Putative phosphorylation sites on WCA domain of HA2 is essential for <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> single nucleopolyhedrovirus replication

Protein phosphorylation is one of the most common post-translational modification processes that play an essential role in regulating protein functionality.The Helicoverpa armigera single nucleopolyhedrovirus (HearNPv) orf2-encoded nucleocapsid protein HA2 participates in orchestration of virus-induced actin polymerization through its WCA domain,in which phosphorylation status are supposed to be critical in respect to actin polymerization.In the present study,two putative phosphorylation sites (232Thr and 250Ser) and a highly conserved Serine (245Ser) on the WCA domain of HA2 were mutated,and their phenotypes were characterized by reintroducing the mutated HA2 into the HearNPV genome.Viral infectivity assays demonstrated that only the recombinant HearNPV bearing HA2 mutation at 245Ser can produce infectious virions,both 232Tbr and 250Ser mutations were lethal to the virus.However,actin polymerization assay demonstrated that all the three viruses bearing HA2 mutations were still capable of initiating actin polymerization in the host nucleus,which indicated the putative phosphorylation sites on HA2 may contribute to HearNPV replication through another unidentified pathway.     

White spot syndrome virus induces metabolic changes resembling the warburg effect in shrimp hemocytes in the early stage of infection

The Warburg effect is an abnormal glycolysis response that is associated with cancer cells. Here we present evidence that metabolic changes resembling the Warburg effect are induced by a nonmammalian virus. When shrimp were infected with white spot syndrome virus (WSSV), changes were induced in several metabolic pathways related to the mitochondria. At the viral genome replication stage (12 h postinfection [hpi]), glucose consumption and plasma lactate concentration were both increased in WSSV-infected shrimp, and the key enzyme of the pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G6PDH), showed increased activity. We also found that at 12 hpi there was no alteration in the ADP/ATP ratio and that oxidative stress was lower than that in uninfected controls. All of these results are characteristic of the Warburg effect as it is present in mammals. There was also a significant decrease in triglyceride concentration starting at 12 hpi. At the late stage of the infection cycle (24 hpi), hemocytes of WSSV-infected shrimp showed several changes associated with cell death. These included the induction of mitochondrial membrane permeabilization (MMP), increased oxidative stress, decreased glucose consumption, and disrupted energy production. A previous study showed that WSSV infection led to upregulation of the voltage-dependent anion channel (VDAC), which is known to be involved in both the Warburg effect and MMP. Here we show that double-stranded RNA (dsRNA) silencing of the VDAC reduces WSSV-induced mortality and virion copy number. For these results, we hypothesize a model depicting the metabolic changes in host cells at the early and late stages of WSSV infection.     

Dermal β-catenin activity in response to epidermal Wnt ligands is required for fibroblast proliferation and hair follicle initiation

Dermal fibroblasts are required for structural integrity of the skin and for hair follicle development. Uniform Wnt signaling activity is present in dermal fibroblast precursors preceding hair follicle initiation, but the functional requirement of dermal Wnt signaling at early stages of skin differentiation and patterning remains largely uncharacterized. We show in mice that epidermal Wnt ligands are required for uniform dermal Wnt signaling/β-catenin activity and regulate fibroblast cell proliferation and initiation of hair follicle placodes. In the absence of dermal Wnt signaling/β-catenin activity, patterned upregulation of epidermal β-catenin activity and Edar expression are absent. Conversely, forced activation of β-catenin signaling leads to the formation of thickened dermis, enlarged epidermal placodes and dermal condensates that result in prematurely differentiated enlarged hair follicles. These data reveal functional roles for dermal Wnt signaling/β-catenin in fibroblast proliferation and in the epidermal hair follicle initiation program.     

A global alfalfa diversity panel reveals genomic selection signatures in Chinese varieties and genomic associations with root development

Alfalfa (Medicago sativa L.) is an important forage crop worldwide. However, little is known about the effects of breeding status and different geographical populations on alfalfa improvement. Here, we sequenced 220 alfalfa core germplasms and determined that Chinese alfalfa cultivars form an independent group, as evidenced by comparisons of F_ST values between different subgroups, suggesting that geographical origin plays an important role in group differentiation. By tracing the influence of geographical regions on the genetic diversity of alfalfa varieties in China, we identified 350 common candidate genetic regions and 548 genes under selection. We also defined 165 loci associated with 24 important traits from genome-wide association studies. Of those, 17 genomic regions closely associated with a given phenotype were under selection, with the underlying haplotypes showing significant differences between subgroups of distinct geographical origins. Based on results from expression analysis and association mapping, we propose that 6-phosphogluconolactonase (MsPGL) and a gene encoding a protein with NHL domains (MsNHL) are critical candidate genes for root growth. In conclusion, our results provide valuable information for alfalfa improvement via molecular breeding.     

植酸酶及其热稳定性研究进展

植酸酶能降解植物性饲料中的植酸盐类,释放出无机磷酸,对于提高饲料中磷的利用率,减轻畜禽高磷排泄物对环境的污染以及促进单胃动物对饲料中矿质营养的吸收利用有重要作用,因此植酸酶的研究有重要的科学和实用价值。获得高活性高热稳定性的植酸酶是近年来植酸酶工业的研究热点和难点,综述了植酸酶及其热稳定性研究的现状和提高植酸酶热稳定性方法的最新进展 。     

Highly efficient and inducible DNA excision in transgenic silkworms using the FLP/<Emphasis Type="Italic">FRT</Emphasis> site-specific recombination system

Efficient and inducible recombinase-mediated DNA excision is an optimal technology for automatically deleting unwanted DNA sequences, including selection marker genes. However, this methodology has yet to be established in transgenic silkworms. To achieve efficient and inducible FLP recombinase-mediated DNA excision in transgenic silkworms, one transgenic target strain (TTS) containing an FRT-flanked silkworm cytoplasmic actin 3 gene promoter (A3)-enhanced green fluorescent protein (EGFP) expression cassette, as well as two different types of FLP recombinase expression helper strains were generated. Then, the FLP recombinase was introduced into the TTS silkworms by pre-blastoderm microinjection and sexual hybridization. Successful recombinase-mediated deletion of the A3-EGFP expression cassette was observed in the offspring of the TTS, and the excision efficiencies of the FLP expression vector and FLP mRNA pre-blastoderm microinjection were 2.38 and 13.3 %, respectively. The excision efficiencies resulting from hybridization between the TTS and the helper strain that contained a heat shock protein 70 (Hsp70)-FLP expression cassette ranged from 32.14 to 36.67 % after heat shock treatment, while the excision efficiencies resulting from hybridization between the TTS and the helper strain containing the A3-FLP expression cassette ranged from 97.01 to 100 %. These results demonstrate that the FLP/FRT system can be used to achieve highly efficient and inducible post-integration excision of unwanted DNA sequences in transgenic silkworms in vivo. Our present study will facilitate the development and application of the FLP/FRT system for the functional analysis of unknown genes, and establish the safety of transgenic technologies in the silkworm and other lepidopteran species.     

New species of Nepalomyia henanensis species group from China(Diptera: Dolichopodidae: Peloropeodinae)

Three new species of Nepalomyia henanensis species group are described from China, N. damingshanus sp. nov., N. dongae sp. nov., and N. shennongjiaensis sp. nov. A key to known species of this species group is presented.     

Top3α Is Required during the Convergent Migration Step of Double Holliday Junction Dissolution

Although Blm and Top3α are known to form a minimal dissolvasome that can uniquely undo a double Holliday junction structure, the details of the mechanism remain unknown. It was originally suggested that Blm acts first to create a hemicatenane structure from branch migration of the junctions, followed by Top3α performing strand passage to decatenate the interlocking single strands. Recent evidence suggests that Top3α may also be important for assisting in the migration of the junctions. Using a mismatch-dHJ substrate (MM-DHJS) and eukaryotic Top1 (in place of Top3α), we show that the presence of a topoisomerase is required for Blm to substantially migrate a topologically constrained Holliday junction. When investigated by electron microscopy, these migrated structures did not resemble a hemicatenane. However, when Blm is together with Top3α, the dissolution reaction is processive with no pausing at a partially migrated structure. Potential mechanisms are discussed.     

miR-10a Regulates Proliferation of Human Cardiomyocyte Progenitor Cells by Targeting GATA6

microRNAs (miRNAs) play essential roles in cardiogenesis. The altered expression of miRNAs can result in cardiac malformations by inducing abnormalities in the behavior of cardiac cells. However, the role of miR-10a in the regulation of cardiomyocyte progenitor cells (CMPCs) remains undetermined. In the present study, we found that up- or down-regulation of miR-10a inhibited or promoted the proliferation of human CMPCs, respectively, without affecting their differentiation toward cardiomyocytes. miR-10a bound to GATA6 directly and reduced GATA6 expression. Over-expression of GATA6 greatly attenuated the miR-10a-mediated inhibitory effect on the proliferation of human CMPCs. Thus, our results indicate that miR-10a could effectively modulate the proliferation of human CMPCs by targeting GATA6. The finding provides novel insights into the potency of miR-10a during heart development.     

甘蔗抗逆细胞系选择及其生化特性的研究

利用脯氨酸类似物羟脯氨酸(Hyp)的生长抑制作用,筛选出抗Hyp的甘蔗(Saccha-rum sinensis Roxb)细胞变异系R932。抗性系体内游离脯氨酸含量超常积累(×3．2)。而且其体内脯氨酸合成途径中的关键酶γ－谷氨酸激酶对脯氨酸的反馈抑制较不敏感。R932抗PEG和低温能力较供体加强。实验结果表明γ－谷氨酸激酶特性的变化可能导致细胞内脯氨酸的过量积累,脯氨酸的过量积累有利于植物细胞对抗恶劣环境。