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Simultaneous saccharification and fermentation of straw to ethanol using the thermotolerant yeast strain Kluyveromyces marxianus imb3 总被引:1,自引:0,他引:1
The thermotolerant, ethanol-producing yeast strain Kluyveromyces marxianus IMB3 was grown at 45°C on media containing 2, 4 and 6 % (w/v) pulverized barley straw and supplemented with 2% (v/v) cellulase. Maximum ethanol concentrations produced were 2, 3 and 3.6g/l, respectively. When the pulverized straw was replaced by NaOH pretreated straw (at 2, 4 and 6% (w/v); based on original untreated straw), ethanol concentrations increased to maxima of 3.9, 8, and 12g/l, respectively. The ethanol yields amount to 20g ethanol from 100g of straw. 相似文献
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Evolution and phylogenetic information content of the ITS-1 region in the tiger beetle Cicindela dorsalis 总被引:6,自引:0,他引:6
Sequence divergence in the internal transcribed spacer region 1 (ITS-1) of
the ribosomal DNA locus was assessed in subspecies of the coastal North
American tiger beetle, Cicindela dorsalis. The spacer region was amplified
using the polymerase chain reaction and cloned for sequencing. Of a total
of 50 clones obtained from 12 specimens, 42 clones were different in at
least one nucleotide position. In a parsimony analysis of these sequences,
the main phylogenetic distinction was found to separate sequences from the
Gulf of Mexico and the Atlantic Ocean. Within these two assemblages
phylogenetic resolution was low, and the variation within individuals was
almost as high as the variation within the entire lineage. The pattern of
sequence variation suggests the existence of two forms of the ITS-1 that
are maintained on different chromosomes. Polymorphisms of limited
geographical distribution could be detected, and 41 additional clones were
partly sequenced, to assess the geographic distribution of these
polymorphisms in more detail. In a population aggregation analysis, the
geographic pattern of ITS-1 distribution was basically congruent with that
obtained in earlier studies from mitochondrial DNA in the same C. dorsalis
populations.
相似文献
54.
Hypothesis: For any one time and place a ‘functional signature’ can be derived for a sample of herbaceous vegetation in a way that concisely represents the balance between the different clusters of functional attributes that are present among component species. Methods: We developed a spreadsheet‐based tool for calculating functional signatures within the context of the C‐S‐R system of plant functional types. We used the tool to calculate and compare signatures for specimen British vegetation samples which differed in management regime and location in time. Conclusion: The integrative power of the ‘C‐S‐R signature’ is useful in comparative studies involving widely differing samples. Movements in the signature can be used to indicate degree of resistance, resilience, eutrophication and dereliction. Systems of plant functional types other than C‐S‐R might also be approached in this way. Availability: The tool can be downloaded free of charge from the first author's web pages or from the journal's electronic archive. 相似文献
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St John JA Braun EL Isberg SR Miles LG Chong AY Gongora J Dalzell P Moran C Bed'hom B Abzhanov A Burgess SC Cooksey AM Castoe TA Crawford NG Densmore LD Drew JC Edwards SV Faircloth BC Fujita MK Greenwold MJ Hoffmann FG Howard JM Iguchi T Janes DE Khan SY Kohno S de Koning AJ Lance SL McCarthy FM McCormack JE Merchant ME Peterson DG Pollock DD Pourmand N Raney BJ Roessler KA Sanford JR Sawyer RH Schmidt CJ Triplett EW Tuberville TD Venegas-Anaya M Howard JT Jarvis ED Guillette LJ Glenn TC 《Genome biology》2012,13(1):415-12
The International Crocodilian Genomes Working Group (ICGWG) will sequence and assemble the American alligator (Alligator mississippiensis), saltwater crocodile (Crocodylus porosus) and Indian gharial (Gavialis gangeticus) genomes. The status of these projects and our planned analyses are described. 相似文献
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Evolutionary relatedness of some primate models of Plasmodium 总被引:1,自引:0,他引:1
Primate--and, specifically, monkey--malaria infections are commonly used
for understanding the pathology of and immune response to the human disease
because they are thought to resemble most closely the host-parasite
relationship found in humans. Plasmodium cynomolgi is used extensively as a
model for the human parasite, P. vivax, and P. knowlesi is used primarily
as a model for the development of erythrocytic-stage vaccines. Both of
these simian parasites can naturally infect man, resulting in mildly
symptomatic episodes of the disease. The phylogenetic relationship between
these two simian parasites and previously characterized Plasmodium species,
including P. vivax, was examined by comparison of the asexually expressed
small- subunit ribosomal RNA genes. Our analysis confirmed that P. vivax is
most closely related to P. cynomolgi and that it remains an appropriate
model of the human pathogen. Furthermore, with P. knowlesi and P. fragile,
these two species form a group of closely related species, distant from
other Plasmodium species. What is considered to be the most ancient of the
human malaria pathogens, P. malariae, was also included in the analysis and
does not group at all with other simian or human parasites.
相似文献
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Sequence variation in the middle part of the small-subunit rRNA was studied
for representatives of the major groups in the family Cicindelidae
(Coleoptera). All taxa exhibited a much expanded segment in variable region
V4 compared to D. melanogaster. This expanded segment was not found in
other groups of beetles, including three taxa in the closely related
Carabidae. Secondary structure predictions indicate that the expanded
segment folds into a single stem-loop structure in all taxa. Despite its
structural conservation, the fragment differs strongly in primary sequence,
even between closely related sister taxa. Several features of these
sequences are consistent with slippage replication as the mechanism that
has generated this sequence variation: the level of internal sequence
repetition as measured by the relative simplicity factor (RSF), its
variation in length between close relatives, and the strong nucleotide bias
compared to the remainder of the gene. With few exceptions, there was also
a correlation between sequence length and the level of sequence repetition,
frequently interpreted as the result of slippage. Phylogenies inferred from
the expansion segment were not consistent with existing hypotheses from
other molecular data for the group. This indicates that DNA sequences in
this region are not homologous throughout the entire Cicindelidae, but it
leaves open the possibility that this expansion segment can be used for
phylogeny reconstruction within subgroups. The implications of a
phylogenetic approach to the understanding of slippage-like evolution are
discussed.
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58.
Background
An important component of sexual selection arises because females obtain viability benefits for their offspring from their mate choice. Females choosing extra-pair fertilization generally favor males with exaggerated secondary sexual characters, and extra-pair paternity increases the variance in male reproductive success. Furthermore, females are assumed to benefit from 'good genes' from extra-pair sires. How additive genetic variance in such viability genes is maintained despite strong directional selection remains an evolutionary enigma. We propose that sexual selection is associated with elevated mutation rates, changing the balance between mutation and selection, thereby increasing variance in fitness and hence the benefits to be obtained from good genes sexual selection. Two hypotheses may account for such elevated mutation: (1) Increased sperm production associated with sperm competition may increase mutation rate. (2) Mutator alleles increase mutation rates that are revealed by the expression of condition-dependent secondary sexual characters used by choosy females during their mate choice. M Petrie has independently developed the idea that mutator alleles may account for the maintenance of genetic variation in viability despite strong directional selection. 相似文献59.
Amalia Kallergi Enrique AsinGarcia Vitor AP Martins dos Santos Laurens Landeweerd 《EMBO reports》2021,22(1)
Biosafety is a major challenge for developing for synthetic organisms. An early focus on application and their context could assist with the design of appropriate genetic safeguards. Subject Categories: Synthetic Biology & Biotechnology, S&S: Economics & BusinessOne of the goals of synthetic biology is the development of robust chassis cells for their application in medicine, agriculture, and the food, chemical and environmental industries. These cells can be streamlined by removing undesirable features and can be augmented with desirable functionalities to design an optimized organism. In a direct analogy with a car chassis, they provide the frame for different modules or “plug‐in” regulatory networks, metabolic pathways, or safety elements. In an effort to ensure a safe microbial chassis upfront, safety measures are implemented as genetic safeguards to limit risks such as unwanted cellular proliferation or horizontal gene transfer. Examples of this technology include complex genetic circuits, sophisticated metabolic dependencies (auxotrophies), and altered genomes (Schmidt & de Lorenzo, 2016; Asin‐Garcia et al, 2020). Much like seat belts or airbags in cars, these built‐in measures increase the safety of the chassis and of any organisms derived from it. Indeed, when it comes to safety, synthetic biology can still learn from a century‐old technology such as cars about the significance of context for the development of biosafety technologies.Every car today has seat belts installed by default. Yet, seat belts were not always a standard component; in fact, they were not even designed for cars to begin with. The original 2‐point belts were first used in aviation and only slowly introduced for motorized vehicles. Only after some redesign, the now‐common 3‐point car seat belts would become the life‐saving equipment that they are today. A proper understanding of the context of their application was therefore one of the crucial factors for their success and wide adoption. Context matters: It provides meaning for and defines what a technological application is best suited for. What was true for seat belts may be also true for biosafety technologies such as genetic safeguards.
… when it comes to safety, synthetic biology can still learn from a century‐old technology such as cars about the significance of context for the development of biosafety technologies.Society has a much higher awareness of technology’s risks compared to the early days of cars. Society today requires that technological risks are anticipated and assessed before an innovation or its applications are widely deployed. In addition, society increasingly demands that research and innovation take into account societal needs and values. This has led to, among others, the Responsible Research and Innovation (RRI; von Schomberg, 2013) concept that has become prominent in European science policy. In a nutshell, RRI requires that innovative products and processes align with societal needs, expectations, and values in consultation with stakeholders. RRI and similar frameworks suggest that synthetic biology must anticipate and respond not only to risks, but also to societal views that frame its evaluation and risk assessment. 相似文献
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