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Ping Li Wei Guo Xin Mei Qiao Zhi Gang Liu Li Shen Qi Wei Wei 《Zeitschrift fur angewandte Ichthyologie》2019,35(1):192-201
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P. K. Gillingham B. Huntley W. E. Kunin C. D. Thomas 《Diversity & distributions》2012,18(10):990-1000
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S. Srisuwan D. Sihachakr J. Martín J. Valls A. Ressayre S. C. Brown S. Siljak‐Yakovlev 《Plant biology (Stuttgart, Germany)》2019,21(2):237-247
- Genome size evolution and its relationship with pollen grain size has been investigated in sweet potato (Ipomoea batatas), an economically important crop which is closely related to diploid and tetraploid species, assessing the nuclear DNA content of 22 accessions from five Ipomoea species, ten sweet potato varieties and two outgroup taxa.
- Nuclear DNA amounts were determined using flow cytometry. Pollen grains were studied using scanning and transmission electron microscopy.
- 2C DNA content of hexaploid I. batatas ranged between 3.12–3.29 pg; the mean monoploid genome size being 0.539 pg (527 Mbp), similar to the related diploid accessions. In tetraploid species I. trifida and I. tabascana, 2C DNA content was, respectively, 2.07 and 2.03 pg. In the diploid species closely related to sweet potato e.g. I. ×leucantha, I. tiliacea, I. trifida and I. triloba, 2C DNA content was 1.01–1.12 pg. However, two diploid outgroup species, I. setosa and I. purpurea, were clearly different from the other diploid species, with 2C of 1.47–1.49 pg; they also have larger chromosomes. The I. batatas genome presents 60.0% AT bases.
- DNA content and ploidy level were positively correlated within this complex. In I. batatas and the more closely related species I. trifida, the genome size and ploidy levels were correlated with pollen size. Our results allow us to propose alternative or complementary hypotheses to that currently proposed for the formation of hexaploid Ipomoea batatas.
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Michela Del Pasqua Marco Lezzi Margherita Licciano Adriana Giangrande 《Invertebrate Biology》2017,136(2):207-216
Branchiomma bairdi is a Caribbean fan worm introduced in several localities worldwide, including the Mediterranean Sea, where the species’ range has rapidly expanded. Reproduction in B. bairdi was previously investigated in both extra‐Mediterranean and Mediterranean areas, but no information is available on larval development and post‐larval growth. In the present article, we examined these features for a population from the Mar Grande of Taranto (Ionian Sea). The species is hermaphrodite, and fertilization occurs in situ. Mucus seems to play an important role in fertilization, and also in preserving eggs before fertilization. The trochophore stage develops within the mucus and after hatching, larvae swim for about 3 d before settlement. The trochophore showed a distinct prototroch and two red dorsolateral larval eyes. The pelagic stage takes only 96 h even though prototroch is maintained after settlement, disappearing at 5 d, when larvae showed three chaetigers and branchial crown consisted of four radioles. Some interesting observations concerning changes in the morphology of chaetae and in the number of uncini during growth are also reported, together with discussion of the development of stylodes, an important diagnostic feature in Branchiomma species identification. 相似文献
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Fabrizio Di Caprio Francesca Pagnanelli Rene H. Wijffels Douwe Van der Veen 《Journal of phycology》2018,54(2):187-197
Much of our current knowledge of microbial growth is obtained from studies at a population level. Driven by the realization that processes that operate within a population might influence a population's behavior, we sought to better understand Tetradesmus obliquus (formerly Scenedesmus obliquus ) physiology at the cellular level. In this work, an accurate pretreatment method to quantitatively obtain single cells of T. obliquus , a coenobia‐forming alga, is described. These single cells were examined by flow cytometry for triacylglycerol (TAG ), chlorophyll, and protein content, and their cell sizes were recorded by coulter counter. We quantified heterogeneity of size and TAG content at single‐cell level for a population of T. obliquus during a controlled standard batch cultivation. Unexpectedly, variability of TAG content per cell within the population increased throughout the batch run, up to 400 times in the final stage of the batch run, with values ranging from 0.25 to 99 pg · cell?1. Two subpopulations, classified as having low or high TAG content per cell, were identified. Cell size also increased during batch growth with average values from 36 to 70 μm3 · cell?1; yet cell size variability increased only up to 16 times. Cell size and cellular TAG content were not correlated at the single‐cell level. Our data show clearly that TAG production is affected by cell‐to‐cell variation, which suggests that its control and better understanding of the underlying processes may improve the productivity of T. obliquus for industrial processes such as biodiesel production. 相似文献
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The domestication syndrome comprises phenotypic changes that differentiate crops from their wild ancestors. We compared the genomic variation and phenotypic differentiation of the two putative domestication traits seed size and seed colour of the grain amaranth Amaranthus caudatus, which is an ancient crop of South America, and its two close wild relatives and putative ancestors A. hybridus and A. quitensis. Genotyping 119 accessions of the three species from the Andean region using genotyping by sequencing (GBS) resulted in 9485 SNPs that revealed a strong genetic differentiation of cultivated A. caudatus from its two relatives. A. quitensis and A. hybridus accessions did not cluster by their species assignment but formed mixed groups according to their geographic origin in Ecuador and Peru, respectively. A. caudatus had a higher genetic diversity than its close relatives and shared a high proportion of polymorphisms with their wild relatives consistent with the absence of a strong bottleneck or a high level of recent gene flow. Genome sizes and seed sizes were not significantly different between A. caudatus and its relatives, although a genetically distinct group of A. caudatus from Bolivia had significantly larger seeds. We conclude that despite a long history of human cultivation and selection for white grain colour, A. caudatus shows a weak genomic and phenotypic domestication syndrome and proposes that it is an incompletely domesticated crop species either because of weak selection or high levels of gene flow from its sympatric close undomesticated relatives that counteracted the fixation of key domestication traits. 相似文献
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Gilad Luria Nicholas Rutley Itay Lazar Jeffery F. Harper Gad Miller 《The Plant journal : for cell and molecular biology》2019,98(5):942-952
Sexual reproduction in flowering plants depends on the fitness of the male gametophyte during fertilization. Because pollen development is highly sensitive to hot and cold temperature extremes, reliable methods to evaluate pollen viability are important for research into improving reproductive heat stress (HS) tolerance. Here, we describe an approach to rapidly evaluate pollen viability using a reactive oxygen species (ROS) probe dichlorodihydrofluorescein diacetate (i.e. H2DCFDA‐staining) coupled with flow cytometry. In using flow cytometry to analyze mature pollen harvested from Arabidopsis and tomato flowers, we discovered that pollen distributed bimodally into ‘low‐ROS’ and ‘high‐ROS’ subpopulations. Pollen germination assays following fluorescence‐activated cell sorting revealed that the high‐ROS pollen germinated with a frequency that was 35‐fold higher than the low‐ROS pollen, supporting a model in which a significant fraction of a flower's pollen remains in a low metabolic or dormant state even after hydration. The ability to use flow cytometry to quantify ROS dynamics within a large pollen population was shown by dose‐dependent alterations in DCF‐fluorescence in response to oxidative stress or antioxidant treatments. HS treatments (35°C) increased ROS levels, which correlated with a ~60% reduction in pollen germination. These results demonstrate the potential of using flow cytometry‐based approaches to investigate metabolic changes during stress responses in pollen. 相似文献
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A study of nematodes associated with the large larch bark beetle Ips cembrae (Heer 1836) was carried out at three locations in the Czech Republic. The proportion of beetles infested by endoparasitic nematodes (representatives of genera Contortylenchus, Parasitylenchus, Cryptaphelenchus and Parasitorhabditis) ranged from 29.9 to 50.9%. Significant differences were determined in nematode infestation levels among locations, generations and sampling methods. No differences were found in infestation rates between males and females. The percentage of bark beetles with phoretic nematodes ranged from 18 to 42.9%. Phoretic nematodes directly found under elytra, on wings and between body segments of the bark beetles belong to the genus Micoletzkya. However, adults and juveniles of other two phoretic species Laimaphelenchus penardi and Bursaphelenchus sp. were found in the gallery frass of I. cembrae. Infestation by phoretic nematodes positively correlated with the presence of mites under elytra. 相似文献
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As a major driving element of the structure and function of arid and semiarid ecosystems, rainfall is the essential factor limiting plant biological processes. To clarify the characteristics of transpiration and responses to summer rainfall, sap flow density (Fd) of Pinus tabulaeformis and Hippophae rhamnoides was monitored using thermal dissipation probes. In addition, midday leaf water potential (ψm) and leaf stomatal conductance (Gs) were also analyzed to determine water use strategies. The results indicated that the diurnal variation in the normalized Fd values exhibited a single‐peak curve for P. tabulaeformis, while H. rhamnoides showed multiple peaks. The normalized Fd for P. tabulaeformis remained relatively stable regardless of rainfall events. However, there was also a significant increase in the normalized Fd for H. rhamnoides in response to rainfall in June and August (p < .05), although no significant differences were observed in July. The normalized Fd values for P. tabulaeformis and H. rhamnoides fitted well with the derived variable of transpiration, an integrated index calculated from the vapor pressure deficit and solar radiation (Rs), using an exponential saturation function. The differences in fitting coefficients suggested that H. rhamnoides showed more sensitivity to summer rainfall (p < .01) than P. tabulaeformis. Furthermore, during the study period, P. tabulaeformis reduced Gs as soil water decreased, maintaining a relatively constant ψm; while H. rhamnoides allowed large fluctuations in ψm to maintain Gs. Therefore, P. tabulaeformis and H. rhamnoides should be considered isohydric and anisohydric species, respectively. And more consideration should be taken for H. rhamnoides in the afforestation activities and the local plantation management under the context of the frequently seasonal drought in the loess hilly region. 相似文献
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Hans Petter Leinaas Marwa Jalal Tove M. Gabrielsen Dag O. Hessen 《Ecology and evolution》2016,6(16):5585-5595
The tendency of ectotherms to get larger in the cold (Bergmann clines) has potentially great implications for individual performance and food web dynamics. The mechanistic drivers of this trend are not well understood, however. One fundamental question is to which extent variation in body size is attributed to variation in cell size, which again is related to genome size. In this study, we analyzed body and genome size in four species of marine calanoid copepods, Calanus finmarchicus, C. glacialis, C. hyperboreus and Paraeuchaeta norvegica, with populations from both south Norwegian fjords and the High Arctic. The Calanus species showed typical interspecific Bergmann clines, and we assessed whether they also displayed similar intraspecific variations—and if correlation between genome size and body size differed between species. There were considerable inter‐ as well as intraspecific variations in body size and genome size, with the northernmost populations having the largest values of both variables within each species. Positive intraspecific relationships suggest a functional link between body and genome size, although its adaptiveness has not been settled. Impact of additional drivers like phylogeny or specific adaptations, however, was suggested by striking divergences in body size – genome size ratios among species. Thus, C. glacialis and C. hyperboreus, had fairly similar genome size despite very different body size, while P. norvegica, of similar body size as C. hyperboreus, had the largest genome sizes ever recorded from copepods. The inter‐ and intraspecific latitudinal body size clines suggest that climate change may have major impact on body size composition of keystone species in marine planktonic food webs. 相似文献
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Muhammad Ashfaq Muhammad Asif Zahid Iqbal Anjum Yusuf Zafar 《Molecular ecology resources》2013,13(4):573-582
Although two plastid regions have been adopted as the standard markers for plant DNA barcoding, their limited resolution has provoked the consideration of other gene regions, especially in taxonomically diverse genera. The genus Gossypium (cotton) includes eight diploid genome groups (A–G, and K) and five allotetraploid species which are difficult to discriminate morphologically. In this study, we tested the effectiveness of three widely used markers (matK, rbcL, and ITS2) in the discrimination of 20 diploid and five tetraploid species of cotton. Sequences were analysed locus‐wise and in combinations to determine the most effective strategy for species identification. Sequence recovery was high, ranging from 92% to 100% with mean pairwise interspecific distance highest for ITS2 (3.68%) and lowest for rbcL (0.43%). At a 0.5% threshold, the combination of matK+ITS2 produced the greatest number of species clusters. Based on ‘best match’ analysis, the combination of matK+ITS2 was best, while based on ‘all species barcodes’ analysis, ITS2 gave the highest percentage of correct species identifications (98.93%). The combination of sequences for all three markers produced the best resolved tree. The disparity index test based on matK+rbcL+ITS2 was significant (P < 0.05) for a higher number of species pairs than the individual gene sequences. Although all three barcodes separated the species with respect to their genome type, no single combination of barcodes could differentiate all the Gossypium species, and tetraploid species were particularly difficult. 相似文献
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Min Yue Zhang Tsz Kin Fung Fang Yuan Chen Chor Sang Chim 《Journal of cellular and molecular medicine》2013,17(10):1282-1290
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Sverin Jouveau Maude Toïgo Brice Giffard Bastien Castagneyrol Inge van Halder Fabrice Vtillard Herv Jactel 《Insect Conservation and Diversity》2020,13(1):36-46
- More diverse forests are generally more resistant to insect herbivores. This might be due to positive effects of tree diversity on predation. Although the enemies hypothesis has received conflicting evidence in forest ecosystems.
- Carabids were sampled by pitfall trapping in a tree diversity experiment, at the centre of plots ranging from one to five tree species mixtures. The composition and vertical structure of the vegetation was assessed at three scales, in the understorey, in the canopy of the experimental plots, and in the surrounding area of each plot.
- None of the tested vegetation variables had an effect on the species richness of carabids. In contrast, the vegetation compositional diversity at the understorey, canopy and surrounding scales had additive and positive effects on the activity‐density of the carabids.
- Our findings indicate that more diverse forests can host a higher activity‐density of predatory carabids, as a result of the combined effect of horizontal and vertical vegetation diversity, which might increase both habitat quality and the amount of feeding resources. This highlights the relevance of manipulative tree diversity experiments to identify the ecological filters shaping local carabid communities.