Two new ballistoconidium-forming yeast species, Bullera melastomae and Bullera formosana, found in Taiwan

Two yeast strains, the cells of which contained xylose and Q-10 as the major ubiquinone, were isolated from a plant leaf collected in Taiwan. These yeasts were found to represent two new species of the genus Bullera in the Hymenomycetes. Identification was based on the sequence analysis of the 18S rDNA, the internal transcribed spacer (ITS) regions and the D1/D2 domain of 26S rDNA. The yeasts are named Bullera melastomae sp. nov. and Bullera formosana sp. nov. In the phylogenetic trees based on 18S rDNA and D1/D2 domain of 26S rDNA sequences, these two species constitute a cluster connected with Dioszegia cluster in the Cryptococcus luteolus lineage.     

Bullera begoniae sp. nov. and Bullera setariae sp. nov., two new species of ballistoconidium-forming yeasts in the Bullera variabilis (Bulleribasidium) cluster isolated from plants in Taiwan

Two strains of xylose-containing and Q-10-having ballistoconidiogenous yeasts isolated from plant leaves collected in Taiwan were found to represent two new species of the genus Bullera. In the phylogenetic trees based on the sequence analysis of 18S rDNA and D1/D2 domain of 26S rDNA, these species are located in the Bullera variabilis (Bulleribasidum) cluster in Hymenomycetes. They are described as Bullera begoniae sp. nov. and Bullera setariae sp. nov., respectively.     

Cutting Edge: Allele-specific and peptide-dependent interactions between KIR3DL1 and HLA-A and HLA-B

Although it is clear that KIR3DL1 recognizes Bw4(+) HLA-B, the role of Bw4(+) HLA-A allotypes as KIR3DL1 ligands is controversial. We therefore examined the binding of tetrameric HLA-A and -B complexes, including HLA*2402, a common Bw4(+) HLA-A allotype, to KIR3DL1*001, *005, *007, and *1502 allotypes. Only Bw4(+) tetramers bound KIR3DL1. Three of four HLA-A*2402 tetramers bound one or more KIR3DL1 allotypes and all four KIR3DL1 allotypes bound to one or more HLA-A*2402 tetramers, but with different binding specificities. Only KIR3DL1*005 bound both HLA-A*2402 and HLA-B*5703 tetramers. HLA-A*2402-expressing target cells were resistant to lysis by NK cells expressing KIR3DL1*001 or *005. This study shows that HLA-A*2402 is a ligand for KIR3DL1 and demonstrates how the binding of KIR3DL1 to Bw4(+) ligands depends upon the bound peptide as well as HLA and KIR3DL1 polymorphism.     

Induction of the acrosome reaction in black tiger shrimp (Penaeus monodon) requires sperm trypsin-like enzyme activity

Trypsin-like enzymes in egg water (EW), a natural acrosome reaction (AR) inducer, are known for their importance in shrimp AR. In this report, we describe a unique phenomenon of the AR of black tiger shrimp (Penaeus monodon) sperm. It was completed within 45-60 sec and comprised only the acrosomal exocytosis and depolymerization of the sperm head anterior spike. We used peptidyl fluorogenic substrates to show the presence of trypsin-like enzymes in P. monodon EW and sperm, but minimal activities of chymotrypsin-like enzymes. In sperm, these trypsin-like enzymes existed both on the sperm surface and in the acrosome. The acrosomal enzyme was revealed as a 45-kDa band by fluorogenic substrate in-gel zymography. Although EW possessed high trypsin-like enzyme activities, they were not essential for the AR induction; EW pretreated with an irreversible trypsin inhibitor, or heat-inactivated EW (HI-EW), to abolish the trypsin-like activities could still induce the AR. The HI-EW-induced AR was inhibited by the presence of a membrane impermeant soybean trypsin inhibitor (SBTI) in the sperm suspension, indicating the significance of sperm-borne trypsin-like enzymes (on the surface and/or in the acrosome) in this AR process. However, pretreatment of sperm with SBTI followed by its removal from the suspension still allowed the AR to occur within 5 min of sperm exposure to HI-EW. Since trypsin-like activity of the SBTI-pretreated sperm surface at 5 min after SBTI removal was at the minimal level, our results suggest the importance of the acrosomal trypsin-like enzyme in the AR process.     

Molecular modification of Penaeus monodon sperm in female thelycum and its consequent responses

Using Penaeus monodon as the model, we demonstrated the molecular changes and the mechanism of thelycal-dependent sperm modification resulting in an enhanced acrosome reaction (AR) response. Attention was paid to the modification of the sperm plasma membrane which was mediated through an adsorption or removal of sperm peripheral and integral membrane proteins as indicated by the different profiles of these proteins in spermatophore (S) and thelycal (T) sperm. In vitro adsorption of Alexa-488 conjugated T proteins onto the entire S-sperm surface confirmed protein transfer in a time-dependent manner. Specific anchoring of 83 and 140 kDa proteins to sperm peripheral proteins as well as 53/55 and 60 kDa proteins to sperm lipids was demonstrated. Apart from membrane modification, a substantial increase in protein tyrosine phosphorylation was shown to be closely associated with T-dependent sperm modification event. The physiological significance of this sperm modification in enhancing sperm AR response, which required at least 3 days of T residence in order for the sperm to gain a complete AR response, was also elucidated.     

Sporobolomyces magnisporus sp. nov., a new yeast species in the Erythrobasidium cluster isolated from plants in Taiwan

Two strains of yeasts that contain Q-10 as the major ubiquinone, lack cellular xylose and produce large bilaterally symmetrical ballistoconidia were isolated from plants collected in a protected subtropical rain forest in Taiwan and were found to represent a new species. The taxonomic properties of this species coincide with the genus Sporobolomyces, so it is described as Sporobolomyces magnisporus sp. nov. In phylogenetic trees based on the nucleotide sequences of 18S ribosomal DNA and D1/D2 domain of 26S ribosomal DNA, this species is located in the Erythrobasidium cluster.     

Sporobolomyces diospyroris sp. nov., Sporobolomyces lophatheri sp. nov. and Sporobolomyces pyrrosiae sp. nov., three new species of ballistoconidium-forming yeasts in the Agaricostilbum lineage isolated from plants in Taiwan

Three strains of xylose-lacking and ubiquinone-10-having ballistoconidium-forming yeasts isolated from plant leaves collected in Taiwan were found to represent respective new species. In phylogenetic trees constructed based on the nucleotide sequences of 18S rDNA and D1/D2 domain of 26S rDNA, they were located in the Agaricostilbum lineage (Agaricostilbum/Bensingtonia cluster). Since the taxonomic properties of these species coincide with those of the genus Sporobolomyces, they are described as Sporobolomyces diospyroris sp. nov., Sporobolomyces lophatheri sp. nov. and Sporobolomyces pyrrosiae sp. nov., respectively.