Inter-varietal sterility and fertility restoration in Oryza sativa Linn.

This study explored the underlining reproductive factors that cause sterility in rice, using hybrids obtained from crosses among landrace selections and improved varieties. The study was carried out between 2016 and 2018. Nine landrace cultivars and two improved varieties were involved in the hybridization experiment. Among the 17 putative hybrids that were obtained, only 5 were confirmed as true hybrids. Meiotic chromosome studies and pollen studies in the F1, and Mendelian segregation studies for fertility in the F2 were carried out. Some F2 lines were monitored to F3 to ascertain the level of fixation of gene combinations for fertility. The results obtained from the chromosomal studies showed that phenomena such as laggards, precocious movements, formation of multivalents, and unequal segregation to the poles are associated with pollen sterility in all - 5 hybrids, at the F1 and F2 generations. The indehiscence of anthers contributed to infertility due to pollen shortage than the fertility of the pollens themselves. Even though in males, there is a preponderance of male sterility, female sterility is also a phenomenon that is possibly contributing to inter-varietal sterility. The segregational pattern of 13:3 was observed for fertility in the F2 which suggests the inhibition of fertility by a gene in the dominant state. There was the restoration of fertility in many of the lines advanced to the F3 to up to 93 % fertility. It was, therefore, concluded from the study that landraces of rice still hold the key for the rice crop improvement and should therefore be conserved.

A PIP-mediated osmotic stress signaling cascade plays a positive role in the salt tolerance of sugarcane

Background Plasma membrane intrinsic proteins (PIPs) are plant channel proteins involved in water deficit and salinity tolerance. PIPs play a major role in plant cell water balance and responses to salt stress. Although sugarcane is prone to high salt stress, there is no report on PIPs in sugarcane. Results In the present study, eight PIP family genes, termed ScPIP1–1, ScPIP1–2, ScPIP1–3, ScPIP1–4, ScPIP2–1, ScPIP2–2, ScPIP2–4 and ScPIP2–5, were obtained based on the sugarcane transcriptome database. Then, ScPIP2–1 in sugarcane was cloned and characterized. Confocal microscopy observation indicated that ScPIP2–1 was located in the plasma membrane and cytoplasm. A yeast two-hybridization experiment revealed that ScPIP2–1 does not have transcriptional activity. Real time quantitative PCR (RT-qPCR) analysis showed that ScPIP2–1 was mainly expressed in the leaf, root and bud, and its expression levels in both below- and aboveground tissues of ROC22 were up-regulated by abscisic acid (ABA), polyethylene glycol (PEG) 6000 and sodium chloride (NaCl) stresses. The chlorophyll content and ion leakage measurement suggested that ScPIP2–1 played a significant role in salt stress resistance in Nicotiana benthamiana through the transient expression test. Overexpression of ScPIP2–1 in Arabidopsis thaliana proved that this gene enhanced the salt tolerance of transgenic plants at the phenotypic (healthier state, more stable relative water content and longer root length), physiologic (more stable ion leakage, lower malondialdehyde content, higher proline content and superoxide dismutase activity) and molecular levels (higher expression levels of AtKIN2, AtP5CS1, AtP5CS2, AtDREB2, AtRD29A, AtNHX1, AtSOS1 and AtHKT1 genes and a lower expression level of the AtTRX5 gene). Conclusions This study revealed that the ScPIP2–1-mediated osmotic stress signaling cascade played a positive role in plant response to salt stress.

First successful hybridization experiment between native European weatherfish (Misgurnus fossilis) and non-native Oriental weatherfish (M. anguillicaudatus) reveals no evidence for postzygotic barriers

The European weatherfish Misgurnus fossilis (Linnaeus, 1758) is a threatened freshwater species in large parts of Europe and might come under pressure from currently establishing exotic weatherfish species. Additional threats might arise if those species hybridize which has been questioned in previous research. Regarding the hybridization of M. fossilis × M. anguillicaudatus (Cantor, 1842), we demonstrate that despite the considerable genetic distance between parental species, the estimated long divergence time and different ploidy levels do not represent a postzygotic barrier for hybridization of the European and Oriental weatherfish. The paternal species can be easily differentiated based on external pigment patterns with hybrids showing intermediate patterns. No difference in standard metabolic rate, indicating a lack of hybrid vigour, renders predictions of potential threats to the European weatherfish from hybridization with the Oriental weatherfish difficult. Therefore, the genetic and physiological basis of invasiveness via hybridization remains elusive in Misgurnus species and requires further research. The existence of prezygotic reproductive isolation mechanisms and the fertility of F1 hybrids remains to be tested to predict the potential threats of globally invasive Oriental weatherfish species.

Expression of the Testis-Specific Serine/Threonine Kinases Suggests Their Role in Spermiogenesis of Bay Scallop Argopecten irradians

Members of the testis-specific serine/threonine kinases (Tssk) family play critical roles in spermatogenesis in vertebrates. But in mollusks, research on Tssk family is still lagging. In this study, we systematically identified Tssk family based on the genomic and transcriptomic data from a commercially important scallop Argopecten irradians and detected the spatiotemporal expression in adult gonads. Five members were identified, with the gene length varying from 1,068 to 10,729 bp and the protein length ranging from 294 to 731 aa. All the Tssks possess a serine/threonine protein kinase catalytic (S_TKc) domain. Phylogenetic analysis revealed existence of four homologs of vertebrate Tssk1/2, Tssk3, Tssk4, Tssk5, and absence of Tssk6 in the scallop. The remaining gene (Tssk7) formed an independent clade with Tssks of other mollusks and arthropods, indicating that it may be a new member of Tssk family unique to protostomes. By investigating the expression of Tssks in four developmental stages of testes and ovaries, we found all five Tssks were primarily expressed in mature testis. In situ hybridization experiment revealed the five Tssks were localized in the spermatids and spermatozoa. The testis-predominant expression of Tssk family suggests Tssks may play pivotal roles in spermiogenesis in the scallop. Our study provides basic information on the characteristics and expression profiles of Tssk family of A. irradians. To our knowledge, it represents the first comprehensive analysis of Tssk family in mollusks.

Differences in Morphology, Mitochondrial Genomes, and Reproductive Compatibility Between Two Clades of Aphelinus Mali in China

Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) in China is comprised of two clades (Shandong and Liaoning). In order to clarify the genetic relationship of them, we compared and analyzed the morphological characteristics and the mitochondrial genome of each, and ran a hybridization experiment between these clades. Morphological results showed that both males and females of the Liaoning clade were larger than Shandong clade, in terms of whole body, abdominal lengths and antennal lengths, but there were no significant differences between clades for total lengths of the middle and hind foot of females. The arrangement of the mitochondrial genomes was same in both clades, and each contained 31 genes, including 13 protein-encoded genes, 16 tRNA genes, and 2 rRNA genes. The highest AT levels among the 13 protein-coding genes for the two clades were the same gene (atp8) (Shandong clade, 91.52%; Liaoning clade, 90.91%). By hybridization and backcrossing, we found there was no cross incompatibility between these two clades of A. mali. Our results indicate that the historic geographical isolation between these two A. mali clades has not yet caused reproductive isolation of these two geographically separated populations, and they belong to the same species.

Circ-ZDHHC5 Accelerates Esophageal Squamous Cell Carcinoma Progression in vitro via miR-217/ZEB1 Axis

Circular RNA (circRNA) exhibits a covalently closed circular conformation and is structurally stable. Nevertheless, the precise effects exerted by circRNA in esophageal squamous cell carcinoma (ESCC) remains uncertain. circRNA was ascertained by a human circRNA array study and was confirmed by the quantification of reverse transcriptase polymerase reactions. A luciferase reporter, fluorescence in situ hybridization experiment was exploited to explore the interaction between circ-ZDHHC5 and miR-217. The function of circ-ZDHHC5 was determined by siRNA-mediated knockout of circ-ZDHHC5 in in vitro proliferation, migration, and invasion. circ-ZDHHC5, rather than linear ZDHHC5 mRNA, rose in the tissues of patients with ESCC, plasma, and ESCC cell lines in comparison with normal controls. Knockdown of circ-ZDHHC5 inhibited tumorigenesis in ESCC cells, and the co-transfection of si-circ-ZDHHC5 and miR-217 mimics further enhanced the above effect. Noticeably, the present study showed that circ-ZDHHC5 was an miR-217 sponge that modulated the expression of zinc finger E-box binding homeobox 1 (ZEB1), further facilitating ESCC tumorigenesis. As revealed by this study, circ-ZDHHC5 can act as a new potential circular biomarker for detecting ESCC. It provides a novel perceptivity for the treatment of ESCC suggesting that circ-ZDHHC5 could impact on ESCC progression by sponging miR-217 with ZEB1.

Interspecific hybridization of Quasipaa and genetic characteristics of hybrid tadpole

This study aims to reveal the formation mechanism of distant hybridization of Quasipaa. We collected five species of Quasipaa for hybridization experiment and raised tadpoles at three temperature groups (14 ℃, 22 ℃, and 28 ℃) and three density groups (5, 15, and 30 ind/L). We monitored the growth rate and swimming speed of the tadpoles. We also used nine microsatellite markers to evaluate genetic diversity and structure between the crossbred offspring and parents. Results suggested that the hybrid combinations of Quasipaa spinosa (♀) × Q. shini (♂) and Q. boulengeri (♀) × Q. spinosa (♂) obtained healthy crossbred offspring. Temperature and breeding density significantly affected the growth and development of purebred and crossbred tadpoles. Compared with purebred tadpoles, the hybrids showed heterosis under similar experimental conditions. The genetic diversity of the crossbred tadpoles was higher than that of the parents. Higher heterozygosity and genetic differentiation were also observed in the progeny population. A close genetic relationship was found between the offspring population and the female parent.

Interspecific hybridization of Quasipaa and genetic characteristics of hybrid tadpole

This study aims to reveal the formation mechanism of distant hybridization of Quasipaa. We collected five species of Quasipaa for hybridization experiment and raised tadpoles at three temperature groups (14 ℃, 22 ℃, and 28 ℃) and three density groups (5, 15, and 30 ind/L). We monitored the growth rate and swimming speed of the tadpoles. We also used nine microsatellite markers to evaluate genetic diversity and structure between the crossbred offspring and parents. Results suggested that the hybrid combinations of Quasipaa spinosa (♀) × Q. shini (♂) and Q. boulengeri (♀) × Q. spinosa (♂) obtained healthy crossbred offspring. Temperature and breeding density significantly affected the growth and development of purebred and crossbred tadpoles. Compared with purebred tadpoles, the hybrids showed heterosis under similar experimental conditions. The genetic diversity of the crossbred tadpoles was higher than that of the parents. Higher heterozygosity and genetic differentiation were also observed in the progeny population. A close genetic relationship was found between the offspring population and the female parent.

Emticicia sediminis sp. nov. isolated from sediment of a shallow stream

A novel bacterial strain, designated JBR12T, was isolated from sediment of a shallow stream in Cheonan, Korea. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain JBR12T belongs to the genus Emticicia, and indicated that its closest relatives are Emticicia oligotrophica DSM 17448T (97.8 % sequence similarity) and E. ginsengisoli Gsoil 085T (94.3 %). A DNA–DNA hybridization experiment revealed < 70 % genomic relatedness between strain JBR12T and E. oligotrophica DSM 17448T. The major fatty acids (>5 % of the total) were iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 3-OH, anteiso-C15 : 0 and iso-C15 : 0 3-OH. The DNA G+C content of strain JBR12T was 37.7 mol%. According to data from the present polyphasic taxonomic study, strain JBR12T represents a novel species of the genus Emticicia, for which the name Emticicia sediminis sp. nov. is proposed. The type strain is JBR12T ( = KACC 17466T = JCM 19321T).