No abstract

Ulva sp. (Chlorophyta) is a representative species of the intertidal macro-algae responsible for the green tides that occurred along the shores of Qingdao in 2008 and had detrimental effects on the preparation for the 2008 Beijing Olympic Games sailing competition. In view of its significance, we have investigated the photosynthetic performance of the photosystems and the changes in photosynthetic electron transport that occur during desiccation and rehydration of Ulva sp. The PSII activity in Ulva sp. declined gradually during the course of desiccation, which was reflected by the decreased maximum quantum yield and effective quantum yield, whereas the PSI activity fluctuated significantly. In contrast, the electron transport rates of PSII approached zero at severe levels of desiccation, but the electron transport of PSI, which still operated, could be suppressed effectively by a specific inhibitor. Furthermore, the electron transport of PSI during rehydration of desiccated thalli was recovered faster than that of PSII. All these results implied that the linear electron flow was abolished in desiccated Ulva sp., whereas the cyclic PSI activity was significantly elevated, was still active at severe levels of desiccation and could be restored faster than PSII activity. Based on these results, we concluded the PSI-driven cyclic electron flow might provide desiccation tolerance and additional flexibility for the cell physiology of Ulva sp. under desiccation conditions, which might be one of the most important factors that make Ulva sp. well suited to experience daily cycles of desiccation at low tide and rehydration at high tide.

Background: This study aimed to investigate the prevalence and associated factors of malocclusion among children with primary dentition in Xi'an, China. Methods: A total of 2,974 subjects were selected from local schools in Xi'an city using a stratified cluster sampling method from January to September 2015. After screening samples according to the inclusion criteria, the final sample size comprised 2,235 pre-school children, with a mean age of 4.82 (SD, 1.76; range, 2.63-6.12) years. Malocclusion traits were assessed by trained clinicians followed by the evaluation of associated factors through clinical examination and a precisely designed questionnaire including data regarding gender, birth place, parental education level, monthly familial income, parental attitude toward the problem of malocclusion, feeding methods of the children, feeding postures, pacifier use, and delivery methods. Data were analyzed using the Chi-square test and logistic regression analysis. Results: The most common type of malocclusion was increased overjet (34.99 %) in the sagittal direction, deep overbite (37.58 %), and midline deviation (25.32 %) in the vertical and transverse directions, respectively. The prevalence of posterior crossbite, anterior crossbite, and anterior open bite was 7.56, 6.80 and 6.98 %, respectively. The prevalence of the anterior edge-to-edge occlusion was the lowest (2.46 %). The variables associated with malocclusion (P < 0.05) were birth place (odds ratio [OR] = 1.741 with 95 % CI of 1.384-2.162), insufficient abrasion of primary canines (OR = 1.465; 95 % CI of 1.153-1.894), caries in primary teeth (OR = 2.045; 95 % CI of 1.665-2.539), tongue thrusting (OR = 2.833; 95 % CI of 1.640-3.649), mandibular prognathism (OR = 2.621; 95 % CI of 1.574-3.689), and finger sucking (OR = 1.573 with 95 % CI of 1.098-2.014). The feeding methods (OR = 3.614 with 95 % CI of 3. 087-4.596) along with the method of delivery (OR = 1.847 with 95 % CI of 1.323-2.451) have been observed to play an important role in the morbidity of malocclusion (P < 0.05). Conclusions: The prevalence of malocclusion among pre-school children in Xi'an is higher compared to that in other geographical parts of China. Therefore, early attention to the development of occlusion and necessary interventions toward the associated factors are important to reduce its prevalence and further adverse effects.

Chloroplast formation is associated with embryo development and seedling growth. However, the relationship between chloroplast differentiation and embryo development remains unclear. Five FtsHi genes that encode proteins with high similarity to FtsH proteins, but lack Zn2+-binding motifs, are present in the Arabidopsis genome. In this study, we showed that T-DNA insertion mutations in the Arabidopsis FtsHi4 gene resulted in embryo arrest at the globular-to-heart–shaped transition stage. Transmission electron microscopic analyses revealed abnormal plastid differentiation with a severe defect in thylakoid formation in the mutant embryos. Immunocytological studies demonstrated that FtsHi4 localized in chloroplasts as a thylakoid membrane-associated protein, supporting its essential role in thylakoid membrane formation. We further showed that FtsHi4 forms protein complexes, and that there was a significant reduction in the accumulation of D2 and PsbO (two photosystem II proteins) in mutant ovules. The role of FtsHi4 in chloroplast development was confirmed using an RNA-interfering approach. Additionally, mutations in other FtsHi genes including FtsHi1, FtsHi2, and FtsHi5 caused phenotypic abnormalities similar to ftshi4 with respect to plastid differentiation during embryogenesis. Taken together, our data suggest that FtsHi4, together with FtsHi1, FtsHi2, and FtsHi5 are essential for chloroplast development in Arabidopsis.

Enteromorpha prolifera (Muell.) J. Agardh (Chlorophyta, Ulvophyceae), which is distributed widely in the inter-tidal zone of the ocean, is one of the most common fouling green algae. However, the present understandings of the life history of E. prolifera have been insufficient to explain their seasonal abundances. Thus it is essential to investigate how many reproductive strategies are likely to contribute to the successful colonization and flourishing of the green alga. In the present study the reproduction diversity of E. prolifera was observed and studied systematically by culturing chopped tissues. Our results showed that there are in total seven pathways of reproduction for E. prolifera including sexual, asexual and vegetative reproduction. It was indicated that the variety of the reproductive ways and the large quantity of reproductive cells produced and released during the reproductive season are the two key factors that facilitate colonization of E. prolifera. The reproduction of the alga E. prolifera mainly depends on asexual methods. The results presented here contribute to increasing our understanding about how the opportunistic macroalgae successfully maintain colonization and excessive growth.

No abstract

Gliomas are common malignant tumors of the human neural system, and Wnt signaling activation is closely related to glioma malignancy. Human Pygopus 2 (Pygo2) was recently discovered to be a component of the Wnt signaling pathway, which is required for β-catenin/Tcf-dependent transcription. However, the role of Pygo2 in glioblastoma cell growth and survival remains uncertain. In the present study, Pygo2 expression was evaluated in 80 glioma tissue samples. Results demonstrated that tumor grade exhibited a positive correlation with overexpression of Pygo2. In addition, small hairpin RNA (shRNA) was used to specifically knockdown Pygo2 expression in human glioblastoma U251 cell lines. Results showed that inhibition of Pygo2 expression resulted in inhibited cell proliferation and invasiveness, as well as increased cell cycle arrest at the G(1) stage and decreased expression of the Wnt target gene cyclin D1. These results demonstrated that Pygo2 was highly expressed in glioma tissue and required for growth of glioblastoma cells.

The complete nuclear ribosomal DNA (nrDNA) cistron sequence of Pyropia yezoensis has been sequenced, of which each unit is composed of the intergenic spacer (IGS), the small-subunit (SSU) ribosomal RNA (rRNA) gene, the internal transcribed spacer 1 (ITS1), the 5.8S rRNA gene, the internal transcribed spacer 2 (ITS2), and the large-subunit (LSU) rRNA gene. This cistron occurs in tandem repeats that can number in 100s to 1000s. Furthermore, in the analysis of the sequence data, we determined that introns were present in the small-subunit rRNA genes, for which the exon sequences (1834 bp) are almost identical. The intron numbers ranging from zero to two in the small-subunit rRNA genes are different between multiple individuals. However, the full length of the large-subunit rRNA genes is 4770 bp without any introns, and the 5.8S rRNA gene is 159 bp. Moreover, the 5′ and 3′ terminal sequences of the genic regions of the ribosomal cistron are extremely conservative even among various species in red alga. In addition, the range for ITS1 is 371-372 bp and for ITS2 is 532 to 535 bp. The IGS is 5984 bp in length and possesses upstream direct repeats, downstream repeats, and middle inverted repeats that make sequencing untoward. This is the first time that the complete nucleotide of the IGS region of P. yezoensis has been sequenced. The provision of the full length of nrDNA cistron will offer useful information to be widely utilized for identification, taxonomic relationships, and phylogenies in red algae.