A review of target gene specificity of flavonoid R2R3-MYB transcription factors and a discussion of factors contributing to the target gene selectivity

Flavonoid biosynthetic genes are often coordinately regulated in a temporal manner during flower or fruit development, resulting in specific accumulation profiles of flavonoid compounds. R2R3-MYB-type transcription factors （TFs） ＂recruit＂ a set of biosynthetic genes to produce flavonoids, and, therefore, R2R3-MYBs are responsible for the coordinated expression of structural genes. Although a wealth of information regarding the identified and functionally characterized R2R3-MYBs that are involved in flavonoid accumulation is available to date, this is the first review on the global regulation of MYB factors in the flavonoid pathway. The data presented in this review demonstrate that anthocyanin, flavone/flavonol/3-deoxyflavonoid （FFD）, proanthocyanidin （PA）, and isoflavonoid are independently regulated by different subgroups of R2R3-MYBs. Furthermore, FFD-specific R2R3-MYBs have a preference for early biosynthetic genes （EBGs） as their target genes; anthocyanin-specific R2R3-MYBs from dicot species essentially regulate late biosynthetic genes （LBGs）; the remaining R2R3-MYBs have a wider range of target gene specificity. To elucidate the nature of the differential target gene specificity between R2R3-MYBs, we analyzed the DNA binding domain （also termed the MYB-domain） of R2R3-MYBs and the distribution of the recognition cis-elements. We identified four conserved amino acid residues located in or just before helix-3 of dicot anthocyanin R2R3-MYBs that might account for the different recognition DNA sequence and subsequently the different target gene specificity to the remaining R2R3-MYB TFs.

Recent advances in identification of male specificity determinant and its function in S-RNase-mediated gametophytic self-incompatibility

S-RNase-mediated gametophytic self-incompatibility （GSI） is controlled by a multiallelic S-locus at which two separate genes, the female （pistil） and male （pollen） specificity determinants, are tightly linked. This review described both the identification of pollen specific F-box genes, SLF/SFBs, in Antirrhinum, Petunia and Prunus species and the demonstration of SLF/SFB as pollen determinant together with their functions in GSI response. Recent studies of how the pollen determinant functions in pollination reaction revealed that pollen determinant interacted with S-RNases in a non-allele-specific manner. It targeted all of the non-self S-RNases for ubiquitination through a functional SCF complex and subsequent degradation via 26S proteasome pathway in compatible reaction. It allows pollen tube to reach into the embryo sac and to finish double fertilization. In incompatible response, the intact self S-RNases were left to function as a cytotoxin that degrades self-pollen tube RNA, resulting in the cessation of pollen tube growth.

Enhancement of mouse germ cell-associated genes expression by injection of human umbilical cord mesenchymal stem cells into the testis of chemical-induced azoospermic mice

Various methods are currently under investigation to preserve fertility in males treated with high-dose chemotherapy and radiation for malignant and nonmalignant disorders. Human umbilical cord mesenchymal stem cells （HUC-MSCs）, which possess potent immunosuppressive function and secrete various cytokines and growth factors, have the potential clinical applications. As a potential alternative, we investigate whether injection of HUC-MSCs into the interstitial compartment of the testes to promote spermatogenic regeneration efficiently. HUC-MSCs were isolated from different sources of umbilical cords and injected into the interstitial space of one testis from 10 busulfan-treated mice （saline and HEK293 cells injections were performed in a separate set of mice） and the other testis remained uninjected. Three weeks after MSCs injection, Relative quantitative reverse transcription polymerase chain reaction was used to identify the expression of 10 of germ cell associated, which are all related to meiosis, demonstrated higher levels of spermatogenic gene expression （2-8 fold） in HUC-MSCs injected testes compared to the contralateral uninjected testes （five mice）. Protein levels for germ cell-specific genes, miwi, vasa and synaptonemal complex protein （Scp3） were also higher in MSC-treated testes compared to injected controls 3 weeks after treatment. However, no different expression was detected in saline water and HEK293 cells injection control group. We have demonstrated HUC-MSCs could affect mouse germ cell-specific genes expression. The results also provide a possibility that the transplanted HUC-MSCs may promote the recovery of spermatogenesis. This study provides further evidence for preclinical therapeutic effects of HUC-MSCs, and explores a new approach to the treatment of azoospermia.

Characterization of an Organ Specific and Pathogen Responsive CC-NBS-LRR Gene from Cotton(Gossypium hirsutum L.)

Cotton diseases represent a major challenge to cotton growth.Cloning of a cotton pathogen response gene and promoter is of great importance to improve disease resistance.In this study,a

Cloning and analysing of 5' flanking region of Xenopus organizer gene noggin

Xenopus organizer specific gene Noggin possessesnearly all the characterestic properties of the action of or-ganizer to specify the embryonic body axis. To analyzehow the maternal inherited factors cofltrol its expressionpattern, we cloned the 5’ regulatory region of noggn gene.The 1.5 kb upstream sequense could direct reporter geneto express in vivo and data from deletion analysis indi-cated that a 229 base pair fragmet is essential for acti-vating noggn expression. We further demonstrated thatthe response elements within this regulatory region wereindeed under the control of growth factor activin and Wntsignaling pathway components.

Study on the Specific Gene Expression during Spermatogenesis of Rat

Objective To explore specific gene expression for regulating meiosis of germ cells during spermatogenesis of rat testis Materials & Methods Male SD rats, aged 1, 3 and 8 weeks, were observed in this study. The methods of morphological observation on testicular tissues embedded by resin and mRNA differential display (DDRT PCR) were combined to obtain specific mRNA expression gene fragments during the testicular development. Reverse dot blot hybridization was operated to further screen the positive differential DNA fragments. The positive DNA segments were sub cloned in pGEM T Easy vector and transformed into the competent E coli 109 straint. Northern blot analysis and in situ hybridization were also carried out for identifying tissue specific expression as well as cell specific expression DNA fragments. To screen λ ZAP II rat testicular gene library was searched for the original gene. Results Eighty two differential cDNA fragments were obtained through primary DDRT PCR, among which 40 differential cDNA fragments were selected for further screening with reverse dot blot hybridization. After the reverse dot blot hybridization, 12 primary differential DNA fragments were obtained. The size of DNA fragments ranged from 250 to 500 bp. The in situ hybridization of the testicular tissue showed that a specific DNA fragment derived from 8 week old rat testis, named CG14, was hybridized in adult rat testicular section, in which the positive nucleic acid signals were distributed specifically in the primary spermatocytes. Another DNA fragment derived from 1 week old rat testis, named AA11, was hybridized specifically in Sertoli cell of 1 week old rat testis. Northern blot hybridization with [α 32 P] dCTP labeled CG14 probe, including cardiac, liver, kidney, brain, testis, and epididymis tissue mRNAs of rat, showed that an mRNA specific hybridization band, size of 1.258 kb, was found in testis tissue and size of 1.531 kb of another hybridization band present in epididymis tissue. The CG14 DNA specific gene fragment existed in the λ ZAP II testis gene library. Conclusion 1. The DDRT PCR technique is a convenient tool to find the specific expression gene during spermatogenesis. 2. The CG14 DNA fragment was expressed significantly in rat testicular tissue, weakly expressed in the epididymis tissue of rat, but not found in cardiac, liver, kidney, and brain tissues. 3. The CG14 DNA fragment was specifically expressed in the primary spermatocytes and might be associated with the meiosis of the primary spermatocyte during spermatogenesis of rat. 4. The CG14 DNA fragment existed in the λ ZAP II testis gene library.

Retinoic acid enhances expression of neural specific genes in Sca-1^+ cells of mouse fetal liver through activating protein kinase C

BACKGROUND： Interstitial stem cell is charactenzed by multiple differentiations, and retinoic acid （RA） can induce differentiation of stromal cells into nerve tissue cells in fetal liver of mice, so, its signal transduction pathway should be discussed to trigger differentiation. OBJECTIVE ： To study the effect of RA on expression of neural specific gene and its signal transduction in fetal liver of mice.DESIGN ： Paired controlled study on the basis of cell.SETTING ： Institute of Hematology, Medical College of Jinan University.MATERIALS： The experiment was completed in the Institute of Hematology, Medical College of Jinan University from April to December 2005. C57BL/6 mice, of clean grade, aged 8-10 weeks, weighting 20-35 g, 10 females and 4 males, were selected in this study.METHODS： Sca-1^＋ cells in fetal liver were prepared with MACS kit and cultured with DMEM ＋ 10% fetal bovine serum （FBS）. On the fourth day, it was added with or without protein kinase C （PKC） inhibitor chelerythrine chloride （3μmol/L） and 5×10^-7 mol/L RA for 24 hours, and then incubated in serum-free medium for 5 days. Expressions of genes were assayed by Westem blotting and semi-quantitative RT-PCR.MAIN OUTCOME MEASURES ： Expression of neural specific gene NF-L, NF-H, BF-1 and TH.RESULTS： Expression of neural specific gene NF-L, NF-H, BF-1 and TH was significantly increased after treatment with RA and they were increased 5.06, 5.15, 4.63 and 3.33 times, respectively. However, chelerythrine chloride could inhibit expression of neural specific gene NF-L, NF-H, BF-1 and TH induced by RA.CONCLUSION ： RA can promote the expression of neural specific genes in Sca-1^＋ cells of fetal liver, and its pathway may be related to PKC.

Anti-tumor effects induced by gene vaccines co-expressing truncated human prostate specific membrane antigen gene and mouse 4-1BBL

Objective To investigate the influence of m4-1BBL on anti-tumor effects induced by truncated human prostate specific membrane antigen ( tPSMA ) gene in mice. Methods A eukaryotic expression plasmid encoding tPSMA and m4-1BBL ( pDC316-tPSMA-IRES m4-1BBL) ,pDC316-tPSMA and pDC316 were constructed.

Predicting the Reproduction Strategies of Several Microalgae Through Their Genome Sequences

Documenting the sex and sexual reproduction of the microalgae is very difficult, as most of the results are based on the microscopic observation that can be heavily influenced by genetic, physiological and environmental conditions. Understanding the reproduction strategy of some microalgae is required to breed them in large scale culture industry. Instead of direct observation of sex and sexual reproduction under microscope, the whole set or the majority of core meiosis genes may evidence the sex and sexual reproduction in the unicellular algae, as the meiosis is necessary for maintaining the genomic stability and the advantages of genetic recombination. So far, the available genome sequences and bioinformatic tools （in this study, homolog searching and phylogenetic analysis） allow us to propose that at least 20 core meiosis genes （among them 〉6 must be meiosis specific） are enough for an alga to maintain its sexual reproduction. According to this assumption and the genome sequences, it is possible that sexual reproduction was carried out by Micromonas pusilla and Cyanidiosehyzon merolae, while asexual reproduction was adopted by Bigelowiella natans, Guillardia theta, Nannochloropsis gaditana, N. oeeanica, Chlorella variablis, Phaeodactylum tricornutum and Thalassiosira pseu- donana. This understanding will facilitate the breeding trials of some economic microalgae （e.g., N. gaditana, N. oceanica, C. vari- ablis and P. tricornutum）. However, the reproduction strategies of these microalgae need to be proved by further biological experiments.

Comparative transcriptomes reveal the disjunction adaptive strategy of Thuja species in East Asia and North America

The genus Thuja is ideal for investigating the genetic basis of the East Asia-North America disjunction.The biogeographical background of the genus is debatable and an adaptive strategy is lacking.Through the analysis and mining of comparative transcriptomes,species differentiation and positively selected genes(PSGs)were identified to provide information for understanding the environmental adaptation strategies of the genus Thuja.De novo assembly yielded 44,397-74,252 unigenes of the five Thuja species with contig N50length ranging from 1,559 to 1,724 bp.Annotations revealed a similar distribution of functional categories among them.Based on the phylogenetic trees constructed using the transcriptome data,T.sutchuenensis was divided first,followed by T.plicata and T.occidentalis.The final differentiation of T.koraiensis and T.standishii formed a clade.Enrichment analysis indicated that the PSGs of the North American Thuja species were involved in plant hormone signal transduction and carbon fixation of photosynthetic organisms pathways.The PSGs of East Asian Thuja were related to phenolic,alkaloid,and terpenoid synthesis,important stress-resistant genes and could increase plant resistance to external environmental stresses.This study discovered numerous aroma synthetic-related PSGs including terpene synthase(TPS)genes and lipid phosphate phosphatase 2(LPP2),associated with the synthetic aroma of T.sutchuenensis.Physiological indicators,such as the contents of soluble sugars,total chlorophyll,total phenolics,and total flavonoids were determined,which are consistent with the PSGs enrichment pathways associated with adaptive strategies in the five Thuja species.The results of this study provide an important basis for future studies on conservation genetics.

Drosophila Ortholog of Mammalian Immediate-Early Gene Npas4 is Specifically Responsive to Reversal Learning

Dear Editor,In dynamic environments,the memory system of the brain must be able to perceive and process conflicting experiences to reach an adaptive decision.In Drosophila,in contrast to consistent experiences,conflicting experiences trigger significantly increased Rac1 activity which mediates active forgetting [1].The ability to cope with conflicting experiences but not simple learning experiences is impaired in mutants of multiple autism-risk genes [2].

Mutations in Hemagglutinin of a Novel Avian-Origin H7N9 Virus That Are Critical for Receptor Binding Specificity

A novel avian-origin H7N9 influenza virus was discovered in March in China and has caused a total of131 people infected including 39 deaths in China as of June 9, 2013. Adaptation of avian viruses to efficiently infect humans requires the viral hemagglutinin（HA） binding switches from avian to human type receptors with help of some mutations in HA. As such it is critical for pandemic assessment to discover these mutations as hallmarks of adaptation. To continue our previous study of this novel H7N9 virus, we identified two sets of mutations in HA. The first set of mutations are present in the current circulating strains of 2013 H7N9 in China, and the second set are potential mutations that were found when compared to the HAs of previous human H7 subtype. These two sets of mutations exhibited unique features. The first group of mutations, on average, enhanced the HA binding to human type receptors whereas reduced that to avian types. Further the reduction of avian binding was almost three times of the increase of the human binding. The second group increased the binding to both human and avian types.But the increase in human types was almost three times of that in the avian types. Though different in their way of changing the binding preference, these two sets of mutations both contained more mutations to decrease the avian binding and increase the human binding than those that did the opposite. Our research highlighted the pandemic potential of this novel virus by showing the important mutations that could potentially help it to adapt to human hosts. Our findings offered new insights into the current state of evolution of this virus, which might be helpful for the continued surveillance of the emergence of H7N9 strains having the ability of human-to-human transmission.

Regulation of phagocytosis by TAM receptors and their ligands

The TAM family of receptors is preferentially expressed by professional and non-professional phagocytes,including macrophages,dendritic cells and natural killer cells in the immune system,osteoclasts in bone,Sertoli cells in testis,and retinal pigmental epithelium cells in the retina.Mutations in the Mertk single gene or in different combinations of the double or triple gene mutations in the same cell cause complete or partial impairment in phagocytosis of their preys;and as a result,either the normal apoptotic cells cannot be efficiently removed or the tissue neighbor cells die by apoptosis.This scenario of TAM regulation represents a widely adapted model system used by phagocytes in all different tissues.The present review will summarize current known functional roles of TAM receptors and their ligands,Gas 6 and protein S,in the regulation of phagocytosis.