Heat shock triggers rapid protein phosphorylation in soybean seedings

Heat shock arrests the synthesis of many cellular proteins and simultaneously initiates expression of a unique set of proteins, termed heat shock proteins. We have found that heat shock rapidly triggers phosphorylation of a set of proteins in soybean seedlings. Although the kinetics of phosphorylation and the heat shock response are similar, the major identified phosphorylation products do not comigrate with heat shock proteins on polyacrylamide gels. Cadmium, which is known to induce the heat shock response, stimulates phosphorylation of the same set of proteins. The rapidity of phosphorylation suggests that it may play a pivotal role in sensing and transducing elevated temperature stress in plants.     

Preferences for sex of children: a multivariate analysis

Data from the 1973-74 Growth of Alberta Family Study were used to determine whether women who express a preference for sons versus daughters differ from each other in terms of selected characteristics. 67% of the 599 women surveyed indicated a preference for at least 1 child of each sex. However, the majority of those who wanted 3 children desired 2 sons and 1 daughter, indicating a slight son preference. Discriminant function analysis indicated the pull toward son preference was greater the higher the woman's education, the more sisters the wife has, and the higher the current family size and number of additional children expected. While the number of wife's sisters makes the greatest contribution to daughter preference among adolescent mothers, birth place (Canada) was most important among older women. Finally, it was shown that acceptance of traditional female roles was a significant discriminator among women with a strong sex preference and those with no sex preference at all. These findings suggest that sex preference may become an important factor in fertility decisions as family size continues to decrease. If sex predetermination were to become possible, an imbalance in the sex ratio is a likely result.     

Folate (pteroylglutamate) uptake in human red blood cells, erythroid precursors and KB cells at high extracellular folate concentrations. Evidence against a role for specific folate-binding and transport proteins.

Membrane-associated folate (pteroylglutamate, PteGlu)-binding proteins (FBPs) play an important role as PteGlu-transport proteins in malignant and normal human cells. Since high extracellular folate (PteGlu) concentrations (EFC) profoundly influenced uptake and toxicity of the anti-PteGlu methotrexate in malignant KB cells, we studied human cells to determine additional mechanisms for PteGlu uptake when the EFC was varied. At low EFC (less than 10 nM), the predominant mechanism for folate uptake in mature erythrocytes was through binding to externally oriented FBPs which were quantitatively insignificant (4-6 orders of magnitude lower) and of no apparent physiological relevance when compared with KB cells. However, the predominant mechanism of PteGlu accumulation at high EFC [10-250 nM] in intact erythrocytes and sealed right-side-out (RSO) ghosts was not FBP-mediated and non-specific. This conclusion was based on the findings that radiolabelled PteGlu uptake: (i) continued even in the presence of a 1000-fold excess of unlabelled PteGlu and was linear and not saturable up to 250 nM; (ii) was two-fold higher at pH 4.5 than 7.5; (iii) was less than 2-fold increased at 37 degrees C compared with 4 degrees C; and (iv) was unaffected after trypsin-mediated proteolysis of greater than 75% FBPs. The [3H]PteGlu and 125I-PteGlu (histamine derivative) accumulated intracellularly through the non-specific PteGlu-uptake mechanism was unaltered biochemically and in a soluble compartment. Raising the EFC 500-fold higher than controls during erythropoiesis in vitro resulted in reversal of the expected anti-(placental folate-receptor)-antiserum-induced megaloblastic changes in orthochromatic normoblasts derived from burst-forming unit-erythroid colonies. Furthermore, at EFC greater than 0.1 microM, KB-cell accumulation of [3H]PteGlu was also predominantly through a mechanism that did not involve specific FBPs. Thus, at high EFC, a major component of PteGlu transport in human cells is not mediated through FBPs and is likely to be a passive diffusion process.     

Clostridium pasteurianum glutamine synthetase mechanism. Evidence for active site tyrosine residues

Preliminary chemical modification studies indicated the presence of tyrosine, carboxyl, arginine, histidine and the absence of serine and sulfhydryl residues at or near the active site of Clostridium pasteurianum glutamine synthetase. The conditions for tyrosine modification with tetranitromethane were optimized. The inactivation kinetics follow pseudo-first-order kinetics with respect to enzyme and second order with respect to modifier per active site. There was no inactivation at pH 6.5 suggesting the absence of thiol oxidation. The synthetase and transferase reactions followed the same pattern of inactivation on enzyme modification and both were equally protected by glutamate plus ATP. Thus tyrosine residues are present at the active site of the enzyme and are essential for both transferase and synthetase activities.     

Development and validation of co-dominant gene based markers for <Emphasis Type="Italic">Pi9</Emphasis>, a gene governing broad-spectrum resistance against blast disease in rice

Rice production and grain quality are severely affected by blast disease caused by the ascomycetous fungus Magnaporthe oryzae. Incorporation of genes that confer broad-spectrum resistance to blast has been a priority area in rice breeding programs. The blast resistance gene Pi9 sourced from Oryza minuta has shown broad spectrum and durable resistance to blast world-wide. In the present study co-dominant gene-based markers were developed for the precise marker-assisted tracking of Pi9 in breeding programs. The developed markers were validated across a diverse set of cultivars including basmati, indica and japonica varieties. Two markers, Pi9STS-1 and Pi9STS-2, effectively differentiated Pi9 donors from all the indicas and commercial basmati varieties tested. However, these markers were monomorphic between Pi-9 donors (IRBL9-W and Pusa 1637) and japonica type varieties. An additional gene-derived CAPS marker Pi91F_ 2R was developed to differentiate Pi9 donors from japonicas and traditional basmati lines. The co-dominant markers developed in the present study will be of immense utility to rice breeders for precise and speedy incorporation of Pi-9 into susceptible rice varieties through marker-assisted selection.     

Production of extracellular hydrolase enzymes by fungi from King George Island

Fungi are known to produce a range of extracellular enzymes and other secondary metabolites. Investment in extracellular enzyme production may be an important element of the survival strategy of these fungi in maritime Antarctic soils. This study focuses on fungi that were isolated from ornithogenic, undisturbed and human-impacted soils collected from the Fildes Peninsula, King George Island, Antarctica, during the austral summer in February 2007. We (1) describe fungal diversity based on molecular approaches, (2) describe the thermal characteristics of the fungal isolates, and (3) screen extracellular hydrolase enzyme production (amylase and cellulase) by the isolates. Soil samples were cultured using the Warcup soil plating technique and incubated at 4 and 25 °C to allow basic thermal classification. In total, 101 isolates were obtained. All the isolates were screened at culture temperatures of 4 and 25 °C in order to detect activity of extracellular hydrolase enzymes. At 25 °C, ornithogenic penguin rookery soils recorded the lowest diversity of fungi, with little difference in diversity apparent between the other soils examined. At 4 °C, an undisturbed site recorded the lowest and a human-impacted site the highest diversity of fungi. The majority of the fungi identified in this study were in the mesophilic thermal class. Six strains possessed significant activity for amylase and 13 for cellulase at 25 °C. At 4 °C, four strains showed significant amylase and 22 significant cellulase activity. The data presented increase our understanding of microbial responses to environmental temperature.     

Kinetics of maize leaf elongation IV. Effects of (+)- and (-)-abscisic acid

Abscisic acid (ABA) is involved in many of the responses of plants to environmental stress. This study focuses on the inhibitory effect of ABA on leaf expansion. In addition, the effects of (+)-ABA, the natural form of ABA, were compared to the effects of (-)-ABA. Leaf elongation rates (LER) were measured for the 3rd leaf of maize plants. ABA concentrations were measured by RIA for total ABA and an ELISA specific for (+)-ABA. ABA was added to the hydroponic solution and changes in the LER were measured over time. ABA could inhibit LER within 30 min ad reached steady-state LER within 4 h. Internal ABA concentrations in the growing zone of the leaf also reached steady-state concentrations after 4 h. This effect of ABA was reversible, because LER was fully restored upon removal of externally applied ABA, and internal concentrations of ABA in the growing zone returned to normal levels, whereas ABA concentrations remained elevated in mature tissue. Thus, steady-state LER was highly correlated with the steady-state internal ABA concentration of the growing zone. ABA inhibited leaf expansion by increasing the apparent cell wall yield threshold; no other growth parameters were affected. The (-)-enantiomer of ABA had much less effect on LER than (+)-ABA when compared upon an external concentration basis. Internal ABA concentrations rationalized the response, showing that (-)-ABA accumulation was very low, most likely due to low uptake rates. From this analysis, it was determined that LER was equally sensitive to internal concentrations of (+)- or (-)-ABA.     

In vitro propagation ofHolostemma annulare (Roxb.) K. Schum., a rare medicinal plant

Summary A rapid micropropagation system was established forHolostemma annulare (Roxb.) K. Schum., (H. ada-kodien R. Br. ex Schult; Asclepiadaceae), a rare medicinal plant. Shoot tips (0.5–0.8 cm) and terminal and basal nodes (1.0–1.5 cm) harvested from actively growing shoots of conventionally raised plants were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of 6-benzyladenine (BA) and α-naphthaleneacetic acid (NAA). Multiple shoot formation (3.8) was observed in 68% of basal nodes cultured on medium with optimum concentration of 4.43 μM BA and 0.54 μM NAA after 8 wk. Terminal nodes were not suitable for inducing multiple shoots. Irrespective of the orientation (vertical/horizontal), all shoot tip explants responded with a single shoot in all the combinations of plant growth regulators tried. Effects of other cytokinins (kinetin and 2-isopentenyladenine) and auxins [indole-3-acetic acid and indole-3-butyric acid (IBA)] to enhance the regeneration potential of basal nodes were analyzed. Shoots were multiplied by subculture of basal nodes and stumps (the original explant tissue free of shoots, but with remnant axillary, meristem and two or three protruding buds) in a reduced concentration of BA (2.21 μM) and NAA (0.27 μM). Liquid medium for multiplication was found to be ineffective due to a high degree of hyperhydricity. To make the multiplication process cost effective, culture bottles with polypropylene, caps were used for multiplication. The best root induction (75%) and survival (80%) was achieved on 0.5 strength MS medium supplemented with 1.48 μM IBA. Field-established plants had uniform growth habit traits in terms of height of plants and number, length, and weight of the tuberous roots.