Search results for "Obligate"
showing 10 items of 80 documents
Metabolic stasis in an ancient symbiosis: genome-scale metabolic networks from two Blattabacterium cuenoti strains, primary endosymbionts of cockroac…
2012
Abstract Background Cockroaches are terrestrial insects that strikingly eliminate waste nitrogen as ammonia instead of uric acid. Blattabacterium cuenoti (Mercier 1906) strains Bge and Pam are the obligate primary endosymbionts of the cockroaches Blattella germanica and Periplaneta americana, respectively. The genomes of both bacterial endosymbionts have recently been sequenced, making possible a genome-scale constraint-based reconstruction of their metabolic networks. The mathematical expression of a metabolic network and the subsequent quantitative studies of phenotypic features by Flux Balance Analysis (FBA) represent an efficient functional approach to these uncultivable bacteria. Resul…
Geographic distribution and seasonal variation of mitochondrial DNA haplotypes in the aphidRhopalosiphum padi(Hemiptera: Aphididae)
1997
AbstractThis study examines the spatial and seasonal patterning of mitochondrial DNA diversity in French populations of the bird cherry-oat aphid,Rhopalosiphum padi(Linnaeus), on both its primary and secondary hosts. Our results confirm the presence of two major mitochondrial lineages that are generally associated with the breeding system variation (cyclic and obligate parthenogenesis) shown by this species. The strength of this relationship varies regionally, being most evident in the south and west. Cyclically parthenogenetic populations show no significant regional or seasonal genetic divergence reflecting high levels of gene flow, possibly promoted by their obligate host-alternation. Ho…
Temnothorax pilagens sp. n. – a new slave-making species of the tribe Formicoxenini from North America (Hymenoptera, Formicidae)
2014
A new species of the ant genus Temnothorax Forel, 1890 – Temnothorax pilagens sp. n. is described from eastern North America. T. pilagens sp. n. is an obligate slave-making ant with two known hosts: T. longispinosus (Roger, 1863) and T. ambiguus (Emery, 1895). A differential diagnosis against Temnothorax duloticus (Wesson, 1937), the other dulotic congener from the Nearctic, is presented and a biological characteristics of the new species is given.
Genomic Changes in Bacteria: From Free-Living to Endosymbiotic Life
2007
Symbiosis is the association between two or more distinct organisms during at least one part of their lifecycle. Although this term is sometimes used in a narrower sense, it includes for most authors a set of different situations such as mutualism, parasitism and commensalism. Mutualism is defined as an association in which both partners derive benefit from living together. Parasitism is an association in which one of the partners benefits, while the other is harmed. Finally, commensalism is an association in which one of the two members benefits while the other is neither harmed nor obtains an advantage. In most cases, the association is established between a pluricellular eukaryote and a …
Tradeoffs in the evolution of plant farming by ants
2020
Diverse forms of cultivation have evolved across the tree of life. Efficient farming requires that the farmer deciphers and actively promotes conditions that increase crop yield. For plant cultivation, this can include evaluating tradeoffs among light, nutrients, and protection against herbivores. It is not understood if, or how, nonhuman farmers evaluate local conditions to increase payoffs. Here, we address this question using an obligate farming mutualism between the ant Philidris nagasau and epiphytic plants in the genus Squamellaria that are cultivated for their nesting sites and floral rewards. We focused on the ants' active fertilization of their crops and their protection against he…
Sex Loss in Monogonont Rotifers
2009
Monogonont rotifers are small, aquatic invertebrates capable of asexual and sexual reproduction. Sexual reproduction is required to produce diapausing eggs, which are able to survive adverse periods that typically occur every year. Their cyclically parthenogenetic life-cycle is believed to retain the advantages of recombination while minimizing the cost of sex. However, this life cycle is also thought to be unstable due to periodic loss of sexual reproduction by directional selection. Explaining the evolutionary dynamics of the monogonont rotifer life cycle is important for understanding how cyclical parthenogenesis is maintained, and for comparing monogononts with their close relatives, th…
Arbuscular mycorrhiza - studies on the geosiphon symbiosis lead to the characterization of the first glomeromycotan sugar transporter
2007
Article Addendum ; International audience; The intimate arbuscular mycorrhiza (AM) association between roots and obligate symbiotic Glomeromycota (‘AM fungi’) ‘feeds’ about 80% of land plants. AM forming fungi supply land plants with inorganic nutrients and have an enormous impact on terrestrial ecosystems. In return, AM fungi obtain up to 20% of the plant‑fixed CO2, putatively as monosaccharides. In a recent work we have reported the characterization of the first glomeromycotan monosaccharide transporter, GpMST1, and its gene sequence. We discuss that AM fungi might take up sugars deriving from plant cell‑wall material. The GpMST1 sequence delivers valuable data for the isolation of orthol…
Evolutionary dynamics of ‘the’ bdelloid and monogonont rotifer life-history patterns
2006
Substantial differences in both life-table characteristics and reproductive patterns distinguish bdelloid from monogonont rotifers. Bdelloids reproduce only asexually, whereas most monogononts are cyclical parthenogens. We explore some of the adaptive consequences of these life-history differences using a computer model to simulate the evolutionary acquisition of new beneficial mutations. A one-locus mutation-selection regime based on the life-history characteristics of bdelloids indicates that asexuals can maintain higher levels of both allelic and genotypic diversity over a longer time period than obligate sexuals. These results are produced by differences in the magnitude of random genet…
Chaperoning the <em>Mononegavirales</em>: Current Knowledge and Future Directions
2018
The order Mononegavirales harbors numerous viruses of significant relevance for human health, including both established and emerging infections. Currently, vaccines are only available for a small subset of these viruses and antiviral therapies remain limited. Being obligate cellular parasites, viruses must utilize the cellular machinery for their replication and spread. Therefore, targeting cellular pathways used by viruses can provide novel therapeutic approaches. One of the key challenges confronted by both hosts and viruses alike is the successful folding and maturation of proteins. In cells, this task is faced by cellular molecular chaperones, a group of conserved and abundant proteins…
Interaction of a host plant and its holoparasite: effects of previous selection by the parasite
2001
If parasites decrease the fitness of their hosts one could expect selection for host traits (e.g. resistance and tolerance) that decrease the negative effects of parasitic infection. To study selection caused by parasitism, we used a novel study system: we grew host plants (Urtica dioica) that originated from previously parasitized and unparasitized natural populations (four of each) with or without a holoparasitic plant (Cuscuta europaea). Infectivity of the parasite (i.e. qualitative resistance of the host) did not differ between the two host types. Parasites grown with hosts from parasitized populations had lower performance than parasites grown with hosts from unparasitized populations,…