Acaricidal properties of the essential oil and precocene II obtained from Calea serrata (Asteraceae) on the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Calea serrata Less. (Asteraceae), an endemic species of south Brazil known as "quebra-tudo", is used in Afro-Brazilian religious rituals and in folk medicine for treating liver disorders. Phytochemical studies of the n-hexane extract of this plant demonstrated the presence of precocene II, a benzopyran derivative known for its insecticidal activity. The aim of this work was to isolate this benzopyran and determine the chemical composition of the essential oil of C. serrata and further to evaluate the acaricidal activity of the essential oil and precocene II against the larvae of Rhipicephalus (Boophilus) microplus. The LC(99.9) and LC(50) values obtained with the oil, which presents precocene II and sesquiterpenes, were 3.94 μL/mL and 0.28 μL/mL, respectively. For precocene II this values were 4.25mg/mL and 1.78 mg/mL, respectively. The results indicate a synergistic interaction between the components of the oil and precocene II.     

马尾松人工林近自然化改造不同阶段森林凋落物持水特性研究

笔者以湖北省团风县马尾松人工林近自然林经营过程中不同阶段森林凋落物数量及其持水量等水文特征进行了研究,结果表明:不同阶段林下凋落物的现存数量依次为:竞争选择阶段>恒续林阶段>质量形成阶段>建群阶段;不同阶段半分解层和未分解层的凋落物持水量依次为:建群阶段<质量形成阶段<竞争选择阶段<恒续林阶段。     

大别山自然保护区天然次生林分类及其生态位特征

通过样方调查、TWINSPAN分类与DCA排序及生态位分析,以物种重要值为分类排序与生态位计测的数据指标,研究湖北省大别山自然保护区天然次生林分类及优势木本生态位宽度与重叠。结果表明:应用TWINSPAN分类并结合DCA排序,可将植被划分为6个群落类型(针叶林Ⅰ、Ⅱ,针阔混交林Ⅰ、Ⅱ,E落叶阔叶林和F常绿落叶阔叶混交林)。同时DCA排序图中反映了植被由针叶林Ⅰ、Ⅱ——针阔混交林Ⅰ、Ⅱ——落叶阔叶林与常绿落叶混交林的格局变化。在针叶林Ⅰ、Ⅱ中,马尾松与黄山松生态位宽度较大,在针阔混交林Ⅰ、Ⅱ中,松类与栎类等都占据较大生态位,阔叶林阶段占据优势的木本种类更多,不同群落主要种群生态位宽度随着演替表现出相应的变化规律,同时也反映了多数广生态位物种间的生态位竞争。对于大多数演替阶段群落中的物种间的关系,以生态位重叠指数和物种生活特性作为主要的评价标准是可行的。     

Beziehungen zwischen Kohlenstoff-und Stickstoffmetabolismus bei Pflanzen — eine Übersicht über ausgewählte Aspekte

Zusammenfassung Die mannigfaltigen Wechselbeziehungen zwischen photosynthetischer Kohlenstoffassimilation und N-Metabolismus haben weltweit eine Vielzahl von Untersuchungen stimuliert. Es ist versucht worden, zu einigen ausgewählten Aspekten dieses komplexen Problemkreises eine Übersicht über den gegenwärtigen Kenntnisstand zu geben. Von den Prozessen auf molekularer Ebene wurden besonders der photorespiratorische N-Zyklus und die Beziehungen zwischen Photosynthese und Nitratassimilation berücksichtigt. Auf der organismischen Ebene spielen Wechselwirkungen zwischen Photosynthese und N-Haushalt in bezug auf die Ertragsbildung eine besondere Rolle. Sie wurden am Beispiel des Getreides erörtert. Mathematische Modelle der Photosynthese und Ertragsbildung haben in stärkerem Maße als bisher dem Einfluß des N-Metabolismus Rechnung zu tragen. Daher wurde der Darstellung dieses Problemkreises besondere Aufmerksamkeit gewidmet.

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Interactions between carbon and nitrogen metabolism in plants — a review of some selected topics

Summary The multiple interactions between photosynthetic carbon assimilation and nitrogen metabolism have stimulated worldwide investigations. In the present review some selected topics of this field are discussed. At the molecular level the photo-respiratory nitrogen cycle and relationships between photosynthesis and nitrate assimilation are especially considered. At the whole plant level relationships between photosynthesis and N metabolism are of importance with regard to yield formation of cultivated plants. As an example the situation in cereals is discussed. Mathematical models of photosynthesis and yield formation have to consider the influence of nitrogen metabolism on these processes. Therefore this aspect was treated in some detail.

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Die Bedeutung der Grannen für die Kornentwicklung III. Photosyntheseintensität der Ähren verschiedener Gersten- und Weizensorten

Zusammenfassung Die Photosyntheserate blühender Gersten- und Weizenähren verschiedener Sorten wurden gemessen. Die Sorten unterschieden sich in Vorhandensein, Form und Größe der Grannen.Die Photosyntheseleistung ist bei den stark begrannten Formen am größten, am geringsten bei den unbegrannten. Die Werte für kurzgrannige Varietäten lagen dazwischen.

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Summary The photosynthetic rate of flowering barley and wheat ears from different sorts was measured. The sorts differed in presence, form and size of awns.The intensity of photosynthesis was highest among the forms with long awns and lowest among the awnless sorts. The values of the short-awned varieties lay between them.

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Herrn Dr. Lehmann danken wir für die Unterstützung bei der Auswahl gegeigneter Formen und die Überlassung von Saatgut.     

Potentielle Photosyntheseintensität von Gerstensorten des Gaterslebener Sortiments

Zusammenfassung Die potentielle (maximale) Photosyntheseintensität der Fahnenblattspreiten von zehn zweizeiligen und acht mehrzeiligen Sommergerstensorten des Gaterslebener Sortiments wurde gemessen, um die Variabilität dieses Merkmals innerhalb der Art zu ermitteln. Die Werte für die apparente Photosynthese liegen bei den zweizeiligen Gersten zwischen 8,7 und 19,8 mg CO₂/dm²·h und bei den mehrzeiligen zwischen 8,2 und 13,8 mg CO₂/dm²·h. Die Korrelation dieser Werte zu dem Korngewicht/Ähre ist erwartungsgemäß nicht sehr eng (0,65 bei den mehrzeiligen) beziehungsweise fehlt (0,22 bei den zweizeiligen). Dies ist auf den Einfluß anderer an der Ertragsbildung beteiligter Komponenten zurückzuführen. Die Variabilität des Merkmals potentielle Photosyntheseintensität ist groß genug, um den Gedanken an eine Selektion nahezulegen. Gegenwärtig stehen dem noch methodische Schwierigkeiten gegenüber.

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Summary The potential (maximum) photosynthetic rate of flag leaves of 10 two-rowed and 8 six-rowed spring barleys from the Gatersleben collection was measured to find out the variability of this character among the speciesHordeum vulgare. The values of apparent photosynthetic rate of the two-rowed barleys were between 8,7 and 19,8 mg CO₂/dm² · h and between 8,2 and 13,8 mg CO₂/dm² · h for the six-rowed varieties. The correlation between these values and the grain weight/ear is small (0,75) for the six-rowed, respectively insignificant (0,22) for the two-rowed barleys. This is caused by the influence of other yield-forming components. The variability of the potential photosynthetic rate is large enough to take into consideration a selection of positive extrems, but this is essentially a methodical problem.

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Analysis of caprine IgG1 and IgG2 subclass responses to Chlamydia psittaci infection and vaccination

Enzyme-linked immunosorbent assays (ELISAs) specific for caprine IgG(H+L), IgG1 and IgG2 were developed and evaluated for serodiagnosis of Chlamydia psittaci infections in a Tunisian goat flock with currently occurring chlamydial abortions and a clinically inapparent goat flock of an animal research facility. Additionally, ELISAs were applied to record the IgG1 and IgG2 dynamics of four goats vaccinated with inactivated Chlamydia psittaci and Coxiella burnetii. For screening purposes, the IgG(H+L) ELISA proved to be superior to the complement fixation test because it detected a larger number of chlamydial abortions and was easier to perform and to interpret. Analysis of Chlamydia psittaci-specific IgG1 and IgG2 responses to naturally occurring infections by ELISA revealed high IgG1 levels associated with IgG2 in goats with current abortions, whereas clinically inapparent, but seropositive goats were characterized by significantly lower IgG1 levels only (P less than 0.001). Similarly, the four vaccinated goats responded initially with Chlamydia psittaci-specific IgG1, whereas second and third vaccinations induced (as in goats with chlamydial abortions) predominantly IgG1, but also IgG2. The results indicated that clinically inapparent chlamydial infection may be distinguished from overt disease by analysing specific IgG1 and IgG2 responses. Applying Coxiella burnetii- specific ELISAs on field samples, IgG1 alone could be detected in eight, IgG2 alone in one and IgG1 combined with IgG2 in nine goats. The coxiella-specific antibody response of the four vaccinated goats was--in contrast to the chlamydia-specific response--characterized by IgG2 dominance.     

Missing OH reactivity in a forest: evidence for unknown reactive biogenic VOCs

Forest emissions of biogenic volatile organic compounds (BVOCs), such as isoprene and other terpenes, play a role in the production of tropospheric ozone and aerosols. In a northern Michigan forest, the direct measurement of total OH reactivity, which is the inverse of the OH lifetime, was significantly greater than expected. The difference between measured and expected OH reactivity, called the missing OH reactivity, increased with temperature, as did emission rates for terpenes and other BVOCs. These measurements are consistent with the hypothesis that unknown reactive BVOCs, perhaps terpenes, provide the missing OH reactivity.