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41.
42.
High rate of DNA loss in the Drosophila melanogaster and Drosophila virilis species groups 总被引:6,自引:3,他引:3
We recently proposed that patterns of evolution of non-LTR
retrotransposable elements can be used to study patterns of spontaneous
mutation. Transposition of non-LTR retrotransposable elements commonly
results in creation of 5' truncated, "dead-on-arrival" copies. These
inactive copies are effectively pseudogenes and, according to the neutral
theory, their molecular evolution ought to reflect rates and patterns of
spontaneous mutation. Maximum parsimony can be used to separate the
evolution of active lineages of a non-LTR element from the fate of the
"dead-on-arrival" insertions and to directly assess the relative
frequencies of different types of spontaneous mutations. We applied this
approach using a non-LTR element, Helena, in the Drosophila virilis group
and have demonstrated a surprisingly high incidence of large deletions and
the virtual absence of insertions. Based on these results, we suggested
that Drosophila in general may exhibit a high rate of spontaneous large
deletions and have hypothesized that such a high rate of DNA loss may help
to explain the puzzling dearth of bona fide pseudogenes in Drosophila. We
also speculated that variation in the rate of spontaneous deletion may
contribute to the divergence of genome size in different taxa by affecting
the amount of superfluous "junk" DNA such as, for example, pseudogenes or
long introns. In this paper, we extend our analysis to the D. melanogaster
subgroup, which last shared a common ancestor with the D. virilis group
approximately 40 MYA. In a different region of the same transposable
element, Helena, we demonstrate that inactive copies accumulate deletions
in species of the D. melanogaster subgroup at a rate very similar to that
of the D. virilis group. These results strongly suggest that the high rate
of DNA loss is a general feature of Drosophila and not a peculiar property
of a particular stretch of DNA in a particular species group.
相似文献
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Yan Liu Kathleen DeBoer David M. de Kretser Liza O’Donnell Anne E. O’Connor D. Jo Merriner Hidenobu Okuda Belinda Whittle David A. Jans Athina Efthymiadis Robert I. McLachlan Christopher J. Ormandy Chris C. Goodnow Duangporn Jamsai Moira K. O’Bryan 《PLoS genetics》2015,11(3)
Male infertility affects at least 5% of reproductive age males. The most common pathology is a complex presentation of decreased sperm output and abnormal sperm shape and motility referred to as oligoasthenoteratospermia (OAT). For the majority of OAT men a precise diagnosis cannot be provided. Here we demonstrate that leucine-rich repeats and guanylate kinase-domain containing isoform 1 (LRGUK-1) is required for multiple aspects of sperm assembly, including acrosome attachment, sperm head shaping and the initiation of the axoneme growth to form the core of the sperm tail. Specifically, LRGUK-1 is required for basal body attachment to the plasma membrane, the appropriate formation of the sub-distal appendages, the extension of axoneme microtubules and for microtubule movement and organisation within the manchette. Manchette dysfunction leads to abnormal sperm head shaping. Several of these functions may be achieved in association with the LRGUK-1 binding partner HOOK2. Collectively, these data establish LRGUK-1 as a major determinant of microtubule structure within the male germ line. 相似文献
47.
Claire Remacle Nadine Coosemans Frédéric Jans Marc Hanikenne Patrick Motte Pierre Cardol 《Plant molecular biology》2010,74(3):223-233
The COX3 gene encodes a core subunit of mitochondrial cytochrome c oxidase (complex IV) whereas the COX17 gene encodes a chaperone delivering copper to the enzyme. Mutants of these two genes were isolated by RNA interference in
the microalga Chlamydomonas. The COX3 mRNA was completely lacking in the cox3-RNAi mutant and no activity and assembly of complex IV were detected. The cox17-RNAi mutant presented a reduced level of COX17 mRNA, a reduced activity of the cytochrome c oxidase but no modification of its amount. The cox3-RNAi mutant had only 40% of the wild-type rate of dark respiration which was cyanide-insensitive. The mutant presented a
60% decrease of H2O2 production in the dark compared to wild type, which probably accounts for a reduced electron leakage by respiratory complexes
III and IV. In contrast, the cox17-RNAi mutant showed no modification of respiration and of H2O2 production in the dark but a two to threefold increase of H2O2 in the light compared to wild type and the cox3-RNAi mutant. The cox17-RNAi mutant was more sensitive to cadmium than the wild-type and cox3-RNAi strains. This suggested that besides its role in complex IV assembly, Cox17 could have additional functions in the cell
such as metal detoxification or Reactive Oxygen Species protection or signaling. Concerning Cox3, its role in Chlamydomonas complex IV is similar to that of other eukaryotes although this subunit is encoded in the nuclear genome in the alga contrary
to the situation found in all other organisms. 相似文献
48.
Tove Jansén Dominic Kurian Wuttinun Raksajit Steve York Michael L. Summers Pirkko Mäenpää 《Acta Physiologiae Plantarum》2010,32(3):511-518
Cyanobacteria have a tremendous activity to adapt to environmental changes of their growth conditions. In this study, Synechocystis sp. PCC 6803 was used as a model organism to focus on the alternatives of cyanobacterial energy metabolism. Glucose oxidation
in Synechocystis sp. PCC6803 was studied by inactivation of slr1843, encoding glucose-6-phosphate dehydrogenase (G6PDH), the first enzyme
of the oxidative pentose phosphate pathway (OPPP). The resulting zwf strain was not capable of glucose supported heterotrophic growth. Growth under autotrophy and under mixotrophy was similar
to that of the wild-type strain, even though oxygen evolution and uptake rates of the mutant were decreased in the presence
of glucose. The organic acids citrate and succinate supported photoheterotrophic growth of both WT and zwf. Proteome analysis of soluble and membrane fractions allowed identification of four growth condition-dependent proteins,
pentose-5-phosphate 3-epimerase (slr1622), inorganic pyrophosphatase (sll0807), hypothetical protein (slr2032) and ammonium/methylammonium
permease (sll0108) revealing details of maintenance of the cellular carbon/nitrogen/phosphate balance under different modes
of growth. 相似文献
49.
LEANDRO AMBRÓSIO CAMPOS HÉLIO RICARDO DA SILVA ANTONIO SEBBEN 《Biological journal of the Linnean Society. Linnean Society of London》2010,99(4):752-767
We describe the extra bony elements, plates, and osteoderms present in species of the genus Brachycephalus. Samples of eight species of Brachycephalus, including seven populations of Brachycephalus ephippium, were examined. The large additional elements associated with the skull (parotic plate) and vertebrae (vertebral and paravertebral plates) all comprise intramembranous bone, similar to that of the frontoparietal or nasal bones of the skull of most of frogs. Additionally, in the dermis of one unnamed species, we discovered and described true osteoderms. We discuss the morphological nature and diversity of theses elements and their importance as evidence of phylogenetic relationship within Brachycephalus. In summary, three distinct conditions of extra bony elements occur in the genus Brachycephalus: (1) bony plates may be present or absent in species of the genus; (2) a few, small bony plates may be developed and these may be represented by (a) paravertebral plates small and restricted to the distal ends of the transverse processes of the presacral IV, (b) parotic plates small and not covering the tops of the squamosals, and (c) ornamented spinal plates on all vertebrae; and (3) well‐developed bony plates may be present as (a) paravertebral plates forming a ‘bone‐shield’ on the dorsal surface of the trunk, ornamented, and visible through the integument, (b) parotic plates covering the tops of the squamosals, and (c) spinal plates associated with all vertebrae, and ornamented on vertebrate I–VI. Although the phenomenon of miniaturization may be associated with the appearance of new elements in at least some of the species in the genus, the traditional rule may not be universally applicable. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 752–767. 相似文献
50.
PATRICIA FERNANDES NERES VERÔNICA GOMES DA FONSECA‐GENEVOIS RODRIGO AUGUSTO TORRES MARIANA DA FONSECA CAVALCANTI FRANCISCO JOSÉ VICTOR DE CASTRO NEYVAN RENATO RODRIGUES DA SILVA TANIA TASSINARI RIEGER WILFRIDA DECRAEMER 《Zoological Journal of the Linnean Society》2010,158(1):1-15
A new species of Daptonema is described based upon morphological characters and 18S rRNA sequence. Daptonema matrona sp. nov. was collected in Pina Basin (north‐eastern Brazil). It differs from all other species of the genus by the presence of reduced cephalic setae and straight spicules. These features require an adaptation of the generic diagnosis. Moreover, the females are characterized by intra‐uterine development of the offspring, considered herein as their major autapomorphic feature. Molecular systematic analyses supported Daptonema matrona sp. nov. as a distinct genetic and evolutionary lineage. The data also indicate hypotheses of taxonomic synonymies amongst some related taxa from Xyalidae as well as the paraphyly of Daptonema. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 1–15. 相似文献