was investigated during a three-year study in the Etosha National Park on five lion prides. Lions were immobilized with ketamine hydrochloride and xylazine hydrochloride. Following immobilization, lionesses were weighed, measured and aged, while serum steroid hormone levels were analysed and vaginal smears were obtained. Physical condition and sexual state were assessed. Individuals were used as control animals or given melengestrol acetate (contraceptive) implants, branded and released; the animals were observed for possible changes in behaviour, birth rate and mortality. Ten treated lionesses were recaptured at irregular intervals to reassess weight and steroid hormone levels, while three lionesses had their implants removed to determine if their fertility would return. The contraceptives prevented pregnancy, were reversible when removed and did not alter lion behaviour significantly, except that sexual behaviour was not recorded in treated lionesses.     

SEMI-LUNAR AND LUNAR SPAWNING PERIODICITY IN SOME TROPICAL LITTORINID GASTROPODS

Littoraria strigata, Nodilittorina millegrana and N. pyramidalisall spawned regularly in a rock-flanked Malaysian bay in March-June1985, whereas none had spawned there in July-October 1981. N.millegrana showed the least precise timing with some irregularpreponderance during the days between 2d before and 7d afternew or full moon and their associated spring tides. Spawningof N. pyramidalis was more strictly confined to spring tideswith 90% of eggs appearing between 2d before and 5d after newor full moon. There was no apparent difference between alternatespawnings on new and on full moons. L. strigata also spawnedregularly on the spring tides with 89% of eggs appearing between1 and 5 days after new and full moon. In this case, however,full moon spawnings (when spring tides rose highest) yieldedsome 7 times more eggs on average than the weaker spring tidesat new moons. In laboratory aquaria, the three species all released eggs duringboth night and daytime and through periods of both spring andneap tides with no evidence that periodicity persisted in constantconditions. The different degrees of 2-weekly spawning periodicity, togetherwith littorinids which spawn only monthly, may represent a rangeof adaptation to life at increasing shore heights. (Received 26 November 1985;     

DEVELOPMENT OF A TEXTURE PROFILE PANEL FOR EVALUATING RESTRUCTURED BEEF STEAKS VARYING IN MEAT PARTICLE SIZE

A texture profile panel was developed for measuring textural properties of restructured beef steaks differing in meat particle size. For steaks of different particle sizes, considerable differences existed in the type of sample breakdown and shape of chewed pieces after just two chews. Panelists also found restructured steaks made from large meat particle sizes to be visually more distorted and to contain more gristle than steaks made from small meat particle sizes. Several characteristics (chunkiness after two chews, coarseness of chewed mass at 15 chews) were dropped from the profile over time, while several characteristics (type of sample breakdown and shape of chewed pieces at two chews, size of chewed pieces at 10 chews) not used initially, were added. The texture profile panel approach appears suitable for discerning the textural differences in restructured steaks that can arise from using different meat particle sizes during processing.     

Gel‐free species identification using melt‐curve analysis

DNA‐based identification of organisms is an important tool in biosecurity, ecological monitoring and wildlife forensics. Current methods usually involve post‐polymerase chain reaction (PCR) manipulations (e.g. restriction digest, gel electrophoresis), which add to the expense and time required for processing samples, and may introduce error. We developed a method of species identification that uses species‐specific primers and melt‐curve analysis, and avoids post‐PCR manipulation of samples. The method was highly accurate when trialled on DNA from six large carnivore species from Tasmania, Australia. Because of its flexibility and cost‐effectiveness, this method should find wide use in many areas of applied biological science.     

British mammals: from trinomials to evolutionary ecology

The study of mammals in Britain has progressed from studies of distribution and differentiation to the present time, when new challenges face mammal workers. We need to build upon past achievements and use both new technology and old-fashioned dedicated observation to learn why what mammal is whew.     

The Use of a Mathematical Model for the Analysis of Manurial and Weather Effects on the Growth of Carrots

A model for the study of yearly and other variation in cropyields, based on a generalized form of the logistic equationof growth, was applied to three years' growth analysis dataon carrot crops from 16 plots of a long-term manurial experiment.In the ideal case, it is postulated that the growth in differentyears of carrot leaves or taproots on soil receiving a givenmanurial treatment could be described by a single curve if timein days was replaced by a scale based on one or more meteorologicalelements which affect relative growth-rates. The equation fitted the data on the growth of the leaves butnot that on the taproots. For leaf growth, the use of the sumsof solar radiation, day degrees or evaporation from an openwater surface did not give curves that fitted the growth databetter than those obtained with time in days. Yearly differencesin leaf (but not taproot) growth appeared to be related to correspondingdifferences in rainfall amounts, and it is suggested that ascale taking account of soil moisture tension might have givena better fit to the model. It appeared that whereas the relative leaf growth-rate was afunction of leaf but not taproot weight, relative taproot growth-ratewas a function of taproot weight and leaf weight. A furthermodel for the growth of carrots, based on this hypothesis isdescribed.     

Silencing of EEF2K (eukaryotic elongation factor-2 kinase) reveals AMPK-ULK1-dependent autophagy in colon cancer cells

EEF2K (eukaryotic elongation factor-2 kinase), also known as Ca²⁺/calmodulin-dependent protein kinase III, functions in downregulating peptide chain elongation through inactivation of EEF2 (eukaryotic translation elongation factor 2). Currently, there is a limited amount of information on the promotion of autophagic survival by EEF2K in breast and glioblastoma cell lines. However, the precise role of EEF2K in carcinogenesis as well as the underlying mechanism involved is still poorly understood. In this study, contrary to the reported autophagy-promoting activity of EEF2K in certain cancer cells, EEF2K is shown to negatively regulate autophagy in human colon cancer cells as indicated by the increase of LC3-II levels, the accumulation of LC3 dots per cell, and the promotion of autophagic flux in EEF2K knockdown cells. EEF2K negatively regulates cell viability, clonogenicity, cell proliferation, and cell size in colon cancer cells. Autophagy induced by EEF2K silencing promotes cell survival and does not potentiate the anticancer efficacy of the AKT inhibitor MK-2206. In addition, autophagy induced by silencing of EEF2K is attributed to induction of protein synthesis and activation of the AMPK-ULK1 pathway, independent of the suppression of MTOR activity and ROS generation. Knockdown of AMPK or ULK1 significantly abrogates EEF2K silencing-induced increase of LC3-II levels, accumulation of LC3 dots per cell as well as cell proliferation in colon cancer cells. In conclusion, silencing of EEF2K promotes autophagic survival via activation of the AMPK-ULK1 pathway in colon cancer cells. This finding suggests that upregulation of EEF2K activity may constitute a novel approach for the treatment of human colon cancer.