Serglycin expression during monocytic differentiation of U937-1 cells

Serglycin is the major proteoglycan in most hematopoietic cells, including monocytes and macrophages. The monoblastic cell line U937-1 was used to study the expression of serglycin during proliferation and differentiation. In unstimulated proliferating U937-1 cells serglycin mRNA is nonconstitutively expressed. The level of serglycin mRNA was found to correlate with the synthesis of chondroitin sulfate proteoglycan (CSPG). The U937-1 cells were induced to differentiate into different types of macrophage-like cells by exposing the cells to PMA, RA, or VitD3. These inducers of differentiation affected the expression of serglycin mRNA in three different ways. The initial upregulation seen in the normally proliferating cells was not observed in PMA treated cells. In contrast, RA increased the initial upregulation, giving a reproducible six times increase in serglycin mRNA level from 4 to 24 h of incubation, compared to a four times increase in the control cells. VitD3 had no effect on the expression of serglycin mRNA. The incorporation of (35S)sulfate into CSPG decreased approximately 50% in all three differentiated cell types. Further, the (35S)CSPGs expressed were of larger size in PMA treated cells than controls, but smaller after RA treatment. This was due to the expression of CSPGs, with CS-chains of 25 and 5 kDa in PMA and RA treated cells, respectively, compared to 11 kDa in the controls. VitD3 had no significant effect on the size of CSPG produced. PMA treated cells secreted 75% of the (35S)PGs expressed, but the major portion was retained in cells treated with VitD3 or RA. The differences seen in serglycin mRNA levels, the macromolecular properties of serglycin and in the PG secretion patterns, suggest that serglycin may have different functions in different types of macrophages.      

C(4) Pathway Photosynthesis at Low Temperature in Cold-tolerant Atriplex Species

Two species of Atriplex were grown under low temperature (8 C day/6 C night) and high temperature (28 C day/20 C night) regimes. The photosynthetic capacity of these plants was studied as a function of temperature in a leaf gas exchange cuvette. Both species showed substantial photosynthetic capacity between 4 and 10 C and this was not enhanced by growth at low temperatures but rather, was somewhat greater in plants grown at higher temperature. Photosynthetic capacity of low temperature-grown plants at high temperature was greater in Atriplex confertifolia (Torr. and Frem.) S. Watts., a native of cool deserts, than in Atriplex vesicaria (Hew. ex. Benth.) from warmer desert areas. Leaves of both species were also subjected to ¹⁴CO₂ pulse-chase and steady-state feeding experiments under controlled temperature conditions. These experiments revealed that the kinetics of carbon assimilation through the intermediates of the C₄ pathway is not substantially disrupted at low temperature in either species. There was, however, a substantial interchange of label between aspartate and malate at low temperature which was not evident at high temperature. There was also an increase in the pool sizes of the C₄ acids involved in photosynthesis of A. confertifolia. Speculation as to the explanation of these changes and their possible significance in promoting low temperature C₄ photosynthesis in these plants is presented.     

<Emphasis Type="Italic">α</Emphasis>-Amylase inhibitor-1 gene from <Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> expressed in <Emphasis Type="Italic">Coffea arabica</Emphasis>plants inhibits α-amylases from the coffee berry borer pest

Background  

Coffee is an important crop and is crucial to the economy of many developing countries, generating around US70 billion per year. There are 115 species in the < i > Coffea < /i > genus, but only two, < i > C. arabica < /i > and < i > C. canephora < /i > , are commercially cultivated. Coffee plants are attacked by many pathogens and insect-pests, which affect not only the production of coffee but also its grain quality, reducing the commercial value of the product. The main insect-pest, the coffee berry borer ( < i > Hypotheneumus hampei < /i > ), is responsible for worldwide annual losses of around US70 billion per year. There are 115 species in the Coffea genus, but only two, C. arabica and C. canephora, are commercially cultivated. Coffee plants are attacked by many pathogens and insect-pests, which affect not only the production of coffee but also its grain quality, reducing the commercial value of the product. The main insect-pest, the coffee berry borer (Hypotheneumus hampei), is responsible for worldwide annual losses of around US500 million. The coffee berry borer exclusively damages the coffee berries, and it is mainly controlled by organochlorine insecticides that are both toxic and carcinogenic. Unfortunately, natural resistance in the genus Coffea to H. hampei has not been documented. To overcome these problems, biotechnological strategies can be used to introduce an α-amylase inhibitor gene (α-AI1), which confers resistance against the coffee berry borer insect-pest, into C. arabica plants.     

Isolation and Characterization of Protein Bodies in Lupinus angustifolius

Using Nycodenz, a novel density gradient medium, we isolated intact protein bodies from developing seeds of Lupinus angustifolius L. (cultivar Unicrop) and achieved excellent separation from the endoplasmic reticulum, mitochondria, and other organelles. The distribution of the storage protein conglutin-β was taken as evidence that up to 96% of the protein bodies remained intact on the gradients and banded at 1.25 grams per milliliter. The protein bodies also contained the three other abundant proteins present in L. angustifolius seeds: conglutins-α, -γ, and -δ. Pulse labeling experiments were carried out to determine the site of proteolytic processing of conglutin-α, a legumin-like 11Svedberg unit storage protein. Cotyledons aged either 33 or 40 days after flowering were pulsed with [³H]leucine. Protein bodies obtained from the cotyledons aged 33 days after flowering contained only the labeled precursors of conglutin-α with molecular weights 85,000, 72,000, and 64,000, even after a 4 hour chase of the radioactivity. Protein bodies obtained from the cotyledons aged 40 days after flowering contained the same radioactive precursors if the tissue had been pulsed for 2 hours, and the processing products of these precursors when the tissue had been chased for 4 hours. These studies confirm that the subcellular location of proteolytic cleavage of this legumin-like protein is the protein body, that this activity is detected only in protein bodies from lupin seeds aged between 33 and 40 days of seed development after flowering and that protein bodies from seeds younger than this contain only unprocessed conglutin-α.     

(Trans)esterification of mannose catalyzed by lipase B from Candida antarctica in an improved reaction medium using co-solvents and molecular sieve

Four co-solvents (dimethylformamide [DMF], formamide, dimethyl sulfoxide [DMSO], and pyridine) were tested with tert-butanol (tBut) to optimize the initial rate (v?) and yield of mannosyl myristate synthesis by esterification catalyzed by immobilized lipase B from Candida antarctica. Ten percent by volume of DMSO resulted in the best improvement of v? and 48-hr yield (respectively 115% and 13% relative gain compared to pure tBut). Use of molecular sieve (5% w/v) enhances the 48-hr yield (55% in tBut/DMSO [9:1, v/v]). Transesterification in tBut/DMSO (9:1, v/v) with vinyl myristate leads to further improvement of v? and 48-hr yield: a relative gain of 85% and 65%, respectively, without sieve and 25% and 10%, respectively, with sieve, compared to esterification. No difference in v? and 48-hr yield is observed when transesterification is carried out with or without sieve.     

Carbon assimilation patterns and growth of the introduced CAM plant Opuntia inermis in Eastern Australia

Summary The daily course of CO₂ and H₂O exchange in cladodes of Opuntia inermis was studied at four sites in Eastern Australia. On most occasions cladode water contents were high and nocturnal stomatal opening resulted in substantial uptake of CO₂ and synthesis of about 130 equiv cm^-2 of malic acid during the night. Under water stress nocturnal stomatal opening was confined to the latter part of the night and acid synthesis was reduced to about 40 equiv cm^-2. Night temperature had little effect on acid synthesis, which responded primarily to rainfall and changed from the stressed condition within 2–3 days in irrigation experiments. On many occasions following summer rainfall stomata opened for 4 h in the late afternoon permitting net CO₂ fixation which may contribute about 25% of the total carbon assimilated. This CO₂ fixation was insufficient to have a marked impact on the ₁₃C value of the Opuntia cladodes. CO₂ fixation in the light occurred in conjunction with maximum dark CO₂ fixation under mesic conditions. Dark CO₂ fixation rates were 3 to 5 times greater than those recorded in desert cacti under favorable conditions. Relative growth rates calculated on the basic of CO₂ exchange correspond to measured relative growth rates of 0.05 g g^-1 dry wt day^-1 which prevailed for 60–90 days in summer. The capacity for very active CO₂ fixation in the dark and light following summer rainfall and the capacity to persist at low levels of metabolic activity through summer drought are discussed in relation to the success of this introduced species in this habitat.     

Chilling injury and recovery in detached and attached leaves measured by chlorophyll fluorescence

Smillie, R. M., Nott, R., Hetherington, S. E. and Öyustt, G. 1987. Chilling injury and recovery in detached and attached leaves measured by chlorophyll fluorescence Chilling injury was compared in detached and attached leaves chilled at 0 or 0.5°C by measuring the decrease in induced chlorophyll fluorescence in vivo. The fluorescence parameter measured was F_R, the maximal rate of rise of induced chlorophyll fluorescence emission after irradiating dark-adapted leaves. The plants used were bean, Phaseolus vulgaris L. cv. Pioneer, and maize, Zea mays L. cvs hybrid GH 390 and Northern Belle. Leaves were detached and placed on wet paper and covered with thin polyethylene film to prevent water loss during chilling. Leaves left attached on plants were treated similarly. When chilled in this way at 100% relative humidity, the chilling-induced decrease in F_R was the same in detached and attached leaves. For the attached leaves, the same result was obtained whether just a single leaf was chilled or the whole plant. Expression of chilling injury was greatest in fully turgid leaves and comparisons can be invalid unless the water status of the detached and attached leaves are the same. Problems arising from diurnal fluctuations in water potential of plants grown in a glasshouse were circumvented by placing leaves on the wet filter paper under polyethylene film prior to chilling, which allowed high water potentials to be regained, or mist sprays in the glasshouse were employed. Determinations of the time course for changes in F_R of maize (cv. Northern Belle) during chilling at 0°C showed that F_R decreased exponentially, at the same rate (time to 50% decrease in F_R was 9.3 h) in detached and attached leaves. Chilling injury was largely reversible for the first 20 h of chilling stress as both detached and attached leaves recovered their pre-chilling values of F_R after a further 20 h at 20°C in darkness. Leaves chilled for 48 h showed partial recovery, while those chilled for 72 h did not recover. Recovery was impeded by light. Inability to recover from chilling as indicated by measurements of F_R was paralleled by the incidence of visible symptoms of injury. It is concluded that detached and attached leaves behave similarly during chilling and short-term recovery, provided a similarity in treatments is rigorously maintained.     

Influences of the El Niño/Southern Oscillation and the North Atlantic Oscillation on avian productivity in forests of the Pacific Northwest of North America

To model the effects of global climate phenomena on avian population dynamics, we must identify and quantify the spatial and temporal relationships between climate, weather and bird populations. Previous studies show that in Europe, the North Atlantic Oscillation (NAO) influences winter and spring weather that in turn affects resident and migratory landbird species. Similarly, in North America, the El Niño/Southern Oscillation (ENSO) of the Pacific Ocean reportedly drives weather patterns that affect prey availability and population dynamics of landbird species which winter in the Caribbean. Here we show that ENSO‐ and NAO‐induced seasonal weather conditions differentially affect neotropical‐ and temperate‐wintering landbird species that breed in Pacific North‐west forests of North America. For neotropical species wintering in western Mexico, El Niño conditions correlate with cooler, wetter conditions prior to spring migration, and with high reproductive success the following summer. For temperate wintering species, springtime NAO indices correlate strongly with levels of forest defoliation by the larvae of two moth species and also with annual reproductive success, especially among species known to prey upon those larvae. Generalized linear models incorporating NAO indices and ENSO precipitation indices explain 50–90% of the annual variation in productivity reported for 10 landbird species. These results represent an important step towards spatially explicit modelling of avian population dynamics at regional scales.