Guar gum: a cheap substitute for agar in microbial culture media

AIMS: To determine the possibility of using guar gum, a colloidal polysaccharide, as a cheap alternative to agar for gelling microbial culture media. METHODS AND RESULTS: As illustrative examples, 12 fungi and 11 bacteria were cultured on media solidified with either guar gum or agar. All fungi and bacteria exhibited normal growth and differentiation on the media gelled with guar gum. Microscopic examination of the fungi and bacteria grown on agar or guar gum gelled media did not reveal any structural differences. However, growth of most of the fungi was better on guar gum media than agar, and correspondingly, sporulation was also more advanced on the former. Bacterial enumeration studies carried out for Serratia sp. and Pseudomonas sp. by serial dilution and pour-plate method yielded similar counts on both agar and guar gum. Likewise, a selective medium, succinate medium used for growth of Pseudomonas sp. did not support growth of Bacillus sp. when inoculated along with Pseudomonas on both agar or guar gum supplemented medium. CONCLUSIONS: Guar gum, a galactomannan, which is 50 times cheaper than Difco-bacto agar, can be used as a gelling agent in place of agar in microbial culture media. SIGNIFICANCE AND IMPACT OF THE STUDY: As the media gelled with guar gum do not melt at temperature as high as 70 degrees C, these can be used for isolation and maintenance of thermophiles.     

Effect of genotype and root colonization in biological control of fusarium wilts in pigeonpea and chickpea by Pseudomonas aeruginosa PNA1

Pseudomonas aeruginosa PNA1, an isolate from chickpea rhizosphere in India, protected pigeonpea and chickpea plants from fusarium wilt disease, which is caused by Fusarium oxysporum f.sp. ciceris and Fusarium udum. Inoculation with strain PNA1 significantly reduced the incidence of fusarium wilt in pigeonpea and chickpea on both susceptible and moderately tolerant genotypes. However, strain PNA1 protected the plants from fusarium wilt until maturity only in moderately tolerant genotypes of pigeonpea and chickpea. Root colonization of pigeonpea and chickpea, which was measured using a lacZ-marked strain of PNA1, showed tenfold lower root colonization of susceptible genotypes than that of moderately tolerant genotypes, indicating that this plant-bacteria interaction could be important for disease suppression in this plant. Strain PNA1 produced two phenazine antibiotics, phenazine-1-carboxylic acid and oxychlororaphin, in vitro. Its Tn5 mutants (FM29 and FM13), which were deficient in phenazine production, caused a reduction or loss of wilt disease suppression in vivo. Hence, phenazine production by PNA1 also contributed to the biocontrol of fusarium wilt diseases in pigeonpea and chickpea.     

Chiral resolution of the epoxyeicosatrienoic acids, arachidonic acid epoxygenase metabolites

An HPLC method for the chiral analysis of the four regioisomeric epoxyeicosatrienoic acids (EETs) is described. The cytochrome P450 arachidonic acid epoxygenase metabolites are resolved, without the need for derivatization, by chiral-phase HPLC on a Chiralcel OJ column. Application of this methodology to the analysis of the liver endogenous EETs demonstrates stereospecific biosynthesis and corroborates the role of cytochrome P450 as the endogenous arachidonic acid epoxygenase.     

Diabetes alters vascular mechanotransduction: pressure-induced regulation of mitogen activated protein kinases in the rat inferior vena cava

Background

Foam cell formation in diabetic patients often occurs in the presence of high insulin and glucose levels. To test whether hyperinsulinemic hyperglycemic conditions affect foam cell differentiation, we examined gene expression, cytokine production, and Akt phosphorylation in human monocyte-derived macrophages incubated with two types of oxidized low density lipoprotein (LDL), minimally modified LDL (mmLDL) and extensively oxidized LDL (OxLDL).

Methods and results

Using Affymetrix GeneChip^® arrays, we found that several genes directly related to insulin signaling were changed. The insulin receptor and glucose-6-phosphate dehydrogenase were upregulated by mmLDL and OxLDL, whereas insulin-induced gene 1 was significantly down-regulated. In hyperinsulinemic hyperglycemic conditions, modified LDL upregulated Akt phosphorylation and expression of the insulin-regulated aminopeptidase. The level of proinflammatory cytokines, IL-lβ, IL-12, and IL-6, and of a 5-lipoxygenase eicosanoid, 5-hydroxyeicosatetraenoic acid (5-HETE), was also increased.

Conclusion

These results suggest that the exposure of macrophages to modified low density lipoproteins in hyperglycemic hyperinsulinemic conditions affects insulin signaling and promotes the release of proinflammatory stimuli, such as cytokines and eicosanoids. These in turn may contribute to the development of insulin resistance.     

Expression of the unconventional myosin Myo1c alters sodium transport in M1 collecting duct cells

Epithelial cells rely on proper targeting of cellular components to perform their physiological function. This dynamic process utilizes the cytoskeleton and involves movement of vesicles to and from the plasma membrane, thus traversing the actin cortical cytoskeleton. Studies support both direct interaction of actin with channels and an indirect mechanism whereby actin may serve as a track in the final delivery of the channel to the plasma membrane. Actin-dependent processes are often mediated via a member of the myosin family of proteins. Myosin I family members have been implicated in multiple cellular events occurring at the plasma membrane. In these studies, we investigated the function of the unconventional myosin I Myo1c in the M1 mouse collecting duct cell line. Myo1c was observed to be concentrated at or near the plasma membrane, often in discrete membrane domains. To address the possible role of Myo1c in channel regulation, we expressed a truncated Myo1c, lacking ATP and actin domains, in M1 cells and compared electrophysiological responses to control M1 cells, M1 cells expressing the empty vector, and M1 cells expressing the full-length Myo1c construct. Interestingly, cells expressing the Myo1c constructs had modulated antidiuretic hormone (ADH)-stimulated short-circuit current and showed little inhibition of short-circuit current with amiloride addition. Evaluation of enhanced green fluorescent protein-Myo1c constructs supports the importance of the IQ region in targeting the Myo1c to its respective cellular domain. These data are consistent with Myo1c participating in the regulation of the Na⁺ channel after ADH stimulation. actin; cytoskeleton; ion channel; kidney     

Ischemia disrupts myosin I beta in renal tubules

In thesestudies we have examined rat kidneys biochemically and microscopicallyto determine where myosin I is located before, during, and after anacute ischemic injury. Myosin I is present in multipletubule segments including the brush border (BB) of the proximal tubulecell (PTC). Its distribution is severely altered by a 15-min renalartery clamp. Myosin I is present in the urine during reflow and isfound in the numerous cellular blebs arising from the damaged PTC andother tubules. Two hours of reflow result in a decrease in BB myosinI staining and an increase in its cytoplasmic staining.Interestingly, the return of the F-actin in the BB precedes the returnof the myosin I, suggesting that this myosin I isoform may not playa role in rebuilding the microvilli after an ischemic injury. Anonstructural role for this myosin, such as transport or channelregulation, is supported by its presence in many tubule segments, allof which have transport and channel requirements but do not all contain microvilli.

     

A method for isolation and purification of peanut genomic DNA suitable for analytical applications

Numerous methods are available for isolation of plant genomic DNA, but in practice these procedures are empirical due to variability in plant tissue composition. Consistent isolation of quality DNA from peanut (Arachis hypogaea L.) is particularly problematic due to the presence of phenolic compounds and polysaccharides. Inconsistencies in extraction results can be attributed to the age and growth stage of the plant material analyzed. Mature leaves have higher quantities of polyphenols, tannins, and polysaccharides that can contaminate DNA during isolation. We show that four published protocols could not be used to isolate peanut DNA of sufficient quality for PCR amplification or Southern hybridization. We have devised a new protocol that uses DEAE-cellulose purification to isolate peanut DNA useful for downstream applications.     

Impaired overload-induced hypertrophy is associated with diminished mTOR signaling in insulin-resistant skeletal muscle of the obese Zucker rat

Recent data have suggested that insulin resistance may be associated with a diminished ability of skeletal muscle to undergo hypertrophy (Paturi S, Gutta AK, Kakarla SK, Katta A, Arnold EC, Wu M, Rice KM, Blough ER. J Appl Physiol 108: 7-13, 2010). Here we examine the effects of insulin resistance using the obese Zucker (OZ) rat with increased muscle loading on the regulation of the mammalian target of rapamycin (mTOR) and its downstream signaling intermediates 70-kDa ribosomal protein S6 kinase (p70S6k), ribosomal protein S6 (rpS6), eukaryotic elongation factor 2 (eEF2), and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). Compared with that observed in lean Zucker (LZ) rats, the degree of soleus muscle hypertrophy as assessed by changes in muscle wet weight (LZ: 35% vs. OZ: 16%) was significantly less in the OZ rats after 3 wk of muscle overload (P < 0.05). This diminished growth in the OZ rats was accompanied by significant impairments in the ability of the soleus to undergo phosphorylation of mTOR (Ser(2448)), p70S6k (Thr(389)), rpS6 (Ser(235/236)), and protein kinase B (Akt) (Ser(473) and Thr(308)) (P < 0.05). Taken together, these data suggest that impaired overload-induced hypertrophy in insulin-resistant skeletal muscle may be related to decreases in the ability of the muscle to undergo mTOR-related signaling.     

Molecular simulation on the interaction of Ethinylestradiol (EE2) with polymer membranes in wastewater purification

Molecular dynamics (MD) simulations are performed to study the adsorption of solute organic molecules (Ethinylestradiol (EE2) and testosterone) with different polymer membranes such as polyether sulfone (PES), polyvinylidene fluoride (PVDF). The equilibrium MD simulations results for the membrane solution interface system show that the interaction of EE2 with PES is specific and strong, whereas the interaction is weak and non-specific for PVDF. The binding free energies, the non-bonded short range interaction energies and mobility are also consistent with the interaction behaviour found in experiments. The adsorption of testosterone onto PES and PVDF is considered as control system. The result shows that binding free energies of PES and PVDF interacting with organic solute are consistent with experimental result in the order as; PES-EE2 > PES-Testosterone > PVDF-EE2 > PVDF-Testosterone. The formation hydrogen bonds and π–π interactions are observed between the EE2 and PES. In addition, adsorption of EE2 onto polyamide 6-12 (PA612) and polystyrene (PS) membranes are predicted. This simulation study provides molecular insights on the experimental observations and helps as a computational methodology to screen the membrane materials for EE2 removal from wastewater.