Structural insights of Mycobacterium GTPase‐Obg and anti‐sigma‐F factor Usfx interaction

An essential protein for bacterial growth, GTPase‐Obg (Obg), is known to play an unknown but crucial role in stress response as its expression increases in Mycobacterium under stress conditions. It is well reported that Obg interacts with anti‐sigma‐F factor Usfx; however, a detailed analysis and structural characterization of their physical interaction remain undone. In view of above‐mentioned points, this study was conceptualized for performing binding analysis and structural characterization of Obg‐Usfx interaction. The binding studies were performed by surface plasmon resonance, while in silico docking analysis was done to identify crucial residues responsible for Obg‐Usfx interaction. Surface plasmon resonance results clearly suggest that N‐terminal and G domains of Obg mainly contribute to Usfx binding. Also, binding constants display strong affinity that was further evident by intermolecular hydrogen bonds and hydrophobic interactions in the predicted complex. Strong interaction between Obg and Usfx supports the view that Obg plays an important role in stress response, essentially required for Mycobacterium survival. As concluded by various studies that Obg is crucial for Mycobacterium survival under stress, this structural information may help us in designing novel and potential inhibitors against resistant Mycobacterium strains.     

Cloning and restriction fragment length polymorphism analysis of a cDNA for swine PIT-1, a gene controlling growth hormone expression*

A partial swine cDNA which encodes the functional domain of PIT-1 was isolated by the polymerse chain reaction (PCR). The swine PIT-1 cDNA clone is 95% identical at the protein level to the rat Pit-1 gene. Thus, Pit-l's known function in control of rat growth hormone and prolactin expression is likely to be conserved in swine. This swine cDNA clone was used to investigate genetic variability at PIT-1 in several American and Chinese breeds. Polymorphic BamIII fragments were found in pure-bred Meishan animals (n= 13), but only monomorphic fragments in five American breeds (n= 36).     

Partitioning of MLX-Family Transcription Factors to Lipid Droplets Regulates Metabolic Gene Expression

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Biological control of bacterial spot disease and plant growth-promoting effects of lactic acid bacteria on pepper

In our previous studies, we observed the biological control effect of lactic acid bacteria strains (LABs) KLF01, KLC02 and KPD03 against different plant pathogenic bacteria in vitro against Ralstonia solanacearum, and strains KLF01 and KLC02 against Pectobacterium carotovorum under greenhouse and field experiments, respectively. In this study, we observed the efficacy of these bacteria against bacterial spot pathogen (Xanthomonas campestris pv. vesicatoria) and their plant growth-promoting activities in pepper (Capsicum annuum L. var. annuum), under greenhouse and field conditions. LABs significantly (P < 0.05) reduced bacterial spot on pepper plants in comparison to untreated plants in both the greenhouse and the field experiments. The plant growth-promoting effect of LABs on pepper varied; some strains had a significant effect on growth promotion (P < 0.05) compared with untreated plants, while some showed no significant effect in the greenhouse and field experiments. Additionally, LABs were able to colonise roots, produce indole-3-acetic acid (IAA), siderophores and solubilise phosphate. These findings indicate that application of LABs could provide a promising alternative for the management of bacterial spot disease in pepper plants and could therefore be used as a healthy plant growth-promoting agent.     

Tradeoff between height and relative growth rate in a dominant grass from the Serengeti ecosystem

We determined the relationship between plant height and whole-plant relative growth rate (g g^-1 day^-1) for ten genotypes of Sporobolus kentrophyllus collected from an intensively grazed site on the Serengeti Plains, Tanzania. Plants were grown for 7 weeks in a greenhouse in Syracuse, N.Y., and harvested weekly. Plants that received simulated bovine urine showed a negative relationship between plant height and growth rate, suggesting a genetic tradeoff between competitive ability if ungrazed (height) and ability to recover from grazing (growth rate). There was no height-growth rate relationship under nitrogen addition rates similar to field mineralization rates. In addition, faster-growing, shorter plants tended to have relatively higher above-ground growth rates than slower-growing, taller plants. These results suggest that natural selection has maintained a gradient of morphologies within this species ranging from short, rapidly growing genotypes adapted to intense grazing conditions to tall, slow-growing, grazer-susceptible genotypes that are superior light competitors in absence of herbivory.     

Leaching requirement conceptual models for reactive salt

Accurate prediction of the leaching requirements (Lr) of crops and striving to attain them is essential for efficient irrigation water use. Solute modeling was extended to develop four Lr conceptual models that do not neglect solute reactions in the root-zone, surface evaporation, and the influence of immobile wetted pore space. The models were based on: (i) the water movement equation which included an exponential water-uptake function (-e) or the 40-30-20-10 water-uptake function (-4); (ii) the solute movement equation for a reactive salt of a linear reaction term (the Lrchem-e and Lrchem-4 models); or the employment of output (salinity of soil solution, EC vs concentration factor, CF) of the SAO comprehensive chemical model (the LrSAO-e and LrSAO-4 models); and (iii) the inclusion of an effective soil solution volume in the transport equations. The root-zone average relative effective soil solution volume νeff (L | L50, p) was of sigmoidal response to leaching fraction (L) with two adjustable parameters L50 and p; the root-zone average reduced retention coefficient decreased linearly with L; and salt concentration at soil surface was related to salt concentration of irrigation water (ECi) by the fraction of irrigation water that evaporated (∈). The resulted concentration profiles indicated the salt behaved as a conservative one down to a threshold depth (xs) below of which salt was retained and precipitated. The depth of the conservative-salt front, xs increased with L and the 40-30-20-10 water-uptake pattern overestimated the xs depth relative to the exponential pattern. Concentration profiles were integrated to compute the root-zone average salinity, which was converted to crop salt-tolerance threshold (AE). The four conceptual models were successfully calibrated using experimental AE/ECi vs. Lr data with the input parameter values: ς = 0.27, p = 1.44, L50 = 0.16, ω = 2, and ∈ = 0 or 0.1 for the exponential or the 40-30-20-10 pattern, respectively; where ς is relative root length parameter and ω is a weighing parameter. No significant difference existed between the four model correlations at the 0.05 level. The four models require ECi and AE of the crop as input for Lr prediction. Sensitivity analysis revealed predicted Lr was sensitive the least to error in ∈. For tolerant and moderately tolerant crops Lr was sensitive the most to ς, and for sensitive crops to L50 and p. Model verification and validation were discussed. In deriving the present Lr models, no osmotic adjustment was required and both the exponential and the 40-30-20-10 water uptake patterns were, equivalently, applicable. This revised version was published online in July 2006 with corrections to the Cover Date.     

Production of acidic xylo-oligosaccharides by a family 10 endoxylanase from Thermoascus aurantiacus and use as plant growth regulators

Neutral and acidic oligosaccharides were obtained from birchwood xylan by treatment with an endoxylanase, family 10 class, from Thermoascus aurantiacus. The main acidic xylooligosaccharide (aldotetrauronic acid) was separated from the hydrolysate by anion-exchange and size-exclusion chromatography and the primary structure was determined by ¹³C NMR spectroscopy. The aldotetrauronic yield was 15% (w/w) of the total solubilised sugars. The addition of purified aldoterauronic acid at 1.6–16 mg l^–1 growth medium, induced callus and somatic embryogenesis in culture explants of common mallow (Malva silvestris L.) and cotton (Gosssypium hirsutum).