Diapause induction in Ephestia cautella: An interaction between genotype and crowding

Larval diapause induction in Ephestia cautella (Walker) (Lepidoptera: Pyralidae) is a function of the interaction between genotype and larval crowding. A diapause stock in which 79% of the larvae diapaused under crowded conditions and 40% diapaused under uncrowded conditions was maintained by selection. Outbreeding of adults from this diapause stock to those from a non-diapause stock resulted in 36% diapause under crowded conditions and 6% diapause under uncrowded conditions. The rate of termination of larval diapause is inheritable and temperature dependent. These data seem to explain the seasonal trends in percentage larval diapause among E. cautella infesting citrus pulp during storage.Larval diapause was induced in groups of larvae by crowding in mass cultures and in single larvae by rearing on a small amount of fresh diet or on a larger amount of fresh diet containing residual diet from crowded cultures. The diapause-inducing effects of this residual diet could be removed by extraction with lipid solvents. Some activity was demonstrated when the extract was dried onto fresh diet.

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Resume L'induction de la diapause larvaire d'Ephestia cautella (Walker) dépend du génotype et de la densité larvaire.Des croisements à l'intérieur de la souche diapausante donnent 79% de diapause aux fortes densités larvaires et 40% aux faibles densités. Les croisements des adultes de cette souche avec ceux de la souche non-diapausante donnent 36% de diapause aux fortes densités et 6% aux faibles densités. La fréquence de fin de diapause est héréditaire et dépend de la température. Ces résultats peuvent expliquer les variations saisonnières du taux de diapause E. cautella dans la pulpe de citron stockée.La diapause larvaire a été induite chez des groupes de chenilles par surpeuplement dans des élevages standards, et chez des chenilles isolées par élevage sur une quantité limitée d'aliments frais ou sur une quantité abondante d'aliments frais contenant des résidus alimentaires provenent d'élevages surpeuplés. Les effets inducteurs de ces résidus alimentaires disparaissent après extraction avec les solvants de lipides. Une certaine action est observée par de l'extraint sec sur de l'aliment frais.

     

窄叶山血丹(紫金牛科)一新变种

报道了紫金牛科紫金牛属的一个新变种：窄叶山血丹Ardisia lindleyana D．Dietr．var．angustifolia C．M．Hu＆X．J．Ma,并比较了此变种与本属中具有类似叶形种类的区别。     

Insect population quality and meteorological conditions

Recent studies on the rice stem borer,CHILO SUPPRESSALIS Walker,are presented as an example of some results of spatial variation in population quality.Local differences in the seasonal prevalence of this insect are basically related to the alternative occurrence of a short life-cycle strain which has a strong tendency to multivoltinism, and a long life-cycle strain which has a deep intensity of diapause along the climatic line. Qualitative change in a local population is illustrated by some effects of phase polymorphism in the armyworm,LEUCANIA SEPARATA Walker. The active black larvae that appear in crowded populations and the sluggish pale larvae that appear in sparse populations differ in their daily rhythmic activity and in their resistance to starvation at different humidities.

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Zusammenfassung Kürzliche Untersuchungen über den Reisstielbohrer, CHILO SUPPRESSALIS Walker, werden als Beispiel für einige Ergebnisse bei räumlichen Unterschieden in der Qualität einer Population beschrieben.Ortliche Unterschiede in der jahreszeitlichen Verbreitung dieses Insekts werden grundlegend in Beziehung gesetzt zum Vorkommen eines Stammes von kurzer Lebenslänge, der eine starke Tendenz zu Multivoltinismus zeigt und eines Stammes von langer Lebenslänge,der eine besondere Tiefe der Diapause entlang der Klimalinie aufweist.Der qualitative Wechsel in einer lokalen Population wird and einigen Wirkungen des Phasenpolymorphismus beim Heerwurm,LEUCANIA SEPARATA Walker, aufgezeigt. Die aktiven schwarzen Larven, die in dichten Populationen auftreten und die trägen blassen Larven, die in dünnen Populationen auftreten, differieren in ihrer täglichen rhythmischen Aktivität und in ihrem Widerstand gegen Hungern bei verschiedenen Feuchten.

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Resume L'étude récente du mode de vie du charançon du riz, CHILO SUPPRESSALIS Walker, fournit un exemple frappant des variations auxquelles sont soumises les qualités d'une population. Les différences locales constatées dans la répartition saisonnière de cet insecte sont en relation étroite avec l'apparition successive,alternée ou simultanée de populations ayant des caractéristiques propres. L'une est formée d'individus qui ont une courte vie et une forte tendance à produire plusieurs générations en un certain laps de temps, l'autre d'individus ayant un long cycle de développement. Ces derniers présentent en outre une longue diapause le long d'une ligne climatique déterminée. Une modification qualitative à l'intérieur d'une population locale est illustrée par quelques effets de polymorphisme des phases de développement du LEUCANIA SEPARATA Walker (Armyworm).Les larves actives et noires qui se rencontrent dans les populations denses et les larves paresseuses et pâles qui composent les populations peu denses différent dans leur rythme journalier d'activité et dans leur résistance aux privations à diverses humidités.

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Paper presented during the Fourth International Biometeorological Congress, New Brunswick, N.J., 26 August – 2 September 1966.     

Cachexia induced by Walker 256 tumor growth causes rat lymphocyte death

Death induction by Walker 256 tumor cachexia in non-tumor-infiltrating lymphocytes was investigated. Lymphocytes from cachectic tumor-bearing rats presented a higher proportion of cells with ruptured membranes, indicating necrotic cell death. The cachexia induced by Walker 256 tumor also increased by 3.6-fold the percentage of cells with fragmented DNA, suggestive of apoptotic cell death. The mitochondria involvement was examined by analysis of mitochondria transmembrane potential using rhodamine 123. Lymphocytes from cachectic tumor-bearing rats presented a more pronounced depolarization of mitochondrial transmembrane potential in comparison with cells from the control group. The expression of important proapoptotic (Bcl-x_s, Bax, p53, caspase-3) and antiapoptotic genes (Bcl-2 and Bcl-x_L) was also altered by tumor cachexia. These results suggest that the immunosuppression induced by Walker 256 tumor cachexia is at least in part a result of lymphocyte death. Evidence was found for the involvement of mitochondria and important proapoptotic genes in the process of lymphocyte death by Walker 256 tumor cachexia.Thais Martins de Lima and Manuela M. Ramos Lima have contributed equally to this study.     

Trichospilus pupivorus (Hymenoptera: Eulophidae): first report of parasitism on Thagona tibialis (Lepidoptera: Lymantriidae) in Brazil

We report the occurrence of Trichospilus pupivorus Ferrière, 1930 (Hymenoptera: Eulophidae) parasitizing pupae of Thagona tibialis Walker, 1855 (Lepidoptera: Lymantriidae) collected on Terminalia catappa L. (Combretaceae) tree in Viçosa, Minas Gerais, Brazil. Fifty to 75 parasitoids emerged from three pupae of Th. tibialis. This is the first record of Tr. pupivorus for the American continent and a new host record.

Relatamos a ocorrência de Trichospilus pupivorus Ferrière, 1930 (Hymenoptera: Eulophidae) parasitando pupas de Thagona tibialis Walker, 1855 (Lepidoptera: Lymantriidae) coletadas em uma árvore de Terminalia catappa L. (Combretaceae) em Viçosa, Minas Gerais, Brasil. Cinqüenta a 75 parasitóides emergiram de três pupas de Th. tibialis. Este é o primeiro relato de Tr. pupivorus no continente americano como também um hospedeiro novo.     

Fruit flies of the subtribe Gastrozonina of Indonesia,New Guinea and the Bismarck and Solomon Islands (Diptera,Tephritidae, Trypetinae,Acanthonevrini)*

Thirty one genera [including Homoiothemara gen.n., Polyaroidea gen.n., Proepacrocerus gen.n. and 1 unnamed new(?) genus], 3 subgenera, 87 species [including 9 new species: Acrotaeniostola interrupta, Carpophthorella bivittata, Enicoptera gressitti, Homoiothemara eurycephala, Polyaroidea distincta, P. opposita, P. univittata, Proepacrocerus pallidoviridus and Xanthorrachis sabahensis and 6 unnamed new(?) species] and 1 subspecies are keyed and described or, if recently described elsewhere, only listed and additional data recorded. The following are new synonyms: Trypeta retorta Walker, Carpophthorella magnifica Hendel, Gastrozona bifasciata de Meijere and Gastrozona alboscutellata Enderlein =Carpophthorella nigrifascia Walker; Icteroptera van der Wulp =Sophira Walker; Sophira disjuncta Hardy =Sophira (Kambangania)ypsilon (Rondani); Curvinervis walkeri Hardy and Strumeta concisa Walker =Stymbara vagaria Walker; Carpophthorella scutellomaculata Hering =Xanthorrachis annandalei Bezzi. Proanoplomus cinereofasciatus (de Meijere) is a new combination and Spilocosmia kotoshoensis (Shiraki) is given new status.     

中国美广口蝇属(双翅目,广口蝇科)一新种及二新纪录种

记述采自中国广西大青山的美广口蝇属(双翅目,广口蝇科)一新种,广西美广口蝇Euthyplatystoma guangxiensis sp. nov..报道了2个中国新纪录种,多斑美广口蝇E.punctiplenum(Walker)(分布:云南)和明带美广口蝇E.rigidum(Walker)(分布:四川峨眉山).编制了中国美广口蝇属分种检索表.新种模式标本保存于中国科学院动物研究所,北京.     

Investigating the role of the invariant carboxylate residues E552 and E1197 in the catalytic activity of Abcb1a (mouse Mdr3)

The invariant carboxylate residue which follows the Walker B motif (hyd(4)DE/D) in the nucleotide-binding domains (NBDs) of ATP-binding cassette transporters is thought to be involved in the hydrolysis of the gamma-phosphate of MgATP, either by activating the attacking water molecule or by promoting substrate-assisted catalysis. In Abcb1a, this invariant carboxylate residue corresponds to E552 in NBD1 and E1197 in NBD2. To further characterize the role of these residues in catalysis, we created in Abcb1a the single-site mutants E552D, N and A in NBD1, and E1197D, N and A in NBD2, as well as the double-mutant E552Q/E1197Q. In addition, we created mutants in which the Walker A K --> R mutation known to abolish ATPase activity was introduced in the non-mutant NBD of E552Q and E1197Q. ATPase activity, binding affinity and trapping properties were tested for each Abcb1a variant. The results suggest that the length of the invariant carboxylate residue is important for the catalytic activity, whereas the charge of the side chain is critical for full turnover to occur. Moreover, in the double-mutants where the K --> R mutation is introduced in the 'wild-type' NBD of the E --> Q mutants, single-site turnover is observed, especially when NBD2 can undergo gamma-P(i) cleavage. The results further support the idea that the NBDs are not symmetric and suggest that the invariant carboxylates are involved both in NBD-NBD communication and transition-state formation through orientation of the linchpin residue.     

Effects of combined selenium and vitamin E administration on DNA in Walker tumor bearing Wistar rat exposed to cytostatic acute treatment

Previous studies have showed that organic Se and Vitamin E have a significant protective effect when administered in combination with cytostatics. This paper reports the investigation on effects of mixed administration Orgasel 50 and Vitamin E in Wistar rat with experimentally induced Walker tumor under acute cytostatic treatment, with emphasis on two aspects: a) the influence of antioxidants upon liver unscheduled DNA biosynthesis under cytostatic (Lomustin) acute aggression; and b) the potential improvement of cytostatic effects by antioxidants treatment in tumor. Two lots of animals were used: lot 1 - Orgasel 50 and Vitamin E administered 7 days before the initiation of tumor induction and lot 2 - the antioxidants were concomitantly administered with tumor cell inoculation. The Walker tumor (an epithelial carcinoma) cells were subcutaneously injected (5 x 10(6) cells/0.5 ml in isotonic saline solution); the first tumor nodules appeared in 4 days; the tumor has reached the appropriate dimensions in 12 days. The unscheduled DNA biosynthesis caused by Lomustin in rat liver as well as the replicative DNA biosynthesis taking place in Walker tumor cells were assessed radioisotopically by measuring the uptake of 3H-Thymidine (200 microCi / 100 g.b.w.). Our observations regarding the role of antioxidant treatment suggest: 1) a benefic effect on DNA alkylant-induced lesions, expressed by a decrease in the level of 3H-Thymidine uptake in liver and, 2) an increase of the inhibitory activity of cytostatic on DNA replication biosynthesis in tumor cells, suggested by lower 3H-Thymidine incorporation in tumor cells. The most significant results were showed in both analyzed tissues, when the Orgasel 50 + Vitamin E administration begins at the same time with the tumor cell inoculation. These findings clearly show the organic Se salts and Vitamin E constitute a valuable adjuvant in anticancer medication, increasing the interest for the application of these antioxidants in cancer therapy and prevention.     

A revision of European Copidosoma Ratzeburg (Hymenoptera, Chalcidoidea, Encyrtidae): some corrections and a description of Copidosoma tremblayi sp.nov.

Abstract.  One invalid lectotype designation proposed in a recent revision of European species of Copidosoma is validated ( Encyrtus geniculatus Dalman) and four incorrectly cited designations are corrected ( C. peninsulare Mercet, E. filicornis Dalman, E. flagellaris Dalman, E. machaeras Walker). One species, C. tremblayi , is described as new.     

Effects of temperature, photoperiod, and light intensity on the calling rhythm in Arctiid moths

Mean times of onset for calling in Haploa clymene (Brown), Spilosoma virginica (Fabricius), Pareuchaetes insulata (Walker), Cycnia tenera (Hübner), and Euchaetes egle (Drury) advance to earlier times in the photoperiod at lower temperatures. Temperature has no apparent effect on the calling period in Pyrrharctia isabella (J. E. Smith), Spilosoma congrua Walker, and Apantesis nais (Drury). The relationship between the temperatures experienced by each of these species as adults and the response of their calling rhythms to temperature is discussed. Lights-on can elicit calling behaviour in C. tenera, although it is not an absolute requirement because calling eventually begins when lights-on is delayed 4 h and calling also begins prior to lights-on at lower temperatures. Calling periods lengthen in C. tenera and S. congrua when the scotophase is prolonged and in S. congrua after the onset of a lower photophase light intensity (40 lux), suggesting that a higher photophase light intensity (450 lux) inhibits calling and thus causes its termination.

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Résumé Aux faibles températures le moment moyen de déclenchement de l'appel apparaît plus tôt au cours de la photopériode chez Haploa clymene Brown, Spilosoma virginica Fab., Pareuchaetes insulata Walk., Cycnia tenera Hübn. et Euchaetes egle Drury. La température n'a apparemment pas d'effet sur le moment où l'appel débute chez Pyrrharctica isabella J.E. Smith, S. congrua Walk. et Apantesis nais Drury.L'analyse porte sur les relations entre les températures subies par les adultes de ces espèces et leurs réactions d'appel aux différentes températures. L'apparition de la lumière peut induire le comportement d'appel chez C. tenera, bien que ce ne soit pas indispensable puisqu'il peut éventuellement commencer à des températures plus basses avant l'illumination quand celle-ci est retardée de 4 heures. Les périodes d'appel sont prolongées avec la scotophase chez C. tenera et S. congrua, et même après l'apparition d'une photophase à faible intensité lumineuse (40 lux), l'appel de S. congrua se poursuit, ce qui suggère que les photophases à intensité lumineuse plus élevée (450 lux) inhibent l'appel et ainsi en provoquent la fin.

     

Effects of Azadirachtin on reproduction in the African armyworm (Spodoptera exempta)

Azadirachtin, applied topically to final instar larvae of the African armyworm (Spodoptera exempta, Walker) (Lepidoptera: Noctuidae), adversely affected oogenesis and reproductive maturation in subsequent female moths. Moths obtained from such treated larvae failed to mature their oocytes, probably as a result of interference of azadirachtin with vitellogenin synthesis and/or its uptake by developing oocytes. Such larval treatment also caused substantial decreases in fecundity and although fertility in affected females was not decreased significantly, emerging larvae were less viable, less than 40% reaching the fourth instar.Closer examination revealed that protein levels as well as fat body development in female moths were suppressed by azadirachtin. Prospects for field control of this pest with neem are discussed in the light of these findings.

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Résumé L'application locale d'azadirachtine sur des chenilles de dernier stade de S. exempta Walker nuit à l'ovogenèse et à la maturation des ovaires des futures femelles. Les papillons provenant des chenilles traitées ne produisent pas d'ovocytes mûrs, probablement par suite de l'interférence de l'azadirachtine avec la synthèse de la vitellogénine et/ou son incorporation dans les ovocytes en développement. De tels traitements larvaires provoquent aussi une diminution importante de la fécondité et bien que la fertilité des femelles touchées ne diminue pas significativement, les chenilles néonates sont moins viables, moins de 40% atteignant le 4^e stade. Un examen plus précis a révélé que la teneur en protéines et le développement du corps gras des papillons femelles étaient altérés par l'azadirachtine. Des perspectives d'utilisation du NEEM dans la lutte contre cet insecte ont été discutées à la lumière de ces résultats.

     

Defining the ATPase center of bacteriophage T4 DNA packaging machine: requirement for a catalytic glutamate residue in the large terminase protein gp17

Double-stranded DNA packaging in icosahedral bacteriophages is driven by an ATPase-coupled packaging machine constituted by the portal protein and two non-structural packaging/terminase proteins assembled at the unique portal vertex of the empty viral capsid. Recent studies show that the N-terminal ATPase site of bacteriophage T4 large terminase protein gp17 is critically required for DNA packaging. It is likely that this is the DNA translocating ATPase that powers directional translocation of DNA into the viral capsid. Defining this ATPase center is therefore fundamentally important to understand the mechanism of ATP-driven DNA translocation in viruses. Using combinatorial mutagenesis and biochemical approaches, we have defined the catalytic carboxylate residue that is required for ATP hydrolysis. Although the original catalytic carboxylate hypothesis suggested the presence of a catalytic glutamate between the Walker A (SRQLGKT(161-167)) and Walker B (MIYID(251-255)) motifs, none of the four candidate glutamic acid residues, E198, E208, E220 and E227, is required for function. However, the E256 residue that is immediately adjacent to the putative Walker B aspartic acid residue (D255) exhibited a phenotypic pattern that is consistent with the catalytic carboxylate function. None of the amino acid substitutions, including the highly conservative D and Q, was tolerated. Biochemical analyses showed that the purified E256V, D, and Q mutant gp17s exhibited a complete loss of gp16-stimulated ATPase activity and in vitro DNA packaging activity, whereas their ATP binding and DNA cleavage functions remained intact. The data suggest that the E256 mutants are trapped in an ATP-bound conformation and are unable to catalyze the ATP hydrolysis-transduction cycle that powers DNA translocation. Thus, this study for the first time identified and characterized a catalytic glutamate residue that is involved in the energy transduction mechanism of a viral DNA packaging machine.     

The effect of hybridization on the periodicity of sex pheromone release of Euxoa species (Lepidoptera: Noctuidae)

ABSTRACT. The periodicities of sex pheromone release by reciprocal F₁ hybrid females obtained from laboratory matings between Euxoa declarata (Walker) and E. rockburnei Hardwick were found to be dependent upon the parental cross. The period of sex pheromone release by females from the E. declarata (female) × E. rockburnei (male) cross paralleled that of the maternal parent species, E. declarata. However, female hybrid E. rockburnei (female) × E. declarata (male) had a prolonged calling period which intersected the pheromone release periods of both parental species and peaked later than that of E. declarata. These results indicate that the circadian periodicity of calling in these species is controlled by autosomal genes and a matroklinal inheritance factor.     

Damage and performance of the green spruce aphid, Elatobium abietinum on twenty spruce species

Field and laboratory observations of the relationships between the performance of Elatobium abietinum (Walker), Homoptera, Aphididae, and various species of spruce were undertaken from January 1980 to April 1981. The study included sampling for aphids in established field plots of spruce during May and June respectively before and after the migration period in spring. The aphid's performance (weight and mean relative growth rate) at different seasons on pot grown plants of selected spruce species was monitored, covering, in all, 20 species of spruce.Aphid performance was greatest on the North American spruces, especially Picea sitchensis (Bong) Carr and P. mexicana Martinez; the Asian spruces were the least favoured, especially P. glehnii (Schmidt) Mast. Between these two geographical groups the Eurasian spruce species (sensu Wright, 1955) demonstrated an intermediate aphid performance.

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Résumé Les observations dans la nature et au laboratoire sur les performances d'E. abietinum Walker et différentes espèces d'épicéas ont été effectuées de janvier 1980 à avril 1981. Les observations dans la nature comprenaient des prélèvements de pousses d'épicéa pour dénombrer les pucerons avant (mai) et après (juin) la période de migration du printemps. Les performances des pucerons (poids et taux moyen de croissance relative) ont été examinées à différentes saisons sur des plantes en pot sur un total de 20 espèches sélectionnées d'épicéas.Les performances du puceron ont été supérieures sur les espèces d'épicéa de l'Amérique du nord Picea sitchensis et P. mexicana; les espèces asiatiques étaient les moins favorables, particulièrement P. glehnii. Entre ces deux groups géographiques, les espèces eurasiennes (sensu Wright, 1955) ont permis des performances intermédiares chez les pucerons.

     

The subfamily classification of the Micropezidae and the genera of Eurybatinae (Diptera: Schizophora)

The classification of the family Micropezidae is re-examined and a key is given to the five subfamilies now recognised, of which Calycopteryginae is described as new and Eurybatinae is raised from tribal rank. Metopochetini is a new tribe of Eurybatinae. A key is given to the nine genera now included in the Eurybatinae, of which Papeza is described as new. P.szentivanyi is a new species from Papua. Notes on the taxonomy and distribution of genera are included. The position of Anaeropsis Bigot in the Micropezidae is confirmed. New synonymies are established as follows: Crepidochetus Enderlein (= Gongylocephala Czerny syn. n.); Metopochetus bivittatus (Macquart) (= Calobata tenuipes Walker syn. n.). New generic combinations are as follows: Metopochetus terminalis (Walker) and M.compressus (Walker) from Calobata; Crepidochetus nigrifemur (Czerny), C.pallidus (Steyskal), and Cater (Steyskal) from Gongylocephala; Crosa fragilis (Walker) from Micropeza; Crosa nigriventris (Enderlein) and C.uneifera (de Meijere) from Eurybata.     

Effects of host fecal pellet and synthetic kairomone on host-searching and postoviposition behavior of Apanteles kariyai, a parasitoid of Pseudaletia separata

The response of female Apanteles kariyai (Watanabe) to a fecal pellet of its host, Pseudaletia separata (Walker) was observed in the laboratory. The arrestment response of A. kariyai to a fecal pellet was characterized by a reduction of walking speed and increased turing rate. During arrestment, A. kariyai turned back towards the fecal pellet several times after she had left it. Using patches impregnated with the synthetic kairomone 2,5-dihexadecyltetrahydrofuran, it was determined that the time spent in arrestment response increased with increasing kairomone concentration but leveled off above 10^-4 mg kairomone per patch. A. kariyai demonstrated two modes of arrestment response towards the patch (patch-searching mode and patch-edge-following mode), which were dependent on the amount of kairomone per patch. During successive visits to the patch, walking speed increased whereas time spent and distance walked on the patch decreased. Postoviposition behavior of A. kariyai was also studied using the kairomone patch. Immediately after oviposition, the wasp did not respond to the kairomone stimuli or to a host and always walked away from the patch.

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Résumé La réponse des femelles d'A. kariyai Watanabe aux crottes de la chenille de P. separata Walker a été étudiée au laboratoire. L'effet fixateur sur A. kariyai d'une crotte est caractérisé par une réduction de la vitesse de marche et par des détours fréquents. Pendant la fixation, elle se retourne plusieurs fois vers la crotte qu'elle vient de quitter. Le temps passé en fixation croît avec la concentration de la source en kairomone synthétique (2,5-dihexandécyltétrahydrofuran), jusqu'à 10^-4 mg de kairomone par source. Suivant la concentration de la kairomone on observe 2 types de réations de fixation par la source: la recherche de la source et le parcours du bord de la source. Au cours de visites successives à la source, la vitesse de déplacement augmente, tandis que le temps dépensé sur la source et la distance parcourue diminuent. Immédiatement après la ponte la femelle ne réagit plus à la kairomone ou à un hôte et s'éloigne de la source.

     

Characterization of a trap mutant of the AAA+ chaperone ClpB

The AAA+ protein ClpB mediates the solubilization of protein aggregates in cooperation with the DnaK chaperone system (KJE). The order of action of ClpB and KJE on aggregated proteins is unknown. We describe a ClpB variant with mutational alterations in the Walker B motif of both AAA domains (E279A/E678A), which binds but does not hydrolyze ATP. This variant associates in vitro and in vivo in a stable manner with protein substrates, demonstrating direct interaction of ClpB with protein aggregates for the first time. Substrate interaction is strictly dependent on ATP binding to both AAA domains of ClpB. The unique substrate binding properties of the double Walker B variant allowed to dissect the order of ClpB and DnaK action during disaggregation reactions. ClpB-E279A/E678A outcompetes the DnaK system for binding to the model substrate TrfA and inhibits the dissociation of small protein aggregates by DnaK only, indicating that ClpB acts prior to DnaK on protein substrates.     

朱砂根复合群形态性状的数量分析

朱砂根复合群—朱砂根(Ardisia crenata Sims)、红凉伞(A. crenata var. bicolor (E. Walker) C. Y. Wu C. Chen),和岭南紫金牛(A. linangensis C. M. Hu)之间存在一些过渡类型,很难依据少数几个关键性状对它们明确划分。本文运用E. Anderson的形象化散点图和柱状图的方法对全国14个省区135份标本的9个性状进行了分析,结果表明：岭南紫金牛应为独立的种,支持将红凉伞归并。     

Conserved sequence motifs in the unorthodox BvgS two-component sensor protein ofBordetella pertussis

The unorthodox two-component sensor protein BvgS ofBordetella pertussis contains several interesting sequence motifs of unknown functional relevance, such as a histidine motif in its output domain, which is conserved among several unorthodox sensor proteins, a putative nucleotide binding site [Walker box type A] in its linker region, and a region in its periplasmic domain with significant homology to the TonB protein ofEscherichia coli. We investigated potential functions of these sequences by constructingB. pertussis strains that express mutant BvgS derivatives. The His₁₁₇₂ residue in the output domain was exchanged for Gln, and the Walker motif was mutated either by the replacement of Lys₆₂₅ by Arg, or of Gly₆₂₄ by Val and Lys₆₂₅ by Leu. To analyse the TonB motif, the periplasmic domain of BvgS was replaced with the corresponding domain of EvgS, anE. coli sensor that is highly homologous to BvgS but lacks the similarity with TonB. All mutations except the conservative Lys/Arg exchange in the Walker box caused the inactivation of BvgS, indicating the functional importance of the conserved motifs. The activity of the mutant proteins could be restored by complementation in trans with various separately expressed, truncated parts of BvgS. Mutations in the BvgS receiver domain could be complemented not only by a construct expressing the wild-type receiver and output domains, but also by the derivative containing the His-Gln exchange. Therefore, the histidine motif, although important for BvgS function, is not essential for complementation of BvgS mutants. The mutations in the Walker box and in the periplasmic domain could be complemented by a truncated BvgS derivative lacking the receiver and output domains. The characterization of a spontaneous revertant of the strain expressing the originally inactive EvgS/BvgS hybrid protein revealed the presence of a mutation in the BvgS linker region, conferring constitutive activity on the protein. As TonB energizes transport processes across the outer membrane ofE. coli, the strain expressing the constitutive EvgS/BvgS hybrid protein lacking the TonB motif was used in preliminary investigations of a possible direct involvement of BvgS in transport processes.