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1.
2.
Marcella Carcupino Anna Maria Fausto Maria Luisa Bernardino Ortega Marzio Zapparoli Massimo Mazzini 《Zoomorphology》1996,116(3):103-110
Spermatophore development and ultrastructure of the mature sperm of Craterostigmus tasmanianus were studied using light and electron microscopy. In C. tasmanianus, as in the Scolopendromorpha, the spermatophore develops within the vas deferens. The latter consists of three parts, each
with a different morphology. The first may be involved in guiding the sperm to roll up into typical ring-like structures,
while the other two, which show an evident secretory activity, secrete the acellular wall of the spermatophores. The ultrastructure
of mature spermatozoa showed that a very close similarity exists between Craterostigmomorpha and Lithobiomorpha, especially
regarding the organization of the connecting piece. Based on this similarity, we consider the Craterostigmomorpha together
with the Scolopendromorpha, Geophilomorpha and Lithobiomorpha (=Pleurostigmophora) to be the sister group of the Scutigeromorpha.
Accepted: 2 June 1996 相似文献
3.
The ATP-binding-cassette transmembrane transporters (ABC transporters)
known from vertebrates belong to four major subfamilies: (1) the P-
glycoproteins (Pgp); (2) the cystic fibrosis transmembrane conductance
regulators (CFTR); (3) the Tap proteins encoded with the major
histocompatibility complex of mammals; and (4) the peroxisomal membrane
proteins. Both Pgp and CFTR have a structure suggesting a past internal
gene duplication; a phylogenetic analysis indicated that these duplications
occurred independently, while an independent tandem gene duplication
occurred in the case of the Tap family. Both the Pgp and Tap proteins show
evidence of relationship to bacterial ABC transporters lacking internal
duplication, and both are significantly more closely related to the HlyB
and MsbA families of transporters from purple bacteria than they are to ABC
transporters from nonpurple bacteria. The simplest hypothesis to explain
this observation is that eukaryotic Pgp and Tap genes are descended from a
mitochondrial gene or genes that were subsequently translocated to the
nuclear genome. The Pgp genes of eukaryotes are characterized by a
remarkable degree of convergent evolution between the ATP-binding cassettes
of their N- terminal and C-terminal halves, whereas no such convergence is
seen between the two halves of CFTR genes or between the duplicated Tap
genes. Exon 13 of the CFTR gene, which encodes a putative regulatory domain
not found in other ABC transporters apart from CFTR, showed high levels of
both synonymous and nonsynonymous difference in comparisons among different
mammalian species, suggesting that this region is a mutational hot spot.
相似文献
4.
5.
X Xiao G Hintermann AL Demanin J Piret 《Journal of industrial microbiology & biotechnology》1996,16(4):261-262
Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis. 相似文献
6.
ERIC S. BONO PATRICK SMOLINSKI AL CASAGRANDA JUNDE XU 《Computer methods in biomechanics and biomedical engineering》2013,16(2):125-131
The Shear-slip Mesh Update Method (SSMUM) is being used in flow simulations involving large but regular displacements of one or more boundaries of the computational domain. We follow up the earlier discussion of the method with notes on practical implementation aspects. In order to establish a benchmark problem for this class of flow problems, we define and report results from a two-dimensional viscous flow around a rotating stirrer in a square chamber. The application potential of the method is demonstrated in the context of biomedical design problem, as we perform an analysis of blood flow in a centrifugal left ventricular assist device, or blood pump, which involves a rotating impeller in a non-axisymmetric housing. 相似文献
7.
A. D. da Matta A. M. R. Bernardino G. A. Romeiro M. R. P. de Oliveira M. C. B. V. de Souza V. F. Ferreira 《Nucleosides, nucleotides & nucleic acids》2013,32(4):889-898
Abstract Ribosylation reactions of previously silylated 3-carbethoxy-8-methyl-1,4-dihydro-4-oxoquinoline (6a) and 3-carbethoxy-6-methyl-1,4-dihydro-4-oxoquinoline (6b) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (7), under Lewis acid catalysis, were studied. The method using hexamethyldisilazane (HMDS)/trimethylchlorosilane (TMCS) mixture for silylation and anhydrous stannic chloride as catalyst for ribosylation failed to give any nucleoside product. On the other hand, the protected nucleoside 3-carbethoxy-6-methyl-1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-1,4-dihydro-4-oxoquinoline (8b) was obtained in good yields using bis(trimethylsilyl)trifluoroacetamide (BSTFA) containing 1% of TMCS and the same catalyst. Compound 8b was more easily isolated in higher yields with an improvement of the later method by replacing stannic chloride with trimethylsilyl trifluoromethanesulfonate (TMSOTf). De-O-benzoylation of 8b with methanolic sodium hydroxide solution afforded the free riboside 3-carbomethoxy-6-methyl-1-β-D-ribofuranosyl-1,4-dihydro-4-oxoquinoline (9b). The structures of the obtained products were confirmed by their LTV, MS, IR, 1H and 13C-NMR data. 相似文献
8.
Leticia Ramos de Arvelos Vanessa Custódio Afonso Rocha Gabriela Pereira Felix Cleine Chagas da Cunha Morun Bernardino Neto Mario da Silva Garrote Filho Conceição de Fátima Pinheiro Elmiro Santos Resende Nilson Penha-Silva 《The Journal of membrane biology》2013,246(3):231-242
The stability of the erythrocyte membrane, which is essential for the maintenance of cell functions, occurs in a critical region of fluidity, which depends largely on its composition and the composition and characteristics of the medium. As the composition of the erythrocyte membrane is influenced by several blood variables, the stability of the erythrocyte membrane must have relations with them. The present study aimed to evaluate, by bivariate and multivariate statistical analyses, the correlations and causal relationships between hematologic and biochemical variables and the stability of the erythrocyte membrane against the chaotropic action of ethanol. The validity of this type of analysis depends on the homogeneity of the population and on the variability of the studied parameters, conditions that can be filled by patients who undergo bariatric surgery by the technique of Roux-en-Y gastric bypass since they will suffer feeding restrictions that have great impact on their blood composition. Pathway analysis revealed that an increase in hemoglobin leads to decreased stability of the cell, probably through a process mediated by an increase in mean corpuscular volume. Furthermore, an increase in the mean corpuscular hemoglobin (MCH) leads to an increase in erythrocyte membrane stability, probably because higher values of MCH are associated with smaller quantities of red blood cells and a larger contact area between the cell membrane and ethanol present in the medium. 相似文献
9.
10.
Ignacio Pérez-Valero Alicia González-Baeza Miriam Estébanez María L. Montes-Ramírez Carmen Bayón Federico Pulido José I. Bernardino Francisco X. Zamora Susana Monge Francisco Gaya María Lagarde Rafael Rubio Asunción Hernando Francisco Arnalich José R. Arribas 《PloS one》2013,8(7)