Embryogenesis and plant regeneration from unpollinated ovaries of Amorphophallus konjac

The system of somatic embryogenesis of Amorphophallus konjac had been built through unpollinated ovaries. The embryogenic calli were induced on Murashige and Skoog (MS) basal medium supplemented with 9.0 μM 6- benzylaminopurine (BA), 0.4 μM 2,4dichlorophenoxyacetic acid (D), 1.0 μM naphthaleneacetic acid (NAA), and the induction rate was 34.0%. The differentiation rate was 35.5% on the medium of MS basal medium supplemented with 6.7 μM 6-BA and 2.2 μM NAA. The obtained plantlets were transferred into rooting medium which was 1/2MS supplementing with 2.7 μM NAA, and the rooting rate was above 95%. All of the media were added 3% (w/v) sucrose and 0.3% (w/v) phytagel, the experimental materials for each step were cultured at 25 ± 2°C with a photoperiod of 12 h and light intensity of 50 μmol m-2 s-1.Keywords: Amorphophallus konjac, unpollinated ovary, embryogenic calli, plant regeneratio

A conserved but plant-specific CDK-mediated regulation of DNA replication protein A2 in the precise control of stomatal terminal division

The R2R3-MYB transcription factor FOUR LIPS (FLP) controls the stomatal terminal division through transcriptional repression of the cell cycle genes CYCLIN-DEPENDENT KINASE (CDK) B1s (CDKB1s), CDKA; 1, and CYCLIN A2s (CYCA2s). We mutagenized the weak mutant allele flp-1 seeds with ethylmethane sulfonate and screened out a flp-1 suppressor 1 (fsp1) that suppressed the flp-1 stomatal cluster phenotype. FSP1 encodes RPA2a subunit of Replication Protein A (RPA) complexes that play important roles in DNA replication, recombination, and repair. Here, we show that FSP1/RPA2a functions together with CDKB1s and CYCA2s in restricting stomatal precursor proliferation, ensuring the stomatal terminal division and maintaining a normal guard-cell size and DNA content. Furthermore, we provide direct evidence for the existence of an evolutionarily conserved, but plant-specific, CDK-mediated RPA regulatory pathway. Serine-11 and Serine-21 at the N terminus of RPA2a are CDK phosphorylation target residues. The expression of the phosphorylation-mimic variant RPA2a(S11,21/D) partially complemented the defective cell division and DNA damage hypersensitivity in cdkb1;1 1;2 mutants. Thus, our study provides a mechanistic understanding of the CDK-mediated phosphorylation of RPA in the precise control of cell cycle and DNA repair in plants

Molecular and cellular evidence for biased mitotic gene conversion in hybrid scallop

<p>Abstract</p> <p>Background</p> <p>Concerted evolution has been believed to account for homogenization of genes within multigene families. However, the exact mechanisms involved in the homogenization have been under debate. Use of interspecific hybrid system allows detection of greater level of sequence variation, and therefore, provide advantage for tracing the sequence changes. In this work, we have used an interspecific hybrid system of scallop to study the sequence homogenization processes of rRNA genes.</p> <p>Results</p> <p>Through the use of a hybrid scallop system (<it>Chlamys farreri </it>♀ × <it>Argopecten irradians </it>♂), here we provide solid molecular and cellular evidence for homogenization of the rDNA sequences into maternal genotypes. The ITS regions of the rDNA of the two scallop species exhibit distinct sequences and thereby restriction fragment length polymorphism (RFLP) patterns, and such a difference was exploited to follow the parental ITS contributions in the F1 hybrid during early development using PCR-RFLP. The representation of the paternal ITS decreased gradually in the hybrid during the development of the hybrid, and almost diminished at the 14th day after fertilization while the representation of the maternal ITS gradually increased. Chromosomal-specific fluorescence <it>in situ </it>hybridization (FISH) analysis in the hybrid revealed the presence of maternal ITS sequences on the paternal ITS-bearing chromosomes, but not vice versa. Sequence analysis of the ITS region in the hybrid not only confirmed the maternally biased conversion, but also allowed the detection of six recombinant variants in the hybrid involving short recombination regions, suggesting that site-specific recombination may be involved in the maternally biased gene conversion.</p> <p>Conclusion</p> <p>Taken together, these molecular and cellular evidences support rapid concerted gene evolution via maternally biased gene conversion. As such a process would lead to the expression of only one parental genotype, and have the opportunities to generate recombinant intermediates; this work may also have implications in novel hybrid zone alleles and genetic imprinting, as well as in concerted gene evolution. In the course of evolution, many species may have evolved involving some levels of hybridization, intra- or interspecific, the sex-biased sequence homogenization could have led to a greater role of one sex than the other in some species.</p

Learning Spiking Neural Network from Easy to Hard task

Starting with small and simple concepts, and gradually introducing complex and difficult concepts is the natural process of human learning. Spiking Neural Networks (SNNs) aim to mimic the way humans process information, but current SNNs models treat all samples equally, which does not align with the principles of human learning and overlooks the biological plausibility of SNNs. To address this, we propose a CL-SNN model that introduces Curriculum Learning(CL) into SNNs, making SNNs learn more like humans and providing higher biological interpretability. CL is a training strategy that advocates presenting easier data to models before gradually introducing more challenging data, mimicking the human learning process. We use a confidence-aware loss to measure and process the samples with different difficulty levels. By learning the confidence of different samples, the model reduces the contribution of difficult samples to parameter optimization automatically. We conducted experiments on static image datasets MNIST, Fashion-MNIST, CIFAR10, and neuromorphic datasets N-MNIST, CIFAR10-DVS, DVS-Gesture. The results are promising. To our best knowledge, this is the first proposal to enhance the biologically plausibility of SNNs by introducing CL

The miR-1204 regulates apoptosis in NSCLC cells by targeting DEK

Introduction. This study endeavors to analyze the effects of miR-1204 on the expression of DEK oncogene in non-small cell lung cancer (NSCLC) cell lines and to study the molecular mechanisms of these effects. Material and methods. The miR-1204 mimics and inhibitors were transfected into the (A549 and SPC) NSCLC cells. Then the mRNA levels, cell viability, apoptosis rate, morphology and caspase activity were determined. The expression of apoptosis-related proteins Bcl-2 and Bax was also analyzed. Results. In NSCLC cell lines (A549 and SPC), DEK mRNA levels were down-regulated in miR-1204 overex­pression group. In miR-1204 inhibition group, the expression of DEK mRNA showed an opposite trend. The overexpression of miR-1204 increases the apoptosis rate in NSCLC cells. The Bcl-2 levels in the miR-1204 over­expression group were decreased, while the Bax level was increased. In the miR-1204 inhibition group, expression of Bcl-2 and Bax showed opposite trends. Cell staining revealed cell’s morphological changes; the apoptosis in the miR-1204 overexpression group revealed significant morphological features, such as brighter nuclei and nu­clear condensation. Results indicated a typical characteristic of apoptosis in the miR-1204 overexpression group. Caspase-9 and Caspase-3 were involved in the apoptosis pathway, which was mediated by miR-1204 and DEK. Conclusions. The miR-1204 induces apoptosis of NSCLC cells by inhibiting the expression of DEK. The mech­anism of apoptosis involves down-regulation of Bcl-2 and up-regulation of Bax expression. Moreover, the apoptosis was mediated by mitochondria-related caspase 9/3 pathway

Determination of chromosomal ploidy in Agave ssp.

Chromosome observation is necessary to elucidate the structure, function and organization of Agave plants’ genes and genomes. However, few researches about chromosome observation of Agave ssp. were done, not only because their chromosome numbers are large, but also because their ploidies are complicated. The root tips of 19 Agave ssp. germplasms were used as materials for determining their chromosomal ploidies. Through normal pre-treatment, fixation, digesting and Giemsa staining, the glass slides with expelled cells on them were obtained. Observed with a light microscope, the results showed that 10 germplasms are diploids, including 4 wild species and a local variety which are good parents for cross-breeding. The main cultivar in China A.hybrid cv NO 11648 is also a diploid. A. cantala Roxb used as parent for disease-resistant breeding is a triploid. A. hybrid cv nanya NO.1 and A. hybrid cv nanya NO.2 are tetraploids. The other germplasms belong to polyploids. Although three germplasms’ ploidies were reported before, the other 16 germplasms’ were first reported in this paper. These results will provide theoretical basis for cross-breeding