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1.
Structure and growth pattern of the bizarre hemispheric prominence on the rostrum of the fossil beaked whale Globicetus hiberus (Mammalia,Cetacea, Ziphiidae)
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Maïtena Dumont Vivian de Buffrénil Ismael Miján Olivier Lambert 《Journal of morphology》2016,277(10):1292-1308
The rostrum of most ziphiids (beaked whales) displays bizarre swollen regions, accompanied with extreme hypermineralisation and an alteration of the collagenous mesh of the bone. The functional significance of this specialization remains obscure. With the voluminous and dense hemispheric excrescence protruding from the premaxillae, the recently described fossil ziphiid Globicetus hiberus is the most spectacular case. This study describes the histological structure and interprets the growth pattern of this unique feature. Histologically, the prominence in Globicetus is made up of an atypical fibro‐lamellar complex displaying an irregular laminar organization and extreme compactness (osteosclerosis). Its development is suggested to have resulted from a protraction of periosteal accretion over the premaxillae, long after the end of somatic growth. Complex shifts in the geometry of this tissue are likely to have occurred during its accretion and no indication of Haversian remodeling could be found. X‐ray diffraction and Raman spectroscopy indicate that the bone matrix in the premaxillary prominence of Globicetus closely resembles that of the rostrum of the extant beaked whale Mesoplodon densirostris: apatite crystals are of common size and strongly oriented, but the collagenous meshwork within bone matrix seems to be extremely sparse. These morphological and structural data are discussed in the light of functional interpretations proposed for the highly unusual and diverse ziphiid rostrum. J. Morphol. 277:1292–1308, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
2.
Salt inhibition of RuBP carboxylase activity from Aphanothecehalophytica was caused by Cl-, but not by K+ nor Na+. The intracellularCl- concentration increased about 4-fold from 35 mM to 150 mM,when NaCl concentration in the culture medium was increasedfrom 0.5 M to 2.0 M.
1Permanent address: Department of Biochemistry, Faculty of Science,Chulalongkorn University, Bangkok, Thailand (Received February 12, 1988; Accepted June 1, 1988) 相似文献
3.
Maria F. S. Barbosa Maria B. de Medeiros Ismael M. de Mancilha Henry Schneider Hung Lee Ph.D. 《Journal of industrial microbiology & biotechnology》1988,3(4):241-251
Summary The ability to convertd-xylose to xylitol was screened in 44 yeasts from five genera. All but two of the strains produced some xylitol with varying rates and yields. The best xylitol producers were localized largely in the speciesCandida guilliermondii andC. tropicalis. Factors affecting xylitol production by a selectedC. guilliermondii strain, FTI-20037, were investigated. The results showed that xylitol yield by this strain was affected by the nitrogen source. Yield was highest at 30–35°C, and could be increased with decreasing aeration rate. Using high cell density and a defined medium under aerobic conditions, xylitol yield byC. guilliermondii FTI-20037 from 104 g/ld-xylose was found to be 77.2 g/l. This represented a yield of 81% of the theoretical value, which was computed to be 0.9 mol xylitol per mold-xylose.Issued as NRCC publication No. 28798. 相似文献
4.
M Glibowicka B Winckler N Araníbar M Schuster H Hanssum H Rüterjans H Passow 《Biochimica et biophysica acta》1988,946(2):345-358
Arrhenius plots of chloride and bromide transport yield two regions with different activation energies (Ea). Below 15 or 25 degrees C (for Cl- and Br-, respectively), Ea is about 32.5 kcal/mol; above these temperatures, about 22.5 kcal/mol (Brahm, J. (1977) J. Gen. Physiol. 70, 283-306). For the temperature dependence of SO4(2-) transport up to 37 degrees C, no such break could be observed. We were able to show that the temperature coefficient for the rate of SO4(2-) transport is higher than that for the rate of denaturation of the band 3 protein (as measured by NMR) or the destruction of the permeability barrier in the red cell membrane. It was possible, therefore, to extend the range of flux measurements up to 60 degrees C and to show that, even for the slowly permeating SO4(2-) in the Arrhenius plot, there appears a break, which is located somewhere between 30 and 37 degrees C and where Ea changes from 32.5 to 24.1 kcal/mol. At the break, the turnover number is approx. 6.9 ions/band 3 per s. Using 35Cl- -NMR (Falke, Pace and Chan (1984) J. Biol. Chem. 259, 6472-6480), we also determined the temperature dependence of Cl- -binding. We found no significant change over the entire range from 0 to 57 degrees C, regardless of whether the measurements were performed in the absence or presence of competing SO4(2-). We conclude that the enthalpy changes associated with Cl- - or SO4(2-)-binding are negligible as compared to the Ea values observed. It was possible, therefore, to calculate the thermodynamic parameters defined by transition-state theory for the transition of the anion-loaded transport protein to the activated state for Cl-, Br- and SO4(2-) below and above the temperatures at which the breaks in the Arrhenius plots are seen. We found in both regions a high positive activation entropy, resulting in a low free enthalpy of activation. Thus the internal energy required for carrying the complex between anion and transport protein over the rate-limiting energy barrier is largely compensated for by an increase of randomness in the protein and/or its aqueous environment. 相似文献
5.
When excited by ultraviolet radiation, leaves of a great number of species of higher plants exhibit emission of blue fluorescence, comparable in intensity to the red emission of chlorophyll. The fluorescence decay of the blue emission of spinach leaves recorded by single photon counting techniques is decomposed into exponential components and it is shown that at least three different components are present. The lifetime of the three components does not show significant variations with the excitation or emission wavelengths. The excitation and emission spectra of each component were determined. The nature of the chemical compounds which cause this emission is discussed in relation to these spectra. 相似文献
6.
Zoran G. Cerovic Maurice Bergher Yves Goulas Stephane Tosti Ismael Moya 《Photosynthesis research》1993,36(3):193-204
A newly developed nitrogen laser fluorimeter insensitive to actinic illumination was used to follow simultaneously the light induced changes in red and blue fluorescence of intact isolated spinach chloroplasts and leaf pieces. The recorded variable blue fluorescence was linked to a water soluble component of intact isolated chloroplasts, depended on Photosystem I, and was related to changes in carbon metabolism. From the comparison of changes in intact and broken chloroplasts and from fluorescence spectra under different conditions, it was concluded that the variation in NADPH was the major cause for the changes in blue fluorescence. This study opens a path towards continuous and non-destructive monitoring of NADPH redox state in chloroplasts and leaves.Abbreviations Chl
chlorophyll
- DHAP
dihydroxyacetone phosphate
- DLGA
DL-glyceraldehyde
- FNR
ferredoxin-NADP reductase
- FWHM
full width at half maximum
- LED
light emitting diodes
- OAA
oxaloacetate
- qN
non-photochemical quenching
- PGA
3-phosphoglycerate
- Pi
inorganic orthophosphate
- qP
photochemical quenching
- PPFD
photosynthetic photon flux density
- QA
primary quinone acceptor of Photosystem II
Preliminary results of this work were presented at the First Conference on the Physiology and Biochemistry of high Mountain Plants, 2–3 July 1992, Villar d'Arene, France. 相似文献
7.
María Florencia Pignataro María Georgina Herrera Natalia Brenda Fernández Martín Aran Hernán Gustavo Gentili Fernando Battaglini Javier Santos 《Biotechnology and bioengineering》2023,120(2):409-425
Frataxin is a kinetic activator of the mitochondrial supercomplex for iron-sulfur cluster assembly. Low frataxin expression or a decrease in its functionality results in Friedreich's Ataxia (FRDA). With the aim of creating new molecular tools to study this metabolic pathway, and ultimately, to explore new therapeutic strategies, we have investigated the possibility of obtaining small proteins exhibiting a high affinity for frataxin. In this study, we applied the ribosome display approach, using human frataxin as the target. We focused on Affi_224, one of the proteins that we were able to select after five rounds of selection. We have studied the interaction between both proteins and discussed some applications of this specific molecular tutor, concerning the modulation of the supercomplex activity. Affi_224 and frataxin showed a KD value in the nanomolar range, as judged by surface plasmon resonance analysis. Most likely, it binds to the frataxin acidic ridge, as suggested by the analysis of chemical shift perturbations (nuclear magnetic resonance) and computational simulations. Affi_224 was able to increase Cys NFS1 desulfurase activation exerted by the FRDA frataxin variant G130V. Importantly, Affi_224 interacts with frataxin in a human cellular model. Our results suggest quaternary addition may be a new tool to modulate frataxin function in vivo. Nevertheless, more functional experiments under physiological conditions should be carried out to evaluate Affi_224 effectiveness in FRDA cell models. 相似文献
8.
Roberto de la Herrán Miguel Hermida Juan Andres Rubiolo Jèssica Gómez-Garrido Fernando Cruz Francisca Robles Rafael Navajas-Pérez Andres Blanco Paula Rodriguez Villamayor Dorinda Torres Pablo Sánchez-Quinteiro Daniel Ramirez Maria Esther Rodríguez Alberto Arias-Pérez Ismael Cross Neil Duncan Teresa Martínez-Peña Ana Riaza Adrian Millán M. Cristina De Rosa Davide Pirolli Marta Gut Carmen Bouza Diego Robledo Laureana Rebordinos Tyler Alioto Carmelo Ruíz-Rejón Paulino Martínez 《Molecular ecology resources》2023,23(4):886-904
Sex determination (SD) shows huge variation among fish and a high evolutionary rate, as illustrated by the Pleuronectiformes (flatfishes). This order is characterized by its adaptation to demersal life, compact genomes and diversity of SD mechanisms. Here, we assembled the Solea senegalensis genome, a flatfish of great commercial value, into 82 contigs (614 Mb) combining long- and short-read sequencing, which were next scaffolded using a highly dense genetic map (28,838 markers, 21 linkage groups), representing 98.9% of the assembly. Further, we established the correspondence between the assembly and the 21 chromosomes by using BAC-FISH. Whole genome resequencing of six males and six females enabled the identification of 41 single nucleotide polymorphism variants in the follicle stimulating hormone receptor (fshr) consistent with an XX/XY SD system. The observed sex association was validated in a broader independent sample, providing a novel molecular sexing tool. The fshr gene displayed differential expression between male and female gonads from 86 days post-fertilization, when the gonad is still an undifferentiated primordium, concomitant with the activation of amh and cyp19a1a, testis and ovary marker genes, respectively, in males and females. The Y-linked fshr allele, which included 24 nonsynonymous variants and showed a highly divergent 3D protein structure, was overexpressed in males compared to the X-linked allele at all stages of gonadal differentiation. We hypothesize a mechanism hampering the action of the follicle stimulating hormone driving the undifferentiated gonad toward testis. 相似文献
9.
Tipparat Hongpattarakere Aran H-Kittikun 《World journal of microbiology & biotechnology》1995,11(6):607-609
Schwanniomyces castellii B5285 grew faster and produced greater biomass and higher protein yield than either S. alluvius ATCC 26074 or S. alluvius 81Y when these amylolytic yeasts were grown with 2% (w/v) cassava starch as sole C source. With 0.5% (w/v) glutamate as N source, S. castellii reached 7.12 g cell dry mass/l, with a protein yield of 6.4 g/100 g starch. The optimal agitation speed, aeration rate and pH for growth of this yeast in a fermenter were 400 rev/min, 1.67 vol./vol.min. and 5.0, respectively. Tween 80 at 0.1% increased cell dry mass to 8.90 g/l, cell yield to 44 g/100 g starch and protein yield to 7.4 g/100 g starch.The authors are with the Department of industrial Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai 90110, Thailand 相似文献
10.