Characterization of Genomic Inheritance of Intergeneric Hybrids between Ascocenda and Phalaenopsis Cultivars by GISH,PCR-RFLP and RFLP

BackgroundThe intergeneric hybrids between Ascocenda John De Biase ‘Blue’ and Phalaenopsis Chih Shang''s Stripes have been generated to introduce the blue color into the Phalaenopsis germplasm in prior study. In order to confirm the inheritance in hybrid progenies, genomic in situ hybridization (GISH) and restriction fragment length polymorphism (RFLP) analysis were conducted to confirm the intergeneric hybridization status.Methods/ResultsGISH analysis showed the presence of both maternal and paternal chromosomes in the cells of the putative hybrids indicating that the putative hybrid seedlings were intergeneric hybrids of the two parents. Furthermore, twenty-seven putative hybrids were randomly selected for DNA analysis, and the external transcribed spacer (ETS) regions of nrDNA were analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and RFLP analyses to identify the putative hybrids. RFLP analysis showed that the examined seedlings were intergeneric hybrids of the two parents. However, PCR-RFLP analysis showed bias to maternal genotype.ConclusionsBoth GISH and RFLP analyses are effective detection technology to identify the intergeneric hybridization status of putative hybrids. Furthermore, the use of PCR-RFLP analysis to identify the inheritance of putative hybrids should be carefully evaluated.     

Probing the polarity and water environment at the protein-peptide binding interface using tryptophan analogues

7-Azatryptophan and 2,7-diazatryptophan are sensitive to polarity changes and water content, respectively, and should be ideal for studying protein-protein and protein-peptide interactions. In this study, we replaced the tryptophan in peptide Baa (LKWKKLLKLLKKLLKLG-NH₂) with 7-azatryptophan or 2,7-diazatryptophan, forming (7-aza)Trp-Baa and (2,7-aza)Trp-Baa, to study the calmodulin (CaM)-peptide interaction. Dramatic differences in the (7-aza)Trp-Baa and (2,7-aza)Trp-Baa fluorescence properties between free peptide in water and calmodulin-bound peptide were observed, showing a less polar and water scant environment at the binding interface of the peptide upon calmodulin binding. The affinity of the peptides for binding CaM followed the trend Baa (210±10 pM)<(7-aza)Trp-Baa (109±5 pM)<(2,7-aza)Trp-Baa (45±2 pM), showing moderate increase in binding affinity upon increasing the number of nitrogen atoms in the Trp analogue. The increased binding affinity may be due to the formation of more hydrogen bonds upon binding CaM for the Trp analogue with more nitrogen atoms. Importantly, the results demonstrate that (7-aza)Trp and (2,7-aza)Trp are excellent probes for exploring the environment at the interface of protein-peptide interactions.     

Acidogenic growth model of embryogenic cell suspension culture and qualitative mass production of somatic embryos from triploid bananas

A young male flower-derived embryogenic suspension cell population of AAA ‘Pei Chiao’, ‘Dwarf Cavendish’, and AAB ‘Raja’ was used for developing an acidogenic growth model . We hypothesized that a close relationship exists between the self-regulated pH medium and the corresponding changes in the growth phases. Studies have reported that a pH below 4.6 may prevent the embryogenic cells from undergoing polar growth. Controlling pH up to a level 4.6 within 2 days during the changes of pre-embryogenic cells (PECs) and proembryogenic masses into embryogenic determined cells (EDCs) uniformly resulted in unequal cell division. The hydrogen ion buffer 2-N-morpholino-ethanesulfonic acid at 10 g L⁻¹ was added to MA2 and MA3 media, showing the medium pH of MA3 up to 5.0, thus maintaining a relatively stable pH in AAA ‘Pei-Chiao’ and AAB ‘Raja’ cells that autoregulate acidification, significantly increasing the number of somatic embryos. When the proliferation and globularization phases were acidified to pH 3.5 ± 0.2, cells were released to free single cells of PECs and EDCs after 21 days. This study provides possible explanation that PECs deposit callose on their cell walls as a possible protector from strong acidic condition. Regulation at pH 5.0 ± 0.2 resulted the production efficiency achieved was 0.9 million somatic embryos per 1 mL of the settled cell volume.

     

Strategies Toward Stable Nonaqueous Alkali Metal–O2 Batteries

Alkali metal–O₂ batteries, by coupling high‐capacity alkali metal anodes with gaseous oxygen, possess extremely high gravimetric energy density that is comparable to gasoline and are potential energy storage technologies beyond lithium–ion batteries. The development of alkali metal–O₂ batteries has achieved great progress in recent years, from materials to prototype devices and on fundamental mechanisms. The stability of alkali metal–O₂ batteries is still poor, however, leading to a huge gap between laboratory research and commercial applications. A series of parasitic reactions result in the instability, which occur during electrochemical discharging and charging. The ubiquitous active oxygen species attack both the organic electrolyte and the carbon cathode, triggering various parasitic reactions. Meanwhile, dendrite growth and volume expansion upon repeated plating/stripping and O₂ crossover severely limit the reversibility of alkali metal anodes. Here, an overview of the strategies against these issues is given to improve the stability of nonaqueous alkali metal–O₂ batteries, which is discussed from three aspects: air cathodes, alkali metal anodes, and aprotic electrolytes. Furthermore, perspectives for future research of stable alkali metal–O₂ batteries are outlined.     

Ultrathin 2D TiS2 Nanosheets for High Capacity and Long‐Life Sodium Ion Batteries

Sodium ion batteries are now attracting great attention, mainly because of the abundance of sodium resources and their cheap raw materials. 2D materials possess a unique structure for sodium storage. Among them, transition metal chalcogenides exhibit significant potential for rechargeable battery devices due to their tunable composition, remarkable structural stability, fast ion transport, and robust kinetics. Herein, ultrathin TiS₂ nanosheets are synthesized by a shear‐mixing method and exhibit outstanding cycling performance (386 mAh g^?1 after 200 cycles at 0.2 A g^?1). To clarify the variations of galvanostatic curves and superior cycling performance, the mechanism and morphology changes are systematically investigated. This facile synthesis method is expected to shed light on the preparation of ultrathin 2D materials, whose unique morphologies could easily enable their application in rechargeable batteries.     

The motility and dynamic properties of intermediate filaments and their constituent proteins

Intermediate filament (IF) proteins exist in multiple structural forms within cells including mature IF, short filaments or 'squiggles', and non-filamentous precursors called particles. These forms are interconvertible and their relative abundance is IF type, cell type- and cell cycle stage-dependent. These structures are often associated with molecular motors, such as kinesin and dynein, and are therefore capable of translocating through the cytoplasm along microtubules. The assembly of mature IF from their precursor particles is also coupled to translation. These dynamic properties of IF provide mechanisms for regulating their reorganization and assembly in response to the functional requirements of cells. The recent findings that IF and their precursors are frequently associated with signaling molecules have revealed new functions for IF beyond their more traditional roles as mechanical integrators of cells and tissues.     

Nearly identical paralogs: implications for maize (Zea mays L.) genome evolution

As an ancient segmental tetraploid, the maize (Zea mays L.) genome contains large numbers of paralogs that are expected to have diverged by a minimum of 10% over time. Nearly identical paralogs (NIPs) are defined as paralogous genes that exhibit > or = 98% identity. Sequence analyses of the "gene space" of the maize inbred line B73 genome, coupled with wet lab validation, have revealed that, conservatively, at least approximately 1% of maize genes have a NIP, a rate substantially higher than that in Arabidopsis. In most instances, both members of maize NIP pairs are expressed and are therefore at least potentially functional. Of evolutionary significance, members of many NIP families also exhibit differential expression. The finding that some families of maize NIPs are closely linked genetically while others are genetically unlinked is consistent with multiple modes of origin. NIPs provide a mechanism for the maize genome to circumvent the inherent limitation that diploid genomes can carry at most two "alleles" per "locus." As such, NIPs may have played important roles during the evolution and domestication of maize and may contribute to the success of long-term selection experiments in this important crop species.