A model for the temperature and density dependent reemergence of the bark beetle Ips typographus

A model is presented that describes the reemergence of parent spruce bark beetles, Ips typographus, based on breeding density and temperature conditions. Laboratory data obtained at one constant temperature provide the distribution of reemergence time and different combinations of threshold temperatures and degreedays (°D) at mean reemergence. Of these combinations, 167.71 °D above 7.5 °C gave the best correspondence between model prediction and field data obtained from densely infested standing trees. The model was in good agreement with the reemergence pattern found for two groups of infested logs under different temperature conditions when adjusted for the lower breeding density. The applicability of the model in the study of bark beetle reproductive biology and in forest management is discussed. The method used to construct the model should be useful in developing other models for poikilothermic processes.

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Résumé Ce modèle décrit la réémergence d'adultes d'I. typographus L. (Coleoptera, Scolytidae) en fonction de la densité et de la température.Les résultats obtenus en laboratoire à des températures constantes fournissent la distribution des réémergences et pour les dates de réémergence moyenne les différentes combinaisons de température de seuil et de degré de jour (°D). De toutes ces combinaisons, 167.71 °D au-dessus de 7,5 °C fournit la meilleure concordance entre les prévisions du modèle et les observations dans la nature à partir d'arbres fortement attaqués.Le modèle a montré un bon accord avec la réémergence observée dans deux groupes de branches attaquées dans différentes conditions de la température quand il a été ajusté aux faibles densités d'élevage.La discussion examine les possibilités d'application du modèle à l'étude de la biologie de la reproduction d'I. typographus et à l'aménagement forestier.La méthode utilisée pour construire le modèle pourrait être employée pour en développer d'autres chez des poikilothermes.

     

A chitinase structurally related to the glycoside hydrolase family 48 is indispensable for the hormonally induced diapause termination in a beetle

Two proteins (APAP I and II) of the glycoside hydrolase family 48 (Family GH48) were isolated from the active adults of the leaf beetle Gastrophysa atrocyanea. Full-length and cDNAs were sequenced. APAP I expression and function were examined in detail. The protein has a chitinase but not a glucanase and cellobiohydrolase activity. It is expressed in the feeding stages, including beetles whose diapause was terminated with a juvenile hormone agonist. Suppression of the APAP I expression by means of RNA interference prevented the hormonal termination of diapause.     

A gene cluster for amylovoran synthesis in Erwinia amylovora: characterization and relationship to cps genes in Erwinia stewartii

A large ams gene cluster required for production of the acidic extracellular polysaccharide (EPS) amylovoran by the fire blight pathogen Erwinia amylovora was cloned. Tn5 mutagenesis and gene replacement were used to construct chromosomal ams mutants. Five complementation groups, essential for amylovoran synthesis and virulence in E. amylovora, were identified and designated amsA-E. The ams gene cluster is about 7 kb in size and functionally equivalent to the cps gene cluster involved in EPS synthesis by the related pathogen Erwinia stewartii. Mucoidy and virulence were restored to E. stewartii mutants in four cps complementation groups by the cloned E. amylovora ams genes. Conversely, the E. stewartii cps gene cluster was able to complement mutations in E. amylovora ams genes. Correspondence was found between the amsA-E complementation groups and the cpsB-D region, but the arrangement of the genes appears to be different. EPS production and virulence were also restored to E. amylovora amsE and E. stewartii cpsD mutants by clones containing the Rhizobium meliloti exoA gene.     

Uracil-DNA N-glycosylase (UNG) from the marine, psychrophilic bacterium Vibrio salmonicida shows cold adapted features: A comparative analysis to Vibrio cholerae uracil-DNA N-glycosylase

The genes encoding uracil-DNA N-glycosylase (UNG) from the marine, psychrophilic bacterium Vibrio salmonicida and the mesophilic counterpart Vibrio cholerae have been cloned and expressed in Escherichia coli. The purified proteins have been characterized in order to reveal possible cold adapted features of the V. salmonicida UNG (vsUNG) compared to the V. cholerae UNG (vcUNG). Characterization experiments demonstrated that both enzymes possessed the highest activities at pH 7.0–7.5 and at salt concentrations in the range of 25–50 mM NaCl. Temperature optima for activity were determined to approximately 30 °C for vsUNG and 50 °C for vcUNG. Temperature stability of the enzymes was compared at 4 °C and 37 °C, and vsUNG was found to be more temperature labile than vcUNG. Kinetic studies performed at three different temperatures, 15 °C, 22 °C and 37 °C, demonstrated higher catalytic efficiency for vsUNG compared to vcUNG due to lower K_M-values. The increased substrate affinity of vsUNG is probably caused by an increased number of positively charged residues in the DNA-binding site of the enzyme compared to vcUNG. Thus, activity and stability measurements reveal typical cold adapted features of vsUNG.     

Genetic localization of a bruchid resistance gene and its relationship to insecticidal cyclopeptide alkaloids, the vignatic acids, in mungbean ( Vigna radiata L. Wilczek)

Bruchid resistance, controlled by a single dominant gene (Br) in a wild mungbean accession (TC1966), has been incorporated into cultivated mungbean (Vigna radiata). The resistance gene simultaneously confers inhibitory activity against the bean bug, Riptortus clavatus Thunberg (Hemiptera: Alydidae). The resultant isogenic line (BC₂₀ generation) was characterized by the presence of a group of novel cyclopeptide alkaloids, called vignatic acids. A linkage map was constructed for Br and the vignatic acid gene (Va) using restriction fragment length polymorphism (RFLP) markers and a segregating BC₂₀F₂ population. By screening resistant and susceptible parental lines with 479 primers, eight randomly amplified polymorphic DNA (RAPD) markers linked to Br were identified and cloned for use as RFLP probes. All eight RAPD-based markers, one mungbean, and four common bean genomic clones were effectively integrated around Br within a 3.7-cM interval. Br was mapped to a 0.7-cM segment between a cluster consisting of six markers and a common bean RFLP marker, Bng110. The six markers are closest to the bruchid resistance gene, approximately 0.2 cM away. The vignatic acid gene, Va, cosegregated with bruchid resistance. However, one individual was identified in the BC₂₀F₂ population that retained vignatic acids in spite of its bruchid susceptibility. Consequently, Va was mapped to a single locus at the same position as the cluster of markers and 0.2 cM away from Br. These results suggest that the vignatic acids are not the principal factors responsible for bruchid resistance in V. radiata but will facilitate the use of map-based cloning strategies to isolate the Br gene. Received: 20 November 1997 / Accepted: 6 January 1998     

Seasonal patterns of the thermal response in relation to sugar and polyol accumulation in overwintering adults of elm leaf beetle, Xanthogaleruca luteola (Coleoptera: Chrysomelidae)

Elm leaf beetle, Xanthogaleruca luteola (Muller), is one of the key pests of elm trees that survive winter in reproductive diapause in sheltered locations. Overwintering adults of the elm leaf beetle showed a complex sugar/polyol cryoprotectant system. The major components of the multiple systems were glucose, myo-inositol and trehalose. In this study, we investigated the seasonal profile of low molecular weight compounds and glycogen in natural population and also in response to thermal constant regimes (5 and 15 °C). Among these components, a remarkable seasonal pattern of accumulation/depletion was observed in myo-inositol over the course of hibernation with the development of diapause progress. Incubating at 5 °C only elicited a strong response in myo-inositol synthesis during diapause. It suggests that the elm leaf beetle accumulates myo-inositol not only in relation to entering diapause but also in response to low temperatures and their interactions. The laboratory acclimation experiments showed that adults exposed to 15 °C had no chance for accumulation of low molecular weight carbohydrate even during diapause. The results of this study illustrated that overwintering adults of elm leaf beetle produce myo-inositol as the primary substance which plays a specific role in some biochemical adjustments in overwintering adults of X. luteola.     

Aspects of the thermal biology of the six-lined racerunner, Cnemidophorus sexlineatus (Squamata:Teiidae) in West-Central Florida

(1) I measured the critical thermal maximum (CTM_ax), mean selected temperature (MST), and mean activity temperature (MAT) of six-lined racerunners, (Cnemidophorus sexlineatus) from Florida. (2) Mean CTM_ax and MST of Florida lizards (n=10) were 48.2±0.6 and 33.5±1.9^oC, respectively. MAT (n=22) at 36.6^oC was statistically higher than MST. (3) CTM_ax, MST, and MAT of Florida lizards were statistically lower than those published for a conspecific Oklahoma population.     

Low temperature-stimulated phosphorylation regulates the binding of nuclear factors to the promoter of Wcs120 , a cold-specific gene in wheat

The Wcs120 gene encodes a highly abundant protein which appears to play an important role during cold acclimation of wheat. To understand the regulatory mechanism controlling its expression at low temperature, the promoter region has been characterized. Electrophoretic mobility shift assays using short promoter fragments revealed the presence in nuclear extracts from non-acclimated (NA) plants of multiple DNA-binding proteins which interact with several elements. In contrast, no DNA-binding activity was observed in the nuclear extracts from cold-acclimated (CA) plants. In vitro dephosphorylation of these CA nuclear extracts with alkaline phosphatase restored the binding activity. Moreover, okadaic acid (a potent phosphatase inhibitor) markedly stimulated the in vivo accumulation of the WCS120 family of proteins. This suggests that protein phosphatases PP1 and/or PP2A negatively regulate the expression of the Wcs120 gene. In addition, both Ca²⁺-dependent and Ca²⁺-independent kinase activities were found to be significantly higher in the CA nuclear extracts. Western analysis using antibodies directed against protein kinase C (PKC) isoforms showed that a PKCγ homolog (84 kDa) is selectively translocated into the nucleus in response to low temperature. Taken together, our results suggest that, in vivo, the expression of the Wcs120 gene may be regulated by nuclear factors whose binding activity is modulated by a phosphorylation/dephosphorylation mechanism. Received: 9 June 1997 / Accepted: 18 August 1997     

A population model for the black tern Chlidonias niger in West-Europe

Based on empiric data of breeding success and accurate number trends in The Netherlands, a population model for the black tern was constructed. This model is based on Leslie matrices. Reproductive parameters from the four most important landscape types (river landscape, agricultural grasslands, peat marsh and heath land/moors) are used as model input. Highly accurate national population trend data were used to obtain the best (least square) estimate of overall adult and subadult survival (resp. 0.849 and 0.595). Estimating survival parameters in this way might be useful for threatened (bird) species, especially if catching and ringing is difficult or less desired from a conservation perspective. The model shows the actual importance of the river landscape as the main source for reproductive output of the Dutch black tern population. The prediction model was subsequently used to test different conservation strategies for the Dutch black tern population. Conservation strategies ranged from a null scenario (no change in conservation effort) to in- or decreasing the number of rafts in the most productive landscape (river landscape) to a scenario where breeding success is improved recently in agricultural grasslands via minimizing disturbance. For all scenarios, the model predicts a slow to rapid population increase in the Dutch black tern population after 10–20 years. Improving breeding success in agricultural grasslands habitat has the highest added value.     

Size variations of the calcareous nannofossil taxon Discoaster multiradiatus (Incertae sedis) across the Paleocene–Eocene thermal maximum in ocean drilling program holes 690B and 1209B

Size measurements of the calcareous nannofossil taxon Discoaster multiradiatus were carried out across the Paleocene–Eocene Thermal Maximum (PETM) in Ocean Drilling Program Holes 690B (Maud Rise, Weddell Sea) and 1209B (Shatsky Rise, Pacific Ocean). Morphometric investigations show that D. multiradiatus specimens are generally larger at ODP Site 1209 than at ODP Site 690. A limited increase in size of D. multiradiatus is recorded at ODP Site 1209, whereas significant enlargements characterize ODP Site 690. Preservation is comparable at both sites: nannofossils are moderately preserved with some evidence of etching/overgrowth in the PETM interval. Yet, D. multiradiatus variations do not correlate with preservation state and morphometric data most likely represent primary signals rather than diagenetic artifacts. There is a direct relationship between D. multiradiatus size and paleotemperatures: largest specimens are coeval with global warming associated with the PETM, inferred to result from excess atmospheric CO₂ due to (partial) oxidation of massive quantities of methane. Size increases and largest specimens of D. multiradiatus occur at different stratigraphic levels within PETM at ODP Sites 690 and 1209. A marked shift in diameter size was observed at the onset and peak of the Carbon Isotopic Excursion (CIE) at ODP Site 690, but only at the end of CIE and initial recovery interval at ODP Site 1209. This diachroneity is puzzling, but indeed correlates well with reconstructed changes in surface and thermocline water masses temperature and salinity in the PETM interval at low and high latitudes. The presumed high concentrations of carbon dioxide seem to have not influenced the morphometry of D. multiradiatus. The major size increase of D. multiradiatus in the CIE of ODP Site 690 could represent the migration of larger-sized allochtonus specimens that moved from peri-equatorial/subtropical areas to higher latitudes during the warmest interval of the PETM, although no direct evidence of distinct populations/subpopulations has been obtained from the frequency diagrams. As a result, we infer that D. multiradiatus is a proxy of water masses stratification and might be used for deriving temperature–salinity–nutrient conditions in the mixed layer and thermocline and their dynamics.     

Temperature gradient from the urogenital sinus to the pouch in the pregnant marsupial quoll, Dasyurus hallucatus

1. The mechanisms utilised by the newborn quoll to move from the uterus to the teat within the pouch are unknown. The ability to sense gravity and odour have been suggested and it is possible that temperature may also assist the young in this migration.

2. An increasing temperature gradient was observed from the sinus at 28.98 °C increasing to 29.38 °C on the skin between the sinus and the pouch and further increasing to 30.96 °C within the pouch. This temperature gradient was not as apparent during lactation.

3. Hairs may also play an important role in allowing the newborn to leave the gelatinous material emanating from the uterus and travel to the pouch. The hairs form a tunnel between the sinus and the pouch and may assist the young in the moving from uterus to the pouch.     

A novel role for the Bombyx Slbo homologue, BmC/EBP, in insect choriogenesis

One previously unidentified cDNA clone coding for a C/EBP factor, BmC/EBP, was isolated from Bombyx mori follicular cells. This is the first time that a C/EBP factor has been isolated and characterized in Lepidoptera. We provide information concerning structural features and developmental specificity, as well as in vitro interaction properties with chorion gene promoter modules. BmC/EBP was capable of effectively recognizing homologous binding sites from chorion gene promoters derived from flies and other moths, despite significant diversity of chorion structure, gene organization, and gene expression profiles. We propose that the relative concentration of BmC/EBP, in relation to its differential binding affinity for promoter cis-elements, results in activation or repression of silkmoth chorion gene expression.     

Metabolic and ventilatory responses to hypoxia in two altitudinal populations of the toad, Bufo bankorensis

Effects of hypoxia on resting oxygen consumption ( ), lung ventilation, and heart rate at different ambient P_O2 were compared between lowland and high altitude populations of the toad, Bufo bankorensis. Resting decreased significantly in mild hypoxia (P_O2=120 mm Hg) at 10°C and in moderate hypoxia (P_O2=80 mm Hg) at 25°C in both altitudinal populations; however, resting did not differ significantly between the two populations. Numbers of lung ventilation periods (VP) and total inspired volume (V_L) did not change with P_O2 at 10°C, but did increase at moderate and severe hypoxia (40 mm Hg), respectively, at 25°C. Resting heart rates did not change during hypoxia and did not differ between altitude populations. The results suggest (1) the effect of P_O2 change on should be considered in future studies involving transfer of anurans to a different altitude; and (2) the metabolic and ventilatory physiology in B. bankorensis does not compensate for the low temperature and P_O2 at high altitude.     

Baculovirus-mediated Expression of a Gene for Trehalase of the Mealworm Beetle, Tenebrio molitor, in Insect Cells, SF-9, and Larvae of the Cabbage Armyworm, Mamestra brassicae

It is of interest to understand what kinds of physiological and biochemical changes occur in insects if the homeostasis of trehalose in the hemolymph is disrupted by the infection with a recombinant baculovirus containing a secretory-trehalase gene. For this purpose, two recombinant non-occluded Autographa california multicapsid nucleopolyhedroviruses (AcMNPVs), vTREVL and vERTVL, containing a trehalase cDNA of the mealworm beetle, Tenebrio molitor, were constructed. The trehalase cDNA was inserted in the sense orientation downstream of the polyhedrin promoter for vTREVL, and in the anitsense orientation for vERTVL. The active trehelase of T. molitor was found outside of cells when SF-9 cells or larvae of the cabbage armyworm, Mamestra brassicae, were infected with vTREVL. In the hemolymph of vTREVL-infected larvae, expression of the active trehelase was followed by disappearance of trehalose and appearance of glucose. However, the mortality time of virus-infected 5th instar larvae increased in the following order: AcMNPV C6 (wild-type virus) ≤ vERTVL < vTREVL. The symptoms (the browning and liquefying of the host body) of NPV infection were moderated considerably in vTREVL-infected larvae.     

An Aspergillus nidulans nuclear protein, AnCP, involved in enhancement of Taka-amylase A gene expression, binds to the CCAAT-containing taaG2 , amdS , and gatA promoters

Using AnCP (Aspergillus nidulans CCAAT-binding protein) as a CCAAT-specific binding factor model, the possibility that one factor is able to recognize CCAAT sequences in several different genes in A.␣nidulans was examined. DNase I protection analysis showed that AnCP specifically bound to CCAAT sequence-containing regions comprising 21 to 36 bp of the taa, amdS and gatA genes. Furthermore, replacement of the CCAAT sequence with CGTAA was found to abolish the binding of AnCP and to have an inhibitory effect on taa promoter activity. This clearly demonstrates a positive function of the CCAAT element. However, amylase was induced by starch and repressed by glucose in a CCAAT-box disruptant, as in wild-type cells. Received: 28 June 1996 / Accepted: 7 October 1996     

Effect of photoperiod on the size–temperature relationship in a pentatomid bug, Dolycoris baccarum

(1) The effects of photoperiod and temperature on nymphal growth, development and adult size in a pentatomid bug, Dolycoris baccarum, were examined. (2) The temperature–size relationship was not stable but was highly affected by the photoperiod, and showed a geographical variation. (3) There were variations also in the developmental period and the growth rate. (4) The responses to temperature and photoperiod can explain the seasonal and geographical adaptations of the insect, and thus are considered to be important seasonal adaptations in D. baccarum.     

A randomized, double-blind, placebo-controlled, clinical dose–response trial of an extract of Baptisia, Echinacea and Thuja for the treatment of patients with common cold

The aim of this study was to verify the efficacy and safety of an herbal medication containing an extract of a mixture of Baptisiae tinctoriae radix, Echinaceae pallidae/purpureae radix and Thujae occidentalis herba (SB-TOX) in the treatment of upper respiratory tract infections (URIs), and to test whether SB-TOX's clinical efficacy is dose dependent. A total of 91 adults (mean age 42.1±13.0 years) were randomised to receive 19.2 mg of SB-TOX (n=31), 9.6 mg SB-TOX (n=29) or placebo (n=31) three times daily for 3–12 days. Since a “running nose” is the main symptom of a common cold, the total number of facial tissues used throughout the clinical duration of their cold was the primary efficacy parameter. In the intention-to-treat analysis, this total number of tissues decreased with increasing extract dose. The slope across groups according to the Jonckheere test was significant (p=0.0259). In the high-dose group, the standardised effect size Δ/SD was 0.46 compared with placebo. Time to relevant improvement in cold symptoms (measured as the time until less than 30 tissues per day were used) was 1.1 days (95% CI 0.52; 1.67), 0.76 days (95% CI 0.28; 1.24) and 0.52 days (95% CI 0.22; 0.82) in the placebo, low-dose and high-dose groups, respectively (p_LogRank=0.0175). No adverse events were reported. This study demonstrates the efficacy and safety of SB-TOX in the treatment of URIs, and that its efficacy is dose dependent.     

Response of two species of Indo-Pacific corals, Porites cylindrica and Stylophora pistillata, to short-term thermal stress: The host does matter in determining the tolerance of corals to bleaching

The role of both host and dinoflagellate symbionts was investigated in the response of reef-building corals to thermal stress in the light. Replicate coral nubbins of Stylophora pistillata and Porites cylindrica from the GBR were exposed to either 28 °C (control) or 32 °C for 5 days before being returned to an ambient reef temperature (28 °C). S. pistillata was found to contain either Symbiodinium genotype C1 or C8a, while P. cylindrica had type C15 based on ITS genotyping. Analysis of the quantum yield of photosystem (PS) II fluorescence of the symbionts in P. cylindrica showed that light-induced excitation pressure on the C15 Symbiodinium was significantly less, and the steady state quantum yield of PSII fluorescence at noon (ΔF/Fm′) greater, than that measured in C1/C8a Symbiodinium sp. from S. pistillata. Immunoblots of the PS II D1 protein were significantly lower in Symbiodinium from S. pistillata compared to those in P. cylindrica after exposure to thermal stress. The biochemical markers, heat-stress protein (HSP) 70 and superoxide dismutase (SOD), were significantly greater in P. cylindrica before the experiment, and both species of coral increased their biosynthesis of HSP 70 and SOD when exposed to thermal stress. Concentrations of MAAs, glycerol, and lipids were not significantly affected by thermal stress in these experiments, but DNA damage was greater in heat-stressed S. pistillata compared to P. cylindrica. There was minimal coral mucus, which accounts for up to half of the total energy budget of a coral and provides the first layer of defense for invading microbes, produced by S. pistillata after heat stress compared to P. cylindrica. It is concluded that P. cylindrica contains a heat resistant C15 Symbiodinium and critical host proteins are present at higher concentrations than observed for S. pistillata, the combination of which provides greater protection from bleaching conditions of high temperature in the light.     

A morphometric study of the midgut in resistant and non-resistant Anticarsia gemmatalis (Hübner) (Lepidoptera: Noctuidae) larvae to its nucleopolyhedrovirus (AgMNPV)

In this investigation, the anterior and posterior regions of the midgut of resistant (RL) and non-resistant (SL) Anticarsia gemmatalis larvae were analyzed morphometrically to characterize different regions along their length. Also, this investigation compares the results between SL and RL to improve the understanding of the resistance mechanisms to the virus. Histological sections were analyzed in a computerized system and the data were statistically analyzed by the Kruskal-Wallis test and by multivariate analysis. The midguts are morphometrically different in the two larval populations; we observed higher values in RL. The morphometric analysis of the epithelial cells showed that only columnar and goblet cells were distinct along the midgut, in both larvae, with the higher values found in the anterior region. Comparing the results between the two larval populations, all the epithelial cells presented significant differences, with RL showing the higher morphometric values. We concluded that there are regional differences along the length of midgut in SL and RL that confirm the idea of two morpho-functional distinct regions. The consistently morphometric superior values in RL indicate that this variability can be related with the resistance of A. gemmatalis to its AgMNPV.