Proteins and polyamines during dormancy breaking of European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) seeds

The studies were carried out on Fagus sylvatica seeds during stratification and their germination. After imbibition beechnuts were subjected to cold (3 °C — temperature which breaks dormancy) or warm (15 °C — temperature unable to break dormancy) stratification and alternatively were treated with polyamine synthesis inhibitors: canavanine and DFMO (difluoromethylornithine). After cold stratification in embryo axes we found (using 2-D electrophoresis) about 150 new proteins absent in dry seeds. Exogenous spermidine increased the protein synthesis, percent of germinated seeds and accelerated breaking of dormancy. In contrast, canavanine and DFMO decreased dynamic of protein synthesis, quantity of proteins probably synthesised de novo, and percent of germinated seeds. The maximum of polyamine content in embryo axes during cold stratification preceded such the maximum during warm stratification. Irrespective of the influence of PAs and inhibitors of PA synthesis, the comparison of electrophoregrams and autoradiograms showed that different groups synthesised de novo appeared after different periods of cold stratification. Probably the part of this protein is associated with Fagus sylvatica seeds dormancy breaking.     

Fecundity and feeding of <Emphasis Type="Italic">Galerucella calmariensis</Emphasis> and <Emphasis Type="Italic">G. pusilla</Emphasis> on <Emphasis Type="Italic">Lythrum salicaria</Emphasis>

Fecundity and feeding of two introduced sibling biological control species, Galerucella calmariensis and G. pusilla (Coleoptera: Chrysomelidae) on purple loosestrife, Lythrum salicaria L. (Lythraceae) were compared at constant temperatures of 12.5, 15, 20, 25, and 27.5 °C. Larval feeding was also carried out at 30 °C, but at this temperature, larvae developed only to the L2 stage and none pupated. Thus, data for this temperature were not used in the analysis. There were significant species × temperature interactions in fecundity. Of the two species, Galerucella pusilla laid more eggs. Although egg production of both species was lowest at 12.5 °C and increased to 20 °C, at higher temperatures, the two species reacted differently. From 25 to 27.5 °C, egg production decreased for G. pusilla, but G. calmariensis fecundity peaked at 27.5 °C. Significant temperature × species × life-stage interactions were also observed in feeding. For each species, the amount of feeding varied with temperature and stage of development. Galerucella pusilla adults consumed more foliage at 15, 20, and 27.5 °C. However, at 12.5 °C G. calmariensis adults fed more than G. pusilla. G. pusilla larvae consumed an average of 25% less foliage than G. calmariensis. The lower larval consumption of G. pusilla suggests that when food is limited, G. pusilla larvae may have a higher survival rate because of its ability to complete larval development with less food and produce more progeny due to its greater fecundity. When food is not limited neither species would have a competitive advantage and both species could coexist temporally and spatially. However, since G. calmariensis larvae consumed more leaf material, the larval stage of this species would have a greater impact on purple loosestrife than G. pusilla.     

Dormancy of<Emphasis Type="Italic"> Arabidopsis</Emphasis> seeds and barley grains can be broken by nitric oxide

Seeds of Arabidopsis thaliana (L.) Heynh. and grains of barley (Hordeum vulgare L.) were used to characterize the affects of nitric oxide (NO) on seed dormancy. Seeds of the C24 and Col-1 ecotypes of Arabidopsis are almost completely dormant when freshly harvested, but dormancy was broken by stratification for 3 days at 4°C or by imbibition of seeds with the NO donor sodium nitroprusside (SNP). This effect of SNP on dormancy of Arabidopsis seeds was concentration dependent. SNP concentrations as low as 25 M reduced dormancy and stimulated germination, but SNP at 250 M or more impaired seedling development, including root growth, and inhibited germination. Dormancy was also reduced when Arabidopsis seeds were exposed to gasses that are generated by solutions of SNP. Nitrate and nitrite, two other oxides of nitrogen, reduced the dormancy of Arabidopsis seeds, but much higher concentrations of these were required compared to SNP. Furthermore, the kinetics of germination were slower for seeds imbibed with either nitrate or nitrite than for seeds imbibed with SNP. Although seeds imbibed with SNP had reduced dormancy, seeds imbibed with SNP and abscisic acid (ABA) remained strongly dormant. This may indicate that the effects of ABA action on germination are downstream of NO action. The NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3 oxide (cPTIO) strengthened dormancy of unstratified and briefly stratified Arabidopsis seeds. Dormancy of three cultivars of barley was also reduced by SNP. Furthermore, dormancy in barley grain was strengthened by imbibition of grain with cPTIO. The data presented here support the conclusion that NO is a potent dormancy breaking agent for seeds and grains. Experiments with the NO scavenger suggest that NO is an endogenous regulator of seed dormancy.Abbreviations ABA Abscisic acid - cPTIO 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3 oxide - GA Gibberellin - SNP Sodium nitroprusside - NO_x Gaseous oxides of nitrogen     

The effect of the temperature of drying on viability and some factors affecting storability of <Emphasis Type="Italic">Fagus sylvatica</Emphasis> seeds

Beech (Fagus sylvatica L.) seeds, which are tolerant to desiccation, freshly harvested after shedding, were dried at 15 and 30 °C and at the similar rate, to 9% of water content. A slight decrease of germinability was observed in seeds dried at 30 °C. Moreover, there was a notably higher solute leakage and a higher level of lipid hydroperoxides. Seeds dried at 30 °C contained less PC and PE and a lower level of unsaturated fatty acids (18:2 and 18:3), sterols and α-tocopherol. These results as well as changes in ascorbate and glutathione contents provide conclusive evidence for the presence of oxidative stress in beech seeds desiccated at 30 °C, which damaged membranes due to increased lipid peroxidation and changed membrane structure leading to their enhanced sensibility to free radical attack during storage.     

RETRACTED ARTICLE: Transgenic ramie [<Emphasis Type="Italic">Boehmeria nivea</Emphasis> (L.) Gaud.]: factors affecting the efficiency of <Emphasis Type="Italic">Agrobacterium</Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>-mediated transformation and regeneration

In the present study, an efficient Agrobacterium-mediated gene transformation system was developed for ramie [Boehmeria nivea (L.) Gaud.] based on the examinations of several factors affecting plant transformation efficiency. The effects of Agrobacterium cell density, acetosyringone, co-cultivation temperature, co-cultivation duration, co-cultivation photoperiod and pH on stable transformation were evaluated. Agrobacterium at a concentration of OD = 0.5–0.8 improved the efficiency of transformation. Concentration of acetosyringone at 50 mg/L during co-cultivation significantly increased transformation efficiency. Co-cultivation at 20°C, in comparison to 15, 25 and 28°C, consistently resulted in higher transformation frequencies. A relatively short co-cultivation duration (3 days) was optimal for ramie transformation. Co-cultivation medium at pH 5.9 and co-cultivation in darkness both improved the transformation efficiencies of ramie. An overall scheme for producing transgenic ramie is presented, through which an average transformation rate from 10.5 to 24.7% in five ramie varieties was obtained. Stable expression and integration of the transgenes were confirmed by histochemical GUS assay, kanamycin painting assay, PCR and Southern blotting. This optimized transformation system should be employed for efficient Agrobacterium-mediated transformation of ramie. An erratum to this article can be found at     

<Emphasis Type="Italic">In vitro</Emphasis> germination and axillary shoot propagation of <Emphasis Type="Italic">Centaurea zeybekii</Emphasis>

In vitro culture is an important aid for ex situ conservation of rare, endemic or threatened plants. In this work, we establish an efficient method for the seed germination, seedling development, and axillary shoot propagation of Centaurea zeybekii Wagenitz. The seeds, collected from a wild population, were surface sterilised and cultured on various in vitro germination media. The effects of photoperiod and temperature on seed germination were also investigated. Germinations were obtained after 6 weeks in culture and the radicle emergence was evaluated as a main indicator. A high frequency of germination was obtained on distilled water supplemented with vitamines and 1 mg/L GA₃. Although the seed germination frequencies were not affected by photoperiod, the highest germination frequency was obtained at 24 ± 2°C. A high frequency of axillary shoot proliferation was produced on MS medium supplemented with 1 mg/L BA. Then, the axillary shoots were separated and transferred to MS medium with or without plant growth regulators for rooting. Rhizogenezis was promoted after 6 weeks only in MS and 1/2 MS media containing 0.5 mg/L IBA. The rooting process was very slow and the percentage of shoot rooting was also very low (15%). The present study not only enables reinforcement of wild plant populations using ex situ growth of individuals, but it also helps to large number of aseptic seedling to use it in clonaly micropropagation studies.     

Seed germination ecology of the threatened endemic Iberian <Emphasis Type="Italic">Delphinium fissum</Emphasis> subsp. <Emphasis Type="Italic">sordidum</Emphasis> (Ranunculaceae)

Seeds of Delphinium fissum subsp. sordidum are physiologically dormant at maturity, with underdeveloped embryos; thus they have morphophysiological dormancy (MPD). The aims of this study were to determine the requirements for embryo growth, dormancy break and germination, to characterise the type of seed dormancy and to evaluate the effects of light, seed age, pollination mechanism, and inter-annual and inter-population variability on germinative ability. After 3 months of incubation at 5°C (cold stratification) in darkness conditions, the mean embryo length increased from 5.6 to 2.07 mm, with 76% of seeds germinating. Conversely, embryos of seeds incubated during 3 months at 20/7 or 28/14°C hardly grew and no germination was recorded. Since cold stratification was the only requirement for the loss of MPD, and both dry storage in laboratory conditions and warm stratification prior to cold stratification shortened the cold stratification period required for germination, it could be concluded that D. fissum subsp. sordidum seeds have intermediate complex MPD. Cold stratification and incubation in darkness conditions promoted higher germination percentages than those in light. In addition, germinative ability increased with seed age up to 8 months (reaching 96% at 5°C in darkness), showed a pronounced inter-annual and inter-population variability, as well as a significant decrease in seeds coming from pollination by geitonogamy. High temperatures (25/10 or 28/14°C) induced seeds to secondary dormancy, so seedling emergence in the greenhouse was restricted to February–March. The requirements for dormancy break and germination reflect an adaptation to trigger germination in late winter. This study is the first one to document a gradual increase in germination percentage with seed age for plant species with intermediate complex MPD.     

Efficient decomposition of shrimp shell waste using <Emphasis Type="Italic">Bacillus cereus</Emphasis> and <Emphasis Type="Italic">Exiguobacterium acetylicum</Emphasis>

Two bacterial cultures were isolated and tested for degradation of shrimp shell waste. According to morphological examination, physiological tests, and applied molecular techniques, isolates were identified as Bacillus cereus and Exiguobacterium acetylicum. Both strains were cultivated separately in flasks with 100 mL of shrimp shell waste broth (3% of washed, dried and ground shrimp shell waste in tap water, pH 7.0) at 37°C. At determined periods of time, deproteinization and demineralization of residuals were measured. Fermentation of 3% shell waste with B. cereus indicated 97.1% deproteinization and 95% demineralization. For E. acetylicum, the level of deproteinization and demineralization was 92.8 and 92%, respectively. Protein content was reduced from 18.7 to 5.3% with B. cereus and to 7.3% with E. acetylicum. No additional supplements were used during the fermentation of shell waste. B. cereus strain showed higher efficacy in decomposition of shell waste and was used for large-scale fermentation in 12 L of 10% shrimp shell waste broth. Incubation of bacteria with shell waste during 14 days at 37°C resulted in 78.6% deproteinization and 73% demineralization. High activity of isolated cultures in decomposition of shrimp shell waste suggests broad potential for application of these bacteria in environmentally friendly approaches to chitin extraction from chitin-rich wastes.     

Dormancy release and seed ageing in the endangered species <Emphasis Type="Italic">Silene diclinis</Emphasis>

The influence of seed testa color, temperature and seed water content on dormancy release and seed viability loss in the endangered, endemic species Silene diclinis (Lag.) M. Laínz was evaluated. Dormant heterogeneous seeds (black, red and grey colored) were exposed to three different temperatures (5, 20, and 35°C) and two relative humidities (33 and 60%) in order to assay their dormancy release. Longevity behavior was studied for the three colored seeds, storing samples at nine different combinations of temperature (5, 20 and 35°C) and relative humidities (33, 60 and 90%). According to our findings, seed heteromorphism was not related to neither break of dormancy nor seed storage behavior. Silene diclinis seeds present dormancy after collection, and need an after-ripening period to germinate. Temperature and relative humidity are positively correlated with dormancy release and seed ageing. Therefore, both factors must be carefully controlled during seed manipulation in the laboratory for long term seed conservation purposes. When seeds are stored immediately after collection (dormant), if the temperature of storage is above the base temperature for dormancy release found in this work (between 2.7 and 1.6°C), seeds may eventually overcome dormancy. On the other hand if seeds are stored after an after-ripening period, storage at low temperature does not induce secondary dormancy.     

Comparative <Emphasis Type="Italic">in vitro</Emphasis> germination ecology of <Emphasis Type="Italic">Calopogon tuberosus</Emphasis> var. <Emphasis Type="Italic">tuberosus</Emphasis> (Orchidaceae) across its geographic range

Seed responses to temperature are often essential to the study of germination ecology, but the ecological role of temperature in orchid seed germination remains uncertain. The response of orchid seeds to cold stratification have been studied, but the exact physiological role remains unclear. No studies exist that compare the effects of either cold stratification or temperature on germination among distant populations of the same species. In two separate experiments, the role of temperature (25, 22/11, 27/15, 29/19, 33/24°C) and chilling at 10°C on in vitro seed germination were investigated using distant populations of Calopogon tuberosus var. tuberosus. Cooler temperatures promoted germination of Michigan seeds; warmer temperatures promoted germination of South Carolina and north central Florida seeds. South Florida seed germination was highest under both warm and cool temperatures. More advanced seedling development generally occurred at higher temperatures with the exception of south Florida seedlings, in which the warmest temperature suppressed development. Fluctuating diurnal temperatures were more beneficial for germination compared to constant temperatures. Cold stratification had a positive effect on germination among all populations, but South Carolina seeds required the longest chilling treatments to obtain maximum germination. Results from the cold stratification experiment indicate that a physiological dormancy is present, but the degree of dormancy varies across the species range. The variable responses among populations may indicate ecotypic differentiation.     

Seed size and seed germination in the Mediterranean fire-prone shrub <Emphasis Type="Italic">Cistus </Emphasis><Emphasis Type="Italic">ladanifer</Emphasis>

The germination response of different sized seeds from individuals of a Mediterranean fire-prone shrub (Cistus ladanifer) was investigated in relation to pre-germination heating. A control (no heating), a low temperature during a short exposure time (50°C during 5 min), a high temperature during a short exposure time (100°C during 5 min) and a high temperature during a long exposure time (100°C during 15 min) were applied to seeds from different individual plants with different mean seed weight. These pre-germination treatments resemble natural germination scenarios for the studied species, absence of fire, low intensity pasture fire, typical Mediterranean shrub fire, and severe fire with high fuel load. Mean seed weight only showed a marginally significant positive correlation with the proportion of germinated seeds whatever the pre-germination treatment. These results suggest that seed dormancy is unrelated to seed size and that under the experimental conditions used in this study, the effect of seed size on seed germination is low. Nevertheless, larger seeds could be favoured in natural conditions, especially under the high competition scenario which arise after wildfires. Control seeds showed a negative correlation between seed size and germination velocity suggesting that lighter seeds could take advantage from early germination in recruitment events in the absence of wildfires. Nevertheless, even the lower pre-germination heating treatment turns this correlation in not significant, suggesting a strong selection pressure (unrelated to seed size) for early germination after fire events. In our study, different sized seeds of C. ladanifer seem to perform better under different germination scenarios suggesting that seed size variation could be maintained by the alternation of recruitments without wildfires and recruitments after wildfire events.     

The germination characteristics of <Emphasis Type="Italic">Scrophularia marilandica</Emphasis> L. (Scrophulariaceae) seeds

Investigations on seeds of Scrophularia marilandica L. were undertaken to determine their germination requirements. Seeds were collected from three naturally occurring sites and one greenhouse-grown population in London, Ontario in September and October of 1997. Some were set to germinate immediately after collection; others were stored in or on soil outside and/or under controlled laboratory conditions before testing. Germination was assessed under two light/temperature regimes (35°C 14 h light, 20°C 10 h dark and 25°C 14 h light, 10°C 10 h dark), in continuous darkness, and in the presence of two germination-promoting chemicals (GA₃ and KNO₃). Fresh seeds germinated best at 35/20°C, while stored seeds germinated best at 25/10°C. No differences in percent germination were found among three seed-maturity stages. All chemical treatments, except 0.01 M KNO_3, increased percent germination. Significant differences were found both among and within sites for most chemical treatments, but exposure to 3 × 10⁻⁴ M GA₃ caused almost every seed to germinate. When compared to the control, both the gibberellic acid and the soil-storage treatments contributed to faster germination. Exposure of seeds to naturally prevailing conditions on the soil surface followed by testing under the 25/10°C regime produced the highest percent germination. No seeds germinated in the dark. In summary, seeds of S. marilandica exhibit physiological dormancy, which can be alleviated by exposure to light, after-ripening and/or cold stratification. It is probable that the differences in germination response among sites can be attributed to differences in environmental conditions during seed production. These experiments indicate that the seeds of S. marilandica must be buried shortly after dispersal in order to form a persistent seed bank.     

Effect of temperature on the life history of <Emphasis Type="Italic">Eretmocerus</Emphasis> sp. nr. <Emphasis Type="Italic">furuhashii</Emphasis>, a parasitoid of <Emphasis Type="Italic">Bemisia tabaci</Emphasis>

Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae) is an indigenous parasitoid of Bemisia tabaci (Gennadius)(Hemiptera: Aleyrodidae) from southern China; the effects of constant temperatures on the life history of E. sp. nr. furuhashii were examined in the laboratory. The developmental period ranged from 39.2 days at 20°C to 12.40 days at 32°C. A total of 263.4 degree-days were required to complete development with a lower developmental threshold temperature of 11.1°C. Of the eggs produced, 59.3% completed development at 20°C with completion increasing to 71.5% at 26°C. Adult female longevity was 10.8 days at 20°C and 5.2 days at 32°C while the mean daily offspring reproduced per female was highest at 29°C with 5.9 offspring. Adult oviposition peaked three days after emergence at 26, 29 and 32°C, and four days post-emergence at 20°C and 23°C. The total numbers of offspring produced per female ranged from 25.7 individuals at 32°C to 41.1 individuals at 20°C. The sex ratio had a female bias and ranged from 0.72 at 17°C to 0.51 at 35°C. The intrinsic rate of increase was 0.1727 at 29°C followed with 0.1606 at 32°C. Results indicated that E. sp. nr. furuhashii reaches its maximum biological potential at temperatures ranging from 26°C to 32°C.     

Physical and physiological dormancy in black henbane (<Emphasis Type="Italic">Hyoscyamus niger</Emphasis> L.) seeds

Aim of this study was to investigate the nature of dormancy in black henbane (Hyoscyamus niger) seeds which have low germination rate under normal laboratory conditions. To do this, before placing the seeds in Petri dishes, they were soaked in 5,10 and 15 mg/L GA; 1,2 and 3% H₂SO₄, 15 mg/L GA + 1% H₂SO₄, 0.01 M KNO₃ solutions, tap water, 40, 50 and 60°C hot water for 30 min. The study was performed under both continuous illumination and darkness in growth chambers to evaluate the effect of light on germination rate. The results showed that H₂SO₄ and GA treatments were the most important factors affecting seed germination and their germination enhancing effects were more evident in darkness. The results also suggested that black henbane seeds exhibit double dormancy involving a hard seed coat and a partially dormant embryo and have a partial dark requirement to germinate.     

Sporulation and regeneration efficiency of phosphobacteria (<Emphasis Type="Italic">Bacillus megaterium</Emphasis> var <Emphasis Type="Italic">phosphaticum</Emphasis>)

Sporulation in Bacillus megaterium var phosphaticum (PB — 1) was induced using modified nutrient media. This modified medium induced sporulation within 36 h. After spore induction the spores were kept under refrigerated (5°C) and room temperature (32°C) for five months and survival of spores was studied at 15 days intervals by plating them in nutrient agar medium. It was observed that there was not much variation in the storage temperature (5°C & 32°C). The spore cells of Bacillus megaterium var phosphaticum (PB — 1) were observed up to five months of storage under refrigerated (5°C) and room temperature (32°C). Regeneration of spore cells into vegetative cells was studied in tap water, rice gruel, nutrient broth, sterile lignite and sterile water at different concentrations of spore inoculum. The multiplication of sporulated Bacillus megaterium var phosphaticum culture was fast and reached its maximum (29.5 × 10⁸ cfu ml⁻¹) in nutrient broth containing 5 per cent inoculum level.     

Germination ecology of <Emphasis Type="Italic">Scorpiurus subvillosus</Emphasis> L. seeds: the role of temperature and storage time

Scorpiurus subvillosus L., wide spread in pastures of Mediterranean basin, is disappearing in the native pastures of the Hyblean plateau (Sicily, southern Italy), because of overgrazing and intensive management techniques. Moreover, it exhibits seed coat dormancy, which delays and reduces germination preventing its diffusion. This paper represents a first attempt in order to investigate changing in germination determined by storage time and temperature on seeds of two populations of S. subvillosus. Germination of S.␣subvillosus seeds was tested in relation to four storage time (30, 130, 200 and 360 days after harvest (DAH)), eight constant temperatures (5, 10, 15, 20, 25, 30, 35 and 40°C) and two populations of different provenience (30 and 600 m above mean sea level). The experiments were conducted either on scarified and unscarified seeds. In S. subvillosus the failure of germination under favourable conditions must be attributed␣only to seed coat, since seed scarification enhanced germination percentage with values up to 100% at almost all tested temperatures. In both treatments, but with a grater incidence in unscarified, seed germination increased gradually as temperature raised, peaking at 20–25°C, then declined with further increases of temperatures. At 40°C no germination occurred. Storage time induced a softening effect, which is somewhat limited by the natural ageing of seeds occurring from about 6 months after harvest.     

Releasing primary dormancy in <Emphasis Type="Italic">Avena fatua</Emphasis> L. caryopses by smoke-derived butenolide

The effect of smoke and smoke-derived butenolide in releasing dormancy of caryopses (referred to as seeds) of the economically important weed Avena fatua L. was studied. Seeds of A. fatua are dormant after harvest. Both smoke-water and butenolide, applied continuously, removed dormancy in darkness at 15, 20 and 25°C and slightly at 30°C. Butenolide was very active at a concentration of 10⁻⁸ M. Butenolide at 10⁻⁸ M was also able to remove dormancy at 20°C when applied for 12 or 24 h at 4°C or for 3 to 24 h at 20°C. Sensitivity to butenolide decreased with longer preincubation times in water. This compound was less effective in releasing dormancy in the light than in darkness. Dormancy release by butenolide involves induction of cell-cycle activity just before coleorhiza protrusion. Stimulatory effects of smoke-water and butenolide were also observed in respect of seedling growth and vigor.     

Influence of Temperature on Virulence of Fungal Isolates of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> and <Emphasis Type="Italic">Beauveria bassiana</Emphasis> to the Two-Spotted Spider Mite <Emphasis Type="Italic">Tetranychus urticae</Emphasis>

Twenty-three isolates of Metarhizium anisopliae (Metschnikoff) Sokorin and three isolates of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales: Clavicipitaceae) were assessed for their virulence against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Based on the screening results, nine isolates of M. anisopliae and two isolates of B. bassiana were tested for their virulence against young adult (1- to 2-day-old) female T. urticae at constant temperatures of 20, 25, 30 and 35°C. At all temperatures tested, all the fungal isolates were pathogenic to T. urticae but mortality varied with isolates and temperatures. Fungal isolates were more virulent at 25, 30 and 35°C than at 20°C. The lethal time to 50% mortality (LT₅₀) and lethal time to 90% mortality (LT₉₀) values decreased with increased temperature. There were no significant differences in virulence between fungal isolates at 30 and 35°C; however, significant differences were observed at 20 and 25°C.     

Effect of Temperature on Development and Fecundity of the Predaceous Plant Bug <Emphasis Type="Italic">Deraeocoris brevis</Emphasis> Reared on <Emphasis Type="Italic">Ephestia kuehniella</Emphasis> Eggs

Temperature-dependent development and oviposition component models were developed for Deraeocoris brevis (Uhler) (Hemiptera: Miridae). Egg development times decreased with increasing temperature and ranged from 35.8 d at 15 °C to 6.7 d at 32 °C. Total development times of nymphs reared on frozen Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs decreased from an estimated 55.6 d at 15 °C to 9.2 d at 32 °C and 10.0 d at 34.6 °C. By fitting linear models to the data the lower developmental threshold temperatures for eggs, small nymphs (1st to 3rd instar), large nymphs (4th to 5th instar), and all nymphs combined were calculated as 10.5, 12.5, 11.8, and 11.9 °C, respectively. The thermal constants were 144.1, 90.3, 95.0, and 190.8 degree-days for each of the above stages. The non-linear model was based on a Gaussian equation, which fit the relationship between development rate and temperature well for all stages. The Weibull function provided a good fit for the distribution of development times of each stage. Adult longevity decreased with increasing temperature and ranged from 52.9 d at 21.7 to 16.8 d at 32.0 °C. D. brevis had a maximum fecundity of 471 eggs per female at 24 °C, which declined to 191 eggs per female at 32 °C. Also, three temperature-dependent components for an oviposition model of D. brevis were developed including models for total fecundity, age-specific cumulative oviposition rate, and age-specific survival rate.     

Photoregulation of morphological structure and its physiological relevance in the cyanobacterium <Emphasis Type="Italic">Arthrospira</Emphasis> (<Emphasis Type="Italic">Spirulina</Emphasis>) <Emphasis Type="Italic">platensis</Emphasis>

The spiral structure of the cyanobacterium Arthrospira (Spirulina) platensis (Nordst.) Gomont was previously found to be altered by solar ultraviolet radiation (UVR, 280–400 nm). However, how photosynthetic active radiation (PAR, 400–700 nm) and UVR interact in regulating this morphological change remains unknown. Here, we show that the spiral structure of A. platensis (D-0083) was compressed under PAR alone at 30°C, but that at 20°C, the spirals compressed only when exposed to PAR with added UVR, and that UVR alone (the PAR was filtered out) did not tighten the spiral structure, although its presence accelerated morphological regulation by PAR. Their helix pitch decreased linearly as the cells received increased PAR doses, and was reversible when they were transferred back to low PAR levels. SDS-PAGE analysis showed that a 52.0 kDa periplasmic protein was more abundant in tighter filaments, which may have been responsible for the spiral compression. This spiral change together with the increased abundance of the protein made the cells more resistant to high PAR as well as UVR, resulting in a higher photochemical yield.