Electrophoretic results of a biochemical systematic survey of Oxychilus (Drouetia) atlanticus and some other Zonitidae (Gastropoda: Zonitidae)

Oxychilus (Drouetia) atlanticus is an endemic terrestrial mollusc from the Azores that shows a high degree of both anatomical and morphological variability. In order to support a biochemical systematic study, several potential taxonomic isoenzymes were tested over non-congeneric, congeneric, consubgeneric and infraspecific taxa.     

COGNITIVE ASPECTS OF DIFFERENCE TESTING: MEMORY AND INTERSTIMULUS DELAY

There are many ways in which a laboratory difference test differs from 'real life' discrimination of foods. One of these is the interval of time between tasting the two stimuli to be discriminated. To investigate this, judges performed same-different discrimination tests using a citrus flavored beverage as a medium. The time interval between tasting the standard and comparison stimuli was varied. In this initial study, short intervals of zero, 30, 60 s were examined. For judges unfamiltar with the stimuli, performance deteriorated as the time interval increased. For judges familiar with the stimuli, the zero time interval elicited best performance but there was no decrease in performance when the interval was increased from 30 to 60 s. The results were explained by hypothesizing different types of memory trace for the standard stimulus being utilized for comparison with the comparison stimulus.     

Induction and Growth of 'Microspore-Derived' Embryos of Brassica napus ssp. oleifera

Three cultivars of spring rape (Brassica napus ssp. oleifera),Tower, Willi and Duplo, were used for a study of induction andgrowth of ‘microspore-derived’ embryos, Buds, 2.0mm in length, containing uninucleate microspores were harvestedand stored for 14 d at 4 ?C in darkness. Anthers were then removedand cultured on a liquid medium based upon that of Murashigeand Skoog and containing 8% sucrose, 0.5 mg l^–1 naphthylaceticacid and 0.05 mg l^–1 benzylaminopurine. Cultures werepre-incubated at 35 ?C for 0–3 d and then incubated at30 ?C. After a total of 42 d incubation, cultures were scoredfor the presence of macroscopic embryos (1–2 mm in length)and for the presence of anthers containing abortive embryoidswhich had not developed further. The cultivars differed greatly in terms both of the frequencyof anthers showing induced embryoids and of the final yieldof embryos. Tower showed the highest frequency of induction(maximum 38% of cultured anthers with induced embryoids) whereasthe highest yield (equivalent to 1.1 embryo per cultured anther)was obtained from anthers of the cv. Duplo after a 3 d treatmentat 35 ?C. Yields from the other cultivars were much lower andwere relatively unaffected by the 35 ?C treatment. Key words: Brassica napus, Rape, Anther culture, Pollen, Haploid     

A Comparative Study of 14 Strains of Naegleria australiensis Demonstrates the Existence of a Highly Virulent Subspecies: N. australiensis italica n. spp.1

Fourteen strains of Naegleria australiensis, including the type strain, were compared for virulence for mice, maximum growth temperature, lectin agglutination, isoenzyme pattern, and total protein banding pattern. Their relation to other species of Naegleria also was compared by immunoelectrophoretic analysis. Strains with high virulence, comparable to that of N. fowleri, were found to be different in concanavalin A agglutination as well as with regard to zymograms and total protein patterns. Although serologically different from N. fowleri and reacting with N. australiensis antiserum in the fluorescent antibody test, these high-virulence strains differed in number of immunoelectrophoretic precipitin bands. Because of these results, the high-virulence strains are considered to be a subspecies of N. australiensis. The low-virulence strains showed minor differences from the type strain. Thus, N. australiensis does not appear to be as homogenous a species as N. fowleri. Pathogenic N. australiensis also seems to be more widespread than previously thought.     

Temperature dependence of fitness components in geographical populations of Drosophila melanogaster: changing the association between size and fitness

Contrary to the conventional wisdom 'bigger is better', evolution at high temperature invariably leads to small individuals in Drosophila melanogaster . Natural selection is known to be responsible, meaning that genotypes that are small because of adaptation to high temperature must have some temperature dependent fitness advantage. In this study we consider both preadult and adult fitness components, and show that large adults from a cold adapted population significantly outperform small adults from a warm adapted population only when tested at low temperature and low larval density. In all other conditions 'bigger is not necessarily better', meaning that environmental influences are capable of altering the association between size and fitness. Yet, 'smaller wasn't better either' under any condition, when considering the overall measure of fitness. Examination of individual fitness components revealed population by temperature interaction in preadult survival; this interaction is potentially capable of explaining the temperature specific advantage of small adult body size. At high temperature, the warm adapted population exhibits superior preadult survival while producing small adults. Geographical variation in adult body size seems to be the result of selection on larval growth and competitive strategies, resulting in alterations in the association between fitness components.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 717–725.     

A new species of Exostyles (Leguminosae, Papilionoideae, Swartzieae s.l.), from Paraná State, Brazil

A new species Exostyles godoyensis Soares-Silva & Mansano (Leguminosae, Papilionoideae, Swartzieae), endemic to Paraná state in southern Brazil, is described and illustrated. The new species is distinct from all the other species of Exostyles in having a leaf with up to five leaflets, while the other species have at least seven leaflets per leaf. The new species is distinct from Exostyles amazonica Yakovlev in its longer stamen filaments and ovary stipe and from E. glabra Vogel and E. venusta Schott by its shorter anthers. In addition to these morphological characters E. godoyensis has a disjunct geographical distribution.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 103–106.