Taste receptor activity and feeding behaviour reveal mechanisms of white spruce natural resistance to Eastern spruce budworm Choristoneura fumiferana

The pattern of feeding of Eastern spruce budworm Choristoneura fumiferana (Clem.) (Lepidoptera, Tortricidae) is compared on foliage from white spruce Picea glauca (Moench) Voss. (Pinaceae) trees previously determined to be susceptible and resistant to defoliation by budworm. No differences are observed in electrophysiological responses from taste sensilla to aqueous extracts of the two foliage types, nor is there a preference for either extract type in a choice test. Acetone extracts from the two foliage types are both preferred to a control sucrose solution, although neither elicits a preference relative to the other. These results suggest that there is no difference in phagostimulatory power of internal leaf contents of the two foliage types. Longer‐term observation of feeding behaviour in a no‐choice situation shows no difference in meal duration, confirming the lack of difference in phagostimulatory power. However, on average, intermeal intervals are twice as long on the resistant foliage, leading to an overall lower food consumption during the assay. This result suggests an anti‐digestive or toxic effect of the resistant foliage that slows behaviour and limits food intake. Previous research has shown that waxes of the resistant foliage deter initiation of feeding by the spruce budworm and that this foliage contains higher levels of tannins and monoterpenes. The data suggest that the resistant foliage contains a post‐ingestive second line of defence against the spruce budworm.     

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)     

Behavioural variation in natural populations. V. Morphological correlates of locomotion in the garter snake (Thamnophis radix)

A series of morphologieal and locomotor performance variables was measured in a population of newborn garter snakes to determine whether performance capacity has a significant morphological basis in these animals. Morphological traits measured were body length and mass, number of body and tail vertebrae and numbers of vertebral abnormalities. Locomotor performances included burst and mid-distance speed and distance and time crawled before anti-predator displays were assumed. All performance variables were repeatable in daily replicate trials ( P < 0.001). Individual burst speed, mid-distance speed, and distance crawled were significantly correlated pairwise ( P < 0.01). Most morphological and performance variables had a significant mass dependence (static allometry), although the effects were rather weak ( r ² < 0.1, except for body length): larger animals performed better and had fewer abnormalities. There were significant associations between some morphological traits and locomotor performance. Morphological factors accounted for 19% of the variation in mid-distance speed and 14% of the variation in antipredator behavior by multiple regression analysis. Canonical correlation of all performance and morphological variables simultaneously accounted for 24% of the observed variation in performance. Numbers of body and tail vertebrae (assayed by scale counts) had an interactive effect on speed of locomotion.     

Tumor Suppressor p53 Down-Regulates Tissue-Specific Expression of Tyrosinase Gene in Human Melanoma Cell Lines

Tyrosinase, the key gene in melanin pigment synthesis, is tissue-specifically expressed in melanocytic cells. Expression of this gene is regulated by various hormones, carcinogens, and environmental factors. The molecular basis underlying tyrosinase gene regulation is still not clear. In this report, we present the effects of tumor suppressor p53 protein on tyrosinase gene expression and melanin synthesis in human melanoma. After stable transfection of wild type p53 expression plasmid into a highly pigmented melanoma cell line, overexpression of wt p53 suppressed the pigmentation of the melanoma cells. The loss of pigmentation was associated with the loss of endogenous tyrosinase expression at the activity and mRNA levels. In order to determine whether the p53 repression of tyrosinase mRNA involved modulation of tyrosinase promoter activity, transient transfection approaches involving p53 expression plasmid and construct containing chloramphenicol acetyl transferase (CAT) reporter gene linked to 270 bp tissue-specific tyrosinase promoter have been used. p53 specifically repressed CAT gene expression from the tyrosinase promoter and not from the Rous sarcoma virus promoter. These data suggest that in human melanoma p53 down-regulates the tissue-specific expression of tyrosinase gene and subsequent melanin synthesis.     

THE RATIO OF CALCAREOUS AND ORGANIC SHELL COMPONENTS OF FRESHWATER SPHAERIID CLAMS IN RELATION TO WATER HARDNESS AND TROPHIC CONDITIONS

Shells from 14 populations of sphaeriid clams including Sphaeriumstriatinum, S. simile, Pisidium walkeri, Musculim partumeiumand M. iransversum were analyzed for organic carbon (µgCmg^–1 shell), nitrogen (µg,N mg^–1 shell) andCaCO_s (%CaCO₃ of total clam dry weight). Habitat waters wereassessed for total hardness (expressed as ppm CaCo₃), ppm Ca,ppm Mg, conductivity (µmho) and suspended organic Carbon(µgCl^–1). For all populations, shell organic C andN are positively correlated and there is an inverse relationshipbetween the amounts of shell CaCO₃ and shell organic carbon.Trophic considerations give the best correlation with shelltype at the generic level of consideration since species ofMusculium are found at the opposite end of the trophic scale(eutrophic) from all other populations studied. For S. striatinum,the most extensively studied species, the amount of shell CaCO₃is inversely related to water hardness. The selection of shellsin the Sphaeriidae is discussed in relation to structural-functionalneeds and habitat conditions ¹ Present Address: Department of Biology, Syracuse University,Syracuse, New York 13210, U.S.A. ² Present Address: Department of Zoology, Miami University,Oxford, Ohio 45056, U.S.A. (Received 5 December 1978;     

Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and Bayesian methods

The late Cretaceous hadrosaurids were the most specialized and diverse clade of ornithopod dinosaurs. Parsimony and Bayesian methods were implemented to elucidate the phylogenetic relationships of all hadrosaurid species. Traditional and geometric morphometrics were applied to discover patterns of variation containing phylogenetic information. In total, 286 phylogenetically informative characters (196 cranial and 90 postcranial) were defined and documented: the most extensive character data set ever constructed for hadrosaurid dinosaurs. Of these, 136 characters were used for the first time in phylogenetic analysis of these ornithopods, and 93 were modified from those of other authors. Parsimony and the Bayesian analysis (using the Mk model without the gamma parameter) confirmed the split of hadrosaurids into Saurolophinae and Lambeosaurinae. Saurolophines included a major clade composed of the Prosaurolophus–Saurolophus and the Kritosaurus–Gryposaurus–Secernosaurus subclades. Edmontosaurus and Shantungosaurus were recovered outside the major clade of saurolophines. The Brachylophosaurus clade was recovered as the most basal clade of saurolophines in the parsimony analysis, whereas following the Bayesian analysis it was recovered as the sister clade to the Kritosaurus–Gryposaurus–Secernosaurus clade. These two analyses resulted in a Lambeosaurinae composed of a succession of Eurasian sister taxa to two major clades: the Parasaurolophus clade and the Hypacrosaurs altispinus–Corythosaurus clade. In contrast, the Bayesian analysis using the Mk model with the gamma parameter included, resulted in an unbalanced hadrosauroid tree, with a paraphyletic Saurolophinae, and with the Prosaurolophus clade, Edmontosaurus, and Shantungosaurus as successively closer sister taxa to Lambeosaurinae. Based on the strict reduced consensus tree derived from the parsimony analysis, Hadrosauridae was redefined as the clade stemming from the most recent common ancestor of Hadrosaurus foulkii and Parasaurolophus walkeri. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 435–502.     

Incorporation of Precursors into Toxoplasma DNA

SYNOPSIS. DNA synthesis of Toxoplasma gondii differs from that of other obligate intracellular parasites in that the parasite can synthesize DNA independently of the host cell and can incorporate preformed pyrimidines as well as pyrimidine precursors. However, pyrimidine precursors such as orotic acid are preferentially utilized over preformed pyrimidines such as thymidine. There is little apparent utilization of purine precursors.     

Methane production by microbial mats under low sulphate concentrations

Cyanobacterial mats collected in hypersaline salterns were incubated in a greenhouse under low sulphate concentrations ([]) and examined for their primary productivity and emissions of methane and other major carbon species. Atmospheric greenhouse warming by gases such as carbon dioxide and methane must have been greater during the Archean than today in order to account for a record of moderate to warm palaeoclimates, despite a less luminous early sun. It has been suggested that decreased levels of oxygen and sulphate in Archean oceans could have significantly stimulated microbial methanogenesis relative to present marine rates, with a resultant increase in the relative importance of methane in maintaining the early greenhouse. We maintained modern microbial mats, models of ancient coastal marine communities, in artificial brine mixtures containing both modern [] (c. 70 mm ) and ‘Archean’[] (<0.2 mm ). At low [], primary production in the mats was essentially unaffected, while rates of sulphate reduction decreased by a factor of three, and methane fluxes increased by up to 10‐fold. However, remineralization by methanogenesis still amounted to less than 0.4% of the total carbon released by the mats. The relatively low efficiency of conversion of photosynthate to methane is suggested to reflect the particular geometry and chemical microenvironment of hypersaline cyanobacterial mats. Therefore, such mats were probably relatively weak net sources of methane throughout their 3.5 Ga history, even during periods of low environmental levels oxygen and sulphate.