Transgenerational Effects of Parental Larval Diet on Offspring Development Time, Adult Body Size and Pathogen Resistance in Drosophila melanogaster

Environmental conditions experienced by parents are increasingly recognized to affect offspring performance. We set out to investigate the effect of parental larval diet on offspring development time, adult body size and adult resistance to the bacterium Serratia marcescens in Drosophila melanogaster. Flies for the parental generation were raised on either poor or standard diet and then mated in the four possible sex-by-parental diet crosses. Females that were raised on poor food produced larger offspring than females that were raised on standard food. Furthermore, male progeny sired by fathers that were raised on poor food were larger than male progeny sired by males raised on standard food. Development times were shortest for offspring whose one parent (mother or the father) was raised on standard and the other parent on poor food and longest for offspring whose parents both were raised on poor food. No evidence for transgenerational effects of parental diet on offspring disease resistance was found. Although paternal effects have been previously demonstrated in D. melanogaster, no earlier studies have investigated male-mediated transgenerational effects of diet in this species. The results highlight the importance of not only considering the relative contribution each parental sex has on progeny performance but also the combined effects that the two sexes may have on offspring performance

Speed variability of air-driven motors in the self-threading pin technique.

Effective pin placement is dependent upon correct preparation of the dentine channel. Various factors contribute to the success or otherwise of this channel preparation. One such factor is the rotational speed of the twist drill. It is widely recommended that the twist drill be operated within the 500-800 rpm speed range, in order to prevent a temperature rise in the pulp during the cutting process. This paper examines the ability of air-driven dental motors, when coupled to two speed-reduction handpieces with differing reducing ratios, to operate within this range. The results reveal a wide variation in the speed ranges of the motors tested. Of the two types of handpiece examined, it appears that a 10:1 speed reduction is appropriate for the majority of motors.link_to_subscribed_fulltex

Complications of pin placement. A survey of 429 cases.

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Current status of the cast metal inlay: a survey of dental schools in the UK and Hong Kong

This study reports on the current status of the gold inlay in the undergraduate curriculum of Dental Schools in the UK and at the Prince Philip Dental Hospital, Hong Kong, to determine if the decline in the use of the cast gold inlay over the past 20 years is reflected in teaching at undergraduate level. A questionnaire, which was mailed to all the heads of departments of conservative dentistry in the UK, was designed to determine current teaching in respect of cast inlays. The results show that although the majority of UK dental schools continue to teach direct and indirect inlay techniques, a minority (4 and 5 respectively) no longer incorporate a practical exercise in this teaching. Reasons cited for the discontinuation of the technique are varied but the availability of simpler, more conservative techniques is emphasized. Examination of the treatment records at the prince Philip Dental Hospital, Hong Kong, where the Class II inlay technique is taught both theoretically and practically, shows that only a small proportion of all posterior cast restorations fitted between May 1983 and April 1988 were inlays (4·6 per cent). © 1989.link_to_subscribed_fulltex