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1.
Antoine Wystrach Sebastian Schwarz Patrick Schultheiss Guy Beugnon Ken Cheng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(2):167-179
The Australian desert ant Melophorus bagoti often follows stereotypical routes through a cluttered landscape containing both distant panoramic views and obstacles (plants)
to navigate around. We created an artificial obstacle course for the ants between a feeder and their nest. Landmarks comprised
natural objects in the landscape such as logs, branches, and tussocks. Many ants travelled stereotypical routes home through
the obstacle course in training, threading repeatedly the same gaps in the landmarks. Manipulations altering the relations
between the landmarks and the surrounding panorama, however, affected the routes in two major ways. Both interchanging the
positions of landmarks (transpositions) and displacing the entire landmark set along with the starting position of the ants
(translations) (1) reduced the stereotypicality of the route, and (2) increased turns and meanders during travel. The ants
might have used the entire panorama in view-based travel, or the distal panorama might prime the identification and use of
landmarks en route. Despite the large data set, both options (not mutually exclusive) remain viable. 相似文献
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Timothy J. Strabala Sebastian Y. Bednarek Gregory Bertoni Richard M. Amasino 《Molecular & general genetics : MGG》1989,216(2-3):388-394
Summary A 1.9 kb clone of the T-DNA region of the Agrobacterium tumefaciens Ti plasmid Bo542 which exhibited homology to the isopentenyl transferase (ipt) locus of pTiA6 was identified by low stringency DNA hybridization. Introduction of this segment of pTiBo542 DNA into cells of Nicotiana tabacum or N. glauca caused tumor formation in vivo, and allowed hormone independent growth in vitro. Furthermore, this DNA segment complemented ipt mutant strains of A. tumefaciens, restoring their ability to cause tumors on Kalanchöe leaves and tomato stems. The complete DNA sequence of this segment has been determined, revealing an open reading frame homologous to other known Agrobacterium ipt genes. 相似文献
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Nicotiana tabacum protoplasts were transformed by polyethylene glycol (PEG)-mediated uptake and electroporation, with circular and linear DNA, and with or without X-ray irradiation. We investigated the influence on the transient expression by these parameters as well as on the frequencies for stable transformation. Plants were regenerated and selfed, and the progenies of the transformed plants were analysed and used to compare the pattern of gene integration by these different variations in transformation methods. The results from the transient expression as judged by glucuronidase (GUS) activity, showed electroporation to give higher and more reproducible results than PEG-mediated uptake. Using linear instead of circular DNA increased the rate of stable transformation about 3 times. Including a mild X-ray treatment gave an increase in the same range. When the inheritance of the transferred trait was investigated, it was found that protoplasts transformed with linear DNA resulted in the highest number of plants with single-copy insertions. Protoplasts transformed with circular DNA showed the highest incidence of losing the trait, while plants in which the transformation included an X-ray treatment, had the highest frequency of multicopy insertion events. 相似文献
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Summary Reproductive value (RV) and net reproductive output (R
o) are frequently used fitness measures. We argue that they are only appropriate when intervals between reproductive events are fixed, as they are dimensionless generation-to-generation scalings with units offspring per parent. A fitness measure should account for two different effects of a decrease in generation time: (1) increased survival due to shorter exposure to mortality agents and (2) increased frequency of reproduction.R
o andRV deal with the first of these two effects, while a measure with a physical dimensionper time [T–1] is needed to account for the second. The Malthusian growth parameter,r, meets this requirement and in situations where time to reproduction is variable, we propose, the instantaneous rate of spread of descendants (from an individual) be used instead ofR
o. As an alternative toRV, we suggest using the instantaneous difference = –r, wherer is the population rate of increase. WhileRV andR
o are dimensionless ratios, , and areper time rates which are appropriate in accounting for alterations in generation time. 相似文献
8.
Max R. Brown Hannes Becher Sebastian Williams Alex D. Twyford 《American journal of botany》2023,110(1):e16100
Premise
Strong postzygotic reproductive isolating barriers are usually expected to limit the extent of natural hybridization between species with contrasting ploidy. However, genomic sequencing has revealed previously overlooked examples of natural cross-ploidy hybridization in some flowering plant genera, suggesting that the phenomenon may be more common than once thought. We investigated potential cross-ploidy hybridization in British eyebrights (Euphrasia, Orobanchaceae), a group from which 13 putative cross-ploidy hybrid combinations have been reported based on morphology.Methods
We analyzed a contact zone between diploid Euphrasia rostkoviana and tetraploid E. arctica in Wales. We sequenced part of the internal transcribed spacer (ITS) of nuclear ribosomal DNA and used genotyping by sequencing (GBS) to look for evidence of cross-ploidy hybridization and introgression.Results
Common variant sites in the ITS region were fixed between diploids and tetraploids, indicating a strong barrier to hybridization. Clustering analyses of 356 single-nucleotide polymorphisms (SNPs) generated using GBS clearly separated samples by ploidy and revealed strong genetic structure (FST = 0.44). However, the FST distribution across all SNPs was bimodal, indicating potential differential selection on loci between diploids and tetraploids. Demographic inference suggested potential gene flow, limited to around one or fewer migrants per generation.Conclusions
Our results suggest that recent cross-ploidy hybridization is rare or absent in a site of secondary contact in Euphrasia. While a strong ploidy barrier prevents hybridization over ecological timescales, such hybrids may form in stable populations over evolutionary timescales, potentially allowing cross-ploidy introgression to take place. 相似文献9.
Rizky Pasthika Kirana Kumar Gaurav Sanu Arora Gerlinde Wiesenberger Maria Doppler Sebastian Michel Simone Zimmerl Magdalena Matic Chinedu E. Eze Mukesh Kumar Ajla Topuz Marc Lemmens Rainer Schuhmacher Gerhard Adam Brande B. H. Wulff Hermann Buerstmayr Barbara Steiner 《Plant biotechnology journal》2023,21(1):109-121
Aegilops tauschii is the diploid progenitor of the wheat D subgenome and a valuable resource for wheat breeding, yet, genetic analysis of resistance against Fusarium head blight (FHB) and the major Fusarium mycotoxin deoxynivalenol (DON) is lacking. We treated a panel of 147 Ae. tauschii accessions with either Fusarium graminearum spores or DON solution and recorded the associated disease spread or toxin-induced bleaching. A k-mer-based association mapping pipeline dissected the genetic basis of resistance and identified candidate genes. After DON infiltration nine accessions revealed severe bleaching symptoms concomitant with lower conversion rates of DON into the non-toxic DON-3-O-glucoside. We identified the gene AET5Gv20385300 on chromosome 5D encoding a uridine diphosphate (UDP)-glucosyltransferase (UGT) as the causal variant and the mutant allele resulting in a truncated protein was only found in the nine susceptible accessions. This UGT is also polymorphic in hexaploid wheat and when expressed in Saccharomyces cerevisiae only the full-length gene conferred resistance against DON. Analysing the D subgenome helped to elucidate the genetic control of FHB resistance and identified a UGT involved in DON detoxification in Ae. tauschii and hexaploid wheat. This resistance mechanism is highly conserved since the UGT is orthologous to the barley UGT HvUGT13248 indicating descent from a common ancestor of wheat and barley. 相似文献
10.
Sebastian Voigt Reinhart Gossrau Oliver Baum Klemens L?ster Werner Hofmann Werner Reutter 《The Histochemical journal》1995,27(2):123-132
Summary The 11-integrin is known to be a receptor for collagen and laminin mediating cell-matrix interactions. A monoclonal antibody, 33.4, which specifically inhibits the 1-integrin-mediated in vitro cell-collagen binding of rat hepatocytes and hepatoma-derived A-cells (Löster et al., 1994), was used to purify by immunoaffinity chromatography the 1-integrin subunit from rat liver in large quantities for inducing a polyclonal antiserum. In immunoblot analysis on membrane extracts of several rat organs this polyclonal antiserum recognized only a 190 kDa-band, suggesting that it is highly specific for the 1-integrin subunit. A sandwich-ELISA with monoclonal antibody 33.4 and the polyclonal antiserum against the 1-integrin subunit, respectively, enabled the quantitative expression pattern of the 1-integrin subunit to be studied in different rat organs. With the exceptions of brain (not detectable) and muscle (low concentration), the 1-integrin subunit was detectable in almost all organs of the digestive, respiratory and urogenital system as well as in lymphatic organs. The highest relative concentrations of 1-integrin subunit were found in uterus, lung and spleen, whereas in seminal vesicle, stomach, parotid gland, epididymis, kidney and liver only modest concentrations were evident. The organ distribution and localization of 1-integrin subunit were studied by immunohistochemistry with monoclonal and polyclonal antibodies. Immunoreactivity was present in the plasma membranes of all smooth muscle cells, vascular endothelial cells of many organs and fibrocyte-fibroblast sheaths in the heart and kidney. Since these cells are in close contact with collagen-containing basal membranes as well as reticular fibrils, strong evidence exists that in rat tissues the 1-integrin subunit is expressed at sites where collagen is present and might be involved in vivo in cell—ollagen binding.Dedicated to Professor Peter Sitte on the occasion of his 65th birthday 相似文献