Seasonal Effects on Photosynthetic Electron Transport and Fluorescence Properties in Isolated Chloroplasts of Pinus silvestris

Chloroplasts were isolated from primary needles of 1-year-old seedlings and from secondary needles of a 20-year-old pine tree in a natural stand. In autumn the electron transport capacities of PSII, PSI and PS (II + I) decreased and the electron transport between PSII and PSI became inhibited in October in the 20-year-old tree. This inhibition lasted until May the following year. The partial reactions of PSI and PSII still showed low but fairly constant rates during the whole winter seedlings. Seasonal changes in the electron transport properties of 1-year-old showed the same general trends as observed in the 20-year-old tree, but the changes were less pronounced. However, in snow-covered seedlings the PSI-mediated electron transport and the electron transport from H₂O to NADP increased during the late winter when the seedlings were still covered by snow. The total chlorophyll content of the needles decreased in autumn and winter. Low temperature fluorescence ratios of F692/F680 and F726/F680 indicated more severe destruction of the chlorophyll a antennae closely associated with the two photosystems than of the light harvesting chlorophyll a/b complex. In this case, too, the changes were more pronounced in the 20-year-old tree than in the 1-year-old seedlings. The chlorophyll/P700 ratios indicated a more marked reduction in the reaction centre molecules during autumn than in the antennae chlorophyll molecules. The changes in electron transport and low temperature fluorescence properties which occurred during autumn and winter were mainly reversed during spring.     

Studies on broccoli necrotic yellows virus

Electron microscopy of infected D. stramonium cells showed that the virus particles occurred in the cytoplasm. Particles were mostly bacilliform and measured 297 ± 18 times 64 ± 4 nm. In negatively stained leaf homogenates, particles were mostly disrupted; intact particles measured 267 ± 20 times 69 ± 6 nm. In brussels-sprout cells containing BNYV and CIMV, BNYV particles were rarely found compared with those of CIMV, and they occurred within and near CIMV inclusion bodies. BNYV particles were also found in extracts of virus-carrying Brevicoryne brassicae. Broccoli necrotic yellows (BNYV) and cauliflower mosaic (CIMV) viruses occurred together in naturally infected Brussels sprout plants, which showed conspicuous symptoms, and in cauliflower. BNYV was transmitted to and maintained in Datura stramonium and Hyoscyamus niger. It was partially purified from D. stramonium. Using these preparations, from which inhibitor had been removed, BNYV was manually transmitted to cauliflower, causing mild symptoms, and to Brussels sprout, causing a symptomless infection. BNYV also infected Sinapis alba but not cabbage, lettuce, Sonchus oleraceus or Plantago major. BNYV was transmitted by Brevicoryne brassicae but not by Myzus persicae, Hyperomyzus lactucae or Aleyrodes proletella.     

Ceratophyllum demersum hampers phytoplankton development in some small Norwegian lakes over a wide range of phosphorus concentrations and geographical latitude

1. Data on submerged and floating-leafed macrophytes, phytoplankton, nutrients (N, P) and calcium were collected from twenty-four small lakes ( 1 km²) over a wide range of latitudes in Norway. The majority of the investigated lakes were mesotrophic or eutrophic, and most of the lakes were markedly affected by diffuse and point-source runoff from agriculture. According to their macrophyte species composition, the majority of the lakes can be classified as Potamogeton lakes or Chara lakes, or a combination of these.
2. This study is consistent with the 'two alternative stable states' hypothesis. We observed clearwater lakes with dense macrophyte cover over a wider range of total P concentration than has been reported previously: from 30 to more than 700 mg P m^–3. The clearwater state was only observed in lakes with mean depths of less than 1.9 m.
3. Most clear lakes with high cover of submerged vegetation showed indications of N limitation.
4. In this study nearly all the macrophyte-dominated lakes with P concentrations above 30 mg m^–3 had dense stands of Ceratophyllum demersum (L.). This indicates that Ceratophyllum may also play an important role in stabilizing and maintaining a clearwater state at high P concentrations.     

Morphology and Infraciliature of Trochiliopsis australis N. Sp., Pelagohalteria viridis (Fromentel, 1876) N. G., N. Comb., and Strobilidium lacustris N. Sp. (Protozoa,Ciliophora)1

Three ciliate species from Australia and Norway were examined by silver impregnation, biometry, and scanning electron microscopy. Trochiliopsis australis n. sp. (order Nassulida, family Microthoracidae) differs from the single other known species of the genus, T. opaca, by its prominent ridges on the left side, the distinctly longer anterior segment of somatic kinety 2, and by the doubled total number of kinetosomes. Pelagohalteria n. g. (order Oligotrichida, family Halteriidae) differs from Halteria by the structure of the bristle complexes, which are composed of a vertically and a horizontally oriented row of kinetosomes. Two Halteria species belong to the new genus: P. viridis (Fromentel, 1876) n. comb., which is redescribed here, and P. cirrifera (Kahl, 1935) n. comb. Strobilidium lacustris n. sp. (order Oligotrichida, family Strobilidiidae) differs from its nearest relative, S. velox, by the smooth pellicle, the absence of symbiotic green algae, and by its larger size.     

Molecular evolution of rodent insulins

Several trees of amino acid sequences of rodent insulins were derived with the maximum-parsimony procedure. Possible orthologous and paralogous relationships were investigated. Except for a recent gene duplication in the ancestor of rat and mouse, there are no strong arguments for other paralogous relationships. Therefore, a tree in agreement with other biological data is the most reasonable one. According to this tree, the capacity to form zinc-binding hexamers was lost once in the ancestor of the hystricomorph rodents, followed by moderately increased evolutionary rates in the lineages to African porcupine and chinchilla but highly increased rates in at least three independent lines to other taxa of this suborder: guinea pig, cuis, and Octodontoidea (coypu and casiragua).      

Genotypic differences in embryonic life history traits of Folsomia quadrioculata (Collembola: Isotomidae) across a wide geographical range

1. Life history traits play a central role in adaptation to specific environmental conditions. Egg development time, hatchling, and egg batch size in 10 populations of the soil‐dwelling collembolan species Folsomia quadrioculata (Tullberg, 1871) from diverse habitats across arctic and temperate regions, ranging in latitude from 43 to 81°N were studied. 2. For all traits, 15 °C was used as the reference temperature. Phenotypic plasticity was studied by changing temperature to 10 and 20 °C in hatchling size, and to 20 °C in egg development time. The effect of latitude, climatic zone, and summer temperature at their sites of sampling was tested to address the hypotheses that populations from cooler areas would have (i) a faster temperature‐dependent egg development, (ii) a larger hatchling size, (iii) smaller egg batches and (iv) higher phenotypic plasticity 3. The first and fourth hypothesis were not supported, whereas the second and third were partly supported when including the whole latitudinal gradient, but not within regions. Plasticity showed a complex pattern, including large differences between populations from similar macroclimates and considerable similarity between some populations from contrasting climates. Small effects of latitude and macroclimatic variables emphasised that local climate and microhabitat should be taken into account when evaluating thermal conditions as possible drivers of population‐specific differences in soil‐dwelling ectotherms. 4. There was a trade‐off between egg batch and hatchling sizes. A weak correlation between the population mean egg development time and the mean hatchling size suggested that the populations are, or have been, exposed to differential selection.     

Observed trends in winegrape maturity in Australia

An extensive assessment of historical trends in winegrape maturity dates from vineyards located in geographically diverse winegrape growing regions in Australia has been undertaken. Records from 44 vineyard blocks, representing a range of varieties of Vitis vinifera L., were accessed. These comprise 33 short‐term datasets (average 17 years in length) and 11 long‐term datasets, ranging from 25 to 115 years in length (average 50 years). Time series of the day of the year grapes attain maturity were assessed. A trend to earlier maturity of winegrapes was observed in 43 of the 44 vineyard blocks. This trend was significant for six out of the 11 long‐term blocks for the complete time period for which records were available. For the period 1993–2009, 35 of the 44 vineyard blocks assessed displayed a statistically significant trend to earlier maturity. The average advance in the phenology was dependent on the time period of observation, with a more rapid advance over more recent decades. Over the more recent 1993–2009 period, the average advance was 1.7 days year, whereas for the period 1985–2009 the rate of advance was 0.8 days yr^?1 on average in the 10 long‐term vineyard blocks assessed for cross‐regional comparison. The trend to earlier maturity was associated with warming temperature trends for all of the blocks assessed in the study.     

A remarkable new leafhopper genus and species from Thailand (Hemiptera: Cicadellidae: Stegelytrinae) with modified legs and 'hairy' eggs

Abstract.  Pataniolidia magnifica Wei & Webb gen.n. , sp.n. from Thailand is described and illustrated, and placed in the leafhopper subfamily Stegelytrinae. Its unusual features, including 'membracid-like' legs and 'hairy' eggs, are discussed, and new tarsal sensilla for Cicadellidae are described.