SummaryA total of 2 542 lincRNAs were identified from Populus trichocarpa and some of them play key roles in drought stress tolerance or regulate microRNA through target mimicry patterns.

In this study, the prevalence of Enterocytozoon bieneusi in China was investigated. Twelve genotypes of E. bieneusi were identified, of which 10 were novel genotypes. Further, 41.6% of the genotypes were found in both humans and animals. This is the first report of E. bieneusi in China.Microsporidia are a diverse group of obligate intracellular pathogens consisting of approximately 1,300 formally described species in 160 genera that infect a wide range of invertebrate and vertebrate hosts, including humans (8,16). Enterocytozoon bieneusi, the most frequently diagnosed microsporidial species in humans, was first reported in an AIDS patient in 1985 (4). Over the last 2 decades, E. bieneusi has been detected in humans, other mammals, and birds in more than 30 countries (1,6,10,12). However, the prevalence of this parasite in China has been unclear.Currently, sequencing of the internal transcribed spacer (ITS) region of the rRNA gene is regarded as the standard method for species identification and genotyping of E. bieneusi isolates (17). More than 90 genotypes or variants of E. bieneusi that infect humans and animals have been identified (16). Recent molecular epidemiological studies indicated that some genotypes are host specific (17). Further, 8 genotypes (WL15, D, Peru6, EbpC, Peru10, Peru16, WL11, and Type IV) have been found in both humans and animals, indicating the potential for zoonotic transmission and the importance for surveillance of the epidemiology of E. bieneusi (17).We investigated the prevalence of E. bieneusi infection in humans and animals in China. A total of 220 fecal samples were collected. Among them, 40 fecal samples were from diarrheal children in the First Hospital of Jilin University in Changchun City, northeast China, 61 were from pigs in a livestock production facility, 26 were from dogs in a pet market, and 93 were from cows. Both human and animal samples were collected in the same area around Changchun City; however, the human samples were not from the same farm as the animal samples. The collection of human and animal stool samples was approved by the Ethics Committee of the Institute of Zoonosis, Jilin University. DNA was extracted from each fecal sample with a modified protocol as described previously (7).A nested PCR with primers based on the specific ITS sequences of E. bieneusi was applied for pathogen identification as previously reported (2, 5). E. bieneusi ITS sequences were determined, and a multiple alignment was performed using the ClustalX program. To assess the extent of genetic diversity and evolutionary relationships among the previously known genotypes of Enterocytozoon spp. and the novel genotypes, a neighbor-joining tree based on the evolutionary distances calculated by the Kimura two-parameter model (15) was constructed using the MEGA 4.0 program (19).E. bieneusi-specific sequences were amplified from 56 of the 220 fecal samples (9 from humans, 2 from dogs, 35 from cows, and 10 from pigs) ( Table 1). The 56 sequences were classified into 12 genotypes, which include...

The plant-specific GRAS/SCL transcription factors play diverse roles in plant development and stress responses. In this study, a poplar SCL gene, PeSCL7, was functionally characterized in Arabidopsis thaliana, especially with regard to its role in abiotic stress resistance. Expression analysis in poplar revealed that PeSCL7 was induced by drought and high salt stresses, but was repressed by gibberellic acid (GA) treatment in leaves. Transient expression of GFP-PeSCL7 in onion epidermal cells revealed that the PeSCL7 protein was localized in the nucleus. Transgenic Arabidopsis plants overexpressing PeSCL7 showed enhanced tolerance to drought and salt treatments. The activity of two stress-responsive enzymes was increased in transgenic seedlings. Taken together, these results suggest that PeSCL7 encodes a member of the stress-responsive GRAS/SCL transcription factors that is potentially useful for engineering drought- and salt-tolerant trees.

BackgroundDNA methylation is an important biological form of epigenetic modification, playing key roles in plant development and environmental responses.ResultsIn this study, we examined single-base resolution methylomes of Populus under control and drought stress conditions using high-throughput bisulfite sequencing for the first time. Our data showed methylation levels of methylated cytosines, upstream 2kp, downstream 2kb, and repeatitive sequences significantly increased after drought treatment in Populus. Interestingly, methylation in 100 bp upstream of the transcriptional start site (TSS) repressed gene expression, while methylations in 100-2000bp upstream of TSS and within the gene body were positively associated with gene expression. Integrated with the transcriptomic data, we found that all cis-splicing genes were non-methylated, suggesting that DNA methylation may not associate with cis-splicing. However, our results showed that 80% of trans-splicing genes were methylated. Moreover, we found 1156 transcription factors (TFs) with reduced methylation and expression levels and 690 TFs with increased methylation and expression levels after drought treatment. These TFs may play important roles in Populus drought stress responses through the changes of DNA methylation.ConclusionsThese findings may provide valuable new insight into our understanding of the interaction between gene expression and methylation of drought responses in Populus.

BackgroundMicroRNAs (miRNAs) are endogenous small RNAs (sRNAs) with a wide range of regulatory functions in plant development and stress responses. Although miRNAs associated with plant drought stress tolerance have been studied, the use of high-throughput sequencing can provide a much deeper understanding of miRNAs. Drought is a common stress that limits the growth of plants. To obtain more insight into the role of miRNAs in drought stress, Illumina sequencing of Populus trichocarpa sRNAs was implemented.ResultsTwo sRNA libraries were constructed by sequencing data of control and drought stress treatments of poplar leaves. In total, 207 P. trichocarpa conserved miRNAs were detected from the two sRNA libraries. In addition, 274 potential candidate miRNAs were found; among them, 65 candidates with star sequences were chosen as novel miRNAs. The expression of nine conserved miRNA and three novel miRNAs showed notable changes in response to drought stress. This was also confirmed by quantitative real time polymerase chain reaction experiments. To confirm the targets of miRNAs experimentally, two degradome libraries from the two treatments were constructed. According to degradome sequencing results, 53 and 19 genes were identified as targets of conserved and new miRNAs, respectively. Functional analysis of these miRNA targets indicated that they are involved in important activities such as the regulation of transcription factors, the stress response, and lipid metabolism.ConclusionsWe discovered five upregulated miRNAs and seven downregulated miRNAs in response to drought stress. A total of 72 related target genes were detected by degradome sequencing. These findings reveal important information about the regulation mechanism of miRNAs in P. trichocarpa and promote the understanding of miRNA functions during the drought response.

Secondary cell wall (SCW) biosynthesis is the biological process that generates wood, an important renewable feedstock for materials and energy. NAC domain transcription factors, particularly Vascular-Related NAC-Domain (VND) and Secondary Wall-Associated NAC Domain (SND) proteins, are known to regulate SCW differentiation. The regulation of VND and SND is important to maintain homeostasis for plants to avoid abnormal growth and development. We previously identified a splice variant, , derived from as a dominant-negative regulator, which suppresses the transactivation of all family members. PtrSND1-A2 also suppresses the self-activation of the PtrSND1 family members except for its cognate transcription factor, PtrSND1-A2, suggesting the existence of an unknown factor needed to regulate Here, a splice variant, , derived from was discovered that suppresses the protein functions of all family members. PtrVND6-C1 also suppresses the expression of all members, including, demonstrating that PtrVND6-C1 is the previously unidentified regulator of We also found that PtrVND6-C1 cannot suppress the expression of its cognate transcription factor, is suppressed by PtrSND1-A2 Both PtrVND6-C1 and PtrSND1-A2 cannot suppress their cognate transcription factors but can suppress all members of the other family. The results indicate that the splice variants from the and family may exert reciprocal cross-regulation for complete transcriptional regulation of these two families in wood formation. This reciprocal cross-regulation between families suggests a general mechanism among NAC domain proteins and likely other transcription factors, where intron-retained splice variants provide an additional level of regulation.

Mass excesses of short-lived A=2Z-1 nuclei (63)Ge, (65)As, (67)Se, and (71)Kr have been directly measured to be -46,921(37), -46,937(85), -46,580(67), and -46,320(141)  keV, respectively. The deduced proton separation energy of -90(85)  keV for (65)As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of (65)As suggest that the majority of the reaction flow passes through (64)Ge via proton capture, indicating that (64)Ge is not a significant rp-process waiting point.

Isochronous mass spectrometry has been applied to neutron-deficient 58Ni projectile fragments at the HIRFL-CSR facility in Lanzhou, China. Masses of a series of short-lived T(z)=-3/2 nuclides including 41Ti, 45Cr, 49Fe, and 53Ni have been measured with a precision of 20-40 keV. The new data enable us to test for the first time the isobaric multiplet mass equation (IMME) in fp-shell nuclei. We observe that the IMME is inconsistent with the generally accepted quadratic form for the A=53, T=3/2 quartet. We perform full space shell model calculations and compare them with the new experimental results.