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Silver nanoparticles (AgNP) are heavily used in consumer products and medical devices, including face masks to fight against COVID-19. AgNP effects on mammals have been studied both using cellular and animal models. The former elucidate molecular mechanisms occurring at the subcellular level, while the latter bring insight into the toxicity and accumulation at the organ level. It has not yet been possible to reconcile these two kinds of studies in a translational approach. In the current study, we use 3D HepG2/C3A hepatocyte cultures that partially reproduce liver architecture, leading to the formation of active bile canaliculi and exposure scenarios mimicking parenteral or oral exposure to AgNP. By using a combination of cutting edge imaging techniques, atomic spectroscopy, and cell biology, we reveal the formation of Ag sulphide or Ag–organothiol complexes in the different conditions, the storage of excess Ag into vacuoles, the excretion of Ag(i) ions into bile canaliculi through the ATP7B Cu transporter, and modifications of the mitochondrial network. These findings, made possible by the use of a pseudo-organ as a model, reveal exposure-dependent mechanisms that can inspire future studies on nanomaterial metabolism in mammals and risk-assessment, and thereof regulations. Moreover, they can help bridge the gap between cellular and animal studies, bringing significant advances into the understanding of AgNP fate in mammals.

Plastid division in higher plants is morphologically similar to bacterial cell division, with a process termed binary fission involving constriction of the envelope membranes. FtsZ proteins involved in bacterial division are also present in higher plants, in which the ftsZ genes belong to two distinct families: ftsZ1 and ftsZ2. However, the roles of the corresponding proteins FtsZ1 and FtsZ2 in plastid division have not been determined. Here we show that the expression of plant FtsZ1 and FtsZ2 in bacteria has different effects on cell division, and that distinct protein domains are involved in the process. We have studied the assembly of purified FtsZ1 and FtsZ2 using a chemical cross-linking approach followed by PAGE and electron microscopy analyses of the resulting polymers. This has revealed that FtsZ1 is capable of forming long rod-shaped polymers and rings similar to the bacterial FtsZ structures, whereas FtsZ2 does not form any organized polymer. Moreover, using purified sub-plastidial fractions, we show that both proteins are present in the stroma, and that a subset of FtsZ2 is tightly bound to the purified envelope membranes. These results indicate that FtsZ2 has a localization pattern distinct from that of FtsZ1, which can be related to distinct properties of the proteins. From the results presented here, we propose a model for the sequential topological localization and functions of green plant FtsZ1 and FtsZ2 in chloroplast division.

When maize calluses are grown in the presence of the RGD peptide, important morphological changes are observed indicating the presence of a likely RGD-binding receptor. Polyclonal antibodies generated against the human β1 integrin subunit, the platelet integrin αIIbβ3 (P23) and antibodies specific for either the β3 platelet chain or the αIIb polypeptide cross-react with glycoproteins in Western blot analyses. Immunoprecipitation assays indicate that this maize integrin-like protein shares structural similarities with the animal αIIbβ3 complex. We also show that AcAt2, a polyclonal antibody raised against Arabidopsisproteins purified on an RGD column, interacts with a maize protein.

When maize calluses are grown in the presence of the RGD peptide, important morphological changes are observed indicating the presence of a likely RGD‐binding receptor. Polyclonal antibodies generated against the human β1 integrin subunit, the platelet integrin αIIbβ3 (P23) and antibodies specific for either the β3 platelet chain or the αIIb polypeptide cross‐react with glycoproteins in Western blot analyses. Immunoprecipitation assays indicate that this maize integrin‐like protein shares structural similarities with the animal αIIbβ3 complex. We also show that AcAt2, a polyclonal antibody raised against Arabidopsisproteins purified on an RGD column, interacts with a maize protein.

Closely linked genes for 18S and 5S rRNAs have been located on four different cloned SalI restriction fragments of wheat (Triticum aestivumL.) mitochondrial DNA. Restriction analysis has revealed that in each of the cloned fragments, the 18S and 5S rRNA genes are contained within the same basic structural unit, R, which is at least 4 kbp long. This unit is flanked by sequences designated u(0.8 kbp), v(13.7 kbp), w(0.7 kbp), and y(1.4 kbp), in the orientations v‐R‐w, v‐R‐y, u‐R‐w,and u‐R‐yin the four different SalI fragments. We conclude that 18S + 5S rRNA genes are located at several distinct sites in the wheat mitochondrial genome, and suggest that reciprocal intra‐ and/or intermolecular recombination between such repeated sequences could promote extensive genomic rearrangement and thus contribute to the physical heterogeneity that is a hallmark of most plant mitochondrial DNAs.

Closely linked genes for 18S and 5S rRNAs have been located on four different cloned SalI restriction fragments of wheat (Triticum aestivumL.) mitochondrial DNA. Restriction analysis has revealed that in each of the cloned fragments, the 18S and 5S rRNA genes are contained within the same basic structural unit, R, which is at least 4 kbp long. This unit is flanked by sequences designated u(0.8 kbp), v(13.7 kbp), w(0.7 kbp), and y(1.4 kbp), in the orientations v‐R‐w, v‐R‐y, u‐R‐w,and u‐R‐yin the four different SalI fragments. We conclude that 18S + 5S rRNA genes are located at several distinct sites in the wheat mitochondrial genome, and suggest that reciprocal intra‐ and/or intermolecular recombination between such repeated sequences could promote extensive genomic rearrangement and thus contribute to the physical heterogeneity that is a hallmark of most plant mitochondrial DNAs.

To measure transcript levels for individual members of the Cab (chlorophyll a/b protein) multigene family in pea under a range of developmental situations, we developed a system using cDNA synthesis, the polymerase chain reaction (PCR), and chemiluminescence detection. In order to design gene-specific PCR primers for all genes, a partial genomic clone for a fifth, Type I LHCII (light-harvesting complex of photosystem II) gene, Cab-9The Cab-9 sequence appears in the Genbank/EMBL databases under the accession number M86906, was isolated and sequenced. All seven known Cab genes in pea are expressed in light-grown buds and leaves, including several genes previously known only from genomic clones. There appear to be at least two groups of Cab genes in pea which differ in their response to light and development. The first group (consisting of Cab-8, AB96, Cab-215 and Cab-315) includes Type I, Type II and Type III genes, shows a relatively strong response to red light, and has bud transcript levels similar to or slightly higher than leaves. The second group, consisting of the Type I genes Cab-9, AB80 and AB66, shows little or no transcript accumulation 24 h after a red light pulse, and has higher transcript levels in leaves than in buds. Transcript levels for genes in this second group appear to be lower than those of the first group in all developmental situations examined. These data indicate that there has been an evolutionary divergence of the responses to light and development among the Type I LHCII genes.

The nucleotide sequence of the wheat mitochondrial 26S ribosomal RNA gene and flanking regions was determined and compared with mitochondrial 26S rRNA genes from maize and Oenothera. All three genes exhibit a high degree of homology except within two variable regions. When the plant mitochondrial 26S rRNA genes are compared with Escherichia coli 23S rRNA and chloroplast 23S and 4.5S rRNA genes, a third variable region is apparent close to the 3' end of the gene. The 5' and 3' ends of the wheat mitochondrial gene were determined by S1 nuclease mapping. Computer analysis of the wheat mitochondrial gene revealed several small sequences present either in the 5' region of the 26S rRNA gene or in the 18S rRNA gene.

Wheat mitochondria) DNA has been isolated from callus cultures initiated from both immature embryos and the corresponding parental cultivar. A Sall restriction pattern study has shown that the organization of callus culture mitochondria) DNA underwent extensive change, characterized by either the disappearance or the decrease in the relative stoichiometry of several restriction bands. Hybridization of labelled mitochondrial fragments obtained from a recombinant cosmid library to Southern blots of callus and parental line restricted mitochondria) DNAs has shown that a fraction of the mitochondria) genome was lost in callus cultures. Data from a Sall + HindIII restriction map of a defined part of the wheat mitochondria) genome concerned with some of these variations strongly suggest that the observed variations correspond to the disappearance of at least one mitochondria) DNA subgenomic molecule in callus cultures.

Analysis of cloned SalI fragments coding for the 26S rRNA in wheat mitochondria (Triticumaestivum L.) shows that the 26S gene is contained within the same basic structural unit RS (which is about 6.6 kbp long). This repeated sequence is flanked by four different sequences I, II, III, IV in the orientations: I-RS-III, I-RS-IV, II-RS-III and II-RS-IV. This organization of the 26S gene, similar to the organization found for the 5S and 18S gene, suggests again that reciprocal intra-and/or intermolecular recombination occurs within these repeated sequences. S1 mapping and R loop mapping indicate that the 26S gene is about 3.5 kbp and has no intron.