Dioecy, a rather rare phenomenon in the plant kingdom seems to be more prevalent on oceanic islands. The high incidence of dioecy on these islands could result from dioecious colonists among which a small percentage show leaky dioecy, which is an ability to self-fertilise. In this study, we report the occurrence of leaky dioecy in one of the 11 extant Diospyros species endemic to Mauritius. Female flowers on the leaky dioecious plants were artificially pollinated and bagged. Populations of D. egrettarum, D. leucomelas, D. melanida, D. revaughanii, D. tessellaria were all male-biased with a ratio of at least 2:1. Leaky dioecy occurred only in one Diospyros species, D. egrettarum where hermaphrodite plants represented 2% of the populations studied. Seeds collected from them had the same germination rate (approximately 40%) as the ones obtained from strictly unisexual female plants of D. egrettarum. The fact that leaky dioecy led to the production of fertile seeds opens the possibility that a single pioneer Diospyros plant could have played a major role in the establishment of reproductively viable populations in Mauritius.

The properties of temperature-sensitive mutants of adenovirus type 2 representing 12 complementation groups were studied. All mutants were normal with respect to adsorption as measured by viral inclusion formation and viral DNA synthesis as shown by velocity sedimentation in alkaline sucrose gradients. One mutant, however, formed viral inclusions of altered morphology at the nonpermissive temperature. The synthesis of the major capsid proteins was examined by immunodiffusion. On this basis, the complementation groups could be arranged as follows: (i) one group was negative for all three proteins; (ii) three groups failed to synthesize penton bases; (iii) eight groups were positive for hexons, pentons, and fibers. The assembly of virus particles at 39 C was examined by equilibrium sedimentation in CsCl; three groups were found defective, whereas two of the penton-negative groups were positive for virion production. Tests of the thermolability of virions at 50 C revealed eight groups labile whereas the remainder were insensitive to heat inactivation. None of five mutants inoculated in newborn rats induced tumors, although three of them were capable of in vitro transformation.

The Diospyros (Ebenaceae) species which colonized the Mascarene Islands, namely Mauritius, Reunion and Rodrigues, have been decimated over the years by human settlements. Of the 14 endemic species that have been described and collected for herbaria, Diospyros angulata is now believed to be extinct in Mauritius. The phylogenetic relationships of the 14 Diospyros species were determined using maximum parsimony analysis of 35 morphological characters. This analysis separated the Mascarene Diospyros into two major clades, with D. revaughanii , D. egrettarum and D. leucomelas grouped in the same strongly supported most basal clade while the rest of the species formed the other major clade. High bootstrap values were obtained for the sister species D. angulata and D. boutonania , and the clade clustering the upland species D. neraudii , D. nodosa and D. pterocalyx . There was also relatively strong support for the clade comprising D. hemiteles and D. melanida , which are located in mid altitude regions. These results indicate that Diospyros species most probably colonized the coastal areas of Mauritius and then moved to mid altitude habitats before finally reaching the upland regions. There are also strong indications that D. borbonica and D. diversifolia , endemic to Reunion and Rodrigues, respectively, resulted from migrations from Mauritius.

Advenovirus type 2 core proteins were studied with the aid of temperature-sensitive (ts) mutants affecting them. Cores prepared from wild-type virions with pyridine contained the structural proteins IVa2, V, VII, and X. Cores from the H2ts3 mutant contained an altered polypeptide V (50 K) of higher molecular weight and additional peptides. Ts1 virions produced at the restrictive temperature contained precores with proteins IVa2, V, pre-VI, pre-VII, and 11 K. This precore could be matured to a wild-type-like core by the adenovirus endoprotease. Of these core proteins only V, pre-VI, pre-VII, VII, and 11 K could be shown to reassociate in vitro with double-stranded heterologous DNA. Proteins IVa2 and X may bind to these core proteins rather than to the DNA directly.

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