Paragonimus ohirai: identification of nucleolar organizer regions (NORs) and silver nitrate staining pattern in spermatogenesis

AgNOR/P53 expression compared with different grades in bladder carcinoma

OBJECTIVE

The aim of this study is to assess the relation between silver-strained nucleolar organizer regions (AgNOR)/P53 expression and urothelial neoplasm of the bladder which graded according to the WHO/ISUP tumor grading system.

METHODS

Transurethral resection materials (TUR) and cystectomy specimens from 52 patients with bladder urothelial carcinomas were stained by AgNORs and analyzed immunohistochemically using an avidinbiotin peroxidase method for p53 staining and also silver for AgNORs.

RESULTS

Nuclear p53 accumulation was determined in two of 5 LMP cases (%40), in 10 of 22 LGC (%45.4), and in 8 of 25 HGC (%32). Positivity of p53 accumulation was observed in 20 (%57.7) of all cases. There was no statistically significant relationship between AgNOR score of p53(+) and p53(-) cases. There was no correlation between LGC and LMP, also between LGC and HGC (p > 0.05), but a meaningful relationship was found between LMP and HGC (p = 0.03). Association between P53 and grade, AgNOR value and grade, p53 and AgNOR was found statistically insignificant.

CONCLUSIONS

Although we found a statistically significant correlation between AgNOR count of LMP and HGC, this study did not show a satisfying correlation between AgNOR, p53 and any grade of urothelial carcinoma.

Mutation scanning analysis of sequence heterogeneity in the second internal transcribed spacer (rDNA) within some members of theHypodontus macropi (Nematoda: Strongyloidea) complex

Single-strand conformation polymorphism analysis was employed to investigate sequence variation in the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA within and among individuals representing three operational taxonomic units (OTUs) of Hypodontus macropi from different species of Australian macropodid marsupials. Of the 96 nematodes analysed, totals of 3 (OTU1 from Petrogale persephone), 10 (OTU2 from Macropus robustus) and 7 (OTU9 from Macropus rufus) representative individuals were selected for DNA sequencing to characterise and estimate the magnitude of nucleotide variation in the ITS-2. While no unequivocal nucleotide difference in the ITS-2 was detectable within OTU1, most sequence variation (3/44.7%) detected within OTU2 and OTU9 was related chiefly to dinucleotide (CA, TA, or a combination of both) differences. This microsatellite variability in some H. macropi OTUs suggests that the ITS-2 rDNA may be subjected to slippage events during DNA replication, resulting in short dinucleotide repeat tracts being dispersed throughout the ITS-2 lineages, or possibly transposition and/or crossing-over events. Nucleotide variation in the ITS-2 of individual OTUs was related to the proposed secondary structure for the precursor ribosomal RNAs. Most of the sequence heterogeneity or polymorphism within OTU2 and OTU9 occurred in loops or bulges of the predicted secondary structure, which appear not to be under functional constraint. The findings of this study have implications for investigating speciation events and population differentiation in nematodes at the molecular level.

Genomes of Paragonimus westermani and related species: current state of knowledge

There have been few investigations of genomes of Paragonimus westermani and related species. Most studies have focussed on questions such as the identities of species and relationships among them, origins and relationships of strains with different ploidy states, and the characterisation of genes producing immunologically significant proteins. In the context of these questions, work on the karyotypes, nuclear and mitochondrial genomes is reviewed.

ITS-1 ribosomal DNA sequence variants are maintained in different species and strains of Echinococcus

This study investigated sequence heterogeneity in the first internal transcribed spacer (ITS-1) of ribosomal DNA within and among species and strains of Echinococcus. Different ITS-1 sequence variants exist in Echinococcus granulosus and Echinococcus multilocularis, which represent at least four evolutionary lineages: (1) a sheep strain-lineage of E. granulosus, (2) a sister lineage of a cervid and camel E. granulosus ITS-1 variants, (3) a lineage including the ITS-1 variants representing horse, bovine and camel strains of E. granulosus, as well as variants from E. multilocularis, Echinococcus oligarthrus and Echinococcus vogeli and (4) a distinct lineage of ITS-1 variants including E. granulosus strains from sheep and cervid, and E. multilocularis. At least two of the species (E. granulosus and E. multilocularis) were paraphyletic for ITS-1. Divergent ITS-1 variants from these two species shared distinct evolutionary lineages. The sequence data provided evidence that at least two turnover mechanisms, namely slippage and unequal crossing over/transposition, have led to the divergence and maintenance of sequence variants in Echinococcus species and strains.

Intra- and interindividual variation in ITS1 of paragonimus westermani (Trematoda: digenea) and related species: implications for phylogenetic studies

We investigated the utility of the ribosomal first internal transcribed spacer (ITS1) for phylogenetic studies on trematodes of the genus Paragonimus. Numerous clones containing ITS1 PCR products were sequenced for P. miyazakii, P. macrorchis, and members of the P. ohirai and P. westermani species complexes. Some additional data were obtained by direct sequencing of PCR products. The ITS1 is composed of three distinct regions: the short 5' end, followed by a tract of approximately 120 nucleotides which occurs a variable number of times in tandem, and the 3' region, which lacks repeats and is referred to as the "post-repeat" fragment. Sequences from all three regions can be aligned among the species studied. Our initial hypothesis, that the post-repeat region would be valuable for phylogenetic studies within the P. westermani complex, was proved wrong. Intraindividual sequence variation in P. westermani was sometimes greater than between individuals of the species complex. In the P. ohirai species complex, however, sequence variation within individuals was minimal. Possible reasons for these observations are discussed. We also wished to determine whether the length variants sequenced were the dominant variants present in Paragonimus species. This was done by probing Southern blots of genomic digests with an ITS1 fragment which lacks repeat sequences. There is generally greater abundance of large variants, with much lower abundance of small variants, such as those sequenced. Differences in ITS1 lengths are attributed largely to differing numbers of repeats, though some exceptions (which are discussed) were found.

Morphological features of spermatozoa of Paragonimus ohirai (Trematoda: Platyhelminthes) examined by a silver nitrate staining technique

The mature thread-like spermatozoon of Paragonimus ohirai was shown to be composed of 7 distinct segments which have morphologically different characteristics, following staining with silver nitrate. The first segment (1S) is a needle-shaped structure with a perforatorium. The 2S is composed of two filaments loosely paired; 3S consists of a somewhat coarse thread (vestige of the cytoplasmic projection); 4S is composed of two flagella tightly paired; in 5S, two silver-positive filaments are independently seen as in 2S; 6S has a 'spiral' structure composed of two flagella; in 7S, two filaments are seen dissociated from each other. The sperm nucleus exists within the 'spiral' structure of 6S and this structure may serve to hold and/or protect the nucleus. The technique presented here is useful for gross morphological observations of the long sperm of flatworms.