Transthyretin mouse transgenes direct RFP expression or Cre‐mediated recombination throughout the visceral endoderm

Transthyretin (Ttr) is a thyroid hormone transport protein secreted by cells of the visceral yolk sac and fetal liver in developing embryos, and by hepatocytes and the choroid plexus epithelium of the brain in adult mice. Spatiotemporal localization of Ttr mRNA during embryogenesis suggested that Ttr regulatory elements might drive transgene expression throughout the visceral endoderm of early mouse embryos. We use Ttr cis‐regulatory elements to generate Ttr::RFP and Ttr::Cre strains of mice, driving red fluorescent protein (RFP) and a nuclear‐localized Cre recombinase, respectively. Visualization of RFP fluorescence in Ttr::RFP transgenics confirms reporter localization throughout the visceral endoderm in early embryos and in the visceral yolk sac and fetal liver of later stage embryos. Using both GFP‐based and LacZ‐based Cre reporter strains, we demonstrate that in Ttr::Cre transgenics, Cre‐mediated recombination occurs throughout the visceral endoderm. The Ttr::Cre strain can therefore be used as a tool for genetic modifications within the visceral endoderm lineage. genesis 47:447–455, 2009. © 2009 Wiley‐Liss, Inc.     

Highly Active and Durable Pt72Ru28 Porous Nanoalloy Assembled with Sub‐4.0 nm Particles for Methanol Oxidation

The main challenges to the direct methanol fuel cells are the activity and durability of electrocatalysts. To alleviate such issues, a recently proposed strategy introduces an exotic element to form Pt‐based alloy nanostructures. This study reports a green route to prepare porous flowerlike Pt₇₂Ru₂₈ nanoalloys assembled with sub‐4.0 nm particles. The peak current density and mass activity on these as‐synthesized porous flowerlike Pt₇₂Ru₂₈ nanoalloys can be increased to 10.98 mA cm^?2 and 1.70 A mg^?1 Pt for methanol oxidation in acidic medium. They are respectively 4.19/3.54, 4.27/5.0, and 5.74/1.73 times those on the commercial Pt black, Pt₅₀Ru₅₀ black, and Ru₅₀Pt₅₀/C. These porous flowerlike Pt₇₂Ru₂₈ nanoalloys have a much higher long‐term durability than commercial Pt black, Pt₅₀Ru₅₀ black, and Ru₅₀Pt₅₀/C. More significantly, the porous Pt₇₂Ru₂₈ bimetallic nanoalloys have long‐term solvent durability after immersion in water for 16 months. The peak current density and mass activity on porous Pt₇₂Ru₂₈ nanoalloys are still 7.76 mA cm^?2 and 1.2 A mg^?1 Pt. These experimental results show an effective approach to the development of PtRu nanoalloys as electrocatalysts with substantially enhanced activity and durability for direct methanol fuel cells.     

Tailored Electron Transfer Pathways in Aucore/Ptshell–Graphene Nanocatalysts for Fuel Cells

Au_core/Pt_shell–graphene catalysts (G‐Cys‐Au@Pt) are prepared through chemical and surface chemical reactions. Au–Pt core–shell nanoparticles (Au@Pt NPs) covalently immobilized on graphene (G) are efficient electrocatalysts in low‐temperature polymer electrolyte membrane fuel cells. The 9.5 ± 2 nm Au@Pt NPs with atomically thin Pt shells are attached on graphene via l ‐cysteine (Cys), which serves as linkers controlling NP loading and dispersion, enhancing the Au@Pt NP stability, and facilitating interfacial electron transfer. The increased activity of G‐Cys‐Au@Pt, compared to non‐chemically immobilized G‐Au@Pt and commercial platinum NPs catalyst (C‐Pt), is a result of (1) the tailored electron transfer pathways of covalent bonds integrating Au@Pt NPs into the graphene framework, and (2) synergetic electronic effects of atomically thin Pt shells on Au cores. Enhanced electrocatalytic oxidation of formic acid, methanol, and ethanol is observed as higher specific currents and increased stability of G‐Cys‐Au@Pt compared to G‐Au@Pt and C–Pt. Oxygen reduction on G‐Cys‐Au@Pt occurs at 25 mV lower potential and 43 A g_Pt^?1 higher current (at 0.9 V vs reversible hydrogen electrode) than for C–Pt. Functional tests in direct fomic acid, methanol and ethanol fuel cells exhibit 95%, 53%, and 107% increased power densities for G‐Cys‐Au@Pt over C–Pt, respectively.     

Pt‐Ir‐Pd Trimetallic Nanocages as a Dual Catalyst for Efficient Oxygen Reduction and Evolution Reactions in Acidic Media

The development of dual catalysts with high efficiency toward oxygen reduction and evolution reactions (ORR and OER) in acidic media is a significant challenge. Here an active and durable dual catalyst based upon cubic Pt₃₉Ir₁₀Pd₁₁ nanocages with an average edge length of 12.3 nm, porous walls as thin as 1.0 nm, and well‐defined {100} facets is reported. The trimetallic nanocages perform better than all the reported dual catalysts in acidic media, with a low ORR‐OER overpotential gap of only 704 mV at a Pt‐Ir‐Pd loading of 16.8 µg_Pt+Ir+Pd cm^?2_geo. For ORR at 0.9 V, when benchmarked against the commercial Pt/C and Pt‐Pd nanocages, the trimetallic nanocages exhibit an enhanced mass activity of 0.52 A mg^?1_Pt+Ir+Pd (about four and two times as high as those of the Pt/C and Pt‐Pd nanocages) and much improved durability. For OER, the trimetallic nanocages show a remarkable mass activity of 0.20 A mg^?1_Pt+Ir at 1.53 V, which is 16.7 and 4.3 fold relative to those of the Pt/C and Pt‐Pd nanocages, respectively. These improvements can be ascribed to the highly open structure of the nanocages, and the possible electronic coupling between Ir and Pt atoms in the lattice.     

Metal-stabilized rare tautomers of nucleobases

 A Pt^II complex containing N4 bound neutral 1-methylcytosine (1-MeC), trans–[Pt(NH₃)₂(1-MeC-N4)₂](ClO₄)₂ (5), has been prepared and characterized by X-ray analysis. The complex contains the rare iminooxo tautomer form of the cytosine nucleobase. Pt^II binding is through the exocyclic N4 position of the nucleobases, with Pt and the N3 positions in a syn orientation. As a consequence, the proton at N3 is pointing toward the heavy metal, thereby allowing an agostic Pt···HN interaction. Formation of 5 is achieved via oxidation of the linkage isomer trans–[Pt(NH₃)₂(1-MeC-N3)₂]²⁺ (1) to a Pt^IV species (2), followed by metal migration to N4, and subsequent reduction to Pt^II. This process is a text-book example for a redox-assisted metal migration at a heterocyclic ligand. The existence of various rotamers of 5 in aqueous solution is evident from ¹H NMR spectroscopy. The possible role of these rotamers of the metalated rare tautomer, and in particular of those having Pt and the N3 position in an anti arrangement, with regard to base mispairing is discussed. Received: 27 February 1996 / Accepted: 10 June 1996     

Differential permeability of murine visceral yolk sac to thymidine and to hydroxyurea.

Mouse embryos at the 10–12-somite stage of development were excised from the uterus either with or without the encapsulating visceral yolk sac and were incubated in vitro in 3 × 10^?7M thymidine (methyl-T, 5 μCi/ml) for 30 min or in 4 × 10^?3M hydroxyurea for 45 min with [³H]thymidine present for the last 30 min. Radioautograms of nuclei of neural epithelium enabled an estimate of the effectiveness of the barrier imposed by the visceral yolk sac membrane to the passage of thymidine and hydroxyurea.Labeling of nuclei in the neural epithelium showed that the visceral yolk sac caused a 44% decrease in frequency and a 51% decrease in intensity of label. Hydroxyurea inhibited labeling by 15% in frequency and 37% in intensity irrespective of the presence or absence of visceral yolk sac. These results show that hydroxyurea and the presence of visceral yolk sac independently interfered with labeling of the neural epithelium by thymidine and that visceral yolk sac caused a proportionally greater retardation of label than did hydroxyurea.Nuclei of the endodermal epithelium of the intervening yolk sac, following exposure to hydroxyurea, showed a labeling decrease of 44% in frequency and 77% in intensity. The inhibitory effect of hydroxyurea on yolk sac labeling, however, did not alter yolk sac permeability to hydroxyurea. The results indicate that the visceral yolk sac, by offering no detectable barrier to hydroxyurea, permits prompt teratogenic action of hydroxyurea directly upon the embryo and suggest that the visceral yolk sac is a likely candidate to account for reports that the 8.5-day mouse embryo in situ fails to label with radioisotopic thymidine.     

A conditional mutant allele for analysis of Mixl1 function in the mouse

Mixl1 is the only member of the Mix/Bix homeobox gene family identified in mammals. During mouse embryogenesis, Mixl1 is first expressed at embryonic day (E)5.5 in cells of the visceral endoderm (VE). At the time of gastrulation, Mixl1 expression is detected in the vicinity of the primitive streak. Mixl1 is expressed in cells located within the primitive streak, in nascent mesoderm cells exiting the primitive streak, and in posterior VE overlying the primitive streak. Genetic ablation of Mixl1 in mice has revealed its crucial role in mesoderm and endoderm cell specification and tissue morphogenesis during early embryonic development. However, the early lethality of the constitutive Mixl1^?/? mutant precludes the study of its role at later stages of embryogenesis and in adult mice. To circumvent this limitation, we have generated a conditional Mixl1 allele (Mixl1^cKO) that permits temporal as well as spatial control of gene ablation. Animals homozygous for the Mixl1^cKO conditional allele were viable and fertile. Mixl1^KO/KO embryos generated by crossing of Mixl1^cKO/cKO mice with Sox2‐Cre or EIIa‐Cre transgenic mice were embryonic lethal at early somite stages. By contrast to wild‐type embryos, Mixl1^KO/KO embryos contained no detectable Mixl1, validating the Mixl1^cKO as a protein null after Cre‐mediated excision. Mixl1^KO/KO embryos resembled the previously reported Mixl1^?/? mutant phenotype. Therefore, the Mixl1 cKO allele provides a tool for investigating the temporal and tissue‐specific requirements for Mixl1 in the mouse. genesis 52:417–423, 2014. © 2014 Wiley Periodicals, Inc.     

In vivo monitor oxidative burst induced by Cd2+ stress for the oilseed rape (Brassica napus L.) based on electrochemical microbiosensor

Introduction – Since the mechanism of Cd²⁺ stress for plants is not clear, an in vivo method to monitor Cd²⁺ stress for plants is necessary. However, oxidative burst (OB) is a signal messenger in the process of Cd²⁺ stress for plants. Objective – To establish an electrochemical method with poly‐o‐phenylenediamine and Pt microparticle modified Pt electrode (POPD–Pt‐MP–Pt) as a microbiosensor for the in vivo detection of oxidative burst induced by Cd²⁺ stress in oilseed rape (Brassica napus L.). Methodology – The optimal fabrication of POPD–Pt‐MP–Pt biosensor was achieved. Electrochemical signal was collected by amperometry. Results – After oilseed rape was exposed to 84.9 mM CdCl₂ stress, three oxidative bursts were observed in oilseed rape by amperometry at 3.3 h, 8.4 h and 13.2 h, respectively. However, there was no obvious signal observed in the controlled assay. Conclusion – This contribution presents the in vivo monitoring of the OB process induced by Cd²⁺ stress in oilseed rape by POPD–Pt‐MP–Pt microbiosensor in real‐time. The novel electrochemical microbiosensor not only facilitates the real‐time study in plant self‐defence response to the adverse environment such as Cd²⁺ stress, but also provides an effective tool for probing the self‐defence mechanism in plants. Copyright © 2009 John Wiley & Sons, Ltd.     

Accumulation of calcium and phosphorus in pigeon (Columba livia) embryos

Summary Calcium and phosphorus were measured in the yolk and albumen of fertile pigeon (Columba livia) eggs incubated for 0–17 days, and in embryos and hatchlings. Shell provided most of the calcium for skeletal mineralization of the embryos, whereas phosphorus was derived from the yolk and albumen. Mobilization of calcium from the shell to the embryo commenced at approximately day 11 of incubation, accumulating both in the embryo and the yolk sac. There was 1.4 times more calcium in squab yolk sacs than that contained in newly laid egg yolks. The results suggest that whereas general patterns of calcium and phosphorus accumulation during embryogenesis in altricial birds closely resemble those of precocial birds, calcium mobilization from the shell begins later, proceeds at a slower rate and results in a less mineralized hatchling.CIDA/NSERC Visiting Research Associate Permanent address: Department of Animal Science, University of Peradeniya, Peradeniya, Sri Lanka     

Torsion in Patella caerulea (Mollusca, Patellogastropoda): ontogenetic process, timing, and mechanisms

Abstract. Torsion is a process in gastropod ontogenesis where the visceral body portion rotates 180° relative to the head/foot region. We investigated this process in the limpet Patella caerulea by using light microscopy of living larvae, as well as scanning electron microscopy (SEM) of larvae fixed during the torsion process. The completion of the 180° twist takes considerably less time in larvae of Patella caerulea than previously described for other basal gastropod species. At a rearing temperature of 20–22°C, individuals complete ontogenetic torsion in ?2 h. Furthermore, the whole process is monophasic, i.e., carried out at a constant speed, without any evidence of distinct ‘fast” or ‘slow” phases. Both larval shell muscles—the main and the accessory larval retractor—are already fully contractile before the onset of torsion. During the torsion process both retractors perform cramp‐like contractions at ～30 s intervals, which are followed by hydraulic movements of the foot. However, retraction into the embryonic shell occurs only after torsion is completed. The formation of the larval operculum is entirely in‐dependent from ontogenetic torsion and starts before the onset of rotation, as does the mineralization of the embryonic shell. The reported variability regarding the timing (mono‐ versus biphasic; duration) of torsion in basal gastropod species precludes any attempt to interpret these data phylogenetically. The present findings indicate that the torsion process in Patella caerulea, and probably generally in basal gastropods, is primarily caused by contraction of the larval shell muscles in combination with hydraulic activities. In contrast, the adult shell musculature, which is independently formed after torsion is completed, does not contribute to ontogenetic torsion in any way. Thus, fossil data relying on muscle scars of adult shell muscles alone appear inappropriate to prove torted or untorted conditions in early Paleozoic univalved molluses. Therefore, we argue that paleontological studies dealing with gastropod phylogeny require data other than those based on fossilized attachment sites of adult shell muscles.     

Shell differentiation and engrailed expression in the Ilyanassa embryo

 We have used in situ hybridization and immunocytochemistry to study the expression of the engrailed-related gene, Ily-en in embryos of the marine mud snail Ilyanassa obsoleta. We find that Ily-en is only expressed in shell gland cells. Only mRNAs localized in the shell gland hybridize to an antisense probe of the Ily-en homeobox. Similarly, only shell gland cells or shell-forming cells are stained by the monoclonal antibody 4D9, which was raised to the engrailed-class protein from Drosophila. Ilyanassa embryos made deficient in vegetal cytoplasm by removing the third polar lobe fail to differentiate an organized external shell. They do however make some randomly oriented internal shell fragments in which Ily-en is expressed. Because Ily-en is expressed in shell gland cells of both normal and lobeless embryos, we conclude that the determinant(s) required for Ily-en expression are not exclusively localized in the polar lobe. Received: 16 October 1997 / Accepted: 9 January 1998     

Cold-enhanced somatic embryogenesis in cell suspension cultures of Astragalus adsurgens Pall.: relationship with exogenous calcium during cold pretreatment

The inter-relationship between exogenous calcium (Ca²⁺) during cold pretreatment and cold-enhanced somatic embryogenesis was investigated using cell suspension cultures of Astragalus adsurgens Pall. Cell suspension was obtained from embryogenic callus and could be induced to form somatic embryos in the differentiation medium. Suspension cells, after cold-treatment at 8 °C for 2 to 3 wk, displayed an enhanced capacity for somatic embryogenesis as compared to those without cold pretreatment. Longer cold pretreatment (> 4 wk) resulted in the inhibition of somatic embryogenesis. The enhanced embryogenic response of cells to cold pretreatment was dependent on the Ca²⁺ level in the pretreatment medium. Ca²⁺ levels below 1 mM suppressed the cold-enhanced response. Addition of lanthanum into the pretreatment medium completely abolished the cold induced enhancement of somatic embryogenesis. These results suggest that embryogenic cells require a minimal concentration of Ca²⁺ during pretreatment for the expression of this cold-enhanced capacity for somatic embryogenesis in A.adsurgens and the influx of exogenous Ca²⁺ during pretreatment might also be involved.     

Polyoxometalate‐Derived Ultrasmall Pt2W/WO3 Heterostructure Outperforms Platinum for Large‐Current‐Density H2 Evolution

Platinum (Pt)‐based catalysts with high Pt utilization efficiency for efficient H₂ evolution are attracting extensive attention to meet the issues of energy exhaustion and environmental pollution. Herein, a one‐step electrochemical method is demonstrated to construct ultrafine heterostructure Pt₂W/WO₃ on reduced graphene oxide (RGO) by injecting multielectrons into the Preyssler anion [NaP₅W₃₀O₁₁₀]^14? to codeposit with anodic deliquescent Pt cations. The resulting Pt₂W/WO₃/RGO shows much higher performance than that of commercial Pt catalysts for large‐current‐density H₂ evolution, which can deliver a large current density of 500 mA cm^?2 with an overpotential of only 394 mV, much lower than that of 20% Pt/C (578 mV). Comparisons with control experiments and density functional theory (DFT) calculations both suggest that the much enhanced activity can be mainly attributed to the synergistic cooperation of different components to drive fast and continuous hydrogen desorption on Pt₂W/WO₃/RGO, while it could not run normally for 20% Pt/C under similar conditions due to the formation of huge bubbles on the electrode surface. The effective integration of high catalytic activity and hydrogen desorption ability into a single material can yield advanced materials for large‐current‐density H₂ evolution with remarkable stability.     

Changes of 6-benzylaminopurine and 2,4-dichlorophenoxyacetic acid concentrations in plant tissue culture media in the presence of activated charcoal

Somatic embryos and embryogenic callus were initiated from immature zygotic embryos of ginseng (Panax ginseng C.A. Meyer). These somatic embryos were multiplied by adventitious (secondary and tertiary) embryogenesis and their growth and development were dependent on growth hormones in the medium. Auxins, 2,4-d, NAA, and IAA at 1.0 mg l^-1 were effective in inducing secondary and tertiary somatic embryos, which proliferated directly from the apical or cotyledonary portions of the primary somatic embryos. Single somatic embryos or clusters or embryos developed from the explanted primary embryos. Cytokinin (Kn, BA) inhibited adventitious embryogenesis. Secondary somatic embryos developed to maturation and later regenerated into plantlets in two stage process; firstly elongation of the shoot axes on MS +1.0 mg l^-1 Kn, secondly formation of root on 1.0 mg l^-1 Kn+1.0 mg^-1 GA₃ medium.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - NAA naphthaleneacetic acid - IAA in-doleacetic acid - Kn kinetin - BA benzylaminopurine - PSE primary somatic embryo - SSE secondary somatic embryo - TSE tertiary somatic embryo     

The role of calcium on protein secretion of the albumen gland in Helisoma duryi (Gastropoda)

Abstract. The albumen gland of the freshwater pulmonate snail Helisoma duryi produces and secretes the perivitelline fluid, which coats fertilized eggs and provides nutrients to the developing embryos. It is known that perivitelline fluid secretion is stimulated by dopamine through the activation of a dopamine D₁‐like receptor, which in turn stimulates cAMP production leading to the secretion of perivitelline fluid. This paper examines the glandular release of perivitelline fluid and provides evidence for the role of Ca²⁺ in the regulated secretion of perivitelline fluid based on protein secretion experiments and inositol 1,4,5‐trisphosphate assays. Dopamine‐stimulated protein secretion by the albumen gland is reduced in Ca²⁺‐free medium or in the presence of plasma membrane Ca²⁺ channel blockers, although the Ca²⁺ channel subtype involved is unclear. In addition, dopamine‐stimulated protein secretion does not directly involve phospholipase C‐generated signaling pathways and Ca²⁺ release from intracellular stores. Sarcoplasmic/endoplasmic reticulum Ca²⁺‐ATPase inhibitors had little effect on protein secretion when applied alone; however, they potentiated dopamine‐stimulated protein secretion. Dantrolene, an inhibitor of ryanodine receptors, 8‐(N,N‐diethylamino)‐octyl‐3,4,5‐trimethoxybenzoate hydrochloride, a nonspecific inhibitor of intracellular Ca²⁺ channels, and 2‐aminoethyldiphenylborate, an inhibitor of inositol 1,4,5‐trisphosphate receptors, did not suppress protein secretion, suggesting Ca²⁺ release from internal stores does not directly regulate protein secretion. Thus, the influx of Ca²⁺ from the extracellular space appears to be the major pathway mediating protein secretion by the albumen gland. The results are discussed with respect to the role of Ca²⁺ in controlling exocytosis of proteins from the albumen gland secretory cells.     

Differential gene expression profiles in the venom gland/sac of Orancistrocerus drewseni (Hymenoptera: Eumenidae)

To determine differential gene expression profiles in the venom gland and sac (gland/sac) of a solitary hunting wasp species, Orancistrocerus drewseni Saussure (1857), a subtractive cDNA library was constructed by suppression subtractive hybridization. A total of 498 expressed sequence tags (EST) were clustered and assembled into 205 contigs (94 multiple sequences and 111 singletons). About 65% (134) of the contigs had matched BLASTx hits (E≤10^?4). Among these, 115 contigs had similarity to proteins with assigned molecular function in the Gene Ontology database, and most of them (112 contigs, 83%) were homologous to genes from Hymenoptera, particularly to Apis mellifera (98 contigs). The contigs encoding hyaluronidase and phospholipase A2, known to be main components of wasp venoms, were found in high frequencies (27 and 4%, respectively, as judged by the number of ESTs) in the gene ontology category of catalytic activity. Full‐length open reading frames of hyaluronidase and phospholipase A2 were characterized and their abundance in the venom gland/sac was confirmed by quantitative real‐time PCR. Several contigs encoding enzymes, including zinc‐metallopeptidases that are likely involved in the processing and activation of venomous proteins or peptides, were also identified from the library. Discovery of venom gland/sac‐specific genes should promote further studies on biologically active components in the venom of O. drewseni. © 2009 Wiley Periodicals, Inc.     

Dose-dependent effects of developmental mercury exposure on C-start escape responses of larval zebrafish Danio rerio

Zebrafish Danio rerio embryos were exposed to 0, 25, 50 or 75 ppb Hg²⁺ from 0 to 24 h post‐fertilization (hpf) then placed into Hg²⁺‐free water. Inductively coupled plasma‐mass spectrophotometer analysis of whole embryo Hg²⁺ content at 24 hpf showed a positive correlation with exposure regime (Pearson's one‐tailed, r²= 0·698, P < 0·01); at 5 days post‐hatch (dph), whole larval Hg²⁺ content was not detectable. Hg²⁺‐induced behavioural deficits in larvae were, therefore, due to changes during embryogenesis and not to residual Hg²⁺ in the larvae. At 5 dph, larvae were tested for responses to different frequencies but equal intensities of vibrational stimuli generated by a remotely controlled plastic hammer. Data were recorded by high‐speed videography and computer‐analysed for latency of response (ms), amplitude of the response as measured by maximum initial velocity [normalized as body (standard) lengths s^?1; V_max] and duration of behaviour from initial head movement to cessation of caudal tail movement (ms). A single mechanical stimulus resulted in behavioural outcomes that were related to embryonic Hg²⁺ uptake. Response latency increased with exposure level and displayed an increase of ×1·5–2·5 over control values (ANOVA, P < 0·01). The V_max decreased with exposure level to a low of 71% of control at the highest Hg²⁺ concentration (ANOVA, P < 0·01). Duration of behaviour displayed a biphasic response pattern in which exposure to 0, 50 or 75 ppb Hg²⁺ did not result in a significantly different response yet exposure to 25 ppb Hg²⁺ caused a significantly longer time of active response (ANOVA, P < 0·01). Repeated stimulation (1, 2 or 4 hits s^?1) resulted in a concentration‐dependent increase in response failures. Regardless of stimulation frequency, larvae exposed to 0 or 25 ppb Hg²⁺ as embryos maintained higher V_max levels for longer intervals during the testing period than those exposed as embryos to either 50 or 75 ppb Hg²⁺.     

Somatic embryogenesis from immature zygotic embryos and monitoring the genetic fidelity of regenerated plants in grapevine

Somatic embryogenesis and plant regeneration were successfully established on Nitsch and Nitsch (NN) medium from immature zygotic embryos of six genotypes of grapevine (Vitis vinifera). The optimum hormone combinations were 1.0 mg dm⁻³ 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction and 1.0 mg dm⁻³ α-naphthalene acetic acid (NAA) + 0.5 mg dm⁻³ 6-benzyladenine (BA) for embryos production and 0.03 mg dm⁻³ NAA + 0.5 mg dm⁻³ BA for embryos conversion and plant regeneration. The frequency of somatic embryogenesis varied from 10.5 to 37.5 % among six genotypes and 15.5–42.1 % of somatic embryos converted into normal plantlets. The analysis of DNA content determined by flow cytometry and chromosome counting of the regenerated plantlets clearly indicated that no ploidy changes were induced during somatic embryogenesis and plant regeneration, the nuclear DNA content and ploidy levels of the regenerated plants were stable and homogeneous to those of the donor plants. RAPD markers were also used to evaluate the genetic fidelity of plants regenerated from somatic embryos. All RAPD profiles from regenerated plants were monomorphic and similar to those of the field grown donor plants. We conclude that somaclonal variation is almost absent in our grapevine plant regeneration system.     

Ultrafine Pt Nanoparticle‐Decorated Pyrite‐Type CoS2 Nanosheet Arrays Coated on Carbon Cloth as a Bifunctional Electrode for Overall Water Splitting

To improve the utilization efficiency of precious metals, metal‐supported materials provide a direction for fabricating highly active and stable heterogeneous catalysts. Herein, carbon cloth (CC)‐supported Earth‐abundant CoS₂ nanosheet arrays (CoS₂/CC) are presented as ideal substrates for ultrafine Pt deposition (Pt‐CoS₂/CC) to achieve remarkable performance toward the hydrogen and oxygen evolution reactions (HER/OER) in alkaline solutions. Notably, the Pt‐CoS₂/CC hybrid delivers an overpotential of 24 mV at 10 mA cm^?2 and a mass activity of 3.89 A Pt_mg^?1, which is 4.7 times higher than that of commercial Pt/C, at an overpotential of 130 mV for catalyzing the HER. An alkali‐electrolyzer using Pt‐CoS₂/CC as a bifunctional electrode enables a water‐splitting current density of 10 mA cm^?2 at a low voltage of 1.55 V and can sustain for more than 20 h, which is superior to that of the state‐of‐the‐art Pt/C+RuO₂ catalyst. Further experimental and theoretical simulation studies demonstrate that strong electronic interaction between Pt and CoS₂ synergistically optimize hydrogen adsorption/desorption behaviors and facilitate the in situ generation of OER active species, enhancing the overall water‐splitting performance. This work highlights the regulation of interfacial and electronic synergy in pursuit of highly efficient and durable supported catalysts for hydrogen and oxygen electrocatalytic applications.