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;     

蜜蜂属六蜂种间MRJP2基因C-端重复序列的比较分析

构建了中华蜜蜂（Apis cerana cerana,中蜂）8日龄工蜂头部cDNA文库,获得了中蜂王浆主蛋白2（major royal jelly protein 2,MRJP2）的全长cDNA序列,该序列长1 605bp,包含一个编码468个氨基酸的开放阅读框（open reading frame,ORF）。在中蜂MRJP2的cDNA序列的C-端,首次发现存在串联重复片段长度多态性（variable numbers of tandem repeat,VNTR）。克隆并测定了蜜蜂属Apis内其他5个种的MRJP2基因的C-端重复序列,结果表明: 在蜜蜂属的其他5个种中,C-端重复片段的核心序列是以碱基高度突变方式而表现出个体之间的多态性,而重复片段长度基本一致。中蜂与西方蜜蜂A. mellifera,大蜜蜂A. dorsata与黑大蜜蜂A. laboriosa,以及小蜜蜂A. florea与黑小蜜蜂A. andreniformis分别形成3个进化枝。中蜂和西方蜜蜂与大蜜蜂和黑大蜜蜂之间的亲缘关系较近,而与小蜜蜂和黑小蜜蜂的亲缘关系较远。     

Changes in species richness and composition in European acidic grasslands over the past 70 years: the contribution of cumulative atmospheric nitrogen deposition

Our study investigates the negative impact of nitrogen (N) deposition on species richness in acidic grasslands, based on a temporal comparison of vegetation data spanning a period of almost 70 years. We compiled a large data base of plots assigned to the Violion caninae grassland type, composed of managed, but unfertilized semi-natural grasslands on nutrient-poor, acidic soils. In total 1114 plots, mainly from Great Britain, the Netherlands and Germany, were compiled, dating back to 1939. Environmental site information included geographical and soil (mean Ellenberg values) variables as well as estimates of cumulative N and sulphur (S) deposition since 1939. Statistical analyses were carried out separately for the data subsets from the three regions. In all regions, the vegetation differentiation was mainly related to soil acidity and nutrient availability, as well as to the year of sampling and the cumulative amounts of N and S deposition. Plot-species richness of vascular plants and bryophytes (analysed for Great Britain only) decreased with time and analyses suggest these are affected by various factors, notably soil pH, but also latitude and cumulative N deposition. The latter explained more of the variation in species number than the year of sampling and cumulative S deposition, which supports the interpretation that the decline in species richness is mainly caused by increasing N availability and less by altered management and soil acidification. For Great Britain and Germany, cumulative N deposition showed a strong negative relationship with several biodiversity measures, especially the proportion of dicots, whereas it was positively related to the proportion of grass species. In general, our results give temporal evidence for the negative effect of N deposition on species richness in semi-natural vegetation.