SummaryPartial sequence analysis of the Cryptococcus neoformans MATa mating type locus revealed the presence of a gene with substantial sequence similarity to other fungal mitogen-activated protein (MAP) kinase kinase kinase (MAPKKK) genes. The C. neoformans gene, designated STE11a, showed the highest degree of similarity to the Neurospora crassa nrc-1, Schizosaccharomyces pombe byr2 and Saccharomyces cerevisiae STE11 genes. A polymerase chain reaction-mediated sib-selection technique was successfully adapted for the purpose of disrupting STE11a. C. neoformans ste11aD mutants were found to be sterile, consistent with the phenotypes of ste11 and byr2 mutants in S. cerevisiae and S. pombe respectively. Haploid ste11aD mutants were also found to be unable to produce hyphae, suggesting that the C. neoformans gene is functionally conserved when compared with its S. cerevisiae MAPKKK counterpart. Comparison of the wild-type STE11a strain with a ste11aD disruptant for virulence using the mouse model showed that the ste11aD strain was less virulent, but the difference was only minor. In spite of some of the conserved functions of STE11a , linkage analysis showed that STE11a is only found in mating type a strains. These results demonstrate that, although functionally conserved, the mating pathway in C. neoformans has a unique organization.

Two of the dominant whey proteins of the tammar wallaby, beta-lactoglobulin (BLG) and late lactation protein (LLP), have been positively identified on gradient polyacrylamide gradient gels by N-terminal protein sequencing. The origin of the electrophoretic variation present in these proteins has been found to be principally genetic. The variation was examined in 97 lactating female tammar wallabies, of which 10 were followed throughout lactation to determine if any developmental variation existed. The only distinguishable developmental difference results from the previously described appearance of LLP at the beginning of phase III of lactation (approximately 180 days after birth of the young). Electrophoretic analysis of BLG implies that it exists in monomeric, dimeric, and tetrameric forms. Very strong linkage disequilibrium, indicative of close linkage, was found between alleles at the Blg and Llp loci. Examination of their cDNA sequences suggests that LLP and BLG represent an ancient gene duplication. Both have conserved amino acid residues characteristic of the lipocalins. The results imply that the marsupial mode of lactation, and hence of reproduction, is also very ancient.