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R A Hayes

Publications and source records attributed to R A Hayes.

7 recordsLinked to original sources
PubMed2002

Semiochemicals and social signaling in the wild European rabbit in Australia: I. Scent profiles of chin gland secretion from the field.

The European rabbit (Oryctolagus cuniculus) uses the secretion of the chin gland in the maintenance of social status. Previous work has concentrated on secretion collected directly from the animal. In this study, the analysis was conducted by collecting scent marks made by free-ranging animals. Scent marks were found to be concentrated at the center of the area controlled by a social group, and at the boundaries between two adjacent social groups. Only the mark from dominant animals could be identified. Marks were also collected from the skin of rabbits, where they had been placed by the dominant individual. The mark found on the head of a subordinate animal may, in the future, be used to identify the dominant animal of the social group, who placed the mark.

Animal Communication↗
PubMed2002

Semiochemicals and social signaling in the wild European rabbit in Australia: II. Variations in chemical composition of chin gland secretion across sampling sites.

The volatile components of the chin gland secretion of the wild European rabbit, Oryctolagus cuniculus (L.), were investigated with the use of gas chromatography. Studies of the chemical nature of this secretion by previous workers demonstrated that it was important in the maintenance of social structure in this species. This study identified 34 different volatile components that consist primarily of aromatic and aliphatic hydrocarbons. Especially common are a series of alkyl-substituted benzene derivatives that provide most of the compound diversity in the secretion. Samples of chin gland secretion collected from animals at three different geographical locations, separated by more than 100 km, showed significant differences in composition. This work suggests that variation among populations needs to be considered when undertaking semiochemical research. Alternate nonparametric methods are also used for the analysis of chromatographic data.

Animals↗
PubMed2001

Biological control of the rabbit in Australia: lessons not learned?

The story of the spread of the European rabbit across Australia, and of the two viruses used to control it, is an interesting way to look at some of the issues associated with biological control. What can be learned from the way this system developed, and what has been learned, or not learned, from the mistakes made? Here, we look at these events and examine what insights can be gained from this history.

Animals↗
PubMed1993

Pregnancy can be established in superovulated adult rats treated with progesterone and an aromatase inhibitor.

An adult superovulated rat model has been developed and is characterized by high ovulation rates, early morphological degeneration of embryos, complete embryo loss within 48 hours of conception and elevated peripheral estradiol(E2)/progesterone(P4) ratios. In this study, three trials were conducted using the superovulated adult rat model. First, control naturally cycling rats were compared with superovulated rats supplemented with 1 mg P4 on days 0-3 of pregnancy. A sperm positive vaginal smear is designated as day 0 of pregnancy. The P4 treated rats demonstrated improved embryo retrieval on day 1 of pregnancy, continued embryo recovery with a decrease in normal morphologic characteristics of integrity on day 2, with nearly total embryo loss by day 3. On each day, P4 levels were elevated 2-3 times over control. The second trial compared 3 groups of rats, 1) naturally cycling, 2) superovulated unsupplemented and 3) superovulated rats supplemented with 1 mg P4/rat/day and the aromatase inhibitor, 4-hydroxyandrostenedione (4-OHA), 12.5 mg/rat/day. The superovulated unsupplemented rats had no embryo recovery after day 2 of pregnancy, while the P4 and 4-OHA treated rats showed a variable ability to maintain normally developing embryos through day 4 of pregnancy. E2 levels were elevated in both superovulated groups on days 1-4 of pregnancy as were P4 levels on days 2-4. The E2/P4 ratio was significantly lowered only on day 1 of pregnancy in the P4 and 4-OHA treated group. The third trial demonstrated implantation in 50% of the superovulated rats supplemented with P4 and 4-OHA. In conclusion, implantation in the superovulated adult rats can occur with P4 and 4-OHA supplementation, however, this biologic phenomenon could not be explained by obvious changes in peripheral E2 and P4 levels.

Analysis of Variance↗