Functional Characterization of 14 Pht1 Family Genes in Yeast and Their Expressions in Response to Nutrient Starvation in Soybean

Background

Phosphorus (P) is essential for plant growth and development. Phosphate (Pi) transporter genes in the Pht1 family play important roles in Pi uptake and translocation in plants. Although Pht1 family genes have been well studied in model plants, little is known about their functions in soybean, an important legume crop worldwide.

Principal Findings

We identified and isolated a complete set of 14 Pi transporter genes (GmPT1-14) in the soybean genome and categorized them into two subfamilies based on phylogenetic analysis. Then, an experiment to elucidate Pi transport activity of the GmPTs was carried out using a yeast mutant defective in high-affinity Pi transport. Results showed that 12 of the 14 GmPTs were able to complement Pi uptake of the yeast mutant with Km values ranging from 25.7 to 116.3 µM, demonstrating that most of the GmPTs are high-affinity Pi transporters. Further results from qRT-PCR showed that the expressions of the 14 GmPTs differed not only in response to P availability in different tissues, but also to other nutrient stresses, including N, K and Fe deficiency, suggesting that besides functioning in Pi uptake and translocation, GmPTs might be involved in synergistic regulation of mineral nutrient homeostasis in soybean.

Conclusions

The comprehensive analysis of Pi transporter function in yeast and expression responses to nutrition starvation of Pht1 family genes in soybean revealed their involvement in other nutrient homeostasis besides P, which could help to better understand the regulation network among ion homeostasis in plants.     

The role of chick Ebf genes in the mediolateral patterning of the somites

This study was conducted to check whether the three chick Early B‐cell Factor (Ebf) genes, particularly cEbf1, would be targets for Shh and Bmp signals during somites mediolateral (ML) patterning. Tissue manipulations and gain and loss of function experiments for Shh and Bmp4 were performed and the results revealed that cEbf1 expression was initiated in the cranial presomitic mesoderm by low dose of Bmp4 from the lateral mesoderm and maintained in the ventromedial part of the epithelial somite and the medial sclerotome by Shh from the notochord; while cEbf2/3 expression was induced and maintained by Bmp4 and inhibited by high dose of Shh. To determine whether Ebf1 plays a role in somite patterning, transfection of a dominant‐negative construct was carried out; this showed suppression of cPax1 expression in the medial sclerotome and upregulation and medial expansion of cEbf3 and cPax3 expression in sclerotome and dermomyotome, respectively, suggesting that Ebf1 is important for ML patterning. Thus, it is possible that low doses of Bmp4 set up Ebf1 expression which, together with Shh from the notochord, leads to establishment of the medial sclerotome and suppression of lateral identities. These data also conclude that Bmp4 is required in both the medial and lateral domain of the somitic mesoderm to keep the ML identity of the sclerotome through maintenance of cEbf gene expression. These striking findings are novel and give a new insight on the role of Bmp4 on mediolateral patterning of somites.     

Multi‐Length‐Scale Morphologies in PCPDTBT/PCBM Bulk‐Heterojunction Solar Cells

Additives are known to improve the performance of organic photovoltaic devices based on mixtures of a low bandgap polymer, poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b′]‐dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)] (PCPDTBT) and [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM). The evolution of the morphology during the evaporation of the mixed solvent, which comprises additive and chlorobenzene (CB), is investigated by in‐situ grazing incidence X‐ray scattering, providing insight into the key role the additive plays in developing a multi‐length‐scale morphology. Provided the additive has a higher vapor pressure and a selective solubility for PCBM, as the host solvent (CB) evaporates, the mixture of the primary solvent and additive becomes less favorable for the PCPDTBT, while completely solubilizing the PCBM. During this process, the PCPDTBT first crystallizes into fibrils and then the PCBM, along with the remaining PCPDTBT, is deposited, forming a phase‐separated morphology comprising domains of pure, crystalline PCPDTBT fibrils and another domain that is a PCBM‐rich mixture with amorphous PCPDTBT. X‐ray/neutron scattering and diffraction methods, in combination with UV–vis absorption spectroscopy and transmission electron microscopy, are used to determine the crystallinity and phase separation of the resultant PCPDTBT/PCBM thin films processed with or without additives. Additional thermal annealing is carried out and found to change the packing of the PCPDTBT. The two factors, degree of crystallinity and degree of phase separation, control the multi‐length‐scale morphology of the thin films and significantly influence device performance.     

在小鼠心跳骤停期间应用中度低温对复苏后抗氧化物酶活性的影响

目的：低温在许多小鼠心跳骤停后复苏模型的研究中被证实是有效的。心跳骤停后释放的氧自由基是产生继发性损伤的一个重要机制。本研究旨在探索心跳骤停期间应用中度低温对复苏后抗氧化物酶活性的影响。方法：用氯化钾诱导8min心跳骤停。此实验分为常温心跳骤停组（NCA）、低温心跳骤停组（HCA）TL对照组。HCA组在心跳骤停5min后开始降温使核心温度维持在（30．0±1．0）℃。应用胸部按压和肾上腺素来复苏。在心跳骤停两组各选择三个时间点：复苏后1h、4h和24h。测量超氧化物歧化酶（SOD）和过氧化氢酶（CAT）在心脏和肝脏的活性。结果：实验动物在HCA组比常NCA组生存率高。HCA组比NCA组复苏时间明显延长。与NCA组相比,HCA组复苏后24h的SOD活性在肝脏表达明显降低。与NCA组相比,HCA组复苏后4h的CAT活性在肝脏表达显著增高。结论：在心跳骤停过程中,与正常体温相比,应用中度低温能够提高生存率。与正常体温相比较,在心跳骤停中期间应用中度低温不影响心脏的SOD与CAT活性,应用中度低温在肝脏可延迟性抑制SOD的活性并且短暂提高CAT活性。     

天然雌核发育贵州普安鲫(A型)染色体组型的初步研究

普安鲫(Carassius auratus)原产于贵州省普安县青山镇一带的天然水体中,它有3个不同类型(A、B和C型)的种群。目前除了A型在野外未见雄性个体外,B和C型都是两性型种群,它们同地共栖,且行天然雌核发育。       

Inducible and constitutive mechanisms of salt stress resistance in <Emphasis Type="Italic">Geum urbanum</Emphasis> L.

The avens (Geum urbanum L.) seedlings were grown for 6 weeks until the expansion of five to six leaves and then exposed to salinity shock (300 mM NaCl in the nutrient medium) or to a gradual (within 4 days) increase in NaCl concentration from 100 to 400 mM. The dynamics of stress-dependent accumulation of Na⁺, Cl^?, proline, and polyamines in leaves and roots was measured, together with activities of antioxidant enzymes, namely, superoxide dismutase (SOD) and guaiacol-dependent peroxidase occurring in soluble, ionically bound, and covalently bound forms. It is shown that avens plants can adapt to gradual salinization by mobilizing stressinducible protective mechanisms (accumulation of proline and spermine) and by activating constitutive enzyme systems (SOD and peroxidase).     

Variability in nitrogen stable isotope ratios of macroalgae: consequences for the identification of nitrogen sources

In our research, we collected and analyzed numerous macroalgal specimens (738) for isotopic analysis sampled over a year at monthly intervals across 20 sites within the Urías lagoon complex, a typical subtropical coastal ecosystem located in the Gulf of California. We quantified and characterized (chemically and isotopically) the N loads received by Urías throughout a year. We studied the spatial‐temporal variation of the chemical forms and isotopic signals of the available N in the water column, and we monitored in situ different environmental variables and other hydrodynamic parameters. Multiple N sources (e.g., atmospheric, sewage, seafood processing, agriculture and aquaculture effluents) and biogeochemical reactions related to the N cycle (e.g., ammonia volatilization, nitrification and denitrification) co‐occurring across the ecosystem, result in a mixture of chemical species and isotopic compositions of available N in the water column. Increased variability was observed in the δ¹⁵N values of macroalgae (0.41‰–22.67‰). Based on our results, the variation in δ¹⁵N was best explained by spatio‐temporal changes in available N and not necessarily related to the N sources. The variability was also explained by the differences in macroalgal biology among functional groups, species and/or individuals. Although the δ¹⁵N‐macroalgae technique was a useful tool to identify N sources, its application in coastal ecosystems receiving multiple N sources, with changing environmental conditions influencing biogeochemical processes, and high diversity of ephemeral macroalgal species, could be less sensitive and have less predictive power.     

Membrane proteins organize a symmetrical virus

Alphaviruses are enveloped icosahedral viruses that mature by budding at the plasma membrane. According to a prevailing model maturation is driven by binding of membrane protein spikes to a preformed nucleocapsid (NC). The T = 4 geometry of the membrane is thought to be imposed by the NC through one-to-one interactions between spike protomers and capsid proteins (CPs). This model is challenged here by a Semliki Forest virus capsid gene mutant. Its CPs cannot assemble into NCs, or its intermediate structures, due to defective CP-CP interactions. Nevertheless, it can use its horizontal spike-spike interactions on membrane surface and vertical spike-CP interactions to make a particle with correct geometry and protein stoichiometry. Thus, our results highlight the direct role of membrane proteins in organizing the icosahedral conformation of alphaviruses.     

Two Rubisco activase isoforms may play different roles in photosynthetic heat acclimation in the rice plant

Studies on some plant species have shown that increasing the growth temperature gradually or pretreating with high temperature can lead to obvious photosynthetic acclimation to high temperature. To test whether this acclimation arises from heat adaptation of ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activation mediated by Rubisco activase (RCA), gene expression of RCA large isoform (RCA_L) and RCA small isoform (RCA_S) in rice was determined using a 4‐day heat stress treatment [40/30°C (day/night)] followed by a 3‐day recovery under control conditions [30/22°C (day/night)]. The heat stress significantly induced the expression of RCA_L as determined by both mRNA and protein levels. Correlative analysis indicated that RCA_S protein content was extremely significantly related to Rubisco initial activity and net photosynthetic rate (Pn) under both heat stress and normal conditions. Immunoblot analysis of the Rubisco–RCA complex revealed that the ratio of RCA_L to Rubisco increased markedly in heat‐acclimated rice leaves. Furthermore, transgenic rice plants expressing enhanced amounts of RCA_L exhibited higher thermotolerance in Pn and Rubisco initial activity and grew better at high temperature than wild‐type (WT) plants and transgenic rice plants expressing enhanced amounts of RCA_S. Under normal conditions, the transgenic rice plants expressing enhanced amounts of RCA_S showed higher Pn and produced more biomass than transgenic rice plants expressing enhanced amounts of RCA_L and wild‐type plants. Together, these suggest that the heat‐induced RCA_L may play an important role in photosynthetic acclimation to moderate heat stress in vivo, while RCA_S plays a major role in maintaining Rubisco initial activity under normal conditions.     

State and role of SRC family kinases in replication of herpes simplex virus 1

An earlier report showed that infected cell protein no. 0 (ICP0) of herpes simplex virus 1 (HSV-1) interacts with the SH3 domains of a recently discovered adaptor protein, CIN85. Here, we report the following. (i) ICP0 also interacts with other SH3 domain-containing proteins and, in particular, with nonneuronal members of the Src kinase family. (ii) HSV-1 infection enhanced the activating phosphorylation of Tyr416 of the members of the Src kinase family, modestly enhanced the kinase activity of Src, and posttranslationally modified at least one additional member of the Src kinase family by phosphorylation in a manner dependent on the viral gene products ICP0, unique short 3 (U(S)3), and unique long 13 (U(L)13). (iii) To define the roles of Src kinase family members, we examined the accumulation of viral proteins, DNA, and mRNA and virus yields from wild-type mouse embryo fibroblasts and sibling cells lacking Src, Fyn, and Yes (SYF-); a mutant cell line, +Src, in which Src was restored to SYF- cells; and the mutant cell line (CSK-) lacking the negative regulator Csk gene of the Src kinase family. Representative alpha, beta, and gamma2 proteins accumulated in the largest amounts in SYF- cells and the smallest amounts in +Src compared to wild-type cells. The CSK- cells yielded smaller amounts of the gamma2 protein and at least 10-fold less virus than wild-type cells. We conclude that HSV-1 proteins regulate the activities of Src family kinases to achieve optimal viral yields in the course of viral replication.