ANATOMICAL STUDIES REVEAL NEW PHYLOGENETIC INTERPRETATIONS IN LISSACHATINA (PULMONATA: ACHATINIDAE)

This is essentially a preliminary report on the revision ofsubgenus Lissachatina of the African land snail family Achatinidae.It extends the conchological revisionary work of J.C. Bequaert(1950) along the complementary line of comparative anatomicalstudies of the reproductive tracts. This is directed towardthe goal of a better understanding of phylo-geny in this family.Species emphasized are Achatina albopicta E.A. Smith,1878; A.allisa Reeve, 1849; A. fulica Bowdich, 1822; A. loveridgei Clench& Archer, 1930; A. zanzibarica Bourguignat, 1879, and thenew species A. eleanorae. Relegated tosynonymy are A. albicansPfeiffer, 1851; A. delorioli Bonnet, 1864; and A. iredalei Preston,1910. Tangible anatomical characters separate subgenera Lissachatinaand Achatina. A. capelloi Furtado, 1886; A. craveni E.A. Smith,1881; and A. connollyi Preston, 1912 are transferred from Lissachatinato Achatina s.s. Other transfers are in progress. (Received 26 September 1994; accepted 25 November 1994)     

Effect of nickel on oxygen free radical metabolism

The effect of nickel on superoxide dismutase activity (SOD), as well as on rate of hydroxydopamine oxidation, was studied in vitro since lipid peroxidation has been implicated in cell damage by nickel, whose toxicity and carcinogenicity are well established. Nickel strongly inhibits SOD activity. The degree of inhibition is directly proportion to the nickel concentration (tested range 0.066 to 0.33 microgram/mL in the reaction mixture); to the substrate concentration (tested range 0.4 x 10 4M to 1.1 x 10 4M 6-hydroxydopamine); and to reaction mixture. Autoxidation of 6-hydroxydopamine was increased by nickel concentrations higher than 15 micrograms/mL. The combination of excessive oxygen free radical production and inhibition of their elimination by inhibition of SOD activity may contribute to the nickel toxicity that has been reported in industrial accidents, as well as to the high incidence of cancer occurring in nickel workers. It may also contribute to many complications in uremic patients, in whom increased serum nickel levels were reported to be in a similar range to those inhibiting SOD.     

PARATI – a dynamic model for radiological assessments in urban areas

The structure and mathematical model of PARATI, a detailed computer programme developed for the assessment of the radiological consequences of an accidental contamination of urban areas, is described with respect to the scenarios used for the estimation of exposure fields in a village or town, the models for the initial and secondary contamination with the radionuclide ¹³⁷Cs, the concepts for calculating the resulting radiation exposures and the changes with time of the contamination and radiation fields. Kerma rates at various locations in tropical urban areas are given, and the contribution of different contaminated surfaces to these rates after dry or wet deposition are discussed. Received: 12 April 1996 / Accepted in revised form: 30 August 1996     

Studies of biosorption of Pb2+, Cd2+ and Cu2+ from aqueous solutions using Adansonia digitata root powders

The potentials of Adansonia digitata root powders (ADRP) for adsorption of Pb²⁺, Cd²⁺ and Cu²⁺ from aqueous solutions was investigated. Physico-chemical analysis of the adsorbent (ADRP) shows that hydroxyl, carbonyl and amino groups were predominant on the surface of the adsorbent. Scanning Electron Microscope (SEM) image revealed its high porosity and irregular pores in the adsorbent while the Energy Dispersive X-ray Spectrum showed the major element with 53.0% Nitrogen, 23.8% carbon, 9.1% calcium, 7.5% potassium and 6.6% magnesium present. The found optimal conditions were: initial concentration of the metal ions = 0.5 mg/L, pH = 5, contact time = 90 min, adsorbent dose = 0.4 g and particle size = 32 µm. Freundlich isotherm showed good fit for the adsorption of Pb²⁺, Cd²⁺ and Cu²⁺. Dubinin-Radushkevich isotherm revealed that the adsorption processes were physisorption Cd(II) and Cu(II) but chemisorption with respect to Pb(II) ions. The kinetics and thermodynamic studies showed that Pseudo-second order and chemisorptions provided the best fit to the experimental data of Pb (II) ions only. Batch desorption result show that desorption in the acidic media for the metal ions were more rapid and over 90% of the metal ions were recovered from the biomass.     

An initial top-down proteomic analysis of the standard cuprizone mouse model of multiple sclerosis

An initial proteomic analysis of the cuprizone mouse model to characterise the breadth of toxicity by assessing cortex, skeletal muscle, spleen and peripheral blood mononuclear cells. Cuprizone treated vs. control mice for an initial characterisation. Select tissues from each group were pooled, analysed in triplicate using two-dimensional gel electrophoresis (2DE) and deep imaging and altered protein species identified using liquid chromatography tandem mass spectrometry (LC/MS/MS). Forty-three proteins were found to be uniquely detectable or undetectable in the cuprizone treatment group across the tissues analysed. Protein species identified in the cortex may potentially be linked to axonal damage in this model, and those in the spleen and peripheral blood mononuclear cells to the minimal peripheral immune cell infiltration into the central nervous system during cuprizone mediated demyelination. Primary oligodendrocytosis has been observed in type III lesions in multiple sclerosis. However, the underlying mechanisms are poorly understood. Cuprizone treatment results in oligodendrocyte apoptosis and secondary demyelination. This initial analysis identified proteins likely related to axonal damage; these may link primary oligodendrocytosis and secondary axonal damage. Furthermore, this appears to be the first study of the cuprizone model to also identify alterations in the proteomes of skeletal muscle, spleen and peripheral blood mononuclear cells. Notably, protein disulphide isomerase was not detected in the cuprizone cohort; its absence has been linked to reduced major histocompatibility class I assembly and reduced antigen presentation. Overall, the results suggest that, like experimental autoimmune encephalomyelitis, results from the standard cuprizone model should be carefully considered relative to clinical multiple sclerosis.     

Conserved water-mediated H-bonding dynamics of catalytic Asn 175 in plant thiol protease

The role of invariant water molecules in the activity of plant cysteine protease is ubiquitous in nature. On analysing the 11 different Protein DataBank (PDB) structures of plant thiol proteases, the two invariant water molecules W1 and W2 (W220 and W222 in the template 1PPN structure) were observed to form H-bonds with the O_b atom of Asn 175. Extensive energy minimization and molecular dynamics simulation studies up to 2 ns on all the PDB and solvated structures clearly revealed the involvement of the H-bonding association of the two water molecules in fixing the orientation of the asparagine residue of the catalytic triad. From this study, it is suggested that H-bonding of the water molecule at the W1 invariant site better stabilizes the Asn residue at the active site of the catalytic triad.     

Using Haplotype Trees for Phylogeographic and Species Inference in Fish Populations

Genetic variation is now routinely screened at the DNA sequence level in many studies. If the DNA region being screened has not experienced excessive amounts of recombination, it is often possible to reconstruct the evolutionary history of the genetic variation in the form of a haplotype tree. This tree estimates the evolutionary pathway that interconnects all the different haplotypes (sequence variants) observed in the sample. This haplotype tree can be used to define a series of nested branches (clades) that reflects the relative temporal history of the haplotypes and groups of haplotypes. Geographical information can then be overlaid upon this temporal series to test for significant associations between geography and temporal position in the haplotype tree. This allows a reconstruction of how the genetic variation arose and spread in both space and time. Such reconstructions can yield many insights into the joint roles of recurrent events such as gene flow and of historical events such as fragmentation or range expansion. These points are illustrated with studies on the chub, Leuciscus cephalus. There is also a need to extend such nested phylogeographic analyses to a phylo/reticulate geographic analysis that incorporates both assortment and recombination between and within DNA regions. A preliminary phylo/reticulate geographic analysis is presented of the transferrin locus in the brown trout, Salmo trutta, species complex that reveals the importance of hybridization in the recent evolutionary history of this group. This example shows the inadequacy of a strictly phylogenetic approach and illustrates the need to incorporate reticulate evolution. The results of nested clade phylogeographic analysis and the new phylo/reticulate geographic analysis are then used for inferring species status of the marbled trout. The results indicate that an old hybridization event may have played a role in the origin of the marbled trout. Currently the marbled trout is primarily endangered by hybridization with introduced brown trout. These results show both the positive and negative impacts of hybridization upon biodiversity. Such phylo/reticulate geographic studies will challenge both our concepts of species and our conservation management strategies.