Pre‐copulation intervals,copulation frequencies,and initial progeny sex ratios in two biotypes of whitefly,Bemisia tabaci

The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is a species complex, and its systematic classification requires controlled crossing experiments among its genetic groups. Accurate information on pre‐copulation intervals, copulation frequencies, and initial frequency of egg fertilization of newly emerged adults is critical for designing procedures for collecting the virgin adults necessary for these experiments. In the literature, considerable variation is reported between B. tabaci populations, with respect to the length of the pre‐copulation interval and the initial frequency of egg fertilization. Here, we used a video‐recording method to observe continuously the copulation behaviour of the Mediterranean/Asia Minor/Africa (B biotype) and the Asia II (ZHJ1 biotype) groups of B. tabaci. We also recorded the initial frequency of egg fertilization, as determined by the sex of the progeny. When adults were caged in female–male pairs on leaves of cotton plants, the earliest copulation events occurred 2–6 h after emergence; at 12 h after emergence 56–84% of the females had copulated at least once, and nearly all (92–100%) had copulated at least once by 36 h after emergence. Both females and males copulated repeatedly. Approximately 80 and 20% of copulation events occurred during the photophase and scotophase, respectively. By 72 h post‐emergence, the females of the B and ZHJ1 biotypes had copulated on average 6.1 and 3.9 times, respectively. When adults were caged in groups on plants 1–13 h after emergence, 30–35% of the eggs deposited during this period were fertilized, and approximately 90% of females were fertilized by the end of the 13 h. Although timing of copulation differed in detail between the two genetic groups, the results demonstrate that B. tabaci adults can start to copulate as early as 2–6 h post‐emergence and the majority of females can become fertilized on the day that they emerge.     

Application of muonic X-rays for elemental analysis

Because of the large μ mass compared to the electron mass, the muonic X-rays have energies very suitable for standard γ-ray spectroscopy (Ge detectors), so every element is easily recognized. By selecting the primary μ energies appropriately any part of the specimen, also well inside, can be nondestructively investigated. On the other hand, surface layers may be analyzed. Accuracies of quantitative analyses are 1% of the atomic abundance of the element in question in favorite cases. Results on applications in nuclear medicine and surface physics are presented, and ways of improving the muon flux density are discussed.     

Localization of vanadium-containing particles in the lungs of uranium/vanadium miners

Several geological formations of the Utah-Colorado mining region mined for uranium ore during and after World War II had been mined earlier for vanadium. Therefore, most miners and millers from that region were exposed to those metals’ ores or tailings at one time or another. Preliminary investigation to determine uranium and vanadium retained in the lungs of a former uranium miner and miller from this region, who died of lung cancer (mesothelioma), showed a high nonuniform distribution of vanadium. This observation led to the hypothesis that the vanadium content in the lungs could be associated with inhaled particles. Further examination of spectra of characteristic X-rays obtained by scanning particle-induced X-ray emission (microPIXE) of an autopsy sample of this lung indicated that vanadium was indeed present in localized sites within the 20-μm spatial resolution of the proton beam. This work points out that the microPIXE-RBS (Rutherford backscattering) test for vanadium can be used for site localization of inhaled particles retained in the lungs. Further studies are in progress to: (i) locate uranium-bearing particles in lung tissues of former uranium miners and millers; and (ii) evaluate the local doses of alpha radiation received from these particles.     

The effect of the dark interval in intermittent light on thylakoid development: photosynthetic unit formation and light harvesting protein accumulation

Etiolated bean plants were grown in intermittent light with dark intervals of shorter or longer duration, to modulate the rate of chlorophyll accumulation, relative to that of the other thylakoid components formed. We thus produced conditions under which chlorophyll becomes more or less a limiting factor. We then tested whether LHC complexes can be incorporated in the thylakoid. It was found that an equal amount of chlorophyll, formed under the same total irradiation received, may be used for the stabilization of few and large-in-size PS units containing LHC components (short dark-interval intermittent light), or for the stabilization of many and small-in-size PS units with no LHC components (long dark-interval intermittent light). The size of the PS units diminishes as the dark-interval duration is increased, with no further change after 98 minutes. The PSII/cytf ratio remains constant throughout development in intermittent light and equal to that of mature chloroplasts (PSII/cytf = 1) except in the case of very long dark-interval regimes, where about half PSII units per cytf are present. The PSII/PSI ratio was found to be correlated with the PSII unit size (the larger the size, the lower the ratio). The number of PSI units operating on the same electron transfer chain varied depending on the size of the PSII unit (the larger the PSII unit size, the more the PSI units per chain). The results suggest that it is not the chlorophyll content per se which regulates the stabilization of LHC in developing thylakoids and consequently the size of the PS units, but rather the rate by which it is accumulated, relative to that of the other thylakoid components.Abbreviations Chl Chlorophyll - CL Continuous light - CPa the reaction center complex of PSII - CPI the reaction center complex of PSI - CPIa Chlorophyll protein complex containing the CPI and the light harvesting complex of PSI - fr w fresh weight - LDC Light dark cycles - LHC-I Light-harvesting complex of PSI - LHC-II Light harvesting complex of PSII - PS photosystem - PSI photosystem I - PSII photosystem II     

In vitro proliferation of saffron (Crocus sativus L.) stigma

Excised young intact stigmas plus ovaries of Crocus sativus L. were cultured on Linsmaier-Skoog media supplemented with either a cytokinin or an auxin alone or in combinations. Benzyladenine and kinetin at concentrations of 0.1, 1, and 5 mgl^-1 supported growth, and crocin was biosynthesized in the stigmas in vitro. Auxins had little effect. Young excised single stigmas or half ovaries were also cultured so as to form stigma-like structures in order to explore a possible new approach to industrial production of the spice, saffron. On Linsmaier-Skoog and Nitsch media supplemented with kinetin at concentration of 1 or 5 mgl^-1 and alpha-naphthalene acetic acid or indole-butyric acid at concentration of 0.1 or 10 mgl^-1 in combinations, stigma-like structures appeared directly and indirectly (through meristematic tissue), grew and matured. The maximum number of structures were 75 per half ovary. Three kinds of yellow pigments including crocin were tentatively identified by TLC in the stigma-like structures as was the case for the in vivo grown natural stigma, although the contents were lower.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxy-acetic acid - IAA indole-acetic acid - IBA indole-butyric acid - NAA alpha-naphthalene-acetic acid - TLC thin layer chromatography     

Aluminum,Fe, Ca,Mg, K,Mn, Cu,Zn and P in above- and belowground biomass. I.Abies amabilis andTsuga mertensiana

In a mature mixed subalpine stand ofTsuga mertensiana andAbies amabilis, significantly higher Al levels were found in foliage, branch and root tissues ofT. mertensiana.Tsuga mertensiana had significant increases in Al, Ca and Mn levels with increasing foliage age. In current foliage,T. mertensiana had lower levels of Ca, similar levels of Mg and P, and higher levels of Mn thanA. amabilis. Both tree species had Cu and Fe present at higher levels in branch than foliage tissues. Fine roots had the highest concentrations of Al, Fe and Cu but the lowest Ca and Mn concentrations of all tissues analyzed. In the roots of both species, phloem tissues always had significantly higher Al levels than xylem. Fine roots (< 1 and 1–2 mm) ofT. mertensiana had higher Al levels than were found inA. amabilis. Roots greater than 2 mm in diameter exhibited no significant differences in Al levels in phloem or xylem tissue betweenA. amabilis andT. mertensiana. The two species show a clear difference in their ability to accumulate specific elements from the soil.     

The effect of different night conditions on the CO2 fixation in a lichen Xanthoria parietina

CO₂ fixation was studied in a lichen, Xanthoria parietina, kept in continuous light, and with cyclic changes in light intensity, dark period or temperature. The diurnal and seasonal courses of CO₂ exchange were followed. The rate of net photosynthesis was observed to fall from morning to evening, and this decline was more pronounced in winter than in summer. The maximal net photosynthetic rate, 223 ng CO₂g^-1dws^-1, occured in winter and the minimum, 94 ng CO₂g^-1dws^-1, late in spring. The light compensation point in summer was four times as high as in winter. In continuous light (180 or 90 mol photons m^-2s^-1, 15°C) net photosynthesis decreased noticeably during one week, falling below the level maintained in a 12 h light: 12 h dark cycle. Photosynthetic activity did not decrease, however, in lichens held in continuous light (90 mol photons m^-2s^-1) with cyclic changes of temperature (12 h 20 °C: 12 h 5 °C). Active photosynthesis was also maintained in light of cyclically changing intensity (12 h: 12 h, 15 °C) when night-time light was at least 75% lower than illumination by day. A dark period of 4 hours in a 24-h light:dark cycle was sufficient to keep CO₂ fixation at the control level. It seems that plants need an unproductive period during the day to survive and this can be induced by fluctuations in light and/or temperature.     

Influence of cadmium on the distribution of the essential trace elements zinc and copper in the liver and kidneys of rats

Cd induced changes of Zn and Cd distribution in the liver and kidneys were studied in relation to Cd metallothionein (MT) synthesis. Wistar male rats were given CdCl₂ by sc injection of .8, 1.5, and 3.0 mg Cd/kg three times a week for three weeks. Cd levels of liver and kidneys increased with the increment of Cd dosage and 80–90% of Cd was found in the cytosol. The MT fractions contained 80–89% cytosolic Cd in the liver and 55–75% Cd in the kidneys. Zn concentrations in the liver increased following Cd administration, But Zn in the kidneys showed only slight increase. There was a distinct decrease of Cu concentration in the liver of the 3.0 mg group. In contrast, Cu concentrations in the kidneys increased about three times in the .8 and 1.5 mg Cd groups, but Cu in the 3.0 mg group showed only 1.5 times increase. The changes of these metal concentrations were observed mainly in the cytosol. Non-MT-Cd in the kidneys was maximum in the 1.5 mg group, but the 3.0 mg group showed significant decrease. In parallel with this decrease of Cd, Cu and Zn in the kidneys showed similar decrease. When the kidneys are injured, Zn and Cu appear to leak from this organ.     

Depolarized fluorescence photobleaching recovery

The effects of the fact that the laser sources typically used in fluorescence photobleaching recovery (FPR) experiments in the most commonly employed in-line microscope imaging geometries, are highly linearly polarized, are examined in some detail. The implications of the results, in particular for the interpretation of FPR data in complex cell membrane systems in terms of laterally mobile and immobile sub-populations of the labelled molecular species of concern, are discussed. Methods of experimentally eliminating the potentially major rotational diffusion-based artifacts, different from those appropriate to three-dimensional (solution or suspension) systems which require other than in-line geometries, are delineated.Abbreviations FPR fluorescence photobleaching recovery - FRAP fluorescence recovery after photobleaching - 2- and 3-D two- and three-dimensional     

Turnover of Brain Monoamine Oxidase Measured In Vivo by Positron Emission Tomography Using l-[11C]Deprenyl

The distribution of carbon-11-labeled L-deprenyl, an irreversible inhibitor of monoamine oxidase type B (MAO-B), was determined in the baboon brain by positron emission tomography. The irreversible blood-to-brain transfer constant (influx constant, K_i) was measured using a complete metabolite-corrected arterial plasma concentration curve. This influx constant was used as a measure of functional enzyme activity for sequential determinations of MAO-B recovery following a single high dose of unlabeled l -deprenyl. The half-life for turnover of MAO-B was thus determined to be 30 days. Using appropriate irreversible inhibitors, this procedure should be generally useful for determining enzyme turnover rates in any organ in vivo and can be applied to some human studies as well.