On the Phylogenetic Position of Rotifera – Have We Come Any Further?

Rotifers are bilateral symmetric animals belonging to Protostomia. The ultrastructure of the rotiferan trophi suggests that they belong to the Gnathifera, and ultrastructural similarities between the integuments and spermatozoa as well as molecular evidence strongly suggest that rotifers and the parasitic acanthocephalans are closely related and form the clade Syndermata. Here we discuss the phylogenetic position of rotifers with regard to the gnathiferan groups. Originally, Gnathifera only included the hermaphroditic Gnathostomulida and the Syndermata. The synapomorphy supporting Gnathifera is the presence of pharyngeal hard parts such as jaws and trophi with similar ultrastructure. The newly discovered Micrognathozoa possesses such jaws and is a strong candidate for inclusion in Gnathifera because their cellular integument also has an apical intracytoplasmic lamina as in Syndermata. But Gnathifera might include other taxa. Potential candidates include the commensalistic Myzostomida and Cycliophora. Traditionally, Myzostomida has been included in the annelids but recent studies regard them either as sister group to the Acanthocephala or Cycliophora. Whether Cycliophora belongs to Gnathifera is still uncertain. Some analyses based on molecular data or total evidence point towards a close relationship between Cycliophora and Syndermata. Other cladistic studies using molecular data, morphological characters or total evidence suggest a sister group relationship between Cycliophora and Entoprocta. More molecular and morphological data and an improved sampling of taxa are obviously needed to elucidate the phylogenetic position of the rotifers and identify which phyla belong to Gnathifera.     

Does the Emperor Have Any Clothes: Using Mechanistic Information or Doing Houdini Risk Assessments?

Risk assessment research rarely quells controversy. Mega-mouse, and mega-rat, experiments contradicted a threshold for carcinogenesis, yet thresholds are still argued. High to low dose continuity of response from cigarette smoking to environmental tobacco smoke, and from occupational asbestos exposure to take-home asbestos, contradict thresholds in people. Nevertheless, mechanistic hypotheses allege “Houdini Risk Assessments”, which make risks disappear or allow industries to escape from protecting workers. Despite concerns for animal-to-human extrapolations, priority occupational exposures with sufficient or substantial evidence of carcinogenicity in people not addressed by new exposure limits include silica, sulfuric acid mist, chromates, diesel particulate matter, particulate matter generally, metalworking fluids, welding fume, and formaldehyde. “Houdini Risk Assessments” are exercises in “anti-hypothesis generation”: ignore selected tumor sites and types; ignore data from people (as with formaldehyde and diesel); choose the most resistant species in laboratory tests; select biochemical parameters in which the most resistant species resembles people; assume a mechanism that gives threshold or steep exposure response for carcinogenic effect; and reduce estimated people risk by the parameter ratio to the most resistant species. NORA research should focus on quantitative reconciliation of laboratory and epidemiology studies, and develop a counter “anti-hypothesis” generation research agenda for key exposure circumstances.     

HERNIATION OF INTERVERTEBRAL DISCS—An Evaluation of the “Indirect Signs”

The incidence of so-called indirect signs of posterior herniation of an intervertebral disc in a series of working men who had no symptoms referable to the back was compared with the incidence of those signs in a group of cases in which herniation of a disc was proved at operation. There was no significant difference in incidence. In the cases in which herniation was proved at operation, it occurred no more often at a level where there was a thin disc than at a level where the disc was of normal thickness.     

Does the Genetic Code Have A Eukaryotic Origin?

In the RNA world, RNA is assumed to be the dominant macromolecule performing most, if not all, core "house-keeping" functions. The ribo-cell hypothesis suggests that the genetic code and the translation machinery may both be born of the RNA world, and the introduction of DNA to ribo-cells may take over the informational role of RNA gradually, such as a mature set of genetic code and mechanism enabling stable inheritance of sequence and its variation. In this context, we modeled the genetic code in two content variables-GC and purine contents-of protein-coding sequences and measured the purine content sensitivities for each codon when the sensitivity (% usage) is plotted as a function of GC content variation. The analysis leads to a new pattern-the symmetric pattern-where the sensitivity of purine content variation shows diagonally symmetry in the codon table more significantly in the two GC content invariable quarters in addition to the two existing patterns where the table is divided into either four GC content sensitivity quarters or two amino acid diversity halves. The most insensitive codon sets are GUN (valine) and CAN (CAR for asparagine and CAY for aspartic acid) and the most biased amino acid is valine (always over-estimated) followed by alanine (always under-estimated). The unique position of valine and its codons suggests its key roles in the final recruitment of the complete codon set of the canonical table. The distinct choice may only be attributable to sequence signatures or signals of splice sites for spliceosomal introns shared by all extant eukaryotes.     

Evaluation of the PathoTec ?Rapid I-D System”

The 10 biochemical test strips included in the PathoTec Rapid I-D System were evaluated for accuracy as compared to standard tests and for efficacy in identification of 193 gram-negative bacilli. The test agreement was 100% for oxidase and phenylalanine deaminase, 99% for indole, nitrate, and Voges-Proskauer, 98% for malonate, 97% for lysine decarboxylase, 90% for urease, 84% for H(2)S, and 75% for esculin hydrolysis. Most of the commonly isolated Enterobacteriaceae were identified correctly within 4 h. Errors in identification of Proteus morganii and P. rettgeri occurred because of positive H(2)S tests on the PathoTec strips with these organisms.     

An Evaluation of β-Propiolactone for the Sterilization of Fermentation Media

Twenty-five bacterial species were cultured in basal broth plus 1 of 19 different carbohydrates which were sterilized by Seitz filtration, autoclaving (112 C, 10 min), or exposure to 0.2% β-propiolactone (BPL). No significant differences were found either in the visual observations for acid and gas, pH, or titrable acidity determinations after 3 days of incubation with any of the three preparations tested. An effort was made to further determine the effect of BPL and heat on carbohydrates by assaying for glucose before and after treatment. Results indicated that glucose was not degraded by 0.2% BPL, however, it was shown that autoclave temperatures caused extensive degradation. Statistical treatment of the results from Warburg studies indicated that BPL-treated glucose showed no appreciable toxic effects, although the actual oxygen uptake was not as great as with Seitz- or autoclave-treated glucose. The application of the BPL sterilization process was discussed.     

Genetic Variation in Toxicant-Stressed Populations: An Evaluation of the “Genetic Erosion” Hypothesis

The question whether environmental pollution affects genetic diversity in natural populations remains unanswered to date despite the fact that genetic variation is one of the three pillars of biodiversity recognized in the Rio convention of 1993. The loss of genetic diversity in populations subjected to anthropogenic stress can be designated as “genetic erosion” and may be considered as a factor of concern in risk assessment of toxic chemicals. Theoretically there are four different ways in which toxicants can affect genetic variation: (i) by increasing mutation rates, (ii) by directional selection on tolerant genotypes, (iii) by causing bottleneck events, and (iv) by altering migration. This paper reviews studies that have documented genetic change in animal populations exposed to environmental pollution. In these studies, genetic variation is measured in a variety of ways: heritability of quantitative characters, heterozygosity of allozyme loci, haplotype diversity in mitochondrial DNA, and variability in RAPD fingerprints. Studies on cadmium tolerance of Collembola living in metal-contaminated soil suggest that strong directional selection pressure may decrease genetic variability of traits immediately linked to tolerance. Allozyme studies in fish have documented a similar decrease of genetic variation in populations living in strongly acidified waters. A correlation between RAPD-PCR-based genetic similarity and site contamination has been documented in crayfish. Overall, there is significant support for the genetic erosion hypothesis, but the issue cannot be considered settled. In most studies insufficient attention is given to factors such as population size, bottlenecks and mutation, which may influence genetic variability in addition to the toxicant selection regime. At the moment, there does not seem to be a sound scientific basis for incorporating genetic diversity measurements into risk assessment, despite the variety of easily applicable molecular techniques available. It is often not known what kind of variation is measured by these techniques (neutral or selectable) and how the markers are inherited. Given the importance of the issue, as stressed by the Rio Convention, a concentrated research effort is necessary to better define the question and find a general approach to evaluate its importance in ecological risk assessment.     

Chronostratigraphy and the Palaeoenvironment of the Bistrița Valley. New Interpretations and a Critical Retrospective Evaluation

The Carpathian Arch was certainly a difficult obstacle for the Palaeolithic communities of Eastern and Central Europe, at least during certain stages of the Upper Pleistocene glaciation, such as the Last Glacial Maximum. The density and perennity of the Palaeolithic occupations in the Bistri?a Valley were favoured by the propitious conditions of living and developing long-term survival strategies. The importance of the Bistri?a Valley lies in the fact that it is strongly embedded in the mountainous landscape, with a route extended in the Sub-Carpathian area and a generous opening towards the east to the plateau region and further towards the Great Russian Plain. The Bistri?a Valley is a landmark of the Romanian Palaeolithic due to the number of investigated Palaeolithic settlements, the wealth and variety of archaeological materials and the extensive interdisciplinary studies. All this has entailed a better assessment of the evolution of the palaeoenvironment and of the chronostratigraphy of the Palaeolithic occupations. In a matter of speaking, the Bistri?a Valley is to Romania what the Vézère Valley is to the Dordogne region in France.     

Does the Axillary Lymph Node Ratio Have Any Added Prognostic Value over pN Staging for South East Asian Breast Cancer Patients?

Introduction

Lymph node ratio (LNR, i.e. the ratio of the number of positive nodes to the total number of nodes excised) is reported to be superior to the absolute number of nodes involved (pN stage) in classifying patients at high versus low risk of death following breast cancer. The added prognostic value of LNR over pN in addition to other prognostic factors has never been assessed.

Methods

All patients diagnosed with lymph node positive, non-metastatic invasive breast cancer at the National University Hospital (Singapore) and University of Malaya Medical Center (Kuala Lumpur) between 1990–2007 were included (n = 1589). Overall survival of the patients was estimated by the Kaplan Meier method for LNR [categorized as low (>0 and <0.2), intermediate (0.2–0.65) and high (>0.65–1)] and pN staging [pN1, pN2 and pN3]. Adjusted overall relative mortality risks associated with LNR and pN were calculated by Cox regression. The added prognostic value of LNR over pN was evaluated by comparing the discriminating capacity (as indicated by the c statistic) of two multivariate models, one including pN and one including LNR.

Results

LNR was superior to pN in categorizing mortality risks for women ≥60 years, those with ER negative or grade 3 tumors. In combination with other factors (i.e. age, treatment, grade, tumor size and receptor status), substituting pN by LNR did not result in better discrimination of women at high versus low risk of death, neither for the entire cohort (c statistic 0.72 [0.70–0.75] and 0.73 [0.71–0.76] respectively for pN versus LNR), nor for the subgroups mentioned above.

Conclusion

In combination with other prognosticators, substitution of pN by LNR did not provide any added prognostic value for South East Asian breast cancer patients.     

Does Actaea asiatica Have the Most Symmetric and Primitive Karyotype in the Ranunculaceae?

Actaea asiatica was previously reported to have the most symmetric and primitive karyotype, consisting of 10 m- and 6 sm-chromosomes, which is quite different from those of the remaining species in the genus Actaea, consisting of 10 m-, 4 sm- and two T-chromo somes. In this paper, the chromosomes of this species were re-examined. The results show that Actaea asiatica has the same karyotype as the other species in the genus. Compared with the species in other genera in the tribe Cimicifugeae, i.e. Beesia, Anemonopsis, Souliea and Cimicifuga, Actaea asiatica, together with the remaining species of the genus, has the most asymmetric and thus probably the most advanced karyotype in this tribe because of the presence of two T- chromosomes in their chromosome complements. The two T- chromosomes may serve as one of the most important cytological markers, by which the species in Actaea are clearly distinguishable cytologically from those in Beesia, Anemonop-sis, Souliea and Cimicifuga.