scholarly journals Correction to: Caught in action: fine-scale plastome evolution in the parasitic plants of Cuscuta section Ceratophorae (Convolvulaceae)

2019 ◽  
Vol 101 (3) ◽  
pp. 341-341
Author(s):  
Arjan Banerjee ◽  
Saša Stefanović
Keyword(s):  
Parasitic Plants ◽  
Fine Scale ◽  
Plastome Evolution

scholarly journals Plastome Reduction in the Only Parasitic Gymnosperm Parasitaxus Is Due to Losses of Photosynthesis but Not Housekeeping Genes and Apparently Involves the Secondary Gain of a Large Inverted Repeat

2019 ◽  
Vol 11 (10) ◽  
pp. 2789-2796 ◽  
Author(s):  
Xiao-Jian Qu ◽  
Shou-Jin Fan ◽  
Susann Wicke ◽  
Ting-Shuang Yi
Keyword(s):  
Inverted Repeat ◽  
Chlorophyll Biosynthesis ◽  
Housekeeping Genes ◽  
Parasitic Plants ◽  
Structural Features ◽  
Regulation System ◽  
Biosynthesis Pathway ◽  
Plastid Genomes ◽  
Plastome Evolution ◽  
Selection For

Abstract Plastid genomes (plastomes) of parasitic plants undergo dramatic reductions as the need for photosynthesis relaxes. Here, we report the plastome of the only known heterotrophic gymnosperm Parasitaxus usta (Podocarpaceae). With 68 unique genes, of which 33 encode proteins, 31 tRNAs, and four rRNAs in a plastome of 85.3-kb length, Parasitaxus has both the smallest and the functionally least capable plastid genome of gymnosperms. Although the heterotroph retains chlorophyll, all genes for photosynthesis are physically or functionally lost, making photosynthetic energy gain impossible. The pseudogenization of the three plastome-encoded light-independent chlorophyll biosynthesis genes chlB, chlL, and chlN implies that Parasitaxus relies on either only the light-dependent chlorophyll biosynthesis pathway or another regulation system. Nesting within a group of gymnosperms known for the absence of the large inverted repeat regions (IRs), another unusual feature of the Parasitaxus plastome is the existence of a 9,256-bp long IR. Its short length and a gene composition that completely differs from those of IR-containing gymnosperms together suggest a regain of this critical, plastome structure-stabilizing feature. In sum, our findings highlight the particular path of lifestyle-associated reductive plastome evolution, where structural features might provide additional cues of a continued selection for plastome maintenance.

scholarly journals Reconstructing plastome evolution across the phylogenetic backbone of the parasitic plant genus Cuscuta (Convolvulaceae)

2020 ◽  
Vol 194 (4) ◽  
pp. 423-438
Author(s):  
Arjan Banerjee ◽  
Saša Stefanović
Keyword(s):  
Parasitic Plants ◽  
Closely Related Species ◽  
Sequence Composition ◽  
Genomic Changes ◽  
Photosynthetic Genes ◽  
Plastome Evolution ◽  
Composition And Structure ◽  
Parasitic Lifestyle ◽  
Photosynthesis Genes ◽  
Substantial Degree

Abstract Parasitic plants have evolved to have reduced or completely lost ability to conduct photosynthesis and are usually characterized by sweeping morphological, physiological and genomic changes. The plastid genome (or plastome) is highly conserved in autotrophic plants and houses many key photosynthesis genes. This molecule is thus a useful system for documenting the genomic effects of a loss of autotrophy. Cuscuta (dodders) represents one of 12 independent transitions to a parasitic lifestyle in angiosperms. This near-cosmopolitan genus contains > 200 obligate parasitic species circumscribed in four subgenera: Grammica, Pachystigma, Cuscuta and Monogynella. With respect to photosynthesis, Cuscuta is a heterogeneous group, containing both hemi- and holoparasitic members that are, respectively, partially or entirely reliant on parasitism to meet their carbon budget. Plastomes in this genus have been reported to show a substantial degree of diversification in terms of length and gene composition. Considered together with well-understood phylogenetic relationships, this genus presents an opportunity for fine-scale comparisons among closely related species of heterotrophic plants. This research documents changes in sequence composition and structure that occurred as these plants evolved along the trophic spectrum by using multiple whole-plastome assemblies from each of the four subgenera. By ‘triangulating’ the positions of genomic changes, we construct a step-by-s’tep model of plastome evolution across the phylogenetic backbone of Cuscuta and highlight the remarkable retention of most photosynthetic genes in these parasitic plants.

High Resolution Stereography of Complementary Freeze-Fracture Replicas Reveals the Presence of Depressions Opposite Membrane Associated Particles of Split Membranes

1971 ◽  
Vol 29 ◽  
pp. 442-443
Author(s):  
Russell L. Steere
Keyword(s):  
High Resolution ◽  
Cardiac Muscle ◽  
Electron Micrographs ◽  
Chromic Acid ◽  
Freeze Fracture ◽  
Distilled Water ◽  
Fine Scale ◽  
Acid Cleaning ◽  
Cleaning Solution

Complementary replicas have revealed the fact that the two common faces observed in electron micrographs of freeze-fracture and freeze-etch specimens are complementary to each other and are thus the new faces of a split membrane rather than the original inner and outer surfaces (1, 2 and personal observations). The big question raised by published electron micrographs is why do we not see depressions in the complementary face opposite membrane-associated particles? Reports have appeared indicating that some depressions do appear but complementarity on such a fine scale has yet to be shown.Dog cardiac muscle was perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (material furnished by Dr. Joaquim Sommer, Duke Univ., and VA Hospital, Durham, N.C.). Small strips were freeze-fractured in a Denton Vacuum DFE-2 Freeze-Etch Unit with complementary replica tooling. Replicas were cleaned in chromic acid cleaning solution, then washed in 4 changes of distilled water and mounted on opposite sides of the center wire of a Formvar-coated grid.

Anatomy and ultrastructure of haustoria in selected West Australian parasitic angiosperms

1990 ◽  
Vol 48 (3) ◽  
pp. 690-691
Author(s):  
John Kuo ◽  
John S. Pate
Keyword(s):  
Parasitic Plants ◽  
The Other ◽  
Nutrient Transfer ◽  
Direct Solution ◽  
Tracheary Elements ◽  
Solute Transfer ◽  
Glycol Methacrylate ◽  
Australian Species ◽  
Anatomy And Ultrastructure ◽  
Solution Transfer

Our understanding of nutrient transfer between host and flowering parasitic plants is usually based mainly on physiological concepts, with little information on haustorial structure related to function. The aim of this paper is to study the haustorial interface and possible pathways of water and solute transfer between a number of host and parasites.Haustorial tissues were fixed in glutaraldehyde and embedded in glycol methacrylate (LM), or fixed in glutaraldehyde then OsO4 and embedded in Spurr’s resin (TEM).Our study shows that lumen to lumen continuity occurs between tracheary elements of a host and four S.W. Australian species of aerial mistletoes (Fig. 1), and some root hemiparasites (Exocarpos spp. and Anthobolus foveolatus) (Fig. 2). On the other hand, haustorial interfaces of the root hemiparasites Olax phyllanthi and Santalum (2 species) are comprised mainly of parenchyma, as opposed to terminating tracheads or vessels, implying that direct solution transfer between partners via vessels or tracheary elements may be limited (Fig. 3).

Fine-scale taxonomic and temporal variability in the energy density of invertebrate prey of juvenile Chinook salmon Oncorhynchus tshawytscha

2020 ◽  
Vol 655 ◽  
pp. 185-198
Author(s):  
J Weil ◽  
WDP Duguid ◽  
F Juanes
Keyword(s):  
Energy Density ◽  
Chinook Salmon ◽  
Temporal Variability ◽  
Energy Content ◽  
Single Point ◽  
Single Species ◽  
Fine Scale ◽  
Temporal Differences ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Variation in the energy content of prey can drive the diet choice, growth and ultimate survival of consumers. In Pacific salmon species, obtaining sufficient energy for rapid growth during early marine residence is hypothesized to reduce the risk of size-selective mortality. In order to determine the energetic benefit of feeding choices for individuals, accurate estimates of energy density (ED) across prey groups are required. Frequently, a single species is assumed to be representative of a larger taxonomic group or related species. Further, single-point estimates are often assumed to be representative of a group across seasons, despite temporal variability. To test the validity of these practices, we sampled zooplankton prey of juvenile Chinook salmon to investigate fine-scale taxonomic and temporal differences in ED. Using a recently developed model to estimate the ED of organisms using percent ash-free dry weight, we compared energy content of several groups that are typically grouped together in growth studies. Decapod megalopae were more energy rich than zoeae and showed family-level variability in ED. Amphipods showed significant species-level variability in ED. Temporal differences were observed, but patterns were not consistent among groups. Bioenergetic model simulations showed that growth rate of juvenile Chinook salmon was almost identical when prey ED values were calculated on a fine scale or on a taxon-averaged coarse scale. However, single-species representative calculations of prey ED yielded highly variable output in growth depending on the representative species used. These results suggest that the latter approach may yield significantly biased results.

Fine-scale habitat partitioning facilitates sympatry between two octopus species in a shallow Florida lagoon

2019 ◽  
Vol 609 ◽  
pp. 151-161 ◽  
Author(s):  
CO Bennice ◽  
AP Rayburn ◽  
WR Brooks ◽  
RT Hanlon
Keyword(s):  
Habitat Partitioning ◽  
Fine Scale

Small pelagic fish responses to fine-scale oceanographic conditions: implications for the endangered African penguin

2017 ◽  
Vol 569 ◽  
pp. 187-203 ◽  
Author(s):  
AM McInnes ◽  
PG Ryan ◽  
M Lacerda ◽  
J Deshayes ◽  
WS Goschen ◽  
...  
Keyword(s):  
Pelagic Fish ◽  
Fine Scale ◽  
Small Pelagic Fish ◽  
African Penguin ◽  
Oceanographic Conditions
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