Acetic acid pretreatment of initiated epidermis inhibits tumour promotion by a phorbol ester

Summary Mouse skin initiated with 7,12-dimethylbenz(a)anthracene and then exposed to multiple treatments of acetic acid, shows a decreased papilloma yield on subsequent promotion with croton oil.Acknowledgment. The author thanks Mr M. Froscio for excellent technical assistance.This investigation was supported by the Australian Research Grants Committee, the Australian Tobacco Research Foundation and the University of Adelaide Anti-Cancer Foundation.     

Heterogeneity of macrophage cytophilic antibodies in immunized mice

Résumé Des souris immunisés avec des globules rouges de mouton dans l'adjuvant de Freund produisent deux types de facteurs cytophiles pour macrophages. L'un s'attache aux macrophages trypsinisées et se trouve parmi les immunoglobulines. L'autre ne s'attache pas aux macrophages trypsinisées et se rencontre dans une fraction de sérum contenant de l'albumine et de la globuline-₁.

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Supported by grants from the Australian Research Grants Committee, the National Health and Medical Research Council of Australia and the Postgraduate Medical Foundation, University of Sydney.     

Immunological and morphological consequences of vasectomy in the rabbit

Summary Cell-mediated immunity to spermatozoa was detected in vitro 6–18 months after vasectomy in the rabbit. The autoimmunity was accompanied by aspermatogenic orchitis in the testes and epididymides.Acknowledgments. We acknowledge the financial support of the Australian Research Grants Committee and the Australian and Kenyan Governments for support through the Australian Development Assistance Bureau.     

A new interpretation of the sex determining mechanism of the European earwig,Forficula auricularia

Riassunto Osservazioni su femmine diForficula auricularia L. indicano che esse possiedono un solo cariotipo formato da 22 autosomi e da 2 cromosomiX. Sulla base di questo studio, suggeriamo che i maschi con 3 cromosomi sessuali sono del tipoXYY, e nonXXY come precedentemente ritenuto da varii autori. Ci sono maschiXY ₁t, XY₂, XY₂Y₂ e mosaiciXY ₂/XY₂Y₂ nella popolazione. Inoltre viene dimostrato che solamente il più grande dei due cromosomi Y, che caratterizzano questa specie, viene accumulato nei maschi con un meccanismo multiple di cromosomi sessuali.

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Supported by a postgraduate award from the Commonwealth of Australia to G.C.W. and by Public Health Service Grant No. GM-07212 from the Division of General Medical Sciences, U.S. National Institutes of Health and by a grant from the Australian Research Grants Committee.     

Über den Vitamin-B12-Gehalt von Organen verschieden ernährter Ratten

Summary Adult, male rats bred for over 10 generations on a soy meal-corn-diet had vitamin B₁₂ values of liver and kidney about 10 times lower than the controls. If the deficient ration was supplemented with 5µg/kg of B₁₂, these values were still about 1/5 of the controls. 3 weeks on the deficient diet lowered the B₁₂ levels in the livers and kidneys of previously undepleted rats to about 1/2, and a similar diet containing 0.1% of iodized casein lowered these levels to about 1/3 of the normal values but did not lower the B₁₂-concentration of organs of already deficient rats.Rats bred on the deficient diet and receiving for 1 month a supplement of 30µg/kg of vitamin B₁₂ or the stock diet with a similar B₁₂-content, had normal B₁₂-levels in livers and kidneys.     

Sarcomere shortening and tension development during ‘isometric’ tetanus of muscle

Summary Laser diffraction and tension measurements from frog muscle during isometric tetanus reveal that the sarcomeres contract more rapidly than tension develops.Supported by the Australian Research Grants Committee and the National Health and Medical Research Council.     

Effect of ascorbic acid on biotransformation and modification of the toxicity of mercurials in goldfish (Carassius auratus)

Summary Ascorbic acid mediated a small but significant degradation of methylmercury to inorganic mercury in goldfish (Carassius auratus) and reduced the toxicity of mercuric chloride despite its substantial conversion into organic form. This investigation was supported by a grant from the Fishing Industry Research Account of the Australian Department of Primary Industry.     

An Argentine ant aggregation factor

Summary (Z)-9-Hexadecenal, a general aggregation factor of the Argentine ant,Iridomyrmex humilis, has been isolated and chemically characterized. It is implicated as a component of the trail-pheromone complex on evidence that it is a constitutent of the ventral gland secretion, and that it both activates and attractsI. humilis workers.Acknowledgments. We thank the Australian Research Grants Committee, and the Reserve Bank of Australia, Rural Credits Development Fund for financial support.     

Evolutionary implications of ascorbic acid production in the Australian lungfish

Summary It is shown that the Australian lungfish (Neoceratodus forsteri) synthesizes ascorbic acid in its kidney, suggesting that ascorbic acid synthesis started before the origin of the tetrapods.Acknowledgments. We would like to thank Dr G.C. Grigg, University of Sydney, Mr R. B. Humphries, Dr P.A. Janssens and Dr C.H. Tyndale-Biscoe, Australian National University, and Dr. M. Griffiths and J.C. MacIlroy C.S.I.R.O., Division of Wildlife Research for supplying the tissue.     

Muscle crossbridge action in excitation and relaxation

Summary Pulse-propagation measurements on a muscle stimulated into tetanus show that the stiffness develops earlier and starts to relax later than the tension. It is concluded that the myosin heads which move towards the actin filaments during excitation become mechanically attached to them.We gratefully acknowledge financial help from the Australian Research Grants Committee.     

Changes of hormonal status in young mice by restricted caloric diet. Relation to lifespan extension. Preliminary results

Summary The maintainance of mice on a reduced caloric diet for 6 weeks starting from weaning time produces persistent changes in their hormonal status as reflected by differences in blood levels of gonadal and adrenal steroids. The changes might express a permanently different hypothalamic regulation. This might accoutn for a prolongation of their life span.This work has been supported by the Swiss National Fund for Scientific Research, grant No. 3.8750.72. I thank Miss M. Hämmerli of Ciba-Geigy AG, Basel, for her participation in the low caloric diet experiments.     

What distinguishes cosmopolitan and endemicDrosophila species?

Summary CosmopolitanDrosophila species can survive wide ecological tolerances measured by resistance to desiccation/temperature extremes compared with endemic rain forest species. This, rather than any genetic features, is important in helping to explain the widespread distributions of cosmopolitan species.We thank Dr Lee Ehrman for cultures ofD. paulistorum, and the Australian Research Grants Committee for financial support.     

Comparison of sterols from a phytophagous and predacious species of the family coccinellidae

Summary The sterols of a phytophagous and a predacious species of the family Coccinellidae were found to be quite different from each other, indicating that adaptation to different diet regimens is reflected in the utilization and metabolism of dietary sterols.We thank Dr George Angalet, USDA Beneficial Insects Research Laboratory, Federal Research, SEA, Newark, DE, for providing us with the adultCoccinella septempunctata used in this study.     

Maternal influences on cardiovascular pathophysiology

Elevated blood pressure (BP) is of special clinical significance because of its association with pathophysiologies such as heart disease, renal failure, and stroke. We described the development of a protocol for use with hypertensive rats in which prepubertal exposure to a high salt (8% NaCl) diet results in a pathophysiological syndrome including rapid increase in BP, failure to maintain normal weight gain, renal damage, cerebrovascular lesions, and early mortality. These phenomena are described for the inbred spontaneously hypertensive rat (SHR), and for reciprocal F₁ hybrids of a cross between SHR and the Dahl salt-sensitive (SS/Jr) inbred strain. The study with reciprocal F₁s revealed striking effects of maternal environment on pathophysiological response to a high salt diet. F₁s nurtured by SHR mothers weighed less at 35 days of age, and after exposure to the high salt diet suffered more rapid BP increases, greater incidence of stroke, body weight loss, and mortality, than F₁s nurtured by SS/Jr dams. These results suggest that maternal mediation of the nutritional status of the animal may play an important role in determining susceptibility to elevated BP and subsequent pathophysiology associated with exposure to a high salt diet. The implication of these findings for human hypertension is briefly discussed.     

Dietary restriction and fetal development

Summary The effect of deficient nutrition of pregnant Wistar rats on the fetal weight has been studied. It has been established that the fetal weight of the group of rats fed with a restricted amount of stock diet lags behind the fetal weight of the group receiving unrestricted amounts of the same stock diet. The differences in weight between the 2 groups were, on each day of the observation period, significant at the level of p<0.05 and p<0.01, respectively.This work was supported by a grant of the Republic Research fund of Croatia No. 18-04-06/19-1975.     

Sterilising activity of methoprene and hydroprene inTribolium castaneum (Herbst)

Summary The productivity ofT. castaneum adults, previously reared in flour incorporating either the IGR methoprene or hydroprene, was found to be impaired depending on the concentration of the IGR in the flour, whether or not the individual was morphologically deformed, and its sex.The authors are indebted to Mr P. B. Du Guesclin for technical assistance, and Dr J. Diekman, Zoecon Corporation, California, for supplying the IGRs. This work was financed in part by the Australian Wheat Industry Research Council.     

Changes in serum proteins and in major liver constituents following carbon tetrachloride and a high-fat choline-free diet in rats

Summary Both carbon tetrachloride and a high-fat, low-protein choline-free diet cause hepatomegaly in rats due to an accumulation of both lipids and proteins with a concomitant increase in deoxyribonucleic acid content. CCl₄ causes a decline in hepatic glycogen. Serum albumin level is decreased in CCl₄-treated rats and increased in those fed the experimental diet.     

On the location of the tetrapyrrole macrocycle of chlorophyll a in phospholipid vesicles and in hexadecane

Summary The state of chlorophyll a in phosphatidylcholine vesicles was examined. The results indicate that the chlorophylls are present in monomeric form. A kinetic study of chlorophyll reactions with K₂S₂O₈ and piperidine showed that these substances react with the porphyrin rings of pigments located on both vesicle faces, most probably within the polar headgroup region.Acknowledgments. This work was supported by the Research Committee and the Biophysics Research Group, University of Québec at Trois-Rivières.     

Acetic acid vapour as a resource: Threshold differences among threeDrosophila species

Summary Acetic acid vapour is utilized as an energy source up to a threshold where it becomes a stress in 3Drosophila species. The threshold ranking isD. melanogaster» D. simulans>D. immigrans, which qualitatively parallels that for ethanol. The capacity to use nutritive vapours appears to be very important inDrosophila ecology.I thank Gary Spence for technical assistance, and the Australian Research Grants Committee for partial financial support.     

Cattle grazing behavior regulates tick populations

Summary Analysis of field population data showed that host-seeking larvae of the tickBoophilus microplus were less successful in attaching to their hosts when larval densities were high. Experimental results showed that cattle hosts detected and avoided high densities of larvae in pasture. The finding reveals a previously unknown population-regulating mechanism for ticks, which are important pests of livestock.Acknowledgment. The authors wish to thank G. Maywald, D. Stegeman, R. Tozer, A. Voll, G. Milne and J. Osborne who helped with the observations. The Australian Meat Research Committee (AMRC) and the Australian Centre for International Agricultural Research (ACIAR) provided some financial support for the project and A. Edwards assisted greatly with the photography.