Search results for "Gymnosperm"
showing 10 items of 10 documents
Disentangling temporal patterns in our perception of the fossil history of gymnosperms
2012
By taking gymnosperms as a case study, this article evaluates the perception of plant life history from the fossil record to test the biases associated with the time-dependent aspects of the taxonomy, following a stepwise modelling procedure based on two divergent sets of time units. The idea that the effects of the temporal component of paleobiological inference need to be evaluated to remove any possible bias in our interpretation and perception of plant evolution based on analyses of large-scale data sets is investigated. The results reveal important differences in our perception of the tempo of gymnosperm evolution and how it is biased in terms of time unit length due to the loss of inf…
Retrotranspozonu struktūra parastās priedes (Pinus sylvestris L.) genomā un to ekspresija
2014
ANOTĀCIJA Promocijas darbs izstrādāts Latvijas Valsts mežzinātnes institūtā „Silava”. Pētījuma mērķis bija identificēt aktīvos retrotranspozonus parastās priedes (Pinus sylvestris L.) genomā un raksturot to transkripcijas līmeni dažādu stresa veidu ietekmē kontrolētos apstākļos. Pētījumā izmantoti nespecifiskie retrotranspozonu marķieri balstīti uz augsti konservatīvām tRNS piesaistes vietām. Viena klona priežu rametus pakļāva dabā izplatītam karstuma stresam, kukaiņu invāzijai (priežu hermess (Pineus pini L.), kā arī mākslīgi izraisītai augu hormonu (abscīzskābes un salicilskābes) ietekmei. Darba rezultātā identificēti pārsvarā I klases mobīlo elementu pārstāvji, kā arī tos saturošie himēr…
Angiosperm to Gymnosperm host-plant switch entails shifts in microbiota of the Welwitschia bug, Probergrothius angolensis (Distant, 1902).
2019
The adaptation of herbivorous insects to new host plants is key to their evolutionary success in diverse environments. Many insects are associated with mutualistic gut bacteria that contribute to the host's nutrition and can thereby facilitate dietary switching in polyphagous insects. However, how gut microbial communities differ between populations of the same species that feed on different host plants remains poorly understood. Most species of Pyrrhocoridae (Hemiptera: Heteroptera) are specialist seed-feeders on plants in the family Malvaceae, although populations of one species, Probergrothius angolensis, have switched to the very distantly related Welwitschia mirabilis plant in the Nami…
The Norway spruce genome sequence and conifer genome evolution
2013
Conifers have dominated forests for more than 200 million years and are of huge ecological and economic importance. Here we present the draft assembly of the 20-gigabase genome of Norway spruce (Picea abies), the first available for any gymnosperm. The number of well-supported genes (28,354) is similar to the >100 times smaller genome of Arabidopsis thaliana, and there is no evidence of a recent whole-genome duplication in the gymnosperm lineage. Instead, the large genome size seems to result from the slow and steady accumulation of a diverse set of long-terminal repeat transposable elements, possibly owing to the lack of an efficient elimination mechanism. Comparative sequencing of Pinu…
Molecular characterization of a phosphoenolpyruvate carboxylase in the gymnosperm Picea abies (Norway spruce)
1996
Phosphoenolpyruvate carboxylase (PEPC) genes and cDNA sequences have so far been isolated from a broad range of angiosperm but not from gymnosperm species. We constructed a cDNA library from seedlings of Norway spruce (Picea abies) and identified cDNAs coding for PEPC. A full-length PEPC cDNA was sequenced. It consists of 3522 nucleotides and has an open reading frame (ORF) that encodes a polypeptide (963 amino acids) with a molecular mass of 109551. The deduced amino acid sequence revealed a higher similarity to the C3-form PEPC of angiosperm species (86-88%) than to the CAM and C4 forms (76-84%). The putative motif (Lys/Arg-X-X-Ser) for serine kinase, which is conserved in all angiosperm …
Molecular composition and chemotaxonomic aspects of Eocene amber from the Ameki Formation, Nigeria
2012
The molecular composition of fossil resin from the Eocene Ameki Formation, southern Nigeria has been analyzed by infrared spectroscopy, pyrolysis–gas chromatography–mass spectrometry and thermochemolysis gas chromatography–mass spectrometry to determine the structural class and botanical source of the resin. The pyrolysis products were dominated by bicyclic products derived from regular labdatriene structure and lacked succinic acid indicating Class Ib type amber. The biomarker compositions in the pyrolysates are dominated by sesquiterpenoids of the cadinane and bisabolane classes that are common constituents of higher plants and labdane type diterpenoids. The exclusive presence of labdane …
Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review.
2021
The discovery of telomeric repeats in interstitial regions of plant chromosomes (ITRs) through molecular cytogenetic techniques was achieved several decades ago. However, the information is scattered and has not been critically evaluated from an evolutionary perspective. Based on the analysis of currently available data, it is shown that ITRs are widespread in major evolutionary lineages sampled. However, their presence has been detected in only 45.6% of the analysed families, 26.7% of the sampled genera, and in 23.8% of the studied species. The number of ITR sites greatly varies among congeneric species and higher taxonomic units, and range from one to 72 signals. ITR signals mostly occurs…
Le site à ambre et plantes du Cénomanien de Neau (Mayenne, France)
2020
International audience; A new Cenomanian amber- and plant-bearing deposit has been discovered at Neau, in the Mayenne department (France). The Cenomanian fossiliferous lignites are located in karst filling in a substratum of Cambrian limestones. The amber corresponds mainly to tiny millimetric grains, devoid of arthropod inclusions, but rich in microorganisms, especially the sheated bacteria Leptotrichites resinatus , and containing pollen grains ( Classopollis ) and wood fibers (Araucariacae or Cheirolepidiaceae). The lignites provide abundant conifer and ginkgoale cuticle fragments ( Frenelopsis , Eretmophyllum ) and a lot of palynomorphs ( e.g. Gleicheniidites senonicu s, Cyathidites , D…
Terpenoid composition and chemotaxonomic aspects of Miocene amber from the Koroglu Mountains, Turkey
2014
Abstract A recently discovered fossil resin from Koroglu Mountain in Turkey has been analyzed by gas chromatography–mass spectrometry and pyrolysis gas chromatography–mass spectrometry to determine its structural class and botanical origin. The sesqui- and diterpenoids contained in the amber extract were used as chemosystematic markers when compared with terpenoids in extant conifers. The pyrolysis products were dominated by labdanoid derived bicyclic products together with succinic acid indicating Class Ia type amber. The biomarker compositions of the resin comprise mainly sesqui- and diterpenoids, and lack triterpenoids. This distribution suggests a gymnosperm, and more specifically a con…
Early evolutionary colocalization of the nuclear ribosomal 5S and 45S gene families in seed plants: evidence from the living fossil gymnosperm Ginkgo…
2012
In seed plants, the colocalization of the 5S loci within the intergenic spacer (IGS) of the nuclear 45S tandem units is restricted to the phylogenetically derived Asteraceae family. However, fluorescent in situ hybridization (FISH) colocalization of both multigene families has also been observed in other unrelated seed plant lineages. Previous work has identified colocalization of 45S and 5S loci in Ginkgo biloba using FISH, but these observations have not been confirmed recently by sequencing a 1.8 kb IGS. In this work, we report the presence of the 45S–5S linkage in G. biloba, suggesting that in seed plants the molecular events leading to the restructuring of the ribosomal loci are much o…