In our study, the effects of water stress on photosynthesis and photosynthetic electron transport chain (PETC) were studied in several ways, including monitoring the change of gas exchange parameters, modulated chlorophyll fluorescence, rapid fluorescence induction kinetics, reactive oxygen species (ROS), antioxidant enzyme activities and D1 protein levels in apple leaves. Our results show that when leaf water potential (ψw) is above –1.5 MPa, the stomatal limitation should be the main reason for a drop of photosynthesis. In this period, photosynthetic rate (PN), stomatal conductance (Gs), transpiration rate (E) and intercellular CO2 concentration (Ci) all showed a strong positive correlation with ψw. Modulated chlorophyll fluorescence parameters related to photosynthetic biochemistry activity including maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency of PSII (ΦPSII), photochemical quenching coefficient (qP) and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennae (qL) also showed a strong positive correlation as ψw gradually decreased. On the other hand, in this period, Stern-Volmer type non-photochemical quenching coefficient (NPQ) and quantum yield of light-induced non-photochemical fluorescence quenching [Y(NPQ)] kept going up, which shows an attempt to dissipate excess energy to avoid damage to plants. When ψw was below –1.5 MPa, PN continued to decrease linearly, while Ci increased and a ‘V’ model presents the correlation between Ci and ψw by polynomial regression. This implies that, in this period, the drop in photosynthesis activity might be caused by non-stomatal limitation. Fv/Fm, ΦPSII, qP and qL in apple leaves treated with water stress were much lower than in control, while NPQ and Y(NPQ) started to go down. This demonstrates that excess energy might exceed the tolerance ability of apple leaves. Consistent with changes of these parameters, excess energy led to an increase in the production of ROS including H2O2 and O2•−. Although the activities of antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) increased dramatically and ascorbate peroxidase (APX) decreased in apple leaves with drought stress, it was still not sufficient to scavenge ROS. Consequently, the accumulation of ROS triggered a reduction of net D1 protein content, a core protein in the PSII reaction center. As D1 is responsible for the photosynthetic electron transport from plastoquinone A (QA) to plastoquinone B (QB), the capacity of PETC between QA and QB was considerably downregulated. The decline of photosynthesis and activity of PETC may result in the shortage of adenosine triphosphate (ATP) and limitation the regeneration of RuBP (Jmax), a key enzyme in CO2 assimilation. These are all non-stomatal factors and together contributed to decreased CO2 assimilation under severe water stress.

No abstract

Although Chinese has become the third largest mother tongue in both Canada and the USA, Chinese/English biliteracy development has received little attention in educational research.This article explores three Chinese-Canadian first and second graders’ biliteracy (Chinese/English reading and writing) and trilingual (Mandarin, Cantonese, and English) practices in the home milieu. Findings suggest that the home context is a crucial environment for success or failure in achieving biliteracy. All families expected their children to become biliterate and multilingual, but the three children vary in their preferences and use of different languages and literacies at home. Factors such as parents’ perceptions of their minority status in the host society, their attitudes toward the role of heritage language and their own proficiencies in the dominant language, as well as several school and societal factors, such as quality of instruction in heritage language schools, language policies in the mainstream schools, and the media, played an important role in shaping the children’s language choices and patterns of use at home. These multiple factors suggest that helping immigrant children become biliterate and multilingual is a challenging task that requires concerted efforts between parents, public schools, and community organizations.

Dysfunctions of gene transcription and translation inthe nociceptive pathways play the critical role in development and maintenance of chronic pain. Circular RNAs (circRNAs) are emerging as new players in regulation of gene expression, but whether and how circRNAs are involved in chronic pain remain elusive. We showed here that complete Freund's adjuvant-induced chronic inflammation pain significantly increased circRNA-Filip1l (filamin A interacting protein 1-like) expression in spinal neurons of mice. Blockage of this increase attenuated complete Freund's adjuvant-induced nociceptive behaviors, and overexpression of spinal circRNA-Filip1l in naive mice mimicked the nociceptive behaviors as evidenced by decreased thermal and mechanical nociceptive threshold. Furthermore, we found that mature circRNA-Filip1l expression was negatively regulated by miRNA-1224 via binding and splicing of precursor of circRNA-Filip1l (pre-circRNA-Filip1l) in the Argonaute-2 (Ago2)-dependent manner. Increase of spinal circRNA-Filip1l expression resulted from the decrease of miRNA-1224 expression under chronic inflammation pain state. miRNA-1224 knockdown or Ago2 overexpression induced nociceptive behaviors in naive mice, which was prevented by the knockdown of spinal circRNA-Filip1l. Finally, we demonstrated that a ubiquitin protein ligase E3 component n-recognin 5 (Ubr5), validated as a target of circRNA-Filip1l, plays a pivotal role in regulation of nociception by spinal circRNA-Filip1l. These data suggest that miRNA-1224-mediated and Ago2-dependent modulation of spinal circRNA-Filip1l expression regulates nociception via targeting Ubr5, revealing a novel epigenetic mechanism of interaction between miRNA and circRNA in chronic inflammation pain. Significance StatementcircRNAs are emerging as new players in regulation of gene expression. Here, we found that the increase of circRNA-Filip1l mediated by miRNA-1224 in an Ago2-dependent way in the spinal cord is involved in regulation of nociception via targeting Ubr5. Our study reveals a novel epigenetic mechanism of interaction between miRNA and circRNA in chronic inflammation pain.

No abstract

To counter the "grand narratives" of the model minority myth, this study unveils the stories of a Chinese immigrant family who are encountering difficulties with schooling. The study demonstrates a complex interrelationship between home literacy, culture, and politics of schooling. Findings suggest that cultural mismatch theory alone cannot explain minority schoolfailure. Rather, multilevel interactions, including cultural differences, modes of incorporation, and differential power relationships between school and home, result in minority students' school difficulties.

We describe an isomerization–alternating ROMP protocol that gives linear copolymers with rigorous sequence alternation. Bicyclo[4.2.0]oct-7-ene-7-carboxamides of primary amines are isomerized in the presence of (3-BrPyr)2Cl2(H2IMes)Ru=CHPh to the corresponding bicyclo[4.2.0]oct-1(8)-ene-8-carboxamides in which the olefinic bond is tetrasubstituted. The isomerized amides undergo alternating ring-opening metathesis polymerization with cyclohexene to provide soluble and linear copolymers with molecular weights up to ∼130 kDa. This process provides efficient entry to strictly alternating copolymers that can display diverse functional groups.

No abstract