Salt Tolerance ofEchinochloa crusgalli

Salt tolerance ofEchinochloa crusgalli was studied using gravel culture with root medium electrical conductivity between 3 to 25 dS m^-1. Salinity depressed germination and shoot yield. A 50 % reduction in shoot yield occurred at 15.9 dS m^-1. The plant was able to maintain its tissue water content and K concentration in the tissue water while Na, Ca and Cl increased and Mg decreased with increasing root zone salinity.     

Biological Control of Macrophomina phaseolina Charcoal Rot of Sunflower and Mung Bean

Infection by Macrophonina phaseolina was substantially reduced following treatment of sunflower and mungbean seeds with Trichoderma harzianum, Gliocladium virens, Paecilomyces lilacinus or Streptomyces sp. which gave promising control of charcoal rot disease. Treatment of mungbean seeds with Rhizobium meliloti also gave good disease control.     

Effect of salinity and inoculation on growth,nitrogen fixation and nutrient uptake ofVigna radiata (L.) Wilczek

This study reports the effect of salinity and inoculation on growth, ion uptake and nitrogen fixation byVigna radiata. A soil EC_e level of 7.5 dS m⁻¹ was quite detrimental causing about 60% decline in dry matter and grain yield of mungbean plants whereas a soil EC_e level of 10.0 dS m⁻¹ was almost toxic. In contrast most of the studied strains of Rhizobium were salt tolerant. Nevertheless, nodulation, nitrogen fixation and total nitrogen concentration in the plant was drastically affected at high salt concentration. A noticeable decline in acetylene reduction activity occurred when salinity level increased to 7.5 dS m⁻¹.     

Effect of ammonium on the regulation of nitrate and nitrite transport systems in roots of intact barley (Hordeum vulgare L.) seedlings

The effect of NH ₄ ⁺ on the regulation of NO ₃ ^– and NO ₂ ^– transport systems in roots of intact barley (Hordeum vulgareL.) seedlings grown in NO ₃ ^– or NO ₂ ^– was studied. Ammonium partially inhibited induction of both transport systems. The inhibition was less severe in NO ₂ ^– -fed than in NO ₃ ^– -fed seedlings, presumably due to lower uptake of NH ₄ ⁺ in the presence of NO ₂ ^– . In seedlings pretreated with NH ₄ ⁺ subsequent induction was inhibited only when NH ₄ ⁺ was also present during induction, even though pretreated roots accumulated high levels of NH ₄ ⁺ . This indicates that inhibition may be regulated by NH ₄ ⁺ concentration in the cytoplasm rather than its total accumulation in roots. L-Methionine sulfoximine did not relieve the inhibition by NH ₄ ⁺ , suggesting that inhibition is caused by NH ₄ ⁺ itself rather than by its assimilation product(s). Ammonium inhibited subsequent expression of NO ₃ ^– transport activity similarly in roots grown in 0.1, 1.0, or 10 mM NO ₃ ^– for 24 h (steady-state phase) or 4 d (decline phase), indicating that it has a direct, rather than general feedback effect. Induction of the NO ₃ ^– transport system was about twice as sensitive to NH ₄ ⁺ as compared to the NO ₂ ^– transport system. This may relate to higher turnover rates of membraneassociated NO ₃ ^– -transport proteins.Abbreviations Mes 2(N-morpholino)ethanesulfonic acid - MSO L-methionine sulfoximine     

SYNTHESIS OF LACTOFERRIN AND CASEIN BY EXPLANTS OF BOVINE MAMMARY TISSUE

Synthesis of lactoferrin and casein by the bovine mammary gland was determined in an experimental model where lactation was maintained in one mammary half, while involution was induced in the contralateral half. Culture of explants with prolactin had no consistent effect on synthesis of casein or lactoferrin in tissue from either mammary half. Endotoxin and tumor necrosis factor-α generally decreased synthesis of casein and lactoferrin, suggesting that these inflammatory mediators are not directly responsible for increasing lactoferrin synthesis during mammary inflammation or involution. Synthesis of lactoferrin was increased and casein decreased in the involuting mammary half vs. the lactating half. These results suggest that local factors in the mammary gland play a role in the regulation of lactoferrin synthesis during involution.     

Expanding EMC foldopathies: Topogenesis deficits alter the neural crest

The endoplasmic reticulum (ER) membrane protein complex (EMC) is essential for the insertion of a wide variety of transmembrane proteins into the plasma membrane across cell types. Each EMC is composed of Emc1-7, Emc10, and either Emc8 or Emc9. Recent human genetics studies have implicated variants in EMC genes as the basis for a group of human congenital diseases. The patient phenotypes are varied but appear to affect a subset of tissues more prominently than others. Namely, craniofacial development seems to be commonly affected. We previously developed an array of assays in Xenopus tropicalis to assess the effects of emc1 depletion on the neural crest, craniofacial cartilage, and neuromuscular function. We sought to extend this approach to additional EMC components identified in patients with congenital malformations. Through this approach, we determine that EMC9 and EMC10 are important for neural crest development and the development of craniofacial structures. The phenotypes observed in patients and our Xenopus model phenotypes similar to EMC1 loss of function likely due to a similar mechanism of dysfunction in transmembrane protein topogenesis.     

Aluminum Toxicity: A Case Study on Tobacco (<i>Nicotiana tabacum</i> L.)

Aluminum is an abundant metal in the earth’s crust that turns out to be toxic in acidic environments. Many plants are affected by the presence of aluminum at the whole plant level, at the organ level, and at the cellular level. Tobacco as a cash crop (Nicotiana tabacum L.) is a widely cultivated plant worldwide and is also a good model organism for research. Although there are many articles on Al-phytotoxicity in the literature, reviews on a single species that are economically and scientifically important are limited. In this article, we not only provide the biology associated with tobacco Al-toxicity, but also some essential information regarding the effects of this metal on other plant species (even animals). This review provides information on aluminum localization and uptake process by different staining techniques, as well as the effects of its toxicity at different compartment levels and the physiological consequences derived from them. In addition, molecular studies in recent years have reported specific responses to Al toxicity, such as overexpression of various protective proteins. Besides, this review discusses data on various organelle-based responses, cell death, and other mechanisms, data on tobacco plants and other kingdoms relevant to these studies.     

Effect of pH and calcium on short-term NO3- fluxes in roots of barley seedlings

The effect of pH and Ca2+ on net NO3- uptake, influx, and efflux by intact roots of barley (Hordeum vulgare L.) seedlings was studied. Seedlings were induced with NO3- or NO2-. Net NO3- uptake and efflux, respectively, were determined by following its depletion from, and accumulation in, the external solution. Since roots of both uninduced and NO2(-)-induced seedlings contain little internal NO3- initial net uptake rates are equivalent to influx (M. Aslam, R.L. Travis, R.C. Huffaker [1994] Plant Physiol 106: 1293-1301). NO3-, uptake (influx) by these roots was little affected at acidic pH. In contrast, in NO3(-)-induced roots, which accumulate NO3-, net uptake rates decreased in response to acidic pH. Under these conditions, NO3- efflux was stimulated and was a function of root NO3- concentration. Conversely, at basic pH, NO3- uptake by NO3- and NO2(-)-induced and uninduced roots decreased, apparently because of the inhibition of influx. Calcium had little effect on NO3- uptake (influx) by NO2(-)-induced roots at either pH 3 or 6. However, in NO3(-)-induced roots, lack of Ca2+ at pH 3 significantly decreased net NO3- uptake and stimulated efflux. The results indicate that at acidic pH the decrease in net NO3- uptake is due to the stimulation of efflux, whereas at basic pH, it is due to the inhibition of influx.     

Effect of glucose on the induction of nitrate reductase in corn roots

In Zea mays L., addition of glucose to the induction medium has no effect on the induction of nitrate reductase during the initial 3 hours either in root tips (0-10 mm) or mature root sections (25-35 mm). With longer times, higher levels of enzyme activity are recovered from both root segments when glucose is present in the incubation medium. The induction in root tips is saturated by 10 mm NO(3) (-). Higher concentrations of NO(3) (-) are required for saturation in mature root sections. The response to glucose is seen over a wide range of external NO(3) (-) concentrations.Nitrate reductase activity is lost rapidly when nitrate is withdrawn from the induction medium. Additions of glucose do not prevent this loss. Additions of glucose have no effect on total uptake of NO(3) (-) by the root segments but they increase the anaerobic NO(2) (-) production in both root tips and mature root segments. This latter measurement is considered to be an estimate of an active NO(3) (-) pool in the cytoplasm. Thus the results show that glucose alters the distribution of NO(3) (-) within the root sections. This may be an important factor in controlling the in vivo stability of the enzyme or its rate of synthesis.