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461.
Molecular evolution of bacteriophages: evidence of selection against the recognition sites of host restriction enzymes 总被引:12,自引:0,他引:12
Restriction enzymes produced by bacteria serve as a defense against
invading bacteriophages, and so phages without other protection would be
expected to undergo selection to eliminate recognition sites for these
enzymes from their genomes. The observed frequencies of all restriction
sites in the genomes of all completely sequenced DNA phages (T7, lambda,
phi X174, G4, M13, f1, fd, and IKe) have been compared to expected
frequencies derived from trinucleotide frequencies. Attention was focused
on 6-base palindromes since they comprise the typical recognition sites for
type II restriction enzymes. All of these coliphages, with the exception of
lambda and G4, exhibit significant avoidance of the particular sequences
that are enterobacterial restriction sites. As expected, the sequenced
fraction of the genome of phi 29, a Bacillus subtilis phage, lacks Bacillus
restriction sites. By contrast, the RNA phage MS2, several viruses that
infect eukaryotes (EBV, adenovirus, papilloma, and SV40), and three
mitochondrial genomes (human, mouse, and cow) were found not to lack
restriction sites. Because the particular palindromes avoided correspond
closely with the recognition sites for host enzymes and because other
viruses and small genomes do not show this avoidance, it is concluded that
the effect indeed results from natural selection.
相似文献
462.
Alessandra Ferreira Dales Nava Laury Cullen Jr Dênis Aléssio Sana Marcello Schiavo Nardi José Domingues Ramos Filho Thiago Ferraz Lima Kauê Cachuba Abreu Fernando Ferreira 《EcoHealth》2008,5(4):513-518
Serum samples from 19 jaguars (Panthera onca), nine pumas (Puma concolor), and two ocelots (Leopardus pardalis) were collected between January 1999 and March of 2005 and tested for presence of canine distemper virus (CDV). All cats
were free-ranging animals living in two protected areas in the Brazilian Atlantic Forest. In addition, 111 domestic dogs from
nearby areas were sampled for CDV. Our results show the first evidence of CDV exposure in Brazilian free-ranging felids. From
the 30 samples analyzed, six jaguars and one puma were tested seropositive for CDV. All seropositive large felids were from
Ivinhema State Park, resulting in 31.5% of the sampled jaguars or 60% of the total jaguar population in Ivinhema State Park,
and 11.28% of the sampled pumas. From the total 111 domestic dogs sampled, 45 were tested seropositive for CDV. At Morro do
Diabo State Park, 34.6% of the dogs sampled were positive for CDV, and 100% at Ivinhema State Park. Canine distemper virus
in wild felids seems to be related with home range use and in close association with domestic dogs living in nearby areas. 相似文献
463.
Tiago Benedito dos Santos Viviane Y. Baba Luiz Gonzaga Esteves Vieira Luiz Filipe Protasio Pereira Douglas Silva Domingues 《Physiology and Molecular Biology of Plants》2021,27(2):203
The high costs of N fertilizers in the coffee production emphasizes the need to optimize fertilization practices and improve nitrogen use efficiency. Urea is widespread in nature, characterizing itself as a significant source of nitrogen for the growth and development of several organisms. Thus, the characterization of genes involved in urea transport in coffee plants is an important research topic for the sustainable production of this valuable cash crop. In the current study, we evaluated the expression of the DUR3 gene under abiotic and biotic stresses in coffee plants. Here, we show that the expression of a high-affinity urea transporter gene (CaDUR3) was up-regulated by N starvation in leaves and roots of two out of three C. arabica cultivars examined. Moreover, the CaDUR3 gene was differentially expressed in coffee plants under different abiotic and biotic stresses. In plants of cv. IAPAR59, CaDUR3 showed an increased expression in leaves after exposure to water deficit and heat stress, while it was downregulated in plants under salinity. Upon infection with H. vastatrix (coffee rust), the CaDUR3 was markedly up-regulated at the beginning of the infection process in the disease susceptible Catuaí Vermelho 99 in comparison with the resistant cultivar. These results indicate that besides urea acquisition and N-remobilization, CaDUR3 gene may be closely involved in the response to various stresses. 相似文献
464.
David G. McGrath Fabio de Castro Celia Futemma Benedito Domingues de Amaral Juliana Calabria 《Human ecology: an interdisciplinary journal》1993,21(2):167-195
Traditionally, the ribeirinhoeconomy has been based on strategies of multiple resource use including agriculture, fishing, and small-scale stock raising. In the last two decades though, ribeirinhostrategies of resource management have undergone major changes due to the decline of jute production (the principal cash crop), and the intensification of the commercial fisheries. As a result of these trends, there has been a shift of ribeirinholabor from agriculture to commercial fishing. Today, the diversity which once characterized ribeirinhosubsistence strategies is disappearing, and fishing has become the primary economic activity for the great majority of varzeafamilies. As pressure on varzeafisheries has increased, ribeirinhocommunities have attempted to assert control over local varzealakes and exclude fishermen from outside the community. In a number of cases, ribeirinhocommunities have closed lakes to outsiders and established informal lake reserves under local community management. These lake reserves are a promising strategy for managing lake fisheries on a sustainable basis. 相似文献
465.
Alessandro Domingues Heubel Ariane Aparecida Viana Stephanie Nogueira Linares Vanessa Teixeira do Amaral Nathany Souza Schafauser Gustavo Yudi Orikassa de Oliveira Paula Camila Ramírez Bruno Martinelli Tiago da Silva Alexandre Audrey Borghi-Silva Emmanuel Gomes Ciolac Renata Gonalves Mendes 《Obesity (Silver Spring, Md.)》2022,30(1):165-171
466.
João P. Monteiro Elisabete Maciel Rita Maia Andreia T. Pereira Ricardo Calado Pedro Domingues Tânia Melo Catarina Eira M. Rosário Domingues 《Marine Mammal Science》2021,37(4):1406-1427
The maintenance of a tightly regulated heart lipidome is a general hallmark of mammal health. However, in the case of cetaceans, heart tissue lipid composition remains obscure. This work represents a first in-depth state-of-the-art characterization of the lipid content of small cetacean hearts, namely those of Delphinus delphis, Phocoena phocoena, and Stenella coeruleoalba. Phospholipid classes identified were similar to those found in terrestrial mammals. Regarding fatty acid profiles, they revealed a much higher n-3 fatty acid content than that reported for terrestrial counterparts. Phospholipidome characterization allowed identification of 198 lipid species, including phospholipids, lysophospholipids, and sphingomyelins, generally characterized by a high content of species with esterified n-3 fatty acids. The cardiac lipid profile of the three cetacean species is similar in terms of lipid classes, fatty acids, and even molecular lipid species present. However, quantitative differences suggest a divergence of S. coeruleoalba from the other species in terms of fatty acid and phospholipid profile. The identified differences regarding terrestrial counterparts will contribute to better understanding the details of small cetacean cardiac physiology. Moreover, the characterization of cardiac phospholipidome may represent an opportunity to establish lipidomic-based practical tools to reliably and reproducibly assess small cetacean health population status by remote sampling. 相似文献
467.
Lucília Domingues António A. Vicente Nelson Lima José A. Teixeira 《Biotechnology and Bioprocess Engineering》2000,5(4):288-305
A review on the main aspects associated with yeast flocculation and its application in biotechnological processes is presented.
This subject is addressed following three main aspects—the basics of yeast flocculation, the development of “new” flocculating
yeast strains and bioreactor development. In what concerns the basics of yeast flocculation, the state of the art on the most
relevant aspects of mechanism, physiology and genetics of yeast flocculation is reported. The construction of flocculating
yeast strains includes not only the recombinant constitutive flocculent brewer's yeast, but also recombinant flocculent yeast
for lactose metabolisation and ethanol production. Furthermore, recent work on the heterologous β-galactosidase production
using a recombinant flocculentSaccharomyces cerevisiae is considered. As bioreactors using flocculating yeast cells have particular properties, mainly associated with a high solid
phase hold-up, a section dedicated to its operation is presented. Aspects such as bioreactor productivity and culture stability
as well as bioreactor hydrodynamics and mass transfer properties of flocculating cell cultures are considered. Finally, the
paper concludes describing some of the applications of high cell density flocculation bioreactors and discussing potential
new uses of these systems. 相似文献
468.
Morphological and chemical characterization of mineral concretions in the freshwater bivalve Anodonta cygnea (Unionidae)
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Mariana F. Hinzmann Manuel Lopes‐Lima Iulius Bobos Jorge Ferreira Bernardo Domingues Jorge Machado 《Journal of morphology》2015,276(1):65-76
The freshwater mussel Anodonta cygnea is commonly used as a model organism for biomineralization studies, its peculiar morphofunctional properties also make it an excellent environmental biomonitor. The first detailed on the calcareous concretions from gill and mantle tissue, as well as fluids of the freshwater bivalve A. cygnea, supported by histological, scanning, spectrometry, and spectroscopy analyses. Through these analyses, the morphology, structure, and chemical characterization of these biomineral concretions were accomplished. The concretions represent a high percentage of the dry weight of these organisms. In gill tissue, it can reach up to 50% of dry weight prior to reproductive maturity. Analysis of elemental composition of the tissue concretions showed the presence of calcium and phosphate, as main components, associated with other residual elements like iron, manganese, magnesium, and zinc. Concretions are arranged in concentric alternated layers of organic and inorganic matrix. The shape and size of the concretions vary substantially, from very small, less than 1 μm diameter with very regular round structure, found mainly in the mantle tissue, to more than 50 μm length with irregular globular clusters, found predominantly in the gills. The microstructural organization is of a hydroxyapatite polymorphism in the mantle, in contrast to the gills, which exhibit irregular structure and carbonated hydroxyapatite polymorphism. These differences are supported by higher contents of dinitrogen pentoxide, magnesium, and iron in the mantle concretions, but higher contents of manganese and zinc in the gills. Furthermore, the results indicate that the mineral concretion formation in A. cygnea is a hemocytes reaction to particle or toxic invasions. A second relevant role, concerns the close involvement of these microspherules on the adult and larval shell calcification. J. Morphol. 276:65–76, 2015. © 2014 Wiley Periodicals, Inc. 相似文献
469.
The reciprocal position of sexual organs in complementary floral morphs is central to our understanding of heterostyly. Reciprocity indices are used to quantify the spatial match between complementary sex organs, but previous indices fail to appropriately account for intra-population variation in sex organ positions. In this study, we examine how an increase in intra-population variation in sex organ heights affects reciprocity and consequently reproductive success. We formulated a reciprocity index that incorporates this variation and asked if estimates of reciprocity can predict reproductive success in naturally occurring heterostylous populations. We developed a reciprocity index that assumed pollen transfer success equalled one for a perfectly matched stigma–anther pair, and decreased to zero with increasing mismatch. We examined the relationship between intra-population variation in organ position and reciprocity, compared previously proposed indices using simulated populations and empirical data from natural populations, and tested the ability of the indices to predict reproductive success. We observed that when differences between mean complementary sex-organ heights are small, increasing intra-population variation in heights resulted in a decrease in reciprocity. However, when this difference is larger, reciprocity increased, reached a peak, and then decreased with increasing variation. Previous indices failed to capture this behavior. Seed set was positively related to reciprocity for our index. These results challenge the current understanding that increasing variation in sex-organ heights will always decrease reciprocity in heterostylous populations. This may help explain why heterostylous systems exhibit and tolerate high amounts of intra-population variation in sex organ heights. 相似文献
470.
R. R. Domingues A. F. de Amorim A. W. S. Hilsdorf 《Zeitschrift fur angewandte Ichthyologie》2013,29(4):738-742
Sharks of the genus Carcharhinus exhibit subtle morphological differences that are difficult to observe because of the common practice of head and fin removal, making species identification challenging. A total of 317 sharks, commonly called ‘cação‐baia’ (large individuals) or ‘machote’ (small size) in Brazil, were captured by the tuna fleet at the Santos and Guarujá fishery ports on the southeastern coast of Brazil and identified at the species level by multiplex PCR. The Internal Transcribed Spacer 2 region of ribosomal DNA was amplified using universal primers, and species‐specific primers were used for some of the Carcharhinus species. A total of 313 shark carcasses were directly identified by multiplex PCR. Four carcass samples did not amplify; therefore, the partial COI sequences were used to confirm their taxonomic identity. The results show that more than one species was being traded under the same commercial designation, including some Carcharhinus species that are under protection by federal legislation. Such species misidentification directly affects the long‐term sustainability of sharks. 相似文献