Histone methylation in eukaryotes is one of the key posttranslational modifications in epigenetic regulation. Human lysine specific demethylase 1 (LSD1), which demethylates not only histone H3 lysines 4 and 9 but also non-histone proteins, is involved in the regulation of developmental processes. LSD1 also acts as an oncogene to promote cancer cell proliferation. Arabidopsis thaliana has four LSD homologs, which are involved in flowering, root development, circadian rhythm, DNA damage, pathogen resistance and shoot regeneration. Here, we summarize the roles of LSD family members in various biological processes.
Heat shock proteins (Hsps) are molecular chaperones that respond to various external and internal cellular stresses. Hsp90 is an abundant cellular heat shock protein. It has two isoforms, Hsp90α and Hsp90β. In fish, expression of the isoforms is augmented by various stress signals, including thermal change, salinity, pH, ammonia, infection, and environmental pollutants. In this study, we isolated both isoforms of Hsp90, designated rkHsp90α and rkHsp90β, from the liver of Kumgang fat minnow, Rhynchocypris kumgangensis, a small freshwater fish that is endemic to Korea. Sequences of the isolated isoforms showed homology with the corresponding isoforms of teleost Hsp90. Both isoforms of rkHsp90 were highly expressed in the liver compared to other tissues, including brain, gastrointestinal tract, gills, and muscle. Water temperature elevation induced increased hepatic and muscular expression of rkHsp90α, but not rkHsp90β. Both isoforms did not respond to lipopolysaccharide challenges. Exposure to environmental pollutants promoted expression of rkHsp90β, but not rkHsp90α. The collective findings support the proposal that rkHsp90α and rkHsp90β act as molecular chaperones that respond to distinct cellular stresses. Both could serve as useful biomarkers for assessing cellular stress in Kumgang fat minnow.
Capsaicin and its analogs, which are collectively called capsaicinoids, are pungent components that are produced only in Capsicum species. Several reports have indicated that chili peppers start accumulating capsaicinoids in fruits approximately 20 days after flowering (DAF), with capsaicinoid levels continuing to increase until 40 DAF and then decreasing. In this study, a Capsicum baccatum cultivar was analyzed to investigate capsaicinoid accumulation and the morphological changes to capsaicinoid-producing cells in maturing fruits. Capsaicinoids accumulated and capsaicinoid-producing cells were detected at 10 DAF. Additionally, the capsaicinoid contents increased during the fruit development stage. At 40 DAF, the nuclear shape was unclear, and cytoplasm appears to condense in C. baccatum.
Piper nigrum is an important age-old herbal plant of the family Piperaceae. Chromosomal analysis a part of genomic research to conserve plant genetic resources has confronted difficulties in this particular species with conventional methods primarily due to its very small chromosome size and rich cytoplasmic contents. Different chromosome number from 2n=52 to 128 have been reported in this species. A reassessment of chromosome analysis not attempted earlier with aerial roots and enzymatic maceration and air drying (EMA) method has been standardized in this species. Well scattered cytoplasm free metaphase plates stained with Giemsa revealed 2n=52 very small chromosomes. Total chromosome length attains to 75.36±011 µm. Most chromosome pairs except one ranged from 0.99 to 1.81 µm. Karyotype formula is determined as 6M+26m+20sm and accordingly, idiogram is constructed. Fluorochrome banding with two contrasting nucleic acid dye DAPI and CMA provided positive signals for both of the stains on the very small chromosomes. The standardized EMA method and fluorochrome banding is repeatable and will help to evaluate other important species and genus within this family for the conservation of plant genetic resources.
Dihaploid Thelypteris decursive-pinnata (2n=2x=60) was produced artificially from tetraploid T. decursive-pinnata (2n=4x=120) by induced apogamy. In the spore mother cells of dihaploid sporophytes, many bivalent chromosomes (maximum 30 bivalents) and some univalent chromosomes were observed at metaphase I. Lagging chromosomes were frequently observed at anaphase I and anaphase II, and in most of the sporangia many young normal and abnormal spores were observed. The meiotic chromosome behavior might indicate that the donor T. decursive- pinnata is autotetraploid.
The genus Chlorella is a well-known member of the green algal class Trebouxiophyceae, which is characterized by an immotile and asexual life cycle. Here, we performed an analysis of the whole genome and transcriptome of Parachlorella kessleri NIES-2152 with emphasis on the evolution of meiosis and the flagellar proteins. The Parachlorella transcriptomic data showed that the MID-related RWP-RK genes and meiosis-specific and flagellar proteins were expressed; at the transcriptional level, the DNA repair protein RAD50 was upregulated in the stationary phase, with four-fold more reads per kilobase of transcript per million mapped reads (RPKM) compared with the early stage of culture. In contrast, radial spoke protein genes were down-regulated in the stationary phase. These results suggest that genes for meiotic and flagellar proteins are culture stage-dependent and retain their functions. We presume that the algae lost some of the genes for meiosis and the flagella during asexual evolution, but other genes still possess biological functions other than those related to the flagellum and meiosis.
The chromosomal data (chromosome number and morphology, Ag-NOR and C-banding patterns) of endemic Luciobarbus kottelati was presented from Turkey. The diploid chromosome number was found to be 2n=100. The karyotype consisted of nine pairs of metacentric, 17 pairs of submetacentric and 24 pairs of subtelo-acrocentric chromosomes (Fundamental number, Fn=152). Evident C-bands were on the pericentromeric regions of three chromosome pairs. The number of Ag-NOR bearing chromosomes varied from two to six. This study is a contribution to barbels chromosomal knowledge.
In Xenopus laevis embryos, gastrulation involves external and internal dynamic cell movements and rearrangements. However, the exact position of the internal archenteron when the external yolk plug closes remains unknown. In this study, we observed the position of the yolk plug and archenteron during gastrulation in X. laevis. The yolk plug closed on average at a position 22° ventral to the vertical or gravity axis of the late gastrula. We also demonstrated that the proximal end of the archenteron cavity, the gastrocoel, was always located on the gravity axis, although the shape and length of the archenteron varied among embryos. This is the first report showing that the position of the archenteron can be determined by the position of the proximal end of the gastrocoel when the yolk plug closes. In addition, time-lapse analysis of live embryos revealed that embryo rotation changed the position of the future neural tube between the late gastrula and neurula stages. Our results present an intermediate model between the classical model and a recently proposed model for amphibian gastrulation.
The formation of shoot branches plays a key role in plant development. Here, we show that ORYZA SATIVA HOMEOBOX1 (OSH1), a member of class I knotted-like homeobox (KNOX) genes, is involved in shoot branching in rice (Oryza sativa). During axillary bud formation, OSH1 began to be expressed in the presumptive region of the axillary meristem, and continued its expression in the established axillary meristem. In the osh1 mutant, axillary meristem formation was impaired, resulting in a failure in tiller formation. Considering a suggested role of OSH1 in the shoot apical meristem, OSH1 is likely to play an important role in maintaining undifferentiated cells during axillary bud formation.
In higher plants, ultraviolet (UV)-B irradiation induces DNA damage and inhibits DNA replication, and this subsequently inhibits plant growth. However, the specific responses of plant cells to UV-B stress remain largely unknown. Previously, we found that low-doses of UV-B irradiation-induced morphological changes in cultured plant cells and nuclei, using an evaluation system with tobacco Bright Yellow-2 (BY-2) cells. In this study, we quantified the effects of UV-B stress on transgenic BY-2 cells, by visualizing the nuclei in living cells using a fluorescent protein marker. The UV-B irradiated cells and their nuclei were enlarged 1–4 days after irradiation. We also observed significant size changes in the nuclei and cells 1–2 days after irradiation, with rates of increase of 131.36 and 138.42%, respectively. The ratio of nuclear sizes in the UV-B–irradiated cells was similar to the ratio of nuclear sizes found in the S and G2 phases of the cell cycle. We suggest that low-doses of UV-B induce moderate increases of the nuclei and cell volumes through cell cycle arrest.
The Passiflora coriacea complex encompasses the species P. megacoriacea K.Port.-Utl., P. coriacea Juss and P. sexocellata Schltdl, and the morphological similarities among the species have posed challenges for taxonomic and phylogenetic studies in the past. Image cytometry (ICM) has been used to improve the karyotype characterization in some plant species and has allowed the identification of small variations in the DNA content between homomorphic chromosomes. The aim of the present study was to determine the chromosome number, characterize the karyotype and measure the chromosomal DNA content in P. megacoriacea using classical cytogenetic and ICM approaches. We observed a chromosome number of 2n=12, with the chromosomes 1–3 and 5 classified as submetacentric and chromosomes 4 and 6 as metacentric in all metaphase plates. The nuclear DNA content (1C=0.51 pg) was measured by ﬂow cytometry and then distributed proportionally to mean integrated optical density values calculated by ICM from Feulgen stained chromosomes. So, the mean 1C chromosomal DNA content varied of 0.129 pg for chromosome 1 to 0.054 pg for chromosome 6. We can thus establish that the ensemble analysis of qualitative and quantitative parameters allowed us the first karyotype characterization of P. megacoriacea, providing data to a better taxonomic delimitation among the species of the P. coriacea Juss complex.
Polyploidy induction is expected to increase its breeding potential. Cucumber, Cucumis sativus L. (2n=2x=14), is one of important vegetable worldwide. The objective of this work was to develop autotetraploids three ecotypes of cucumber through colchicine and to reveal their phenotypic characterization. Autotetraploid plants were produced by colchicine using the treatment method to shoot apexes of seedlings with different concentrations (0, 0.1%, 0.2%, and 0.3%) and treated times (3, 5 and 7 applications). The treatment with 0.2% colchicine for 5 or 7 times and 0.3% colchicine for 5 times were proved to be more effective in producing autotetraploids. Candidate polyploids were preliminarily screened by morphological characteristics and stomatal apparatus, then detected by flow cytometry and confirmed by chromosome counting. As expected, the chromosome number was 2n=2x=14 in diploids, and 2n=4x=28 in the autotetraploid. The genome size was not altered in the second-generation progeny from all plants analyzed by flow cytometry. The tetraploid plants were accompanied by larger leaf size, flower diameter, stoma size, pollen grains and more chloroplast number in guard cell, but decrease in stoma, fruit size, and percentage of normal pollen. This study established an efficient method for the induction and identification of autotetraploids in cucumber.
The karyotype of Calliandra grandiflora from a population of Mexico is described. The karyotypic formula of 2n=22=4m+18st is the first for a species of the genus. The predominance of subtelocentric chromosomes (st) and the index of asymmetry (TF)=25.05±1.03 described an asymmetric karyotype not registered so far in the tribe Ingeae. The majority of the short arms in st chromosomes exhibited structures of similar appearance to the secondary constrictions, present even in the first pair, but not in the smallest. In addition, the prophase nuclei showed up to 12 protuberances that could correspond to such structures whose origin and nature are discussed in light of probable chromosomal fission events.
Achyranthes aspera, known as Latjeer, is a medicinally as well as an economically important plant and shows a lot of cytomorphological diversity. Keeping this status in consideration, the present attempt was made to study the detailed meiotic course in 12 plants of A. aspera collected from different areas of North India. The meiotic analysis depicts the presence of two cytotypes with 2n=28 and 42. The chromosome number of 2n=42 confirms the previous reports whereas the 2n=28 is a new chromosome number. The meiotic behavior in 4x and 6x plants may suggest their allopolyploid nature.