Digestive tract and leaf processing capacity of the stream invertebrate Tipula lateralis

2006 ◽  
Vol 84 (8) ◽  
pp. 1087-1095 ◽  
Author(s):  
C. Canhoto ◽  
M.A.S. Graça
Keyword(s):  
Environmental Changes ◽  
Alnus Glutinosa ◽  
General Context ◽  
Microbial Counts ◽  
Transmission Electron ◽  
Leaf Processing ◽  
Colony Forming Units ◽  
Alkaline Conditions ◽  
Reducing Substances ◽  
Midgut Ph

We investigated the digestive potential of the stream detritivore Tipula lateralis Meigen, 1804 as a tool to understand and predict their ability to adapt to environmental changes, such as the nature of leaf resources reaching streams. The structure of larval digestive tracts and the presence of bacteria were investigated by scanning and transmission electron microscopy. Gut sections were investigated with respect to pH, microbial counts, and ability to digest protein and carbohydrates of unconditioned leaves of Alnus glutinosa (L.) Gaertn. and Eucalyptus globulus Labill. Alkaline conditions prevailed throughout the gut, with the highest values in the middle midgut (pH up to 10.8). An abundant microflora was closely associated with the caecum (~34 × 104 colony forming units (cfu)) and hindgut (~50 × 104 cfu), whereas the foregut and midgut seemed to be almost devoided of permanent bacteria (~0.45 × 104 to ~2.1 × 104 cfu). Digestion of T. lateralis seems to be optimized by compartmentalization: proteinase activity was limited to the midgut (0.017 ± 0.0054 change in absorbance units), while the capacity to release reducing substances was almost completely restricted to the caecum and being higher when alder was used as a substratum (0.437 ± 0.153 g glucose·mg–1·h–1). Eucalyptus oils resulted in a 25% reduction in enzymatic capability of gut extracts. Overall, the results suggest that T. lateralis has the enzymatic capability of feeding on recalcitrant leaves, but specific components of leaves such as oils have the potential to interfere with food intake by this leaf consumer. In a more general context, the results help to assess biological changes introduced by eucalyptus plantations in non-native areas.

scholarly journals Variability in larval gut pH regulation defines sensitivity to ocean acidification in six species of the Ambulacraria superphylum

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171066 ◽  
Author(s):  
Marian Hu ◽  
Yung-Che Tseng ◽  
Yi-Hsien Su ◽  
Etienne Lein ◽  
Hae-Gyeong Lee ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Large Scale ◽  
Environmental Changes ◽  
Ph Regulation ◽  
Gastric Ph ◽  
Differential Sensitivity ◽  
Larval Stages ◽  
Regulatory Systems ◽  
Alkaline Conditions ◽  
Gut Ph

The unusual rate and extent of environmental changes due to human activities may exceed the capacity of marine organisms to deal with this phenomenon. The identification of physiological systems that set the tolerance limits and their potential for phenotypic buffering in the most vulnerable ontogenetic stages become increasingly important to make large-scale projections. Here, we demonstrate that the differential sensitivity of non-calcifying Ambulacraria (echinoderms and hemichordates) larvae towards simulated ocean acidification is dictated by the physiology of their digestive systems. Gastric pH regulation upon experimental ocean acidification was compared in six species of the superphylum Ambulacraria. We observed a strong correlation between sensitivity to ocean acidification and the ability to regulate gut pH. Surprisingly, species with tightly regulated gastric pH were more sensitive to ocean acidification. This study provides evidence that strict maintenance of highly alkaline conditions in the larval gut of Ambulacraria early life stages may dictate their sensitivity to decreases in seawater pH. These findings highlight the importance of identifying and understanding pH regulatory systems in marine larval stages that may contribute to substantial energetic challenges under near-future ocean acidification scenarios.

Microbiological Quality of Commercial Tofu

1984 ◽  
Vol 47 (3) ◽  
pp. 177-181 ◽  
Author(s):  
T. G. REHBERGER ◽  
L. A. WILSON ◽  
B. A. GLATZ
Keyword(s):  
Microbiological Quality ◽  
Plate Count ◽  
Microbial Counts ◽  
Colony Forming Units ◽  
Low Levels ◽  
Microbial Groups ◽  
Yeasts And Molds ◽  
Processing Techniques

A study was done to investigate the microbiological quality of commercial tofu available in local retail outlets. A sampling method was first developed to obtain accurate and representative microbial counts of individual pieces of tofu. Plate count determination of total aerobic organisms, psychrotrophs, coliforms, sporeformers, yeasts and molds, and staphylococci were made on 60 tofu samples (representing three lots each of four different brands) obtained within 24 h after delivery to the retail store. In addition, for two brands that provided manufacturer's pull dates, the same microbial counts were obtained for samples stored in the laboratory at 10°C until the pull date. Of the tofu sampled immediately after purchase, 83% of the lots tested had total counts greater than 106 colony-forming units (CFU)/g and psychrotrophic counts greater than 104 CFU/g. In addition, 67% of the lots tested had confirmed coliform counts greater than 103 CFU/g. Very low levels (less than 10 CFU/g) of all other microbial groups tested for were found in the majority of lots. Samples held until the manufacturer's pull date contained higher total and psychrotrophic counts but lower or stable counts of other organisms compared with samples tested immediately after purchase. To improve the microbiological quality of tofu, processors need to reduce initial loads by improving sanitation and processing techniques, and retailers should provide more consistent and colder refrigerated storage.

Mesocosm and Microcosm Experiments On the Feeding of Temperate Salt Marsh Foraminifera

2019 ◽  
Vol 49 (3) ◽  
pp. 259-274
Author(s):  
Jennifer L. Frail-Gauthier ◽  
Peta J. Mudie ◽  
Alastair G. B. Simpson ◽  
David B. Scott
Keyword(s):  
Salt Marsh ◽  
Sea Level ◽  
Environmental Changes ◽  
Eastern Canada ◽  
Form And Function ◽  
Transmission Electron ◽  
Salt Marsh Sediment ◽  
And Function ◽  
Key Indicators ◽  
Agglutinated Foraminifera

Abstract Agglutinated foraminifera dominate in temperate salt marsh sediment, making them key indicators for monitoring sea level and environmental changes. Little is known about the biology of these benthic foraminifera because of difficulties in distinguishing live from dead specimens in laboratory cultures. We present data from 10 years of laboratory experiments using comparisons of the agglutinant trochamminids Trochammina inflata and Entzia macrescens and the miliolid Miliammina fusca with the calcareous rotalids Helenina anderseni and Elphidium williamsoni. Specimens were taken from a laboratory mesocosm representing Chezzetcook Inlet, a cool-temperate salt marsh in eastern Canada. We determined culture requirements for the agglutinated foraminifera in Petri dishes over 10–12 week periods. Five inexpensive, non-terminal ways of identifying live organisms were developed: spatial movement, detritus-gathering, attachment, clustering, and test opacity. Comparison with rose Bengal staining showed <10% diversion for calcareous species and T. inflata but M. fusca was over-counted by >30%. Terminal chambers of Trochammina inflata were examined by transmission electron microscopy to visualise food consumption and identify food in digestive vacuoles, both in specimens from mesocosm and in culture. Bacteria and unidentified detritus in the vacuoles establish that this agglutinated species is a saprophagous and bacterivorous detritivore. The adhesive secretions by these species apparently help them gather and possibly farm food while being relatively immobile in the sediments. Our observations of movement and feeding orientation in the agglutinants suggest links between form and function that underscore their value as ultra high resolution sea-level proxies. Mesocosm biomass and abundance counts show that foraminifera represent >50% of the meiofaunal biomass, emphasising their importance in the food web and energy-flow dynamics of temperate salt marsh systems.

Yolk platelet degradation in preemergence Artemia embryos: response to protons in vivo and in vitro

1987 ◽  
Vol 252 (4) ◽  
pp. R774-R781 ◽  
Author(s):  
P. J. Utterback ◽  
S. C. Hand
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dry Weight ◽  
Platelet Protein ◽  
Transmission Electron ◽  
Structural Differences ◽  
Alkaline Conditions ◽  
Yolk Platelet

Alteration of intracellular pH (pHi) influences yolk platelet degradation during preemergence development in Artemia embryos. Cysts incubated for 10 h under conditions of aerobic development (aqueous medium equilibrated with 60% N2-40% O2, pHi greater than or equal to 7.9) exhibit a significant decrease in numbers of yolk platelets and platelet protein. In contrast, cysts incubated for 10 h under aerobic acidosis (60% CO2-40% O2, pHi = 6.8) show no significant decrease in numbers of yolk platelets or platelet protein. When subjected to alkaline conditions in vitro, yolk platelets release protein exponentially as a function of time. The process is essentially complete in 40 min. The extent of protein and lipid release from platelets increases markedly as pH of the medium is raised in increments from 6.3 to 8.0. Concomitant with these changes are reduction (50%) in platelet dry weight and reduction (21%) in platelet diameter. Transmission electron microscopy does not reveal major structural differences between isolated yolk platelets and those contained in hydrated embryos. The proton effects on platelet composition and size detected in vitro may explain in part the mechanism of platelet degradation observed during aerobic development and its suppression under conditions of acidic pHi.

Iron Oxide Nanoparticles Obtained from a Fe(II) - Chitosan Polymer Film

2010 ◽  
Vol 644 ◽  
pp. 51-55 ◽  
Author(s):  
Juan Fco Luna Martínez ◽  
E. Reyes-Melo ◽  
Virgilio González-González ◽  
A. Torres-Castro ◽  
Carlos Guerrero-Salazar ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Composite Film ◽  
Polymer Film ◽  
Iron Oxide Nanoparticles ◽  
Magnetic Behavior ◽  
Nanostructured Material ◽  
Oxide Nanoparticles ◽  
Transmission Electron ◽  
Alkaline Conditions

In this work, iron oxide nanoparticles (~5 nm) embedded in a chitosan polymer film, were synthesized. In order to obtain this nanostructured material, firstly a homogenous film of Fe(II)-chitosan was prepared. The resulting composite film has a thickness of ~140μm. Iron oxide nanoparticles were in-situ synthesized by treating the composite film with H2O2 under alkaline conditions. The morphological analysis by Transmission Electron Microscopy (TEM) shows the nanoparticles were embedded and stabilized in chitosan polymer film. The magnetic behavior was studied by magnetization measurements. The magnetization curves at room temperature showed that iron oxide nanoparticles have a superparamagnetic behavior.

Microstructural development of BaTiO3 powders synthesized by aqueous methods

1996 ◽  
Vol 11 (6) ◽  
pp. 1325-1328 ◽  
Author(s):  
L. Zhao ◽  
A. T. Chien ◽  
F. F. Lange ◽  
J. S. Speck
Keyword(s):  
Electron Microscopy ◽  
Lattice Mismatch ◽  
Anatase Tio2 ◽  
Microstructural Development ◽  
Complete Conversion ◽  
Epitaxial Relationship ◽  
Tio2 Particles ◽  
Transmission Electron ◽  
Alkaline Conditions ◽  
Relationship Of

The hydrothermal growth of perovskite BaTiO3 powders has been studied by transmission electron microscopy. The growth is carried out under high alkaline conditions (pH — 14) achieved with Ba(OH)2. Anatase (TiO2) is used as a titanium source. The perovskite BaTiO3 nucleates heterogeneously on anatase TiO2 particles with an epitaxial relationship of (001)TiO2 ‖ (001)BaTiO3 and [010]TiO2 ‖ [010]BaTiO3. This epitaxial relationship preserves the parallel alignment of the oxygen octahedra between the structures. A mosaic misorientation between (001)TiO2 and (001)BaTiO3 along 〈110〉 is seen in this relationship due to the lattice mismatch between TiO2 and BaTiO3. After complete conversion of the anatase to BaTiO3, the BaTiO3 particles develop into {111} octahedrons with ∼10 nm {001} and {110} microfacets on the {111} faces. This evolution suggests that {111} becomes the stable crystallographic facet for BaTiO3 under highly alkaline conditions.

Kinetic studies on carbohydrates in alkaline conditions III. Interconversion of D-glucose, D-fructose and D-mannose in feebly alkaline solution

1955 ◽  
Vol 228 (1172) ◽  
pp. 100-119 ◽  
Keyword(s):  
Sodium Bicarbonate ◽  
Alkaline Solution ◽  
Kinetic Studies ◽  
Alternative Mechanism ◽  
Bicarbonate Buffer ◽  
First Order ◽  
Alkaline Conditions ◽  
The Common ◽  
Singly Charged ◽  
Reducing Substances

The interconversion of glucose, fructose and mannose in sodium carbonate-sodium bicarbonate buffer at pH 10.14 has been studied kinetically at 35 and 50° C. Degradation and the formation of other reducing substances also occur at significant rates and consideration of these reactions was necessary. The ratios of the three sugar concentrations become constant after a sufficient interval of time, and in these conditions the ratio [mannose]/ [glucose + fructose + mannose] was found to be 0.18 approximately, which is higher than has been previously reported. The reactions are shown to be first order in the concentrations of the three sugars, and the results are consistent with a mechanism in which these sugars form a common intermediate. The alternative mechanism, in which fructose is an intermediate in the interconversion of glucose and mannose, is not supported. A comparison with the experiments at much higher alkaiinities reported in parts I and II identifies the common intermediate with the singly charged enolate ion XH 2 - previously described. The comparison has enabled all the relevant velocity constants to be calculated. From these constants the rates of autoxidation of the sugars under the present conditions may be estimated; the results are shown to be in satisfactory agreement with observation. This supplies an additional check on the validity of the proposed mechanism. The latter is also shown to be consistent with the results of recent investigations on deuterium exchange in interconversion.

scholarly journals Preparation of Nano-Sized Mesoporous Silica and Its Application in Immobilization of β-galactosidase from Aspergillus Oryzae

2017 ◽  
Vol 9 (1) ◽  
pp. 65
Author(s):  
Jiao Yang ◽  
Zhenzhen Liu ◽  
Huan Ge ◽  
Sufang Sun
Keyword(s):  
Mesoporous Silica ◽  
Aspergillus Oryzae ◽  
Nitrogen Adsorption ◽  
Ammonium Bromide ◽  
Experimental Conditions ◽  
Transmission Electron ◽  
Alkaline Conditions ◽  
Activity Yield ◽  
Cetyl Trimethyl Ammonium ◽  
First Time

In alkaline conditions, monodisperse nano-sized mesoporous silica was synthesized using cetyl trimethyl ammonium bromide (CTAB) as template and tetraethoxysilane (TEOS) silica as source in ethanol / water cosolvent conditions. Using method of nitrogen adsorption, specific surface area of the dried monodisperse nano-sized mesoporous silica was about 1591 m2/g and the pore size was about 3.8 nm. The field-emission scanning electron microscope (SEM) micrographs showed that the silica particles obtained were spherical with an approximate diameter of 160 nm and of good dispersion. Transmission electron microscopy (TEM) revealed that the carrier had an excellent cellular structure with disordered multi-channels and smooth surface. The nano-sized mesoporous silica above was employed to immobilize β-galactosidase from aspergillus oryzae for the first time. At the experimental conditions in section 2.4, the enzyme activity and the activity yield were 535.11 U/g dry carrier and 79.63%, respectively. Kinetic data of the immobilized enzyme such as optimum temperature, pH, and thermal and pH stability among other valuable results were also determined.

scholarly journals Flavor and Other Quality Factors of Enzyme-peeled Oranges Treated with Citric Acid

HortScience ◽  
2007 ◽  
Vol 42 (7) ◽  
pp. 1644-1650 ◽  
Author(s):  
Simona Pinnavaia ◽  
Emilio Senesi ◽  
Anne Plotto ◽  
Jan A. Narciso ◽  
Elizabeth A. Baldwin
Keyword(s):  
Citric Acid ◽  
Bacterial Growth ◽  
Titratable Acidity ◽  
Taste Panel ◽  
Enzyme Treatment ◽  
Quality Factors ◽  
Microbial Counts ◽  
Aroma Volatiles ◽  
Colony Forming Units ◽  
Methyl Butanoate

Oranges can be satisfactorily processed for fresh slices using a process of enzyme infiltration under vacuum. Scored ‘Valencia’ and ‘Hamlin’ oranges were placed under 90 kPa vacuum in water, 1% citric acid (CA), or 1000 ppm pectinase (Ultrazym) at 30 °C for 2 min followed by 30 min incubation in air. After peeling, fruit were washed, cut, and all but CA-infused slices were dipped in water or 1% CA for 2 min. Drained slices were placed in sealed 454-mL deli containers and stored at 5 °C for up to 21 days. All ‘Valencia’ slices had microbial counts less than 1.0 log cfu·g−1 (cfu = colony-forming units) after 7 days storage, and slices from CA-infused fruit had less than 1.0 log cfu·g−1 after 21 days storage. For ‘Hamlin’, CA dips controlled bacterial growth on slices from water-infused oranges, except at 14 days. Enzyme-infused oranges resulted in slices with lower counts for both cultivars. CA-treated sliced (post enzyme treatment or by infusion) oranges had higher titratable acidity initially (‘Hamlin’) and after 14 days (‘Valencia’). When presented to a taste panel, ‘Valencia’ slices from enzyme-peeled fruit were preferred for texture after 2 days and 8 days in storage. In contrast, slices from fruit infused with water or citric acid were least preferred, were firmer, and had thicker segment membranes. Appearance of enzyme-treated fruit was preferred for ‘Hamlin’ oranges. Enzyme treatments increased levels of aroma volatiles, methanol and methyl butanoate, in ‘Hamlin’ slices, but overall sensory flavor data were unaffected.

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