Influence of Storage at Freezing and Subsequent Refrigeration Temperatures on β-Galactosidase Activity of Lactobacillus acidophilus

The ability of three strains of Lactobacillus acidophilus to survive and retain β-galactosidase activity during storage in liquid nitrogen at −196°C and during subsequent storage in milk at 5°C was tested. The level of β-galactosidase activity varied among the three strains (0.048 to 0.177 U/10⁷ organisms). Freezing and storage at −196°C had much less adverse influence on viability and activity of the enzyme than did storage in milk at 5°C. The strains varied in the extent of the losses of viability and β-galactosidase activity during both types of storage. There was not a significant interaction between storage at −196°C and subsequent storage at 5°C. The strains that exhibited the greatest losses of β-galactosidase activity during storage in milk at 5°C also exhibited the greatest losses in viability at 5°C. However, the losses in viability were of much greater magnitude than were the losses of enzymatic activity. This indicates that some cells of L. acidophilus which failed to form colonies on the enumeration medium still possessed β-galactosidase activity. Cultures of L. acidophilus to be used as dietary adjuncts to improve lactose utilization in humans should be carefully selected to ensure that adequate β-galactosidase activity is provided.     

Mechanistic basis for differential inhibition of the F1Fo‐ATPase by aurovertin

The mitochondrial F₁F_o‐ATPase performs the terminal step of oxidative phosphorylation. Small molecules that modulate this enzyme have been invaluable in helping decipher F₁F_o‐ATPase structure, function, and mechanism. Aurovertin is an antibiotic that binds to the β subunits in the F₁ domain and inhibits F₁F_o‐ATPase‐catalyzed ATP synthesis in preference to ATP hydrolysis. Despite extensive study and the existence of crystallographic data, the molecular basis of the differential inhibition and kinetic mechanism of inhibition of ATP synthesis by aurovertin has not been resolved. To address these questions, we conducted a series of experiments in both bovine heart mitochondria and E. coli membrane F₁F_o‐ATPase. Aurovertin is a mixed, noncompetitive inhibitor of both ATP hydrolysis and synthesis with lower K_i values for synthesis. At low substrate concentrations, inhibition is cooperative suggesting a stoichiometry of two aurovertin per F₁F_o‐ATPase. Furthermore, aurovertin does not completely inhibit the ATP hydrolytic activity at saturating concentrations. Single‐molecule experiments provide evidence that the residual rate of ATP hydrolysis seen in the presence of saturating concentrations of aurovertin results from a decrease in the binding change mechanism by hindering catalytic site interactions. The results from these studies should further the understanding of how the F₁F_o‐ATPase catalyzes ATP synthesis and hydrolysis. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 830–840, 2009. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

Allometric scaling of kidney function in green iguanas

Numerous physiological parameters, such as metabolic rate and glomerular filtration rate (GFR), are allometrically related to body mass. Whereas the interspecific relationships between metabolic rate and body mass have been extensively studied in vertebrates, intraspecific studies of renal function have been limited. Therefore, kidney function was studied in 16 green iguanas, (Iguana iguana; 322-4764 g), by using nuclear scintigraphy to measure the renal uptake of 99mTc-diethylenetriamine pentaacetic acid (99mTc-DTPA), following either intravenous or intraosseous administration. Route of 99mTc-DTPA administration did not affect the percentage of the dose that accumulated in the kidney (P > 0.05). Renal uptake of 99mTc-DTPA was related to body mass (W, g) as: %Dose Kidney (min-1) = 11.09W(-0.235). Although not directly measured, the apparent renal clearance of 99mTc-DTPA could be described as: Renal CL 99mTc-DTPA (ml.min-1) = 0.005W(0.759), and the mass exponent did not differ from either the 2/3 or 3/4 values (P > 0.05). The similarity of the mass exponents relating both renal function and metabolic rate to body mass suggests a common mechanism underlying these allometric relationships. As this study also demonstrated that renal scintigraphy can be used to quantify kidney function in iguanas, this technique may be a useful research and diagnostic tool.     

The interface between the arbuscular mycorrhizal fungus Glomus intraradices and root cells of Panax quinquefolius: a Paris-type mycorrhizal association

Two major types of arbucular mycorrhizal associations, the Arum-type and the Paris-type, have been identified based on morphological features. Although the Paris-type is the most common, it is the Arum-type that has been most intensively studied in terms of structure/function because of its prevalence in agronomically important plant species. In this study, the interface between the host cell cytoplasm and intracellular hyphae (extensive hyphal coils and arbusculate coils), which typify the Paris-type mycorrhiza, was studied. Using immunofluorescence techniques combined with laser scanning confocal microscopy, dramatic changes in the cytoskeleton in colonized cells were observed. Changes in the positioning of both host cell microtubules and actin filaments occurred in colonized plant cells. Both microtubules and actin filaments were associated with the hyphal coils and the arbusculate coils. An interfacial matrix, of host origin, was demonstrated between hyphal coils and arbusculate coils using various affinity techniques. It formed an apoplastic compartment consisting of cellulose and pectins between the fungus and host cell cytoplasm. There was less labelling adjacent to the fine branches of arbusculate coils compared to the hyphal coils. These observations show some similarities to those seen with Arum-type mycorrhizas.     

Fibroblast growth factor 18 influences proximal programming during lung morphogenesis

The structure and functions of the airways of the lung change dramatically along their lengths. Large-diameter conducting airways are supported by cartilaginous rings and smooth muscle tissue and are lined by ciliated and secretory epithelial cells that are involved in mucociliary clearance. Smaller peripheral airways formed during branching morphogenesis are lined by cuboidal and squamous cells that facilitate gas exchange to a network of fine capillaries. The factors that mediate formation of these changing cell types and structures along the length of the airways are unknown. We report here that conditional expression of fibroblast growth factor (FGF)-18 in epithelial cells of the developing lung caused the airway to adopt structural features of proximal airways. Peripheral lung tubules were markedly diminished in numbers, whereas the size and extent of conducting airways were increased. Abnormal smooth muscle and cartilage were found in the walls of expanded distal airways, which were accompanied by atypically large pulmonary blood vessels. Expression of proteins normally expressed in peripheral lung tubules, including SP-B and pro-SP-C, was inhibited. FGF-18 mRNA was detected in normal mouse lung in stromal cells surrounding proximal airway cartilage and in peripheral lung mesenchyme. Effects were unique to FGF-18 because expression of other members of the FGF family had different consequences. These data show that FGF-18 is capable of enhancing proximal and inhibiting peripheral programs during lung morphogenesis.     

Sensory lateralization in pain subjective perception for noxious heat stimulus

The aim of the present study was to identify and characterize hemispheric lateralization for pain intensity perception. A sample of 351 healthy volunteers was tested by the immersion of the right hand for 10 s followed by the same test for the left hand (RL group; n = 199) or in a random sequence (RND group; n = 152) into a water bath (48 degrees C, 15 s). Pain intensity was self-reported by the Visual Analogue Scale (VAS). The motor hemispherical Lateralization Index (LI) was obtained by the Edinburgh Inventory. Gender, hand skin fold, interstimulus time and menstrual cycle data in case of female subjects were recorded. The sample, 60.7% females and 39.3% males, 20.4 +/- 0.18 (mean +/- SEM) years old, showed 92.1% right-handed subjects. Left hand VAS was significantly higher than right hand VAS for RL (7.24 +/- 1.31 vs 6.74 +/- 1.52; p < 0.01) and RND (7.24 +/- 0.82 vs 6.73 +/- 1.25; p < 0.01) both for right- and left-handed subjects. A low but significant correlation for VAS scores and LI was found (r = 0.14; p < 0.05 or r = 0.18; p < 0.05, for left or right hand, respectively). Skin fold was statistically similar in both hands (p > 0.05) being highly correlated with each other (r = 0.68; p < 0.05). Pain subjective perception was not correlated to interstimulus time (r = -0.01; p > 0.05). Females showed significantly higher values than males for both left and right hand VAS scores. Periovulatory phase VAS value was significantly higher than luteal phase VAS only for the right hand test (7.57 +/- 0.20 vs 6.47 +/- 0.33; p < 0.01). The results of the present study suggest a lateralization of pain intensity perception to the right hemisphere not correlated with the motor hemispheric lateralization.     

Application of waste activated bleaching earth containing rapeseed oil on riboflavin production in the culture of Ashbya gossypii

Waste activated bleaching earth (ABE) that contained 40% rapeseed oil and was discharged by an oil refinery plant, was used for riboflavin production in a culture of Ashbya gossypii. When 125 g/L waste ABE that contained 50 g/L rapeseed oil was added into the culture, the riboflavin concentration was 1.12 g/L, which was almost 1.6-fold as high as that of pure rapeseed oil. However, in waste ABE concentration higher than 125 g/L, the produced riboflavin concentration decreased, which was due to the difficulty in mixing due to the presence of a high amount of solid material in the culture. The surface of the waste ABE was smooth without a hitch, because of being covered with rapeseed oil. However, after the culture, the surface of the waste ABE seemed like that of new one, and the oil content was nearly zero grams per liter. The waste ABE, oily clay, and its black color gradually fade and yellow little by little, and finally the waste ABE changed to yellow powder. Of the riboflavin produced during the culture, 70% was adsorbed in the oil free waste ABE. With diluted alkali solution, extraction only two times yielded 90% recovery of riboflavin adsorbed in the waste ABE. The waste ABE containing waste vegetable oil was suitable for raw material for production of the value-added useful bioproducts, which might be a good model for reuse of the waste resource.     

Distribution of neuropeptide Y-like immunoreactive fibers in the cat thalamus

Neuropeptide Y-like immunoreactivity was studied in the thalamus of the cat using an indirect immunoperoxidase method. The densest network of immunoreactive fibers was observed in the nucleus (n.) paraventricularis anterior. In the anterior, intralaminar and midline thalamic nuclei, as well as in the n. geniculatum medialis, n. geniculatum lateralis, n. habenularis lateralis, n. medialis dorsalis, n. lateralis posterior and n. pulvinar a low density of neuropeptide Y-like immunoreactive fibers was observed. Neuropeptide Y-like fibers were totally absent in the n. ventralis lateralis, n. ventralis medialis, n. ventralis postero-medialis and n. ventralis postero-lateralis. In addition, neuropeptide Y-like perikarya were found in the n. parafascicularis, n. suprageniculatus, n. geniculatum lateralis ventralis, n. medialis dorsalis and n. lateralis posterior.     

Microarray Data Reveal Relationship between Jag1 and Ddr1 in Mouse Liver

Alagille syndrome is an autosomal dominant disorder involving bile duct paucity and cholestasis in addition to cardiac, skeletal, ophthalmologic, renal and vascular manifestations. Mutations in JAG1, encoding a ligand in the Notch signaling pathway, are found in 95% of patients meeting clinical criteria for Alagille syndrome. In order to define the role of Jag1 in the bile duct developmental abnormalities seen in ALGS, we previously created a Jag1 conditional knockout mouse model. Mice heterozygous for the Jag1 conditional and null alleles demonstrate abnormalities in postnatal bile duct growth and remodeling, with portal expansion and increased numbers of malformed bile ducts. In this study we report the results of microarray analysis and identify genes and pathways differentially expressed in the Jag1 conditional/null livers as compared with littermate controls. In the initial microarray analysis, we found that many of the genes up-regulated in the Jag1 conditional/null mutant livers were related to extracellular matrix (ECM) interactions, cell adhesion and cell migration. One of the most highly up-regulated genes was Ddr1, encoding a receptor tyrosine kinase (RTK) belonging to a large RTK family. We have found extensive co-localization of Jag1 and Ddr1 in bile ducts and blood vessels in postnatal liver. In addition, co-immunoprecipitation data provide evidence for a novel protein interaction between Jag1 and Ddr1. Further studies will be required to define the nature of this interaction and its functional consequences, which may have significant implications for bile duct remodeling and repair of liver injury.