Heterophylly in some Species of Callitriche, with especial reference to Callitriche intermedia

Callitriche stagnalis, C. obtusangula, and C. intermedia, inthat order, were found to show a progressively greater variationin leaf form. Axes of C. intermedia bearing crowns of ovateleaves were submerged under various light and temperature conditionsand the growth rates studied in relation to the form of theleaves produced. Leaf movements were also studied in connexionwith the growth of such submerged shoots and with the generalquestion of heterophylly.     

Further Studies on Heterophylly in Callitriche intermedia: Leaf Development and Experimental Induction of Ovate Leaves

The forms of successive primordia in the development of linearand ovate leaves are described and discussed in relation toprimordia in crowns where a transition is occurring betweenovate leaves and linear leaves. Ovate leaves are induced onsubmerged axes, originally bearing linear leaves, by submergingthese axes in 30 per cent. sea water. The results are discussedin relation to possible interpretations of heterophylly in C.intermedia.     

Distribution and habitat of unionid mussels and invasive sea lamprey larvae in the Paw Paw River,a tributary of Lake Michigan

1. Lampricides are commonly used to control invasive sea lampreys (Petromyzon marinus) in tributaries around the Great Lakes (U.S.A.) by targeting their larvae (ammocoetes). As lampricides have sublethal effects on unionids, this study investigated unionid and ammocoete distribution and habitat use to aid in refining lampricide applications. 2. Habitat and unionid surveys were conducted in the Paw Paw River, in south‐west Michigan (U.S.A.). Unionids were predominately present in the upper main stem, while the probability of ammocoete presence was highest in the tributaries and lower main stem. 3. Generalised linear models revealed median particle size and gradient to be effective predictors of unionid distributions, while distance to sea lamprey spawning habitat and bank stability were effective predictors of ammocoete distributions. 4. Minimal overlap of unionid and ammocoete distributions suggests that refinement of lampricide treatment in the Paw Paw River is possible. We propose redefining the extent of the treatment unit so that only areas with a high probability of ammocoete presence and a low probability of unionid presence are treated with lampricide. This could result in reducing treatment costs and minimising threats to unionid conservation, while not jeopardising the success of lampricide treatment programmes.     

zpl, a new gene in drosophila required for neurogenesis

zpl(zip-like) gene mutant embryos showed the cuticular defect with alternative denticle rows and a hole from head to abdomen.zpl mutants also caused the overgrowth of neural cells and axons both in CNS and PNS as well as the wrong pathway of neural fasciculation and the disappearance of hypophysis,as shown by whole mount embryos stained with antibody against HRP and MAb-22C10.Genetic analysis has provided evidence that zpl,located in the right arm of the second chromosome(between 75 and 102 genetic map units),is a new gene closely related to the zip gene.     

Ribosomal RNA Sequences of Enterocytozoon bieneusi, Septata intestinalis and Ameson michaelis: Phylogenetic Construction and Structural Correspondence

ABSTRACT. The microsporidian species Enterocytozoon bieneusi, Septata intestinalis and Ameson michaelis were compared by using sequence data of their rRNA gene segments, which were amplified by polymerized chain reaction and directly sequenced. The forward primer 530f (5'-GTGCCATCCAGCCGCGG-3') was in the small subunit rRNA (SSU-rRNA) and the reverse primer 580r (5'-GGTCCGTGTTTCAAGACGG-3') was in the large subunit rRNA (LSU-rRNA). We have utilized these sequence data, the published data on Encephalitozoon cuniculi and Encephalitozoon hellem and our cloned SSU-rRNA genes from E. bieneusi and S. intestinalis to develop a phylogenetic tree for the microsporidia involved in human infection. The higher sequence similarities demonstrated between S. intestinalis and E. cuniculi support the placement of S. intestinalis in the family Encephalitozoonidae. This method of polymerized chain reaction rRNA phylogeny allows the establishment of phylogenetic relationships on limiting material where culture and electron microscopy are difficult or impossible and can be applied to archival material to expand the molecular phylogenetic analysis of the phylum Microspora. In addition, the highly variable region (E. coli numbering 590–650) and intergenic spacer regions in the microsporidia were noted to have structural correspondence, suggesting the possibility that they are coevolving.     

Identification of a Microsporidian Polar Tube Protein Reactive Monoclonal Antibody

ABSTRACT. The microsporidia are characterized by spores containing a single polar tube that coils around the sporoplasm. When triggered by appropriate stimuli, the polar tube rapidly discharges out of the spore forming a hollow tube. The sporoplasm passes out of the spore through this tube serving as a unique vehicle of infection. Due to the unusual functional and solubility properties of the polar tube, the proteins comprising it are likely to be members of a protein family with a highly conserved amino acid composition among the various microsporidia. Polar tube proteins were separated from the majority of other proteins in glass bead disrupted spores of Glugea americanus using sequential 1% sodium dodecyl sulfate (SDS) and 9M urea extractions. The resultant spore pellet demonstrated broken, empty spore coats and numerous polar tubes in straight and twisted formations by negative stain transmission electron microscopy. After subsequent incubation of the pellet with 2% dithiothreitol (DTT), empty spore coats were still observed but the polar tubes were no longer present in the pellet. The DTT supernatant demonstrated four major protein bands by SDS-PAGE: 23, 27, 34 and 43 kDa. Monoclonal antibodies were produced to these proteins using Hunter's Titermax adjuvant. Mab 3C8.23.1 which cross-reacted with a 43-kDa antigen by immunoblot analyis, demonstrated strong reactivity with the polar tube of G. americanus spores by immunogold electron microscopy. This antibody will be useful in further characterization of polar tube proteins and may lead to novel diagnostic and therapeutic reagents.