Intestinal caveolin-1 is important for dietary fatty acid absorption

How dietary fatty acids are absorbed into the enterocyte and transported to the ER is not established. We tested the possibility that caveolin-1 containing lipid rafts and endocytic vesicles were involved. Apical brush border membranes took up 15% of albumin bound ³H-oleate whereas brush border membranes from caveolin-1 KO mice took up only 1%. In brush border membranes, the ³H-oleate was in the detergent resistant fraction of an OptiPrep gradient. On OptiPrep gradients of intestinal cytosol, we also found the ³H-oleate in the detergent resistant fraction, separate from OptiPrep gradients spiked with ³H-oleate or ³H-triacylglycerol. Caveolin-1 immuno-depletion of cytosol removed 91% of absorbed ³H-oleate whereas immuno-depletion using IgG, or anti-caveolin-2 or -3 or anti-clathrin antibodies removed 20%. Electron microscopy showed the presence of caveolin-1 containing vesicles in WT mouse cytosol that were 4 fold increased by feeding intestinal sacs 1 mM oleate. No vesicles were seen in caveolin-1 KO mouse cytosol. Caveolin-1 KO mice gained less weight on a 23% fat diet and had increased fat in their stool compared to WT mice. We conclude that dietary fatty acids are absorbed by caveolae in enterocyte brush border membranes, are endocytosed, and transported in cytosol in caveolin-1 containing endocytic vesicles.     

Acid-Adapted Strains of Escherichia coli K-12 Obtained by Experimental Evolution

Enteric bacteria encounter a wide range of pHs throughout the human intestinal tract. We conducted experimental evolution of Escherichia coli K-12 to isolate clones with increased fitness during growth under acidic conditions (pH 4.5 to 4.8). Twenty-four independent populations of E. coli K-12 W3110 were evolved in LBK medium (10 g/liter tryptone, 5 g/liter yeast extract, 7.45 g/liter KCl) buffered with homopiperazine-N,N′-bis-2-(ethanosulfonic acid) and malate at pH 4.8. At generation 730, the pH was decreased to 4.6 with HCl. By 2,000 generations, all populations had achieved higher endpoint growth than the ancestor at pH 4.6 but not at pH 7.0. All evolving populations showed a progressive loss of activity of lysine decarboxylase (CadA), a major acid stress enzyme. This finding suggests a surprising association between acid adaptation and moderation of an acid stress response. At generation 2,000, eight clones were isolated from four populations, and their genomes were sequenced. Each clone showed between three and eight missense mutations, including one in a subunit of the RNA polymerase holoenzyme (rpoB, rpoC, or rpoD). Missense mutations were found in adiY, the activator of the acid-inducible arginine decarboxylase (adiA), and in gcvP (glycine decarboxylase), a possible acid stress component. For tests of fitness relative to that of the ancestor, lacZ::kan was transduced into each strain. All acid-evolved clones showed a high fitness advantage at pH 4.6. With the cytoplasmic pH depressed by benzoate (at external pH 6.5), acid-evolved clones showed decreased fitness; thus, there was no adaptation to cytoplasmic pH depression. At pH 9.0, acid-evolved clones showed no fitness advantage. Thus, our acid-evolved clones showed a fitness increase specific to low external pH.     

Seasonal and Diurnal Patterns of Behavior Exhibited by Atlantic Bottlenose Dolphins (Tursiops truncatus) in the Mississippi Sound

Many of the threats to bottlenose dolphins are anthropogenic factors including overfishing, high‐speed boats, chemical runoff, and noise pollution. Having a thorough understanding of the behavior and behavioral patterns of these animals can help with conservation plans to protect this species. This study examined the behavioral states and behavioral events of Atlantic bottlenose dolphins (Tursiops truncatus) in the Mississippi Sound. The behavioral states exhibited by dolphins within the Sound were found to vary by both season and time of day. Dolphins socialized more during the spring and spent more time feeding in the fall. Feeding was highest early in the morning and decreased throughout the day, while socializing occurred at low levels in the morning and increased in the early afternoon. Two distinct forms of social behavior and multiple feeding strategies were exhibited by dolphins within the Sound. Results suggest that certain percussive behavioral events may be used to communicate motivation during transitional behavioral states. These results demonstrate the need for a more complete understanding of dolphin behavior that will facilitate the conservation of this species.     

Seasonal Dynamics of the Airborne Bacterial Community and Selected Viruses in a Children’s Daycare Center

Children’s daycare centers appear to be hubs of respiratory infectious disease transmission, yet there is only limited information about the airborne microbial communities that are present in daycare centers. We have investigated the microbial community of the air in a daycare center, including seasonal dynamics in the bacterial community and the presence of specific viral pathogens. We collected filters from the heating, ventilation, and air conditioning (HVAC) system of a daycare center every two weeks over the course of a year. Amplifying and sequencing the 16S rRNA gene revealed that the air was dominated by Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes that are commonly associated with the human skin flora. Clear seasonal differences in the microbial community were not evident; however, the community structure differed when the daycare center was closed and unoccupied for a 13-day period. These results suggest that human occupancy, rather than the environment, is the major driver in shaping the microbial community structure in the air of the daycare center. Using PCR for targeted viruses, we detected a seasonal pattern in the presence of respiratory syncytial virus that included the period of typical occurrence of the disease related to the virus; however, we did not detect the presence of adenovirus or rotavirus at any time.     

Virus-like particles in the brown algaStreblonema

Summary Ultrastructural examination ofStreblonema sp. revealed icosahedral virus-like particles (135–150 nm) throughout the cytoplasm of vegetative cells. The densely packed particles consist of an osmiophilic coat around a fibrillar core. Most cytoplasmic organelles are excluded from the regions where the particles are extremely abundant, but no degeneration of plastids, mitochondria or dictyosomes is evident. The virogenic stroma contains many ribosomes and fibers possibly representing DNA strands remaining from the lysed nucleus. No decrease in vigor seemed to be associated with the presence of the particles.     

Maturation of the angiotensin II cardiovascular response in the embryonic White Leghorn chicken (Gallus gallus)

Angiotensin II (Ang II) is an important regulator of cardiovascular function in adult vertebrates. Although its role in regulating the adult system has been extensively investigated, the cardiovascular response to Ang II in embryonic vertebrates is relatively unknown. We investigated the potential of Ang II as a regulator of cardiovascular function in embryonic chickens, which lack central nervous system control of cardiovascular function throughout the majority of incubation. The cardiovascular response to Ang II in embryonic chickens was investigated over the final 50% of their development. Ang II produced a dose-dependent increase in arterial pressure on each day of development studied, and the response increased in intensity as development progressed. The Ang II type-1 receptor nonspecific competitive peptide antagonist [Sar¹ ile⁸] Ang II blocked the cardiovascular response to subsequent injections of Ang II on day 21 only. The embryonic pressure response to Ang II (hypertension only) differed from that of adult chickens, in which initial hypotension is followed by hypertension. The constant level of gene expression for the Ang II receptor, in conjunction with an increasing pressure response to the peptide, suggests that two Ang II receptor subtypes are present during chicken development. Collectively, the data indicate that Ang II plays an important role in the cardiovascular development of chickens; however, its role in maintaining basal function requires further study.     

Bacterial production of free fatty acids from freshwater macroalgal cellulose

The predominant strategy for using algae to produce biofuels relies on the overproduction of lipids in microalgae with subsequent conversion to biodiesel (methyl-esters) or green diesel (alkanes). Conditions that both optimize algal growth and lipid accumulation rarely overlap, and differences in growth rates can lead to wild species outcompeting the desired lipid-rich strains. Here, we demonstrate an alternative strategy in which cellulose contained in the cell walls of multicellular algae is used as a feedstock for cultivating biofuel-producing microorganisms. Cellulose was extracted from an environmental sample of Cladophora glomerata-dominated periphyton that was collected from Lake Mendota, WI, USA. The resulting cellulose cake was hydrolyzed by commercial enzymes to release fermentable glucose. The hydrolysis mixture was used to formulate an undefined medium that was able to support the growth, without supplementation, of a free fatty acid (FFA)-overproducing strain of Escherichia coli (Lennen et. al 2010). To maximize free fatty acid production from glucose, an isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible vector was constructed to express the Umbellularia californica acyl-acyl carrier protein (ACP) thioesterase. Thioesterase expression was optimized by inducing cultures with 50 μM IPTG. Cell density and FFA titers from cultures grown on algae-based media reached 50% of those (～90 μg/mL FFA) cultures grown on rich Luria-Bertani broth supplemented with 0.2% glucose. In comparison, cultures grown in two media based on AFEX-pretreated corn stover generated tenfold less FFA than cultures grown in algae-based media. This study demonstrates that macroalgal cellulose is a potential carbon source for the production of biofuels or other microbially synthesized compounds.     

Phenol utilization by filamentous yeast Trichosporon cutaneum

The investigated strain Trichosporon cutaneum shows well expressed capability for metabolizing high concentrations of phenol, up to 1 g/l, utilizing it as the sole carbon source for the growth and development of the population. The data reported, prove the good perspectives for its application in protecting the environment from phenol pollution. No data about modelling the process of cultivation of Trichosporon cutaneum in phenol media is available in scientific literature up to now. The mathematical model, reported here, consists of two nonlinear differential equations, describing cell growth and substrate consumption. The unknown parameters are estimated following the method of Hooke and Jeeves. A number of simulation investigations are carried out. They prove the adequacy of the model and its applicability in further studies on the processes of growth and phenol uptake of Trichosporon cutaneum.     

Role of hydrolysis conditions in the enzyme-mediated release of reducing sugars from sulphite pulp

Summary The release of reducing sugars from sulphite pulp treated with an Aureobasidium pullulans xylanase preparation was studied. Hydrolysis conditions such as pH, buffer, temperature and time of enzyme treatment were optimized in terms of their effect on sulphite pulp for production of dissolving pulp with an improved quality. Enzyme hydrolysis of pulp was found to be most effective at a temperature of 55°C and at pH 4.7 using sodium acetate buffer.