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71.
Wagner Vital Gustavo Lazzaro Rezende Leonardo Abreu Jorge Moraes Francisco JA Lemos Itabajara da Silva VazJr Carlos Logullo 《BMC developmental biology》2010,10(1):25
Background
The mosquito A. aegypti is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of A. aegypty life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during A. aegypti embryogenesis are unknown. 相似文献72.
Nick Fotheringham 《Journal of experimental marine biology and ecology》1976,23(3):299-305
Growth rates of the hermit crabs Pagurus longicarpus Say and P. pollicaris Say maintained in preferred shells and in shells smaller than the preferred size have been compared. Changes in wet weight, shield length, and duration of the molt cycle were determined. Crabs in preferred shells grew significantly faster than those in small shells. P. pollicaris molted at approximately the same rate in both cases but grew more each molt in preferred shells. Von Bertalanffy growth curves were fitted to changes in shield length among crabs in preferred shells. These curves indicate that P. longicarpus may mature four months after settling from the plankton and reach its asymptotic size within the next eight months while P. pollicaris also matures four months after leaving the plankton but does not reach its asymptotic size for approximately three years. The rapid growth of P. longicarpus may enable it to preempt shells which are required for the successful brooding of a large clutch before these shells are required by more aggressive competitors, such as P. pollicaris and Clibanarius vittatus. 相似文献
73.
Sandra Abad Jozef Nahalka Gabriele Bergler S Alison Arnold Robert Speight Ian Fotheringham Bernd Nidetzky Anton Glieder 《Microbial cell factories》2010,9(1):24
Background
Trigonopsis variabilis D -amino acid oxidase (Tv DAO) is a well characterized enzyme used for cephalosporin C conversion on industrial scale. However, the demands on the enzyme with respect to activity, operational stability and costs also vary with the field of application. Processes that use the soluble enzyme suffer from fast inactivation of Tv DAO while immobilized oxidase preparations raise issues related to expensive carriers and catalyst efficiency. Therefore, oxidase preparations that are more robust and active than those currently available would enable a much broader range of economically viable applications of this enzyme in fine chemical syntheses. A multi-step engineering approach was chosen here to develop a robust and highly active Pichia pastoris Tv DAO whole-cell biocatalyst. 相似文献74.
In order to reconstruct phylogenetic trees from extremely dissimilar
sequences it is necessary to estimate accurately the extent of sequence
divergence. In this paper a new method of sequence analysis, Markov triple
analysis, is developed for determining the relative frequencies of
nucleotide substitutions within the three branches of a three-taxon
dendrogram. Assuming that nucleotide sites are independently and
identically distributed and assuming a Markov model for nucleotide (or
protein) evolution, it is shown that the unique Markov matrices can be
reconstructed given only the joint probability distribution relating three
taxa. (In the much simpler case involving only two taxa and two character
states, Markov matrices can also be reconstructed, provided symmetry
assumptions are placed on the elements of the matrices.) The method is
illustrated using sequence data from the combined first and second codon
positions derived from complete human, mouse, and cow mitochondrial
sequences.
相似文献
75.
J Nelms R M Edwards J Warwick I Fotheringham 《Applied and environmental microbiology》1992,58(8):2592-2598
The bifunctional enzyme chorismate mutase/prephenate dehydratase (EC 5.4.99.5/4.2.1.51), which is encoded by the pheA gene of Escherichia coli K-12, is subject to strong feedback inhibition by L-phenylalanine. Inhibition of the prephenate dehydratase activity is almost complete at concentrations of L-phenylalanine greater than 1 mM. The pheA gene was cloned, and the promoter region was modified to enable constitutive expression of the gene on plasmid pJN302. As a preliminary to sequence analysis, a small DNA insertion at codon 338 of the pheA gene unexpectedly resulted in a partial loss of prephenate dehydratase feedback inhibition. Four other mutations in the pheA gene were identified following nitrous acid treatment of pJN302 and selection of E. coli transformants that were resistant to the toxic phenylalanine analog beta-2-thienylalanine. Each of the four mutations was located within codons 304 to 310 of the pheA gene and generated either a substitution or an in-frame deletion. The mutations led to activation of both enzymatic activities at low phenylalanine concentrations, and three of the resulting enzyme variants displayed almost complete resistance to feedback inhibition of prephenate dehydratase by phenylalanine concentrations up to 200 mM. In all four cases the mutations mapped in a region of the enzyme that has not been implicated previously in feedback inhibition sensitivity of the enzyme. 相似文献
76.
PAWEŁ JAŁOSZYŃSKI 《Systematic Entomology》2012,37(3):448-477
Neotropical genera of Cephenniini characterized by an additional leg ‘segment’ (‘trochantellus’) are revised, and the following new taxa are described: Shyri gen.n. , Shyri pichincha sp.n. (type species of Shyri) (Ecuador), Shyri perversus sp.n. (Ecuador), Shyri quitu sp.n. (Ecuador), Shyri microphthalmus sp.n. (Ecuador), Monstrophennium gen.n. (type species: Cephennium spinicolle Schaufuss), Furcodes gen.n. , Furcodes apicalis sp.n. (type species of Furcodes) (Mexico), Furcodes tutule sp.n. (Honduras), Paracephennium pumilio sp.n. (Costa Rica), Pseudocephennium iwokramanum sp.n. (Guyana), Pseudocephennium trilineatum sp.n. (Guyana), Pseudocephennium araguanum sp.n. (Venezuela), Pseudocephennium maximum sp.n. (Venezuela), Pseudocephennium peruvianum sp.n. (Peru), Pseudocephennium cochabambanum sp.n. (Bolivia), Pseudocephennium saramaccanum sp.n. (Suriname) and Pseudocephennium brokopondonum sp.n. (Suriname). Pseudocephennium spinicolle (Schaufuss) is transferred to Monstrophennium. Cladistic analysis of characters from adult morphology of all genera of Cephenniini and a large outgroup sample from Cyrtoscydmini, Eutheiini, Scydmaenini, Clidicini and Mastigini strongly supported the monophyly of Cephenniini. However, only the Cephennomicrus group comprising nine genera was strongly supported as a monophyletic clade, while only weak support was found for the previously suggested Cephennodes group and Cephennium group. Two alternative hypotheses concerning the phylogeny of Cephenniini are put forward and discussed: (i) the Cephennium group is sister to all remaining Cephenniini; or (ii) the Cephennomicrus group is sister to all remaining Cephenniini. The Neotropical genera with ‘trochantellus’ form a well‐supported clade derived from the ancestral lineage of the Cephennodes group. 相似文献
77.
E C Castro JA Diaz GomezDe Ferreyra C R De Castro N D'Acosta C M De Fenos 《Biochemical and biophysical research communications》1973,50(2):337-343
There is a higher activity of ethyl morphine N-demethylase (EM-ase) and cytochrome P-450 (P-450) reductase as well as higher P-450 content in the smooth endoplasmic reticulum (SER) than in the rough endoplasmic reticulum (RER). The extent of the irreversible binding of the14C from14CCl4 to lipids and proteins, as well as the CCl4-induced destruction of P-450 is more intense in SER than in RER while the opposite was found for glucose 6-phosphatase (G6P-ase) destruction. CCl4-induced lipid peroxidation is as intense in SER as is in RER.14C from14CCl4 gets irreversibly bound to ribosomal proteins. 相似文献
78.
79.
80.
JA Kiernan 《Biotechnic & histochemistry》2004,79(5):203-210
Hexazonium pararosaniline is a valuable reagent that has been used in enzyme activity histochemistry for 50 years. It is an aqueous solution containing the tris-diazonium ion derived from pararosaniline, an aminotriarylmethane dye, and it contains an excess of nitrous acid that was not consumed in the diazotization reaction. Other investigators have found that immersion for 2 min in an acidic (pH 3.5) 0.0015 M hexazonium pararosaniline solution can protect cryostat sections of unfixed animal tissues from the deleterious effects of aqueous reagents such as buffered solutions used in immunohistochemistry, while preserving specific affinities for antibodies. In the present investigation hexazonium pararosaniline protected lymphoid tissue and striated muscle against the damaging effects of water or saline. The same protection was conferred on unfixed sections treated with dilute nitrous or hydrochloric acid in concentrations similar to those in hexazonium pararosaniline solutions. Model tissues (solutions, gels or films containing gelatin and/or bovine albumin) responded predictably to well known cross-linking (formaldehyde) or coagulant (mercuric chloride) fixatives. Hexazonium pararosaniline solutions prevented the dissolution of protein gels in water only after 9 or more days of contact, during which time considerable swelling occurred. It is concluded that there is no evidence for a “fixative” action of hexazonium pararosaniline. The protective effect on frozen sections of unfixed tissue is attributable probably to the low pH of the solution. 相似文献