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991.
Glossoscolex paulistus extracellular hemoglobin (HbGp) oligomeric dissociation upon interaction with sodium dodecyl sulfate: Isothermal titration calorimetry (ITC)
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Fernanda Rosa Alves Francisco Adriano O. Carvalho José Wilson P. Carvalho Marcel Tabak 《Biopolymers》2014,101(10):1065-1076
Annelid erythrocruorins are respiratory proteins with high cooperativity and low autoxidation rates. The giant extracellular hemoglobin of the earthworm, Glossoscolex paulistus (HbGp), has a molecular mass of 3.6 MDa. In this work, isothermal titration calorimetry (ITC), together with DLS and fluorescence emission have been used to investigate the interaction of SDS with the HbGp in the oxy‐form, at pH 7.0. Our ITC and DLS results show that addition of SDS induces oxy‐HbGp oligomeric dissociation, while a small amount of protein aggregation is observed only by DLS. Moreover, the oligomeric dissociation process is favored at lower protein concentrations. The temperature effect does not influence significantly the interaction of SDS with the hemoglobin, due to the similarities presented by the critical aggregation concentration (cac) and critical micelle concentration (cmc′) for the mixtures. The increase of oxy‐HbGp concentration leads to a slight variation of the cac values for the SDS‐oxy‐HbGp mixture, attributed mainly to the noncooperative electrostatic binding of surfactant to protein. However, the cmc′ values increase considerably, associated to a more cooperative hydrophobic binding. Complementary pyrene fluorescence emission studies show formation of pre‐micellar structures of the mixture already at lower SDS concentrations. This study opens the possibility of the evaluation of the surfactant effect on the hemoglobin stability by ITC, which is made for the first time with this extracellular hemoglobin. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1065–1076, 2014. 相似文献
992.
Brett Jestrow Ethan Freid Santiago Arango-Garces Javier Francisco-Ortega 《The Botanical review》2014,80(3):231-244
Dr. John Popenoe was Director of Fairchild Tropical Botanic Garden (FTBG) between 1963 and 1989. Dr. Popenoe was a strong supporter of the Bahamian flora, and in 1963 he obtained extramural funds to develop a living collection focusing on Bahamian plants that was established in FTBG. During his tenure FTBG supported the publication of the latest comprehensive flora of this archipelago. A project initiated by the first FTBG herbarium curator, William Gillis, but published by Donovan and Helen Correll (with illustrations of Priscilla Fawcett) in 1982. This living collection of Bahamian plants has supplied plant material for molecular phylogenetic studies worldwide. There are DNA phylogenies for only 10 of the 89 Bahamian endemics; most of the material of these phylogenies came from plants from these collections (three species) and/or from fragments of herbarium specimens collected by Donovan Correll (six species). Only two of the species included in these phylogenies are from collections unrelated to FTBG. Excluding species restricted to the Bahamas, material from 14 Caribbean Island endemics that are part of these collections has been used in phylogenetic studies. The available molecular phylogenies show that the Bahamian endemics are closely related to species from the West Indies or continental areas of the Caribbean Basin. There is also a paucity of population genetic studies based on DNA markers focusing on Bahamian plants. Only two of the four available population genetic studies are for a Bahamian endemic taxon. 相似文献
993.
Jane Mello Lopes Cheila de Lima Boijink Luiz Henrique Florindo Cleo Alcantara Costa Leite Ana Lúcia Kalinin William K. Milsom Francisco Tadeu Rantin 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(6):797-811
In one series of experiments, heart frequency (f
H), blood pressure (P
a), gill ventilation frequency (f
R
), ventilation amplitude (V
AMP) and total gill ventilation (V
TOT) were measured in intact jeju (Hoplerythrinus unitaeniatus) and jeju with progressive denervation of the branchial branches of cranial nerves IX (glossopharyngeal) and X (vagus) without
access to air. When these fish were submitted to graded hypoxia (water PO2 ~140, normoxia to 17 mmHg, severe hypoxia), they increased f
R
, V
AMP, V
TOT and P
a and decreased f
H. In a second series of experiments, air-breathing frequency (f
RA), measured in fish with access to the surface, increased with graded hypoxia. In both series, bilateral denervation of all
gill arches eliminated the responses to graded hypoxia. Based on the effects of internal (caudal vein, 150 μg NaCN in 0.2 mL
saline) and external (buccal) injections of NaCN (500 μg NaCN in 1.0 mL water) on f
R
, V
AMP, V
TOT, P
a and f
H we conclude that the O2 receptors involved in eliciting changes in gill ventilation and associated cardiovascular responses are present on all gill
arches and monitor the O2 levels of both inspired water and blood perfusing the gills. We also conclude that air breathing arises solely from stimulation
of branchial chemoreceptors and support the hypothesis that internal hypoxaemia is the primary drive to air breathing. 相似文献
994.
Foraminiferal assemblages from the Bifurcatus Zone (Oxfordian, Upper Jurassic) are studied in the Navalperal section (Betic
Cordillera, southern Spain). A total of 24 sampling stations and around 5,700 specimens of foraminifera were recognized on
thin-section analysis and classified into two major categories: planktonic and benthic. The abundance of foraminifera (number
of specimens/cm2) was calculated for both categories and the cyclic pattern was studied by spectral analysis, considering the autochthonous
and para-autochthonous character of the studied assemblages. The Lomb-Scargle periodogram together with a permutation test
were tested for performing the high-resolution spectral analysis, being particularly well suited for working with short time
series and uneven sampling. Spectral analysis reveals the influence of orbital-scale Milankovitch cyclicity at the eccentricity,
obliquity, and precession bands. Moreover, this incidence is significantly different depending on the analyzed group (benthic
versus planktonic). Whereas the long-range eccentricity band is not distinguishable from a trend and the short-range eccentricity
band is not statistically significant (at 90% confidence level), the obliquity band is better represented in the planktonic
component and the precession band is better developed in the benthic group. Variations in temperature affecting upper waters,
determined by obliquity-scale fluctuations, could be responsible for changes in the planktonic foraminiferal assemblage, while
changes in nutrient availability and substrate oxygenation, as a consequence of input variations from source areas at the
precession-scale cycles, could affect the benthic foraminiferal assemblage. 相似文献
995.
Leonardo D. Bacigalupe Diego M. Bustamante Francisco Bozinovic Roberto F. Nespolo 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(2):293-299
A major goal of evolutionary physiology is to understand the intrinsic and the extrinsic factors that impose limitations on
an animal’s energy budget. Although natural selection acts upon organismal traits such as performance (e.g., burst, sustained
metabolic rates), from a mechanistic perspective, organismal performance results from the integrated functioning of different
levels of biological organization. Hence, a better understanding of whole-animal performance must necessarily incorporate
an explicit analysis of the integration between those different levels. Although this topic has been under intense scrutiny,
overall there have been very few consistent patterns. Here, we explore the phenotypic integration between organ masses and
the overall energy budget under routine capacities by statistically decomposing the covariance matrix (using path analysis
and canonical correlation analysis) between organ masses and thermoregulatory burst and sustained metabolisms in cold acclimated
individuals of Phyllotis darwini. Our results suggest that (a) central organs associated with the processing of food (cecum and liver), residuals (kidneys)
and pumping of O2 (heart) are tightly integrated to sustained expenditure and between themselves; (b) with the exception of the heart, central
energy supplying organs are weakly related to burst expenditures; (c) sustained and burst metabolisms refer to complete different
strategies and (d) basal metabolic rate is not related to any of the physiological or morphological traits considered in this
study. Overall, our results support the hypothesis of an economic phenotype: animals maintain their excess capacities to face
those critical extreme events, but their physiology and internal morphology are tightly integrated to function under routine
needs. 相似文献
996.
Denise Navia Ronald Ochoa Cal Welbourn Francisco Ferragut 《Experimental & applied acarology》2010,51(1-3):225-255
Eriophyoids have high potential as adventive mite species (AMS) because their small size make them difficult to detect, and can be easily distributed in world trade. Economic, social and environmental impact from adventive eriophyoid mites has been significant. Considerable attention has been given to adventive insect species while adventive mites have received little attention and little information is available for eriophyoids. This paper summarizes information on adventive eriophyoid mites, their impact, and the history of some important invasions. The status of adventive species of eriophyoids introduced as biological control agents of weeds is presented. A list of eriophyoid mites reported as invasive species worldwide is given. Pathways of concern and biosecurity actions to reduce the risk of eriophyoid mites are discussed. The need to raise public awareness of the risk and importance of these tiny organisms as AMS is emphasized. Scientific and technical challenges to deal with adventive eriophyoids are discussed. 相似文献
997.
998.
Torregrosa-Hetland CJ Villanueva J López-Font I Garcia-Martinez V Gil A Gonzalez-Vélez V Segura J Viniegra S Gutiérrez LM 《Cellular and molecular neurobiology》2010,30(8):1315-1319
In chromaffin cells, SNARE proteins, forming the basic exocytotic machinery are present in membrane clusters of 500–600 nm
in diameter. These microdomains containing both SNAP-25 and syntaxin-1 are dynamic and the expression of altered forms of
SNAREs modifies not only their motion but also the mobility of the associated granules. It is also clear that SNARE microdomain
location defines the place for individual vesicle fusion and that the alteration of cluster dynamics affects the fusion process
itself. Interestingly, these SNARE patches colocalize with the borders of F-actin cages forming the cytoskeletal cortical
network, and these borders also contain clusters of L- and P/Q type calcium channels. The organization of the secretory machinery
in association with the borders of cytoskeletal cages seems to be an effective way to promote fast coupling between calcium
entry and catecholamine release as demonstrated with the use of mathematical secretory models. 相似文献
999.
We present an inventory of single or multiple calponin homology (CH) domain containing proteins of Dictyostelium discoideum. A multiple alignment and a phylogenetic tree of all 60 CH domains found in 36 proteins showed that most CH domains can be
assigned to one of 6 types. We have then distributed the proteins into several classes according to the type and arrangement
of the CH domains. Most proteins belong to the class of ABD (actin-binding domain)-forming CH tandems (CH1–CH2) of the α-actinin
and fimbrin families or to the class of CH3 domain-bearing proteins. There are a few examples of proteins with a single CH1
or CH2 domain, one with a CH1–CH1 doublet and a single representative of the CHe class of microtubule-binding proteins. A
comparison with CH domain proteins in Homo sapiens suggests that while the individual domains are available in both species, the existence of identical multidomain proteins
in toto is rare. Fimbrin 1, α-actinin and EB1 appear as perfect orthologs in both species, whereas filamin and interaptin
may represent ancestral forms of human filamin and nesprins. In four more cases (NAV/Unc-53-, smoothelin-, transgelin- and
Gas2-related proteins) functional data are needed in order to establish a potential relationship with a human counterpart.
Although extensive data exist for a few of the D. discoideum CH proteins, most remain to be characterized and our analysis may help predicting some of their properties. 相似文献
1000.
Laura Mazzaferro Lucrecia Piñuel Marisol Minig Javier D. Breccia 《Archives of microbiology》2010,192(5):383-393
We screened for microorganisms able to use flavonoids as a carbon source; and one isolate, nominated Stilbella fimetaria SES201, was found to possess a disaccharide-specific hydrolase. It was a cell-bound ectoenzyme that was released to the medium
during conidiogenesis. The enzyme was shown to cleave the flavonoid hesperidin (hesperetin 7-O-α-rhamnopyranosyl-β-glucopyranoside)
into rutinose (α-rhamnopyranosyl-β-glucopyranose) and hesperetin. Since only intracellular traces of monoglycosidase activities
(β-glucosidase, α-rhamnosidase) were produced, the disaccharidase α-rhamnosyl-β-glucosidase was the main system utilized by
the microorganism for hesperidin hydrolysis. The enzyme was a glycoprotein with a molecular weight of 42224 Da and isoelectric
point of 5.7. Even when maximum activity was found at 70°C, it was active at temperatures as low as 5°C, consistent with the
psychrotolerant character of S. fimetaria. Substrate preference studies indicated that the enzyme exhibits high specificity toward 7-O-linked flavonoid β-rutinosides.
It did not act on flavonoid 3-O-β-rutinoside and 7-O-β-neohesperidosides, neither monoglycosylated substrates. In an aqueous
medium, the α-rhamnosyl-β-glucosidase was also able to transfer rutinose to other acceptors besides water, indicating its
potential as biocatalyst for organic synthesis. The monoenzyme strategy of S. fimetaria SES201, as well as the enzyme substrate preference for 7-O-β-flavonoid rutinosides, is unique characteristics among the microbial
flavonoid deglycosylation systems reported. 相似文献