Reproduction in the marsupial dibbler, Parantechinus apicalis; differences between island and mainland populations.

Details of the reproductive endocrinology of the dibbler, Parantechinus apicalis, an endangered member of the Family Dasyuridae, are presented from two geographically-separated populations, living either on the mainland or on islands in Jurien Bay, Western Australia. Plasma free cortisol in males measured in the island population during 1998/9 did not differ between the breeding and non-breeding season, but during the March rut in 2000, when males died after breeding, free cortisol levels were significantly raised. Post-mating mortality in dibbler males is facultative, rather than obligatory and the cortisol data implicate the same physiological sequelae described in other dasyurids. In females, a single annual oestrus was recorded during late summer to autumn in both populations with an onset earlier by 12 days in the mainland animals. Faecal steroids excreted as progesterone metabolites (PM) and oestradiol-17ß were measured during the annual oestrous period and showed significantly higher PM concentrations in island animals. Oestradiol, although raised, was not different between the two populations. A profile of PM levels throughout gestation revealed a small peak at the time of ovulation, followed by slowly rising levels to peak 8 days before birth, indicating slow development of the corpora lutea. Using collective data, the presumptive day of ovulation could be identified, allowing the calculation of a presumptive gestation length of 45days in dibblers from mainland populations. This gestation length compares with that of a related species, Pseudantechinus macdonnellensis, reported at 45-55 days. A surprising finding is the significantly shorter gestation period of approximately 38 days in island animals compared with those from the mainland. This and other differences between reproductive parameters of island and mainland populations are discussed in the context of the 'island syndrome'.

Sequence variation in the early genes E1E4, E6 and E7 of human papilloma virus type 6.

The majority of condylomata acuminata (anogenital warts) are caused by infection with Human Papilloma Virus type 6 (HPV-6). We have sequenced the HPV-6 early genes, E1-E4, E6 and E7 from wart biopsy DNA samples sourced from the UK and USA and derived a consensus sequence for these genes and the proteins they encode. When compared to the prototype HPV-6b sequence, published over 12 years ago, the E1-E4 consensus sequence showed 3/91 (3.3%) amino acid changes, the E6 consensus sequence showed 1/150 (0.7%) changes and the E7 consensus sequence showed 1/98 (1.0%) changes. Since many of the early gene sequences from biopsy material were more similar to the HPV-6a subtype than HPV-6b, this data supports the use of HPV-6a as the HPV-6 prototype.

Expression and purification of p24, the core protein of HIV, using a baculovirus-insect cell expression system.

The baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV) has been genetically manipulated to yield a recombinant virus capable of expressing p24, the major core protein of HIV-1, in insect cell culture. The expressed product is a p24 protein flanked by short regions of p17 at the amino terminus and p12 at the carboxy terminus. It has been identified and characterized using monoclonal antibodies on Western blots and by amino-terminal sequence analysis. The presence of p24 in the soluble fraction of infected cells following lysis by detergent or sonication, combined with a high level of expression (in excess of 50 mg/l of culture) facilitates the enrichment of large quantities of recombinant HIV antigen in a simple two-step procedure involving ammonium sulphate fractionation and gel filtration. p24 antigen purified in this way is shown to be an efficient diagnostic reagent.