Reverse transcriptase activity and untranslated region sharing of a new RTE-like, non-long terminal repeat retrotransposon from the human blood fluke, Schistosoma japonicum

A new RTE-like, non-long terminal repeat retrotransposon, termed SjR2, from the human blood fluke, Schistosoma japonicum, is described. SjR2 is similar to3.9 kb in length and is constituted of a single open reading frame encoding a polyprotein with apurinic/apyrimidinic endonuclease and reverse transcriptase domains. The open reading frame is bounded by 5'- and 3'-terininal untranslated regions and, at its 3-terminus, SjR2 bears a short (TGAC)(3) repeat. Phylogenetic analyses based on conserved domains of reverse transcriptase or endonuclease revealed that SjR2 belonged to the RTE clade of non-long terminal repeat retrotransposons. Further, SjR2 was homologous, but probably not orthologous, to SR2 front the African blood fluke, Schistosoma mansoni; this RTE-like family of non-long terminal repeat retrotransposons appears to have arisen before the divergence of the extant schistosome species. Hybridisation analyses indicated that similar to 10,000 copies of SjR2 were dispersed throughout the S. japonicum chromosomes, accounting for up to 14% of the nuclear genome. Messenger RNAs encoding the reverse transcriptase and endonuclease domains of SjR2 were detected in several developmental stages of the schistosome, indicating that the retrotransposon was actively replicating within the genome of the parasite. Exploration of the coding and non-coding regions of SjR2 revealed two notable characteristics. First, the recombinant reverse transcriptase domain of SjR2 expressed in insect cells primed reverse transcription of SjR2 mRNA in vitro. By contrast, recombinant SjR2-endonuclease did not appear to cleave schistosome or plasmid DNA. Second, the 5'-untranslated region of SjR2 was >80% identical to the 3-untranslated region of a schistosome heat shock protein-70 gene (hsp-70) in the antisense orientation, indicating that SjR2-like elements were probably inserted into the non-coding regions of ancestral S. japonicum HSP-70, probably after the species diverged from S. mansoni. (C) 2002 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.

Isolation and characterization of nine microsatellite loci from the Hawaiian grouper Epinephelus quernus (Serranidae) for population genetic analyses

The availability of variable genetic markers for groupers (Serranidae) has generally been limited to mitochondrial DNA. For studies of population genetic structure, more loci are usually required; particularly useful are those that are nuclear in origin such as microsatellites. Here, we isolated and characterized 9 microsatellite loci from the endemic Hawaiian grouper Epinephelus quernus using a biotin-labeled oligonucleotide-streptavidin-coated magnetic bead approach. Of the 20 repeat-containing fragments isolated, 15 had sufficient flanking region in which to design primers. Among these, 9 produced consistent polymerase chain reaction product, and 6 were highly variable. These 6 loci were all composed of dinucleotide repeats, with the number of alleles ranging from 6 to 18, and heterozygosities from 33.3% to 91.7%. The high levels of variability observed should make these markers useful for population genetic studies of E. quernus, and potentially other epinephelines.

Auditor conservatism and voluntary disclosure: Evidence from the Year 2000 systems issue

This study further examines the phenomenon of conservative auditor behaviour by considering the level of voluntary disclosure of Year 2000 remediation information in company annual reports. Previous studies have provided evidence of conservative auditor behaviour by examining the link between Big 6 auditor choice and accruals (Francis and Krishnan 1999; Becker et al., 1998; Defond and Subramanyam 1998). Protecting their reputation capital increases Big 6 auditor incentives to act conservatively to avoid litigation risk. We propose and find that Big 6 auditor clients disclose more Year 2000 remediation information than non–Big 6 auditor clients.

Poracanthodid acanthodian from the Upper Silurian (Pridoli) of Nevada

Dissociated remains of the acanthodian Poracanthodes punctatus are described from Upper Silurian (Pridoli) limestones of the Roberts Mountains Formation at Pete Hanson Creek, Eureka County, Nevada. The vertebrate microremains in sample residues comprise scales, a dentigerous jaw bone fragment, and a fin spine fragment assigned to P. punctatus, plus one possible acanthothoracid placoderm scale. Some macroremains from the same locality are also assigned to P. punctatus. This taxon has been nominated as, a zone fossil for the Silurian vertebrate biozonal scheme, and its presence has been recorded throughout the circum-Arctic region. Identification of the taxon in Nevada extends its known geographic range.

A new species of Dactylostomum Woolcock, 1935 (Digenea: Opecoelidae) from the goatfish Upeneichthys lineatus (Bloch & Schneider) (Mullidae) in Western Australian waters

Dactylostomum nicolli n. sp. is described from the intestine of the goatfish Upeneichthys lineatus (Bloch & Schneider) (Mullidae) caught off Point Peron, Western Australia. The problem of assigning the new species to the appropriate genus, especially with regard to its close resemblance to Paropecoelus Pritchard, 1966, which also infects goatfishes, is discussed. This is the second report of Dactylostomum Woolcock, 1935 from an Australian marine fish. The new species is distinguished by its elongate form, simple ventral sucker papillae and irregularly shaped ovary.

Lepocreadiidae (Digenea) from the batfish of the genus Platax Cuvier (Teleostei : Ephippidae) from the southern Great Barrier Reef, Queensland, Australia

The following species are described from Platax spp.: Neomultitestis aspidogastriformis n. sp., from P. teira, off Heron Island, Queensland, which can be distinguished from its congeners by the transversely elongate ventral sucker divided into three loculi and probably by testis number; Multitestis magnacetabulum Mamaev, 1970, from P. teira, off Heron Island, Queensland; Diploproctodaeum rutellum ( Mamaev, 1970), from P. teira, off Heron Island, Queensland; Diploproctodaeum tsubameuo n. sp., from P. batavianus, from the Swain Reefs, off Queensland, which differs from its congeners in its overlapping, posteriorly attenuated testes and 38-55 ovarian lobes; and Diplocreadium sp., from P. batavianus, from the Swain Reefs, off Queensland.

Enhanced vector competence of Aedes aegypti (Diptera : Culicidae) from the torres strait compared with mainland Australia for dengue 2 and 4 viruses

Australian Aedes aegypti (L.) mosquitoes colonized from the Torres Strait and three mainland localities (Charters Towers, Townsville, and Cairns) were fed on blood suspensions containing dengue virus type 2 (DEN-2) or dengue virus type 4 (DEN-4). Variation was found in oral susceptibility to DEN-2 (59-99% infection) and DEN-4 (28-79% infection) among Ae. aegypti assayed for virus at 8, 12, 16, or 20 d after ingestion of infected blood. Torres Strait Ae. aegypti were the most susceptible to DEN-2 and were significantly more efficient in transmission to capillary tube at 16 d (76% transmission) than mainland Ae. aegypti populations (20-28% transmission). Torres Strait Ae. aegypti were also the most susceptible to DEN-4, although transmission did not vary significantly from mainland populations at 16 d (12% compared with 0-4%) or 20 d (16% compared with 4-16%). Disseminated infection (i.e., leg infection) with either DEN-2 or DEN-4 was not an accurate predictor of transmission potential. This study demonstrates differences among Australian Ae. aegypti populations in vector competence for DEN-2 and DEN-4. Torres Strait Ae. aegypti were more frequently infected and able to transmit DEN-2 at higher rates than mainland populations. These data indicate that the Torres Strait region is potentially more receptive to dengue transmission than mainland localities, a finding discussed with respect to past outbreaks.

4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes from the cane beetle Antitrogus parvulus - Cuticular hydrocarbons with unprecedented structure and stereochemistry

[GRAPHICS] The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus were deduced to be 4,6,8,10,16,18-hexa- and 4,6,8,10,16-pentamethyldocosanes 2 and 3, respectively. Isomers of 2,4,6,8-tetramethylundecanal 27, 36, and 37, derived from 2,4,6-trimethylphenol, were coupled with the phosphoranes 28 and 29 to furnish alkenes and, by reduction, diastereomers of 2 and 3. Chromatographic and spectroscopic comparisons confirmed 2 as either 6a or 6b and 3 as either 34a or 34b.

Novel sesquiterpenes from the fungus lactarius piperatus

Four novel sesquiterpenes, namely 7alpha,8beta,13-trihydroxy-5,13-marasmanolide (2), isoplorantinone (5), 4,8,14-trihydroxyilludala-2,6,8-triene (6), and 8-hydroxy-8,9-secolactara-1,6-dien-5,13-olide (10), together with six known ones, 7alpha,8beta-dihydroxy-5,13-marasmanolide (1), 7alpha,8alpha-dihydroxy-5,13-marasmanolide (3), isolactarorufin (4), blennin A (7), blennin D (8), and lactarorufin (9), were isolated from the ethanolic extract of Lactarius piperatus. The structures of these sesquiterpenes, representing diversified structural types, were determined mainly by spectroscopic methods, especially 2D-NMR techniques. The structure of 6 was further confirmed by a single-crystal X-ray-diffraction determination.

The value of idiosyncratic markers and changes to conserved tRNA sequences from the mitochondrial genome of hard ticks (Acari: Ixodida: Ixodidae) for phylogenetic inference

Idiosyncratic markers are features of genes and genomes that are so unusual that it is unlikely that they evolved more than once in a lineage of organisms. Here we explore further the potential of idiosyncratic markers and changes to typically conserved tRNA sequences for phylogenetic inference. Hard ticks were chosen as the model group because their phylogeny has been studied extensively. Fifty-eight candidate markers from hard ticks ( family Ixodidae) and 22 markers from the subfamily Rhipicephalinae sensu lato were mapped onto phylogenies of these groups. Two of the most interesting markers, features of the secondary structure of two different tRNAs, gave strong support to the hypothesis that species of the Prostriata ( Ixodes spp.) are monophyletic. Previous analyses of genes and morphology did not strongly support this relationship, instead suggesting that the Prostriata is paraphyletic with respect to the Metastriata ( the rest of the hard ticks). Parallel or convergent evolution was not found in the arrangements of mitochondrial genes in ticks nor were there any reversals to the ancestral arthropod character state. Many of the markers identified were phylogenetically informative, whereas others should be informative with study of additional taxa. Idiosyncratic markers and changes to typically conserved nucleotides in tRNAs that are phylogenetically informative were common in this data set, and thus these types of markers might be found in other organisms.

Effects of additional sequences directly downstream from the AUG on the expression of GFP gene

We have studied the expression of the green fluorescent protein (GFP) gene to gain more understanding of the effects of additional nucleotide triplets (codons) downstream from the initiation codon on the translation of the GFP mRNA in CHO and Cos1 cells. A leader sequence of six consecutive identical codons (GUG, CUC, AGU or UCA) was introduced into a humanized GFP (hm gfp) gene downstream from the AUG to produce four GFP gene variants. Northern blot and RT-PCR analysis indicated that mRNA transcription from the GFP gene was not significantly affected by any of the additional sequences. However, immunoblotting and FACS analysis revealed that AGU and UCA GFP variants produced GFP at a mean level per cell 3.5-fold higher than the other two GFP variants and the hm gfp gene. [35S]-Methionine labeling and immunoprecipitation demonstrate that GFP synthesis was very active in UCA variant transfected-cells, but not in GUG variant and hm gfp transfected-cells. Moreover, proteasome inhibitor MG-132 treatment indicated that the GFPs encoded by each of the GFP variants and the hm gfp were equally stable, and this together with the comparable mRNA levels observed for each construct suggested that the different steady-state GFP concentrations observed reflected different translation efficiencies of the various GFP genes. In addition, the CUC GFP variant, when transiently transfected into CHO or COS-1 cells, did not produce any GFP expressing cells (fully green cells), and the GUG variant produced GFP expressing cells less than 10%, while AGU and UCA GFP variants up to 30–35% in a time course study from 8 to 36 h posttransfection. Analysis of the potential secondary structure of the GFP variant mRNAs especially in the translation initiation region suggested that the secondary structure of the GFP mRNAs was unlikely to explain the different translation efficiencies of the GFP variants. The present findings indicate that a change of the initiation context of the GFP gene by addition of extra coding sequence can alter the translation efficiency of GFP mRNA, providing a means of more efficient expression of GFP in eukaryotic cells.